Ferroalloy is an alloy formed by one or more concentrated elements and iron elements. According to element classification, it is mainly divided into silicon series, manganese series, and chromium series. According to the classification of carbon content, it is divided into high carbon, medium carbon, low carbon, micro carbon, ultra-micro carbon, etc. According to the production methods, it is divided into blast furnace ferroalloy, electric furnace ferroalloy, ferroalloy produced by outside furnace (metal heating method), ferroalloy produced by vacuum resistance furnace, ferroalloy produced by oxygen converter, etc.
It is mainly used to produce easily reducible elemental ferroalloys and low-grade ferroalloys. At present, it is mainly used to produce Fe-Mn, and the production process is basically the same as that of blast furnace pig iron smelting. Advantages: continuous production, high production efficiency and low cost; Disadvantages: the temperature in the furnace is low, refractory elements cannot be reduced, and the production varieties are limited.
The main method of producing ferroalloys, with the output accounting for 80% of all ferroalloys. The main equipment is an electric furnace, which is divided into two types: reduction furnace (submerged arc furnace) and electric arc furnace (refining furnace). The products include ferrosilicon, industrial silicon, high-carbon ferromanganese, silicon-calcium alloy, high-carbon ferrochromium, etc.
Reduction furnace: Its production features are that the electrodes are inserted into the furnace charge, the submerged arc operation is carried out, and the ore is heated by resistance and electric arc to reduce it, so it is also called a submerged arc furnace.
Electric arc furnace: An electric furnace that uses the high temperature generated by electrode arc to melt ore and metal. It has great technological flexibility, can effectively remove impurities such as sulfur and phosphorus, and is easy to control the furnace temperature, with a small equipment occupation area. It is suitable for smelting high-quality alloy steel.
Silicon, aluminum or aluminum-magnesium alloy are used as reducing agents, and smelting is carried out by chemical heat energy generated by reduction reaction. The main equipment is a barrel furnace, and the raw materials used are concentrated, reducing agent, flux, heating agent, steel scraps, iron ore, etc.
The main equipment used in the oxygen converter method is the converter. According to its oxygen supply methods, there are top, bottom, side blowing and top-bottom combined blowing methods. The raw materials used are liquid high-carbon ferroalloy, pure oxygen, coolant and slagging materials, etc. The liquid high-carbon ferroalloy is put into a converter, high-pressure oxygen is introduced into the furnace through an oxygen lance for blowing, and decarburization is carried out intermittently by the heat released by the oxidation reaction.
The vacuum resistance furnace method is used to produce low-carbon ferrochromium, ferrochrome nitride, ferromanganese nitride and other products, and its main equipment is a vacuum resistance furnace.