Transactions of the INDIAN CERAMIC SOCIETY Vol. 27 1968
Chemical Decolourisation of Some Indian Clays
S. K. GuHA, S. R. DAS AND SUDHIR SEN
Pages : 54-62
DOI : 10.1080/0371750X.1968.10855631
Abstract
Dissolution of Fe20 3 from clay suspension by various reducing agents at different
pH and temperature was systematically studied. Based on these observations a procedure
was worked out for decolourisation of clays by reducing-their Fe20 3 content.
The method developed involved dispersion of the clay suspension, addition of Na2S20 5
in presence of zinc at controlled pH and after completion of the reactions washing
the decolourised clay free of excess salts, filtering and drying. An important feature
of the process was that no external heating was necessary and it could as such be adopted
as an adjunct to a clay washing plant.
Clays from different regions were studied. In most cases substantial increase in
brightness factor was obtained without showing any deterioration in the other properties.
