Orion Minerals Ltd (ASX:ORN, JSE:ORN) has taken another step down the path to sustainability with an electrolysis water treatment trial set to begin at the Prieska Copper-Zinc Mine in South Africa’s Northern Cape Province.
Prieska’s extensive underground workings hold about 9 million cubic metres of water, accumulated since the mine was closed in 1991.
While the pH of this water ranges from 6.6 to 7.1, neither particularly acidic nor alkaline, the total dissolved solids in the shaft water was measured at 6,000 to 11,000 milligrams per litre, meaning some water treatment is required before it can be used for agricultural or potable purposes.
Assessing ESG outcomes
“As we prepare to start dewatering the underground mine at the Prieska Mine, we continually review engineering and technology solutions to find ways of reducing costs and maximising ESG outcomes at our operations,” Orion Minerals managing director and CEO Errol Smart said.
“Any technology or new process that offers benefits to our key stakeholders and local host communities while supporting shareholder returns will always be prioritised in our operating plans.
“We are particularly pleased to have the opportunity to collaborate with South African technology developers, Free Radical Process Design, who have worked with The University of Pretoria to develop an innovative technology that could have a global impact in the treatment of contaminated mine water, and which is directly applicable to our Prieska Mine dewatering challenge.”
Innovative electrochemical treatment
Orion intends to leverage Free Radicals Process Design’s innovative Electrosoftner/RotowinnerTM electrochemical water treatment and mineral extraction technology, which will use a combination of reverse osmosis and electrolysis to extract minerals from the mine shaft water.
The company expects this process to yield both clean water and valuable mineral products, including sodium hydroxide and iron oxide – which are used in the chemical industry – and calcium and magnesium, which have agricultural applications.
“We look forward to trialling the Rotowinner Technology to treat our Prieska Mine water while simultaneously recovering ‘clean and green’ agricultural nutrients and delivering treated water which would be available for community agriculture purposes,” Smart continued.
“In addition to agricultural nutrients, other products can potentially be extracted using the Rotowinner Technology which are used in the chemical industry, opening up interesting future by-product sales opportunities.”
The collaborative research and development initiative will partially be used to conduct field trials on the Rotowinner technology using Free Radical’s mobile pilot plant (pictured), to test the capacity for this technology to replace more expensive reverse osmosis processes for water purification.
Orion has planned for the dewatering process to take about three and half years, during which it intends to begin copper and zinc mining operations in the upper regions of the deposit that sit above the water level.