Leaching Kinetics of Weathered Crust Elution-Deposited Rare Earth Ore with Compound Ammonium Carboxylate

Abstract

Due to the special properties of the ammonium salts, ammonium acetate and ammonium citrate were used to explore the best leaching conditions of rare earth with compound ammonium carboxylate. This paper explored the influence of the molar ratio, ammonium concentration, experimental temperature, and pH of the compound leaching agents on the leaching efficiency of rare earth and aluminum, and it analyzed the leaching process based on the leaching kinetics, which provides a new method for leaching rare earth from the weathered crust elution-deposited rare earth ore. The results showed that under the conditions where the molar ratio of ammonium acetate and ammonium citrate was 7:3 and the ammonium concentration was 0.15 mol/L, the leaching efficiency of rare earth was the highest when the pH of leaching agent was 4.0 and the experimental temperature was 313 K. Meanwhile, when CH3COONH4 and (NH4)3Cit were used to leach rare earth ore, the leaching reaction kinetics equation of rare earth and aluminum were obtained. In the temperature range of 283–323 K, the apparent activation energy of rare earth was 14.89 kJ/mol and that of aluminum was 19.17 kJ/mol. The reaction order of rare earth was 0.98 and that of aluminum was 0.79. The results were in accordance with the shrinking core model and indicate that the concentration of the leaching agent had a greater influence on rare earth than aluminum. This process can reduce the use of ammonium salt, and it is of great significance to extract rare earth elements from weathered crust elution-deposited rare earth ore and improve the utilization rate of resources.

Mesoscopic Process Simulation of In Situ Leaching of Ionic Rare Earth Based on NMRI Technology

“…The wall of the seepage channel is the “surface region,” and the leaching agent exchanges with the rare earth ion adsorbent on the “surface region.” It is assumed that only the rare earth ions represented by yttrium (Y) element are uniformly distributed on the surface region, with a concentration of 0.12 mol/m 2 . Studies on the leaching kinetics of in situ leaching show that [35, 36] mineral ion leaching is a process controlled by surface reaction, which is mainly affected by the exchange rate of leaching agent cation and mineral cation in leaching agent. In this study, magnesium sulphate solution is considered a leaching agent [37], and the chemical reaction equation between magnesium ion and rare earth ion can be expressed as follows: (6) Al 4 Si 4 O 10 OH 8 m ⋅ 2 n RE 3 + s + 3 n Mg 2 + aq ⇄ Al 4 Si 4 O 10 OH 8 m ⋅ 3 n Mg 2 + s + 2 n RE 3 + aq …”

Development Review on Leaching Technology and Leaching Agents of Weathered Crust Elution-Deposited Rare Earth Ores

“…Compared with (NH 4 ) 2 SO 4 , the rare earth leaching rate reached up to 91%. Chai Xiuwei et al [18] explored the effect of compound ammonium carboxylate composed of ammonium acetate and ammonium citrate on the leaching of weathered crust elution-deposited rare earth ores and found that the leaching rate of rare earth can reach 80% at a molar ratio of ammonium acetate to ammonium citrate of 7:3; the ammonium concentration was 0.15 mol/L, pH 4.0, and the temperature was 313 K.…”

Rare Earth Occurrence States of Weathered Crust Elution-Deposited Rare Earth Ores in Southern Yunnan

“…Weathered crust elution-deposited rare earth ores are rich in medium and heavy rare earth elements; thus, they have high economic value and are strategic mineral resources in China [1][2][3]. This mineral was firstly discovered in the Jiangxi province of China, and is mainly located in the Jiangxi, Fujian, Hunan, Guangdong, Guangxi and Zhejiang provinces [4,5].…”