โ Scribed by Gerald P. Huffman; Frank E. Huggins; Armand A. Levasseur; Oscar Chow; Srivats Srinivasachar; Arun K. Mehta
No coin nor oath required. For personal study only.
The transformations of pyrite removed from coal in a drop-tube furnace containing a 95 % N,-5 % 0, atmosphere were investigated. Gas temperatures ranged from 13 11 to 1727 K and residence times from 0.07 to 1.2 s. Mossbauer spectroscopy provided quantitative analysis of the iron compounds in the drop-tube samples, while computer-controlled scanning electron microscopy (CCSEM) was used to study particle morphology and elemental distribution. Magnetite was the dominant oxide phase formed, while pyrrhotite (Fe, _,S) was the dominant sulphide. Small amounts (5 10 %) of hematite, wustite and remnant pyrite were common. The CCSEM results showed evidence of extensive melting, even at the lowest temperature, indicating exothennic oxidation reactions. A thermodynamic model gave reasonable agreement with the observed variation of the iron phase distributions.
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