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Introduction Raney metal type catalysts are prepared by leaching the reactive material out from alloys of catalytically active transition metals such as nickel, cobalt, iron, copper and a reactive material such as aluminum with

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] Kovalčíková M. , Eštoková A. Leaching of calcium and silicon from cement composites in the aggressive environment , Pollack Periodica , Vol. 9 , No. 2 , 2014 , pp. 123 – 130 . [13

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Faucon P., Le Bescop P., Adenot F., Bonville P., Jacquinot J. F., Pineau F., Felix B. Leaching of cement, study of the surface layer, Cement and Concrete Research 26, 1996; pp. 1707–15. Felix B

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. [5] Marion A. M. , Lanève M. D. , Grauw A. D. Study of the leaching behavior of paving concretes: quantification of heavy metal content in leachates issued

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Abstract  

This paper describes the solvent extraction studies carried out on an acidic low assay uranium bearing leach liquor generated during sulfuric acid leaching of a refractory uranium ore using alamine 336–isodecenol–kerosene reagent combine. The leach liquor has a U3O8 content of about 270 mg/L, free acidity 2.4 N H2SO4 and total dissolved solids concentration of 260 g/L. Process parameteric variation studies indicated strong influence of free acidity of the leach liquor, alamine 336 concentration and aqueous to organic phase ratio on the extraction efficiency of uranium. An extraction efficiency of about 95% was achieved when the free acidity of leach liquor was 1 N H2SO4 or lower, using 2% (v/v) alamine 336 at ambient temperature with an aqueous to organic phase ratio of 1:1. The loading capacity under these conditions was 1.2 g/L of U3O8. About 98% of the uranium values could be stripped from the loaded organic using 1 N NaCl in 0.2 N H2SO4. The solvent extraction studies aided in developing a suitable process flowsheet for treating refractory uranium ores which need high acidity during leaching and relatively lower acidity for purification by solvent extraction.

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Abstract  

The tetravalent and hexavalent uranium content of three Egyptian phosphate type ore samples namely; Sebayia, Abu Tartur and Qatrani have been studied through selective leaching by hydrochloric acid at normal, oxidized and reduced conditions at an amount of hydrochloric acid less than the stoichiometric value i.e. before phosphoric acid production. Oxidizing condition is attained by incorporating 2% of manganese dioxide in the leaching cycle, whereas reducing condition is attained by adding 2% iron powder. The achieved results show that the amount of tetravalent uranium varies between 5 and 95%. As soon as the achieved stoichiometric value of hydrochloric acid is sufficient to produce phosphoric acid both tetravalent and hexavalent uranium dissolve by virtue of phosphoric acid complexing power for uranium. The chemical form of uranium in the ore determines the type of solvent needed to recover it.

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Abstract  

A radiotracer technique was used to investigate the leaching of an antifouling agent from different marine paint formulations with an objective to select the best paint formulation for bulk production. The antifouling agent (Diuron) itself was labeled with carbon-14 (half-life: 5,730 years, β-energy: 156 keV) and used as a radiotracer. The different paint formulations added with radiolabeled Diuron were applied onto suitably selected substrates and measured for initial intensity of β-radiation using a Geiger-Muller detector connected to a ratemeter. The painted substrates were subjected to shower tests for a pre-decided time and subsequently measured for β-radiations. The comparison of intensity of β-radiations in substrates prior and post shower tests provides information about leaching of antifouling agent Diuron from the paint formulation. The high leaching percentage of antifouling agent Diuron post shower tests indicates non-suitability of paint formulation for marine and civil structures. However, low leaching rate of Diuron will make a paint formulation more efficient and suitable. Based on the results of investigation, a paint formulation with minimum leaching rate was identified and selected for bulk production by a paint company.

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Journal of Thermal Analysis and Calorimetry
Authors: L. A. Perez-Maqueda, C. Maqueda, J. L. Perez-Rodriguez, J. Subrt, Z. Cerny, and V. Balek

amorphization, accompanied with the formation of hard agglomerates by cold-welding [ 11 ]. Selective leaching by acid has been used to prepare porous silica from various clay minerals, including vermiculite [ 12 – 15 ]. The presence of iron in the

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. Influences of pipe drainage and fertilization on nitrate leaching. Cereal Res. Commun. 35 :237–240. Vrhovec D. Influences of pipe drainage and fertilization on nitrate leaching

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Kádár, I., T. Németh, G.J. Kovács 1987: Nitrogen efficiency and nitrate leaching on a calcareous chernozem soil. - In: 5 th International Symposium of CIEC. 2. Sec. 1, Balatonfüred, Hungary, pp. 130–137. Kovács

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