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Low-grade diasporic bauxite samples were processed using a hydrocyclone with a small cone angle and the effects of apex diameter, feed pressure and feed concentration were investigated. An increase in apex diameter resulted in changes in the spatial position of the envelope of zero vertical velocity, resulting in a decrease in the ratio of Al2O3/SiO2 in the overflow and an increase in the recovery of Al2O3 in the underflow. Feed pressure and feed concentration had no marked effect on the zero vertical velocity envelope, but separation improved with an increase in feed pressure and was adversely affected by an increase in feed concentration., Low-grade diasporic bauxite samples were processed using a hydrocyclone with a small cone angle and the effects of apex diameter, feed pressure and feed concentration were investigated. An increase in apex diameter resulted in changes in the spatial position of the envelope of zero vertical velocity, resulting in a decrease in the ratio of Al2O3/SiO2 in the overflow and an increase in the recovery of Al2O3 in the underflow. Feed pressure and feed concentration had no marked effect on the zero vertical velocity envelope, but separation improved with an increase in feed pressure and was adversely affected by an increase in feed concentration.

Results are presented which showed that Mycobacterium phlei was adsorbed more readily on pyrite than on galena at pH values above 5, with other process parameters kept constant. Chemical adsorption occurred on the surfaces of the two minerals through Fe, Pb and S, and the degree of reaction between C, N and O on the surface of the Mycobacterium Phlei and the surface elements on the pyrite was greater than for galena. The crystal structure and surface properties of the two minerals and the linkage between groups on the surface of Mycobacterium phlei and the metal ions on the surface of the minerals were the main factors governing the selective adsorption., Results are presented which showed that Mycobacterium phlei was adsorbed more readily on pyrite than on galena at pH values above 5, with other process parameters kept constant. Chemical adsorption occurred on the surfaces of the two minerals through Fe, Pb and S, and the degree of reaction between C, N and O on the surface of the Mycobacterium Phlei and the surface elements on the pyrite was greater than for galena. The crystal structure and surface properties of the two minerals and the linkage between groups on the surface of Mycobacterium phlei and the metal ions on the surface of the minerals were the main factors governing the selective adsorption.

An investigation was carried out into the use of N-dodecylethylene diamine as a collector in the flotation of quartz, haematite, calcite and calamine. The results showed that the flotation recovery increased sharply with increasing collector concentration. Maximum recoveries of 97.64%, 91.04% and 95.99%, respectively, were obtained for quartz, calamine and calcite at a collector concentration of 1.83 x 10(-4) mol/l. The recoveries increased significantly with increasing pH and exceeded 90% over a wide pH range. In the case of haematite the recovery increased with collector concentration and pH but did not exceed 55%. N- dodecylethylene diamine exhibits stronger collectivity than dodecylamine for quartz and calamine, while the recoveries are similar in the case of calcite. Infrared spectra studies showed that hydrogen-binding adsorption and electrostatic adsorption occurred between the collector and the quartz surface., An investigation was carried out into the use of N-dodecylethylene diamine as a collector in the flotation of quartz, haematite, calcite and calamine. The results showed that the flotation recovery increased sharply with increasing collector concentration. Maximum recoveries of 97.64%, 91.04% and 95.99%, respectively, were obtained for quartz, calamine and calcite at a collector concentration of 1.83 x 10(-4) mol/l. The recoveries increased significantly with increasing pH and exceeded 90% over a wide pH range. In the case of haematite the recovery increased with collector concentration and pH but did not exceed 55%. N- dodecylethylene diamine exhibits stronger collectivity than dodecylamine for quartz and calamine, while the recoveries are similar in the case of calcite. Infrared spectra studies showed that hydrogen-binding adsorption and electrostatic adsorption occurred between the collector and the quartz surface.

The selective adsorption was studied of Gordona amarae, Mycobacterium phlei and Bacillus micilayinosus on pyrite, galena and sphalerite. All three strains adsorbed more preferentially on pyrite than on the other two sulphide minerals under neutral and alkaline conditions. FTIR and UV spectroscopy studies showed that the main functional groups were almost the same for the three strains and that they all contained saccharide and protein, with the former having the higher content. The empty orbital numbers of the electron shell of the metal ions on the mineral surface play an important role in the selective adsorption process, and stable metal coordinate constants can be used to explain the contribution to selective adsorption of certain groups in the saccharide of the cell walls., The selective adsorption was studied of Gordona amarae, Mycobacterium phlei and Bacillus micilayinosus on pyrite, galena and sphalerite. All three strains adsorbed more preferentially on pyrite than on the other two sulphide minerals under neutral and alkaline conditions. FTIR and UV spectroscopy studies showed that the main functional groups were almost the same for the three strains and that they all contained saccharide and protein, with the former having the higher content. The empty orbital numbers of the electron shell of the metal ions on the mineral surface play an important role in the selective adsorption process, and stable metal coordinate constants can be used to explain the contribution to selective adsorption of certain groups in the saccharide of the cell walls.

The effect was investigated of polyethylene glycol on the Fe2+ oxidising activities of Acidithiobacillus ferrooxidans strain XZ11 and the bioleaching of chalcopyrite. The surface morphologies and phase composition of the chalcopyrite after bioleaching were characterised using SEM and EDS. The results showed that polyethylene glycol with relative molecular mass greater than 200 promoted the Fe2+ oxidising activity of Acidithiobacillus ferrooxidans. After bioleaching for 20 d using 30mg/l of polyethylene glycol 2000, the Cu extraction yield from chalcopyrite was 451.70 mg/l, a factor of about 1.11 times higher than obtained in bioleaching in the absence of polyethylene glycol. Native-like structure, holes and the formation of Fe(III)-O-OH were observed on the erosion surface of the chalcopyrite. The use of polyethylene glycol increased the cell density of Acidithiobacillus ferrooxidans and the Fe3+ concentration in the leaching solution, accelerating chalcopyrite oxidation dissolution., The effect was investigated of polyethylene glycol on the Fe2+ oxidising activities of Acidithiobacillus ferrooxidans strain XZ11 and the bioleaching of chalcopyrite. The surface morphologies and phase composition of the chalcopyrite after bioleaching were characterised using SEM and EDS. The results showed that polyethylene glycol with relative molecular mass greater than 200 promoted the Fe2+ oxidising activity of Acidithiobacillus ferrooxidans. After bioleaching for 20 d using 30mg/l of polyethylene glycol 2000, the Cu extraction yield from chalcopyrite was 451.70 mg/l, a factor of about 1.11 times higher than obtained in bioleaching in the absence of polyethylene glycol. Native-like structure, holes and the formation of Fe(III)-O-OH were observed on the erosion surface of the chalcopyrite. The use of polyethylene glycol increased the cell density of Acidithiobacillus ferrooxidans and the Fe3+ concentration in the leaching solution, accelerating chalcopyrite oxidation dissolution.

Experiments were carried out on samples of chalcopyrite and galena containing, respectively, 32.9% Cu, 29.1% Fe and 33.2% S and 86% Pb and 13.3% S, to investigate the effect of O,O-bis(2,3-dihydroxypropyl) dithiophosphate (DHDTP) as depressant in the presence of ammonium dibutyl dithiophosphate (DDTP) as collector. Results obtained in the flotation of the single minerals showed that DHDTP slightly depressed chalcopyrite over the whole pH range and strongly depressed galena over the pH range 6-10. The recovery of galena decreased rapidly and that of chalcopyrite decreased slightly with increasing DHDTP dosage. Flotation tests using mixtures of the minerals resulted in a Cu grade and recovery of 24.08% and 81%, respectively, at pH 6 using a DHDTP dosage of 278 mg/l. Zeta potential and adsorption measurements showed that DHDTP was more strongly adsorbed on galena than on chalcopyrite and that chemisorption of DHDTP may occur on galena., Experiments were carried out on samples of chalcopyrite and galena containing, respectively, 32.9% Cu, 29.1% Fe and 33.2% S and 86% Pb and 13.3% S, to investigate the effect of O,O-bis(2,3-dihydroxypropyl) dithiophosphate (DHDTP) as depressant in the presence of ammonium dibutyl dithiophosphate (DDTP) as collector. Results obtained in the flotation of the single minerals showed that DHDTP slightly depressed chalcopyrite over the whole pH range and strongly depressed galena over the pH range 6-10. The recovery of galena decreased rapidly and that of chalcopyrite decreased slightly with increasing DHDTP dosage. Flotation tests using mixtures of the minerals resulted in a Cu grade and recovery of 24.08% and 81%, respectively, at pH 6 using a DHDTP dosage of 278 mg/l. Zeta potential and adsorption measurements showed that DHDTP was more strongly adsorbed on galena than on chalcopyrite and that chemisorption of DHDTP may occur on galena.