Sulphate and TDS Treatment
Total dissolved solids (TDS) and particularly high sulphate concentrations are an on-going challenge for the mining industry. Limits exist in many jurisdictions and mining companies are having difficulty meeting these limits. Envirobay has extensive experience in the removal of TDS using chemical processes and/or membrane filtration. Ion exchange and biological processes are other technologies occasionally applied.
Membrane filtration can be completed using nano-filtration (NF) or reverse osmosis (RO). The key is in properly pre-treating the water and optimising the operating conditions to minimise membrane fouling, decrease costs of anti-scalants, and maximise recovery. The challenge is often in the cost-effective treatment of the concentrate. Envirobay has proven methods for combining chemical processes with membrane filtration for best cost efficiency and reliable operation.
The chemical processes can include the use of lime, barium compounds, and ettringite precipitation. The HDS process can be optimised to serve as a pre-treatment in conjunction with other additives in order to minimise the scaling potential in the membrane system or decrease costs for other chemical processes. These options are reliable, proven and generally more cost-effective than direct barium or ettringite options. This optimised HDS process can also be used to deal with the concentrate (or brine) from NF or RO filtration.