Flotation of Mica-Containing Rubidium under Weak Acidity Medium
Nowadays with the continuous development of science and technology,rubidium has been widely used in photoelectric,aviation,medical and other fields due to its unique physical and chemical properties,becoming one of the important elements in the application of high technology.There was no independent mineral for rubidium and it usually exists in mica in the way of isomorphism,or in salt lake and brine,so,the beneficiation for rubidium-containing mica was one of the main methods to recover rubidium.In this paper,an Australian rubidium-containing lepidolite ore was taken as the research object,the pure ore flotation behavior of rubidium-containing lepidolite and feldspar was mainly studied,and the floatability difference of two kinds of pure minerals under different col-lecting agents,pH value and regulator was investigated and verified by artificial mixed ore.The adsorption mechanism of the collecting agents with rubidium-containing lepidolite and feldspar was studied by means of infrared spectrum(FTIR),zeta potential and X-ray photoelectron spectroscopy(XPS),etc.The results of the pure minerals test indicated that:(1)Three cationic collectors(dodecylam-ine,dodecyltrimethylammonium chloride,trimethyltetradecylammonium chloride)had strong collecting ability for pure minerals of ru-bidium-containing lepidolite and feldspar.(2)The three anion collectors(sodium dodecyl sulfonate,sodium oleate and sodium dodec-yl sulfate)had weak collecting capacity for rubidium-containing lepidolite and feldspar,the flotation recoveries of the two pure miner-als were low,and the recovery changed little with pH value changed.It showed that the single anion collector had poor collecting per-formance for feldspar and rubidium-containing lepidolite,but had certain selectivity.(3)The combination of anion and cation was used as the collector to carry out the flotation test.The test results showed that dodecamine and sodium dodecyl sulfonate had better flo-tation ability when the combination collector was used for flotation.It was found that with the increase of the ratio of sodium dodecyl sul-fonate concentration,the flotation recovery of pure minerals of rubidium-containing lepidolite did not change obviously,but the flota-tion recovery of feldspar decreased greatly,which was beneficial to the flotation separation of two kinds of pure minerals.Under the condition of weak acidity(pH=6),when the concentration ratio of dodecamine and sodium dodecyl sulfonate was 1∶1,and the total concentration was 5×10-4 mol·L-1,the difference of flotation recovery between feldspar and rubidium-containing lepidolite was the larg-est,which had a good collection ability and selectivity.(4)When the dosage of oxalic acid as depressor was less than 300 g·t-1,the flotation recovery of rubidium-containing lepidolite changed little,and the flotation recovery of feldspar decreased significantly.Oxalic acid could increase the difference of flotation recovery between rubidium-containing lepidolite and feldspar,but sodium hexametaphos-phate and sodium silicate could not achieve the purpose of increasing the difference of flotation recovery.(5)The test was carried out when H2SO4 was used to adjust pH to 6,oxalic acid 300 g·t-1,sodium dodecyl sulfonate and dodecylamine as the combined collector,whose concentration ratio was 1∶1,and the total concentration was 5x10-4 mol·L-1.The reagent system was verified by flotation test of artificial mixed ore,and the mass ratio of rubidium-containing lepidolite and feldspar was 1∶1 and 1∶3.The test results showed that the reagent system obtained from pure minerals had good separation effect.When the mass ratio of rubidium-containing lepidolite to feldspar was 1∶1,and the grade of Rb2O was increased from 0.51％of the original ore to 0.76％of the concentrate,and the recovery of Rb2O was 79.8％.When the mass ratio of rubidium-containing lepidolite to feldspar was 1∶3,and the grade of Rb2O was increased from 0.23％of the original ore to 0.58％of the concentrates,the recovery of Rb2O was 70.2％.The results showed that the separation of artificial mixed ore could achieve good effect.The mechanism of collector and mineral surface adsorption showed that:(1)It could be known from solution chemistry calculation that dodecamine existed in the form of positive cationic charge in the vast majority of the so-lution.(2)When dodecamine acted as a combined collector with sodium dodecyl sulfonate,the overall surface potential of feldspar changed in the range of acidity to a small extent,almost the same as the potential of feldspar in deionized water,with no significant change.Compared with the single action of dodecamine,the potential movement on the surface of feldspar was obviously in the direc-tion of negative potential,and the movement amplitude was larger than that of rubidium-containing lepidolite.(3)It could be known from the adsorption capacity test that when dodecamine was combined with sodium dodecyl sulfonate as collector,the adsorption amount of dodecylamine rubidium-containing lepidolite decreases,while the adsorption amount of sodium dodecyl sulfonate increased.The adsorption of dodecamine on feldspar decreased significantly,while the adsorption of sodium dodecyl sulfonate did not change sig-nificantly.The adsorption capacity of rubidium-containing lepidolite was higher than that of feldspar.(4)Through infrared spectrum,when dodecamine and sodium dodecyl sulfonate were used as combined collectors,physical adsorption was carried out on the surface of pure minerals of rubidium-containing lepidolite and feldspar,in which the combined collectors could form hydrogen bonds on the surface of pure minerals of rubidium-containing lepidolite.(5)According to XPS test,it could be seen that when sodium dodecylsulfo-nate and dodecylamine formed a combined collector compared with dodecamine single action,the energy spectrum of aluminum ele-ments on the surface of rubidium-containing lepidolite changed,which indicated that the chemical valence state of aluminum had changed,and sodium dodecylsulfonate and aluminum in mica had chemically reacted to form chemical adsorption.
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