| In this paper, seven hydroximic acids collectors were designed and synthesized. By means of micro-flotation tests of pure minerals, the flotation performances of six tertiary amines on diaspore and kaolinite were investigated and figured out. Using the measurements of zeta-potential and FT-IR, the calculations of solution chemistry and quantum chemistry, and the simulations of molecular dynamics, the interaction mechanisms between hydroximic acids and minerals were studied and discussed. The main contents were briefly summarized as follow.(1) When being ground to particles, the liberation of diaspore takes place mainly along the (001) crystal planes, breaking Al-O bonds with high energy and stronger hydrophilicity. The liberation of kaolinite takes place along (001) completly, and along (110) and (010) planes incompletely. Besindes the Al-O bonds whit high energy, there are also the Si-O bonds on these liberation surfaces, which also exhibited the strong hydrophilicity. The surface charging mechanism of diaspore and kaolinite is similarly controlled mainly by the ionization of the surface O-H groups, and this part of charge is dominated by the pH of the pulp. In addition, the isomorphic exchange of kaolinite surface ions is responsible for the permanent negative charge of (001) planes.(2) Under the aim of enhancing the collecting power and selectivity of new collecters on kaolinite, based on the basic structure of flotation reagents and surface characteristics of diaspore and kaolinite, O atom was determined to be the bonding atom of the polar group of new collectors, the polar group was determined to be the Hydroxyl oxime group (-CONHOH). Norpolar group were included, benzene rincycloalkyl, alkyl grou, and the carbon chain lenth of norpolar group were6-9. By using grease, hydroxylamine hydrochloride and formic acid as raw materials, and seven hydroxamic acids were synthesized. The synthetic yield of hydroxamic acid is considerable high, and near all these amines have the purity of more than90%.(3) Flotation of monomineralsFrom the flotations of series of hydroxamic acid, the collectivity of series hydroxamic acids to diaspore in an incremental sequence was shown as follows:Benzyl hydroximic acid<amylic hydroximic acid<heptylic hydroximic acid<sodium oleic acid<octylic hydroximic acid; while the incremental sequence of the colleting power to kaolinite was like this:benzyl hydroximic acid<amylic hydroximic acid<heptylic hydroximic acid<octylic hydroximic acid<oleic acid. The octyl hydroxamic acid, used as collector of bauxite, had more collecting powers and selectivity than the oleic acid.Depressors of NaSiO3, Na4P2O7·10H2O, Na2SiF6and (NaPO3)6had little affect on the recovery of the diaspore, while the can restrain kaolinite effectively, and (NaPO3)6perform excellently.Combination reagents of octyl hydroxamic acid and oleic acid could improve the recovey of the diaspore significantly, when the ratio of the octyl hydroxamic acid was60%, and the best reagent sequence was reagent added with the mixture reagent.(4) Action mechanism of hydroxamic acid on diaspore and kaolinite:Hydroxamic acid reacts on diaspore and kaolinite by chemical bond. Hydroxamic acid anion reduced the Zeta potential on the minrerals. The quality of adsorption on diaspore beloned to multi-layer adsorption was more than on the kaolinite, whinch beloned to single-layer adsorption. From the calculation results, different nonpolargroups affected the charge of the O atom littlly to the hydroxamic acid and hydroxamic acid ion, While which affected the (EHOMOo-ELUMO) and the chemical reactivity in the order of benzohydroxamic acid>cyclohexane hydroxyl oxime acid-heptane hydroxyl oxime, hydrophobic ability in the order of heptane hydroxyl oxime>cyclohexane hydroxyl oxime acid> benzohydroxamic acid.(5) Experiment flotation of manual blend mineral and bauxiteThe experiment flotation with manual blend mineral show the collecting ability and the selectivity in the order of combinations of octyl hydroxyl oxime acid and oleic acid> octyl hydroxyl oxime acid> oleic acid, and the same conclusion all got in open and closed-circuit flotation experiment on bauxite. |
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