Cleaner production of rare earth elements from phosphorus-bearing sulfuric acid solution of vein deposit monazite

In the present study, the recovery of rare earth elements (REEs; viz. cerium, lanthanum, and yttrium) from sulfate leach liquor of vein deposit Korean monazite has been investigated using the solvo-chemical techniques. The dissolved phosphorus (373 mg L-1), which may significantly affect the products' purity, was selectively removed using the benzyl-di-methyl amine (BDMA). The logarithmic distribution vs. BDMA concentration along with spectral analysis of the organic phases revealed the formation of extracted species (3[BDMA]center dot[H3PO4]) over bar. The quantitative removal of phosphorus was achieved in three stages of counter-current extraction (CCE) under the organic-to-aqueous (O:A) ratio of 1.0:1.5, leaving REEs' into the raffinate. Subsequently, Cyanex 923 was employed to selectively extract cerium(IV) from P-depleted solution under the varying parameters of extractant and sulfuric acid concentration, temperature, and O:A ratio. The quantitative extraction of cerium (similar to 99% from 864 mg L-1 feed concentration) showing exothermic nature was achieved at an O:A of 1:2 under three stages of CCE while using 0.15 mg L-1 extractant into organic phase and 1.12 mol L-1 H2SO4 into aqueous phase. Further, the experimental results and spectral analysis of the organic phases could reveal that cerium solvates as <([Ce(SO4)(2)]center dot 2[Cyanex 923]center dot[HSO4-])over bar> species. Cerium was successfully stripped from loaded organic by contacting with a higher concentration of H2SO4 solution (>= 4.0 mol L-1) in presence of 0.1 mol L-1 H2O2, yielding an enriched high-purity solution of 2.54 g L-1 cerium. Lanthanum and yttrium were recovered from the Ce-depleted raffinate by co-precipitation with oxalic acid, forming a mixture of C6La2O12 center dot 10H(2)O and C6Y2O12 center dot 4H(2)O. The study approaches a cleaner production of high-purity REEs for clean energy programs under Sustainable Development Goals. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

This study investigated the recovery of rare earth elements (REEs) from sulfate leach liquor of vein deposit Korean monazite using solvo-chemical techniques. The selective extraction of cerium and removal of phosphorus from the solution were successfully achieved, leading to high-purity REEs for clean energy programs. The study presents a cleaner production approach for sustainable development goals.