Acid Leaching And Leaching Kinetics Of Rare Earths In Rare Earth Ore

Rare earths are of great importance strategic resources,and high great ores have been largely exploited and have become less and less since the development of global rare earth resources entered the third period.With the unceasing growth of universal rare earths market,it has become significant measure of protecting Chinese power of discourse to rare earths and easing the pressure on global rare earths supply to exploit rare earth mine mud,associated rare earths and other rare earth resources difficult to be utilized.The test sample is rare earth mine mud which is obtained by classification and desliming.Based on the results of process mineralogy,physical and chemical benefication methods to recycle rare earths in rare earth mine mud were carried out according to the characteristics of slime.The effects of of leaching temperature,sulfuric acid concentration and stirring intensity on leaching speed and leaching rate of rare earths were discussed,and the leaching kinetics equation was calculated,at the same time,the liquid-solid ratio,leaching time and other parameter were optimized.The results of process mineralogy show that the REO grade of the test sample is 7.23%.Particularly,the grade at-S?m fraction is 7.34%,and the productivity and distribution rate were about 85%.Rare earths in slime contain and ionic rare earths,and mineral-type rare earths are given priority to hamartite,the main gangue mineral were Argillaceous Hematite-Crandallite clay mixture,in which 59%of REO disseminated.Exploratory test results show that sulfuric acid leaching is a better technology for the recovery of rare earths from this kind of rare earth mine mud.Study on leaching kinetics started from the leaching of hamartite in sulfuric acid system,and the Erare earth mine mud=52.53kJ/mol was obtained by Arrhenius equation on the basis of the effect of temperature on the leaching rate of rare earth,at the same time,according to combining the effect of sulfuric acid concentration and stirring intensity on the leaching rate of rare earth,the kinetic equation of rare earth leaching in sulfuric acid system was obtained:1-?1-??^1/3 = 1.34038×10^-9T⁾2.81736)C^0.52017W^0.36069tThree parameters?temperature,sulfuric acid concentration and stirring intensity?are the key to increase the leaching speed and leaching rate,and the effect of temperature on rare leaching is greatest.On this basis,the leaching process was optimized,and then the optimum conditions of rare earth mine mud leaching were obtained as follow:leaching temperature?90??,sulfuric acid concentration?7.5mol/L?,stirring intensity?400rpm?,liquid-solid ratio?5:1?,auxiliary leaching agent ammonium sulfate concentration?0.25mol/L?,Leaching time?45min?.According to carrying out the stability test under the optimum conditions,the leaching rate of rare earths could reach 91.606%,and the REO grade of leaching residue was reduced to 1.274%.Eventually,the efficient recovery of rare earth resources in slime was realized.