Platinum Palladium Rhodium Recovery & Refining Plant

— Turnkey Platinum Palladium Rhodium Recovery & Refining Plant

A Platinum Palladium Rhodium Recovery and Refining Plant is a turnkey platinum-group-metal plant that takes PGM-bearing secondary material — spent autocatalysts, industrial catalysts, e-waste fractions, jewellery sweeps, refinery residues and PGM liquors — through feedstock preparation, thermal pre-concentration, oxidative dissolution, selective separation and final reduction, and delivers platinum, palladium and rhodium as three separate, assay-certified metals at Pt ≥ 99.95%, Pd ≥ 99.95% and Rh ≥ 99.90%. Recovery runs above 99% for platinum and palladium and around 95% for rhodium on autocatalyst feed, with direct PGM recovery up to 99% on material from roughly 5% PGM content upward. the process route is cyanide-free, capacity is engineered from a few kilograms to several tonnes of PGM-bearing feed per day, and every consignment leaves against a Certificate of Analysis from fire assay with ICP-OES confirmation.

Product Overview

The Platinum Palladium Rhodium Recovery and Refining Plant is the complete PGM circuit of a precious-metal works: the front end that receives, prepares and pre-concentrates PGM-bearing material, the middle that dissolves and separates platinum, palladium and rhodium one from another, and the back end that reduces, melts, assays and packs three saleable metals — with the gas, effluent and residue circuits engineered as part of the same plant rather than added afterwards. It is, in effect, a self-contained PGM recovery refining plant on one site. Platinum, palladium and rhodium sit at the centre of automotive emission control, petrochemical and fine-chemical catalysis, glass and optical-fibre production, electronics, dentistry and the emerging hydrogen economy. Primary supply is concentrated in a handful of geological provinces, so an increasing share of the world’s Pt, Pd and Rh comes out of secondary material: three-way catalytic converters, palladium-on-carbon and platinum reforming catalysts, rhodium hydroformylation catalysts, fuel-cell and electrolyser stacks, workshop sweeps, thermocouple wire and spent plating solutions. That secondary material is what this plant is engineered for. On rhodium specifically — ranked in the highest supply-chain risk category by the United States Geological Survey — recovery from secondary sources is the only route to new supply that does not depend on a single mining region.

A recovery plant is required because PGM material rarely arrives at a dissolvable grade, and because PGM chemistry punishes any shortcut. Autocatalyst monoliths carry platinum, palladium and rhodium in a cordierite, alumina or ceria washcoat at concentrations well below the threshold at which direct acid attack is economic, and catalyst carriers arrive loaded with carbon, oil, organics and base metals. The plant therefore opens with feedstock preparation — dismantling, crushing, milling, screening, blending and representative sampling — followed by thermal pretreatment and pre-concentration: incineration or roasting to burn off carbon and organics and open up the alumina encapsulation that forms during catalyst service, or smelting in an electric-arc or reverberatory furnace with a base-metal collector to produce a PGM bullion. Published life-cycle assessment of an integrated precious-metal refinery that recovers gold, silver, platinum, palladium and rhodium from production scrap, spent catalysts, liquid waste and incineration ash reports a carbon footprint of 0.18 t CO₂ eq per kg of platinum, 0.47 t CO₂ eq per kg of palladium and 1.55 t CO₂ eq per kg of rhodium — the order of magnitude that makes secondary PGM recovery materially less carbon-intensive than primary production.

The separation chain is the classic chloride route, and it is where the metals are won or lost. Platinum and palladium enter chloride solution comparatively easily; rhodium, iridium and ruthenium do not, because their aqua-chloride complexes are kinetically inert and their higher oxidation states are difficult to reach. Palladium can additionally oxidise to palladium oxide (PdO), which is insoluble in both acid and alkali and therefore dissolves very poorly on a straight aqua regia attack. The plant answers this with a pretreatment stage — acid washing to strip iron, copper, nickel and zinc, and conditioning of the refractory fraction by roasting, oxidation or oxidising fusion — because the dissolution rate set at that stage is what the final recovery figure is built on. In chloride media silver reports as low-solubility silver chloride and is filtered off; ammonium chloride precipitates crude ammonium chloroplatinate, which is redissolved and re-precipitated and/or purified by oxidative hydrolysis until the salt reaches specification, then calcined above 800 °C and hydrogen-reduced to sponge platinum. The gold-barren filtrate is reduced with anhydrous sodium sulfite to gold powder, and the palladium that follows is precipitated as ammonium chloropalladate, purified through complexation–dissolution–acidification cycles and reduced with hydrazine hydrate, formic acid or hydrogen to palladium powder. Rhodium is the difficult one: the sodium chlororhodate solution is adjusted in acidity and treated with ammonium sulfite so that rhodium precipitates as an ammonium trisulfite complex while iridium stays in solution — a ligand-substitution separation, not a simple precipitation — and the rhodium salt is converted to ammonium chlororhodate and hydrogen-reduced to rhodium metal powder. Where precipitation alone cannot reach the target grade, solvent extraction and ion exchange are inserted — TBP, DBC and amine extractants on mixer-settler banks or centrifugal extractors, plus resin and molecular-recognition columns — to split and polish individual streams.

The gas and liquid circuits are design drivers on a PGM plant, not accessories. PGM dissolution is the most fuming operation in precious-metal refining and its off-gas carries acid mist, chlorine-containing vapour and a very high nitrogen-oxide load. Reactors are fitted with sealed mouths and a sealed reaction hood; vapour passes through a cold-water circulation condenser and gas–liquid separator so the condensate — which carries dissolved and entrained precious metal — returns to the reactor instead of being vented or blown out of the workshop; the remaining NOₓ goes to a multi-stage jet-spray absorption tower with a non-oxidation tank and two-stage alkali neutralisation. The plant is sized for inlet NOₓ of the order of 30,000 mg/m³ and holds the stack below 100 mg/m³. On the liquid side, solution is moved by vacuum transfer rather than pouring; filtration uses horizontal filters with a slight incline so the last of the solution can be drawn off, with filter presses and wheel filters on diaphragm pumps for slurry duty; and glass elevated storage tanks replace polypropylene vessels wherever duty allows, because glass is transparent, easy to clean and easy to inspect, so level control is visual and residual metal held up on tank walls is minimised. Raffinate leaving solvent extraction is never discharged — equilibrium losses, untargeted PGMs and residual chloride are polished by ion exchange and, where concentration is too low for resin to load efficiently, by membrane pre-concentration, and the cleaned chloride solution is returned to the circuit.

The result is a compact, cyanide-free, closed-loop PGM plant that a catalyst recycler, precious-metal refiner or trader, e-waste processor or industrial catalyst user can own and operate on site: platinum, palladium and rhodium recovered at full metal value, short cycle times, low in-process inventory of extremely high-value metal, off-gas and effluent treated inside the same package, and every batch released against an assay certificate. Wetted parts — reactor, filter, tank, piping — are selected against the actual chemistry from glass, glass-lined (enamel) steel, titanium, titanium-clad, stainless steel and anti-ageing PP / PPH; casting to bars, buttons and granules is done in induction furnaces under inert gas or vacuum; and reagent addition, temperature, pH, vacuum transfer and scrubbing are PLC-controlled with parameter logging and interlocks.

Application Scenarios

A platinum palladium rhodium recovery and refining plant is specified wherever PGM-bearing material exists in volume and the operator wants to own the recovery and the final separation step instead of selling a mixed concentrate at a discount to a third-party refiner.

Automotive catalyst recyclers — process whole three-way catalytic converters through dismantling, decanning and milling, then refine the PGM concentrate into three separate metals rather than a mixed Pt / Pd / Rh product. Output: Pt, Pd and Rh sponge and powder.
Autocatalyst washcoat and honeycomb processors — treat milled ceramic and metallic monolith powder, washcoat fines and decanning residue as the primary feed. Output: separate Pt, Pd and Rh metals at ≥ 99.95% / ≥ 99.95% / ≥ 99.90%.
Spent industrial and petrochemical catalyst reclaim plants — recover palladium-on-carbon, platinum reforming, palladium hydrogenation and rhodium hydroformylation catalysts back to metal. Output: recovered PGM sponge, with the support routed away.
Chemical and pharmaceutical producers — refine in-house catalyst change-out, guard-bed material and production residues instead of surrendering them to an external refiner. Output: recovered PGM metal and a documented mass balance.
Precious-metal refineries and assay houses — add or replace a PGM recovery and separation train with glass reactors, horizontal filtration and low hold-up of high-value metal. Output: certified Pt, Pd and Rh metal.
E-waste and PCB recyclers — feed the precious-metal alloy, concentrate or pregnant liquor produced by the front end of an e-waste line into a PGM recovery circuit. Output: Pd and Pt metal, with Au and Ag finished on the same site.
Jewellery and precious-metal workshops — recover platinum and palladium from alloy scrap, sweeps, polishing dust, filings and floor residues in-house and quickly. Output: Pt and Pd bars, sponge and powder.
Glass, optical-fibre and crystal producers — recover rhodium and platinum from spent bushings, stirrers, crucibles and platinum-rhodium ware. Output: Rh and Pt metal powder.
Hydrogen and fuel-cell supply chains — recover platinum from membrane electrode assemblies, electrolyser stack scrap and catalyst production waste. Output: Pt ≥ 99.95% sponge.
Copper-nickel and PGM smelter operators — treat PGM-bearing anode slime, converter matte leach residue and refinery residue on site, with an optional smelting front end. Output: individual PGM metals plus base-metal by-products.
Dental, medical and laboratory operations — recover Pt, Pd and Rh from alloy scrap, crucibles, thermocouple wire, gauze and bench residues. Output: high-purity PGM powder.
Precious-metal traders, banks and fabricators — convert mixed, contaminated or off-spec PGM material back to assay-certified metal with full batch traceability. Output: certified sponge and bars with assay documents.
National and regional critical-metals programmes — build domestic closed-loop PGM capacity from secondary sources instead of relying on imported refined metal. Output: domestically refined Pt, Pd and Rh for strategic and industrial users.
Universities, institutes and pilot facilities — bench and pilot PGM recovery and refining trains for process development, teaching and small-batch work. Output: analytical-grade Pt, Pd and Rh.

Applicable Raw Materials

Route selection follows the assay. The plant is fed with PGM-bearing material that has been concentrated to a dissolvable grade — typically from about 5% PGM content upward for direct separation and refining — while leaner material such as raw washcoat powder or e-waste fractions is first upgraded inside the plant by incineration, roasting, smelting or selective leaching, because that is where a PGM recovery project is won or lost economically.

Spent automotive three-way catalysts and autocatalyst powder — ceramic and metallic monoliths, decanned honeycomb, milled monolith powder and washcoat fines carrying Pt, Pd and Rh in a cordierite, alumina or ceria-based matrix. Output: separate Pt, Pd and Rh sponge and powder.
PGM bullion, matte and concentrate from pre-processing — the PGM-enriched alloy button, matte, calcined catalyst concentrate or ash produced by smelting, fusion or selective leaching of catalysts and e-waste. Output: dissolved PGM chloride liquor.
Spent palladium-on-carbon and palladium-alumina catalysts — hydrogenation and fine-chemical catalysts, wet or dry, including spent ligand systems and process residue. Output: Pd ≥ 99.95% powder.
Spent platinum reforming and oxidation catalysts — petrochemical reforming catalysts and Pt-alumina oxidation catalysts, together with platinum gauze and catchment material from nitric acid plants. Output: Pt ≥ 99.95% sponge.
Spent rhodium process catalysts — hydroformylation and other rhodium-based homogeneous and supported catalysts, and rhodium-containing process residue. Output: Rh ≥ 99.90% powder.
Platinum-rhodium ware and high-temperature components — thermocouple wire, gauze, bushings, stirrers, crucibles, nozzles, and refractory brick or glass-cullet waste from the glass and optical-fibre industry. Output: Rh and Pt metal powder.
Jewellery and workshop sweeps — platinum and palladium alloy scrap, sprues, filings, polishing dust and floor sweepings, plus karat gold where the same line finishes Au. Output: Pt and Pd metal, plus gold powder.
Electronic and e-waste precious-metal fractions — PGM-bearing alloy, connector and contact scrap, multilayer ceramic capacitor (MLCC) residues, and the concentrate or pregnant liquor produced by PCB processing. Output: Pd, Pt, Au and Ag metal.
Fuel-cell and electrolyser materials — membrane electrode assemblies, stack scrap, catalyst-coated membranes and catalyst production waste. Output: Pt ≥ 99.95% sponge.
Spent plating, electrolyte and ion-exchange material — platinum and palladium plating baths, drag-out and strip solutions, spent electrolyte, and loaded ion-exchange resin or activated carbon. Output: recovered PGM metal and recyclable liquor.
PGM anode slime, refinery residue and process liquors — copper-nickel electrorefinery slime, precious-metal refinery tail residues, PGM chloride stock solutions, solvent-extraction raffinate and stripped liquors. Output: individual refined PGM metals and base-metal by-products.
Incineration ash and industrial residues — precious-metal-bearing incineration ash, filter cake, sludge and floor residue from refineries, mints and industrial catalyst users. Output: recovered PGM metal and decontaminated inert residue.
Mining concentrates and tailings — primary PGM concentrate, flotation concentrate and PGM-bearing tailings where a hydrometallurgical route is preferred to smelting. Output: individual refined PGM metals.

Output Products

Every consignment leaves the plant against a Certificate of Analysis produced by fire assay with ICP-OES confirmation, and each metal is packed in the form its buyer wants — sponge, powder, granules or cast bar.

Refined platinum — precipitated as ammonium chloroplatinate, purified by re-precipitation and/or oxidative hydrolysis, then calcined and hydrogen-reduced toPt ≥ 99.95%. Output: platinum sponge, and cast bars, granules or buttons on request.
Refined palladium — separated as ammonium chloropalladate, purified through complexation cycles and reduced with hydrazine hydrate, formic acid or hydrogen toPd ≥ 99.95%. Output: palladium sponge and powder.
Refined rhodium — separated by ammonium sulfite complexation and ligand substitution, converted to ammonium chlororhodate and hydrogen-reduced toRh ≥ 99.90%. Output: rhodium metal powder and sponge.
Iridium, ruthenium and osmium — recovered on request: iridium from the rhodium tail liquid by oxidation and coprecipitation, ruthenium by oxidative distillation as its volatile tetroxide, osmium only in a dedicated fully enclosed circuit. Output: Ir, Ru and Os powder and salts.
PGM salts and solutions — where a buyer prefers chemical form, purified intermediates and salts (chloroplatinic acid, ammonium chloroplatinate, palladium chloride, rhodium chloride and their ammonium salts) are supplied rather than reduced to metal. Output: purified PGM salts and standardised solutions.
Gold and silver co-products — where the feed also carries Au and Ag, silver leaves as silver chloride for its own electrolytic circuit and gold is reduced out as powder. Output: gold powder ≥ 99.99% and silver chloride / silver metal.
Base-metal and support by-products — iron, copper, nickel and zinc removed in the acid-wash pretreatment are recovered by cementation, precipitation or electrowinning, and spent catalyst support is routed to sale or disposal. Output: base-metal salts or cathode, and decontaminated support.
Treated off-gas and closed-loop water — scrubbed exhaust with NOₓ below 100 mg/m³, and neutralised, metal-polished water recirculated to the wash and rinse loop. Output: compliant emission and recirculated process water.
Batch documentation — input assay, process record and output certificate for every lot, in the form banks, metal buyers and environmental authorities expect. Output: Certificate of Analysis and batch traceability record.

Process Flow

The plant runs as a staged route in which the PGM-bearing feed is first concentrated and conditioned, then the three metals are pulled apart one at a time — silver first, then gold, then platinum, then palladium, and rhodium last — with the gas circuit, the raffinate polishing loop and the effluent circuit running continuously in parallel with the metal chain rather than behind it.

Steps 1 — Feedstock Receiving, Sorting and Assay. Incoming material is weighed, photographed and logged batch by batch, then sorted by type — autocatalyst monoliths, milled catalyst powder, industrial catalyst, e-waste fraction, sweeps, wire, residue or process liquor — because each stream follows a different pretreatment and dissolution route. A representative sample is drawn from every lot and assayed by XRF and fire assay with ICP-OES confirmation, and each batch is tagged for traceability from the gate to the finished metal. Output: sorted, weighed, assayed and barcoded batch with a route sheet.

Steps 2 — Size Reduction and Homogenisation. Monoliths are decanned and crushed and the honeycomb, washcoat and metallic carrier are separated; catalyst powder, sweeps, wire, ash and residue feed is milled and screened to a uniform particle size so that the acid attack in Steps 4 is complete rather than partial; oil, organics, plastics and loose base metal are removed where the assay requires it; and blended lots are homogenised so that a sample of the blend represents the whole. Output: milled, homogeneous, assayed feed with a confirmed batch mass balance.

Steps 3 — Thermal Pretreatment and PGM Pre-Concentration. Feed is incinerated or roasted to burn off carbon, oil and organics and to open up the alumina encapsulation that forms around PGM particles during catalyst service, and where the grade is too low for economic direct refining it is smelted in an electric-arc or reverberatory furnace with a base-metal collector so that the platinum-group metals report to a PGM bullion while the carrier forms a slag. Off-gas from this stage passes through dust collection and scrubbing. Output: PGM bullion, calcined concentrate or conditioned ash at a dissolvable grade, plus decontaminated slag and collected dust.

Steps 4 — Base-Metal Removal and Oxidative Dissolution. The conditioned feed is washed with hydrochloric or nitric acid to dissolve iron, copper, nickel, zinc and other base metals before the precious metals are attacked, and the refractory fraction is additionally conditioned — palladium oxide and deeply alloyed rhodium, iridium and ruthenium are roasted, oxidised or subjected to an oxidising fusion so that their dissolution rate in the following attack rises instead of leaving metal in the residue. The prepared feed is then charged into a sealed, enclosed reactor — glass-lined (enamel) steel, titanium, titanium-clad or anti-ageing PP, or an inclined tumbling reactor held at about 25° for dense and sludge-like material — and dissolved in aqua regia at roughly 3:1 hydrochloric to nitric acid, or in hydrochloric acid with chlorine gas as the oxidant. In chloride media platinum, palladium and gold go into solution as chloro-complexes while silver reports as low-solubility silver chloride and stays in the residue. The reactor mouth is sealed; vapour passes through a cold-water circulation condenser and gas–liquid separator; the precious-metal-bearing condensate returns to the reactor and the nitrogen oxide is routed to the jet-spray tower. Reaction time is typically 3–6 hours depending on feed type and particle size. Output: PGM chloride liquor carrying PtCl₆²⁻, PdCl₄²⁻ and RhCl₆³⁻, plus silver chloride and insoluble residue.

Steps 5 — Silver and Gold Recovery. Sodium chloride is added to the liquor to precipitate silver as silver chloride, which is filtered off on a horizontal filter or filter press and routed to a silver circuit. Ammonium chloride is then added to precipitate crude ammonium chloroplatinate, which is transferred to platinum refining; the filtrate is reduced with anhydrous sodium sulfite to precipitate gold powder, which is filtered, washed and dried. Output: silver chloride residue, crude ammonium chloroplatinate, gold powder, and a gold-barren filtrate carrying palladium and rhodium.

Steps 6 — Platinum Separation and Purification. The crude ammonium chloroplatinate is redissolved and re-precipitated — the ammonium chloride repeated precipitation method — and/or purified by oxidative hydrolysis to drive out iridium, rhodium and base-metal impurities, until the salt reaches specification. The purified salt is calcined at above 800 °C to drive off nitrogen and chlorine, and hydrogen-reduced to a metal sponge that is dried, sampled and packed. Output: platinum sponge at Pt ≥ 99.95%, or cast platinum bars and granules on request.

Steps 7 — Palladium Separation and Reduction. Palladium is precipitated from the filtrate with ammonium chloride as ammonium chloropalladate, then purified through complexation–dissolution–acidification cycles or the ammonia complexation combined process to remove residual base metals and other platinum-group metals. The purified compound is reduced with hydrazine hydrate, formic acid or hydrogen gas, and dried to metal powder. Output: palladium sponge and powder at Pd ≥ 99.95%.

Steps 8 — Rhodium and Iridium Separation. The remaining liquor is prepared as a sodium chlororhodate solution of the order of 50 g/L rhodium and its pH is adjusted to about 1–1.5 with a dilute alkali; a 25% ammonium sulfite solution is added at a volume ratio of roughly 1:0.75, and the batch is boiled with the pH controlled near 6.4 so that rhodium precipitates as a milky-white ammonium trisulfite complex while iridium does not form a similar precipitate and stays in solution. The rhodium compound is filtered, washed with pure water, redissolved in boiling concentrated hydrochloric acid to ammonium chlororhodate and converted through ammonia coordination, then reduced with hydrogen to metal. Iridium is recovered from the tail liquid by oxidation and coprecipitation, refined and ground. Output: rhodium metal powder at Rh ≥ 99.90%, and iridium powder where required.

Steps 9 — Raffinate Polishing and Environmental Control. Reactor off-gas passes through the condenser and mist separator, then a multi-stage jet-spray absorption tower with a gas–liquid separator and non-oxidation tank, followed by two-stage alkali neutralisation; the tower is sized for an inlet nitrogen-oxide load of the order of 30,000 mg/m³ and holds the outlet below 100 mg/m³ at 99.5% or better absorption, while condensate and scrubber liquor are returned to the process instead of being discharged. On the liquid side, raffinate leaving solvent extraction is polished rather than discarded: ion exchange recovers PGM chloro-complexes at ppm-to-ppb concentrations under a selectivity order of Pd > Pt > Ir > Rh > Ru, and where rhodium concentration is too low for efficient resin loading the stream is pre-concentrated by membrane separation before it returns to the refining circuit. Wastewater and bleed streams are segregated, neutralised, metal-polished and recirculated, and acid-based process liquors are reused. Output: compliant off-gas, a PGM-rich eluate returned to the refinery, and polish water below 10 ppm metal for recirculation.

Steps 10 — Melting, Casting and Certificate of Analysis. The purified powders and sponges are dried and reduced, then melted in induction furnaces under inert gas or vacuum and cast into bars, granules or buttons, while sponge intended for catalyst and alloy makers is packed as produced. Every lot is re-assayed by fire assay and ICP-OES and released against a Certificate of Analysis. Output: certified platinum, palladium and rhodium metal with full assay documentation.

The main chain runs vertically through receiving → size reduction → thermal pretreatment → dissolution → silver and gold recovery → platinum → palladium → rhodium → polishing and environmental control → casting. Side branches route incineration and smelting off-gas through dust collection, reactor vapour and scrubber liquor back to the process, silver chloride to the silver circuit, gold powder to the gold circuit, the iridium-bearing tail liquid to iridium recovery, ion-exchange eluate back to the refinery, slag and decontaminated support to sale or disposal, and neutralised water to the rinse loop.

Product Structure (Main Equipment)

The plant is supplied as factory-assembled, piped and functionally tested modules on a turnkey basis, with the wetted path built from glass, glass-lined steel, titanium, titanium-clad, stainless steel and anti-ageing PP / PPH according to duty.

Feedstock Receiving, Sorting and Weighing Station — weighbridge or platform scale, sorting benches, barcode tagging and batch-record station. Function: establishing the mass balance and traceability chain that all downstream metal accounting depends on.
Monolith Dismantling and Decanning Unit — converter shell cutter, decanning press and honeycomb extraction for whole autocatalysts, with dust extraction. Function: separating ceramic or metallic substrate from the steel shell as the first recovery step.
Crushing, Milling and Screening Unit — jaw or hammer crusher, ball or hammer mill, screen deck and dust extraction, with magnetic separation for loose ferrous material. Function: reducing feed to a uniform particle size so that acid attack is complete rather than partial.
Blending, Homogenisation and Sampling Station — ribbon or cone blender, riffle and rotary sample dividers, and sample-preparation bench. Function: producing a feed that is homogeneous enough for a sample to represent the whole batch.
Thermal Pretreatment Furnace Set — incinerator or roaster for carbon, oil and organic removal; calciner for catalyst concentrate; oxidising or roasting furnace for conditioning refractory PGM fractions. Function: opening alumina encapsulation and converting palladium oxide and inert Rh / Ir / Ru phases into dissolvable form.
Smelting and Pre-Concentration Furnace — electric-arc or reverberatory melting furnace with collector-metal charge system, slag handling and tapping, plus dust collection and off-gas scrubbing. Function: concentrating low-grade and mixed feed into a PGM bullion or matte that the chemical section can handle economically.
Pretreatment and Acid-Wash Reactor — enclosed glass-lined or PP reactor with agitation and heating for hydrochloric / nitric acid washing of base metals. Function: removing iron, copper, nickel and zinc before the precious metals are attacked.
Enclosed Dissolution Reactor Train — glass-lined (enamel) kettles, titanium and titanium-clad vessels, static glass reactors and anti-ageing PP reactors with agitation, controlled heating, reflux, sealed reaction mouth and vacuum transfer connections. Function: dissolving PGM feed under fully enclosed, controlled conditions.
Tumbler / Rotating Reactor — inclined PP or titanium cylinder, typically set at about 25°, with speed-controlled continuous rotation, automatic dosing and direct or indirect electric or fired heating. Function: keeping dense, sludge-like and granular feed in contact with the liquor so dissolution completes in a short residence time.
Sealed Reaction Hood, Condenser and Gas–Liquid Separation Unit — sealed fume hood over the reactor mouth with a cold-water circulation condenser, gas–liquid separator and condensate return line. Function: condensing acid vapour and steam, returning the precious metal carried in the condensate to the reactor, and preventing metal loss to atmosphere.
Reagent Preparation and Dosing Station — graduated chemical tanks, metering and dosing pumps, and PP trays inside secondary containment for acids, ammonium chloride, ammonium sulfite, sodium chloride, sodium sulfite, alkali and reducing agents. Function: precise, repeatable reagent addition with reduced operator exposure.
Filtration and Solution Transfer Skid — horizontal filters with a slight incline for complete vacuum draw-off, plate-and-frame filter press, wheel filter with diaphragm pump, candle filters for catalyst slurry, glass elevated storage tanks, vacuum receivers and solution transfer piping. Function: clarifying liquor, washing and dewatering precipitate, and moving high-value solution by vacuum rather than pouring.
Precipitation and Reduction Reactor Set — dedicated agitated reactors with temperature control and dosing for ammonium chloroplatinate and ammonium chloropalladate precipitation, sulfite reduction of gold, and hydrazine hydrate / formic acid / hydrogen reduction of palladium. Function: selective recovery of a single metal out of a mixed PGM liquor.
Rhodium Complexation and Separation Unit — pH-controlled reactor with alkali dosing, sulfite addition and boiling control, filtration, washing and redissolution vessels for the ammonium trisulfite route to ammonium chlororhodate. Function: separating rhodium from iridium and from residual base metals.
Solvent Extraction Skid — mixer-settler banks for TBP, DBC and amine extractants, with scrub and strip circuits and centrifugal extractors. Function: splitting and polishing individual PGM streams where precipitation alone cannot reach the target grade.
Ion-Exchange and Raffinate Polishing Unit — resin-packed columns with loading, elution and regeneration circuits, molecular-recognition media, and membrane separation for pre-concentration of dilute rhodium streams. Function: recovering trace PGMs from raffinate and returning a clean chloride solution to the circuit.
Electrowinning and Dilute-Stream Recovery Units — high-current-density and rotating or cyclone electrowinning cells, resin and activated-carbon capture columns. Function: recovering PGM and base metals from wash water, bleed, eluate and dilute liquor instead of neutralising the metal to waste.
Nitrogen Oxide and Acid Gas Treatment System — multi-stage jet-spray absorption tower in anti-ageing PPH, gas–liquid separators, non-oxidation tank, circulation pumps and tank, and two-stage alkali neutralisation with pH control. Function: reducing NOₓ from the order of 30,000 mg/m³ at the inlet to below 100 mg/m³, and absorbing HCl, Cl₂, SO₂ and acid mist.
Dust Collection and Thermal-Stage Off-Gas Treatment — cyclone, bag filter or sleeve filter unit with ductwork and induced draught fan. Function: capturing PGM-bearing dust from crushing, milling, incineration and smelting so it re-enters the circuit instead of the environment.
Wastewater Neutralisation and Polishing Unit — neutralisation reactor, settling tank, sludge filter press and polish-water loop with metal analysis. Function: compliant discharge and recirculation of process water.
Calcination, Reduction and Drying Furnace Set — calcination furnace for ammonium salts, hydrogen reduction furnace and controlled drying ovens. Function: converting purified PGM salts to metal sponge and powder at controlled temperature and atmosphere.
Melting, Granulation and Casting Unit — medium- and high-frequency induction melting furnaces, granulator, ingot moulds and vacuum ingot casting machine with inert-gas pressurisation and tight temperature control. Function: casting void-free bars or producing granules and buttons from refined PGM metal.
Assay and Quality-Control Laboratory — XRF analyser, fire-assay furnace and cupellation equipment, sample-preparation bench, potentiometric titration and ICP-OES. Function: input control, in-process checking and Certificate of Analysis.
PLC Automation and Control Cabinet — PLC with touch-screen HMI, dosing, temperature, pH, vacuum, off-gas and scrubbing control, rectifier and pump control, parameter logging, alarms and interlocks. Function: repeatable, safe, traceable operation and a defensible metal-accounting record.
Safety and Workplace Package — reactor fume hoods, local extraction, acid-proof flooring and matting, secondary containment, eyewash and safety shower, gas-detection interlocks and operator protective equipment. Function: operator protection and compliance with workplace chemical-handling rules.

Product Features

Recovery and refining in one plant. The front end that prepares and concentrates PGM-bearing material and the back end that separates it into three individual metals are designed as a single flowsheet, so the grade the chemical section receives is set by the plant rather than by an outside supplier.
Pretreatment stage included, not optional. Acid washing and conditioning of the refractory fraction are built into the flow, which is what allows palladium oxide and alloyed rhodium, iridium and ruthenium to dissolve instead of reporting to the residue and being sold as a loss.
Purpose-built for the three PGM metals. The route is designed around the individual chemistry of platinum, palladium and rhodium — ammonium chloroplatinate and ammonium chloropalladate precipitation for Pt and Pd, ammonium sulfite complexation and ligand substitution for Rh — not as a gold line with a PGM stage bolted on.
Rhodium separated from iridium by chemistry. The ammonium trisulfite separation is run as a controlled, pH-managed operation, so rhodium is recovered as a clean compound while iridium remains in solution and is subsequently recovered rather than contaminating the rhodium product.
Raffinate is polished, never discharged. Ion exchange, molecular-recognition media and membrane pre-concentration recover PGM from ppm-level equilibrium losses and dilute streams, and the cleaned chloride solution returns to the circuit — which is what converts a nominal recovery figure into a plant-level one.
Sealed reactors with condensate recovery. Sealed reaction mouths and hoods, a cold-water circulation condenser and a gas–liquid separator keep vapour inside the system and return the metal-bearing condensate to the reactor — the single largest avoidable PGM loss in older open-hood refineries.
High-concentration NOₓ handled inside the package. Multi-stage jet-spray absorption with a non-oxidation tank and two-stage alkali neutralisation is sized for the nitrogen-oxide load that PGM dissolution actually produces, holding the outlet below 100 mg/m³ at 99.5% or better absorption.
Dust from the mechanical and thermal stages is captured. Crushing, milling, incineration and smelting all generate PGM-bearing dust; cyclone and bag-filter capture with return to the process keeps that metal in the circuit instead of the stack.
High recovery on high-grade feed. Recovery runs above 99% for platinum and palladium and around 95% for rhodium from autocatalyst feed, with direct PGM recovery up to 99% on suitable material from about 5% PGM content upward, supported by raffinate, condensate and filter wash liquor being returned to the circuit.
Purity established by re-precipitation, not by hope. Repeated precipitation, oxidative hydrolysis, complexation–dissolution–acidification cycles and hydrogen reduction are specified for each metal, delivering Pt ≥ 99.95%, Pd ≥ 99.95% and Rh ≥ 99.90%.
Low hold-up of very high-value metal. Glass elevated tanks, horizontal filters, vacuum transfer and short 3–6 hour batch reactions keep solution volumes and equipment surfaces small, so far less platinum, palladium and rhodium is tied up in process inventory at any moment.
Heat recovery on the thermal stage. Hot incineration and smelting off-gas is routed through heat recovery before scrubbing where the duty allows, cutting the fuel and power load of the pretreatment section.
Corrosion-engineered wetted path. Glass, glass-lined enamel steel, titanium, titanium-clad, stainless steel and anti-ageing PP / PPH are selected against the real duty — aqua regia, chloride liquor, ammonium sulfite, alkali and thermal-stage dust — rather than a single material used everywhere.
Cyanide-free chemistry. The standard route uses aqua regia, chloride and chlorine oxidant, sulfite, ammonium salts and hydrogen, with no cyanide salt anywhere in the flow.
Visibility and cleanability as design principles. Transparent glass vessels and filters let the operator see colour change, level and precipitate formation directly, and they clean out completely, so residual metal held on equipment surfaces is minimised.
Batch accountability. Weighing, sampling and assaying are tied to a batch record from receiving to dispatch, and every consignment is released against an assay certificate from fire assay and ICP-OES — essential when a single batch can be worth more than the plant.
Modular and scalable. The same process logic runs from bench and pilot trains to multi-tonne industrial plants; capacity is added by duplicating reactor, separation, polishing and treatment trains rather than by redesigning the chemistry.

Technical Parameters & Specifications

Values below describe the standard process envelope and product outcomes. Throughput, footprint, power and utility figures are engineered to each client’s feed assay, target metals and site conditions, and are confirmed at design review.

Parameter	Specification
Product	Platinum Palladium Rhodium Recovery and Refining Plant (integrated PGM recovery, separation and refining plant)
Metals recovered	Platinum (Pt) · Palladium (Pd) · Rhodium (Rh); iridium (Ir) and ruthenium (Ru) on request
Process route	Integrated route: feedstock preparation and homogenisation → thermal pretreatment and pre-concentration → acid-wash pretreatment → aqua regia / chlorination dissolution → silver and gold recovery → selective precipitation → solvent extraction and ion exchange → reduction → calcination, melting and casting
Plant configuration	Turnkey, skid-mounted and modular: mechanical preparation section · thermal pretreatment and smelting section · chemical dissolution and separation section · solvent extraction and polishing section · off-gas and effluent treatment section · reduction, casting and assay section
Overall PGM recovery	Above 99% for platinum and palladium and around 95% for rhodium on autocatalyst feed; direct PGM recovery up to 99% on suitable feed, with raffinate, condensate, eluate and wash liquors returned to the circuit
Refined platinum purity	Pt ≥ 99.95% (ammonium chloride repeated precipitation and/or oxidative hydrolysis)
Refined palladium purity	Pd ≥ 99.95% (ammonium chloropalladate precipitation; ammonia complexation combined process)
Refined rhodium purity	Rh ≥ 99.90% (ammonium sulfite complexation and ligand substitution)
Optional metal purity	Ir and Ru powder on request; PGM salts to specification in chemical form
Recommended feed grade	PGM content from about 5% upward for direct separation and refining; leaner material is pre-concentrated in the thermal or smelting section
Plant scale	Engineered from laboratory and pilot scale to industrial turnkey plants, from a few kilograms to several tonnes of PGM-bearing feed per day; capacity fixed at design review
Thermal pretreatment	Incineration and roasting for carbon, oil and organic removal · calcination of catalyst concentrate · roasting, oxidation or oxidising fusion for refractory Rh / Ir / Ru fractions · electric-arc or reverberatory collection smelting for low-grade feed
Dissolution chemistry	Aqua regia (approximately 3:1 HCl : HNO₃) · hydrochloric acid with chlorine gas as oxidant · nitric acid parting · pressure leaching · oxidising fusion for refractory fractions
Pretreatment chemistry	Hydrochloric or nitric acid washing of base metals · roasting and oxidation conditioning of palladium oxide and alloyed PGM fractions
Platinum separation reagents	Ammonium chloride (ammonium chloroplatinate) · oxidative hydrolysis
Palladium separation reagents	Ammonium chloride (ammonium chloropalladate) · ammonia complexation · hydrazine hydrate · formic acid · hydrogen
Rhodium separation reagents	Sodium chloride · ammonium sulfite (approximately 25% solution, volume ratio about 1:0.75) · concentrated hydrochloric acid · ammonia · hydrogen
Gold and silver reagents (where present)	Sodium chloride for silver chloride · anhydrous sodium sulfite for gold reduction
Separation technologies	Selective precipitation · ammonium salt precipitation · complexation and ligand substitution · solvent extraction (TBP, DBC, amine extractants) · centrifugal extraction · ion exchange and molecular-recognition media · membrane pre-concentration · cementation
Reactor materials	Glass-lined (enamel) steel · titanium and titanium-clad · static glass · anti-ageing PP / PPH · stainless steel where duty allows
Reactor configuration	Enclosed kettle with agitation, heating, reflux and sealed mouth · inclined tumbling reactor at about 25° with speed control and automatic dosing
Batch reaction time	Typically 3–6 hours for dissolution, depending on feed type and particle size
Precise rhodium operating window (typical)	Sodium chlororhodate solution at about 50 g/L Rh · pH adjusted to about 1–1.5 · 25% ammonium sulfite at a volume ratio of about 1:0.75 · boil at pH near 6.4 to precipitate the ammonium trisulfite complex
Platinum salt calcination temperature	Above 800 °C, followed by hydrogen reduction
Operating temperature range	Ambient to about 90–100 °C in the chemical section; higher temperature in the thermal pretreatment, calcination and melting furnaces
Filtration and transfer	Horizontal filter with slight incline and full vacuum draw-off · filter press · wheel filter with diaphragm pump · candle filter for catalyst slurry · vacuum solution transfer · glass elevated storage tanks
Off-gas inlet NOₓ concentration	Of the order of 30,000 mg/m³ from PGM dissolution
Treated NOₓ concentration	Below 100 mg/m³, within discharge standard
Scrubber absorption efficiency	≥ 99.5% for NOₓ, HCl, Cl₂, SO₂ and acid mist
Dust control	Cyclone and bag or sleeve filter capture on crushing, milling, incineration and smelting, with collected PGM-bearing dust returned to the process
Metal recovered from off-gas and dust	Condensate, scrubber liquor and collected dust returned to the process circuit
Raffinate polishing	Ion exchange with PGM selectivity order Pd > Pt > Ir > Rh > Ru · molecular-recognition media · membrane pre-concentration of dilute rhodium streams · scavenger precipitation for circuit cleanup
Wastewater treatment	Segregated collection, neutralisation, metal precipitation and polishing; polish water below 10 ppm metal, recirculated
Casting	Ingots, bars, granules, buttons and sponge; vacuum ingot casting with inert-gas pressurisation
Assay and quality control	XRF · fire assay with cupellation · ICP-OES, with a Certificate of Analysis per batch
Automation	PLC with touch-screen HMI; dosing, temperature, pH, vacuum, off-gas and scrubbing control; parameter logging, alarms and interlocks
Feed forms accepted	Monolith · milled catalyst powder · concentrate, bullion and matte · sweeps and wire · process liquor · loaded resin and carbon · ash, anode slime and residue
Standards	CE; EPA and EU emission and discharge limits; cyanide-free process route

Technical Advantages

The recovery stage is engineered, not assumed. Most PGM losses are set before the acid ever touches the metal: carbon and oil fouling, alumina encapsulation formed during catalyst service, refractory Rh / Ir / Ru phases and insoluble palladium oxide. Building incineration, roasting, conditioning and optional collection smelting into the plant is what makes a recovery above 99% for Pt and Pd a design outcome rather than a laboratory best case.
Dissolution rate is designed in. Because palladium oxide and alloyed rhodium, iridium and ruthenium dissolve very poorly on a straight aqua regia attack, the plant opens with an acid-wash and conditioning stage. Raising the dissolution rate at the front is the cheapest recovery improvement available anywhere in the flowsheet.
Rhodium is actually separated from iridium. The ammonium sulfite complexation route exploits the fact that iridium does not form the corresponding precipitate under the same conditions. A plant that treats rhodium as “the rest of the liquor” carries iridium into the rhodium product and loses both grade and value; here the two are separated deliberately.
Raffinate polishing turns equilibrium losses into product. Solvent extraction is an equilibrium process, not a one-way capture, so raffinate always carries residual metal. Ion exchange recovers it at ppm-to-ppb concentrations, and because rhodium loads 5–20× more weakly than palladium and 3–8× more weakly than platinum on chloride resins, membrane pre-concentration is used ahead of the resin bed so rhodium concentration is high enough to load efficiently.
Metal loss through the exhaust is captured, not vented. Open refining cabinets draw large air volumes, which evaporate solution and carry precious metal out with the vapour. Sealing the reactor mouth and condensing the vapour returns that metal to the batch — in a PGM plant this single detail can be worth more per year than the cost of the condenser.
Dust is treated as product, not as waste. Crushing, milling, incineration and smelting all generate PGM-bearing fines; cyclone and bag-filter capture with return to the process recovers a stream that is frequently lost in plants built around the chemical section alone.
The NOₓ problem is solved at the design stage. PGM dissolution generates nitrogen-oxide concentrations in the region of 30,000 mg/m³, roughly an order of magnitude beyond what a jewellery gold line produces, and collection smelting adds SO₂ and dust. The multi-stage jet-spray tower, gas–liquid separator, non-oxidation tank and two-stage alkali neutralisation are sized for that combined load, holding the outlet below 100 mg/m³.
Purity built by repetition and re-purification. Repeated ammonium chloride precipitation, oxidative hydrolysis for platinum, complexation–dissolution–acidification cycling for palladium and hydrogen reduction for rhodium and platinum are what hold Pt ≥ 99.95%, Pd ≥ 99.95% and Rh ≥ 99.90% batch after batch, rather than a single precipitation that drifts with the feed.
Solvent extraction and ion exchange available as a second lever. Where a feed is unusually complex — high iridium, mixed Pt / Pd ratio, heavy base-metal load — TBP, DBC and amine extractants on mixer-settler banks or centrifugal extractors, plus resin and molecular-recognition columns, split and polish the streams that precipitation alone cannot clean.
Low inventory of extremely high-value metal. Three to six hour batch reactions, small solution volumes, horizontal filters with full vacuum draw-off and glass elevated tanks together mean less platinum, palladium and rhodium is sitting in solution, on tank walls or in filter cakes at any moment — a direct reduction in working capital and metal at risk.
Corrosion protection matched to each duty. Aqua regia, chloride liquor, ammonium sulfite, ammonia, alkali and thermal-stage dust are aggressive in different ways; using glass-lined steel, titanium, static glass and anti-ageing PP where each belongs extends equipment life and avoids the contamination a wrongly chosen material causes.
By-products are recovered instead of disposed. Base metals removed in pretreatment, gold and silver where present, iridium from the tail liquid, PGM-bearing dust, slag and decontaminated catalyst support all leave as recoverable or saleable streams instead of tipping fees.
Dilute streams still pay. Cyclone, rotating-cathode and high-current-density electrowinning plus resin capture work from low concentrations upward, turning wash water, bleed and eluate that would otherwise be neutralised into recovered metal.
Compliance and licence to operate. Closed-loop water, condensate recovery, dust collection and 99.5%+ absorption keep the plant inside EPA and EU emission and discharge limits, and the cyanide-free route removes the most heavily regulated reagent class from the site entirely.
Batch traceability on a high-value product. Weighing, sampling and assay management are integrated into the control system from the gate onward, so every batch carries an input assay, a process record and an output Certificate of Analysis — the documentation auditors, banks and metal buyers expect.
Turnkey single-point accountability. One contractor owns test work, process design, equipment, assembly, commissioning and operator training, which removes the integration risk of assembling a PGM plant out of several vendors’ modules.

Service Process

YuSai delivers a platinum palladium rhodium recovery and refining plant as a full turnkey project, from feed characterisation and bench test work to a running, assay-verified PGM refinery.

Steps 1 — Feed Characterisation and Consultation. Send representative samples of your converter, catalyst, sweeps, ash, residue or PGM liquor. Our metallurgical team runs XRF, fire assay and ICP-OES, identifies the Pt, Pd, Rh and impurity levels, checks the base-metal, support and organic load, and proposes the optimal preparation, pretreatment, dissolution and separation route with the achievable purity and recovery. Output: assay report and preliminary route proposal.

Steps 2 — Laboratory Test Work and Process Design. Bench and pilot campaigns confirm pretreatment conditions, dissolution rates, reagent consumption, the separation sequence, decontamination of residue and slag, and expected recovery, and are converted into a mass balance, flowsheet, equipment list, vessel, tower and furnace sizing, utility schedule and plant layout against your throughput, site and local emission and discharge rules. Output: test report, process design package and firm quotation.

Steps 3 — Detailed Engineering and Manufacturing. Crushing, milling and blending equipment, thermal pretreatment and smelting furnaces, reactors, hoods and condensers, filtration and transfer skid, precipitation and complexation units, solvent-extraction and ion-exchange columns, NOₓ and acid-gas treatment tower, dust collection, wastewater plant, reduction and calcination furnaces, casting unit and control cabinet are fabricated, pre-assembled on skids and piped. Output: engineered, skid-mounted modules.

Steps 4 — Factory Assembly, Testing and Acceptance. Each module is functionally tested and the whole train is trial-run, wherever possible on your own material, with the client invited to attend the factory acceptance test before shipment. Output: FAT-approved, pre-commissioned modules.

Steps 5 — Shipping, Installation and Commissioning. We supervise the civil interface, erection, piping, ductwork and electrical tie-in, then run an instrumented commissioning campaign on your feed until the contracted purity and recovery are demonstrated and the NOₓ outlet and dust emission are verified against your local limits. Output: a producing PGM recovery and refining plant at contracted performance.

Steps 6 — Operator Training and Handover. On-site training covers safe aqua regia and chlorination working, thermal-stage operation, reagent handling and dosing, precipitation and complexation control, ion-exchange and raffinate polishing, off-gas and effluent operation, emergency procedures and assay QC, supported by Standard Operating Procedures and a full handover dossier. Output: trained crew and complete documentation.

Steps 7 — Process Optimisation and Ongoing Support. Remote troubleshooting, reagent supply, crucible, resin and carbon service, periodic performance audits and recovery or capacity upgrade paths keep the plant at target over its service life. Output: sustained performance and spare-part continuity.

Warranty & After-Sales Service

Standard warranty. Twelve (12) months from commissioning, or eighteen (18) months from shipment, whichever comes first, covering structural, mechanical, electrical, control, thermal and scrubbing equipment against defects in material and workmanship.
What the warranty covers. Replacement of defective components, repair or exchange of main-process equipment, and free remote technical guidance throughout the warranty period. Consumables such as reagents, crucibles, electrodes, resin, carbon and filter cloth, and damage caused by misuse, unauthorised modification or operation outside the agreed feed and process envelope, are excluded.
Guaranteed performance. We warrant that, when fed material inside the agreed assay and throughput envelope and operated to the supplied SOP, the plant meets the contracted Pt, Pd and Rh purity and recovery figures, verified at commissioning by fire assay and ICP-OES.
Response commitment. Guaranteed remote response within 24 hours, on-site engineer dispatch and hotline support for breakdowns affecting production, and expedited supply of critical spares.
Spare parts and consumables. Genuine spares, furnace elements, crucibles, rectifier components, metering pumps, ion-exchange resin, activated carbon, filter cloth, tower packing and reagent ranges are held as a stocking range to minimise downtime.
Commissioning and start-up support. Supervised installation, commissioning on the customer’s own feed, performance verification against contract, off-gas and dust emission verification, and an operator competence sign-off before handover.
Lifetime technical support. Free access to our engineering team for process questions after warranty expiry, plus optional retrofit, capacity-upgrade, recovery-improvement and reagent-optimisation services.
Documentation. Full operating, maintenance and safety manuals, electrical drawings, P&ID, scrubber and furnace documentation, spare-parts catalogue, SOPs and training material accompany every plant.
Compliance support. Assistance with local emission, effluent and chemical-storage permitting documentation, and with the assay and product-certification records that buyers and authorities require.

Frequently Asked Questions

Q1. What is a platinum palladium rhodium recovery and refining plant?
A platinum palladium rhodium recovery and refining plant is an integrated industrial plant that extracts and purifies platinum group metals from primary or secondary material such as spent catalytic converters, industrial catalysts, e-waste fractions and refinery residues. It covers feedstock preparation and homogenisation, thermal pretreatment and pre-concentration by incineration, roasting or smelting, leaching and dissolution in aqua regia or chloride media, separation and purification by selective precipitation, solvent extraction and ion exchange, final reduction to high-purity metal sponge or ingot, and environmental control of off-gas, dust and effluent inside the same plant. Products are Pt ≥ 99.95%, Pd ≥ 99.95% and Rh ≥ 99.90%.

Q2. What is the difference between a recovery plant and a refining plant?
Recovery is the front end and refining is the back end, and this plant contains both. Recovery takes dilute, mixed or contaminated material — whole converters, milled washcoat powder, ash, sweeps, e-waste fractions — and concentrates it into something the chemistry can handle, by mechanical preparation, incineration or roasting to remove carbon and organics, and collection smelting to produce a PGM bullion. Refining takes that concentrated feed and separates it into individual metals at ≥ 99.95% / ≥ 99.95% / ≥ 99.90%. Feeding a refinery directly with raw washcoat powder or e-waste fraction is the most common reason a PGM project underperforms; the recovery stage is what fixes the grade the refinery sees.

Q3. Which platinum-group metals can the plant recover?
The standard configuration recovers platinum, palladium and rhodium. Iridium and ruthenium are separated on request — iridium from the rhodium tail liquid by oxidation and coprecipitation, ruthenium by oxidative distillation of its volatile tetroxide — and osmium only in a dedicated fully enclosed circuit because its tetroxide is highly toxic. Gold and silver, where the feed carries them, are removed on the same line and finished on their own circuits.

Q4. Why does PGM recovery need a pretreatment stage at all?
Because the metals that matter most do not dissolve readily. Rhodium, iridium and ruthenium form kinetically inert aqua-chloride complexes and their higher oxidation states are difficult to reach, so a direct aqua regia or chlorination attack leaves part of the rhodium undissolved. Palladium can oxidise to palladium oxide (PdO), which is insoluble in both acid and alkali. During catalyst service, platinum-group metal particles also become encapsulated in alumina that has transformed at high temperature, and the carrier accumulates carbon and organics. Incineration, roasting, conditioning and acid washing remove those barriers before the main dissolution; skipping them simply moves the metal from the feed into the residue.

Q5. How is rhodium separated from iridium?
Rhodium is separated from iridium by ligand substitution, not simple precipitation. The sodium chlororhodate solution is adjusted to a rhodium concentration of the order of 50 g/L and a pH of about 1–1.5 with dilute alkali, then treated with a 25% ammonium sulfite solution at a volume ratio of roughly 1:0.75 and boiled with the pH controlled near 6.4. Rhodium precipitates as a milky-white ammonium trisulfite complex while iridium does not form a comparable precipitate and remains in solution. The rhodium compound is filtered, washed, redissolved in boiling concentrated hydrochloric acid to ammonium chlororhodate, converted through ammonia coordination and reduced with hydrogen to rhodium metal.

Q6. What recovery rate can the plant achieve?
Recovery runs above 99% for platinum and palladium and around 95% for rhodium on autocatalyst feed, with direct PGM recovery up to 99% on suitable material from about 5% PGM content upward. Rhodium is lower because part of it is bound in refractory phases that resist dissolution even after pretreatment. Published pilot campaigns on spent autocatalysts have reported the same pattern — above 99% for Pt and Pd and 95% for Rh over more than a thousand locked-cycle and pilot batch tests — which is why the plant treats raffinate, condensate, eluate and filter wash liquor as process streams that return to the circuit rather than as waste.

Q7. What purity can the recovered metals reach?
Pt ≥ 99.95%, Pd ≥ 99.95% and Rh ≥ 99.90% as standard products, with iridium and ruthenium recovered on request, and PGM salts supplied to specification where a buyer prefers chemical form. Purity is held by re-purification rather than by a single precipitation: repeated ammonium chloride precipitation and oxidative hydrolysis for platinum, complexation–dissolution–acidification cycling for palladium, and ammonium sulfite complexation followed by hydrogen reduction for rhodium.

Q8. How is the nitrogen oxide gas from PGM dissolution treated?
PGM dissolution produces the most concentrated nitrogen-oxide off-gas in precious-metal refining, typically of the order of 30,000 mg/m³. The reactor mouth is sealed and fitted with a hood, the vapour passes through a cold-water circulation condenser and gas–liquid separator, the metal-bearing condensate returns to the reactor, and the gas then enters a multi-stage jet-spray absorption tower with a non-oxidation tank and two-stage alkali neutralisation. Outlet concentration is held below 100 mg/m³, and the lowest achievable figure is below 20 mg/m³, with absorption efficiency of 99.5% or better. Collection smelting adds SO₂ and dust, which are captured in the same gas train.

Q9. What happens to the PGM that remains in the raffinate after solvent extraction?
It is recovered, not discharged. Solvent extraction is an equilibrium process rather than a one-way capture, so raffinate always carries residual platinum-group metals, untargeted metals and residual acidity. Ion exchange removes PGM chloro-complexes effectively at ppm-to-ppb concentrations under a selectivity order of Pd > Pt > Ir > Rh > Ru, and the eluate — a small, PGM-rich concentrate — returns to the refining circuit. Because rhodium loads weakly on chloride resins, dilute rhodium streams are first pre-concentrated by membrane separation so the resin loads efficiently; published membrane polishing figures show rhodium raffinate at about 3 mg/L being concentrated to roughly 36 mg/L with permeate below 1 mg/L. Scavenger precipitation is then used at campaign end or during off-spec operation to clean the circuit.

Q10. What PGM content should the feed have?
Direct separation and refining works from a PGM content of roughly 5% and above. Material below that grade is better pre-concentrated first — inside the plant, by incineration, roasting, selective leaching or collection smelting — because the cost of acid, reagents and reactor time per kilogram of metal becomes unattractive. Spent autocatalyst washcoat typically assays far below that threshold as received, which is exactly why a recovery and refining plant includes a concentration stage rather than starting at the reactor. During test work we will tell you where your material sits and which pre-concentration route is worth adding.

Q11. How long does a refining batch take and how many batches can run in parallel?
Dissolution typically runs 3–6 hours depending on feed type and particle size, with milled catalyst powder dissolving faster than dense bullion or sludge. The precipitation, complexation and reduction stages that follow are individually short but sequential, so the practical cycle is set by how many reactor, filtration and furnace trains are installed and by how many batches run in parallel. Silver and gold removal are fast single-step operations. Batch count and parallel trains are fixed at design review from your throughput target.

Q12. Is the process cyanide-free?
Yes. The standard route uses aqua regia, hydrochloric acid with chlorine as oxidant, nitric acid, sodium chloride, ammonium chloride, ammonium sulfite, sodium sulfite, hydrazine hydrate, formic acid and hydrogen — none of which involve cyanide salts. Alternative chloride and pressure-leaching routes are also available, and the plant is specified to operate without cyanide because that removes the most heavily regulated reagent class from the site and simplifies permitting and workplace safety.

Q13. What capacity range is available, and can it be expanded later?
The plant is modular. Configuration runs from bench and pilot trains for process development and small-batch work to industrial plants handling several tonnes of PGM-bearing feed per day, with the same process logic at every scale, so capacity is added by duplicating reactor, separation, polishing and treatment trains rather than by redesigning the chemistry. The right size and the expansion path are fixed at design review from your feed assay, metal load and batch frequency.

Q14. Should we recover and refine in-house or sell the concentrate?
In-house recovery and refining captures the full margin between raw PGM-bearing material and three finished metals, removes third-party refining charges and settlement delays, shortens the cash cycle and gives the operator control of its own assay and product certification. It also turns previously marginal material into feed worth processing, because a batch no longer has to justify an overseas shipment. Recovery rates above 99% for platinum and palladium and around 95% for rhodium from autocatalyst feed, together with published life-cycle figures of roughly 0.18 t CO₂ eq per kg of platinum, 0.47 t CO₂ eq per kg of palladium and 1.55 t CO₂ eq per kg of rhodium for integrated secondary refining, are the two benchmarks that normally settle the economic case — and the case itself is proved by a test-work-based mass balance on your own material.

Q15. What information is needed for a quotation, and what warranty and support are included?
For a quotation we need a representative sample or assay of your feed giving Pt, Pd, Rh and the main base metals; the material type and physical form, including whether the PGM is in ceramic, alumina, carbon or metallic form; the target throughput and batch frequency; the products and purity you want to sell; available floor area, headroom and utilities; and your local air-emission, wastewater and chemical-storage requirements. A sample and an assay are what let us confirm the route and the performance figures. The plant is then delivered turnkey with a standard 12-month warranty from commissioning, or 18 months from shipment, whichever comes first, covering material and workmanship defects with defective-part replacement and free remote support, backed by a guaranteed-performance clause confirming the contracted purity and recovery at commissioning. Delivery includes supervised installation, commissioning on your own feed, off-gas and dust emission verification, on-site operator training with full SOPs and a handover dossier, a 24-hour remote response commitment, stocked spares and consumables, and lifetime technical support after warranty expiry.

Platinum Palladium Rhodium Recovery & Refining Plant

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Frequently Asked Questions

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