Sand is a naturally occurring material and fragmented that consist tiny particles of decomposed corals, rocks or shells. It is used to give strength and other qualities to construction materials such as concrete and asphalt. It is used as decorative material as well in landscaping. Specific sand types are being used in manufacturing glass and as molding material for casting metal. There are other sand as well that are used in sandblasting and in making sandpaper.
The process of formation of sand starts in the natural decomposition. Breaking down of solid rocks into chunks are caused by natural mechanical forces like the movement of the glaciers, impact of rocks that fall on each other and expansion of water in cracks in freezing. Then the chunk of rocks is further broken down into grains caused by chemical action of rain and vegetation combined with mechanical impacts.
Extraction of sand can be as easy as scooping it from the riverbank with rubber-tired vehicle known as front loader. Then it is dumped into a train or truck or can be placed as well into a conveyor belt to transport to the nearby processing plant. If sand is extracted from underwater with dredge, slurry of sand and water is being dumped through pipeline to the plant. In the processing plant, the incoming material is mixed with water first. The material will undergo a number penetrated screens or plates with different openings. They re vibrated to enable the trapped material on every level working its way off the screen end and onto the other conveyor belts.
The material coming off the coarsest screen is cleansed in log washer before screening it further. Then the material which comes off the intermediate screen can be stored and mixed with finer sand or coarser gravel to make aggregate mixes. The material and water passing through the finest screen is then pumped into the horizontal sand classifying tank. While the mixture is flowing from one end of the tank into the other, the sand sinks into the bottom in which it is trapped in series of bins. The sand is taken out from the bins in the bottom of the tank with rotating dewatering screws that gradually moves the sand up within the inclined cylinder.
Some sand is crushed to produce a certain shape or size that is not naturally available.