Structure, classification and use of submerged arc furnace

What is a submerged arc furnace?

A submerged arc furnace, commonly known as an electric furnace, is an electro-metallurgical equipment that uses the arc heat at the end of the electrode and the resistance heat of the charge or slag to convert electrical energy into heat energy, so that useful elements such as metals are reduced from ore or oxides. It is mainly used for the reduction and smelting of metal oxide ore, so it is called submerged arc furnace or submerged arc reduction electric furnace. In addition, since most of the arcs of submerged arc furnaces are deeply buried in the charge, they are also called submerged arc furnaces or submerged arc furnaces.

The use of submerged furnace

The submerged arc furnace is called iron alloy furnace when it is used to produce ferroalloy; it is called calcium carbide furnace when it is used to produce calcium carbide; it is called yellow phosphorus furnace when it is used to produce yellow phosphorus; it is called copper matte furnace when it is used to produce matte; it is used for ferroalloy When refining, it is called a submerged thermal refining furnace; when it is used to melt the pre-reduced charge and separate the metal from the slag, it is called a melting furnace.

When producing ferroalloys in submerged arc furnaces, most of them use coke as a reducing agent, and use different raw materials according to different production varieties. and other series of ferroalloy products. When the submerged arc furnace produces calcium carbide, coke is still used as the reducing agent, calcium oxide (lime) is used as the raw material, and calcium carbide (the main component is calcium carbide) is obtained by smelting in the furnace. The submerged arc furnace uses vanadium titanomagnetite as the raw material, and when coal is used as the reducing agent, the titanium slag is obtained through the furnace smelting, and the vanadium-containing molten iron and other products are obtained. Therefore, submerged arc furnace is a smelting equipment covering ferroalloys, chemical industry, ferrous metals, non-ferrous metals and other industries.

The basic structure of submerged electric arc furnace

Submerged arc furnace is a kind of complex electro-metallurgical equipment, which consists of electric furnace body, furnace transformer, high current conductor (short network), electrode system, submerged arc furnace charging system, cooling system, high and low voltage power distribution system, monitoring and automation It is composed of system, iron tapping and slag tapping system, smoke exhaust and dust removal system.

The high-voltage electric energy provided by the power grid is converted into low-voltage and high-current through the special transformer used in the submerged arc furnace, and the current is sent to the electrode through the high-current conductor, and is input into the furnace through the carbon electrode, generating resistance heat and heat between the charges around the electrode. The arc heat generated at the end of the electrode converts electrical energy into thermal energy, thereby forming a high-temperature reaction zone in the furnace body to carry out the reduction reaction of metal oxide ore. Usually, a carbonaceous reducing agent such as coke is used to continuously add coke and reduced metal oxide ore raw materials into the furnace. The reduction reaction in the reaction zone is carried out continuously, and the obtained liquid products are accumulated in the molten pool. It is released, the molten metal is poured and refined to obtain an alloy product, and the slag is water-quenched or poured for reuse.

Classification of submerged arc furnaces

Submerged arc furnaces are mainly divided into circular submerged arc furnaces and rectangular submerged arc furnaces. Since a large amount of furnace gas (that is, flue gas) is generated during smelting and production of submerged arc furnaces, circular submerged arc furnaces are divided into open furnaces with high hood, semi-closed furnaces and closed furnaces according to the method of flue gas capture. There are fixed and rotating points. The rectangular submerged arc furnace is generally a closed structure with a fixed furnace body.

Open furnaces with high smoke hoods have been gradually phased out because the smoke hoods hang high above the furnace body, causing serious environmental pollution and high energy consumption.

The semi-hermetic submerged arc furnace (ie low-smoke hood furnace) seals the furnace mouth with a fume hood, and only has an operating door on the side of the fume hood. The combustion flame on the stove top of this kind of stove is still larger, but the radiation heat dissipation on the stove top is reduced. According to the management level of the production enterprise and the difference in the selection of furnace design parameters, the various consumption indicators of this type of submerged arc furnace are quite different, the utilization rate of energy has a large gap, and the treatment level of the flue gas released in the production process is also different. , Some enterprises' flue gas purification devices can use high-temperature flue gas to produce steam to realize waste heat utilization, and the energy utilization rate has been greatly improved.

The airtight submerged arc furnace is completely sealed from the furnace cover and the furnace body, so there is no combustion on the furnace surface, and the gas generated in the furnace is extracted and purified by air extraction equipment. The capacity of the closed furnace is generally large and the degree of automation is high. The amount of flue gas is greatly reduced due to the sealing of the furnace, thereby reducing the energy consumption of the flue gas dust removal system. Generally, the comprehensive utilization of flue gas is carried out, such as steam production, waste heat power generation, The raw materials are dried and used as gas, and the dust collected by the dust collector can be reused, so the comprehensive energy consumption is low and the element recovery rate is high.