HEAVY METAL EMISSIONS FROM STEELWORKS BASED ON SOLID WASTE RESOURCE RECYCLING: A CASE STUDY ON LEAD

Recently, China has issued policies, opinions and plans on heavy metal pollution prevention and control respectively. However, there were still some obstacles in the process of promoting heavy metal emission reduction, such as unclear accounting, lack of quantitative pathway studies and unsystematic emission reduction pathways. Specifically, firstly, the emission factors of heavy metals from the steelworks failed to consider the secondary emissions from waste recycling. Secondly, studies on the material flow of heavy metals from steelworks have not been reported. Finally, previous emission reduction studies focused on a specific production step or problem, but lacked a systematic analysis of emission reduction potential. In view of the above problems, this paper, taking the lead (Pb) as an example, adopted the substance flow analysis method to establish the Pb flow in steelworks for the first time, and analyzed the flow mechanism of Pb in steelworks. With source reduction, process control, and end-of-pipe treatment as emission reduction ideas, based on the input-output multi-objective optimization method, the current Pb flow network was optimized to explore the emission reduction potential of Pb in steelworks and provided technical suggestions for the reduction of Pb-content pollution in the steel industry. The results showed that the values of input, circulation, and output of Pb were 341.32 g/t-crude steel, 357.06 g/t-crude steel and 129.41 g/t-crude steel, respectively. Pb is enriched and circulated mainly between the sinter plant and the BF plant. Pb was mainly derived from iron ore concentrate and lump ore and exported with slag, waste gas and hot rolled coils. After source reduction and end-of-pipe treatment optimization, the reduction ratio of Pb content of steel products was between 16.06% and 30.69%.