Mineral Processing
Amirmohammad Nasrollahzadeh bafti; Laya Shakib Mehr; Esmaeel Darezereshki; Mohsen Akhoundi parizi; Hossein pour Shahnazari
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, ...
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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.
Mineral Processing
Mohammadreza Shahbazi; Hadi Abdollahi; Sied Ziaeddin Shafaei; Ziaeddin Pourkarimi; Sajjad Jannesar Malakooti; Ehsan Ebrahimi
Abstract
Tabas coal possesses favorable plastometric properties that make it suitable for use in metallurgical industries as coking coal. However, its high sulfur content, which stands at approximately 2%, poses a significant environmental pollution risk. Additionally, reducing ash content to below 10% is a critical ...
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Tabas coal possesses favorable plastometric properties that make it suitable for use in metallurgical industries as coking coal. However, its high sulfur content, which stands at approximately 2%, poses a significant environmental pollution risk. Additionally, reducing ash content to below 10% is a critical objective of this study to prevent a decline in coal's thermal efficiency in the metallurgical industries. This research work investigates the removal of sulfur and ash from Tabas coal samples using the biological methods including bioflotation and bioleaching. Initially, a combination of mesophilic bacteria including Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptosprillium ferrooxidans were employed in the bioflotation method to detain pyrite sulfur in the Tabas coal samples. The highest reduction percentages of pyrite sulfur and ash were equal to 62% and 54.18%, respectively. In the next stage, bioleaching experiments were conducted, the effect of the test time, percentage of bacteria by volume, percentage of coal solids, and absence of bacteria on the amount of sulfur and ash removal was investigated. The test time emerged as the most critical factor. The best sulfur removal was achieved using bioleaching, with a maximum removal of 72.43%, observed for the PE coal sample. Bioflotation also achieved significant sulfur removal, with a maximum removal of 61% observed for the same sample. On the other hand, the best ash removal was achieved using bioflotation, with a maximum removal of 68.98% observed for the PE coal sample, and a maximum removal of 69.34% observed for the B4B2 coal sample using bioleaching. Finally, this research work conducted a comparison of biological methods to determine the amount of sulfur and ash reduction achieved. The results showed that both bioleaching and bioflotation were effective for coal desulfurization and ash removal, with bioleaching performing slightly better for sulfur removal and bioflotation performing slightly better for ash removal.
