碱熔融焙烧SiO_2和Zn_2SiO_4反应过程分析

以自制SiO_2和分析纯Zn_2SiO_4为研究对象,NaOH为反应介质,考察了反应温度、物料配比和反应时间对硅提取率的影响.碱熔融焙烧SiO_2的合适反应条件:反应温度450℃,NaOH与SiO_2物质的量比2.4∶1,反应时间60 min.二氧化硅与NaOH反应先生成Na_2SiO_3,随温度升高逐步转化为Na_4SiO_4.碱熔融焙烧Zn_2SiO_4的合适反应条件为反应温度500℃,NaOH与Zn_2SiO_4物质的量比20∶1,反应时间150 min.Zn_2SiO_4与NaOH反应生成Na_2ZnSiO_4和Na_2ZnO_2,在350℃硅氧四面体反应得到Na_2SiO_3,随升温转化为Na_4SiO_4.

Reaction Process Analysis of SiO2 and Zn2SiO4 Roasting with Molten NaOH

Employing homemade SiO₂ and analytic Zn₂SiO₄ as raw materials and NaOH as reaction medium， the influences of reaction temperature， molar ratio of NaOH to SiO₂ and reaction time on the extraction ratio of silica were investigated. The appropriate reaction conditions were obtained as reaction temperature of 450℃， molar ratio of NaOH to SiO₂ of 2.4∶1 and reaction time of 60min. Silica reacted with NaOH to form Na₂SiO₃ at first and then was transformed into Na₄SiO₄ along with temperature rising. The appropriate reaction conditions of Zn₂SiO₄ roasting were reaction temperature of 500℃， molar ratio of NaOH to Zn₂SiO₄ of 20∶1 and reaction time of 150min. Na₂ZnSiO₄ and Na₂ZnO₂ were formed when Zn₂SiO₄ reacted with NaOH. Silicon oxygen tetrahedron reacted with NaOH to form Na₂SiO₃ when the roasting temperature reached 350℃， and then Na₂SiO₃ was transformed into Na₄SiO₄.