• K A Natarajan

      Articles written in Bulletin of Materials Science

    • Electrochemical aspects of grinding media-mineral interaction on sulphide flotation

      M K Yelloji Rao K A Natarajan

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      Galvanic interaction between electrically conducting minerals may affect the mineral surface and influence their flotabilities. The metallographic examinations as well as hardness measurements have been made with grinding media. Rest potential, combination potential, galvanic current and polarization studies were made to understand the probable electrochemical interaction between grinding media and chalcopyrite. The galvanic contact lowered the flotability of chalcopyrite. AES and ESCA indicated that galvanic coupling of chalcopyrite with grinding media resulted in the formation of oxy-hydroxide species of iron on the chalcopyrite surface. Scanning electron microscopy was used to study the surface morphological changes on the grinding media due to galvanic interaction with chalcopyrite.

    • Development ofThiobacillus ferrooxidans ATCC 19859 strains tolerant to copper and zinc

      G P Brahmaprakash Preston Devasia K S Jagadish K A Natarajan G Ramananda Rao

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      A study was carried out to develop strains ofThiobacillus ferrooxidans ATCC 19859 tolerant to higher levels of heavy metal ions. Strains ofT. ferrooxidans capable of growing in Cu2+ (30 g/L) and Zn2+ (60 g/L) have been obtained. The ability of strains tolerant to either copper or zinc to grow in medium containing both the metals has been examined. The copper-tolerant strain (25 g/L) grows better in the medium containing both metals (Cu2+ 25 g/L and Zn2+ 40 g/L) compared to the zinc-tolerant strain (40 g/L).

    • Biotechnology in gold processing

      K A Natarajan

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      The applicability of a biotechnological approach for extracting gold from lean grade and refractory ores and from tailings is analysed. Microbiological as well as physicochemical characteristics of various leaching bacteria are outlined. Technological aspects of bioleaching of refractory gold-bearing concentrates in specially designed bioreactors are illustrated with emphasis on control parameters and use of metal and temperature-tolerant strains. Commercial operations prevalent across the world are detailed and the relevance of biomineral technology for augmentation of gold production in India brought out.

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