bleaching kaolin process

the bleaching clays - usgs

kaolin minerals appear to be the product of extreme weathering of kinds of i_gneous rocks and are highly stable. the bleaching clays appear to be composed chiefly of the less and less completely weathered clay minerals. they are characterize by high contents of loosely held water and by :partial solubility in di ute

process for bleaching kaolin - imc chemical group

i claim: 1. in a process for treating raw kaolin clay to improve the color and brightness by bleaching the clay in an aqueous dispersion with sodium dithionite the improvement consisting of treating the dispersion with hydroxylamine or salt thereof within about 1 to 5 hours after the treatment with sodium dithionite is complete.

reduce bleaching for kaolin - 911metallurgist.com

a process for producing reductive bleach in-situ in kaolin slurries has been developed. the bleach is formed by mixing an iron sponge powder (-325m) with slurry treated with so2. the process has been successfully demonstrated in production and applied to several grades. the color brightness and viscosity of the bleached product is equivalent to or better than that of product bleached with

us4002487a - process for bleaching kaolin - google patents

in a process for treating raw kaolin clay to improve the color and brightness by treating the clay in an aqueous dispersion with sodium dithionite the improvement consisting of treating the dispersion with hydroxylamine or salt thereof after the treatment with sodium dithionite is complete.

ep1146089a1 - methods for bleaching kaolin clay and other

improved methods for bleaching kaolin clay and other minerals are provided. more particularly methods of the present invention employ a hydrosulfite or bisulfite material and a second reducing agent preferably a reducing agent that contains a group iii element such as a borohydride to increase the brightness of kaolin clay and other minerals and reduce color present therein.