PJSC RUSAL Bratsk, Bratsk, Russia:

E. Yu. Zenkin, Managing Director, e-mail: Evgeniy.Zenkin@rusal.com
A. A. Gavrilenko, Director for Environment, Labor Protection and Industrial Safety, e-mail: Aleksandr.Gavrilenko@rusal.com

RUSAL — Engineering and Technology Center Ltd., Krasnoyarsk, Russia:
S. I. Nozhko, Head of Electrolysis Department, Candidate of Technical Sciences, e-mail: Semen.Nozhko@rusal.com
L. V. Gavrilenko, manager of Electrolysis Department, Candidate of Technical Sciences, e-mail: Lyudmila.Gavrilenko@rusal.com

The quality of petroleum cokes used in the aluminum industry is rapidly deteriorating, with the main criterion being an increase in the content of sulfur and vanadium. An increase in the mass fraction of sulfur has a more significant effect on the process of electrolytic production of aluminum. Previous studies show that this leads to a decrease in the performance of electrolysers. Therefore, cumulative accumulation of sulfur in gas cleaning solutions should be avoided and, if possible, sulfur should be removed from the process. The technology of regeneration of gas-cleaning solutions of aluminum electrolyzers from sulfur compounds has been studied. The advantages of the developed technology in comparison with other existing ones are substantiated. A technological scheme for the regeneration of the gas-cleaning solution is given, the theoretical foundations of the process are given, and methods for a possible further intensification of this technology are described. At PJSC RUSAL Bratsk, the technology for removing sodium sulfate from gas cleaning solutions has been successfully tested and implemented on a semiindustrial scale. Atmospheric air was used as a cooler during the cold season. According to the analysis of the chemical composition of desulfurized gas cleaning solutions, this technology will reduce the load on the sludge fields, excluding the withdrawal of solutions to maintain the balance of sulfur products, and reduce the consumption of soda ash. The obtained sodium sulfate can be used in related industries, for example cellulose or synthetic detergents production.

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