Analysis of advantages of graphitized cathode carbon block

The cathode carbon block is the main part of the cathode structure used in the aluminum reduction cell. In the process of aluminum electrolysis, it not only takes the role of the cathode conductor, but also serves as the lining material of the electrolyzer, whether it is the self baking tank or the prebaked slot, so the improvement of the quality of the cathode carbon block not only reduces the electric energy consumption of the aluminum electrolysis production. The important significance is also important for prolonging the service life of the aluminum reduction cell. According to statistics, 90% of the shutdown is caused by the breakage of the cathode carbon block.

The graphitized carbon block has the advantages of good sodium corrosion resistance, low resistivity, high thermal conductivity, strong thermal shock resistance, uniform quality, stable production and energy saving. It is the development trend of cathodic carbon block for large electrolytic cell. At present, the cathodic carbon block with high conductivity, high graphitization and low expansion rate is widely used in the world, which makes the aluminum electrolyzer with lower cathode pressure drop. It greatly reduces the unit power consumption of aluminum electrolysis and reduces the cost. Moreover, the operation of the electrolyzer is stable, and the effect of increasing energy and energy saving has been achieved. The original cathet Aluminum Inc began to try the graphite cathodic carbon block in the 90s of last century, and has been used in more than 200 electrolytic cells of a variety of groove type (100-300kA). After the use of graphitized cathode in 280kA electrolyzer, the current efficiency increased by 2.1% and the cathode resistance decreased by 0.25 Omega. After the use of the graphite cathode in the 300kA electrolyzer, the current efficiency increased by 2.6% and the cathode resistance decreased by 0.25 Omega.

The graphitized cathode carbon block is made of calcined petroleum coke as raw material, by molding, roasting, impregnating and REBAKING, through graphitization furnace (2500~2700 C) to graphitization of aluminum carbon products. The product has low specific resistance (generally 10~12 Omega m), high thermal conductivity, true density, large volume density and low stomatal rate.  The utility model has the advantages of corrosion resistance, long service life and low power consumption during the electrolytic process.

The physical and chemical properties of the cathode carbon block are low in the small current small self baking tank and precalciner. Generally, the common cathode carbon block and the semi graphite cathode carbon block produced by the addition of a small amount of graphite from the calcined coal and the electric calcined coal can meet the requirements of the electrolytic production process.

After the 90s of last century, the world's major Aluminum Inc began to focus on the large-scale electrolyzer and the stability of production and operation, and to strengthen the current and increase production capacity. In order to reduce the pressure drop of the cathode and create more space for the energy saving or the strengthening of the current, two is to reduce the load of the heat flow in the area of the bath melt. In order to form a complete furnace and maintain stability, three is to enhance the corrosion resistance of cathode carbon block and prolong the service life of cathode.

Although the life of the electrolyzer has been reduced from the transition from the semi graphite and graphite carbon blocks to the graphite carbon block, almost all the electrolytic aluminum plants that have been used as graphite carbon blocks are reluctant to return back and reuse graphite or semi graphite carbon blocks. This is because the use of graphitized carbon block is the need to increase the unit area capacity of the electrolytic cell. The properties of graphitized carbon block are uniform, and the probability of local early breakage (usually leading to the rejection of the entire lining) is very small. This is especially important for large tanks.