Diatomaceous silica, insulation material

When lime-bonded insulating materials are being made, inclusion of colloidal silica increases the strength when sand or diatomaceous earth are the major components (762, 763). 

Calcium silicate heat insulation material is a synthetic material produced from silica (rebned diatomaceous ore or milled silica sand) and of calcium oxide (high-quality calcium carbonate chalk or lime) with the addition of organic bbers (in order to keep shape after pressing). Pulp sluny from the mixer is squeezed out, pressed, and after exposure at air placed in the autoclave with steam pressure about 10 atm and temperature 120-130 °C. The synthesis of xonolite [207] mineral takes place at the above-menti(Mied crHiditimis, and actually it is the end of the technological process. The dimensiOTis of calcium sibcate boards may be up to 2,500 mm x 1,500 mm. 

Diatoms are single-celled algae that produce a hard skeleton made of hydrous silica (opal). The rock that forms from consolidated layers of diatom skeletons is called diatomite. This material has many common and commercial names, including diatomaceous earth, Fuller s earth, kieselgur, and tripo-lite. Diatomite is mined and used as building material, in filters, as insulation, as a mild abrasive, and as a filler in dry chemicals. 

Insulation should be designed for maximum ambient and minimum chlorine temperatures. It should be nonflammable, dry, and chemically inert to chlorine. Because a purge gas is required between the two tanks, the insulation should be a granular material. Expanded silica and diatomaceous earth are examples. The purge gas outlet should be monitored for chlorine. 

In recent years the increasing use of liquefied gases in industry, as rocket propellants, and as low-temperature baths, to mention only a few. and the practical results of transporting gases in liquid form, have necessitated a search for more efficient schemes for low-temperature insulation. Evacuated powders are one scheme that shows promise. Powder insulation, in either evacuated or unevacuated systems, refers to the use of materials with a low bulk solid conduction, in a finely divided state. Examples are silica aerogel (Santocel, Cab-0-Sil,Syloid), calcium silicate (Microcel), diatomaceous earths, perlite, etc. 

Perlite, colloidal silica, and silica aerogel have been widely used as powder insulations as well as mica, diatomaceous earth, carbon, calcium, silicate, and plastic microspheres. All are finely divided particulate materials that make solid conduction paths disjointed and discontinuous. 

---