Blast furnace

The furnace is designed for smelting pig iron. First appeared in the XV century. in Europe. In Russia, the first blast furnace was built in 1620 near Tula. Then fuel for such furnaces was charcoal. Only a century later (1709), the English inventor Abraham Derby managed to carry out blast furnace smelting, replacing charcoal wood with coke coal and coal.

Centuries-old experience has changed the blast furnace's design, its appearance and the cast iron production scheme itself . But the basics remained the same. Today, a blast furnace is a construction of about 30 meters (height varies ± 5 m). The height of the entire structure can exceed 80 m.

How does the blast furnace work?

Through the top (koloshnik) charge is loaded (agglomerate, pellets, iron ore, manganese ore , fuel and fluxes). Below is the mine, the largest part of the blast furnace, which is an expanding cone. Due to this expansion, it is easier to lower solid materials that increase the volume when heated. The bottom (broad, cylindrical) is adjacent to the bottom of the shaft. In it melts charge. Behind the rasp, below, are the shoulders, made in the form of a truncated cone with a reduced base beneath. Such a cross section is most suitable for a material volume that decreases as a result of melting.

In the cylindrical furnace, the lower part of the profile, there is burning of coke and a liquid product of melting is collected.

The horn is divided into parts: the upper zone (the tuyere) and the lower one (the metal receiver, in which the products of the smelting are collected). The lower part of the furnace is called the bottom.

In the tuyere zone there are tuyere devices that feed blast furnace (heated air) into the blast furnace. It is this site that is responsible for the burning of coke, the temperatures here grow to its maximum values of 2000 degrees. At the top of the top the temperature is lower (up to 350 degrees).

In the lower part of the hearth is built a cast iron tapper, skipping the products of melting - slag and cast iron itself.

Previously, slag tap was used, but the practice of the last decades has shown that it is more practical to pass slag and cast iron through a tap-cast iron, with their further separation in the main trench adjoining the furnace.

The furnace is adjoined by the so-called foundry, where the devices that open the cast iron tap and close it after the release of slag and cast iron. Here there are gutters with ditches, directing the product of melting into buckets.

The product released from the oven is sent to the main chute where the cast iron is separated from the slag (density difference). From the gutter go two ditches. Slag is sent one by one, and cast iron by another. Cast iron is poured over continuously moving forms (conveyor type), after cooling down the molds are overturned and further the cast iron is directed to the wagons. Slag is poured into pools, cooled by water and granulated.

Each furnace height has its own specific temperature, which is why the process of transition to the metal from the ore flows.

A sufficient amount of oxygen is supplied to the lower part of the furnace to burn the coke. Coke burns, converting to carbon dioxide, which reacts with coke, converting already into carbon monoxide. Then there is a reaction between carbon monoxide and iron oxides. There is a restoration to the metal. Iron is saturated with carbon and cast iron is produced. In addition to three to four percent of carbon, in the alloy in minor proportions are present manganese and silicon, sulfur and phosphorus.

Actually, a blast furnace, the principle of operation of which has been described here, may well be considered a non-waste production. By-products, appearing in the process of production, quite find use outside the walls of factories for the production of cast iron. The slag is added to the cement, suitable for buildings (so widely used now is the cinder block), and blast furnace gas serves as a good fuel that heats the air fed to the blast furnace.