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Ferroalloy ore furnace structure and refractory for optimum furnace lining
Dec 20, 2018

The ferroalloy smelting process is a high temperature physical and chemical process, and the furnace structure of the ferroalloy ore furnace must fully meet the special needs of use. The furnace body of the ferroalloy ore furnace is composed of a furnace shell and a furnace lining made of a certain thickness of the boiler steel plate. Most of the furnace shells are cylindrical, and a few are conical. The cylindrical furnace shell has a small heat dissipation area, high strength, and easy processing, which is conducive to energy saving. The furnace shell is required to have sufficient strength to withstand the thermal stress generated by the swell of the lining after being heated. The furnace shell must have a certain thickness. Generally, the large furnace is a 15~20mm boiler steel plate, and the small furnace is a steel plate of about 10mm. In order to improve the strength of the furnace shell, in addition to the reinforced reinforcement along the longitudinal direction of the steel plate, there are also 2 to 3 horizontal reinforcement rings, and the taphole flow groove is also made of steel plate or cast steel.


 


The lining of the submerged arc furnace is a more important part of the furnace body, because it has to withstand high temperature during use. Although some electric furnaces are separated from the high temperature and temperature arc by the charge and the slag shell, the lining still has to withstand the high temperature of 1400~1800 °C. It also has to withstand the mechanical scouring of the charge, high temperature furnace gas and molten iron water, which is easily eroded, softened, eroded or even cracked by the physical and chemical attack of the slag. Damage to the lining will directly affect the normal operation of the smelting process. If it is not damaged, only the thermal insulation performance is not good, and the heat dissipation of the furnace shell will increase, and the electric energy consumption will increase. Therefore, the lining should be built with special building materials, refractory materials and insulating materials.


The requirements for these refractory materials for the blast furnace lining are:


1 has high refractoriness and can withstand high temperature;


2 has sufficient strength at high temperature and low temperature;


3 can withstand temperature changes without damage, that is, it has high resistance to chilling and heat;


4 has sufficient chemical resistance;


5 large heat capacity, small thermal conductivity, that is, good thermal insulation performance;


6 volume expansion coefficient is small;


7 has a certain conductivity, or insulation.


The well-constructed and well-welded furnace shell is placed on the I-beam, which is a rail embedded in the concrete foundation. The I-beam overhead of the furnace shell is to form an air insulation layer, which reduces the heat dissipation of the furnace body and also avoids overheating of the steel plate at the bottom of the furnace.


 


The ore furnace lining tightly protects the steel plate with the best thermal insulation material: asbestos board, asbestos ash or refractory insulating clay, etc., and the thickness is 10-25mm. The inner 40-80mm buffer layer is composed of water slag and slag bulk material. This layer requires a certain compressibility to meet the thermal expansion of the lining, avoiding the thermal expansion force directly transmitted to the furnace shell, resulting in a furnace shell. Burst and other issues. It is also a layer of air insulation that can provide some insulation. Inside is the refractory clay brick, which is a low-temperature refractory layer, which also has certain heat insulation and oxidation resistance to protect the inner inner brick from oxidation. The inner layer is a carbon brick layer with a refractoriness of up to 3000 ° C, ie a working layer. Some varieties of smelting furnace working layers use magnesium bricks, silicon bricks and so on. Special attention should be paid to the masonry of the tapping part of the furnace. It is necessary to prevent the air from entering the vicinity of the tapping port without leaving a buffer layer, and it should be processed with integral carbon bricks. The tapping trough should be tightly connected with the carbon bricks in the furnace to avoid Leakage of molten iron or oxidation of carbon bricks.


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