Tresearch On Crystal Chemistry And Flotation Behavior Of Bastnaesite,Parisite And Fluorite

Rare earth elements are national strategic metal resources.Bastnaesite and parisite are the main rare earth fluorocarbonate minerals,which are often associated with calcium gangue minerals such as fluorite,so it is difficult to separate them by flotation.Taking bastnaesite,parisite and fluorite as the research objects,this paper studies the crystal structure and common exposed surface properties of the three minerals and their relationship with surface properties such as mineral surface electricity and wettability through quantum chemical calculation combined with flotation test,zeta potential test and XPS test;The effect and mechanism of OHA and sodium silicate on the flotation behavior of bastnaesite,parisite and fluorite were studied.The following research conclusions were obtained:（1）Bastnaesite,parisite and fluorite belong to hexagonal system,monoclinic system and cubic system,respectively.The interatomic bond in the three mineral bulk phases is ionic bond except CO₃ group;Bastnaesite（100）plane,parisite（100）plane and fluorite（111）plane are common exposed surfaces;The surface electrical properties and wettability of bastnaesite,parisite and fluorite are similar.（2）Bastnaesite,parisite and fluorite have good floatability under neutral and weakly alkaline pulp conditions.When p H=9.5 and OHA dosage is 1×10^-4mol/L,the flotation recovery of the three minerals is the highest;The order of inhibition effect of sodium silicate on the three minerals is fluorite>parisite>bastnaesite.The separation effect of the two binary ores is the best when p H=8.5,REO grade and recovery are 60.25%and 80.16%（the binary mixed ore with bastnasite and fluorite）,47.69%and 66.15%（the binary mixed ore with parasite and fluorite）,the flotation separation effect of bastnaesite and fluorite binary mixed ore is better than that of parisite and fluorite binary mixed ore.（3）OHA^-and SiO（OH）₃^-anions are the dominant components of OHA and water glass.The order of adsorption strength（absolute value of adsorption energy）of OHA and sodium silicate on the surface of bastnaesite,parisite and fluorite is:OHA>sodium silicate,OHA≈sodium silicate,OHA<sodium silicate.The differential inhibition mechanism of water glass on bastnaesite,parisite and fluorite are as follows:Sodium silicate preferentially adsorbs on fluorite surface and has stronger inhibition on fluorite.On the surface of parisite,there is competitive adsorption between sodium silicate and OHA,followed by sodium silicate inhibition.On bastnaesite surface,OHA preferentially adsorbed,while sodium silicate had weak inhibition;The water glass component interacts with Ca ions on the surface of parisite and fluorite to form Ca-Si O₃ complex,which is the main reason for the strong inhibition.By studying the crystal chemical properties of bastnaesite,parisie and fluorite and their effects on mineral flotation behavior,this thesis explored the micro-interface interaction mechanism between flotation reagent and the three minerals,and expounded the essential reason of the three minerals have different flotation behavior under the"water glass+hydroxamic acid"reagent system.It provided a theoretical basis for strengthening the flotation separation between the two rare earth minerals and fluorite gangue minerals through reagent system optimization and mineral interface regulation,and had important guiding significance for flotation practice of rare earth ores.