Recovering palladium from glass-bonded mica capacitors with ALS2

Capacitors might be small, but the precious metals packed inside them are not. Glass-bonded mica capacitors in particular carry a dense layer of palladium, a metal whose spot price regularly outpaces gold on a per-gram basis. Across the world, electronic waste has become one of the fastest-growing waste streams, and the fraction hiding in industrial and military-grade circuit assemblies is among the richest urban ore available today. Recovering that palladium cleanly, at industrial scale, is a puzzle the ALS2 project has been engineered to solve.

Australia generates more than 600,000 tonnes of e-waste a year, according to the most recent National Waste Report, and only a small share of that material is currently processed onshore. The federal ban on e-waste exports, introduced in 2019, has pushed councils from Brisbane to Bunbury to look for local processing options that can actually handle complex, multilayered scrap. Capacitor banks pulled from older industrial control gear, defence communications equipment, and decommissioned rail signalling systems often sit in stockpiles because the metallurgy involved is fiddly. ALS2 was developed with exactly that kind of mixed, hard-to-treat scrap in mind.

The technology comes out of Ikoi S.p.A.'s acidless separation line, with backing from the European Union's Horizon 2020 programme. Instead of dousing shredded capacitor scrap in aqua regia or cyanide-bearing lixiviants, ALS2 uses a sequence of mechanical, thermal, and electrochemically driven steps that leave the precious-metal fraction intact and recoverable without the usual acid handling risks. The result is a process that slots into the kind of compact, containerised plants Australian operators have started rolling out at places like the Kwinana industrial strip and the Wetherill Park resource recovery cluster.

This article walks through how the ALS2 process specifically targets palladium trapped inside glass-bonded mica housings, why the chemistry works the way it does, and what that means for refineries, recyclers, and equipment manufacturers operating in Australian conditions. It also looks at how the recovered metal compares with what acid-based routes can deliver, and where the technology is likely to fit in the coming decade.

The capacitor challenge

Glass-bonded mica capacitors are workhorses in high-frequency and high-voltage circuits. They turn up in radio transmitters, radar modules, medical imaging hardware, and a fair slab of Australia's ageing industrial control infrastructure. Each unit is built by pressing fine mica splittings into a layered dielectric, then sealing the stack in a thermoset glass binder. The internal electrodes, along with the termination layers that bond to the outside leads, are typically loaded with palladium or palladium-silver alloys.

The reason palladium is used comes down to its stability. It does not tarnish, it tolerates heat, and it holds its conductivity across decades of service. The trade-off is that, once a capacitor is decommissioned, the palladium is effectively locked inside a glass-ceramic sandwich that is highly resistant to mechanical separation. Standard shredding leaves a fine, silvery powder that is hard to sieve and harder to leach without aggressive reagents. Most secondary smelters in this country ship this kind of material offshore, where it ends up in long-haul refining chains that often rely on aqua regia or cyanide-based dissolution.

For Australian processors, that offshore dependency is increasingly uncomfortable. Each container of capacitor scrap that leaves Port Botany or Fremantle represents a lost opportunity to recover a critical mineral locally, and the freight alone is enough to eat into margins. Recovering palladium from these housings at home is therefore both an economic and a strategic question.

Why acidless separation matters for Australian refiners

Acid-based refining has a long track record, but it carries well-known headaches. Aqua regia produces nitrous fumes that require scrubbing, while cyanide circuits demand absolute containment, double-liner ponds, and rigorous operator training. In Australian conditions, where sites can be remote and workforce turnover is steady, those overheads add up fast. Operators at resource processing hubs around Kalgoorlie and Mount Isa are used to handling reagent-heavy flowsheets, but downstream e-waste refiners rarely have the same infrastructure on hand.

ALS2 sidesteps those headaches by avoiding bulk strong acids altogether. The feedstock is conditioned thermally, then routed through a controlled oxidative step that liberates the palladium from its ceramic cage without dissolving it into a corrosive liquor. From a regulatory standpoint, this is a significant shift. The waste streams produced are far less hazardous to transport, and the operator footprint needed to gain an environment protection licence in states like Victoria or New South Wales is meaningfully smaller.

For Australian councils trialling small-footprint precious-metal recovery at transfer stations, that lower regulatory barrier is often the make-or-break factor. It is also why the technology has drawn interest from Indigenous-owned resource companies operating in remote regions, where a contained, low-reagent process is far easier to permit and to run safely.

How ALS2 stacks up against conventional routes

Parameter	ALS2 acidless route	Aqua regia dissolution	Pyrometallurgical smelting
Primary reagent class	Mild electrolyte plus thermal energy	Concentrated HCl and HNO₃	High-temperature smelt with flux
Palladium recovery rate	92–96%	90–94%	80–88%
Waste stream hazard	Low, solid ceramic residue	High, acidic fumes and liquors	Moderate, slag plus off-gas
Operator footprint	Compact, containerised	Medium, requires scrubbers	Large, fixed plant only
Suitability for remote Australian sites	High	Low	Moderate

The figures above come from pilot runs reported by the ALS2 consortium and from publicly available data on conventional refining routes. What stands out is not just the recovery rate, which is competitive, but the waste profile. Australian operators working under strict environment protection licences benefit considerably from a process that produces a benign, glassy residue rather than tonnes of spent acid that has to be neutralised before disposal.

The energy picture is also favourable. Because the thermal step operates below the melting point of palladium, fuel demand per kilogram of recovered metal is lower than for a full pyrometallurgical campaign. For a country whose grid is steadily decarbonising, that is an additional point in the technology's favour.

Inside the ALS2 recovery process

The first stage of the ALS2 process is decapsulation. Capacitor scrap is heated under controlled atmosphere to a temperature at which the glass binder softens and the mica layers delaminate, releasing the metallised film inside. This thermal pulse is calibrated to break the glass-ceramic bond without vaporising the palladium, which would be a costly mistake given the metal's value per gram.

Once the capacitor housings are opened, the material passes through a precision milling step. The aim is to liberate the palladium-bearing electrode fragments from the now-brittle ceramic matrix. Because the binder has been weakened thermally, the energy required to achieve liberation is much lower than in conventional shredding, which means less palladium smearing across equipment surfaces. The milled fraction is then routed through a selective electrochemical cell, where the palladium is dissolved into a benign electrolyte that can be precipitated cleanly in a downstream step.

The ceramic and mica residues, meanwhile, leave the circuit as a clean, glassy aggregate that can be reused in construction materials or as a feedstock for cement plants. Closing that loop is one of the quiet wins of the flow sheet, because it converts a problematic waste into a saleable by-product rather than a disposal cost.

Real-world yields and palladium quality

Across ALS2 pilot campaigns, the palladium recovered from glass-bonded mica feedstock has consistently met London Bullion Market Association good delivery standards after a single electrorefining pass. That matters because many acid-based routes require a second or third purification step before the metal is bankable. Operators in New Zealand and Australia who have trialled the system on capacitor scrap from decommissioned radio and radar units have reported final metal purities above 99.95% without additional chemical clean-up.

The yield is also steady across feedstocks. Palladium-rich and palladium-silver alloy electrodes both respond well to the electrochemical cell, which is useful for processors receiving mixed batches from defence disposals, telecoms upgrades, and industrial retrofits. The CSIRO has noted in its critical-minerals strategy that domestic recovery of platinum-group metals, including palladium, is a strategic priority for Australia, particularly given the country's reliance on imported supply for catalytic and electronics manufacturing.

Technologies that lift recovery rates from local scrap streams, without raising the environmental cost of processing, fit neatly into that national picture. Palladium recovered at home is also a hedge against the price spikes that have hit the global market whenever South African supply has been disrupted.

Integrating ALS2 into compact recovery plants

One of the most practical features of the ALS2 process is its modularity. The line can be delivered in a containerised format that fits on a standard 40-foot flatbed, which is the same form factor used for many of the mobile recovery units now appearing at Australian resource recovery hubs. A small team can run the full process, from decapsulation to refined palladium sponge, with a fraction of the personnel required for a traditional refinery.

For operators weighing capital outlay, the absence of large acid storage tanks and scrubber stacks simplifies permitting and lowers upfront cost. The process also scales gracefully, with additional modules bolted on as feedstock volume grows. That makes it a sensible fit for regional councils running transfer stations, for e-waste aggregators in Western Sydney or the Adelaide Hills, and for private processors serving the mining and defence supply chain. Anyone studying compact precious-metals recovery plants in Australia will find the ALS2 footprint fits the same operational envelope.

The technology is not a silver bullet. Feedstock still needs to be sorted, and the line performs best on capacitors that have been pre-separated from broader circuit boards. Used in combination with established dismantling and shredding infrastructure, however, it gives Australian operators a credible path to onshore platinum-group-metal recovery that did not really exist a decade ago.

Palladium locked inside glass-bonded mica housings no longer has to end up in long-haul refining chains or in landfill. ALS2 turns a difficult, acid-bound problem into a contained, modular flow that suits Australian conditions and the country's growing onshore e-waste processing ambitions. For refiners, recyclers, and engineering firms looking to study the technology in more depth or to keep up with the consortium's technical updates, a useful starting point is the project channel, which carries regular bulletins on pilot results and deployment milestones.