A coagulant is a chemical agent added to a liquid suspension — typically slurry or process water — to promote the aggregation of fine suspended particles into larger, heavier clumps (called flocs) that settle more readily under gravity or can be more efficiently removed by filtration or thickening. In mineral processing operations associated with bauxite, gold, iron ore, and diamond mining, coagulants play a vital role in the treatment of process water, tailings slurries, and plant effluents. Commonly used coagulants include inorganic compounds such as aluminium sulfate (alum), ferric chloride, and ferric sulfate, as well as lime. These reagents neutralise the electrostatic charges that keep fine particles suspended in solution, enabling them to collide and bind together. Effective coagulation improves the efficiency of downstream solid-liquid separation processes such as thickening, filtration, and clarification, reduces water consumption by enabling greater process water recycling, and helps achieve regulatory discharge water quality standards. The selection and dosage of coagulants must be carefully optimised based on the chemistry of the particular process stream.
