Papers by Keyword: Alkaline Leaching

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Authors: Shao Jian Ma, Jin Lin Yang, Gui Fang Wang, Wei Mo, Xiu Juan Su
Abstract: Alkaline leaching is an important way for treating low grade metal oxide ore, which has some advantages such as low corrosion and low pollution compared to acidic leaching. In order to recover the zinc from a low grade complex zinc oxide ore in which the grade of Zn and Fe are 13 wt.% and 40.2 wt.%, respectively, and 52.8% of Zn is contained in siderite, 34.63% in limonite and 11.55% in smithsonite, this paper presents a preliminary investigation of this type of ore by alkaline leaching method. In this study, ammonia-ammonium chloride and ammonia-ammonium carbonate were used as the leaching reagents. The effects of alkaline concentration, leaching time, leaching temperature and liquid to solid ratio (L/S) were studied, respectively. The results show that 43.15% of initial Zn content was extracted adopting ammonia-ammonium chloride as the leaching reagent in 4.5M at 30°C for 3h with a liquid to solid ratio of 4:1, while 43.07% of Zn recovery was achieved employing ammonia-ammonium carbonate as the leaching reagent at 5M, 30°C and 4:1(L/S). The low leaching rate of Zn is probably attributed to that the zinc contained in siderite was not extracted completely because Zn and Fe exist as isomorphism in siderite.
Authors: Francisco Espinosa-Magaña, L. Bejar Gómez, Ivanovich Estrada-Guel, Roberto Martínez-Sánchez
Authors: Cheng Long Zhang, Li Li Zhuang, Ying Shun Li, Wen Yi Yuan, Jing Wei Wang, Jian Feng Bai
Abstract: This study evaluates the efficiency of lead (Pb) extraction from spent leaded glass in strongly alkaline solution after mechanical activation in a planetary ball mill as the chemical breakage and defects formed in the inner structures will contribute to the easy dissolution of the activated leaded glass. The influence of rotate speed and time of mechanical activation, NaOH concentrations, leaching temperature, phase ratios (v/w) had been studied. More than 78% of Pb extraction can be achieved after mechanical activation, compared with 3.5% Pb extraction for chemical leaching of non-activated samples. High purity lead powder can be obtained by electrowinning from the leaching solution. The Pb-depleted solution can be recycled into the leaching step. Thus, a novel hydrometallurgical process for recovering Pb from spent leaded glass in alkaline solution is proposed.
Authors: Jia Peng Chen, Li Wen Ma, Ming Xing Cao, Xiao Li Xi
Abstract: Tungsten and vanadium are efficiently extracted from honeycomb-type spent selective catalytic reduction (SCR) catalyst by using a high pressure alkali leaching method. Theoretical thermodynamics calculation indicates that WO3 and V2O5 are soluble in sodium hydroxide solution, proving that the extraction of Wand V from the spent SCR catalyst by high pressure alkaline leaching is feasible. The effects of NaOH concentration, leaching temperature and time, liquid-solid ratio and stirring speed on leaching efficiency of W and V are systematically investigated. The leaching efficiency of W and V is 94.3% and 91.2%, respectively, under the optimal conditions: the NaOH concentration of 2mol/L, the leaching temperature 463.5 K, the reaction time 3 h, solid-liquid ratio 0.1 g/ml, the stirring speed of 400 r/min. The TiO2 residue is in anatase crystalline phase.
Authors: Jian Hua Liu, Jing Long Chu, Tian Yan Xue, Yan Fang Han, Tao Qi
Abstract: In order to reduce the silicon content to the maximum allowed value for the production of high-purity titanium dioxide, a hydrometallurgical process on the desiliconization during alkaline leaching of titanium slag under atmospheric pressure was studied. The effect of leaching temperature, initial NaOH concentration, leaching time and mass ratio of alkali to slag, on the efficiency of silicon removal were investigated. The results show that when the mass concentration of NaOH is 30%, mass ratio of alkali to slag 3:1, the leaching temperature 120°C and the retention time about 120min, the content of silicon in solid is reduced to 0.45%. Simultaneously, the content of aluminum is reduced to 1.62%, without affecting the content of titanium. The kinetics on the desiliconization during alkaline leaching of titanium slag was carried out. The results show that under the leaching parameters mentioned above, the apparent activation energy is calculated to be 45.43kJ/mol.
Authors: Ivanovich Estrada-Guel, G. Alonso, C. Ornelas, J.I. Barajas-Villaruel, L. Bejar Gómez, Francisco Espinosa-Magaña, Roberto Martínez-Sánchez
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