Refractory in steel ladle application

1. Refractory in steel ladle application
DEPARTMENT OF CERAMIC ENGINEERING
NATIONAL INSTITUTE OF TECHNOLOGY
ROURKELA
Seminar and Technical Writing (Autumn 2021)
Course Instructor: Prof. Debasish Sarkar
Presented by
Satyam kumar
Roll no. 519CR1004

2. Content
Introduction
Function of Steel ladle
Classification of steel ladle
Important ladle Refractories
Requirement of refractory in steel ladle lining
summary

3. Introduction
 Ladles in steel plant are generally used to transfer
molten steel from the melting unit to the casting
unit .
 It is a basic tool extensively used in the continuous
casting operation and it has capability to resist
heat.
 Structure of ladle is made multi-layered strong
and heat insulated. Inner face of ladle is made up
of special kinds of refractory bricks. These brick
can withstand with high temperature and also heat
resistant allowing them to hold molten metal.
Figure 1.Image source: http://www.wonlf.com/Products1?product_id=5

4. Function of ladle
 Transportation of molten steel tapped from basic oxygen furnace or an electric arc
furnace between 1500-1700 ℃ to the continuous casting or ingot casting process.
 To improve the quality of molten steel acts as a secondary refining reactor.
 Supply of molten steel to a tundish or an ingot mould, with the flow rate controlled in
a variable manner.

5. Classification of steel ladle
1.Casting ladle: It is used to pour hot molten metal for casting.
Figure 2. Casting ladle [1]
2 Transfer Ladle:
This type of ladle is used typically to transfer hot
liquid molten metal from melting unit to casting
unit or an auto pouring unit like in steel mills, the
ladle can be transported on wheels, in a specially
designed ladle transfer car, or hung from an
overhead crane and tilted using another overhead
lifting mechanism.
Figure 3. Transfer ladle [1]

6. Treatment Ladle
A ladle that is used to change some aspect of the molten metal by a process that takes place within the ladle.
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Figure 4. Treatment ladle [1]

7. Important ladle refractories
Magnesia refractories:
 Major source ; brine and sea water magnesia
Advantages :
 Chemical stability very high
 High strength
 Good corrosion resistance
 In steel ladle lining less pure magnesia with 87% MgO ,2 wt.% CaO and 6 wt.% SiO2 is used.

8. Continue..
Dolomite refractories :
 High temperature firing can transform natural double carbonate dolomite (CaCO3
MgCO3) into refractory dolomite (CaO+MgO).
 Dolomite with a high purity content of more than 97 percent CaO + MgO and 0.5 – 3 %
impurities is known as high purity dolomite.
 Interaction with steel or steelmaking slags, dolomite exhibits exceptional refractoriness
and is very thermodynamically stable
 It is used in steel ladle application with pitch bonded doloma with 60% CaO and 40 %
MgO content.
 These kind of refractories with graphite composition and resin bonding is also used in
wear areas in steel ladle application such as impact pad, slag lines etc

9. Zircon/Zirconia –Excellent refractory material with very high specific gravity (4.5 - 4.6 gm/cm3 )
Advantages:
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 High melting point
 chemical inertness
 Excellent mechanical strength and
 High thermal stability
 Excellent thermal spalling resistance
Application:- steel ladle as a nozzle for pouring molten steel
Zirconia Refractory:
Natural source- Badeleyite
Application: Slide gate plates in steel ladle Application

10. Carbon Group :
 Carbon is a conductive in nature that makes it different from any other group of
refractories
 Bulk density 1.5-1.8 g/cm3 , Apparent porosity =12-25%
Advantages :
 High thermal stability
 Poor wettability
 High thermal conductivity
 Low thermal expansion coefficients
 Excellent thermal spalling resistance
It is applicable where the presence of oxygen is minimum otherwise oxidation will take place
and it will support the burning of carbon
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11. Spinel Refractories :
 Magnesium aluminate spinel exhibits unique combination of properties such as high
melting point, excellent resistance to chemical attack, High strength at elevated
temperature, excellent thermal shock resistance etc. makes a special class of refractory
material
 General formula of this group is AB2O4
 Stoichiometric spinel contains 71.67 wt.% Al2O3 and 28.33 wt.% MgO and has a
molar ratio of 1 MgO to 1 Al2O3
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12. Crystal structure of spinel:
Figure 5 cubic crystal structure of spinel [9]

13. Thermophysical properties of Spinel, Alumina and Magnesium oxide
Properties Spinel Magnesium oxide Alumina
Melting point (℃) 2135 2852 2054
Thermal expansion (10-6 /℃)
100 ℃ 5.6 10-12 5.6
500 ℃ 7.6 11-13 7.3-8.0
1000 ℃ 8.4 13-15 8.7-9.3
1500 ℃ 10.2 15-19 9.3-9.9
Thermal conductivity (W/mK)
25 15 40 38
100 13 38 36
500 8 16 11
1000 5 7 7
Density ( gm/cm3 ) 3.58 3.65 3.99
Table 1 [9-11]:

14. Spinel formation mechanism: Solid state reaction route
Al2O3
4MgO
-3Mg2+
+2Al+3
MgAl2O4
MgAl2O4
MgO
4Al2O3
-2Al+3
+3Mg2+
3MgAl2O4
3Mg2+
2Al+3
Figure 6. Spinel formation through counter diffusion mechanism [12]
Al2O3

15. Requirements of refractory in steel ladle lining :
 Very high thermal stability
 High corrosion and slag penetration resistance
 High erosion resistance
 Very high thermal shock resistance

16. Steel ladle lining Zone
 Steel ladle is basically divided into various zone like slag line, sidewall, tuyere and impact
pad
Slag zone:
 In slag zone Magnesia carbon brick is employed .
Advantages of Magnesia carbon Brick in slag region:
 Very high refractoriness so that no low melting eutectic temperature occurs between
magnesium oxide and carbon.
 Graphite is the source of carbon which has very low thermal expansion coefficient value.
 Thermal spalling resistance of magnesia carbon refractories is very high.
 High thermal conductivity.
 Very high corrosion resistance.

17. Flow diagram of magnesia carbon refractory is shown in Figure below
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Figure 7. Flow Diagram of magnesia carbon Refractory [4]

18. Continue..
Side wall
 In side wall portion of the ladle refractory based castables are used after
1990’s [13] for production of high purity steel and ultralow carbon steel.
The benefit of this type of system it increases the durability of the
product. The densification effect of magnesia based castable is very
good and it also helps in expansion.
Bottom portion
 Monolithic based refractory castable alumina spinel is used in the bottom
portion of the ladle lining. . Lining life is increased considerably with
superior corrosion resistant and thermal shock resistance compared to
conventional brick used in ladle lining.

19. Advantages of refractory base castable bottom portion of ladle:
 High mechanical strength
 High thermal spalling resistance
 High corrosion resistance
 High erosion resistance
 High volumetric stability
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20. Summary:
Steel ladle plays an important role in steel making process. Production of steel is
directly dependent on the performance of the ladle. Understanding the concept of
ladle lining is very much important because it is made up with different kinds of
refractory material and their requirement is different in different zone, no single
material can full fill all these requirements .Thus a comprehensive study has been
done with different kind of refractory material applied in steel ladle lining
starting from the slag line to bottom portion of the ladle

21. Refrences:
[1] Mahamure, N. (2013). Review of ladle furnace. Proceedings of the 7th ICECSME-2013, Pune, India, 65-70.
[2] Nandi, D. N. (1987). Handbook on refractories. Tata McGraw-Hill Publishing Company Limited.
[3] Matsui, T., & Taki, N. (2020). Refractory technology of ladle. Nippon Steel Technical Report, (415), 52-55.
[4] Sarkar, R. (2016). Refractory technology: Fundamentals and applications. CRC Press.
[5] Kathait, D. S. (2016). Ladle furnace refractory lining: A review. Department of Mechanical Engineering, SOET, HNB Garhwal University, Srinagar (Garhwal), Uttarakhand
(India).
[6] Sarkar, R. (2010). Refractory applications of magnesium aluminate spinel. Interceram: Refractories Manual, 1, 11-14.
[7] Braulio, M. A. L., Rigaud, M., Buhr, A., Parr, C., & Pandolfelli, V. C. (2011). Spinel-containing alumina-based refractory castables. Ceramics International, 37(6), 1705-
1724.
[8] Bradt, R. C. (2004). Mg-Al SPINEL: IS IT THE MULLITE OF THE 21 ST CENTURY?. Refractories Applications & News, 9(4), 8-10.
[9] Kingery, W. D., Bowen, H. K., & Uhlmann, D. R. (1976). Introduction to ceramics (Vol. 17). John wiley & sons.
[10] Rethwisch, W. D. (2010). Callister, Materials Science and Engineering.
[11] Rigaud, M. A., & Landy, R. A. (1996). Pneumatic Steelmaking.: Refractories. Iron and Steel Society.
[12] Nakagawa, Z., Enomoto, N., I-S, Y., & Asano, K. (1995, November). Effect of corundum/periclase sizes on expansion behaviour during synthesis of spinel.
In UNITECR'95 Congress. Proc. Unified Int. Tech. Conf. on Refractories (Vol. 4).
[13] Schnabel, M., Buhr, A., Exenberger, R., & Rampitsch, C. (2010). SPINEL: IN-SITU VERSUS PREFORMED- CLEARING THE MYTH. Refractory World forum, 2(2),
87-93.