焙烧对铝土矿尾矿相转变,失重率及平均粒径与比表面积的影响

Effect of Calcination to the Mineral Phase Transformation,Weight Loss Ratio,Granularity and Specific Surface Area of Bauxite Tailings

本文对铝土矿尾矿以不同温度进行焙烧,采用X射线衍射分析、差热-热重分析、平均粒径与比表面积分析等分析手段详细表征了焙烧温度对铝土矿尾矿主要矿物的矿相转变,尾矿的失重率及平均粒径与比表面积的影响。结果表明尾矿中的一水硬铝石及高岭石在600℃以前完全分解,分别转化为刚玉相及偏高岭石相;伊利石在500℃以上开始脱水生成脱水伊利石相;石英相、赤铁矿相与锐钛矿相基本无明显变化;由于一水硬铝石及高岭石在400~600℃之间完全脱除结构水,尾矿在此温度区间剧烈失重8.4%左右;随焙烧温度的提高,铝硅酸盐矿物逐步脱水分解导致尾矿的平均粒逐渐减小,比表面积逐步增大;但高于800℃以上,在脱水伊利石相与赤铁矿相接触面处,由于K2O-SiO2-Al2O3-Fe2O3四元系低熔点化合物的生成,尾矿颗粒产生粘结,导致尾矿的平均粒径转而上升,比表面积转而下降。

Bauxite tailings were calcined under varied calcining temperatures in this paper. The mineral phase transformation of bauxite tailings under varied calcining temperatures were detailed investigated by XRD analysis. It indicated that,the diaspore and kaolin in bauxite tailings decomposed completely before600 ℃,corundum and meta-kaolin were generated therewith. Illite was beginning to dehydrate at 600 ℃and transformed to dehydration illite. Quartz,Hematite and Anatase didn ＇t change. TG-DSC analysis indicated that bauxite tailings loss 8. 4% weight during 400-600 ℃,due to the decomposition of diaspore and kaolin. The granularity of bauxite tailings decreased before 800 ℃ and increased after 800 ℃,specific surface are on the contrary therewith,due to the glass phase generated at the contact area of dehydration illite and hematite.