Sulfur forms determination in coal using microwave discharge activated oxygen and Moessbauer spectroscopy

The testing of the use of a microwave discharge to activate oxygen for the low temperature ashing of coal is discussed. The effect of low temperature ashing by the normal radiofrequency procedures and this new mircowave procedure upon The Fe-S compounds is monitored by the use of /sup 57/ Fe Moessbauer spectroscopy. Results show that the microwave technique effectively ashes the coal without the oxidation of pyritic sulfur. Dehydration of iron sulfates and oxidation of Fe /sup 2+/ to Fe /sup 3+/ in sulfates occurs in both ashing procedures under the conditions tested. Separate experiments show that dehydration is caused by sample heating rather than by reaction with the activated oxygen. The Moessbauer recoilless fractions of the Fe-sulfates observed in this study are found to be only about half that of pyrite