Modern Mining August 2020

cause scaling of pipelines, which results in reduced throughput. “Furthermore, it has been proven that con- taminated waters can have a significant effect in recovery efficiency of hydrometallurgical processes. Compared to uncontaminated fresh water, lower recovery of target metals can be attributed to the presence of various metal ions in the process water,” explains Ridgard. For gold operations, for example, the gangue minerals are insoluble in cyanide solution. Some metallic minerals, however, are soluble and deprive the solution of its oxygen and cyanide.

It is also used in some underground operations for hydro-powered equipment. “Mining operations, commonly seek water from groundwater, rivers and lakes, or through municipal water service suppliers. It plays an essential role in most mining and extractive processes, and today, responsible water use is a critical business issue for the mining sector as a whole,” adds Ridgard. “Maintaining a constant water balance on your site is critical for both mining and mineral process- ing. For underground mining, you constantly need to dewater your shaft to allow for mining practices to continue. This water could now be contaminated by naturally leached components such as arsenic, and first needs to be treated before it can be dis- charged to the environment to maintain a water balance,” he says. On the surface, the water needs of the process- ing plant must be balanced with what is now in the tailings facility. Any excess water needs to be treated and discharged from the tailings facility to maintain the water balance. Overcapacity can be catastrophic, with dam failures inevitable, explains Ridgard. Effect of contaminants in process water Water quality can have a detrimental effect on pro- cess efficiency and recovery, but it is often the last place that mine operators look when experiencing a drop in recovery. Water hardness (high concentra- tion of CaCO 3 and MgCO 3 ) in process waters can

Maintaining a constant water balance on your site is critical for both mining and processing.

Multotec has partnered with Australian based Clean TeQ Water to provide the African mining market with a continuous counter current ion exchange technology.

August 2020  MODERN MINING  31