London- and Johannesburg-listed Tharisa has successfully produced 40 t of chrome alloy using a unique and proprietary process developed by its research and development business Arxo Metals.

Arxo, which successfully developed proprietary processes to produce specialty chrome – chemical and foundry grades – at the Challenger plant and to recover fine chrome particles at the Vulcan plant – both in commercial production at the Tharisa mine in South Africa’s North West province – has now developed a proprietary process to produce chrome alloy direct from smelting Tharisa-mined chrome.

Using a pilot facility, it has proven the feasibility of the process, Tharisa points out.

Chrome alloy has traditionally been produced by smelting chrome ore and producing ferrochrome, which is then remelted in furnaces and alloyed to produce various chrome-containing alloys. The ferrochrome smelting process is electricity-intensive.

Arxo’s process requires less power and, with the recent signing of a 15-year power purchase agreement (PPA) for wheeled renewable energy to be supplied by Etana Energy, Arxo believes the drive for ‘greener’ chrome from mine to final alloy production is attainable.

The first 40 t of alloy produced using chrome from the Tharisa mine has been sold to a downstream customer producing chrome alloy products.

In the process of developing these platinum group metal (PGM) and chrome alloys, Arxo has created over 100 new job opportunities in the pilot facility, Tharisa points out.

“This is a major milestone in our quest for maximising value for the raw materials we produce. Our aim at Arxo, driven by the chairman of the group, was always to revisit traditional thinking and methodologies and look for opportunities in value-creating in nontraditional ways.

“We have successfully demonstrated this in the two main commodities we mine, namely PGMs and chrome,” Tharisa beneficiation executive Lucien Matthews says.

“The pilot facilities have allowed us to prove technical feasibility and provide a means for technoeconomic evaluations and improvements. Our research in further downstream beneficiation using renewable energy and energy storage opportunities is moving ahead rapidly.

“With the production of PGM alloys and now with the commencement of the production of chrome alloys, we are proving the commercial viability of Arxo’s research, while adding further value with new sustainable jobs that we have created,” he adds.