Vanadium, separation from uranium

Vanadium and phosphate and molybdate have been separated from uranium in carbonate solutions by anion exchange. The Impurities are adsorbed on the resin together with uranium and eluted with a 10 NSgCO solution. Uranium Is eluted with a 5 ... 

Determination of uranium with cupferron Discussion. Cupferron does not react with uranium(VI), but uranium(IV) is quantitatively precipitated. These facts are utilised in the separation of iron, vanadium, titanium, and zirconium from uranium(VI). After precipitation of these elements in acid solution with cupferron, the uranium in the filtrate is reduced to uranium(IV) by means of a Jones reductor and then precipitated with cupferron (thus separating it from aluminium, chromium, manganese, zinc, and phosphate). Ignition of the uranium(IV) cupferron complex affords U308. 

The organic amine extractants are the most commonly used anion exchangers. Secondary amines have been used to recover uranium from leach liquors (GlO) secondary and tertiary amines to recover molybdenum from uranium mill circuits (L13) a primary amine, diethylenetriamine-penta-acetic acid (DTPA) to extract cerium group lanthanides (B6) tri-,V-butylamine-3-methyl-2-butanonc to separate yttrium and rare earth nitrates (G13) tricaprylyl amine (Alamine 336) and methyltrioctyl-ammonium salt (Aliquat 336) to recover vanadium from acidic solutions (A3) and Aliquat 336 to extract vanadium from slightly acidic or alkaline leach liquor (S36). 

Carnotite may be fused Avith potassium hydrogen sulphate and the residue extracted with Avater. From the solution the double sulphates of potassium AAuth uranium and vanadium may be obtained by crystallisation. These are reduced by means of zinc and sulphuric acid, and the vanadium precipitated from the solution by means of ammonia and ammonium carbonate. Ammonium diuranate separates from the filtrate on boiling. ... 

An alkali phosphate jrrecipitates yellow uranyl hydrogen phosphate, UO2HPO4, or in presence of an ammonium salt, uranyl ammonium phosphate, UO2NH4PO4 (see p. 330) uranium may be qualitatively separated from chromium and vanadium by this means. -... 

Efficient and selective cation chromatographic separations are possible with an ethylenediammonium tartrate eluent at pH 4.5 and sulfosalicylic acid added to the sample before injection. At pH 4.5 zinc(Il) can be chromatographed without interference from a 20-fold excess of thorium(IV), vanadium(IV), or uranium(Vl), or from a 100-fold excess of iron(lll) when sulfosalicylic acid is added to the sample [14]. 

The meta-elements of Crookes anticipated the idea of isotopes. The most readily available sources of separated stable isotopes are lead 206 from uranium minerals and lead 208 from thorium minerals, and it is interesting enough that before 1910 several successful chemical separations of radioactive isotopes of the same element were reported, involving both thorium 230 (ionium) and lead 210 (radium D). In otir opinion, this can only be due to kinetically metastable chemical nonequivalency in the mixture, for instance, due to colloidal or oligomeric complexes. The valuable conclusion of this story is that the chemical similarity of trivalent rare earths is so striking that doubts have been expressed whether they deserved more than one place in the Periodic Table, a situation isotopes later had to accept. Such a doubt has never been expressed for any other elements, not even for a pair of elements like vanadium and chromium, which were confused at the time of their discovery (7). Nevertheless, studies based on the possibility of metaelements continued rather late for instance, Debierne attempted to separate neo-radium from conventional radium 226 and to perform nuclear reactions on charcoal cooled with liquid helium (77). 

This process coextracts molybdenum, vanadium, and zirconium, but uranium can be separated from these elements by using a selective back-extraction process into the aqueous phase. For example, sodium chloride will strip uranium, while carbonate will remove uranium and molybdenum. This is relevant if, for example, the uranium will be quantified by titration (see below). 

The uranium anion present in carbonate solutions is [U02(C03)8] and this is associated with few other impurity anions. Absorption capacities as high as 100 to 200 mg/g of dried resin have been obtained on Amberlite IRA-400 2 and Dowex I , under conditions where competing anionic impurities such as phosphate and aluminate ions have only absorbed to an insignificant extent. The resin capacity, in both cases, is greatest at low sodium carbonate concentrations. Vanadate ion absorption can take place to an appreciable extent when vanadium is present in the carbonate leach liquor from the ore. It is, however, readily separated from the uranium, e.g. by a preliminary elution with a saturated solution of sulphur dioxide. This removes the vanadium from the resin by reducing it to a lower valency state. 

Electrochemical methods. Hie electrolysis of dilute sulfuric acid solutions with a mercury cathode results In the quantitative deposition of Cr, Fe, Co, Nl, Cu, Zn, Qa, Oe, Mo, Rh, Pd, Ag, Cd, In, Sn, Re, Ir, Pt, Au, Hg, and T1 In the cathode. i Arsenic, selenium, tellurium, osmium, and lead are quantitatively separated from the electrolyte, but are not quantitatively deposited In the cathode. Manganese, ruthenium, and antimony are Incompletely separated. Uranium and the remaining actinide elements, rare earth elements, the alkali and alkaline eeu th metals, aluminum, vanadium, zirconium, niobium, etc. remain In solution.Casto and Rodden and Warf— have reviewed the effects of many variables In the electrolytic separation of the above-named elements from uranium. According to Rodden and Warf optimum conditions for the purification of uranium In sulfuric acid solutions with a mercury cathode are electrolyte volume,... 

A mercury cathode finds widespread application for separations by constant current electrolysis. The most important use is the separation of the alkali and alkaline-earth metals, Al, Be, Mg, Ta, V, Zr, W, U, and the lanthanides from such elements as Fe, Cr, Ni, Co, Zn, Mo, Cd, Cu, Sn, Bi, Ag, Ge, Pd, Pt, Au, Rh, Ir, and Tl, which can, under suitable conditions, be deposited on a mercury cathode. The method is therefore of particular value for the determination of Al, etc., in steels and alloys it is also applied in the separation of iron from such elements as titanium, vanadium, and uranium. In an uncontrolled constant-current electrolysis in an acid medium the cathode potential is limited by the potential at which hydrogen ion is reduced the overpotential of hydrogen on mercury is high (about 0.8 volt), and consequently more metals are deposited from an acid solution at a mercury cathode than with a platinum cathode.10... 

The application of the Chelex 100 resin separation and preconcentration, with the direct use of the resin itself as the final sample for analysis, is an extremely useful technique. The elements demonstrated to be analytically determinable from high salinity waters are cobalt, chromium, copper, iron, manganese, molybdenum, nickel, scandium, thorium, uranium, vanadium, and zinc. The determination of chromium and vanadium by this technique offers significant advantages over methods requiring aqueous final forms, in view of their poor elution reproducibility. The removal of sodium, chloride, and bromide allows the determination of elements with short and intermediate half-lives without radiochemistry, and greatly reduces the radiation dose received by personnel. This procedure was successfully applied in a study of... 

The contactor finds extensive use where high performance phase separation and countercurrent extraction or washing in the one unit are required. Particularly important applications are the removal of acid sludges from hydrocarbons, shown in Figure 13.40, hydrogen peroxide extraction, sulphonate soap and antibiotics extraction, the extraction of rare earths such as uranium and vanadium from leach liquors, and the washing of refined edible oils. 

A general method for the separation of vanadium from arsenic, molybdenum, phosphorus, chromium, uranium, tungsten, and silicon, consists in precipitating these metals as their respective lead salts and digesting the precipitate with potassium carbonate, whereupon all the lead salts are decomposed with the exception of the lead vanadate.5... 

The use of organophosphorus acids, such as di(2-ethylhexyl)phosphoric acid (D2EHPA di(2-ethylhexyl) monohydrogen phosphate 2 R = C4H9CH(Et)CH2), is now well established in the recovery of base metals. This reagent has found commercial application in the separation of cobalt from nickel,67 68 the separation of zinc from impurities such as copper and cadmium,69 the recovery of uranium,68 beryllium70 and vanadium,71 and in separations involving yttrium and the rare-earth metals.72 73... 

Recovery of vanadium with peroxygens involves both oxidation and com-plexation. In solution, conversion of lower oxidation states into vanadium(V) allows separation by solvent extraction (Figure 6.18).269 This chemistry can be used for vanadium by-products in uranium extractions. With hydrogen peroxide, vanadium(IV) is not oxidized in acidic solution, but rather in alkaline conditions, e.g. 60 °C at pH 9 (Figure 6.19).270 Use of excess hydrogen peroxide readily forms peroxo complexes and this is of value in selective dissolution of vanadium from secondary sources. 

Fundamental studies have been reported using the cationic liquid ion exchanger di(2-ethylhexyl) phosphoric acid in the extraction of uranium from wet-process phosphoric acid (H34), yttrium from nitric acid solution (Hll), nickel and zinc from a waste phsophate solution (P9), samarium, neodymium, and cerium from their chloride solutions (12), aluminum, cobalt, chromium, copper, iron, nickel, molybdenum, selenium, thorium, titanium, yttrium, and zinc (Lll), and in the formation of iron and rare earth di(2-ethylhexyl) phosphoric acid polymers (H12). Other cationic liquid ion exchangers that have been used include naphthenic acid, an inexpensive carboxylic acid to separate copper from nickel (F4), di-alkyl phosphate to recover vanadium from carnotite type uranium ores (M42), and tributyl phosphate to separate rare earths (B24). 

The frequent occurrence of vanadium in uranium minerals renders the separation of these two metals of importance. One method in use is based on the solubility of uranyl nitrate in ether, %vhilst vanadic and also molybdic and tungstic acids are insoluble. A solution containing these substances may therefore be evaporated to drjmess, and the uranyl salt extracted from the residue with ether. Another method depends upon the fact that uranyl nitrate is readily soluble, whilst vanadium compounds are insoluble, in acetic acid of 95 per cent, strength to which nitric acid has been added in the proportion 1 20. ... 

A series of processes have been patented for the separation of vanadium and uranium by anion-exchange from sodium carbonate solutions resulting from carbonate leaching of carnotite ore. None of them, however, are believed to be operated commercially. Three methods of operation are proposed with a strong base resin. These are (a) selective elution of uranium followed by elution of vanadium, (b) selective elution of vanadium followed... 

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