ABSTRACT

Sand and gravel production processes can be grouped into extraction (digging, loading and transporting), preparation (clay matrix disaggregation, washing, scrubbing and cobble crushing), sizing (gravel screening and sand classification) and beneficiation (removal of deleterious particles, desliming and dewatering). The present tendency is towards more elaborate plants, with more diverse products obtained from less-promising feedstocks. Other recent developments are the use of friable, weakly cemented sandstone and conglomerate as sources, and the wider use of dredged marine sands.