Sulphate Removal From Mining-Process Water By Capacitive Deionization

The removal of dissolved sulphate ions in water is one of the main challenges in the industry. Dissolved sulphate ions are ubiquitous in mining influenced waters because of its physical and chemical stability in aqueous solutions, including in process-water used by mineral beneficiation processes. It is a major problem for the mining industry because it can have negative impacts on the mineral beneficiation process and bring other issues for equipment and piping infrastructure. Not to mention the quality requirements for environmental water release. For instance, when water is recycled to the concentrator plant, dissolved sulphates can build up to increased concentration levels that can have negative effects in the processing of minerals. This work proposes a new approach for the removal of sulphate ions from mining influenced waters, including process water, which is the capacitive deionization technique (CADI). The technique can provide good quality water with low sulphate content suitable for recycling to the beneficiation process and meet adequate quality for recycling and safe release to the environment. Synthetic process-water with sulphate concentrations similar to those in mining and mineral process water was prepared and treated by CADI at fixed conditions of electric current and residence time. The original sulphate concentration in water was 1000, 2000, 3000 mg/L; and reduction rates achieved of sulphate concentrations of 275 mg/L, 712 mg/L and 1015 mg/L. respectively. The results show effective removal of sulphate ions.