PROJECT REPORT TATA STEEL- Rahul

JAMADOBA COAL PREPARATION PLANT, JHARIA DIVISION
INDIAN SCHOOL OF MINES, DHANBAD
A PROJECT REPORT ON
PERFORMANCE ANALYSIS OF DENSE MEDIA CYCLONE
JAMADOBA COAL PREPARATION PLANT
JHARIA DIVISION
DURATION -8TH JUNE -20TH JULY 2015
UNDER GUIDANCE OF- SUBMITTED BY-
SHRI MANISH KUMAR RAHUL SINGH -2012JE1320
(SENIOR MANAGER, JCPP) Mineral Engg. (B.tech+M.tech)
FUEL AND MINERAL ENGINEERING
DEPARTMENT
INDIAN SCHOOL OF MINES
DHANBAD

TATA STEEL-PIONEER IN STEEL MANUFACTURING
ACKNOWLEDGEMENT
I wish to acknowledge the fuel and Mineral Engineering Department for giving the
opportunity to conduct this Industrial training Project.
I also acknowledge the support of Assistant Prof. Shri Pankaj kumar Jain (AP and Training-
in charge) for this Industrial training Project.
I hereby, take this opportunity to express my gratitude to all the people who have helped me in
successfully completing my Industrial training project at Tata Steel, Jharia Division
I express my gratitude to MR.SANJAY SINGH, (General Manager), Tata Steel Jharia Division for giving
this opportunity to me.
I wish to acknowledge the support of Mr G.S TIWARI (Training –in charge) JCPP
I am highly indebted to Mr. PARTHA DAS, (Head JCPP), Tata Steel Jharia Division, for providing
adequate facilities and guidance to complete my Industrial training Project.
I wish to acknowledge the support of SHRI MANISH KUMAR (Senior Manager, JCPP) for this
Industrial training Project
I wish to acknowledge the support of SHRI MAHESH KUMAR ( Manager, JCPP) for this Industrial
training Project
I acknowledge the wonderful support of individuals numerous to mention by name-they
allowed us uninhibited access to their database for the success of the this Industrial training
Project

SUMMARY
At JCPP coal from BCCL mines and Jharia division mines is been washed at ash 18%. The feed
coal of size-1000mm contain ash 30-37% which is first introduced to CHP section where sizing
and de-shaling is done in rotary breaker, from there it introduced to impact crusher and
scalping of feed take place. Finally feed coal of size-15mm is introduced to De-sliming screen of
0.5mm aperture, where+0.5mm is introduced to DM cyclone and -0.5mm is introduced to FF
section. DM cyclone separate clean coal at yield of 52.47% with an ash of 18-21% and reject
coal at yield of 23.28% with an ash of 50-60%.
Optimization of DM cyclone should be done and new digital techniques should be introduced
improve DM cyclone efficiency, proper visual checking of screen should be done so that it can
be checked that the oversize or undersize fraction is not exceeding it standard value, Moreover
proper checking of cyclone pressure should also be done in order to improve cyclone efficiency.
The magnetite media should have atleast 90% of -325mesh size fraction in media, it should be
checked in regular interval that so that proper size distribution.
2

CONTENTS
1.0 CHAPTER ONE –INTRODUCTON
1.1 Introduction to Tata Steel and Jharia division.
1.2 About Jamadoba coal preparation plant (JCPP).
1.3 Quality Performance Report
1.4 Process Flow sheet
1.5 Process Description
1.6 Major Failure and Prevention
2.0 CHAPTER TWO- DENSE MEDIA CYCLONE
2.1 Introduction to DMC
2.2 Design and Separation Mechanism
2.3 Common Problem in DMC
2.4 Parameter effecting DMC performance
2.5 Performance Evolution
2.5.1 Efficiency of Separation
2.5.3 Major Failure Mode, Potential Cause and Prevention
2. 6 Separating Media
2.6.1 Major Losses
2.7 Dense Media cyclone Development and Different Models.
3.0 CONCLUSION
4.0 RECOMMENDATION
5.0 REFERENCE
3

1.0 CHAPTER ONE - INTRODUCTION
1.1 INTRODUCTION TO TATA STEEL AND JHARIA DIVISON
TATA STEEL
Envisioned by the great patriot, Jamsetji Tata, and founded in 1907, Asia's first integrated private
sector steel company, Tata Steel Group is among the top-ten global steel companies with an annual
crude steel capacity of over 29 million tonnes per annum. It is now the world's second-most
geographically-diversified steel producer, with operations in 26 countries and a commercial presence
in over 50 countries. The Tata Steel Group, with a turnover of Rs. 1, 48,614 crores in FY 14, has over
80,000 employees across five continents and is a Fortune 500 company Tata Steel founded India’s
first industrial city, now Jamshedpur, where it established India’s first integrated steel plant in 1907.
The Jamshedpur Works currently comprises of a 9.7 mtpa crude steel production facility and a variety
of finishing mills.Two new Greenfield steel projects are planned in the states of Jharkhand and
Chhattisgarh. Kalinganagar project is underway, it is set to augment production capacity by 3 MnTPA
in the first phase.
Mines and collieries in India give the Company a distinct advantage in raw material sourcing. Iron
Ore mines are located at Noamundi (Jharkhand) and Joda (Odisha) both located within a distance of
150 km from Jamshedpur. The Company’s captive coal mines are located at Jharia and West Bokaro
(Jharkhand)
JHARIA DIVISION
Tata Steel is mining and beneficiating coal from Jharia Division since 1909. The division
produces steel grade prime coking coal and clean it by beneficiation process at its two washeries
– one at Jamadoba group and the other at Bhelatand group, supplying clean coal to Jamshedpur
plant for coke making. The division comprises of five collieries, each nearly 100 years old spread
over 5507.81 acres of leasehold areas in two locations 20km apart, namely Jamadoba group with
Jamadoba Digwadih and 6&7 Pits collieries and Sijua group with Sijua, Malkera and Bhelatand
collieries in it. The country’s Jharia collieries have extractable reserves of prime coking coal at
depths of more than 600 metres.

FIG. NO. 1 – GEOLOGICAL MAP OF JHARIA DIVISION
KEY FEATURES OF JHARIA DIVISION
 First Underground Mines Certified to QMS (ISO 9001:2008), EMS (ISO 14001:2004) and
OHSAS (18001:2007).
 Safety, low manpower productivity, escalating wage cost & deteriorating underground
geo- mining conditions with depth are the challenges. Not amenable to high level
of mechanization and uniqueness in geo-mining condition
 Facilities like Electronically Operated Koppe Winders, which is first time being used at coal
mines in the country, using SDLs in depillaring first time in India for loading of coal,
Programmable Logic Controllers (PLC) based coal beneficiation plant, Heavy Dense media
Cyclones, Tailing dewatering plant, Rotary breaker, Online monitoring of coal ash through
Ash Analyzer, Captive10MW Fluidized Bed Power Plant that uses washery rejects for
power generation are specially implemented in this division.

1.2 ABOUT JAMADOBA COAL PREPARATION PLANT (JCPP)
The need for beneficiation occurs because the coal coming from the collieries has high ash
percentage (30%-37%) but the coke sinter and iron plant at Jamshedpur needs coal of 17.5% ash for
metallurgical purpose. In JCPP, the beneficiation of coal from underground mines coming from
Jamadoba collieries, Digwadih collieries and 6-7 pits is done. Apart from this, coal from mines of
BCCL are also washed during the process of beneficiation four products are generated. The reject is
sent to the power plant where as the tailings are handled as ‘secondary products’
The Jharia division consists of two coal preparation plant known as Jamadoba Coal Preparation
Plant (JCPP), and Bhelatand Coal preparation plant,(BCPP) located in Dhanbad district, which were
commissioned in year 1952 and 1995 respectively,. Out of the total raw Coal, 80% of the coal is
treated through Dense media cyclone and 20 % through the Froth Flotation operation
1.3 QUALITY PERFORMAMNCE REPORT (AVERAGE)
 PLANT OPERATIONAL HOURS
SHIFT PLANT OPERATIONAL
HOURS
RAW COAL
FEED
DMC FF TONNES
A 7:00 7:00 1120
B 7:50 7:50 1273
C 8:00 8:00 1434
TOATL(AVG.) 22.50 22.50 3827
 PRODUCTION AND QUALITY SUMMARY
RAW
COAL
COMP. CLEAN
COAL
TAILING REJECT
TONNES 3827 1995 891 1056
ASH% 32.03 18.19 41.35 51.65
MOISTURE% 6.087 10.18 6.67
YIELD% 52.13 23.28 27.59
CUM. TONNES 59986 31484 11856 18444
CUM. YIELD 52.49 19.76 30.75
CUM. ASH% 33.31 18.18 43.57 53.92
CUM.
MOISTURE %
5.11 10.05 6.52

 SIZE DISTRIBUTION OF RAW COAL , COMPOSITE CLEAN AND REJECT COAL
SIZE
RAW
COAL
COMPOSITE CLEAN
COAL
DMC CLEAN
COAL
DMC REJECTS
WT% ASH% WT% ASH% WT% ASH% WT% ASH%
+20mm
+15mm 4.55 46.25 1.92 21.70 2.56 22.95 5.99 61.72
+ 13 mm 6.91 43.60 3.48 21.38 4.72 21.49 11.29 58.24
+ 10 mm 8.45 40.88 8.03 22.13 13.17 21.95 7.88 56.61
+ 6 mm 19.76 38.94 14.03 21.95 16.53 20.49 28.01 56.12
+ 3 mm 15.49 38.10 13.01 20.28 23.91 20.20 22.01 54.00
+ 1 mm 18.01 35.50 21.66 19.17 30.77 19.23 21.33 54.36
+ 0.5 mm 8.36 30.14 7.30 15.40 7.83 17.63 3.26 51.43
- 0.5 mm 18.46 26.59 30.60 13.84 0.52 17.15 0.25 45.23
Total 100.00 35.99 100.00 18.16 100.00 20.09 100.00 55.71
0.00
20.00
40.00
60.00
80.00
100.00
120.00
+20mm +15mm + 13 mm + 10 mm + 6 mm + 3 mm + 1 mm + 0.5 mm - 0.5 mm Total
RAW COAL WT% RAW COAL ASH% COMPOSITE CLEAN COAL WT% COMPOSITE CLEAN COAL ASH%

1.4 PROCESS FLOWSHEET
1.3.1 Dry process
RAW COAL; SIZE -1000mm Ash; 30-37%
ROTARY DISCARD
-75mm size, Ash; 30-37%
SCALPING
-15mm size, Ash; 30-37%
1.3.2 WET PROCESS
-15mm +0.5mm - 0.5mm
Ash; 30-37% Ash; 20-23%
ROTARY BREAKER
IMPACT CRUSHER
DESLIMING SCREEN
DENSE MEDIA CIRCUIT FLOTATION CIRCUIT
COARSE CLEAN COAL
ASH 19-21%
FINE CLEAN COAL
ASH 12-14%
TAILING
ASH 40-45%
REJECT COAL
ASH 50-60%
CLEAN COAL, ASH %18-19
METTALURGICAL COAL
REJECT COAL, ASH 40-50%,
THERMAL POWER PLANT
SCREEN

GRIZZLY
C4 C5 ROTARY BREAKER ROTARY DISCARD
C2
C106
C3 BC5
SILO1 TO 6 C2 BC2 PAJAMA CHUTE BC5
C6 BC1
CHP SC2 (15mm) CHP SC1
BC6
BC3
BC10 IMPACT CRUSHER
-15mm, Ash- 30-37%
ROM &FEED TO MAIN PALNT
DISTRIBUTER
O/F & U/F
DS SC 207-1 DS SC 207-2 DS SC 207-3 DS SC207-4 FEED TO CELL
+0.5mm FROTH
-0.5mm FEED TO FF SECTION FLOTATION CELL TAILING
MAGNETIC MEDIA+WATER FEED TO DMC CELL-1 &CELL-2(STANDBY) DERRICK SCREEN
MIXER BOX FEED TO BIRD EFFLUENT
208-1 208-2 208-3 208-4 C308
BIRD CENTRIFUGE
DMC 209-1 DMC 209-2 DMC 209-3 DMC 209-4 C309
CSS 211-1 CSS 211-2 CSS211-3 CSS 211-4-
C248 SCREEN BOWL Ash40-45%
RS 215-1 RS215-2 CENTRIFUGE
C213 CLEAN COAL (Ash-18-19%)
C15 FTS & BF REJECT Ash 50-60% REJECT COAL C403 C403A OUTSIDE STOCK
OVERALL FLOWSHEET OF PLANT REJECT BUNKER CLEAN COAL BUNKER C406 C406A
OPEN CAST
MINES
STOCK
YARD
UNDERGROUND
ROM
TANK
200K
HEAD
BOX
CONDITIONER
THICKNER
HIGH RATE
THICKNER
REJECT
STOCK
TAILING
STOCK

1.4 PROCESS DESCRIPTION
The whole Jamadoba coal preparation plant consists of three sections which are as follows:
1. Coal Handling Plant (CHP)
2. Coarse Coal Circuit
3. Fine Coal Circuit
1. COAL HANDLING PLANT (CHP)
In this unit, the coal received from the collieries by means of conveyor belts and trucks undergo primary
crushing in a rotary breaker. It produces coal of -75mm which are then stored in bunker. There are six
bunkers each of 100 ton capacity. The coals from the bunker go to scalping screens. There are two scalping
screens. The undersize of the screens i.e. -15 mm is feed of the main plant where as the oversize undergoes
secondary cruising in the impactor. The product from the impactor is recirculates back to the screens.
 TRUCK DUMP HOPPER:-
 The run of mine coal with segments less than 1000 mm in size is dumped from a
truck dump hopper or a belt network to a belt conveyer. The coal processed in
Jamadoba Washery comes from Jamadoba, 6 & 7 pits and Digwadih (with ash
percentage of 24 to 27%).
 The truck sample is held in a triangular kiln known as ‘tippler’. The raw coal passes
through the screens in the tippler and then goes to rotary breaker
 ROTARY BREAKER:-
 Rotary Breakers are used to break the coal to a predetermined size and remove
rock. It is mostly used by the coal washery plants. From here coal segments less than
75 mm in dimensions are allowed to pass to primary scalping screen. The rest goes
to the stone bunker.
 The rotary principle has the advantage of very low fines production because
undersize coal is immediately screened out. The residual contaminants will get
segregated by the Rotary Breaker which operates on the principle that coal being
lighter will break and get segregated by centrifugal force of the rotary breaker and
pass through the screen inside the Rotary Breaker. Hard stone and shale will not
break under same speed and centrifugal force and hence will be discharged through
the reject chute of the Rotary Breaker.
 Length of rotary breaker = 11 feet
Diameter of rotary breaker = 12 feet
Speed of rotary breaker =16.49 rpm (approx.)
Motor speed = 985 rpm Motor drive = 100 h p V-belt = D 328

FIG NO.2 TOP VIEW OF ROTARY BREAKER
 SILOS:-
 From here the coal moves on to the steel bunkers also known as silos which are
used as a raw coal section.
 STONE BUNKER:-
 The stone bunker is the place where the segments with larger dimensions than 75
mm are deposited and this in turns derives it to dump yard .The stones or rejects of
rotary bunker is collected more or less manually
 IMPACT HAMMER CRUSHER:-
 Impact hammer crushers are hammer mills that are particularly used for primary
and secondary crushing of feed materials from mining and pit and quarry industries.
Reversible impact hammer mill for crushing of medium-hard rock and ore.
 After entering the crushing radius of the rotor, the feeding material is grasped by
the beater heads and crushed by being thrown against the beater head respectively
the impact wall. A second crushing process is carried out in the lower section
between the rotor and the impact wall. The impact hammer crusher is resistant to
foreign matters entering the mechanism, due to the flexible suspension of the
beater arms on the rotor. The adjustment of the impact walls also functions as a
compensation for wear and tear.
 Advantages:-
High and constant capacity
High level of operational safety
Long lifetime
Easy replacement of wear and spare parts
Resistance to foreign matters
High reduction ratio

 DESLIMING SCREEN:-
 In -15x20 mm sized coal, water is seeped through at a very high speed into
it. The mixture of coal and water runs through the distributer bands and
falls on de-sliming screens and separates the particles on the basis of size.
Thus the particle is separated into -15+0.5 mm and -0.5 mm sized coal.
 The undersize (of size -0.5mm) is sent to the fines section or fine coal circuit.
The oversize (of size-15+0.5mm) coarse coal circuit
2. COARSE COAL CIRCUIT
There are mainly three section in coarse coal circuit
 DISTRIBUTION AND DESLIMING SECTION
 CYCLONE SECTION
 MEDIA RECOVERY SECTION
1. DISTRIBUTION AND DESLIMING SECTION
In this section coal feed coming from CHP section is allowed to fall in a distribution box
with water through conveyer and the slurry is distributed to four de-sliming screen.
There are four de-sliming screen named as 207-1, 207-2, 207-3, 207-4.
Aperture of each de-sliming screen is 0.5mm
CHP -15mm
WATER CONVEYER BELT
DS SCREEN 207-1 DS SCREEN 207-2 DS SCREEN 207-3 DS SCREEN 207-4
-0.5mm -0.5mm -0.5 mm
+0.5mm MIXER BOX TOWARD FINE COAL CIRCUIT
DISRIBUTION
BOX
MIXER BOX
208-1
MIXER BOX
208-4
MIXER BOX
208-3
MIXER BOX
208-2

 CYCLONE SECTION
In Cyclone section there are four dense media cyclone named as DMC 209-1,
DMC 209-2, DMC 209-3, DMC 209-4. The coal feed coming from de-sliming screen
(+0.5mm) in allowed to fall in mixer box where fresh separating media (Magnetite ) in
mix with coal and a mixer is prepared which is gravity fed to DMC cyclone. The overflow
(size -15+0.5 mm) is now sent to four Mixer Boxes. In the mixer boxes the coal is mixed with
a media made up of Fe3O4 (Magnetite) suspension in water. This mixture is now sent into
four Dense Media Cyclones (DMC) where separation takes place at specific gravity of about
1.50. The overflow is composed of particles of specific gravity less than 1.50while the
underflow is made up of particles of specific gravity more than 1.50. The overflow is now of
ash content of about 18-19% and is considered as Washed Coal. The underflow is high in ash
content, about 45-55%. The underflow is thus considered to be Reject.
 DENSE MEDIA CYCLONE
 Dense medium cyclones are the conical dynamic dense medium separators
developed by Dutch State Mines in 1940s. These units are mainly used for
coal cleaning applications. Geometrically DM cyclones are similar to
hydrocyclone and generally use magnetite as a media to separate lights from
heavies.
 DM Cyclone operation is very simple and gained popularity many folds over
conventional techniques for treating particularly intermediate size coal i.e. -50
+0.50 mm
FIG.NO.3 CYCLONE AT JCPP FIG.NO.4 CROSS SECTION VIEW OF CYCLONE

MEDIA MEDIA MEDIA MEDIA
DMC 209-1 DMC 209-2 DMC 209-3 DMC 209-4
CLEAN COAL CLEAN COAL CLEAN COAL CLEAN COAL
REJECT COAL REJECT COAL REJECT COAL REJECT COAL
FLOWSHEET NO. 3 FEED TO DMC AND DMC PRODUCT
 MEDIA RECOVERY CIRCUIT
Media from clean coal and reject coal is recoverd first using media recocery sieve bend
of aperture 0.5mm . There are four sieve bend for clean coal ( CCS 211-1, CSS 211-2,
CSS 211-3, CSS 211-4 ) and two for reject coal (RS 215-1, RS 215-2). The diute media is
then collected to receiver tank 1 and 2 , from receiver tank it is passed over primary
magnetic separator where magnetic media is separated from effluent and the
separated media is collected in Dense tank (FTS & BF ). The effluent from Primary
separator is collected to Dilute tank.
KEY FEATURES OF MEDIA RECOVERY CIRCUIT
 Media recovery system greatly reduces the required magnetic separator
capacity. Also, the extremely fine magnetite particles are more effectively
recovered.
 The dilute media is classified in a low pressure cyclone.
MIXER BOX
208-1
MIXER BOX
208-2
MIXER BOX
208-3
MIXER BOX
208-4

 The coarse magnetite in the underflow is fed to a magnetic separetor which
concentrates the magnetite and removes the nonmagnetic. This magnetite
concentrate also flows to the static thickner.
 The magnetite particles settle rapidly to the bottom of the thickner because their high
magnetic charge causes them to form strong flocs. This thickned magnetite is then fed
to the medium sump at a rate generally determined by an automatic mediam specific
gravity control system.
 The thickner overflow, which contain only a few grams of magnetite per gallonn, is used
for rising the cyclone products.
 The concentration of magnetite in the dilute medium may become high enough to
couse the cyclone classifier to act as a dense medim cyclone. Low specific gravity coal
particles then report to the cyclone classifier overflow, settle to the bottom of the
thickner, and discharge with the thickner overflow.
 High concentration of the material lowers the specific gravity of the thickner underflow,
which in turn may cause difficulty in maintaining the specific gravity of the dense
medium.

DMC CLEAN COAL DMC CLEAN COAL DMC CLEAN COAL DMC CLEAN COAL
DMC REJECT COAL DMC REJECT COAL DMC REJECT COAL DMC REJECT COAL
c
DILUTE MAGNETIC MEDIA DILUTE MAGNETIC MEDIA
B
BIRD CENTIFUGE CLEAN COAL
PRIMARY MAGNETIC SEPARATOR
DENSE TANK (FTS) DENSE TANK (BF)
DILUTE TANK
FLOWSHEET NO.4 MEDIA RECOVERY CIRCUIT
CSS 211-1 CSS 211-4CSS 211-3CSS 211-2
REJECT SCREEN
RS 215-1
REJECT SCREEN
RS 215-2
RECEIVER TANK I RECEIVER TANK II
MAINS STANDBY

3.0 FINE COAL CIRCUIT
 The fines section coal of below 0.5mm, which comes from the underflow of de-sliming
screen, is processed. It consists of three Water only Cyclones and two Froth Flotation cells.
Recently cyclones have been stopped in action and only flotation cells are taken into
process for the purpose of beneficiation. Input to fines circuit is the underflow of de-sliming
screen (207-1, 2, 3, 4). The fines coming from underflow of de-sliming screen has size –
0.5mm and of ash percentage 21%-24%.
 The underflow of de-sliming screens is taken first to 200k tank sump from where it is
pumped to head box. From head box the slurry is taken to two conditioners which take it to
two flotation cell (A & B) each containing 4 compartments Presently the quantity of
collector and frother added is 20cc/min and 200cc/min respectively. The slurry in flotation
chambers is agitated with the help of a rotor-stator assembly and air is flown as per
requirement. The froth formed is collected out continuously with the help of paddles and is
taken into froth launder from where it is taken to centrifuge for the process of dewatering.
The tailings are taken out by automatic valve or manual valve and are taken to tailing
thickener.
 In the thickener the tailings got settled down owing to the principle of sedimentation and
are taken out through pump and are sent to tailing ponds from where after settling, tailings
are taken out and sent through trucks. The overflow of tailing thickener is clarified water
which is further reused in the plant.
 The froth from flotation cell is sent to screen bowl centrifuge (manufactured by Bird) for the
dewatering purpose. It consists of a horizontal revolving shell or bowl inside which a screw
conveyor of similar section rotates in the same direction at a slightly lower speed. The feed
pulp is admitted to bowl through the centre tube of revolving screw conveyor. On leaving
the feed pipe the slurry is immediately subjected to high centrifugal force causing the solids
to settle on the inner surface of the bowl at a rate which depends on the rotational speed
employed. Here the bowl is revolved at speed 1000 rpm. The product of the centrifuge is
the dry clean coal (ash=14.5%), effluent and port. The clean coal obtained here has moisture
around 20%. It has been found that effluent carries ultra-fines of low ash content..
 The clean coal obtained from screen bowl centrifuge is mixed with the clean coal coming
from main plant. The ash percentage of composite coal is 18.0% which is then sent to
Jamshedpur

STUDY OF DIFFERENT UNITS OF FINES CIRCUIT
1. Head box:-
The underflow of de-sliming screens of size -0.5mm is taken first to 200k tank sump from
where it is pumped to head box. Head Box has three chambers. The feed is falling from the
pipe on the middle chamber and the two chambers are there to provide feed to both the
flotation panels A and B. Each flotation panel contains 4 flotation cells.
2. Water only cyclone:-
From the main feed pipe coming from the 200k tank sump, a valve is there and from there
another pipe is placed to supply feed to the water only cyclone. The under flow of cyclone is
taken to the conditioning tank of flotation cells of A. The overflow of the cyclone is taken
directly to the froth launder of the flotation cell A. There are 3 cyclones out of which one
was running but recently cyclones have been stopped in action and only flotation cells are
taken into process for the purpose of beneficiation.
3. Conditioning tank:-
` Both the flotation panels A & B consisting four flotation cells, each panel is having two
different conditioning tanks for the feed. In conditioning tank feed is allowed to mix with
reagent i.e. collector. Collector is added in conditioning tank and provided with sufficient
conditioning time which is very important for flotation. Conditioning tank is also having an
agitator for the proper mixing of feed and collector. Collector used here is diesel and its
dosage is 200ml/min. Main function of collector is to promote contact between coal
particles and air bubbles by forming a thin layer/coating over the particle to be floated
4. Flotation cell
In JCPP, Mechanical flotation machines are used with two parallel flotation banks A & B,
each of four flotation cells. Flotation cell gets feed from the feed launder. Flotation cell
consists of agitator rotating at certain rpm and air introduction pipe which gets into agitator
by a hollow pipe and air is introduced at the bottom of the cell and distributed with agitator
forming suspension. Volume of the cell is 8.5m3. Air is controlled depending upon the
product quality.
5. Screen bowl centrifuge:-
The froth from flotation cell is sent to screen bowl centrifuge (manufactured by Bird) for the
dewatering purpose. It consists of a horizontal revolving shell or bowl inside which a screw
conveyor of similar section rotates in the same direction at a slightly lower speed. The feed
pulp is admitted to bowl through the center tube of revolving screw conveyor. On leaving
the feed pipe the slurry is immediately subjected to high centrifugal force causing the solids
to settle on the inner surface of the bowl at a rate which depends on the rotational speed
employed.
6. High rate thickener:-
Effluent and port of Bird centrifuge which mainly contains ultra-fines
(-300mesh) are sent to high rate thickener. The thickener is used to increase the
concentration of suspension by sedimentation, accompanied by the formation of clear
liquid. The underflow of HRT is sent back to centrifuge for

dewatering. The diameter of HRT is 12m and flocculants are used to increase the
sedimentation of particles. One of the problems is that sedimentation of particles in HRT is
not effective and ultra-fines are coming in overflow.
7. Tailing thickener:-
Tailings from the flotation cells are taken to tailing thickener where they got settled down.
These tailings are then taken to tailing ponds from where, after settling, are taken through
trucks for selling. The overflow of thickener is clarified water which is taken to 302 tank and
reused as process water in the main plant.

1.5 MAJOR FAILURES AND PREVENTION
1. COAL HANDLING PLANT (CHP)
 COAL PREPARATION (CRUSHING AND STACKING)
Product (output)
characteristics
requirements
Potential
failure
mode
Potential
effect of
failure
Potential
cause
Prevention
+15mm size fraction
<4.5%
+15mm size
fraction >
4.5%
Lower clean
coal yield
Woven wire
screen cloth
panel
damaged
Visual
checking at
De-sliming
screens
Identification of the shift
wise coal stacked in silos
Mix up of
underground
coal and
opencast coal
misplacement Tripper
position not as
per the coal
received &
stacking the
different coal
in same silo
Manually as
and when coal
changes
-0.5mm size fraction
<20%
-0.5mm size
fraction >20%
Lower clean
coal yield
Crusher gap
setting =
25mm
Checking gap
by measuring
linear length
of adjusting
bolt
 DE-SLIMMING OPERATION
Product
(output)
characteristics
requirements
Potential
failure mode
Potential
effect of
failure
Potential cause Prevention
-0.5mm size
fraction < 2.0 %
in DM cyclone
-0.5mm size
fraction
> 2.0 % in DM
cyclone
Lower
clean yield
coal
Non uniform feeding of
coal throughout the
screens
Unequal distribution of
coal in all the streams
Improper water spray in
screens
Visual checking
at de-sliming
screens
+0.5mm < 11%
in feed FF cell
+0.5mm > 11%
in feed FF cell
Lower
clean yield
coal
coal throughout the
screens
Visual checking
at de-sliming
screens
Measurement
by filler gauge

2. COARSE COAL SECTION
Product
(output)
characteristics
requirements
Potential
failure mode
Potential
effect of
failure
Potential cause Prevention
Misplacement of
clean coal in
rejects < 0.5 %
Misplacement of
clean coal in
rejects < 0.5 %
Lower clean
coal yield
Specific gravity of
media in DM
cyclone not as per
coal blend
Unequal
distribution of coal
in all the streams
Cyclone pressure
< 0.6 Kg /cm2
Cyclone Vortex
Finder > 210 mm
Cyclone nozzles >
190mm
Feed rate > 170
TPH
DCS continuous
Monitoring &
Automatic
correction
Visual checking
at de-sliming
screens
Measurement
by pressure
gauge
Measurement
by measuring
scales
Measurement
by measuring
scales
Continuous
monitoring by
weightometer
& manual
correction
Rejects Ash > 48
%
Rejects Ash < 48
%
Lower clean
coal yield
Specific gravity of
media in DM
cyclone not as per
coal blend
Unequal
distribution of coal
in all the streams
Cyclone pressure <
0.6 Kg /cm2
DCS continuous
Monitoring &
Automatic
correction
Visual checking
at desliming
screens
Measurement
by pressure
gauge

3.0 FINE COAL SECTION
 FINE COAL BENIFICIATION
Product
(output)
characteristi
cs
requirement
s
Potential
failure mode
Potential
effect of
failure
Potential
cause
Prevention
Loss of
magnetite in
rejects < 2kg/t
Coarse clean
coal ash >
19.8%
Loss of
magnetite in
rejects > 2kg/t
High clean
coal ash
High CPT of
clean coal
Cyclone nozzle >
190mm
Improper profile
of primary &
secondary
sprays
Measurement by
measuring scales
Visual checking at
product screens
Fines clean
coal ash = 13.2
– 15.2 %
Fines clean
coal; ash > 15.2
%
Lower clean
coal yield
Frother &
collector dozing
not as per coal
blend
Gap between
rotor & stator >
70mm
Tailing gate level
as per SOP
Manually
Measurement by
measuring scales
Manually
Tailing ash >
44.0 %
Tailing ash < 44
%
Lower clean
coal yield
Gap between
rotor & stator >
70mm
Measurement by
measuring scales
 CLEAN COAL DE-WATERING
Product
(output)
characteristics
requirements
Potential
failure mode
Potential
effect of
failure
Potential
cause
Prevention
Coarse clean coal
moisture < 6.0 %
Coarse clean
coal moisture >
6.0 %
High clean coal
dispatch
moisture
Coarse coal
centrifuge
basket aperture
> 0.7mm
Measurement
by filler gauge
fines clean coal
moisture < 24.0 %
fines clean coal
moisture > 24.0
%
High clean coal
dispatch
moisture
Pool depth of
SCBC > 3.5mm
Manually

2.0 CHAPTER TWO- DENSE MEDIA CYCLONE
2.1 INTRODUCTION
Dense medium cyclones are the conical dynamic dense medium separators developed by Dutch
State Mines in 1940s. These units are mainly used for coal cleaning applications. Geometrically DM
cyclones are similar to hydrocyclone and generally use magnetite as a media to separate lights from
heavies. DMC yclone operation is very simple and gained popularity many folds over conventional
techniques for treating particularly intermediate size coal i.e. -50 +0.50mm. Due to the high
tonnage, a small increase in DMC efficiency can have a large impact on plant profitability
 At tata steel , Jamadoab or any other plant Dense media cyclone (DMC) treats 80% of
the wahsery feed and hence feed rate of the washery can be increased when proper
arrangement are made to increase the feed rate to DM cyclone.
 80% of the feed is washed by DM cyclone (-15 +0.5 mm ) coal doesn’t responed well to
gravity separation process due to the presence of high NGM in the coarse coal feed,
hence the Ep (Ecart propabale) for the DM cyclone operation is also high.
 In Jamadoba there are four DM cyclone named as DMC209-1 , DMC209-2, DMC209-3,
DMC209-4.Earlier terminology was that two cyclone (DMC209-1, DMC209-2) were
considered as FTS section and two( DMC209-3, DMC209-4) were considered as BF section.
 There are four sieve bend named as CSS 211-1, CSS 211-2, CSS 211-3, CSS 211-4 used to
recover the magnetic media from the cyclone product that ‘s clean coal , and there are
two screen named as RS 215-1,RS 215-2 for Recovery of magnetic media from reject coal.
SOME ADVANTAGES OF DMC PROCESS OVER OTHER BENEFICIATION PROCESS
 DMS have the ability to make sharp separations at any required relative density within
the range normally required for coal preparation (and other minerals). A high degree of
efficiency can be achieved even in the presence of high percentages of near density
material (minerals/coal within ±0.1 relative density units of the cut point).
 The rate of separation is much higher the any other bath, Fe> 500*g
 The relative density and thereby the cut point, can be changed at will and fairly quickly to
meet varying requirements.
 A wide range of sizes (+0.1mm – 150mm) can be handled (each size range in different
units), Through put capacity is much higher than any other bath

WASHING OF COAL AT SIZE (-13 +.5 mm) IS MORE ECONOMICAL BECAUSE-
 Lower capital and operating costs in size reduction
 Dewatering is easy
 Material handling and transportation at this size is very easy.
 Lesser environmental problems for tailing disposal
2.2 DESIGN AND SEPARATION MECHANISM
 The constructional features of a cyclone washers are essentially the same as that as a
cyclone thickener or cyclone classifier. The only difference lies in the mode of operation and
the use of medium for separation.
 A cyclone washer consists of a cylindrical part with a tangential feed inlet and a cover plate
with a central outlet pipe at the top. A cone is fitted at the bottom of the cylinder having
suitable aperture at the apex. Over the cover plate there is a chamber with an outlet pipe.
 In a typical dense media cyclone, the mixture of medium and raw coal enters tangentially
near the top of the cylindrical section, thus forming a strong vertical flow. The refuse moves
along th e wall of the cyclone and is discharged through the underflow orifice. The washed
coal moves towards the longitudinal axis of the cyclone and passes through the vortex
finder to the overflow chamber. The washed coal is discharged from this chamber, usually a
tangential outlet.
 The lighter particles reverse its path and move towards the longitudinal axis of the cyclone
and pass through the vortex tinder as a clean coal.
 In a cyclone washer, the force responsible for separation or sorting is the centrifugal which
is many times (50-100) greater than the gravitational force that effects separation of small
or fine particles in conventional washers including jigs and heavy medium units.
 The effect of viscosity in the required separation of small or fines particles in the
conventional baths is eliminated to larger extent in cyclone washers. Thus the application of
centrifugal force in a cyclone washers makes it possible to efficiently treat coal down to a
bottom size of 0.5mm.

OPERATING PRINCIPLE AND RESPONSIBLE FORCES
 The buoyant forces acting on the coal particles cause them to rise the surface, the impurity
particles, being heavier than the liquid they displace, sink to the bottom.
 The magnitude of the gravitational and buoyant forces that separate the particles is a
primary consideration because it governs the velocity with which the particles separate,
which in turn determines the capacity of the separating vessel.
 In a static baths the net forces is written as Fg = (Mp-Mt)g
Where Fg= gravitational force, Mp= mass of particle,Mt= mass of fluid displaced by particle,
and g= acceleration of gravity
 For float particels Fg will have a negative value
 For sink particles Fg will have a positive value
 In a cyclone specific gravity separation results primarily from application and utilization of
similar forces. However, the acceleration of gravity is substituted by a centrifugal
acceleration. Thus the equation changes to
Fc=(Mp – Mt)V2
/R
Where Fc=centrifugal , V= tangential velocity and R= radius of cyclone
 In a typical cyclone the centrifugal force acting on a particle in the inlet region is about 20
times greater than the gravitational force in a static bath , In the conical section of the
cyclone, V is further increased according to the relationship Vr1/2
=constant
 At the apex of the cyclone the acceleration increases to over 200 times greater than gravity.
Thus the forces tending to separate the coal and impurity particles are much greater in
cyclone than in other baths
GENERAL FLOW PATTERN OF THE MEDIUM IN A CYCLONE
 It consist of a descending vortex that originates at the inlet and progresses through the
cyclone to the underflow outlet. As the descending vortex passes down the cyclone, the
part of the fluid peels off toward the center of the cyclone to form an ascending vortex.
The ascending vortex, in turn surrounds a cylindrical air core that encircles the entire
longitudinal axis of the cyclone.
 An additional factor that influence the separation is the progressive increase in specific
gravity of the medium as it descend towards the apex. This increase occurs because of
the centrifugal force also tend to force the medium particles toward the cyclone wall.
Therefore, they are preferentially caught in the descending vortex resulting in

progressively higher concentration of medium particles as the apex is approached. As
might be expected, then, the specific gravity of the medium flowing through the
underflow orifice is higher than the specific gravity of the circulating medium.
Conversely, the specific gravity of the medium passing through the overflow orifice is
less.
FIG. NO.5 IDEALIZED FLOW PATTERN OF MEDIUM IN DM CYCLONE

FIG. NO.6 A 510mm DM CYCLONE
At jamadoba coal washery the DM cyclone is gravity feeding low pressure cyclone
So advantages of gravity feed cyclone
 Degradation was minimized as in pump feed cyclone a lot of degradation of the coal
particles took place inside the pump
 Fluctuation in feed rate were avoided as due to fairly wide fluctuation in the delivery rate of
feed pump, the pressure could not be properly maintained , this lead to the design and
installation of a different setup in which feed was delivered from the overhead tank from
which the pulp gravitated to the cyclone below at constant pressure
 Segregation of coal particles was mostly eliminated.
 Continuous operation was ensured.
 CYCLONEWISE SPECIFIC GRAVITY/LINE GRAVITY
CYCLONES OVERFLOW UNDERFLOW LINE GRAVITY
DMC 209-1 1.320 1.808 FTS 1.393
DMC 209-2 1.312 1.787
DMC 209-3 1.352 1.705 BF 1.410
DMC 209-4 1.349 1.731

2.3 COMMON PROBLEM IN DMC
Field studies indicate that the most common troubles encountered in dense
Medium cyclone circuits include:
 Clean coal vortex overload,
 Excessive particle retention,
 Improper specific gravity cut-point
1. CLEAN COAL VORTEX OVERLOAD
The vortex finder of a dense medium cyclone is somewhat analogous to the overflow lip of a
dense medium vessel. In a vessel, a minimum depth of overflow of 7-10cm must be
maintained to ensure that the largest size particles of clean coal can be hydraulically carried
into the clean product. Likewise, an adequate flow of medium containing the proper amount
of medium particles must pass through the vortex finder of a DMC in order to carry out the
coal particles. If the flow of medium to the overflow is too low, then the excess clean coal
cannot be carried through the vortex finder and will instead report to refuse. This problem is
common in DMCs operated with too large an apex or too low of an inlet pressure.
2. EXCESSIVE PARTICLE RETENTION
The centrifugal field within a DMC causes magnetite to classify and preferentially report to
underflow. The classification causes the underflow SG to be higher than that of the feed and
the overflow SG to be lower than that of the feed. As a result, middlings particles that have a
density between that of the feed SG and overflow SG tend to remain in the cyclone for a
longer period of time than particles outside this density range. Retention is normally
associated with only the coarsest particles and rarely occurs for particles finer than about 15
mm. The retention of coarser middlings may even improve the separation by breaking
middlings into smaller particles that are better liberated and easier to discharge. However,
particle retention can be a serious problem when middlings particles enter the cyclone at a
faster rate than they can be removed. The excessive build-up of middlings eventually leads to a
sudden surge to the underflow that clears the accumulated load of retained material.
Unfortunately, the surge also tends to carry out a portion of low-density clean coal to the
refuse stream.
3. IMPROPER SPECIFIC GRAVITY CUT-POINT
Dense medium cyclones are frequently installed in banks of two or more parallel units in
order to achieve the production requirements of a given plant. For all practical purposes, the
maximum yield from such a circuit can only be achieved when all of the DMCs are operated at
the same specific gravity cut-points. This optimization principle is valid regardless of the
desired quality of the total clean coal product or the ratios of different coals passed through
the circuit.

2.4 PARAMETER AFFECTING DMC PERFORMANCE
A systematic study was conducted to find out the influence of the following variables on the
performance of the cyclone;
 Aperture of overflow and underflow nozzles and their ratio
 Length of the vertex finder tube.
 Feed pressure
 Apex angle of the cone
 Size- grading of the feed Coal
 Pulp ratio
 Specific gravity of separation
1. APERTURE OF OVERFLOW AND UNDERFLOW NOZZLES AND THEIR RATIO
The size variation of the opening and underflow openings influenced the separation most
significantly, It become apparent from the study that by adjusting the opening of the either
of the nozzles, the yield from nill to nearly 100%. However, an optimum ratio of their
combination gave maximum efficiency in separation.
For a 75mm cyclone washer the optimum ratio is 1:5
 INFLUENCE OF SIZE OF CLEANS NOZZLE
Dia. Of Clean
nozzles
9.5 13 15.9 19.1
Clean wt% 35.8 61.3 81.6 91.4
Clean Ash % 7.2 10.8 13.4 16.2
Feed Ash% 19.4 20.3 18.6 19.2
Sp. Gr. of
separation
1.358 1.442 1.450 1.590
 INFLUENCE OF SIZE OF REJECT NOZZLE
Reject nozzle
Dia (mm)
7.9 9.5 11.1 13
Clean Wt% 84.7 67.4 48.2 39.7
Clean Ash% 19.4 15.9 12.2 10.5
Reject Wt% 15.3 32.6 51.8 60.3
Reject Ash % 56.1 49.3 42.6 39.5
Feed Ash % 25.1 26.8 27.9 27.9
Sp. Gr. Of
separation
1.650 1.600 1.470 1.440

2. LENTH OF VERTEX FINDER
Cyclones have been constructed with many different inlet configuration: round, square,
rectangular, inclined, parabolic, cycloidal, etc. Each style has its supporters. The overflow
pipe, commonly called the vortex finder, usually discharges into an overflow chamber. A
tangential exit pipe from this chamber is preferred because it reduces undesirable back
pressure on the cyclone.
3. FEED PRESSURE
Dense media cyclones will operate with inlet pressures as low as 6-8 psi, but pressures of 20
psi and higher are used. About 10-14 psi is perhaps a good average. It is generally not
advisable to operate at inlet pressure as low as 6-8 psi because the recovery of low specific
gravity material and the rejection of impurity is noticeably improved at higher pressure,
especially for the finer sizes.
The pressure can be developed by two methods which are governed by the point where the
de-slimed raw coal enters the cyclone plant
 The simplest, from a materials handling standpoint, is to simply feed the coal
directly into the medium sump. The mixture is then pumped to the cyclone.
 In an alternative method, the medium is pumped to a head tank, which is about 15-
30 (4.57-6.1m) above the cyclone inlet, where the coal is added. The method is
especially applicable for friable coals, because degradation in the medium pump is
eliminated, although an elevator may be required to raise the coal to the head tank
level.
With the both methods, it is important that the medium flow impinge on the incoming feed.
Also, if the raw coal is fed to the medium sump, the coal-medium mixture should be
directed by a feed tube to the strong suction currents at the bottom of the medium sump.
Otherwise, rafting of the fee coal may cause difficulty.
4. APEX ANGLE OF CONE
A cone angle of about 200
appears to be standard, but a few investigator advocate larger
cone angles. Many test in US Bureau of Mines pilot plants, however, indicates that
occasionally the performance of cyclones with larger cone angles were equal, but never
superior, to those with 200
.
5. SIZE GRADING OF FEED COAL
The size distribution play an important role in deciding the performance of the DM cyclone.
The feed should not contain over size fraction, it should be limited to <2% and the undersize
should also be limited to 2% for effective separation. At JCPP the feed distribution after
going through primary process is follows

FEED TO CYCLONE
De-sliming Screen 207-1
From the above plot as the size decrease the ash % also decreases so for an effective separation to
take place in DM cyclone the oversize i.e +15mm should be <4% and undersize i.e -0.5mm should
also be <2%. As in the given case for de-sliming screen 207-3, 207-4 the oversize fraction is >4%,
hence there should be possibility of bad performance of DM cyclone and more misplacement.
0
10
20
30
40
50
60
70
80
90
100
SIZE + 20
mm
+ 15
mm
+ 13
mm
+ 10
mm
+ 6 mm + 3 mm + 1 mm + 0.5
mm
- 0.5
mm
Total
Wt% 0 4.18 9.18 7.30 28.91 21.52 22.23 5.74 0.95 100.00
Ash% 0 48.19 44.40 42.61 36.52 34.93 37.12 33.38 37.21 37.79
207-1 207-2 207-3 207-4
SIZE WT% ASH% WT% ASH% WT% ASH% WT% ASH%
+ 20 mm
+ 15 mm 4.18 48.19 3.95 47.54 4.28 51.25 6.11 49.09
+ 13 mm 9.18 44.40 9.10 45.53 9.12 48.52 10.23 45.33
+ 10 mm 7.30 42.61 8.59 40.11 9.63 40.54 8.76 45.24
+ 6 mm 28.91 36.52 25.55 37.37 32.48 37.60 29.84 36.75
+ 3 mm 21.52 34.93 22.84 36.71 21.44 36.15 19.99 35.19
+ 1 mm 22.23 37.12 24.07 34.25 19.62 34.14 20.42 35.34
+ 0.5 mm 5.74 33.38 5.38 34.52 3.09 27.70 4.28 35.00
- 0.5 mm 0.95 37.21 0.52 29.10 0.34 26.11 0.38 29.55
Total 100.00 37.79 100.00 37.65 100.00 38.13 100.00 38.42

6. PULP RATIO
A medium to coal ratio of about 5:1 is recommended. A ratio as low as 3:1 can be used, but
with some sacrifice in performance. Performance is not improved by using ratios higher
than 5:1, and such dilute feeds involve a number of disadvantages. Pumping and
maintenance costs are both increased, and if the drainage screen are heavily loaded, the
loss of magnetic media may increase because the load on the magnetic separators will be
greater.
For a 150mm cyclone washer
Pulp Ratio 6:1 4.75:1 3.25:1 3:1
Sp. Gr of
separation
1.486 1.487 1.527 1.542
Ecart probable 0.020 0.026 0.042 0.042
NGM 43.4 44.2 48.5 50.0
Capacity of
washer(kg/hr)
70.9 87.7 197.3 270.9
7. SPECIFIC GRAVITY OF SEPARATION
For all practical purposes, the maximum yield from such a circuit can only be achieved when
all of the DMCs are operated at the same specific gravity cut-points. This optimization
principle is valid regardless of the desired quality of the total clean coal product or the ratios
of different coals passed through the circuit.
Specific gravity of
separation
1.486 1.487 1.527 1.542
Ecart probable 0.020 0.026 0.042 0.042

2.5 PERFOMANCE EVOLUTION
Performance evolution of DM cyclone can be done by determining the efficiency of separation
Misplacement of particles, Major failure mode. Misplacement can be defined in the term of
misplaced clean coal in reject coal due to improper separation in DM cyclone.
2.5.1 EFFICIENCY OF SEPARATION
 In continuous production process, however, conditions are usually for away from the
ideal and particles can be misplaced to wrong product for a variety of reasons. The
dominant effect is that of the density distribution of feed. Very dense or very light
particles will settle through the medium and report to appropriate product quickly but
particles of density close to that of medium will move more slowly and may not reach
the right product in the time available for separation
 Other factors also play a role in determining the efficiency of separation
 Fine particles generally separate less efficiently than coarse again because of
their slower settling rates. So fines fraction should be <2%
Observation of De-sliming screen shown below
207-1 207-2 207-3 207-4
SIZE WT% ASH% WT% ASH% WT% ASH% WT% ASH%
-0.5MM 1.82 31.26 0.44 32.47 0.43 29.15 0.72 28.22
As in the above observation it is clear that the size fraction -0.5mm is less
than 2%
 The properties of medium, the design and condition of separating vessel, the
feed condition, particularly feed rate, will all influence the separation
 For an effective separation the size distribution of magnetic media should
contain at least 90% size fraction of -325mesh.
 The efficiency of separation can be represented by the slope of partition or tromp
curve, first introduce by K.F. Tromp (1937). It describe the separating efficiency for the
separator whatever the quality of feed and can be used for estimation of performance
and comparison between separators

 PARTITION CURVE
 Partition curve relates the partition coefficient or partition number, i.e. the
percentage of the feed material of a particular specific gravity which reports
to either the sinks product or the float product (generally for coal), to
specific gravity.
 The ideal partition curve reflects a perfect separation in which all particles
having a density higher than the separating density report to sinks and those
lighter report to floats. There is no misplaced material.
 The partition curve for a real separation shows that efficiency is highest for
particles of density far from the operating density and decrease for particles
approaching the operating density.
 The partition curve for an operating dense medium vessel can be
determined by sampling the sink and float products and performing heavy
liquid test to determine the amount of material in each density fraction. The
range of liquid densities applied must envelope the working density of the
dense medium unit. The result of heavy liquid test on samples of float and
sink from a vessel separating coal(floats) from shale (sinks) are shown in
table
FLOAT AND SINK ANALYSIS OF CYCLONE PRODUCT AT JCPP
FLOAT & SINK FLOAT & SINK
215-1 &2 207-1 TO 4
Sp-Gr WT% ASH% Sp-Gr WT% ASH%
Ft-1.30 0.00 Ft-1.30 1.82 3.42
Ft-1.40 0.37 10.20 Ft-1.40 10.30 10.19
Ft-1.50 0.88 17.24 Ft-1.50 19.73 17.42
Sk-1.50 98.76 56.27 Sk-1.50 68.16 46.07
TOTAL 100.00 55.76 TOTAL 100.00 35.95
WHERE 215-1 & 215-2 REPRESENT SINK FLOAT OF REJECT COAL
AND 207-1, 207-2, 207-3, 207-4 REPRESENT SINK-FLOAT ANALYSIS OF
CYCLONE FEED.
The above highlighted part shows that when separation done at 1.50
specific gravity we are misplacing 1.25% clean coal where matters a lot to
plant economic.

REPRESENT SINK FLOAT OF REJECT COAL
REPRESENT SINK-FLOAT ANALYSIS OF CYCLONE FEED.
0.00
20.00
40.00
60.00
80.00
100.00
Ft-1.30 Ft-1.40 Ft-1.50 Sk-1.50 TOTAL
WT% 0.00 0.37 0.88 98.76 100.00
ASH% 10.20 17.24 56.27 55.76
FLOAT & SINK-REJECT COAL
WT%
ASH%
0.00
20.00
40.00
60.00
80.00
100.00
Ft-1.30 Ft-1.40 Ft-1.50 Sk-1.50 TOTAL
WT% 1.82 10.30 19.73 68.16 100.00
ASH% 3.42 10.19 17.42 46.07 35.95
Chart Title
WT% ASH%

PARTITION CUVRE FOR REAL AND IDEAL CONDITION
 MISPLACEMENT OF PARTICLES
 Misplacement is define as the particles of density close to that of medium will move
more slowly and may not reach the right product in the time available for
separation, Dominant factor for misplacement is density distribution of feed.
 Area between the two curve is called the “error” and is a measure of the degree of
misplacement of particles to the wrong product
 Many partition curves give a reasonable straight-line relationship between the
distribution of 25 and 75%, and slope of line between these distributions is used
show efficiency of the process.
 The probable error of separation or Ecart probable (Ep) is defined as half the
difference between the density where 75% is recovered to sinks and that at which
25% is recovered to sinks
EP= (d75-d25)/2d50
 The density at which 50% of the particle report to sinks is shown as the effective
density of separation which may not be exactly the same as medium density,
particularly for centrifugal separators, in which the separating density is generally
higher than the medium density.
 Lower the Ep, the nearer to the vertical is the line between 25 and 75% and the
more efficient is the separation.
 An ideal separation has a vertical line with an Ep = 0 whereas in the practice the Ep
usually lies in the range the range 0.01-0.10.
 The Ep is not commonly used as a method of assessing the efficiency of separation
in units such as table, spirals, cones, etc. due to many variable (wash water, table
slope, speed, etc.) which can affect the separation efficiency. It is however, ideally
suited to the relatively simple and reproducible DMS process

MISPLACEMENT OF CLEAN COAL TO REJECT AT 1.50 SPECIFIC GRAVITY AT JCPP IS
SHOWN BELOW
CLEAN COAL MISPLACEMENT
FLOAT AT 1.50 20/06/2015 21/06/2015
A B C A B C
FTS WT% 2.70 2.80 3.20 11.00 8.00 2.10
ASH% 19.71 20.87 19.62 19.15 18.80 17.54
BF WT% 0.35 1.40 1.80 6.6 5.50 0.60
ASH% 21.99 21.78 20.28 21.17 30.55 18.38
AVERAGE WT% 1.52 2.10 2.50 8.80 6.75 1.35
ASH% 20.85 21.33 19.95 20.16 19.82 17.96
As per required product characterization misplacement should be less 0.5% but we
see in both FTS and BF section misplacement is more than 0.5%, due improper
feed distribution to all stream , cyclone pressure >0.6 kg/cm3
FTS has more misplacement than BF because
 Improper distribution of feed to FTS section.
 Fines more to FTS i.e >2% due damaged PU panel of 207-1, 207-2
de-sliming screen

2.5.2 MAJOR FAILURE MODE, POTENTIAL CAUSE AND PREVENTION
 MISPLACEMENT OF PARTICLE AND EFFICIENCY OF SEPARTION
 ANALYSIS OF REJECT ASH %
Product
(output)
characteristics
requirements
Potential
failure mode
Potential
effect of
failure
Potential cause /
mechanism of failure
Current process
controls detection /
prevention
Rejects Ash >
48 %
Rejects Ash <
48 %
Lower
clean coal
yield
Specific gravity of media
in DM cyclone not as per
coal blend
Cyclone pressure < 0.6 Kg
/cm2
DCS continuous
Monitoring &
Automatic correction
Visual checking at de-
sliming screens
Measurement by
pressure gauge
Product
(output)
characteristics
requirements
Potential
failure mode
Potential
effect of
failure
Potential cause /
mechanism of failure
Current process
controls detection /
prevention
-0.5mm size
fraction < 2 % in
DM cyclone
-0.5mm size
fraction
> 2 % in DM
cyclone
Lower
clean yield
coal
coal throughout the
screens
Improper water spray in
screens
sliming screens
Misplacement
of clean coal in
rejects < 0.5 %
Misplacement
of clean coal
in rejects < 0.5
%
Lower
clean coal
yield
Specific gravity of media
in DM cyclone not as per
coal blend
Cyclone pressure < 0.6 Kg
/cm2
Cyclone Vortex Finder >
210 mm
Cyclone nozzles > 190mm
Feed rate > 170 TPH
DCS continuous
Monitoring &
Automatic correction
sliming screens
Measurement by
pressure gauge
Measurement by
measuring scales
Measurement by
measuring scales
Continuous monitoring
by weightometer%
manual correction

2.7 SEPARATING MEDIA
Media from clean coal and reject coal is recovered first using media recovery sieve bend of
aperture 0.5mm. There are four sieve bend for clean coal (CCS 211-1, CSS 211-2, CSS 211-3,
CSS 211-4) and two for reject coal (RS 215-1, RS 215-2). The dilute media is then collected
to receiver tank 1 and 2 , from receiver tank it is passed over primary magnetic separator
where magnetic media is separated from effluent and the separated media is collected in
Dense tank (FTS & BF ). The effluent from Primary separator is collected to dilute tank
 KEY FEATURES OF MAGNETIC SEPARATION CIRCUIT
 Media recovery system greatly reduces the required magnetic separator
capacity. Also, the extremely fine magnetite particles are more effectively
recovered.
 The dilute media is classified in a low pressure cyclone.
 The coarse magnetite in the underflow is fed to a magnetic separetor which
concentrates the magnetite and removes the nonmagnetic. This magnetite
concentrate also flows to the static thickner.
 The magnetite particles settle rapidly to the bottom of the thickner because
their High magnetic charge causes them to form strong flocs. This thickened
magnetite is then fed to the medium sump at a rate generally determined by
an automatic mediam specific gravity control system.
 The thickner overflow, which contain only a few grams of magnetite per
gallonn, is used for rising the cyclone products.
 The concentration of magnetite in the dilute medium may become high
enough to couse the cyclone classifier to act as a dense medim cyclone. Low
specific gravity coal particles then report to the cyclone classifier overflow,
settle to the bottom of the thickner, and discharge with the thickner
overflow.
 High concentration of the material lowers the specific gravity of the thickner
underflow, which in turn may cause difficulty in maintaining the specific
gravity of the dense medium.
MAGNETITE SCREEN ANALYSIS IN MEDIA CIRCUIT AT JCPP
Magnetite Content % Magnetite Screen analysis in Media Circuit
FTS BF FTS BF
94.00 94.00 +325 MESH 18.09 15.96
-325 MESH 81.91 84.04

2.7.1 MAJOR LOSSES
 MAGNETITE LOSS IN COARSE CLEAN SCREEN AND REJECT SCREEN
Magnetite
Loss
Clean Coal Screen (GM/KG)
Reject Screen (GM/KG)
211-1 211-2 211-3 211-4 Average 215-1 215-2 Average
0.017 0.03 0.01 0.05 0.03 0.03 0.04 0.04
ASH% 19.38 20.69 20.88 20.71 20.42 57.62 53.61 55.62
 MAGNETITE LOSS IN PRIMARYY SEPARATION
PRIMARY SEPARATOR
Magnetite
Loss
Primary Separator U/F (gm/Lt)
FTS BF Average
0.237 0.073 0.155
 MAGNETITE LOSS IN COARSER BIRD EFFLUENTS
Magnetite loss in coarser bird effluents (gm/Lt) 0.039

2.8 DENSE MEDIA CYCLONE DEVELOPMENT AND DIFFERENT MODEL
DSM (Dutch state mines) recorded many principle guidelines for DM cyclones which are used
to this day. The Guidelines are summarised in table
DSM DM cyclone selection guidelines vs. current trends
PARAMETERS DSM
RECOMMENDATIONS
CURRENT
MANUFACTURING
TRENDS
CYCLONE DIAMETER(DC) <800mm UPTO 1500mm
INLET SIZE(DI) 0.2*DC 0.20, 0.25, 0.30* DC
VORTEX FINDER(DO) 0.43*DC 0.43-0.53* DC
SPIGOT OR APEX (DU) 0.3* DC 0.3-0.4* DC
BARREL LENGTH 0.5* DC 0.5 to 2.5* DC
CONE ANGLE 200 200
CYCLONE FEED
PRESSURE
9* DC 6 DC to 18 DC
 LAMINAR SPIRAL FEED CHAMBER DM CYCLONE DESIGN
 All equipment and resources were provided by Weir Minerals Africa. A material
survey on the current installed DM cyclones indicated that +92% Alumina
ceramic tiles lasted about 1.5 times as long as 27% Cr cast iron.
 Silicon Carbide was excellent in high wear applications like spigots, but if the
entire cyclone was cast in Silicon Carbide, the impact of the slurry caused the
Silicon feed chamber to crack when pump fed.
 The market survey was comprehensive and included the DM cyclone installation
sizes of 72 different operations across Southern Africa. After the market survey,
it was concluded that +92% Alumina tiles were the most cost effective material
of construction for DM cyclones. The 27% Cr Cast iron cyclones are almost
exclusively used in diamond operation
 The operating principle was to reduce the turbulence when feeding the cyclone
in order to increase the residence time of the particles in the classification zone
and, as a result, increase efficiency by reducing the misplaced particles.
 This required the design and fabrication of radius-moulded tiles to follow the
exact profile of the Cavex feed chamber whilst using +92% Alumina tiled
ceramics instead of the traditional natural rubber moulds.

3.0 CONCLUSION
DMS plays a significant role in the global coal industry, This R&D project established that almost all
coal plants use DMS in order to produce saleable yields. The most common DMS separating vessel
was a DM cyclone. Dense medium cyclones are playing vital role in Indian coal preparation plants
and optimising the performance of DM cyclone is imperative for the washeries. DM cyclone
operation can be tuned to achieve optimum result, by manipulating operating and design variables.
Systematic investigation in the operating plants and use of suitable mathematical models can
significantly improve the performance of the dense medium cyclones. At JCPP clean coal of ash 18%
is supplied at yield of 53.76%, where as tailing with ash of 41.54% at a yield of 23.28 and reject of
ash 51.26% with a yield of 27.57% is done, Misplacement of clean coal to reject is about 2% is
observed, to avoid misplacement it is required to have visual checking of de-sliming screen ,
pressure of cyclone at regular interval.

4.0 RECOMMENDATIONS
At JCPP the misplacement of clean coal to reject coal is about 2% which value to a
larger extent , so it is required to stop misplacing clean coal of high value to reject,
For which proper checking of aperture of PU panel of all de-sliming screen should be
done at regular interval so that fine fraction to DMC should not exceed 2%(-0.5mm) and
moreover avoiding oversize(+0.5mm) fraction to go Flotation cell.
Measurement of cyclone pressure in regular interval should be done.

5.0 REFERENCE
 GEOLOGICAL SECTION OF JCPP
 STUDIES ON COAL PREPARATION IN INDIA(CFRI)
 COAL PREPARATION BY LEONARD
 DEVELOPMENT AND EVALUATION OF A DENSE MEDIA CYCLONE FOR THE SOUTHERN AFRICAN
MINERAL AND COAL INDUSTRIES
 https://www.google.co.in/
 https://scholar.google.co.in/
 WILL’S MINERAL PROCESSING TECHNOLOGY

PROJECT REPORT TATA STEEL- Rahul

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