Leptosririllum ferrooxidans-sulfide mineral interactions with
reference to bioflotation nad bioflocculation
(Division of Mineral Processing, Luleå University of Technology, SE-971 87 LULEÅ, Sweden)
Abstract: The adhesion of ferrous ions grown Leptospirillum ferrooxidans cells on pyrite and chalcopyrite minerals was investigated through adsorption, Zeta-potential and diffuse reflectance FT-IR measurements. The influence of bacterial species on minerals floatability was determined by Hallimond flotation tests while the flocculation behaviour was examined by Turbiscan measurements. The minerals iso-electric point (pH 6.5−7.5) after interaction with bacterial cells shifted towards cells iso-electric point (pH 3.3), indicating the chemical nature of cells adsorption on mineral surfaces. The FT-IR spectra of minerals treated with bacterial cells showed the presence of all the cell functional groups signifying cells adsorption. The bacterial cells adsorption on chalcopyrite was higher compared with pyrite, which agreed with cells greater depression effect on chalcopyrite flotation and pronounced flocculation behaviour in comparison with pyrite.
Key words: bacteria; sulphide mineral; Zeta-potential; adhesion; FT-IR; flocculation; flotation