Study On The Interface Assembly Mechanism For Flotation Separation Of Bastnaesite-type Rare Earth Ore By Mixed Collectors

On account of the poor selectivity between bastnaesite and associated minerals such as calcite and fluorite,and the difficulty in effective control of interface properties,this study researches the influence of mixed collectors which is composed of different-type collectors on the flotation separation of bastnaesite type rare earth minerals,and selects the appropriative mixed collector scheme which can effectively separate bastnaesite from gangue minerals.Moreover,the assembly mechanism of mixed collectors at the bastnaesite/water interface and the selective adsorption mechanism of efficient depressant are explored.Based on the theoretical research results,the process flow which can realize the efficient recovery of rare earth is designed.This study has important theoretical and practical significance for enriching the basic theory of rare earth ore flotation system,solving the technical problems of rare earth ore flotation separation,and further improving the comprehensive utilization rate of rare earth resources.The results are shown as follows:1.Bastnaesite is close to full flotation using the combination of octanohydroxamic acid and sodium oleate(OHA/Na OL)at the ratio of 2:1,indicating OHA/Na OL has a significant synergistic effect on bastnaesite flotation.The flotation separation of bastnaesite from gangue minerals can be realized at p H 8-9 by using OHA/Na OL mixed collectors and citric acid as depressant,and the dosage of mixed collectors is 2/3 less than that of single OHA.2.By means of Zeta-potential measurements,infrared spectroscopy analyses,in-situ ATR infrared spectroscopy analyses together with two-dimensional infrared spectroscopy analyses,XPS and molecular simulation,it is found that OHA/Na OL mixed collectors co-adsorb on the surface of bastnaesite.And the main adsorption process are that OHA and Na OL first form a complex through hydrogen bonding in the slurry,and then hydroxime group of OHA chelates rare earth ions on bastnaesite surface,leading to the synergistic adsorption of Na OL.3.Through Zeta-potential measurements,microcalorimetric analyses,reaction thermodynamic calculation and XPS,it is found that the key factors of citric acid to achieve the effective separation of bastnaesite from gangue minerals are shown as below.First,the electrical difference between the surface of bastnaesite and gangue minerals makes citric acid more readily adsorb on the surfaces of gangue minerals.Besides,the reaction between the L^3-and Ca²⁺on the surfaces of gangue minerals to form calcium carboxylate is a strong spontaneous reaction at p H 8-9,and the reaction degree with fluorite is intenser than calcite,while the reaction with the surface of bastnaesite is an unspontaneous process.4.When fatty acid and hydroxamic acid are employed as mixed collectors while citric acid is used as depressant,concentrate with REO grade of 58.68%and recovery of 48.73%can be obtained,via combined process of flotation and magnetic separation in“two roughing,two scavenging and three refining”.