Potassium alum thermal decomposition stu

Potassium sulfate (K2 SO4) is a very important compound, mostly used as nutrient for plant growth. Potassium sulfate production can be accomplished through the Mannheim process. For potassium bearing silicate minerals, such as glauconite, one alternative is acid leaching followed by selective precipitation and thermal decomposition of potassium alum (KAl(SO4)2). This chemical process is responsible for the formation of soluble K2 SO4 and insoluble Al2 O3, which can be later separated after solubilization in water and filtration. In this pyrometallurgical reaction, the temperature control is very important. Through the addition of a reducing agent, the decomposition temperature could be significantly reduced. In the present work, the thermal behavior of synthetic samples of hydrated potassium alum (KAl(SO4)2·12H2O) is appreciated through thermogravimetric analysis (TGA), both in the absence as well as in the presence of a reducing agent (charcoal) under inert atmosphere (nitrogen) and dynamic analysis. The addition of a stoichiometric amount of the reducing agent stimulated considerably the decomposition, which started at a lower temperature in comparison to non-reductive conditions.