Sand washing / attrition

Sand washing (attrition) is used to remove unwanted impurities such as clay, loam, dust or organic materials from sand or other bulk materials. 

The process involves mechanical friction between the sand particles, whereby the impurities are removed by shear forces. This takes place in a special washing machine, in which the sand grains rub against each other in a stream of water to loosen and remove the impurities. The washed sand particles are then further processed using a screening system or another separation technique.