A Bioleaching Process for Sustainable Recycling of Complex Structures with Multi-Metal Layers

Eva Pakostova () and Anuradha Herath
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Eva Pakostova: Centre for Manufacturing and Materials, Institute for Clean Growth and Future Mobility, Coventry University, Coventry CV1 5FB, UK
Anuradha Herath: Centre for Manufacturing and Materials, Institute for Clean Growth and Future Mobility, Coventry University, Coventry CV1 5FB, UK

Sustainability, 2023, vol. 15, issue 19, 1-18

Abstract: Industrial waste is accumulating, while primary metal resources are depleting. Bioleaching has been shown to be a cost-effective and environmentally friendly approach to metal recovery from waste, but improved designs are needed for large-scale recycling. Metal components that are manufactured by electrodeposition over a mandrel can be difficult to recycle using conventional techniques due to their complex geometry and inner Ag coating. A sustainable biotechnology for separating Cu and Ag from waste electrodeposited components is presented. Two-step bioleaching experiments were performed, during which Cu was solubilized by Fe 3+ regenerated by Acidithiobacillus ( At. ) ferrooxidans CF3 and a consortium of ten acidophilic Fe 2+ -oxidizers. High Cu recovery rates were achieved in agitated flasks (22 °C, pH 1.9), with At. ferrooxidans solubilizing 94.7% Cu in 78 days and the consortium 99.2% Cu in 59 days. Copper bio-solubilization was significantly accelerated in a laboratory-scale bioreactor (32 °C, 1 L air min −1 ) using the bacterial consortium adapted to elevated Cu concentrations, reaching >99.6% Cu extraction in only 12 days. The bioreactor was dominated by Leptospirillum and Acidithiobacillus , with their proportions changing (from 83.2 to 59% of total reads and from 3.6 to 29.4%, respectively) during the leaching process. Dissolved Cu was recovered from the bioleachates (containing 14 to 22 g Cu L −1 ) using electrowinning; >99% of the Cu was deposited (with Cu purity of 98.5 to 99.9%) in 3.33 h (at current efficiency between 80 and 92%). The findings emphasize the importance of a bioleaching system design to achieve economical separation of base and precious metals from industrial wastes. The presented technology minimizes waste generation and energy consumption. On a larger scale, it has the potential to contribute to the development of industrial recycling processes that will protect natural resources and contribute to the Net Zero target.

Keywords: bioleaching; acidophiles; iron oxidation; copper electrowinning; metal recycling (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2023
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