| In this dissertation, the differences in crystal structures, surface properties and floatability of kaolinite and diaspore were studied. Some factors effecting on the process of bauxite floatation were found by investigating the flotation behavior of the two minerals on single mineral test under different reagent conditions. Corresponding measures were put forward. At the same time, the action mechanisms between collector and minerals had been researched in details. Main conclusions are obtained as following:1. There are four differences of kaolinite and diaspore on crystal structures and surface properties.In the crystal lattice of diaspore, aluminum-oxygen octahedron forms double chain. In the crystal lattice of kaolinite , aluminum-oxygen octahedron and silicon-oxygen tetrahedron forms Isyer type silicate mineral in a ratio of 1:1;The acidity of aluminum ion on mineral surface is medium, and the acidity of silicon-ion on mineral surface is weak;Abundance of aluminum atom on the surface of diaspore is 1.7 times larger than that on the surface of kaolinite;Absorbing or ionizing H* result in charging on surface of diaspore; Zata-potential of diaspore is variable with pH in the solution. Charging mechanism of on surface of kaolinite are two kind. The charge of lateral surface of kaolinite results from absorbing or ionizing H*, and the charge of layer surface of kaonilite owe to crystal lattice displacement of cation. The latter is related to the degree of displacement and independent of pH value in solution. The point of zero charge (P.Z.C) of diaspore is pH5.5, and pH3.4 for kaolinite.2. Obverse floatation of bauxite using anion collectorOn the obverse floatation of bauxite, the primary factor to result in difference on floatability for kaolinite and diaspore is the difference on abundance of aluminum atom on minerals surface. Because of the difference of acidity for kaolinite and diaspore, sodium oleate tends to take action with aluminum ion but not silicon ion, which is controlled by electric charge. Abundance of aluminum atom on the surface of diaspore is 1.7 times larger than that of kaolinite, so sodium oleate tends to absorb on surface of diaspore.To enhance the dispersion on slurry is the key for obverse floatation of bauxite using anion collector. The results of single mineral flotation with collectors and depressors indicate: there are obvious difference on floating behavior of kaolinite and diaspore, and depressors make no effect on the process of separation. Using appropriate dispersant to enhance theindispersion effect on slurry, satisfactory results of desilication can be obtained by obverse floatation.The new technique of bauxite floatation, selective hydrophobic agglomeration floatation, was put forward in this paper. On the new technique of bauxite floatation, anion collector was KL, and modifiers Na2CO3 and (NaPO3)6 was used to enhance the dispersion on slurry ..The concentrate Al/Si 11.11 and the recovery of Al2O3 90.52% were obtained through closed-circuit test on the ore. The concentrate Al/Si 11.02 and the recovery of Al2O3 88.47% were obtained through the test on bauxite ore (1 ton ore was processed every day).Using Na2CO3 and HZT as modifiers, HZB as collector, 470.39 tons bauxite (Al/Si 5.90) had been processed to produce 402 tons concentrate (Al/Si 11.39) by pilot plant, and recovery of Al2O3 was 86.45%. The results of the matching test on reagents had indicated again that to enhance the dispersion on slurry is the key for obverse floatation of bauxite.3. Reverse floatation using cation collectorOn the reverse floatation of bauxite, the primary factor to result in difference on floatability for kaolinite and diaspore is the different charging mechanism on the mineral surfaces. Using cation collector, the floatability of diaspore in the range of pH less than 5.5, is not as good as in the range of pH over than 5.5. Because of the different charging mechanism on the layer and lateral surface, In acidity and neutral condition, kaolinite is in...
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