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Reductive acid leaching of manganese dioxide with glucose: Identification of oxidation derivatives of glucose
No full textThe oxidation of glucose during the reductive leaching of pure MnO2 and manganese ore in sulphuric, acid at 90 degrees C MnO2 was investigated. The aim was to identify the derivatives and the chemical pathway of glucose oxidation. Organic derivatives were monitored by HPLC using an Aminex HPX-78H column and UV detection. Chromatographic patterns of leaching solutions showed that major compound formed was formic acid. Minor quantities of glycolic, glycerie and traces of gluconic acids were identified. Results suggest that during the leaching reaction, the carbon chain of glucose is shortened by detachment of one carbon atom as formic acid. (c) 2006 Elsevier B.V. All rights reserved
Leaching of low-grade manganese ores: effects of mineralogical composition and reagent types on the optimisation of the operative conditions.
No full textDevelopment of a hydrometallurgical process for automobile shredded residue valorisation
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Leaching of low-grade manganese ores by using nitric acid and glucose: Optimization of the operating conditions
No full textManganese extraction from low-grade ores was investigated by using glucose as a reducing agent in dilute nitric acid medium. Ore characterisation by X-ray and SEM denoted that manganese is present as a mixed oxide Mn7O 13 (6MnO2·MnO) surrounding and joining together aluminosilicate fragments. The effects of temperature, particle size, glucose and nitric acid concentrations were investigated and compared with previous results using H2SO4. The operating conditions of leaching were optimised to obtain maximum manganese extraction and purity by performing sequential factorial designs and evaluating the statistical significance of the different factors by analysis of variance (ANOVA). The optimised conditions are 90°C, stoichiometric nitric acid, -20% below stoichiometric glucose and 295-417 μm size fraction. The stoichiometric reagent concentrations were evaluated according to the following reaction assuming all manganese in the ore as Mn(IV): C6H12O6+12MnO2+24H +=6CO2+12Mn2++18H2O Optimised leaching conditions with HNO3 give up to 99% manganese extraction, <0.05% iron dissolution and reduced reagent consumption compared to previous tests using H2SO4. © 2004 Elsevier B.V. All rights reserved
Automobile shredded residue valorisation by hydrometallurgical metal recovery
No full textThe aim of this work was developing a hydrometallurgical process to recover metals from automobile shredded residue (or car fluff). Automobile shredded residue (ASR) was characterised by particle size distribution, total metal content and metal speciation in order to guide the choice of target metals and the operating conditions of leaching. Characterisation results showed that Fe is the most abundant metal in the waste, while Zn was the second abundant metal in the fraction with diameter lower than 500 mu m. Sequential extractions denoted that Zn was easily extractable by weak acid attack, while Fe and Al required a strong acid attack to be removed. In order to recover zinc from <500 mu m fraction leaching tests were operated using acetic acid, sulphuric acid and sodium hydroxide at different concentrations. Sulphuric acid determined the highest zinc extraction yield, while acetic acid determined the highest zinc extractive selectivity. Sodium hydroxide promoted an intermediate situation between sulphuric and acetic acid. Zn recovery by electro winning using acetic leach liquor determined 95% of Zn electro deposition yield in 1 h, while using sulphuric leach liquor 40% yield in 1 h and 50% yield in 2 h were obtained. Simulation results showed that the sulphuric leaching process was more attractive than acetic leaching process. (C) 2010 Elsevier B.V. All rights reserved
Zeolite based photocatalytic membranes for the treatments of industrial effluents. Preliminary results
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