General Description
Odorless, white to tan powder.
Reactivity Profile
LIMESTONE has generally low chemical reactivity. Is non-combustible. Decomposes at high temperature (825°C) to give gaseous carbon dioxide and calcium oxide (quicklime). Incompatible with acids, alum, ammonium salts, fluorine, magnesium. Reacts with acids and acidic salts to generate gaseous carbon dioxide with effervescence (bubbling). The reaction is rapid and exothermic with concentrated solutions of acids. The efferversence can create extensive foaming. Ignites on contact with fluorine.
Hazard
A nuisance particulate dust.
Potential Exposure
Calcium carbonate is used as a source
of lime; neutralizing agent; manufacturing or rubber, plastics, paint and coatings; sealants, paper, dentifrices, ceramics, putty, polishes and cleaners, insecticides, inks and
cosmetics; whitewash; Portland cement; antacids; analytical
chemistry, and others
First aid
If this chemical gets into the eyes, remove any
contact lenses at once and irrigate immediately for at least
15 minutes, occasionally lifting upper and lower lids. Seek
medical attention immediately. If this chemical contacts
the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention
immediately. If this chemical has been inhaled, remove
from exposure, begin rescue breathing (using universal
precautions, including resuscitation mask) if breathing
has stopped and CPR if heart action has stopped. Transfer
promptly to a medical facility. When this chemical has
been swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an
unconscious person vomit
Incompatibilities
Calcium carbonate decomposes in high
temperature forming carbon dioxide and corrosive
materials
Description
Calcite is one of the most common minerals on the face of
the earth, comprising about 4% by weight of the earth’s
crust and is formed in many different geological environments.
Calcite can form rocks of considerable mass
and constitutes a significant part of all three major
rock classification types. It forms oolitic, fossiliferous
and massive limestones in sedimentary environments
and even serves as the internal cement for many sandstones
and shales.Calcite is even a major component in the igneous rock called carbonatite and forms the
major portion of many hydrothermal veins. Not necessarily
a variety of calcite, cave formations are certainly
a unique aspect of calcite’s story.
Chemical Properties
Calcium carbonate is a white, odorless
powder, or crystalline solid.
Chemical Properties
Ground limestone consists essentially of calcium carbonate. It is
obtained by crushing, grinding, and classifying naturally occurring
limestone benefited by flotation and/or air classification. It is pro duced as a fine, white to off-white, microcrystalline powder. It is
odorless and tasteless and is stable in air. It is practically insoluble
in water and in alcohol. The presence of any ammonium salt or
carbon dioxide increases its solubility in water, but the presence
of any alkali hydroxide reduces the solubility.
Waste Disposal
Landfills. It is the responsibility of chemical waste generators to determine if a discarded
chemical is classified as a hazardous waste. See 40 CFR
Parts 261.3 for United States Environmental Protection
Agency guidelines for the classification determination. In
addition, in order to ensure complete and accurate classification, waste generators must consult state and local hazardous waste regulations.
Definition
Aragonite: An
anhydrous mineral form of calcium carbonate,
CaCO3, which occurs associated
with limestone and in some metamorphic
rocks. It is also the main ingredient of
pearls. It is not as stable as calcite, into
which it may change over time.
Calcite:A mineral form of calcium
carbonate occurring in limestone,
chalk, and marble.
Charlk: A natural form of calcium carbonate
(CaCO3) formed originally by marine
organisms. (Blackboard chalk is calcium
sulfate, CaSO4.).
Preparation
The calcite present is derived mostly from the remains of organisms
such as clams, brachiopods, bryozoa, crinoids and
corals. These animals live on the bottom of the sea and
when they die their shells accumulate into piles of shelly debris. This debris can then form beds of limestone.
Some limestones may have been derived from nonbiogenic
calcite formation.
Health Hazard
Calcium carbonate is considered
to be a nuisance dust.
Although no adverse effects have been
reported in the literature among workers
exposed to calcium carbonate, high concentrations
of the dust would be expected to act as a
physical irritant to the eyes and skin.1 Fourteen
British workers exposed to heavy calcium carbonate
concentrations for 12–35 years showed
no trace abnormalities due to dust or any
clinical sign of pneumoconiosis or chronic
bronchitis on X ray.2 Long exposure to high
dust concentrations of pure calcium carbonate
(quartz content less than 1.1%) did not result
in lung fibrosis.
Agricultural Uses
Limestone or dolomite, used in agriculture for liming the soil, is ground to a fineness to ensure that 50% of the particles pass through a 1.70mm Indian Standards (IS) sieve, and 50% is retained on a 150micron IS sieve.