A study of the solubility of yttrium, praseodymium, neodymium, and gadolinium sulfates in the presence of sodium and potassium in sulfuric-phosphoric acid solutions at 20°C

Simultaneous recovery of rare earths and uranium from wet process phosphoric acid using solvent extraction with D2EHPA

“…Fortunately, solubility of REEs in phosphoric acid shows a dramatic difference from that of REEPO 4 in non-phosphate solution. LREEs have far lower solubility in WPA than HREEs, for example, solubility of Y 2 O 3 in WPA is about 48.8 g/L while solubility of La 2 O 3 is about 0.18 g/L (Lokshin et al, 2007). Therefore, evaporation method-a general process for the commercial grade phosphoric acid production was adopted for LREEs enrichment from WPA.…”

“…Since the 1930s, many processes have been proposed for REEs recovery from WPA including crystallization, precipitation, solvent extraction, and ion exchange methods (Habashi, 1985;Wu, 1983). However, due to the high energy consumption of crystallization (Weterings and Janssen, 1985), the impurities involvement, high reagent consumption and phosphorus loss in precipitation processes (Lokshin et al, 2005;Lokshin et al, 2004;Lokshin et al, 2007;Lokshin et al, 2011), the low efficiency of ion exchange (less than 60%) (Reddy et al, 2009;Reddy et al, 2010), these methods did not achieved their industrial applications. Solvent extraction was considered as the most promising method since it is possible to simultaneously recover REEs and U (Beltrami et al, 2014).…”

Recovery of yttrium and lanthanides from sulfate solutions with high concentration of iron and low rare earth content

“…Regarding the REE double sulfate salt precipitation, the quantitative recovery of HREE requires a very high excess of sodium ions. Little detailed information is available on REE double salt precipitation but it seems that the solubility of NaREE(SO 4 ) 2 ,nH 2 O (s) increases with the atomic number of the REE (Lokshin et al, 2005(Lokshin et al, , 2007. To treat these low REE concentration solutions, ion exchange and solvent extraction systems have been extensively studied (Radhika et al, 2010(Radhika et al, , 2011Reddy et al, 2009).…”

Thermodynamics of the Eu(iii)–Mg–SO4–H2O and Eu(iii)–Na–SO4–H2O systems. Part I: solubility experiments and the full dissociation Pitzer model

“…The study by Keyes and James 25 focused on the solubility of Sm(III) in the ternary system Sm 2 (SO 4 ) 3 -Na 2 SO 4 -H 2 O. The authors observed the formation of a hydrated salt in the form of Na 2 Sm 2 (SO 4 ) 4 •2H 2 O(cr) at Na 2 SO 4 concentrations above ∼0.01 M. Some studies with different lanthanides reporting the formation of double salts with Na + are also available in the literature, [25][26][27][28] but they were performed at low Na 2 SO 4 concentrations and did not conclude any solubility information for a supposed Na 2 Ln 2 (SO 4 ) 4 •2H 2 O(cr) phase. The lack of relevant experimental solubility data makes it difficult to understand the behavior of Eu(III) and feed the thermodynamic models used to reproduce and estimate such properties.…”