In India, most of the washing plants follow a very simple process of beneficiation: The mined clay boulders are first crushed into small lumps and mixed with water and sodium silicate in a high speed blunger. The blunged slurry is then passed through a series of sieve (filter) systems starting from coarse to fine ones.
The sieved slurry is allowed to settle down in tanks where in ‘The Gravity Settling’ principle is used for separating the coarser particles from finer particles. The settled clay is then pumped into filter presses where filter cakes are formed. In small scale industries the cakes are dried in open sun heat and delivered to the end users.
In larger industries, hot air is used for drying. Due to very high demand for china clays in all ceramic products like ceramic tiles, ceramic sanitary wares, ceramic art wares, refractaries, paints, paper, medicine etc., these clay industries are gaining more importance and hence many advanced technologies are being introduced for large scale production.
To be continued………
