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Hālol, India

Reddy B.R.,Rubamin Ltd | Kumar J.R.,Korea Institute of Geoscience and Mineral Resources
Solvent Extraction and Ion Exchange | Year: 2016

Rare earths (REs) recovery and processing becomes most important all over the globe due to their versatile applications in modern life. The present general article discusses REs extraction and possible separation and recovery methods from phosphoric acid media. Leaching studies are discussed followed by two extraction techniques: solvent extraction and solid–liquid extraction. Various extractants such as TOPS 99 (or) D2EHPA, Cyanex 272, PC 88A were tested for REs extraction and separation. Three resins, Tulsion T-PAR, CH-96, and CH-93, as well as impregnated TOPS 99 were utilized for solid–liquid extraction studies. © 2016 Taylor & Francis

Kim J.S.,Korea Institute of Geoscience and Mineral Resources | Kumar B.N.,Indian Institute of Chemical Technology | Radhika S.,Indian Institute of Chemical Technology | Kantam M.L.,Indian Institute of Chemical Technology | And 2 more authors.
International Journal of Mineral Processing | Year: 2012

In this paper, solvent extraction of mixture of rare-earths (Sm(III), Gd(III), Dy(III) and Y(III)) from chloride solutions using acidic, neutral and basic type extractants and their mixtures has been investigated. The main objective of the work was to select a suitable solvent extractant system for the separation of mixture of rare-earths using organophosphoric acid (TOPS 99), phosphonic acid (PC 88A), phosphinic acid (CYANEX® 272), monothiophosphinic acid (CYANEX® 302), phosphine oxide (CYANEX® 923, CYANEX® 921) and amine based (ALAMINE® 336, ALIQUAT™ 336) extractants. The composition of the synthetic mixture of rare-earths was Sm - 1.835 g/L, Gd - 0.862 g/L, Dy - 0.303 g/L, Y - 0.589 g/L which was prepared according to the leach liquor of the Korean domestic ore. From the effect of aqueous phase acidity and extractant concentration on the extraction efficiency of rare-earths, PC 88A (0.1 mol/L) considered as better extractant with high separation factor for Dy-Y pair with Sm-Gd pair. Mixture of extractants has shown no significant effect on the separation factors of rare-earths than individual extractants. © 2012 Elsevier B.V.

Radhika S.,Indian Institute of Chemical Technology | Nagaphani Kumar B.,Indian Institute of Chemical Technology | Lakshmi Kantam M.,Indian Institute of Chemical Technology | Ramachandra Reddy B.,Indian Institute of Chemical Technology | Ramachandra Reddy B.,Rubamin Ltd
Hydrometallurgy | Year: 2011

TOPS 99, an equivalent to di-2-ethylhexyl phosphoric acid has been employed for the solvent extraction and separation of a mixture of rare-earths (four light rare-earths (LREs) La, Ce, Pr, Nd, and seven heavy rare-earths (HREs) like Tb, Dy, Y, Ho, Er, Yb and Lu) into some fractions from phosphoric acid solutions. From the acid and extractant effects, 0.1 and 1 M TOPS 99 were suitable for the separation of a mixture of REs into three concentrates at 3 M acid, which is similar to wet phosphoric acid solutions (WPA). McCabe-Thiele extraction isotherm predicts the separation of Yb + Lu at an aqueous-to-organic (A/O) phase ratio of 2 in three stages using 0.1 M TOPS 99. Counter-current batch extraction simulation (CCES) of Yb and Lu at an A/O of 2 resulted in a raffinate containing 3.6 mg/L of Yb + Lu, corresponding to an extraction efficiency of 91.9%, whereas other five HREs loss was about 6.7%. Stripping of Yb and Lu as per the predictions of McCabe-Thiele plot from loaded organic (LO) was selected at O/A phase ratio of 3 with 4 M HCl and counter-current stripping simulation studies resulted 100% stripping efficiency. From the Yb + Lu raffinate, remaining five HREs were extracted about 94.4% with 1 M TOPS 99 at an A/O ratio of 3 in three stages. The LRE (Pr and Nd) co extraction is 9.8%. Quantitative stripping of HREs from LO is achieved with 7 M HCl at an O/A ratio of 3 in two stages. Finally, a process flowsheet was presented for the separation of rare-earths into three groups, two HRE fractions (Yb + Lu and Tb, Dy, Ho, Y, Er) and one LRE fraction from 3 M phosphoric acid. © 2011 Elsevier Inc. All rights reserved.

Kumar B.N.,Indian Institute of Chemical Technology | Radhika S.,Indian Institute of Chemical Technology | Kantam M.L.,Indian Institute of Chemical Technology | Reddy B.R.,Indian Institute of Chemical Technology | Reddy B.R.,Rubamin Ltd
Journal of Chemical Technology and Biotechnology | Year: 2011

BACKGROUND: In this work, the solid-liquid extraction of terbium from phosphoric acid solutions using solvent-impregnated resin containing TOPS 99, an equivalent of di-2-ethylhexyl phosphoric acid, has been investigated. The parameters studied include equilibration time, acid concentration, amount of resin, metal concentration, kinetics, temperature, loading, elution, regeneration and recycling. RESULTS: FT-IR results confirm the physical interaction of the extractant with the resin. The extraction of terbium with TOPS 99 impregnated Amberlite XAD 4 resin was acid dependent and transfer of metal follows a cation exchange mechanism. The loading capacity of TOPS 99-impregnated resin for terbium was calculated to be 23.8 mg g -1 resin. Controlling mechanism of the adsorption was found to be a chemical reaction following pseudo-second-order kinetics. The endothermic nature of extraction was confirmed by temperature studies. Among the various eluants studied, H 2SO 4 was the best. Regeneration and recycling of the resin indicated the resin can be used for continuous cycles. CONCLUSIONS: Terbium was successfully extracted from phosphoric acid using TOPS 99 extractant impregnated into Amberlite XAD4 with a maximum loading of 23.8 mg g -1 resin and fully recovered with 1 mol L -1sulfuric acid. The resin was subjected to seven cycles of extraction and elution without any loss of performance. Further studies showed that terbium could be separated from lutetium. © 2010 Society of Chemical Industry.

Raju B.,Indian Institute of Chemical Technology | Kumar J.R.,Korea Institute of Geoscience and Mineral Resources | Lee J.-Y.,Korea Institute of Geoscience and Mineral Resources | Kwonc H.-S.,University of Suwon | And 3 more authors.
Journal of Hazardous Materials | Year: 2012

The solvent extraction and precipitation methods have been used to develop a process to separate platinum and rhodium from a synthetic chloride solutions containing other associated metals such as (mg/L): Pt-364, Rh-62, Al-13880, Mg-6980, Fe-1308 at <1M HCl acidity. At pH 3.4, the quantitative precipitation of Al and Fe was achieved using 10wt% Na 3PO 4·12H 2O, with ~4% loss of Pt and Rh due to adsorption phenomenon. The selective separation of platinum was carried out with 0.01M Aliquat 336 (a quaternary ammonium salt) at an aqueous to organic ratio (A/O) of 3.3 in two stages. Stripping of Pt from loaded organic (LO) at O/A ratio 6 with 0.5M thiourea (tu) and HCl indicated that ~99.9% stripping efficiency. In stripping studies, needle like crystals of Pt were found and identified as tetrakis (thiourea) platinum (II) chloride ([Pt(tu) 4]Cl 2). The selective precipitation of rhodium was performed with (NH 4) 2S from platinum free raffinate with a recovery of >99%. © 2012 Elsevier B.V..

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