Fuels and Combustion
Washing of coal

All of these
Controls its ash fusibility and increases its calorific value
Improves its coking properties
Reduces its sulphur and ash content

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Fuels and Combustion
A coal with high ash content is undesirable, as

It is abrasive to the coal pulveriser (ie.g. ball mill) and the combustion chamber
The ash retains the sulphur & phosphorus and thus affects the quality of products in metallurgical furnace apart from increasing the slag volume. Besides, it may fuse and stick to the boiler tubes
The ash in molten condition gets absorbed in the pores of the refractory lining of the furnace and causes its spalling due to different co-efficient of expansion/contraction of the refractory and the
All of these

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