Studies On Solution Chemistry Of Interactions Between Cationic Collectors And Aliminosilicate Aluminum Minerals In Bauxite Flotation Desilica

In this thesis, the flotaion tests have been performed on diaspore, kaolinite, pyrophyllite and illite using alkylamine hydrochloride and quaternary ammonium compoun as collectors. Adsorption mechanism of the cationic collectors on the four minerals have been investigated by Zeta potential measurement, IR spectriscopy. The fluorescence probe technique also is uesed to probe the structure of the cationic collectors adsorption layer on minerals. It is basis of the differences of mineral crystal structure, surface properties and solution chemistry of cationic collectorsIn diaspore crystal lattice, aluminum-oxygen octahedron forms double chain struture. When it is crushed, diaspore surface broken bonds are ionic/covalent Al-O bonds and the diaspore exists strong hydrophilicity. Kaolinite, pyrophyllite and illite all are layer-structured aluminosilicates. During crushing, the minerals are cleaved mainly in the parallel layer directions where the binding is the weakest. The SME results show kaolinite, pyrophyllite and illite are all platelets and the (001) crystal planes are main surface. (001) crystal planes of pyropyllite are molucular bonds and it bears good natural floatbility. kaolinite and illite are hydrogen/molucular bonds and ionic/ molucular bonds, respectively. The surfaces of pyrophyllite kaolinite and illite exhibit part hydrophobicity. Order of natural floatbility of the four minerals is pyrophyllite>kaolinite>illite>diaspore.Diaspore is oxide minerals and the charging mechanism is the H+ of aluminol groups adsorption and dissociation. Charging mechanism of the bases and edges of kaolinite pyrophyllite and illite is difference. Substitution of A13+ or Fe3+ for Si4+in the tetrahedral sheet would give rise to a permanent ( not pH dependent) negative charge on the Si basal plane, and charging mechanism of the edges just like that of diaspore. The PZC of diaspore,kaolinite, illite and pyrophyllite is pH6.2, 4.3, 3.4 and 2.0 respectively. The PZC obtained by solution chemistry calculation is 6.85 and 4.44 for diaspore and kaolinite respectively.The adsorption of cationic collectors alkylamine hydrochloride and quaternary ammonium compound on diaspore is driven by electrostatic interaction and hydrophobic interaction between collectors alkyl chains. The adsorption of the cationic collectors on kaolinite, illite and pyrophyllite is driven by ion exchange but electrostatic interaction and hydrophobic interaction. The amount of adsorption of cationic collectors increases with increasing of length alkyl chains.The fluorescence probe results show the quaternary ammonium compounds adsorbed on the four minerals will be made up of smaller aggregate structures than that for the equivalent chain length alkylamine hydrochloride, even at higher adsorption. It is because of the differences of solution chemistry of primary and quaternary ammonium and the head group structure.The flotation recovery of diaspore by cationic collectors increases with increasing of length alkyl chains and pH. The flotation recovery of pyrophyllite doesn't increase like that of diaspore with increasing of length alkyl chains that because of the good flotability of it, and the flotation recovery decrease with increasing of pH.The flotation rusults of the reverse flotation of Henan bauxite shows octadecylamine hydrochloride is better than dodecylamine hydrochloride. The quaternary ammonium compounds will obtain better flotation target than alkylamine hydrochloride The 1231 is best in the quaternary ammonium compounds. In the reverse flotation separation of Henan bauxite, a satisfactory separation was achieved by 1231 as collector.