以矾土碎矿和煤矸石合成莫来石均质料

Preparation of homogenized mullite grogs with broken bauxite and coal gangue

采用Ⅰ等高铝矾土碎矿、Ⅱ等高铝矾土碎矿分别与煤矸石配合,并加入活性Al2O3调整m(Al2O3)/m(SiO2),按照矾土基莫来石均质熟料w(Al2O3)=68%～72%的要求,共配成6个混合料,将混合料湿磨至粒度≤0.044mm以均化化学成分,经成型、干燥后分别在1550℃、1600℃、1650℃和1700℃煅烧3h,冷却后测定其显气孔率和体积密度,以确定它们的烧结温度。结果表明:均质料的烧结温度为1700℃;在1700℃烧结制成的矾土基莫来石均质熟料的Al2O3含量为68%～72%,显气孔率<2.5%,体积密度≥2.75g·cm-3,其莫来石晶体发育良好,构成网络结构。同时,还将部分试样分别在800℃、1000℃、1200℃、1300℃、1400℃、1500℃、1600℃、1650℃和1700℃保温3h,测量其烧后线收缩率和显气孔率,并用XRD分析其相组成,据此分析试样在不同温度下所发生的反应。结果表明,试样在1000～1700℃加热过程中的变化可分为3个阶段:1000～1200℃的一次莫来石形成阶段,1200～1500℃的二次莫来石化阶段,以及1500～1700℃的液相烧结阶段。

Six kinds of mixtures are prepared by synthesizing broken bauxite grade Ⅰ ,grade Ⅱand coal gangue and adding active Al2O3 according to formula w（Al2O3） = （68% -72% ） in bauxite based homogenized mullite grogs. Milling these mixtures to particle size ≤0.044 mm by wet milling to homogenize chemical composition, and calcining the materials at 1550 ℃, 1600 ℃, 1650 ℃ and 1700 ℃ for 3 h respectively after moulding and drying. Finally, after cooling them down, confirm their sintering temperature by determining apparent porosity and bulk density. Results show that sintering temperature is 1700 ℃,at which bauxite based homogenized mullite grogs are with 68% -72% Al2O3, apparent porosity 〈2.5% and bulk density ≥2.75 g · cm^-3 ,and with well developed mullite crystal and network structure. Simultaneously, some specimens are calcined respectively at 800 ℃,1000 ℃,1200 ℃,1300 ℃,1400 ℃,1500 ℃,1600 ℃,1650℃ and 1700℃ for 3 h,then their linear shrinkage and apparent porosity were determined and phase compositions were analyze by XRD, so as to evaluate their chemical reactions at different temperatures. Results show that the changes of the specimens during heating from 1000 ℃ to 1700 ℃ are found to proceed in three stages：formation of primary mullite from 1000 ℃ to 1200 ℃,secondary mullitization from 1200 ℃ to 1500 ℃,and liquid phase sintering from 1500 ℃ to 1700 ℃.