Brief introduction of blast furnace ironmaking

In the process of blast furnace production, iron ore, coke and flux (limestone) used for slagging are loaded from the top of the blast furnace, and preheating air is blown along the circumference of the blast furnace from the tuyere located at the lower part of the blast furnace. At high temperature, carbon in coke (some blast furnaces also inject auxiliary fuels, such as pulverized coal, heavy oil, natural gas, etc. ) burns with oxygen blown into the air to generate carbon monoxide, which removes oxygen from iron ore during the rising process in the furnace, thus reducing to obtain iron. The molten iron is discharged from the taphole. Unreduced impurities in iron ore combine with fluxes such as limestone to form slag, which is discharged from the slag outlet. The generated gas is extracted from the top of the furnace and used as fuel for hot blast stoves, heating furnaces, coke ovens and boilers after dust removal.

A brief history and recent situation

In the early days, the blast furnace used charcoal or coal as fuel, which was changed to coke in the18th century and changed from cold air to hot air in the middle of19th century (see metallurgical history). At the beginning of the 20th century, blast furnace ironmaking developed rapidly after using gas-fired internal combustion engines and steam turbine blowers. At the beginning of the 20th century, the daily output of American large blast furnaces reached 450 tons, and the coke ratio was about 65,438+0,000 kg/ton of pig iron. In the early 1970s, Japan built a 465,438+0.97 cubic meter blast furnace, with a daily output of more than 654.38+0 million tons of pig iron and a fuel ratio of less than 500 kg/ton of pig iron. China began to develop modern iron and steel industry in the late Qing Dynasty. The construction of Hanyang Iron Works began in 1890, and the blast furnace 1 (248 cubic meters, with a daily output of iron 100 tons) was put into operation in May 1894. 1908 Hanyeping Company including Daye Iron Mine and Pingxiang Coal Mine was established. 1980, the total volume of blast furnaces in China was about 80,000 cubic meters, of which 26 exceeded 1000 cubic meters. 1980, China produced 38.02 million tons of iron, ranking fourth in the world.

Blast furnace ironmaking is facing elimination, and China iron and steel industry needs to be upgraded urgently.

Blast furnace ironmaking technology is suitable for producing commodities and primary steel in countries that have initially realized industrialization, but in developed countries, blast furnace technology is facing elimination. Electric furnace steelmaking is the trend in the world today. Electric furnace ironmaking can improve the quality and special properties of steel and reduce the waste of raw materials and electricity. In the era of order economy, production should change according to market demand, but the technological cycle of blast furnace ironmaking is long, the product grade is low, and the product needs a longer processing chain. Electric furnace steelmaking can shorten the iron and steel smelting cycle, arrange production according to orders, waste less raw materials and power resources, and there will be no large backlog of products like blast furnace ironmaking. Nowadays, the society has entered the material age, and the steel needed by the market is no longer the traditional material. The living space of blast furnace ironmaking is greatly reduced, and the added value is very low. Take the iron and steel industry in China as an example, the profit of the national iron and steel industry is not as good as that of iron ore mining, because the level of blast furnace ironmaking technology is low and backward, and it is impossible to produce high value-added products. Although we praise the contribution of China's iron and steel industry to the country, we can't sleep on the credit book. Blast furnace ironmaking technology has reached a dead end.

As the world's largest steel producer, iron ore importer, primary steel exporter, steel importer and steel industry with the largest population and steel mills, China must seriously consider the next development strategy of China's steel industry. We can't rely on the huge investment of the state to promote the prosperity of the steel industry on the pretext of promoting employment, but we should seriously think about reducing pollution, improving the added value of products and adapting to the actual demand of the market, so as to realize the industrial upgrading and benefit upgrading of the steel industry.