Brasil Prezentacja121009 d
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Transcript of Brasil Prezentacja121009 d
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DOLOMITE CLINKER PRODUCTION
FOR MODERN STEELMAKING
Czesaw Golawski,
Michal L.Sulkowski,
PMO KOMEX Sp.z o.o., Krakow, Poland(A 100% Subsidiary of ArcelorMittal Poland S.A)
11th BIENNAL WORLDWIDE CONGRESS
13-16 October, 2009
Pestana Bahia Hotel-Salvator-Brasil
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CaCO3.MgCO3 CaCO3 MgO CaO.MgO
dolomite 650oC 850oC dolime
CaO.MgO (dv=1,4 g/cm3) CaO.MgO (dv=3,15 g/cm3)
dolime sintering in rotary kiln dead burned dolomite
Chemical Reaction
of
Raw Dolomite to Dolomite Clinker
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Rotary Kiln for Dolomite Clinker Production
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Binding System Development
continuous improving of the quality of polymer binder for ecological low PAHand optimization of hot mass preparation
working out a conditioning at the temperature 300oC resulted in improvingthe working conditions and facilitated the heating up process after lining the
products in vessel.
Increasing of Hydration Resistance
through improving the degree of clinker sintering, tempering of productsafter moulding and packing together with protecting the products withthermo-shrinkable foil,
working out technological alternatives of combined dolomite-magnesiaproducts along with replacing the fine-grained fast hydrating dolomiteclinker fraction with magnesia clinker
working out new technological solutions in the semi-technical trials of two-
step sintering dolomite clinker.
Composition Development
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Raw Material
Triassic dolomites DK, DWH and dewon dolomite from Silesia-
Krakow region of Siewierz deposits are used for the production
of dolomite clinker.
Dolomite
stone SiO2 Al2O3 Fe2O3 MgO Porosity %
DWH-Triass 0,9 0,36 2,07 18,63 7,84
DK-Triass 0,37 0,26 1,02 19,38 7,76
Dewon
dolomite0,16-0,6 0,17-0,54 0,1-0,34 19,63-22,19 1,4-3,2
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Higher mass loss (48,37%
at 1000oC of dolomite DK
quality, is a consequence
of higher chemical purity
Dolomite DWH
Dolomite DK
Thermal Analysis
of Raw Dolomite
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Dolomite Clinker from Rotary Kiln
MictrostructureMixed crystal, magn. 2500x Closed pores magn. 600x
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Dolomite Clinker Application After cooling, the dolomite clinker is crushed in
cone crushers to save undamaged glazed aggregatesurface directly used in moulding composition.
Melted polymer binder enables the moulding ofproducts, but also to protect the dolomite grainsagainst rapid hydration and to retain the bindingcarbon residue after coking which reduces thecorrosion process by metallurgical slags.
Main application of dolomite products is steel ladleslining where the products made by PMO Komexhave a very good performance.
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Influence ofBurner Type on the Quality
of Dolomite Clinker.
Type of burner Oil burner Gas burner
Total porosity % 3.30 1,4 1.350,9
Bulk density g/cm3 3.175 0,4 3.23 0,2
In June 2008 the burner fired by coal pitch in the high-
temperature rotary kiln was replaced with a burner fired with
gas. Although the major purpose of the project was to reduce
the energy consumption, after a short period of commissioning
of the kiln a significant improvement of clinker quality was also
achieved and mostly the homogeneity was increased.
Change of temperature profile in zones improved
homogenisation of input before sintering.
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Trial of Two-steps Dolomite Clinker Production
Type of dolomite DK DWH
Total porosity % 57.5 58.3
Bulk density g/cm3
1.47 1.44
Specific surface area
BET, m2/g
1.33 1.51
The decarbonization of dolomite was carried out at the temperature of 1100oC.
Decarbonates have a high total porosity and a low bulk density but crystal size ofDK> DWH. Total porosity of raw dolomites of DK and DWH is up to 10% of
decarbonization generate very big increase of porosity.
Tests of densification of the decarbonate of DK quality v. pressure of moulding
carried out in the range 120 MPa to 320 MPa. Increase of moulding pressure was
linear and resulted in total porosity change from 45,9% to 35,9%.
Properties of dolomite after decarbonization
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Type of dololmite Rotary kiln one
step product
DK DWH
Total porosity % 2.2 1.2 2.2
Bulk density g/cm3
3.2009 3.3433 3.2485
Density g/cm3
/He/ 3.2703 3.3425 3.3226
Properties of dolomite clinkers
Briquettes moulded with high pressure from decarbonates were burnt at themaximum temperature of 1600oC
Clinkers obtained from DK and DWH qualities, (X-Ray) the main phases are
crystalline calcium oxide, periclase, small quantities of calcium hydroxide
and calcium aluminates: C3A and C12A7.
In the second sintering step coarse-crystalline DK quality dolomite (lower
content of iron compounds) does not sinter worse than dolomite DWH
(higher iron content) but even better.
Trial of Two-steps Dolomite Clinker Production
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Decarbonized dolomite DK Second step sintered dolomite DK
The pores are mainly of the closed type, which have a positive effecton the hydration resistance and also the reduced infiltration of slag
was observed
Microstructure of the Two-Step Sintering Trials
Investigation in scanning microscope NOVA NANOSEM 200 (FEI), 2500x
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Two Step Sintering of Dewon Dolomite
Dr in. Zygmunt Piotrowski research on two step sintering of Siewierz depositDewon dolomite calcined samples, ground and pressed sample for sintering
Type of dolomite
Sintering effect
DK
TRIAScrystal size 100-150 um
% of initial surface
SIEWIERZ
DEWONcrystal size 750-900 um
% of initial surface
two steps 37,3 35,6
one step 53,3 81,2
10 Tons of Dewon Dolomite stone calcined in 1100o
C, ground to 0,6 mmbriqueting without binder into 50x35mm with pressure 520 MPa to prosity 5,8 %
density 2,98 g/cm3. Briquets fired in 1700 oC in rotary kiln.
Clinker properties: porosity 2,4-2,7 %, density 3,2-3,5 g/cm3. Applied for pitch
bonded bricks- wear rate was 30-35% better than fine crystals triasic dolomite.
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Dolomite refractories of 40% MgO are currently used in linings of steel ladles
their performance in a number of steel plants is very good:
Grade 42D7 42D9 42D11 4RD9
CCS
MPa40 30 25 50
Porosity
%4 3 2 3
Densityg/cm3
2,95 2,95 2,95 2,95
Carbon
content %7 9 11 9
Binder type carbon polymer resin
The carbon additive (7-11%) reduces the iron oxides lowering the chemical
corrosion and by its low wetability limits metal penetration into the products
Further improvement of the quality of dolomite clinker could be expected
when introducing the two-step method of sintering. That, would require
substantial investment expenditure in the form of devices for
decarbonization, making pellets and the RCE shaft kiln.
The trials of fusing dolomite have also brought interesting results.
Properties of the Dolomite Refractories
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Steel Ladle Dolomite Lining
50D11
60D11
40D
40D7MSP5-DK
LCC
Bauxite-Spinel
40D11
Manesite
Ramming Mix
M90, HA55,MCr90
MCC, Bauxite-Corundum
M90, HA55, MCr90LCC
Bauxite-Spinel
DolomiteRamming
Mix
M90, HA55,
MCr90
M90, HA55,
MCr90
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Conclusion - Dolomite v. Magnesia
1. Increased of costs of purchase of good quality
magnesia clinker.
2. Dolomite raw material is more available andcheaper than the magnesia raw material.
3. In many applications dolomite products cansuccessfully compete with magnesia productsfor higher resistance in special metallurgical
treatment the silica-rich slags application.Free CaO reacts with low-basic slag, in fusedslag calcium silicates are formed on bricksurface, thus reducing the corrosion process
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Conclusion - Dolomite v. Magnesia
4. Combination CaO-C is more stable above1600C comparing to MgO-C combination,(carbothermical reaction ).
5. The production of dolomite products isimportant in Poland where there is ashortage of good quality raw material for theproduction of magnesia products, and on theother hand there are large deposits of goodquality dolomite and so there are theconditions to produce this type of refractoryproducts.
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THANK YOUFOR YOUR ATTENTION