Chemical principle
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 loaded from the furnace top (generally, the furnace top is composed of bell and hopper, and the modern blast furnace is bell valve top and bell-less top), hot air (1 ~ 13 degrees Celsius) 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, carbon in coke and injection and carbon monoxide generated by carbon combustion take oxygen out of iron ore and get iron. This process is called reduction. Iron ore is refined into raw 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 exported 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 to generate electricity with some derived gas.
basic process
blast furnace smelting is a continuous production process of reducing iron ore into pig iron. Solid raw materials such as iron ore, coke and flux 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.
Operation in front of the furnace
1. Using special equipment and various tools such as tapping machine, clay gun and slag blocking machine, the slag and taphole are opened respectively at the specified time (now the slag and taphole are combined into one), and the slag and iron are discharged, and then flow into the slag and taphole respectively through the slag and taphole, and the slag and taphole are blocked after the slag and iron are discharged, so as to ensure the continuous production of the blast furnace.
2. complete the maintenance of slag, taphole and various special equipment in front of the furnace.
3. Make and repair the skimmer, main tapping ditch and slag and iron ditch.
4. a series of work related to slag tapping, such as replacing cooling equipment such as air and slag port, and cleaning slag iron transportation line.
Basic operating system of blast furnace:
The furnace condition of blast furnace is stable and smooth: generally speaking, it means that the burden in the furnace drops and the gas flow rises uniformly, the furnace temperature is stable and abundant, pig iron is qualified, and high yield and low consumption are achieved.
operating system: the 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 slagging system.
expanded information
development process
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 in solid state to obtain sponge iron, and then forged into iron blocks. In general, there are three kinds of smelting blocks for ironmaking: ground furnace, flat furnace and shaft furnace.
Soon after mastering the technology of block ironmaking in China, liquid pig iron containing more than 2% carbon was smelted and used for casting tools. In the early Warring States period, China had mastered the technical methods of decarbonization and heat treatment, and invented ductile cast iron. In the late Warring States period, a reusable "iron model" (an empty stomach made of iron for casting metal objects) was invented.
in the western Han dynasty, the crucible ironmaking method appeared. At the same time, the scale of ironmaking shaft furnace has been further expanded. In 1975, an iron smelting site of the Han Dynasty was discovered and excavated in Guxing Town near Zhengzhou, covering an area of 12, m2, and two parallel blast furnace foundations were excavated, with a blast furnace volume of about 5m3. In the Western Han Dynasty, the "steel-frying method" was also invented, that is, a new process of "frying" mature iron or steel with pig iron, and the product was called fried steel.
At the same time, the technology of "Hundred Steelmaking" is emerging. In the Eastern Han Dynasty (AD 25-22), when Emperor Guangwu was in power, he invented the hydraulic blast furnace, namely "water drainage". The invention of ancient water rafts in China was about 11 years earlier than that in Europe.
after the Han dynasty, the method of pouring steel was invented. "Biography of the Northern Qi Dynasty's Book" is called "Sugang", and later it is called "Guangang" and "Tuangang". This is another great achievement of China's ancient steelmaking technology.
According to "A Brief Introduction to Chinese Encyclopedia", China was the first country to use coal to make iron, which was tried out in the Han Dynasty and popularized in the Song and Yuan Dynasties. By the Ming Dynasty (AD 1368-1644), pig iron could be smelted with coke. During the 14th ~ 15th century, the output of iron exceeded 2 million Jin, and the contract was 12, t.. 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 with solid reduction have been used for a long time in the world, and China cast iron and pig iron have been the main methods for steelmaking. Due to the invention and development of cast iron and pig iron steelmaking, China's metallurgical technology had been at the advanced level in the world before the middle of Ming Dynasty.
in the second half of 19th century, Qing Ye government developed modern military industry, manufactured guns and warships, and imported a large number of steel produced in western countries. In 1867, about 8,25 t of steel was imported, in 1885, about 9, t, and in 1891, it increased to 1.7 million tons (about 13, t). Imported steel has gradually occupied the market in China, making it 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.
In p>1871 (13th year of Tongzhi in Qing Dynasty), Li Hongzhang, governor of Zhili, and Shen Baozhen, minister of shipping administration, asked for the opening of coal and iron to help military supplies, and they were granted the request, and were ordered to try it out in Cizhou, Fujian and Taiwan Province of Zhili. In 1875, Zhili Cizhou Coal and Iron Mine ordered an iron melting machine from Britain, but it was far from successful because of the difficult transportation. This shows that at that time, attention had been paid to the establishment of a new type of steel industry.
in p>1886, Pan Wei, the governor of Guizhou province, founded the Green Factory, which first used earthen stoves, and then ordered ironmaking and steelmaking equipment from Britain, which was installed in 1888. In the end, it was closed in 1893 because of corruption in the Qing court, lack of funds, coal and iron ore, poor management and no one proficient in technology. This is an attempt to set up a modern steel plant.