Gold Recovery from Gold-over-Nickel RF Shielding Cans

Radio-frequency shielding cans protect sensitive electronics from electromagnetic interference. Their contact surfaces often carry a very thin gold-over-nickel finish over copper or brass, combining corrosion resistance with reliable electrical performance. Because these components are frequently nested inside larger assemblies, their precious-metal content can be overlooked during routine waste sorting.

Conventional acid treatment can dissolve the nickel underlayer or base metal along with the gold, increasing reagent consumption and creating liquid residues that require careful management. ALS2Project is developing an acidless separation approach intended to recover precious metals from electronic waste and WEEE more cleanly, with support from the European Union’s Horizon 2020 research and innovation programme.

The treatment of gold-over-nickel finishes requires attention to coating structure, feed preparation and metal selectivity. For Australian electronics manufacturers, repair networks, e-waste contractors and urban mining operators, that means combining appropriate pre-treatment with a compact recovery process and a transparent route for the remaining metals.

Why RF Shielding Cans Matter

RF shielding cans are used in telecommunications equipment, industrial controls, medical devices, automotive electronics and security systems. Sydney and Melbourne host substantial telecommunications, data-centre and advanced-manufacturing activity, while Adelaide and Canberra have aerospace, defence and government technology supply chains. Even a modest number of discarded assemblies can therefore create a concentrated stream of high-value shielding components.

A typical can contains much more copper or brass than gold. The economically important feature is the selective coating, commonly gold over nickel, applied to selected surfaces for solderability, wear resistance and stable conductivity. Gold may represent only a small proportion of the component’s mass, yet its value per kilogram can justify dedicated recovery when the cans are separated before shredding.

These parts are also easy to miss in mixed WEEE. They may be attached to circuit boards, enclosed in housings or discarded after an equipment upgrade. Collecting them at equipment refurbishment, maintenance or controlled dismantling stages preserves cleaner material and reduces the sorting burden faced by general recyclers.

The Gold-over-Nickel Treatment Problem

The principal difficulty is the layered nature of the finish. The gold layer can be extremely thin, while the nickel beneath it may react readily under acidic conditions. Treatment must therefore distinguish between a precious-metal surface and the underlying barrier without losing efficiency to excessive chemical consumption.

A conventional acid leach may dissolve nickel, copper or brass along with gold. That behaviour can increase salinity in the process liquor, complicate downstream metal recovery and transfer contamination into what should be a concentrated gold-bearing fraction. It also creates additional handling requirements for acidic solutions and the residues generated during neutralisation.

Mechanical separation alone offers another challenge. Abrasion may expose the coating, but it can also mix gold particles with nickel and base-metal fragments. Effective treatment depends on controlled pre-treatment, representative sampling and a selective separation stage. The objective is a high-value precious-metal fraction alongside a nickel- or copper-bearing residue that can enter a more appropriate metal-recycling stream.

Preparing a Feed for High-Value Recovery

The first step should be controlled dismantling rather than immediate size reduction. Non-metallic seals, fasteners, plastic inserts and circuit-board attachments should be removed where practical. Intact cans are easier to identify and assay, while early shredding can blend gold-over-nickel parts with unrelated alloys and lower the concentration of recoverable material.

After dismantling, the cans can be sorted by construction and coating type. Some use gold over nickel on copper, while others contain different base metals or plating combinations. Magnetic, optical, density and X-ray fluorescence screening can support this stage, although laboratory assay remains necessary for commercial decisions and process control.

A suitable pre-treatment method may use controlled abrasion, brushing or another delamination process to separate or expose the valuable coating. The selected method must avoid excessive loss of gold and prevent cross-contamination between batches. Each resulting stream should then be weighed and sampled so that operators can measure metal distribution rather than relying on visual estimates.

Applying Acidless Separation Technology

ALS2Project’s approach centres on avoiding the bulk acid-leaching stage associated with conventional hydrometallurgical refining. In a treatment train for shielding cans, mechanical or thermal-assisted pre-treatment would prepare a concentrated gold-and-nickel fraction for the project’s acidless separation stage. The aim is to recover the precious metal while keeping the base-metal residue distinct.

Acidless does not mean chemical-free or impact-free. Process media, energy, rinsing and waste management remain important design considerations. The value lies in reducing reliance on aggressive acid circuits, improving selectivity and lowering the burden associated with dissolved nickel and base metals. Closed vessels, captured rinse water and suitable off-gas treatment would still be required for a safe commercial installation.

A modular plant could combine sorting, pre-treatment, separation, precious-metal recovery and residue conditioning in one controlled flow. Process parameters must be established through representative testing, including examinations of reagent consumption, recovery efficiency and the fate of nickel. The ALS2Project research programme provides a technical foundation for evaluating these options before full-scale deployment.

Designing a Compact Plant for Australia

Compact installations are particularly relevant to Australian cities, where industrial land is expensive, traffic congestion affects logistics and waste-storage space is limited. A facility near an electronics manufacturing precinct or authorised collection hub could process shielding cans without transporting low-density component waste across long distances. Regional depots could use the same modular equipment before consolidating recovered fractions.

Western Australia’s nickel-mining sector and Perth’s gold-refining ecosystem create a distinctive local market. Nickel-bearing residues may have value when their chemistry meets smelter specifications, while recovered gold can be directed to established refiners. The presence of both materials also raises a technical risk: nickel contamination can reduce the value of a gold fraction, making accurate sorting and residue treatment central to commercial performance.

Environmental requirements also vary across states and territories. Australia’s National Waste Policy supports improved product stewardship, but operational e-waste programs, retailer obligations and approved collection routes differ by jurisdiction. Commercial generators should confirm whether shielding cans qualify for a funded e-waste stream or require an authorised contractor. Storage, transport and treatment may also be regulated through state environmental legislation.

These differences favour a documented chain of custody. A national electronics company should be able to identify the jurisdiction generating the component, the licensed party receiving it, the treatment route and the destination of both precious-metal and base-metal outputs. The same clarity helps suppliers demonstrate responsible procurement and prevents valuable components from entering mixed general waste.

Turning a Recovery Stream into Circular Supply

Recovering gold does not automatically make the original shielding can reusable. RF performance depends on electrical continuity, surface condition and the integrity of the shielding enclosure. If a can is to return to manufacturing, its remaining coating and attenuation performance must be tested against the relevant specification. Parts that fail that assessment should follow the metal-recovery route.

Verification should cover more than gold recovery percentage. Operators should record nickel carry-over, reagent consumption, water use, waste volume, energy demand and the chemical composition of final residues. These metrics demonstrate whether a compact treatment system delivers the environmental and commercial gains expected from separating gold-over-nickel finishes before destructive processing.

The wider benefit is a more traceable urban-mining supply chain. Precious metal returns to approved refiners, while copper, brass or nickel residues can be assessed for suitable industrial recovery. Shell parts and mixed electronic scrap can then be directed to established WEEE facilities. This separation of materials preserves value at the highest available level and supports better reporting for manufacturers seeking circular, low-impact material cycles.

Organisations that service RF-shielded equipment, dismantle electronic products or operate e-waste collection depots can engage ALS2Project to discuss feedstock trials and acidless recovery opportunities. A representative batch of gold-over-nickel shielding cans can help establish coating composition, metal distribution and the most suitable treatment configuration.

Turning RF shielding cans into a dedicated recovery stream can recover scarce precious metals, reduce mixed-waste processing and strengthen Australian circular-economy supply chains. Contact ALS2Project to begin a practical assessment of shielding-can feed and compact plant deployment.