Sulfur Removal By Adding Hydrogen Peroxide In the Bayer Liquid

Abstract

The presence of sulfur in sodium aluminate solution has a lot of harm to the Bayer process of alumina production. H 2 O 2    is used as oxidant to removal low valence sulfur (S 2- ) into high valence sulfur (S 2 O 3 2- 、SO 3 2- 、SO 4 2- ). this paper studies the reaction mechanism of hydrogen peroxide and different valences sulfur in sodium aluminate solution by combining the thermodynamic calculation and experiment. Through thermodynamic analysis, it is deduced that hydrogen peroxide can undergo oxidation reaction with different valence sulfur (S 2- 、S 2 O 3 2- 、SO 3 2- ) in sodium aluminate solution, and the oxidation effect of S 2-    is the most obvious. By studying the oxidation effect of hydrogen peroxide dosage, oxidation time, and oxidation temperature on different valence sulfur in sodium aluminate solution, it is found that the removal rate of S 2-    reaches 91.85% under the conditions of 9% hydrogen peroxide dosage, 260℃ oxidation temperature, and 60 min oxidation time. The experimental results are consistent with the thermodynamic calculation results. Finally, the reaction mechanism of hydrogen peroxide with different valences sulfur in sodium aluminate solution is described in detail, which provides theoretical support for the desulfurization of high-sulfur bauxite in the production of alumina by Bayer process.

Keywords: High sulfur bauxite, hydrogen peroxide, desulfurization, sodium aluminate solution, digestion