Abstract: An acid treatment, in a liquid medium, of a solid containing a halophosphate and a rare earth compound is described. Further described, is the addition of a base to the medium obtained previously and separation of a solid phase from a liquid phase; mixing and calcination of the solid obtained previously with an alkaline solid compound; redispersing the calcined product in water, separation of the solid product from the suspension obtained in the preceding step; dispersing this solid in water and acidification of the dispersion and separation of the solid from this dispersion.

Abstract: An acid treatment, in a liquid medium, of a solid containing a halophosphate and a rare earth compound is described. Further described, is the addition of a base to the medium obtained previously and separation of a solid phase from a liquid phase; mixing and calcination of the solid obtained previously with an alkaline solid compound; redispersing the calcined product in water, separation of the solid product from the suspension obtained in the preceding step; dispersing this solid in water and acidification of the dispersion and separation of the solid from this dispersion.

Abstract: A method is described for recovering rare earth elements from a solid mixture including a halophosphate and at least one compound of one or more rare earth elements. The method includes: (a) acid etching the mixture; (b) adding a base to bring the pH back up to a value of at least 1.5; (c) etching the solid from step (b) with a solution of soda or potash; (d) acid etching the solid from step (c) until a pH of less than 7 is obtained, resulting in a solid phase and a liquid phase including at least one rare earth salt, and separating the solid phase from the liquid phase.

Abstract: A method is described for recovering rare earth elements from a solid mixture including a halophosphate and at least one compound of one or more rare earth elements. The method includes: (a) acid etching the mixture; (b) adding a base to bring the pH back up to a value of at least 1.5; (c) etching the solid from step (b) with a solution of soda or potash; (d) acid etching the solid from step (c) until a pH of less than 7 is obtained, resulting in a solid phase and a liquid phase including at least one rare earth salt, and separating the solid phase from the liquid phase.

Abstract: Highly pure europium (II) values are produced in high yields by electrolytically reducing an aqueous solution of europium (III) values circulating in the cathode compartment of an electrolytic cell, the electrolytic cell including a graphite cathode and an anode compartment separated from the cathode compartment by a cationic exchange membrane, recovering a solution of europium (II) values from the cathode compartment, and advantageously liquid/liquid extracting the europium (II) values thereform, e.g., with an organic solution of an organophosphorus extractant.

Abstract: Purified barium salts essentially devoid of strontium impurities, e.g., highly pure barium carbonate, are produced by liquid/liquid extracting an aqueous solution of impure barium values with an organic solvent medium which comprises at least one water-insoluble carboxylic acid, phosphonic acid monoester, or substituted 8-hydroxyquinoline extractant. The mixture of extraction is separated into a purified aqueous phase containing the desired barium salt values and an organic phase containing the impurity values sought to be removed.

Abstract: Aqueous nitric solutions of salts of at least one rare earth, and containing contaminating amounts of at least one alkaline earth cation, e.g., calcium, barium and/or radium, are conveniently purified by liquid/liquid extracting same with an organic phase which comprises a polyether extractant for said at least one alkaline earth cation, e.g., a crown ether, and whereby said at least one alkaline earth cation is selectively transferred into said organic phase.

Abstract: Cerium and rare earth values are separated from an aqueous medium comprised thereof, by (i) anodically electrolytically treating such aqueous medium and oxidizing the Ce (III) values therein to Ce (IV) values, (ii) extracting said electrolyzed aqueous medium with a selective organic extractant for said Ce (IV) values, and permitting the extracted medium to separate into an organic phase enriched in Ce (IV) values and a product aqueous phase enriched in rare earth values, (iii) reducing the Ce (IV) values in said organic phase to Ce (III) values and admixing same with an aqueous medium, and (iv) permitting said admixture to separate into an organic phase and a product aqueous phase enriched in Ce (III) values.

Abstract: At least one rare earth value is selectively separated from at least one other rare earth value, by selectively liquid/liquid extracting an aqueous phase comprising the nitrates of said rare earth values with an organic phase which comprises an organic extractant, said organic extractant comprising at least one organophosphinic compound having one of the formulae (I) or (I'): ##STR1## wherein R.sub.1 and R.sub.2, which may be identical or different, are each substituted or unsubstituted alkyl, cycloalkyl, alkoxyalkyl or alkylcycloalkyl radicals, and X is either hydrogen or a cation.