溶液结晶法制取五水正硅酸三钠

Preparation of sodium silicate pentahydrate by aqueous crystallization method

以工业液体硅酸钠和氢氧化钠为原料,采用溶液结晶法制取五水正硅酸三钠(Na3HSiO4·5H2O)产品.从化学反应和Na2O-SiO2-H2O三元系相图分析入手,经过反复实验,确定首次结晶时的原料配比、母液循环时的原料配比,确定反应温度85～95 ℃,反应时间0.5～1.0 h,结晶温度25～50 ℃,结晶时间4～5 h,晶种加入温度50 ℃,并在25 ℃时保温0.5 h,在此条件下制得五水正硅三钠浆液,浆液经离心分离和干燥,得到了与理论技术指标接近的五水正硅酸三纳产品(氧化钠质量分数37.1%,二氧化硅质量分数22.2%,二氧化硅与氧化钠物质的量比0.62).实验样品用于冷轧带钢电解清洗效果良好.

The peparation of sodium silicate pentahydrate （ NasHSiO4 · 5H2O）from water glass and caustic soda by agueous crystallization method is introduced. Through the analysis of chemical reaction and phase diagram of Na2O - SiO2 - H2O system and experiments, the ratio of feed during the period of primary crystallization and mother liquor circulation is determined. Under the following conditions： reaction temperature 85 - 95 ℃, reaction time 0.5 - 1.0 h. Crystallization temperature 25 -50 ℃ ,crystallization time 4 -5 h,seed - adding temperature 50 ℃ and keeping 25 ℃ for 0.5 h,the slurry of sodium silicate pentahydrate can be obtained. After centrifugal seperation and drying, the finished product sodium silicate pentahydrate（ Na2O 37.1% ,SiO2 22.2% SiO2/Na2O 0. 62）is produced. The good result can be got when the sample used in the cleaning for cold - rolling strip steel.