不同温度下赤泥的物理化学特征分析

Characterization of Red Mud Thermally Treated at Different Temperatures

对未经任何加热处理的常温赤泥的XRD、TG-DTA、IR分析表明,经露天长久放置的陈赤泥中结晶态物质主要为碳酸钙(以方解石为主,少量霰石)和钙钛矿。电子显微镜观察表明,组成赤泥团聚体的一次粒子尺寸极其细小,外形极不规则;对赤泥颗粒的微区电子衍射分析则进一步表明,赤泥粒子中有相当部分为化学组成变动不定的无定形铝硅酸盐物质。在室温到900℃之间的加热处理过程中,赤泥中吸附水和结晶水的脱除于600℃之前基本完成,620℃-760℃发生碳酸钙的分解;700℃时β-C2S开始形成,800℃后大量形成;钙钛矿在整个加热处理过程中的表现为惰性。TMS-GC在900℃加热处理时赤泥的分析还表明,赤泥中的硅酸盐物质有38.59%为单体,6.68%为二聚体,3.27%为环三聚体,其余为高聚体。

The physicochemical reactions occurred during the heating process between ambient and 900?℃ was traced by means of TG-DTA,XRD,and IR analysis.Results from TG-DTA,XRD,and IR analysis showed that the main crystalline substances existed in aged red mud which were exposed in atmosphere for a long time are calcium carbonate,mostly calcite and little aragonite,and perovslite.Electronic microscope observation and analysis showed that the red mud agglomerate was actually composed of very fine first particles which were in irregular outline and variable chemical composition,and most of them being amorphous alumino-silicates.Furthermore,it was proved that the absorbed water and crystalline water in red mud were found to be driven out before 600?℃ during heating from ambient to 900?℃,the decomposition of calcium carbonate took place between 620?℃ and 760?℃,the formation of β-C_2S was detected to begin at 700?℃ and continually to form thereafter,whereas perovskite remained unchanged during heating.TMS-GC analysis on the 900?℃heated red mud indicated that the silicate anions in that red mud comprised 38.59% monomer,6.68% dimmer,3.27% trimer and others.