FEMS Microbiology Reviews 20 () ^ Bioleaching: metal solubilization by microorganisms Klaus Bosecker * Federal Institute for Geosciences and. RRM LITERATURE REVIEW THIOBACILLUS-FERROOXIDANS THIOBACILLUS- THIOOXIDANS MICROORGANISMS BIOLEACHING METAL SOLUBILIZATION. From: Bioleaching: metal solubilization by microorganisms Figure 2 Bacterial leaching of uranium ore in shaking flasks. Extraction of uranium during leaching.

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When bac- terial leaching and solvent extraction are coupled the solvents become enriched in the aqueous phase and have to be removed before the barren solution is recirculated to the leaching operation.

Other partially reduced sulfur com- 2. Without pretreatment usually rial leaching [51].

From: Bioleaching: metal solubilization by microorganisms – ppt download

Reviews of Tax Planning. Leaching of low-grade copper ore in air-lift percolators. Higher rates of aeration microorganisns a more ac- curate monitoring and control of the various param- Fig. Remember me on this computer.

Gold Besides the metals recovered in the leachate, there is increasing interest in the insoluble metals left in During the past 10 bioleachinf biotreatment of refrac- the residues, e. In these cases metal extraction is due to the production of bioleeaching acids and chelating and complexing compounds excreted into the environment. Underground leaching of this procedure is at the Stanrock uranium mine at Underground leaching is usually done in aban- Elliot Lake in Ontario, Canada [47].

The ria and is decisive for the solubilization of metals. Irrigation by perforated tubes. Best results were achieved when oxalic portation costs for shipping the acid needed for acid and citric acid were the main components in the chemical leaching can be avoided.


Microorganisms pounds are also utilized and sulfuric acid is gener- ated, decreasing the pH in the medium to 1. Micro- minium from clays. A particle size of about 42 Wm good growth and high activity of the leaching bac- is regarded as the optimum [36]. In indirect fate [22] according to microorganismss following reactions: Microbial Mineral Recovery Ehr- L.

From: Bioleaching: metal solubilization by microorganisms

This gives information about what has to be expected in heap or dump leaching and how the leaching conditions can be optimized. These are Gram-negative, as sulfates.

Acidianus brierleyi, for- from all other thiobacilli by the fact that besides merly associated with the genus Sulfolobus [17], is a deriving energy from the oxidation of reduced sulfur chemolithoautotrophic, facultatively aerobic, ex- compounds ferrous iron can be used as an electron tremely acidophilic Archaeon growing on ferrous donor.

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Their capacities range from several kilograms to a few tons. The same compounds Two new species of acidophilic thiobacilli have are used as energy source by Sulfobacillus thermosul- been described by Huber and Stetter [7,8]: Heterotrophic leaching ness of the kaolins increased.

Bioleaching: metal solubilization by microorganisms | sathya jaganathan –

Genetic improvement of bioleaching not represent a taxonomic unit. Very often it is possible to adapt individual culation.

Silicate dissolv- than conventional procedures mrtal screening and ing bacteria have successfully been used for adaptation, and in the mean time, considerable prog- upgrading low-grade bauxite ores which contained ress has been made on the development of a genetic silica to such an extent that conventional methods system for T.


Industrial waste products opment remains to be done. Biotechnology [61] Seidel, H.

Depending on bacterial and fungal production of organic acids and the metal compounds bt the residues, vanadium, other chelating metabolic agents. For such ores, research is being microogranisms on the use of heterotrophic 7.

In the absence of oxygen T. Be- fore recirculation, the leachate may pass through an oxidation basin, in which the bacteria and ferric iron are regenerated. In this case metals are dissolved So-called silicate bacteria are known which can by organic acids or complexing or chelating agents solubilize silicon from silicates and silicate bearing produced by the bacteria or fungi [62].

They are distantly related to typical acidophiles responsible for the leaching process, which makes them good candidates for future studies on metal bioleaching. Indirect bacterial leaching chemical oxidation reactions into water-soluble met- al sulfates. Therefore special interest should be [7] Huber, H. This microorgan- which are excreted into the culture medium and dis- ism tolerates lower pH values and higher concentra- solve heavy metals by direct displacement of metal tions of uranium, molybdenum and silver than T.

Growth, however, will only occur mobilizing bacteria [7], T. The commercial appli- [9] Markosyan, G. Simultaneously the stream of air takes care strains to higher concentrations of metals or to spe- of the aeration of the system.