The Anglo American Technical Solutions team is pressing head with scale up of SandLix™, the novel heap leach process which it says directly addresses some of the most pressing challenges facing the industry when it comes to future copper supply.
The latest large pilot column is now up and running at the Anglo American Technical Solutions facility in Johannesburg, which is a central technical and analytical support centre for Anglo American’s global mining operations, providing process development and testing in disciplines like minerals processing and hydrometallurgy. South Africa’s ProProcess has also been involved with the pilot, providing fabrication for the column.
Chris Biley, Anglo American VP, Technology Development, said in an online update that the team is continuing excellent scale-up performance seen to date and providing key data into for ongoing deployment studies. To date, fieldwork has also included a prototype heap at the El Soldado copper mine in Chile.
SandLix™ is part of Anglo’s FutureSmart Mining™ programme and has been specifically developed to economically treat low-grade, complex ores, while being far less energy and water intensive than conventional processes, such as flotation. SandLix™ is conceptually simple and has been demonstrated at pilot scale, proving to deliver equal or better recovery rates than flotation on primary ore – more than 85% within 250 days.
Anglo says the key to unlocking high recoveries lies in the configuration and control of the particle size, temperature and chemistry in highly permeable heaps, which are adapted specifically for each ore. Precise control of these optimised heaps generates conditions for natural biooxidising microbes to thrive and increase the temperature of the heap to where high recovery rates of copper can be achieved from even low-grade, complex primary copper ores dominated by chalcopyrite which existing leaching processes are not capable of recovering copper from economically and sustainably.
Through this unique process of heap leaching, SandLix™ has the potential to reduce the cut-off grade of copper processes by up to 20% and increase resource utilisation by economically processing low-grade ores, while reducing water and energy intensity and the quantity of wet tailings.
SandLix™ technology allows ‘stranded’ ores to be economically processed in a sustainable way – using around half the amount of water and energy compared to conventional processes that involve flotation and smelting. In addition to copper, SandLix has potential to be extended to the recovery of other metals in the future.
The technology reimagines the heap leach process by engineering the particle size of the ore to generate a highly permeable ‘sand’ for heap leaching. Fines are removed from the ore to increase the permeability of the remaining heap, and are treated in a separate small, integrated flotation process which both increases recovery and optimises leach reagent consumption. What then remains is a heap made up of sand grain sized particles through which the chemicals can easily flow, enabling the chemical conditions and temperatures in these permeable sand heaps to be more precisely controlled to recover copper from the ore.
Anglo states: “The key to unlocking high recoveries lies in the configuration and control of the particle size, temperature and chemistry in highly permeable heaps, which are adapted specifically for each ore. Precise control of these optimised heaps generates conditions for natural bio-oxidising microbes to thrive and increase the temperature of the heap to where high recovery rates of copper can be achieved from even low-grade, chalcopyrite ores.”
