Akademik Veri Yönetim Sistemi
Industrial and Engineering Chemistry Research, cilt.41, sa.24, ss.6028-6032, 2002 (SCI-Expanded)
The thermal decomposition of Şaphane alunite from Kütahya, Turkey, has been studied using ambient- and high-temperature X-ray diffraction analysis, differential thermal analysis, and thermogravimetric analysis. The alunite content in the ore was about 47.5%. The first endothermic peak at about 545°C is due to the dehydration of the structural water and the transformation of alunite into KAl(SO4)2 and amorphous Al2O3. The small exothermic peak at about 712°C is probably caused by the recrystallization of KAl(SO4)2 into K3Al(SO4)3 and Al2-(SO4)3. So far, no work has reported this new phase, K3Al(SO4)3, resulting from the exothermic reaction of alunite. Moreover, the d and I values of unidentified peaks in the previous literature gave reflections that were surprisingly identical to those of the K3Al(SO4)3 peaks. The second endothermic peak at about 810°C is due to the desulfurization by which K3Al(SO4)3 and amorphous Al2(SO4)3 decompose into K2SO4 (arcanite) and two polymorphic varieties of Al2O3 (κ and γ). Above 800°C, only γ-alumina and arcanite were observed.