Copper Electrolysis Equipment

— Copper Electrolysis Equipment: 99.99% Cathode Copper Refining Cell

Copper electrolysis equipment is an electrorefining cellhouse that dissolves a cast copper anode in a copper sulfate–sulfuric acid electrolyte and plates the copper back onto a permanent stainless steel cathode, taking blister or smelted secondary copper of 98% and above to cathode copper assaying Cu ≥ 99.99% with chemistry engineered to Cu-CATH-1 to BS EN 1978. YuSai Machinery engineers the whole equipment package — anode casting, lug trimming and bagging, the acid-proof cellhouse and 316L permanent cathode assemblies, the IGBT rectifier and busbar, electrolyte make-up, circulation and temperature control, continuous electrolyte purification with decopperising and nickel recovery, per-cell short-circuit detection, automatic cathode stripping and washing, anode slime collection and dewatering, and closed acid mist, nitrogen oxide and effluent control — around your own anode assay and your target cathode specification.

Product Overview

Copper electrorefining is an anodic process. A cast copper anode — normally 98–99% copper, cast from blister copper, anode copper or smelted secondary copper — is hung in an acidified copper sulfate electrolyte and made the positive electrode of a direct-current circuit. Copper dissolves from the anode as the Cu²⁺ ion, migrates through the electrolyte under the applied field, and is reduced back to metallic copper on the cathode as a dense, coherent deposit. What makes the separation work is the position of copper in the electromotive series: copper is more noble than nickel, iron, zinc and the other base metals that accompany it, so copper is the species that deposits preferentially, while the base metals stay in solution and the metals more noble than copper — gold, silver, platinum, palladium, selenium and tellurium — do not dissolve at all and report to the cell bottom as anode slime. Electrolysis is the only commercially proven route to 99.99% copper at industrial scale, because chemical and pyrometallurgical methods reach their limit within the last few hundred parts per million of impurity whereas electrodeposition selects for copper over everything it leaves behind.

The distinction from the two neighbouring processes decides which equipment a site actually needs, and the three are routinely confused. Electrorefining — what this equipment does — dissolves a solid metallic anode, so the anode is both the feedstock and the electrochemical reactant, and the whole design revolves around keeping that anode dissolving at a controlled rate. Electrowinning has no anode to dissolve: the copper is already in solution, in a leach liquor, a spent electrolyte, a strip solution or an etching waste, and the process is governed by how quickly ions can be brought to the cathode. Cementation uses no current at all and swaps the copper out of solution with scrap iron. A copper refinery frequently needs more than one of the three, and a cell specified for one duty does not do the work of another.

The controlling constraint on cathode quality is the electrolyte, not the rectifier. Two mechanisms decide whether the plant delivers Cu-CATH-1 copper on day sixty as well as on day one. The first is impurity accumulation. Nickel builds up in the circulating liquor and raises its viscosity and resistance; arsenic, antimony and bismuth are the elements that actually damage the cathode, because antimony and bismuth form a floating slime that adheres to the deposit and arsenic can co-deposit with the copper. All of them enter the liquor continuously as the anodes dissolve and none of them leaves it unless the plant takes them out, so the purification circuit has to be sized from the impurity accumulation rate that the anode assay implies. The second is physical: the solution film immediately against the cathode is stripped of copper ions as soon as current flows, and current density can only rise as fast as circulation and electrode geometry can replenish that film, otherwise the surplus current goes into roughening the deposit. Both constraints are answered at the design stage — by the surface area of the cathode, the spacing between the electrodes, the circulation rate through the cell, and the throughput of the purification circuit — and neither is answered by the rectifier.

Plant economics follow the same logic, and they are decided before the first cell is energised. Anode assay sets the electrolyte purification duty and the achievable current density. Anode thickness sets the scrap rate and the remelt load. Silver, gold, selenium and tellurium content sets what the slime is worth, and slime behaviour sets the electrode spacing and the cleaning schedule. A plant designed for one feedstock runs badly on another, which is why the flowsheet, the electrode configuration and the electrical parameters are derived from the customer’s own material rather than from a fixed catalogue model. The same is true of the electrical design: current efficiency of 92–97% is not a claim about the rectifier but a statement about how well the cellhouse holds its short-circuit rate, its contact resistance and its electrolyte chemistry, and it is measured per cathode rather than per cell.

The equipment package therefore spans the whole cellhouse rather than a single tank. Anode preparation and casting produce plates of consistent thickness and lug geometry, because a bowed or badly lugged anode changes the inter-electrode distance along its length and shows up later as a localised burn. The cellhouse is built from acid-proof modular cells with alignment fixtures, cell insulation and hooded covers. The cathode set is 316L stainless steel with insulating edge strips and a loop bar, prepared and stripped on a defined cycle. The rectifier, busbar and contact surfaces are designed around the electrical duty that the cathode area and current density imply. Electrolyte make-up, circulation, filtration, temperature control and level control hold the working window, and the purification circuit takes nickel, arsenic, antimony and bismuth out of the loop on a continuous basis. Cathode stripping, washing and bundling turn the deposit into dispatchable metal, anode scrap goes back to the furnace, and slime is dewatered and declared by metal content. Acid mist, nitrogen oxides and effluent are handled inside the same scope so that permitting is a design input rather than an afterthought.

What the package is sized around. Anode assay fixes the purification duty. Anode thickness fixes the scrap rate and the remelt load. Slime behaviour fixes the electrode spacing and the current density the cellhouse can hold. Target cathode specification fixes the stripping cycle, the washing regime and the assay frequency. Because anode assay, impurity profile, slime behaviour, target cathode specification and site conditions vary substantially between one plant and the next, YuSai does not sell this equipment from a fixed model list. The number of cells, the cathode area and spacing, the rectifier rating, the electrolyte volume, the circulation and cooling duty, the purification throughput, the stripping machine capacity and the effluent load are all derived from your material and your output target, and the resulting figures are issued in the process design package before manufacture begins. A pilot tankhouse validating a route on a few hundred kilograms a day and a production refinery are the same engineering exercise at different scales, and both are built from the same component family.

Key Facts

Cathode product: Cu ≥ 99.99% (4N) as standard, with chemistry engineered to Cu-CATH-1 to BS EN 1978, the chemistry basis the LME accepts for Grade A copper; 99.995% and 99.999% are produced on a two-stage refining configuration.
Total controlled impurity: held at 65 ppm or below, with every controlled element — Ag, As, Sb, Bi, Pb, Ni, Fe, S, Se, Te and O — individually limited and reported on the certificate of analysis.
Accepted anode: copper anodes assaying 98% Cu and above; 99% Cu and above is the preferred operating band, because the electrolyte purification duty rises as the anode assay falls.
The binding constraint is the electrolyte, not the rectifier. Arsenic, antimony and bismuth accumulate in the circulating liquor, and above their interference thresholds they co-deposit or form a floating slime that adheres to the cathode. Cathode grade is held by running the purification circuit hard, not by turning the current down.
Current density: 300 A/m² at the design point, inside a 220–320 A/m² working window, with up to 350 A/m² available in high-rate mode. The practical ceiling is set by anode quality and slime settling behaviour.
Cell voltage and current efficiency: 0.25–0.35 V per cell and 92–97% current efficiency, which is where the energy figure comes from — cell-level DC consumption runs 220–320 kWh per tonne of cathode across the design window and is calculated as cell voltage divided by cathode current efficiency.
Electrolyte: copper sulfate and sulfuric acid, held at Cu²⁺ 45–50 g/L, free H₂SO₄ 180–200 g/L and chloride below 0.1 g/L, at a controlled 58–65 °C.
Short circuits are the largest single efficiency loss in a tankhouse, and this equipment measures them instead of inferring them: per-cell voltage, per-cathode current and busbar contact condition are monitored continuously and the rectifier is interlocked to trip on an abnormal reading.
Slime is a product stream, not a waste stream. Anode slime at 0.2–1.0% of anode mass carries the gold, silver, platinum, palladium, selenium and tellurium, and is washed, filter-pressed, dried, weighed and assayed before it leaves the plant.
Configuration: cell count, cathode area, rectifier rating, electrolyte volume, purification duty, footprint, installed power and utilities are engineered to your anode assay, impurity profile, slime behaviour and target daily cathode output rather than taken from a catalogue of fixed models.

Product Core Selling Points

Short-circuit detection treated as the primary yield instrument. Every ampere that bypasses a cathode is cathode copper that is not produced, so the cellhouse is instrumented at the level where a short can actually be seen — per cathode, not only per cell. Per-cell voltage, per-cathode current, busbar contact resistance and cellhouse thermal imaging run continuously, the control system computes the instantaneous current-effective figure from the ampere-hours passed, and the rectifier is interlocked to trip on an abnormal reading rather than allowed to run a compromised campaign to completion.
Electrolyte purification designed with the cellhouse, not added afterwards. Nickel, arsenic, antimony and bismuth accumulate in the circulating liquor for as long as the cellhouse runs. The purification circuit — continuous bleed, decopperising, membrane separation, nickel recovery by crystallisation or solvent extraction with P204, P507 or C272, and ion exchange or adsorption where antimony and bismuth have to be held very low — is sized from the impurity accumulation rate implied by your anode assay, and purified acid returns to the cellhouse instead of being bled to effluent.
The whole electrolyte specification is published. Cu²⁺ 45–50 g/L, free H₂SO₄ 180–200 g/L, chloride below 0.1 g/L, temperature 58–65 °C, additive dosing under automatic control. Three of those numbers appear on no competitor page at all, and a buyer can benchmark the design against their own metallurgical assumptions before an enquiry.
A named product standard instead of a purity slogan. The cathode is engineered to Cu-CATH-1 to BS EN 1978 rather than advertised as a bare “99.99%”, and the certificate of analysis reports every controlled impurity element rather than a single copper figure.
Permanent 316L stainless steel cathodes. Consistent plate geometry, no starter-sheet loop to operate, no starter-sheet copper tied up in circulation, and a stripping cycle that returns the plate to the cell instead of consuming it. Where a customer’s specification rules out a stainless contact, the copper starter-sheet route is supplied instead, and the choice is recorded on the route sheet rather than left to stock on hand.
Energy per tonne stated with its basis. Cell-level DC consumption is given as 220–320 kWh per tonne of cathode copper across the design window and derived from cell voltage and current efficiency, so the figure can be checked against the electrochemical equivalent of copper instead of taken on trust.
Acid mist contained at the source. Cells are hooded and the headspace is collected under negative pressure, so sulfuric acid mist is captured where it forms rather than diluted into the working atmosphere, and the alkali scrubber closes the loop with a demister ahead of the stack.
Nitrogen oxide abatement for the plants that need it. Where nitrate-bearing liquor is processed on site, the reduction-absorption route converts nitrogen oxides to nitrogen, carbon dioxide and water so that the abatement stage does not create a secondary nitrite effluent.
Slime engineered as a revenue line. Anode bagging, slime transfer, filter pressing, drying, weighing and assay are designed for low-loss handling and sized on the assayed precious metal content, because on high-silver and e-waste-derived feedstock the slime stream is the second-largest revenue line in the plant.
Anode scrap returned to the melt. Between 12% and 20% of each anode’s weight remains as undissolved scrap; it is washed free of adhering slime and returned to the melting furnace rather than sold as discounted material.
Anode-first specification. Anode thickness sets the scrap rate and the remelt load, anode assay sets the purification duty, and slime settling behaviour sets the electrode spacing and the current density the cellhouse can sustain. All three are read from your assay before anything is quoted.
Both process routes available. Electrorefining for solid cast anodes and electrowinning for copper-bearing solutions, supplied separately or as a hybrid layout sharing one rectifier room, busbar and electrolyte purification circuit.
IGBT rectifier isolated from the acid atmosphere. The power supply sits in its own enclosed compartment clear of the cellhouse vapour, which is the largest single determinant of its service life in a copper refinery.
Materials selected stream by stream. Acid-proof cell bodies, 316L stainless steel cathode plates with insulating edge strips, lead alloy or coated titanium anodes where the duty is insoluble, titanium or copper-clad busbar, and acid-resistant bag and filter media.
A certificate of analysis with every campaign, not a purity claim. Anode assay, electrolyte assay, slime assay and product assay are produced in house, logged against the batch, and released with a retained reference sample.
Scope that closes the loop. Melting and anode casting, slime dewatering and drying, and the downstream precious metal circuit are inside the same scope, so the slime recovery targets are set alongside the cathode specification rather than negotiated after the plant is built.
Configuration to the assay, with the numbers written down. Cell count, cathode area, rectifier rating, electrode spacing, electrolyte volume, circulation and cooling duty, purification throughput, hood exhaust volume, scrubber duty and effluent load are all stated in the process design package before manufacture begins.

Application Scenarios

Copper smelters upgrading blister copper to marketable cathode. Operations that currently sell anode copper or blister at a treatment and refining charge discount, and want the premium that reference-grade cathode commands instead, with the slime retained as their own revenue rather than passed to the buyer of the anode.
Secondary copper recyclers. Plants that smelt cable, motor, radiator, brass and mixed-alloy scrap into black copper or crude copper and need a route from a discounted intermediate to metal that trades against the reference market price. Secondary anodes carry the heaviest impurity load and are the single most common feedstock for this equipment.
E-waste and printed circuit board recyclers. Facilities that already concentrate copper from boards, connectors and mixed metal fractions, and that need a refining step which converts a copper-bearing concentrate into sellable cathode while capturing the gold, silver, palladium and selenium that the copper carries.
Precious metal refineries using copper as a collector metal. Operations that deliberately melt precious metal residue with copper so that gold, silver and the platinum group metals collect into a castable anode; the cellhouse then delivers the copper as cathode and the values as a slime concentrate.
Copper wire, rod and strip producers. Manufacturers who want to control their own cathode supply rather than buy cathode on the market, particularly where their own process scrap and offcuts can be melted and refined back into specification metal.
Integrated mining and smelting operations. Sites running a concentrator and a smelter that want the refining step on the same complex so the anode does not leave the property and the slime is processed in house.
Copper anode slime processors. Operations that already treat slime and want the upstream cellhouse that generates it, so the slime grade fed to the precious metal circuit is under their own control rather than set by a third-party smelter.
Toll refining and consignment operations. Plants that run customer-owned copper as discrete campaigns with their own mass balance, parameter log and retained sample, where the batch record is as important as the cathode itself.
Copper alloy and brass foundries with a refining department. Works that generate alloy scrap, sweeps and machining residues, and want to return that copper to prime metal instead of selling it downgraded.
Electroplating, etching and surface finishing operations. Plants with copper-bearing strip liquors, etchants and rinse waters that need the copper taken out — recovered as cathode or as powder rather than discharged as a regulated waste.
Battery, catalyst and chemical manufacturers. Industrial sites that accumulate copper-bearing residues and want the recovery step inside their own compliance envelope instead of exporting the metal as waste.
Pilot, laboratory and university metallurgy facilities. Small installations used to establish the behaviour of a particular anode on a few hundred kilograms before a production tankhouse is committed, and to train operators on the electrode handling and electrolyte discipline the process demands.
Operations driven by product specification rather than scale. Buyers whose customer or exchange requires cathode produced on a certified electrorefining route with a full certificate of analysis, and for whom the process route itself is part of the deliverable.
Plants preparing for a capacity increase. Existing refineries whose cellhouse, busbar, rectifier or purification circuit is the bottleneck, where an additional modular cell bank and the purification throughput to match it restores the plant’s nameplate without rebuilding the building.

Applicable Raw Materials

Each feed below enters the circuit at the point its composition requires. The two numbers that decide the design are the anode copper assay, which sets the electrolyte purification duty, and the precious metal content, which sets both the slime revenue and the electrode spacing that the slime settling behaviour allows. Feeds that arrive as powder, cement, sludge or filter cake are melted and cast into anodes, or routed to the electrowinning path where they cannot be agglomerated. Output is stated for each feed.

Blister copper and anode copper from smelting. Plates cast directly from the converter or the anode furnace, normally assaying 98–99% copper with cast lugs; the classic electrorefining feedstock, and the material for which current density, electrode spacing and slime behaviour are best understood. Output: Cu ≥ 99.99% cathode meeting Cu-CATH-1 chemistry; anode slime concentrate; anode scrap returned to the furnace.
Fire-refined anode copper. Higher-grade plates at 99.2–99.7% copper with 0.3–0.8% impurity, produced where the upstream smelt can hold the impurity load down; a lower anode assay is not a defect, it simply moves work from the smelter to the purification circuit. Output: Cu ≥ 99.99% cathode; reduced slime and purification load.
Crude copper from converting and black copper. 98.5–99.5% copper carrying 0.5–1.5% impurity, including the tin, lead and nickel that secondary smelting introduces; pre-treatment to remove tin and lead and a reduction step to remove free oxygen are applied before anode casting. Output: Cu ≥ 99.99% cathode; tin and lead removed upstream as slag or fume.
Smelted secondary copper. Copper anodes cast from copper alloy particles, mixed metal powder from cable and board processing, granules, shavings and machining swarf after melting and casting. Output: Cu ≥ 99.99% cathode; purification sized for the higher impurity load that secondary anodes carry.
Copper fractions from printed circuit board and WEEE processing. Copper concentrate, mixed metal powder and copper-rich residues from mechanical and hydrometallurgical board treatment, melted and cast into anodes or leached for the electrowinning path. Output: Cu ≥ 99.99% cathode; gold, silver and palladium recovered through the slime.
Copper cement and cemented copper. Copper displaced from solution by scrap iron, arriving as a fine wet powder; briquetted or melted and cast where the material can be agglomerated, and leached and electrowon where it cannot. Output: Cu ≥ 99.99% cathode; iron removed in the melt or in the leach.
Copper sludge, filter cake and press residue. Wet filtration products from plating, etching and effluent treatment circuits, dried and consolidated before melting. Output: Cu ≥ 99.99% cathode; water and organics removed before casting.
Copper powder and atomised copper. Fine powder from atomisation, cementation and reduction routes; melted and cast where a stable anode plate can be produced from it, and routed to electrolytic powder production where fine powder is the target product. Output: Cu ≥ 99.99% cathode, or electrolytic copper powder.
Copper-bearing smelting residues and flue dust. Copper-containing residues and dusts recovered from gas cleaning and slag treatment circuits, melted with the secondary anode charge. Output: Cu ≥ 99.99% cathode; volatile impurities removed in the furnace.
Copper-bearing solutions. Spent copper electrolyte, acid etching and micro-etching waste liquid, copper sulfate and copper chloride process solutions, and copper-loaded leach and solvent extraction liquors, taken through electrowinning rather than electrorefining. Output: high-purity cathode copper; regenerated etchant or recycled acid.
Copper–precious metal alloy scrap. Au–Cu, Ag–Cu and Pd–Cu alloy scrap and brazing alloys, where the copper is cast into anodes and the precious metal content reports to the slime instead of entering the electrolyte. Output: Cu ≥ 99.99% cathode; precious metal concentrate from the slime.
Copper anode slime after copper removal. Slime that has already been decopperised, returned to the circuit where the residual copper is worth recovering before the precious metal circuit takes the balance. Output: recovered cathode copper; slime advanced to precious metal refining.
Consigned and toll-refining lots. Customer-owned material run as a discrete campaign with its own mass balance, parameter log and retained sample, cast and refined on a per-lot basis. Output: Cu ≥ 99.99% cathode with a lot-specific mass balance and certificate.

Pre-treatment requirements. Material carrying significant tin, lead, solder or aluminium is treated before electrolysis, because these elements form compounds that contaminate the electrolyte and degrade the cathode. Oil, grease, plastics and organic residue are removed before melting so that the anode does not come out porous and carbon-bearing. Heavily oxidised material takes a reduction step to remove free oxygen before casting. Feedstock too fine or too friable to cast into a stable plate is routed to the leaching and electrowinning path instead, which is the correct route for that material rather than a compromise.

Finished Products

The line is configured around the product form the customer sells, holds or re-uses, from cathode plates in bundle form through to a bagged slime concentrate and a nickel by-product. Where the customer already operates a melting and assay shop, the scope is delivered with the cellhouse, stripping, washing and slime dewatering only; where it does not, melting, sampling and assay are included.

Cu-CATH-1 cathode copper. The primary output, stripped from the permanent cathode, washed and bundled, assaying Cu ≥ 99.99% with chemistry engineered to Cu-CATH-1 to BS EN 1978 and each controlled impurity element limited and reported. Output: certificated cathode copper in bundle form.
Cathode copper at 99.995% to 99.999%. Produced on a two-stage refining configuration where the customer’s specification, customer or end use calls for the higher standard, with a separate certificate of analysis. Output: high-purity cathode copper with an element-by-element certificate.
Stripped cathode plate and cut cathode. The as-stripped plate before shearing, supplied where the customer prefers to shear, bundle or melt the metal in its own downstream operation. Output: cathode plate at declared weight and assay.
Electrolytic copper powder. Produced on the powder configuration for buyers who sell fine copper powder rather than plate. Output: electrolytic copper powder at the declared particle specification.
Anode slime concentrate. The insoluble residue from the anode, washed free of entrained electrolyte, filter-pressed, dried, weighed and declared by metal content, containing the gold, silver, platinum, palladium, selenium and tellurium that the anode carried. Output: dried, assayed slime concentrate routed to precious metal refining.
Silver-bearing slime fraction. The high-silver fraction declared separately where the anode silver content justifies it, delivered as an intermediate to the silver refining circuit or to a customer who refines silver in house. Output: Ag-rich slime fraction at declared silver content.
Gold and platinum group metal concentrate. The gold, platinum, palladium and associated PGM content of the slime, concentrated and declared by metal content before it leaves for the precious metal circuit. Output: PGM-bearing concentrate declared by metal content.
Anode scrap returned to the melt. Between 12% and 20% of each anode’s weight left undissolved, washed free of adhering slime and returned to the melting furnace rather than sold as discounted material. Output: remelt stock returned to anode casting.
Nickel sulfate and nickel carbonate. Nickel taken out of the circulating electrolyte by membrane separation, crystallisation or solvent extraction with P204, P507 or C272, supplied as a saleable by-product instead of a bleed to effluent. Output: nickel sulfate or nickel carbonate by-product.
Recovered copper from the purification circuit. Copper removed from the electrolyte side stream by decopperising and cyclone electrowinning, returned to the anode charge or sold as cathode or powder. Output: recovered copper returned to the circuit.
Purified acid returned to the cellhouse. Electrolyte that has been stripped of copper and nickel and returned to the circulating liquor, holding the free acid balance and closing the loop. Output: purified acid returned to the cellhouse.
Compliant off-gas and effluent. Acid mist captured at the hood, scrubbed with alkali liquor and discharged through a demister; nitrogen oxides abated where nitrate-bearing liquor is processed; process water neutralised, settled, filtered and reused, with the hydroxide sludge returned for metal recovery. Output: compliant discharge with the scrubber liquor analysed and logged.
Certificate of analysis, mass balance and retained sample. Every campaign is released with the anode assay, the electrolyte assay, the slime assay and the cathode assay, the parameter log for the campaign, and a retained reference sample held for the warranty period. Output: batch record and certificate of analysis.

Copper Electrolysis Equipment Process Flow

The nine stages below form the standard copper electrolysis equipment sequence, from the assay that fixes the whole design through to a bundled cathode and a declared slime concentrate. Step 1 and Step 6 are the two stages that decide whether the plant holds its specification: the anode assay taken at Step 1 fixes the purification duty, and the impurity control applied at Step 6 is what keeps arsenic, antimony and bismuth out of the cathode once the cellhouse is running. Engineering setpoints — current density, cell voltage, electrode spacing, electrolyte composition and temperature, circulation rate, additive dosing, bleed rate and stripping cycle — are fixed during process design against your own anode assay.

Copper electrolysis equipment process flow — from a cast copper anode to Cu-CATH-1 cathode copper, with electrolyte purification, slime harvest and off-gas control inside the same circuit.

Steps 1 — Anode Assay and Electrode Scheduling. The lot is weighed, sampled and assayed before anything is charged, and the assay is what the equipment is then specified against. Copper is determined by titration or by a combination of fire assay and ICP-OES, the precious metal suite is determined so the slime credit can be priced, and the full impurity suite — nickel, arsenic, antimony, bismuth, lead, iron, selenium, tellurium and chloride — is determined because those are the elements that decide the purification duty and the achievable current density. Anode thickness and cast weight are measured, because a thinner anode raises the scrap rate and the remelt load while a thicker one raises the cell inventory. From those numbers the cellhouse schedule is fixed: the anode and cathode count per cell, the electrode spacing the slime behaviour allows, the target current density, the stripping cycle that keeps the deposit at specification, and the throughput the purification circuit has to handle when the impurity concentration reaches its steady-state value. Reagent and utility input: sample splitting and riffling equipment, titration apparatus, fire assay and ICP-OES, chloride determination, anode weighing and thickness gauges. Output: full anode and impurity assay; anode and cathode schedule; purification duty for the campaign.

Steps 2 — Anode Casting, Lug Trimming and Bagging. The anode is the feed and the electrode at the same time, so how it is cast determines both how evenly it dissolves and how evenly the cell distributes current. Material that is already metallic is melted under flux and cast in a mould set sized to the anode envelope the cell accepts, with the cast weight, thickness and lug geometry recorded against the lot number. The plate is then straightened, the lugs are trimmed so that both contact faces sit flat on the busbar, and the surface is checked for shrinkage voids and surface defects which would otherwise concentrate current at a single spot and burn the cathode opposite. Every anode is wrapped in an anode bag before it goes near the cell. The bag is a functional component rather than a finishing detail: the slime produced as the anode dissolves is insoluble and, left free, migrates to the cathode where it contaminates the deposit and drags the assay down. The bag retains it at the anode face and turns it into a recoverable stream. Material arriving as powder, cement, sludge or filter cake is dried, fluxed and consolidated into a cast anode rather than fed loose. Reagent and utility input: melting furnace with matched crucible and flux, anode mould set and cooling station, lug trimming and straightening station, anode weighing, acid-resistant anode bag or membrane material. Output: straight, correctly lugged and bagged anodes at a recorded weight and geometry; route sheet and lot record.

Steps 3 — Permanent Cathode Preparation and Cell Loading. The cathode is the product surface, and it is prepared to hold a deposit that strips cleanly. 316L stainless steel permanent cathode plates are inspected for flatness and surface condition, degreased where the plate is new or has been reconditioned, fitted with insulating edge strips that keep the deposit off the plate edges, and mounted on the loop bar or hanger that carries it to the busbar. Where a customer specification rules out a stainless contact in the electrolyte, copper starter sheets produced on mother blanks are fitted instead, and the choice is recorded on the route sheet. Anodes and cathodes are then loaded into the cell in the alternating arrangement, one cathode between each anode pair, and the spacing is set with an alignment fixture so that the distance is uniform along the full immersed length. Contact is the part of the job that is hardest to correct later: busbar contact faces are cleaned and dressed on both sides, the plate is checked for verticality and for a straight top edge, and the electrode set is checked for alignment before the cell is filled, because a resistive contact or a bowed plate produces a localised current concentration that is difficult to diagnose once the hood is closed. Reagent and utility input: 316L stainless steel cathode plates with edge strips and loop bars, or copper starter sheets with mother blanks, plate straightening and flatness gauges, degreasing agents, spacing and alignment fixtures, busbar cleaning and contact dressing tools. Output: prepared cathode assemblies with verified flatness, spacing and contact; loaded cell ready for electrolyte.

Steps 4 — Electrolyte Make-Up and Circulation. The electrolyte is copper sulfate and sulfuric acid in water, and the working window is narrow enough that it is set in process design and then held by measurement rather than by operator judgement. Copper as Cu²⁺ is held at 45–50 g/L and free sulfuric acid at 180–200 g/L; the acid is what makes the liquor conduct and what keeps the copper sulfate in solution at the working temperature, and the copper tenor is what keeps the deposit compact instead of powdery. Chloride is held below 0.1 g/L because above that level the deposit roughens and silver behaves differently in the cell. The liquor is brought to 58–65 °C, a band set from below by the conductivity and the deposition kinetics and from above by evaporation and reagent loss, and held there by heat exchange or immersion heating on a control loop. Circulation runs continuously through the cellhouse, entering along the electrode row and leaving from the top so that the denser copper-rich liquor does not stratify at the bottom of the tank and leave the lower part of the cathode starved. Filtration ahead of the cell removes suspended solids that would otherwise blind the anode bags and plate onto the cathode. Additives are dosed automatically, monitored against current efficiency and electrolyte condition, because the additive balance is one of the variables that decides whether the deposit comes off as a smooth plate or as nodules. Reagent and utility input: copper sulfate and sulfuric acid with metered dosing, chloride dosing, additive dosing on automatic control, make-up vessel with agitation and fume extraction, circulation pumps and piping, heat exchanger or immersion heater with temperature control, filtration, per-cell flow control, demineralised water. Output: electrolyte at Cu²⁺ 45–50 g/L, free H₂SO₄ 180–200 g/L and Cl⁻ below 0.1 g/L, held at 58–65 °C and circulated uniformly; make-up and analysis record.

Steps 5 — Controlled Current Electrolysis and Short-Circuit Control. The rectifier applies controlled direct current to the electrode set, copper dissolves from the anode and an equivalent quantity deposits on the cathode, and the cellhouse runs at a cathode current density of 300 A/m² at the design point inside a 220–320 A/m² window. Cell voltage sits at 0.25–0.35 V per cell, and current efficiency at 92–97%; the two are linked, because a short circuit or a resistive contact does not stop the current, it routes the current around the cathode it was meant to build. This is why short-circuit control is instrumented at the level where a fault is visible. Per-cell voltage is monitored continuously, individual cathode currents are checked so that a single shorted cathode can be identified inside a cell whose overall voltage still looks normal, busbar and contact temperatures are monitored for a resistive joint, and cellhouse thermal imaging is used to locate the hot electrode. The control system computes the current-effective figure from the ampere-hours passed against metal produced and raises an alarm when it drifts, and the rectifier is interlocked to trip rather than allowed to run a compromised campaign. Correcting a rough or dark deposit is done by reducing current density and checking spacing, contact and temperature in that order. Reagent and utility input: IGBT rectifier with current and voltage regulation, per-cell voltage monitoring, per-cathode current measurement, busbar contact temperature monitoring, thermal imaging, ampere-hour integration and current efficiency calculation, PLC interlock with alarm log. Output: cathode deposit built to its design thickness at 92–97% current efficiency; short circuits identified and cleared within the cycle; per-batch electrical record.

Steps 6 — Electrolyte Purification and Impurity Bleed. Every impurity that dissolves at the anode stays in the circulating liquor and accumulates there for as long as the cellhouse runs, so the electrolyte has to be purified continuously rather than cleaned up after a campaign. A side stream is drawn from the circulating electrolyte on a bleed schedule set by the accumulation rate implied by the anode assay, and the elements that damage cathode quality are taken out in sequence. Copper is removed first — by a liberator cell, by cyclone electrowinning or by a dedicated electrowinning stage — because recovering it before the nickel stage keeps the copper out of the by-product and returns value to the circuit. Nickel is then separated, by membrane separation followed by evaporation and crystallisation to nickel sulfate or nickel carbonate, or by solvent extraction with P204, P507 or C272, and the choice is made on the nickel tenor and on what form of by-product the site can sell. Arsenic, antimony and bismuth are the elements that actually decide the cathode assay: antimony and bismuth form a floating slime that adheres to the deposit and rides into the product, and arsenic can co-deposit with the copper, so electrolyte purification is the control point at which cathode grade is defended. Where antimony and bismuth have to be held at very low concentration, ion exchange or adsorption is applied to a further treated stream. The purified acid returns to the cellhouse, so the bleed closes as a loop instead of leaving as effluent. Reagent and utility input: bleed pumping and flow control, liberator cell or cyclone electrowinning unit for decopperising, membrane separation, evaporator and crystalliser, solvent extraction with P204, P507 or C272 where selected, ion exchange or adsorption for antimony and bismuth, electrolyte sampling and analysis for Cu, Ni, As, Sb, Bi, Fe and acid. Output: purified acid returned to the cellhouse holding the free acid balance; copper recovered to the circuit; nickel sulfate or nickel carbonate by-product; arsenic, antimony and bismuth held below their interference thresholds; assay trend and bleed record.

Steps 7 — Cathode Stripping, Washing and Bundling. When the deposit has taken up its design load — judged from the ampere-hours passed against the plate weight and confirmed by weighing the drained cathode — the cell is taken out of service and the cathode is lifted. The plate is moved to the stripping station, where the deposit is peeled from the stainless steel surface; the plate is then cleaned, checked for flatness and surface condition, and returned straight to the cell rather than being set aside, because a spare cathode in the rack is a cathode not producing. The stripped cathode is washed to remove adhering electrolyte and copper sulfate, and this is a specification step rather than housekeeping: residual copper sulfate on the plate surface is a rejection point in most cathode specifications, and the wash water carries copper that belongs back in the circuit rather than down the drain, so it is collected and returned. The washed cathode is then sheared or cut to the customer’s preferred size, bundled, strapped and weighed for dispatch. Stripping cycles run on a 7 to 14 day rhythm across the cellhouse so that no single cathode is left to grow past the deposit quality it can hold, and the stripping schedule is a design output rather than a production decision taken on the day. Reagent and utility input: cellhouse lifting equipment, cathode stripping machine with plate handling, plate washing station with collected wash water, plate cleaning and flatness inspection, cathode shearing or cutting, bundling and strapping, weighing and marking. Output: washed and bundled cathode copper at the certified assay; wash water and stripping residues returned to the circuit; cleaned plates returned to the cell.

Steps 8 — Anode Scrap Return and Slime Harvest. Two streams close here, and both carry value that a plant that only counts cathode output leaves on the floor. Each anode dissolves over roughly 21 to 28 days depending on thickness and current density, and between 12% and 20% of its original weight remains as an undissolved remnant; the remnant is lifted, washed free of adhering slime so the slime does not report to the melt, and returned to the melting furnace to be cast into fresh anodes, so the copper circulates internally instead of being sold as discounted scrap. The anode bag is then opened and its contents harvested. Slime is generated at 0.2–1.0% of anode mass and is where the anode’s gold, silver, platinum, palladium, selenium and tellurium have all reported; the slime is washed free of entrained electrolyte, transferred to a filter press, dewatered, dried, weighed and assayed, and every lot is declared by metal content before it leaves the plant. On high-silver feedstock the slime fraction is separated and declared on its own because the silver tenor changes how the downstream circuit is run. Cell floors and bag cloth are washed on the same schedule so that the material that settled out of the circuit is recovered rather than hosed away, and the cell is inspected and returned to service. Reagent and utility input: anode lifting and scrap washing station, scrap return to the melting furnace, anode bag opening and slime washing, slime pump, filter press or vacuum filtration, drying oven, slime weighing and assay, cell floor and bag cloth washing with collected liquor. Output: anode scrap remelted into fresh anodes; washed, dried and assayed slime concentrate declared by metal content; silver-rich fraction separated where required; cleaned cell returned to service.

Steps 9 — Acid Mist, Nitrogen Oxide and Effluent Control. A copper cellhouse generates sulfuric acid mist at the electrolyte surface, where oxygen and hydrogen bubbles burst and throw fine droplets into the headspace, and it generates nitrogen oxides wherever nitrate-bearing liquor is processed on the same site. Both are handled inside the equipment scope rather than after it. Cells are hooded and the headspace is drawn off under negative pressure, so the mist is captured at the point of generation instead of being diluted into the working atmosphere; the extraction air passes through an alkali scrubbing tower with NaOH scrubbing liquor, packing arranged in two beds with redistribution between them and a demister ahead of the stack, and the scrubber liquor is analysed and logged so that the scrubbing duty can be verified rather than assumed. Where nitrate-bearing solutions are processed, a reduction-absorption stage converts nitrogen oxides to nitrogen, carbon dioxide and water, which keeps the abatement stage from creating a secondary nitrite effluent of its own. Wash water, spent scrubber liquor and the liquors that cannot be returned to the circuit go to neutralisation, sedimentation and filtration, and the process water is recovered for reuse; the hydroxide sludge is routed back for metal recovery instead of being discarded. Working area conditions and the stack are monitored against the site’s own discharge limits and occupational exposure limits. Reagent and utility input: cell covers and hooding, exhaust ducting and fan under negative pressure, alkali scrubbing tower with demister, NaOH scrubbing liquor and dosing, reduction-absorption unit for nitrogen oxides where nitrate-bearing liquor is processed, neutralisation reactor, sedimentation and filtration, process water recovery, stack and workplace monitoring. Output: acid mist captured at the source and scrubbed; nitrogen oxides abated where present; process water neutralised and reused; hydroxide sludge returned for metal recovery; compliant discharge with the monitoring record retained.

Product Structure (Main Equipment)

The equipment package is assembled from the six groups below. Materials of construction are selected for hot acid sulfate duty and for the small quantity of electrolyte that inevitably escapes the circuit: cell bodies in acid-proof polymer or protected concrete, 316L stainless steel for the permanent cathode plates, lead alloy or coated titanium for the insoluble anodes, acid-resistant filter and bag media for the slime circuit, and alkali-resistant linings wherever scrubbing liquor is handled.

Anode preparation, casting and handling

Copper melting and anode casting furnace. Induction or resistance furnace with a matched crucible, flux formulation and anode mould set, used to melt blister copper, smelted secondary copper, cement and copper-bearing residues into anode plates of controlled thickness, geometry and weight. Output: cast anode plates with a recorded weight, thickness and assay.
Anode mould set and cooling station. Moulds sized to the anode envelope the cell accepts, with a controlled cooling station so the plates are cast without shrinkage voids and come out straight enough to hang at a uniform distance from the cathode. Output: dimensionally consistent anode plates.
Lug trimming and anode straightening station. Forming and trimming station that produces a uniform lug contact geometry on every plate, with a straightening press that removes the bow introduced by casting and handling. Output: flat anodes with matched lug contacts.
Anode weighing and identification. Weighing station and plate marking so that each anode is traceable from the melt to the cell and the anode mass balance closes at the end of the campaign. Output: per-anode weight record.
Anode bag and membrane supply. Acid-resistant bag or membrane assemblies fitted around each anode to retain the insoluble slime at the anode face and keep it out of the cathode deposit, supplied with the fitting jigs and the replacement schedule. Output: contained anode slime with the cathode deposit protected.
Anode scrap washing and return station. Collection, washing and handling for residual anode plate, hanger residues and cell-bottom material, all of which are returned to the melting station rather than sold. Output: washed remelt stock returned to anode casting.

Cellhouse and electrode assemblies

Electrolytic cell body. Acid-proof modular cell in polymer or in protected concrete with a corrosion barrier, sized to the electrode set and to the electrolyte volume the design allows, with cell insulation, drainage and a sealed base so the cell can stand over a containment tray without leaking. Output: the primary process vessel.
Cell hood and cover assemblies. Hooded covers with acid mist collection tappings, arranged so the headspace is collected under negative pressure while the electrodes remain accessible for inspection and lifting. Output: contained acid mist with a workable cellhouse.
Permanent cathode plate set. 316L stainless steel plates with insulating edge strips and loop bars, supplied as a matched set with hanger bars, sized to the cathode area the current density requires. Output: the deposition surface and the deposit carrier.
Cathode preparation station. Plate straightening, flatness checking, degreasing and edge strip fitting station that brings a plate back to specification before it returns to the cell. Output: prepared plates returned to service.
Copper starter sheet option. Mother blanks, peeling, flattening and lug attachment equipment for the starter sheet route, supplied where a customer specification rules out a stainless contact in the electrolyte. Output: copper starter sheets ready for loading.
Insoluble anode option for the electrowinning route. Lead alloy anodes or coated titanium anodes with the fittings they require, fitted where the copper enters as a solution rather than as a cast plate. Output: insoluble anodes for the electrowinning configuration.
Electrode spacing and alignment fixtures. Insulated retaining combs, spacer bars and alignment jigs that hold every electrode at the design inter-electrode distance along its full immersed length. Output: uniform spacing and even current distribution.
Busbar set, clamps and cell insulation. Busbar sized to carry the cellhouse current with a low voltage drop across the section, with compression clamps, machined contact faces, insulated supports and per-cell insulation that lets the cells be monitored independently. Output: even current distribution and a measurable base for fault detection.
Cellhouse lifting equipment. Handling gear for electrodes, covers and plates, designed so that inspection, stripping and loading do not depend on improvisation and the plates are never dragged across the cell edge. Output: safe, repeatable electrode handling.
Containment tray and cell floor drainage. Acid-resistant containment under the cells that holds any electrolyte spill for recovery rather than letting it reach the floor drain. Output: spill containment with recoverable liquor.

Electrolyte preparation, circulation and purification

Electrolyte make-up vessel. Agitated vessel with metered copper sulfate and acid dosing and fume extraction in which the electrolyte is made up to the working copper tenor and free acid band. Output: electrolyte made up to specification with a recorded make-up analysis.
Electrolyte circulation system. Acid-resistant pumps, piping, head tank and per-cell flow control that keep the electrolyte moving through the cellhouse, refresh the boundary layer at the cathode face and prevent the denser copper-rich liquor from stratifying in the tank. Output: uniform electrolyte composition and a sustained mass-transfer rate.
Temperature control loop. Heat exchanger or immersion heating with a temperature probe and controller that holds the electrolyte at 58–65 °C, together with the cooling duty that keeps the band when the cellhouse is running hard. Output: electrolyte held in the working temperature band.
Electrolyte filtration. Cartridge, bag or disc filtration ahead of the cell that removes suspended solids which would otherwise blind the anode bags, plate onto the cathode and contaminate the deposit. Output: particle-free electrolyte.
Automatic level and concentration control. Level sensing with metered make-up addition, matched to the liquor that leaves with the extraction air, so the cellhouse neither runs down in level nor drifts in concentration between shifts. Output: level and concentration held inside the control band.
Additive dosing system. Metered dosing for the electrolyte additives that govern deposit morphology, monitored against current efficiency and electrolyte condition rather than added by habit. Output: stable deposit morphology and a dosing record.
Electrolyte analysis station. Sampling and analytical equipment for Cu, Ni, As, Sb, Bi, Fe, chloride and free acid on the circulating liquor, so the bleed decision is taken on measurement rather than on appearance. Output: electrolyte assay trend used to set the bleed schedule.
Bleed, decopperising and liberator circuit. Bleed pumping with a liberator cell, cyclone electrowinning unit or dedicated electrowinning stage that takes the copper out of the side stream before the nickel stage sees it. Output: copper recovered and returned to the circuit.
Nickel recovery system. Membrane separation, evaporator and crystalliser, or solvent extraction with P204, P507 or C272, sized to the nickel accumulation rate and configured to the by-product form the site can sell. Output: nickel sulfate or nickel carbonate by-product.
Impurity polishing stage. Ion exchange or adsorption for the antimony and bismuth fraction where the cathode specification requires those elements to be held at very low concentration in the working liquor. Output: antimony and bismuth held below the interference threshold.
Purified acid return. Return line and blending control that puts the purified acid back into the cellhouse and closes the electrolyte loop. Output: purified acid returned to the cellhouse.

Harvesting, electrolyte regeneration and finishing

IGBT rectifier. High-frequency switching rectifier with current and voltage regulation, sized to the cellhouse current the cathode area and current density imply, with 12-pulse or 24-pulse configuration and an optional polarity-reversal pulse mode. Output: controlled direct current to the cellhouse.
Enclosed rectifier room and cooling. The rectifier and its cooling are housed clear of the cellhouse atmosphere, so acid vapour does not attack the power electronics, which is the largest single determinant of service life in a copper refinery. Output: extended power supply service life.
PLC control and operator interface. Touch-screen panel controlling the rectifier, circulation, heating, dosing and the purification circuit, running the operating sequence with a manual mode for intervention and a per-cell overview for the operator. Output: repeatable operation and reproducible campaigns.
Per-cell voltage monitoring and alarm. Continuous measurement of the voltage across every cell with individual alarms, because a single shorted cathode inside a cell is invisible in the overall cellhouse total. Output: faults located at cell level.
Per-cathode current measurement and short-circuit detection. Individual cathode current measurement, busbar contact monitoring and cellhouse thermal imaging, brought together so a short circuit is identified at the cathode that carries it. Output: short circuits found and cleared rather than run to harvest.
Current efficiency calculation and parameter logging. Ampere-hour integration against cathode mass produced, with the electrical and process record of every campaign stored for retrieval, so a drift in current efficiency can be traced to the cell, the contact, the electrolyte or the anode. Output: instantaneous current efficiency figure and a per-batch process record.
Interlocks. The rectifier is stopped automatically on an abnormal current, voltage, contact temperature or electrolyte reading rather than allowed to run a compromised campaign to completion. Output: a fault that stops the cellhouse instead of a batch that fails the assay.

Cathode handling and finishing

Cathode stripping machine. Semi-automatic or automatic stripping station that peels the deposit from the permanent plate with controlled plate handling, verticality checking and a deposit path that keeps the cathode intact. Output: stripped cathode plate with the stainless plate recovered undamaged.
Cathode washing station. Washing station with collected wash water in which the stripped cathode is rinsed free of adhering electrolyte and copper sulfate before bundling, because residual sulfate on the surface is a rejection point in most cathode specifications. Output: washed cathode and wash water returned to the circuit.
Cathode shearing, bundling and strapping. Cutting to the customer’s preferred size with bundling, strapping, weighing and marking for dispatch. Output: dispatch-ready cathode bundles with a weight and assay record.
Plate reconditioning and spares. Plate inspection, straightening, edge strip renewal and a standing supply of plates so that the cathode set stays at design area instead of degrading as plates are damaged. Output: cathode set held at design area and specification.
Anode scrap washing and packing. Washing and packing station for residual anodes and hanger residues, with the wash liquor collected so that entrained slime returns to the slime circuit rather than to the melt. Output: clean remelt stock and slime returned to the circuit.

Slime collection, dewatering and environmental control

Slime collection and transfer. Slime pump, transfer piping and handling arranged for low-loss movement, because the slime is the highest-value stream per tonne in the plant and is the second-largest revenue line on high-silver feedstock. Output: slime transferred to dewatering without loss.
Filter press and vacuum filtration. Filter press or vacuum filtration for the anode bag contents, sized to the slime generation rate, with filtration clarified enough that the liquor returns to the circuit. Output: dewatered slime cake and clarified liquor returned to the circuit.
Slime drying, weighing and packaging. Drying oven, weighing and packaging for the slime concentrate ahead of assay and dispatch. Output: dried slime concentrate declared by metal content.
Slime and product assay station. Fire assay, ICP-OES, sample preparation and a dedicated fume hood, so the anode, electrolyte, slime and cathode assays for a campaign are produced in house on the day the campaign closes. Output: certificate of analysis issued against the batch.
Acid mist hooding and extraction. Hooded cells with collection ducting and a fan run under negative pressure, so that any leakage is inward and the mist is captured where it forms. Output: acid mist contained at the source.
Alkali scrubbing tower with demister. Packed scrubbing tower with NaOH scrubbing liquor, packing arranged in two beds with redistribution and a demister ahead of the stack, with the scrubber liquor analysed and logged. Output: scrubbed off-gas with a verifiable scrubbing record.
Nitrogen oxide abatement stage. Reduction-absorption unit that converts nitrogen oxides to nitrogen, carbon dioxide and water where nitrate-bearing liquor is processed on site, so the abatement route does not create a secondary nitrite effluent. Output: abated off-gas meeting the site discharge limit.
Effluent neutralisation, sedimentation and reuse. Neutralisation reactor with sedimentation and filtration for the wash water and spent liquors that cannot be returned to the circuit, with the process water recovered for reuse and the hydroxide sludge routed back for metal recovery. Output: compliant effluent and recovered residual metal.

Product Features

Short-circuit detection instrumented at cathode level. Per-cell voltage, per-cathode current, busbar contact temperature and cellhouse thermal imaging run together, because a single shorted cathode inside a cell whose overall voltage still looks normal is the failure mode that quietly destroys a campaign’s current efficiency. Faults are located, not merely reported.
Current efficiency computed, not assumed. Ampere-hour integration against cathode mass produced gives the operating figure continuously, and the rectifier is interlocked to trip on an abnormal reading. A drifting campaign stops at the cellhouse rather than being discovered in the assay report.
Full electrolyte specification published. Cu²⁺ 45–50 g/L, free H₂SO₄ 180–200 g/L, chloride below 0.1 g/L, 58–65 °C, additive dosing under automatic control, per-cell flow control. Buyers can benchmark the design against their own metallurgical assumptions before an enquiry.
Energy per tonne with a stated basis. Cell-level DC consumption of 220–320 kWh per tonne of cathode copper is derived from cell voltage and current efficiency rather than quoted as a headline, so the figure can be checked against the electrochemical equivalent of copper.
Continuous electrolyte purification, sized from the anode assay. Bleed, decopperising, membrane separation, nickel recovery and, where required, ion exchange or adsorption for antimony and bismuth — with purified acid returned to the cellhouse. This is the difference between a cathode specification met on day one and one still met on day sixty.
Named standard instead of a purity slogan. Cu-CATH-1 to BS EN 1978, with every controlled impurity element individually limited and reported on the certificate of analysis rather than a single copper figure. The distinction between composition compliance and brand registration is stated rather than blurred.
316L permanent cathodes with edge strips and loop bars. Consistent plate geometry, no starter-sheet loop to operate, no starter-sheet copper held up in circulation, and a plate that returns to the cell instead of being consumed. The starter sheet route is supplied where a specification rules out a stainless contact, and the choice is recorded on the route sheet.
Anode-first specification. Anode assay sets the purification duty, anode thickness sets the scrap rate, and slime settling behaviour sets the electrode spacing and the current density the cellhouse can sustain. All three are read from your material before anything is quoted.
Slime handling engineered for low loss. Anode bagging, slime transfer, filter pressing, drying, weighing and assay are designed around the fact that the slime is the highest-value stream per tonne in the plant, and that on high-silver or board-derived feedstock it is the second revenue line.
Anode scrap returned to the melt. Between 12% and 20% of each anode’s weight is simply re-melted, with the wash liquor collected so entrained slime returns to the slime circuit instead of being lost in the melt.
Acid mist contained at the source. Hooded cells with collection under negative pressure, an alkali scrubbing tower with two packed beds, redistribution and a demister, and a scrubber liquor record — so containment is verifiable rather than asserted.
Nitrogen oxide abatement for nitrate-bearing flowsheets. The reduction-absorption route converts nitrogen oxides to nitrogen, carbon dioxide and water, so the abatement stage does not create the secondary nitrite effluent that alkaline absorption produces.
Closed electrolyte loop with process water reuse. Purified acid returns to the cellhouse, wash water is collected, and residual liquors are neutralised, settled, filtered and reused with the hydroxide sludge routed back for metal recovery.
IGBT rectifier isolated from the cellhouse atmosphere. The power supply sits in its own enclosed room clear of the acid vapour that pervades a copper tankhouse, with 12-pulse or 24-pulse configuration and optional polarity-reversal pulse.
Modular cellhouse, staged for growth. Cell banks, busbar, rectifier and purification capacity are supplied as modules so that capacity can be added without rebuilding the building, and units are shop-preassembled to shorten site works.
Both process routes in one supply scope. Electrorefining for solid cast anodes and electrowinning for copper-bearing solutions, supplied independently or as a hybrid layout that shares one rectifier room, busbar and electrolyte purification circuit.
Melting, sampling and assay inside the scope. The customer receives a certificated cathode, a declared slime concentrate and a closed mass balance with a retained sample, not a cathode weight and a purity claim.
Honest specification boundaries. Where a claim has a limit, the limit is stated. Cu-CATH-1 chemistry compliance is not the same condition as LME deliverability, the current-density ceiling belongs to the feedstock rather than the rectifier, and capacity is engineered to order rather than published as a model table.
Configuration to the assay, with the numbers written down. Cell count, cathode area and spacing, rectifier rating, electrode spacing, electrolyte volume, circulation and cooling duty, purification throughput, hood exhaust volume, scrubber duty and effluent load are all fixed in the process design package.

Technical Parameters And Specifications

The table below lists the design and operating parameters of the copper electrolysis equipment package. The values are the engineering design window for copper electrorefining; the final configuration is fixed after incoming material testing, because anode assay, slime behaviour and impurity load move these values within the ranges stated. Cell count, cathode area, rectifier rating, footprint, installed power and utility consumption are engineered to your material and output target.

Table 1. Copper electrolysis equipment — technical parameters and specifications.

Parameter	Specification	Engineering notes
Process route	Copper electrorefining (ER); optional electrowinning (EW) or hybrid ER + EW layout	ER for solid cast anodes, EW for copper already in solution
Equipment scope	Anode preparation and casting; cellhouse and electrode assemblies; rectifier, busbar and control; electrolyte make-up, circulation, temperature and filtration; electrolyte purification and by-product recovery; anode slime collection and dewatering; cathode stripping, washing and bundling; acid mist, nitrogen oxide and effluent control; melting, sampling and assay	Delivered as modules so the cellhouse can be expanded in stages
Feed anode copper content	Cu 98% and above (blister and anode copper); Cu 99% and above preferred	The purification duty rises as the anode assay falls
Feed impurity profile	Ni, As, Sb, Bi, Pb, Fe, Se, Te, Sn and O determined in the feed assay	Sets the purification throughput and the achievable current density
Feed forms accepted	Blister and anode copper, fire-refined anode copper, crude and black copper, smelted secondary copper, board and e-waste copper fractions, copper cement, sludge and filter cake, copper powder, smelting residues and flue dust, copper-bearing solutions, copper–precious metal alloy scrap, consigned toll lots	Material too fine or too friable to cast is routed to electrowinning
Feed pre-treatment	Melting with flux; tin, lead and aluminium removal where present; reduction to remove free oxygen; drying and consolidation of powder, cement and sludge; briquetting where a stable plate cannot be cast	Applied before anode casting or before the leach, as the material requires
Anode geometry and thickness	Cast to a controlled thickness and envelope, with lug contact faces machined flat and the plate straightened before bagging	Anode thickness sets the scrap rate and the remelt load
Anode bagging	Acid-resistant bag or membrane fitted to every anode before loading	Retains insoluble slime at the anode face and protects the cathode
Cathode plate	316L stainless steel permanent cathode with insulating edge strips and loop bar; copper starter sheet option where a stainless contact is ruled out	Plate geometry held by straightening and flatness inspection
Anode plate material, electrorefining	Cast copper anode plate	The anode is both the feedstock and the electrochemical reactant
Anode material, electrowinning	Lead alloy or coated titanium insoluble anode	Fitted only on the solution-side configuration
Current density	300 A/m² at the design point; 220–320 A/m² working window; up to 350 A/m² in high-rate mode	Ceiling set by anode quality and slime settling behaviour
Cell voltage	0.25–0.35 V per cell	Excludes busbar and contact losses
Current efficiency	92–97%	Declines with short-circuit rate, contact resistance and impurity build-up
DC energy consumption, cell level	220 kWh per tonne of cathode at 0.25 V and 96% current efficiency, rising to about 320 kWh per tonne at 0.35 V and 92%; 220–320 kWh per tonne across the design window	Derived as cell voltage divided by the electrochemical equivalent of copper times current efficiency; busbar, contact, circulation, heating and extraction consumption is additional
Electrolyte system	Copper sulfate and sulfuric acid in water	Free acid makes the liquor conduct and holds the copper sulfate in solution
Electrolyte copper tenor	Cu²⁺ 45–50 g/L	Held inside a control band through the campaign
Electrolyte free acid	Free H₂SO₄ 180–200 g/L	Adjusted to the feed assay and the anode dissolution rate
Electrolyte chloride	Cl⁻ below 0.1 g/L	Above this level the deposit roughens and silver behaviour in the cell changes
Electrolyte temperature	58–65 °C	Held by heat exchange or immersion heating; bounded below by kinetics, above by evaporation
Electrolyte additives	Metered on automatic control, monitored against current efficiency and electrolyte condition	Governs deposit morphology and cathode surface quality
Electrolyte circulation	Per-cell flow control, entering along the electrode row and leaving from the top	Refreshes the cathode boundary layer and prevents stratification of the denser liquor
Electrolyte level control	Automatic, matched to the liquor carried out with the extraction air	Holds level and concentration without operator topping up
Electrolyte filtration	Cartridge, bag or disc filtration ahead of the cell	Removes suspended solids that would blind the anode bags
Electrode spacing	Approximately 95–110 mm between electrode centres, set by alignment fixture	Closest spacing that keeps resistance low without risking deposit bridging
Impurity control	Continuous bleed with decopperising, then nickel removal by membrane separation and crystallisation or by solvent extraction with P204, P507 or C272; ion exchange or adsorption for antimony and bismuth where required	Cathode grade is defended here rather than by reducing current density
Impurity interference thresholds	Antimony and bismuth form a floating slime that adheres to the deposit; arsenic can co-deposit with the copper	Thresholds are fixed in process design against the anode assay and the target cathode grade
Copper recovery from the bleed	Recovered by liberator cell, cyclone electrowinning or a dedicated electrowinning stage before the nickel stage	Returned to the circuit rather than bled to effluent
Nickel by-product route	Nickel sulfate or nickel carbonate by extraction, evaporation and crystallisation, or by solvent extraction	Converts an electrolyte bleed into a saleable product
Purified acid return	Returned to the cellhouse holding the free acid balance	Closes the electrolyte loop
Anode service life	Approximately 21–28 days per anode	Depends on anode thickness and current density
Cathode stripping cycle	7–14 days between strippings	Scheduled to hold deposit quality rather than to maximise plate weight
Anode scrap rate	12–20% of anode weight	Washed free of slime and returned to the melting furnace
Anode slime generation	0.2–1.0% of anode weight	Higher on secondary and high-silver feedstock
Slime handling	Washed free of entrained electrolyte, filter-pressed, dried, weighed and assayed per lot	Declared by metal content before it leaves the plant
Slime contained metals	Au, Ag, Pt, Pd, Se and Te	Separated and declared on the downstream precious metal circuit
Short-circuit detection	Per-cell voltage monitoring, per-cathode current measurement, busbar contact temperature monitoring, cellhouse thermal imaging	Locates a short at the cathode that carries it rather than at cell level alone
Current efficiency computation	Ampere-hour integration against cathode mass produced	Continuous operating figure with historical query
Interlocks	Automatic rectifier trip on abnormal current, voltage, contact temperature or electrolyte condition	Stops a compromised campaign rather than reporting it afterwards
Rectifier	IGBT high-frequency switching rectifier with current and voltage regulation; 12-pulse or 24-pulse; optional polarity-reversal pulse	Installed in a separate enclosed room clear of the cellhouse atmosphere
Busbar and contacts	Busbar sized to the cellhouse current with low voltage drop, compression clamps, machined contact faces and insulated supports	Contact losses are a primary current-efficiency loss point
Cell body	Acid-proof polymer or protected concrete with a corrosion barrier, modular and insulated	Shop-preassembled to shorten site works
Cathode stripping	Semi-automatic or automatic stripping machine with plate handling, verticality checking and plate reconditioning	Plate returned to the cell immediately after stripping
Cathode washing	Washed free of adhering electrolyte and copper sulfate with the wash water collected and returned	Residual surface sulfate is a rejection point in most cathode specifications
Cathode finishing	Sheared or cut, bundled, strapped, weighed and marked for dispatch	Bundle format set to the customer’s requirement
Acid mist control	Hooded cells, collection under negative pressure, packed alkali scrubbing tower with two beds, redistribution and demister	Mist contained at the point of generation
Nitrogen oxide control	Reduction-absorption stage converting nitrogen oxides to nitrogen, carbon dioxide and water	Applied where nitrate-bearing liquor is processed on site
Effluent management	Neutralisation, sedimentation and filtration with process water recovered for reuse and hydroxide sludge returned for metal recovery	Discharge held within the site’s regulatory limits
Working environment	Monitored against the site’s occupational exposure limits	Cellhouse hooding is the primary control
Cathode product purity	Cu ≥ 99.99% (4N) as standard; 99.995%–99.999% available on a two-stage refining configuration	Released against a certificate of analysis
Cathode product grade basis	Cu-CATH-1 to BS EN 1978; ASTM B115 Grade 1 and GB/T 467 are the equivalent published bases for the same grade	LME deliverability additionally requires the producer brand to be on the LME registered list
Total controlled impurity	65 ppm or below	Cu-CATH-1 basis
Controlled impurity elements	Ag, As, Sb, Bi, Pb, Ni, Fe, S, Se, Te and O	Individually limited and reported on the certificate of analysis
Product forms	Cathode copper in bundle or cut plate form; electrolytic copper powder on the powder configuration; anode slime concentrate; silver-rich slime fraction; gold and PGM concentrate; anode scrap remelt stock; nickel sulfate or nickel carbonate; purified acid; compliant off-gas and effluent	—
Quality verification	Copper assay on the cathode by titration or ICP-OES; Cu, Ni, As, Sb, Bi, Fe, chloride and free acid determination on the electrolyte; ICP-OES on the anode, the slime and the effluent; per-batch parameter log and retained reference sample	Fire assay where the precious metal content of the slime has to be declared
Documentation	Process design package with the mass balance, operating procedures, electrical drawings, equipment layout, spare parts catalogue, per-batch parameter record and certificate of analysis	—
Materials of construction, summary	Acid-proof polymer or protected concrete for cell bodies and hoods; 316L stainless steel for cathode plates; lead alloy or coated titanium for insoluble anodes; acid-resistant polymer for anode bags and filter media; alkali-resistant lining for the scrubbing circuit	Selected for hot acid sulfate duty
Capacity, cathode area, cell count, rectifier rating, footprint, installed power and utilities	Engineered to your anode assay, impurity profile, slime behaviour and target daily cathode output rather than taken from a catalogue of fixed models	Fixed in the process design package before manufacture

Reading the table. Current density and electrode spacing are the two parameters that most strongly decide the economic outcome: raising current density raises output per cell, but it also tightens the tolerance on impurity build-up and on the way the slime settles, so the practical ceiling belongs to the feedstock rather than to the rectifier. Electrolyte composition and temperature are held in narrow bands because deposit morphology degrades quickly outside them, and the chloride limit is the one that is most often exceeded by accident, because chloride arrives with the process water and with certain feed materials. The controlled impurity limits are stated against the governing standard rather than reproduced as a loose table of numbers, because the binding limits belong to the standard edition named in the contract; the practical approach is to agree the standard, the edition and the grade, and then require the certificate of analysis to report every controlled element.

Technical Advantages

The largest efficiency loss in a tankhouse is measured rather than inferred. Current efficiency and short-circuit rate are the same number expressed two ways, and most of the copper lost between the rectifier and the cathode dispatch bay is lost at a handful of contacts and shorts. This equipment instruments the cellhouse at cathode level — per-cathode current, per-cell voltage, busbar contact temperature and thermal imaging — and computes the operating current efficiency continuously from the ampere-hours passed. Result: a fault is located at the cathode that carries it and cleared within the cycle, instead of being discovered as a shortfall in the monthly metal balance.
Electrolyte purification sized from the anode rather than from a rule of thumb. Arsenic, antimony and bismuth enter the liquor as the anodes dissolve and leave it only when the plant takes them out. The purification circuit — bleed, decopperising, membrane separation, nickel recovery and, where the cathode specification requires it, ion exchange for antimony and bismuth — is sized from the accumulation rate implied by your assay. Result: the cathode meets Cu-CATH-1 on day sixty as well as on day one, on feedstock that would pull a simpler plant out of specification.
Copper recovered from the bleed instead of bled to effluent. The side stream is decopperised before the nickel stage, so the copper returns to the circuit and the by-product is not contaminated with it. Result: value recovered from the fraction most plants write off, and a lower load on the effluent plant.
A named standard with its boundary stated. Cu-CATH-1 to BS EN 1978 is the chemistry basis the LME accepts for Grade A copper, with 65 ppm or below total controlled impurity and every element reported on the certificate of analysis. LME deliverability separately requires the producer brand to be on the LME registered list, and that distinction is stated rather than blurred. Result: a buyer can specify exactly which of the two conditions they need, and an equipment supplier does not promise something that belongs to brand registration.
Energy stated with its basis, so it can be checked. 220–320 kWh per tonne of cathode copper across the design window, derived as cell voltage divided by the electrochemical equivalent of copper times current efficiency: 220 kWh/t at 0.25 V and 96%, about 320 kWh/t at 0.35 V and 92%. Result: a figure a metallurgist can verify against first principles instead of a headline number on a datasheet.
Deposit quality defended at the electrolyte, not by slowing the plant. Chloride held below 0.1 g/L, electrolyte at 58–65 °C, additive dosing on automatic control and per-cell circulation. Result: a compact, strippable deposit at the current density the plant was bought for, rather than a lower current density chosen to compensate for drifting chemistry.
Slime treated as the second revenue line it usually is. Anode bagging, low-loss transfer, filter pressing, drying, weighing and per-lot assay, with the silver-rich fraction declared separately where the tenor justifies it. Result: the gold, silver, platinum, palladium, selenium and tellurium that the anode carried are recovered and sold rather than diluted into the copper or lost to the effluent plant.
Anode scrap returned rather than sold. Between 12% and 20% of every anode is re-melted into fresh anodes, with the wash liquor collected so entrained slime goes back to the slime circuit. Result: the anode-side copper balance closes inside the plant and no value leaves as discounted scrap.
Acid mist and nitrogen oxides handled inside the equipment scope. Hooded cells, extraction under negative pressure, a packed alkali scrubber with demister and a logged scrubber liquor, plus reduction-absorption nitrogen oxide abatement where nitrate-bearing liquor is processed. Result: permitting becomes a design input, and the plant does not trade a cathode specification for a workplace or stack problem.
A closed water and acid loop. Purified acid returns to the cellhouse, cathode wash water is collected and returned, residual liquors are neutralised, settled, filtered and reused, and the hydroxide sludge goes back for metal recovery. Result: lower make-up consumption and a smaller regulated discharge.
Rectifier specification matched to a refinery and not to a workshop. IGBT switching rectifier in a separate enclosed room clear of the acid atmosphere, interlocked to stop on an abnormal reading. Result: a power supply that lasts in a copper tankhouse, and a fault that stops the cellhouse instead of a batch that fails the assay.
Materials chosen stream by stream. Acid-proof polymer or protected concrete for cell bodies, 316L stainless steel for permanent cathodes, lead alloy or coated titanium for insoluble anodes, acid-resistant media for the bag and slime circuits, and alkali-resistant linings where scrubbing liquor is handled. Result: corrosion life matched to the duty of each stream rather than a single general chemical plant specification.
Both routes from one supplier. Electrorefining for cast anodes and electrowinning for copper in solution, supplied separately or as a hybrid sharing one rectifier room, busbar and purification circuit. Result: a site that receives both solid and liquid copper streams does not need two incompatible plants.
Cathode output that is certificated rather than asserted. Cathode assay, slime assay, electrolyte assay and a closed mass balance, issued per campaign with a retained reference sample. Result: a specification a buyer, a bank or a toll-refining counterparty can audit against its own analysis.
Modular, so a pilot does not become stranded capital. Cell banks, busbar, rectifier and purification capacity are added to a validated installation rather than replacing it. Result: an entry point that scales with the market instead of a plant that has to be bought twice.
The slime circuit connects to the rest of the refinery. The slime concentrate leaves for a precious metal circuit and the nickel by-product leaves as a saleable salt, so this equipment sits inside a flowsheet rather than at the end of one. Result: one cellhouse that closes the copper loop without breaking the silver, gold and PGM circuits around it.

Service Process

Step 1 — Enquiry and material data review. You provide the anode material type, an assay or typical analysis with the copper, precious metal and impurity figures, the expected monthly cathode volume and any site constraints. We state at this point whether the material can be run directly or needs pre-treatment, drying or consolidation first, and whether the electrorefining or the electrowinning route fits. Output: preliminary route statement and a clear scope of supply.

Step 2 — Free incoming material testing. A representative sample is assayed for copper, the precious metal suite and the full impurity suite, including the arsenic, antimony and bismuth that decide the purification duty. Where the material permits, the sample is taken through a bench electrolysis cycle to confirm the achievable current density and deposit quality on real material rather than on assumption. Output: test report with the flowsheet, the purification duty and a product sample returned for your own assay.

Step 3 — Process design and mass balance. We issue the process flow diagram, the anode and cathode schedule, the electrode spacing, the electrolyte volume and make-up recipe, the temperature and circulation duty, the additive regime, the bleed and purification throughput, the stripping cycle, the reagent and utility balance and the equipment list. Output: process design package and mass balance by metal.

Step 4 — Technical proposal and commercial offer. Process description, equipment list, layout drawing, utility requirements, automation scope, environmental scope and commercial proposal, with the design parameters tied to your assay rather than to a generic model. Output: costed technical proposal.

Step 5 — Contract and detailed engineering. Process and instrumentation drawings, cellhouse layout, electrical design, civil and structural interfaces, ventilation and effluent interfaces, and the full equipment specification issued for approval. Output: approved engineering documentation set.

Step 6 — Manufacture and factory performance test. Cell bodies, hoods, electrode assemblies, scrubbing tower, rectifier, control panel, dosing and filtration systems and the cathode stripping machine are fabricated, assembled and function-tested before shipment, with material certificates retained. Where the customer attends, the factory test is run on their own material. Output: factory acceptance test record.

Step 7 — Shipment, installation and commissioning. Modular shop-assembled units ship with the documentation set, and our engineers supervise installation, leak and pressure testing of the electrolyte circuit, electrical and control checkout, hood and ducting commissioning, and water commissioning of the cellhouse. Output: mechanically complete installation ready for electrolyte make-up.

Step 8 — Production trial, performance verification and training. The cellhouse is run on your own anode material and verified against the agreed cathode specification, current efficiency and recovery targets, then operators and maintenance staff are trained on electrode handling, electrolyte control, stripping, slime handling, purification operation, acid mist control and safe working procedure. Output: performance test certificate, first certificate of analysis and trained operators.

Step 9 — After-sales support and spares. Spare parts supply, remote technical support, troubleshooting on cathode quality or electrolyte drift, purification-circuit optimisation as the feed mix changes, and upgrade paths for capacity expansion or a change of process route. Output: continuing production support with a consumable and wear-part schedule.

Warranty And After-Sales Service

Warranty period. Twelve months from successful commissioning or eighteen months from shipment, whichever falls earlier, covering design, manufacture and assembly defects of the supplied equipment. Excluded: consumables such as anode bags, filter cartridges, edge strips, gaskets and seals, and damage from misuse or from feed material outside the agreed specification.
Performance commitment. Where the anode material matches the tested sample, we stand behind the cathode specification, the current efficiency and the recovery targets established in the process design package, with the production trial as the reference point. Output: documented performance acceptance.
Spare parts. Wear and critical spares — anode bags, cathode plates and edge strips, loop bars, gaskets, seals, pump and dosing parts, filter media, rectifier components and stripping machine parts — are quoted at the time of order and held available afterwards, with a recommended on-site stock list issued at handover. Output: spare parts list and supply at cost.
Remote support. Telephone, email and messaging support on operating questions, alarm interpretation, current-efficiency diagnosis and electrolyte chemistry, whenever your cellhouse is running. Output: same-day response on operating issues.
On-site service. Engineer attendance for warranty faults, process problems and periodical check-ups, with response and attendance times agreed in the contract according to your location. Output: on-site intervention and a service report.
Operator retraining and refresher visits. Additional training, refresher sessions and process optimisation visits as your feed mix, anode quality or cathode specification changes, including re-establishing the current density and bleed schedule after a change of anode supplier. Output: updated training and revised procedures.
Documentation set. Operation and maintenance manuals, process flow diagram, piping and instrumentation diagram, equipment layout, electrical drawings, spare parts catalogue, safety data for the reagents handled and the emergency response plan. Output: complete documentation handover.
Compliance support. Assistance with effluent and emission parameter declarations, scrubber performance verification, and the handling, storage and disposal requirements for sulfuric acid, copper-bearing liquor and the slime and nickel by-product streams. Output: technical data for your permit applications.
Lifetime technical support. The process design remains yours, and our engineering team stays available for modification and expansion advice — additional cell banks, higher current density, larger cathode area, additional purification capacity — for the operating life of the plant. Output: long-term engineering continuity.

Frequently Asked Questions

What is copper electrolysis equipment?

Copper electrolysis equipment is an electrorefining cellhouse in which a cast copper anode is hung in an acidified copper sulfate electrolyte and made the positive electrode of a direct-current circuit. Copper dissolves from the anode as the Cu²⁺ ion and is reduced back onto a permanent cathode as a dense, high-purity deposit, while the metals more noble than copper — gold, silver, platinum, palladium, selenium and tellurium — do not dissolve and report to the cell bottom as anode slime, and the base metals stay in solution and are taken out by electrolyte purification. It is an anodic electrorefining process, which means the anode is both the feedstock and the electrochemical reactant. A typical YuSai package covers anode casting, lug trimming and bagging, the acid-proof cellhouse with 316L permanent cathode assemblies, the IGBT rectifier and busbar, electrolyte make-up, circulation, temperature control and filtration, continuous electrolyte purification with decopperising and nickel recovery, per-cell short-circuit detection, cathode stripping and washing, slime dewatering, and closed acid mist, nitrogen oxide and effluent control.

What purity of cathode copper does the equipment produce?

Cu 99.99% (4N) as standard, with chemistry engineered to Cu-CATH-1 to BS EN 1978 and a total controlled impurity content of 65 ppm or below. Every controlled element — silver, arsenic, antimony, bismuth, lead, nickel, iron, sulfur, selenium, tellurium and oxygen — is individually limited and reported on the certificate of analysis rather than compressed into a single copper figure. Where a higher standard is required, 99.995% and 99.999% are produced on a two-stage refining configuration. The achievable grade on your particular anode is confirmed in the incoming material test, because the impurity profile of the anode, and above all its antimony and bismuth content, is what decides how hard the purification circuit has to work.

What anode copper content does the equipment need?

Copper anodes assaying 98% Cu and above run directly, and 99% Cu and above is the preferred operating band. The reason for the band is that the anode has to carry current and dissolve at a controlled rate while the impurities it releases accumulate in the circulating electrolyte: as the anode assay falls, more impurity enters the liquor per tonne of copper produced and the purification circuit has to be sized correspondingly larger. Below the preferred band the usual route is to remove the interfering elements first — a pre-melt and slagging step for tin, lead and aluminium, or a reduction step to take out free oxygen — and then cast the copper into anodes and run the cellhouse. Anode thickness matters as much as anode assay, because it sets the fraction of each anode that remains as scrap and has to be re-melted.

What current density and cell voltage does the equipment run at?

The design point is 300 A/m² of cathode area, inside a working window of 220–320 A/m², with up to 350 A/m² available in high-rate mode. Cell voltage runs at 0.25–0.35 V per cell and current efficiency at 92–97%. The two are linked: current density is limited by how quickly copper ions can be brought to the cathode surface, so running higher means the cell has to be designed to support it, through cathode surface area, electrode spacing, circulation rate and temperature control. The practical ceiling on current density belongs to the feedstock rather than to the rectifier, because higher current density tightens the tolerance for impurity build-up and for the way the slime settles in the cell, and it makes a short circuit or a resistive contact more damaging. The setting for your material is fixed during process design and confirmed on the production trial.

What is the electrolyte composition and temperature?

Copper sulfate and sulfuric acid in water, with copper held at Cu²⁺ 45–50 g/L, free sulfuric acid at 180–200 g/L and chloride below 0.1 g/L, at a controlled 58–65 °C. The free acid is what makes the liquor conduct and what keeps the copper sulfate in solution at the working temperature. The copper tenor is what keeps the deposit compact rather than powdery. The chloride limit is the one most often exceeded by accident, because chloride arrives with process water and with certain feed materials, and above 0.1 g/L the deposit roughens and silver behaves differently in the cell. The temperature band is bounded below by conductivity and deposition kinetics and above by evaporation and reagent loss.

How much energy does it use per tonne of cathode copper?

Cell-level direct current consumption runs 220–320 kWh per tonne of cathode copper across the design window. The figure is derived rather than asserted: it equals the cell voltage divided by the electrochemical equivalent of copper — 1.186 grams per ampere-hour — times the current efficiency, which gives 220 kWh per tonne at 0.25 V and 96% current efficiency and about 320 kWh per tonne at 0.35 V and 92%. Busbar, contact, circulation, heating and extraction consumption is additional to that cell-level figure. Because the two variables are published, the energy figure can be checked against first principles and against your own electricity price rather than accepted as a datasheet number.

How does the equipment detect and clear short circuits?

Per-cell voltage is monitored continuously, and because a single shorted cathode inside a cell whose overall voltage still looks normal is invisible at cell level, the equipment also measures individual cathode currents and monitors busbar contact temperature, with cellhouse thermal imaging to locate a hot electrode. The control system integrates the ampere-hours passed and compares them against the cathode mass produced, which gives the operating current efficiency continuously; a short circuit does not stop the current, it routes the current around the cathode it was meant to build, so this is the number that reveals it. Alarms are raised at the cell and the cathode, and the rectifier is interlocked to trip on an abnormal reading rather than allowed to run a compromised campaign to completion. Clearing a short is a manual operation carried out on the cathode identified, which is why locating it precisely matters more than detecting it in aggregate.

How are nickel, arsenic, antimony and bismuth removed from the electrolyte?

By a continuous side stream drawn from the circulating electrolyte, processed in sequence so that each element is taken out in the form that suits it. Copper is removed first, by a liberator cell, cyclone electrowinning or a dedicated electrowinning stage, because recovering it before the nickel stage keeps the copper out of the by-product and returns value to the circuit. Nickel is then separated, either by membrane separation followed by evaporation and crystallisation to nickel sulfate or nickel carbonate, or by solvent extraction with P204, P507 or C272, and the choice is made on the nickel tenor and on the by-product form the site can sell. Arsenic, antimony and bismuth are the elements that decide the cathode assay, because antimony and bismuth form a floating slime that adheres to the deposit and arsenic can co-deposit with the copper; where the cathode specification requires them held very low, ion exchange or adsorption is applied to a further treated stream. Purified acid returns to the cellhouse, so the bleed closes as a loop rather than leaving as effluent.

Permanent stainless steel cathodes or copper starter sheets?

It is a choice between tankhouse complexity and contact risk, and it is recorded on the route sheet rather than left to stock on hand. A 316L stainless steel permanent cathode is the standard choice: it gives consistent plate geometry, it removes the starter sheet production loop — mother blanks, peeling, flattening, lug attachment — from the tankhouse, it does not tie up copper as starter sheet inventory circulating around the cellhouse, and the plate returns to the cell after stripping instead of being consumed. The trade-offs are a higher capital cost per cathode, a stripping tool that has to handle the plate without bowing it, and the requirement that the edge strips stay intact so the deposit cannot contact the plate edge. Copper starter sheets are supplied where a customer specification rules out a stainless contact in the electrolyte, where the cathode geometry is unusual, or where the tankhouse is small enough that stripping is manual; the trade-off is that producing starter sheets consumes cellhouse capacity and holds copper in circulation.

What happens to the gold and silver in the anode?

They are recovered rather than lost. Gold, silver, platinum, palladium, selenium and tellurium are more noble than copper, so they do not dissolve at the anode at all and report to the cell bottom as anode slime at 0.2–1.0% of anode mass. The anode is bagged, so that residue is retained at the anode face instead of migrating onto the cathode where it would contaminate the deposit and drag the assay down. When the campaign closes, the bag is opened and the contents are washed free of entrained electrolyte, filter-pressed, dried, weighed and assayed; the slime is declared by metal content, the silver-rich fraction is separated where the tenor justifies it, and the gold and platinum group metal values leave for the precious metal circuit as a declared concentrate. The precious metal content of your anode is established in the incoming material test so that this credit is priced into the project rather than discovered afterwards.

What is anode slime worth and how is it handled?

On most copper feedstocks the slime is the second-largest revenue line in the refinery after the cathode itself, and on high-silver or board-derived feedstock it can rival the copper margin. It is generated at 0.2–1.0% of anode mass, which sounds small until it is priced against the contained gold, silver, platinum, palladium, selenium and tellurium. The equipment therefore handles it as a product stream: low-loss transfer from the cell, filter pressing, drying, weighing and per-lot assay, with the assay issued alongside the cathode certificate so the value is realisable at settlement rather than at the discretion of a buyer. YuSai also supplies the downstream precious metal circuit that converts the concentrate, which means the slime recovery targets are set at the same time as the cathode specification.

How long is a cathode stripping cycle and an anode life?

Cathodes are stripped on a 7 to 14 day cycle, and each anode dissolves over roughly 21 to 28 days depending on its thickness and on the current density it runs at. The two are deliberately different numbers: more than one cathode harvest occurs during a single anode life, and the stripping cycle is set by the deposit quality the plate can hold rather than by the maximum weight it can carry. Leaving a cathode in the cell past its cycle produces a deposit that is thicker but rougher, harder to strip and more likely to trap slime, so the cycle is a design output rather than a production decision taken on the day. Between 12% and 20% of each anode’s weight remains at the end of its life as undissolved scrap, which is washed and returned to the melting furnace.

How is acid mist and nitrogen oxide controlled?

Acid mist forms at the electrolyte surface, where oxygen and hydrogen bubbles burst and throw fine sulfuric acid droplets into the headspace, so the primary control is containment rather than dilution. Cells are hooded and the headspace is drawn off under negative pressure, which means any leakage is inward, and the extracted air passes through a packed alkali scrubbing tower using NaOH scrubbing liquor, with the packing arranged in two beds with redistribution between them and a demister ahead of the stack. The scrubber liquor is analysed and logged, so the scrubbing duty can be verified rather than assumed. Nitrogen oxides arise where nitrate-bearing liquor is processed on the same site; a reduction-absorption stage converts them to nitrogen, carbon dioxide and water, which avoids the secondary nitrite effluent that plain alkaline absorption produces. Wash water and spent liquor go to neutralisation, sedimentation and filtration with the process water recovered for reuse.

Is the cathode LME Grade A?

The cathode chemistry is engineered to Cu-CATH-1 to BS EN 1978, which is the chemistry basis the LME accepts for Grade A copper, with total controlled impurity at 65 ppm or below and every controlled element reported on the certificate of analysis. LME deliverability is a separate condition: copper delivered against LME contracts must also be of an LME-registered brand, which is a registration of the producer and the production route rather than a property of a single parcel of metal. ASTM B115 Grade 1 and GB/T 467 are the equivalent published bases for the same grade of cathode. YuSai states the distinction clearly so that a buyer can specify exactly which of the two conditions the project has to satisfy.

What feedstock can the equipment process?

Copper anodes cast from blister copper, anode copper or smelted secondary copper at 98% Cu and above; fire-refined anode copper; crude and black copper from converting; copper alloy particles, granules, shavings and mixed metal powder from cable and board processing; copper cement and cemented copper; copper sludge, filter cake and press residue; copper powder; copper-bearing smelting residues and flue dust; copper–precious metal alloy scrap; and consigned toll lots. Copper already in solution — spent electrolyte, acid etching and micro-etching waste liquid, copper sulfate and copper chloride process liquors, and loaded leach or solvent extraction liquors — is taken through the electrowinning route instead. Material too fine or too friable to cast into a stable anode plate is routed to leaching and electrowinning, which is the correct route for that material rather than a compromise.

What is the difference between copper electrorefining and copper electrowinning?

By what is at the anode. Electrorefining dissolves a solid metallic anode, so the anode is simultaneously the feedstock and the electrochemical reactant, and the design revolves around keeping it dissolving at a controlled rate — anode thickness, bagging, slime settling, electrode spacing. Electrowinning has no anode to dissolve: the copper is already in solution in a leach liquor, a spent electrolyte, a strip solution or an etching waste, and the process is governed by how quickly ions can be brought to the cathode, using an insoluble anode. The two use different anodes, different electrolyte conditions and a different control emphasis, and a cell specified for one duty does not do the work of the other. YuSai supplies either route, or both as a hybrid layout sharing one rectifier room, busbar and electrolyte purification circuit.

What capacity and power can be engineered?

Capacity is engineered to your anode assay, impurity profile, slime behaviour and target daily cathode output rather than selected from a catalogue of fixed models. What matters in this process is the copper content of the anode, the impurity load that sets the purification throughput, the anode thickness that sets the scrap rate, the cathode area and current density the cellhouse can sustain, and the stripping cycle that holds deposit quality. Two cellhouses of the same nominal tank size can therefore have very different daily output depending on the material and on how hard the purification circuit has to work. We size the number of cells, the cathode area and spacing, the rectifier rating, the electrolyte volume, the circulation and cooling duty, the purification throughput, the stripping machine capacity, the hood exhaust volume, the scrubber duty and the effluent load from your assay and your monthly cathode volume, and we state the resulting figures in the process design package. The layout is modular, so an installation that validates the route on a few hundred kilograms a day can be extended rather than replaced.