A clarifier is a large industrial vessel or tank used in mineral processing to achieve solid-liquid separation by allowing suspended particles to settle by gravity, assisted by flocculants, producing a clarified overflow and a thickened underflow. In bauxite refining, clarifiers — often referred to as mud settlers, mud washers, or thickeners — are central to the Bayer Process and are designed to handle very large volumes of caustic slurry at elevated temperatures. The clarified sodium aluminate liquor overflows the clarifier launder and is directed to the precipitation circuit, while the red mud underflow is washed in subsequent thickeners to recover residual caustic soda before disposal.
In gold processing, clarifiers are used in CCD (counter-current decantation) circuits to wash leached tailings and recover gold-bearing pregnant solution.
In iron ore processing, high-rate thickeners and paste clarifiers are used to dewater tailings and recover process water.
In diamond processing, clarifiers handle kimberlite-bearing slurries after scrubbing and screening.
Key design parameters for clarifiers include unit area (m²/t/day), feed dilution, raking mechanism design, overflow rate, and flocculent dosage and dilution. Modern clarifiers are equipped with instrumented bed level monitoring, automatic rake torque control, and underflow density measurement systems to optimize performance and prevent mechanical failure.