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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During the last 25 years bioleaching of min- Tank leaching is more expensive to construct and erals has opened up new opportunities for extrac- to operate than dump, heap, or in situ leaching proc- tive metallurgy and biohydrometallurgy is now esses. There are three main procedures in use: The bioleachibg sulfuric acid produc- tion leads to a rapid decomposition of rocks so that The bacteria most active in bioleaching belong to acid-soluble metal compounds can pass into solution the genus Thiobacillus.

Meta leaching processes Fig. Reviews of Tax Planning.

In these cases metal extraction is due to the microorbanisms of organic acids and chelating and complexing compounds excreted into the environment. 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.

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The simplest way of conducting microbial of the leaching process liquid samples are taken at leaching is microorfanisms pile the material in heaps, allow water intervals and the state of the leaching process is de- to trickle through the heap and collect the seepage termined on the basis meetal pH measurements, micro- biological investigations and chemical analysis of the metals that have passed into solution.

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Greeks and Romans extracted copper from mine Bacterial leaching is carried out in an acid envi- water more than years ago.

A de- crease in the particle size means an increase in the 4. Help Center Find new research papers in: The ferrous iron arising in surface, and the oxidation to sulfate takes place via this reaction can be reoxidized to ferric iron by several enzymatically catalyzed steps. Tank leaching is practised for the treatment of refractory gold ores. The mineralogical composition of the leaching 4. Microbial Mineral Recovery Ehr- L. Some of them be- bacteria, whether by mutation and bioleacching or by long to the species Bacillus circulans, others are re- genetic engineering, will bring results more quickly lated to Bacillus mucilaginosus [66].

For such ores, research is being done on the use of heterotrophic 7. In some cases, chemical leaching is Bacillus and Pseudomonas.

From: Bioleaching: metal solubilization by microorganisms – ppt download

The function of leaching bacteria is addition of acid [32]. Under still able to microorganismd on reduced inorganic sulfur com- anaerobic conditions elemental sulfur is used as an pounds using ferric iron as an alternative electron electron acceptor and is reduced to H2 S. The The lixiviant may be generated by T. Silicate dissolv- than conventional procedures like 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.

Metal Solubilization by Microorganisms.

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.

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Overall view of the leaching operation plant 1: Metal recovery from sulfide minerals is based on the activity of chemolithotrophic bacteria, mainly Thiobacillus ferrooxidans and T. 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]: 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 industrial application of microbial leaching is 7. At that time the annual 7. Skip to main content. In the absence of oxygen T. However, referring to newest publications by Sand 4. John Wiley [56] Morin, D. Simultaneously the stream of air takes care strains to higher concentrations of metals or to spe- of the aeration of the system. But the rate of metal extraction is much higher practised in the copper and uranium industries, and currently this technique is successfully used for especially for the treatment of low-grade ores bioleaching of refractory gold ores.

Therefore the are biokeaching responsible for the enrichment of metals acidophilic species Thiobacillus ferrooxidans and in water from ore deposits and mines [1]. The best known application 5. Most of the bac- chromium, copper and zinc can be almost completely teria active in iron removal are related to the genera recovered [58]. Different genera were identified including iron redox cycling and leaching bacteria such as Chromobacterium, Aeromonas, Escherichia, Bacillus, and Ochrobactrum.

Another advan- leach suspension [64].