REE Recovery Research Articles

Recovery of rare-earth elements from nitric acid solutions by fullerene black impregnated with diphenyl(dibutylcarbamoylmethyl)phosphine oxide

The distribution of microamounts of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y nitrates between aqueous HNO3 solutions and fullerene black impregnated with diphenyl(dibutylcarbamoylmethyl)phosphine oxide (L) was studied. The influence exerted on the efficiency of REE recovery by the HNO3 concentration in the aqueous phase and concentration of L in the sorbent phase was examined. The degree of REE recovery increases on adding HClO4 to the aqueous phase.

Extraction properties of polyfunctional P,N-containing podands with diphenylphosphorylacetamide terminal groups in nitric acid solutions

The extraction of HNO3 and microamounts of U(VI), Th(IV), Sc(III), and REE(III) nitrates from HNO3 solutions with dichloroethane solutions of phosphorus-containing podands containing two terminal Ph2P(O)CH2C(O)NH groups linked by a di-or triethylene glycol chain was studied, and the stoichiometry of the extractable metal complexes was determined. The compounds extract the metal ions from nitric acid solutions more efficiently than does (dibutylcarbamoylmethyl)diphenylphosphine oxide. With increasing length of the polyethylene glycol chain, the extraction of HNO3 increases, but the degree of recovery of REE(III) ions from HNO3 solutions of the concentration exceeding 3 M decreases.

Partitioning of High-Level Waste with an Extractant Based on Chlorinated Cobalt Dicarbollide and Dibutylphosphoric Acid Zirconium Salt

A new extractant allowing full partitioning of high-level waste was developed. It consists of chlorinated cobalt dicarbollide, dibutylphosphoric acid zirconium salt, and polyethylene glycol, dissolved in a polar diluent, mononitrobenzotrifluoride. This extractant recovers from the Purex process raffinate REE, TPE, Cs, Sr, Mo, and Zr. The component ratio ensuring maximal recovery of REE and TPE was found. The majority of the above-mentioned elements are extracted by the cation-exchange mechanism, with the recovery increasing as the aqueous phase acidity is decreased. The composition of the extractable species and the stoichiometry of extraction exchange reactions with REE and TPE were studied.

Radium Institute Research on Actinide Separation from High-Level Waste (Review)

Development of efficient technologies for recovery of long-lived radionuclides from high-level wastes (HLW) is urgent for implementation of the promising management methods (transmutation and disposal), as well as for existing practice of HLW management. In Russia at “Mayak” radiochemical plant since 1996 there has been in operation the industrial facility UE-35 which provides the recovery of cesium and strontium from HLW. The next stage is aimed at development and implementation of actinide separation technology from HLW. For this purpose the following four processes are studied and tested: processes based on chlorinated cobalt dicarbollide (ChCoDiC-process), isoamyldialkyl-phosphine oxide (POR-process), diphenyldibutylcarbamoylphosphine oxide (modified TRUEX-process) and mixture of ChCoDiC, carbamoylphosphine oxide (CMPO) and polyethylene glycol (PEG) (UNEX-process). After comprehensive study of extraction, physico-chemical and operational properties of selected extraction systems, testing of processes was conducted at test facilities with the use of actual or simulated HLW. Mixer-settlers and centrifugal contactors were used as extraction equipment in these tests. The test results show that the ChCoDiC-process can afford recovery of transplutonium and rare-earth elements (TPE and REE) from HLW and separation of them into fractions. POR-process and modified TRUEX-process enable to recover from HLW uranium, neptunium, plutonium, TPE, REE and technetium with the possibility for production of individual fractions. UNEX-process permits to attain simultaneous recovery of actinides, REE, cesium and strontium from HLW. During tests the potentialities of UNEX-process for obtaining such fractions as cesium, cesium+strontium and actinides+REE at stripping stage were demonstrated as well.

Platinum group metals

This paper investigates the recovery of rare earth elements (REEs, mainly lanthanum and cerium) from spent fluid catalytic cracking (FCC) catalysts via the hydrometallurgical processes of leaching and liquid-to-liquid extraction. The maximum leaching efficiency (99.3% for REEs) was achieved under the following conditions: 2 mol/L HCl, a solid-to-liquid (S/L) ratio of 1:10, leaching at 60 °C for 2 h, and 2 h of roasting at 750 °C prior to leaching. Because the main impurity element in the leachate was aluminum, the extractions of REEs and aluminum using di-2-ethylhexyl phosphoric acid (D2EHPA) and 2-ethylhexylphosphonic mono-2-ethylhexyl ester (HEHEHP) under different conditions were compared. The results indicated that D2EHPA and HEHEHP exhibited large extraction differences for REEs but small extraction capacity differences for aluminum. Based on the analysis of the experiments, the optimum extraction conditions for REEs were determined to be 0.5 mol/L D2EHPA, equilibrium pH = 2.5, ambient temperature and then stripping with 2 mol/L HCl. The overall REEs recovery efficiency was 62.88%.