Study On The Mechanism Of Lead Ion Modification Induced Sulfide Xanthate Flotation

Zinc plays a key role in the national economy and infrastructure construction.At present,the mine production of zinc in China has ranked first in the world,but it cannot meet the demand for zinc metal consumption in our country.And as the reserves of zinc sulfide minerals that are easily enriched gradually decrease,the development and utilization of zinc oxide minerals will be necessary.Compared with hydrometallurgy,flotation is a cost-effective method relatively for separating and enriching zinc oxide minerals.In the process of flotation separation of zinc oxide ore,the disadvantages include a high content of slime?fine-grained ore particles?,a large amount of flotation reagent and the zinc silicate minerals is not easy to sulfidization.Therefore,it is necessary to research and develop new-type zinc oxide ores flotation technology.Based on the characteristics of zinc oxide minerals,combined with the literature reviewed,the ammonia pre-treatment enhanced lead ions modification to induce sodium sulfide sulfidization xanthate flotation technology was proposed.Taking the smithsonite as the research object,the foundational key issues of the technology were systematically studied via flotation,modern analysis techniques and theoretical calculation models.The results of the single mineral micro-flotation test proved that the smithsonite flotation recovery was improved after lead ions modification,lead ions modification–sodium sulfide sulfidization or ammonia treatment–lead ions modification–sodium sulfide sulfidization,respectively,where the xanthate functioned as a collector.Among them,the prominent means was ammonia treatment–lead ions modification–sodium sulfide sulfidization xanthate flotation,when the p H was 10 approximately,the concentrations of NH₃·H₂O,Pb?NO₃?₂,Na₂S and xanthate were 2.5×10^-3 mol/L,6×10^-4 mol/L,3×10^-4mol/L and 50 mg/L,the flotation recovery of smithsonite was80.91%.Compared with the traditional ammonia treatment–sulfidization–metal ions activated xanthate flotation technology the new technology can obtain more outstanding flotation indexes.The results of ICP-MS measurement,Visual MINTEQ model calculation and XPS surface analysis revealed that the lead ions modification can be achieved via ion exchange on the mineral surface.During the modification,large amounts of Pb species,including Pb CO₃ and Pb₃?CO₃?₂?OH?₂,were formed on the smithsonite surface.The results of FT-IR spectroscopy,To F-SIMS analysis,and UV-visible spectrophotometry test indicated that the smithsonite modification with lead ions not only increased the adsorption of xanthate,but also enhanced the adsorption stability on the mineral surface.In addition,Pb carbonate can react with xanthate to form a hydrophobic Pb-xanthate precipitate,so that the hydrophobic xanthate anion can be stably attached to the smithsonite surface.Therefore,the interaction of Pb ions with the smithsonite surfaces enhanced the adsorption and stability of the hydrophobic layer,resulting in the promoted hydrophobicity of smithsonite.The results of ICP-OES measurement,Visual MINTEQ model calculation and XPS surface analysis suggested there was a positive correlation between the adsorption of Pb and S species on the smithsonite surface,and the adsorption of S species was more stable on the lead ions modified smithsonite surface.During the sulfidization process,sodium sulfide not only reacted with the Pb carbonate formed via the surface modification to form Pb S,but also interacted with the Zn of the smithsonite surface to produce ZnS and polysulfide,thereby achieving the lead ions modification to induce sodium sulfide sulfidization and xanthate flotationThe results of XPS surface analysis shown that the ammonia may dissolve the Zn on the smithsonite surface,after the smithsonite was treated with ammonia,resulting in a decrease in relative amounts of Zn2p,and the treatment with ammonia can strengthen the adsorption of Pb species.The products that were formed via ammonia treatment and lead ions surface modification were roughly the same as those formed by the modification of the single lead ions,and they were both Pb carbonates.According to the results of XPS analysis,the electronegativity of the new Pb carbonate was increased in the presence of ammonia,so that the Pb species was most likely Pb₃?CO₃?₂?OH?₂.The results of solution chemical calculations theoretically revealed that the Zn species that were formed on the smithsonite pulp include zinc hydroxyl complex Zn?OH?₂ and zinc ammonia complex Zn?NH3?²⁺via ammonia treatment and lead ion modification,while Pb species containd Pb?OH?₂ besides Pb carbonate PbCO₃.