Water treatment and recovery strategies for the Northern Cape Assmang operations

Abstract

Water scarcity is a global issue where many countries, including South Africa, experience it due to various factors such as climate change, water contamination, poor infrastructure and industrial overuse. This study focuses in developing a water treatment strategy to address water constraints at Assmang mining operations in the Northern Cape, South Africa. The study used a traditional coagulation process with ferric chloride and simulated reverse osmosis (RO) system using the LewaPlus software to observe their feasibility on treating mine wastewater to produce domestic water, suitable for reuse in mining activities, complying with South African National Standard (SANS). In this research, a jar test was used to determine the optimal dose for treating mine wastewater and the simulated RO system was analysed under varying operating conditions to optimize recovery, energy consumption, and cost efficiency. Results from the two-stage RO design indicate greater than 97% reduction in total dissolved solids, with an 80% recovery rate and permeate water quality, meeting SANS standards for domestic use. In conclusion, the coagulation process and RO system can be effective, for most of all physicochemical characteristics, falling within acceptable ranges, but not for coagulation experiments. Magnesium, calcium and sodium remain above the recommended SANS limits. The turbidity level also was reduced from 1.20 to 0.55 NTU, but it is not enough for RO system feed water, as it can result in scaling, or damage the membrane and increase operational cost. This indicates the need for additional treatment to ensure optimal removal of turbidity and magnesium, calcium, and sodium. Additionally, to consider the cost of water produced as may be more cost-effective to procure municipal water.