利用氧氯化锆副产物合成硅酸钠的实验研究

Preparation of Sodium Silicate from By-production of Zirconium Oxy-chloride

利用氧氯化锆生产中排放的锆硅渣和废碱液作原料,通过水热-碱化反应合成硅酸钠。先将酸性硅渣与废碱液中和,经离心水洗得到中性二氧化硅凝胶,再在反应釜中与计量的NaOH溶液进行化合反应,然后对产物进行固液分离,最后将所得溶液浓缩即得产物。通过正交试验,研究了影响SiO2溶出率及硅酸钠模数的主要因素。结果表明,起始物的n(SiO2)/n(Na2O)比影响最大,其次依次为反应温度和反应时间。最优方案按n(SiO2)/n(Na2O)=2.5配制起始物,180℃下反应3 h,由此可使锆硅渣的SiO2溶出率达82%,合成的硅酸钠模数为2.21,其各项技术指标均达到国标优等品水平。

The silica residue containing zirconium and waste alkali liquor were used for the preparation of sodium silicate by hydrothermal-alkaline reaction. The neutralized SiO2 gel, which the silica residue containing zirconium was blended with waste alkali liquor, reacted with stoichiometric NaOH liquor in the reactor, and the product was obtained by concentrated solution which was from solid-liquid separation. Through orthogonal experiment,the influence of correlative parameters on the deliquescent rate of SiO2 and modulus of sodium silicate was discussed. The orthogonal experimental results were analyzed, and drew the conclusion that the deliquescent rate of SiO2 was the most important factor, while the second one was reaction temperature and the last one was reaction time. The optimal product was obtained after reacted for 3 h at 180℃, when the mole ratio of initial reactant materials（SiO2 to Na2O）was equal to 2.5. It was verified that the deliquescent rate of SiO2 of the optimal scheme was 82% and the modulus was 2.21, and the function of the final product achieved classy level of national standard.