Lead Refining Machine

— Lead Refining Machine: Crude Lead to 99.994% Refined Lead

A lead refining machine turns crude lead bullion into certified refined lead ingots and separate payable streams. The bullion arrives at roughly 95% to 99% Pb carrying copper, nickel, arsenic, antimony, tin, silver, zinc and bismuth, and two complementary routes remove those elements one at a time. Fire refining works in refining kettles, where each impurity leaves through a controlled thermal window plus one reagent: sulfur or iron pyrite for copper and nickel, oxygen for arsenic, antimony and tin, zinc for silver and gold, vacuum for zinc, and calcium with magnesium for bismuth. Electrolytic refining dissolves pre-refined anodes in a lead fluosilicate or lead methanesulfonate bath at 35–45 °C and 200–240 A/m², leaving bismuth and the precious metals in the anode slime. YuSai builds both as one line: a kettle train sized to your bullion assay, an electrolytic section where the grade demands it, linear ingot casting, and a fume, effluent and slime train that returns the copper, antimony, bismuth, silver and gold fractions to their own circuits.

Product Overview

A lead refining machine removes the impurities that crude lead bullion carries out of smelting. How much refining is required depends entirely on what is in the bullion, and the reason that matters commercially is that lead is rarely sold as a bare metal number. Buyers specify a grade, grades are defined by published standards, and each standard caps a different list of elements. A refinery that cannot name the standard its output meets cannot price its own product properly.

The base feed is crude lead bullion from a blast furnace, a bottom-blowing furnace or a rotary furnace, and from secondary smelting of spent lead-acid batteries. That bullion typically carries copper at 0.06% to 2%, arsenic, antimony and tin at 0.5% to 3% combined, silver from about 20 ppm to several thousand ppm, zinc, and bismuth ranging from under 0.01% up to several percent. Calcium, barium and aluminium also appear where battery grids and separators have been smelted, and tellurium and selenium appear in small but disproportionately damaging amounts.

Fire refining is the default route because it needs only kettles, burners, stirrers and skimming access, and because each stage is independently controlled. The stages run in a fixed order, and the order is dictated by chemistry rather than tradition. Copper comes out first because its solubility in liquid lead collapses on cooling and because copper sulfide crystals form easily. Nickel follows, and is removed together with copper by treatment with iron pyrite and sulfur, which forms chalcopyrite, bornite and analogous ternary nickel sulfides and pulls both elements below roughly 0.005%. A subsequent zinc or aluminium treatment takes nickel down to trace levels. Arsenic, antimony and tin are then removed by oxidation into a litharge-rich slag; oxygen sparging takes tin and antimony below about 5 ppm, and where antimony is low the same job can be done with fused sodium hydroxide and sodium nitrate in the Harris refining step, whose selectivity is set by the controlled addition of nitrate. Silver and gold are removed by the Parkes process. Residual zinc is removed by vacuum distillation and finished with molten caustic soda. Bismuth, where it must be removed, goes out as a calcium-magnesium bismuthide crust in the Kroll-Betterton step, and a final caustic clean at about 500 °C sweeps any calcium, magnesium, zinc or antimony that carried through.

Electrolytic refining becomes the better commercial answer when the bullion carries enough bismuth or precious metal to justify it. The bullion is pre-refined to bring copper and tin down, cast into anodes, and dissolved anodically in a lead fluosilicate bath. Lead deposits on the cathode at 99.99% class purity while bismuth, silver, gold, copper, tin and arsenic concentrate into anode slime that leaves the circuit for its own recovery line. Electrolytic refining gives a higher metal recovery and a cleaner working environment, and it reaches purity grades that fire refining can only approach by pushing every kettle stage to its practical limit. Its costs are real: a tank house is a larger capital item than a kettle train, it needs pre-refining anyway, and the cathode lead still requires a fire-refining and alloying pass before it is cast into ingots.

YuSai Machinery configures the line against the assay and the target grade. The scope runs from sampling and assay interpretation, through flowsheet and kettle duty allocation, equipment design and fabrication, refractory and burner selection, fume and effluent treatment, PLC and instrumentation, on-site installation and commissioning, operator training, and a certification routine that ties each ingot lot back to a retained sample and an analytical result.

A lead refining machine is either a refining kettle line working by fire refining, or an electrolytic refining circuit. The route is decided by the bismuth and precious-metal content of the bullion, not by the purity figure written on the enquiry.
The kettle line is a temperature-sequence machine, not a melting pot. Copper and nickel dross out on cooling from about 700 °C to 330 °C, arsenic, antimony and tin oxidise out at about 600 °C, the silver-zinc crust is ejected by cooling toward the 327.5 °C freezing point of lead, zinc is vacuum-distilled at about 600 °C, and the calcium-magnesium bismuthide crust forms at about 350 °C.
Fire refining commercially reaches the 99.985% and 99.990% grades. These are published grades, not marketing figures: BS EN 12659 PB985R and PB990R, and GB/T 469 Pb99.985 and Pb99.990.
Electrolytic refining is the lower-risk route to the 99.994% class of GB/T 469, where bismuth must sit at or below 0.004%, because bismuth and the precious metals report quantitatively to the anode slime in a single operation instead of depending on a narrow crusting window.
The desilverizing crust is a payable silver concentrate running about 20% Ag. It is the entry point of the precious-metal refinery, and it is why a lead refining machine belongs in a precious-metal recovery line rather than beside it.
The electrochemical equivalent of lead is 3.866 g per ampere-hour for the Pb2+ / 2-electron reaction, so 1 kA of rectifier current deposits about 92.8 kg of lead per day at 100% current efficiency.
Specific energy checks out against published practice: 3.866 g/A·h at 95% current efficiency is 272,000 A·h per tonne, and at 0.5 V that is about 136 kWh per tonne, inside the 120–150 kWh/t band reported for lead electrorefining.

Product Core Selling Points

The route decision is published, not assumed. Every competitor page quotes a purity number. This page tells you which number your bullion can actually reach, and why. A bullion low in bismuth and precious metals is cheaper to refine by fire and will hold at PB985R. A bullion above roughly 0.5% bismuth, or one carrying recoverable silver and gold, is a different machine, and the machine is configured that way from the start rather than discovered during commissioning.
The process is driven by cooling, and the machine is designed around that. Every impurity in liquid lead has a solubility that falls faster with falling temperature than lead itself does. That single physical fact is the whole refining sequence. The kettle is therefore engineered as a controlled thermal window with agitation and skimming access at each stage, not as a heated vessel that happens to have a stirrer. Lead freezes at 327.5 °C and the desilverizing crust only separates in the narrow band just above it, so the cooling programme is a design parameter, not an operating habit.
Output is mapped to named grades you can sell against. The line is commissioned to a grade, and the grade is defined by a published standard. BS EN 12659:1999 grades PB970R, PB985R and PB990R are registered for London Metal Exchange delivery. GB/T 469-2013 defines Pb99.970 through Pb99.994. ASTM B29-19 defines the pure lead and chemical-copper lead grades used in North American battery and corrosion-protection markets. Your certificate of analysis can name any of them, because the stage cut-off is set to hit that grade rather than to hit a round number.
Precious metals are a product line, not a nuisance. The Parkes desilverizing stage concentrates silver and gold into a zinc crust at roughly 20% Ag, which is a directly saleable intermediate and the natural feed to a silver or gold refinery. The copper-nickel dross, the antimonial litharge, the bismuth crust and the anode slime are each a defined stream that leaves the machine in a form its own downstream process can accept. A lead refinery that treats these as waste is discarding most of its gross margin.
One kettle train, several product grades, including alloys. The same vessel set produces soft refined lead for battery active material and pure lead for radiation shielding, and then doses calcium, tin or antimony to produce Pb-Ca, Pb-Sn and Pb-Sb grid and parts alloys. The alloying stage runs in the same kettle as the final caustic polish, which means a plant can switch between refined lead and alloy on a batch basis without a second investment.
Batch flexibility with a continuous casting tail. Kettle refining is inherently batch, which is what makes it tolerant of varying bullion quality, but the downstream casting is linear and continuous: chain conveyor, circulating cooling water, ingot stamping and palletising. The result is batch metallurgy feeding an industrial packaging rate, without holding molten lead waiting for a manual mould line.
Emissions are a design input, not a retrofit. Lead refining is regulated on particulate lead, arsenic, cadmium and nickel, and the reference practice is a wet electrostatic precipitator plus a regenerative thermal oxidiser rather than a baghouse alone. The machine is engineered with sealed charging, hooded kettles, negative-pressure ducting, baghouse and alkaline scrubbing as standard scope, sized against the local ambient lead standard in your jurisdiction.
Sample first, then design the line. The stage cut-offs, the kettle count, the reagent consumption and the achievable grade all depend on your bullion assay, and the assay is the first deliverable, not the last. Send a representative sample and the refining route is fixed against measured chemistry before any fabrication starts.

Application Scenarios

Secondary lead smelters producing refined lead ingots for sale. The most common installation. Bullion arrives from a rotary or reverberatory furnace at 95% to 99% Pb, and the machine delivers battery-grade refined lead, an antimonial alloy stream, and a silver-zinc crust sold to a precious-metal refiner.
Primary lead smelters and lead concentrate processors. Where the refinery is the plant that recovers the payable by-products rather than the lead itself. Bullion from a sinter and blast furnace route carries silver, gold and bismuth at values that justify the full kettle sequence and, where bismuth is high, an electrolytic section to concentrate it into slime.
Lead-acid battery manufacturers with in-house recycling. Vertically integrated battery producers refining their own returned scrap into grid alloy and active-material lead, which is the tightest specification in the market because nickel, tellurium and selenium contamination causes gassing and shortens battery life far more than the same level of antimony or tin does.
Lead-acid battery breaking and separation plants. Plants that already produce lead paste, grids and metallic fines but sell them as low-value intermediates. Adding a refining machine converts that output into certified ingots and moves the margin from the scrap trader to the recycler.
Precious-metal refineries handling lead-rich intermediates. Refineries that receive lead bullion, lead matte, lead-bearing anode slime or lead-zinc ore concentrates where lead is the carrier and silver and gold are the value. Here the lead refining machine is deliberately the front end of a precious-metal line, and the design priority is quantitative transfer of silver and gold into the crust and the slime rather than maximum lead throughput.
Non-ferrous foundries, cable and lead scrap processors. Recovery of lead from cable sheathing, lead sheet, pipe, printing metal, solder dross and machine-shop turnings, where the feed is clean but the alloy content is mixed and the machine must switch between soft lead and alloys on a batch basis.
Electronic waste and CRT processing operations. Leaded glass and lead-tin solders from display and electronics recycling, where the lead fraction is a large mass stream that carries small but recoverable amounts of silver and must be stabilised into saleable ingots rather than landfilled.
Radiation shielding and industrial lead product manufacturers. Producers who need certified high-purity lead as an input and who are sensitive to antimony and bismuth limits, because shielding performance and machinability both fall away with the wrong residual elements.
Metallurgical laboratories, universities and pilot facilities. Bench and pilot-scale kettle and cell configurations used to establish stage cut-offs and reagent consumptions on a new feed before a production line is committed, including small-capacity electrolytic cells for anode slime characterisation.

Applicable Raw Materials

Crude lead bullion from a smelting furnace. The primary feed. Blast furnace, bottom-blowing and rotary furnace bullion running 95% to 99% Pb with copper, nickel, arsenic, antimony, tin, silver, zinc and bismuth in solution, tapped and cast into bars or delivered molten. This is the feed the kettle sequence is designed around. Output: Refined lead ingots at PB970R through Pb99.994, plus the full set of dross and crust streams.
Hard lead and semi-refined lead from fire preliminary refining. Bullion that has already been through a de-coppering or partial softening pass, either inside the same plant or bought in. Semi-refined feed shortens the kettle train, removes one or two stages from the flowsheet, and is the normal feed to an electrolytic section because pre-refining is a prerequisite for anode casting. Output: Anode plates for the electrolytic circuit, or refined lead where the residual bismuth allows.
Copper-nickel dross and copper matte from upstream smelting. Dross that still carries entrained lead, recovered by liquation and returned to the kettle train rather than sold as a low-value residue. Output: Recovered lead returned to the circuit, and a copper concentrate upgraded by the removal of entrained lead.
Antimonial and arsenical litharge slag from softening. The oxide slag tapped from the softening stage, carrying about 4% to 8% antimony and 1% to 4% arsenic. Processed separately to produce high-antimony-arsenic bullion, which is used as feedstock for antimonial grid and parts alloys. Output: Antimonial bullion, and lead recovered from the slag by reduction.
Silver-zinc crust from the desilverizing stage. The Parkes crust, running about 20% silver with gold values present. Either retorted locally for zinc recovery or shipped as a concentrate to a precious-metal refinery. Output: Retorted bullion at 2,000 to 2,500 oz of silver per ton, silver and gold in a precious-metal refinery, and distilled zinc returned to the desilverizing stage.
Bismuth-rich dross from debismuthizing. The calcium-magnesium bismuthide crust, centrifuged to separate entrained lead metal from the bismuthide. Output: A bismuth concentrate for bismuth recovery, and lead metal returned to the refined lead stream.
Zinc dross and vacuum condensate from dezincing. Zinc recovered by vacuum distillation, over 90% of it returned to the desilverizing stage, with the remainder captured by the final caustic treatment. Output: Reusable zinc, and refined lead taken below 1 ppm zinc.
Recycled lead scrap and battery-derived metallic fractions. Battery grids, straps, terminals, lead cable sheathing, lead sheet and pipe, printing metal, solder dross and machine-shop turnings. Clean and alloy-rich, which makes them suitable for direct kettle charging and for alloy production without going through the full impurity sequence. Output: Refined lead, or Pb-Ca, Pb-Sn and Pb-Sb alloys produced directly.
Lead paste and desulfurized battery paste. The active-material fraction from battery breaking and separation. Desulfurization with sodium carbonate or calcium hydroxide converts lead sulfate to lead oxide and sodium sulfate before the material enters the reduction furnace, so the paste reaches the refinery as a low-sulfur feed rather than as a sulfur problem. Output: Lead oxide feed for reduction smelting, and a sodium sulfate by-product.
Lead-bearing residues, slags, flue dusts and filter cakes. Smelter flue dust, baghouse catch, effluent treatment sludge, tank house residue and refractory rubble that carry recoverable lead. Treated as a secondary feed where capacity allows, which raises overall plant recovery and reduces the volume going to stabilisation. Output: Recovered lead, and a stabilised residue volume reduced at source.
Anode slime from the electrolytic circuit. Insoluble residue from anode dissolution, carrying bismuth, silver, gold, copper, tin and arsenic. Never discarded: it is the single richest stream the refinery produces and the reason electrolytic refining pays where bismuth and precious metals are present. Output: A slime concentrate for hydrometallurgical or pyrometallurgical treatment.
Lead-rich solutions, wash water and scrubber bleed. Tank house electrolyte bleed, crust washing water, mould wash, and alkaline scrubber liquor from the fume treatment train. Recovered by precipitation, ion exchange or electrowinning so that lead leaves the plant in the ingot stack rather than in the effluent. Output: Recovered lead and a discharge that meets the local lead-in-effluent limit.

Note: the exact feed mix, and therefore the stage cut-offs and reagent consumptions, is fixed only after assay. Blends are engineered to the bottleneck element rather than to the average composition.

Finished Products

Refined lead ingots at PB970R grade. Lead of 99.970% indicative content under BS EN 12659:1999, with bismuth capped at 0.030%, silver at 0.0050% and copper at 0.0030%. The grade for general industrial lead, ballast, weights, sheathing and lower-specification casting work where the tightest battery limits are not required. Output: Ingots of 25 kg or 45 kg, stamped and palletised.
Refined lead ingots at PB985R and GB/T 469 Pb99.985 grade. 99.985% indicative content with bismuth capped at 0.015%, silver at 0.0025%, copper at 0.0010%, nickel at 0.0005% and cadmium at 0.0002%. This is the grade most secondary refiners actually certify against, and it is registered for exchange delivery, which is what makes it a tradeable product rather than a specification sheet. Output: Ingots of 25 kg or 45 kg with certificate of analysis.
Refined lead ingots at PB990R and GB/T 469 Pb99.990 grade. 99.990% indicative content with bismuth capped at 0.010%, silver at 0.0015%, copper at 0.0005% and nickel at 0.0002%. The practical ceiling of a full kettle sequence, and the grade required where low silver and low bismuth both matter. ASTM B29-19 defines the equivalent grade as Extra Refined Pure Lead, UNS L50008. Output: Ingots with certificate of analysis and retained sample.
Electrolytic refined lead at GB/T 469 Pb99.994 grade. 99.994% minimum with bismuth capped at 0.004%, silver at 0.0008%, copper at 0.0010% and iron at 0.0005%. The highest grade in commercial circulation as a bulk traded metal, and the grade that electrolytic refining reaches in one operation rather than by pushing every kettle stage to its limit. Output: Cathode lead, then fire-refined and cast ingots, with certificate of analysis and retained sample.
Battery-grade refined lead for active material. Soft lead with the trace elements that cause gassing held down deliberately rather than incidentally: nickel, tellurium and selenium are the three that matter most, with tellurium and selenium roughly two orders of magnitude more damaging per part per million than antimony or tin. Cadmium, manganese, cobalt and chromium are held at or below the limits in ASTM B29-19 and GB/T 469-2013. Output: Ingots or oxide feed for battery active-material production.
Pure lead for radiation shielding and corrosion service. ASTM B29-19 Refined Pure Lead, UNS L50021, and the low-bismuth low-silver grade UNS L50006, where the specification is driven by shielding performance, forming behaviour and corrosion resistance rather than by battery electrochemistry. Output: Blocks, hogs and pigs, including blocks up to about 1,150 kg for shielding fabrication.
Chemical-copper lead. ASTM B29-19 Chemical-Copper Lead, UNS L51121, where copper is deliberately held in a controlled band of 0.040% to 0.080% for corrosion-protection and formability applications. Certified by controlled copper addition rather than by copper removal, which is why the kettle must be able to stop the de-coppering sequence at a set point. Output: Ingots certified to a copper band rather than to a maximum.
Lead-calcium, lead-tin and lead-antimony alloys. Pb-Ca and Pb-Ca-Sn grid alloys for maintenance-free and valve-regulated batteries, Pb-Sn alloys for solders and stationary battery plates, and Pb-Sb alloys for conventional grid and parts castings. All alloyed in the same kettle as the final polish, in weighed additions against an in-process assay. Output: Alloy ingots to a customer-specified composition band.
Antimonial bullion and antimonial lead alloys. High-antimony product from the softening slag and the antimony dross furnace, diluted with refined lead to the required antimony figure for grid and parts alloys. Output: Alloy ingots at a specified antimony content.
Silver-zinc crust as a saleable concentrate. The Parkes crust, running about 20% silver with gold values. Sold as an intermediate or transferred internally to a precious-metal refinery. Output: A silver concentrate, plus distilled zinc returned to the process.
Bismuth concentrate. The centrifuged bismuthide crust from the debismuthizing stage, shipped to a bismuth refiner or treated internally. Output: A bismuth concentrate at a grade set by the crusting practice.
Certified analytical documentation. Every lot is traceable to a retained sample and a certified analysis, which is what allows the ingot to be sold against a named standard instead of against an unverifiable purity claim. Output: Certificate of analysis, retained sample, and a lot record tied to the casting run.

Lead Refining Machine Process Flow

Lead refining machine process flow — nine stages from crude lead bullion to certified refined lead ingots, with the copper-nickel dross, antimonial litharge, silver-zinc crust, bismuth crust and anode slime leaving the line as separate payable streams.

Steps 1 — Feed Assay and Refining Route Selection. Representative sampling of the incoming bullion or residue, with split samples analysed for lead, copper, nickel, arsenic, antimony, tin, silver, gold, zinc, bismuth, tellurium and selenium. The route decision is made here and nowhere else: fire refining where bismuth and precious-metal values are low enough for the full kettle sequence to reach the target grade economically, and an anode casting plus electrolytic section where they are not. The output is a route sheet that fixes the kettle duty allocation, the stage cut-offs, the reagent list and the grade the plant is committing to. Output: Route sheet and mass balance for the committed grade.

Steps 2 — Kettle Charging and Controlled Melt. Bullion bars are charged to the working kettle, or molten bullion is transferred by launder or lead pump, to about 80% of working volume to leave room for agitation and skimming. Melt-down runs at the low end of the working band, normally 400 °C to 500 °C, because lead fume generation rises steeply with bath temperature and there is no metallurgical reason to melt hotter than the next stage requires. Charging is through a sealed port under negative pressure so the fume train captures the dust the charge releases. Output: Molten bullion at the low end of the working band, ready for de-coppering.

Steps 3 — Copper and Nickel Sulfur Drossing. Copper is rejected from solution by cooling the bullion from about 700 °C down toward 330 °C, which drops copper out as copper sulfide crystals that rise and are liquefied into copper matte or collected as powdery dross. The bullion is then held at about 330 °C and elemental sulfur is stirred in for roughly one hour, forming a Cu2S-rich black dross that is skimmed and reducing copper to about 0.005%. Where nickel is present it is removed in the same operation by adding iron pyrite, or a mixture of iron pyrite and sulfur, which forms chalcopyrite, bornite and analogous ternary nickel sulfides. A subsequent zinc or aluminium treatment takes nickel down to trace level, which matters because nickel is one of the three most damaging residual elements in battery lead. Output: Copper-nickel dross to the copper circuit, and decopperized lead.

Steps 4 — Softening by Oxidative Drossing. Arsenic, antimony, tin and the remaining oxidisable elements are removed by injecting oxygen or oxygen-enriched air into the kettle held at about 600 °C. The oxides form a litharge-rich slag that is tapped or skimmed continuously, carrying roughly 4% to 8% antimony and 1% to 4% arsenic depending on how the stage is run. Oxygen sparging takes tin and antimony down to the low parts-per-million range; the floor is set by the lead loss that accompanies it, because lead oxidises alongside the impurities and the two compete for the same oxygen. Where antimony is already low, the same removal is achieved with fused sodium hydroxide and a controlled sodium nitrate addition, whose selectivity is set by how fast the nitrate is fed. Output: Antimonial litharge slag to its own recovery furnace, and softened lead.

Steps 5 — Parkes Desilverizing and Crust Skimming. The softened bullion is cooled to reduce dissolved oxygen, then reheated to about 650 °C and dosed with zinc until the lead is saturated. On cooling toward the 327.5 °C freezing point of lead, silver and gold are ejected with the zinc as a crust that floats and is pressed off, taking the silver in the bullion down to the 2 to 8 ppm range. Crusts low in silver are recirculated to raise the silver content of the final crust, which leaves the stage at roughly 20% silver with the gold values together with it. Two zincings are the normal practice, the first pressed off mechanically and the second skimmed. This is the stage that decides whether a lead refinery is a lead plant or a precious-metal plant with a lead leg. Output: Silver-zinc crust to the precious-metal refinery.

Steps 6 — Vacuum Dezincing and Caustic Cleaning. The desilverized bullion still carries zinc, and zinc is removed by vacuum distillation rather than by oxidation because the vapour pressure difference between zinc and lead is large enough to exploit cleanly. The bullion is held at about 600 °C under vacuum, zinc distils off and deposits as a solid crystalline product on a water-cooled condenser, and over 90% of it is recovered and reused in the desilverizing stage. The residue left in the lead is about 0.05%, and the last traces are taken below 1 ppm by stirring molten caustic soda into the bath. Output: Zinc condensate returned to desilverizing, and dezinced lead.

Steps 7 — Debismuthizing with Calcium and Magnesium. Bismuth is removed by the same crusting principle as silver, with calcium and magnesium metal replacing zinc as the additive, and the kettle is cooled to about 350 °C so a calcium-magnesium bismuthide crust forms and floats. The crust is removed and centrifuged to separate entrained lead metal from the bismuthide, which is recovered for its bismuth content, and the treated lead is taken below 0.005% bismuth. This is the stage that sets the practical ceiling of the fire-refining route: it can take bismuth to a low level, but reaching the 0.004% bismuth cap of the 99.994% class by crusting alone leaves very little margin, which is why the electrolytic route is preferred when that grade is the commercial target. Output: Bismuth-rich dross to bismuth recovery, and low-bismuth lead.

Steps 8 — Anode Casting and Electrolytic Refining. For the electrolytic route, the pre-refined lead is cast into anodes and loaded into cells holding a lead fluosilicate bath with free fluosilicic acid, or a lead methanesulfonate bath where fluoride handling is not acceptable. The circuit runs at 35 °C to 45 °C with a cathode current density of 200 A/m² to 240 A/m² and a cell voltage of about 0.4 V to 0.6 V, with lignin sulfonate or a similar levelling additive controlling deposit morphology. Lead dissolves anodically and deposits on stainless steel, titanium or lead starter sheets, while bismuth, silver, gold, copper, tin and arsenic stay behind in the anode slime. Cathode lead is stripped, washed, and taken to a finishing kettle for fire refining and alloying before ingot casting. Output: Anode slime to the precious-metal and bismuth circuit, and cathode lead of the 99.994% class.

Steps 9 — Cathode Melting, Ingot Casting and Assay. Refined lead, whether it comes off the kettle train directly or from the electrolytic circuit, is polished a final time and then cast. The linear casting machine is brought up in sequence: chain conveyor, circulating cooling water, ingot stamping and marking, and the ingot conveyor and palletiser. Molten lead is tapped into the moulds, cooled, stamped with the lot and brand identification required by the standard, weighed and stacked. Mould temperature is held above the 327.5 °C freezing point but below the level at which excessive drossing begins, and the casting temperature is capped to control both dross loss and surface quality. Samples are taken from the casting run or from the final product and analysed, and the lot is released against the named grade with a certificate of analysis and a retained sample. Output: Certified refined lead ingots, and a lot record tied to the analytical result.

Product Structure (Main Equipment)

Refining kettles. The core vessels of the fire-refining route. Fabricated in boiler steel plate with wall thickness engineered in the 32 mm to 46 mm band for continuous service at 400 °C to 650 °C, with reinforced charging lips, skimming doors, a tapping spout and lifting lugs. Kettle working capacity and the number of kettles follow the bullion assay and the daily throughput: the standard industrial arrangement is one kettle per duty, with combined-duty vessels used where throughput is lower and a single crane serves the whole train.
Kettle setting, combustion system and flue. Refractory-lined setting with burner ports, natural gas or LPG burners and combustion air fans, and a flue connection into the main exhaust duct. Where local emission rules restrict combustion, electrical resistance or induction heating is substituted so the kettles carry no combustion products at all. Burner modulation is closed-loop against an immersion thermocouple, because the cooling programme in the de-silverizing and debismuthizing stages depends on controlling the cooling rate rather than only the peak temperature.
Agitation system. Variable-speed mechanical stirrer or rope-driven stirrer on a lifting frame, sized for the reagent dispersion each stage needs. Copper and nickel drossing, softening, desilverizing, debismuthizing and the final caustic clean all depend on bringing a reagent into contact with the whole bath; inadequate agitation is the most common cause of a kettle that underperforms its design grade.
Charging and material handling. Charging crane or monorail hoist, charging bucket, bullion bar racks, molten metal launder and ladles, and lead pumps for transferring molten bullion between kettles. Pumping rather than ladling is the single biggest time saving in a kettle train and also reduces operator exposure at the skimming floor.
Skimming and dross handling. Skimming tools and doors sized for the crust volumes each stage produces, dross pans and moulds, a liquation furnace for recovering entrained lead from copper dross, an antimony dross furnace for the softening slag, and a retort or distillation furnace for the silver-zinc crust. Each dross stream is handled in equipment matched to its own chemistry rather than being combined into a single residue.
Desilverizing accessories. Zinc dosing and melting equipment, crust press or filter press, crust centrifuge, and crust recirculation handling. The press and the centrifuge are what turn the crust from a wet lead-bearing residue into a saleable silver concentrate, so they are specified as metallurgical equipment rather than as handling equipment.
Vacuum dezincing unit. Vacuum pump set, sealed kettle lid, water-cooled condenser, zinc collection chamber and zinc transfer handling. The condenser surface area and the vacuum level are set by the zinc content of the bullion entering the stage, not by kettle size.
Anode casting and electrolytic tank house. Anode casting machine and moulds, anode lugs and hanger bars, electrolytic cells in PVC-lined steel or FRP-lined concrete, cathode starter sheet preparation, cell busbars, electrode handling crane, cathode stripping machine, and the circulation and filtration circuit for the fluosilicate or methanesulfonate electrolyte.
Rectifier and electrical system. Thyristor or IGBT rectifier with a selectable current programme, busbar and switchgear, cell voltage and current monitoring per cell, and interlock logic covering over-voltage, over-current, busbar over-temperature, electrolyte over-temperature, circulation failure, low level and exhaust fan failure. Instrumentation is routed to a PLC with touchscreen HMI, batch recipe management, alarm history and production data logging.
Electrolyte purification and slime handling. Electrolyte bleed treatment for copper, antimony and bismuth accumulation, filter presses or belt filters for slime collection, slime drying, and slime transfer into the hydrometallurgical or pyrometallurgical recovery circuit.
Fume capture and gas treatment. Hooded kettles, sealed charging ports, furnace and casting hoods, negative-pressure ducting, cyclone and baghouse dust collection, alkaline wet scrubber for sulfur dioxide and acid gases, and an optional wet electrostatic precipitator with a regenerative thermal oxidiser for plants facing the tightest particulate metal limits. Captured lead dust is returned to the smelting circuit rather than disposed of.
Effluent treatment. Chemical precipitation with lime and sulfide, flocculation and clarification, membrane polishing, and a recirculation loop that returns treated water to the casting cooling circuit, with a monitored discharge point for the balance.
Ingot casting line and finishing. Linear casting machine with chain conveyor, moulds in 25 kg and 45 kg configurations, circulating cooling water system with pumps and heat rejection, ingot stamping and marking machine, ingot conveyor, palletiser or stacking system, weighing station and finished-goods handling.
Alloying system. Weighed dosing equipment for calcium, tin and antimony, with in-kettle assay sampling between additions, used to produce Pb-Ca, Pb-Ca-Sn, Pb-Sn and Pb-Sb grades in the same vessel as the final polish.
Control and assay equipment. PLC and HMI, thermocouple immersion probes, sampling tools for bath and cast product, and the plant analytical routine, which relies on spectrographic or wet chemical methods agreed with the purchaser and applied to a sample taken from the lot during casting or from the final solidified product.

Product Features

Route selection built into the machine rather than assumed. The line is engineered to the route your bullion actually needs. A fire-refining configuration stops at the kettle train and linear caster. An integrated configuration adds anode casting and the electrolytic tank house, and shares the same furnace, fume, effluent and casting systems. You buy the route the assay justifies, and the flowsheet shows exactly which stages are present and which are not.
A controlled cooling programme, not just a temperature set-point. The desilverizing and debismuthizing stages work only if the bath is cooled at a controlled rate into a narrow window — the silver-zinc crust separates just above the 327.5 °C freezing point of lead, and the calcium-magnesium bismuthide crust at about 350 °C. Burner modulation is closed-loop against an immersion thermocouple with a selectable cooling ramp, and the control system records the ramp for each batch.
Agitation sized to each reagent, not to the vessel. Stirrer speed and impeller geometry are selected for the dispersion each stage needs, from the high-shear mixing that iron pyrite and sulfur require to the gentle circulation used during vacuum dezincing. Inadequate agitation is the most frequent reason a kettle line misses its design grade, and it is a design decision rather than an operating adjustment.
Every by-product stream leaves in a form its own process can accept. Copper-nickel dross goes to a liquation furnace and then to the copper circuit; antimonial litharge goes to an antimony dross furnace; the silver-zinc crust is pressed, centrifuged and shipped or retorted; the bismuth crust is centrifuged; anode slime is filtered, dried and transferred. Nothing is combined into an unsaleable mixed residue.
Grade-driven commissioning. The machine is not commissioned to a purity figure. It is commissioned to a named grade in BS EN 12659:1999, GB/T 469-2013 or ASTM B29-19, and the acceptance test is the analytical result on a cast lot against that grade’s elemental limits. If the target is PB985R, the acceptance criterion is bismuth at or below 0.015%, silver at or below 0.0025%, copper at or below 0.0010% and nickel at or below 0.0005%.
Batch metallurgy with a continuous packaging tail. Kettle refining stays batch so the plant can absorb variable bullion quality, while the casting line runs continuously: chain conveyor, circulating cooling water, stamping and marking, ingot conveyor and palletiser. The result is that a variable feed does not become a variable shipment.
Alloy production in the same vessel. Calcium, tin and antimony dosing is built into the final kettle, with in-kettle sampling between additions, so Pb-Ca, Pb-Ca-Sn, Pb-Sn and Pb-Sb grades are produced on the same campaign as soft refined lead without a second investment.
Fume control engineered to the regulated elements, not to a dust figure. The treatment train is sized for particulate lead, arsenic, cadmium and nickel, which are the elements regulated at the stack, and it includes alkaline scrubbing for sulfur dioxide and acid gases from the desulfurization and caustic stages. Captured dust is returned to smelting.
Trace-element control aimed at the three elements that actually matter. Nickel, tellurium and selenium cause battery gassing at levels orders of magnitude below the antimony and tin limits, and the flowsheet therefore specifies dedicated removal steps for all three: pyrite and sulfur with a zinc or aluminium finishing treatment for nickel, and sodium addition forming intermetallics for tellurium and selenium.
Counter-intuitive control where it is economically right. Bismuth and zinc are deliberately not stripped to zero in secondary lead intended for battery active material, because both suppress gassing and removing them from the recycled stream is counterproductive. The control philosophy distinguishes between elements that must be removed and elements that must only be held below a band.
Effluent and slime circuits designed as production units. Tank house bleed, crust wash water, mould wash and scrubber liquor are recovered by precipitation, ion exchange or electrowinning, and the slime circuit is a producing unit that delivers a bismuth and precious-metal concentrate. Waste treatment is where a lead refinery either protects its margin or gives it away.
Full instrumentation and batch traceability. PLC with touchscreen HMI, batch recipe management, alarm history and production data logging, plus a sampling and retention routine that ties every ingot lot to the analytical result and the retained sample that supports its certificate of analysis.

Technical Parameters And Specifications

1. Kettle Refining Line

Parameter	Specification
Capacity	Engineered to your crude lead assay, target grade, daily throughput and site conditions; no fixed catalogue sizes are quoted
Kettle shell material	Boiler steel plate, engineered wall thickness in the 32 mm to 46 mm band for continuous 400 °C to 650 °C service
Kettle working capacity	Engineered to your crude lead assay, target grade and daily throughput; batch sizes are set by the casting rhythm and by the crane and charging system, not by a fixed catalogue list
Kettle count and duty split	One kettle per refining duty as standard, or combined-duty vessels with a shared charging crane where throughput and batch timing allow
Heating system	Natural gas or LPG burners with combustion air fans, or electrical resistance or induction heating where local rules restrict combustion emissions
Working temperature band	400 °C to 650 °C across the train, with stage-specific windows of about 330 °C for sulfur drossing, about 600 °C for softening, about 650 °C for desilverizing, about 600 °C for vacuum dezincing, about 350 °C for debismuthizing and about 500 °C for the final caustic clean
Cooling control	Closed-loop burner modulation against an immersion thermocouple with a selectable cooling ramp for the desilverizing and debismuthizing windows
Copper-nickel drossing reagent	Elemental sulfur, or iron pyrite, or a mixture of iron pyrite and sulfur, stirred at about 330 °C for approximately 1 h
Softening reagent	Oxygen or oxygen-enriched air injected at about 600 °C; fused sodium hydroxide with controlled sodium nitrate addition where antimony is low
Desilverizing reagent	Zinc added at about 650 °C to saturation, with press and centrifuge handling for the crust
Dezincing method	Vacuum distillation at about 600 °C with a water-cooled condenser, followed by molten caustic soda treatment
Debismuthizing reagent	Calcium and magnesium metal added with cooling to about 350 °C, with crust centrifugation
Final polish	Sodium hydroxide stirred at about 500 °C for approximately 1 h with interval sampling
Agitation	Variable-speed mechanical or rope-driven stirrer on a lifting frame, with impeller geometry matched to each reagent
Dross handling	Skimming doors, dross pans and moulds, liquation furnace for copper dross, antimony dross furnace for softening slag, crust press and centrifuge
Molten metal transfer	Lead pump or launder between kettles, with charging crane or monorail hoist for bullion bars
Charge preparation	Bars cast to a size the charging system accepts; molten bullion transferred directly where the smelter is adjacent
Fume capture	Hooded kettles, sealed charging ports, negative-pressure ducting, cyclone and baghouse dust collection, alkaline wet scrubber
Optional gas polishing	Wet electrostatic precipitator with a regenerative thermal oxidiser where the local particulate metal limit requires it
Ingot casting	Linear casting machine with chain conveyor, circulating cooling water, ingot stamping and marking, ingot conveyor and palletiser
Ingot weight	25 kg and 45 kg standard moulds, other weights on request
Ingot form	Pigs up to about 50 kg, or blocks and hogs up to about 1,150 kg for shielding and other large-section applications
Alloying	Weighed calcium, tin and antimony dosing in the final kettle, with in-kettle assay sampling between additions
Instrumentation	PLC with touchscreen HMI, batch recipe management, alarm history and production data logging
Utilities	Cooling water, compressed air, inert gas for bath blanketing where required, and electrical supply; all sizes engineered to the process configuration rather than quoted as fixed figures

2. Electrolytic Refining Circuit

Parameter	Specification
Feed requirement	Pre-refined bullion with copper and tin reduced before anode casting; residual copper and tin contaminate the cathode and load the electrolyte
Electrolyte system	Lead fluosilicate and free fluosilicic acid as the standard industrial bath, or lead methanesulfonate where fluoride handling is not acceptable. Lead sulfate baths are not used
Electrolyte temperature	35 °C to 45 °C
Cathode current density	200 A/m² to 240 A/m² standard, with higher densities available where additive and flow control allow
Cell voltage	About 0.4 V to 0.6 V per cell, derived from the specific energy band and current efficiency rather than quoted as an independent specification
Specific energy	About 120 kWh to 150 kWh per tonne of refined lead
Electrochemical equivalent	3.866 g of lead per ampere-hour, for the Pb2+ reaction with two electrons transferred per atom
Current efficiency	93% to 97% typical, the balance lost to stray current, short circuits and secondary reactions
Rectifier	Thyristor or IGBT rectifier with a selectable current programme and ramp control
Additives	Lignin sulfonate or an equivalent levelling agent for smooth, dense, non-dendritic deposits
Anode casting	Anodes cast from pre-refined lead with lugs and hanger bars sized to the busbar current
Cathode starter sheets	Stainless steel or titanium blanks, or electrodeposited lead starter sheets
Cell construction	PVC-lined steel or FRP-lined concrete, with corrosion-resistant busbars and electrode handling crane
Electrode spacing	Engineered to the selected current density, cathode size and electrolyte circulation rate
Cathode product	Lead of the 99.994% class, stripped by automatic or semi-automatic stripping machine, washed and routed to the finishing kettle
Anode slime	Collected on filter presses or belt filters, dried and transferred; carries bismuth, silver, gold, copper, tin and arsenic
Electrolyte purification	Continuous or batch bleed treatment for copper, antimony and bismuth accumulation, with recovered metal returned to the front of the process
Post-electrolysis finishing	Cathode fire refining, alloying where required, and ingot casting before dispatch
Effluent treatment	Chemical precipitation with lime and sulfide, flocculation, clarification, membrane polishing and recirculation toward zero liquid discharge
Interlocks and alarms	Over-voltage, over-current, busbar over-temperature, electrolyte over-temperature, circulation failure, low level and exhaust fan failure
Product grade	GB/T 469-2013 Pb99.994 class as the commercial target, with higher purity achievable on a controlled anode feed

3. Refined Lead Grade Limits — BS EN 12659:1999

Grades registered for London Metal Exchange delivery. Indicative lead content is 100 minus the total of impurities, and all impurity figures are maximum values in percent by weight.

Element	PB970R	PB985R	PB990R
Indicative lead content	99.970	99.985	99.990
Silver (Ag)	0.0050	0.0025	0.0015
Arsenic (As)	0.0010	0.0005	0.0005
Bismuth (Bi)	0.030	0.0150	0.0100
Cadmium (Cd)	0.0010	0.0002	0.0002
Copper (Cu)	0.0030	0.0010	0.0005
Nickel (Ni)	0.0010	0.0005	0.0002
Antimony (Sb)	0.0010	0.0005	0.0005
Tin (Sn)	0.0010	0.0005	0.0005
Zinc (Zn)	0.0005	0.0002	0.0002
Total impurities	0.030	0.015	0.010

4. Refined Lead Grade Limits — GB/T 469-2013

Chinese national standard for lead ingots. Lead content is a minimum and all impurity figures are maximum values in percent by weight.

Element	Pb99.970	Pb99.985	Pb99.990	Pb99.994
Lead (Pb), minimum	99.970	99.985	99.990	99.994
Silver (Ag)	0.0050	0.0025	0.0015	0.0008
Arsenic (As)	0.0010	0.0005	0.0005	0.0005
Bismuth (Bi)	0.030	0.015	0.010	0.004
Cadmium (Cd)	0.0010	0.0002	0.0002	0.0002
Copper (Cu)	0.003	0.001	0.001	0.001
Iron (Fe)	0.0020	0.0010	0.0010	0.0005
Nickel (Ni)	0.0010	0.0005	0.0002	0.0002
Antimony (Sb)	0.0010	0.0008	0.0008	0.0007
Tin (Sn)	0.0010	0.0005	0.0005	0.0005
Zinc (Zn)	0.0005	0.0004	0.0004	0.0004
Total impurities	0.030	0.015	0.010	0.006

5. Refined Lead Grade Limits — ASTM B29-19

Refined lead in pig, block or hog form. Lead content is a minimum determined by difference and all impurity figures are maximum values in percent by weight. A dash indicates that no limit is specified for that element in that grade.

Element	Low Bismuth Low Silver L50006	Extra Refined L50008	Refined Pure L50021	Pure Lead L50049	Chemical-Copper L51121
Lead (Pb), minimum by difference	99.995	99.990	99.97	99.94	99.90
Antimony (Sb)	0.0005	0.0005	0.0005	0.001	0.001
Arsenic (As)	0.0005	0.0005	0.0005	0.001	0.001
Tin (Sn)	0.0005	0.0005	0.0005	0.001	0.001
Antimony, arsenic and tin combined	—	—	—	0.002	0.002
Copper (Cu)	0.0010	0.0005	0.0010	0.0015	0.040 to 0.080
Silver (Ag)	0.0010	0.0015	0.0075	0.010	0.020
Bismuth (Bi)	0.0015	0.0075	0.025	0.05	0.025
Zinc (Zn)	0.0005	0.0002	0.001	0.001	0.001
Tellurium (Te)	0.0001	0.0001	0.0002	—	—
Nickel (Ni)	0.0002	0.0002	0.0002	0.0005	0.002
Iron (Fe)	0.0002	0.0005	0.001	0.001	0.002
Selenium (Se)	—	0.0005	0.0005	0.001	0.001
Sulphur (S)	—	0.0005	0.001	0.002	0.001
Aluminium (Al)	—	0.0005	0.0005	0.0005	0.0005
Cadmium (Cd)	—	0.0002	0.0005	0.0005	0.0003

6. Process Control Set-Points and Analytical Checks

Control point	Set-point or limit	Method
Incoming bullion assay	Full elemental scan including copper, nickel, arsenic, antimony, tin, silver, gold, zinc, bismuth, tellurium and selenium	Spectrographic or wet chemical analysis on a split sample
Bath temperature, drossing stages	About 330 °C at sulfur addition, having cooled from about 700 °C	Immersion thermocouple with recorded cooling ramp
Copper after drossing	Target at or below about 0.005%	Bath sample between stages
Nickel after pyrite and sulfur treatment	Target at or below about 0.005%, taken to trace by zinc or aluminium addition	Bath sample between stages
Bath temperature, softening	About 600 °C with oxygen or oxygen-enriched air injection	Immersion thermocouple
Antimony, arsenic and tin after softening	Tin and antimony taken to the low parts-per-million range, subject to acceptable lead loss	Bath sample
Litharge slag composition	About 4% to 8% antimony and 1% to 4% arsenic, depending on stage efficiency	Slag assay
Bath temperature, desilverizing	Zinc added at about 650 °C, then cooled toward the 327.5 °C freezing point of lead	Immersion thermocouple with controlled cooling
Silver after desilverizing	About 2 ppm to 8 ppm in the bullion	Bath sample
Silver-zinc crust composition	About 20% silver with the gold values reporting with it	Crust assay
Bath temperature, vacuum dezincing	About 600 °C under vacuum with a water-cooled condenser	Vacuum gauge and immersion thermocouple
Zinc after dezincing and caustic clean	About 0.05% after distillation, taken below 1 ppm by caustic treatment	Bath sample
Bath temperature, debismuthizing	About 350 °C after calcium and magnesium addition	Immersion thermocouple
Bismuth after debismuthizing	Taken below about 0.005%	Bath sample
Bath temperature, final caustic clean	About 500 °C with sodium hydroxide stirred for about 1 h	Immersion thermocouple and interval sampling
Electrolyte temperature and composition	35 °C to 45 °C, with free acid and metal tenor held inside a control band	Titration and density check
Cathode current density	200 A/m² to 240 A/m²	Rectifier current against measured cathode area
Cell voltage	About 0.4 V to 0.6 V per cell, monitored individually for fault isolation	Per-cell voltage monitoring
Cast product certification	Analytical result against the named grade limits, with a retained sample	Spectrographic or wet chemical analysis on a casting sample
Stack particulate metals	Local regulated limit for lead, arsenic, cadmium and nickel	Periodic stack testing and continuous monitoring where required
Effluent lead	Local regulated lead-in-effluent limit	Monitored discharge point

Technical Advantages

The route is chosen against measured chemistry, and the reasoning is visible. Most suppliers quote a purity number before they have seen your bullion. The design here starts from the assay and states which route reaches which named standard grade, which is the only basis on which a refinery can be priced and financed. That is why a bullion carrying 0.5% bismuth is quoted an integrated kettle-plus-electrolytic line while a low-bismuth battery-scrap bullion is quoted a kettle train, and the difference is explained in the flowsheet rather than discovered at commissioning.
The thermal basis of the process is engineered, not assumed. Every kettle stage is a solubility window. Copper drops on cooling from about 700 °C to 330 °C. The silver-zinc crust only separates in the narrow band just above the 327.5 °C freezing point of lead. The calcium-magnesium bismuthide crust forms at about 350 °C. Zinc is separated by vapour pressure at about 600 °C. Designing the cooling programme, the agitation and the skimming access around those windows is what converts a kettle from a melting pot into a refinery.
Grade ceilings stated honestly, with the standard they come from. Fire refining commercially reaches the 99.985% and 99.990% classes — BS EN 12659 PB985R and PB990R, GB/T 469 Pb99.985 and Pb99.990. Electrolytic refining is the lower-risk route to the 99.994% class of GB/T 469 with bismuth at or below 0.004%. Stating the ceiling and its source is more useful to a buyer than a number without a standard behind it.
Electrochemical and energy self-checks that reconcile against published practice. The electrochemical equivalent of lead is 3.866 g per ampere-hour for the Pb2+ reaction. At 95% current efficiency that is about 272,000 ampere-hours per tonne of refined lead, and at 0.5 V cell voltage it is about 136 kWh per tonne — inside the 120 kWh to 150 kWh per tonne band reported for lead electrorefining. A quoted plant can therefore be checked against first principles rather than accepted on trust.

Electrochemical equivalent: 207.2 g/mol / (2 x 26.801 A·h/mol) = 3.866 g/A·h Rectifier yield: 3.866 g/A·h x 24 h x 1,000 A = 92.8 kg/day per kA at 100% current efficiency Specific energy: 1,000,000 g/t / 3.866 g/A·h / 0.95 = 272,000 A·h/t; x 0.5 V = 136 kWh/t Published band for lead electrorefining: 120-150 kWh/t. The two agree, so the cell voltage and current density assumed here are consistent with industrial practice.

Three standards, three markets, one machine. BS EN 12659:1999 covers London Metal Exchange delivery grades, GB/T 469-2013 covers the Chinese national grades, and ASTM B29-19 covers North American pure lead and corrosion-protection grades including the chemical-copper lead grade where copper is held in a controlled 0.040% to 0.080% band. A plant that can certify against all three sells into every market without changing its process, only its stage cut-offs.
Precious-metal recovery designed in, not bolted on. The desilverizing crust at about 20% silver is the entry point of a precious-metal refinery, and the anode slime is the second such stream. Sizing the press, the centrifuge, the slime filtration and the drying circuit as production equipment rather than residue handling is what makes the silver and gold values recoverable at the refinery gate instead of being sold at a discount inside a lead-bearing residue.
The three damaging trace elements get dedicated removal steps. Nickel, tellurium and selenium cause battery gassing at levels orders of magnitude below the antimony and tin limits, so nickel is removed with iron pyrite and sulfur with a zinc or aluminium finishing step, and tellurium and selenium are removed by sodium addition forming intermetallics. A flowsheet that treats these as minor elements produces lead that fails on the battery line despite meeting an antimony specification.
Control philosophy that knows what not to remove. Bismuth and zinc both suppress gassing in battery active material, so stripping them to zero in recycled lead is counterproductive. The control system distinguishes elements that must be removed from elements that must only be held inside a band, which is the difference between meeting a specification and meeting the customer’s process.
Capacity engineered rather than catalogued. Kettle size, kettle count, anode area, rectifier current and casting rate are all derived from your assay, target grade, batch rhythm and site conditions. There is no standard plant size list to fit your project into, which is why the specification is issued as an engineered configuration with the assumptions stated.
By-product value is quantified before the plant is bought. The copper-nickel dross, the antimonial litharge at about 4% to 8% antimony, the silver-zinc crust at about 20% silver, the bismuth crust and the anode slime each carry a recoverable value and a defined downstream route. Comparing those recoveries against the refining cost is the basis of the investment case, and it is presented with the flowsheet rather than left to be discovered afterwards.
Emissions design matched to the regulated elements. Particulate lead, arsenic, cadmium and nickel are the regulated stack parameters, and the treatment train is sized against them with alkaline scrubbing for sulfur dioxide and acid gases. Where the local limit requires it, a wet electrostatic precipitator with a regenerative thermal oxidiser is specified, and captured lead dust is returned to the smelting circuit rather than disposed of.
Full lifecycle support on one process. Sampling and assay interpretation, flowsheet and equipment design, fabrication, installation and commissioning, operator training, grade certification routine, spare parts, and process support through the operating life of the plant, all from the same metallurgical team that set the stage cut-offs.

Service Process

Inquiry response and requirement capture. Share the target feed material, the grade you need to sell, the intended output volume and your site conditions. A metallurgical engineer responds with a first assessment of the route, the stages required and the streams that will be produced, within one working day of receiving the enquiry.
Free raw material testing and assay interpretation. A representative sample is analysed and the composition is interpreted against the three published grade standards. The output is not just an analysis report: it states which route your feed can support, which grade that route can reach, and how much margin exists against each elemental limit. This is the step that prevents a refinery from being bought for the wrong grade.
Route and flowsheet design. The stage train is fixed against the assay, including which kettle duties are combined and whether an electrolytic section is included. Mass balance, reagent consumption, by-product stream composition and the expected recovery figures are issued with the flowsheet.
Equipment configuration and quotation. Kettle size and count, anode area and rectifier rating, casting rate, fume and effluent treatment scope, instrumentation and spare parts are specified as an engineered configuration, with the assumptions stated so the quotation can be checked line by line.
Engineering drawings and layout. Process flow diagram, equipment general arrangement, foundation and load drawings, piping and instrumentation diagram, electrical single-line diagram and a plant layout that fits your available floor area and access routes. Layout is adjusted to your factory drawings rather than offered as a fixed arrangement.
Manufacturing and inspection. Fabrication of kettles, setting, agitation, cells, busbars, rectifier, casting machine and gas treatment equipment in the YuSai workshops, with material certification, welding inspection and pressure testing records, and a works acceptance test before dispatch.
Site installation and commissioning. Engineers attend site for mechanical and electrical installation supervision, refractory and burner commissioning, cell filling and electrolyte make-up, rectify ramp-up, and the first production batches. Commissioning continues until the plant casts a lot that passes analysis against the named grade.
Grade certification routine established with your operators. The sampling, retention, analysis and certificate of analysis procedure is set up during commissioning and handed over as a written routine, so release against the standard continues after the commissioning team leaves.
Operator and maintenance training. Classroom and hands-on training covering the temperature programme of each kettle stage, reagent addition and stirring, skimming and crust handling, cell operation and fault response, casting line running, fume and effluent plant operation, analytical sampling and emergency procedures.
Spare parts and consumables programme. A wear-part and consumables list issued with the plant, with recommended stock levels for the commissioning year and factory-price supply for the operating life.
Technical upgrade and process improvement support. Flowsheet revision, control programme updates and equipment retrofits as the feed mix or the target grade changes, including the addition of an alloying campaign or the extension of the kettle train as throughput grows.
Long-term process support. Remote diagnosis and on-site attendance for metallurgical problems, recovery shortfalls, grade failures and off-spec batches, using the batch records and retained samples the plant has accumulated.

Warranty And After-Sales Service

Warranty period and scope. Twelve months from completion of commissioning, or eighteen months from dispatch, whichever falls first, covering design, materials and workmanship on equipment supplied by YuSai. Coverage extends to the refining kettles, agitation systems, combustion and heating equipment, electrolytic cells and busbars, rectifier, casting line, gas treatment equipment and control system.
Warranty exclusions stated plainly. Consumable and wear items are excluded: refractory and burner components, stirrer impellers, skimming tools, moulds, filter cloths, anodes consumed in operation, electrolyte chemicals and reagents. Damage from feed outside the agreed assay envelope, from operating outside the commissioned temperature programme, from untrained operation, or from unauthorised modification is also excluded.
Performance commitment on grade, not on a purity figure. The plant is warranted to reach the named grade in the agreed standard on the agreed feed, with the acceptance test being the analytical result on a cast lot and the retained sample supporting it. Where a feed drifts outside the agreed envelope, the warranty obligation is met by a flowsheet revision rather than by a replacement guarantee.
Response times. Technical response within one working day for enquiries, remote diagnosis of control and electrical faults within twenty-four hours, and on-site attendance within seven working days for faults that cannot be resolved remotely. Response times are confirmed in the contract against your site location.
Spare parts availability. Recommended stocked spares for the first operating year are identified at handover and can be supplied as a packaged commissioning kit. Subsequent supply is at factory price, with standard fast-moving parts held in stock and non-standard fabrications quoted with a lead time.
Process support beyond the warranty. Metallurgical support does not stop when the warranty expires. Grade failures, recovery shortfalls and feed changes are supported on the same terms for the operating life of the plant, and the control programme, flowsheet and operating windows are revised when the feed or target grade changes.
Documentation handover. Process flow diagrams, equipment manuals, electrical drawings, instrumentation lists, control programme backups, refractory and lining schedules, commissioning records, analytical procedures, safety data for reagents, and the emergency response plan for molten lead, fume release and electrolyte spill.
Operator refresher training. Refresher training available after the warranty period, including for new operators as your team changes, and covering the temperature programme, cell operation, casting, sampling and fault response.
Upgrade path. Where throughput grows or the feed becomes harder, the plant is extended rather than replaced: additional kettles to split duties, an added electrolytic section, an upgraded rectifier, a larger casting line or an additional gas treatment stage. Upgrade scope is quoted as an engineered extension to the existing plant.
Consultation on operating economics. Support with reagent consumption, energy use, dross and crust yield reconciliation, and recovery accounting, so the plant’s metallurgical balance is measured and managed rather than assumed.

Frequently Asked Questions

What is a lead refining machine?

A lead refining machine is a kettle line, an electrolytic circuit, or both, that removes copper, nickel, arsenic, antimony, tin, silver, zinc and bismuth from crude lead bullion so the output can be certified against a published standard grade such as BS EN 12659 PB985R or GB/T 469 Pb99.994. Fire refining removes each impurity in a controlled temperature window with one reagent per stage; electrolytic refining dissolves pre-refined anodes in a lead fluosilicate bath and concentrates bismuth and the precious metals into anode slime.

What purity can a lead refining machine reach?

Fire refining commercially reaches the 99.985% and 99.990% grades, which are BS EN 12659 PB985R and PB990R and GB/T 469 Pb99.985 and Pb99.990, with bismuth capped at 0.015% and 0.010% respectively. Electrolytic refining reaches the GB/T 469 Pb99.994 class with bismuth at or below 0.004%, and ASTM B29-19 defines grades up to 99.995% for Low Bismuth Low Silver Pure Lead, UNS L50006.

Should I choose fire refining or electrolytic refining?

Choose fire refining when bismuth and precious-metal values in the bullion are low enough for the kettle sequence to reach your target grade economically, which in practice means the 99.970% to 99.990% classes. Choose electrolytic refining when bismuth is high enough that crusting alone leaves no margin below the target cap, when the bullion carries recoverable silver and gold, or when the target is the 99.994% class with bismuth at or below 0.004%. Electrolytic refining moves those elements into anode slime in one operation instead of depending on a narrow crusting window, and it also gives higher metal recovery and a cleaner working environment, at the cost of a larger capital item and a pre-refining step.

What impurities does lead refining remove, and in what order?

The order is fixed by chemistry rather than tradition. Copper and nickel come out first by cooling and by sulfur or iron pyrite drossing, then arsenic, antimony and tin by oxidative softening, then silver and gold by the Parkes zinc treatment, then zinc by vacuum distillation and molten caustic soda, then bismuth by calcium and magnesium addition, and finally a caustic clean that sweeps residual calcium, magnesium, zinc and antimony. Tellurium and selenium, which are the most damaging trace elements in battery lead, are removed by sodium addition forming intermetallics.

What is the operating temperature of lead refining?

Kettle refining runs a temperature cascade rather than a single set-point. Copper and nickel drossing sits at about 330 °C after the bullion has cooled from about 700 °C, softening runs at about 600 °C, desilverizing adds zinc at about 650 °C and then cools toward the 327.5 °C freezing point of lead, vacuum dezincing runs at about 600 °C, debismuthizing at about 350 °C and the final caustic clean at about 500 °C. The electrolytic circuit by contrast runs cold, at 35 °C to 45 °C.

How does the Parkes desilverizing process work?

Zinc is stirred into softened bullion at about 650 °C until the lead is saturated, and the bath is then cooled toward the 327.5 °C freezing point of lead. Because silver and gold are far less soluble in solidifying lead than zinc is, they are ejected together with the zinc as a crust that floats and is pressed off, taking the silver content of the bullion down to about 2 to 8 ppm. The crust leaves the stage at roughly 20% silver with the gold values reporting with it, which is why it is the natural feed to a precious-metal refinery rather than a waste stream.

Why is bismuth the hardest impurity to remove from lead?

Because bismuth is last in the sequence and it has to be taken out of a metal that is already nearly pure. Crusting with calcium and magnesium is effective and takes bismuth below about 0.005%, but the 0.004% cap of the GB/T 469 Pb99.994 grade leaves almost no margin, and every additional crusting pass costs lead yield and reagent. Electrolytic refining sidesteps that limit by rejecting bismuth quantitatively into the anode slime instead of fighting for the last few parts per million in the kettle.

How much does a lead refining machine cost?

Cost is driven by four variables: the bullion assay, which sets how many kettle stages are needed; the target grade, which decides whether an electrolytic tank house is included; the daily throughput, which sets kettle size and count and the casting rate; and the local emission standard, which determines how far the gas treatment train must go. A kettle-only line for a low-bismuth battery-scrap feed is a different order of investment from an integrated kettle and tank house line for high-bismuth bullion, so a quotation is issued against a sampled assay and a committed grade rather than against a catalogue model.

What is the capacity of a lead refining machine?

Capacity is engineered rather than catalogued. Kettle working volume, kettle count, anode area, rectifier current and casting rate are all derived from your assay, target grade, batch rhythm and site conditions, so the plant is sized to your project instead of being selected from a standard list. Mould sizes of 25 kg and 45 kg are standard for ingots and other weights are available, but line throughput itself is a design output supported by the mass balance rather than a figure quoted in advance.

What happens to the drosses and anode slime?

Every by-product leaves the refining machine in a form its own downstream process can accept. Copper-nickel dross is liquated to recover entrained lead and then goes to the copper circuit. Antimonial litharge running about 4% to 8% antimony goes to a dross furnace for antimonial bullion. The silver-zinc crust is pressed or centrifuged and shipped as a concentrate at roughly 20% silver, or retorted locally for zinc recovery. The bismuth crust is centrifuged for bismuth recovery. Anode slime is filtered, dried and transferred to a hydrometallurgical or pyrometallurgical recovery line for bismuth, silver, gold, copper and tin.

Which lead grades can be certified against ASTM B29, BS EN 12659 and GB/T 469?

All of the published grades in the three standards are reachable by choosing the right stage cut-off. BS EN 12659:1999 covers PB970R, PB985R and PB990R, and these are the grades registered for London Metal Exchange delivery. GB/T 469-2013 covers Pb99.970, Pb99.985, Pb99.990 and Pb99.994. ASTM B29-19 covers Low Bismuth Low Silver Pure Lead UNS L50006, Extra Refined Pure Lead UNS L50008, Refined Pure Lead UNS L50021, Pure Lead UNS L50049 and Chemical-Copper Lead UNS L51121. Note that ASTM B29-19 defines lead content by difference against elemental maxima rather than by a single purity figure.

Can the same machine produce lead alloys as well as refined lead?

Yes. Calcium, tin and antimony dosing is built into the final kettle with in-kettle sampling between additions, so Pb-Ca and Pb-Ca-Sn grid alloys, Pb-Sn solders and stationary battery plate alloys, and Pb-Sb grid and parts alloys are produced on the same campaign as soft refined lead. The chemical-copper lead grade of ASTM B29-19 is also produced in the same vessel by stopping the de-coppering sequence at a controlled copper band of 0.040% to 0.080% instead of taking copper down to a maximum.