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Due to the same active Al atoms contained by spodumene, beryl and feldspar, the characteristic surface crystal chemistry of minerals was found to be the major contributing factor for the selective flotation separation. The surface crystal chemistry and anisotropy of spodumene flotation with sodium oleate (NaOL) were studied using single mineral flotation tests, zeta potential measurements, infrared spectral analysis, density functional theory calculation and molecular dynamics simulation. The results show that the flotation recovery rate first increases but then decreases with increasing pH. The flotation recovery rate reaches maximum value at pH 8.5. Within the appropriate particle size range, when the particle size is much more coarse the flotation recovery is higher which shows Al sites on the surface of minerals reacting with NaOL by chemisorption. The order of broken bond densities on the surface of the spodumene crystal planes and interaction energy with NaOL is (110), (001), which is the main cause for the difference in flotation behaviour of spodumene for different particle size fractions., Due to the same active Al atoms contained by spodumene, beryl and feldspar, the characteristic surface crystal chemistry of minerals was found to be the major contributing factor for the selective flotation separation. The surface crystal chemistry and anisotropy of spodumene flotation with sodium oleate (NaOL) were studied using single mineral flotation tests, zeta potential measurements, infrared spectral analysis, density functional theory calculation and molecular dynamics simulation. The results show that the flotation recovery rate first increases but then decreases with increasing pH. The flotation recovery rate reaches maximum value at pH 8.5. Within the appropriate particle size range, when the particle size is much more coarse the flotation recovery is higher which shows Al sites on the surface of minerals reacting with NaOL by chemisorption. The order of broken bond densities on the surface of the spodumene crystal planes and interaction energy with NaOL is (110), (001), which is the main cause for the difference in flotation behaviour of spodumene for different particle size fractions.

A Cu/Mo separation experiment for a chalcopyrite-molybdenite bulk concentrate containing steatite is described. The use of a closed-circuit flowsheet comprising one roughing, two scavenging and seven cleaning steps resulted in a copper concentrate with a Cu grade of 23.52% and recovery of 99.83% and a molybdenum concentrate with Mo grade 34.46% and recovery 88.97%. In a trial reverse-flotation test to separate molybdenite and steatite, a final molybdenum concentrate grading 45.16% Mo was obtained with operational recovery of 97.91%., A Cu/Mo separation experiment for a chalcopyrite-molybdenite bulk concentrate containing steatite is described. The use of a closed-circuit flowsheet comprising one roughing, two scavenging and seven cleaning steps resulted in a copper concentrate with a Cu grade of 23.52% and recovery of 99.83% and a molybdenum concentrate with Mo grade 34.46% and recovery 88.97%. In a trial reverse-flotation test to separate molybdenite and steatite, a final molybdenum concentrate grading 45.16% Mo was obtained with operational recovery of 97.91%.

The tailings contained 0.84% Cu, 0.64% WO3 and 0.84% Sn, with the Cu predominately present as chrysocolla with some in solid solution with W and Sn. W was mainly present as wolframite and Sn as cassiterite. A chlorination segregation, flotation, high-intensity magnetic separation, gravity separation process was developed for processing the tailings. Chlorination segregation was used to separate the Cu from the W and Sn minerals, with the Cu minerals undergoing phase changes while the other minerals did not. Optimum conditions were temperature 950 degrees C, reaction time 45 minutes, CaCl2 and coke dosages of 3% each and primary grinding to 95% less than 74 micrometres. Magnetic separation was carried out following secondary grinding to 95% less 38 micrometres using a magnetic field intensity of 1.0 T. Under optimum conditions Cu, W and Sn concentrates with grades and recoveries of 25.04% and 83.19%, 60.22% and 64.26% and 40.11% and 65.59%, respectively, were obtained., The tailings contained 0.84% Cu, 0.64% WO3 and 0.84% Sn, with the Cu predominately present as chrysocolla with some in solid solution with W and Sn. W was mainly present as wolframite and Sn as cassiterite. A chlorination segregation, flotation, high-intensity magnetic separation, gravity separation process was developed for processing the tailings. Chlorination segregation was used to separate the Cu from the W and Sn minerals, with the Cu minerals undergoing phase changes while the other minerals did not. Optimum conditions were temperature 950 degrees C, reaction time 45 minutes, CaCl2 and coke dosages of 3% each and primary grinding to 95% less than 74 micrometres. Magnetic separation was carried out following secondary grinding to 95% less 38 micrometres using a magnetic field intensity of 1.0 T. Under optimum conditions Cu, W and Sn concentrates with grades and recoveries of 25.04% and 83.19%, 60.22% and 64.26% and 40.11% and 65.59%, respectively, were obtained.

The flotation of powellite (CaMo)4) and apatite was investigated in the presence of sodium oleate. The results showed that sodium oleate exhibited good flotation performance for both minerals. Powellite and apatite showed similar behaviour under alkaline conditions, and recovery of the two minerals was more than 80%. Sodium hexametaphosphate reduced the recovery of powellite and apatite to varying degrees, and at a dosage of 220 mg/l the recoveries of the two minerals were 62.5% and 20.3%, respectively. Sodium oleate significantly increased the work of adhesion of the grains of both minerals, facilitating their absorption by bubbles. Sodium hexametaphosphate increased the difference in hydrophobicity between the minerals, optimising their separation. The adsorption mechanism of sodium oleate on the two minerals involved chemisorption., The flotation of powellite (CaMo)4) and apatite was investigated in the presence of sodium oleate. The results showed that sodium oleate exhibited good flotation performance for both minerals. Powellite and apatite showed similar behaviour under alkaline conditions, and recovery of the two minerals was more than 80%. Sodium hexametaphosphate reduced the recovery of powellite and apatite to varying degrees, and at a dosage of 220 mg/l the recoveries of the two minerals were 62.5% and 20.3%, respectively. Sodium oleate significantly increased the work of adhesion of the grains of both minerals, facilitating their absorption by bubbles. Sodium hexametaphosphate increased the difference in hydrophobicity between the minerals, optimising their separation. The adsorption mechanism of sodium oleate on the two minerals involved chemisorption.

The following papers are presented: Extraction of vanadium from hardest refractory stone coal using recirculating fluidised roasting and pressure leaching technology, by Feng Ya-Li et al., p.2052-2060, 15 refs.; Process of vanadium extraction from stone coal vanadium ore by activated sulphuric acid leaching at atmospheric pressure, by Ju Zhong-Jun et al., p.2060-2068, 16 refs.; and Flotation technology and adsorption mechanism of vanadium extraction from stone coal, by Sun Wei et al., p.2069-2074, 18 refs. The results of the various investigations showed that the primary V mineral in a stone coal grading 1.10% V2O5 is roscoelite, which contains 62.28% of the V while the rest is in iron oxide and clay minerals; the main gangue is quartz. Closed-circuit flotation yielded a concentrate grading 3.20% V2O5 with 74.5% recovery. Fluidised roasting and pressure leaching of a stone coal containing 0.62% V, 50.73% of it in phlogopite and 48.24% in muscovite, found the ore very refractory but yielding up to 98.11% recovery by recirculating fluidised roasting without Na treatment and pressure leaching at 150 degrees C and a 1:1 solid-liquid ratio for 6 h. Another stone coal grading 0.44% V gave more than 86.9% recovery from the size fraction 80% smaller than 74 micrometres over a two-stage countercurrent process, when activated with 60 kg/t CaF2 along with a catalyst and leached for 6 h in 150 g/l H2SO4 at 90 degrees C with a liquid:solid ratio of 2:1., The following papers are presented: Extraction of vanadium from hardest refractory stone coal using recirculating fluidised roasting and pressure leaching technology, by Feng Ya-Li et al., p.2052-2060, 15 refs.; Process of vanadium extraction from stone coal vanadium ore by activated sulphuric acid leaching at atmospheric pressure, by Ju Zhong-Jun et al., p.2060-2068, 16 refs.; and Flotation technology and adsorption mechanism of vanadium extraction from stone coal, by Sun Wei et al., p.2069-2074, 18 refs. The results of the various investigations showed that the primary V mineral in a stone coal grading 1.10% V2O5 is roscoelite, which contains 62.28% of the V while the rest is in iron oxide and clay minerals; the main gangue is quartz. Closed-circuit flotation yielded a concentrate grading 3.20% V2O5 with 74.5% recovery. Fluidised roasting and pressure leaching of a stone coal containing 0.62% V, 50.73% of it in phlogopite and 48.24% in muscovite, found the ore very refractory but yielding up to 98.11% recovery by recirculating fluidised roasting without Na treatment and pressure leaching at 150 degrees C and a 1:1 solid-liquid ratio for 6 h. Another stone coal grading 0.44% V gave more than 86.9% recovery from the size fraction 80% smaller than 74 micrometres over a two-stage countercurrent process, when activated with 60 kg/t CaF2 along with a catalyst and leached for 6 h in 150 g/l H2SO4 at 90 degrees C with a liquid:solid ratio of 2:1.

Diasporic bauxite is a major source for aluminium oxide production in China, but bauxite ores cannot be economically treated using the Bayer process unless the Al2O3/SiO2 mass ratio is greater than 10. The use was studied of the cationic surfactants dodecyltrimethylammonium chloride (DTAC) and cetyltrimethylammonium chloride (CTAC) for the flotation of diaspore and kaolinite. The recovery of kaolinite increased with pH using DTAC and CTAC as collectors, while diaspore exhibited the opposite behaviour. The recoveries of the minerals increased with increasing carbon chain length of the collectors, but the effect was significantly less for kaolinite than for diaspore. At low surfactant concentrations the cationic surfactants were readily adsorbed on the diaspore surface solely through electrostatic interaction, while an ion exchange process also occurred in the case of kaolinite. With an increase in surfactant concentration adsorption was attributed to hydrophobic association of chain-chain interactions. Studies of the micro-polarity of the mineral surfaces showed that CTAC exhibited better hydrophobic characteristics than DTAC. Larger aggregates were formed on diaspore than kaolinite using CTAC at the same solution concentration. The chain length of the cationic surfactants had a greater effect on the adsorption on diaspore than on kaolinite, confirming the flotation results., Diasporic bauxite is a major source for aluminium oxide production in China, but bauxite ores cannot be economically treated using the Bayer process unless the Al2O3/SiO2 mass ratio is greater than 10. The use was studied of the cationic surfactants dodecyltrimethylammonium chloride (DTAC) and cetyltrimethylammonium chloride (CTAC) for the flotation of diaspore and kaolinite. The recovery of kaolinite increased with pH using DTAC and CTAC as collectors, while diaspore exhibited the opposite behaviour. The recoveries of the minerals increased with increasing carbon chain length of the collectors, but the effect was significantly less for kaolinite than for diaspore. At low surfactant concentrations the cationic surfactants were readily adsorbed on the diaspore surface solely through electrostatic interaction, while an ion exchange process also occurred in the case of kaolinite. With an increase in surfactant concentration adsorption was attributed to hydrophobic association of chain-chain interactions. Studies of the micro-polarity of the mineral surfaces showed that CTAC exhibited better hydrophobic characteristics than DTAC. Larger aggregates were formed on diaspore than kaolinite using CTAC at the same solution concentration. The chain length of the cationic surfactants had a greater effect on the adsorption on diaspore than on kaolinite, confirming the flotation results.