Indian scientists have developed synthetic granite tiles that compare well with the natural stuff
GRANITE takes millions of years to form
naturally, but now it can be synthesised
in the laboratory in a matter of days,
thanks to a technique devised at the
Central Glass and Ceramic Research
Institute (CG&CRI), Calcutta.
The CG&CRi researchers came
upon this technology almost by chance.
The scientists were trying to make
scratch-proof floor tiles when they
observed that the ingredients had metamorphosed into a clone of natural
granite.
The magic wand is a silicate mineral
called garnet found in abundance on
the beaches of Kerala and Tamil
Nadu, which are rich in monazite - a
commercially important rare earth
mineral.
Public sector Indian Rare Earths
Limited (IREL) uses monazite from the
sand at its plants in Orissa and Kerala,
while garnet is dumped as worthless.
The IREL people didn't know what
to do with the garnet heaps growing
in their backyards. So they had
approached CG&CRI to
find out if they had any
use for it.
The CG&CRi has,
through the Council for
Scientific and Industrial
Research - both are
Central government bodies - applied for a
patent for the synthetic
granite. Once patented,
the technology can be
sold to an entrepreneur willing to
produce granite tiles on a Commercial basis.
The water is then filtered out and
the tiles allowed to dry. The drying
process could be natural or artificial
using electricity.
The tiles are then put into a kiln and
sintered at temperatures of 1,100-
1,200'c. The end result is an unpolished
synthetic granite tile, which undergoes
the same polishing procedure as natural granite.
Says CG&CRI's G Banerjee, the
principal scientist associated with
the manufacture of synthetic granite,
"The basic design of the tile can be modified to suit the need of the consumer.
We can also control the colour by managing the quantity of additives, but we
cannot make very light coloured tiles,
because the iron present in garnet
imparts a dark hue to it." The lightest
shade of artificial granite tile comes in
beige or tan.
Tiles can be made in various designs
- for example, dots of a particular
colour or a diamond shape can be
incorporated before the tiles are
sintered and do not require any additional process. "This way we can
develop any number of designs and
meet the requirements
of the clients," says Banerjee.
The strength of these
tiles, assures Banerjee, is
almost the same as that of
natural granite. The hard
ness of garnet on Moh's
scale is about 7 (Hardness
scale ranges from 1 to 10
on Moh's Scale, where the hardness of talc is rated as
1, while a diamond is rated as 10).
Banerjee cautions that
synthetic granite should
not be confused with the
artificial granite' tiles
available in the market. The artificial
granite tiles are made up of natural
granite rubble mixed with additives and
are not as sturdy as synthetic granite tiles.
The synthetic granite tiles, when
manufactured on a commercial scak,
would measure 1 foot (0.3048 metre) by
6 inches (0.1524 metre), the same as
natural granite tiles but would be priced
at about two-thirds or half the price of
natural granite tiles, which range from
Rs 60 to Rs 80 per square foot (about
one-tenth of a sq metre).
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