Study On Flotation Purification Process And Mechanism Of Acid Grade Fluorite For Fluorine Material

Organic fluorinating chemicals mainly use acid-grade fluorite（CaF2≥97%）as raw material to produce fluoropolymer materials,fluorocarbon compounds and organic fine fluorinating chemicals.There are thousands of products,and there is no substitute at present.With the rapid progress of fluorine chemical technology,the demand for acid grade fluorite is increasing.Fluorite is generally associated with minerals such as quartz,calcite,barite and clay,and must be purified by flotation.Due to its non-renewable scarcity property,it is called"world-class scarce resources similar to rare earths",so it is necessary to study the process and mechanism of flotation purification of acid grade fluorite.In this paper,in view of the problems of fine muddy easy cover,difficult separation of fluorite and calcite in the flotation process of clay carbonate-containing fluorite mine,this paper proposes to use acidified water glass as a flotation inhibitor through an efficient flotation process to obtain qualified acid grade fluorspar products,and discuss its mechanism of action through single mineral flotation test,infrared spectrum analysis and solution chemical analysis.At the same time,based on the basic theory of flotation,Atomic Force Microscope（AFM）and viscosity method were used to study the mineral surface hydration film.It provides theoretical support for the study of bubble mineralization process of mineral flotation by improving the environment of the slurry solution and selectively thinning or strengthening the hydration film on the particle surface.The main research contents and conclusions are as follows:（1）Experimental study on flotation of clay carbonate-containing fluorite mineIt is proposed to use acidified water glass as an inhibitor to add drugs in stages,and use a rough sweep and four-stage selected closed-circuit flotation process to test.The fluorite concentrate indexes obtained by the flotation test are CaF₂ 98.12%,CaCO₃0.60%and SiO2 0.59%respectively,and the recovery rate of fluorite is 82.66%.The fluorite concentrate has reached the index requirement of acid grade fluorite,and the grade and recovery rate of fluorite concentrate have increased by 5.1 and 12.6percentage points relative to the on-site index.（2）Research on the action mechanism of acidified water glass in fluorite flotationAccording to the single mineral flotation test,when acidified water glass is used as an inhibitor,the floatability of fluorite is better at pH=5-8,and the recovery rate is about80%,while calcite is obviously suppressed and recycled The rate is less than 30%.Acidified water glass can significantly inhibit calcite at ore slurry pH=7.As an inhibitor of calcite,acidified water glass is superior to sodium lignosulfonate and water glass.Through infrared spectroscopy analysis,it can be seen that when calcite is successively reacted with acidified water glass and sodium oleate,the absorption peaks of-CH₃ and-CH₂-at 2977cm^-1,2863cm^-11 and 2514 cm^-11 are significantly reduced,but at 1008cm^-11 there is a characteristic absorption peak of siloxy group,indicating that the adsorption of acidified water glass hydrolysate on the surface of calcite hinders the adsorption of oleic acid ions on the surface of calcite,and the acidified water glass has a strong inhibitory effect on the adsorption of oleic acid ions on the surface of calcite.The solution chemistry study of acidified water glass shows that the main component of acidified water glass is active silicic acid colloid at pH<7,and the active silicic acid colloid is further hydrolyzed into dispersed silica gel[nSiO₂].The adsorption and fixation strength of silicic acid colloid on the surface of calcite is relatively high.Oleic acid ions adsorbed on the surface of calcite are squeezed and desorbed due to the competitive adsorption of silicic acid colloid.At the same time,it is proposed that the silicic acid colloid formed in the acidified water glass has the characteristics of adsorption bridging,net trapping and sweeping,and has a good coagulant effect,which helps the fine particles in the tailings to settle quickly.（3）Micro-morphology and hydration film of mineral surface in different solution environment in fluorite flotation systemUsing AFM to study the surface of minerals,the results show that the surfaces of fluorite and calcite have been dissolved in deionized water to varying degrees,resulting in a significant change in micro-morphology and the formation of a hydrated film.Combined with the AFM force-distance curve,the average hydration film thickness of fluorite,calcite and quartz surface formed in deionized water was calculated as 9.8nm,13.7nm and 22.1 nm respectively.The average thickness of the hydrated film formed on the surface of fluorite,calcite and quartz in the acidified water glass solution increased to varying degrees,reaching 13.5nm,21.7nm and 23.3nm,respectively,and the thickness of the hydrated film on the surface of calcite and quartz The thickness of the hydrated film on the surface is very close,indicating that the hydrolysate of the acidified water glass has been adsorbed on the calcite surface to a greater degree,so that the surface hydrophilicity is increased,thereby selectively separating from the fluorite,which is consistent with the previous results.It provides a theoretical basis for improving the fluorite flotation index in the fluorite flotation system.Viscosity method is used to study the hydration film of silica surface in aqueous solution based on Einstein viscosity theory.The hydration factor is derived to characterize the degree of hydration of the same colloidal particles in different solutions.Comparing the hydration factors of silica at different pH,it was found that the maximum hydration factor was formed in the case of deionized water at pH=5.33.