Recent droughts have exposed South Africa to water shortages, leading mining companies to look at other untapped resources to help save on water use. The impact of diamond mining on water resources is usually material to local communities, and therefore, Petra Diamonds initiated a project to reuse process water from the Koffiefontein Mine in 2014 to help resolve this shortage.
The process water recycling project was initially designed to recycle and clean at least 50% of process water for reuse at Koffiefontein’s processing plant. This involved using a paddock system that settled fine kimberlite particles at the bottom of the process water. The water was then pumped back into the water system and reused in the mining process. The project took 12 months to complete and was tested for three months, with outstanding results. The test work indicated that the paddocks system was recycling 75% of the process water, significantly above the planned 50%.
As an additional bonus, tests also indicated that effluent from the paddocks now had an electrical conductivity level that positively contributed to the diamond recovery process, reducing the reliance on other density-enhancing chemicals. By implementing this water-saving initiative, Koffiefontein has not only saved on operating costs, but has also positively contributed to the sustainability of its local community.