Uranium sulphate

Uranous oxide is only difficultly soluble in hydrochloric and sulphuric acids, even when concentrated. With the latter acid, insoluble uranium sulphate is formed. It readily dissolves, however, in dilute nitric acid forming uranyl nitrate it is also soluble in aqua regia. The amounts of the oxide dissohdng in these acids in a given time vary widely with the mode of preparation of the oxide. 

Uranium Sulphate, U(S0j)3.nH20.—The anhydrous uranous sulphate has not been prepared, but an extraordinarily large number of hydrates is known. Salts containing 1, 2, 3, 4, 5, 6, 7, 8, and 9 molecules of w-ater have been described, and of these the di-, tetra-, octa-, and nona-hydrates are stable. The actual relation of these hydrates to one another is difficult to determine, as they undergo hydrolysis to a considerable extent when in solution, and the tetra-and octa-hydrates, at least, show a marked tendency to remain in a metastable condition at temperatures far removed from the transition-point between the two phases. Solubility determinations indicate that this transition-point is in the neighbourhood of 20° C., but it has been shown that the octahydrate wffien heated in absence of air changes into the tetrahydrate at 68° to 87° C. w hen the former hydrate is in a state of metastable equilibrium. 

On the oxidized side of a mineralized roll front there is a zone of mobilization most typically marked by high concentrations of uranium, sulphate, alkalinity and total dissolved solids (Fig. 9). A decrease in these parameters on the reduced side of the front implies precipitation between wells. 

With the exception of iron(II) and uranium(IV), the reduced solutions are extremely unstable and readily re-oxidise upon exposure to air. They are best stabilised in a five-fold excess of a solution of 150g of ammonium iron(III) sulphate and 150 mL of concentrated sulphuric acid per litre [approximately 0.3M with respect to iron] contained in the filter flask. The iron(II) formed is then titrated with a standard solution of a suitable oxidising agent. Titanium and chromium are completely oxidised and produce an equivalent amount of iron(II) sulphate molybdenum is re-oxidised to the Mo(V) (red) stage, which is fairly stable in air, and complete oxidation is effected by the permanganate, but the net result is the same, viz. Mo(III)- Mo(VI) vanadium is re-oxidised to the V(IV), condition, which is stable in air, and the final oxidation is completed by slow titration with potassium permanganate solution or with cerium(IV) sulphate solution. 

Large amounts of chloride, cobalt(II), and chromium(III) do not interfere iron(III), nickel, molybdenum)VI), tungsten(VI), and uranium(VI) are innocuous nitrate, sulphate, and perchlorate ions are harmless. Large quantities of magnesium, cadmium, and aluminium yield precipitates which may co-precipitate manganese and should therefore be absent. Vanadium causes difficulties only... 

Sulphuric acid is not recommended, because sulphate ions have a certain tendency to form complexes with iron(III) ions. Silver, copper, nickel, cobalt, titanium, uranium, molybdenum, mercury (>lgL-1), zinc, cadmium, and bismuth interfere. Mercury(I) and tin(II) salts, if present, should be converted into the mercury(II) and tin(IV) salts, otherwise the colour is destroyed. Phosphates, arsenates, fluorides, oxalates, and tartrates interfere, since they form fairly stable complexes with iron(III) ions the influence of phosphates and arsenates is reduced by the presence of a comparatively high concentration of acid. 

Z 1 Niobium 1 Nitrate 1 Osmium 73 a. I Perchlorate Phenols u a o Platinum o 0. 1 5 u 1 Rhodium 1 Rubidium Ruthenium Scandium 1 Selenium Silver I Sodium 1 Strontium 1 Sulphate Sulphides, organic Sulphur dioxide 1 Tantalum 1 Tellurium 1 Thallium Thorium e H 1 Titanium a u ab a 1- I Uranium 1 Vanadium 1 Yttrium 1 Zinc Zirconium... 

Gascoyne M, Schwarcz HP (1982) Carbonate and sulphate precipitates. In Uranium series disequilibrium Applications to enviromnental problems (1st edn). Ivanovich M, Harmon RS (eds) Calrendon Press, Oxford, p 268-301... 

In all 28 parameters were individually mapped alkalinity, aluminum, antimony, arsenic, barium, boron, bromide, cadmium, calcium, chloride, chromium, conductivity, copper, fluoride, hardness, iron, lead, magnesium, manganese, nitrate, pH, potassium, selenium, sodium, sulphate, thallium, uranium, and zinc. These parameters constitute the standard inorganic analysis conducted at the DENV Analytical Services Laboratory. 

Crystallisation was one of the earliest methods used for separation of radioactive microcomponents from a mass of inert material. Uranium X, a thorium isotope, is readily concentrated in good yield in the mother liquors of crystallisation of uranyl nitrate (11), (33), (108). A similar method has been used to separate sulphur-35 [produced by the (n, p) reaction on chlorine-35] from pile irradiated sodium ot potassium chloride (54), (133). Advantage is taken of the low solubility of the target materials in concentrated ice-cold hydrochloric acid, when the sulphur-35 as sulphate remains in the mother-liquors. Subsequent purification of the sulphur-35 from small amounts of phosphorus-32 produced by the (n, a) reaction on the chlorine is, of course, required. Other examples are the precipitation of barium chloride containing barium-1 from concentrated hydrochloric acid solution, leaving the daughter product, carrier-free caesium-131, in solution (21) and a similar separation of calcium-45 from added barium carrier has been used (60). 

The halogenates of chromium, uranium, and manganese.—The double decomposition of chrome alum and barium chlorate, or a soln. of chromic sulphate and potassium chlorate, furnishes a violet liquid containing chromium chlorate,134 which becomes green at 65°. Even at ordinary temp, the soln. smells of chlorine at 100°, chlorine gas is given off and the liquid becomes reddish-yellow—it contains chromic... 

Sulphates. Tim solution of I gin. of uranium acetate in 20 n. ul wain- and 2 to, i ee. of dilute, acetic, acid should not be nlTcrtcd by barium chloride solution. 

For the treatment of camotite several methods are available. The method recommended by the United States Bureau of Mines2 is as follows The ore is leached with concentrated nitric acid at 100° C., neutralised with caustic soda, and barium chloride and sulphuric acid added to the solution to precipitate the radium as barium-radium sulphate. The precipitate settles in three or four days, after which time the clear liquid is decanted into tanks and is treated with excess of boiling sodium carbonate solution in order to precipitate any iron, aluminium and chromium present. The solution now contains sodium uranyl carbonate and sodium vanadate. It is nearly neutralised with nitric acid, and caustic soda is added in sufficient quantity to precipitate the uranium as sodium uranate. After filtering, the remaining solution is neutralised with nitric acid and ferrous sulphate added, whereupon iron vanadate is thrown down. By this method it is claimed that 90 per cent, of the radium, all the uranium, and 50 per cent, of the vanadium in the camotite are recovered. 

Electrometric Methods have been applied for the estimation of vanadium alone and alloyed with other metals, e.g. iron, chromium, uranium. The reduced solution is either gradually oxidised by means of a suitable oxidising agent (potassium permanganate, ammonium persulphate, nitric acid), or the vanadate solution is gradually reduced with ferrous sulphate solution the changes in the E.M.F. of a suitable cell indicate the end point.8... 

Uranium has been determined in process liquids by ion chromatography using an ammonium sulphate sulphuric acid element. Uranium was determined in the eluant. Uranium was determined in the eluate spectrophotometrically at 520 mm as the 4(-2-pyridylazo) resorcinol complex [36],... 

In the accompanying table arc listed a few of the more important types of compounds yielded by those elements. It will be observed that, the maximum valency of the elements with regard to oxygen is numerically equal to six. An interesting link between tellurium a heavy member of the oxygen subdivision—and uranium the last, of the chromium subdivision—is afforded by their union with sulphuric acid to form sulphates of the type M(SO ).>. The heaviest members of both subdivisions exhibit radioactivity. 

Uranium shows an interesting similarity to tellurium in the formation of a sulphate of the type M(S04)2 it also resembles polonium or radium F, the heaviest member of the oxygen group, in being radioactive. 

Uranium, in the uranous compounds in which the element is tetra-valent, appears to be closely allied to thorium, the terminal member of Subgroup IVa. The dioxide, UOg, is isomorphous with thorium oxide, ThOj the sulphates are also isomorphous and are only slightly soluble in water. The oxalates of the two elements are highly insoluble. Most uranous salts are readily soluble. Many other salts of tetravalent uranium and thorium are isomorphous nevertheless the two elements exhibit very considerable differences and can easily be separated. ... 

The mechanically dressed ore is first roasted in order to remove sulphur, arsenic, and other volatile ingredients, and then heated in a reverberatory furnace with sodium carbonate or sodium sulphate. The product is extracted with %varm dilute sulphuric acid, whereupon the uranium passes into solution, whilst the radium remains in the residue witlr calcium, barium, and lead. Tliis residue, which is the starting material for tlie extraction of radium, also contains silica and small quantities of copper, bismutli, arsenic, antimony, iron, aluminium, manganese, zinc, nickel, cobalt, thallium, vanadium, columbium, tantalum, and rare earths. 

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. ... 

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