A process for preparing water glass in dissolved form

摘要

Prodn. of water glass in the liquid form from amorphous silica and an alkali metal hydroxide is improved in that fly ash from the prodn. of iron alloys and from other industries in which silica is present in furnaces is used as a source of silica. The compsn. contains (in pts. wt.): silica dust 1, alkali metal hydroxide 0.35-2.1, and water 1.65-3.6. The compsn. is mixed together and heated to 75-100 degrees C (preF. 85 degrees C) at a heating rate of 1.5-2.5 degrees C/min. The resulting liquid is cooled, pref. naturally cooled in a tank without any cooling means. Water glass having sufficient purity of technical applications is produced in a much simpler and cheaper way than by the conventional method comprising fusing crystalline SiO2 with an alkali metal hydroxide or oxide and dissolving the product in water in an autoclave. The siliceous fly ash is cheap. Consumption of energy is reduced by raising the temp. at the rate specified above.