Chapter 4- Results and discussion 85 CHAPTER 4 RESULTS AND DISCUSSION - COAL ANALYSIS In this chapter, the results obtained from the detailed characterisation of coals from mines in the Highveld coalfield as well as the feed coal are discussed as the basis for a better understanding of the mineralogical and chemical properties of the individual components in the feedstocks used for coal conversion processes. 4.1 Chemical analyses of coals from six different Highveld coal mines and feed coal to the coal conversion process 4.1.1 Proximate analysis Proximate analysis data (Table 4.1) show that the samples yield 30-34% volatile matter on a dry ash free (daf) basis. The inherent moisture content of the coals ranged between 2.9% and 3.8% and the total sulphur content from 0.7% to 1.1%. The ash yield of the samples tested (air-dried basis) ranged between 22.1% and 29.7%. Table 4.1: Proximate analyses (air dried basis) of the coals tested Mine Number 1 2 3 4 5 6 Moisture (%) 3.30 2.90 3.20 3.40 3.00 3.80 Ash (%) 24.50 29.00 29.70 27.20 26.80 22.10 Volatile matter (%) 21.70 22.90 21.30 21.50 22.40 23.10 Fixed carbon (%) 50.50 45.20 45.80 47.90 47.80 51.00 Total sulphur (%) 1.10 1.00 0.80 1.00 1.10 0.70 Volatile matter (daf basis, %) 30.10 33.60 31.70 31.00 31.90 31.20 4.1.2 Ultimate analysis Ultimate analysis data (Table 4.2) indicate that the coals contain high proportions of carbon (ranging from 77 - 80% daf), with relatively low concentrations of sulphur (0.9%- 1.6% daf), nitrogen (2-2.2% daf) and hydrogen (ranging from 4-4.6% daf). The oxygen content of the coals (daf basis) was found by calculation to range from 12-16%.
RESULTS AND DISCUSSION - COAL ANALYSIS
Jun 29, 2023
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