What is ferroalloy?
Ferroalloy is a kind of additive used for steelmaking and casting. It is composed of Ferro and other elements, which mainly is used as deoxidizer or alloying agent for steelmaking.
Methods of ferroalloy production
There are various ferroalloy smelting processes such as carbon reduction method, metallothermic reduction, electrolytic process, and refining process, etc. Different kinds of ferroalloys and quality requirements adopt different smelting processes.
Blast furnace process
The blast furnace process is the earliest industrial large-scale production method of ferroalloy. The blast furnace process of ferroalloy smelting has the advantages of high output and low cost. It uses the heat produced by burning coke to smelt ferroalloy. The coke is not only used as fuel but also used as a reducing agent.
The blast furnace process produces the ferroalloys such as:
- Ferro manganese
- Ferro silicon (Si: 10-15%）
- Silicon manganese
After the addition of manganese ore, coke, and a fluxing agent from the furnace top, blow the high-temperature air or oxygen through the tuyere, carry out the reduction reaction by the heat of burning coke. The molten metal and slag gathered in the furnace and tapped through the iron notch. Adding the materials continually so that keep the continuous production. Due to the temperature of the furnace being comparatively low, the ferroalloy is carburized.
In recent years, using oxygen-rich high temperature and other processes, the silicon manganese can smelt in the blast furnace.
Electric furnace process
The electric furnaces are mainly divided into submerged arc furnaces and refining furnaces. The arc furnace process is using carbon as a reducing agent to produce ferroalloys. It is the main method of ferroalloy production, about three-quarters of ferroalloys, are manufactured by this method.
The electric furnace process produces the ferroalloys such as:
- Ferro silicon
- Silicon manganese
- HC Ferrochrome
- Silicon Calcium
- Silicon chromium
In the smelting process, the carbon is used as a reducing agent, the mixed materials are added through the furnace mouth, three electrodes are put into the furnace charge. The electric arc and electric current passing through the furnace charge generate the resistance heat, which heats the furnace charge. By adding the new materials continuously from the furnace mouth, the production is continuous.
The raw materials of ferrosilicon are silica, coke, and steel scrap.
The raw materials of high carbon ferromanganese are manganese ore, coke, fluxing agent lime, etc.
The electro-silicothermic process is using the silicon element (ferrosilicon, silicomanganese, or silicon chrome) to reduce the ore, oxide, or slag, and uses lime as a fluxing agent to produce ferroalloys.
The products made by this method contain lower carbon content.
The electro-silicothermic process produces ferroalloys:
- Micro carbon FeCr
- MC ferrochrome
- LC ferrochrome
- MC&LC FeMn
Metallothermic reduction process
The metallothermic reduction process is heating the alloy and slag by the chemical heat generated by the reduction reaction, and making the reaction without external heating.
Metallothermic reduction process produces:
- high ferrotungsten
- high vanadium ferroalloy
The converter process is adding molten high carbon ferroalloy(HC ferrochromium) in the converter, and treating it with oxygen decarburization. The production is carried out intermittently.
The converter process produces:
- Low carbon ferrochromium
- Medium carbon ferrochromium
- Low carbon ferromanganese
- Medium carbon ferromanganese
The ferroalloy is an indispensable part of the steel industry and foundry industry. The price, and quality of ferroalloy influence the cost and quality of the steel. China is one of the most important manufacturing countries in the world. Chinese ferroalloy manufacturers keep on researching and developing ferroalloy production methods, to provide high-quality cheap ferroalloy for the world’s customers.