Sample preparation for leach and characterisation test work has been completed for the concept study into developing a mini-scale, simple, green, and energy-efficient process to recover pure zinc from polymetallic South African ore concentrates. The suitable zinc concentrate sample was sourced through Vedanta from its Black Mountain operation, reports Professor Jochen Petersen from the University of Cape Town’s (UCT’s) Department of Chemical Engineering.
A comprehensive review of current industry practice for zinc refining will be submitted to Minerals Processing and Extractive Metallurgy Review. Development of an ammonia-based leaching process is also underway, including thermodynamic modelling.
The study will now focus on extracting data from the leach experiments to inform the operating conditions and likely efficiencies of the ammonia-based leaching process. In parallel, a basic process flowsheet will be developed, together with a baseline prefeasibility cost evaluation for operating the process at a 40 000 tpa zinc production facility.
“The outcomes will enable the decision whether to develop the envisaged process further towards industrialisation and what aspects of the process may require further technology development,” highlights Professor Petersen. While using an ammonia medium for base metal processing is well established, it has yet to be applied to zinc refining.