Post on 25-Apr-2018
Center for Advanced Separation Technologies CASTCAST
ADVANCED COAL CLEANING AND COAL RECOVERY
US-India Coal Working Group MeetingApril 4-5, 2006
by
Roe-Hoan YoonVirginia Tech
http://www.castconsort.org
Center for Advanced Separation Technologies CASTCAST
Separation Processes Used for Coal
Ultr
afin
e
SieveBends
Dense Media
Cyclone
BasketCentrifuges
Dense Media Vessel
DewateringScreens
Raw CoalScreens
Coal Spirals Screen-BowlCentrifuges
ClassifyingCyclones
Med
ium
Solid-Solid Solid-LiquidSize-SizeC
oars
eFi
ne
Froth Flotation Disc Filter
Center for Advanced Separation Technologies CASTCAST
SieveBends
BasketCentrifuges
Dense Media Vessel
DewateringScreens
Raw CoalScreens
Smal
lSolid-Solid Solid-LiquidSize-Size
Coa
rse
Fine
Ultr
afin
e
Dense Media
Cyclone
Coal Spirals Screen-BowlCentrifuges
ClassifyingCyclones
Froth FlotationSlimes(-325 M)
In the absence of advanced Solid-Liquid Separation Technologies coal fines are still being discarded.
Center for Advanced Separation Technologies CASTCAST
Impoundments3 billion tons of fine coal
In 713 impoundmentsMostly in Central Appalachia.
Main causeLack of appropriate Separation Technologies
• Solid-Solid (Fine particles)• Solid-Liquid (Dewatering)
Center for Advanced Separation Technologies CASTCAST
Application of Advanced Separation Technologies
Use of advanced separation technologies at Middle Fork
Recovered coalReuse of impoundment
• No new impoundment• No new permits
Then…
…and NowTechnology
Center for Advanced Separation Technologies CASTCAST
5 10 15 20
Ash Content (%)
0
20
40
60
80
100
0
Rec
over
y (%
)
Laboratory ColumnFull-Scale Conventional
Microcel Flotation
Full-Scale Column
ReleaseAnalysis
Center for Advanced Separation Technologies CASTCAST
Microcel at BMA
Center for Advanced Separation Technologies CASTCAST
0%
2%
4%
6%
8%
10%
12%
Ash
(%)
Target
Time (hours)
Cleaner Coal at BMA
Center for Advanced Separation Technologies CASTCAST
New Installations in Australia
Center for Advanced Separation Technologies CASTCAST
Microcel In Australia
Center for Advanced Separation Technologies CASTCAST
An Indian Coal
0 2 4 6 8 10 12 14 160
10
20
30
40
50
60
70
80
90
100
>65 mesh <65 mesh
Cum
. Yie
ld, %
Flotation Time, minutes
Float Separately
Float Together
Center for Advanced Separation Technologies CASTCAST
0
20
40
60
80
100
0 6 12 18 24 30
Product Ash (%)
Com
bust
ible
Rec
over
y (%
)
28 x 100 mesh-100 mesh-325 mesh
Release AnalysisAssam Coal I
Fine coal produces lower-ash coal.
Center for Advanced Separation Technologies CASTCAST
Cos
t of D
ewat
erin
g ($
/t)
Particle Top Size (mm)0 1 2 3 4 5 6 7
0
2
4
6
8
10
from Hucko, 1990
Center for Coal and Minerals Processing
VTVT
Fine coal dewatering is costly.
Center for Advanced Separation Technologies CASTCAST
Advanced Coal Cleaning Technologies at Virginia Tech
Microcel flotationDewatering1. Dewatering aids
• Licensed to Nalco• Pinnacle pond recovery plant
– Due to completion in July 2006
2. Hyperbaric centrifuge• Licensed to Decantor• Pilot-scale tests is ongoing
3. Hyperbaric horizontal belt filter
• Pilot-scale tests is ongoing4. Dewatering by displacement
• An engineering company is exploring commercialization potential
5. Polymer injection system for Screen-bowl centrifuges
• 18 installations
Center for Advanced Separation Technologies CASTCAST
Dewatering fine coal helps you increase revenue.
1230011.86.2637.6Total Plant1132510.514.085.0Fines Circuits1245012.05.0552.6Coarse (1.50 SG)
Heat(Btu/lb, ar)
Ash(%, ar)
Moisture(%, ar)
Clean(tph, ar)Existing Dewatering
1050025.05.025.8Coarse (1.5x1.6 SG)
1230012.45.6659.7Total Plant1185211.010.081.2Fines Circuits
1245012.05.0552.6Coarse (1.50 SG)
Heat(Btu/lb, ar)
Ash(%, ar)
Moisture(%, ar)
Clean(tph, ar)Improved Dewatering
Tonnage Gain = 659.7-637.6 = 22 tphValue = 22 ton/hr x $50/ton x 5,000 hr/yr = $5.5 MM/yr
Great Payback! Dump moisture on steam contracts, it’s 100% inert!
Center for Advanced Separation Technologies CASTCAST
---1.11.42.0
---3.55.51.5
>1.08.812.51.0
6.510.7---0.75
9.615.1---0.5
30% Solids15% Solids5% Solids
Percent Moisture at Specified Feed Solids ContentMb/Mc
Ratio
---1.11.42.0
---3.55.51.5
>1.08.812.51.0
6.510.7---0.75
9.615.1---0.5
30% Solids15% Solids5% Solids
Percent Moisture at Specified Feed Solids ContentMb/Mc
Ratio
By decreasing the top size of the coals cleaned from 1.5 inches to 14 mesh, US can double its reserve for compliance coal (DOE report by Cavallero, et al. 1991)
Results show that dry coal can be obtained without thermal drying.
Fine coal cleaning is good for the country.
Center for Advanced Separation Technologies CASTCAST
Advanced Hydrocyclone
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1 10 100
Particle Size (Microns)
Mas
s Pa
ssin
g (%
)
1.25 Apex, 28 PSI 1.00 Apex, 30 PSI0.75 Apex, 32 PSI1.00 Apex, 26 PSI (Washed)
120 GPM
Center for Advanced Separation Technologies CASTCAST
Electronic Density Tracers
Project: Develop electronic “tags” to monitor performance of density separators.
Status:Tag/antenna system constructed using transponder technology.Automated system accurately detected 98.5% of tracers added, while lower manual count gave a misleading result.Field study indicated potential savings of $1 MM per plant by improving recovery and reducing waste.
Applicability:Coal, Base Metals, Diamond Refuse
DiscardCleanCoal
HMCs
To FineCircuit
CircuitFeed
SizingScreens
Antenna& Tuner
D&RScreens
EDT Addition Acquisition
Computer
ControlModule
MultiplexerUnit
Reader/Interrogator
& TuningBoard
Center for Advanced Separation Technologies CASTCAST
Under Laminar Flow Conditions(Yoon and Mao, JCIS, 1996; Mao and Yoon, IJMP, 1997)
k S Pb= 14
kNdtdN −=
P P P Pc a d= −( )1
Flotation Model
R
θ
UtUr
r
Rb
H
Ve
Vh
Vd
Vt
E10
V
Wad
Hc
k
1ad
k
1
2
b
p72.0
b 'EEWexp1
EEexp
DD
15Re4
23S
41k ⎥
⎦
⎤⎢⎣
⎡⎟⎟⎠
⎞⎜⎜⎝
⎛ +−−⎟⎟
⎠
⎞⎜⎜⎝
⎛−⎟⎟
⎠
⎞⎜⎜⎝
⎛⎥⎦
⎤⎢⎣
⎡+=
Center for Advanced Separation Technologies CASTCAST
Microcel
Microcel Sparger
Center for Advanced Separation Technologies CASTCAST
Pilot-scale testsMoisture reduction
• From 29% to 16%Throughput
• 2-3 times higher200 tons/hr plant is being built by Beard Technologies
Pond recovery at Pinnacle MineWyoming County, WV
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A Solution for Indian Coal
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Energy Policy Act 2005
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Simplified Flowsheet
Heavy MediaCyclone
HydrocycloneSpirals
FrothFlotation
BasketCentrifuge
Screen-BowlCentrifuge
DiscFilter
Coa
rse
Inte
rmed
iate
Fine
Solid-Solid Separation
Raw CoalScreen
Solid-Liquid SeparationSize-Size SeparationIn
cre
asin
g D
iffi
cu
ltie
sIn
cre
asin
g D
iffi
cu
ltie
s
Center for Advanced Separation Technologies CASTCAST
Separation Processes Used for Coal
Ultr
afin
e
SieveBends
Dense Media
Cyclone
BasketCentrifuges
Dense Media Vessel
DewateringScreens
Raw CoalScreens
Coal Spirals Screen-BowlCentrifuges
ClassifyingCyclones
Med
ium
Solid-Solid Solid-LiquidSize-SizeC
oars
eFi
ne
Center for Advanced Separation Technologies CASTCAST
Microcel at BHP
Center for Advanced Separation Technologies CASTCAST
Typical Ash/Moisture in Product Stream
7.58.8
10.87.9
5.1
12.3
25.1
7.4
0
5
10
15
20
25
30
Plus 28 28 x100 Minus 100 Total
Particle Size Class (Mesh)
Perc
ent
AshMoisture
Center for Advanced Separation Technologies CASTCAST
0
20
40
60
80
100
0 6 12 18 24 30
Product Ash (%)
Com
bust
ible
Rec
over
y (%
)
-100 mesh-325 mesh
Release AnalysisAssam Coal II
Center for Advanced Separation Technologies CASTCAST
Hyperbaric Centrifuge
Air pressure
Center for Advanced Separation Technologies CASTCAST
Slurry
AirPneumaticCylinder
Housing
DrainDischarge
Cake Discharge
SealingEdge
CakePressureChamber
Drain PortsCake Port
Seal
TimedRotaryValve
DriveMotor
Belt
Wedge Bars
FeedInlet
ScreenPanelBars
FilterCake
0.1 mmOpening
Rotation
A
A
Scraper
Cross Section A-A
Semi-continuous unit
Center for Advanced Separation Technologies CASTCAST
Dewatering by Displacement (1)(Liquid butane displaces water from coal surface.)
Dry Coal
V
Water
C
Coaland
Water
7
P
V
1
2
3
456
7
6 8
8
9
6
10
11
12
6Dry Coal
V
Water
C
Coaland
Water
7
P
V
1
2
3
456
7
6 8
8
9
6
10
11
12
6
CoalCoal
An engineering company is exploring commercialization potential.
Center for Advanced Separation Technologies CASTCAST
Dewatering Aids (2)Pinnacle plant flowsheet
(due to completion in January 2006)
+1 mm
FeedSizing
Waste
-100 M
CoarseClean
Screen-BowlCentrifuge
Waste
UltrafineColumns
Waste
PrimaryCyclones
ReagentConditioner
UltrafineDisc Filter
UltrafineClean
Waste
FineColumns
ReagentConditioner
FineDisc Filter
FineClean
CleanCyclones
DeslimeCyclones
Two-StageSpirals
-325 M
+100 M
100 x325 M
Center for Advanced Separation Technologies CASTCAST
Hyperbaric Filter Centrifuge Project:
Develop a pressurized (hyperbaric) filter centrifuge for solid-liquid separation.
StatusPilot-scale unit constructed and tested One test reduced moisture from 11.0% to 1.86%.Flotation product from Moss 3, VA
• No air 15.9% moisture• 15 sec air 10.3%• 120 sec air 6.7%
US patent issued6 international patents applied for
Applicability:fine coalMineral finesmunicipal sludgeFoodothers.
DischargeSection
FilterSection
Partition/Outer Seal
DriveMotor
DriveBelt
ReturnLine
3-WayValve
PneumaticCylinder
DischargeRam
FeedLine
SlurryPump
Solenoid
SealAir Inlet
CentrifugeHousing
CentrifugeDrum
Center for Advanced Separation Technologies CASTCAST
Hyperbaric Belt Filter
Project: Development of high efficiency, high pressure belt filter for solid-liquid separation.
Status:Project just beginning, but design and construction of prototype is well underway.Contact with a major equipment producer to further develop, manufacture, and sell the unit.
Applicability:Coal and Minerals, Municipal Waste Sludge, Environmental Applications
Feed Slurry FilterCake
PressureChamber
FilterCloth
GuideRoller
ClearEffluent
FilterBelt Dry
CakeBack
to Feed
Air LockGates
CompressedAir
DriveMotor
Center for Advanced Separation Technologies CASTCAST
Hydrophobic Dewatering Project:
Develop of novel solid-liquid separation process can compete with thermal drying methods.
Status:Process uses recyclable non-polar liquid to displace moisture Bench-scale tests successfully completed with moistures <1%.Concept patent issued and new disclosures expected.Marketing discussions underway with a major engineering firm.
Applicability:Coal and Minerals, Municipal Waste Sludge, Environmental Applications
CondensedNon-Polar
Liquid
DischargeWater
FeedSlurry
Air-Locks
Valve
Valve
Dry CoalPowder
Compressor
PressureReactor
Evaporator
VentGas
Gauges
TestCondition
5 ml P5 ml P + 1 ml E
5 ml P + 12 ul RU 5 ml P + 12 ul FA5 ml P + 120 ul O
Moisture(%)
2.902.171.890.671.15
Yield(%)
89.675.574.249.914.0