Ceramic – Glass
Raw materials for Glass manufacturing:
The BS2975 will list the parameters like minimum level of Silica required; maximum level of other metallic elements like aluminium, iron, chromium, copper, cobalt, nickel and vanadium; maximum alkali content allowed in the sand; particle size distribution required for each grade and the permissible heating loss in each grade. The standards will also specify the amounts by which each of the above parameter can vary. The sand has to undergo extensive physical and chemical processing to meet the above mentioned parameters.
The processing involves crushing, screening, removing contaminating impurities in the sand and adjusting the grain-size distribution of the quartz grains. If there are metallic oxides in silica sand then it can be used for making coloured glass. If iron is present, the resulting glass is coloured green or brown. If there is iron in silica sand then that cannot be used for making Clear glass. Hence sands used to manufacture colourless glass are therefore likely to be processed further by methods such as acid leaching, froth flotation or gravity separation.
To be Contd….
