The recycling of platinum-group metals (PGMs) is important as it provides an additional source of PGMs besides the mining of these metals and it reduces the impact of the platinum industry on the environ- ment, says Australian precious metals recovery company Wintermute Metals.
PGMs are a key component in catalytic converters, which are used in cars, trucks, buses, motorcycles and generators. However, scrap converters are not currently processed in Australia but are collected, crushed and shipped to Europe or South Africa for this purpose instead, which is a carbon-intensive process.
For this reason, Wintermute Metals has researched, developed and patented the Wintermute Process, which is a method that efficiently and safely recovers 99% platinum and palladium as well as 90% rhodium from scrap catalytic converters, while also impacting less on the environment.
The patented Wintermute Process entails a dilute acidic, oxidising leach of the crushed catalyst, says business development and investor relations director Barry Epstein.
“The catalyst is removed from the steel containers, after which it is crushed and leached for a short period in dilute acid, which contains several chlorine containing compounds at a relatively low temperature (90 ˚C) and at atmospheric pressure. This process converts the PGMs to water-soluble metal complexes, which are filtered from the matrix material and precipitated, by using recycled aluminium cans. The acid and reagents are then collected and reused for the next round of processing,” he explains.
Compared with existing recovery techniques, during which large furnaces are used to melt the catalysts, with the heat and fluxes used being potentially hazardous, the Wintermute Process is a hydrometallurgical solution – it operates at normal atmospheric pressure; it does not use concentrated acids or cyanide; and it does not have any hazardous effluent or intense power requirements.
Wintermute established a pilot production facility in Armadale, in Western Australia, which is currently operational and uses this technology.
“The capacity of the plant will be increased progressively over the next few months as funding becomes available to eventually process more than 100 t of catalyst a year,” says Epstein.
The company is seeking investors to raise $400 000 of seed capital to enable the purchase of capital equipment and catalysts to take the business to the next level.
“Our business plan is firstly to establish several facilities in Australia, after which we will aim to expand through suitable partners or licence holders overseas,” he adds.