Abstract:
Process and flow sheet development for the
beneficiation of China clay remains always unique to each
deposit since the mineral characteristics changes from
deposit to deposit. The difference in characteristics has got
a great bearing on the geological formation, setting and the
transformation of the resource over millions of years. Each
clay deposit differs in its type and extent of impurities,
particle size distribution, pH and other characteristics.
Hence it is imperative that flow sheet for beneficiation for
any clay can be made only after detailed laboratory processing
studies. The present paper discusses about the
above mentioned aspect by carrying out process development
studies on five typical clays from different states of
India, viz., Mamuara clay from Kutch (Gujarat), Thonnakkal
Pink clay from Trivandrum (Kerala), Thonnakkal
Grey clay from Trivandrum (Kerala), Koraput clay from
Orissa and Guda clay from Bikaner, Rajasthan so as to
bring out the vagaries in process and develop flow sheet.
Studies shows that, besides the normal operations, high
gradient magnetic separation and calcination are essential
for Mamuara clay so as to get a premium grade calcined
clay, reductive bleaching is unavoidable for Thonnakkal
Pink clay, shear-floc flotation is required for Thonnakkal
Grey clay to remove graphite and a non-conventional (pH
controlled) water washing is required for Koraput clay
even before blunging since it is highly acidic (pH 1.7).
Finally, Guda clay responds only to magnetic separation
and can not be upgraded to any premium grade Incidentally, reductive bleaching, flotation and selective
flocculation are not effective for Guda clay. Thus the
investigations reveal that each deposit needs different unit
operations and hence different beneficiation flow sheets.
