Principle and technological process of domestic ironmaking

Blast furnace production is continuous. The first generation blast furnace (from blowing-in to overhaul and shutdown) can be continuously produced for several years to more than ten years. During production, iron ore, coke and flux are continuously charged from the furnace top (generally, the furnace top is composed of bell and hopper, while the modern blast furnace is bell valve top and bell-less top), hot air (1000 ~ 1300℃) is blown from the tuyere at the lower part of the blast furnace, and fuel such as oil, coal or natural gas is injected. The iron ore charged into the blast furnace is mainly a compound of iron and oxygen.

At high temperature, the carbon in coke and injection and carbon monoxide produced by carbon combustion take away the oxygen in iron ore and get iron. This process is called reduction. Iron ore is refined into pig iron through reduction reaction, and molten iron is discharged from the taphole.

Gangue in iron ore, ash in coke and injection are combined with flux such as limestone added into the furnace to generate slag, which is discharged from the taphole and slag outlet respectively. The gas is led out from the top of the furnace and used as industrial gas after dust removal. Modern blast furnaces can also use the high pressure at the top of the furnace and some derived gases to generate electricity.

Basic process

Blast furnace smelting is a continuous production process of reducing iron ore into pig iron. Iron ore, coke, flux and other solid raw materials are fed into the blast furnace in batches from the top charging device according to the specified batching ratio, and the throat material level is kept at a certain height. Coke and ore form an alternating layered structure in the furnace.

Furnace front operation

1. By using special equipment and various tools such as taphole machine, clay gun and slag stopper, the slag hole and taphole are opened respectively at the specified time (at present, the slag hole and taphole are combined into one), slag and iron are discharged, and then flow into the slag hole and taphole respectively through the slag iron ditch, and the slag iron is blocked after being discharged, thus ensuring the continuous production of the blast furnace.

2. Complete the maintenance of slag tapping, taphole and various special equipment in front of the furnace.

3. Manufacture and repair the skimmer, main runner and slag runner.

4. Replace the cooling equipment such as air and slag port, clean up the slag iron transportation line and a series of work related to slag discharge.

Basic operating system of blast furnace:

The furnace condition of blast furnace is stable and smooth: generally speaking, the burden in the furnace decreases, the gas flow increases evenly, the furnace temperature is stable and abundant, and the pig iron is qualified, so as to achieve high yield and low consumption.

Operating system: operating criteria of blast furnace based on specific conditions of blast furnace (such as blast furnace type, equipment level, raw material conditions, production plan and variety index requirements).

Basic operating systems of blast furnace: charging system, air supply system, hearth heating system and slag tapping system.

Extended data

Color development method

Ironmaking in China began in the Spring and Autumn Period. At that time, the ironmaking method was block ironmaking, that is, at a lower smelting temperature, iron ore was reduced to sponge iron in solid state and then forged into iron blocks. Generally speaking, there are three kinds of smelting blocks for ironmaking: ground furnace, flat furnace and shaft furnace.

Soon after China mastered the massive ironmaking technology, liquid pig iron containing more than 2% carbon was smelted for casting tools. As early as the Warring States Period, China had mastered the technical methods of decarbonization and heat treatment, and invented ductile iron. In the late Warring States period, a reusable "iron model" (an empty stomach made of iron for casting metal objects) was invented.

During the Western Han Dynasty, the crucible ironmaking method appeared. At the same time, the scale of ironmaking shaft furnace has been further expanded. 1975, the site of iron smelting in Han Dynasty was discovered and excavated in Guxing town near Zhengzhou, with an area of120,000 m2, and two parallel blast furnace foundations were excavated, with a blast furnace volume of about 50m3. In the Western Han Dynasty, the "steel explosion method" was also invented, that is, a new process of "frying" wrought iron or steel with pig iron, and the product was called steel explosion.

At the same time, the technology of "hundred steelmaking" came into being. In the Eastern Han Dynasty (AD 25-220), when Emperor Guangwu was in power, he invented the hydraulic blast furnace, namely "drainage". The invention of ancient water rafts in China was about 1 100 years earlier than that in Europe.

After the Han Dynasty, the method of pouring steel was invented. Biography of the Northern Qi Dynasty was called "Su Gang", later called "Guan Gang" and "Tuan Gang". This is another great achievement of China's ancient steelmaking technology.

According to "Introduction to China Encyclopedia", China was the first country to use coal to make iron, which was tried out in Han Dynasty and popularized in Song and Yuan Dynasties. In the Ming dynasty (a.d. 1368 ~ 1644), pig iron could be made from coke. During the period from 14 to 15, the output of iron once exceeded 20 million Jin, equivalent to12,000 t, and Britain, the first western country to start the industrial revolution, reached this level about two centuries later.

Generally speaking, the characteristics of China's ancient steel development are different from those of other countries. Bulk ironmaking and solid carburized steel by solid reduction method have been used for a long time in the world, and China cast iron and pig iron have always been the main methods of steelmaking. Due to the invention and development of cast iron and pig iron steelmaking, China's metallurgical technology was at the advanced level in the world before the middle of Ming Dynasty.

/kloc-In the second half of the 9th century, the Qing Ye government developed modern military industry, manufactured guns and warships, and imported a large number of steel produced in western countries. 1867 imported about 8250t tons of steel, 1885 about 90,000 tons, 189 1 year increased to 1.7 million tons (about 1.3 million tons). Imported steel has gradually occupied the domestic market, and it is difficult for the traditional iron smelting industry to maintain production, while the domestic steel consumption is increasing. Therefore, the rise of modern iron and steel industry has become the need of the times.

187 1 year (13th year of Tongzhi in Qing Dynasty), Li Hongzhang, governor of Zhili, and Shen Baozhen, minister of ship administration, invited them to open coal and iron to save munitions, so they granted their request and ordered them to try it out in Cizhou, Fujian and Taiwan Province provinces of Zhili. 1875, Zhili Cizhou Coal and Iron Mine ordered an iron melting machine from Britain, but it was far from successful due to transportation difficulties. This shows that attention has been paid to the establishment of a new type of iron and steel industry.

1886, Pan Wei, the governor of Guizhou province, founded a green factory, using earthen stoves first, and then ordering ironmaking and steelmaking equipment from Britain, which was installed in 1888. Finally, due to the corruption of the Qing court, lack of funds, poor management of coal and iron mines, and no one is proficient in technology, it closed at 1893. This is an attempt to establish a modern steel plant.