Method of producing low-carbon, white husk ash

Claim 1

In a method of producing low-carbon, white rice husk ash suitable for the production of building materials, and more particularly refractory building materials, in which method, for purposes of removing volatile constituents and for purposes of transforming the fixed carbon into a gaseous compound, the rice husks are heated to a temperature below the crystallization temperature of the SiO 2 of the rice husks, whereupon the resultant husk ash is heat-treated at a temperature above the crystallization temperature of the SiO 2 for the purposes of obtaining a uniform SiO 2 crystal structure, the improvement comprising: the first step of heating the rice husks to a first relatively low separation temperature within the range of from 200° to 450° C. in the absence of air, exclusively for separating the volatile constituents that are capable of after-burning; subsequently the second step of heating the rice husks free of volatile constituents to a gasification temperature in the range of from 450° to 550° C. while feeding an oxidizing agent thereto for transforming the fixed carbon into a gaseous phase prior to heat treatment; and the third step of subsequently heating the thus obtained rice husk ash to a heat treatment temperature in the range of from 700° to 800° C.