| Abstract：The recocery of antimony oxide by flotation is now a difficulty subject in mineral processing, and there are few studies on the technology and basic theory for antimony oxide flotation.In this dissertation, based on the studies of crystal structure and the main cleavage plane property differences for three minerals,the flotation behaviors of three minerals in anion and cation flotation collector system have been investigated by flotation.At the same time,the action mechanisms between flotation reagents and minerals have also been revealed by means of surface potential,adsorption capacity, X-ray photoelectron spectroscopy, infrared spectroscopy and quantum chemical calculations.Main conclusions are obtained as following:(1)Crystal structure and surface properties of three mineralsThe surface energy of major cleavage plane (001)of cervantite and quartz are1.646J/m2and2.675J/m2,respectively.The surface energy of calcite’s major cleavage plane(104) is0.887J/m2.The density of states near Fermi level of cervantite and quartz are almost from the O2p orbit. It indicates that the reactive sites on surface of cervantite and quartz are O, which results in the similarity of their nature.XPS results show that the relative content of oxygen on quartz and cervantite surface is closer to each other, and the calcite surface relative content of oxygen is the lowest, and these cause the differences both of surface potential and the action of reagent with mineral surface.The measured PZC of cervantite,quartz,and calcite are2.4,2.6,and7.6,respectively.(2) Cationic collector flotation system31series quaternary ammonium salt collector have strong collect ability for flotation of cervantite,and the flotation pH range of cervantite expands with the increasing of collectore’s carbon chain length.However, the collecting capacity of31and27series collector for quartz and calcite are stronger than that of cervantite,and it makes difficult to achieve flotation separation of cervantite from quartz and calcite.The flotation of cervantite is depressed while the recovery of quartz is more than85%at pH>10.5,so the reverse flotation separation of cervantite from quartz and calcite can be achieved under this condition.Changes of surface potential and adsorption capacity of dodecylamine on mineral’s surface are consistent with flotation behaviors of minerals using dodecylamine as collector, indicating that electrostatic interaction play an important role in flotation of three minerals by dodecylamine. The order of adsorption energy of dodecylamine molecules,water molecules and dodecylamine ions on cervantite surface is DDA>H2O>DDA+.Dodecylamine cation can not only supplant water molecules from cervantite surface to form hydrophobic layer, but also easy to adsorb on cervantite surface by electrostatic and hydrogen bond adsorption than dodecylamine molecular. The reason for achieving separation of cervantite from quartz and calcite under alkalinite conditions is that dodecylamine molecule can adsorb on quartz and calcite surface to some extent, while it is difficult for dodecylamine molecule adsorbing on cervantite surface in the pulp.(3) Activation of metal ions on three mineralsWithout adding metal ions,sodium oleate has no collectting capacity for cervantite and quartz, but has a good collectting capacity for calcite. Quartz can be activated by Ca+and Mg+under high alkalinity conditions,but cervantite can not be activated.Cervantite can be activated by Al3+and Fe3+, while quartz can be activated meanwhile. Flotation separation of cervantite from quartz and calcite can not be achieved. Cervantite and quartz can be selectively activated by Pb2+ions in a small range of pH. Cervantite and quartz can be selectively activated by Cu2+ions to achieve flotation separation in a lager pH range.Calcite gets a high flotation recovery with adding six metal ions.(4) Anionic collector flotation systemSodium oleate and sodium dodecyl sulfate are the effective collectors for the flotation of cervantite from quartz using copper ions as the activator at pH of6.7and6.1,respectively.Sodium oleate and sodium dodecyl sulfate occured chemical adsorption on activated cervantite surface by copper ions,and only physical adsorption on quartz surface under conditions of pH=6.7and6.1,respectively. Changes of surface potential and adsorption capacity of three minerals in the presence of two reagents are consistent with flotation behavior of three minerals. CuOH+and Cu(OH)2become active sites for oleate ion adsorbing on cervantite surface.CuOH+becomes active site for sodium dodecyl sulfate adsorbing on cervantite surface. CuOH+and Cu(OH)2both act as a "bridge" to connect cervantite surface and anionic collectors, play an important role in activating cervantite.(5)Differences of structure and property of two anionic collectorsThe different flotation behavior on cervantite are caused by the different structure of sodium oleate and sodium dodecyl sulfate.The adsorption energy order ofthree adsorbates on activated cervantite surface by Cu(OH)2is [SDS]->[OH]->[Ol]-.Dodecyl sulfate ions can not repel hydroxyl ions on activated cervantite surface by Cu(OH)2while oleic acid ions can repel hydroxyl ions on activated cervantite surface by Cu(OH)2to achieve flotation.Different from oleic acid ion, dodecyl sulfate ion has stronger electrostatic repulsion to copper hydroxide and weaker chemical adsorption activity.(6) Research on flotation process of Xikuangshan antimony oxide oreA antimony oxide ore with Sb grade about1.11%from Xikuangshan is used as raw material for flotation tests.By "direct flotation" technological process, a concentrate obtained with Sb grade and recovery of2.57%and78.7%, respectively. By"direct flotation-sulfidation roasting-flotation" process, the Sb grade and recovery of obtained concentrate are21.8%and64.81%, respectively. |
PDF Full Text Request