Mossbauer Analyses of the As-Mined Samples

Typical Mossbauer spectra of coal samples are shown in Fig. 30.3a and b and the spectra of all the as-received samples consisted of one or two doublets, each characterized by the isomer shift (S), the quadrupole splitting (A), and a relative spectral area (%). 

From the Mossbauer spectra, it can be concluded that the iron-bearing minerals were pyrite, ankerite, illite, and jarosite. In the SEM analyses, the non-iron-bearing minerals quartz, clay, and carbonates were observed in addition to the iron-bearing minerals. 

The Mossbauer parameters obtained for the iron-bearing minerals are shown in Table 30.2 and are in agreement with those published in the literature [8]. It is clear from the data that distinctions between the different coal fields can be made. Sample 4 was taken from the stockyard pile of the Delmas mine in the Mpumalanga/Witbank coal field and has undergone some weathering, thus the appearance of the ferrous sulfate, a phenomenon that will be discussed in Section 30.3.2. 

It should also be noted that these results are obtained from just a few samples and already a pattern emerges and detailed analyses of an ongoing project will make an enormous amount of information available to assist in a better understanding of the iron minerals and their distribution in the coal and different coal fields. 

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