5
A series of tests were performed to evaluate the impact
of operating parameters including air flow rate, wash water
rate and froth depth on product ash and combustible recov-
ery. Further evaluation was performed to define the impacts
of collector and frother dosage on performance. For each
test, timed froth concentrate samples were collected and
representative feed and tailings samples were obtained
from each StackCell to evaluate the circuit mass balance
and performance. All samples were submitted for analysis
including weight percent solids, ash, and sulfur. Finally, the
measured data was reconciled using a numerical technique
that minimizes the sum of squared errors to generate a self-
consistent data set of balanced results for each test.
The results of three individual pilot tests are presented
in Figure 6. As shown for Tests 1, 2 and 3, combustible
recovery in the range of 75% was achievable at a less than
7% product ash.
Also shown in Figure 6, a 75% combustible recovery
was achievable with the StackCell at less than 2 minutes
of residence time. Both the pilot scale product ash versus
combustible recovery and residence time versus combus-
tible recovery data were similar to the bench-scale data.
Accordingly, design boundary conditions were established
using the bench-scale and pilot-scale data to size the
StackCell production unit. To produce 75% combustible
recovery at less than 7% ash content, it was determined that
a carrying capacity of less than 0.04 tph/ft2 and a minimum
residence time of 2 minutes was required.
Commercial Circuit Design
Based on the bench-scale and pilot test results, a StackCell
circuit design was selected for the Leer ultrafines flotation
circuit. For this exercise, feed weight percent solids of 2%,
target concentrate grade of 6.5% ash and the requirement
for two rows of StackCells were specified. Based on the Figure 4. StackCell pilot test circuit feed source within
delime cyclone cluster at Arch Resources’ Leer preparation
plant
Figure 5. StackCell pilot test circuit arrangement at Arch
Resources’ Leer preparation plant
0
20
40
60
80
100
0 4 8 12 16
Product Ash (%)
Test 1
Test 2
Test 3
0
20
40
60
80
100
0 30 60 90 120 150
Flotation Residence Time (sec)
Test 1
Test 2
Test 3
Figure 6. Combustible recovery versus product ash (top) and
residence time (bottom) for StackCell pilot tests
Combustible
Recovery
(%)
Combustible
Recovery
(%)
A series of tests were performed to evaluate the impact
of operating parameters including air flow rate, wash water
rate and froth depth on product ash and combustible recov-
ery. Further evaluation was performed to define the impacts
of collector and frother dosage on performance. For each
test, timed froth concentrate samples were collected and
representative feed and tailings samples were obtained
from each StackCell to evaluate the circuit mass balance
and performance. All samples were submitted for analysis
including weight percent solids, ash, and sulfur. Finally, the
measured data was reconciled using a numerical technique
that minimizes the sum of squared errors to generate a self-
consistent data set of balanced results for each test.
The results of three individual pilot tests are presented
in Figure 6. As shown for Tests 1, 2 and 3, combustible
recovery in the range of 75% was achievable at a less than
7% product ash.
Also shown in Figure 6, a 75% combustible recovery
was achievable with the StackCell at less than 2 minutes
of residence time. Both the pilot scale product ash versus
combustible recovery and residence time versus combus-
tible recovery data were similar to the bench-scale data.
Accordingly, design boundary conditions were established
using the bench-scale and pilot-scale data to size the
StackCell production unit. To produce 75% combustible
recovery at less than 7% ash content, it was determined that
a carrying capacity of less than 0.04 tph/ft2 and a minimum
residence time of 2 minutes was required.
Commercial Circuit Design
Based on the bench-scale and pilot test results, a StackCell
circuit design was selected for the Leer ultrafines flotation
circuit. For this exercise, feed weight percent solids of 2%,
target concentrate grade of 6.5% ash and the requirement
for two rows of StackCells were specified. Based on the Figure 4. StackCell pilot test circuit feed source within
delime cyclone cluster at Arch Resources’ Leer preparation
plant
Figure 5. StackCell pilot test circuit arrangement at Arch
Resources’ Leer preparation plant
0
20
40
60
80
100
0 4 8 12 16
Product Ash (%)
Test 1
Test 2
Test 3
0
20
40
60
80
100
0 30 60 90 120 150
Flotation Residence Time (sec)
Test 1
Test 2
Test 3
Figure 6. Combustible recovery versus product ash (top) and
residence time (bottom) for StackCell pilot tests
Combustible
Recovery
(%)
Combustible
Recovery
(%)