Browsing by Author "Ring, RJ"
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- ItemCatalytic decomposition of peroxygen compounds in uranium leaching circuits(Institution of Chemical Engineers : Institution of Engineers, Australia : Royal Australian Chemical Institute, 1985-08-25) Secomb, RJ; Ring, RJ; Nugent, AJThis paper reports on the kinetics of decomposition of hydrogen peroxide and Caro's acid under conditions encountered in uranium leach circuits. The relative catalytic activity of the metal ions was measured as a function of pH and temperature. The percentage utilisation of oxidants was measured in batch and continuous flow experiments in the presence of Fe(II) where oxidant reduction and decomposition occur simultaneously. The results are used to identify conditions which can maximise the use of oxidant in large-scale leaching circuits.
- ItemLeaching of heavy metals and radionuclides from uranium tailings(Institution of Chemical Engineers : Institution of Engineers, Australia : Royal Australian Chemical Institute, 1985-08-25) Ring, RJ; Levins, DM; Cooper, MBThis paper presents results of accelerated column leaching tests carried out to estimate the long-term release rate of heavy metals and radionuclides from Australian uranium tailings. The effect of limestone and lime treatment before impoundment is examined. A simple model is proposed which can be used, in association with seepage data, to estimate the total quantities of contaminants released over many centuries.
- ItemManufacture of phosphatic fertilisers and recovery of byproduct uranium - a review.(Australian Atomic Energy Commission, 1975-11) Ring, RJThe processes used in the production of phosphatic fertilisers are reviewed and those in which uranium can be extracted as a byproduct are described in detail. The current status of the world and Australian phosphate rock and fertiliser industries is described and production figures and marketing information for these industries are also presented. Techniques for the recovery of byproduct uranium during the processing of phosphate rock to fertilisers are also examined in detail. Recovery from wet-process phosphoric acid by solvent extraction is the most promising approach.
- ItemOxidants for uranium leaching(ALTA Metallurgical Services, 2007-05-24) Ho, E; Ring, RJMost uranium ores are leached with sulfuric acid under oxidising conditions. This paper reviews the oxidants that have been traditionally used in uranium leaching and discusses their merits in the context of overallow sheet considerations. Options for alternative oxidants are also discussed. In acid leaching, ferric ion (Fey) in solution oxidises insoluble uranium(IV) to soluble uranium(VI). Though ferric ion may be added directly, usually an oxidant is added to the circuit to convert ferrous ion to ferric ion in the liquor so that leaching can continue. The most common oxidants are pyrolusite and sodium chlorate. Pyrolusite is relatively cheap but introduces manganese ions into the liquor and consumes twice as much acid as sodium chlorate. Sodium chlorate is a slow reacting oxidant at low temperatures and acidities, and introduces chloride into the leach liquor. Caro ’s acid, HZSO5, is a non-polluting reagent that was used successfully at the Nabarlek uranium mine, and provided very good control of oxidising conditions. Other oxidants that are now being considered to overcome the disadvantages of pyrolusite and sodium chlorate are oxygen, hydrogen peroxide and SO/O2. Some performance data for these oxidants are presented. © The Authors
- ItemPilot scale production of yellowcake from the Kintyre uranium deposit using a direct precipitation process(Institution of Engineers Australia, 1998-09-28) Machaughton, SJ; Collier, DE; Tapsell, GJ; Ring, RJ; Hawley, B; Bellingham, AKintyre is a high grade uranium deposit located in the north west of Western Australia 90 km south of Telfer. Two bulk samples of upgraded ore from the deposit were processed in a pilot plant to produce a saleable uranium oxide concentrate. The pilot plant was operated continuously for 42 days at a throughput of 15 kg h-1. This paper describes the direct precipitation processing route that was employed and the performance of the plant under a range of operating conditions. Ground ore was leached at 56% solids using sulphuric acid and hydrogen peroxide as an oxidant. The leach liquor was recovered using a high rate thickener followed by belt filtration. The resulting leach liquor had a tenor of 6 to 8 g L-1 U3O8 and was treated with hydrogen peroxide to oxidise any ferrous iron to the ferric state. The ferric iron was then removed by precipitation with lime. The iron precipitate was leached with sulphuric acid to recover uranium before disposal with the primary leach tailings. Yellowcake was precipitated from the clarified iron-free liquor using hydrogen peroxide and sodium hydroxide for pH control. The simplicity of the circuit – a leaching stage followed by two precipitation stages – is in marked contrast to conventional uranium circuits which utilise solvent extraction or ion exchange to recover uranium from leach liquors. Operation of the pilot plant successfully demonstrated the technical feasibility of the direct precipitation processing route. In both precipitation circuits the overall efficiency was found to be dependent on the distribution of reagents within each circuit. Optimisation of these variables resulted in high precipitation efficiencies (>99.9%). The design criteria that were established in the pilot plant were generally more favourable than predictions based on laboratory testwork.
- ItemRecovery of byproduct uranium from the manufacture of phosphatic fertilizers(Australian Atomic Energy Commission, 1977-01-01) Ring, RJ
- ItemRegeneration of caustic potash solution used for the disposal of gaseous fluorides(Institution of Chemical Engineers, 1975-08-23) Royston, D; Burwell, A; Janov, J; Le Page, AH; Levins, DM; Ring, RJ; Vilkaitis, VKA system for the disposal of fluorine and gaseous hydrogen fluoride was developed as part of an experimental 1500 A fluorine cell facility used to investigate the production of fluorine. The design, operation and performance of the plant have been described in detail by Royston et al.1,2. The cell produced fluorine and hydrogen at 0.24 & s-1 with both gases containing approximately l0 vol.% hydrogen fluoride. These off—gases were disposed of continuously by scrubbing with 5-8.5 wt.% caustic potash solution which was regenerated by reaction with lime on a batch basis. This paper outlines the selection of the system and describes its operation and performance.
- ItemReview of fluorine cells and fluorine production facilities(Australian Atomic Energy Commission, 1973-09) Ring, RJ; Royston, DThe development of laboratory and industrial scale electrolytic cells used for the generation of fluorine is reviewed and the construction and operating characteristics of these cells are examined in detail. In addition, the associated facilities required for the supply and treatment of raw materials, treatment of product gases and disposal of waste materials are described. Safety practices adopted in the design and operation of equipment including personnel protection and first aid procedures are also outlined.
- ItemReview of recent developments in uranium extraction technology(Australian Atomic Energy Commission, 1978-12) Alfredson, PG; Crawford, RE; Ring, RJDevelopments in uranium ore processing technology since the AAEC Symposium on Uranium Processing in July 1972 are reviewed. The main developments include the use of: - autogenous or semi-autogenous grinding, - benefication techniques such as radiometric sorting, flotation, magnetic and gravity separation, - strong acid and ferric bacterial leaching processes, - solution mining and heap leaching operations - horizontal belt filters for solid-liquid separation, - continuous ion exchange processes for use with solutions containing up to 8wt % solids, - hydrogen peroxide and ammonia for the precipitation of uranium to improve product yield and purity, and - the recovery of by-product uranium from the manufacture of phosphoric acid and copper processing operations.
- ItemTreatment of uranium waste liquors by the high density sludge process(Institution of Engineers Australia, 1998-09-28) Tapsell, GJ; Ring, RJ; Collier, DEThe treatment of acidic waste liquors is often carried out in a conventional neutralisation circuit using lime as reagent. The High Density Sludge (HDS) process improves this technology by recycling conditioned thickener underflow to modify the precipitate particle formation, leading to an increase in the density of the settled solids. The treatment of two waste liquors from uranium ore processing were tested in both conventional and HDS circuits. The HDS process consumed more reagent than the conventional treatment but improved the quality and quantity of treated effluent for recycle. Tests on the liquors have indicated a marked increase in sludge density using the HDS process compared to conventional treatment. In both cases no change in the particle size was observed, indicating that the HDS solids contain less water in a more compact structure. The increased solids content of the HDS sludge ensured higher filtration rates than the conventionally produced sludge, and allowed filter cakes of lower moisture content to be produced.