PROCESS FOR HYDROTHERMAL PRODUCING SODIUM-SILICATE SOLUTIONS OF HIGH SIO2:NA2O MOLAR RATIO

摘要

In a hydrothermal process for preparing sodium silicate solutions with a high SiO2:Na2O molar ratio, a crystalline silicon dioxide is reacted with an aqueous solution of sodium hydroxide. The process is characterized in that the crystalline silicon dioxide used is a quartz tempered at temperatures from 1100 DEG C up to its melting point, and that this tempered quartz is reacted with an aqueous solution of sodium hydroxide at a concentration between 10 and 50 wt.%, in a closed pressure reactor at temperatures between 150 and 300 DEG C and under saturated water vapour pressures corresponding to these temperatures.