Life Cycle Assessment Of Electrolytic Manganese Metal Production

Electrolytic manganese metal is widely used in various industrial fields,especially in the steel industry due to its characteristics.With the rapid development of economy,China has become the largest producer of electrolytic manganese metal in the world.However,electrolytic manganese metal production is one of the industries with high resource and energy consumption and considerable waste emission.It has promoted the economic development of China.At the same time,it has also brought serious pollution to the environment.Based on this realistic background,this study used a life cycle assessment method to quantify and analyze the environmental impact of electrolytic manganese metal production.By considering the input and output of the entire production process from "cradle" to "gate",the data on the production process of electrolytic manganese metal product were collected.Onsite data and background data were combined to build a complete life cycle inventory of electrolytic manganese metal.The ReCiPe2016 model was applied to evaluate the life cycle impact at midpoint and endpoint level,and the key processes and substances at midpoint and endpoint level were identified.Finally,suggestions were put forward to reduce the environmental burden of electrolytic manganese metal production,so as to improve the clean production level of this industry.The results show that mineral resource scarcity,terrestrial ecotoxicity,fossil resource scarcity,and global warming are the most important midpoint impact categories.Manganese concentrate preparation,manganese oxide production,direct emissions,and electricity generation are key processes that cause environmental burdens.Through the identification of key substances at midpoint level,it is found that manganese,sulfuric acid,coal,and carbon dioxide are the main substance contribution factors of mineral resource scarcity,terrestrial ecotoxicity,fossil resource scarcity,and global warming,respectively.For other relatively insignificant midpoint impact categories,the key substances are mainly nitrogen oxides,sulfur dioxide,zinc to air,carbon disulfide,and chromium VI to water.The analysis results of electrolytic manganese production at endpoint level were normalized and found that human health damage was the most significant category The key processes and key substances were identified at the endpoint level.The results show that processes related to manganese resources(i.e.,manganese concentrate preparation and manganese oxide production)and electricity generation are the main processes that affect the overall environmental performance because of the mineral-intensive and power-intensive production characteristics of the electrolytic manganese metal production industry.Carbon dioxide,sulfur dioxide,particulates,manganese,coal,and zinc are the key substances for endpoint impact categories.The sensitivity analysis results show that reducing the consumption of electricity,optimizing the production process of manganese concentrate and manganese oxide,and reducing direct emissions during the production of electrolytic manganese metal can have the greatest environmental benefits.If electricity consumption is reduced by 5%,global warming and fossil resources scarcity will decrease 353.67 kg CO2 eq and 63.91 kg oil eq,respectively.In addition,to ensure the data quality and the result accuracy,uncertainty analysis based on Monte Carlo method was performed.In order to reduce the environmental burden of electrolytic manganese metal production,the production technology should be improved,including the utilization technologies of low-grade manganese carbonate ore and manganese oxide ore in China,as well as energy-saving and consumption-reducing technologies that reduce resource waste and pollutant emissions;new production technology without selenium and chromium should be developed to reduce human health damage;manganese residues should be reduced and make timely use of it to solve the problems of waste of resources and environmental pollution caused by manganese residue and potential safety hazards;electricity structure should be adjusted,and replace coal with clean energy in power generation,such as hydropower,wind power,and solar energy,while improving the efficiency of electricity consumption,thus effectively reducing the associated environmental impacts.