The silicon dioxide. Distribution in nature, way of getting, using

Silicon Dioxide (chemical formula: SiO2, silica) – it is a colorless crystalline, glassy or amorphous substance. This mineral is in the form of quartz sand is widely used in construction, chemical production and radio engineering, in aircraft construction and many other industries.

Distribution of silica in nature

Silicon Dioxide contained in the earth's crust in the form of mixtures with other minerals (they are called granites) and in the form of silicates included in the composition of the rocks. The most common natural mineral-quartz, rarer cristobalite, and stones of chalcedony, tridymite, opal, lechatelierite (quartz glass). Small quartz crystals form the so-called “core” quartz. With the gradual destruction of rocks are formed by quartz sand, which, compressed, lead to the emergence of quartzites and sandstones.

Rhinestone – this is the most clear quartz, is colorless. Its crystals can weigh dozens of tons and reach lengths of several meters. Also quartz can be colored by different impurities in the color purple (amethyst), yellow (citrine), black (Morion), smoky (rauchtopaz). In nature there are cryptocrystalline forms of quartz: it is a red pink carnelian, green Apple chrysoprase, blue sapphire, subtly-colored Jasper, onyx and agate sandy, hornfels and chert.

Unique “noble” opal, which consists of homogeneous colloidal particles with a diameter of about 0.2 µm. These particles closely Packed in orderly agglomerates, the water in them contains less than one percent (in most opals – about seven percent). Natural deposits of silicon dioxide can also form diatomite, diatomaceous earth. The mineral is built shells of diatoms, the skeletons of certain sponges. He is part of the stems of plants-such as reeds, horsetail, bamboo.

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How do you get the silica?

Synthetic SiO2 can be obtained:

– by the action of hydrochloric (HCl) or sulfuric (H2SO4) acids on sodium silicate, at least – to other soluble silicates (this method is basic in developed countries);

– using silica colloidal anhydrous (by freezing or coagulation under the action of the ions F-, Na+);

- by hydrolysis of silicon fluoride SiF4, SiCl4 silicon tetrachloride, tetraethoxysilane (C2H5O)4Si, solid desublimate (NH4)2SiF6 in the gaseous form and in aqueous ammonia and water solution (sometimes with the addition of organic bases or ethanol).

Silica amorphous get:

– diatomite and diatomaceous earth;

– calcining rice husk;

– a milling fused quartz sand.

Anhydrous powders of silica get:

– using a chemical deposition from the gas phase;

– by hydrolysis and oxidation of the vapor of esters fumed silica and fluoride of silicon;

- by burning of vapors of silicon tetrachloride SiCl4 in a mixture of O2 and H2.

How to use silica?

– the natural silica used in the manufacture of porcelain, concrete, abrasives, silicate brick, ceramic, porcelain, silica, silicate glasses;

– silica synthetic (‘black white”) are used as filler in the production of rubber;

– single crystals of quartz found use in electronics (filters, frequency stabilizers piezoelectric, resonators) in acoustoelectronics and acousto-optics, in the jewelry business, in an optical instrument;

– rhinestone and synthetic silica are used as raw materials to produce quartz glass, quartz crystals, quartz fibers and ceramics. In turn, ceramics and quartz glass used in the aircraft industry, optics, electronics and other industries. Quartz fabric is used as material, heat-trapping, and quartz fibers – to create a fiber-optic transmission systems and communication lines.