A system for extracting vanadium from a leaching solution containing vanadium chromium silicon and for preparing vanadium pentoxide, and a method therefor, the system comprising, in sequence: an impurity removal system, an extraction system, a reverse-extraction and vanadium precipitation system, a washing system and a calcining system. The method comprises the following steps: removing silicon in a leaching solution by using a silicon removal agent, extracting most of the vanadium to an organic phase by using centrifugal extraction, reverse-extracting the vanadium of a vanadium-rich organic phase by using a mixed solution containing a basic solution and an ammonium salt, and precipitating ammonium metavanadate to obtain an ammonium metavanadate solid, washing and drying, and then calcining at a certain temperature to obtain a low chromium, low silicon, low aluminum and high-purity vanadium pentoxide product.

Provided is a method for efficiently separating and recovering tungsten and other valuable(s) from at least one valuable containing tungsten. The present invention relates to a method for recovering at least one valuable containing tungsten, comprising subjecting a raw material mixture comprising at least one valuable containing tungsten to electrolysis using an electrolytic solution containing at least one alcohol amine to dissolve tungsten in the electrolytic solution, electrodeposit a part of the valuable(s) onto a cathode used for the electrolysis and separate at least one valuable other than the valuable(s) electrodeposited onto the cathode as a residue in the electrolytic solution, and then separating and recovering each of the residue and the valuable(s) electrodeposited onto the cathode.

The present disclosure is directed to novel functionalized ionic liquids (ILs) that are used, for example, for enhanced recovery and separation of rare earth elements from aqueous solutions. The liquids and processes disclosed herein lead to greater separation efficiency, increased stability of separation materials, increased selectivity, and a reduced amount of waste materials.

A method for extracting a rare earth metal from a mixture of one or more rare earth metals, said method comprising contacting an acidic solution of the rare earth metal with a composition which comprises an ionic liquid to form an aqueous phase and a non-aqueous phase into which the rare earth metal has been selectively extracted, wherein the ionic liquid has the formula [Ca.sup.++][X], where [X] represents a phosphinate anion.

A method for extracting a rare earth metal from a mixture of one or more rare earth metals, said method comprising contacting an acidic solution of the rare earth metal with a composition which comprises an ionic liquid to form an aqueous phase and a non-aqueous phase into which the rare earth metal has been selectively extracted, wherein the ionic liquid has the formula [Ca.sup.++][X], where [X] represents a phosphinate anion.

The invention relates to a hydrometallurgical process which makes it possible to selectively recover at least one heavy rare earth metal, i.e. a rare earth metal with an atomic number at least equal to 62, that is in an acidic aqueous phase resulting from the treatment of spent or scrapped permanent magnets. It also relates to a hydrometallurgical process which makes it possible to selectively recover, on the one hand, at least one heavy rare earth metal present in an acidic aqueous phase resulting from the treatment of spent or scrapped permanent magnets and, on the other hand, at least one light rare earth metal, i.e. a rare earth metal with an atomic number at most equal to 61, that is also in this acidic aqueous phase. The invention has in particular an application in the recycling of rare earth metals present in spent or scrapped permanent magnets of the type Neodymium-Iron-Boron (or NdFeB) and, in particular, dysprosium, praseodymium and neodymium, and also in the recycling of samarium present in spent or scrapped permanent magnets of the type samarium-cobalt (or SmCo).

Methods for removing an oxyanion from an aqueous source containing said oxyanion, comprising contacting said aqueous source with an aqueous-insoluble hydrophobic solution containing an oxyanion extractant compound dissolved in an aqueous-insoluble hydrophobic solvent to result in formation of an oxyanion salt of said extractant compound and extraction of said oxyanion salt into said aqueous-insoluble hydrophobic solution, wherein said extraction results in an extraction affinity (D) of said oxyanion of at least 1, wherein D is the concentration ratio of said oxyanion in the organic phase divided by the concentration of said oxyanion in the aqueous phase; wherein said extractant compound has the following composition:

##STR00001##

wherein at least one of R.sup.1-R.sup.10 is or contains a hydrocarbon (R) group containing at least 4, 5, 6, 7, 8, 9, 10, 11, or 12 carbon atoms.

A new extractant which makes it possible to extract both light rare earths and heavy rare earths from an aqueous phosphoric acid solution, likely to be present in this solution, and which is characterised in that it comprises: a compound of formula (I) below: wherein R1 and R2, identical or different, are a hydrocarbon group, saturated or unsaturated, linear or branched, in C6 to C12; R3 is a hydrocarbon group, in C1 to C6, or a hydrocarbon group, saturated or unsaturated, monocyclic, in C3 to C8; R4 and R5, identical or different, are a hydrogen atom or a hydrocarbonate group, saturated or unsaturated, linear or branched, in C2 to C8; anda surfactant. It also relates to the applications of this new extractant: treatment of aqueous solutions from the leaching of natural phosphates by sulphuric acid and aqueous solutions from the leaching of urban minerals by phosphoric acid, in view of making profitable use of the rare earths present in these solutions.

Hydrometallurgical systems, methods, and compositions are described in which organic amine-based lixiviants are utilized in the selective removal of carbonate-forming alkaline earth elements from slag. The resulting processed slag has a reduced tendency to form carbonate salts on environmental exposure, and reduced tendency to fracture due to the formation of such salts. The lixiviant used can be regenerated and recycled for use in subsequent iterations of the process.

Hydrometallurgical systems, methods, and compositions are described in which organic amine-based lixiviants are utilized in the selective removal of carbonate-forming alkaline earth elements from slag. The resulting processed slag has a reduced tendency to form carbonate salts on environmental exposure, and reduced tendency to fracture due to the formation of such salts. The lixiviant used can be regenerated and recycled for use in subsequent iterations of the process.