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8/7/2019 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

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