Cryptocrystalline and macrocrystalline magnesite ores · The super fine crystal structure of the...
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Dr. Beyhan Ozdemir, KUMAS Kutahya Manyezit Isletmeleri A.S. Cryptocrystalline and macrocrystalline magnesite ores 1
Transcript of Cryptocrystalline and macrocrystalline magnesite ores · The super fine crystal structure of the...
Dr. Beyhan Ozdemir, KUMAS Kutahya Manyezit Isletmeleri A.S.
Cryptocrystalline and macrocrystalline magnesite ores
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CONTENTS
1. Objective
2. Types of natural magnesite deposits
3. Examination and evaluation of magnesite ore
4. Microstructures SEM, XRD and TG-DTA analysis results
5. Firing of samples and results
- Single firing results
- Double firing results
6. Conclusion
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OBJECTIVE
In this study, brickmaking grades of high quality magnesite resources were compared.
two cryptocrystalline magnesite samples
FROM TURKEYKUMAS MINE
FROM AUSTRALIA
one macrocrystalline magnesite sample
FROM CHINA
COMPARISION OF MAGNESITE TYPE
&
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TYPES OF NATURAL MAGNESITE DEPOSITS
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1- Serpentine Alteration by Hydrothermal Process – CO2 rich waters alter magnesium-rich serpentinite
3- Sedimentary Type- Ultrabasic rock may be weathered, eroded and transported to lake to
precipitate magnesite
4- Replacement of Limestone and Dolomite - Magnesia rich fluids attack dolomite or limestone.
CRYPTOCRYSTALLINE / AMORPHOUS MAGNESITE Turkey, Greece, Australia, Albania, Egypt, Iran, Nepal
MACROCRYSTALLINE /SPARRY /BONE MAGNESITE Austria, Slovakia, Spain, Canada, Brazil, Southern India (Uttar Pradesh),
China, North Korea, Russia
2- Magnesite Formation by Infiltration- the weathering of serpentine by CO2-laden waters
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Source: 1- “World Resources of Magnesite and Market Utilisation”, Ian Wilson, IM MagMin, Amsterdam, May 20092- “The Industrial Minerals Handy Book”, a guide to markets, Peter W. Harben3- “The Chemistry and Technology of Magnesia”, Mark A. Shand
CRYPTOCRYSTALLINE / AMORPHOUS
MAGNESITE
MACROCRYSTALLINE /SPARRY /BONE
MAGNESITE
Marble like crystallinity
Often of high quality with low CaO, Fe2O3 Higher Fe2O3 and impurities
Generally white color Various colors, but color doesn’t reflect grade.
Present in huge depositsTends to occur in smaller and shallow deposits
Present in veins and stockworks.
Fine crystal size 1-10 micron Large crystal size in cms.
Massive with a characteristic conchoidal fracture
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Source: 1- “World Resources of Magnesite and Market Utilisation”, Ian Wilson, IM MagMin, Amsterdam, May 20092- “The Industrial Minerals Handy Book”, a guide to markets, Peter W. Harben3- “The Chemistry and Technology of Magnesia”, Mark A. Shand
TYPES OF NATURAL MAGNESITE DEPOSITS
Source: Ian Wilson, November 2-4th 2011 Hangzhou, China
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Examination and evaluation of magnesite ore
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Experimental procedure
Analysis on magnesite
ore samplesChemical analysis
XRF
Microstructures analysis
SEM
Porosity Bulk densityASTM C 830
Thermal decomposition
TG-DTA
Mineralogical analysis
XRD
Visiualappearance
9**All this studies was done at laboratory scale.
APPEARANCE TO THE NAKED EYE
Cryptocrystalline1
Macrocrystalline From China
Cryptocrystalline2
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Cryptocrystalline 1
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Cryptocrystalline 2
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Macrocrystalline From China
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Results on Chemical Composition
Cryptocrystalline 1
Cryptocrystalline 2
Macrocrystalline From China
SiO2 0.22 0.14 0.41
CaO 0.73 0.62 0.65
Fe2O3 0.27 0.08 0.51
Al2O3 0.04 0.02 0.02
MgO 47.51 47.62 47.13
Na2O 0.125 0.098 0.154
MnO 0.002 0.047 0.013
LOI 51.11 51.38 51.13
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Physical Properties
Cryptocrystalline 1
Cryptocrystalline 2
Macrocrystalline From China
Porosity (%) 10.62 10.31 0.73
Bulk Density (gr/cm3) 2.62 2.62 2.98
Water Absorption (%) 4.06 3.96 0.34
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MICROSTRUCTURES
BY SEM EXAMINATION
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Cryptocrystalline 2
Cryptocrystalline 1
Macrocrystalline From China
100 X
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4400 micron
1000 X
Cryptocrystalline 2
Cryptocrystalline 1
Macrocrystalline From China 18
380 micron
5 000 X
Cryptocrystalline 2
Cryptocrystalline 1
Macrocrystalline From China 19
80 micron
10 000 X
Cryptocrystalline 2
Cryptocrystalline 1
Macrocrystalline From China 20
35 micron
20 000 X
Cryptocrystalline 2
Cryptocrystalline 1
Macrocrystalline From China 21
18 micron
30 000 X
Cryptocrystalline 2
Cryptocrystalline 1
Macrocrystalline From China 22
10 micron
Mineralogical Structures by XRD
Macrocrystalline From China
Cryptocrystalline 1
Cryptocrystalline 2
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Thermal Analysis Results TG-DTA
Macrocrystalline – 6780C
Cryptocrystalline 1- 6400C
Cryptocrystalline 2 – 6520C
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FIRING OF SAMPLES AND
RESULTS
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Experimental procedure
A- SINGLE FIRING
Calcinationat 7000C
Calcinationat 10000C
Firing at 17000C
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Calcination at 7000C
Cryptocrystalline2
Macrocrystalline From China
Cryptocrystalline1
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Calcination at 10000C
Cryptocrystalline2
Macrocrystalline From China
Cryptocrystalline1
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20 000 X
Cryptocrystalline 2
Cryptocrystalline 1
Macrocrystalline From China 29
18 micron
Firing at 17000C
Cryptocrystalline2
Macrocrystalline From China
Cryptocrystalline1
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BULK DENSITY VALUES after calcination (gr/cm3)
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POROSITY VALUES after calcination(%)
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BULK DENSITY VALUES after single firing (gr/cm3)
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Experimental procedure
A- DOUBLE FIRING
Calcinationat 10000C
Grinding
Briqueting Firing at 17000C
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FIRING TESTS RESULTS after double firing
Cryptocrystalline1
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2000 X
FIRING TESTS RESULTS after double firing
Cryptocrystalline2
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2000 X
FIRING TESTS RESULTS after double firing
Macrocrystalline From China
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2000 X
MgO 29.13
SiO2 40.03
CaO 30.85
Grain Boundry Phase
FIRING TESTS RESULTS after double firing
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CONCLUSION
1. Macrocrystalline magnesite ore structure has very low porosity amounting to 0,7% whereas cryptocrystalline has 10,3% and 10,6%. Accordingly, same tendency was observed in the bulk density results . Macrocrystalline magnesite structure has 2.98 gr/cm3 bulk density, but cryptocrystalline is lighter with a density of 2.62 gr/cm3.
2. According to TG-DTA analysis cryptocrystalline magnesite has lower decomposition temperature than macrocrystalline magnesite
3. The super fine crystal structure of the cryptocrystalline magnesite results in the formation of high levels of porosity during the calcination process. Most probably it will have higher SSA.
4. High bulk density values were determined after single firing of cryptocrystalline magnesite samples. In contrast,disintegration took place after single firing of macrocrystalline magnesite . Therefore, macrocrystalline magnesite is not suitable for use in the single firing DBM production process because of its very high crystal size. Higher DBM densities can be reached by using double firing production process for macrocrystalline magnesite .
5. Double firing test results showed that cryptocrystalline magnesite ore samples had higher bulk density values than macrocrystalline magnesite ores under similar firing conditions.
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Thanks for your kind attention
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