XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1413
Generally, to determine PSD, coal samples were sieved over
a series of screens. The PSD data is summarized in Table 1.
WASHABILITY NUMBERS, INDICES, AND
PARAMETERS
Sheared Coal Quality and Associated Issues
The impact of shearing on coal quality has been a subject
of investigation, with past studies presenting conflicting
findings. Coals in the Rocky Mountain region have been
subjected to extensive shearing because of the mountain
formation processes (Bustin, 1982). The strongly sheared
coals tend to be very friable and produce high quantities
of fines during mining and processing (Holuszko, 1992
Holuszko, 1994). Previous research on sheared coal strata
in SE British Columbia highlighted challenges in process-
ing due to minerals being embedded in organic matter,
making separation difficult. Conversely, an internal study
on coal from the studied mine site lithotypes suggested that,
despite increased friability and greater fines production,
washability numbers for sheared coals were not signifi-
cantly affected. In this project, a visual and microscopic
examination of sheared seam was conducted to detect signs
of shearing. The assessment revealed difficulties in verifying
shearing through sample preparation techniques, but some
visual indications, such as increased friability, were noted.
Washability Data by Seam
The geology team at one of the coal operations facing
persistent challenges in washing certain coal seams, drew
general conclusions about classifying seams based on wash-
ability characteristics. Table 2 provides a summary of Wn
for various seams, along with geologists’ rankings derived
from field experience. The observations indicate that Seam
C (not included in Table 1 due to the lack of PSD data)
displayed good washability for Wn range 45–50, while
Seam A exhibited more challenges in terms of washabil-
ity with Wn below 47, with a relatively good character-
istics in the range of Wn 47–70, and very good for Wn
Table 1. Summary of the PSD for Seam A (baseline) and Seam B from various locations
Sample
Location/% of Material
Passing the Size 1 mm 300µm 100µm
Seam A Baseline Sample 65 40 15
Stockpile 1 35 25 13
Stockpile 2 30 17.5 8
Seam B Sample 1 60 35 20
Sample 2 70 45 30
Sample 3 50 25 15
Sample 4 70 40 20
Sample 5 55 30 17.5
Sample 6 40 22 12
Sample 7 50 25 12.5
Sample 8 55 30 18
Table 2. Washability (Wn) information for various coal seams/bulk samples statistics and validation
SEAMID Mean Count Median Range Std Min Max Variance Challenging Good
Very
Good
A 58.84 342 57 174 21.01 12 186 442.57 47 47–70 70
B 44.9 176 43.5 128 14.82 11 139 220.74 42 42–60 60
C 45.53 150 42.5 124 15.36 133 237.66 45–55
D 42.88 73 42 80 15.46 8 88 242.47
E 53.54 71 50 144 22.73 15 159 524.25
F 52.23 151 51 108 16.76 19 127 282.74
G 42.93 57 1.41 43 10.54 20 65 113.1
H 44.77 201 45 73 9.98 14 87 100.06
I 60.5 133 60 75 13.99 21 102 197.28
J 55 29 53 87 15.79 24 111 258.14
K 43.56 9 38 28 9.18 33 61 94.78
Generally, to determine PSD, coal samples were sieved over
a series of screens. The PSD data is summarized in Table 1.
WASHABILITY NUMBERS, INDICES, AND
PARAMETERS
Sheared Coal Quality and Associated Issues
The impact of shearing on coal quality has been a subject
of investigation, with past studies presenting conflicting
findings. Coals in the Rocky Mountain region have been
subjected to extensive shearing because of the mountain
formation processes (Bustin, 1982). The strongly sheared
coals tend to be very friable and produce high quantities
of fines during mining and processing (Holuszko, 1992
Holuszko, 1994). Previous research on sheared coal strata
in SE British Columbia highlighted challenges in process-
ing due to minerals being embedded in organic matter,
making separation difficult. Conversely, an internal study
on coal from the studied mine site lithotypes suggested that,
despite increased friability and greater fines production,
washability numbers for sheared coals were not signifi-
cantly affected. In this project, a visual and microscopic
examination of sheared seam was conducted to detect signs
of shearing. The assessment revealed difficulties in verifying
shearing through sample preparation techniques, but some
visual indications, such as increased friability, were noted.
Washability Data by Seam
The geology team at one of the coal operations facing
persistent challenges in washing certain coal seams, drew
general conclusions about classifying seams based on wash-
ability characteristics. Table 2 provides a summary of Wn
for various seams, along with geologists’ rankings derived
from field experience. The observations indicate that Seam
C (not included in Table 1 due to the lack of PSD data)
displayed good washability for Wn range 45–50, while
Seam A exhibited more challenges in terms of washabil-
ity with Wn below 47, with a relatively good character-
istics in the range of Wn 47–70, and very good for Wn
Table 1. Summary of the PSD for Seam A (baseline) and Seam B from various locations
Sample
Location/% of Material
Passing the Size 1 mm 300µm 100µm
Seam A Baseline Sample 65 40 15
Stockpile 1 35 25 13
Stockpile 2 30 17.5 8
Seam B Sample 1 60 35 20
Sample 2 70 45 30
Sample 3 50 25 15
Sample 4 70 40 20
Sample 5 55 30 17.5
Sample 6 40 22 12
Sample 7 50 25 12.5
Sample 8 55 30 18
Table 2. Washability (Wn) information for various coal seams/bulk samples statistics and validation
SEAMID Mean Count Median Range Std Min Max Variance Challenging Good
Very
Good
A 58.84 342 57 174 21.01 12 186 442.57 47 47–70 70
B 44.9 176 43.5 128 14.82 11 139 220.74 42 42–60 60
C 45.53 150 42.5 124 15.36 133 237.66 45–55
D 42.88 73 42 80 15.46 8 88 242.47
E 53.54 71 50 144 22.73 15 159 524.25
F 52.23 151 51 108 16.76 19 127 282.74
G 42.93 57 1.41 43 10.54 20 65 113.1
H 44.77 201 45 73 9.98 14 87 100.06
I 60.5 133 60 75 13.99 21 102 197.28
J 55 29 53 87 15.79 24 111 258.14
K 43.56 9 38 28 9.18 33 61 94.78