Winner of the Excellence in low-carbon steel production Steelie 2022
Angang Steel Company Limited Ironmaking General Factory has four 3,200 m3 blast furnaces and four 2,580 m3 blast furnaces with a capacity of 19 million tonnes/year; the agglomerated iron ore for blast furnaces is 20 million tonnes/year of high basicity sintering ore and 8.2 million tonnes/year of regular acid pellet ore.
There are three key problems that restrict the low-carbon and low-CO2 emission of Ansteel’s blast furnace charge production process structure: firstly, there are many sintering producing lines, resulting in large SOx, NOx and CO2 emissions of sintering flue gas; secondly, the proportion of sintering ore in the furnace is high (76%-78% on average), the proportion of pellet ore into the furnace is low (18%-21% on average), and a small amount of natural lump ore (3%-5% on average), so the structure of the blast furnace charge is not optimal in the long term; thirdly, the SiO2 content of regular acid pellet ore is as high as 6.37%, with poor thermal metallurgical performance.
The above three problems are common in other domestic iron and steel enterprises, which also restrict domestic blast furnaces from achieving low carbon and low CO2 emission targets.
In response to the above three issues, this project is based on the development of low-basicity, high-SiO2 pellets, a disruptive change to the current acid pellet ore and blast furnace charge structure of Ansteel; innovative development of highly efficient calcium-based binder with low silicon for acid pellet ore; the production of high-SiO2 0.35-basicity pellet ore; and the thermal metallurgical properties and soft melting properties have been significantly improved.
The achievement was successfully applied to eight Ansteel blast furnaces.
The furnace charge structure of the eight blast furnaces was significantly adjusted to 63.51% for high basicity sinter ore, 6.91% for regular acid pellets, 20.78% for low basicity high silica pellets and 8.80% for natural lump ore, initially achieving a low-carbon and low-CO2 emission furnace charge structure pattern.