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Extraction and characterization of alumina nanopowders from aluminum dross by acid dissolution process

International Journal of Minerals,Metallurgy and Materials 2015年第4期22卷 429-436页

作者： Saifur Rahman Sarker Zahangir Alam Rakibul Qadir M A Gafur Mohammad Moniruzzaman Department of Applied Chemistry and Chemical Engineering University of Dhaka Pilot Plant & Project Development Centre (PP& PDC) Bangladesh Council of Scientific and Industrial Research (BCSIR) BCSIR Laboratories Dhaka

A significant amount of aluminum dross is available as a waste in foundry industries in Bangladesh. In this study, alumina was ex- tracted from aluminum dross collected from two foundry industries situated in Dhamrai and Manikgang, near the capital city, Dhaka. Alu- minum dross samples were found to approximately contain 75wt% A1203 and 12wt% SIO2. An acid dissolution process was used to recover the alumina value from the dross. The effects of various parameters, e.g., temperature, acid concentration, and leaching time, on the extrac- tion of alumina were studied to optimize the dissolution process. First, AI（OH）3 was produced in the form of a gel. Calcination of the AI（OH）3 gel at 1000℃, 1200℃, and 1400℃ for 2 h produced O-AlcOa, （t~＋O）-A1203, and u-alumina powder, respectively. Thermal charac- terization of the AI（OH）3 gel was performed by thermogravimetric/differential thermal analysis （TG/DTA） and differential scanning calo- rimetry （DSC）. The phases and crystallite size of the alumina were determined by X-ray diffraction analysis. The dimensions of the alumina were found to be on the nano level. The chemical compositions of the aluminum dross and alumina were determined by X-ray fluorescence （XRF） spectroscopy. The microstructure and morphology of the alumina were studied with scanning electron microscopy. The purity of the alumina extracted in this study was found to be 99.0%. Thus, it is expected that the obtained alumina powders can be potentially utilized as biomaterials.

关键词： aluminum dross alumina nanoparticles acid dissolution calcination X-ray fluorescence analysis

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Mechanisms of Pb(Ⅱ) coprecipitation with natrojarosite and its behavior during acid dissolution

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Journal of Environmental Sciences 2022年第12期34卷 128-137页

作者： Meiqing Shi Xiaobo Min Chen Tian Taixu Hao Sijie Zhu Yun Ge Qingwei Wang Xu Yan Zhang Lin Institute of Environmental Engineering School of Metallurgy and EnvironmentCentral South UniversityChangsha 410083China Chinese National Engineering Research Center for Control&Treatment of Heavy Metal Pollution Changsha 410083China Water Pollution Control Technology Key Lab of Hunan Province Changsha 410004China

Lead(Pb) coprecipitation with jarosite is common in natural and engineered environments,such as acid mine drainage(AMD) sites and hydrometallurgical industry. Despite the high relevance for environmental impact, few studies have examined the exact interaction of Pb with jarosite and the dissolution behavior of each phase. In the present work, we demonstrate that Pb mainly interacts with jarosite in four modes, namely incorporation, occlusion,physically mixing, and chemically mixing. For comparison, the four modes of Pb-bearing natrojarosite were synthesized and characterized separately. Batch dissolution experiments were undertaken on these synthetic Pb-bearing natrojarosites under pH_(2) to simulate the AMD environments. The introduction of Pb decreases the final Fe releasing efficiency of jarosite-type compounds from 18.18% to 3.45%-5.01%, showing a remarkable inhibition of their dissolution. For Pb releasing behavior, PbSO_(4) dissolves in preference to Pb-substituted natrojarosite, i.e.,(Na, Pb)-jarosite, which primarily results in the sharp increase of Pb releasing concentration(> 40 mg/L). PbSO_(4) occlusion by jarosite-type compounds can significantly reduce the release of Pb. The results of this study could provide useful information regarding Fe and Pb cycling in acidic natural and engineered environments.

关键词： Pb-bearing natrojarosite Interaction mechanism acid dissolution Releasing behavior

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