1418 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
2007]. In the micro-FTIR mapping, the peaks at 815 cm–1
and 1505 cm–1 can also help with locating the quartz. The
interference of quartz and clay minerals indicates the close
textural association of these phases. Calcite can be identi-
fied by the wavelength number at 881 cm–1 but dolomite
shows very weak signals in the micro-FTIR technique and
is more difficult to identify.
The Micro-FTIR or any bulk FTIR system can be
trained as a tool for fast identification of clay minerals
and possibly to detect an increase in their quantities on
coal samples without tedious sample preparation such as
the preparation required for XRD. The best qualitative
results with improved identification of mineral species are
obtained on the high ash samples due to the interference of
organic matter with the FTIR signal.
XRD and Automated Mineralogy (MLA)
Reverse circulation drill core samples (RC) for Seam A, B
and C were used for the mineral characterization via XRD
and automated mineralogy to subsequently correlate them
with the Wn data sets.
The automated mineralogy method for the MLA is
described by Fandrich et al., 2007 Gu, 2003 Kappes et
al., 2007 and is based on Scanning Electron Microscope
(SEM) backscattered electron (BSE) image analysis and
Energy Dispersive Spectrometry (EDS) an electron beam
micro-spot chemical analysis technique. Coal quantity
measurements allow for predicted ash percentage estima-
tions directly from the automated mineralogy data. The
ash minerals and their relative abundance estimated by
XRD in the raw composites are shown in Table 3 while the
simplified bulk mineralogy determined by MLA is given in
Table 4.
Coal liberation by size was determined by MLA and
is shown for the calculated head samples in Figure 8.
Liberation is defined by particle composition and coal
liberation is defined as the proportion of the total coal
(grouped macerals) that occurs as clean coal grains contain-
ing less than 10% mineral/ash content (examples are shown
in Figure 9). Coal liberation ranged from 60% to 71% in
Table 3. List of minerals identified by XRD. Their idealised chemical formulae and estimated relative
abundance are also given
Mineral Group Mineral Species Idealised Chemical Formulae Relative Abundance
Silicates Quartz SiO2 Primary to major
Kaolinite Al2Si2O5(OH)4 Major to minor
K-feldspar KAl
2 Si
3 O
8 Trace
Phengite (phyllosilicate)
Identified as illite-muscovite
(K,H
3 O)(Al,Mg,Fe)
2 (Si,Al)
4 O
10 [(OH)
2 ,(H
2 O)]
Minor to major
Oxides Magnetite Fe3O4 Trace
Carbonates Calcite CaCO3 Minor to trace
Dolomite CaMg(CO
3 )
2 Minor to trace
Ankerite Ca(Fe,Mg,Mn)(CO
3 )
2 Minor to trace
Siderite FeCO3 Minor to trace
Phosphates Apatite Ca5(PO4)3(OH,F,Cl) Minor to trace
Gorceixite/goyazite/
crandallite
BaAl
3 (PO
4 )(PO
3 OH)(OH)
6 /
SrAl
3 (PO
4 )
2 (OH)
5 ·(H
2 O)/
CaAl
3 (PO
4 )
2 (OH)
5 ·(H
2 O)
Minor to trace
Sulphides Pyrite FeS
2 Minor to trace
Table 4. Simplified normalized bulk mineralogy of the feed
composites from Seams A-C, determined by MLA in wt.%
Seam A
(n=2)
Seam B
(n=4)
Seam C
(n=2)
Coal 74.05 44.15 44.85
Quartz 1.9 7.25 11.1
Muscovite-llite-smectite1 11.9 17.3 14.5
Kaolinite 9.3 25.15 22.65
Other silicates2 1.25 4.23 4.3
Phosphates3 0.75 0.25 0.25
Carbonates &Sulphates4 0.3 1.1 1.55
Sulphides5 ND 0.03 0.1
Oxides6 0.55 0.55 0.7
Total 100.00 100.00 100.00
1 Not easily differentiated by automated mineralogy techniques
and therefore grouped
2 Mainly K-feldspar
3 Apatite and crandallite-group minerals
4 Calcite, ankerite, siderite and dolomite
5 Mainly pyrite
6 Mainly magnetite
ND =not detected
2007]. In the micro-FTIR mapping, the peaks at 815 cm–1
and 1505 cm–1 can also help with locating the quartz. The
interference of quartz and clay minerals indicates the close
textural association of these phases. Calcite can be identi-
fied by the wavelength number at 881 cm–1 but dolomite
shows very weak signals in the micro-FTIR technique and
is more difficult to identify.
The Micro-FTIR or any bulk FTIR system can be
trained as a tool for fast identification of clay minerals
and possibly to detect an increase in their quantities on
coal samples without tedious sample preparation such as
the preparation required for XRD. The best qualitative
results with improved identification of mineral species are
obtained on the high ash samples due to the interference of
organic matter with the FTIR signal.
XRD and Automated Mineralogy (MLA)
Reverse circulation drill core samples (RC) for Seam A, B
and C were used for the mineral characterization via XRD
and automated mineralogy to subsequently correlate them
with the Wn data sets.
The automated mineralogy method for the MLA is
described by Fandrich et al., 2007 Gu, 2003 Kappes et
al., 2007 and is based on Scanning Electron Microscope
(SEM) backscattered electron (BSE) image analysis and
Energy Dispersive Spectrometry (EDS) an electron beam
micro-spot chemical analysis technique. Coal quantity
measurements allow for predicted ash percentage estima-
tions directly from the automated mineralogy data. The
ash minerals and their relative abundance estimated by
XRD in the raw composites are shown in Table 3 while the
simplified bulk mineralogy determined by MLA is given in
Table 4.
Coal liberation by size was determined by MLA and
is shown for the calculated head samples in Figure 8.
Liberation is defined by particle composition and coal
liberation is defined as the proportion of the total coal
(grouped macerals) that occurs as clean coal grains contain-
ing less than 10% mineral/ash content (examples are shown
in Figure 9). Coal liberation ranged from 60% to 71% in
Table 3. List of minerals identified by XRD. Their idealised chemical formulae and estimated relative
abundance are also given
Mineral Group Mineral Species Idealised Chemical Formulae Relative Abundance
Silicates Quartz SiO2 Primary to major
Kaolinite Al2Si2O5(OH)4 Major to minor
K-feldspar KAl
2 Si
3 O
8 Trace
Phengite (phyllosilicate)
Identified as illite-muscovite
(K,H
3 O)(Al,Mg,Fe)
2 (Si,Al)
4 O
10 [(OH)
2 ,(H
2 O)]
Minor to major
Oxides Magnetite Fe3O4 Trace
Carbonates Calcite CaCO3 Minor to trace
Dolomite CaMg(CO
3 )
2 Minor to trace
Ankerite Ca(Fe,Mg,Mn)(CO
3 )
2 Minor to trace
Siderite FeCO3 Minor to trace
Phosphates Apatite Ca5(PO4)3(OH,F,Cl) Minor to trace
Gorceixite/goyazite/
crandallite
BaAl
3 (PO
4 )(PO
3 OH)(OH)
6 /
SrAl
3 (PO
4 )
2 (OH)
5 ·(H
2 O)/
CaAl
3 (PO
4 )
2 (OH)
5 ·(H
2 O)
Minor to trace
Sulphides Pyrite FeS
2 Minor to trace
Table 4. Simplified normalized bulk mineralogy of the feed
composites from Seams A-C, determined by MLA in wt.%
Seam A
(n=2)
Seam B
(n=4)
Seam C
(n=2)
Coal 74.05 44.15 44.85
Quartz 1.9 7.25 11.1
Muscovite-llite-smectite1 11.9 17.3 14.5
Kaolinite 9.3 25.15 22.65
Other silicates2 1.25 4.23 4.3
Phosphates3 0.75 0.25 0.25
Carbonates &Sulphates4 0.3 1.1 1.55
Sulphides5 ND 0.03 0.1
Oxides6 0.55 0.55 0.7
Total 100.00 100.00 100.00
1 Not easily differentiated by automated mineralogy techniques
and therefore grouped
2 Mainly K-feldspar
3 Apatite and crandallite-group minerals
4 Calcite, ankerite, siderite and dolomite
5 Mainly pyrite
6 Mainly magnetite
ND =not detected