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Company Presentation

Kolkata Unitcompleted its 40 years of

operation

& is proud to be part

of KHD Humboldt Wedag on completion of its 150 years of

operation

HUMBOLDT WEDAG INDIA


BENEFICIATION OF INDIAN NON COKING COAL - ISSUES, PROBLEMS & REMEDIES

Gurudas Mustafi, Vice President, Humboldt Wedag India Pvt. Ltd.Kolkata, India

Beneficiation of Lump Sized CoalIssues

A great percentage of the power station coal mined throughout India has been burned so far without preparation or refuse separation, because the preparation costs are too high or combustible substance is lost in the preparation process. Considering, however, the lower wear in the boiler houses and the increased volume of transportation in the case of prior separation of refuse from the power station coal, then a preparation, at least of the lump sized portion should be profitable. Test regarding the abrasive properties of different types of coal shows that the abrasion and thus the wear are considerably limited due to a separation of refuse from lumpy run-of-mine coal.



Benefits

The removal of a certain portion of the refuse from the uncrushed raw coal offers great advantages for the preparation process, such as for example

- Decrease of power requirements for size reduction.

- Increased yield of graded coal in the case of domestic coal production,

- decreased yield of slurry,

- decrease of ash content in the raw slurry,

- more favourable homogenising properties of the raw coal,

- decreased wear in the concentration machines,

- more favourable utilisation of the preparation capacity, i.e. increased efficiency of the preparation plant.



Remedies

The development of the ROMJIG (Fig 1) opened the possibility, to use a very simple process for

the beneficiation of the lump size coal - the top size is 400 mm and the bottom feed size is 30

mm - by using only one technologically improved machine and some standard auxiliary

equipment.

In fact the idea was to solve the problem of preparing non coking coal, as far as possible dry.

After many years of development, such plants have been installed at Bina and

Kargali and are in operation to separate refuse and clean coal. (Ref : Flow Sheet 1)



Bina / India:Deshaling in front of a Powerplant ROMJIGHUMBOLDT WEDAG INDIA

Flow Sheet 1: ROMJIG Process for Run of Mine Coal


Separation

ROMJIGfor separation of coal 30 - 400 mm


Fig 1: ROMJIG


ResultsBINAPresently from this plant of NCL washed coal is produced with ash < 34% and is linked to Delhi Vidyut Board. In general the results are:

Raw Coal Screen analysis: Products of that plant:Grain size Wt. % Ash % Product Wt. % Ash %

250 - 30 mm 68.78 42.13 deshaled coal 49.76 31.3430 - 0 mm 31.22 38.08 unwashed coal 31.22 38.08

250 - 0 mm 100.0 40.87 saleable product 80.98 33.94Refuse 19.02 70.37

KARGALIDuring the performance tests conducted over a span of 15 days a series of tests were conducted and following results were computed on an average basis:


350 - 50 mm 45.3 40.75 deshaled coal 34.26 30.750 - 0 mm 54.7 32.56 unwashed coal 54.7 32.56


At a cut density of 1.9, the average imperfection determined was 0.089



Prospects

The successful employment of a ROMJIG for large refuse separation of

run-of-mine coal opens a wide field of future applications. In view of the

favourable secondary conditions, such as low water and power

consumption, low expenditure for necessary auxiliary equipment this

process stands any time economical compared with other proven

technologies of large refuse separation and is the ideal process, in case

people think of a pit head instalment.



Beneficiation of coarse grain coal

Issues

Whenever the characteristics of the raw coal does not allow, to achieve the

required product quality with the ROMJIG by only washing the lump size coal,

the grain size of beneficiation has to be reduced. Reasons can be the grain size

distribution, when the amount of material < 30 mm is more and the ash content

of this fraction too high.



Remedies

This leads immediately to the beneficiation of coarse coal by means of Batac® Jig (Fig 2)

or Heavy Media Teska® Separator / Heavy Media Bath (Fig 3).

A typical process for such a jig plant requires only very few equipment while some

additional equipment and the magnetite circuit essentially comprising of magnetizer,

primary & secondary magnetic separators and de-magnetizer are involved in such a HM

Separator / Bath plant. The raw coal with a top size of 75 (100) mm is at first screened

at 13 / 6 mm. The coarse product 75 (100) – 13 / 6 mm is fed either to the Batac jig or

Heavy Media Teska Separator / H.M.Bath, where it is separated into refuse and clean

coal and un-washed fraction (-) 13 / 6 mm mixed with Clean Coal. (Ref : Flow Sheets 2

& 3)

The process is closed by means of a combination of cyclones, filters & thickener (Ref :

Flow Sheets 5 or 8)

The top size can be reduced to 50 mm depending on the grain size distribution.



raw coal

+ 75 mm

- 75 mm

refuseclean coal

circulating water

Humboldt Wedag75 - 0 mm

13/6 - 0 mm

Flow Sheet 2: Jigging Process for Coarse Coal

to refuse

Standard-FlowsheetJigging process for Power Station Coal



- 13 mm

Humboldt Wedag

mixed fine coal

clean coal

+ 13 mm

13 -1 mm

1 - 0 mm

13-1 mm

+ 13 mm

13-0 mm

(-)25 mm

Flow Sheet 3: Heavy Medium Process for Coarse Coal

raw coal

+ 13 mm

circulating water

refuse

cleancoal

+25 mm

Standard-FlowsheetHeavy Medium for Power Station Coal

Slurry sump



Separation

Coarse Coal BATAC - JIGfor separation of coal 10 - 150 mm


Fig 2: Batac Jig


SeparationTESKA - Separator

Heavy Medium separation 10 - 150 mm


Fig 3: Teska Bath


Prospects

The Batac jig is so flexible that the bottom washing size can be reduced

from 13 mm to 6 mm or even to 3 mm, without a modification of the flow

sheet. The only problem is the dry screening at the lower sizes, which can

be solved by using the right screening system.

Equally good operating results are achieved with the Heavy Media Teska

Separator / H.M.Bath without reducing the lower size and for which it needs

to be ensured that the media recovery circuit is properly designed and

media of the correct quality & quantity is made available.



ResultsPIPARWARPiparwar washery under Central Coalfields Limited having a capacity of 6.5 mtpa is equipped with two such Batac Jigs, which forms the heart of the plant supplying washed coal of around 82 to 83% yield having ash < 34% to NTPC for their Delhi based power plants. Raw coal presently fed has an ash in the range of 39 to 40%

PRIVATE WASHERIESPlants with Jig and HM Bath for similar application have been set up for private entreprenuers to wash power grade coal in different locations adjacent to MCL, SECL & WCL mines. Some of these are already in operation. (Results attached)Additionally the depth of beneficiation can be increased by adopting further processes, like the combination of coarse and fine coal jigging or combination of coarse coal HM Bath and fine coal HM Cyclone or combination of jigging with heavy media process and at the end the addition of the flotation system, which is relatively seldom in the beneficiation of non coking coal.



ResultsThe ash in raw coal received varies between 34 to 38%. Results shown in both cases are with 38% ash in raw coal but from different mines of WCL. HEAVY MEDIA BATHThe results from a plant installed at Wani supplying washed coal to MSEB are:

Raw Coal Screen analysis: Products of that plant:Grain size Wt. % Ash % Product Wt. % Ash %50 - 13 mm 68.00 37.80 washed coal 41.00 24.1013 - 0 mm 32.00 40.00 unwashed coal 32.00 40.0050 - 0 mm 100.00 38.50 saleable product 73.00 31.07

Refuse 27.00 58.60Operating Cut Density : 1.45 BATAC JIGThe results from a plant installed at Ghugus supplying washed coal to MSEB are:


50 - 6 mm 85.0 37.90 washed coal 49.80 24.606 - 0 mm 15.0 38.13 unwashed coal 15.00 38.13


Operating Cut Density : 1.5



Beneficiation of medium and fine grain coal

Issues

In good coal reserves - preferably in open cast mining - a relatively big amount of

good quality raw coal is dumped, i.e. wasted, due to the selective mining method.

This is the material close to the border between coal seam and shale band, which

contains up to 50% of saleable coal.

Further whenever the characteristics of the raw coal does not allow, to achieve the

required product quality with only washing the coarse coal, the grain size of

beneficiation has to be reduced. Reasons can be the liberation in course of crushing,

grain size distribution, presence of amount of material < 13 / 6 mm is more and the

ash content of the fine material is too high.



Remedies

This leads immediately to the beneficiation of small coal by means of Heavy

Media Cyclones (Fig – 4) or fine coal Batac® Jig (Fig – 5).

World over plants are being installed to process especially such type of

interface material. The process flow sheet of such a plant appears very

simple. The heart of this plant is the HM Cyclone or Batac jig and depth of

beneficiation is again defined by the raw coal characteristics and the product

requirements. Due to this the flow sheets of such plants vary widely. Here we

present a sample of both systems, which can be considered as a standard

for this duty (Ref: Flow Sheets 4,5,6,7 & 8).


Company Presentation Feed ( -) 25 mm Water addition

0.5 - 25 mm E.P

to Thickener E.P

to hydrocyclone stage P to Thickener C.V.

Middlings (-) 25 mm

Over Dense Media Sump

SlurrySump

Clean Coal 0.5 - 25 mm

C.VWater

D..B. addition

Density Guage H.M.Sump Dilute Media Sump

Coal Processing PlantHeavy-Media Cyclone Single Stage ProcessKHD Proj.-Nr.: B40.3610Date: 15.07.2007

Flow Sheet 4: Heavy Medium Single Stage Cyclone Process for Small Coal


Middling (-) 0.5 mm

Coal Processing Plant - Slurry CircuitHeavy-Media Cyclone ProcessKHD Proj.-Nr.: B40.3610Date: 15.07.2007

Process-water Tank

Flow Sheet 5: Slurry Circuit



Feed 0 - 0,5 mm

to finest coal section

(-)25mm25 - 0 mm

0 - 0.5 mm

25 – 0.5 mm

(-)0.5 mm

25 – 0.mmto outgoing middlings conveyor

25 –0.5 mmto outgoing

clean coal conveyor

GEBComp

Coal processing plantBatac Jig Single Stage ProcessKHD Proj.-Nr.: B40.3654Date: 19.07.2007

25 – 0.5 mm

Flow Sheet 6: Batac Jig Single Stage Process for Small Coal



FIG-5

Flow Sheet 7: Batac Jig Single Stage Process for Small Coal with Crushed Refuse for Power Generation


(-) 0.5 mm

Coal beneficiation plantSlurry CircuitKHD Proj.-Nr.: B40.3654Date: 19.07.2007

To common outgoing middlings conveyor




Separation

HMS - Cyclonesfor separation of coal 0 - 50 mm


Fig 4: HM Cyclone


Separation

Fine Coal BATAC - JIGfor separation of coal 0 - 20 mm


Fig 5: Small Coal Batac Jig


Prospects

Such plants having a simple designed process can be very useful

for producing washed coal required for consumers besides power

viz. sponge iron plants, cement plants to name a few.



Results

Coal washeries with both Jig and HM Cyclone process are in operation in JSPL,

BPSL, BSL,Grasim Cement & Gujarat NRE to name a few while ACC, UltraTech

are in the process of setting up their captive coal washeries at different locations

which includes 3 product washery with either two stage H.M.Cyclone process

(Ref: Flow Sheet 9,10 & 11) or combination of jigging with heavy media process

(Ref: Flow Sheet 12 & 13) having provision to operate as and when required one

circuit to produce two products.

More are being set up to wash non coking coal in different locations adjacent to

WCL, MCL & SECL mines by private entrepreneurs to meet the rising demand of

washed coal.



To SlurryPum p & C om pressor

From ExistingSource ofIndustria l W ater

W ashery feed Conv.

(-) 0 .5m m .

(50-

0.5m

m.) (50-0.5m m .)Reject

(50-25m m .)

(-) 0

.5m

m.

To Reject Bunker

(25-0.5m m .)

To Thickener O verflow

From Thickener O verflow Pum p

O .H. Process W ater Tank

Jig O .H .Tank

Coal Hopper

R .P . G ate

V.Feeder

S ieve BendW et Coal Hopper

D eslim ing Screen

Jig S lurry Tank

Sealing & CoolingW ater Pum p

Process W ater Tank

Process M ake-UpW ater Pum p

S INGLE / DO UBLE STAGE JIG CUM CYCLO NE W ASHERY

Subm ersib lePum p

Slurry Feed Pum p To

Hyd

. Cyc

.

J ig B lower

Com p.For Jig

Batac

Buc

ket E

leva

tor

F ixed Screen

Dewatering Screen

S izing Screen

To H .M . Tank For

To Centrifuge at H .M . Section

D ouble Stage W ashing

(For S ingle Stage W ashing)

To Centrifuge at H.M .

W ashing Section (for single

stage washing)

Jig

To C lean coal conv.

Flow Sheet 9: Two Stage Batac Jig & HM Cyclone Process


W ater

W ater

De-

mag

netiz

er

T o S lu rry T ank T o S lurry Tank

(50 -0 .5m m .)

from B a tac J ig

H .M . C yc lone

S ieve B end S ieve B end

D e-pu lp ing &R ins ing S creen

F or M idd lingR ins ing S creen

C en trifuge

T o M idd ling C onv.

D ilu te M ed ia S um p

D ilu te M ed ia P um p

D e-pu lp ing &R insing S creenFor C lean C oa lF or M idd ling C oa l

F or C leanR insing S creen

C en trifugeC lean C oa l

C lean C oa l C onv.

H .M . C yc loneF eed P um p

H .M . S um p

(50-0 .5m m .)

D ense M ed iaT ank

O ver D ense M ed ia P um p

C la rify ing C one

M agnetic S ep .

F rom B atac J ig W ash ing

S ection (25-0 .5 ) (M idd ling)

W ash ing (25-0 .5 m m .)

50-2

5 m

m.

25-0

.5 m

m.

5 0 -25 m m .

D ensity A d jus tingT ank

D ens ity G auge

F rom B a tac J ig

S IN G LE / D O U B LE S TA G E JIG C U M C Y C LO N E W A S H E R Y

T o S lu rry T ank

S pray

Mag

netiz

er

M ed ia

Flow Sheet 10: Two Stage Batac Jig & HM Cyclone Process


+ 0.5mm.

Filtrate

Filtrate

(-)0.5mm.

Slurry Pond

Thicking Hydro Cyclone

Sieve Bend

Check SlurryScreen

From Slurry Feed Pump

Slurry Distributor

Vacuum Filter

Blower

Receiver

MoistureTrap

Vacuum Pump

Filtrate TransferPump

SINGLE / DOUBLE STAGE JIG CUM CYCLONE WASHERY

Tank Thickener O.F.Pump

To J

igO

.H. T

ank

From

Ove

rflow

O

f Jig

O.H

. Tan

k

Slurry Thickener

Middling Coal(Product)

Flocculent Dosing Unit

Thickener U.F.Pump

To Air

To ProcessWater Tank



W a te r

T o S lu rryP u m p & C o m p re s s o r

W A S H E R Y F E E D C O N V E Y O R

F ro m E x is t in gS o u rc e o fIn d u s tr ia l W a te r

R e je c tsC o n ve yo r

(50 -0 m m .)

W a te r

S L U R R Y S U M P

F R E S HW A T E RT A N K C IR C U L A T IN G

W A T E RT A N K

S U R G EH O P P E R

R A C K & P IN IO NG A T E

V IB R A T IN GF E E D E R

W E T T IN G B O X

S IE V E B E N D D E S L IM IN G H E A V Y M E D IAD IS T R IB U T IO NB O XS T A G E -I

H E A V Y M E D IAD IS T R IB U T IO NB O XS T A G E - II

H E A V Y M E D IAS U M PS T A G E - I

H E A V Y M E D IAS U M PS T A G E - II

(U S E D D U R IN G T W O S T A G E O P E R A T IO N )

F L A P G A T E

H E A V Y M E D IAC Y C L O N E S T A G E - I

S IE V E B E N D

D & R S C R E E NS T A G E - I (C L E A N S )

D & R S C R E E NS T A G E - I (R E J E C T S )

S T A G E - I C L E A N C O A LT R A N S F E R R E D T O S T A G E - I I H . M . S U M PD U R IN G T W O S T A G EO P E R A T IO N

D E S L IM E D C O A L T R A N S F E R C O N V E Y O R

S C R E E N

T O H E A V Y M E D IAC Y C L O N E S T A G E - II

T 0 T H IC K E N IN GC Y C L O N E

F R O M D IL U T E M E D IA S U M P S T A G E -II

F R O M T H IC K E N E R O V E R F L O W P U M P

T O D IL U T E M E D IA S U M P S T A G E -II F R O M D . & R . S C R E E N

S T A G E -II

Flow Sheet 12: Two Stage HM Cyclone Process


To S lu rry Tank

S pray

Mag

netiz

er

T o A ir

To P rocessW ate r T ank

W ater

De-

mag

netiz

er

M ed ia

S LU R R Y P O N D S

T H IC K E N E R

M IDD LING S CO NVEYO R

To S lu rry TankTo S lu rry Tank

S IE V E B E N D S IE V E B E N D

H E A V Y M E D IAC Y C LO N E S TA G E - II

D & R S C R E E NS T A G E - II (C LE A N S )

D & R S C R E E NS TA G E - II (M ID D LIN G S )

R IN S IN G S C R E E N(C LE A N C O A L)

R IN S IN G S C R E E N(M ID D LIN G S )

C E N TR IFU G E(C LE A N S )

C E N T R IFU G E(M ID D LIN G S )

D ILU TE M E D IAS U M PS TA G E - II

C LA R IFY IN GC O N E

M A G N E TICS E P A R A TO R

O V E R D E N S E M E D IA S U M P

C LE A N C O A L C O N V E Y O R

M ID D LIN G S C O N V E Y O R

C LE A N C O A L

M ID D LIN G S

TH IC K E N IN GC Y C LO N E

S IE V E B E N D

C H E C K S LU R R YS C R E E N

V A C U U MP U M P

D IS CF ILTE R

F ILTE RB LO W E R

FILT R A TES U M P

E Q U IP M E N T F LO W S H E E TT W O S T A G E H E A V Y M E D IA C O A L W A S H E R Y

TO C IR C U LA T IN G W A TE R TA N K

TO H E A V Y M E D IA D IS T R IB U TIO N B O X S TA G E -I & II

FR O M H E A V Y M E D IA S U M P S TA G E -II

FR O M S LU R R Y S U M P

TO H E A V Y M E D IAD IS TR IB U TIO N B O X S TA G E -II

Flow Sheet 13: Two Stage HM Cyclone Process


Selection of Process

Selection between the HM & jigging process depends on several factors inter-alia the following:

• raw coal characteristics

• washed coal quality required

• use of reject coal

• operating & maintenance cost

• availability of required quality & quantity of magnetite

Both HM & jigging are the proven processes accepted on worldwide basis for such applications.



Conclusions

According to today’s standard it is no longer required or necessary to work

with open washery circuits and to damage the environment as well as to

spoil energy. The described processes for the various applications have

proven their flexibility as well as their acceptance in the coal beneficiation

industry. In future it will be a must throughout the world, to beneficiate the

raw coal before being used to produce power, cement, sponge iron etc. The

users will appreciate the better and consistent coal quality, being fed to their

plants.




THANK YOU !

WE VALUE YOUR COMMENTS

THANK YOU !

WE VALUE YOUR COMMENTS

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