Триоксид кальция и кремния (волластонит)

Описание

“Wollastonite” occurs as a calcium inosilicate mineral that may contain small amounts of Fe, Mg and Mn substituting for calcium.
The manufactured salt is usually white. It forms within the earth when impure limestone is subjected to high temperature and pressure, sometimes in the presence of silica-bearing fluids as in metamorphic rocks. It is named after the English chemist and mineralogist William Wollaston (1766– 1828).
Wollastonite crystallizes as a triclinic crystal with the space group, 1, and the lattice constants: a = 7.94? , b = 7.32 ? , c = 7.07 ? ; α= 90.03°, β = 95.37°, γ = 103.43° and six formula units per cell.

Химические свойства

White to brown, red, gray, yellow solid; vitreous to pearly luster. Mohs hardness 4.5–5.

Физические свойства

Wollastonite occurs as bladed crystal masses, single crystals can show an acicular particle shape and usually it exhibits a white color, but sometimes cream, gray or very pale green. The melting point of wollastonite is about 1540°C.

Использование

Ceramics; paint extender; welding rod coatings; rubber filler; silica gels; paper coating; filler in plastics, cements, and wallboard; mineral wool; soil conditioner.

Определение

A natural calcium silicate found in metamorphic rocks.

Методы производства

Wollastonite is a natural calcium silicate that typically occurs in deposits with other silicate minerals. When crushed, it tends to cleave into particles that have length to diameter ratios of 7 or 8 to 1. Fibrous forms of wollastonite are not uncommon.

Общее описание

White or slightly cream-colored powder. pH (aqueous slurry) 8.0 to 10.0.

Реакции воздуха и воды

Insoluble in water.

Профиль реактивности

These substances undergo chemical reactions only under relatively severe circumstances or in the presence of an effective catalyst that promotes reaction. They are resistant to ignition, although they may become flammable at very high temperatures. They will be resistant to oxidation/reduction, except in the most severe conditions. These materials may be nontoxic.

Опасность

Questionable carcinogen

Пожароопасность

Flash point data for CALCIUM SILICATE are not available; however, CALCIUM SILICATE is probably nonflammable.

Безопасность

Calcium metasilicate is potentially harmful to humans. It can cause eye irritation and is harmful if swallowed. Prolonged exposure may result in symptoms such as chronic bronchitis, fibrosis of the lungs and pleural parenchyma.