垃圾焚烧炉用赤泥质蓄热陶瓷的研究

Red Mud Thermal Storage Ceramic for Waste Incinerator

以拜尔法赤泥和页岩为主要原料，采用无压烧结制备了赤泥质蓄热陶瓷。研究了蓄热陶瓷配方组成和烧结温度对材料烧结性能和力学性能的影响。利用XRD、SEM等测试手段对样品的物相组成、微观结构、力学性能和热学性能进行了表征。结果表明：经1040℃烧成样品（G4配方）性能最优，吸水率为21．27％，气孔率为39．19％，体积密度为1．84g／cm^3，抗折强度达33．32MPa；经30次热震（在空气中气冷，25-800℃）后，样品未开裂，样品的抗折强度损失为2．56％，热膨胀系数为10．48×10^-6℃^-1，蓄热密度随温度升高而增大，600℃时，蓄热密度达445．28kJ／kg。XRD分析结果表明，样品热震前后的主晶相为鳞石英、赤铁矿和蓝晶石；SEM研究表明，热震前及热震后样品存在着较多的闭气孔和连通气孔，尺寸在1～20μm之间，样品中有大量板条状和柱状晶粒生成。赤泥质蓄热陶瓷可望用作垃圾焚烧炉的蓄热材料。

The thermal storage ceramics were prepared from red mud of Bayer process and shale as main raw materials by pressureless firing method. The composition, microstructure, mechanical properties and thermal properties of the sam-ples were tested by XRD, SEM, etc. The results showed that the best performance with the water absorption was 21.27%,the porosity was 39. 19%, the bulk density was 1. 84 g/cm^3 , the bending strength was 33. 32 MPa, and the coefficient of thermal expansion was 10.48×10^-6℃C^-1 when the thermal storage composite ceramic of samples G-4 were fired at 1 040 ℃ for 2 h. The G-4 samples can withstand 30 thermal shock test cycles without racking（wind cooling from 800 ℃ to 25 ℃）,and the bending strength after the thermal shock test only decreased 2. 56 %. It indicated that thermal storage density was increasing with rising temperature, and thermal storage density was 445.28 kJ/kg. The examination of the phase composition indicated that tridymite, hematite and kyanite were the predominant phases compositions. Analysis of the microstructure showed that there were many vent holes and closed pores with the size of 1-20 μm,and a mass of lath-shaped and columnar crystals were distributed desultorily in the samples, showing a good thermal shock resistance. The ceramic made by red mud expected to be used as a high temperature thermal storage ceramic for the heat storage sys-tem of waste incinerator.