Uranyl sulphide

Ammonium sulphide solution brown precipitate of uranyl sulphide, U02S, soluble in dilute acids and in ammonium carbonate solution. 

Ammonium sulphide gives a brown precipitate of uranyl sulphide, which on prolonged heating decomposes with separation of sulphur and hydrated uranous oxide. 

Gravimetric Estimation.—Many methods for the quantitative determination of uranium have been described, but the follo%ving appear to be the most trustworthy (1) precipitation with ammonia as ammonium diuranate, and ignition to urano-uranie oxide (2) precipitation of uranyl ammonium phosphate by means of ammonium phosphate in presence of ammonium acetate, and ignition of the precipitate to uranyl pyrophosphate and (8) precipitation as uranyl sulphide by means of ammonium sulphide, and ignition to urano-uranie oxide. 

U-bearing minerals and adsorption processes (Salah et al. 2000 Perez del Villar et al. 2000). The vertical and lateral flow of groundwater is responsible for the oxidation and dissolution of primary sulphides, leading to acidic solutions that facilitated the oxidation and dissolution of uraninite. The resulting uranyl cations migrated and precipitated as uranyl minerals, mainly phosphates, silicates, silico-phosphates. In certain local conditions, reduction of these uranyl cations allowed precipitation of coffinite with a high content of P and LREE. Adsorption of uranium, together with P, mainly occurs on Fe-oxyhydroxides, but this kind of uranium retention seems less efficient than the precipitation, at least in the close vicinity to the... 

Uranyl Nitrate. Acquaint yourself with the appearance of uranyl nitrate. Find the solubility products of uranyl nitrate in water and ether in a reference book. What is the reaction of solutions of ammonium sulphide, potassium hexacyanoferratefll), and potassium phosphate with a uranyl nitrate solution What is obtained Write the equations of the reactions. 

Uranium Oxysulphide, U3O2S4 or UO3.2US2, is formed when uranous oxide, urano-uranic oxide, or ammonium uranate is heated in a stream of hydrogen sulphide or carbon disulphide vapour when one of the oxides is heated with a mixture of ammonium chloride and sulphur or when uranyl sulphate is heated in hydrogen or with potassium pentasulphide. It is a greyish-black powder, which is decomposed by nitric acid %vith deposition of sulphur. 

Uranium minerals may be obtained in solution, in a suitable condition for estimation, by the following process. The ore is dissolved in aqua regia, or, if necessary, fused with alkali bisulphate and extracted mth hot hydrochloric acid. After evaporation to drjmess, the residue is taken up with dilute hydrochloric acid, and the solution saturated with hydrogeir sulphide in order to remove any copper, lead, bismuth, arsenic, antimony, or any other metal yielding an insoluble sulphide. The filtrate is concentrated and treated with ammonium carbonate, which precipitates the carbonates of the alkaline earths, iron, and most of the rare earths. The filtrate is neutralised by hydrochloric acid, evaporated to dryness, and the residue ignited to drive off ammonium salts, and then redissolved in dilute acid. The remaining rare earths, and particularly thorium, are next precipitated by the addition of oxalic acid. The filtrate, which contains the uranium in the uranyl condition, may now be precipitated by any of the methods described above. 

Experimental. The general conditions of experiments, and methods of investigations were similar to those described previously.However, extremely precise and reproducible results of crosslinking were achieved owing originally developed device for exposure (Pig in which the specimens may be rotated with chosen rate. Additionally, the selection of UV-sensitizers was ex-tented, and besides diphenyl sulphoxide, also dinaphtyl sulphoxide, methyl - benzyl sulphoxide, bis- p-chloro-phenyl sulphoxide, bis- 2,4-dichlorophenyl sulphoxide, were used. Also, some other compounds were examined, namely diphenyl sulphide and its p-nitro-p-amino- as well o,o-dicarboxy-derivatives, methiomethy-lene-diethyl phosphate and uranyl acetate. 

The structures of the metal, hydrides, and carbides are described in other chapters, as also are the halides MX3, MX4, and MX5. Here we devote sections to certain halide structures peculiar to U, complex fluorides of Th and U, oxides of U, uranyl compounds and uranates, nitrides and related compounds, and conclude with a note on the sulphides of U, Th, and Ce. 

The uranyl ions absorb in a part of the spectrum to which the silicon cells are quite insensitive and where diffuse light contains a large proportion of the incoming solar flux. They fluoresce with yields of 0.3 to 0.6 in glasses (according to chemical composition) and emit closer to the optimum wave-numbers of silicon cells, and in particular of cadmium sulphide mixed with Cu2S or CdTe(9) or binary CdSe for that matter. 

The olf-gases are filtered by conventional means and heat exchanged between them and the ingoing gases, before recompression and make up with additional hydrogen. The water produced in the reaction is allowed to condense and join the water or dilute sodium hydroxide solution used as the pump seal liquid. When sodium hydroxide solution is present, it tends to scrub out the small proportion of hydrogen sulphide arising from the sulphate addition to the uranyl nitrate feed, and so minimize corrosion. 

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