Bioleaching of metals from wastes and low-grade sources by HCN-forming microorganisms

Faramarzi, Mohammad Ali; Mogharabi‐Manzari, Mehdi; Brandl, Helmut

doi:10.1016/j.hydromet.2019.105228

Cited by 46 publications

(16 citation statements)

References 143 publications

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“…This effect could be explained by different bacterial metabolisms when the conditions of their growth medium, such as pH, are altered and result in new products such as weak acid cyanide, ammonia, cyanate, etc. 35,36,38 Moreover, cyanide concentration was the highest in the middle range of pH values (pH 9 and 10 in controlled and no control cases, respectively). Considering that pK a for cyanide to hydrogen cyanide (HCN) transformation is 9.3 under standard conditions, 39 an observed lower amount of cyanide in the pH below 10 could be a result of HCN formation.…”

Section: ■ Materials and Methodsmentioning

confidence: 95%

“…These transformations are most likely to occur after about 2 days. 35,36 Generally, C. violaceum produces HCN between the end of the log phase and early stationary phase while Pseudomonas sees production at the start of the stationary phase. 37 Similarly, cyanide production by bacteria B. megaterium happens within the first 2 days after inoculation and depending on the medium condition, concentration of bio-CN can peak at any time during this period.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

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A Green and Sustainable Process for the Recovery of Gold from Low-Grade Sources Using Biogenic Cyanide Generated by Bacillus megaterium: A Comprehensive Study

Faraji

Wang

Mahandra

et al. 2020

ACS Sustainable Chem. Eng.

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The decreasing grade of gold deposits and environmental regulations concerning the use of cyanide, a conventional extraction agent used in gold recovery, has highlighted the challenge in the field of gold extraction. The bioleaching of gold using microorganisms for in situ cyanide production to recover gold is a promising new approach for prohibiting the use of conventional chemical cyanide. For the first time, this study reports a comprehensive investigation on the role of pH on individual steps of Bacillus megaterium bacterial growth, cyanide production, and gold recovery. This novel way of maximizing biogenic cyanide is highly efficient and demonstrates biocyanidation as a potentially viable technique for direct treatment of sulfidic gold ores, i.e., eliminating the step of biooxidation for the first time. The low-grade sources were treated with both chemical cyanide and biogenic cyanide generated by B. megaterium. Results indicate that the bacteria generated a maximum of 61.89 ppm cyanide, which correspondingly recovered over 87% and 43% gold from O1 and O2 sources, respectively, comparable to gold recoveries by chemical leaching. The pure gold powder leaching was also performed to evaluate the loss in gold recovery due to the biosorption of gold to bacterial cells. The feasibility of the work is also supported by green chemistry metrics, and a comparison has been made between conventional and biocyanide leaching. The results revealed the potential of biocyanidation for industrial applications.

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Section: ■ Materials and Methodsmentioning

confidence: 95%

Section: ■ Materials and Methodsmentioning

confidence: 99%

A Green and Sustainable Process for the Recovery of Gold from Low-Grade Sources Using Biogenic Cyanide Generated by Bacillus megaterium: A Comprehensive Study

Faraji

Wang

Mahandra

et al. 2020

ACS Sustainable Chem. Eng.

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“…Many studies have investigated the bioleaching of different ores and industrial wastes [24][25][26]; only a few, however, involve the bioleaching of BR, especially for REE extraction [18,22,27]. Fungal strains such as Penicillium tricolor [18,27] and Aspergillus niger [27][28][29] and microalgae [30] such as Desmodesmus quadricauda, Chlamydomonas reinhardtii, and Parachlorella kessleri have been investigated.…”

Section: Introductionmentioning

confidence: 99%

Study of Microbial Cultures for the Bioleaching of Scandium from Alumina Industry By-Products

Kiskira

Lymperopoulou

Tsakanika

et al. 2021

Metals

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The disposal of voluminous, highly alkaline, bauxite residue (BR), the industrial by-product of alumina production by the Bayer process, constitutes an intricate global environmental problem. BR, containing valuable metals such as rare-earth elements (REEs)—in particular, scandium (Sc)—can be used as a secondary source for REE extraction. The scope of this study was the investigation of bioleaching as an innovative and environmentally friendly approach for the extraction of Sc from BR. The bioleaching parameters were studied on Greek BR and experiments were performed using different microbial cultures and solid to liquid ratios (S/L). The maximum extraction of Sc was 42% using Acetobacter tropicalis in a one-step bioleaching process at 1% S/L. The main organic acids produced were acetic, oxalic, and citric. The bioleaching data indicated a probable synergistic effect of the different organic acids produced by microorganisms along with a more targeted leaching mechanism.

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“…It is the extraction or mobilization of valuable (target) metal from the ore, can also be defined as a process of recovering metals from low grade ore [2,3], with regard to solubility, bioleaching can be defined as a process of recovering soluble one from insoluble impurities after dissolving sulfide metal as soluble salt in a solution [4] that results toxics and heavy metals removed. It is isolation of metals from their ores, concentrates and mineral wastes under the influence of microorganisms leading to dissolution of metal solutions of leach liquor containing metals [5], followed by solvent extraction, stripping, ion exchange, electro wining to get pure metal.…”

Section: Introductionmentioning

confidence: 99%

Bio Hydrometallurgical Technology, Application and Process Enhancement

Cheru¹

2021

Heavy Metals - Their Environmental Impacts and Mitigation

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The review is in general try to see some of the major microorganism involved in bioleaching process and studied by different scholars, identify the mechanics and techniques employed to bioleach minerals and factor that enhance or to inhibit the leaching process of microorganism with major reaction taking while bioleaching. Here the methodology and different leaching technique presented with their respected pros and cons, which are commonly employed and reasons behind with justifiable evidences were presented. The values and bioleaching sulfide mineral (copper), precious metal (gold) and radioactive element (uranium) were discussed with some the known producers in the world and finally some highlight given on industrial application of bioleaching.

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Bioleaching of metals from wastes and low-grade sources by HCN-forming microorganisms

Cited by 46 publications

References 143 publications

A Green and Sustainable Process for the Recovery of Gold from Low-Grade Sources Using Biogenic Cyanide Generated by Bacillus megaterium: A Comprehensive Study

A Green and Sustainable Process for the Recovery of Gold from Low-Grade Sources Using Biogenic Cyanide Generated by Bacillus megaterium: A Comprehensive Study

Study of Microbial Cultures for the Bioleaching of Scandium from Alumina Industry By-Products

Bio Hydrometallurgical Technology, Application and Process Enhancement

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