Chemical Properties
white or cream powder
Hazard
Irritating dust. Use in foods restricted to
5% in baking powder, 2% in table salt. Upper res-
piratory tract irritant. Questionable carcinogen.
Description
Calcium orthosilicate is
commonly used as a safe alternative to asbestos for
high-temperature insulation materials. Industrial grade
piping and equipment insulation are often fabricated
from calcium orthosilicate.
Description
The stoichiometry of the hydrate in cement paste is
variable and the state of the chemically and physically
bound water in its structure is not clear.
Thus, calcium silicate can be prepared by calcining
the oxide with silica, SiO2, at an elevated temperature:
CaO + SiO2+ hea?CaSiO3
Application
The main applications of calcium silicate relate to its anticaking properties, and it has therefore been used in dusting powders and a range of different cosmetic products (e.g. face powders, eye shadow). It is also used as anticaking agent in table salt, foods, pharmaceuticals, and agricultural pesticides; replacement for asbestos in thermal insulation; Constituent (produced in situ) of lime glass, portland cement; reinforcing filler in elastomers and plastics; absorbent for liquids, gases, vapors; as anti-caking agent, suspension agent, pigment and pigment extender; binder for refractory material; in chromatography; in road construction.
Preparation
Calcium silicate is a naturally occurring mineral, but for commercial applications it is usually prepared from lime and diatomaceous earth under carefully controlled conditions.
Production Methods
When used in oral formulations, calcium silicate is practically
nontoxic. Inhalation of the dust particles may cause respiratory
tract irritation.
Health Hazard
The toxicity of calcium silicate
depends on particle size, aspect ratio, and
amount of silica and respirable fiber.1 Synthetic
nonfibrous calcium silicate is considered to be
a nuisance dust.
Skin irritation was reported in a worker
exposed to an atmosphere permeated with calcium silicate.1 A study of 104 wallastonite (a
naturally occurring calcium silicate mineral)
miners showed no relationship between the
prevalence of chronic bronchitis or airflow
obstruction with increasing exposure.1 In a
cohort mortality study of wollastonite quarry
workers the observed numbers of deaths from
all cancers combined and lung cancer were
lower than expected.
Flammability and Explosibility
Notclassified
Pharmaceutical Applications
Calcium silicate is used as a filler aid for oral pharmaceuticals. It has
also been used in pharmaceutical preparations as an antacid.
The main applications of calcium silicate relate to its anticaking
properties, and it has therefore been used in dusting powders and a
range of different cosmetic products (e.g. face powders, eye
shadow).
Industrial uses
Calcium silicate compounds belong to a complicated class of silicates. Among their many industrial applications, calcium silicates are heavily used as a building material as they constitute the main ingredient in today’s cement clinker.
Safety
GRAS listed. Included in the FDA Inactive Ingredients Database
(oral dosage forms). Included in nonparenteral (oral, orodispersible,
effervescent and enteric-coated tablets) formulations licensed in the
UK.
storage
Calcium silicate is chemically stable and nonflammable, but it
should be protected from moisture. Store in airtight containers in a
cool, dry place.
Incompatibilities
Calcium silicate is a naturally occurring mineral, but for commercial
applications it is usually prepared from lime and diatomaceous
earth under carefully controlled conditions.
Regulatory Status
Calcium diorthosilicate; calcium trisilicate.
