溶出过程中三水铝土矿微观结构的变化

研究了三水铝土矿在铝酸钠溶液的溶出过程(液-固反应)中颗粒微观结构的变化规律.利用ASAP2020Micrometitics测量仪及扫描电子显微镜分别检测了颗粒的比表面积、孔隙结构(孔隙平均尺寸和体积)和表观结构.用BET法、Langmiur法、t-plot法及BJH法分别计算了颗粒的比表面积,同时用BJH法还计算了颗粒的孔隙结构.结果表明:颗粒比表面积和孔隙体积有相同的变化规律,即随溶出时间延长先增加后稍有减小;孔隙平均尺寸呈先减小再稍增加后降低;SEM照片显示三水矿颗粒的表面结构在溶出过程中逐渐变得疏松;在三水铝石的溶出过程中,矿石颗粒与溶液的接触面积不与颗粒直径的平方成正比.

Microstructural Change of Gibbsite Particle in Digestion Process

The change of microstructure of the gibbsite particle while digesting in sodium aluminate solution (liquid-solid reaction) was studied. The ASAP 2020 micrometric apparatus and SEM were employed to determine the specific surface area of particles, pore structure including average pore size and volume and apparent structure. The BET, Langmuir, t-plot and BJH methods were all used to calculate the specific surface area of gibbsite particles with the pore structure of particles calculated by the BJH method. The results showed that both the specific surface area of particles and pore volume increase then decrease slightly with prolonged digestion time, while the average pore size changes in a decrease-increase-decrease process. The SEM images showed that the surface structure of gibbsite particles becomes looser gradually in digestion process. A conclusion is therefore drawn that the surface area of gibbsite particles in contact with solution is not in direct proportional to the square of particle radius in the process of gibbsite dissolution in alkali solution.