TWO-STAGE PROCESS FOR THE PRODUCTION OF CONCENTRATED SODIUM SILICATE SOLUTIONS FROM SODIUM SILICATE LUMP GLASS AND THIN LIQUORS

摘要

ABSTRACT OF THE DISCLOSUREAqueous sodium silicate solutions containingat least 26% of SiO2 and having a ratio of weight ofSiO2 to Na2O of from 2.0 to 3.0 can be obtained usingthin or waste liquor containing at most 20% of NaOHproviding: A) solid sodium silicate glass having aratio by weight of SiO2 to Na2O of from 3.0 to 3.5 isfirst dissolved in alkali-free water at 135° to 155°Cunder the autogenous vapor pressure of the water untilan aqueous sodium silicate solution containing more than20% by weight and less than 30% by weight of SiO2 isformed, after which thin liquor containing at most 20%of NaCH is added in such a quantity as to produce ratiosby weight of SiO2 to Na2O of from 1.8 to 2.6 in themixture of the two components; B) more solid sodiumsilicate glass is dissolved in this mixture until aconcentration of at least 23% of SiO2 in solution isreached. A high volume-time yield for minimal energyconsumption and maximal utilization of dilute wasteliquor is obtained.