Study Of Microwave Sodium Salt Roasting-leaching Mechanism Of Rare Earth Concentrates

Low-grade uncommon earth listen is commonly leached via high-temperature sulfuric acid roasting,which will produce"three wastes"and pollute the environment.Sodium salt roasting(sodium carbonate roasting)has the benefits of easy operation,low acid consumption,and little environmental pollution.In latest years,microwave-assisted heating decomposition of uncommon earth listen has proven benefits of excessive pace and efficiency.Therefore,the manner of“microwave sodium roasting and high-pressure leaching”used to be adopted to decompose Bayan Obo's low-grade uncommon earth listen in this paper.Through XRD,SEM-EDS,FT-IR,TG,ICP,and different detection methods,the impact of check stipulations on the decomposition method of uncommon earth listen was once investigated.At the equal time,the evaluation of the dynamics of sodium roasting and high-pressure acid leaching of uncommon earth listen used to be carried out.Compared with the traditional heating decomposition process,it affords theoretical practise for the manufacturing method of uncommon earth concentrate.The outcomes of the roasting check of uncommon earth listen confirmed that the first-class stipulations of microwave roasting have been as follows:roasting temperature 450?,roasting time 90min,sodium carbonate ratio 20%,and loss price of15.5%.The microwave roasting kinetics calculation effects of uncommon earth pay attention confirmed that from 350?to 550?,the foremost response was once the decomposition of bastnaesite and the response of decomposition manufacturing and sodium carbonate,the obvious activation electricity(E_a)used to be 14.55Kj/mol,and the mechanism characteristic was once A₃ function,which was once regular with the random nucleation model.From 550?to 630?,the major response used to be the response of monazite and sodium carbonate,the mechanism feature was once D₁function,and the obvious activation strength(E_a)used to be 65.43Kj/mol,which used to be constant with the one-dimensional diffusion model.The outcomes of traditional calcination kinetics confirmed that from 350?to 440?,the decomposition of bastnaesite used to be the most important process,and the apparent activation strength(E_a)was once 56.14Kj/mol,and the mechanism feature was once F1=-ln(1-?),which was once steady with the random nucleation model.From 440?to 524?,the response used to be typically REFO and Na₂CO₃,the mechanism feature was once F1=[-ln(1-?)]^1/3,the obvious activation electricity(Ea)used to be 65.43Kj/mol,which is constant with the one-dimensional diffusion model.From 524?-613?,monazite and sodium carbonate had been generally reacted,and the mechanism feature was once F1=-ln(1-?),and the obvious activation strength(E_a)was once 27.46Kj/mol,which was once steady with the random nucleation model.From 613?to 680?,the decomposition response was once on the whole carbonate,the mechanism characteristic was once F1=[-ln(1-?)]^1/3,the obvious activation power(E_a)used to be17.05Kj/mol,which conformed to the one-dimensional diffusion model.At 680?to757?,the response was once commonly a hint of fluorophosphate and sodium carbonate,the mechanism feature was once D₃ function,the obvious activation electricity(E_a)was once 48.04Kj/mol,in line with the third-dimensional diffusion(spherically symmetric)model.Compared with traditional roasting,the obvious activation strength of microwave roasting decreased.Pressurized acid leaching was performed under the optimal microwave roasting conditions,and it was found that the leaching rate was the highest at 90.8%under the conditions of leaching temperature of 75?,leaching time of 50min,leaching hydrochloric acid concentration of 7mol/L,and leaching liquid-solid ratio of 10ml/g;The calculation results of high pressure acid leaching reaction kinetics show that when the leaching temperature is 40?-60?,the apparent activation energy Ea is16.48Kj/mol,and the mechanism function is ln(1-x)/3+(1-x)^-1/3-1=kt,controlled by the mass transfer and diffusion reaction at the product layer interface;when it is 75?-125?,its apparent activation energy is 0.52Kj/mol,and the mechanism function is 1-(1-x)^1/3=kt,the reaction is mainly controlled by the chemical reaction.