黑液燃烧法绿液除硅绿液硅不溶物的形貌组成及其性能研究

Study on morphology composition and properties of green-liquor-silicon-insolubles from green liquor desilication via black liquor combustion process

采用偏铝酸钠和硫酸镁复配除硅剂进行竹浆黑液燃烧法绿液除硅研究,获得绿液硅不溶物,采用ICP及SEM-EDAX确定组成,采用SEM观察形貌,采用激光粒度仪以及沉降法测定绿液硅不溶物粒径分布、沉降体积和时间评价绿液硅不溶物的沉降性能.研究表明,偏铝酸钠和硫酸镁复配除硅剂具有较好的除硅效果,除硅剂摩尔比Si∶Al∶Mg为1∶0.3∶0.4时,除硅率最高可达86.17%,绿液硅不溶物的球形块状结构最明显,絮聚最明显,同时伴随着表面吸附着更细小的绿液硅不溶物颗粒;除硅剂摩尔比Si∶Al∶Mg为1∶0.35∶0.35,绿液中Al、Mg元素含量最低,除硅率为85.84%,相应的绿液硅不溶物的平均粒径最大,为39μm,粒径主要集中在3~70μm,沉降性能也较好;除硅剂摩尔比Si∶Al∶Mg为1∶0.3∶0.4和1∶0.35∶0.35的绿液硅不溶物Si元素含量最高,为5.82%,后者绿液硅不溶物Al、Mg元素含量高于前者,最终确定除硅剂配比工艺Si∶Al∶Mg为1∶0.35∶0.35.

The green-liquid-silicon-insoluble(GLSI)was obtained through green liquor desilication via black liquor combustion process using NaAlO 2 and MgSO 4 as compound desilication agents in this study.The morphology,composition and properties of GLSI were studied.ICP and SEM-EDAX were used to determine the composition,and SEM was used to observe the morphology.Laser particle size analyzer and sedimentation method were used to measure the particle size distribution,precipitation volume and precipitation time to evaluate the precipitation performance of GLSIs.The results show that NaAlO 2-MgSO 4 compound desilication agent has a good desilication effect.The desilication rate can reach 86.17%and the content of Si element in corresponding GLSIs is the highest 5.82%at the molar ratio Si∶Al∶Mg as 1∶0.3∶0.4.The spherical bulk structure and flocculation of GLSIs are the most obvious,smaller GLSI particles being observed on the surface.The contents of Al and Mg elements in the green liquor are the lowest and the desilication rate is up to 85.84%at the molar ratio of Si∶Al∶Mg as 1∶0.35∶0.35,and the content of Si element in GLSIs is the same as that at the molar ratio Si∶Al∶Mg as 1∶0.3∶0.4.The average particle size of the corresponding GLSIs is mainly in the range of 3~70μm and the largest is 39μm,which elucidates that the precipitation performance is also good.The content of Al and Mg elements of the latter is higher than that of the former,so the molar ratio of Si∶Al∶Mg is determined as 1∶0.35∶0.35.