Higher kaolin recovery with a water-injection cyclone

In kaolin classification, the final product is isolated from the overflow of a 50 mm hydrocyclone with an underflow containing fine sand and residual kaolin. For a higher kaolin recovery, the underflow is usually further treated using a washing cyclone. This paper presents a new development in fine sand washing using water injection in the conical section of the classifying cyclone. This washing results in a 45–50% reduction of the kaolin fraction (<10 μm) in the underflow. Thus, water injection into the classifying cyclone leads to a separation comparable to downstream washing.