The recycling of used automotive catalytic converters (autocatalysts) has become economically and environmentally important in the wake of autocatalysts becoming one of the most significant consumers of platinum group metals (PGM) for their manufacture, according to alternating current (AC) and direct current (DC) furnaces designer and fabricator Allied Furnace Consultants (AFC) founder and director Tertius Pieters.

He notes that the recovery of PGMs from autocatalysts is a new and evolving process in terms of historical metals recycling, globally.

In scientific journal Cleaner Engineering and Technology, published by ScienceDirect, in July 2021, it was noted that autocatalysts are the biggest consumer of PGMs, with an estimated 360 t of PGMs being needed for the production of autocatalysts in 2018.

The journal explains that after a certain period of time, autocatalysts become spent and need to be replaced; however, these emissions-scrubbing components still contain significant amounts of precious metals, with a significant loading of PGMs.

Therefore, Pieters notes that a greater emphasis can be placed on the recycling of spent autocatalysts to attain in-demand PGMs.

However, he notes that used autocatalysts need to be received by recyclers in a decent condition and need to be inspected to attain representative samples from which an accurate measurement of contained metal content can be determined.

A widely applied method of PGMs recovery from autocatalysts is pyrometallurgy, explains Pieters.

He says modern pyrometallurgy recycling processes are characterised by automated processes – an “instrumental” aspect in the upscaling of PGMs recovery from such systems, and one which offers promising yields.

For the past 17 years, AFC has been the original-equipment manufacturer (OEM) supplier to South Africa’s national mineral research organisation Mintek, giving AFC unique exposure to a vast number of pyrometallurgical processes using its DC furnace technology equipment.

AFC’s DC plasma arc smelting technology has been demonstrated and commercialised across a variety of commodities, more recently, for the recovery of precious metals from spent autocatalysts.

Relatedly, Pieters explains that AFC is engaged with Europe-based green metals recycler and producer Elemental in a project relating to the development of technologies for the safe, environment-friendly and cost-effective transport, storage and recycling of used autocatalysts.

This project is aimed at developing innovative processes for recovering metals crucial for electric mobility, to be done through innovative methods that will improve upon existing recycling techniques.

Going forward, AFC will assist its key clients in the development of innovative process equipment for the recovery of green metals, conducting research and development activities related to metal recovery.

The Elemental project's first plant is dedicated to implementing innovative metals recovery processes on an industrial scale. The plant will serve as a pilot project, testing the developed technologies in a real-world setting.

Pieters tells Mining Weekly the aim of the project is to validate and optimise these processes on a scale similar to that of industrial production.

He explains that AFC engaged with Elemental at the start of 2020 and has since become the preferred OEM for the company, now supplying them with DC furnace technology.

Pieters adds that AFC’s DC furnace technology can recover fine material, of differing grades, from autocatalysts.

He concludes that Elemental has since hot commissioned the first of two AFC DC furnaces.