| More than70%of Cu deposits in China are low grade and complex sulfide ores.The ore grades for various commodities show long-term declining trends over time.The exploitation of low grade chalcopyrite ore by traditional method was not economical.Bioleaching followed by solvent extraction(SX) and electrowinning(EW) operation has been used to extract Cu from secondary copper sulfides.However,when it was used to deal with primary copper sulfides such as chalcopyrite,the leaching rate was very low.Therefore,in order to make the bioleaching process completely successful,it needs to study the parameters that affect the microbial activity,which is critical to the bioleaching by accelerating the bioleaching processMechanistically based kinetic models are required for the design,optimization and control of bioleaching processes.The model of bioleaching includes direct leaching by the cells attached to the mineral surface(direct leaching mechanism),ferric leaching of sulfide minerals(indirect leaching mechanism) and leaching by both of these two mechanismsBased on the above purpose,the main research in this work includes:1.Competitive adsorption of binary mixture of L.Ferriphilum、A.caldus and A.ferrooxidans onto chalcopyriteCompetitive adsorption of binary mixture of L.Ferriphilum、A.caldus and A.ferrooxidans onto chalcopyrite surface was studied.The adsorption of pure L.Ferriphilum、A.caldus and A.ferrooxidans,and their binary mixture onto chalcopyrite were all in accordance with the Langmuir adsorption isotherm equation.The CAm value of the mixed culture was smaller than the sum of the combined CAm values of each species,the KA value of the binary mixture was also smaller than that of each single component,which indicated that these three bacteria had competitive adsorption sites on chalcopyrite.Real-time quantitive PCR was used to quantify the relative amounts of L.Ferriphilum、A.caldus and A.ferrooxidans adsorbed onto the surfaces of chalcopyrite when exposed to a mixture of these three microorganisms.The adsorption of L.Ferriphilum was not affected by A.caldus and A.ferrooxidans.However, adsorption of A.caldus and A.ferrooxidans were greatly affected by the presence of L.Ferriphilum.The percentages of adsorbed cells of L.Ferriphilum were nearly the same for cells in the pure and binary mixture(4S%and49%,respectively),however the percentages of adsorbed cells of A.caldus and A.ferrooxidans decreased from68%to63%and80%to65%when changed from a pure culture to a culture mixed with L.Ferriphilum.Zeta potential measurement indicated that the three bacteria were positively charged and the net electrical charge on L.Ferriphilum surfaces was1.6、1.2times greater than the net electrical charge on A.caldus and A.ferrooxidans at pH2.0.The FT-IR spectra showed the presence of CH、CH2、CH3、NH、NH2、NH3、COOH and CONH groups,which are common to any protein molecule. L.Ferriphilum has more NH3group than A.caldus and A.ferrooxidans. A.caldus has more CH3group than L.Ferriphilum and A.ferrooxidans.The analyse of surface thermodynamics showed that the free energy of L.Ferriphilum-chalcopyrite interactions was the steadiest.2. Competitive adsorption of binary mixture of L.Ferriphilum、A.caldus onto chalcopyriteCompetitive adsorption of binary mixture of L.Ferriphilum, A.caldus onto chalcopyrite surface was studied.The adsorption of pure L.Ferriphilum、A.caldus,and their binary mixture onto chalcopyrite were all in accordance with the Langmuir adsorption isotherm equation.The CAm value of the mixed culture was smaller than the sum of the combined CAm values of each species,the KA value of the binary mixture was also smaller than that of each single component,which indicated that these two bacteria had competitive adsorption sites on chalcopyrite. Real-time quantitive PCR was used to quantify the relative amounts of L.Ferriphilum、A.caldus adsorbed onto the surfaces of chalcopyrite when exposed to a mixture of these two microorganisms.The adsorption of L.Ferriphilum was not affected by A.caldus.However, adsorption of A.caldus was greatly affected by the presence of L.Ferriphihim.The percentages of adsorbed cells of L.Ferriphilum were nearly the same for cells in the pure and binary mixture(48%and50%.respectively),however the percentages of adsorbed cells of A.caldus decreased from68%to61%when changed from a pure culture to a culture mixed with L.Ferriphilum.Zeta potential measurement indicated that the two bacteria were positively charged and the net electrical charge on L.Ferriphilum surfaces was1.6times greater than the net electrical charge on A.caldus at pH2.0.The FT-IR spectra showed the presence of CH、CH2、CH3、NH、NH2、NH3、COOH and CONH groups,which are common to any protein molecule. L.Ferriphilum has more NH3group than A.caldus. A.caldus has more CH3group than L.Ferriphilum.The analyse of surface thermodynamics showed that the free energy of L.Ferriphilum-chalcopynte interactions was the steadiest.3. Competitive adsorption of binary mixture of L.Ferriphilum、A.ferwoxidans onto chalcopyrite Competitive adsorption of binary mixture of L.Ferriphilum、A.ferrooxidans onto chalcopyrite surface was studied.The adsorption of pure L.Ferriphilum A.ferrooxidans,and their binary mixture onto chalcopyrite were all in accordance with the Langmuir adsorption isotherm equation.The CAm value of the mixed culture was smaller than the sum of the combined CAm values of each species,the KA value of the binary mixture was also smaller than that of each single component,which indicated that these two bacteria had competitive adsorption sites on chalcopyrite.Real-time quantitive PCR was used to quantify the relative amounts of L.Ferriphilum、A,ferrooxidans adsorbed onto the surfaces of chalcopyrite when exposed to a mixture of these two microorganisms.The adsorption of L.Ferriphihim was not affected by A.caldus.However, adsorption of A.ferrooxidans was greatly affected by the presence of Ferriphilum.The percentages of adsorbed cells of L.Ferriphium were nearly the same for cells in the pure and binary mixture(48%and47%,respectively),however the percentages of adsorbed cells of A.ferrooxidans decreased from80%to69%when changed from a pure culture to a culture mixed with L.Ferriphilum.Zeta potential measurement indicated that the two bacteria were positively charged and the net electrical charge on L.Ferriphilum surfaces was1.2times greater than the net electrical charge on A.ferrooxidans at pH2.0.The FT-IR spectra showed the presence of CH、CH2、CH3、NH、NH2、NH、COOH and CONH groups,which are common to any protein molecule. L.Ferriphilum has more NH3group than A.ferrooxidans. A.ferrooxidans has more CH3group than L.Ferriphilum.The analyse of surface thermodynamics showed that the free energy of L.Ferriphilum-chalcopy rite interactions was the steadiest.4. Competitive adsorption of binary mixture of A.caldus and A.ferrooxidans onto chalcopyrite Competitive adsorption of binary mixture of A.caldus、A.ferrooxidans onto chalcopyrite surface was studied.The adsorption of pure A.caldus、A.ferrooxidans,and their binary mixture onto chalcopyrite were all in accordance with the Langmuir adsorption isotherm equation.The CAm value of the mixed culture was smaller than the sum of the combined CAm values of each species,the KA value of the binary mixture was also smaller than that of each single component,which indicated that these two bacteria had competitive adsorption sites on chalcopyrite.Real-time quantitive PCR was used to quantify the relative amounts of A.caldus、 A.ferrooxidans adsorbed onto the surfaces of chalcopyrite when exposed to a mixture of these two microorganisms.The adsorption of A.caldus was not affected by A.ferrooxidcms.However, adsorption of A.ferrooxidcms was greatly affected by the presence of A.caldus.The percentages of adsorbed cells of A.caldus were nearly the same for cells in the pure and binary mixture(68%and69%,respectively),however the percentages of adsorbed cells of A.ferrooxidcms decreased from80%to73%when changed from a pure culture to a culture mixed with A.caldus.Zeta potential measurement indicated that the two bacteria were positively charged and the net electrical charge on A.ferrooxidcms surfaces was1.3times greater than the net electrical charge on A.caldus at pH2.0.The FT-IR spectra showed the presence of CH、CH2、CH3、NH、NH2、NH3、COOH and CONH groups,which are common to any protein molecule. A.ferrooxidcms has more NH3group than A.caldus. A.caldus has more CH3group than A.ferrooxidans.The analyse of surface thermodynamics showed that the free energy of A.caldus-chalcopyrite interactions was the steadiest when d<2nm. |
PDF Full Text Request