Effects Of Different Sintering Methods And Sintering Systems On The Properties Of Municipal Sludge Ceramsite

Municipal sludge is waste generated by people during their production and living activities.With the continuous expansion of the city scale and the acceleration of the urbanization process,the output of urban sludge has also increased sharply.It has now become a major source of pollution of rivers and groundwater,which has caused great harm to the environment and human life.At present,the main disposal methods of sludge include incineration and landfilling,which cannot make full use of sludge resources,and easily cause secondary pollution.This project uses urban sludge as the main raw material and uses two sintering methods,namely,rapid sintering and conventional sintering,to burn the sludge ceramsite to produce light and high strength,it complies with the national standard requirements of GB/T 17431-2010"Lightweight Aggregate and its Test Methods",and can realize the green environmental protection disposal of solid waste and the effective use of resources.The chemical composition of the raw materials was analyzed in the early stage of this subject,and the range of the raw material mixture ratio was determined in combination with the Riley phase diagram.According to the TG-DSC thermogravimetric analysis and preheating experiments of the ceramsite blank,the scope of the firing system was determined.The sintering methods of sludge ceramsite in this subject are divided into rapid sintering and conventional sintering.The rapid sintering method refers to the pre-heating stage and sintering stage of ceramsite.There is no heating process.First,a single factor experiment is designed to study the influence of sintering temperature,sintering time and sludge content on the performance of ceramsite.Cross test L₉?3⁴?determines the optimal firing process of sludge ceramsite.The conventional sintering method refers to preheating,heating and high temperature sintering of sludge ceramsite mixed with foaming agent.First,A single factor experiment is designed to study the influence of sintering temperature,sintering time and foaming agent content on the performance of ceramsite.The pore structure parameters of clay ceramsite determine the relationship between the pore structure's bulk density and compressive strength of ceramsite.Finally,a comparative study of the two sintering methods of sludge ceramsite was carried out.In the rapid sintering method,the research results of the influence of the sludge ceramsite firing process parameters show that with the progress of the sintering reaction,the bulk density of ceramsite decreases first and then increases,and the tube compression strength strength increases and then decreases.As the sintering temperature increases,the water absorption first decreases and then rises,and gradually decreases as the sintering time increases.With the increase of sludge content,the bulk density and tube compressive strength of ceramsite gradually decrease,and the water absorption rate gradually increases.The best firing process of sludge ceramsite was determined by orthogonal test:the sludge pottery content was 60%,preheating temperature was 350?,preheating time was 30min,sintering temperature was 1150?and sintering time was 20min.The bulk density is 315kg/cm³,the cylinder pressure strength is 2.69MPa,and the water absorption is 12.8%.Under the conventional sintering method,the effect of firing process parameters of sludge ceramsite shows that the bulk density of ceramsite decreases gradually with the progress of sintering reaction.As the sintering temperature increases,the tube compression strength first increases and then decreases,and gradually decreases with the increase of the sintering time.The water absorption decreases gradually with the increase of sintering temperature and increases gradually with the increase of sintering time.The results of the research on sludge ceramsite with MnO₂as foaming agent show that with the increase of MnO₂content,the bulk density and water absorption of ceramsite gradually decrease,the tube compressive strength first increases and then decreases,and the average pore size of pores It increases first and then decreases,which is opposite to the changing trend of the specific surface area.When the MnO₂content was increased from 2%to 6%,the pore number and porosity of the ceramsite increased,and the bulk density decreased accordingly.The tube compressive strength reached a maximum of 5.21MPa when the MnO₂content was 4%.Compared with the sludge ceramsite with the MnO₂content of 0%,2%,and 6%,the tube compressive strength was increased to 27%,13%,and 15%.At this time,the proportion of micro pores with a pore diameter of<0.10mm in the ceramsite is about 40%,and the proportion of pores with a pore diameter of 0.10mm to 1.5mm is about 60%.Controlling the ratio of these two pores is close to 40%and 60%respectively,which can effectively improve the tube compressive strength of sludge ceramsite and increase the ratio by 10%to 30%.Determined the best firing process of sludge ceramsite in conventional sintering method:50%sludge content,4%foaming agent content,preheating temperature 300°C,preheating time 30min,sintering temperature 1100°C,sintering time 20min,heating rate 10°C/min.The prepared sludge ceramsite has the bulk density of 628kg/cm³,the tube compressive strength of 5.21MPa,and the water absorption of 7.9%.A comparative study of the two sintering methods:rapid sintering and conventional sintering showed that the bulk density of sludge ceramsite prepared by rapid sintering is between 310kg/cm³and 320kg/cm³,and the tube compression strength is between 2.6 and2.7MPa,which is higher than the 1.0MPa required by the specification,wuich belongs to the ultra-light density ceramsite.The bulk density of the sludge ceramsite produced by conventional sintering method is between 620kg/cm³and 630kg/cm³,and the cylinder pressure strength is between 5.2MPa and 5.3MPa,which is higher than the 5.0MPa required for the specification of high-strength artificial lightweight aggregates,which belongs to high-strength ceramsite.Comprehensive analysis,the performance of the sludge ceramsite prepared by the rapid sintering method is better than that of the conventional sintered sintering method.The rapid sintering method is selected as the preferred sintering method of the sludge ceramsite.