Preparation Of Novel Red Mud, Yellow River Silt Sintered Bricks And The Study Of Its Properties And Sintering Mechanism

In this paper, sintered bricks were prepared from red mud (RM), Yellow River silt (YRS) and clay (CL) by extrusion molding and sintering. RM-CL sintered brick and RM-YRS sintered brick were prepared successively, and their preparation conditions, important properties and sintering mechanisms were investigated.Based on weight loss on ignition, density, sintering shrinkage, water absorption and compressive strength, the optimum preparation conditions were determined through single factor experiment. For RM-CL sintered brick, it was sintering temperature of1050℃, sintering time of2h and RM content of20%. For RM-YRS sintered brick, it was sintering temperature of1050℃, sintering time of2h and RM content of40%. The weight loss on ignition, density, sintering shrinkage, water absorption and compressive strength of RM-CL sintered brick prepared under the optimum conditions were10.32%,1.69g/cm3,5.71%,19.91%and36.5MPa, respectively. The weight loss on ignition, density, sintering shrinkage, water absorption and compressive strength of RM-YRS sintered brick prepared under the optimum conditions were8.91%,1.69g/cm3,7.49%,17.91%and39.1MPa, respectively.The properties research results indicated that:the higher sintering temperature and more RM would lead to more uniform and compact bricks, avoiding spalling; the sintering process made some components of raw materials transform into others having better thermostability, in which, the transformation of hematite to magnetite was the color changes reason of bricks; in addition, leaching toxicity and radioactivity of these sintered bricks met the national standards, therefore, they were safe.The results of sintering mechanisms research indicated that:the weight loss on ignition of sintered bricks was principally caused by the removal of absorbed water and crystal water, because the water content of RM was higher than YRS, and almost of all water would be completely eliminated below1000℃, weight loss on ignition was positive correlation with RM content, but almost uncorrelated with sintering temperature; the sintering shrinkage of sintered bricks mainly depended on sodium compounds and iron compounds of RM, and there had been lot of little interspaces in the inside of dried specimens before sintering operation, which led to high sintering shrinkage of sintered bricks.The above results indicated that it was entirely feasible to prepare sintered bricks with RM and YRS, and physical properties, leaching toxicity and radioactivity of the prepared bricks met the national standards. Therefore, they can be used as safe, economic, feasible and environmentally friendly building materials, realizing the reduction, harmlessness and reutilization of RM and YRS.