Goonyella coal

Fig. 4. H CRAMPS spectra of Goonyella coal with deconvoluted contributions.

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. 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.

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. 

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