Study On The Synergistic Solidification Of Heavy Metals In Coal Gasification Fine Slag And Electrolytic Manganese Slag By Multi Source Industrial Waste

With the development of industrial production and life,the number of solid waste from different sources is increasing day by day.In the northwest industrial system,coal chemical industry and electrolytic manganese industry occupy an important position.The solid waste of coal chemical industry and electrolytic manganese industry has a huge amount of production,but the main treatment methods of coal gasification slag and electrolytic manganese slag are still stockpiled and landfill.The ecological environment in Northwest China is fragile.If a large number of industrial solid waste is discharged without treatment,it will not only occupy a large amount of land,but also cause accumulated heavy metal pollution hazards,which will cause continuous pollution to soil,groundwater and air,which will bring great threat to the regional ecological environment.In recent years,the technology of environmental pollution control and the mechanism of heavy metal pollution enrichment and solidification have been the hot spots of the corresponding subjects.The scientific community has made obvious progress in the research of heavy metal solidification and pollution control technology,but it is still unable to realize large-scale application,mainly because of the high application cost,insufficient basic research and insufficient technology integration for the process of pollution control.Some curing agents and processing technologies which have been proved to be superior in performance are mostly expensive chemical reagents,which are difficult to form industrial production and application.Facing the requirements of the Yellow River basin ecological protection and high-quality development leading area,the treatment of solid waste is urgent.The first problem is harmless treatment and safe storage of solid waste,and then gradually realize ecological utilization and resource utilization.Accelerating the carbonation process is that the chemical reaction between carbon dioxide and inorganic materials is transformed into a heat stable insoluble material,which can absorb carbon dioxide and reduce the leachability of trace metals.It is a simple and low-cost method to accelerate the carbonation and solidify heavy metals in solid waste,and can also absorb a large amount of carbon dioxide generated when using fossil fuels,Prevent it from releasing to the atmosphere.With the large use of fossil fuels,people have realized the harm of global warming.In this paper,the leaching test,physical and chemical properties,thermal decomposition characteristics of coal gasification slag,electrolytic manganese slag,carbide slag of heavy metal hazards and the feasibility of carbonation were studied.On this basis,a scheme of CO2 solidification of heavy metals in fine coal gasification slag and electrolytic manganese slag by carbide slag and tail gas of coal gasification process is proposed.Firstly,the effects of reaction temperature,reaction pressure,mixed gas flow rate,reaction time and water-solid ratio on heavy metal leaching from calcium carbide slag during carbonation were systematically explored;then,the effects of calcium carbide slag addition amount,reaction temperature,reaction pressure,mixed gas flow rate and reaction time on solidification of heavy metal from electrolytic manganese slag during carbonation were studied by adding calcium carbide slag into electrolytic manganese slag The phase transformation before and after carbonation was analyzed by XRD,TG-DSC,FT-IR,and the changes of pore structure and micro morphology were analyzed by SEM-EDS and BSE.Explore and analyze the principle of accelerating carbonation to fix heavy metals in coal gasification fine slag and electrolytic manganese slag.The results show that carbide slag is suitable for carbonation,while coal gasification fine slag and electrolytic manganese slag are not suitable for carbonation alone.Calcium carbide slag was added to coal gasification fine slag and electrolytic manganese slag,and the tail gas of coal gasification process was introduced to accelerate the carbonation.Compared with the original coal gasification fine slag and electrolytic manganese slag,the pH value of leachate changed to 6?9,the carbonate increased and the concentration of trace metals(Ni,Mn,As,Pb,Zn,Cd)in leachate was removed by at least 99%,Other heavy metals are also within the scope of the national integrated wastewater discharge standard.The main reasons are as follows:calcium carbide slag provides Oh-and Ca2+for salinization,which can make heavy metals settle in alkaline environment.Meanwhile,solid waste slag can play the role of"crystal nucleus".Calcium carbonate generated by CO2 salinization of Ca2+ can also fill the pores,reduce the pore size,further cover the solid waste,and prevent the further leaching of heavy metals;high temperature and high concentration of CO2 in boiler tail gas are used to improve the quality of coal The rate of carbonation reaction can promote the occurrence of carbonation reaction.This study opens up a new way for comprehensive harmless treatment and carbon dioxide sequestration of fine coal gasification slag,electrolytic manganese slag and carbide slag.The harmless treatment conditions are relatively mild,and the raw materials are solid waste,so as to achieve the purpose of "waste treatment" and resource saving.The process is simple and has a bright future for industrialization.