According to the heat source, they can be divided into carbon-thermal, electrothermal, electrosilicon, and metal-thermal methods.
In the carbon-thermal method, the heat source for smelting is mainly the calorific value of the coke, and part of the coke is also used as a reducing agent to reduce the oxide content of the ore. Production takes place in a blast furnace.
In the electric heating method, the heat source for the smelting process is mainly electrical energy, and
carbonaceous materials are used as reducing agents to reduce the oxide content of the ore. Production is mainly carried out in a continuous way in a furnace with a mineral heat source, such as ferrosilicon and ferromanganese.
In the electric silicon heating method, the silicon or silicide of the alloy element to be extracted is used as a reducing agent to reduce the oxide content of the ore. The source of heat is partly the chemical heat released during the oxidation of silicon, and most of the insufficient heat comes from electrical energy. Ferroalloys are produced by this method in a batch electric arc furnace, for example, medium- and low-carbon manganese and rare-earth alloys.
In the metallothermal method, aluminum granules and 75% ferrosilicon powder, and sometimes a mixture of silicon and aluminum, are often used as reducing agents. The use of silicon as the main reducing agent is called the silicon thermal method, and the use of aluminum as the main reducing agent is called the aluminum thermal method.
