A cathode paste that can be built at room temperature. The aggregate of this cathode paste is the same as that of ordinary cathode paste (also known as hot ramming paste), such as common calcined anthracite or electric calcined anthracite, metallurgical coke, graphite chips, etc. The low softening point of the binder is 20 ℃± 5 ℃.
Cold rammed paste has low softening point and high volatile content. It should be packed in woven bags and plastic bags with a shelf life of 6 ~ 9 months. The construction temperature of Cold ramming paste is 25 ~ 50 ℃, and it can be constructed under the ambient temperature in summer: stewing paste can be used to make up for the impact of low ambient temperature in spring and autumn. The stewing temperature is 40 ~ 50 ℃. Furnace building in northern winter will affect the masonry quality and the service life of the trough.
Before the 1970s, the hot ramming paste or aluminum electrolytic cell used in China’s aluminum industry borrowed the coarse seam paste, fine seam paste used in iron making blast furnace or the paste using petroleum coke as aggregate. With medium temperature coal tar pitch as binder, the construction temperature is high, the environmental conditions are poor, the labor intensity is high, and the construction quality is difficult to guarantee. In the 1970s, carbon materials with softening temperature lower than 80 ℃ called cold binding paste were developed for iron smelting blast furnaces and aluminum reduction cells. With the expansion of aluminum reduction cells and the renewal of cathode carbon blocks, people began to pay attention to the matching use of cathode paste and cathode carbon blocks. Petroleum coke has been eliminated as the main raw material for the production of cold rammed paste. Ordinary calcined anthracite and high-temperature electric calcined anthracite are widely used, and a small amount of graphite is added. Cold ramming paste has become a special material for aluminum reduction cells, which is popularized throughout the country and promoted to large cells. The following table shows the quality of cold rammed paste. In order to match with the titanium boride composite cathode block, titanium boride composite cold ramming paste was developed. The commonly used formula of Cold ramming paste is as follows: (1) binder. Accounting for 15% – 16% of the total paste. Softening point 20 ℃± 5 ℃. Its composition is: ① medium temperature coal tar pitch 70% ± 2% anthracene oil 30% ± 2%; ② Medium temperature coal tar pitch 40% ± 2% + coal tar 50% ± 2%.