Document Type : Original Research Paper
Authors
- Amirmohammad Nasrollahzadeh bafti 1
- Laya Shakib Mehr 2
- Esmaeel dareh zereshki 3
- Mohsen Akhoundi parizi 4
- Hossein pour Shahnazari 5
1 Master of Science in Mining Engineering, Mineral Processing, Sarcheshmeh Copper Complex, Kerman, Iran
2 Faculty of Materials and Metallurgical Engineering, Shiraz University, Shiraz, Iran.
3 Faculty of Materials and Metallurgical Engineering, Bahonar University of Kerman, Kerman, Iran.
4 Head of Operations, Slag Copper Flotation Plant, Sarcheshmeh Copper Complex, Kerman, Iran
5 Head of Metallurgy, Slag Copper Flotation Plant, Sarcheshmeh Copper Complex, Kerman,
Abstract
Copper smelting slag (CSS) represents a significant secondary resource containing valuable metals such as copper and molybdenum. However, its complex mineralogy and the glassy nature of the slag limit the efficiency of conventional flotation processes and require high reagent consumption. In this study, a native halophilic bacterium, Halomonas lutescens, was investigated as an eco-friendly bio-reagent to improve the flotation performance of CSS. Laboratory-scale experiments were conducted under controlled conditions to determine the optimal bacterial dosage, evaluate reusability, and analyze kinetic behavior. The results demonstrated that adding 40 mL of bacterial suspension (conditioned for 5 min) significantly enhanced copper and molybdenum recoveries compared to chemical flotation. Based on previous research on the adhesion of halophilic bacteria, supportive FTIR, SEM–EDS, and adhesion schematic analyses indicate that hydroxyl, carboxyl, and amine groups in bacterial EPS can coordinate with Cu²⁺/Fe³⁺ surface sites, thereby enhancing mineral hydrophobicity and improving Cu–Mo recoveries. Total copper recovery increased from 58.98% to 71.11%, and molybdenum recovery rose markedly from 4.50% to 28.51%, while maintaining similar concentrate grades. Kinetic modeling revealed higher rate constants and better fitting with bacterial presence, confirming enhanced flotation kinetics. Moreover, bacteria remained viable and reusable over multiple flotation cycles, indicating strong potential for process sustainability. Overall, H. lutescens acts as a bio-frother and collector aid, enabling more efficient and environmentally friendly flotation of copper smelting slag.
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