以矾土和煤矸石烧结合成刚玉和莫来石

Corundum and mullite synthesized from bauxite and coal gangue

为了提高高铝矾土资源的综合利用率,并促使矾土熟料在质量、品种和价格上升级,以高铝矾土和煤矸石为原料,配制成w(Al2O3)分别为90%、80%、70%和60%的试样,通过均化(细磨、混练)、成型、烘干后,分别在1450℃、1500℃、1550℃、1600℃、1650℃和1700℃保温3h煅烧,测定煅烧后试样的显气孔率、体积密度和烧后线变化率,以此确定各试样的烧结温度;还测定了烧结试样的荷重软化开始温度,并采用XRD和SEM分析了烧结试样的相组成和显微结构。结果表明:w(Al2O3)为90%、80%、70%和60%的试样的烧结温度分别为1550℃、1550℃、1700℃和1650℃,各烧结试样的荷重软化开始温度分别为1450℃、1500℃、1600℃和1550℃,并且烧结试样的纯度和密度均很高(w(Al2O3+SiO2)>93.5%,显气孔率<3%)。由于w(Al2O3)为70%和60%的试样在煅烧过程中二次莫来石化较多,玻璃相含量较少,因此其烧结温度相对较高;同时,由于这两个试样烧结后有发育良好的棱柱状莫来石构成的连续的网络结构,因此其荷重软化开始温度相对较高。

Study focused on to improve the comprehensive utilization of bauxite resource and the optimization of quality,variety and price of bauxite chamotte. Specimens with Al2O3 about 90% ,80% ,70% and 60% were prepared using bauxite and coal gangue as starting materials. These specimens were homogenized （by fine milling and mixing） ,pressed and dried,then fired at 1450℃,1500 ℃,1550 ℃,1600℃,1650 ℃ and 1700 ℃ for 3 h. The apparent porosity, bulk density and linear shrinkage of fired specimens were analyzed to determine their sintering temperature. Moreover, refractoriness under load（ RUL）, phase composition and microstructure of sintered specimen were determined and analyzed by XRD and SEM. The results showed that the sintering temperature of specimens with Al2O3 of 90%, 80%,70% and 60% were 1550 ℃, 1550℃, 1700 ℃ and 1650 ℃separately,and their RULs were 1450 ℃,1500 ℃,1600 ℃ and 1550 ℃ separately. The sintered specimens showed high purity and bulk density （w（Al2O3 ＋SiO2） 〉93.5%, apparent porosity 〈3% ）. When the specimens with Al2O3 60% and 70% were fired,the secondary mullitization was higher and glass phase less,resulting in higher sintering temperature. Simultaneously,both of them had structure of continuous interlocking network by columnar mullite,so the refractoriness under load was relatively higher.