Copper-uranium oxides

Anderson Stresino, 1963 [33] 0.91,1.5 copper uranium oxide none <373... 

Malinin, G. V. et al., Russ. Chem. Rev., 1975, 44, 392-397 Thermal decomposition of metal oxides was reviewed. Some oxides (cobalt(II, III) oxide, copper(II) oxide, lead(II, IV) oxide, uranium dioxide, triuranium octaoxide) liberate quite a high proportion of atomic oxygen, with a correspondingly higher potential for oxidation of fuels than molecular oxygen. 

Strangely enough, a combination similar to the ammonia catalyst, iron oxide plus alumina, yielded particularly good results (32). Together with Ch. Beck, the author found that other combinations such as iron oxide with chromium oxide, zinc oxide with chromium oxide, lead oxide with uranium oxide, copper oxide with zirconium oxide, manganese oxide with chromium oxide, and similar multicomponent systems were quite effective catalysts for the same reaction (33). 

Oxides.—Amongst the simple oxides may be classed —oxide of chromium, oxide of iron, oxide of uranium, oxide of manganese, oxide of zinc, oxide of cobalt, oxide of antimony, oxide of copper, oxide of tin. 

In a much earlier patent, the removal of organics from exhaust gases by oxidation over a supported uranium oxide catalyst was reported by Hofer and Anderson [39]. The catalyst was 4% U3O8 supported on alumina spheres. The authors used the incipient wetness technique to impregnate alumina with uranyl nitrate solution. In this case the catalyst precursors were calcined at 700°C for 3 h to decompose the uranium salt. The use of other uranium compounds as starting materials was mentioned and these included uranyl acetate, uranium ammonium carbonate and uranyl chloride. The alumina-supported catalyst had a surface area of ca 400m g and further added components, such as copper, chromium and iron, were highlighted as efficient additives to increase activity. 

The catalysts were evaluated by exposure to a simulated automobile exhaust gas stream composed of 0.2% isopentane, 2% carbon monoxide, 4% oxygen and a balance of nitrogen. The temperature required to oxidize the isopentane and carbon monoxide was used to compare catalyst performance. The chromium-promoted catalyst oxidized isopentane at the lowest temperature, and a mixed chromium/copper-promoted catalyst proved the most efficient for oxidizing carbon monoxide and isopentane. It is interesting to note that the test rig used a stationary engine with 21 pounds of catalyst. Although the catalyst was very effective it is difficult to envisage uranium oxide catalysts employed for emission control of mobile sources. 

More and more minerals are being found amenable to bacteriological leaching. The copper sulfide minerals, such as chalcopyrite (B31-B33, D22, D24), chalcocite (B35), and tetrahedrite (B32, D21) are among the best studied. The iron sulfide (pyrite) (B31, B33, C22, L4) and sulfur (B33, B34, C22, L4) oxidation processes are the best understood. Investigations on the leaching of nickel sulfides (D21, D24, T17), lead sulfide (E4), molybdenum sulfide (molybdenite) (B17, B31, D24), cobalt sulfide (D9), zinc sulfide (D24), and uranium oxide (D24, F2, H13, H14, Ml) have been reported in the literature. 

T1 ecent investigations have shown that chromium, manganese, cobalt, nickel, copper, and zinc oxides react with uranium oxides at elevated temperatures to form double oxides with the formulas MUO4 and MU3O10. Table I lists eight compounds for which some structural and thermal stability information has been reported. 

Among the transition metals from chromium through zinc, iron remains the only element for which no double oxide formation with uranium oxide has been reported. Both the l.T and 1 3 compounds of mainganese, cobalt, and copper have been prepared, while only the 1 1 compound of chromium, and the 1 3 compound of nickel and zinc are known. 

The 3,3 -diaminobenzidine method has been applied for determination of Se in biological materials [28,66], soils [67], air [68], silicates [11], sulphide ores [1], copper [8,14,18], organic substances [69], lead [8,14], steel [29], antimony and bismuth tellurides [70], thin Cd-Se films [71], silver chloride and uranium oxide [12],... 

The uranium oxide was held in most cases in steel shells 6.8 by 10 cm thick, surrounded by shields to absorb thermal neutrons. No difference was found if copper shells were used in place of the steel. The thermal neutron shields were of two types one a mixture of CdS04 and AI2O3 such that there was 0.49 g/cm of Cd around the sphere, and the other B4C and AI2O3, sufficient to place 0.13 g/cm of B around the sphere. Above 700°C, in the CO atmosphere generated by diffusion of air into the furnace, the CdS04 decomposed, and CdS and Cd boiled off. Therefore, a chemical analysis of the shell was made after use, showing that some of the experiments were done with less Cd around the uranium than were others. To partially remedy this trouble, CdSiOs shells were prepared, but they also partly decomposed to Cd which evaporated. 

Table 7.8 DLs for Elements in High-Purity Copper and High-Purity Uranium Oxide Using DC Arc Emission Spectrometry...

Element High-Purity Copper High-Purity Copper High-Purity Uranium Oxide... 

A large variety of secondary uranium minerals are known, many are brilliantly colored and fluorescent. The commonest are gummite (a general term like limonite for mixtures of various secondary hydrated uranium oxides with impurities) hydrated uranium phosphates of the phosphuranylite type, including autunite (with calcium), saleeite (magnesium), and torbernite (with copper) and hydrated uranium silicates such as cof-finite, uranophane (with calcium), and sklodowskite (magnesium). 

The present fuel is made of stainless steel clad uranium oxide, but low absorbing can materials have been developed. Six channels of the reactor are loaded with zirconium-copper clad bundles, and their number will be progressively increased during the next two years, since Irradia-... 

For example, if the amount of ferrous iron minerals present in repository backfill and fracture minerals (represented by FeC03(s) in Fig. 1(a)) is much greater than the amount of O2 remaining after closure, then with time, all O2 will be reduced to H2O by these minerals, producing iron hydroxide in the process. This would ensure that the reducing intensity would return to values at least as low as the redox potential of the Fe(0H)3(s)/FeC03(s) couple (near —0.05 V). This is below the threshold for corrosion of either copper or uranium oxide by O2. It is also shghtly above the threshold for sulphide production by sulphate reduction (—0.2 V). The presence of ferrous minerals thus buffers the redox intensity of the repository to conditions that are favourable for repository performance. 

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