A decant tower is a vertical structure, typically cylindrical or rectangular in cross-section and constructed from steel, concrete, or HDPE pipe segments, that is installed within a tailings storage facility (TSF) or residue impoundment to serve as the primary inlet for collecting surface water from the decant pond and directing it into an outlet conduit for removal from the impoundment. As the tailings or residue level within the storage facility rises over the operational life of the TSF, the decant tower is progressively extended upward by adding additional riser sections, ensuring that the inlet to the tower remains above the tailings surface and within the decant pond at all times. In bauxite residue storage facilities, decant towers are engineered to resist attack by the highly caustic alkaline liquors present in the pond, typically using chemical-resistant materials or protective coatings. Gold mine TSF decant towers are designed in accordance with international tailings management standards such as the MAC Guide or GISTM, with freeboard maintained between the pond water level and the top of the tower inlet to prevent uncontrolled entry of water into the penstock under storm conditions. Iron ore tailings facility decant towers must be of sufficient diameter and height to manage the inflows from large catchment areas and high-intensity rainfall events common in tropical mining regions. Diamond mining operations use decant towers as part of their overall water management system to maintain appropriate pond water levels and maximize water recovery for plant reuse. The structural integrity of decant towers is critical to the safety of the TSF and must be regularly inspected and maintained.
