Silica and its role in the production of iron and steel...

Silica and its role in the production of iron and steel Silicon, the element, is the second most abundant element in the earth’s crust. Silica is the scientific name for a group of minerals made of silicon and oxygen. It is one of the most abundant oxide materials in the earth’s crust and is found in most mineral deposits found on the earth. It is the starting material for the production of ceramics and silicate glasses. Silica (from the Latin word ‘silex’), is an oxide of silicon. It is a compound made up of silicon and oxygen atoms and has the chemical formula SiO2. It occurs commonly in nature as sandstone, silica sand or quartzite. It is the most frequently found in nature as quartz (SiO4). It is the major constituent of sand. Silica is one of the most complex and most abundant families of materials, existing as a compound in several minerals. Silica occurs in a variety of crystalline modifications and also as an under-cooled melt called quartz glass. The crystal structure of the individual SiO2 modifications can differ widely, so that distinct density changes occur during transformation. This is of great importance during heating and cooling because of the change in the volume. Silica can be a naturally occurring substance, like quartz, or it can result from human activities. It occurs in many forms. It can exist in an amorphous form (vitreous silica) or in a variety of crystalline forms. Amorphous silica is found in nature (e.g., diatomaceous earth and plants), as well as in synthetic materials. In amorphous silica, the silicon and oxygen atoms are not arranged in any particular pattern. Amorphous forms of silica have a random pattern while in crystalline silica, atoms of silicon and oxygen are arranged in a repeating, three dimensional pattern which is known as crystal lattice. Crystalline silica...