The present invention relates to a process for recovering metals from metal-bearing material, said process comprising the step of contacting the metal-bearing material with condensed phosphoric acid at a temperature of greater than 215° C. and less than 300° C. for a period of time sufficient to at least partially dissolve the metal-bearing material; to provide a leaching solution containing metal ions. The invention is applicable to a range of metals including the rare earth elements, as well as thorium and uranium. The invention is applicable to a range of metal-bearing materials, particularly phosphate minerals such as monazite and xenotime.

A mesoporous organic material which makes it possible to extract, using the liquid-solid extraction technique, the uranium(VI) contained in an aqueous medium including phosphoric acid, with high efficiency and high selectivity for the iron that the medium can likewise contain. The material is likely to be obtained by cross-linking polymerisation of a monomer of formula (I) below, wherein: R.sup.1, R.sup.2 and R.sup.3 are, independently from one another, H, a C.sub.1 to C.sub.12 saturated or unsaturated, linear or branched hydrocarbon group, or a polymerisable group, with the condition that at least one of R.sup.1, R.sup.2 and R.sup.3 is a polymerisable group; R.sup.4 and R.sup.5 are, independently from one another, H or a C.sub.1 to C.sub.8 saturated or unsaturated, linear or branched hydrocarbon group; the cross-linking polymerisation being carried out in the presence of a cross-linking agent and one or more pore-forming agents.

In alternative embodiments, the invention provides processes and methods for the recovery, removal or extracting of, and subsequent purification of uranium from a wet-process phosphoric acid using a continuous ion exchange processing approach, where the uranium is recovered from a phosphoric acid, or a phos-acid feedstock using either a dual or a single stage extraction methodology. In both cases an intermediate ammonium uranyl-tricarbonate solution is formed. In alternative embodiments, in the dual cycle approach, this solution is contacted in a second continuous ion exchange system with a strong anion exchange resin then subsequently recovered as an acidic uranyl solution that is further treated to produce an intermediate uranyl peroxide compound which is ultimately calcined to produce the final uranium oxide product. In alternative embodiments, in the single cycle case, the intermediate ammonium uranyl-tricarbonate solution is evaporated to decompose the ammonium carbonate and produce an intermediate uranium carbonate/oxide solid material. These solids are digested in an acid medium, and then processed in the same manner as the secondary regeneration solution from the dual cycle process to produce an intermediate uranyl peroxide that is calcined to produce a final uranium oxide product.

A mesoporous organic material which makes it possible to extract, using the liquid-solid extraction technique, the uranium(VI) contained in an aqueous medium including phosphoric acid, with high efficiency and high selectivity for the iron that the medium can likewise contain. The material is likely to be obtained by cross-linking polymerisation of a monomer of formula (I) below, wherein: R.sup.1, R.sup.2 and R.sup.3 are, independently from one another, H, a C.sub.1 to C.sub.12 saturated or unsaturated, linear or branched hydrocarbon group, or a polymerisable group, with the condition that at least one of R.sup.1, R.sup.2 and R.sup.3 is a polymerisable group; R.sup.4 and R.sup.5 are, independently from one another, H or a C.sub.1 to C.sub.8 saturated or unsaturated, linear or branched hydrocarbon group; the cross-linking polymerisation being carried out in the presence of a cross-linking agent and one or more pore-forming agents.

In alternative embodiments, the invention provides processes and methods for the recovery, removal or extracting of, and subsequent purification of uranium from a wet-process phosphoric acid using a continuous ion exchange processing approach, where the uranium is recovered from a phosphoric acid, or a phos-acid feedstock using either a dual or a single stage extraction methodology. In both cases an intermediate ammonium uranyl-tricarbonate solution is formed. In alternative embodiments, in the dual cycle approach, this solution is contacted in a second continuous ion exchange system with a strong anion exchange resin then subsequently recovered as an acidic uranyl solution that is further treated to produce an intermediate uranyl peroxide compound which is ultimately calcined to produce the final uranium oxide product. In alternative embodiments, in the single cycle case, the intermediate ammonium uranyl-tricarbonate solution is evaporated to decompose the ammonium carbonate and produce an intermediate uranium carbonate/oxide solid material. These solids are digested in an acid medium, and then processed in the same manner as the secondary regeneration solution from the dual cycle process to produce an intermediate uranyl peroxide that is calcined to produce a final uranium oxide product.

The invention relates to compounds which correspond to the general formula (I) below: ##STR00001## in which: R.sup.1 and R.sup.2 represent, independently of one another, a C.sub.4 to C.sub.12 acyclic hydrocarbon group; R.sup.3 represents H; a C.sub.1 to C.sub.12 acyclic hydrocarbon group with optionally one or more heteroatoms; a C.sub.5 or C.sub.6 cyclic hydrocarbon group; or a 5- or 6-membered heterocyclic group; R.sup.4 represents H or a C.sub.1 to C.sub.12 acyclic hydrocarbon group with optionally one or more heteroatoms; R.sup.5 and R.sup.6 represent, independently of one another, H; a C.sub.1 to C.sub.12 acyclic hydrocarbon group with optionally one or more heteroatoms; a C.sub.5 or C.sub.6 cyclic hydrocarbon group; or a 5- or 6-membered heterocyclic group; on the condition however that R.sup.5 and R.sup.6 do not each represent H. The invention also relates to the uses of these compounds as uranium(VI) ligands, in particular for extracting uranium(VI) from an aqueous solution of sulphuric acid, and also to a method that makes it possible to recover the uranium(VI) present in an aqueous solution of sulphuric acid resulting from the attack of a uranium ore by sulphuric acid and using said the compounds.

A method for extracting uranium (VI) from an aqueous solution including phosphoric acid, which includes placing the aqueous solution 5 in contact with an organic material, followed by separating the aqueous solution and the organic material. The organic material includes a solid polymer substrate impregnated with a compound having the following general formula (I):

##STR00001##

The invention also relates to a method for retrieving uranium (VI) from an aqueous solution including phosphoric acid.

In alternative embodiments, the invention provides processes and methods for the recovery, removal or extracting of, and subsequent purification of uranium from a wet-process phosphoric acid using a continuous ion exchange processing approach, where the uranium is recovered from a phosphoric acid, or a phos-acid feedstock using either a dual or a single stage extraction methodology. In both cases an intermediate ammonium uranyl-tricarbonate solution is formed. In alternative embodiments, in the dual cycle approach, this solution is contacted in a second continuous ion exchange system with a strong anion exchange resin then subsequently recovered as an acidic uranyl solution that is further treated to produce an intermediate uranyl peroxide compound which is ultimately calcined to produce the final uranium oxide product. In alternative embodiments, in the single cycle case, the intermediate ammonium uranyl-tricarbonate solution is evaporated to decompose the ammonium carbonate and produce an intermediate uranium carbonate/oxide solid material. These solids are digested in an acid medium, and then processed in the same manner as the secondary regeneration solution from the dual cycle process to produce an intermediate uranyl peroxide that is calcined to produce a final uranium oxide product.

The application relates to a method for separating iron from an initial liquid organic phase containing uranium and iron, wherein the initial liquid organic phase is contacted with an aqueous solution referred to as aqueous de-ironing solution, whereby the iron passes into the aqueous solution to form a final liquid aqueous phase, and uranium remains in the initial liquid organic phase to form a final liquid organic phase referred to as de-ironed organic phase. The method is characterised in that the aqueous de-ironing solution contains an inorganic acid and uranium, and does not contain iron. The application also relates to a method for extracting uranium from an aqueous solution of an inorganic acid containing uranium and iron.

The invention relates to compounds which correspond to the general formula (I) below:

##STR00001##

in which: R.sup.1 and R.sup.2 represent, independently of one another, a C.sub.4 to C.sub.12 acyclic hydrocarbon group; R.sup.3 represents H; a C.sub.1 to C.sub.12 acyclic hydrocarbon group with optionally one or more heteroatoms; a C.sub.5 or C.sub.6 cyclic hydrocarbon group; or a 5- or 6-membered heterocyclic group; R.sup.4 represents H or a C.sub.1 to C.sub.12 acyclic hydrocarbon group with optionally one or more heteroatoms; R.sup.5 and R.sup.6 represent, independently of one another, H; a C.sub.1 to C.sub.12 acyclic hydrocarbon group with optionally one or more heteroatoms; a C.sub.5 or C.sub.6 cyclic hydrocarbon group; or a 5- or 6-membered heterocyclic group; on the condition however that R.sup.5 and R.sup.6 do not each represent H.