CO₂ cut-down potential of conventional iron and steel making process in China based on carbon transfer and emission identification

Iron and steel industry is the largest CO₂ contributor in China's energy end-users, accounting for 15 % of the national emission, whose decarbonization is the key step for carbon neutrality. Blast Furnace and Basic Oxygen Furnace (BF-BOF) process dominates steel production in China, and carbon flow inside that process with multi-layered energy and material network is complex, leading to difficulty in CO₂ emission estimation. Herein, to understand the CO₂ emission and its cut-down potential of iron and steel industry, a carbon counting model is established and typical decarbonization ways are taken into consideration, including energy efficiency improvement, raw material composition reformation and traditional blast furnace technology innovation. The carbon counting model is based on detailed carbon transfer analysis in the BF-BOF process, and can be used to show the changes in carbon flows and CO₂ emissions caused by typical decarbonization methods. The CO₂ emissions of the BF-BOF process in China are estimated to be 1864.9 Mt. (1.954 kgCO₂/t cs), and around 61.03 % is from BF iron-making procedure. For traditional BF-BOF process, improving energy efficiency and reforming raw material composition can reduce CO₂ emissions by 71.9 kgCO₂/t cs (3.68 %) and 317.1 kgCO₂/t cs (16.23 %), respectively. Innovating traditional BF iron-making technology can achieve more significant reduction in CO₂ emissions. Compared to the traditional BF-BOF process, the oxygen blast furnace with top gas recycling and the one with top gas recycling plus COG injection can reduce CO₂ emissions by 557.1 kgCO₂/t cs (28.51 %) and 707.8 kgCO₂/t cs (36.22 %), respectively.