Pollutant Discharge And Site Pollution Characteristics Of Electrolytic Manganese Industry

Manganese is an important metal mineral,mainly used in the steel industry.At present,metal manganese is mainly produced by electrolysis.In the electrolytic manganese production process,there are many types of ore-associated metals,low level of equipment automation,high energy consumption and material consumption in each process link,and complex sources of pollutants and site environmental conditions,making it difficult to connect and implement key links in site pollution source prevention and control.This paper analyzes the characteristics of the electrolytic manganese industry pollution discharge and identifies pollution factors based on the list of raw and auxiliary materials,process flow,production and discharge nodes,and pollutant discharge of electrolytic manganese enterprises in Hunan Province through on-site surveys,personnel interviews,and data collection.Select 7 different types of electrolytic manganese enterprises to sample and analyze the soils in key areas of the site,and study the contents and spatial variability of 10 heavy metals in soils at different depths.The risk assessment model is used to evaluate the poisoning risk of pollution factors,and the analytic hierarchy process is used to assign points among the four indicators of pollutant ore content,pollutant discharge,pollutant soil exceeding rate,and pollutant poisoning risk,and screen out the characteristic pollution factors.Identify each key pollution area,main prevention and control nodes and key prevention and control factors,and establish a pollutant emission list and site pollution identification table for the electrolytic manganese industry.It is expected to provide theoretical support for the supervision and prevention of pollution sources of electrolytic manganese enterprises and the pollution restoration and management of decommissioning sites.research shows:(1)In 2019,my country's electrolytic manganese production capacity has reached 2.35 million tons,with an output of 153 tons and an export volume of about30 tons.It is the world's largest producer,consumer and exporter.As of the end of2020,there are currently 24 electrolytic manganese production enterprises in Hunan Province,with a total production capacity of 443,000 tons/year.The scale of the enterprises is mainly small,mainly distributed in Xiangxi Prefecture and Huaihua,with production capacity mostly between 10,000 and 30,000 tons/year.(2)Heavy metal pollutants from electrolytic manganese industry enterprises are mainly discharged into the environment through solid waste.The discharge per ton of pollutants from large to small are manganese,zinc,hexavalent chromium,nickel,lead,copper,cobalt,arsenic,Cadmium,mercury.Exhaust gas is mainly unorganized emission,and the main pollution factors are lead,manganese,and cadmium.The main pollutants in wastewater are manganese and chromium.Among the four solid wastes,the amount of leaching residue is the largest,followed by anode mud,sulfide residue,and chromium-containing waste residue.(3)The arsenic pollution of the electrolytic manganese enterprise site in Hunan Province is relatively prominent.The metal samples exceed the screening value standard and the ratio of the background value is as follows: arsenic,hexavalent chromium,manganese,lead,cobalt,and nickel.The over-standard rate of key areas in order from high to low is the electrolysis workshop,the leaching press filter workshop,the solid waste storage area,the wastewater treatment area,and the raw material storage area.The main prevention and control factors in the leaching filter press workshop are As,Mn,the main prevention and control factors in the electrolysis workshop are As,Cr(?),Pb,and the key prevention and control factors in the wastewater treatment zone are As,Cr(?),Ni,and solid waste.The main prevention and control factors in the storage area are Cr(?),Mn,and Pb.(4)The over-standard rate of electrolytic manganese closed enterprises is 100%,and the environmental quality of the production enterprises is better.The nearby manganese slag storage yard left by company A is heavily polluted.The maximum multiples of lead,hexavalent chromium,and manganese are located in this area.The concentration of lead,nickel,hexavalent chromium,and arsenic in the underlying soil and high content areas all exceed the surface soil.The characteristic pollutants of the electrolytic manganese industry were screened out through the analytic hierarchy process as As,Mn,Cr(?),Pb,Co,Ni.