Technology for Removal of Sulphur Compounds from Gases Generated during Aluminum Production

Abstract

RUSAL has been upgrading its aluminium smelters by replacing the scrubbing of the cell off-gases with the “state of the art” alumina dry scrubbers followed by preexisting wet scrubber technology to satisfy today’s environmental regulations for fluoride and sulfur emissions. Today, sixty percent of RUSAL’s smelters are converted to an alumina dry scrubber followed by a wet scrubber and the others are still using a wet-process that captures the fluorides and sulphur emissions with a liquor of soda.

While the wet scrubber technology meets recovery efficiency in accord with environmental regulations for the recovery of sulfur compounds for all smelters and it recovers fluorides, the sulfur compounds, mainly as sulfates, end up in costly and monitored landfills.

This paper covers RUSAL’s development of a technology for producing a commercial grade sodium sulfate slurry, decreasing salt concentrations, delaying the constructing of landfills, and reducing the environmental impact of wet scrubber technology.