Preparation And Characterization Of Alumina By The Direct Spray Pyrolysis Of AlCl₃Solution

China is aluminium industry power, the output of alumina in our country has broke through40million tons at the end of2013. As the productivity increased constantly, high quality alumyte reserves in our country can hardly meet the need of alumina industry. So the efficient utilization technology in nontraditional bauxite with large reserve, as presented by high Fe bauxite and Al-Fe paragenetic mineral, is drawing great attention of academic circles and industry circles。For better utilization of the nontraditional bauxite mentioned above, our research group proposed a double circulation for Al2O3production process, that is Pressure-leached with hydrochloric acid-separation of the leaching liquid and extract liquid-directly producing Al2O3with AICl3solution by spry pyrolysis. The advantage of this technology is that it makes the traditional process of producing Al2O3more simple, and reduces energy consumption and the hydrochloric produced can be recycled.(1) The chlorine content of spray pyrolysis product was lower than0.5%prepared under the conditions of800℃for20min, spray pressure is0.2Mpa and AlCl3concentration is15%. In order to achieve this index, the desired temperature is more than900℃for direct pyrolysis of AlCl3crystals, this indicate that the application of spray pyrolysis can reduced the pyrolysis temperature of AlCl3effectively.(2) Orthogonal experiment of propane combustion and resistance furnance spray pyrolysis have been studied, the results indicate:the temperature and AlCl3concentration of propane combustion spray pyrolysis had some influence on the pyrolysis process. On the other hand, the pressure of carrier gas had less influence, the reason is that there was flame jet in the propane heating pyrolysis furnance, and it leads to a severe gas flow, therefore, the impact of carrier gas pressure was weakened. For resistance furnance pyrolysis, the temperature was significant factor, and the AlCl3concentration and carrier gas pressure were general factors.(3) Raising of pyrolysis temperature can reduce the pyrolysis time significantly. The product of AlCl3crystals static pyrolysis began to crystallized at800℃, and it priority growth along the (440) lattice plane, as the product of static pyrolysis process, the morphology of alumina was lamellar, and pore of the product mainly in the presence of the slit-shaped hole and plate-shaped hole through analysis of the specific surface area. In contrast, the resistance furnance spray pyrolysis began to crystallized at700℃, and with increasing of pyrolysis temperature, each intensity of diffraction peak of different lattice plane improved significantly, this indicate that the alumina product growth acceleration along each lattice plane as the temperature increases. It is important to note that the growth rate of (440) lattice plane higher than others two plane clearly, and pore of the product mainly exist as cylindrical hole.