Extraction of lanthanum and neodymium from leach liquor containing rare earth metals (REMs)

Abstract

Present paper reports the systematic scientific studies for extraction of lanthanum (La) and neodymium (Nd) from chloride solution containing rare earth metals (REMs). The chloride leach liquor was generated by dissolving rare earth mineral and found to contain 0.53g/L La and 1.01g/L Nd along with other REMs. Initial extraction studies were carried out from a model solution containing La and Nd using 10% Cyanex 272 diluted in kerosene along with 2% isodecanol (ID) as phase modifier. Various process parameters viz. effect of pH, time, O/A ratio, loading capacity, etc. were optimized for maximum extraction. More than 97% La and Nd were extracted at an equilibrium pH of 3.3 and 2.7, respectively at phase ratio (O/A) 1:1 and mixing time of 5min in two stages. 10% HCl was used to strip La as well as Nd from the loaded extractant. Moreover, 99.99% separation of La and Nd could also be achieved by stripping the loaded organic phase with pure Nd scrub solution. The optimum condition for extraction was validated with the actual solution. The result revealed that 99.49% La and 95.04% Nd can be extracted in 5min at an equilibrium pH of 3.3 and 2.7, respectively at phase ratio 1:1.