Process for the continuous preparation of sodium metasilicate

摘要

Pulverulent sodium metasilicate is prepared by reaction of silica sand with sodium hydroxide at a molar NaOH/SiO2 ratio of 2.1:1 to 4:1. This is done by continuously feeding solid, dissolved or molten sodium hydroxide and silica sand into a horizontal tubular reactor, intensively mixing the reaction mixture perpendicular to the tubular reactor axis and slowly advancing the mixture in (along) the direction of the tubular reactor axis. The mixture is heated to temperatures of 250 to 400 DEG C and maintained at this temperature until the initially formed paste-like phase has been processed to give a powder. Steam and sodium metasilicate powder are continuously removed from the reactor.