Geology Reference
In-Depth Information
Bromine is a brownish-red liquid at ambient temperature and is used in industry
to make organobromo compounds. These compounds find application as insecti-
cides, in fire extinguishers, water purification, flame retardants, pharmaceuticals,
fumigants, dyes or photography.
B.2.9 Cadmium
No cadmium ore is mined for the metal, because more than enough is produced
as a byproduct of the smelting of zinc from its ore, sphalerite (ZnS), in which
greenockite, CdS, is a significant impurity making up as much as 3%.
Cadmium is used as a protective coating for iron and steel, as a pigment and as
a stabiliser for plastics. Its main application (about three-fourths of its production)
however involves NiCd batteries.
B.2.10 Calcium
Calcium is a silvery white metal belonging to the alkaline earth group. It is the
fifth most abundant element in the Earth's crust and the third most abundant metal
after Al and Fe. Vast sedimentary deposits of limestone CaCO
3
, which represent
the fossilised remains of earlier marine life, occur over large parts of the Earth's
surface. Other important minerals are gypsum CaSO
4
2H
2
O, anhydrite CaSO
4
,
fluorite CaF
2
and apatite Ca
5
(PO
4
)
3
F.
The metal is used as a reducing agent in the extraction of other metals, as a
deoxidiser, desulphuriser and decarboniser in the manufacture of many steels, as a
separating material for gaseous mixtures, as an alloying agent used in the production
of aluminium, beryllium, copper, lead and magnesium alloys as well as in the making
of cements and mortars to be used in construction. Calcium compounds are used
in a wide variety of applications such as insecticides, the manufacture of plastics,
as an additive in food and vitamin pills, as a disinfectant, as a fertiliser, in paints,
lights and X-rays.
B.2.11 Carbon
Carbon is a non-metallic element that forms more chemical compounds than any
other element except hydrogen. The major economic use of carbon not in living
material or organisms is in the form of hydrocarbons. It occurs both as the free
element (graphite, diamond) and in a combined form, mainly as the carbonates of
Ca, Mg. It also occurs as CO
2
, a minor but very important constituent of the
atmosphere, which is known to contribute significantly to the greenhouse effect. In
addition, carbon is widely distributed in the organic form of coal and oil.
The free element has a lot of uses, including jewellery (diamonds), as a black
fume pigment in automobiles rim, printer ink, for pencil tips, dry cell and arch
electrodes and as a lubricant. Carbon dioxide is used in drinks, in fire extinguishers
Search WWH ::
Custom Search