Recovering rhodium from thermocouple wire scrap with ALS2
Rhodium recovery from thermocouple wire scrap can turn a low-volume industrial residue into a valuable secondary resource. The material appears in temperature sensors used across furnaces, kilns, laboratories, power facilities and heavy process plant. Its precious-metal content is attractive, while its small size, mixed construction and dispersed origins make collection and sorting unusually difficult.
Not every thermocouple contains rhodium. Type K leads, for example, usually use nickel-chromium and nickel-silicon alloys, while platinum-rhodium Types S, R and B do. Recovering rhodium therefore begins with identifying the alloy rather than treating a random bundle of wire as a single rhodium-bearing feed.
ALS2Project presents an acidless separation route developed around Ikoi S.p.A.’s cleaner processing concept. Support from the EU’s Horizon 2020 research and innovation programme adds credibility, but commercial use still depends on assays, controlled trials and evidence for the specific alloy, contamination level and scale involved. For Australian businesses, that evidence is the bridge between an interesting chemistry and a bankable recovery plant.
A compact installation could suit regional aggregation hubs, specialist reclamation businesses and licensed waste operators. It could also give manufacturers and maintenance contractors a practical way to retain value that would otherwise disappear in mixed electronic-waste and waste electrical and electronic equipment (WEEE) streams. The strongest case combines verified feedstock, secure logistics, transparent mass balances and a buyer ready to pay for refined metal.
Why rhodium matters in spent thermocouples
Thermocouples are safety and control devices, so many are removed when equipment is retired or replaced. Scrapped assemblies may contain platinum-rhodium contact wire, stainless-steel or copper connection leads, ceramic insulation, mineral insulation, brazing filler and oxides. Once separated from service, those pieces are easy to overlook because a kilogram of finished sensors may carry far less actual rhodium-bearing metal than a shipment of ore concentrate.
Rhodium’s industrial value comes partly from its resistance to corrosion and oxidation at high temperature. It is also scarce and expensive, which makes careful recovery economically attractive. Yet price alone does not guarantee a viable project: recovery grade must cover assay, collection, processing, transport, refining and residue treatment without creating losses that erase the margin.
The ALS2 proposition is particularly relevant here. An acidless process can reduce dependence on aggressive acid circuits for suitable feeds and may fit a smaller plant footprint. It should not be treated as a claim of zero impact. Reagent handling, solid residues, energy demand, worker exposure and final metal purity still need to be demonstrated under Australian operating conditions.
Identify the right thermocouple scrap
A reliable feedstock map should record thermocouple type, supplier, service history and whether the material is bare wire, a lead assembly or a complete removed probe. Non-destructive analysis can screen large batches, while laboratory assay is needed to confirm rhodium and platinum values. This step prevents dilution with Type K wire and identifies material that is too dirty or too fine to process economically.
Appearance cannot replace analysis. Two conductors may look alike while carrying different alloy fractions, and heat-affected wire can be coated, welded or oxidised. Platinum-rhodium Types S and R commonly pair platinum with alloys containing about 10% or 13% rhodium on one leg, while Type B uses different Rh-bearing grades. A practical sorting habit is to treat each batch as a unique fingerprint, much as tea flavour profiles show that two visually similar samples can have different underlying character. The comparison is an analogy, but the lesson is sound: sort, sample and document before committing capacity.
Removing ceramics and non-metallic insulation is essential. Metallic sheaths, cores and supports must also be separated or accounted for in the final mass balance. Small quantities can be consolidated from hospitals, test laboratories, food processing, aerospace suppliers, foundries, mining workshops and process-control firms. Records tied to equipment numbers and removal dates can improve traceability and help a collector verify that material came from a thermocouple rather than mixed manufacturing scrap.
Stage the ALS2 separation process
A practical ALS2 evaluation can be divided into five linked workstreams: feedstock preparation, conditioning, selective separation, metal finishing and residue verification. Wire may need cutting or granulating to expose the alloy and reach a consistent particle size. The selected condition should then be tested against a representative mass, with every input and output weighed and sampled.
Selective separation is the heart of the case for ALS2. The process is intended to recover precious metals without relying on the aggressive mineral-acid leaching used in some conventional refining flows. For a platinum-rhodium feed, the technical challenge is to show that rhodium follows the intended product stream while platinum, base metals and contaminants report elsewhere. Testwork should measure those splits rather than rely on visual colour or a single bulk assay.
Finishing and reconciliation are where commercial claims become numbers. Recovered material needs purity suitable for a refinery or metal trader, while residues require sampling for unextracted rhodium. The project should report input metal, recovered metal, recovery percentage, reagent consumption, energy use, water demand, labour and final residue value. A compact skid can then be sized from real batch data instead of an optimistic spreadsheet.
ALS2Project’s work under Horizon 2020 provides a European development base for this approach. Australian deployment would still require local validation, regulatory review and clear arrangements for any imported technology or chemical. A successful pilot should leave behind an operating protocol, an assay trail and enough operating data for an independent engineer to evaluate scale-up.
Fit the route to Australian markets
Australian demand is geographically spread. Pilbara mining operations, Hunter Valley preparation plants, Kalgoorlie workshops and Melbourne manufacturing sites all use temperature instrumentation. The scrap may be modest at each site but valuable when several streams are combined. General e-waste shredding often disperses or loses small sensor components, making source segregation more valuable than bulk collection. Many buyers also price material by assay and tender terms rather than by the original equipment label.
Local purchasing habits favour a practical trial before a large commitment. Procurement teams can ask for a defined feed parcel, a mass balance and a sensitivity model, then compare the result with the value of the contained metal. That “small test first” mindset is the same disciplined logic behind beginner gaming basics: understand the rules, limit the initial exposure and check the outcome before scaling up. For a fair-dinkum feasibility test, recovery costs also need to stack up against local wages, freight and waste-disposal charges.
Regulation and logistics vary across states and territories. Transporters, waste classification, licences, chain-of-custody records and residue handling must be checked for each site and route. Australia’s national e-waste product stewardship work supports better recovery systems, but a stand-alone industrial thermocouple may not sit within every covered electronics category. Keeping the material identified and documented from collection through final sale reduces compliance risk and the chance of contamination.
Compare operating and commercial outcomes
No process is universally superior. Acid-based refining is mature and can offer high throughput for suitable feeds, whereas ALS2’s potential advantage is lower acid dependence, safer separation conditions and modular deployment. The comparison below is a decision framework rather than a substitute for pilot data; reagent identity, feed composition and local treatment costs still determine the result.
| Consideration | Acid-based refining | ALS2 separation route | Evidence for an Australian project |
|---|---|---|---|
| Feedstock | Mature processes can handle concentrated, homogeneous feeds | Suited to targeted separation of sorted feed; selectivity between rhodium and platinum must be proven | Head grades, impurity profile and trial mass balance |
| Chemical system | Often uses mineral acids, oxidants and corrosion-resistant equipment | Designed around acidless separation with lower acid dependence | Reagent inventory, compatibility and safety data |
| Plant configuration | Throughput and economies of scale can favour a large central refinery | Modular equipment can suit a compact precious-metals recovery plant | Capacity, capital cost, labour and shift pattern |
| Environmental profile | Mature controls, but acid, gas and residue management can be demanding | Potential lower acid-corrosion burden, while residues and exposure still require assessment | Water, energy, emissions, waste classification and protective equipment |
| Commercial position | Established refining and offtake networks | Emerging project-backed route requiring Australian validation | Refinery acceptance, payment terms and scale-up risk |
The most persuasive evidence would be side-by-side data from the same sorted thermocouple stream. At minimum, record rhodium recovery, product purity, residue loss, water and energy consumption, working-hour exposure, waste volume and total cost per contained gram of rhodium. Australian industrial buyers will respond better to a measured cost and safety case than to a broad claim that one route is simply cleaner.
Build the feedstock chain before the plant
A rhodium recovery venture should be built backwards from an actual stream of metal. Secure several suppliers, define what will and will not be accepted, assay representative batches and test the route before purchasing a full skid. A small Australian demonstration can then produce the operating history needed for finance, regulators and a refinery partner.
Contact ALS2Project and Ikoi S.p.A. to scope a thermocouple-wire trial, partner with an accredited Australian assay laboratory and qualified metallurgical contractor, and obtain a feed-specific recovery and cost model. Move now to identify a pilot parcel, assign chain-of-custody responsibility and schedule the first controlled ALS2 test; the evidence gathered there will determine whether a compact Australian rhodium recovery plant can become a dependable circular-metal business.