- Time:Jul 11, 2022
The steel industry accounts for a large proportion of refractory material consumption. In non-ferrous smelting, the large proportion of refractory material consumption depends on the aluminum industry in non-ferrous smelting. Metal aluminum is prepared by wet bauxite to obtain alumina, and then molten salt electrolysis is used to prepare metal aluminum. The kilns used in the production of metal aluminum and aluminum include rotary kilns, fluidized flash roasting furnaces, suspension roasting furnaces, circulating fluidized bed roasting furnaces, molten salt electrolytic cells, aluminum melting furnaces, tank roasting furnaces, carbon roasting furnaces, etc. . The temperature of smelting aluminum is not very high, but the erosion and penetration of molten aluminum are particularly strong, and the damage to the refractory structure is very serious.
There are three main reasons for the damage of refractory materials.
1. Due to the strong permeability of aluminum water, it will penetrate into the pores or small cracks of the refractory material during use, causing the structure of the refractory material to gradually loosen and peel off, and eventually damage the refractory material; Impurities undergo physical and chemical reactions. Substances produced during the reaction can affect the quality of the aluminum product.
2. The molten aluminum reacts with the refractory material and adheres to the refractory material, forming surface nodules, bulges and deposits, which are not easy to remove. In general, refractory materials will be damaged if cleaned mechanically.
3. During the production process of the aluminum melting furnace, mechanical operations such as feeding and slag pulling will hit the furnace case, furnace wall and furnace bottom, causing serious wear and tear, which is also an important reason for the damage to the refractory material of the aluminum melting furnace.
Solve the above three aspects:
1. Increase the density of refractory materials and reduce the porosity of refractory materials. The refractory itself has high density and low porosity, which can effectively prevent the penetration of molten aluminum and its alloys;
2. Aluminum water corrosion resistant material. The refractory material has excellent resistance to the wetting of aluminum water, which can effectively prevent the penetration of aluminum water and prevent the adhesion of aluminum water and aluminum slag. SiO2 in refractory materials. Impurities easily react with Al and Mg in the molten aluminum, causing the volume of the refractory to change, causing the refractory to form cracks and accelerating the erosion of the refractory by the molten aluminum. Therefore, the higher the aluminum content of the refractory material, the higher the purity, the lower the probability of reaction with aluminum water, and the better the corrosion resistance. At the same time, admixtures such as barium salt and chromium salt can also be added to react with aluminum water to form a protective layer to improve the corrosion resistance of refractory materials;
3. Wear resistance of refractory materials. The wear resistance of refractory materials is mainly to improve its strength, which can effectively improve the wear resistance and mechanical impact resistance of refractory materials.
Alumina rotary kiln lining structure
The kiln head cover and kiln flange are refractory castables, the decomposition zone, preheating zone, firing zone and cooling zone are shaped kiln lining refractory brick masonry, rear lifting plate area, kiln tail cover and flue are refractory castables . A block ring is arranged between the refractory brick and the refractory castable. The block ring is made of 20mm thick steel plate.
Unshaped refractory material for aluminum melting furnace.
For some parts with difficult masonry, special working environment and complicated process, such as nozzles, feeding door frames, arches, special vaults, etc., pouring materials or prefabricated parts of new refractory materials can be widely used to make up for the dead zone of the corner furnace. of the triangular wall. The use of these non-standard, non-formed refractory materials not only saves a lot of time for sawing bricks, forming and masonry, but also the lining components composed of non-forming materials have good integration and long life. At present, the application ratio of new and unformed refractory materials in domestic aluminum melting furnaces is not enough. After using high-alumina phosphate refractory pouring materials to prefabricate the feeding port of masonry, the service life of the feeding port is 2~3 times of the original. . It is worth mentioning that due to the lively nature of aluminum, it can constantly exert physical and chemical effects with the furnace lining material. The selection principle of new and unshaped materials is the same as that of traditional shaped materials. High alumina aggregates and admixtures should be preferred over siliceous, semi-silicon or ordinary clay products.
Aluminum electrolytic cell
The basic structure of aluminum electrolytic cell lining can be divided into integral tamping type, semi-integral tamping type and masonry type.
1. Overall tamping type. All carbon in the lining is locally tamped with plastic carbon paste, and the lower part is alumina as insulation and refractory material, or refractory bricks and lightweight refractory bricks.
2. Semi-integral tamping type. The bottom carbon body is made of cathode carbon block, the side is rammed with plastic carbon paste, and the lower thermal insulation refractory is similar to the overall rammed type.
3. Masonry type. The bottom of the masonry is made of carbon blocks, the sides are made of carbon blocks or silicon carbide and other materials, and the lower part is made of refractory, thermal insulation and anti-seepage materials such as heavy refractory bricks and light refractory bricks. According to the different treatment methods of the bottom carbon block and its surrounding gap, the masonry type is divided into two types: two types of tamping bonding. The former type is to leave a gap between the bottom carbon block and the side block when masonry, and then tamping with paste; the latter type has no gap and the block is bonded with carbon glue.
In addition to the refractory brick joints and size requirements, it should also be checked whether the masonry quality is carried out according to the basic rules of industrial furnace masonry, and whether the masonry refractories are qualified.
The plumpness of the masonry brick mud should be checked with a feeler gauge in time. The width of the feeler gauge is 15mm, and the thickness is equal to the thickness of the inspected brick joint. If the corresponding feeler gauge depth does not exceed 20m, the brick is considered to be sewn. When checking the thickness of the feeler gauge, use a feeler gauge to check 10 positions per 5m2 surface, and the brick joints that are 80% larger than the specified brick joint thickness shall not exceed the positions specified in the following table.