The entire smelting process of the iron and steel industry from coking, sintering, ironmaking, steelmaking to steel rolling involves different types of pollutants, covering three types of waste gas, waste water and slag.
Specifically, the sintering and coking processes mainly produce exhaust gas such as sulfides, nitrogen oxides and soot, the iron and steelmaking processes mainly produce solid wastes such as slag, and the pollutants generated in the steel rolling process are mainly wastewater pollution such as cooling water. Among them, gaseous pollutants such as sulfides, nitrogen oxides and soot generated in the sintering and coking process are the most serious.
The exhaust gas produced by the iron and steel industry is dominated by sulfides, nitrogen oxides and soot, mainly from the pre-iron links such as coking, sintering, and pelletizing. Take the exhaust gas pollutant emissions of a large-scale steel company (9.7 million tons) with a long process as an example. The smoke/dust emitted by the company mainly comes from the raw material system (accounting for 19.5%) and the ironmaking system (coking + sintering + pellets + Ironmaking, accounting for 62.3%) and steelmaking systems (accounting for 13.5%), the three together account for 95.3% of the total smoke/dust emissions from the steel industry. Specifically, SO2 mainly comes from pellets (accounting for 34.1%), sintering (accounting for 25.1%) and captive power stations (accounting for 27.5%), accounting for about 86.7% of the total emissions; NOX mainly comes from sintering (accounting for 30.9%), Captive power stations (23%), pellets (15.1%), and coking (9.9%) account for about 78.9% of total emissions.