scholarly journals Bioleaching of Transition Metals From Limonitic Laterite Deposits and Reassessment of the Multiple Roles of Sulfur-Oxidizing Acidophiles in the Process

2021 ◽  
Vol 12 ◽  
Author(s):  
D. Barrie Johnson ◽  
Sarah L. Smith ◽  
Ana Laura Santos
Keyword(s):  
Iron Reduction ◽  
Mineral Dissolution ◽  
Multiple Roles ◽  
Reductive Dissolution ◽  
Acidithiobacillus Thiooxidans ◽  
Redox Potentials ◽  
Waste Products ◽  
Acidophilic Bacteria ◽  
Oxidized Iron ◽  
Pure Cultures

Using acidophilic bacteria to catalyze the reductive dissolution of oxidized minerals is an innovative process that facilitates the extraction of valuable base metals (principally cobalt and nickel) from limonites, which are otherwise often regarded as waste products of laterite mining. The most appropriate conditions required to optimize reductive mineral dissolution are unresolved, and the current work has reassessed the roles of Acidithiobacillus spp. in this process and identified novel facets. Aerobic bio-oxidation of zero-valent sulfur (ZVS) can generate sufficient acidity to counterbalance that consumed by the dissolution of oxidized iron and manganese minerals but precludes the development of low redox potentials that accelerate the reductive process, and although anaerobic oxidation of sulfur by iron-reducing species can achieve this, less acid is generated. Limited reduction of soluble iron (III) occurs in pure cultures of Acidithiobacillus spp. (Acidithiobacillus thiooxidans and Acidithiobacillus caldus) that do not grow by iron respiration. This phenomenon (“latent iron reduction”) was observed in aerated cultures and bioreactors and was independent of electron donor used (ZVS or hydrogen). Sufficient ferrous iron was generated in the presence of sterilized hydrophilic sulfur (bio-ZVS) to promote the effective reductive dissolution of Mn (IV) minerals in limonite and the solubilization of cobalt in the absence of viable acidophiles.

Leaching of Pyrite by Acidophilic Heterotrophic Iron-Oxidizing Bacteria in Pure and Mixed Cultures

1999 ◽  
Vol 65 (2) ◽  
pp. 585-590 ◽  
Author(s):  
Paula Bacelar-Nicolau ◽  
D. Barrie Johnson
Keyword(s):  
Yeast Extract ◽  
Thiobacillus Ferrooxidans ◽  
Pyrite Oxidation ◽  
Mixed Cultures ◽  
Mineral Dissolution ◽  
Acidophilic Bacteria ◽  
Pure Cultures ◽  
Sulfur Oxidizing ◽  
Thiobacillus Acidophilus ◽  
Basal Salts

ABSTRACT Seven strains of heterotrophic iron-oxidizing acidophilic bacteria were examined to determine their abilities to promote oxidative dissolution of pyrite (FeS2) when they were grown in pure cultures and in mixed cultures with sulfur-oxidizingThiobacillus spp. Only one of the isolates (strain T-24) oxidized pyrite when it was grown in pyrite-basal salts medium. However, when pyrite-containing cultures were supplemented with 0.02% (wt/vol) yeast extract, most of the isolates oxidized pyrite, and one (strain T-24) promoted rates of mineral dissolution similar to the rates observed with the iron-oxidizing autotroph Thiobacillus ferrooxidans. Pyrite oxidation by another isolate (strain T-21) occurred in cultures containing between 0.005 and 0.05% (wt/vol) yeast extract but was completely inhibited in cultures containing 0.5% yeast extract. Ferrous iron was also needed for mineral dissolution by the iron-oxidizing heterotrophs, indicating that these organisms oxidize pyrite via the “indirect” mechanism. Mixed cultures of three isolates (strains T-21, T-23, and T-24) and the sulfur-oxidizing autotroph Thiobacillus thiooxidans promoted pyrite dissolution; since neither strains T-21 and T-23 nor T. thiooxidans could oxidize this mineral in yeast extract-free media, this was a novel example of bacterial synergism. Mixed cultures of strains T-21 and T-23 and the sulfur-oxidizing mixotrophThiobacillus acidophilus also oxidized pyrite but to a lesser extent than did mixed cultures containing T. thiooxidans. Pyrite leaching by strain T-23 grown in an organic compound-rich medium and incubated either shaken or unshaken was also assessed. The potential environmental significance of iron-oxidizing heterotrophs in accelerating pyrite oxidation is discussed.

Interactions of the extremely acidophilic archaeon Ferroplasma acidiphilum with acidophilic bacteria during pyrite bioleaching

2016 ◽  
Vol 1 (2) ◽  
pp. 43 ◽  
Author(s):  
Nova Maulani ◽  
Qian Li ◽  
Wolfgang Sand ◽  
Mario Vera ◽  
Ruiyong Zhang
Keyword(s):  
High Performance ◽  
Single Species ◽  
Microbial Interactions ◽  
Mineral Dissolution ◽  
Physical Contact ◽  
Low Grade ◽  
Adhesion Forces ◽  
Initial Attachment ◽  
Acidophilic Bacteria ◽  
Pure Cultures

Bioleaching has been applied as a successful technique for metal recovery from various mineral sources like low-grade ores, waste materials and tailings. Mixed cultures of bioleaching microorganisms have a high performance in mineral dissolution. Thus far, microbial interactions in bioleaching communities are poorly understood. In this paper, the acidophilic archaeon Ferroplasma acidiphilum and the bacteria Leptospirillum ferriphilum and Sulfobacillus thermosulfidooxidans were chosen to study their interactions during pyrite leaching. The initial attachment to pyrite and pyrite leaching efficiency of pure and mixed populations were investigated. The data indicate: (i) attachment and bioleaching efficiency of L. ferriphilum was reduced in the presence of F. acidiphilum. However, the combination of F. acidiphilum and S. thermosulfidooxidans showed increased leaching, although the initial attachment rate was reduced, when compared to pure cultures. Thus, synergistic or antagonistic interactions may exist between F. acidiphilum and S. thermosulfidooxidans or F. acidiphilum and L. ferriphilum, respectively; (ii) pre-established biofilms of L. ferriphilum inhibited initial attachment to pyrite by cells of F. acidiphilum and did not promote pyrite leaching by F. acidiphilum. In contrast, inactivated biofilm cells of S. thermosulfidooxidans enhanced pyrite bioleaching by F. acidiphilum; (iii) adhesion forces of cells to an AFM tip (Si3N4) seemed to be not correlated to attachment and bioleaching capacity; and (iv) lectins were applied to show and distinguish single species in mixed biofilm populations. Physical contact between cells of S. thermosulfidooxidans and F. acidiphilum was visible. 

Laboratory-Based Bacterial Weathering of the Merensky Reef and Its Impact on Platinum Group Mineral Migration

2021 ◽  
Author(s):  
Ling Tan ◽  
Thomas Jones ◽  
Jianping Xie ◽  
Xinxing Liu ◽  
Gordon Southam
Keyword(s):  
Base Metal ◽  
Mineral Dissolution ◽  
Metal Sulfides ◽  
Acidithiobacillus Thiooxidans ◽  
Thin Sections ◽  
Secondary Minerals ◽  
Merensky Reef ◽  
Fe Oxides ◽  
Base Metal Sulfides ◽  
Platinum Group

Abstract Weathering of the Merensky reef was enhanced under laboratory conditions by Fe- and S-oxidizing bacteria: Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptospirillum ferrooxidans. These bacteria preferentially colonized pyrrhotite and pyrite, versus pentlandite and chalcopyrite (all of which were common within the rock substrate), promoting weathering. Weathering of base metal sulfides resulted in the precipitation of Fe oxides, Fe phosphate, and elemental sulfur as secondary minerals. Fe pyroxene weathered readily under acidic conditions and resulted in mineral dissolution, while other silicates (orthopyroxene and plagio-clase) precipitated Fe phosphate spherules or coatings on their surface. The deterioration of the platinum group metal (PGM) matrix (base metal sulfides and silicates) and the occurrence of a platinum grain associated with platinum nanoparticles observed in the biotic thin sections demonstrate that biogeochemical acid weathering is an important step in the active release of intact PGM grains. A platinum grain embedded in secondary Fe oxides/phosphate that had settled by gravity within the weathering solution demonstrates that secondary minerals that formed during weathering of PGM-hosting minerals also represent targets in PGM exploration by trapping and potentially slowing PGM migration. Dispersion halos surrounding or occurring downstream from PGM occurrences will likely produce two physical target classes—i.e., grains and colloids—under surficial weathering conditions.

Latent disciplinal clashes concerning the batch dissolution of minerals, and their wider implications

2018 ◽  
Vol 15 (2) ◽  
pp. 113 ◽  
Author(s):  
Victor W. Truesdale ◽  
Jim Greenwood
Keyword(s):  
Large Scale ◽  
Dissolution Kinetics ◽  
Mineral Dissolution ◽  
Atomic Scale ◽  
Rate Equations ◽  
Silicate Mineral ◽  
Waste Products ◽  
Calcite Dissolution ◽  
Macro Scale ◽  
Made In

Environmental contextMineral dissolution kinetics are important to understand natural processes including those increasingly used to store waste carbon dioxide and highly radio-active nuclides, and those involved in the amelioration of climate change and sea-level rise. We highlight a mistake made in the fundamental science that has retarded progress in the field for over 40 years. Its removal suggests improved ways to approach dissolution studies. AbstractMineral dissolution kinetics are fundamental to biogeochemistry, and to the application of science to reduce the deleterious effects of humanity’s waste products, e.g. CO2 and radio-nuclides. However, a mistake made in the selection of the rate equation appropriate for use at the macro-scale of the aquatic environment has stymied growth in major aspects of the subject for some 40 years. This paper identifies the mistake, shows how it represents a latent disciplinal clash between two rate equations, and explores the misunderstandings that resulted from it. The paper also briefly explores other disciplinal clashes. Using the example of calcite dissolution, the paper also shows how the phenomenon of ‘non-ideal’ dissolution, which is prevalent in alumino-silicate mineral dissolution, as well as with calcite, has obscured the clash. The paper provides new information on plausible mechanisms, the absence of which has contributed to the problem. Finally, it argues that disciplinal clashes need to be minimised so that a rigorous description of dissolution at the large scale can be matched to findings at the atomic, or near-atomic, scale.

Reductive Dissolution of a Lateritic Ore Containing Rare Earth Elements (REE) Using Acidithiobacillus Species

2017 ◽  
Vol 262 ◽  
pp. 299-302
Author(s):  
Ivan Nancucheo ◽  
D. Barrie Johnson ◽  
Manoel Lopes ◽  
Guilherme Oliveira
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Mineral Dissolution ◽  
The Other ◽  
Reductive Dissolution ◽  
Valuable Metals ◽  
Lateritic Ore

Lateritic deposits containing rare earth elements (REE) are important resources in Brazil, where monazite is the main REE-bearing mineral and is frequently associated with iron hydroxy-oxides and quartz. In order to recover valuable metals such as REE and uranium, experiments were carried out under reductive mineral dissolution using Acidithiobacillus species. In terms of phosphate, aerobic reductive dissolution at pH 0.9 using A. thiooxidans extracted about 35% of that present in the ore which is and indicator of the dissolution of monazite. Although only ~9% of the cerium and 5% of the lanthanum were extracted, ~72% of the uranium was solubilized, indicating that it was more susceptible to extraction by reductive dissolution than the other two REE.

scholarly journals Use of Bacteria To Stabilize Archaeological Iron

2017 ◽  
Vol 83 (9) ◽  
Author(s):  
Lucrezia Comensoli ◽  
Julien Maillard ◽  
Monica Albini ◽  
Frederic Sandoz ◽  
Pilar Junier ◽  
...  
Keyword(s):  
Iron Age ◽  
Iron Reduction ◽  
Physical Stability ◽  
Corrosion Layer ◽  
Homogeneous Layer ◽  
Waste Products ◽  
Promising Alternative ◽  
Content Type ◽  
Archaeological Iron ◽  
Archaeological Objects

ABSTRACT Iron artifacts are common among the findings of archaeological excavations. The corrosion layer formed on these objects requires stabilization after their recovery, without which the destruction of the item due to physicochemical damage is likely. Current technologies for stabilizing the corrosion layer are lengthy and generate hazardous waste products. Therefore, there is a pressing need for an alternative method for stabilizing the corrosion layer on iron objects. The aim of this study was to evaluate an alternative conservation-restoration method using bacteria. For this, anaerobic iron reduction leading to the formation of stable iron minerals in the presence of chlorine was investigated for two strains of Desulfitobacterium hafniense (strains TCE1 and LBE). Iron reduction was observed for soluble Fe(III) phases as well as for akaganeite, the most troublesome iron compound in the corrosion layer of archaeological iron objects. In terms of biogenic mineral production, differential efficiencies were observed in assays performed on corroded iron coupons. Strain TCE1 produced a homogeneous layer of vivianite covering 80% of the corroded surface, while on the coupons treated with strain LBE, only 10% of the surface was covered by the same mineral. Finally, an attempt to reduce iron on archaeological objects was performed with strain TCE1, which led to the formation of both biogenic vivianite and magnetite on the surface of the artifacts. These results demonstrate the potential of this biological treatment for stabilizing archaeological iron as a promising alternative to traditional conservation-restoration methods. IMPORTANCE Since the Iron Age, iron has been a fundamental material for the building of objects used in everyday life. However, due to its reactivity, iron can be easily corroded, and the physical stability of the object built is at risk. This is particularly true for archaeological objects on which a potentially unstable corrosion layer is formed during the time the object is buried. After excavation, changes in environmental conditions (e.g., higher oxygen concentration or lower humidity) alter the stability of the corrosion layer and can lead to the total destruction of the object. In this study, we demonstrate the feasibility of an innovative treatment based on bacterial iron reduction and biogenic mineral formation to stabilize the corrosion layer and protect these objects.

Reductive Leaching of Jarosites by Shewanella putrefaciens - Influence of Humic Substances and Chelators in Mineral Dissolution

2015 ◽  
Vol 1130 ◽  
pp. 450-453 ◽  
Author(s):  
Laura Castro ◽  
J.A. Muñoz ◽  
F. González ◽  
M. Luisa Blázquez ◽  
Antonio Ballester
Keyword(s):  
Humic Substances ◽  
Biofilm Formation ◽  
Iron Reduction ◽  
Cell Attachment ◽  
Reduction Rate ◽  
Shewanella Putrefaciens ◽  
Microbial Reduction ◽  
Mineral Dissolution ◽  
Electron Shuttling ◽  
Reductive Leaching

The anaerobic bioreduction of three Fe (III) ores by a type strain of Shewanella putrefaciens has been investigated. The release of ferrous ion indicated the microbial reduction of jarosite and promotes the subsequent secondary mineralization, leading to the formation of various iron-nearing minerals. In addition, the influence of citrate and EDTA in the medium acting as chelating agents, and an electron shuttling molecule were studied. While the citrate and humic substances increased the iron reduction rate, AQDS inhibit the mineral bioreduction and dissolution. S. putrefaciens do not have the necessity of the direct contact between cells and jarosites and, in consequence, cell attachment and biofilm formation on the mineral surface is scant.

scholarly journals Effects of Conventional Flotation Frothers on the Population of Mesophilic Microorganisms in Different Cultures

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 653 ◽  
Author(s):  
Mohammad Jafari ◽  
Mehdi Golzadeh ◽  
Sied Shafaei ◽  
Hadi Abdollahi ◽  
Mahdi Gharabaghi ◽  
...  
Keyword(s):  
Mixed Culture ◽  
Acidithiobacillus Ferrooxidans ◽  
Lower Sensitivity ◽  
Acidithiobacillus Thiooxidans ◽  
Methyl Isobutyl ◽  
Flotation Process ◽  
Leptospirillum Ferrooxidans ◽  
Pine Oil ◽  
Pure Cultures ◽  
Extraction Of Metals

Bioleaching is an environment-friendly and low-investment process for the extraction of metals from flotation concentrate. Surfactants such as collectors and frothers are widely used in the flotation process. These chemical reagents may have inhibitory effects on the activity of microorganisms through a bioleaching process; however, there is no report indicating influences of reagents on the activity of microorganisms in the mixed culture which is mostly used in the industry. In this investigation, influences of typical flotation frothers (methyl isobutyl carbinol and pine oil) in different concentrations (0.01, 0.10, and 1.00 g/L) were examined on activates of bacteria in the mesophilic mixed culture (Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans, and Acidithiobacillus thiooxidans). For comparison purposes, experiments were repeated by pure cultures of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans in the same conditions. Results indicated that increasing the dosage of frothers has a negative correlation with bacteria activities while the mixed culture showed a lower sensitivity to the toxicity of these frothers in comparison with examined pure cultures. Outcomes showed the toxicity of Pine oil is lower than methyl isobutyl carbinol (MIBC). These results can be used for designing flotation separation procedures and to produce cleaner products for bio extraction of metals.

scholarly journals Bioreductive Dissolution as a Pretreatment for Recalcitrant Rare-Earth Phosphate Minerals Associated with Lateritic Ores

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 136 ◽  
Author(s):  
Ivan Nancucheo ◽  
Guilherme Oliveira ◽  
Manoel Lopes ◽  
David Johnson
Keyword(s):  
Rare Earth ◽  
Elemental Sulfur ◽  
Ferric Iron ◽  
Mineral Dissolution ◽  
Base Metals ◽  
Iron Minerals ◽  
Acidophilic Bacteria ◽  
Biotechnological Approach ◽  
Potential Resource ◽  
Rare Earth Phosphate

Recent research has demonstrated the applicability of a biotechnological approach for extracting base metals using acidophilic bacteria that catalyze the reductive dissolution of ferric iron oxides from oxidized ores, using elemental sulfur as an electron donor. In Brazil, lateritic deposits are frequently associated with phosphate minerals such as monazite, which is one of the most abundant rare-earth phosphate minerals. Given the fact that monazite is highly refractory, rare earth elements (REE) extraction is very difficult to achieve and conventionally involves digesting with concentrated sodium hydroxide and/or sulfuric acid at high temperatures; therefore, it has not been considered as a potential resource. This study aimed to determine the effect of the bioreductive dissolution of ferric iron minerals associated with monazite using Acidithiobacillus (A.) species in pH- and temperature-controlled stirred reactors. Under aerobic conditions, using A. thiooxidans at extremely low pH greatly enhanced the solubilization of iron from ferric iron minerals, as well that of phosphate (about 35%), which can be used as an indicator of the dissolution of monazite. The results from this study have demonstrated the potential of using bioreductive mineral dissolution, which can be applied as pretreatment to remove coverings of ferric iron minerals in a process analogous to the bio-oxidation of refractory golds and expand the range of minerals that could be processed using this approach.

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