Preparation Of Ceramsite By Electrolytic Manganese Residue And Municipal Solid Waste Incineration Fly Ash

Municipal Solid Waste Incineration?MSWI?has become a widely used technology for the treatment of municipal solid waste in cities across the country.MSWI fly ash produced during refuse incineration is defined as hazardous waste due to its harmfulness to the natural environment and human being caused by pollutants rich in heavy metals and organic toxicants.Therefore,MSWI fly ash must be disposed of to achieve stability and harmlessness.Electrolytic Manganese Residue?EMR?is a solid waste produced by electrolytic manganese industry.It not only occupies a large amount of land,but also has potential danger duo to its heavy metal.However,EMR is rich in SiO₂,Al₂O₃ and other oxides,which makes it have potential for resource utilization.This paper selected MSWI fly ash and EMR as the main materials,Coal fly ash as auxiliary material,and Sawdust as pore-forming agent to carry out experimental research on firing ceramsite.The preliminary ceramsite raw material ratio and firing conditions were determined by single factor test,and then the ceramsite ratio and firing process were optimized by uniform design method and orthogonal design method.Finally,the ceramsite properties and solidification effect of heavy metals were analyzed.The main conclusions are as follows:?1?MSWI fly ash and EMR were selected as main materials and Coal fly ash was selecteda as auxiliary material to prepare ceramsite.Through single factor test,the effects of raw material ratio and firing conditions on granule strength,bulk density and1h water absorption of ceramsite were analyzed to determine the initial raw material ratio:MSWI fly ash:EMR:Coal fly ash:12%:50%:38%,and firing conditions:preheating temperature was 600°C,preheating time was 20 min,calcination temperature was 1140°C,roasting time was 14 min.The optimization of ceramsite formulation by uniform design method and quadratic multiple stepwise regression model analysis.The optimal ratio of ceramsite is:EMR 49.01%,MSWI fly ash 14.46%,Coal fly ash 36.53%,and its ceramsite properties:granule strength was 849N,bulk density was 796kg/m3,and 1h water absorption was 5.78%.?2?MSWI fly ash was pretreated with water,and the sawdust was added as a pore former to mix the EMR and the Coal fly ash to prepare the ceramsite.After the MSWI fly ash was pretreated by water washing,the percentage of Cl and SO₃ decreased significantly,and the relative percentage of SiO₂ and Al₂O₃ increased.The ceramsite formula was analyzed by uniform design method and quadratic multiple stepwise regression model and optimal formulation was tested to obtain the best ceramsite raw material ratio:EMR:Coal fly ash:MSWI fly ash:Sawdust:39.46%:33.45%:18.81%:8.28%,its ceramsite properties:granule strenght was 828N,bulk density was 697kg/m³and 1h water absorption was 10.54%.The optimum firing conditions of the ceramsite were obtained by orthogonal test:preheating temperature was 600°C,calcination temperature was 1140°C,and roasting time was 17 min.The ceramsite properties prepared under the optimal ratio and optimum firing conditions:granule strenght was816N,bulk density 693kg/m³,1h water absorption 9.72%,all met the 700 grade light aggregate of GB/17431.2-1998 standards.?3?According to the microscopic morphology of the surface and section of the ceramsite,the surface of the ceramsite was densely glazed and had a porous structure inside.Through heavy metal analysis,the morphology of heavy metals such as Zn,Cu,Cr,Cd and Pb in MSWI fly ash and EMR after calcination were transformed from unstable form to stable residue state.The toxic leaching concentration of heavy metals in ceramsite is far below the leaching standard value specified in the hazardous waste identification standard?GB/T5083.3-2007?and landfill standard?GB16889-2008?.