The electrolytic cell is an important component in the electrolysis of aluminum, and the two main factors that affect the life of the aluminum electrolytic cell are the carbon cathode and the refractory lining. Aluminum electrolytic cell linings are divided by region and can be divided into bottom linings and side linings. Functionally, the bottom lining plays a role in supporting the cathode structure and insulating heat. The side lining mainly plays a role in protecting the surface of the steel metal casing from erosion by the electrolyte melt.
The side lining of the aluminum electrolytic cell is an important structural part of the electrolytic cell. It proposes that the side wall material of the aluminum electrolytic cell should have the following important properties at high temperatures: high resistivity, good thermal conductivity, and no contact with molten cryolite. It reacts chemically, has small porosity, is impermeable to electrolyte and aluminum, and is not oxidized by air.
Due to the valence bond structure characteristics of silicon carbide refractory bricks, it has a series of excellent properties, such as high strength, high hardness, high temperature resistance, oxidation resistance, high thermal conductivity, low thermal expansion rate, excellent thermal shock resistance, and good chemical stability. , not wetted by non-ferrous metals, etc., and has good resistance to high-temperature chemical corrosion, and is especially suitable as a refractory material for lining aluminum electrolytic cells.
As the capacity of the electrolytic cell increases, the material structure of the lining on the side of the electrolytic cell has gradually evolved from the early double carbon block plus insulation brick structure to no insulation brick, single layer carbon block, and even today's separate silicon carbide combination Silicon nitride material.
Silicon carbide refractory bricks are a new type of furnace building material that has recently been promoted and used in my country's non-ferrous industry. In recent years, whether pure silicon carbide refractory brick side blocks or composite side blocks are used, varying degrees of breakage and shedding have been commonly found during the production process. phenomenon, and the silicon carbide layer of the composite side block also has a lifting phenomenon.
The temperature difference (bounded by the upper edge of the artificial leg extension) is the main reason for the fracture of silicon carbide bricks. Although silicon carbide bricks have good thermal conductivity and low thermal expansion coefficient, because the products are fired at high temperatures above 1450°C to form a hexagonal structure ceramic body, their thermal shock resistance and temperature difference resistance are poor. In an environment where temperature differences are repeatedly formed between the upper and lower parts of silicon carbide refractory bricks, they are easily broken. This is also a key issue that needs to be solved in the application of refractory silicon carbide bricks in aluminum electrolytic cells.
