08 industrial minerals (pages 743-806)
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IInndduussttrriiaallMMiinneerraallss
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Proceedings of 14th
International Mineral Processing SymposiumKuadas, Turkey, 2014
743
BENEFICIATION OF UKRANIAN KAOLINS FOR CERAMIC
INDUSTRY WITH FALCON GRAVITY SEPARATOR AND
HYDROCYCLONE
Utku Anl Bata1, Mustafa zer1, Ozan Kkkl1and Hayrnnisa Ateok1,a
1. I.T.U. Mineral Processing Engineering, Istanbul, Turkey
a. Corresponding author ([email protected])
ABSTRACT: In this study, kaolin sample which is belonging to Ukraine Vikninskaya
area is prepared for ceramic industry. First of all, after communition, kaolin sample has
scrubbed with Attrition Scrubber for separating over 0,5 mm sized quartz (SiO2) particles
from the system as quartz concentrate. After scrubbing, enrichment tests have done with C-
124 diffuse-type 50 mm Mozley Hydrocyclone and Falcon Gravity Concentrator and the
results were compared. In hydrocyclone tests, optimum mixing time and solid rates aredetermined and in Falcon tests the effect of the solid rates to the separation are optimised.
Also, in parallel, with the optimal conditions, the optimum capacity is calculated for
getting the best possible concentrate. The processing plants process flow chart has been
created and solid water balance has calculated with the optimum conditions.
1. INTRODUCTION:Kaolinite clay with formula
Si2Al2O5(OH)4, is the major mineral
component of kaolin, which may usuallycontain quartz and mica and also, less
frequently feldspar, illite, ilmenite,
anatase, heamatite, bauxite, zircon, rutile,
kyanite, silimanite, graphite, attapulgite,
montmorillonite, and halloysite [Varga
G.,2007].
Kaolin finds extensive applications in a
variety of industries such as paper, paint
rubber and especially in ceramics
[Murray etal, 1993]. The quality ofkaolins used in the ceramic industry is
very important so chemical and
mineralogical specifications of the
kaolins should meet the following
requirements; minimum 35% Al2O3
maximum 0,4 % Fe2O3and between 44-
64% SiO2 for marketing to ceramic
industry [Guven, 1998].
The preferred beneficiation methods of
kaolin minerals depend on the amount
and nature of the mineral impurities
associated to it. Although these methods
are quite useful in removing impurities,they are, at the same time, costly,
complicated and environmentally
hazardous [Rawlings D.E.,2004].
The size classification produces different
grades of kaolin with varying particle size
distribution. Increase in the finer fraction
can result in improved brightness due to
the increase in surface area and hence
more light scattering sites. During sizing,
coarser (quartz) and / or denser (ilmenite,rutile etc.) impurity minerals get
separated. Even small quantities of the
coloring impurities in the finer fractions
contaminate the clay and reduce its
brightness. Hence, these impurities can
be removed only by special techniques
such as froth flotation, magnetic
separation, oxidative/ reductive bleaching
etc.
Depending upon the nature and quantity
of impurities (Murray et al, 1993; Jepson,1988).
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2. EXPERIMENTALThe physical,chemical and mineralogical
properties were determined by standart
methods and the chemical composition of
the row ore has shown in the table. (Table1)
Table 1: The chemical composition of
row ore
ComponentWeight
(%)
LOI 9.06
SiO2 63.83
Al2O3 25.33
Fe2O3 0.51
TiO2 0.73
CaO 0.04
Na2O 0.16
K2O 0.26
For determining the particle size
distribution of the sample screen test
were done and particle size distribution
curve has and d50 and d80 parameters
were found as 10 and 23 mm.(Figure 1)
Figure 1:Particle size distribution of the
sample
2.1. Attrition Scrubbing TestsAttrition scrubbing tests were done in
Wemco attrition scrubber. The samples in
-20 mm and 10 mm particle sizes and%
50 slurry density were fed into the
scrubber and, 1200 and 900 rpm
velocities and 5, 10 and 15 min. times
were adjusted as the working conditions
of scrubber. And at the end of the testsoptimum scrubbing time and speed and
optimum particle size distributions were
optimised.
2.1.1. Scrubber Tests with -20 mm
SampleThe sample is crushed under 20 mm with
Jaw crusher and screening tests were
applied to the sample and particle size
distribution of the sample was
determined.(Figure 2) After that, attritionscrubbing tests were done for optimising
scrubbing time, scrubbing speed and
slurry density of the pulp. The results
were given in (Table 2).
Figure 2: Particle size distribution curve
of -20 mm sample
2.1.2. Tests with -10 mm sampleThe sample is crushed under 10 mm with
Jaw crusher and screening tests were
applied to the sample and particle size
distribution of the sample was
determined(Figure 3).After that, attrition
scrubbing tests were done for optimising
scrubbing time, scrubbing speed and
slurry density of the pulp.
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1200 rpm was found to be optimum after
the tests and the scrubbing tests were
done in these constant conditions: 1200
rpm and %50 slurry density.
The results of the scrubbing tests weregiven in (Table 3) and (Table 4).
Figure 3: Particle size distribution curveof -20 mm sample
Table 2: -20 mm sized sample attrition scrubbing test results for determining optimum
mixing time.
Time
(min)
Particle
Size(microns)
Amount
(%)
Content, (%) Distribution, (%)
SiO2 Al2O3 Fe2O3 SiO2 Al2O3 Fe2O3
5
+500 19,2 97,3 0,33 0,13 29,3 0,3 5,3
-500+106 13,6 91,3 4,67 0,28 19,5 2,6 8,1-106+38 6,8 62,8 24,51 0,68 6,7 6,7 9,8
-38 60,4 46,9 37,17 0,6 44,5 90,5 76,8
Total 100 63,7 24,87 0,47 100,0 100,0 100,0
10
+500 17 98,75 0,07 0,04 26,22 0,05 1,47
-500+106 12,6 95,20 2,62 0,19 18,73 1,34 5,18
-106+38 10 66,21 22,25 0,63 10,34 9,06 13,63
-38 60,4 47,40 36,41 0,61 44,71 89,55 79,72
Total 100 64,03 24,56 0,46 100,00 100,00 100,00
15
+500 18,7 99,45 0,05 0,03 29,94 0,04 1,21
-500+106 11,4 96,3 1,88 0,17 17,67 0,88 4,17
-106+38 9,4 55,3 21,52 0,62 8,37 8,27 12,55
-38 60,5 45,2 36,7 0,63 44,02 90,81 82,07
Total 100 62,12 24,45 0,46 100,00 100,00 100,00
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Table 3: -10 mm sized sample attrition scrubbing test results for determining optimum
mixing time.Time
(min)
Particle
Size
(microns)
Amount
(%)
Content, (%) Distribution, (%)
SiO2 Al2O3 Fe2O3 SiO2 Al2O3 Fe2O3
5+500 20,8 98,1 0,33 0,13 31,9 0,3 5,9
-500+106 12,5 92,4 4,67 0,28 18,1 2,5 7,7
-106+38 8,4 65,32 24,51 0,68 8,6 8,7 12,5
-38 56,3 47,04 37,17 0,6 41,4 88,5 73,9
Total 100 63,9252 23,63794 0,45696 100,0 100,0 100,0
10
+500 18,8 99,05 0,26 0,07 28,8 0,2 2,8
-500+106 12,0 95,00 2,65 0,24 17,6 1,3 6,1
-106+38 9,0 64,45 21,65 0,77 9,0 7,8 14,7
-38 60,2 47,98 37,52 0,6 44,6 90,7 76,5
Total 100,00 64,70 24,90 0,47 100,00 100,00 100,00
15
+500 18,6 99,50 0,04 0,02 29,68 0,03 0,82
-500+106 12,3 96,10 1,86 0,18 18,96 0,94 4,85
-106+38 9,2 55,70 21,54 0,64 8,22 8,18 12,91-38 59,9 44,90 36,72 0,62 43,14 90,84 81,42
Total 100,00 62,35 24,21 0,46 100,00 100,00 100,00
Table 4: Attrition scrubbing test results for determining optimum mixing velocity.Velocity
rpm
Particle
Size
(microns)
Amount
(%)
Content, (%) Distribution, (%)
SiO2 Al2O3 Fe2O3 SiO2 Al2O3 Fe2O3
1200 +500 19,20 97,30 0,33 0,13 29,30 0,30 5,30
-500+106 13,60 91,30 4,67 0,28 19,50 2,60 8,10
-106+38 6,80 62,80 24,51 0,68 6,70 6,70 9,80
-38 60,40 46,90 37,17 0,60 44,50 90,50 76,80Total 100,0 63,69 24,81 0,47 100,0 100,0 100,0
900
+500 26,10 97,65 1,19 0,07 39,20 1,30 4,50
-500+106 11,20 84,20 10,13 0,34 14,50 4,70 9,50
-106+38 4,40 63,80 24,22 0,65 4,30 4,30 7,20
-38 58,30 46,90 37,52 0,54 42,0 89,70 78,80
Total 100,0 65,06 24,38 0,40 100,0 100,0 100,0
2.2. Classification Tests:After -20 mm sample was screened from
0,5 mm sized screen classification tests
with hydrocyclone and Falcon Gravity
Concentrator were done for determining
optimum working conditions.
2.2.1. Hydrocyclone TestsAfter scrubbing and screening from 0,5
mm screen over 0,5 mm size particles
were taken as quartz concentrate. Under
0,5 mm sized sample was fed to the
hydrocyclone. The parameters slurry
density,feed pressure,apex and vortex
diameters were optimised for determining
optimum working conditions of
hydrocyclone.The flowsheet of
hydrocyclone tests were given in the
(Figure4). And the results of
hydrocyclone tests were given in (Table
5).
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Figure 4:Flowsheet of hydrocyclone tests
2.2.2. Beneficiation tests with Falcon
Gravity Concentrator:
After scrubbing and screening from 0,5
mm screen over 0,5 mm size particleswere taken as quartz concentrate. Under
0,5 mm sized sample was fed to the
Falcon Gravity Concentrator. The
parameters slurry densityand G force
were optimised for determining optimum
working conditions of Falcon Gravity
Concentrator.
The flowsheet of Falcon Gravity
Concentrator tests were given in the(Figure 5).And the results of Falcon
Gravity Concentrator tests were given in
(Table6). After these tests the final flow
sheet was determined as in the (Figure 6).
Table5: Hydrocyclone tests results
Products Amount
(%)
Content, (%) Distribution, (%)
SiO2 Al2O3 Fe2O3 SiO2 Al2O3 Fe2O3
Kaolin 65,20 46,90 37,35 0,66 48,89 93,20 87,82
Middling 5,30 57,50 28,84 0,81 4,87 5,85 8,76
Quartz 29,50 98,08 0,85 0,09 46,26 0,96 5,42
Total 100,0 62,55 26,13 0,49 100,0 100,0 100,0
Figure 5: Flowsheet of Falcon GravityConcentrator tests.
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Table 6: Falcon Gravity Concentrator test results
3. RESULTS AND DISCUSSION1) From the chemical and mineralogical
analysis of the row sample it can be seen
that the quartz content of the sample is
higher for the needs of the ceramic
industry.
2) After screen tests row ores d80= 23
mm and d50= 10 mm has determined.3) As the results of the scrubbing tests the
optimum conditions for enrichment were
found like that: %50 slurry density, 1200
r.p.m. attrition speed, -20mm particle size
and 5 minutes scrubbing time.
4) After attrition scrubbing +0,5 mm can
be separated from the system as quartz
concentrate.
5) The optimum conditions for
hydrocyclone tests slurry density10%; 3,2
mm and 2,2 mm apex radius aredetermined.
6) From Falcon gravity separator tests it
has been found that the ideal slurry
density10 %.
7) It can be clearly said that the content
of the quartz concentrate that is obtained
from Falcon gravity concentrator is not
as well as the hydrocyclone tests.The
efficiency of the Falcon is not enough to
get a good quality of quartz concentrate
but good quality of kaolin concentrate
can be obtained.
4. CONCLUSION:
As the results of the attrition scrubbing
tests, optimum scrubbing time 5 min.,
%50 solid ratio and 1200 rpm scrubbing
velocity were found. From hydrocyclonetests %46,90 SiO2, %37,50 Al2O3 ve %
0,66 Fe2O3 content kaolin concentrate;
%98,08 SiO2, %0,85 Al2O3 ve % 0,09
Fe2O3 content quartz concentrate were
obtained. From the Falcon gravity
concentrator tests the content of kaolin
concentrate were found %46,90 SiO2,
%37,50 Al2O3and % 0,66 Fe2O3 and
content of quartz concentrate %98,08
SiO2, %0,85 Al2O3and % 0,09 Fe2O3
were obtained.Also according to the results of the
process flow chart 1,78 m3 water must be
feed per ton ore to the process plant.
Saolid
Ratio, %
Products Amount
(%)
Content, (%) Distribution, (%)
SiO2 Al2O3 Fe2O3 SiO2 Al2O3 Fe2O3
10
Kaolin 20,80 98,10 0,33 0,13 31,90 0,30 5,90
Middling 12,50 92,40 4,67 0,28 18,10 2,50 7,70
Quartz 8,40 65,32 24,51 0,68 8,60 8,70 12,50
Total 100,00 63,90 23,60 0,45 100,00 100,00 100,00
20
Kaolin 20,80 98,10 0,33 0,13 31,90 0,30 5,90
Middling 12,50 92,40 4,67 0,28 18,10 2,50 7,70
Quartz 8,40 65,32 24,51 0,68 8,60 8,70 12,50
Total 100,00 64,70 24,90 0,47 100,00 100,00 100,00
30
Kaolin 20,80 98,10 0,33 0,13 31,90 0,30 5,90
Middling 12,50 92,40 4,67 0,28 18,10 2,50 7,70
Quartz 8,40 65,32 24,51 0,68 8,60 8,70 12,50
Total 100,00 62,35 24,21 0,46 100,00 100,00 100,00
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Figure 6: Flowsheet of the process plant.
Acknowledgements: Authors present
their special gratefulness to EczacbaEsan to reproduce chemical analysis of
the samples.
REFERENCESGuven, C., 1998, Investigation of beneficiation
possibility of Istanbul-Sile region clays for
ceramics industry, Graduation Thesis, I.U.
Mining Eng. Dept.
Jepson, W.B., 1998,Structural iron in kaolinites in
associated ancillary Minerals, Iron in soilsand clay minerals. NATO Advanced Science
Institutes Series, pp. 467-536.
Murray, K.J., and Keller, W.D.,1993. Kaolins,
Kaolins and Kaolins in Kaolin Genesis and
Utilisation. Special publications by the Clay
Mineral Society, Colorado, US pp 1-24.
Rawlings, D.E., 2004. Microbially assisted
dissolution of minerals and its use in the
mining industry.
Varga, G., 2007. The structure of kaolinite and
metakaolinite. Epitoanyag, 59, 4-8.
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Proceedings of 14th
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751
INVESTIGATION OF USAGE OF ZONGULDAK ALACAAZI
SANDSTONE IN CASTING INDUSTRY
Gndz Ateok1,a, Feridun Boylu1, Mustafa zer1, Frat Burat1and Hseyin
Batrkc1
Istanbul Technical University Mining Faculty, Mineral Processing Engineering Department,
Maslak-stanbul, Turkeya. Corresponding author ([email protected])
ABSTRACT: In 2013 demand of silica sand, which has a usage area in glass, casting,
construction, metallurgy, electronic, and ceramic industries with silicon-ferrosilicon
production, is over 4 million tons in Turkey. This demand cannot be met with running out
of reserves of coastal sand and it resulted in production gap. Therefore, quartzite reserves
of 6.3 billion tons, which exists in Zonguldak, Antalya, Adana, Kastamonu, Yozgat, and
Denizli provinces of Turkey, have increased in importance.
In this research, technological tests were performed on Zonguldak Alacaaz sandstone,which have 700 million tons of reserves. In order to investigate the possibility of usage of
this sandstone in casting industry, at first, physical and chemical properties of the sample
was determined. Particle size was reduced with jaw and cone crushers. Then, scrubbing
was performed on Alacaaz sandstone sample, which has 96.8% SiO2and 0.6% Fe2O3.After classification into size fractions, it was seen that a clay product could be obtained
with 4.40% Fe2O3content, while the sandstone contained 0.36% Fe2O3.
On the other hand, the scrubbed sandstone was tested in high intensity wet magnetic
separation and flotation. According to the results, flotation method gave more positive
results than magnetic separation did. 96% amount of Alacaaz sandstone was obtainedwith 0.24 Fe2O3. At the end of the tests, process flow sheets for both of the samples were
generated.
1. INTRODUCTIONQuartz naturally occurs as colorless or
light-white colored and fine-grained
structure. It has a hardness of 7 on the
Mohs scale with 2.65 specific gravity and
17850
C melting temperature [pekolu,1999].
While pure quartz crystals can be used in
optic and electronic industry, quartz has
areas of usage in chemistry, electric,
glass, detergent, paint, ceramic, abrasive,and metallurgy industries [SPO, 2001].
On the other hand, quartz ores contain
impurities, especially iron. Unless irons
minerals are removed, transmission of
optic fibers are obstructed, discolorationin ceramic products occurs and melting
point of refractory materials is decreased
[Taxiarchou et al.1997].
In order to remove iron minerals, various
physical, chemical and physico-chemical
methods can be applied. As simpleprocesses of crushing, grinding and
sieving can respond, sometimes magnetic
separation and/or flotation processed can
be necessary [Akl et al., 2007].However when the iron minerals are not
able to be liberated, then, acid leachingmethod becomes an alternative method to
obtain high-purity quartz [Loritsch ve
James, 1991].
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Figure 2: XRD pattern of the non magnetic product
Figure 3: XRD pattern of the magnetic product
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3. RESULTS
3.1 Scrubbing TestsThese tests aimed abrasion of the sample
by scrubbing rather than grinding. Thus,formation of fine sizes could be
prevented. Under the conditions of 60%
solid ratio by weight and 700 rpm
rotational speed, different scrubbing
durations were tested. After scrubbing,
the sample was decantated in three stages
and clay was separated. Scrubbing testsresults are given in (Table 1).
Scrubbing+decantation tests showed that
4.9-5.1% of clay material could be
separated, which provided a mechanicalabrasion.
Table 1: Scrubbing+decantation
Particle Size
Fraction, mm
Scrubbing
5 min 10 min 15 min
+1.41 100.0 100.0 100.0
-1.41+1.00 98.5 98.4 98.5
-1.00+0.710 96.5 96.6 96.8
-0.710+0.500 93.4 93.6 94.0
-0.500+0.355 84.3 86.3 87.4
-0.355+0.212 62.7 68.3 66.4
-0.212+0.180 20.9 27.8 27.6
-0.180+0.125 10.1 12.5 13.1
-0.125+0.090 6.7 7.7 8.0
-0.090+0.063 3.7 4.7 4.7
-0.063 2.0 2.8 2.4
Weight accordng
to feed, %95.1 95.1 94.9
-0.125+0.106 100.0 100.0 100.0
-0.106+0.090 99.8 100.0 100.0
-0.090+0.074 99.7 100.0 100.0
-0.074+0.063 99.7 100.0 100.0
-0.063+0.045 99.6 99.7 99.9
-0.045 98.1 99.1 99.7
Weight accordng
to feed, %4.9 4.9 5.1
Chemical analyses of the products are
shown in (Table 2a and 2b). Loss on
ignitions was nearly 0.1%. The SiO2
content of the raw ore sample, which was
96.8%, increased above 99%. On the
other hand, Fe2O3 content of the raw
sample known as 0.72% decreased to0.39%.
Table 2a: Chemical analyses of
Scrubbing+decantation tests
Scrubbing
Duration,
min
SiO2,
%
Al2O3
%
Fe2O3
%
TiO2
%
5 99.00 0.38 0.42 0.035
10 99.09 0.26 0.41 0.036
20 99.11 0.25 0.39 0.033
When the results were evaluated, in order
to decrease the iron content further,
flotation was decided to be performed
following 10 min scrubbing and
decantation.
Table 2b: Chemical analyses of
Scrubbing+decantation tests
Scrubbing
Duration,min
CaO
%
MgO
%
Na2O
%
K2O
%
5 0.01 0.00 0.00 0.05
10 0.01 0.00 0.00 0.04
20 0.01 0.00 0.00 0.04
3.2 Flotation Tests
In the flotation tests, collectors of R801
and R825 were used with the amounts of
varying between 100-400 kg/t. Since the
collectors have frother property, therewas no need to use any frother. The
collectors used in a ratio of R801/R825 :
2/1. pH value was kept constant between
2.5-3.0. Collector amount, multiple stage
collector addition and solid ratios were
tried in the flotation tests. The results
were given in (Table 3).
400 g/t collector addition in multiple
stages to the scrubbed pulp of which can
be adjusted above 30% solid ratios was
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determined as the optimum flotation
condition.
0.72% of Fe2O3 content in the raw ore
sample was decreased to 0.4% with
scrubbing and decantation. After flotationtests, this value was decreased to 0.24%
Fe2O3. Besides, 99.46% SiO2content was
able to be obtained.
3.3 Wet High Intensity Magnetic
Separation TestsScrubbed and decantated pulp, which
contained 0.4% Fe2O3, was fed to Jones
magnetic separator at 20% solid ratioswith a constant feed rate. During the test,
strength of current was adjusted to
different values of 1, 3 and 6.8 A.
Table 3: Scrubbing+decantation+flotation test resultsSolidRatio
Collector Weight SiO2 Al2O3 Fe2O3 TiO2 CaO MgO Na2O K2O
% Amount, g/t Add. % % % % % % % % %
20 150 150 99.2 99.33 0.23 0.27 0.028 0.01 0.01 - 0.04
20 200 200 98.8 99.31 0.23 0.29 0.027 0.01 0.01 - 0.04
20 250 250 96.6 99.36 0.24 0.26 0.022 0.01 0.01 - 0.04
20 360 360 94.9 99.43 0.23 0.23 0.022 - 0.01 - 0.04
28 250 250 96.6 99.46 0.19 0.26 0.022 - - - 0.03
40 250 250 96.6 99.40 0.22 0.25 0.025 - - - 0.04
28 250125+62.5+62.5
97.6 99.44 0.18 0.27 0.026 - 0.01 - 0.03
20 150 150 98.8 99.20 0.22 0.32 0.03 - 0.01 - 0.04
20 200 200 96.2 99.24 0.22 0.29 0.025 - - - 0.04
20 250 250 93.7 99.31 0.23 0.25 0.024 - 0.01 0.04
20 360 360 84.5 99.28 0.23 0.29 0.023 - 0.01 0.01 0.04
28 200 200 96.3 99.21 0.24 0.32 0.034 - 0.01 - 0.04
36 200 200 96.6 99.29 0.23 0.29 0.023 - 0.01 - 0.04
28 400
67.5 +67.5 +67.5 +
67.5+130
95.8 99.40 0.19 0.24 0.025 - - - 0.03
While the results of the magnetic
separation can be seen in (Table 4), the
distributed metal balances are given in
(Table 5).
According to the results, Jones magnetic
separator provided a decrease in Fe2O3
content, which was found as 0.3%. Under
these conditions, 99.45% SiO2 was able
to be obtained.
When the weights and contents of the
products were evaluated, it can be
concluded that there was not suitable
magnetic type iron minerals, which could
be removed with wet high intensity
magnetic separator.
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Table 4: Jones Magnetic Separation
Results
ProductsWeight, Fe2O3, %
% Content Distr.
NonMagnetic
68.2 0.30 59.4
Middling 8.9 0.31 8.0
Magnetic
Product-313.0 0.34 13.0
Magnetic
Product-26.6 0.51 9.7
Magnetic
Product-13.4 0.99 9.9
Feed 100 0.35 100
Table 5: Jones Magnetic Separation
Results (Distributed)
ProductsWeight, Fe2O3
% Content Distr.
Non
magnetic90.0 0.30 80.4
Middling 6.6 0.51 9.7
Magnetic 3.4 0.99 9.9
Feed 100 0.35 100
4. CONCLUSIONPrimary and secondary crushing units
were decided as jaw and cone crushers
respectively. Since sandstone ores
excavated from open pit mines can have
some extent of moisture, hammer
crushers are not be suitable for this
process.
Using flotation method, 0.24% Fe2O3was
able to be obtained with 96% efficiencyfrom the sandstone sample, which
contained 0.7% Fe2O3.
With wet high intensity magnetic
separation using Jones separator, 0.30%
Fe2O3was able to be obtained with 90%
efficiency from the sandstone sample,
which contained 0.7% Fe2O3.
Either flotation or magnetic separation
processes provided acceptable Fe2O3
contents. However when these processes
were compared, in terms of the silica
sand weight and lower Fe2O3 content
obtained, flotation method was thought to
be better.
REFERENCESAkl, A., Tuncuk, A, Deveci, H., 2007. An
Overview of Chemical Methods Used in the
Purification of Quartz. Madencilik, Vol.46,
No.4, pp 3-10.
pekolu, B., 1999. Quartz,Quartzite, Quartzsand. Association of stanbul MineExportersi, Inventory of Industrial Mineralsof Turkey, pp. 102-106.
Loritsch, K.B. and James, R.D., 1991. Purified
Quartz and Process for Purifying Quartz.
United States Patent, Patent Number:
4,983,370.Specialization Commission of Mining Reports of
Development Plan-8th
, 2001. Sub-
commission of Industrial Raw Materials,
Sand Industry Raw Materials- III (Quartz
sand, Quartizte, Quartz). State Planning
Organization.
Taxiarchou, M., Panias, D., Douni, I., Paspaliaris,I. ve Kontopoulos, A., 1997. Removal of Iron
from Silica Sand by Leaching with Oxalic
Acid. Hydrometallurgy, 46, 215-227.
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LEACHING OF A COMMERCIAL VERMICULITE IN H2SO4
SOLUTIONS
.Ehsani1, E.Turianicov2, M.Bal2and A.Obut1,a
1. Hacettepe University, Mining Engineering Department, Ankara, Turkey
2. Institute of Geotechnics, Slovak Academy of Sciences, Koice, Slovakiaa. Corresponding author ([email protected])
ABSTRACT:In this study, the leaching behaviour of a commercial vermiculite sample, in
natural and heated forms, in 1 M aqueous sulphuric acid solutions at 20C and 90C wasinvestigated using chemical and X-ray diffraction analyses, Fourier transform infrared
spectroscopy and nitrogen adsorption measurements. Although small changes occurred in
the chemical compositions and surface area values following leaching at 20C, greatreductions in the amounts of structural components, i.e. Al2O3, Fe2O3, MgO, and dramatic
increases in the surface area values were observed after leaching of both samples at 90C,indicating quantitative, but not total, dissolution of the samples. Similarly, acid leaching of
natural and heated vermiculite samples at 20C resulted only small changes in the X-raydiffraction patterns and infrared spectra, but with the increase of leaching temperature to
90C, significant changes, i.e. the dissolution of vermiculite structures and the formation ofhydrous amorphous silica phase, were observed.
1. INTRODUCTIONSwelling clay minerals, such as smectites
and vermiculites, exhibit differences in
their layer charges, adsorptive properties,
cation exchange capacities, particle sizes
etc. Because of these differences, they
can be used in different areas such as
foundry, construction, agriculture or
chemical industries either directly or after
the application of different modification
processes. Leaching by inorganic acids,
i.e. sulphuric or hydrochloric acid, is one
of the useful modification processes for
these clay minerals and due to the
enhanced surface and catalytic behaviourfollowing acid leaching, they can be used
as bleaching earths, as catalysts or
catalyst supports, in the production of
carbonless copying paper or in the
preparation of pillared clays and
organoclays [Komadel et al., 1990;Suquet et al., 1991; Mokaya and Jones,
1995; Breen et al., 1997; Ravichandran
and Sivasankar, 1997; Londo et al., 2001;
Gates et al., 2002; Jozefaciuk and
Bowanko, 2002; nal et al., 2002; Kooli,2009; Steudel et al., 2009a].
In contrast to numerous studies related
with acid leaching of smectites, the
number of studies investigating the
leaching behaviour of commercial
vermiculites in inorganic or organic acids
is low. Therefore, in this study, leaching
behaviour of a commercial vermiculite, in
natural and heated forms, in sulphuric
acid solutions was investigated and
comparative data were collected for
future studies. To identify the changes
caused by acid leaching, X-ray diffraction
(XRD), Fourier transform infrared (FT-
IR) and chemical analyses together with
nitrogen adsorption measurements wereperformed on the natural, heated and
leached vermiculite samples.
2. MATERIALS AND METHODSThe natural sample used in this work is
commercial micron grade Palabora(South Africa) vermiculite. According to
the data supplied by the producer, 80% of
the natural sample is in the size range of
-0.710+0.250 mm and the fraction of
-0.180 mm is maximum 10%. The naturalsample contains 85-95% vermiculite,
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and phlogopite, apatite, diopside with
trace amounts of dolomite and quartz are
the impurities. Chemical composition of
the natural sample was given in Table 1.
Table 1: Chemical composition (%) of the
natural vermiculite sample.
SiO2 Al2O3 Fe2O3 MgO
41.02 8.90 8.36 19.91
CaO Na2O K2O TiO2
6.27 0.07 4.63 0.97
P2O5 MnO Cr2O3 L.O.I
2.41 0.06 0.05 6.97
In the leaching studies, natural and heated
(at 900C, according to Turianicovet al.[2014]) vermiculite samples were used.
Because surface area is one of the most
important parameters in leaching studies,
in this study, heated vermiculite was
compared with the natural vermiculite
due to its higher surface area. Sulphuric
acid was selected as the leaching reagent
due to its reported efficiency ondissolution [Steudel et al., 2009a]. In a
representative experiment, 50 grams of
natural (NV) or heated (HV) vermiculite
was leached in 500 mL, 1 M aqueous
H2SO4solution either at 20C or 90C for60 minutes under constant rate of stirring.
Following leaching, the solid residues
were separated by filtration, washed and
finally dried at 105C. The chemicalcompositions, XRD patterns (Rigaku
with CuK radiation, followingequilibration under room atmosphere),
FT-IR spectra (Bruker, by KBr pellet
method), and B.E.T. surface area values
(Quantachrome Instruments, by nitrogen
adsorption following degas for two hours
at 105C) of the natural, heated andleached vermiculites were determined in
order to observe the changes caused by
acid leaching. The pore size distribution
of a selected leach residue was alsodetermined.
3. RESULTS AND DISCUSSION
3.1. Chemical Analyses, Surface Area
Measurements and Porous PropertiesSome of the main chemical components
and surface area values of the natural andheated samples together with their
corresponding leached counterparts were
presented in Table 2 and Table 3,
respectively.
Table 2: Main chemical components (%)
of the natural, heated and leached
vermiculites.
Sample SiO2 Al2O3 Fe2O3 MgO K2O
NV 41.02 8.90 8.36 19.91 4.63NV-20 44.22 9.32 8.77 20.21 4.65
NV-90 64.81 4.32 5.08 10.95 2.58
HV 44.39 10.09 9.31 21.69 5.20
HV-20 45.59 9.56 9.08 21.18 4.89
HV-90 62.10 4.94 5.54 13.18 3.03
Table 3: Surface area values (m2/g) of the
natural, heated and leached vermiculites.
NV NV-20 NV-90
3.322 5.632 251.844
HV HV-20 HV-90
13.963 15.429 97.950
(Table 2) showed that when the natural
and heated samples were leached at 20C(NV-20 and HV-20, respectively), there
were only small changes in the values of
main chemical components, indicatinginsignificant dissolution from the clay
samples. Due to the low amounts of
dissolution of the structural components,
i.e. Mg, Fe and Al, the increases in the
surface area values of the leached
vermiculites were also low (Table 3).
On the other hand, when leaching process
was performed at 90C (samples NV-90and HV-90), the amounts of magnesium,
iron and aluminum in the leach residuesbecame approximately half of their initial
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values, which indicated quantitative, but
not total, dissolution of the clay structures
in both samples. Although surface area of
the heated sample is higher than the
natural one, the amount of residualstructural components in its leach
residues were higher in comparison to the
residues of the natural sample probably
due to the presence of dehydrated and
collapsed clay structures in the heated
sample [Okada et al., 2006; Steudel et al.,
2009a,b].
In the studies where micron grade South
African vermiculite was used; Okada et
al. [2006] were increased the surface areafrom 1 to 265 m2/g by leaching the
natural sample in 1 M H2SO4solution at
70C for 60 minutes; Temuujin et al.[2003] were increased the surface area
from 1.4 to 407 m2/g by leaching the
natural sample in 1 M HCl solution at
80C for 60 minutes and to 553 m2/g byleaching under same conditions for 120
minutes; and Temuujin et al. [2008] were
increased the surface area again from 1.4to 547 m2/g by leaching the heated (at
600C) sample in 2 M HCl solution at80C for 120 minutes. In this study, thesurface area of the natural (3.322 m2/g)
and heated (at 900C, 13.963 m2/g)micron grade South African vermiculite
samples were increased to 5.632 m2/g and
15.429 m2/g by low temperature (20C),and to 251.844 m2/g and 97.950 m2/g for
high temperature (90C) leaching in 1 M
H2SO4 solution for 60 minutes,respectively (Table 3).
The adsorption-desorption isotherms and
pore size distribution of the leach residue
HV-90 were given in Figures 1 and 2,
respectively. As can be seen from Figure
1, there is a hysteresis loop which
suggests the presence of mesopores in the
sample. There are no micropores present
in the sample. Due to the shape of the
isotherm in the region of higher relativepressures, it can be said that there could
be some small amount of macropores
present in the sample. The total pore
volume of HV-90 was 0.1326 cm3g-1.
The presence of mesopores wasconfirmed by the pore size distribution
study. As can be seen from Figure 2, the
structure contains almost no other type of
pores than mesopores with radii between
1.5 and 10 nm (the diameters between 3
and 20 nm). The measurement from
adsorption isotherm confirmed the
presence of so-called tensile strength
effect, because the peak with maximum
around 2 nm present in case of pore size
distribution calculated from thedesorption isotherm does not present.
Figure 1: Nitrogen adsorption/desorption
isotherm for HV-90.
Figure 2: Pore size distribution for HV-
90.
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3.2. XRD AnalysesXRD patterns of the natural and heated
samples together with their leached
counterparts were given in Figures 3 and
4, respectively.
Figure 3: XRD patterns of the natural
vermiculite and its leach residues.
Figure 4: XRD patterns of the heated
vermiculite and its leach residues.
XRD pattern of the natural sample (NV
in Figure 3) shows diffraction peaks at
6.22, 7.18 and 7.48, indicating thepresence of both two- and one-water-
layer hydration states and interstratified
phases [Ruiz-Conde et al., 1996; Marcos
et al., 2009; Muiambo et al., 2010]. High
content of potassium (see Table 1) in the
natural sample in comparison to truevermiculites also indicated the presence
of interstratification [Muiambo and
Focke, 2012]. Very small intensity peak
at 8.80 was attributed to mica impurity[Muiambo et al., 2010]. The main and
single basal peak at 8.86 in XRD patternof the heated sample indicated the
existence of dehydrated and collapsed
clay structures.
Leaching of the natural and heatedsamples at 20C in 1 M H2SO4 solutioncaused small changes and only
insignificant differences in the peak
intensities of clay structures were
observed, in accord with the chemical
analyses results. On the other hand,
leaching of the natural sample at 90Ccaused major dissolution of the
vermiculite structures as observed by the
disappearance of peak at 6.22 (compareNV or NV-20 with NV-90 in Figure 3).
The intensities of the basal peaks were
also greatly reduced and background of
the pattern was increased, both
suggesting amorphization by dissolution
of the clay structures.
Heating of the natural sample at 900Cproduced dehydrated and collapsed clay
structures, which resemble micas, as
observed by the main peak at 8.86 (seepattern HV in Figure 4). Although thechanges caused by acid leaching in the
natural sample were easily observable by
the analyses of XRD peaks in the related
patterns, almost no changes were
observed in case of the heated samples.
Only very small increase was observed in
the background intensity in XRD pattern
of the leach residue obtained by leaching
of heated vermiculite sample in 1 M
H2SO4 for 60 minutes (see HV-90 inFigure 4).
2()
NV
NV-20
NV-90
2()
HV
HV-20
HV-90
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3.2. FT-IR AnalysesFT-IR spectra of the natural and heated
samples together with their corresponding
leached counterparts were given in
Figures 5 and 6, respectively.
Figure 5: FT-IR spectra of natural
vermiculite and its leach residues.
Figure 6: FT-IR spectra of heated
vermiculite and its leach residues.
FT-IR spectrum of the natural sample
shows a broad and very strong intensity
absorption band at 999 cm-1belonging to
Si-O-Si and Si-O-Al vibrations. The
strong intensity band (with a shoulder)centered at 457 cm-1 may be associated
with Si-O-Si and Si-O-Mg. The medium
intensity absorption at 1632 cm-1 is
attributed to the OH bend deformation of
water. The medium band observed at 687
cm-1may be related with R-O-Si, where
R=Mg, Al or Fe. The weak bands at 602,
729 and 818 cm-1 may be assigned to
mixed Al-O/Si-O and hydroxyl groups
[Suquet et al., 1991; Ravichandran and
Sivasankar, 1997; da Fonseca et al., 2006;Steudel et al., 2009a; Chmielarz et al.,
2010; Muiambo et al., 2010; Hongo et al.,
2012; Muiambo and Focke, 2012].
In accord with the results of XRD
analyses, low temperature acid leaching
caused only small changes in the FT-IR
spectra of both the natural and heated
vermiculites. But, high temperature acid
leaching changed the corresponding IRspectra dramatically, because of the
sensitivity of FT-IR spectroscopy for
detecting the possible changes (or
destruction) in the crystalline structure of
clay minerals following any modification
process [Suquet et al., 1991]. By high
temperature leaching of the natural
sample, bands at 602, 687, 729 and 818
cm-1 disappeared and new absorption
peaks of Si-O at 1088 (with shoulder
~1200 cm
-1
), 800 and 461 cm
-1
, andSiOH at 968 cm-1 belonging to hydrous
amorphous silica phase were revealed
[Plkov et al., 2003; Wypych et al.,2005; Yu et al., 2012]. This indicates the
formation of hydrous amorphous silica
phase by acid dissolution of the structural
components from the natural and heated
vermiculites. Similar changes were also
observed by high temperature acid
leaching of heated vermiculite sample but
the effect of acid leaching is somewhatlower when compared to the natural
HV
HV-90
HV-20
Wavenumber (cm-1
)
NV
NV-90
NV-20
Wavenumber (cm-1
)
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sample. The absorption band at 1007 cm-1
belonging to the heated sample also
indicated the higher resistance of
collapsed mica like layers against acid
attack, which is consistent with theresults obtained by chemical and XRD
analyses.
4. CONCLUSIONSIn this work, the leaching behaviours of a
natural and a heated vermiculite sample
in 1 M H2SO4solution at 20C and 90Cfor 60 minutes were investigated using
different analyses methods. Although no
or small changes occurred in chemical
compositions, in XRD/FT-IR patterns andsurface area values of the leach residues
obtained by low temperature (20C) acidleaching, significant reductions in the
amounts of structural components,
important changes in XRD and especially
in FT-IR patterns and great increases in
surface area values of the leach residues
obtained by high temperture (90C) acidleaching of the natural and heated
vermiculites were observed. All results ofthe analyses methods indicated that
hydrous amorphous silica phase was
formed following high temperature acid
leaching of the natural and heated
vermiculites due to the dissolution of
structural components from the clay
structures. Under any leaching condition
studied, the heated vermiculite showed
higher resistance against acid leaching
probably due to the presence of collapsed
mica like layers. According to the datacollected in this work, a new leaching
study was initiated for determining the
high temperature (90C) acid leachingbehaviour of the vermiculite samples at
different sulphuric acid concentrations
and for the preparation of higher surface
area and purer hydrous amorphous silica
phases suitable for various applications.
Acknowledgements:The authors wish to
acknowledge Mike Darling (PalaboraEurope Ltd.) for the supply of natural
vermiculite sample. Two of the authors
(E.T. and M.B.) thanks the Slovak Grant
Agency VEGA (project 2/0064/14) and
the Agency for Science and Development
(APVV-0189-10) for the partial support.
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Londo, M.G., Yang, X. and Young, R.H., 2001.
Mesoporous silicoaluminate pigments for use
in inkjet and carbonless paper coatings, US
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Marcos, C., Arango, Y.C. and Rodriguez, I., 2009.
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Applied Clay Science, 42, 368.Mokaya, R. and Jones, W., 1995. Pillared clays
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catalytic properties, Journal of Catalysis, 153,
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Muiambo, H.F. and Focke, W.W., 2012. Ion
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onset temperatures, Molecular Crystals and
Liquid Crystals, 555, 65.Muiambo, H.F., Focke, W.W., Atanasova, M., van
der Westhuizen, I. and Tiedt, L.R., 2010.Thermal properties of sodium-exchanged
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Okada, K., Arimitsu, N., Kameshima, Y.,
Nakajima, A. and MacKenzie, K.J.D., 2006.
Solid acidity of 2:1 type clay minerals
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Plkov, H., Madejov, J. and Righi, D., 2003.Acid dissolution of reduced-charge Li- and
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materials by chemical activation of the Llanovermiculite, Clay Minerals, 26, 49.
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Turianicov, E., Obut, A., Tuek, ., Zorkovsk,A., Girgin, ., Bal, P., Nmeth, Z., Matik,M. and Kupka, D., 2014. Interaction of
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with gaseous carbon dioxide during
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Wypych, F., Adad, L.B., Mattoso, N., Marangon,A.A.S. and Schreiner, W.H., 2005. Synthesis
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MECHANICALLY INDUCED CHANGES ON CRYSTAL
STRUCTURE AND THERMAL BEHAVIOUR OF INDUSTRIAL
MINERALS: CASE STUDIES FOR COLEMANITE, PYROPHYLLITE
AND QUARTZT. Uysal1,a, M. ener1, H. Topta1, . S. Karamaz1, S. Yazc1, Y. Erolu1and
M. Erdemolu1
1. nn University Department of Mining Engineering, 44280 Malatya, Turkeya. Corresponding author ([email protected])
ABSTRACT: Some advanced engineering materials like B4C, CaB6, SiC, Si3N4, Si or
Al2O3are obtained by thermal treatment methods as calcination roasting or carbothermic
reduction. In this study, intensive planetary ball milling was employed to mechanically
activate selected minerals such as colemanite (Ca2B6O11.5H2O), pyrophllite
(Al2Si4O10(OH)2) and quartz (SiO2) in order to alter their thermal behaviour in the high
temperature processes. Unmilled and milled mineral samples were then roasted to
determine high temperature phases of the minerals. Minerals were also analysed using
thermogravimetry. By comparing the crystal structures and thermal behaviors of the
minerals investigated, the footprints of the mechanical activation were investigated. It was
concluded that mechanical activation of these industrial minerals can provide more useful
outputs in the production of the advanced materials at low costs.
1. INTRODUCTION
Mechanical activation (MA) is a pre-treatment method applied to increase the
reactivity of mineral in metallurgical
processes like roasting, carbothermic
reduction or leaching, and performed in
the new generation grinding mills where
the mechanical energy is intensively
transformed into mineral treated. During
MA, size of the mineral particles gets
finer and the formation of defects in the
crystal structure occurs due to mainly the
mechanical energy density [Bal andEbert, 1991]. Decreasing the reaction
temperatures, increasing the reaction rate,
preparation of water soluble compounds,
necessity for less expensive reactors and
shorter reaction times are some
advantages of MA [Erdemolu, 2009].
Various enginering ceramics are
manufactured generally by thermal
treatment of naturally occurring minerals.
Of these, colemanite (Ca2B6O11.5H2O),pyrophllite (Al2Si4O10(OH)2) and quartz
(SiO2) minerals are used as the primary
raw material in the production of severaladvanced materials.
Colemanite is the most occurring type of
the boron minerals. Advanced materials
such as silicon (Si), boron nitride, (BN),
titanium diboride (TiB2), boron carbide
(B4C) and calcium hegzaboride (CaB6)
are some of the examples that have
applications in the boron industry [Tekin,
1990; ekerci, 2000; stn, 2002]. For
instance, CaB6 is used in a variety ofindustrial applications, where it is known
as an abrasive and deoxydation material
because of its hardness and electronic
properties. CaB6 was reported by Yldzet al. (2005) to be produced from
colemanite. However, direct use of
colemanite is so problematic that
transporting raw colemanite and
removing impurities and crystal water
later is expensive and energy inefficient.
Thus colemanite must then undergo heattreatment before use. These compounds
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are used in most of today's high-tech
materials and are sold to 10-20 times the
cost. In our country, some of these
products espacially used in a variety of
cutting and etching materials areimported at very high prices.
Pyrophyllite is an aluminum silicate
mineral with Al2Si4O10(OH)2 formula.
Regarding the usage, it belongs to family
of high alumina clays like kyanite,
andalusite and diaspore [Cornish, 1983].
These alumina containing materials
exhibit very good thermal shock
resistance at high temperatures. Largely
depending on this, they are used in thefabrication of alumina refractories.
Investigations on pyrophyllite based
refractories and ceramics have revealed
some unique advantages, leading to high
corrosion resistance to molten iron, steel
and the slag in iron-steel works; good
thermal shock resistance, low
deformation under load, and good
mechanical resistance in the production
of ceramics. Thus, thermal treatment isvery important mainly mullite
(3Al2O3.2SiO2) requiring processes.
Silicon is one of the most found elements
in the Earths crust.But it is not availablein the element form. It is found as
compounds with oxygen in the form of
quartz or silicates. One of the most
important use of Si is in the solar cells.
Photovoltaic cell manufacturers mostly
use silicon, which can convert sunlightdirectly into electricity. 98% of the solar
cells are from silicon. Metallurgical grade
silicon is primaryly produced by high
temperature treatment of high grade silica
sand with a carbon source.
In this present study, effects of intensive
planetary ball milling on the crystal
structure and thermal behaviour of
selected minerals of colemanite
(Ca2B6O11.5H2O), pyrophllite(Al2Si4O10(OH)2) and quartz (SiO2) were
examined to determine whether the
milling resulted in an mechanical
activation or not.
2. MATERIALS and METHODSColemanite (Ca2B6O11.5H2O) of a high
grade colemanite concentrate, pyrophllite
(Al2Si4O10(OH)2) hand picked from the
mine and quartz (SiO2) from high grade
silica sand were used. All mineral
samples were dry milled in air by a
planetary ball mill. 250 cm3 tungsten
carbide bowl and 10 mm balls of the
same material were used. Colemanite and
pyrophyllite samples were milled alone,
whereas silica sand was milled togetherwith coke.
To define the crystal structure of the
unmilled but gently powdered for particle
size reduction, and intensively milled
mineral samples were analysed using
Rigaku RadB model X-ray diffractometer
(XRD). Thermal behavior of all samples
were determined using Setaram
Labsys1600 Model TGA/DTA
instrument operates in argon atmosphere
and up to 1600C.
3. RESULTS and DISCUSSIONFor determining the effects of intensive
milling on the structure of crystal
colemenite, it was milled and the milled
products were analysed by using XRD.
Milled colemanite samples were then
roasted to determine the solid phases
remained. (Figure 1) shows XRD patternsof unmilled and milled, and then roasted
colemanite. In the original colemanite
(K00) sample, there are some calcite
(CaCO3) and gypsum (CaSO4.2H2O). All
other peaks belog to colemanite. As also
seen from the Figure 1, intensive milling
for 45 min (Sample K4-45), not
completely but partially, altered the
crystal structure of colemenite. At the
examples subjected to mechanical
activation, colemanite crystal peakintensities decreased with milling.
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Accordingly, mechanical activation
caused disruption of the crystal structure
of this borate mineral. However, this
disorder is not very clear and maybe
gradual. When these samples wereroasted up to 500C it was found thatcolemanites peaks disappeared and
almost amorphous structure occurred. It
can be proposed that colemanite begin to
transform into dehydrated form, maybe
just calcium borate. When the
temperature was increased to 800C, newXRD peaks occurs, depending on the
recrystallisation of anhydrous colemanite.
Figure 1: Comparison of XRD patterns for unmilled (K00) and 45 min milled (K4-45)
colemanite samples, and of roasted at 425, 500 and 800 C (Symbols: , calcite; gypsum).
Seen in (Figure 2) are TG curves for
unmilled and 45 min milled colemanite
samples. Thermal decomposition
depending on initially loss of crystal water
begins nearly but not very significantly at
337 C and continues up to 700 C for
unmilled colemanite. At 363 C, otherstrong hydrogen bonds of water moleculesare broken and then borate structure is
began to decompose. When the
temperature is at between of 393-400 C,decomposition rate reaches to maximum
depending on the final release of water
molecules in the pores. This phenomenon
causes sudden crash of the samples, known
as decrepitation [Uzunolu, 1992; elik etal., 1994; ener and zbayolu, 1995].
After 700 C, colemanite converts tosintered colemanite. It was also
demonstrated by Yldz (2004) thatcolemanite loses its crystal water through
endothermic reactions at 300-460 C andthat decrepitation and decomposition of
colemanite to amorphous B2O3 and CaO
takes place at temperatures lower than 600
C, and finally CaB2O4 and Ca2B6O11appear as new crystalline boroncompounds at 800 C. When compared toTG curve of unmilled colemanite, 45 min
milled colemanite losses its water at very
low temperatures. Since the interval
between onset and offset temperatures
appears within very big interval,
decrepitation of milled colemanite does not
occur. In addition, decrepitation of the
milled colemanite was not observed during
atmospheric roasting experimentsperformed at isothermal conditions.
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Figure 2: Comparison of TG curves
obtained for unmilled and 45 min milled
colemanite samples.
(Figure 3) collectively shows XRD
patterns for pyrophyllite samples which
unmilled (P0, just gently milled), 45 min
milled (P45), and then roasted at various
temperatures. Major minerals determined
in pyrophyllite samples are pyrophyllite
(Al2Si4O10(OH)2), quartz (SiO2), kaolinite
(Al2Si2O5(OH)4) and dickite
(Al2Si2O5(OH)4). It was found that milling
for 45 min significantly results in decrease
mainly at the peak intensities ofpyrophyllite, kaolinite and dickite. Peaks
which remain after 45 min of milling fully
belong to quartz.
It is reported that when the milling time
increases, dry milled pyrophyllite losses its
original crystal structure depending on the
creep of tetrahedral-octahedral layers
[Prez- Rodriguez et al., 1988]. Erdemoluand Sarkaya (2002) was also reported thatcollectorless flotation recovery of
pyrophyllite decreases with prolonged
milling due to structural deformationoccurred during the milling.
In order to determine the effects of heat
treatment on the thermal behaviour
unmilled and milled pyrophyllite samples
were roasted at different temperatures and
the raosted samples were also analysed for
their crystal structure.
As seen in (Figure 3), peaks of
pyrophyllite and kaolinite are disappearedin the unmilled sample roasted at 800C,whereas they are not present in the milled
sample even at roasting temperatures as
low as 400C. Peaks of kaolinite found inthe unmilled sample disappeared at 800C,whereas 700C was enough fordecomposition of kaolinite present in the
milled pyrophyllite sample. Morover, new
peaks occurred at high temperatures
belonging to mullite with a nominal
composition of 3Al2O3.2SiO2 are very
common in the milled pyrophyllite samples
roasted at temperatures as low as 400C,when compared to those of unmilled
samples.
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Figure 3: Comparison of XRD patterns for unmilled (P0), 45 min milled (P45) and then
roasted phyrophyllite samples.
Thermograms obtained by roasting of
unmilled and milled pyrophyllite at
isothermal heating conditions are shown inFigure 4. It seems that pyrophyllite losses
its bound water without any structural
changes at temperatures between 400 and700C. At temperatures near to 800C,
pyrophyllite converts into a mullite-like
aluminium silicate form and stays steady
up to 1000C. After this temperature,mullite-phase conversions begin and free
quartz present converts into the
crystobalite which is a high-
temperature polymorph of quartz. It wasfound that intensive milling significantly
changes the thermal behaviour of
pyrophylite. Mass loss in 20 min of milled
pyrophyllite sample begins at 400C,whereas it is almost 500C for unmilledsample. Besides, mass loss of unmilled
pyrophyllite at 700C was calculated as2.5%, whereas it is 3.8% pyrophyllite
sample which was milled for 60 min.
Consequently, conversion of pyrophyllite
into mullite shifted to low temperatures,suggesting the mechanical activation. In
the literature, it was reported that
transformation in the pyrophyllite begins
with the milling; milling longer than 7 minchanges the thermal behaviour; according
to TG curves, onset temperature at which
mass loss begins decreases and
endothermic reaction region shifts to occur
at low temperatures [Prez-Rodriguez andSnchez-Soto, 1991].
Figure 4: TG curves for unmilled and
milled (20, 45 and 60 min) pyrophyllite as
obtained by isothermal roasting tests.
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Silicon carbide is manufactured by
charbothermic roasting of high purity silica
in the presence of coke:
SiO2+ 3C SiC + 2CO
Metallurgical-grade silicon used for many
purposes including photovoltaics is
obtained from the reduction of silicon in
the presence of carbon at high
temperatures:
SiO2 + 2C Si + 2CO
In order to determine the effect of intensive
milling on the carbothermic roasting and
reduction of quartz, high purity silica sandwas mixed with metallurgical grade coke;
milled for long periods and finally the
milled mixtures roasted at 1200 C for halfa day. Unmilled, milled and roasted
materials were characterised using XRD
and TGA.
As seen from Figure 5, XRD patterns of
unmilled mixture are very simple. Since
silica sand is very pure, one and only the
crystal mineral phase seems as quartz. All
the peaks on the patterns are belongs to
quartz. Since coke is in the amorphous
phase, it was not determined by XRD
analysis. However, intensities of the quartz
XRD peaks decreased and peak areas
enlarged gradually with prolonged miling.
Milling 5 h resulted in the amorphisation
of quartz in the silica sand-coke mixture.
Since the presence of coke in the mixture
behaved as grinding additive, 10 h ofmilling gave a complete amouphous
material.
XRD patterns for unmilled and 10 h milled
silica sand-coke mixtures both which were
roasted at 1200C for 12 h werecollectively shown in Figure 6. Seen on the
XRD pattern of unmilled and then roasted
silica sand-coke mixture is quartz with a
little bit high peak intensities due to heat
treatment. But, the materials includingquartz in the 10 h milled mixture were
completely amorphous, roasting of milled
mixture at 1200 C gave also rise toappearance of crystal quartz. But in this
case, quartz is in crystobalite phase. All of
the peaks reappeared belong to crystobalite
quartz. It is known that quartz is in
trydimite phase after 870C and incrystobalite phase after 1470 C. Since thecrystobalite phase is obtained just at 1200
C, this result solely suggests mechanicalactivation which provides phase
transformation of quartz to occur at low
temperatures.
Figure 5: XRD patterns of unmilled and milled (1, 5, 10 h) silica sand-coke mixtures.
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Figure 6: Comparison of the XRD patterns for the unmilled and 45 min milled silica sand and
coke mixtures roasted at 1200C for 12 hours in the air.
Figure 7: TG curves for unmilled silica
sand only, unmilled and milled (1, 5 and
10 h) silica sand-coke mixtures as obtained
by non-isothermal analysis in argon.
Shown in (Figure 7) are TG curves for
original silica sand only, unmilled and 1, 5
and 10 h milled silica sand-coke mixtures,
as obtained by thermal analysis performed
up to 1400 C. On TG curve of theunmilled original silica sand only, mass
loss onset temperature is about 1300C,whereas it is about 1050 C for theunmilled silica sand-coke mixture. It seems
that milling considerably changed the mass
loss starting temperature which decreaseswith milling time be longed from 1 to 5 h.
This may not be resulted from gasification
of carbon using O2originated from the air
to form COx gases, since TG analysis was
performed in argon atmosphere. According
to Sahajwalla et al. (2003), the reactionbetween SiO2 and C in powdery mixtures
has significant rates from about 1400Conwards in vacuum or in stream of argon.The reaction can be seen as a combination
of two basic reactions:
SiO2(s, l)+ C(s)SiO (g)+ CO(g)
SiO(g)+ 2C(s)SiC(s)+ CO(g)
The reactions taking place at the carbon
surface are also reported to play a role in
controlling reaction kinetics. Thus it was
suggested that the mass loss occurred inthe 1 and 5 h milled mixtures is due to
early reactions of silica and carbon to form
SiO gas and to release CO. But, TG curve
of the mixture milled for 10 is very
different. TG pattern is similar to others up
to 900-1000C, then the materialdramatically starts to gain mass up to
1350C and to loose its mass again withthe increasing temperature up to the end of
analysis limit. The mechanism causing this
thermal behaviour needs further study. Butwhat the observed is the clear effect of
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intensive milling on the charbothermic
reactions of quartz.
4. CONCLUSIONSIn this study, structural and thermal
alterations resulted from intensive millingof selected minerals such as colemanite,
pyrophyllite and quartz were investigated,
which are processed generally at very high
temperatures in their metallurgy.
For each of the minerals examined in this
study, it was typically found by XRD
analysis that intensive milling appearently
alter or deform the crystal structure of the
minerals, as leading to become XRD
amourphous as a final point. There was aremarkable result so that quartz present in
the pyrophyllite sample resists to the action
of intensive milling while the quartz in the
silica sand-coke mixture easily goes to
become amorphous.
Studies performed either at non-isothermal
or isothermal heating conditions showed
that, as compared to their unmilled
counterparts, thermal behaviour of the
intensively milled minerals significantly
was altered to release their volatile content
at low temperatures, mainly due to
mechanical activation.
Finally, it was concluded that mechanical
activation may be one of the keys to
develop existing technologies for
manufacturing many of the high
temperature processed engineering
materials like oxides (Al2O3, ZrO2),nitrides (AlN, BN), borides (CaB6, TiB2),
carbides (SiC, TiC, WC, B4C) at low-costs.
Acknowledgement: Financial supports of
nn University (BAPB Project Numbers:2012/108 and 2012/14) is gratefully
acknowledged.
REFERENCESBal P., Ebert I., 1991. Oxidative leaching of
mechanically activated sphalerite,
Hydrometallurgy, 27, 141-150.
elik, M.S., Uzunolu, H.A., Arslan, F., 1994.Decrepitation properties of some boron
minerals, Powder Technology ,79,167172.Cornish, B.E. 1983. Pyrophyllite. Industrial
Minerals and Rocks, SJ.Lefond (Ed.) SME
Publications, s.1085-1108, New York.
Erdemolu M., Carbothermic reduction ofmechanically activated celestite, Int. J. Miner.Process. 92, 144152, (2009).
Erdemolu, M., Sarkaya, M., 2002. The effect ofgrinding on pyrophylliye flotaion, MineralsEngineering, 15, 723-725.
Prez-Rodriguez, J.L., Madrid Sanchez Del Villar,L., Snchez-Soto, P.J. 1988. Effects of drygrinding on pyrophyllite. Clay Minerals. 23,399.
Prez-Rodriguez, J.L., Snchez-Soto, P.J. 1991.The Influence of the Dry Grinding on the
Thermal Behavior of Pyrophyllite. Journal of
ThermalAnalysis. 37:1401.
Sahajwalla, V., Wu, C., Khanna, R., SahaChaudhury, N., Spink, J., 2003. Kinetic study of
factors affecting in Situ reduction of silica in
carbon-silica mixtures for refractories. ISIJ
International, 43(9), 13091315.ekerci Y., 2002. Calcium hegzaboride production.
BSc Thesis. Afyon Kocatepe University,
Ceramics Engineering Department, Afyon.
ener, S., zbayolu, G., 1995. Separation ofulexite from colemanite by calcination,Minerals Engineering, 6, 697-704.
Tekin A., 1990. High technology ceramics and
developments in Turkey. Proceedings of 4th Int.
Ceramics Congress, p317, stanbul.stn, R., 2002. Titanium diboride production.Afyon Kocatepe University, Ceramics
Engineering Department, in Turkish, Afyon.
Uzunoglu, A., 1992. Decrepitation properties of the
boron minerals colemanite and ulexite. Master
of Science Thesis, Technical University of
Istanbul, in Turkish, 1992.
Yldz, ., 2004. The effect of heat treatment oncolemanite processing: a ceramics application,
Powder Technology, 142, 7-12.
Yldz, ., Telle, R., Schmalzried, C., Kaiser, A.,2005. Phase transformation of transient B4C to
CaB6 during production of CaB6 fromcolemanite. Journal of the European Ceramic
Society, 25, 3375-3381.
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OPTIMUM USE OF ZEOLITE IN THE PRODUCTION OF BLENDED
CEMENT
Melis Toker Derdiyok1and Hasan Ergin1,a
1. Istanbul Technical University, Mining Engineering Department, Istanbul, Turkey
a. Corresponding author ([email protected])
ABSTRACT:Cement industry is an energy-intensive process and results in large amount of CO2
emissions. This study is aimed at reducing energy consumption and the emissions by using
zeolite as a substitute of clinker. Firstly, the physical, chemical and mineralogical
characterization of zeolite was determined and the grinding properties of zeolite and
clinker were performed in laboratory ball mill. Then, the ground zeolite which has the
fineness of 5% residue on 32 micrometer sieve was substituted for clinker by 10% and
20%. The physical, chemical and mechanical analyses were conducted on produced
blended cements in accordance with standards. The use of zeolite has resulted in an
increase in the compressive strength at 90 days and also increase in setting time. It has also
been observed that the zeolite has much easier grindability than clinker. Therefore, the use
of zeolite reduces the grinding energy consumption and also emissions due to the use of
less amount of clinker usage without causing any degradation of cement properties. The
full results are illustrated in this article.
1. INTRODUCTIONCement is the biggest man-made and
used material in the world with its 3.6billion tons of annual production at 2013[Republic of Turkey Ministry of Economy, 2014].Production of cement is an expensive
process and has adverse ecological
effects. CO2, NOx, and SOx are among
the hazardous emissions generated in
relatively high volumes in the
conventional Portland cement process.
Zeolites are a group of crystalline
hydrated alumino silicates with uniquephysico-chemical properties resulting
from their specific structure in which
cavities or pores with strictly defined
nanodimensions occur [Mozgawa et al.,
2009]. The microporous crystalline
structure of zeolites is able to adsorb
species that have diameters that fit
through surface entry channels, while
larger species are excluded, giving rise to
molecular sieving properties that are
exploited in a wide range of commercialapplications. These include the use of
natural zeolites in water and air filtration,
pollution, and odour control, animal
hygiene, aqua-culture, pond filtration,soil amendment, and as an industrial filler
and dietary supplement in animal feeds
[Ortega et al., 2000]. Zeolite types that have
been tested so far are those most common
in the sedimentary zeolite (tuff) deposits
widespread all over the world, namely,
clinoptilolite, mordenite, phillipsite and
chabazite [Caputo et al., 2008].
Zeolite as natural pozzolan, which are
materials exhibiting cementitionsproperties, have been widely used as
substitutes for Portland cement clinker in
many applications because of reductions
in the production cost and CO2emission
[Kurudirek et al., 2010]. In a recent study,
Uzal et al. [2012] reported that the
clinoptilolite minerals of zeolite
possesses a lime reactivity which is
comparable to silica fume and higher than
fly ash and a non-zeolitic natural
pozzolan. They also concluded that thehigh reactivity of the clinoptilolite is
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attributable to its specific surface area for
certain grinding method and duration as
well as its reactive SiO2content.
In another study, the use of zeolitesamples, where collected from zmir-Foa, Balkesir-Bigadi and Manisa-Grdes, were investigated in ceramicindustry, in paper industry as filler and
coater and in the cement industry as
additive [Ulusoy & Albayrak, 2009].
Canpolat et al. [2004] investigated the
effects of zeolite, coal bottom ash and fly
ash as Portland cement replacement
materials. The results shown thatinclusion of zeolite up to the level of 15%
resulted in an increase in compressive
strength at early ages, but resulted in a
decrease in compressive strength when
used in combination with fly ash.
Karakurt & Topu [2012] reported thataccording to the results of accelerated
corrosion test; concretes produced with
zeolite, fly ash and ground granulatedblast furnace slag in ternary composition,
the corrosion were significantly reduced.
In this study, the usage of zeolite was
studied as clinker replacement material.
The zeolite was taken from Ktahya-Gediz. The experiments were carried out
at Nuh Cement Plant in Turkey.
2. MATERIALS & METHODOLOGY
2.1. MaterialsClinker, zeolite (Z) and gypsum were
used in this study. The chemical
compositions of these materials
determined by XRF. The results are given
in Table 1. The mineralogical analysis of
clinker and zeolite were also determined
by DTA as the results are presented in
Table 2.
Table 1: Chemical characteristics ofmaterials used (wt. %).
Clinker Gypsum Zeolite
CaO 65.91 32.4 5.81
SiO2 21.55 1.1 62.27
Al2O3 4.80 0.4 12.46
Fe2O3 3.29 0.1 1.51
MgO 1.34 0.1 5.81
SO3 0.48 44.50 0.16
K2O 0.78 0.05 3.65
Na2O 0.20 0.04 0.06
Loss on
ignition0.28 21.50 10.60
The specific gravity was determined by
Gas Pycnometer and the specific surface
area was measured by Blaine equipment.
Specific gravity of zeolite was found 2.24
g/cm3. Specific surface area of zeolite
was measured as 7969 cm2/g.
Table 2: Mineralogical characteristic of
clinker and zeolite.
Clinker (wt. %) Zeolite
C3S (58.48) Clinoptilolite
Illite mica
Opal-CT
Feldspar
SmectiteQuartz
C2S (47.69)
C3A (7.17)
C4AF (10.00)
C: CaO, S: SiO2, A: Al2O3, F: Fe2O3
The other authors were determined
morphology of zeolite by Scanning
Electron Microscope (SEM). As shown
in Figure 1, the particles are typically
euhedral plate prism, monoclinic and its
crystal size is 5-10 micrometer [Esenli &
Gltekin, 2011].
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Figure 1: SEM image of zeolite.
2.1. MethodologyFigure 2 shows the experimental design
of investigating the usability of the
zeolite as a substitute of clinker in
production of blended cement. Firstly;
the crushing and grinding test were
performed in order to compare the
grindability of the zeolite and clinker.
The zeolite was crushed in a laboratory
jaw crusher under the size 5 mm.
Then, the comparative test for grindingproperties of clinker and zeolite were
carried out in a laboratory ball mill. The
ball mill is 52 cm in length and 42 cm in
diameter as it has a rotational speeds of
46 rev/min. The ball sizes ranging from
60 to 15 mm are in total of 215 balls. Its
total weight is 58.58 kg.
The particle size distributions were
determined by Laser particle size
analyzer. Average particle size of groundclinker was 13.70 micrometer after 60
minutes of grinding. Average particle size
of ground zeolite was 7.85 micrometer
after 45 minutes. Thus, it has been found
as a result of grinding test, zeolites can be
ground easier than clinker.
In the final stage, the features of
reference cement was determined that
contains 95% clinker and 5% gypsum,
called Portland cement (R) that is CEM I
called as reference cement. After that, the
ground powders of zeolite, which has the
fineness of 5% residue on 32 micron
sieve, were added by 10% and 20% to the
ground clinker and gypsum.
Figure 2: Experimental processes to
investigate the usability of zeolite.
In experimental studies; the physical,
chemical, and mechanical analysis
(setting time, volume expansion,
compressive strength, fineness, Blaine)
were conducted on produced Blendedcements in accordance with Turkish
Standards that comply with European
Standards. TS EN 196-3 is for setting
time and volume expansion, TS EN 196-
6 is for Blaine and fineness, TS EN 196-1
is for compressive strength (Turkish
Standard, 2000, 2002, 2009). Chemical
analysis of the samples was performed
using X-ray spectrometer. Setting time
was determined by the Automatic Vicat
apparatus.
Determination of expansion of the
Blended cements was carried out by the
Le Chateliers. Fineness of Blendedcements was found by using both Blaine
apparatus and Air Jet Sieve. Compressive
strength of Blended cements was
determined in samples having dimensions
of 40 mm x 40 mm x 160 mm with
prismatic shape at the ages of 2, 7, 28,and 90 days.
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3. RESULTS AND DISCUSSIONBlended cements recipes were labelled
according to the amount of zeolite
additions. The cement mix recipes are
given Table 3.
Table 3. Mix proportions of the cements
(% mass).
Clinker Zeolite Gypsum
R 95 - 5
Z10 85 10 5
Z20 75 20 5
The physical properties of reference
cement and the cements containing
zeolite called blended cements are
presented in Table 4. The specific gravity
values were determined as the average of
four measurements. The fineness of
blended cements was determined using
sieves of 32 micrometer and 90
micrometer.
The specific gravity of the blendedcements was reduced while the specific
surface area was increased by the
addition of zeolite. Initial and final
setting times of blended cements were
longer than that of reference cement R.
The volume expansion, the fineness and
the compressive strength were within the
specified value in the standards. The
compressive strength values of R, Z10
and Z20 are presented in Figure 3.
Table 4: Physical characteristics of R and
the cement containing zeolite (% mass).
R Z10 Z20
Specific gravity
(g/cm3)3.15 2.98 2.88
Specific surface
(cm2/g)3343 5213 6063
Fineness
(32 micrometer) 27.2 23.7 23.0
Fineness
(90 micrometer)7.4 2.8 2.8
Initial setting
time
(minute)
124 173 174
Final setting
time
(minute)
157 227 260
Volume
expansion
(mm)
10 10 9
Figure 3: Compressive strength test results of reference cement and blended cements.
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4. CONCLUSIONSBlended cement produced by the addition
of zeolite was analyzed and their
compressive strength development was
compared at 2, 7, 28 and 90 days withreference cement R. The produced
blended cements comply with the
standards. Zeolite can be used as
substitute till 20% without any quality
degradation. Moreover, the use of zeolite
also contributes to the compressive
strength of the final product. Since the
grinding energy consumption of zeolite is
much less than clinker so that the usage
of the zeolite provides some economic
advantages as well.
Acknowledgements: This research has
been done in Nuh Cement Plant and was
supported by Turkish Cement
Manufacturers Association.
REFERENCESCanpolat, F., Ylmaz, K., Kse, M.M., Smer, M.,
yurdusev, M.A., 2004. Use of zeolite, coal
bottom ash and fly ash as replacement
materials in cement production, Cement andConcrete Research, Volume (34), pp. 731-
735.
Caputo, D., Liguori, B., Colella, C., 2008. Some
advances in understanding the pozzolanic
activity of zeolites: The effectof zeolite
structure, Cement and Concrete Composites,
Volume (30), pp. 455-462.
Esenli, F., Gltekin, A.H., 2011. SANTEKMining CompanyGediz (Ktahya) AreaZeolite (Clinoptilolite) Material
Characteristics, Internal Report, Istanbul
Technical University, Mining FacultyDepartment of Geological Engineering.
Hewlett, P.C. (ed), 2004. Leas chemistry ofcement and concrete, 4th edn, Oxford:
Elsevier Butterworth-Heinmann, Oxford.
Karakurt, C., Topu, I.B., 2012. Effect of blendedcements with natural zeolite and industrial
by-products on rebar corrosion and high
temperature resistance of concrete,Construction and Building Materiaals,
Volume (35), pp. 906-911.
Kurudirek, M., zdemir, Y., Trkmen, I., Levet,A., 2010. A study of chemical composition
and radiation attenuation properties in
clinoptilolite-rich natural zeolite from
Turkey, Radiation Physics and Chemistry,
Volume (79), pp. 1120-1126.
Mozgawa, W., Krol, M., Pichor, W., 2009. Use of
clinoptilolite for the immobilization of heavy
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