Fine Coal Recovery From The Ömerler Washery Tailings And Plant ...

Fine Coal Recovery From The Ömerler Washery Tailings And Plant Applications
Ayşe Erdem, Akan Gülmez, Oğuz Altun, Selami Toprak
General Directorate Of Mineral Research And Exploration (MTA), Ankara, Turkey.
Zeki Olgun, Ahmet Gitmez
General Directorate of Turkish Coal Enterprises (TKI), Ankara, Turkey.
ABSTRACT: In this study, approximately 3 tons of coal sample taken from thickener entrance was
prepared by mineral processing techniques and cleaned by gravity methods. The samples were classified
to 5 size fractions by wet screening. The size fractions of +1mm and -1 +0.500 mm were chosen for direct
consumption or cleaning by spirals. The studies by Multi Gravity Separator (MGS) were carried out with
the -0.500 +0.280 mm and -0.280 +0.020 mm size fractions where the -0.020 mm fraction does not used
in the experiments. The clean coal fractions of +1 mm and -1 +0.500 mm obtained by classification were
subjected to lower calorific value (LCV), ash and total sulphur analyses. The results were 4168-4946
kcal/kg (on dry basis), 31.01-38.54 % ash and 4-4.27 % total sulphur content respectively. The results of
the clean coal concentrated by MGS experiments in -0.500 +0.280 mm fraction was found 5918 kcal/kg
LCV, 19.82 % ash content and 80.47 % combustible recovery. The results for the -0.280 +0.020mm
fraction were 6004 kcal/kg LCV, 19.19 % ash content, 80.47 % combustible recovery respectively. With
reference to the above experimental results, pre-economic evaluation studies were completed and decided
to construct an additional unit to the plant. Capacity of the constructed unit is 75.000 t/y which
corresponds $ 2.600.000 income in a year. General Directorate of Turkish Coal Enterprises concluded to
apply this project to the other coal washing plants in the country due to the successful results of this study
and laboratory studies has been going on by MTA currently
INTRODUCTION
Turkish Coal Enterprises (TKI) is the largest public organization in Turkey. One of its regional
institutions is Western Lignite Establishment (GLI) locating at Tavşanlı Town of Kütahya Province.
6.1 million tons of run of mine of coal has been produced at GLI. More than 45 % of these are consumed
to produce electrical energy at nearby thermal power plants. The remaining (55 %) is washed at The
Washeries of Tunçbilek and Ömerler.
Both The Washeries of Tunçbilek and Ömerler are sub-units of GLI. The former plant was in service
in 1952 and the latter one was in service in the year of 1994. Ömerler Washery being a public
organization has been in service with 600 tons per hour of capacity in the year of 1994 after completing
its performance tests in 1993.
The tailings of these two plants are accumulated at the ponds containing plenty amounts of fine coal
particles.
EXPERIMENTAL
Equipment and Method
The laboratory type C 900 MGS was used in the experimental work. (MGS Application Guide 1991,
Chan et al. 1991). 25 % solid concentration (by weight) was prepared and fed to the MGS by using a
peristaltic pump to obtain a continuous run. The mixture was agitated mechanically during the
experiment. The MGS variables were adjusted at the required levels as per the experimental design. The
feed slurry was then fed to the MGS feed vessel at the required flow rate while the MGS was in operation.
Samples from the concentrate and tailings streams were collected at steady state conditions, which were
achieved after about 5 min of processing. Heavy product, which was collected through front launder,

eferred to as tailings, and light product, which was collected through back launder, referred to as
concentrate. The samples were filtered, dried, and analysed for ash, sulphur and LCV.
Sample
Approximately 3 tons of samples were taken from entrance of TKI-GLI-Ömerler Washery tailing
thickener. The samples were mixed and obtained a homogenously composite sample.
The slurry sample was then wet sieved into four size fractions; +0.500; -0.500 +0.280; -0.280 +0.020
and -0.020 mm. The sieve analysis, ash, total sulphur, LCV and combustible recovery of fractions are
given in Table 1. The +0,500 mm fraction was not used in experimental studies because of that fraction
be able to directly selling or available (cleanable) at spirals; –0.500 +0.280 and –0.280 +0.020 mm
fractions were cleaned by MGS. Preliminary experiments revealed that –0.020 mm fraction was not
effectively cleaned by physical methods and therefore was not used in the experimental work.
Table 1. The sieve analysis of the composite sample on dry basis
Particle Size, Weight Grade (%)
mm
(%)
Ash S LCV, kcal/kg
+1 1.56 31.01 4.00 4946
-1 +0.500 5.11 38.54 4.27 4168
-0.500 +0.280 7.90 34.69 3.60 4435
-0.280 +0.150 4.76 34.45 3.11 4544
-0.150 +0.100 3.49 35.82 3.03 4402
-0.100 +0.055 5.24 42.10 2.69 3878
-0.055 +0.038 2.33 47.70 2.28 3279
-0.038 +0.020 2.69 54.44 1.99 2868
-0.020 66.94 77.92 0.76 707
Feed 100.00 65.02 1.57 1840
The general studies of abovementioned work to determine both physical and chemical properties of
output of coal washing plant, one can summarize;
There is a significant density difference between coal and gangue,
About 6.67 % of sample has an over 0.500 mm. particle size,
The coal particle size is average 10 microns in the -20 microns sized slurry fraction having 66.94 %
weight of the sample and 707 kcal /kg. of LCV,
The LCV of sample vary from 3868 to 4946 kcal /kg. at over 20 microns particle sized sieve fractions,
The MGS experiments reveal that the prepared sample has 7.90 % by weight at -0.500 +0.280 mm.
and 18.51 % by weight at -0.280 +0.020 mm. sieve fractions
The Russell branded wet -sieve system is employed for preparation of different sized fractions of
sample.
The fractions of samples used in the experiments of MGS are both the fractions of -0.500 +0.280 mm.
and -0.280 +0.020 mm. But, the fraction of -0.020 mm. is removed as slurry without any treatment.
Experiments
MGS Experiments at -0.500 +0.280 Fraction
Wash water flow rate, drum speed and tilt of the drum were tested to determine optimum conditions of
separation. Shake frequency and shake amplitude of the MGS were predetermined and set as 4 cps and 10
mm, respectively. Results are illustrated in graphs in terms of ash content and combustible recovery in the

concentrate fraction. The results for coarse (-0.500 +0.280 mm) fraction are given in Table 2 and Figure
1.
Table 2. Optimum values for -0.500 +0.280 particle size
TILT
DEGREES º
CONCENTRATE (%)
Weight Dry Ash Sulphur Combustible Recovery LCV
kcal/kg
0 67.37 21.28 1.82 84.11 5892
1 69.51 19.82 1.19 85.24 5918
2 78.13 25.63 1.19 90.64 5450
Concentrate,%
100
80
60
40
20
0
0 1 2 3 4
Tilt of Drum, º
Figure 1. Optimum values graph of tilt degrees for -0.500 +0.280 mm particle size
The effect of wash water was studied at three different flow rates, i.e. 1, 2 and 3 l/min and drum speed
and tilt of drum were adjusted as 240, 260 and 280 rpm and 0, 1 and 2�, respectively.
When Washing water and speed of drum are examined, one can say that the increasing of washing
water causes the picking up of ash content and decreasing of LCV.
The stratification of sample in the MGS takes place from surface to inward that decreasing of the
density. The particles having less density on upper part of the strata are transported to the back exit of the
device due to the effects of washing water. But, the denser particles sitting inside of drum are drifted to
the front exit by scrapers. Here, the denser particles have the same revolution direction with the drum.
The scraper’s revolution speed is more than the particle’s speed, however. The more the washing water
means the more the drifted light material toward the back exit. Relatively, that makes an increase of ash,
too.
The increasing of the tilt of the drum causes the increase of amount of concentrate. But, the
transportation by scrapers becomes difficult.
By the operation principle of the MGS, the dense material is taken from the front exit. The light
material is taken back front, however.
Weight
Dry Ash
Total Sulphur
Combustible
Recovery

MGS Experiments at -0.280 +0.020 Fraction
The effect of drum speed, wash water amount, tilt of drum, shake amplitude and shake frequency
parameters studied on this size fraction, respectively. Operation conditions are also specified at
experiments. The results are given in Table 3 and Figure 2, respectively.
The -0.280 +0.020 mm size fraction which is used in experiments, 18.51 % of the material constitute.
Table 3. Optimum values for -0,280 +0,020 particle size
TILT
DEGREES º
CONCENTRATE (%)
Weight Dry Ash Sulphur Combustible Recovery LCV
kcal/kg
0 59.17 19.19 1.63 80.47 6004
1 64.12 21.37 1.19 84.67 5877
2 66.10 22.89 1.19 87.22 5696
Figure 2. Optimum values graph of tilt degrees for -0.280 +0.020 mm particle size
Installation of Industrial Plant
Concentrate,%
100
80
60
40
20
0
0 1 2 3 4
Tilt of Drum, º
A protocol was signed within the scope of projects carried out jointly between TKI and MTA. By this
protocol, a pilot plant will be established in Tunçbilek Ömerler Washery whose condition for this purpose
considering appropriate by TKI
The plant was supposed to be found nearby outside the washing plant. The samples were taken to
conduct mineral processing studies at MTA. The technological studies on these samples reveal that fine
coal can be recovered economically and technically.
The four alternative methods were presented to the General Directorate of TKI after the result of prefeasibility
studies. By the lights of these technical data, a pilot plant was established at a chosen place at
Tunçbilek Ömerler Washery. (Table 4)
Weight
Dry Ash
Total Sulphur
Combustible
Recovery

Table 4. The Alternative Economical Assessment of the Tailings of Ömerler Washery
ALTERNATIVES CLASSIFICATION ALTERNATIVE MGS ALTERNATIVE
1-Selling to Power Plant
Investment ($) 444.583 1.192.811
Running Costs ($/y) 243.731 282.985
Running Incomes ($/y) 4.039.845 3.476.411
Net Present Value ($) 22.230.026 17.996.548
Rate of Return (%) 672 213
2-Selling to Cement Factory
Investment ($) 444.583 1.587.356
Running Costs ($/y) 243.731 282.985
Running Incomes ($/y) 6.633.572 5.708.393
Net Present Value ($) 37.696.849 31.306.225
Rate of Return (%) 1127 360
As a result of evaluations of alternative methods, TKI decided to invest in additional units. To observe
the applicability of this work, the first alternative was accepted. By this first alternative, the additional
unit could provide only classification of fine coal that is saleable to power plants.
RESULTS AND DISCUSSIONS
a. The experiments were executed by a C 902 type semi-pilot MGS. The optimum laboratory
conditions were determined using drum speed, washing water flow rate, slope of drum as parameters. The
studies show that purposed plant can produce TKI demanded market products of coal having the various
LCV.
b. When it was evaluated, the lowest value of result is obtained at the -0.500 +0.280 mm. particle
sized product recovered by 98.56 % combustible recovery with 4750 kcal /kg. LCV and having 33.09 %
dry- ash content.
The upper value of the result was obtained at 85.24 % of combustible recovery at the same particle
size having 5918 kcal /kg. of LCV and 19.82 % dry –ash content.
c. As for the -0.280 +0.020 mm. sieve fraction, the minimum value of result was obtained at the
product recovered by 91.68 % combustible recovery with 5380 kcal /kg. LCV and having 26.68 % dry-
ash content.
The maximum value of the result was reached at 80.47 % of combustible recovery at the same particle
size having 6004 kcal /kg. of LCV and 19.19 % dry –ash content.
d. The obtained this quality fine coal can be present to either blending it with the coal having a low
specific calorie to feed the power plants or marketing it to the industrial plants who use fine coal.
e. By the light of studies conducted by Mineral Processing Division of MTA, TKI invested in the
Directorate of GLI of The Washery of Tunçbilek-Ömerler to evaluate of this work economically. As
mentioned above, the first alternative was realized and the plant has been established.
f. As soon as possible the pilot plant had been setup, the industrial scale plant was built and installed
by the date of November, 2009. Since then, the saleable fine coal has been produced at the plant.
g. The cost of the investment was regained in two weeks of operations of the plant. It was
determined that the Washery of Tunçbilek-Ömerler can recover 75.000 tons of fine coal valuing $
2.600.000. This fine coal can market to EÜAŞ (The Electrical Production Cooperation).
h. In the year 2011, a new project is initiated to execute same studies on the other washing plants by
jointly TKI and MTA. By the scope of this project, the team of experts have already examined concerning
coal washing plants and decided to be taken enough amount of samples;
� From the thickener entrance of Dereköy of Ege Lignite Establishment,
� From the thickener output of the Washery of Directorate of Seyitömer Lignite Establishment.

REFERENCES
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Chan, B.S.K., Mozley, R.H. & Childs, G.J.C. 1991. The MGS-A mine scale machine UK, Richard
Mozley ltd.
Erdem, A., Olgun, Z., Gülmez, A., Koca, S. & Öteyaka, B. 2008. Beneficiation of lignites by means of
shaking table, MGS and flotation, Project report 4, Project No. 106G056 (Turkish), MTA, Ankara.
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flotation, Project report, Proje No, 106G056 (Turkish), TÜBİTAK, Ankara
www.tki.gov.tr/ activity report (Turkish), 2010.
*This Project supported by TÜBİTAK.