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Preparation & uses of silica refractories

FE > Semester 1 > Applied Chemistry 1

Marks : 04

Years : MAY 2016

1 Answer
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The main raw materials used are quartz, sand stone etc. the siliceous rock is crushed and ground with 2% lime and water to form a thick paste so formed is moulded into bricks either manually or using a machine-press after which they are heated to about $1500^\circ C$ for 24 hours. Cooling takes about 1 or 2 weeks.

During heating quartzite converts into crystobalite which during cooling gets converted into tridymite, such that silica bricks are the mixture of these two.

Uses:

• Glass furnaces

• Roofs of electric and hearth furnaces

• Lining of acid converters etc.

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