Abstract: To utilize solid-waste coal gangue as a resource,a slurry was prepared by mixing coal gangue powder (d₅₀=75 μm),CaCO₃ powder (d₅₀=75 μm),and α-Al₂O₃ powder (d₅₀=5 μm) at a mass ratio of 6∶3∶1,with 35 mass% distilled water added.Then,2 mass% composite foaming agent NS-Ⅲ was added to the slurry to form a foamed slurry.The foamed slurry was poured into a 100 mm×100 mm×50 mm mold.The demolded green body was first dried at 100 ℃ for 24 h and then fired at different temperatures (1 200,1 250,1 300,and 1 350 ℃) for 3 h to fabricate anorthite insulating refractories.The effects of the heat treatment temperature on the phase evolution,microstructure and properties were investigated.The results show that (1) with the increasing heat treatment temperature,the diffraction peak intensity of anorthite and mullite gradually increases,the anorthite crystals increase and gradually develop from short columnar to lamellar;the bonding among crystals gradually densifies;the bulk density,linear shrinkage and thermal conductivity of the samples decrease firstly and then increase,while the apparent porosity shows an opposite trend,and the cold compressive strength gradually rises;(2)when the heat treatment temperature is 1 300 ℃,the sample exhibits the optimal overall performance,with the bulk density of 0.48 g·cm^-3,apparent porosity of 84.3%,cold compressive strength of 1.80 MPa,and thermal conductivity at 1 000 ℃ of 0.139 W·m^-1·K^-1,and the anorthite crystals in the sample show lamellar morphology and bond closely,which makes the sample suitable for long-term service at high temperatures.

Key words: insulating refractories, anorthite, coal gangue, phase composition, microstructure, thermal conductivity

摘要： 为资源化利用固体废弃物煤矸石,以质量比为6∶3∶1的d₅₀=75 μm的煤矸石粉、d₅₀=75 μm的CaCO₃粉和d₅₀=5 μm的α-Al₂O₃粉,加35%(w)的蒸馏水制成料浆,再加入2%(w)的NS-Ⅲ型复合发泡剂制成泡沫料浆,将其注入100 mm×100 mm×50 mm的模具中,坯体脱模后经100 ℃干燥24 h再热处理,制备了钙长石隔热耐火材料。系统研究了热处理温度(1 200、1 250、1 300、1 350 ℃保温3 h)对试样物相组成、显微结构和性能的影响。结果表明:1)随热处理温度的升高,试样中钙长石和莫来石衍射峰的强度逐渐增强,钙长石晶体的形貌逐渐由短柱状发育成为板片状,且数量增多、各晶体间结合逐渐致密化,试样的体积密度、线收缩率和热导率均呈先降低后升高趋势,显气孔率的变化趋势则与之相反,常温耐压强度逐渐增强。2)当热处理温度为1 300 ℃时,试样综合性能最佳,其体积密度、显气孔率、常温耐压强度和1 000 ℃时的热导率分别为0.48 g·cm^-3、84.3%、1.80 MPa、0.139 W·m^-1·K^-1,试样中钙长石晶体为板片状,且各晶粒间结合致密,适于在高温下长期作为隔热耐火材料使用。

关键词: 隔热耐火材料, 钙长石, 煤矸石, 物相组成, 显微结构, 热导率