Chemo-biohydrometallurgy—A hybrid technology to recover metals from obsolete mobile SIM cards

• SIM waste (SIMW) like Computer Printed Circuit Boards (CPCB) is a source of precious metals.
• Chemo-biohydrometallurgy promotes recovery of Cu and other metals from SIMW.
• Bioleaching coupled with acidic pretreatment yielded high recovery of Cu from SIMW.
• SIMW have potential to be used in recycling industry and can lower burden on natural resources which needs serious consideration.
• Higher Cu percentage of SIMW is a hindrance in recovery of other metals like Au.

The exponential increase in the cellular networking and advancement in the related technology has led to an increase in obsolete SIM cards. Elemental composition of obsolete SIM waste (SIMW) of particle size 355–700 μm was 75.84% Cu, 0.42% Au, and 0.01% Ag. SIMW can be used to extract valuable metals. A chemo-biohydrometallurgy approach was employed for metals recovery from SIMW. Bioleaching experiments were performed in 150 ml Erlenmeyer flasks with 50 ml of Luria broth medium at pH 9, glycine concentration 5 g/L, rpm 150, temperature 30° C and pulp density 10 g/L. Two step bioleaching of untreated SIMW using Chromobacterium violaceum yielded poor metals mobilization of copper (13.79%), gold (0.44%) and silver (2.55%). Acidic pretreatment of SIMW recovered 72% of copper, as its high concentration cause hindrance for leaching and solubilization of other metals like Au, and Ag. Subsequent, two-step bioleaching of pretreated SIMW at alkaline pH using Chromobacterium violaceum solubilized 70.61% of the remaining Cu within 4 days of incubation period. Therefore, a hybrid technology can be applied to efficiently recover Cu and other metals from SIMW. To the best of authors’ knowledge, this is the first report of using hybrid technology to leach out Cu and other metals from SIMW.

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