| 1. |
- Das, A., et al.
(author)
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Surface chemical and adsorption studies using Thiobacillus ferrooxidans with reference to bacterial adhesion to sulfide minerals
- 1999
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In: Biohydrometallurgy and the Environment toward the Mining of the 21st century. - : Elsevier. - 0444501932 ; , s. 697-707
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Conference paper (peer-reviewed)abstract
- Adhesion of Thiobacillus ferrooxidans to pyrite and chalcopyrite in relation to its importance in bioleaching and bioflotation has been studied. Electrokinetic studies as well as FT-IR spectra suggest that the surface chemistry of Thiobacillus ferrooxidans depends on bacterial growth conditions. Sulfur-,Pyrite- and chalcopyrite-grown Thiobacillus ferrooxidans were found to be relatively more hydrophobic. The altered surface chemistry of Thiobacillus ferrooxidans was due to secretion of newer and specific proteinaceous compounds. The adsorption density corresponds to a monolayer coverage in a horizontal orientation of the cells. The xanthate flotation of pyrite in presence of Thiobacillus ferrooxidans is strongly depressed where as the cells have insignificant effect on chalcopyrite flotation. This study demonstrate that:(a)Thiobacillus ferrooxidans cells can be used for selective flotation of chalcopyrite from pyrite and importantly at natural pH values.(b)Sulfur-grown cells exhibits higher leaching kinetics than ferrous ion-grown cells.
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| 4. |
- Sharma, P.K., et al.
(author)
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Role of a heterotrophic Paenibacillus polymyxa bacteria in the bioflotation of some sulfide minerals
- 1999
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In: Minerals & metallurgical processing. - 0747-9182. ; 16:4, s. 35-41
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Journal article (peer-reviewed)abstract
- A pure strain of Paenibacillus polymyxa and mineral-adapted strains are used to bring about surface chemical changes on pyrite and chalcopyrite and, thus, their flotation. Paenibacillus polymyxa was adapted by repeated subculturing in the presence of pyrite and chalcopyrite. The surface chemical changes of bacteria due to adaptation and of minerals after their interaction with bacterial cultures are evaluated by electrokinetic and infrared spectroscopy and are discussed with reference to their flotation responses. Interaction of bacterial cells, bacterial metabolites and whole bacterial cultures affected the Hallimond flotation behavior of the sulfide minerals. The Xanthate flotation results show that pyrite, but not chalcopyrite, is depressed when the tests are carried out after interaction with chalcopyrite-adapted Paenibacillus polymyxa. This investigation demonstrated that the surface chemical properties of bacteria can be manipulated successfully to achieve the desired effects in the flotation process.
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| 5. |
- Sharma, P.K., et al.
(author)
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Thiobacillus ferrooxidans interaction with sulfide minerals and selective chalcopyrite flotation from pyrite
- 1999
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In: Advances in flotation technology. - : Society for Mining, Metalurgy and Exploration. - 0873351843 ; , s. 147-165
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Conference paper (peer-reviewed)abstract
- The acidophilic and chemolithotrophic Thiobacillus ferrooxidans bacteria grown in the presence of soluble ferrous ions and solid substrates (sulfur, pyrite and chalcopyrite) as their energy source have been used in the investigations. The cell surfaces are characterized by zeta-potential, contact angle, FT-IR and FT-Raman studies. The adsorption isotherms of the cells on pyrite and chalcopyrite indicate that the adsorption begins on pyrite at a much lower equilibrium cell population than on chalcopyrite. The isotherms tend to level off at a cell adsorption density corresponding to a horizontal monolayer coverage when the geometrical dimensions of the cells are considered. In the presence of cells, the xanthate flotation of pyrite completely depressed, whereas chalcopyrite flotation is unaffected. The results suggest that chalcopyrite can be selectively floated from pyrite, also at a neutral pH region, in the presence of T. ferrooxidans cells
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| 7. |
- Eriksson, K, et al.
(author)
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Experiential knowledge and cost in the internationalization process
- 1997
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In: JOURNAL OF INTERNATIONAL BUSINESS STUDIES. - : JOURNAL INT BUSINESS STUDIES. ; 28:2, s. 337-360
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Review (other academic/artistic)abstract
- Using a behavioral approach, this study identifies and delineates components of experiential knowledge in the internationalization process, Three hypotheses are developed and tested, They center around the lack of knowledge in the areas of foreign busines
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