Phase Transformations of α-Alumina Made from Waste Aluminum via a Precipitation Technique

We report on a recycling project in which α-Al2O3 was produced from aluminum cans because no such work has been reported in literature. Heated aluminum cans were mixed with 8.0 M of H2SO4 solution to form an Al2(SO4)3 solution. The Al2(SO4)3 salt was contained in a white semi-liquid solution with excess H2SO4; some unreacted aluminum pieces were also present. The solution was filtered and mixed with ethanol in a ratio of 2:3, to form a white solid of Al2(SO4)3·18H2O. The Al2(SO4)3·18H2O was calcined in an electrical furnace for 3 h at temperatures of 400–1400 °C. The heating and cooling rates were 10 °C/min. XRD was used to investigate the phase changes at different temperatures and XRF was used to determine the elemental composition in the alumina produced. A series of different alumina compositions, made by repeated dehydration and desulfonation of the Al2(SO4)3·18H2O, is reported. All transitional alumina phases produced at low temperatures were converted to α-Al2O3 at high temperatures. The X-ray diffraction results indicated that the α-Al2O3 phase was realized when the calcination temperature was at 1200 °C or higher.

[1]  W. Suchanek.  Hydrothermal Synthesis of Alpha Alumina (α‐Al2O3) Powders: Study of the Processing Variables and Growth Mechanisms , 2010 .

[2]  M. Ghasri-Khouzani,et al.  Effect of mechanical activation on structure and thermal decomposition of aluminum sulfate , 2009 .

[3]  D. Young.  High Temperature Oxidation and Corrosion of Metals , 2008 .

[4]  P. Praserthdam,et al.  Impact of concentration and Si doping on the properties and phase transformation behavior of nanocrystalline alumina prepared via solvothermal synthesis , 2008 .

[5]  R. Doremus,et al.  Ceramic and glass materials : structure, properties and processing , 2008 .

[6]  F. Yen,et al.  Microstructure-controlled effects on temperature reduction of α-Al2O3 crystallite formation , 2007 .

[7]  R. Moreno,et al.  Synthesis of Gamma-Alumina Nanoparticles by Freeze Drying , 2006 .

[8]  G. Rohrer,et al.  Influence of Diaspore Seeding and Chloride Concentration on the Transformation of “Diasporic” Precursors to Corundum , 2004 .

[9]  P. K. Mitra,et al.  Thermal decomposition of precipitated low bulk density basic aluminium sulfate , 2004 .

[10]  S. Rossignol,et al.  Preparation of alumina through a sol–gel process. Synthesis, characterization, thermal evolution and model of intermediate boehmite , 2003 .

[11]  P. Bowen,et al.  From powders to sintered pieces: forming, transformations and sintering of nanostructured ceramic oxides , 2002 .

[12]  P. Mishra.  Low-temperature synthesis of α-alumina from aluminum salt and urea , 2002 .

[13]  B. Pacewska,et al.  Thermal transformations of aluminium nitrate hydrate , 2002 .

[14]  J. Ferreira,et al.  Recycling of Al-rich industrial sludge in refractory ceramic pressed bodies , 2002 .

[15]  R. Pati,et al.  A new chemical route for the synthesis of nano-crystalline α-Al2O3 powder , 2001 .

[16]  M. Ozawa,et al.  Structural phase transformations of rare-earth modified transition alumina to corundum1Work supported by US Department of Energy, BES, contract No. W-31-109-ENG-38.1 , 1997 .

[17]  P. K. Sinha,et al.  Characterization of plasma-synthesized alumina , 1996 .

[18]  J. T. Kloprogge,et al.  Thermal stability of basic aluminum sulfate , 1992 .

[19]  J. Geus,et al.  Sintering of pseudo-boehmite and γ-Al2O3 , 1991 .

[20]  N. Ogata,et al.  Preparation of monodisperse, spherical alumina powders from alkoxides , 1991 .

[21]  N. Apte,et al.  Thermal decomposition of aluminium-bearing compounds , 1988 .

[22]  A. B. Gancy.  Preparation and characterisation of the nonahydrate and pentahydrate of aluminum sulfate , 1982 .

[23]  J. M. Rao,et al.  Dehydration Behavior of Aluminum Sulfate Hydrates , 1981 .

[24]  W. H. Gitzen.  Alumina as a ceramic material , 1970 .