The National Green Tribunal (NGT) on Friday recently directed the Central Pollution Control Board (CPCB) to prepare detailed pan-India guidelines for silica sand mining and silica washing plants.
About Silica:
Silica is another name for the chemical compound composed of two most abundant elements in Earth’s crust, silicon and oxygen, SiO2.
The mass of Earth’s crust is 59 percent silica, the main constituent of more than 95 percent of the known rocks.
Silica exists in many different forms that can be crystalline as well as non-crystalline (amorphous).
Silica has three main crystalline varieties: quartz (by far the most abundant), tridymite and cristobalite.
Other varieties include coesite, keatite and lechatelierite.
Uses:
Silica sand is used in buildings and roads in the form of portland cement, concrete and mortar, as well as sandstone.
Silica is also used in grinding and polishing glass and stone; in foundry molds; in the manufacture of glass, ceramics, silicon carbide, ferrosilicon, and silicones; as a refractory material; and as gemstones.
Silica gel is often used as a desiccant to remove moisture.
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