Study On The Adsorption Behavior And Adsorption Mechanism Of Ions In Zinc Oxide

Zinc is an important nonferrous metal and Zinc ore is a vital strategic resource in China. Zinc oxide ore is one of the main kinds of zinc ores. There are abundant of zinc oxide ore resources, while most of them cannot get effective processed and utilized in a long period, for their existence in low grade and complex forms. Apart from these, long-term storage or abandoned result in not only a waste of resources, but also land occupied and environmental pollution.For the past few years, with the continuous development of resources, the zinc sulfide ore gradually becomes poor. Nowadays, the mineral processing of low grade refractory zinc oxide ore has been the difficulty and hotspot in scientific research. While the beneficiation of oxide ore, there are many unavoidable ions produced in the flotation pulp. The ions could change the physicochemical characteristic of mineral surface when they act on the mineral surface, and then the influence of flotation behavior, which has been widely known in beneficiation field. For the faulty establishment of system, feeble scientificity and less basic principles study on zinc oxide ore flotation, we wonder the source and trend of unavoidable ions, the adsorption mechanism acted on mineral surface and the influence on the mineral surface property. For this purpose, in this paper according to the means of modern analysis and testing technology. The mineralogy and behavior of ion existence was deep studied, which based on the object of zinc oxide ore in Lanping and and, the study manly includes the source, variety, quantity, modality and trend of ions. We calculated the solubility of each mineral and its contribution to the ion concentration in pulp. Then according to surface complexation theory, the surface complexation model and mechanism of action between the ion and mineral surface was discussed. At last, the influence to mineral character was investigated, such as floatability, surface electrical behavior and sulfurization based on mixed ions and five kinds of single metal ion included Pb2+, Zn2+, Fe3+, Ca2+, Mg2+.The ions concentration of raw ore grinding pulp showed that there were abundant of ions in the slurry, mainly of them were K+, Na+, Al3+, Pb2+, Zn2+, Fe3+, Ca2+, Mg2+ and SO42-. Ions mainly come from the dissolution of minerals. The main ions source is the dissolution of diffluent minerals at primary stage. As time goes on, part of the ions dissolved from the poorly-soluble minerals.Most of the ions are re-adsorbed by minerals and the rest are in the forms of precipitate or ions. The proportion of absorbed ions on the different minerals surface is proportional to the mineral content in the raw ore. The main adsorbates minerals are quartz, calcite, kaolinite in this zinc oxide ore, followed by sericite and calamine. From the point of adsorption capacity, kaolinite and sericite are the strongest, followed by calcite. The adsorption capacity to the elements which is the constituent of the minerals is generally weak.The results of XPS analysis showed that minerals have an adsorption effect on ions. It results in the elemental composition and content changed on the mineral surface, while causing the chemical environment of the mineral surface changed. The adsorption of metal ions on the surface was mainly chemically reacting with carbonate, and there were exchange reactions exist between the metal ions and calcium ions which were on the calcite surface. Adsorption of metal ions on the quartz and hemimorphite surface was mainly complexation reactions between ions and hydroxyl of mineral surfaces.Quantum chemical calculations showed that the Ca-0 and Zn-O bonds of calcite and smithsonite are mainly for ionic bonding, and C-O is mainly for covalent bonding. The functional groups such as=CO3-,=Ca+,= Zn+,=CO3H,=ZnOH and=CaOH are the surface sites on the calcite and smithsonite surface. The Si-0 of hemimorphite and quartz are mainly for covalent bonding, and the O-Zn is mainly for ionic bonding. The hydroxylation surface site of=SOH is the only kind of site on the surface of hemimorphite and quartz.The studies of surface complexation showed that the adsorption forms of ion-exchange and surface complexation existed side-by-side on the calcite surface. And surface complexation is the only form on the hemimorphite, quartz and calcite surfaces. Finally, we got the action form and adsorption products based on the adsorption data. Meanwhile, the study told us the conclusion that the ions been adsorbed on the surface are easily affected by the solution pH value. When the pH reaches a certain value, the ions may desorb from the mineral surface.While using octadecylamine as collectors, mixed ions will strongly depress the mineral’s floatability in the flotation process, even to the useful minerals more than the gangue minerals. The floatability of smithsonite was decreased by all the five kinds of single metal ion. Solution of Ca2+ and Mg2+ with low concentration could activate the hemimorphite, but opposite with high concentration. Fe3+ could depress the floatability of hemimorphite, while Pb2+ gets some kind of activation. Zn2+ plays less effect in flotation of hemimorphite. Pb2+、Fe3+ and Ca2+ with low concentration could activate quartz, and depress quartz in high concentration, meanwhile, Mg2+、 Zn2+ get significant inhibition to quartz. Mg2+ with low concentration could activate calcite, but significant inhibition in high concentration. Fe3+ has significant inhibition to calcite, while Zn2+、Pb2+ get activation to calcite, and Ca2+ impact less in flotation of calcite.After the action between minerals and mixed ions, the surface potential of smithsonite was reduced, while the other three minerals’increased to some extent. In addition to calcite, the surface potential rise with the increase of single metal ion concentration. In addition to Ca2+, the hydroxide precipitate will generate on the mineral surface, and it will cause that the minerals have three zero-point pH value points.After the action with mixed ions, the adsorption capacity of each mineral to S2" increased, especially quartz and calcite, but smithsonite and henimorphite were relatively little. Ca2+ and Mg2+ could reduce the adsorption of S2-slightly on the smithsonite and hemimorphite surface, but increase a little on calcite and quartz surface. Pb2+, Zn2+ and Fe3+ could increase the adsorption of S2- on the four minerals’ surface, causing the reducing of surface properties difference between useful minerals and gangue minerals, and increasing the difficulty of flotation separation, but this role of calcium and magnesium was not obvious.The results of this thesis preliminarily established the ions behavior system of zinc oxide ore flotation pulp solution. It also developed and improved the zinc oxide ore flotation theory, and there was theoretical significance and application value to understand the behavior of ions in flotation slurry deeply.