How is "green" steel made?

First, steel - the main source of carbon emissions in China's manufacturing industry

China is the world's largest crude steel production country

Before 2016, due to the slowdown in downstream demand, vicious competition in the industry, and the loss of hematopoietic capacity of some enterprises to become zombie enterprises and other multiple reasons, the steel industry has a serious overcapacity situation, resulting in the overall profit reduction of the industry and a sharp decline in profitability.

In order to solve the problem of overcapacity, the steel industry has opened the supply-side reform since 2016, after a series of measures to promote enterprise restructuring and shut down zombie enterprises, the overall industry environment of the steel industry has been improved, and with the downstream industry demand for steel increased, China's crude steel production began to increase rapidly after 2016. In 2020, it will reach 1.065 billion tons, accounting for more than half of the global crude steel production, and it is the world's largest crude steel production country.

Increased crude steel production leads to increased carbon emissions

The rapid rise in crude steel production has led to the rapid rise in carbon emissions in the steel industry. In 2019, China's steel industry carbon emissions reached 1.853 billion tons, accounting for 19% of the country's total carbon emissions, carbon emissions are second only to the power industry, and it is the manufacturing industry with the most carbon emissions in China. Since China's crude steel production accounts for a large proportion of global crude steel production, China's steel industry to achieve carbon neutrality has a crucial role in the global carbon neutrality work.

Where does the carbon in the steel industry come from?

The current mainstream steel smelting methods can be divided into long process steel making with iron ore as the main raw material and short process steel making with scrap as the main raw material. Among them, the long process steel making includes sintering, high-price iron reduction (iron making), steel making, continuous casting, steel rolling and other links, and the short process is relatively short of the long process.

Long processes produce crude steel with higher carbon emissions per unit of output compared to short processes

In the long process of steelmaking, carbon emission mainly comes from sintering and blast furnace two processes. Sintering is the mixing of iron ore powder, fuel (including coke powder, anthracite, etc.), solvent (including quicklime, slaked lime, limestone, etc.), wetting granulation with water, and then ignition sintering on the sintering equipment, and finally forming sinter; The blast furnace melts sinter, iron ore, pellets and other iron-bearing substances to reduce to hot metal; In addition, auxiliary processes such as converter and rotary kiln also produce a certain amount of carbon emissions. The entire long process carbon emissions per ton of steel reach about 1.8-2.2 tons.

Compared with the long process of steel making, the short process, because scrap steel is used as the raw material, omits the high-carbon emission of ironmaking, and directly smelting scrap steel by electric arc furnace. The greenhouse gas emissions in the smelting process mainly come from the carbon in scrap steel and the carbon emissions generated by the oxidation of the graphite electrode used for heating, and the carbon emissions of the short process for producing tons of steel are only 0.4-0.8 tons.

The high proportion of long process is the root cause of high carbon emission in China's iron and steel industry

At present, China's crude steel production process is mainly based on BF - converter method, melt exchange method and direct reduction method and other long process steelmaking methods, accounting for up to 90%, higher than the global average of 73.7%, while the proportion of long process in the United States has dropped to 29.4% in 2020. High output and the use of high-carbon production processes are the most important reasons for high carbon emissions in China's steel industry.

Third, the path and dilemma of carbon neutrality in the steel industry

The steel industry wants to achieve the "double carbon" goal faces the difficulty of large emission reduction and short time, and wants to achieve the carbon neutral goal of the steel industry with high quality, it needs to make comprehensive efforts from various aspects such as strict control of production capacity, output, promoting process transformation, applying assistive technology, and seeking financial support.

Administrative regulation: Continue the requirements of supply-side reform, and strictly control production capacity and output

At the industry level, controlling production capacity and output is the most direct means to reduce carbon emissions in the steel industry. Controlling production capacity and output is not only the most important measure to deepen the supply-side reform of the steel industry that began in 2016, but also the most important measure to reduce carbon emissions.