STUDY OF COAL-DERIVED PYRITE AND ITS CONVERSION PRODUCTS USING ATMOSPHERIC-PRESSURE TEMPERATURE-PROGRAMMED REDUCTION

This study represents an explanation for the behavior of coal pyrite s ubjected to a linear temperature increase up to 1000 degrees C in an i nert (TGA) as well as reductive (AP-TPR) atmosphere. The two pyrite sa mples were extracted from coals of the Halemba and Jastrzebie mines in Poland. In order to understand the behavior of the most frequent occu ring inorganic iron-sulfur compounds in coal under AP-TPR conditions, conversion products of pyrite, namely pyrrhotite (Fe10S11) and troilit e (FeS), were examined as well. An influence of the particle size on t he pyrite reduction was observed. As for the sample mass, only an effe ct on the troilite reduction was found. Similarity of the AP-TPR profi les of coal-derived pyrite and mineral pyrite indicates the analogous reduction course. A study of the iron sulfate as another conversion pr oduct of pyrite is also included in this paper. The complementary tech niques used in this study, TGA and TGA-MS together with AP-TPR, have e nabled us to formulate a mechanism behind the pyrite and sulfate chemi stry under reducing experimental conditions.