Decant water recovery in mining is the systematic process of collecting, transferring, treating where necessary, and reusing the water that accumulates on the surface of tailings storage facilities (TSFs), residue impoundments, or mine pit sumps, as part of a comprehensive water management and conservation strategy. In bauxite and alumina refining, decant water recovery from residue storage areas is a critical component of the caustic soda conservation strategy, as the recovered alkaline liquor contains significant quantities of dissolved sodium hydroxide and aluminate that can be returned to the Bayer process circuit, reducing both reagent costs and freshwater requirements. Gold mining operations prioritize decant water recovery from TSFs as a means of minimizing freshwater make-up requirements, particularly in water-scarce mining regions, and recovering process water that may contain residual soluble gold or costly reagents. Iron ore mining operations implement comprehensive decant water recovery programs from tailings dams and pit dewatering systems to maximize water recirculation rates within the concentrator plant, reducing the environmental impact of mining on local water resources. Diamond mining operations recover decant water from kimberlite tailings ponds to maintain the water balance of the DMS and scrubbing circuits, minimizing freshwater abstraction from local rivers or boreholes. Effective decant water recovery requires well-engineered decant systems, reliable pumping infrastructure, water quality monitoring, and integration of recovered water volumes into the mine's water balance model, which tracks all inflows, outflows, and storage volumes across the entire operation to ensure sustainable water use.
