Wastewater treatment in mining encompasses the physical, chemical, and biological processes used to remove contaminants from water that has been impacted by mining, mineral processing, or associated industrial activities before it is discharged to the environment, reused in operations, or returned to the natural water cycle. Sources of mining wastewater include pit dewatering, tailings storage facility return water, process plant effluents, acid mine drainage seepage, and stormwater contaminated with sediments or chemicals. In bauxite mining, wastewater treatment must address high pH and caustic soda contamination from refinery liquors, as well as suspended solids and elevated metal concentrations in site runoff. Gold mine wastewater treatment systems are designed to destroy residual cyanide — typically using the SO2/air process or hydrogen peroxide treatment — and to precipitate dissolved heavy metals including mercury, arsenic, and lead before water is recycled or discharged. Iron ore mine wastewater treatment focuses on removal of suspended solids through settling ponds, flocculant dosing systems, and mechanical filtration. Diamond mine wastewater treatment addresses turbidity, suspended kimberlite fines, and elevated concentrations of sodium, magnesium, or trace elements from processed ore. Treated water is ideally returned to the process circuit to support water conservation goals and reduce net water consumption.
