Selective Adsorption Of Bacteria On Sulfide Mineral Surface

Along with the continuous exploitation and utilization of mineral resource, the proportion of unwieldiness ores with deficient, poor and complicated character is rising day and day. As a result, the mineral processing fields face serious challenge, and using more medicaments will pollute environment. Under these circumstances, microbial technology to resources emerges as the times require, which provides a new way to solve the problem of mineral resources utilization. After developing for nearly forty years, microbial technology to resources has gained great achievement in basal research and practical application.Much work having been carried out focus on discussing interaction mechanism in the process of microbiohydrometallurgy, and the main content are factors influencing the adsorbing biomass, the relationship of the adsorbing biomass and bioleaching effect, the macroscopic effect after interacted with microbe. The research about selective adsorption is not deep, which is mainly to intensify selective adsorption phenomena by controlling adsorption conditions and the selective adsorption mechanism is analyzed primarily. In this thesis, the selective adsorption of bacteria on sulfide mineral surface is studied and the key factor resulting selective adsorption is founded by some advanced detection methods. The work in the present paper can be summarized as follows:1. The morphlogy and characteristic of bacteria were investigated. Four strains of bacteria were used:Thiobacillus ferrooxidans, Gordona amarae, Mycobacterium phlei and Bacillus mucilayinosus. Their microscopys were displaied, the physical chemistry charaterisritic of four strains of bacteria were inspected. Measure and test in the cell surface characterization including surface elements' content, UVS spectroscopy, molecular weight, growth curve, contact angle and Zeta-potential.2. Adsorption of four strains of bacteria on the surface of pyrite, chalcopyrite, galena and sphalerite were studied under different influence factors. The results showed that the selective adsorption of Thiobacillus ferrooxidans on sulfide minerals is not obvious, and that of other three strains of bacteria is obvious, more cells absorbed on pyrite and less cells absorbed on chalcopyrite, galena and sphalerite, pH is the key factor influencing selective adsorption of bacteria on mineral surface.3. Choose Thiobacillus ferrooxidans and Mycobacterium phlei as study objects, the functional groups on the surface of bacteria which having a selective adsorption or not were investigated by FTIR and XPS, and the groups inducing selective adsorption are ensured primarily.4. The surface structure and character of four sulfide minerals after cleavage is analyzed by the principle of mineral crystal chemistry, and the state of every element on mineral surface is analyzed by XPS, it is concluded primarily that the main element and its valency on mineral surface which inducing bacteria to have a selective adsorption.5. The mineral surface characteristic of sulfide minerals after interaction with Thiobacillus ferrooxidans and Mycobacterium phlei were achieved by SEM, and the state change of each element on mineral surface were studied by FTIR and XPS. The results are in agreement with adsorption phenomena of these two strains of bacteria on sulfide minerals. It is drawn that the O—H or N—H and C=O groups on two strains' cells have a chemisorption to element Fe, Cu, Pb, Zn, S on mineral surface, and the action of these groups to metal ions on mineral surface is stronger than that of elment S.6. The selective adsorption phenomena of bacteria on sulfide minerals are analyzed. It is discovered that the affinity of functional groups on cell surface to metal ion on pyrite surface is large than that of other three sulfide minerals, and Fe3+ is more important in it. In addition, the surface character and physical characteristic of two kinds of bacteria also have an influence on cells'selective adsorption7. The flotation of four sulfide minerals after pretreated by Thiobacillus ferrooxidans and Mycobacterium phlei were studied. The results indicate the flotation of four sulfide minerals all descend after pretreatment, and pyrite is almost depressed completely after pretreated by Mycobacterium phlei.