ADVANCED COAL CLEANING AND COAL … for Advanced Separation Technologies CAST ADVANCED COAL CLEANING...

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


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


SieveBends

BasketCentrifuges

Dense Media Vessel

DewateringScreens

Raw CoalScreens

Smal

lSolid-Solid Solid-LiquidSize-Size

Coa

rse

Fine

Ultr

afin

e

Dense Media

Cyclone


ClassifyingCyclones

Froth FlotationSlimes(-325 M)

In the absence of advanced Solid-Liquid Separation Technologies coal fines are still being discarded.


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 CASTCAST5 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


Microcel at BMA


0%

2%

4%

6%

8%

10%

12%

Ash

(%)

Target

Time (hours)

Cleaner Coal at BMA


New Installations in Australia


Microcel In Australia


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


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


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.


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.


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


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!


---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.


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


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


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 ⎥

⎦

⎤⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛ +−−⎟⎟⎠

⎞⎜⎜⎝

⎛−⎟⎟

⎠

⎞⎜⎜⎝

⎛⎥⎦

⎤⎢⎣

⎡+=


Microcel

Microcel Sparger


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


A Solution for Indian Coal


Energy Policy Act 2005


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


Separation Processes Used for Coal

Ultr

afin

e

SieveBends

Dense Media

Cyclone

BasketCentrifuges

Dense Media Vessel

DewateringScreens

Raw CoalScreens


ClassifyingCyclones

Med

ium

Solid-Solid Solid-LiquidSize-SizeC

oars

eFi

ne


Microcel at BHP


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


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


Hyperbaric Centrifuge

Air pressure


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


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.


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


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


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


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

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