Precious Metal Refining Equipment

— Turnkey Precious Metal Refining Equipment

A YuSai precious metal refining equipment line takes crude gold, silver doré, jewellery scrap, anode slime, spent catalysts and e-waste concentrates and returns them as assayed fine metal — gold and silver at 99.99% (4N) as standard with 99.999% (5N) achievable on a second electrolytic pass, platinum and palladium at 99.95% or above, and rhodium at 99.90%. All four refining technologies used in this industry — chemical (aqua regia), electrolytic (Wohlwill-type gold cells and silver nitrate silver cells), pyrometallurgical (melting, granulation, cupellation) and the filtration and assay systems around them — are engineered as one line by one supplier, so the route is selected from your feed assay instead of being forced onto whatever the catalogue happens to hold. Comprehensive recovery of 95% or more is the standard design target, and the electrolytic route lifts more than 99% of the metal out of a high-grade electrolyte.

Product Overview

Precious metal refining equipment is the plant that converts impure precious-metal-bearing material into metal of certified fineness — ingots, bars, granules, crystal, sponge or powder that can be sold, pledged, returned to production or shipped under custody transfer. The input is crude gold and silver doré, jewellery and bench scrap, anode slime from a tank house, spent industrial catalysts, or concentrates recovered from electronic waste. The output is fine gold at 99.99% or better, fine silver at 99.99%, and platinum group metals at 99.90–99.95% and above, each released against an assay. A refining line is therefore not a single machine: it is a sequence of chemical, electrochemical, thermal and separation duties that have to match each other in capacity, chemistry and materials of construction.

Four technology families make up that sequence, and a properly designed line selects from all four rather than selling one of them to every customer.

Chemical (aqua regia) refining systems dissolve the feed selectively and precipitate the target metal back out. Dissolution reactors are built in highly corrosion-resistant materials — Titanium Grade 2 for heated vessels and borosilicate glass 3.3 where transparency and zero metal adsorption matter — so that boiling aqua regia, a mixture of hydrochloric and nitric acid, can be handled without the vessel becoming a consumable. Precipitation tanks are where reducing agents such as sodium metabisulfite, sodium sulfite or hydrazine are dosed to bring down a pure metal powder. The acid fume scrubber is not optional: multi-stage alkaline washing is what neutralises nitrogen oxides and chlorine before the gas leaves the building.

Electrolytic refining equipment is the route to the highest fineness and the benchmark most buyers already know. Gold is refined in a Wohlwill-type process, with impure gold cast as anodes and pure gold starter sheets as cathodes in a chloroauric acid electrolyte; silver is refined in a nitrate electrolyte, where the metal deposits as crystalline grains because silver chloride is insoluble in chloride media. Electrolytic refining is what takes metal from 95–99% to 99.99% and beyond, and it is the only route that states purity as an electrochemical result rather than a chemical intention.

Pyrometallurgical and melting equipment handles the thermal duties around the chemistry: induction and medium-frequency melting furnaces that turn powder and sponge into anodes or bars, cupellation furnaces used in fire assaying and for separating gold and silver from lead-bearing material, and granulating machines that pour molten metal into water to produce uniform shot, which multiplies the surface area available to the dissolving step that follows.

Filtration and analytical auxiliary systems decide whether the plant meets its recovery figure. Filter presses, bag filters, precision filtration down to 5 μm and vacuum filter discs isolate precipitates from acidic liquor before the values are lost in the filtrate. XRF spectrometers, balances and a fire assay kit verify incoming scrap and outgoing bullion, which is what allows the metal balance be closed per batch instead of per year.

A YuSai line is engineered as these four families working together, and the route is chosen from the feed. A jewellery refiner with 22K scrap and a low tolerance for acid fume handling may run an aqua regia front end into an electrolytic finishing cell. A tank house treating copper anode slime needs a pyrometallurgical enrichment stage first, then hydrometallurgical separation, then electrolysis. A catalyst recycler working in platinum, palladium and rhodium needs solvent extraction with P204, P507 and C272 systems and ammonium salt precipitation before any metal can be brought to fineness. The design work is deciding which of these stages your material actually requires — and the answer comes from an assay of your own sample, not from a size chart.

Every project therefore starts in the laboratory. Feed is characterised by XRF screening and, where the metal content is payable, by fire assay or wet chemical analysis. Bench-scale leaching, reduction, adsorption and deposition tests confirm what is recoverable and in what sequence. Equipment is then configured against that test result, and the line is handed over only after it produces metal at the agreed specification. If your material cannot reach the figure you need on a given route, we say so before the quotation rather than after the shipment.

At a glance

Refining routes: chemical aqua regia · electrolytic (Wohlwill-type gold, silver nitrate silver) · pyrometallurgical melting and casting · filtration, assay and environmental modules — in one scope
Product purity: Au 99.99% (99.999% optional) · Ag 99.99% · Pt/Pd ≥99.95% · Rh ≥99.90%
Comprehensive recovery: 95%+ design target on qualified multi-metal feed; >99% on the electrolytic route from high-grade electrolyte
Metals handled: Au · Ag · Pt · Pd · Rh, with Cu recovered in parallel; Ru · Ir · Se · Te on request
Capacity basis: quoted as kg per batch × cycles per day at a stated feed grade — never as a bare kg/day figure
Materials: Titanium Grade 2 dissolution reactors · borosilicate glass 3.3 vessels · PPH / PP / PVDF / enamel-lined steel · titanium-clad copper bus bars
Environmental control: enclosed hoods · flue gas condensation · multi-stage alkaline scrubbing · wastewater neutralisation, carbon adsorption and polishing · zero-liquid-discharge option
Verification: fire assay, XRF screening and ICP-OES difference analysis against ISO 11426, ASTM E1335, ISO 15093 and ISO 15096
Scope of supply: a single module, one complete refining route, or a turnkey refinery from feed intake to stamped bar
Delivery: process design from your own sample, factory acceptance test before shipment, site installation, commissioning, metal-balance verification and operator training

Application Scenarios

A refining line is installed wherever the value of the metal in the material exceeds the cost of recovering it:

Precious metal refineries and mints — refining of doré, scrap, sweeps and recycled feedstock into certified gold and silver bullion to LBMA Good Delivery minimum fineness.
Jewellery, watch and luxury goods manufacturing — recovery of gold and silver from bench sweeps, filings, polishing and buffing dust, spent plating baths, old alloys and returned stock.
E-waste and WEEE recycling plants — refining of gold, silver, palladium and copper recovered from printed circuit boards, CPUs, RAM modules, connectors and contact pins after mechanical dismantling and desoldering.
Printed circuit board and electronics manufacturing — recovery from gold etching, stripping and deplating solutions, iodine and iodide etchants, and spent plating waste, returned to the anode side of the same process.
Electroplating and surface finishing plants — treatment of gold, silver, palladium and rhodium plating baths, drag-out solutions and rinse water into saleable metal.
Copper, lead, zinc and nickel smelters — treatment of anode slime from the tank house as a payable precious metal stream rather than a residue, including selenium and tellurium recovery.
Automotive and industrial catalyst recyclers — extraction and separation of platinum, palladium and rhodium from spent ceramic and metallic catalytic converters.
Petrochemical and chemical plants — reclamation of precious metal from spent hydrogenation, reforming and coal-chemical catalysts.
Fuel cell and hydrogen industry — recovery of platinum from membrane electrode assemblies, catalyst layers and production scrap.
Photovoltaic panel recycling lines — silver recovery from delaminated solar cells, cell fragments and bus bar offcuts.
Dental, medical and laboratory operations — recovery of precious metal from dental alloys, laboratory ware, waste solutions and instrument scrap, with the same documentation discipline as an industrial plant.
Photographic, imaging and X-ray processing — recovery of silver from fixing, bleaching and developing solutions and from film and X-ray plate stock.
Mining and metallurgical operations — refining of doré bars, gravity and flotation concentrates, gold-loaded activated carbon from CIP and CIL circuits, and PGM-bearing concentrates.
Assay laboratories, bullion dealers and vault operators — compact refining and verification units for sampling, trial refining and custody work.

Applicable Raw Materials

Feedstock is grouped by what the material is, because the material — not the supplier — decides which route runs. The exact flowsheet for any individual stream is confirmed by laboratory test before the equipment design is frozen.

Crude gold, doré and mine bullion — gold doré bars, gold sponge, gold bullion and gold-bearing cement with a gold content of roughly 70% to 99%, produced by gravity, flotation or cyanidation circuits, by small-scale mining operations or by an existing refinery. Processed by melting and anode casting, then dissolution and electrolytic refining, with the aqua regia route used where the feed grade or the matrix makes direct electrolysis impractical. Output: gold anode plates for the electrolytic cell, and fine gold ingots at 99.99% or 99.999%.

Silver-rich doré, silver alloy and silver scrap — silver doré, scrap sterling and silver-copper alloys, silver contacts, silver solder rods and silver-plated components, with feed grades typically above 95% silver. Processed with nitric acid dissolving, impurity removal, sodium chloride precipitation of silver chloride where a parting step is needed, and silver nitrate electrolyte electrolysis. Output: electrolytic silver crystal and 99.99% silver ingots, with silver cement and silver chloride handled as in-circuit intermediates.

Jewellery scrap, bench sweeps and polishing waste — old and returned gold and silver jewellery, 9K to 24K alloys, chain and findings scrap, filings, turning and bench sweeps, polishing and buffing dust, and vacuum cleaner residues from a jewellery workshop. Processed through cleaning, incineration or roasting of organics, melting and granulation or anode casting, then chemical or electrolytic refining. Output: fine gold and silver bars and granules, with base metal values recovered as a by-product salt.

Industrial and automotive spent catalysts — spent three-way catalytic converters in ceramic honeycomb or metallic substrate form, spent petroleum reforming and hydrogenation catalysts, coal-chemical catalysts and fuel cell materials. Processed by milling, sampling, roasting to remove organics, smelting or targeted leaching, solvent extraction, ion exchange and selective precipitation, then reduction and melting. Output: platinum and palladium sponge or powder, rhodium powder or rhodium chloride solution, and a base-metal-bearing residue.

Anode slime and tank house residues — copper, lead, zinc, tin and nickel anode slime, cell mud, refinery sweepings, and platinum- and rhodium-bearing waste refractory brick, glass cullet and burner ash. Processed by washing, drying and roasting for selenium removal, acid leaching to remove copper and base metals, chlorination for gold, selective reduction, and electrolysis of the separated metals. Output: gold and silver powder or crystal, PGM liquor for separation, and selenium and tellurium concentrates.

Electronic waste and board concentrates — printed circuit boards, motherboards, CPU and RAM modules, plug-in cards, connectors and contact pins, gold-plated and silver-plated electronic scrap, and the precious-metal concentrate recovered from a mechanical and thermal e-waste line. Processed by chemical dissolution and electrolytic recovery after de-soldering, component removal and incineration of non-metallics. Output: fine gold and silver, palladium and copper cathode.

Spent process solutions and electrolytes — spent gold, silver, palladium and rhodium plating baths, stripping and deplating solutions, gold etching and iodide etchants, cyanide- and acid-based process solutions, photographic fixing and bleach solutions, electroplating waste liquids and wastewater treatment sludges. Processed by direct electrolytic recovery on concentrated streams and by ion exchange, activated carbon adsorption or precipitation on dilute ones. Output: metal plate, crystal or powder returned to production or re-melted, and treated liquid at parts-per-million residual metal.

Gold-loaded and intermediate streams — gold-loaded activated carbon from CIP and CIL circuits, loaded ion exchange resin, eluate, precipitated and cemented intermediates, secondary black gold powder and abandoned electrolyte. Processed by desorption, elution, reduction, re-leaching and electrolyte purification before being fed back into the head of the circuit. Output: pregnant electrolyte routed to electrolysis and purified electrolyte ready for reuse.

Silver-bearing photovoltaic and industrial streams — delaminated silicon wafers and cell fragments, bus bar offcuts, silver paste-bearing production waste, spent silver-bearing powder and X-ray or film stock. Processed by selective leaching and electrolysis, with silver chloride conversion where chloride media would otherwise passivate the metal. Output: silver crystal and 99.99% silver ingots.

Feed qualification — what this equipment is not designed to process

Stated plainly, because it saves both parties time:

Mixed, uncharacterised feed with no assay — no route can be selected and no responsible recovery figure can be quoted.
Base-metal-dominant material (heavy copper, lead or zinc) without a preceding removal stage — base metals consume reagent and depress precious metal recovery.
High-grade silver or silver-rich doré sent directly to a gold electrolysis cell — silver chloride forms in chloride electrolyte and must be parted first, or handled in a dedicated silver circuit.
Complex, inhomogeneous mixed scrap for which only a photograph is available — a material cannot be routed, priced or guaranteed from an image.
Materials regulated as hazardous waste without the corresponding handling licence at the destination site.
Feed containing mercury, thallium or high-concentration cyanide without a dedicated abatement module.

If your material falls into one of these categories, tell us the composition and we will say so before a quotation is issued.

Output Products

The line delivers finished, saleable metal plus the intermediates that the next stage of refining consumes. Each entry states the form the product leaves the plant in, the fineness it is released at, and the assay behind that figure.

Gold — ingots, bars, granules, sponge and electrolytic powder, and gold anode plates as an in-process intermediate. Refined to 99.99% (4N) as standard, with 99.999% (5N) achievable through a second electrolytic pass, and released against the LBMA Good Delivery minimum fineness for gold. Output: hallmarked gold bars or granules of the weight you specify, cast in vacuum or continuous casting equipment.

Silver — electrolytic silver crystal, silver powder, granule and ingot at 99.99% fineness, with silver cement and silver chloride handled as in-circuit intermediates rather than as waste. Output: silver crystal for industrial sale, and silver ingots for investment or industrial use.

Platinum group metals — platinum sponge, palladium powder and palladium salts, rhodium powder and rhodium chloride solution. Delivered at a minimum of 99.95% for platinum and palladium and 99.90% for rhodium. Output: sponge, powder or purified salt released against ICP-OES verification, and ammonium hexachloropalladate or ammonium hexachloroplatinate where the downstream process requires the salt.

Copper — copper cathode, plate and copper sulphate solution recovered in parallel from impurity removal and electrolyte purification duty, at 99.99% fineness for the cathode product. Output: LME Grade A equivalent cathode and copper salt for sale or return to a copper circuit.

Recovered metal plate, crystal and powder — gold, silver and palladium plate, crystal or powder stripped directly from the recovery cathode at 95–99.8% fineness, and silver crystal from the silver cell. Output: metal ready for re-melting or for direct return to the plating anode.

Intermediate refining solutions — chloroauric acid solution, silver nitrate electrolyte, PGM chloride liquors and loaded resin or carbon eluate. Output: standardised feed liquor that can be metered into the next stage of the circuit, or shipped to a partner refinery under custody documentation.

Treated water and recycled process liquid — clarified, neutralised and polished liquid with precious metal content reduced to parts-per-million levels. Output: water suitable for recirculation to the rinse or plating line, reuse as coolant and cleaner, or release to the wastewater plant.

By-product streams — selenium and tellurium concentrates from anode slime treatment, base metal salts recovered from bleed treatment, and dewatered sludge that has been assayed and released. Output: secondary saleable products plus a residue certified as below the economic recovery threshold.

Process Workflow

The flowsheet combines chemical, electrochemical, thermal and separation duties. Which stages a project includes depends on the feed: a jewellery refiner working on high-grade scrap may run aqua regia dissolution, reduction and one electrolytic finishing cell, while an anode slime or catalyst project will normally use every stage below. Steps 1 and 11 apply to every project.

Steps 1 — Assay and Route Design. Incoming material is weighed, logged and sampled, then characterised by XRF screening and, where the metal content is payable, by fire assay or wet chemical analysis to ISO 11426 or ASTM E1335. The result fixes the feed grade, the separation sequence and the refining route — aqua regia, electrolytic, pyrometallurgical or a combination — before any equipment is sized. Output: a weighed batch with a representative assay, a batch identifier, and a signed route decision.

Steps 2 — Feed Preparation and Granulation. Solid feed is dismantled, de-soldered, stripped of non-metallics and pre-crushed, then ground or milled to a uniform particle size. Metal is granulated or shot where the feed arrives as bar or alloy, because surface area per unit mass is what controls the rate of the dissolution step that follows. Organics are removed by roasting or incineration with afterburner treatment; dust and fines are captured by a dust collection system. Output: a homogenised, sized, organics-free feedstock ready for melting or direct dissolution.

Steps 3 — Melting and Anode Casting. Crude gold, doré and silver-rich material is melted in a medium-frequency or induction melting furnace with flux, sampled and cast — into anode plates for electrolysis, or into granulated shot for chemical dissolution. Anode moulds are produced in high-purity graphite or machined steel, and anode weight and thickness are controlled because they set the current density and the cycle time of the electrolytic stage. Output: cast anode plates of known weight, with a sample sent to assay.

Steps 4 — Chemical Dissolution. Prepared feed is dissolved in agitated, heated and corrosion-resistant reactors. Gold is taken into solution by chlorination or aqua regia chemistry; silver goes through nitric acid dissolving; platinum group metals are dissolved in chloride media with hydrochloric acid and chlorine or oxygen as oxidant, or by pressure leaching where the matrix requires it. Acid ratio, oxidant addition rate, temperature and residence time are controlled and recorded per batch, and dissolution runs under an enclosed hood with the vapour routed to the scrubbing train. Output: pregnant solution, with undissolved residue returned for re-treatment rather than discarded.

Steps 5 — Filtration and Solid-Liquid Separation. The pregnant solution is separated from insolubles by bag filtration, precision filtration to 5 μm, vacuum filter discs or a filter press, so that no value is carried out with the residue and no solids are carried into the cell. Filter cake is washed counter-currently, sampled and either returned to dissolution or released after assay. Output: clear, particle-free solution for the conditioning stage and a washed, assayed residue.

Steps 6 — Solution Conditioning and Impurity Removal. The solution is adjusted before the metal is recovered: excess nitric acid is destroyed, pH, ORP and chloride concentration are set, and base metals are removed by impurity removal and purification kettles, cementation with iron or base-metal powder, or controlled precipitation. Silver chloride, where present, is separated in this stage rather than being allowed to pass into a chloride electrolyte. Output: conditioned, low-impurity solution at a known metal concentration, and a base metal or silver chloride stream routed to its own recovery step.

Steps 7 — Selective Separation and Reduction. The target metal is brought out of solution. On the chemical route, reducing agents such as saturated sodium metabisulfite, sodium sulfite or hydrazine are dosed under controlled temperature so that gold, then palladium, then platinum come down in sequence rather than together; on the hydrometallurgical route, platinum, palladium and rhodium are separated from each other by mixer-settler solvent extraction with P204, P507 and C272 systems, ion exchange, cementation and ammonium salt precipitation. Addition rate and end point are monitored continuously rather than left to the operator’s eye. Output: separated metal powder or salt of each metal, and a barren liquor that is polished before discharge.

Steps 8 — Electrolytic Refining. Purified metal is deposited in electrolytic cells. Gold runs in a Wohlwill-type cell with cast anodes and pure gold starter sheets in a chloroauric acid electrolyte; silver runs in a nitrate electrolyte where the metal deposits as crystalline grains; platinum group metals are recovered by electrowinning from chloride liquor. Cathode current density, electrolyte temperature, circulation, filtration and additive levels are controlled per batch, and electrolyte is regenerated rather than discarded. Output: high-purity cathode gold, electrolytic silver crystal and PGM metal, plus anode slime from the cell floor, which is itself a payable stream.

Steps 9 — Washing, Drying and Product Handling. Deposited metal is stripped from the cathode, washed with hot deionised water and dilute acid until neutral, then dried in a controlled-temperature oven. Washing water is not sent to drain: it is returned to the circuit and its residual metal recovered by activated carbon adsorption, so that the metal balance closes on the wash stream as well as on the main liquor. Output: clean, dry, weighed metal — powder, crystal, sponge or plate — ready for melting.

Steps 10 — Melting, Casting and Assay Release. Dried metal is melted in an induction furnace under flux, then cast into bars, granules or anode plates, or atomised into powder. Vacuum and continuous casting options improve surface finish and reduce oxidation loss. Each batch is re-assayed and released against a Certificate of Analysis naming the method used, with the weight, fineness and serial number recorded. Output: marked, weighed and documented finished product for sale, custody transfer or customs declaration.

Steps 11 — Off-Gas, Wastewater and Recirculation. This step runs continuously across steps 1 to 10 rather than after them. Nitrogen oxides, chlorine and acid vapour are captured under enclosed hoods, condensed to reflux the volatilised electrolyte back into the vessel, and washed in a multi-stage alkaline scrubbing tower with automatic caustic dosing and pH control before discharge. Wastewater is neutralised, precipitated, flocculated and dewatered; activated carbon and ion exchange polish the clear liquor, which is recirculated to the process or reused as coolant and cleaner. Sludge is dried and assayed, and anything above the economic threshold returns to step 4 instead of leaving as waste. Output: gas and water monitored to the agreed discharge limits, a zero-liquid-discharge option, and metal losses closed back into the circuit.

Product Structure (Main Equipment)

The line is assembled from the modules below. Any module can be supplied on its own for a customer upgrading an existing refinery, or as a complete system with process design, layout, utilities, installation, commissioning and operator training.

Dissolution and reaction module — heated Titanium Grade 2 dissolution reactors in single-layer electric or double-layer steam-heated execution, borosilicate glass 3.3 reaction vessels and high-level tanks where transparency and zero metal adsorption are required, rotatable PPH reduction kettles, and enamel-lined primary reduction, secondary reduction and purification kettles for silver duty.

Reagent dosing and storage module — acid storage and metering tanks for hydrochloric and nitric acid, calibrated dosing pumps that maintain the aqua regia ratio automatically, saturated sodium metabisulfite mixing tanks with agitator, urea or neutralising agent dosing for nitric acid destruction, and secondary containment bunding for every chemical store.

Solid-liquid separation module — bag-type filters, precision filters with 5 μm accuracy, PPH vacuum filter discs, filter presses, decanter centrifuge and candle filters, with counter-current wash circuits and filtrate return lines.

Solution conditioning module — impurity removal and purification kettles, cementation tanks, pH and ORP adjustment stations, glass high-level tanks and intermediate storage, and electrolyte preparation and regeneration tanks.

Electrolytic refining module — gold electrolysis cells with an AC/DC superimposed power supply that suppresses silver chloride formation in the cell, silver electrolysis cells with mechanical electrolyte circulation, electrolyte cooling and automatic cathode scraping, pure titanium cathode plates and starter sheet frames, high-purity graphite anode moulds, titanium-clad copper conductive and bus bars, anode bags and diaphragms in acid-resistant fabric or PTFE, and closed electrolyte circulation with continuous filtration.

Power and rectifier module — rectifier power supply with separate closed enclosure isolated from the acid gas in the workshop, intelligent monitoring of electrolyte temperature, cell voltage, cell current and bus bar temperature, automatic pole reversing, and DC distribution with current-density control.

Melting, granulation and casting module — medium-frequency and induction melting furnaces with graphite or ceramic crucibles, flux dosing, granulation unit for shot production, ingot and bar moulds, vacuum or continuous casting unit, bar stamping and marking, and cupellation furnace plus fire assay kit for the assay room.

Off-gas treatment module — enclosed operating and reaction fume hoods, transparent closed covers for the dissolution vessels, flue gas condensation unit that refluxes volatilised electrolyte and prevents gold loss to the stack, two-stage or three-stage PPH alkaline scrubbing tower with automatic caustic dosing and pH control, mist eliminator, centrifugal fan and monitored exhaust stack.

Wastewater and residue module — neutralisation and precipitation tank, flocculation and sedimentation, filter press for sludge dewatering, activated carbon adsorption to recover residual precious metal, ion exchange polishing, and a recirculation circuit with zero-liquid-discharge configuration where required.

Water and utilities module — pure water unit and reverse osmosis or demineraliser, chiller, steam generator or electric steam supply for jacketed kettles, compressed air, vacuum unit, and process cooling circuit.

Control and automation module — PLC and HMI control cabinet with recipe management per feed type, automatic reagent dosing, precipitation end-point detection by sensor, temperature and pH control loops, logging of temperature, pH, ORP, conductivity, flow, current and current density, alarm management, interlock and emergency stop, and remote monitoring access.

Laboratory and verification module — XRF spectrometer or benchtop analyser, precision balance, sample preparation equipment, fire assay consumables and cupellation furnace, ICP-OES sampling protocol and third-party laboratory liaison, and the batch record system that carries the metal balance from intake to release.

Product Features

Four refining routes in one scope — chemical aqua regia, electrolytic, pyrometallurgical and the separation, filtration and assay systems around them, supplied by one engineering team instead of three contractors with three sets of interface risk.
Route chosen from your assay, not from a catalogue — feed grade, matrix, silver content and base metal load decide the flowsheet, and low-grade or mixed feedstock is engineered for rather than refused.
Corrosion-resistant construction specified by grade — Titanium Grade 2 dissolution reactors, borosilicate glass 3.3 vessels, PPH, PP, PVDF and PTFE wetted parts, enamel-lined reduction kettles, 316L stainless steel where chloride attack is not a factor, and titanium-clad copper conductive bars.
Aqua regia and electrolysis engineered to work in series — chemical dissolution and precipitation in front of an electrolytic finishing cell, which is how a low-grade or silver-bearing feed reaches 99.99% without a separate plant.
Electrolyte management built in — closed circulation, continuous filtration, cooling to hold the electrolyte at its working temperature, AC/DC superimposed power supply to suppress silver chloride formation, and regeneration of spent electrolyte instead of disposal.
Automatic cathode handling — mechanical electrolyte circulation and automatic scraping on silver cells reduce manual intervention and keep cathode quality stable from the first plate to the last.
Capacity stated on a defined basis — quoted as kg per batch and cycles per day at a stated feed grade, so the number can be checked against the metal balance rather than interpreted after purchase.
Recovery stated on a defined basis — the metal-balance formula behind every recovery figure is published in the proposal, so the claim can be verified against your own assays.
Purity claims carry the assay method — ISO 11426, ASTM E1335, ISO 15093 and ISO 15096 are named against the corresponding figure, which matters when a third party assays the bar on arrival.
Closed environmental control — enclosed hoods, flue gas condensation and reflux, multi-stage alkaline scrubbing for nitrogen oxides and chlorine, and a wastewater circuit that neutralises, polishes and can close to zero liquid discharge.
No value left in the drain — activated carbon adsorption and ion exchange recover the residual metal from wash water and effluent, and filter cake, cell slime and off-spec product return upstream instead of leaving as waste.
Corrosion-resistant control architecture — the rectifier and control cabinet are housed in a separate closed enclosure isolated from acid gas in the workshop, which is what keeps electronics alive in a refinery environment.
Batch traceability and metal balance — weighing, sampling and assay points at every stage produce a documented metal balance per batch for custody transfer, customs and internal accounting.
Modular scalability — additional cells, reactors or refining modules connect through standardised interfaces, so capacity is added rather than replaced.
Audit-ready documentation — operating manual, maintenance manual, P&ID, electrical drawings, instrumentation list, spare parts list, material certificates and commissioning report, prepared for local regulatory inspection.

Technical Parameters And Specifications

Values below are the standard design basis. Final parameters are fixed during process design, after the customer’s feedstock has been assayed and bench-tested. Parameters marked * are confirmed per project.

1. System Scope And Process Route

Parameter	Specification
Technology families covered	Chemical (aqua regia) refining · electrolytic refining · pyrometallurgical melting, granulation and cupellation · filtration, assay and environmental systems *
Primary route selection drivers	Feed grade, silver content relative to gold, base metal load, organic content, physical form, target fineness, local emission rules *
Chemical route	Aqua regia or chlorination dissolution → filtration → conditioning → selective reduction and precipitation → washing and drying → melting and casting
Electrolytic route	Melting and anode casting → electrolyte preparation → Wohlwill-type gold electrolysis or silver nitrate electrolysis → cathode stripping → washing, drying, melting and casting
Hydrometallurgical separation route	Roasting or smelting → acid or chloride leaching → solvent extraction (P204 / P507 / C272), ion exchange and cementation → electrowinning or precipitation *
Precious metal capacity basis	Stated as kg per batch × cycles per day at a defined feed grade and fineness target; scaled by module count rather than by a fixed model size *
Operating mode	Batch or continuous, or a batch front end feeding a continuous electrolytic stage *
Scope of supply	Single module, one refining route, or complete turnkey refinery from feed intake to stamped bar *

2. Feed And Product Parameters

Parameter	Specification
Typical feed grade, gold	70%–99% Au for doré, bullion and jewellery alloy feed; lower-grade concentrates accepted after assay and bench test *
Typical feed grade, silver	95%+ Ag for silver-rich doré and alloy feed; lower-grade and silver-bearing process streams accepted after test *
Minimum feed grade for direct electrolysis	Set per project from the anode quality the refinery can cast; high base metal or silver content requires a preceding removal stage *
Final product purity, gold	99.99% (4N) standard; 99.999% (5N) achievable on a second electrolytic pass *
Final product purity, silver	99.99% *
Final product purity, platinum / palladium	≥ 99.95%, verified by ICP-OES difference analysis *
Final product purity, rhodium	≥ 99.90% *
Purity of metal stripped from the recovery cathode	95–99.8%, then refined further *
Comprehensive recovery rate	≥ 95% design target on qualified multi-metal feed
Recovery rate, electrolytic route	> 99% from high-grade electrolyte *
Residual metal in treated water	Silver and gold reduced to parts-per-million levels; target fixed during process design against your discharge standard *
Recovery calculation basis	(metal in feed − metal in final slag − metal in filter residue − metal in effluent) ÷ metal in feed — stated in the proposal so it can be checked against your own assays

3. Process Parameters

Parameter	Specification
Cathode current density, gold electrolysis	Up to 1000–1200 A/m², depending on anode quality and cell design *
Cathode current density, silver electrolysis	300–800 A/m², adjustable within the cell’s design envelope *
Electrolyte temperature, gold	60–70 °C, held by jacketed or immersed heating with condensation reflux *
Electrolyte temperature, silver	Controlled by cooling circuit, typically ≤ 50 °C *
Temperature control accuracy	± 1 °C in electrolytic refining cells
Gold concentration in electrolyte	120–150 g/L as the working reference for a standard gold cell *
Electrolysis cycle time	Approximately 20–22 hours per batch at the reference current density; set per project by anode weight and target deposition *
Precious metal inventory in process	Quantified in every proposal — electrolyte, anode plates and in-process stock are real working capital, not a rounding item *
Dissolution temperature	Set per chemistry, typically 40–70 °C for aqua regia and chloride media; boiling conditions only in rated vessels *
Filtration accuracy	Precision filtration to 5 μm as standard; finer polishing before the electrolytic cell where the feed requires it *
Electrolyte circulation	Closed loop with continuous filtration and temperature control
Silver chloride control	AC/DC superimposed power supply in the gold cell plus a dedicated silver circuit, so that silver chloride is managed rather than allowed to co-deposit
Reagent systems	Aqua regia (HCl + HNO₃), nitric acid, chlorination, sodium metabisulfite / sodium sulfite, hydrazine, urea for nitric acid destruction, sodium hydroxide scrubbing liquor, flux system per melt *

4. Materials Of Construction

Stream or equipment	Material options
Heated dissolution reactors	Titanium Grade 2 (single-layer electric or double-layer steam-heated execution)
Transparent reaction and high-level vessels	Borosilicate glass 3.3
Reduction, purification and precipitation kettles	PPH, PP, PVDF, and enamel-lined steel for silver duty
Acid storage and metering tanks	PPH, PVC, PVDF, FRP, PE with secondary containment
Electrolytic cell bodies	PPH, PP, PVC-lined steel, PTFE- or PVDF-lined, with concrete or FRP shells for large silver cells
Cathode and anode substrates	Pure titanium plate, stainless steel, MMO-coated titanium, high-purity graphite for anode moulds
Conductive bars and bus bars	Titanium-clad copper; No. 1 red copper for terminal duty
Wetted parts, pumps and fittings	PTFE, PVDF, fluorine-lined magnetic pumps, titanium, 316L stainless steel
Off-gas ducting, condensers and scrubbers	PPH, FRP, PVC, borosilicate glass
Crucibles and refractories	High-purity graphite, clay-graphite, ceramic, refractory-lined furnace shells

5. Control, Utilities and Environmental Parameters

Parameter	Specification
Control system	PLC + HMI with recipe management per feed type, automatic reagent dosing and remote monitoring access
Precipitation end-point control	Continuous sensor-based detection rather than operator judgement alone
Instrumentation	Temperature, pH, ORP, conductivity, flow, level, cell voltage, cell current and current density
Data logging	Batch-based recording of process parameters, consumption and metal balance
Off-gas treatment	Enclosed hoods + flue gas condensation and reflux + two- or three-stage alkaline scrubbing with automatic caustic dosing and pH control; removal efficiency and outlet concentration set to the local permit limit *
Wastewater treatment	Neutralisation, precipitation, flocculation, sludge dewatering, activated carbon adsorption and ion exchange polishing; recirculation with a zero-liquid-discharge option *
Solid residue handling	Filter cake, cell slime and sludge dried, assayed and returned upstream when above the economic threshold
Power supply	Configured to the local grid — 380 V, 415 V or 440 V, 50 Hz or 60 Hz, three-phase, with single-phase control circuits *
Utilities	Process water, pure or demineralised water, cooling water or chiller, compressed air, vacuum, exhaust ventilation, steam for jacketed vessels
Installation form	Modular skid-mounted or site-assembled, with CAD or 3D plant layout matched to your building and yard
Site data required at design stage	Floor area and headroom, floor loading, drainage and bunding, exhaust route, power capacity, water quality and chemistry of the site *

6. Assay, Verification And Product Release

Stage	Method	Reference standard
Feed sampling and assay	Representative sampling, XRF screening, fire assay or wet chemical analysis	ISO 11426, ASTM E1335
In-process control	Titration, ORP measurement, specific-ion and conductivity measurement	Per project
High-purity gold, platinum, palladium	Difference method by ICP-OES	ISO 15093
High-purity silver	Difference method by ICP-OES	ISO 15096
Final product release	Fire assay to 999.5‰, or ICP-OES difference analysis above that fineness	ISO 11426, ISO 15093, ISO 15096
Good Delivery compliance	Fineness held at or above the LBMA Good Delivery minimum (995.0 gold, 999.0 silver)	LBMA Good Delivery Rules
Batch documentation	Certificate of Analysis per batch with weight, fineness, assay method and serial number	Per project

7. Assay, Verification And Product Release

Stage	Method	Reference standard
Feed sampling and assay	Representative sampling, XRF screening, fire assay or wet chemical analysis	ISO 11426, ASTM E1335
In-process control	Titration, ORP and specific-ion measurement	Per project
High-purity gold, platinum, palladium	Difference method by ICP-OES	ISO 15093
High-purity silver	Difference method by ICP-OES	ISO 15096
Final product release	Fire assay to 999.5‰, or ICP-OES difference above that fineness	ISO 11426, ISO 15093, ISO 15096
Good Delivery compliance	Fineness against LBMA Good Delivery minimum (995.0 gold, 999.0 silver)	LBMA Good Delivery Rules

Important. Precious metal refining involves strong acids, chlorine gas, nitrogen oxides and molten metal. Do not scale or operate a process from published text alone. Final design must be validated by our engineers against your specific feed, local regulations and site conditions.

Technical Advantages

Four routes from one supplier. Most of the market sells either a chemical refining package or an electrolytic cell, and leaves the buyer to bridge the gap. YuSai engineers aqua regia dissolution, precipitation, electrolytic refining, melting and casting, and the environmental train as one line, so the separation chemistry and the cell are matched to each other by design review instead of by site improvisation.

Route selection is argued in writing, before the order. Every proposal compares the applicable routes for your material — chemical, electrolytic, pyrometallurgical or combined — with the feed grade each route assumes, the fineness each can reach and the capital and operating consequences of each. If aqua regia is the better commercial answer for your feed, we will say so even though an electrolytic cell is the larger sale.

Recovery is stated on a defined basis. We publish the metal-balance formula behind every recovery figure, so the number can be checked against your own assays. A percentage without a basis cannot be audited, and in this industry the buyer usually discovers the difference at the first settlement.

Purity claims come with the assay method attached. Naming ISO 11426, ASTM E1335, ISO 15093 and ISO 15096 makes each fineness figure independently reproducible, and it is the difference between a certificate your buyer accepts and a conversation about sampling.

Capacity is quoted in units that survive contact with production. kg per batch and cycles per day at a stated feed grade, not a bare kg/day figure that silently assumes a different feed. This ambiguity is the single most common misunderstanding in the category, and it is cheaper to resolve in the proposal than on the shop floor.

Working capital is treated as a design variable. The precious metal immobilised in electrolyte, anode plates and in-process inventory is quantified in every proposal — a gold cell holds real metal that is not available for sale, and it belongs in the investment decision.

Capacity to handle silver, not just gold. Silver chloride formation is the classic failure mode of a single-pass gold refining line: silver-rich feed must be parted or run in its own circuit, and the gold cell is equipped with an AC/DC superimposed power supply to suppress chloride generation in the cell. Silver is designed in, not discovered during commissioning.

Materials specified by grade, not by adjective. Titanium Grade 2 dissolution reactors, borosilicate glass 3.3 vessels, enamel-lined silver reduction kettles, PPH and PVDF wetted parts, titanium-clad copper bus bars, and a rectifier enclosure isolated from the acid atmosphere of the workshop. Material specification is what decides whether the plant is still running in ten years.

Fewer consumables and less downtime. Electrolyte is regenerated rather than replaced, which reduces make-up reagent consumption; ion exchange and activated carbon are regenerated on a schedule; anode bags, cathodes and gaskets are service items with published lives in the spare parts schedule.

Environmental compliance inside the scope of supply. Enclosed hoods, flue gas condensation with reflux back to the vessel, multi-stage alkaline scrubbing and a wastewater circuit are engineered together with the process rather than procured afterwards. Permitting delay is normally the largest single cause of schedule slippage on a refining project.

Working materials are not lost to the wash stream. Residual metal in wash water and effluent is recovered by activated carbon adsorption and ion exchange rather than neutralised into sludge and written off, which is where a surprising share of the difference between a quoted and an achieved recovery figure comes from.

PGM separation handled technically, not verbally. Platinum, palladium and rhodium are separated by solvent extraction with P204, P507 and C272 systems, ion exchange, cementation and ammonium salt precipitation, followed by hydrogen reduction, calcination and melting — with the separation sequence set by bench test rather than by assumption.

Feed disqualification is stated up front. Saying what the equipment cannot process — unassayed mixed feed, base-metal-dominant material, silver-rich feed sent straight to a chloride cell, hazardous waste without a licence — protects the project schedule and the commercial relationship, and it is the information buyers look for after a poor experience elsewhere.

Documentation is audit-ready. P&IDs, instrumentation lists, operating and maintenance procedures, batch records, material certificates and a commissioning report are supplied as a controlled set, so quality-system audits, customs checks and customer claims do not require reconstruction.

Modular and upgradeable. Additional cells, reactors, scrubbing stages or separation modules connect through standardised interfaces, and a laboratory-scale unit can be used to validate a process on the same control architecture before the investment is expanded.

Service Process

Inquiry and Process Consultation — share your feedstock or process stream, its current handling route and the metals you need to recover. We respond with a preliminary route and the sample quantity and site information required for testing.
Raw Material Testing and Assay — we analyse your sample by XRF screening, fire assay or wet chemical analysis and run bench-scale dissolution, reduction, adsorption and deposition tests, then issue a test report stating recoverable metal content, expected recovery rate and the proposed separation sequence.
Route Selection and Flowsheet — a written comparison of the applicable routes for your material, with the process flow diagram, mass balance, chemical consumption and utility requirements for each, so the decision is made on data.
Process Design and Plant Layout — equipment list, capacities stated as batch mass and cycles per day, instrumentation and control concept, and a CAD or 3D layout matched to your building, headroom, drainage, exhaust route and power supply.
Quotation and Contract — a detailed commercial proposal covering equipment scope, spares, documentation, shipping terms and service scope, with the lead time stated as a commitment rather than an estimate.
Detailed Engineering — P&IDs, equipment specifications, electrical and control design, materials certificates plan, and the emission and effluent data needed to support your permit applications.
Manufacturing and Factory Acceptance Test — fabrication follows approved drawings and the specified materials of construction. Key assemblies are tested at the factory and a factory acceptance test report with photographs and video is issued before shipment.
Packing, Shipping and Documentation — export packing and container loading with a full shipping document set, including packing list, certificate of origin and the technical documentation package.
Site Installation — our engineers attend site to supervise mechanical erection, electrical and piping connection, exhaust and drainage connection, and water, gas and power commissioning.
Commissioning and Metal Balance Verification — cold and hot commissioning, tuning of process parameters on your actual feed, and verification of the batch metal balance. The line is handed over only after it produces metal at the agreed specification.
Operator Training and Handover — operating and maintenance personnel are trained on process control, reagent handling and storage, safety procedures, sampling and assay routines, electrolyte management and daily maintenance. Written manuals and video guides are supplied.
After-Sales Support and Process Review — remote and on-site technical support, spare parts supply, periodic service visits, electrolyte and process reviews when the feed mix changes, and upgrade or retrofit service for the operating life of the line.

Warranty And After-Sales

Warranty period. The complete plant carries a 12-month warranty from the date of production handover, or 18 months from the date of shipment, whichever falls earlier. Structural components — electrolytic cell bodies, tank structures and frame assemblies — carry an extended warranty against defects in material and workmanship. Warranty terms are confirmed in the contract for each project.

Wear parts excluded. Consumable and wear items — eddy current conveyor belts, splitter plates, screens, crusher blades, filter cloth, pump seals, gaskets and refractory materials — are excluded from the standard warranty and are supplied as recommended spare parts with their expected service life stated.

Spare parts guarantee. Spare parts for the supplied equipment remain available for a minimum of 10 years from handover. A recommended first-year spare-parts kit is supplied with the plant, and a critical-spares list is agreed with the customer so that no single consumable can stop production while a replacement is in transit.

Response times. Technical inquiries are answered within 15 minutes during working hours and within 2 hours outside them. A remote diagnosis is completed within 12 hours of a reported fault, and where an on-site visit is required, an engineer is dispatched within 24 hours of fault confirmation, subject to visa and travel arrangements.

Remote support. The control system supports remote diagnostics, allowing engineers to review alarm history, dosing records, cell current and rectifier data without travelling to site, and to identify the cause of a production deviation before an on-site visit is scheduled.

On-site service. Commissioning support and warranty service visits are included in the contract scope. Regular preventive maintenance visits are available under an annual service agreement, covering inspection of the separation modules, calibration of instrumentation, review of process data and a written performance report with recommendations.

Training and documentation. Operator and maintenance training is delivered during commissioning, and refresher training is available on site or online. The documentation package includes the operation manual, maintenance manual, electrical and instrumentation drawings, spare-parts catalogue, process description and the material test report.

Performance guarantee. Where a project is supplied on a turnkey basis, the guaranteed recovery and purity figures established by the material test are written into the contract, and performance is verified during commissioning against the agreed test procedure.

Frequently Asked Questions

What is non-ferrous metal extraction equipment?
It is the processing line that recovers non-ferrous metals — copper, aluminium, brass, zinc, nickel, tin, lead and precious metals — from scrap, waste streams and low-grade concentrates, and upgrades them into saleable metal products. A complete line combines physical separation (magnetic separation, eddy current separation, sensor sorting and screening) with pyrometallurgical concentration and hydrometallurgical extraction, followed by electrowinning or electrorefining to produce cathode metal.

Which non-ferrous metals can your equipment recover?
Copper, aluminium, brass, bronze, zinc, nickel, cobalt, tin, lead, antimony and precious metals including gold, silver and the platinum-group metals. The metal that can be produced depends on the feed: mixed scrap and bottom ash are separated into metal concentrates and refined downstream, while oxide ores, zinc calcine, nickel–cobalt matte and battery black mass go through leaching, solvent extraction and electrowinning.

What recovery rate can I expect?
A well-designed line achieves an overall non-ferrous metal recovery of ≥ 95%, and copper electrorefining typically reaches 99.6 – 99.8%. Recovery is always stated against a defined feed grade and particle-size distribution, because the same machine will produce different results on different feeds. We therefore confirm the figure for your specific material through a material test rather than quoting a single number for all applications.

Can the plant start small and be expanded later?
Yes. The line is built from standardised modules, so a project can begin with a single 1 t/h separation module and a 1 t/day cathode stripping unit, and expand by adding modules — an additional eddy current unit, further mixer-settler stages or an extra cell section — without redesigning the flowsheet. Sizing margins are designed into the mass balance at the outset to allow this.

What particle sizes can the eddy current separator handle?
The rotor assembly is matched to the feed fraction. A coarse-pole rotor handles material above 40 mm, a medium-pole rotor covers approximately 6 – 25 mm, and a high-frequency rotor treats fines. With an ultra-high-frequency rotor, bare copper wire and fine aluminium down to 2 – 3 mm can be recovered — material that is normally lost to the tailings on a conventional separator.

Eddy current separation or sensor-based sorting — which do I need?
Eddy current separation sorts by conductivity and is the right first stage for separating non-ferrous metal from non-metal. Sensor-based sorting sorts by material composition, so it is added when the metal concentrate has to be split by alloy — copper from brass, wrought aluminium from cast aluminium, or a specific alloy out of a mixed stream. Most lines use eddy current separation as standard and add sensor sorting as an upgrade where product specifications demand it.

What is the difference between electrowinning and electrorefining?
In electrorefining, an impure anode plate is dissolved and the metal is re-deposited on the cathode at high purity — the classic route from copper anode at Cu ≥ 98% to cathode copper at Cu ≥ 99.99%. In electrowinning, metal is won directly from a purified leach solution onto the cathode, with no anode dissolution step. Electrorefining needs an anode casting step upstream; electrowinning needs a leaching and solution purification circuit upstream.

How much does a non-ferrous metal extraction plant cost?
Cost is driven by four variables: the feed material, the target capacity, the product specification and the scope of works. A single eddy current separation module is a modest capital item, while a complete leach → solvent extraction → electrowinning plant with a tank house and precious-metal circuit is a full industrial project. Send us your material type, expected capacity and target product, and we will return a budget indication with the process route, equipment list and a phased investment plan so that the project can be built in stages.

Can you test my material before I commit to a plant?
Yes, and we prefer to. A representative sample is tested for screening analysis, magnetic and eddy current response and chemical assay, followed by leach or separation tests where the material requires a chemical route. The test report establishes the achievable recovery and purity for your actual material and forms the basis of the guaranteed mass balance in the commercial proposal.

What are the power and water requirements?
Both depend on the process route and capacity. As a reference, copper electrowinning and electrorefining consume approximately 230 – 280 kW·h of direct current per tonne of copper, plus rectifier losses and plant services; the physical separation stages draw only the drive power of the conveyors, rotors and screens. Process water is circulated at ≥ 90%, so make-up water demand is limited to losses and the controlled bleed. A utility schedule is issued with the proposal.

Do you provide installation, commissioning and training?
Yes. For turnkey projects we install and commission the plant and verify the guaranteed performance figures on site. For equipment supply projects, our engineers supervise installation and carry out commissioning. In both cases, plant operators and maintenance staff are trained on the running line, with a training manual and documentation package left on site.

What warranty and after-sales support do you offer?
The complete plant carries a 12-month warranty from handover (or 18 months from shipment, whichever is earlier), with an extended warranty on structural components. Spare parts remain available for at least 10 years, technical inquiries are answered within 15 minutes during working hours, remote diagnosis is completed within 12 hours and an engineer can be dispatched within 24 hours of a confirmed fault. An annual preventive maintenance agreement is available.

What certifications and standards apply to your plants?
Equipment is manufactured to CE and ISO requirements, and rectifier transformers are built to IEC standards. Emissions and effluent are designed to meet the applicable local discharge limits at the project site, including workplace acid-mist limits and the regional NOx limit. Any additional certification required by the destination market — electrical, pressure-vessel or environmental — is confirmed at enquiry stage and included in the technical scope.

Can the same line process more than one type of material?
Yes. Because the stages are modular and the rotor assemblies, screens and process recipes are interchangeable, a line can be configured to run several feed types in campaigns — for example mixed non-ferrous scrap during one period and incineration bottom ash or cable granulate in another. The limit is set by the chemistry: a dry separation front end can be re-configured by changing rotors and screens, while a hydrometallurgical circuit is designed around a defined liquor chemistry and normally serves one material family.