Abstract: In order to address the challenges of high load and high thermal conductivity of refractory materials in the firing zone of cement rotary kilns,suitable lightweight aggregates for cement kilns were developed.Foaming slurries were first prepared employing light-burned magnesia powder as the raw material,sodium dodecyl benzene sulfonate (SDBS) as the foaming agent,triethanolamine (TEA) as the dispersant,and TiO₂ as the sintering aid.Then MgO foam slurries were prepared,and lightweight magnesia aggregates were successfully synthesized after firing the MgO foam slurries at 1 600 ℃ for 2 h.The effects of the TiO₂ addition (0,0.5%,1.0%,1.5%,2.0%,and 2.5%,by mass)on the properties and microstructure of magnesia foam slurries and lightweight magnesia aggregates were investigated.The results show that (1)TiO₂ surface hydroxylates;as the TiO₂ addition increases,the viscosity of the foam slurries increases,while the surface tension and contact angle decrease;the average size of the bubbles in the slurries ranges from 114.30 to 53.76 μm;(2)TiO₂ reacts with CaO in the light-burned magnesia powder,forming CaTiO₃;as the TiO₂ addition increases,the average grain size of magnesia increases,the amount of intergranular pores decreases,the bulk density of the lightweight aggregates increases,and the apparent porosity decreases;(3)the optimum physical properties were achieved when the TiO₂ addition was 1.0%.

Key words: lightweight magnesia aggregate, microstructure, hydroxylated TiO₂

摘要： 为了改善水泥回转窑用烧成带耐材的高负荷和高导热问题,开发适用于水泥窑的轻质骨料。以轻烧氧化镁粉为原料,十二烷基苯磺酸钠为发泡剂,三乙醇胺为分散剂,TiO₂为助烧剂,先制取镁质泡沫料浆,再于 1 600 ℃下保温2 h热处理制备镁质轻质骨料。研究TiO₂加入量(加入质量分数分别为0、0.5%、1.0%、1.5%、2.0%和2.5%)对镁质泡沫料浆及镁质轻质骨料性能和显微结构的影响。结果表明:1)TiO₂表面发生羟基化,随TiO₂加入量增加,泡沫料浆黏度增加,表面张力和接触角减小,料浆内气泡平均直径为114.30~53.76 μm;2)TiO₂与轻烧氧化镁粉中的CaO反应生成CaTiO₃,随TiO₂加入量的增加,氧化镁晶粒平均尺寸增大,晶间气孔减少,轻质骨料试样的体积密度增大,显气孔率减小;3)当TiO₂加入量为1.0%(w)时,试样物理性能最优。

关键词: 镁质轻质骨料, 显微结构, 羟基化TiO₂