Increasing the Efficiency of the Impregnation of Coke with Pitch in the Production of Anode Paste for Aluminum Cells

This article examines problems related to the quality and production of anode paste for self-baking anodes in aluminum electrolysis cells. Results are presented from laboratory tests of a technology designed to thoroughly impregnate coke dust with coal-tar pitch by giving the dust and pitch opposite electrical charges in dc chargers during the paste production process. The technology significantly improves the quality of the paste while reducing its production cost and improving the technical-economic and environmental indices of aluminum production. These benefits are realized by increasing the degree of impregnation of coke dust by coal-tar pitch, reducing the friability of the anodes during service in electrolysis cells, and decreasing the amount of coal-based foam that is formed in the process. Increasing the productivity of the equipment used to make anode paste by shortening the time needed to mix the components also lowers production costs. Environmental indices are improved by shortening the time the cell is dehermetized, thus decreasing the unit quantity of fluorides released into the atmosphere.