THE MULTI-TECHNIQUE APPROACH

Transcription

1 CHARACTERISATION OF INORGANIC MATTER IN COAL : THE MULTI-TECHNIQUE APPROACH Sanja Potgieter-Vermaak Maledi, N., Wagner, N., Godoi, R. H. M., Potgieter, J. H. Minerals for LIFE conference, 7-9 June 23

2 COAL Boring??? NO there is no other rock like it on Earth ORGANIC MATTER The useful 8% Combustion Coking Liquefaction Methane MINERAL MATTER The troublesome % Dilution Abrasion Slagging and fouling Pollution Minerals for LIFE conference, 7-9 June 23 BUT..

3 Minerals for LIFE conference, 7-9 June 23

4 Coal Composition and current-day Analytical techniques Empirical characteristics (Proximate analyses & CV) H 2 O FC Ash VM Elemental characteristics (Ultimate analyses etc) C, H, O, N, Phos, S, trace elements CV Reflectance (vitrinite) Macerals Minerals Microlithotypes Petrographic components SEM / QEMSCAN XRD Additional analyses characteristics Adapted from Falcon Minerals for LIFE conference, 7-9 June 23

5 Permian age through to mid- Triassic age in the Gondwana basin, reserves spread over the ECCA group in the Karoo super group Main coal reserves - central basin, including Witbank, Highveld, and the Ermelo coal fields Minerals for LIFE conference, 7-9 June 23

6 Minerals for LIFE conference, 7-9 June 23 Witbank Ermelo Proximate analysis (mass %) Ash Volatiles Fixed Carbon Moisture Ultimate analysis (mass %) C H N.4. O S*.6. Forms of sulphur Pyritic.. Mineral sulphur.4.3 Organic sulphur.2.4

7 Concentration (volume %) PETROGRAPHY 2 Witbank 8 Ermelo 6 Mineral (vol%) Witbank Ermelo Clays Sulphides 2..8 Carbonates Other.2.2 Total mineral matter 24.2 Macerals Vitrinite Inertinite Liptinite Total macerals Medium Rank Category Rank C Medium Rank C 4 2 Clays Sulphides Carbonates Other Minerals for LIFE conference, 7-9 June 23

8 Mass % Witbank Ermelo CaO MgO.9.47 K 2 O Na 2 O Fe 2 O TiO Al 2 O SiO Cr 2 O 3.. MnO.4. SO P 2 O XRF bulk analysis of the raw coal Minerals for LIFE conference, 7-9 June 23

9 X R D Mineral Chemical Formula Witbank Ermelo SiO Kaolinite Al 2 (Si 2 O )(OH) Calcite CaCO Aragonite CaCO 3. Dolomite CaMg(CO 3 ) 2.4 Pyrite FeS Muscovite KAl 2 (Si 3 Al)O (OH,F) 2.6 Illite KAl 3 Si 3 O (OH) 2 Alunite KAl 3 (SO 4 ) 2 (OH) 6.7 Gypsum CaSO 4.2H 2 O 2 Raw Coals Anatase TiO 2.2. TOTAL.2. S I R O Q U A N T Minerals for LIFE conference, 7-9 June 23

10 Abundance % Single particle analysis with CCSEM-EDX particles per sample 9% 8% 7% 6% % 4% 3% 2% % Fe Mn Cr Ti Ca K Cl S P Si Al Mg Na % Witbank raw coal R Ermelo raw coal R Witbank HTA Ermelo HTA Witbank LTA Ermelo LTA Minerals for LIFE conference, 7-9 June 23

11 Clustering with chemical boundaries (Kandler et al., 27) Other Sulphates Gypsum Other Ca-rich Carbonates combined Sulphate silicate mixture Silicate 2 Ti-containing Ti-rich 69 Witbank raw coal R Witbank HTA Witbank LTA Ermelo raw coal R Ermelo HTA Ermelo LTA Fe-rich Minerals for LIFE conference, 7-9 June 23

12 Witbank raw coal R Ermelo raw coal R Other Sulphates Other Ca-rich Carbonates combined Sulphate silicate mixture Silicate Ti-containing Ti-rich Fe-rich Minerals for LIFE conference, 7-9 June 23

13 Raman Intensity Raman intensity (arbitrary units) Witbank raw coal R Ermelo raw coal R Micro-Raman Analysis Ermelo Other Sulphates Other Ca-rich Carbonates combined Sulphate silicate mixture Silicate Ti-containing Ti-rich Fe-rich Witbank Anatase Pyrite Rutile Arsenopyrite Pyrite Anatase Rutile Jarosite Calcite Aragonite Dolomite Siderite Arsenopyrite Pyrite E RC marcasite / pyrite E RC stub pyrite Pyrrhotite ref Pyrite ref Marcasite ref Minerals for LIFE conference, 7-9 June 23 Dr. Sanja Potgieter-Vermaak ( Wavenumber (cm- )

14 Minerals for LIFE conference, 7-9 June 23 6 Other Gypsum 4 Other Ca-rich Carbonates combined Sulphate silicate mixture Silicate Ti-containing 2 Ti-rich Fe-rich Witbank HTA Ermelo HTA

15 Raman Intensity (arbitrary units) Raman Intensity (arbitrary units) 6 Other Gypsum Wit HTA anhydrite+aragonite+rutile Aragonite Ref Witbank HTA Anatase Ref E HTA brookite Brookite Ref Ermelo HTA Other Ca-rich Carbonates combined Sulphate silicate mixture Silicate Ti-containing Ti-rich Fe-rich Rutile Ref E HTA Anatase + rutile Wavenumber (cm - ) Minerals for LIFE conference, 7-9 June 23 Rutile ref Anhydrite ref Wavenumber (cm - ) Ermelo Witbank Anatase Anhydrite Rutile Anatase Brookite Rutile Pyrite Brookite Hematite Martite Nephaline Magnetite Calcite Aragonite Hematite Apatite

16 Witbank HTA Ermelo HTA Other Gypsum Other Ca-rich Carbonates combined Sulphate silicate mixture Silicate Ti-containing Ti-rich Fe-rich Ermelo Witbank Anatase Anhydrite Rutile Anatase Brookite Rutile Pyrite Brookite Hematite Martite Nephaline Magnetite Calcite Aragonite Hematite Anatase ref Apatite ref Wit HTA nephaline+anatase+apatite+crednerite Nepheline (NaAlSiO4) ref Apatite-(Ca(PO4)3F) ref Crednerite (CuMnO2) ref 3 4 6Wavenumber 7 (cm- ) 8 9 Minerals for LIFE conference, 7-9 June 23

17 Witbank LTA Ermelo LTA Other Sulphates Gypsum Carbonates combined Sulphate silicate mixture Silicate Ti-containing Ti-rich Fe-rich Minerals for LIFE conference, 7-9 June 23

18 Raman Intensity (arbitrary units) Witbank LTA Ermelo LTA Other Sulphates Gypsum Carbonates combined Sulphate silicate mixture Silicate Ti-containing Ti-rich Fe-rich Ermelo Pyrite Witbank Anhydrite Anatase Rutile Coquimbite Pyrite Hematite Wit LTA anhdr+conquimbite+lepidocrocite Anhydrite Coquimbite (Fe2(SO4)3.9H2O ref Lepidocrocite Wavenumber 8 (cm- ) 2 4 Minerals for LIFE conference, 7-9 June 23

19 In conclusion: Multi-technique approaches to material s characterisation is the way for the future Each technique brings its own new knowledge Careful consideration should be given when only one of these are used in isolation The coal ash could be a useful secondary mineral resource Minerals for LIFE conference, 7-9 June 23