Study On Flotation Behavior Of Biotite Associated In Endogenous Phosphate Deposits

The endogenous phosphate deposits in China are mainly distributed in the northern region, besides the apatite, some other useful minerals also existed in the deposits which can be comprehensively utilized. The dissertation aimed for the comprehensive utilization of associated mineral resources, chose Shangzhuang phosphate ore in Qinghai Province as the research object and carried out study work for the purpose of recovering the associated biotite mineral. The flotation performances of biotite in typical cationic and anionic collector systems and the effect of metal ions were studied by micro-flotation experiments. On the basis of solution chemistry calculation, zeta potential measurement and infrared spectroscopy, the influence mechanisms of metal ions on biotite flotation as well as the interaction mechanism between collectors and biotite were investigated. Flotation tests of biotite with real ore were conducted based on the above results. The main content of this dissertation was briefly summarized as follows.(1) The results of micro-flotation tests showed that apatite can be effectively recovered with sodium oleate as collector in alkaline conditions without collecting any biotite at the same time. Apart from the-0.074mm fraction, the flotation recovery of biotite in other size fractions all first decreased and then increased with the pulp pH increasing in the system of cationic collector dodecylamine. In addition, the floatability of coarser fractions was rather better than the finer ones, and the optimal size distribution for biotite flotation was-0.42+0.15mm. Compared with dodecylamine, the octadecylamine’s collecting ability for biotite was weaker in general. The collecting ability of three kinds of quaternary ammonium salts for biotite in-0.15mm fraction was in the order of1231>1231>1631. Compared with dodecylamine, the collecting ability of three kinds of quaternary ammonium salts for biotite was weaker on the whole. In the cationic-anionic collector system of sodium oleate and dodecylamine, the flotation recovery of biotite increased gradually with the increasing of pulp pH, and the flotation recovery can reach more than80%in neutral and alkaline conditions.(2) In the sodium oleate system, Ca2+, Mg2+, Cu2+, Pb2+, Fe3+and Al3+displayed activation effect of different intensity for biotite flotation under different pH conditions. In the dodecylamine system, Ca2+, Mg2+and Cu2+exhibited activation effect for biotite flotation under weak acid and alkaline conditions; Pb2+exhibited activation effect only in alkaline conditions; Fe3+and Al3+showed complex influence for biotite flotation. The hydrolysis products of metal ions which influenced biotite flotation were investigated through solution chemistry calculation of the metal ions.(3) The results of zeta potential measurements indicated that PZC (point of zero charge) of the biotite sample was about0.2. Primary amine dodecylamine, octadecylamine and quaternary ammonium salt1231were all able to make the zeta potential of biotite moving towards positive trend, and the trend was more obvious with the concentration increasing. It can be proved that cationic collectors adsorb on biotite surface by electrostatic interaction. Zeta potential of biotite treated by dodecylamine moved towards the positive trend more obvious than that treated by1231of the same concentration, which indicated that the electrostatic interaction between dodecylamine and biotite was stronger. The results of zeta potential measurements were in accordance with that of flotation tests. The results of infrared spectra showed that dodecylamine and octadecylamine adsorbed on biotite surface in the form of physical adsorption; weak physical adsorption occurred between1231,1631and biotite; sodium oleate cannot adsorb on biotite surface alone. The characteristic peaks of dodecylamine appeared on the spectra of biotite treated by mixed collectors, but no evidence proved the adsorption of sodium oleate. The solution chemistry of dodecylamine and oleate acid indicated that dodecylamine mainly adsorbed on biotite surface in forms of RNH3+ions and molecule-ion association RNH3+· RNH2, while the hydrolysis components of oleate acid were not able to adsorb on biotite. Electrical neutralization occurred between the hydrolysis components of dodecylamine and oleate acid together with the co-adsorption effect between the two reagents was the key reason for improving the flotation performance of biotite.(4) Taking the tailings of apatite flotation as the feed of biotite flotation, comparison tests were carried out based on acid flotation process and alkaline flotation process. The results showed that the flotation index was better by acid process. Through the acid flotation process under optimum conditions, biotite concentrate with an operation yield of30.28%, K2O grade of8.38%and K2O operation recovery of72.06%was obtained.Research findings of the dissertation can provide theoretical support and technical reference for the flotation recovery of biotite associated in endogenous phosphate ore. Furthermore, the related conclusions can also provide reference for the flotation research of mica minerals.