Preparation Of Innovative Porous Ceramsite By Sewage Sludge, Red Mud And Steel Slag And The Research Of Its Expansion Mechanism

In this study, Sewage Sludge, Red Mud and Steel Slag were employed as the raw materials in the preparation of innovative porous ceramsite. This study utilized two-phase sintered progess to prepare one dimensional Clay Ceramsite, two dimensional Sewage Sludge-Clay Ceramsite, three dimensional Sewage Sludge-Red Mud/Steel Slag-Clay Ceramsite and four dimensional Sewage Sludge-Red Mud-Steel Slag-Clay Ceramsite. The effects of sintering process and chemical component on the expansion characteristics of porous ceramsite were investigated. The expansion mechanism and expansion mode were founded which was expressed by functions. According to the study, the following conclusions were collected:1. The optimum preparation conditions of one dimensional Clay Ceramsite were preheated at400℃for20min and then sintered at1150℃for10min. The water absorption, grain density and bulk density of one dimensional Clay Ceramsite were11.09%,982.37kg/m3and520.05kg/m3respectively. The optimum preparation conditions of two dimensional Sewage Sludge-Clay Ceramsite were as follows:20%of dried sewage sludge added, preheated at400℃for20min and sintered at1100℃for10min. The water absorption, grain density and bulk density of two dimensional Sewage Sludge-Clay Ceramsite were8.25%,633.45kg/m3and386.25kg/m3. The optimum preparation conditions of three dimensional Sewage Sludge-Red Mud-Clay Ceramsite were as follows:the ratio between Clay and Sewage Sludge was8:2,5%of Red Mud added, preheated at400℃for20min and sintered at1050℃for10min. The water absorption, grain density and bulk density of three dimensional Sewage Sludge-Red Mud-Clay Ceramsite were8.36%,728.96kg/m3and309.64kg/m3. The optimum preparation conditions of three dimensional Sewage Sludge-Steel Slag-Clay Ceramsite were as follows:the ratio between Clay and Sewage Sludge was8:2,3%of Steel Slag added, preheated at400℃for20min and sintered at1000℃for10min. The water absorption, grain density and bulk density of three dimensional Sewage Sludge-Steel Slag-Clay Ceramsite were12.6%,760.5kg/m3and300.8kg/m3. The optimum preparation conditions of four dimensional Sewage Sludge-Red Mud-Steel Slag-Clay Ceramsite were as follows:the ratio between Clay and Sewage Sludge was8:2, the ratio between Red Mud and Steel Slag was2:1,4%of mixture of Red Mud and Steel Slag added, preheated at400℃ for20min and sintered at1025℃for10min. The mentioned five kinds of porous ceramsite meet the national requirement.2. During the sintering progress, the relationship between bloating force (BF) and surface tension (ST) could determine the expansion rate of ceramsite. The sintering temperature and chemical component has greatly effect on physical force of BF and ST. Physical force of ST has a negative correlation with sintering temperature and the amount of flux. BF is positively correlated with the volume of gas and Physical force of BF is determined by the amount of gas-production.3. During the sintering progress, Zibo clay could not only provide enough glass phases for ceramsite, but also has the amount of Fe2O3and carbonate minerals which could promote expansion of ceramsite. The main components of Sewage Sludge were organic matter and flux. Preheating treatment of pellets could contribute to the carbonization of organic matters and yield much carbon that could be used as gaseous compositions. The amount of flux in Sewage Sludge could offer more flux composition for ceramsite. Although the amount of organic matter was low in Red Mud and Steel Slag, the amount of Fe2O3and carbonate minerals was much high than Zibo clay and Sewage Sludge. Fe2O3and carbonate minerals could produce the oxygen and carbon dioxide. So expansion force can be enhanced and then promote the expansion of porous ceramsite. The flux in the Red Mud and Steel Slag could decrease sinter temperature.4. Expansion model contained the optimization of expansion model and the general function of expansion model. The optimization of expansion model was used to depicte the expansion progress and the general function of expansion model was used to character the whole expansion process. Depending on the mentioned two functions, it was showed that the expansion process had connections with the chemical component and the preparation process.