Composite WashingComposite Washingof Coals fromof Coals from

Multiple SourcesMultiple Sources

OptimizationOptimizationcase studycase study

CASE STUDYCASE STUDY

9 coals with different washability potential

From seam III to seam VIII

Raw coals were crushed to 75 mm

Only one coal was crushed to 13 mm

Separated into 2 sizes (75-6 & 6-0.5 mm)

Raw Coals

AimTo beneficiate optimally

at an ash level of

16.5 to 17.5 %

Raw coal characteristics

Raw Coal Ash % Raw Coal Ash %

A 28.4 F 28.8

B 16.0* G 30.8

C 23.6 H 35.4

D 24.3 I 35.3

E 27.5

Circuit “I” Each separately crushed & screened

Coarser 75-6 mm fraction

Smaller 6-0.5 mm fraction

Beneficiate each fractions to 17 % ash

Composite yield - Blended cleans

Circuit “II”

Blending of raw coals

Crushed & screened to,

Coarser 75-6 mm fraction

Smaller 6-0.5 mm fraction

Beneficiate both fractions to 17 % ash

Composite yield - Blended cleans

Results

Composite Washing of individual coals

Optimum sp. gr. ofcut

Elementary ash (%)at cut point

Optimum Cleans (%) Desired compositeclean (%)

75-6 mm 6-0.5mm

Coal

75-6mm

6-0.5mm 75-6 mm 6-0.5mm

Yield Ash Yield Ash Yield Ash

A 1.461 1.484 24.1 24.0 37.8 18.1 61.5 10.6 40.1 17.0

B 1.592 1.597 30.7 30.7 95.1 16.0 92.9 7.8 94.8 15.0#

C 1.621 1.622 35.9 35.9 88.0 18.9 84.1 9.3 87.2 17.0

D 1.612 1.610 33.3 33.2 78.3 17.8 90.9 12.1 79.8 17.0

E 1.483 1.498 24.6 24.6 50.9 18.1 69.3 9.4 52.7 17.0

F - 1.516 - 27.0 - - 49.5 17.0 49.5 17.0*

G 1.422 1.474 22.0 22.1 15.0 19.7 45.6 8.8 18.0 17.0

H 1.428 1.464 21.5 21.5 17.5 18.3 53.1 10.8 19.9 17.0

I 1.454 1.478 23.5 23.5 20.7 18.8 44.5 10.6 23.4 17.0

Average 1.509 1.527 27.0 27.0 50.4 18.2 65.7 10.7 51.7 16.8# Raw coal ash 16.0%* Coal crushed to 13mm and washed with smaller fraction

Global Optimization of Mixed coals

Optimum sp. gr. ofcut

Elementary ash (%)at cut point

Optimum Cleans (%) Desired compositeclean (%)

75-6 mm 6-0.5mm

Coal

75-6 mm 6-0.5mm 75-6 mm 6-0.5mm

Yield Ash Yield Ash Yield Ash

Average 1.500 1.516 26.4 26.4 54.3 18.3 59.8 12.8 55.5 17.0

A 27.3 26.9 49.0 19.5 67.2 11.7 50.8 18.5

B 24.4 24.2 81.1 14.3 88.3 7.1 82.0 13.3

C 26.3 26.1 73.1 16.9 78.8 7.7 74.3 15.0

D 24.1 25.6 61.9 15.0 82.1 10.8 64.3 14.3

E 26.2 26.2 55.6 18.5 71.4 9.8 57.2 17.4

F 27.0 49.4 16.9 49.4 16.9

G 28.5 25.6 46.0 24.6 54.6 11.4 46.9 23.1

H 27.9 26.5 39.6 21.6 62.2 12.7 41.1 20.7

I 27.6 27.0 31.2 21.4 49.9 12.3 33.3 19.8