Refractories are the main materials for aluminum smelting at high temperature. Aluminum smelting furnaces mainly include reverberatory furnace, rotary drum furnace and induction furnace, and the operating temperature is generally 700-1000 ℃. The damage of this kind of furnace lining is mainly caused by the penetration and scouring of molten aluminum. The lining is generally built with clay brick, high alumina refractory brick and corundum mullite brick. It can also be made of high alumina refractory castable and refractory plastic. Due to good service conditions, the furnace has a long service life.
1. Refractories materials for reverberatory furnace
The furnace is divided into fixed type and tilting type. Generally, gas or heavy oil is used as fuel. Aluminum smelting is usually carried out by using fixed reverberatory furnace. The non working layer is built with refractory fiber felt and clay insulating refractory brick. The working layer above the molten pool is built with clay brick. It can also be hoisted with high alumina refractory castable blocks or poured on site, or rammed with high alumina refractory plastic. The working layer of the molten pool is made of different materials according to different key techniques, Generally, high alumina refractory bricks with Al2O3 content of more than 75% are used for masonry, and high alumina refractory castables with Al2O3 content of more than 80% can also be used for pouring into an integral working layer. When smelting high-purity metal aluminum, the working layer of molten pool should be built with high-purity mullite brick, zircon brick or corundum brick, or Zhisheng 233 high-temperature thermal reflective coating can be added as thermal energy-saving layer, Effectively protect refractory materials and reduce heat radiation and heat dissipation. In order to resist the penetration and erosion of molten aluminum, large silicon carbide bricks are generally used for aluminum outlet, flow aluminum tank and its lining.
The refractory materials used in the moisturizing furnace and its flux and alloy material treatment room are basically the same as those of the reverberatory furnace. When aluminum ingot or waste aluminum is used as raw material, it can be directly loaded into the furnace from the charging port for smelting. When electrolytic aluminum liquid is used as raw material. First, suck out the aluminum liquid from the bottom of the aluminum reduction cell with a siphon or vacuum bag, and then transport it to the reverberatory furnace. Pour it from the charging port. After charging, while heating, blow chlorine into the molten pool for dehydrogenation and burial. The siphon lining is generally made of refractory fiber reinforced light refractory castable as the thermal insulation layer. It can also be built with clay thermal insulation refractory bricks. Its working layer is generally built with dense clay bricks or corundum bricks. The insulation layer in the vacuum package is the same as that of the siphon. The working layer is built with high-quality clay brick or high alumina refractory brick. Under normal operation, the service life of reverberatory furnace and holding furnace is generally 2-5 years.
2. Refractory materials for rotary furnace
The non working layer of the furnace is built with clay thermal insulation refractory brick or floating bead brick, and can also be poured with light refractory castable with bulk density of 1.0g/cm3 or made into prefabricated block masonry: the working structure is built with dense clay brick or high alumina refractory brick with aluminum content greater than 55%. The furnace life of rotary drum furnace is generally 300-500 heats. When adding salt flux to melt aluminum block. Due to the aggravation of chemical erosion, the furnace life is reduced. In this case, high temperature resistant sealing coating can be applied as a protective layer, which has obvious anti-corrosion and anti-oxidation effect.
3. Refractory materials for induction furnace
The furnace lining is generally built with clay brick or three-level high alumina refractory brick. Sometimes, the base course is poured with high alumina refractory castable at the furnace bottom, and then high alumina refractory bricks are built. When the capacity of induction furnace is less than 10t, its lining can be made of high alumina refractory castable or refractory ramming material with Al2O3 content of about 75%, or corundum refractory castable or dry vibrating material. The lining around the inductor coil of the furnace is generally poured as a whole with corundum refractory castable or vibrated and compacted with dry vibrating material. Due to different types of raw materials and exploration conditions, the service life of the furnace is also different. Generally, the furnace life is 0.5-4.0a. During use, the vulnerable parts such as the lining around the coil shall be subject to minor repair for 1-5 times.
4. Refractory for aluminum holding furnace
Aluminum holding furnace is divided into trough induction furnace, resistance heating pool furnace and gas chamber furnace. Due to the low working temperature, this kind of equipment generally uses clay brick and other materials as the lining, which also obtains a high service life.
5. Refractory for trough induction furnace
The lining structure of the furnace is to lay 10mm asbestos board or refractory fiber felt against the furnace shell, and then lay clay heat insulation refractory brick or floating bead brick as heat insulation layer; The working layer of the furnace and the lining around the coil are generally made of clay fire-resistant ramming material, or can be poured on site with clay fire-resistant castable. The working layer of large groove induction furnace is built with high alumina refractory brick with Al2O3 content greater than 55%, and high alumina brick combined with ZS-1 high temperature resistant and thermal insulation coating is used as the added thermal insulation layer. The effect of refractory material is good.
6. Refractory for resistance heating pool furnace
The non working layer of the furnace is built with clay heat insulation refractory brick, floating bead brick or heat insulation board. It can also be poured integrally with light refractory castable with bulk density of 0.8g/cm3; The working layer of molten pool is built with high alumina refractory brick with Al2O3 content of about 80%, and can also be poured with high alumina refractory castable with bulk density of 2.4g/cm3. The working layer above the molten pool is generally built with clay brick or refractory castable precast block, or it can be tamped with high alumina refractory plastic.
7. Refractory for gas chamber furnace
The furnace is composed of furnace bottom, furnace wall and furnace top. It can be used alone. In order to save energy and facilitate management, it can also be used in combination with aluminum smelting reverberatory furnace. The furnace lining is made of clay brick and high alumina refractory brick.
8. Refractory for aluminum water tank
Aluminum water tank is a thermal equipment used for holding aluminum liquid, transportation and casting. The non working layer of the tank wall is built with clay insulating refractory bricks, and can also be poured with light refractory castable with bulk density of 1.5g/cm3. The working layer is built with clay brick or high alumina refractory brick, and can also be poured with alumina hollow ball refractory castable as a whole; The tank bottom is built with high alumina refractory brick or poured with corundum refractory castable as a whole, and the surface is coated with refractory coating as a protective layer. Due to the impact and erosion of molten aluminum, the casting mouth is generally built with silicon carbide brick, corundum brick or fused quartz brick. Chinese common stopper device is used to control the pouring of molten aluminum in aluminum tank.
9. Refractories for aluminum refining
The thermal equipment used for refining is electrolytic cell. The cell wall is built with magnesia bricks, and the rest parts are made of clay bricks and high alumina refractory bricks. During electrolysis, the cell temperature is generally 720-800 ℃. The cell lining has good service conditions and low operating temperature, so it has a long service life.