How ALS2 recovers gold from motor brush contacts

Brush contacts are among the least visible sources of precious metal in electric motors. They sit inside brushed DC motors, where carbon blocks or copper-backed contacts carry current between the rotor and stationary brush holders. Gold may be present as a surface coating, a gold-copper alloy or a brazed contact layer. These small components also contain copper, graphite, steel springs, insulation and residues from decades of service.

Ikoi S.p.A.’s ALS2Project is developing an acidless separation route for recovering precious metals from electronic waste and WEEE recycling streams. The central aim is to avoid reliance on the concentrated mineral-acid and aqua-regia refining traditionally associated with metal recovery. Support from the European Union’s Horizon 2020 research and innovation programme has supported the project’s development and assessment as a safer, cleaner processing option.

For Australia, the opportunity extends beyond consumer electronics. Motors from power tools, appliances, industrial machinery and vehicles reach workshops, demolition sites and e-waste facilities throughout the country. ALS2 could give recyclers a way to concentrate and recover gold from a dispersed, low-grade stream while reducing the handling of aggressive acids. Local feed composition, transport distances and residue regulations still need to be addressed before commercial deployment.

From mixed motors to a valuable feed

A motor arriving at an e-waste processor may contain several recoverable materials alongside the brush assembly. Steel casings, magnets, copper windings, cables, lubricants and insulation must be separated before any gold-bearing material can be processed efficiently. Dismantling the motor under controlled conditions prevents the entire machine from being shredded into a diluted metal concentrate.

Brush contacts can often be removed with limited destructive processing. Where practical, the commutator and brush components are separated from the steel frame, then inspected and sorted. Motors without recoverable brush contacts can follow established recycling routes, while units containing visible gold-rich contact surfaces create a stream worthy of separate treatment.

Sorting is based on value rather than weight. A few kilograms of contact material can be more valuable than a much larger quantity of mixed plastic, so processors benefit from removing obvious non-metallic contamination early. The resulting feed may contain graphite blocks, copper braids, spring steel and small amounts of gold-bearing alloy. Its value depends on gold grade, condition and the proportion of non-precious material carried into the separation stage.

Liberating gold-bearing material

The first liberation stage reduces brush contacts and related commutator fragments to a controlled particle size. Crushing, milling or granulation exposes surface coatings and separates composite pieces without smelting the motor. The objective is to release gold-bearing particles while preventing fine graphite and copper dust from becoming an uncontrolled loss stream.

Screens and classifiers then divide the material according to size and density. Magnetic separation can remove steel springs and ferrous fragments, while gravity-based or air-assisted sorting may reject lighter carbon and plastic. Copper-rich pieces can also be separated for conventional metal recycling. Fine particles remain important because some of the gold may have detached from the contact surface during service or size reduction.

These steps create a smaller, more consistent concentrate for ALS2 rather than attempting to extract gold from the original mixed motor. Feed characterisation remains essential. Representative sampling and assay results establish gold content, identify contaminants and show whether physical concentration is sufficient or whether chemical selectivity is required for the remaining material.

The core acidless separation

ALS2’s core concept is to recover gold without using conventional acid baths as the primary refining medium. Acidless does not mean chemistry-free or impact-free. It means that the separation strategy is designed around a controlled chemical route with a reduced dependence on highly corrosive, acid-intensive conditions.

During separation, the prepared concentrate is subjected to a carefully managed process that selectively transfers gold into a recoverable phase. The operating window must control factors such as reagent concentration, temperature, contact time and solid-to-liquid ratio. These controls are important because gold may occur in coatings, alloys or discrete particles, and each form responds differently to selective extraction.

After contact with the separation medium, the solid and liquid fractions are separated by filtration, centrifugation or another engineered separation step. Gold-bearing solution or captured material proceeds to metal recovery, while copper, graphite, steel and other base-metal residues are directed for further treatment. The purpose is not to assume that every unwanted element follows one simple path; each residue stream must be characterised before reuse, recycling or disposal.

The safety case comes from reducing acid demand and the associated risks of corrosion, splashing, fumes and worker exposure. A well-designed installation still requires closed handling, monitoring, personal protective controls and documented waste procedures. Lower chemical severity does not remove the need for occupational safety and environmental compliance.

Gold finishing and residue stewardship

The gold-bearing fraction is converted into a concentrated intermediate and then into metallic gold through controlled finishing steps. Depending on the validated flowsheet, this may involve selective precipitation, chemical reduction or electrodeposition. The resulting material can be washed, dried and formed into granules or an ingot for assay and subsequent refining. Readers comparing hydrometallurgical routes can use this acidless separation background as broader technical context.

Residue management is integral to the commercial case. Filter cake and other solid outputs may contain copper, nickel, lead, tin, graphite and residual gold. Their composition changes with the original motor stream and the separation settings. Processors therefore need reliable sampling, metal recovery records and an approved destination for every residue produced.

Water use, energy demand and chemical consumption must be measured alongside recovery. Closed-loop rinsing and recirculation may reduce the volume of liquid requiring treatment, while recovered base metals can improve the value of the remaining stream. Environmental claims should still be supported by plant data, including independent checks on liquid effluent, airborne emissions and solid residues.

Australian conditions that shape the opportunity

Sydney and Melbourne generate substantial quantities of household e-waste through appliance replacement, home renovation and the accumulation of tools in domestic garages. Council resource-recovery centres and specialist recyclers collect televisions, small appliances and batteries, while trade-in and second-hand platforms keep some electrical equipment in use for longer. Even so, every replacement and discarded tool eventually adds motors to the recovery stream.

Australian e-waste regulation is administered mainly through state and territory systems rather than a single national container-deposit program for electrical products. NSW, Victoria, Queensland and other jurisdictions combine different producer, retailer, recycling and disposal obligations. Commercial processors moving equipment between states need to confirm the applicable rules and use destinations with the required approvals.

Industrial demand creates another Australian feedstock. Western Australia’s mining sector, Queensland’s processing facilities, and manufacturing, logistics and building-services networks across Melbourne and Sydney operate large inventories of pumps, fans, conveyors, machine tools and maintenance motors. Many of these machines use brushed designs and can contain decades of accumulated precious-metal contacts.

The shift toward electric vehicles should be treated carefully. Most traction motors in modern battery-electric vehicles are brushless and do not contain commutator brushes. However, legacy household appliances, power tools, servomotors and industrial equipment remain in operation, while hybrid systems can combine electronic controls with conventional brushed components. ALS2’s addressable feed therefore depends on collection and motor classification, not simply the growth of electric vehicles.

Building a compact commercial plant

ALS2 is intended for compact precious-metals recovery plants located near e-waste collection hubs or specialist motor-processing facilities. A smaller plant can process concentrated brush-contact material without treating entire motors. This approach reduces transport costs for bulky scrap and helps economic performance when gold grades are modest and Australian logistics expenses are measured in Australian dollars.

Commercial operation depends on predictable feed and verified process performance. Gold content varies significantly between motor types, and a laboratory result cannot establish the performance of an urban plant. Operators need metallurgical test work, mass balances, independent assays and long-term data covering reagent consumption, water treatment, residue quality and recovered gold value.

The Horizon 2020 programme has provided a foundation for testing the technical and environmental proposition. Australian deployment now requires local feedstock trials, regulatory review and comparison with existing smelting, refining and hydrometallurgical routes. Decisions should consider worker safety, permitting, logistics, residue treatment and exposure to gold-price movements alongside simple percentage-recovery figures.

Bring a representative motor stream into the ALS2 trial

Australian e-waste processors, motor remanufacturers and recycling companies can begin by separating likely brush-contact material from mixed motors. A representative batch should be characterised for gold grade, base metals, particle size and contamination before a pilot is designed. The trial should compare ALS2 with the operator’s current route using measured recovery, chemical use, water demand, labour requirements, residue volume and total cost.

The next step is to contact Ikoi S.p.A. and the ALS2Project consortium for the available technical package, trial protocol and compact-plant configuration. A well-characterised brush-contact stream combined with a measured local pilot offers the clearest route from ALS2’s research promise to an Australian precious-metals recovery operation.