Bioleaching

Bioleaching, particularly of sulfidic ores, has received much attention since the early 1980s. The conditions needed and mechanisms for such processes have been reviewed. Microbial processes involve complete oxidation of sulfide to sulfate, e.g.,... 

Bosecker, K. Bioleaching Metal solubilization by microorganisms. Ferns Microbiol. Rev. 1997, 20, 591-604. 

Fig. 2. t probability as a function of Student s t statistics for Enzyme Leach (a best case ) and Bioleach (b worst case )... 

The subsamples were split and sent to different laboratories to be subjected to ten commonly-used and proprietary leach/digestion techniques (a) aqua regia partial digestion method at Acme Analytical Laboratories (b) sodium pyrophosphate and cold hydroxylamine leaches at ALS Chemex (c) enzyme and TerraSol leach methods at Skyline Labs (d) Bioleach and soil gas hydrocarbon analyses at Activation Laboratories (e) Mobile metal ion (MMI) extraction at SGS Minerals (f) 4-acid near-total and sodium peroxide sinter total digestions (under the uses contract) at SGS Minerals and (g) de-ionized water leach at the USGS laboratories. 

Biosorption/bioleaching and oxidation/reduction mediated by other elements oxidized or reduced by microorganisms... 

Metal-containing minerals, for example sulfides, can be oxidized and metals can be solubilized. This approach is used for the bioleaching of heavy metals from sewage sludge [40,41] before landfilling or biotransformation. 

BIOCHEMICAL SELF-ASSEMBLY ACTIN ASSEMBLY KINETICS HEMOGLOBIN S POLYMERIZATION MICROTUBULE ASSEMBLY KINETICS BIOCONJUGATE BIOCONVERSION BIOLEACHING... 

McCready, R.G.L. Gould, W.D. (1990). Bioleaching of uranium. In Microbial Mineral Recovery ed. H.L. Ehrlich C. L. Brierley, pp. 107-25. New York McGraw-Hill. McLean, R.J. C. Beveridge, T. J. (1990). Metal-binding capacity of bacterial surfaces and their ability to form mineralized aggregates. In Microbial Mineral Recovery, ed. H. L. Ehrlich C. L. Brierley, pp. 185-222. New York McGraw-Hill. 

Rossi, G. Ehrlich, H. L. (1990). Other bioleaching processes. In Microbial Mineral Recovery, ed. H.L. Ehrlich C. L. Brierley, pp. 149-70. New York McGraw-Hill. 

Scanning electron micrographs (SEM) of bioleached shale, which has been leached with the acid produced by sulfur-oxidizing bacteria, have revealed a pitted, spongy-appearing surface texture. Bioleaching removes primarily the carbonate minerals, such as dolomite and calcite, which are apparently deposited in pits throughout the rest of the mineral matrix. The removal of the carbonate would be expected to increase the porosity of the raw shale. Since the results of SEM reveal only the surface... 

Because of the obvious complexity of the controlling factors that may be involved, we shall not attempt at present to estimate their functional magnitude. The existence of interconnecting channels was postulated from scanning electron micrographs of bioleached shale surface (II) and is supported by evidence from the present study. The increase of porosity by removing the carbonate mineral with dilute acid would presumably improve the permeability of certain chemical compounds into and out of the remaining shale structure. 

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