XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1431
installations (Arnold et al 2007 Klima et al 2012 Klima
et al 2019).
An example of using new technology was in the devel-
opment of a northern West Virginia coking coal plant. The
original proposed flowsheet incorporated conventional
froth flotation and spirals operating at a high-RD cutpoint.
Test data showed that the –1 +0 mm plant product would
have assayed 11% ash and 1.3% sulfur, thereby rendering it
unsuitable for the coking coal market. Instead, the author
designed a circuit using Reflux Classifiers making a 1.5 RD
separation along with a column flotation circuit incorpo-
rating desulphurization circuitry. This circuitry involved
treating pyrite-rich effluent streams in low-flow spirals. This
removed much pyrite allowing the spiral concentrate (low
sulfur) to be fed to column flotation, producing high recov-
ery of low ash, low sulfur product. The column cells also
produced a much lower ash product than would have been
achieved through conventional flotation. These changes
with respect to the original circuit concepts resulted in the
production of a 7% ash and 1.0 –1.1%% sulfur clean coal
product with excellent coking characteristics. The financial
impact of being able to place the lower-sulfur, lower ash
coal fines into the coking coal market in 2012 was enor-
mous (Bethell et al 2014). The Leer flow sheet follows
(Figure 5). Interestingly, the original concept was to place
desulfurized spiral product only in the secondary (thermal
flotation circuit). However, desulfurization was successful
enough to move the spiral desulfurized product to primary
flotation and the coking coal market.
More recently Arch Resources (Senior management at
Arch Communication 2023) installed a similar desulfur-
ized column flotation circuit at Leer South. On this occa-
sion, low-density cuts were obtained by using low-density
spirals (LD 10 and LC3) in the 1 mm × 0.25 mm size
range. Another northern West Virginian coal producer
(Senior Management Communication 2023) also installed
a new plant using the original Leer desulfurizing/column
flotation technology coupled with the LC3 low-density spi-
rals. By using primary and secondary spirals, high levels of
efficiency and coal recovery have been achieved, producing
acceptable ash and sulfur values for the coking coal market.
SUMMARY
Maximizing the profitability of coal processing and blending
operations requires rigorous initiatives designed to promote
communication between mine supervisors, plant operators
and coal sales personnel. At the management level, proto-
cols must be in place to ensure that market contract speci-
fications are consistent with the ultimate cleanability of a
particular raw coal feedstock. Evaluating optimum shipped
coal quality from a “total margin” basis rather than a “maxi-
mum dollar per tonne” basis generates the greatest benefit
for coal producers. At the plant level, the monitoring of
separator performance via routine sampling/analysis and
the application of best practices is essential to ensure that
coal sizing, cleaning and dewatering processes are operated
and maintained in a manner that can optimize plantwide
efficiency. In particular, regularly scheduled sampling cam-
paigns provide the best guarantee that performance ineffi-
ciencies are identified, and ultimately corrected, in a timely
manner. Plant personnel also need to ensure that constant
incremental qualities are maintained across all cleaning cir-
cuits since this protocol ensures that the highest possible
clean coal yield is being achieved. The conversion of techni-
cal process efficiency indicators into financial gain oppor-
tunities helps to prioritize where resources are best applied
88
90
92
94
96
98
100
Plant A Plant B Plant C Plant D Plant E
Year 1 Year 2 Year 3
Figure 4. Compliance levels with best practice audits for five CPPs
)%(erocSecnailpmoCtiduA
installations (Arnold et al 2007 Klima et al 2012 Klima
et al 2019).
An example of using new technology was in the devel-
opment of a northern West Virginia coking coal plant. The
original proposed flowsheet incorporated conventional
froth flotation and spirals operating at a high-RD cutpoint.
Test data showed that the –1 +0 mm plant product would
have assayed 11% ash and 1.3% sulfur, thereby rendering it
unsuitable for the coking coal market. Instead, the author
designed a circuit using Reflux Classifiers making a 1.5 RD
separation along with a column flotation circuit incorpo-
rating desulphurization circuitry. This circuitry involved
treating pyrite-rich effluent streams in low-flow spirals. This
removed much pyrite allowing the spiral concentrate (low
sulfur) to be fed to column flotation, producing high recov-
ery of low ash, low sulfur product. The column cells also
produced a much lower ash product than would have been
achieved through conventional flotation. These changes
with respect to the original circuit concepts resulted in the
production of a 7% ash and 1.0 –1.1%% sulfur clean coal
product with excellent coking characteristics. The financial
impact of being able to place the lower-sulfur, lower ash
coal fines into the coking coal market in 2012 was enor-
mous (Bethell et al 2014). The Leer flow sheet follows
(Figure 5). Interestingly, the original concept was to place
desulfurized spiral product only in the secondary (thermal
flotation circuit). However, desulfurization was successful
enough to move the spiral desulfurized product to primary
flotation and the coking coal market.
More recently Arch Resources (Senior management at
Arch Communication 2023) installed a similar desulfur-
ized column flotation circuit at Leer South. On this occa-
sion, low-density cuts were obtained by using low-density
spirals (LD 10 and LC3) in the 1 mm × 0.25 mm size
range. Another northern West Virginian coal producer
(Senior Management Communication 2023) also installed
a new plant using the original Leer desulfurizing/column
flotation technology coupled with the LC3 low-density spi-
rals. By using primary and secondary spirals, high levels of
efficiency and coal recovery have been achieved, producing
acceptable ash and sulfur values for the coking coal market.
SUMMARY
Maximizing the profitability of coal processing and blending
operations requires rigorous initiatives designed to promote
communication between mine supervisors, plant operators
and coal sales personnel. At the management level, proto-
cols must be in place to ensure that market contract speci-
fications are consistent with the ultimate cleanability of a
particular raw coal feedstock. Evaluating optimum shipped
coal quality from a “total margin” basis rather than a “maxi-
mum dollar per tonne” basis generates the greatest benefit
for coal producers. At the plant level, the monitoring of
separator performance via routine sampling/analysis and
the application of best practices is essential to ensure that
coal sizing, cleaning and dewatering processes are operated
and maintained in a manner that can optimize plantwide
efficiency. In particular, regularly scheduled sampling cam-
paigns provide the best guarantee that performance ineffi-
ciencies are identified, and ultimately corrected, in a timely
manner. Plant personnel also need to ensure that constant
incremental qualities are maintained across all cleaning cir-
cuits since this protocol ensures that the highest possible
clean coal yield is being achieved. The conversion of techni-
cal process efficiency indicators into financial gain oppor-
tunities helps to prioritize where resources are best applied
88
90
92
94
96
98
100
Plant A Plant B Plant C Plant D Plant E
Year 1 Year 2 Year 3
Figure 4. Compliance levels with best practice audits for five CPPs
)%(erocSecnailpmoCtiduA