Under the “double carbon” goal, how to save energy and reduce carbon has become the focus of global attention. The steel industry is a high energy consumption industry and a key industry of greenhouse gas emissions. Low-carbon technology in the iron and steel industry is the commanding height to lead the low-carbon transformation and development. Vigorously developing low-carbon technology in the iron and steel industry is an effective way for the iron and steel industry to achieve green development.

The direct reduction iron-making technology uses non-coking coal as an energy source. Under the conditions of no melting and no slag formation, the raw materials basically maintain the original physical form. And iron oxides are reduced to obtain solid products with metallic iron as the main component. Technical method, It has the advantages of short process, low pollution, low consumption, reduces greenhouse gas emissions, and is environmentally friendly. It is one of the development directions of China’s steel industry.

What is direct reduction ironmaking technology?

Direct reduction refers to the iron-making process in which gas, liquid or non-coking coal is used as energy and reducing agent, and solid metal iron is obtained by reduction at a temperature lower than the softening temperature of iron ore and oxidized pellets. As a high-quality raw material for electric furnace steelmaking (referred to as DRI).

Process principle: The iron ore is subjected to the pelletizing process or oxidation melting treatment to obtain oxidized pellets. And then sequentially enters the gas-based reduction shaft furnace, electric furnace melting and refining continuous casting and rolling to convert into direct reduced iron, molten steel, and finished steel respectively. And the refining and continuous casting and rolling processes are accompanied by the generation of scrap.

The different reducing agents used, can be divided into coal-based and gas-based. The gas-based reduction process is the mainstream and dominant in the world; according to the classification of reactors, it can be divided into fixed bed, shaft furnace, fluidized bed, Rotary kiln, etc.

The coal-based direct reduction process is to make high-grade lump ore or iron powder and other iron-containing oxides into pellets and mix them with a solid reducing agent (anthracite, etc.) to form a charge and add it to a coal-based vertical reaction furnace. “Preheating→Reduction” is carried out in a vertical reactor. The reduced product is DRI pellets, which are used in the short-flow steelmaking process, and can be rolled into blocks or cakes. And can also be fed into the steelmaking process through hot charging to achieve low-energy-consumption production.

The gas-based direct reduction process uses natural gas as the main energy source to produce sponge iron. The main equipment is a shaft furnace, and the others include a fluidized bed and a reaction tank.

The advantages of direct reduction ironmaking have two aspects: one is that it does not use coke, and the other is that it is much less dependent on the scale than blast furnaces. However, due to its high energy consumption, it cannot fundamentally replace the blast furnace ironmaking process.

At present, the development of my country’s DRI industry is relatively slow. As my country enters a period of rapid growth in scrap supply, the short-process steel manufacturing process will be vigorously promoted and developed, which will inevitably promote the development of my country’s DRI industry.