Transactions of the INDIAN CERAMIC SOCIETY Vol. 61 2002
On the Chemical Leaching of Kaolins and their
Thermally Treated Products
Sathy Chandrasekhar and S.Ramaswamy
Pages : 87-92
DOI : 10.1080/0371750X.2002.10800033
Abstract
Two Indian kaolins of different origins and containing different
types of iron minerals were subjected to leaching by
citrate-dithionite-bicarbonate (COB) method and also using
dilute sulphuric acid. The kaolins were calcined at various
temperatures from 400° to 1200°C and the products were
also chemically leaured in a similar way. The percentages
of iron and aluminium in the clays and their calcined products
before and after leaching were determined. The change in
optical properties of the samples on COB treatment was
also found out. The removal of iron and aluminium was correlated
with the structural change occurring in kaolinite
during calcination. The optical properties were found to
improve by the removal of iron, which was again dependent
on the temperature of calcination.