Experimental Study On Extracting Scandium From Niobium Tailings Of Bayan Obo Oxidized Ore

Bayan obo Mine is a polymetallic associated deposit with abundant scandium resources,which is mainly stored in various minerals in a quasi-homogeneous manner and needs to be extracted by acid leaching.This paper studies the microwave roasting-hydrochloric acid leaching process to extract scandium from the niobium tailings in the Bayan obo oxidation ore.First,process mineralogy is carried out on the niobium tailings of oxidized ore,including chemical analysis,mineral analysis,and particle size analysis.The results show that the content of Sc2O3 in the niobium tailings is 253 ppm,and the grade of scandium increases with the decrease in particle size,mostly concentrated in the-500 mesh particle size,which proves the necessity of leaching and the rationality of roasting to open cracks.In microwave roasting,each metal in the mineral has different wave absorbing capabilities,and the resulting thermal stress will cause the mineral to crack and help leaching.Scanning electron microscopy found that the cracks and cracks on the surface of the raw material minerals roasted by microwaves increased.Through experiment comparison,it is found that the leaching efficiency is improved after microwave baking,which proves that the pretreatment method is effective.After that,the conditions of microwave roasting-hydrochloric acid leaching were tested,and the effects of microwave power,microwave roasting time,material particle size,leaching solution solids ratio,leaching time,leaching temperature,hydrochloric acid concentration and stirring speed on scandium leaching rate were investigated.The test results show that the best parameters are:microwave power 560w,microwave roasting time 18min,material particle size-400 mesh accounted for 70%,leaching liquid to solid ratio 4:1,leaching time 1.5h;leaching temperature 150?,hydrochloric acid concentration 10mol/L,stirring speed 200r/min.The stability test was carried out on the basis of the best parameters.The test results showed that the parameters were stable and reliable.Under this condition,the leaching rate of scandium was 96.34%.The above studies show that temperature and hydrochloric acid concentration have the most significant effects on leaching kinetics,and they are quantitatively studied.Experiments on scandium leaching kinetics at different temperatures show that the hydrochloric acid leaching process of scandium is controlled by external diffusion.The reaction activation energy during leaching is a frequency factor A of 3.18,the apparent leaching activation energy Ea=4.3kJ/mol,leaching kinetics The equation can be expressed as 1-(1-?)l/3=3.18×e-4.3/RTt.According to the test of different hydrochloric acid concentrations on scandium leaching kinetics,the apparent reaction order of scandium hydrochloric acid leaching process is 1.81,and the apparent reaction order is greater than 1,indicating that the hydrochloric acid concentration has a great influence on the scandium leaching rate,indicating that with the As the concentration of hydrochloric acid increases,the leaching process of scandium transitions from the kinetic zone to the diffusion zone.This article provides a new idea for the extraction of scandium from the niobium tailings in the Bayan obo oxidation ore,and it has a certain reference for the actual on-site production.