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Description:
The mineral graphite
is an allotrope of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient
Greek "to draw/write",[4]
for its use in pencils,
where it is commonly called lead
(not to be confused with the metallic element lead).
Detailed Description:
Unlike diamond (another
carbon allotrope), graphite is an electrical conductor, a semimetal. It
is, consequently, useful in such applications as arc lamp electrodes.
Graphite is the most stable form of carbon under standard conditions. Therefore, it is used in
thermochemistry as the standard state for defining the heat of formation of carbon
compounds. Graphite may be considered the highest grade of coal, just above anthracite
and alternatively called meta-anthracite, although it is not normally used as
fuel because it is difficult to ignite.
There are three principal types
of natural graphite, each occurring in different types of ore deposit:
1. Crystalline flake graphite (or
flake graphite for short) occurs as isolated, flat, plate-like particles with hexagonal edges
if unbroken and when broken the edges can be irregular or angular;
2. Amorphous graphite occurs as
fine particles and is the result of thermal metamorphism of coal, the last stage
of coalification, and is sometimes called meta-anthracite. Very fine flake
graphite is sometimes called amorphous in the trade;
3. Lump graphite (also called vein
graphite) occurs in fissure veins
or fractures and appears as massive platy intergrowths of fibrous or acicular
crystalline aggregates, and is probably hydrothermal in
origin.
Highly ordered pyrolytic
graphite or highly oriented pyrolytic graphite (HOPG) refers to graphite with
an angular spread between the graphite sheets of less than 1°. This
highest-quality synthetic form is used in scientific research, in particular,
as a standard for scanner calibration of scanning probe microscope. The name
"graphite fiber" is also sometimes used to refer to carbon
fiber or carbon fiber-reinforced polymer.
Uses
of natural graphite
Natural
graphite is mostly consumed for refractories, batteries, steelmaking, expanded
graphite, brake linings, foundry facings and lubricants. Graphene, which
occurs naturally in graphite, has unique physical properties and might be one
of the strongest substances known; however, the process of separating it from
graphite will require some technological development before it is economically
feasible to use it in industrial processes.
Refractories
This
end-use begins before 1900 with the graphite crucible used
to hold molten metal; this is now a minor part of refractories.
In the mid 1980s, the carbon-magnesite brick became important, and a bit later the
alumina-graphite shape. Currently the order of importance is alumina-graphite
shapes, carbon-magnesite brick, monolithics (gunning and ramming mixes), and
then crucibles.Crucibles began using very large flake graphite, and carbon-magnesite brick requiring not quite so large flake graphite; for these and others there is now much more flexibility in size of flake required, and amorphous graphite is no longer restricted to low-end refractories. Alumina-graphite shapes are used as continuous casting ware, such as nozzles and troughs, to convey the molten steel from ladle to mold, and carbon magnesite bricks line steel converters and electric arc furnaces to withstand extreme temperatures. Graphite Blocks are also used in parts of blast furnace linings where the high thermal conductivity of the graphite is critical. High-purity monolithics are often used as a continuous furnace lining instead of the carbon-magnesite bricks.
Price
$1165.82/kg or $529.46/ib
For more information:
mobile: +2348039721941
contact person: emeaba uche
e-mail: emeabau@yahoo.com
website: www.franchiseminerals.com
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