Process and assembly to separate and wash sand particles in a waste water treatment plant renders mineral sand fit for disposal to an open site

摘要

A sand washing assembly (10) receives sand from a waste water treatment plant. The sand is received as a mixture of mineral sand, water and organic substances released to a settlement tank (20). The process forms a density gradient by the release of a continual stream of fine bubbles (50) rising through a membrane (54). The separated sand is removed (30) in a regulated manner providing full separation. The sand washer can also undertake the functions of a prior art washer and sand trap. The separation of sand particles is effected by a send recognition sensor (60) which measures the torque exerted on a mixer blade (40) tip by an emerging sand particle.