杂质硅对锌酸钠溶液结晶过程的影响机理研究

Influence Mechanism of Impurity Silicon on Crystallization Process of Sodium Zincate Solution

研究了杂质硅对锌酸钠溶液结晶过程的影响规律,通过结晶物相和热力学研究了杂质硅对锌酸钠溶液结构的影响.通过分析锌酸钠溶液的分解行为,考察了杂质硅浓度、晶种和温度等参数对锌酸钠溶液结晶过程的影响规律.结果表明,存在一个临界硅浓度,当硅浓度高于临界硅浓度时,杂质硅抑制结晶过程的进行;当硅浓度低于临界硅浓度时,杂质硅促进结晶过程的进行.以氧化锌作为晶种时,35,50和60℃时临界硅浓度分别为0.20~0.40,0.054~0.20和0~0.054 g/L.以氢氧化锌作为晶种时,35℃时临界硅浓度为0.20~0.40 g/L.临界硅浓度随温度的升高而降低.硅浓度低时,物相为多面体形的ε-Zn(OH)_(2);硅浓度高时,物相为纳米棒和长方体形的γ-Zn(OH)_(2),提高温度可以抑制γ-Zn(OH)_(2)的生成.硅杂质的存在可能促使锌酸钠溶液的结构发生了重构,使锌酸钠溶液中锌元素以Zn(OH)+的形式存在,升高温度则可减弱杂质硅的影响.

Effect of impurity silicon on the crystallization process of sodium zincate solution was studied.Based on the crystal phase and thermodynamics analysis,the influence mechanism of impurity silicon on the structure of sodium zincate solution was obtained.The decomposition behavior of sodium zincate solution was analyzed.The effects of impurity silicon concentration,crystal seed and temperature on the crystallization process of sodium zincate solution were investigated.The results show that there is a critical silicon concentration.When the silicon concentra⁃tion is higher than the critical silicon concentration,the impurity silicon inhibits the crystallization process;when the silicon concentration is lower than the critical one,the impurity silicon promotes the crystallization process.When zinc oxide is used as crystal seed,the critical silicon concentration at 35,50,and 60℃are in the range of 0.20—0.40,0.054—0.20 and 0—0.054 g/L,respectively;when zinc hydroxide is used as crystal seed,the critical silicon concentration is in the range of 0.20—0.40 g/L at 35℃.The critical silicon concentration decreases with increasing temperature.When silicon content is low,the phase isε-Zn(OH)_(2)of polyhedron;when silicon content is high,the phase isγ-Zn(OH)_(2)of nanorods and cuboids.Increasing the temperature can inhibit the formation ofγ-Zn(OH)_(2).The presence of silicon impurities may reorganize the structure of sodium zincate solution,and is conducive to the existence of zinc ions in the form of Zn(OH)+.The increase of temperature can reduce the influence of silicon impurities.