1. a SciTechnol journalResearch Article
Abbas and Muhammad, J Nucl Ene Sci Power Generat Technol 2016, 5:2
http://dx.doi.org/10.4172/2325-9809.1000149
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Journal of Nuclear
Energy Science & Power
Generation Technology
Optimization of Operating and
Design Parameters of Water
only Cyclone using Cherat Coal
in Pakistan
Naeem Abbas* and Khan Muhammad
Abstract
Experiments have been conducted using Water only cyclone to
reduce ash in coal from Cherat region of Khyber Pakhtunkhwa in
Pakistan, varying the associated design and operation parameters.
These parameters were optimized on the bases of yield and the ash
percent in clean coal. It was observed that the vortex finder diameter
has a greatest effect on the clean coal yield. The selected optimum
parameter values were cyclone inclination 30 degree, cyclone inlet
pressure 100 kPa, vortex finder diameter 54 mm, apex diameter 26
mm, solid feed concentration 18% and the vortex finder length 240
mm. By optimization the operating and design parameters of Water
only cyclone the clean coal of less than 15% ash was produced
from 30% raw coal ash. The indigenous coal of the above given
specification can be utilized in cement industry.
Keywords
Water only cyclone; Optimization; Coal
*Corresponding author: Naeem Abbas, Mining engineering department KIU
Gilgit, Pakistan, E-mail: naeemsahar466@yahoo.com
Received: January 20, 2016 Accepted: March 10, 2016 Published: March 14,
2016
to achieved a desired separation [7]. The cut size of WOC decreased
with increase in apex diameter and cyclone inlet pressure [3,18].
The clean coal yield and ash% decreased with increase in cyclone
inclination and solid feed density [9]. Optimization of dimensions
of vortex finder were investigated for determining their effect on cut
size of cyclone [16,18,19]. The clean coal yield decreased with increase
in spigot diameter [18,19]. With increase in cyclone length and solid
feed density, the clean coal yield increased [15]. The pressure drop
decreased with increase in vortex finder length [20,21]. The cyclone
pressure drop is independent of cyclone diameter [22]. In Pakistan
Dendot coal from Punjab province was cleaned through heavy
media separation [20], however due to the media control, magnetic
recovery and high operation cost the heavy media separation has
limited scope [21]. Therefore, in this study coal from Cherat region of
Khyber Pakhtunkhwa was cleaned to make it useful for cement industry
using WOC by varying several design (vortex finder length, vortex finder
diameter, apex diameter) and operation parameters (cyclone inclination,
solid feed density, cyclone inlet pressure). The design and operating
parameters of WOC have not been investigated simultaneously before.
InthefollowingsectiontheMethodology,resultsanddiscussionsandthe
final conclusion is presented.
Methodology
Water only cyclone is characterized by fixed and variable
parameters, presented in Figure 1. The variable parameters are
further classified into design and operational parameters. While, the
parameters cyclone diameter, cyclone length and cone angle were
fixed to 130 mm, 275 mm and120ᴼ
respectively throughout the study.
The values of variable parameters were given in Table 1.
Coal sample of around 400 kg were collected from Cherat coal
mines of Khyber Pakhtunkhwa province in Pakistan, according
to standard sampling procedure (ASTM D-6883). Different tests
were conducted on water only cyclone using fine coal (i.e. 2 mm to
0.25 mm size). A volume of water was added in the feed tank and
weighed quantities of coal were fed to the pulp tank to maintain the
desired pulp densities (10%, 18% and 25%). The pump was started
and the slurry was circulated to form the homogeneous mixture by
closing the bypass valve. Then the bypass valve was set to get the
required pressures (55 kPa, 75 kPa and 100 kPa). The reject particles
accumulated on the conical section and make the WOC as gravity
concentrator rather than classifier. When the steady state of the slurry
was achieved, the samples of the both clean coal product (overflow)
and the reject (underflow) were collected for a fixed period of
time (8 second). The weights of the both over flow and under flow
were recorded. Ash analyses were carried out according to (ASTM
D-31774) standards. The experimental flow sheet is given in Figure 2.
The details of the experimental set up are given in Table 2. A total
of 54 tests were conducted using different combinations of the design
and operational parameters, e.g. experiments were perform with the
given sample by varying the vortex finder length in three level. In
this way all the design and operation parameters were varied. Some
of the test results were given in Table 3. Based on minimum ash%
and maximum yield of clean from each parameter different graphs
were plotted. The optimal values of the different parameters from the
graphs were given in Table 4.
Introduction
Coal is mostly used in power generation and cement industry as
cheap source of energy. Pakistan has one of the largest reserves of
coal but this coal is not utilized optimally because of low grade and
inconsistent quality. At present the cement industry of Pakistan using
five to six million ton of imported coal [1]. The local coal of four to five
million ton is considered as low efficiency coal and used in brick kiln
industry. The main problem associated with this coal is the relatively
high ash content with run of mine coal. The Water Only Cyclone
(WOC) is a gravity based concentrator which is used for coal cleaning
in several countries [2-4]. Despite of relatively lower coal cleaning
efficiency [5-7], it is preferred due to cheaper capital and operating
cost[7-13]andabilitytohandlelargecleaningcapacity[8].Theconical
section of WOC creates its own heavy medium by accumulation of
particles; therefore it needs no external heavy medium like in heavy
media separation [14]. The WOC was used for separation of fine coal
from shale having smaller density difference [15,16]. In WOC the
light particles report to the clean product through the vortex while
the heavier particles passes down the apex as reject [7,17]. The design
and operational parameters of WOC effect its separation efficiency
so a better understanding of effect of these parameters is essential

2. Citation: Abbas N, Muhammad K (2016) Optimization of Operating and Design Parameters of Water only Cyclone using Cherat Coal in Pakistan. J Nucl Ene
Sci Power Generat Technol 5:2.
• Page 2 of 6 •
doi:http://dx.doi.org/10.4172/2325-9809.1000149
Volume 5 • Issue 2 • 1000149
Results and Discussions
Optimization of Apex diameter of water only cyclone for
Cherat coal
The apex diameter must be large to discharge of coarser particle
during the cyclone separation. To investigate the effect of apex
diameter tests were conducted at 10 mm, 20 mm, 26 mm and 40 mm
apex diameters. At apex diameter of 10 mm choking occurred at the
conical section that’s why 10mm apex diameter was discarded. The
ash content decreased (18%, 11% and 12%) with increase in apex
diameter from 20 mm to 40 mm. Similarly the clean coal yield also
decreased (78%, 75% and 60%) with increased in apex diameter. With
increase in apex diameter, the pressure drop is decreased, therefore all
the particles move towards the apex that’s why, the clean coal yield is
decreased (Figure 3).
The increased in apex diameter from 20 mm to 26 mm has a little
effect on clean coal yield. The yield of clean decreased sharply when
the apex diameter is more than 26 mm. The optimum apex diameter
value for these tests was 26 mm.
Effect of Cyclone inclination on the performance of water
only cyclone for Cherat coal
The cyclone inclination is an operating parameter that affects the
quality of clean coal [9]. To investigate the performance of cyclone
inclination, different tests were conducted at cyclone inclinations
of 20 degree, 30 degree, 40 degree and 50 degrees. With increase in
cyclone inclination at 20, 30, 40 and 50 degrees, the ash in clean were
21%, 15%, 13% ,11% and the clean coal yield were 71%, 70%, 65% ,
61% respectively. This was shown in Figure 4. When the inclination is
increases, the gravity force is vertical therefore more particles report
to apex so the clean coal yield is decreased. When the inclination is
decreases, the cyclone becomes horizontal and the gravity force is
along the centripetal force therefore more particles report to clean
coal product that’s why the clean coal yield is increased.
The best yield was observed at 20 degrees cyclone inclination but
the ash percent was maximum. The decreased in ash percent from
20 to 30 degrees cyclone inclination is significantly. The cyclone
inclination from 30 to 50 degrees shows a little effect on ash percent
but the clean coal yield decreased sharply. The optimum cyclone
inclination for these tests was 30 degree.
Effect of cyclone Inlet pressure on the performance of water only
cyclone for Cherat coal
Figure 1: The selected test fixed and variable parameters of WOC for Cherat coal.
Figure 2: Experimental flow sheet of WOC for Cherat coal.
Operational
parameters
Values
Design
parameters
Values (mm)
Inlet pressure (kPa) 55, 75, 100
Vortex finder
diameter
21,40 ,54, 80
Feed density (%) 10,18, 25 Vortex finder length 210, 230 , 240
Cyclone inclination
(degrees)
20, 30, 40, 50 Apex diameter 10, 20, 26,40
Table 1: Variable Operational and design parameter values of WOC for Cherat
coal.
Fixed
Parameter
Variable parameters
Solid feed
density
Vortex
finder
diameter
(mm)
Vortex
finder
length
(mm)
Apex
diameter
(mm)
Cyclone
inclination
(degrees)
Inlet
Pressure
(kPa)
1. 10% 21 110 10 20 55
2. 18% 40 130 20 30 75
3. 25% 54 140 26 40 100
80 40
Table 2: Design of experiments by varying operational and design parameters.

3. Citation: Abbas N, Muhammad K (2016) Optimization of Operating and Design Parameters of Water only Cyclone using Cherat Coal in Pakistan. J Nucl Ene
Sci Power Generat Technol 5:2.
• Page 3 of 6 •
doi:http://dx.doi.org/10.4172/2325-9809.1000149
Volume 5 • Issue 2 • 1000149
To investigate the effect of inlet pressure on the cyclone
performance, different tests were conducted at 55 kPa, 75 kPa, 100
kPa inlet pressures. The separation efficiency of cyclone decreased
with decrease in inlet pressure, higher pressure will increased
the flow rate by reducing retention time [21]. The decreased in
retention time means, increase in separation [23]. The increased
in cyclone inlet pressure produced spiral flow which increases the
clean coal yield.
By varying the inlet pressures from 55 kPa, 75 kPa and 100 kPa
the ash in clean was 12%, 16% and 17%, while the clean coal yield was
65%, 73% and 78% respectively, this was shown in Figure 5. For these
tests, optimum inlet pressure value was 100 kPa.
It was observe from Figure 5, that the change in cyclone inlet
pressure shows no significant effect on ash percent in clean coal.
The decreased in inlet pressure, the volumetric flow rate and the
centrifugal force both are decreased. This causes a decreased in
separation.
Optimization of Vortex finder diameter of water only
cyclone for Cherat coal
The effect of vortex finder diameter is very important because it,
significantly affect the cyclone performance [24-26] and the pressure
drop of the cyclone [15].
To investigate the effect of vortex finder diameter, different tests
were performed by varying the vortex finder diameters at 21 mm, 40
mm, 54 mm and 80 mm. The increase in vortex finder diameter the
clean coal yield and the ash percent both were increased, for example
the ash in clean coal product at vortex finder diameters 21 mm, 40
mm, 54 mm and 80 mm was increased as 9%, 12%,13% and 21%
respectively. The clean coal yield was increased as 52%, 66%, 75 and
76%, this was shown in Figure 6. The optimum vortex finder diameter
value was 54mm. the increase in vortex finder diameter the clean coal
yield is increased, because the large vortex finder diameter provides
greater space to the particles so the volumetric flow rate towards
clean is increased. With increase in vortex finder diameter, the coarse
particles are able to reach the vortex finder wall directly from the inlet
and the coarse particles take a shorter path towards the vortex finder
(Figure 7).
The increase in vortex finder diameter from 21 mm to 54 mm the
clean coal yield increased significantly. From 54 mm to 80 mm there
is a little effect on clean coal yield. The ash value increased rapidly at
vortex of 80 mm. These results showed that the vortex finder diameter
has a great effect on quantity of clean coal, this is inconsistent with
literature. It is reported in the literature that the vortex finder diameter
has significant affect on quality of clean coal [25]. Optimization of
Vortex finder length of water only cyclone for Cherat coal.
The vortex finder length also effect on the cyclone performance
and pressure drop inside the cyclone. Different tests were performed
to investigate the performance of vortex finder length at 210 mm,
230 mm and 240 mm. with increase in cyclone vortex finder length
the clean coal yield was increased as 58%, 65% and 80% and the ash
in clean coal product was increased as 10%, 11% and 15%. With
the increase in the vortex finder length all the particles were sucked
towards clean, this may increase the ash in clean. The increased in
yield with increase in vortex finder length is also due to the hindered
settling which make high bed thickness. The optimum vortex finder
length value for these tests was 240 mm.
The increase in vortex finder length from 210 mm to 230 mm
there is a little change in ash percent. The ash values is maximum at
240 mm vortex finder length but within the limit of clean coal (<17%),
and the clean coal yield is maximum at 240 mm vortex finder. The
best combination of clean coal yield and as percent was observed at
240 mm.
SL.NO Inlet pressure (kPa) Cyclone inclination degrees Feed density (%) VFD (mm) VFL (mm) AD (mm) Clean coal yield (%) Clean coal ash (%)
1. 55 40 18 21 230 20 62 11
2. 75 50 25 21 230 20 61 10
3. 100 30 18 54 230 20 70 12
4. 75 30 25 80 210 26 58 19
5. 100 50 10 54 240 26 55 13
6. 75 40 25 80 240 20 65 17
7. 100 50 10 80 230 20 54 18
8. 100 40 18 40 210 20 66 10
Note: Here VFD is vortex finder diameter, VFL is vortex finder length, AD is apex diameter.
Table 3: Operating and design parameters and cyclone results for Cherat coal.
Parameters Clean Coal yield % Ash % in Clean Optimum Parameter
Cyclone inclination (degrees)
30 70 15
3040 65 13
50 61 11
Inlet Pressure (kPa)
50 65 12
10075 73 16
100 78 17
Solid Feed Density (%)
10 54 9
1818 71 15
25 78 19
Vortex Finder diameter (mm)
21 52 9
54
40 66 12
54 75 13
80 76 21
Vortex Finder length (mm)
210 58 10
240230 65 11
240 80 15
Apex Diameter (mm)
20 78 18
2626 75 11
40 60 12
Table 4: Optimum Operation and Design Parameters of WOC for Cherat coal.

4. Citation: Abbas N, Muhammad K (2016) Optimization of Operating and Design Parameters of Water only Cyclone using Cherat Coal in Pakistan. J Nucl Ene
Sci Power Generat Technol 5:2.
• Page 4 of 6 •
doi:http://dx.doi.org/10.4172/2325-9809.1000149
Volume 5 • Issue 2 • 1000149
in clean was 9%, 15% and 19%, and the clean coal yield was 54%,
71% and 78%. This is because the increase in solid feed density will
increases the density of solids inside the cyclone, so the amount
of solids report to clean coal were increased furthermore some
heavy particles also report to overflow. As the solid concentration
increased beyond 18% the percent reduction in ash content
decreased so 18% solid concentration was appear to be optimum
for highest yield.
Figure 3: Effect of Apex diameter on the ash content and yield of Cherat coal.
Figure 4: Effect of cyclone inclination on the ash content of clean coal and
yield of Cherat coal.
Figure 5: Effect of cyclone inlet pressure on ash content and yield of Cherat
coal.
Figure 6: Effect of vortex finder diameter on the ash content and yield of
Cherat coal
Effect of Solid feed concentration on the performance of
water only cyclone for Cherat coal
The effect of feed solid concentration on cyclone separation is
complicated, the decreased in solid feed concentration will decreases
the particles interaction. The increased in solid feed concentration
increases the particles-particles interaction as well as particles and
wall of cyclone interaction [9]. The increased in solid feed density
also increases the pulp viscosity and the cyclone separate the particles
on the bases of density differences, the increase in solid density also
produce the hindered settling on the conic section that increases
the clean coal yield [26]. Different tests were performed by varying
the feed concentration at 10%, 18% and 25%. With increase in solid
concentration the clean coal yield and the ash content were increased.
When the solid concentration was varied at 10%, 18% and 25% the ash

5. Citation: Abbas N, Muhammad K (2016) Optimization of Operating and Design Parameters of Water only Cyclone using Cherat Coal in Pakistan. J Nucl Ene
Sci Power Generat Technol 5:2.
• Page 5 of 6 •
doi:http://dx.doi.org/10.4172/2325-9809.1000149
Volume 5 • Issue 2 • 1000149
It was observed from Figure 8 that, the solid feed density of 10%
produced a best ash percent (9%) but the clean coal yield is very low (58%).
Thesolidfeeddensityof25%producedhighestyieldofcleanathighestvalue
ofash,whichisnotinthelimitofcleancoal.Asolidfeeddensityvalueof18%
achievedthebestresultofashrejectionandcleancoalyield.
Conclusions
These tests presented that by optimization of the operating and
design parameters like inlet pressure, solid feed density, cyclone
inclination, apex diameter, vortex finder length and vortex finder
diameter of Water only cyclone the clean coal of less than 15% ash
and maximum of 88% yield was obtained. It have been seen from
the results that the clean coal yield and ash percent increased with
increased in vortex finder length, vortex finder diameter, solid feed
density and cyclone inlet pressure. The clean coal yield and ash
percent decreased with increase in cyclone inclination and apex
diameter. The above tests showed that the apex and vortex finder
significantly affect the quality (ash %) and quantity (yield of clean) of
clean coal. It was also concluded that the apex diameter of less than
20 mm is not suitable for 275 mm long WOC. Thus from the above
discussion it can be safely conclude that the maximum efficiency of
WOC is at 18% solid feed density, 54 mm vortex finder diameter, 140
mm vortex finder length, 26mm apex diameter, 100kPa inlet pressure
and 30 degree cyclone inclination.
References
1. Nawab SH (2013) Energy Situation in Pakistan.
2. Kawatra SK, Eisele TC (2001) Coal desulfurization high efficiency preperation
methods. Taylor and Francis.
3. Hore S, Das SK, Singh R, Bhattacharya KK (2012) Efficiency Study of
a Water-Only Cyclone by experimental data modeling techniques when
cleaning Indian fine coal. Int J Coal Geol 32: 193-209.
4. Rao SM, Rao PVT, Choudhury BR (2000) Efficacy of Gravity Separation
as an Alternative to Froth Flotation for Treating Jharia group Coal fines.
In: International Symposium on Processing of fines. NML Jamshedpur,
Jamshedpur.
5. Klima MS, Arnold BJ, Bethell PJ (2012) Chalanges in fine coal processing,
dewatering and disposal. SME.
6. An introduction to water only cyclone.
7. Suresh N, Vanangamudi M, Rao TC (1990) Water distribution in water only
cyclone. Miner Eng 3: 537-541.
8. Leonard JW, Fan W (1988) Clean coal pretreatment and methanol conversion.
National academy of science.
9. Hacifazlioglu H (2012) Optimization of Some Parameters in a Modified Water-
Only Cyclone for Metallurgical Coal Production from High-Ash Fine Coking
Coals. Int J Coal Prep Util.
10. Byron GS (1978) A generalization of distribution data for characterizing the
performance of float-sink coal cleaning devices. Int J Miner Process 5: 1-20.
11. Hore S, Das SK, Godiwalla KM, Bhattacharya KK, Singh R (2008)
Performance characterization of water-only Cyclone for processing high ash
Indian coal. Metals Materials and Processes 20: 265-280.
12. Wang B, Yu AB (2008) Numerical study of the gas–liquid–solid flow in
hydrocyclones with different configuration of vortex finder. Chemical
Engineering Journal 135: 33-42.
13. Motsamai OS (2010) Investigation of the Influence of Hydrocyclone
Geometric and Flow Parameters on Its Performance Using CFD. Advances
and Applications in Mechanical Engineering and Technology 2: 31-57.
14. Hredzák S, Zubrik A, Dolinská S, Lovás M, Jakabský S (2010) Preparation
of low-ash products from Slovak sub-bituminous coals – a material balance
15: 283-289.
15. Rubieraa F, Hallb ST, Shahb CL (1997) Sulfur removal by fine coal cleaning
processes. Fuel 1187-1194.
16. Valverde MRV, Coury JR, Gonçalves JAS (2011) Modeling the Effects of the
Vortex Finder Height on Pressure Drop in the Cyclone Using Computational
Fluid Dynamics. Mecánica Computacional XXX: 525-533.
17. Slechta J, Firth BA (1984) Classification of fine coal with hydrocyclone, Int J
Miner Process 12: 213-237.
18. Ficici F, Ari V, Kapsiz M (2010) The effects of vortex finder on the pressure
drop in cyclone separators. Int J Phys Sci 5: 804-813.
Figure 7: Effect of Vortex finder length on the ash content and yield of
Cherat coal.
Figure 8: Effect of solid feed concentration on sh content and yield of
Cherat coal.

6. Citation: Abbas N, Muhammad K (2016) Optimization of Operating and Design Parameters of Water only Cyclone using Cherat Coal in Pakistan. J Nucl Ene
Sci Power Generat Technol 5:2.
• Page 6 of 6 •
doi:http://dx.doi.org/10.4172/2325-9809.1000149
Volume 5 • Issue 2 • 1000149
23. Majumder AK, Barnwal JP (2011) Processing of coal fines in a water-only
cyclone. Fuel 90: 834-837.
24. Elsayed K, Lacor C (2011) Analysis and Optimization of Cyclone Separators
Geometry Using RANS and LES Methodologies.
25. Hacifazlioglu H (2012) Application of the modified water-only cyclone for
cleaning fine coals in a Turkish washery, and comparison of its performance
results with those of spiral and flotation. Fuel Processing Technology 102:
11-17.
26. Jouhari MBAK, Reedy PSR (2002) Raw marerial preperation for metallurgical
coal. Allied Publisher.
19. Patil DP, Bhaskar KU, Jakhu MR, Rao TC (1997) Removal of graphite from
lead rougher concentrate using water-only cyclones. Int J Miner Process 49:
87-96.
20. Iqbal A, Ehsan N, Khan MI, Ashraf I (2011) Analyses of dense medium
benificiation of Dantot coal for use in cement industry in Pakistan. Journal of
Quality and Technology Management 7: 115-130.
21. Hore S, Das SK, Godiwalla KM, Bhattacharya KK, Singh R (2008) Modeling
performance of water only cyclone as a gravity seperator for fine coal
cleaning. Advanced Gravity Separation 108-115.
22. Gawali SS, Bhambere MB (2015) Effect of design and the operating parameters
on the performance of cyclone separator - A Review. IJMERR 4: 1.
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Author Affiliations Top
Mining Engineering Department KIU Gilgit, Pakistan