ALS2 silver recovery from industrial sensor diaphragms
Australia’s industrial controls market creates a narrow but valuable recycling stream. Pressure sensors are installed in mine slurry lines, water treatment plants, food and beverage factories, chemical dosing skids and transport assets, yet many are replaced long before the surrounding machinery reaches retirement. Sensors removed during upgrades can include silver-bearing diaphragms, with the precious metal present as a thin coating or contact layer depending on the model. ALS2 for silver recovery from pressure sensor diaphragms in industrial controls therefore starts with a clear objective: capture valuable metal before a mixed electronic-waste stream dilutes it.
Ikoi S.p.A.’s ALS2Project presents acidless separation as a safer, cleaner alternative to conventional acid-based refining. Supported by the European Union’s Horizon 2020 research and innovation programme, the project is developing technology and compact plant concepts for recovering precious metals from electronic waste and WEEE streams. Its relevance to industrial controls lies in turning a dispersed collection of small components into a concentrated feed suitable for metal recovery without relying on the corrosive liquid circuits associated with traditional leaching.
The opportunity is substantial but frequently overlooked. A pressure sensor diaphragm may contain only a small amount of silver, and that silver can be difficult to identify through visual inspection. Diaphragms are also combined with seals, weld material, solder, circuit boards, oils and process fluids, so an entire failed instrument is not automatically suitable for precious-metals refining. Sensible pretreatment and representative sampling are needed before any commercial recovery rate or processing cost can be claimed.
A practical Australian pathway would connect equipment manufacturers, maintenance contractors, industrial operators, accredited samplers and licensed recyclers. The resulting silver-bearing stream could then move to a compact separation facility and, finally, to a specialist refiner. This integrated approach makes more sense than sending pressure sensors through general WEEE processing, where their small size and mixed construction work against efficient material recovery.
| Consideration | ALS2 acidless separation | Conventional acid-based refining |
|---|---|---|
| Core process | Uses an acidless separation route rather than mineral-acid leaching | Uses acids to dissolve and concentrate metals |
| Plant format | Compact modular concept suited to targeted recovery streams | Often requires larger corrosion-resistant process equipment |
| Environmental profile | Intended to reduce corrosive liquid waste and handling risks | Can generate acidic solutions, neutralisation salts and metal-bearing sludge |
| Feed requirements | Benefits from sorted, pretreated and consistently characterised material | Can process broader feeds but demands strict chemical controls |
| Outputs | A precious-metals fraction plus residues that still require testing | Refined metal products alongside liquid and solid waste streams |
| Commercial readiness | Supported by EU research and requiring application-specific validation | Established supply chains and widely understood operating practices |
Why pressure sensor diaphragms are a targeted feed
Control-system replacement work can create an unusually traceable collection stream. Maintenance records often identify pressure transmitter models, manufacturers and installation dates, allowing recyclers to separate likely silver-bearing units from unrelated electronics. This traceability is more valuable than the nominal silver grade alone because it reduces the sampling and sorting burden that normally makes small electronic components uneconomic to process.
Not every diaphragm contains commercially recoverable silver. Some use solid stainless steel or other alloys, while others incorporate plated or metallised layers that differ in thickness and composition. An accredited laboratory should use an appropriate method, such as ICP analysis or fire assay, to establish silver content and identify contaminants. Without that evidence, a stream described as “silver-bearing” may contain too little precious metal to support a viable recovery campaign.
Removing and preparing diaphragms separately also protects the wider recycling operation. Circuit boards, plastics and potentially contaminated process fluids require their own treatment routes. Once instruments have been safely isolated, depressurised and drained under an approved procedure, controlled dismantling can direct the diaphragm material toward metal recovery while the remaining parts continue through conventional e-waste and component-recycling streams.
Where ALS2 fits in an Australian recovery loop
Australia’s geography makes feed logistics decisive. A failed pressure transmitter from a Pilbara pump station may travel hundreds or thousands of kilometres before reaching a workshop in Perth or another processing hub. Operations crews commonly talk about “chucking out” a failed instrument and “getting it back on the tools”; commercially, that informal process can place complete transmitters, valves and unrelated controls into the same collection bin. ALS2 needs a cleaner separation boundary than that.
Concentrated opportunities exist around maintenance centres in Melbourne, Adelaide, Perth, Brisbane and Newcastle, as well as at mines, water utilities and manufacturing plants undergoing major upgrades. Rather than gathering scattered waste from individual sites, a buyer could work with industrial contractors to secure complete batches at scheduled shutdowns. Engineering notes on pressure sensor diaphragm fundamentals can also help maintenance teams identify the relevant component before it is mixed with other equipment.
A second local consideration is the separation between equipment owners and recycling markets. Victorian manufacturers and water authorities often hold substantial installed control systems, while NSW, Queensland and other jurisdictions operate distinct e-waste collection and reporting arrangements. A national ALS2 offer still needs a locally compliant collection partner, transport plan and clear definition of which organisation owns the recovered material at each stage.
Engineering a compact, safe separation plant
Pretreatment should be conservative because industrial pressure sensors may have contacted hydrocarbons, chemicals, food products or compressed gases. Instruments should be removed from service, isolated, depressurised and drained by qualified personnel. Electronic assemblies and seals can then be separated under controlled conditions, with diaphragm-bearing material prepared using methods validated for its construction.
The ALS2 stage would sit between this preparation work and final metal finishing. Its role is to separate and concentrate the silver-bearing fraction without making the plant dependent on a conventional acid-leach circuit. Equipment selection must match the actual feed chemistry, silver grade and required throughput rather than relying on a generic processing design. A modular configuration would allow a pilot line to expand if the results support a larger compact recovery plant.
Water, energy and residue performance need to be demonstrated together. Acidless operation can reduce corrosive handling, but it does not remove the need for sound engineering. Process liquor, wash water, filters and unrecovered solids must be characterised, and their legal classification should be confirmed before the plant handles commercial material. A credible mass balance should show where silver enters, how much is recovered and which approved route receives every remaining stream.
Australian sites also need room for safe receiving, quarantine and residue storage. A facility near an industrial estate with established waste connections may be more practical than a remote site close to the source, especially once transport, labour and power are included. Containerised equipment could support staged deployment, provided that drainage, ventilation and hazardous-area requirements are assessed for each industrial location.
Economics, regulation and buyer expectations
Silver value makes recovery attractive, but it cannot be assessed without representative assays. The commercial calculation must account for collection, dismantling, analysis, transport, ALS2 processing, final refining and residue management. A clean feed with a verified grade may outperform a larger volume of dilute material, particularly where freight distances are substantial. This makes source segregation and reliable sampling the foundation of the business case.
Regulation will vary by jurisdiction and by the condition of the material. Pressure sensors may be classified as waste electrical and electronic equipment, while contaminated residues or process fluids could attract additional controls. Operators should check state and territory requirements, maintain auditable transfers and use licensed carriers where applicable. Export restrictions and chain-of-custody expectations also need consideration if the silver-bearing fraction is sent to an overseas refiner.
Potential buyers include specialised precious-metals refiners, industrial sensor distributors and manufacturers with closed-loop recovery objectives. They will expect a stable specification, assay certificates, documented recovery performance and clear responsibility for non-metallic outputs. The ALS2Project’s compact approach fits this market when it can deliver a consistent intermediate product rather than relying on an unverified claim of pure silver output.
Start with a measured Australian pilot
A useful pilot would begin with a defined batch of segregated diaphragm-bearing material and a documented mass balance. The feed should be sampled by an accredited laboratory, while operators record component weights, contaminants and the handling steps required to separate them safely. This approach tests commercial assumptions as well as technical performance.
The pilot should report silver feed grade, recovery percentage, water and energy consumption, reagent requirements, residue quantities and total processing cost. It should also test whether maintenance contractors can reproduce the sorting process under ordinary Australian industrial conditions. Without those measures, an impressive laboratory result can still fail to support a viable regional plant.
The immediate action is to bring Ikoi S.p.A. and the ALS2Project team a representative Australian feed sample, supplier contacts and information on local transport and e-waste rules. A controlled trial with verified outputs, documented residues and transparent economics would give Australian industrial partners the evidence needed to build a compact silver-recovery operation around ALS2.