| Flotation was a main method for the beneficiation of mid-low grade fluorite ore.Fatty acids were commonly used collectors for fluorite flotation,but its application was limited by its poor water-soluble,poor dispersion,high freezing point and no resistance of hard water which increased agent consumption,and made poor flotation performance at low temperature.A general solution was to increase the pulp temperature,which increased drug costs,thus remained an obstacle for further application of fatty acids.As a good additive,surfactant has drawn more and more attention from flotation researchers,due to its various functions such as emulsification,dispersion,solubilization,wetting,foaming and defoaming which could significantly improve the solution environment.For the shortcomings of oleic acid,a suitable combination surfactant has been selected by a series of experiments.It could significantly improve the flotation behavior of oleic acid at low temperature,and finally fluorite could be recovered by low temperature flotation.With the help of Zeta potential,K100,FTIR,DSA100 and other modern detection techniques,the mechanism of synergism of surfactants was preliminarily discussed.Surfactant screening tests showed that OP-50,sodium laurate,dodecyl dimethyl betaine and DTAC can improve the low-temperature flotation effect of fluorite,especially when sodium laurate and dodecyl dimethyl betaine were used in combination,it would make the betteer synergistic effect.The ratio of oleic acid and composite surfactants was tested and the best flotation performance was achieved at a value of 10%.A series of low temperature fluorite flotation tests were carried out,results showed that the combination of surfactant can improve the low-temperature fluorite flotation effect.In this paper,the stage-grinding,open circuit test of one-stage rougher,eight-stage cleaner and two-stage scavenger flotation was adopted.When the grade of the original ore was 22.03%,with a roughing grinding fineness of-0.074 mm accounts for 65%,pH value of 9.0,the dosage of mixed surfactant 60g/t,the amount of oleic acid 540g/t,the amount of water glass 400g/t,a coarse concentrate regrinding fineness of 92.33%-0.074 mm and the flotation temperature of 10?,a fluorite concentrate with grade 97.39% and recovery rate of 63.66% was obtained.The results of Zeta potential test showed that the adsorption of oleic acid on the fluorite surface made its Zeta potential decline rapidly.When oleic acid was added together with combinatorial surfactants,Zeta potential of fluorite continued driftingtoward negative which proved that the addition of surfactants enhances the adsorption of oleic acid on the surface of fluorite.The results of surface tension test showed that the critical micelle concentration and surface tension of surfactant combination were lower than those of single surfactant addition,indicating that the activity of combined surfactant was stronger.The results of the wettability test of the mineral surface show that compared to using oleic acid only,the addition of combinatorial surfactants made the relative wetting contact angle of fluorite surface increase by around 15o,which showed that fluorite was more hydrophobic.Furthermore,infrared spectrum analysis revealed that oleic acid and sodium laurate absorbed on the surface of fluorite by both chemical and physical adsorption,while the action between dodecyl dimethyl betaine and fluorite was physical adsorption.When mixed surfactant and oleic acid acted on fluorite,coadsorption occurred.Van deer Waals force and Hydrogen bond between reagent molecules improved the surfactivity and increased its dispersion which strengthened the adsorption of oleic acid on the surface of the mineral. |
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