A Study of Gold Recovery from E-Waste by Bioleaching Using Chromobacterium violaceum

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Chromobacterium violaceum is able to produce and detoxify small amounts of cyanide that has been used to recover gold from Electronic scrap materials (ESM). The particle size ≤75 μm fraction was used, containing 0.22% Au and 33.0% Cu. The bioleaching was carried out in 500 ml Erlenmeyer flask with 200 ml LB medium at 0.5% pulp density in pH 9 and shaking in an incubator shaker (200 rpm) at 30°C. The experiment featured two variables, copper removal with nitric acid and 2 leaching times, 1-step and 2-step bioleaching for enhanced cyanide production and gold dissolution. The maximum cyanide production was observed after 1 day before ESM adding. The results showed high efficiency of gold bioleaching from treated EMS containing 0.21% Au and 3.67% Cu. Dissolution of gold increased from 1.63% (0.13 mg/L) to 13.62% (1.43 mg/L) after 7 days in 2-step bioleaching. This study increased the efficiency of gold recovery by bioleaching significantly and can be recycled in an environmental friendly manner.

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280-283

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April 2014

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© 2014 Trans Tech Publications Ltd. All Rights Reserved

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