River sand comes from river beaches, and its resources are relatively abundant. However, with over-exploitation in recent years, it has shown a trend of gradual scarcity. The characteristic of river sand is its low soil content and impurities. River sand is mainly river beach sedimentary sand, which is grayish-white or grayish-yellow in color, and is composed of fine sand, medium-coarse sand, coarse sand, gravel layer, and gravel layer. The occurrence of river sand is oriented toward the river bed, and the surface layer slopes from the river bank to the river bed, and tends to slope from the upstream to the downstream. River sand has the characteristics of hard texture and clear color, and is a good building material.     Washed sand is raw sand made of natural silica sand after washing and grading. The mud content is smaller than that of river sand. Washed sand is natural sand sent to the sand washing machine for cleaning. The powder, soil, and fine sand particles in the sand are cleaned and filtered out. The purpose of controlling the size of the finished sand and gravel can be achieved by controlling the mesh number of the washing screen. , To control the content of fine sand particles and stone powder within a certain ratio to improve the overall quality of sand and gravel. The raw material of sand and gravel can be washed with water to make the finished product size standardized and the size of the finished product can be combined and separated according to the needs of users. Out various specifications of sand.