酸浸工艺脱除微硅粉杂质离子及其对热碱溶解过程的强化

针对热碱溶解微硅粉制备水玻璃的过程中存在Si转化率较低的问题,提出了采用酸浸预处理的方法脱除微硅粉中的金属杂质,强化其热碱溶出过程,以提高Si的转化率。本研究通过采用X射线荧光仪(XRF)、冷场发射扫描电子显微镜与能谱分析仪(SEM-EDS)、X射线衍射仪(XRD)以及滴定分析检测方法,研究了酸种类、酸浓度、反应温度、固液比、反应时间对金属杂质浸出率的影响和酸浸工艺对微硅粉热碱溶出过程的强化作用,得出适宜的酸浸条件:HCl浓度2mol/L、反应温度60℃、固液比1:(6～8)、反应时间40～60min。在碱溶出过程初期,酸浸处理后的微硅粉中SiO₂的溶出率由46.62%增至61.91%,得到了显著提高。结果表明:酸浸预处理对微硅粉的碱溶过程起到很好的强化作用,提高了Si的转化率,这将在增大微硅粉利用率的同时也有利于满足工业水玻璃Na₂O·(2.5～3)SiO₂]对模数的要求。

Impurity ions of micro silicon powder removal by acid leaching and intensification to the hot alkali dissolving process

In the process of sodium silicate preparation with hot alkali dissolving micro silicon powder,silica conversion is low. A new approach of acid leaching pretreatment to removing the metal impurity of micro silicon powder was proposed in this study. The method can strengthen the hot alkali dissolution process and improve the conversion rate of silica. The effects of acid types,acid concentrations,temperatures,solid-liquid ratio and reaction time on leaching rate of metal impurities were investigated by X-ray fluorescence spectrometer(XRF),ice emission scanning electron microscope and energy spectrum analyzer(SEM-EDS),X-ray diffractometer(XRD)and titration analysis. The reinforcement of the acid leaching process of micro silicon powder on hot alkali dissolution process was also studied. The appropriate reaction condition was as follows:2mol/L HCl,reaction temperature 60℃,solid-liquid ratio 1:(6—8),the reaction time 40—60min. At the beginning of the dissolution process,the dissolution rate of micro silicon powder,after acid leaching,was improved from 46.62% to 61.91%. The results showed that the pretreatment of micro silicon powder with acid leaching had good strengthening effect on the dissolution process,and raised the transformation rate of silica. This will increase the utilization ratio of micro silicon powder as well as to meet the module claim industrial sodium silicateNa₂O·(2.5—3)SiO₂].