Application of chromatographic plate theory on the weathered crust elution-deposited rare earth ore with carboxylate

Abstract

To improve the leaching process of rare earth and reduce the impurities in the leachate, the carboxylate ammonium, such as ammonium acetate, ammonium citrate and ammonium tartrate, were selected as lixiviant to compare the effects of concentration, flow rate, pH and temperature on leaching mass process of rare earth and aluminum. Meanwhile, the leaching behaviors of rare earth and aluminum leached by three kinds of carboxylate ammonium were analyzed by chromatographic plate theory. The relationship between the flow rate and height equivalent (HETP) could fit well with the Van Deemter equation and there was an optimal flow rate (uopt) for the leaching of the rare earth and aluminum. Besides, the conditions of carboxylate ammonium lixiviant were optimized. The optimum concentrations of ammonium acetate, ammonium tartrate and ammonium citrate were 15 g/L, 25 g/L and 5 g/L respectively, the leaching flow rate was 0.50 mL/min, the pH value was approximatively 7.00 and the leaching temperature was 293 K to 303 K. At these conditions, the mass transfer efficiencies of three ammonium carboxylates for rare earth and aluminum was in the order of ammonium acetate > ammonium tartrate > ammonium citrate. Moreover, the ammonium acetate could commendably inhibit aluminum ions entering the lixivium.

Effects of Ammonium Salts on Rare Earth Leaching Process of Weathered Crust Elution-Deposited Rare Earth Ores

“…The rare earth leaching solution at different time The clay minerals in weathered crust elution-deposited rare earth ore mainly include halloysite, kaolinite, illite, and montmorillonite. The rare earth elements mainly exist in the ionic or hydration ionic state on the surface of the clay minerals [27]. When clay minerals were placed in a solution environment, rare earth ions and parts of impurity ions were replaced into the solution under the action of the leaching agent.…”