Activated alumina for the removal of selenium oxyanions from heap leach detoxification solutions
The use of activated alumina for the removal of selenium from heap leach detoxification solutions was studied at a laboratory scale. Three aluminas were studied: one unmodified and two chemically modified to function better in a basic pH range. The best performer, Discovery Chemicals DD-6, readily accumulated selenium oxyanions. Furthermore, it could be stripped of selenium and several metals by a mild caustic solution (pH 11.5 to 12.0) and regenerated for further use. Tests using −600 +300-μm (28 x 48 mesh) material indicated that 96% could be removed from solution, and tests using −1.18-mm +600-μm (14 x 28 mesh) material indicated that 91 % could be removed. Flow rates were approximately 58 mL/min. The bed volumes were about 0.8 L. However, soluble silica can accumulate on the activated alumina and subsequently interfere with its regeneration. Therefore, it should be removed from the detox solution prior to use of the adsorbent.
Key wordsAlumina Selenium Detoxification solution Adsorption
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