The lining of submerged arc furnace is composed of thermal insulation layer, thermal insulation layer, thermal insulation layer and working layer. The smelting process is in a complex environment of high temperature, corrosion and heat loss. The damage of the lining increases the energy consumption and production cost. Therefore, optimizing the lining structure is an important direction of energy saving of submerged arc furnace.
Types and structure of refractories for submerged arc furnace
The refractory materials used in the lining of nickel iron ore hot furnace include carbon brick, chrome magnesia brick and magnesia ramming material. Carbon bricks are used to build the furnace wall and bottom. Due to the use of electrode paste in the process of carbon brick masonry, under the action of high temperature, the electrode paste produces volatiles, resulting in micro joints between carbon bricks, and liquid ferronickel will penetrate into the bottom of carbon bricks from the micro joints to float the carbon bricks. When magnesia carbon brick or carbon brick is used to build the furnace bottom, the magnesia carbon brick also floats up. Magnesia ramming material is generally used for furnace bottom masonry, and its composition is generally MgO ≥ 85%, Fe2O3: 4% ~ 6%, Cao: 7% ~ 9%, SiO2: 1% ~ 1.5%. Using magnesium ramming material, the service life of furnace bottom is obviously prolonged, which is related to the strong impermeability of magnesium ramming material. Magnesia chrome brick solves the penetration problem of magnesia brick, significantly improves the slag resistance, has stable volume at 1800 ℃ and high temperature strength.
In the actual selection, the use of magnesium ramming material can prolong the service life of furnace lining and achieve the effect of energy saving; Increase the thickness of thermal insulation layer, use refractory materials with large single area, such as 400mm * 400mm, and increase the contact area between furnace lining and furnace shell. The thermal insulation effect is good, and the furnace lining is not easy to float up; Using materials with good heat insulation effect can reduce the heat loss of furnace lining.
In order to improve the service life of cast iron electric furnace lining, forced water cooling slag hanging lining can also be used. The process is to build the furnace with low thermal resistance refractory materials and equipped with cooling facilities. By cooling the furnace shell, the molten iron or slag on the inner surface of the furnace lining forms a solidification layer, which separates the furnace lining from the slag iron, so as to protect the furnace lining. Due to the small thermal conductivity of solidification layer, the heat loss of submerged arc furnace can be reduced, so as to achieve the purpose of power saving and energy saving. The cooling methods include furnace shell water spray and preset water-cooled copper sleeve in the furnace wall. The advantage of this process is to reduce the temperature of furnace wall and control the temperature of furnace lining. Although the cost of preset water-cooled copper sleeve is high, the effect is good and the service cycle of furnace lining is greatly improved.
The water-cooled round stainless steel equipment in the furnace of submerged arc furnace mainly includes large sleeve, small sleeve (conical ring), smoke hood framework, water-cooled ring, water-cooled blanking pipe, etc. these equipment are in the high-temperature area of electric furnace during operation. The large sleeve, small sleeve and water-cooled blanking pipe need to enter the furnace through the hole of water-cooled ring of smoke hood framework to realize the functions of electrode guidance, holding electrode, blanking, etc. Under normal working conditions, the small sleeve transmits the electric energy transmitted from the short network to the electrode through the copper tile by holding the conductive copper tile. Therefore, the small sleeve is an important charged body, and its insulation is realized by hanging the insulating flange.