How ALS2 Recovers Copper from Tin-Lead Coated Cable Scrap

Cable scrap is one of the most valuable streams in electronic waste, yet it carries a complication that recyclers across Sydney, Melbourne, and the Pilbara know well. The copper inside automotive harnesses, household wiring, and telecoms cable is almost always plated with a tin-lead alloy, and that metallic skin must come off before the underlying copper can be melted into specification-grade product. The conventional answer has long been hot aqua regia, nitric acid baths, or molten metal stripping with lead-laden dross. ALS2 offers a different pathway: an acidless electrochemical route that lifts tin and lead away from copper without producing the chlorine, nitrogen oxides, or acidic wastewater that have made legacy routes hard to permit in many jurisdictions.

For Australian operators, the timing could hardly be better. The country generates around twenty kilograms of e-waste per person each year, one of the highest per-capita rates in the OECD, and cable scrap makes up a sizeable share. State-based regulations in New South Wales, Victoria, and South Australia now require covered e-waste to be processed rather than landfilled, pulling volume toward dedicated recovery plants. Lead exposure controls have tightened, and downstream smelters that buy black copper are increasingly unwilling to accept feedstocks carrying residual solder.

The tin-lead coating is not just a nuisance, however, because both metals carry their own market value. Tin trades on the London Metal Exchange and feeds solder, tinplate, and lithium-ion anode chemistries. Lead, although restricted in consumer goods, still anchors lead-acid battery grids and radiation-shielding applications. A recovery process that simply discards the coating as sludge wastes those two revenue streams and adds a hazardous waste line to the plant's permit. ALS2 is designed with that dual-value logic in mind.

The technology has been developed under the European Union's Horizon 2020 research and innovation programme, with Ikoi S.p.A. coordinating the consortium behind the acidless separation route. The remainder of this article looks at how the system actually treats tin-lead coated copper wire, what falls out of each stage, and what Australian recyclers should know before considering a deployment.

Why Tin-Lead Coatings Challenge Conventional Copper Recovery

Tin-lead coatings on copper wire typically run one to eight microns thick on modern data and telephony cable, and considerably thicker, often fifty microns or more, on heavy-duty automotive and marine harness. The alloy is usually close to the eutectic composition of sixty-three percent tin and thirty-seven percent lead, chosen because it wets copper readily and resists thermal fatigue. From a metallurgical standpoint, that eutectic coating reacts strongly with oxidising acids, which is exactly why it has been stripped chemically for decades.

The trouble starts with the byproduct. Stripping tin and lead in nitric acid liberates copious volumes of nitrogen dioxide, a reddish-brown gas that Australian work health authorities treat as a serious respiratory hazard. Aqua regia, the other common route, releases chlorine and leaves behind a slurry of lead chloride and copper salts that has to be precipitated, filtered, and disposed of as hazardous waste. Both routes also dissolve some of the copper itself, reducing yield and contaminating downstream electrolyte.

Pyrometallurgical plants avoid the acid but pay for it with energy and emissions. Burning the polymer insulation off cable already produces dioxin precursors and brominated volatiles where flame retardants are present. Adding a thermal step to drive off solder creates a multi-emission source, complicating permitting in suburbs like those around the Eastern Creek or Dandenong industrial precincts. That is the gap ALS2 was built to close.

The Chemistry Behind Acidless Tin and Lead Stripping

Acidless separation rests on selective electrochemistry rather than bulk acid digestion. The cable feedstock is immersed in a benign aqueous medium held at a controlled pH, and a precisely tuned potential is applied across the cell. At that potential, tin oxidises first because its standard reduction potential sits well below copper's in the electrochemical series. Lead, lying between the two, enters solution inside a controlled window of operating parameters.

Copper, by contrast, remains untouched. The applied voltage sits below the threshold at which the underlying metal would start to dissolve, so the bulk copper keeps its mass, its conductivity, and its metallurgical history. Plant operators familiar with heap leach pads at sites around Mount Isa or Olympic Dam will recognise the principle: keep the potential inside the stability window of the metal you want to keep.

Tin and lead, once oxidised, migrate through the medium and plate onto dedicated cathodes. The cathodes are periodically harvested, washed, and cast into separate ingots, each metal ending up at purity levels that suit downstream refineries. Lead concentrates can be routed to Australian battery recyclers, where they re-enter the circular flow of lead-acid chemistry; tin concentrates feed back to solder manufacturers or specialty alloy producers.

Inside the ALS2 Process Flow for Coated Cable Feedstock

ALS2 bundles the electrochemical cell with the upstream and downstream steps that turn a laboratory reaction into a working plant. Coated cable arrives chopped, granulated, or as continuous strand, passes through size classification to remove fines and insulation dust, and feeds into the reactor as slurry or packed bed depending on configuration.

Process control is handled by continuous monitoring of the medium's conductivity, pH, and dissolved metal content. Sensor data feeds a supervisory controller that adjusts current density in real time. For a plant in Brisbane or Adelaide operating on intermittent feedstock, that responsiveness matters, because cable scrap composition drifts as ratios of automotive, telecoms, and residential wire change shift to shift.

After the acidless separation stage, solids are rinsed, dried, and passed to a furnace for casting into copper billets, rod, or shot. Recovered tin and lead, already separated at the cathode, require only a refining melt. The water circuit is largely closed, with polishing stages that keep dissolved metal concentrations inside the limits set by state environment protection authorities, a welcome contrast to the open rinse cycles of an acid line.

A safety management layer is one element that prospective operators ask about early. Personnel require training specific to electrochemical cells, and the architecture of the plant rewards operators who follow a structured framework. Ikoi has published a risk assessment framework that licence holders can adopt as a starting point for their own procedures.

Recovered Metal Quality and Environmental Footprint

The metals leaving an ALS2 line arrive in two clean streams. Copper comes out as bright, metallic solid with the coating gone, ready for melting without the lead contamination that can knock a batch out of specification at the refinery gate. Tin leaves the cathode as dendritic sheet that melts into 99.9 percent grade ingots under standard furnace practice, and lead arrives separately as a high-purity concentrate suitable for hard-lead alloys or battery feedstock.

The environmental footprint shrinks in three measurable ways. No chlorine, nitrogen oxides, or sulfuric fumes leave the cell, eliminating the gas scrubbing stack an acid line demands. No lead-laden acidic wastewater enters the trade waste consent, removing a compliance headache for utilities in cities as varied as Perth and Hobart where trade waste pricing has grown punitive. Energy use stays modest because separation runs near ambient temperature rather than at thermal-strip heat.

Side by side, the three processing routes can be compared on the dimensions that matter most to a plant operator deciding between retrofit and replacement.

Performance Area	Acid Leaching (Aqua Regia or Nitric)	Pyrometallurgical Stripping	ALS2 Acidless Separation
Primary reagent	Concentrated HCl plus HNO3, or HNO3 alone	Heat, sometimes with flux salts	Mild aqueous electrolyte
Tin output	Lost to sludge or recovered through precipitation	Captured in dross, mixed with other metals	Direct cathode plating, separate stream
Lead output	Precipitated as lead chloride, hazardous waste	Settled in dross with other heavy metals	Separate cathode stream, reusable
Copper loss	Several percent typical	Minimal but residual coating remains	Minimal, voltage-controlled selectivity
Wastewater profile	Acidic, metal-laden, requires treatment	Mostly clean scrubber condensate	Closed loop, polishing step only
Air emissions	Nitrogen oxides or chlorine, requires scrubbing	Dioxin precursors and particulates	Negligible at operating conditions
Operating temperature	Near ambient	Four hundred to seven hundred degrees Celsius	Near ambient
Indicative footprint	Large tank farm plus scrubber train	Furnace hall plus filtration equipment	Compact modular electrochemical cell

Documentation and reporting also become simpler. Plants supplying recovered copper under voluntary schemes, or feeding it into responsible sourcing audits, can point to a process flow without an acid-bound environmental management plan. For an Australian operator reporting under the National Greenhouse and Energy Reporting framework, the absence of combustion-based stripping makes the boundary cleaner and the audit trail shorter.

Scaling Acidless Separation in Australian Recycling Operations

Australia's cable recycling sector is split between large operators in Melbourne and Sydney who handle mixed WEEE and smaller regional players servicing mining, rail, and telecoms customers in places like Newcastle, Kalgoorlie-Boulder, and Townsville. The ALS2 architecture is modular, with reactor capacity scaled to host-site throughput, so the technology can be dropped into either a five-thousand-tonne urban facility or a five-hundred-tonne regional line without redesign.

Capital cost is competitive with mid-scale acid lines once gas scrubbing, effluent treatment, and hazardous waste handling are included. The compact footprint also suits sites where land is constrained, a familiar story around inner Brisbane or Port Melbourne where existing leases leave little room for new tank farms. Horizon 2020 backing, which has supported ALS2's development, carries weight with Australian lenders and ESG-focused investors familiar with the programme's due diligence, which simplifies conversations around green finance and sustainability-linked loans. The remaining work is site-specific: integrating ALS2 into the existing cable line, training the operations crew, and aligning the safety case with state work health regulations.

If you are sizing a recovery plant, weighing acid-line replacement, or evaluating whether coated cable feedstock can support a higher-grade copper product, the ALS2 consortium can share engineering data, mass-balance models, and reference case studies. Reach out through the project site to start a conversation about deployment, integration, or partnership with Ikoi S.p.A. and its research partners.