Surface and Bulk Properties of Alumina Recovered Under Various Conditions from Aluminum Dross Tailings Chemical Waste Ve
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Samih A. Halawy and Mohamed A. Mohameda) Chemistry Department, Faculty of Science at Qena, South Valley University, Qena 83523, Egypt
Mohamed I. Zaki Chemistry Department, Faculty of Science, Minia University, El-Minia 61519, Egypt (Received 20 February 2002; accepted 15 April 2002)
Bauxite ore (industrial raw material) and aluminum dross tailings (a local industrial waste material of the Aluminium Company of Egypt, Egyptalum) were used as two different parent materials to produce alumina. A set of six different preparation methods was applied to aluminum extracts from both materials. X-ray powder diffractometry, thermal and chemical analyses, and surface area and charge measurements were used to characterize the alumina products. The results indicate that catalytic grade, high-purity alumina products of uniform particle sizes could be obtained in large yields, depending solely on the preparation method applied, i.e., irrespective of the raw material used. Thus, aluminum dross tailings chemical waste is proved to be a feasible parent material for specialty alumina, which is an important finding both economically and environmentally.
I. INTRODUCTION
Naturally occurring bauxite ores are industrially widely used for the production of technical aluminas (Al2O3). The content of alumina in bauxite varies (28–60% by mass1) depending on the ore phase composition. Gibbsite-rich and boehmite-rich bauxites are the favorable raw materials for alumina production by the Bayer process.2 However, the former ore is preferred because it is more readily soluble in NaOH than the latter.2 In recent years, the recovery of alumina from chemical wastes of the aluminum industry has received increasing attention, due to environmental and economic necessities.3–5 Other useful aluminum compounds have, moreover, been recovered from waste materials, such as aluminum sulfate,6 ammonium sulfate alums,6 hydroxides,7 abrasives8 and quick-set cement,9 and aluminum metal.10 Among the waste materials that have been found promising is aluminum dross tailings (ADT). Due to relatively large amounts of ADT (ca. 12,800 tons/year) generated at Egyptalum (a major aluminum and alumina producer in Egypt), the present laboratories have been focusing on developing methods and procedures to recover specialty aluminas from ADT. Consequently, a a)
Address all correspondence to this author. J. Mater. Res., Vol. 17, No. 7, Jul 2002
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novel synthetic route to high-area alumina via H2O2precipitated boehmite from caustic extracts of ADT has been devised.11 The influence of a number of preparation variables on this method has been probed,12 and aluminas thus produced were physicochemically characterized.12 Catalytic-grade (gamma) alumina has, accordingly, been identified and, later, successfully utilized in the chemical makeup of ethene-selective ethanol dehydration catalyst.13 In continuation of this research endeavor, this article presents and discusses results of surface and bulk characterization studies perf
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