Witbank coal

Nakagawa, T., Nishikawa, K., and Komaki, I. (1999). Change of surface fractal dimension for witbank coal with heat-treatment studied by smaU angle X-ray... 

Fig. 3. H CRAMPS spectra of Witbank coal (a) raw coal (b) C5d5N-saturated coal (c) differential spectrum.

Fig. 6. 3C CP/MAS spectra of Witbank coal with editing techniques (a) CP/MAS with TOSS (b) LCPD(CH3 and C function group) (c) SCPPI(CH2 function group only).

Fig. 17. NMR 3D and 2D images of (a) Goonyella coal (b) Witbank coal obtained by SPRITE method and (c) Goonyella coal obtained by spin echo method.

The samples used in this study were Witbank coal and Goonyella coal. To reduce the effect of residual water in the coal on the microimage, the coal samples were evacuated at about 10 2 Torr for approximately 24 h at room temperature and stored in a glovebox under a dry N2 atmosphere. The size of the bulk sample used was about 2.5 mm x 2.5 mm x 100 pm, which was cut artificially in order to reduce the measurement time for the 3D-SPI experiment. The specimen was placed into a 5 mm diameter high-temperature ESR tube with AFO-t powder. 

Fig. 25. H-NMR spectra for Witbank coal obtained at various temperatures.

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. 

Hart R. J. and Leahy R. M. (1983) The geochemical characterization of coal seams from the Witbank Basin. Spec. Publ. Geol Soc. S. Afr. 7, 169-174. 

This section discusses 3D-SPRITE which has been shown to be successful for studying short relaxation time systems and which is free from distortions due to susceptibility variations for coals with high resolution at a frequency of 400 MHz.55 The results obtained are discussed in relation to the three-dimensional distribution of the mobile component for two kinds of coal, Witbank and Goonyella. At the same time, inversion recovery preparation experiments (7 mapping), T2 mapping and T mapping based on SPRITE methods are presented in order to clarify the chemical heterogeneity of coals. 

Fig. 26. Variations in the rates and their half-widths at half-height for the mobile component between 25 °C and 550 °C for Witbank and Goonyella coals.

Fig. 29. In situ T SPRITE image of (a) Witbank and (b) Goonyella coal at various temperature. From top left, T image at room temperature, T -SPRITE image at 425 °C from bottom left, T -SPRITE image at room temperature, T -SPRITE image 450 °C.

Pone J D Hein K A (2007). The spontaneous combustion of coal and its by-products in the Witbank and Sasolburg coalfields of South Africa. International Journal of Coal Geology 72 (2) 124-140. 

Coal Pennsylvania Coalfield, USA Witbank Coalfield, South Africa Wangaloa Coal mines. New Zealand South Coalfield, Brazil Okpara Coalmine, Nigeria Makum and Jantia Coalfield, India Guizhou Coalmine, China Cravotta et al. (2010) Belletal. (2001) Black and Craw (2001) Lattuada et al. (2009) Nganje et al. (2010) Equeenuddin et al. (2010) Sahoo etal. (2012) Tao et al. (2012)... 

Bell FG, Bullock SET, Hdlbich TFJ, Londsay P (2001) Environmental impacts associated with an abandoned mine in the Witbank Coalfield, South Africa. Int J Coal Geol 45 195-216... 

A map of the different coal fields of South Africa with (a) representing the Waterberg field, (b) the Free StateA/ereeniging field, (c) the Mpumalanga/Witbank field, and (d) the Kwazulu-Natal/ Ulundi field. (Adapted from Ref. 7.)... 

The coal used in this investigation originated from the Landau mine in the Mpumalanga/Witbank area and was specially selected due to the different sulfur content (0.6 and 3.0%, respectively) observed in the selected coal samples, the sulfur being present mainly in the mineral pyrite (see Fig. 30.10). The Mossbauer parameters are shown in Table 30.2. 

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