Classification and properties of cathode pastes for aluminum electrolysis
The function of aluminum reduction cell paste is to fill the space between the single cathode carbon blocks laid on the bottom of the cell and between the cathode carbon blocks and the side carbon blocks. After roasting, the bottom and side of the cell form a complete sealed cell body, so as to avoid the leakage of electrolyte and aluminum liquid during roasting and operation; At the same time, as a part of the cell, it can balance the heat generated in the electrolysis process with the heat lost at the side, so as to improve the electrical efficiency and prolong the service life.
At present, the electrolytic cell capacity has entered the super large era of 400ka-600ka. The annual production capacity of a single series is more than 400000 tons. The investment is huge, and the requirements for furnace building, operation and management of the electrolytic cell are higher. The paste is the fatal material of the electrolytic cell, and its performance directly affects the success of the electrolytic cell startup and the length of its life. According to the design requirements or the characteristics of cathode carbon block, the correct selection of paste is the basic requirement of aluminum reduction cell furnace building technology. According to the product standard of cathode paste for aluminum electrolysis (ys/t65-2007) issued in 2007 and the revised exposure draft issued in 2011, cathode pastes for aluminum electrolysis are divided into three categories and 11 brands according to their physical and chemical properties, applicable parts of products and construction temperature. See Table 1 for the classification and use of various pastes.