Study of Tundish Refractory and Slag Interaction

Presented by:Jitendra Salecha

Under the guidance of:Mr. R.K Adepu

Refractory Technology Group

Study of Tundish Refractory and Slag Interaction

Tundish Linings

Working lining

Back-up lining

Study of Tundish Refractory and Slag Interaction

Average sequence length in LD #1 =14 No. of Heats/Hrs in a month = 600 No. of tundishes used in a month =42 Changeover time for a tundish =1-1.5 hrsIf average sequence length is increased by 2 then: No. of tundishes required in a month =37 BENEFITS: Production will be increased by reducing

changeover time for tundish Cost of refractory will also be reduced

OBJECTIVES

To increase the sequence length of the tundish

To reduce the cost of the refractory per ton of steel

To suggest the best suitable refractory to be used as working lining in tundish in LD #1

Study of interaction between working lining and slag

Cup test By Contact angle measurement with different

working linings and different grade slags Study of wear mechanism

By XRD and SEM analysis of reacted working lining

Evaluation of DVM working lining By XRD and SEM

Addition in the refractory to improve the life Carbon fiber, paper fiber, alumina fiber,

mineral wool fiber etc

PLAN

CUP TEST

Refractory:Magnavibe TCO, TCH

Slag:HC, MC, LC (steel grade)

Furnace1350oC, for 8 hrs

XRD & SEM of reacted portion

XRD & SEM of Unreacted portion

Samples after firingMC Slag HC SlagLC Slag HC Slag

Magnavibe

TC

OM

agnavibe T

CH

•Physically, there is no substantial difference in penetration of different grade of steel slag as seen from above figures.

• But MC steel grade slag having higher % of MnO(viz. 13.35%) also has same penetration

CUP TEST

Refractory:Magnavibe TCO, TCH

Slag:HC, MC, LC (steel grade)

Furnace1350oC, for 8 hrs

XRD & SEM of reacted portion

XRD & SEM of Unreacted portion

XRD of pure vibro mass

Position [°2Theta]30 40 50 60 70 80

Counts

0

500

1000

1500

36 M1 UnreactedMagnesium Silicate 62,0 %Iron Diiron(III) Oxide 6,2 %Magnesium Oxide (1/1) 31,8 %

Selected Pattern: Magnetite 98-007-8202

Residue + Peak List

Accepted Patterns

As expected ….

The major phase found in pure vibro mass is Forsterite and Periclase. However, a small amount of magnetite is also present.

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Composition:

Magnesium silicate (Mg2SiO4) : 62.0 %

Periclase(MgO): 31.8%

Magnetite(Fe3O4) :6.2%

XRD of reacted vibro mass

Position [°2Theta]30 40 50 60 70 80

Counts

0

500

1000

36 H1 ReactedMagnesium Iron Silicate (1.86/0.14/1) 100,0 %

Selected Pattern: Magnetite 98-007-8202

Residue + Peak List

Accepted Patterns

36H1 Reacted

Position [°2Theta]30 40 50 60 70 80

Counts

0

1000

2000

3000

36 M1 ReactedMagnesium Iron Silicate (1.8/.2/1) 100,0 %

Selected Pattern: Magnetite low 98-001-7288

Residue + Peak List

Accepted Patterns

36L1 Reacted

Composition:

Magnesium Iron silicate(36H1) (Fe0.14Mg1.86SiO4): 100 %

Magnesium Iron silicate(36L1)

(Fe0.2Mg1.80SiO4): 100 %

Comment:

There was only one major phase found in reacted portion of the brick. From these XRD analysis it can be said that the slag is in glassy phase which presence cannot be seen in XRD

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CUP TEST

Refractory:Magnavibe TCO, TCH

Slag:HC, MC, LC (steel grade)

Furnace1350oC, for 8 hrs

XRD & SEM of reacted portion

XRD & SEM of Unreacted portion

SEM of pure vibro mass(2736)

MgO rich area

Forsterite rich area

Forsterite rich area

MgO rich areaCao,MgO,SiO2

rich area

Silica rich area

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SEM of Deskulled Sample(T-18)

CaO and FeO rich Area

Ca silicate rich area

MgO rich area

Iron rich area

Ca , Mg silicate rich area

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SEM of deskulled sample(T-10)

Al2O3 rich area

Ca,Mg silicate rich area

Iron rich area

MgO rich area Ca,Mg silicate rich area

Chromite rich area1 2 back

OBSERVATIONS

From XRD, it can be seen that there was only one major phase present in reacted portion that magnesium iron silicate.

From SEM, the infiltration of slag into refractory material was clearly visible.

Wettability Characteristics by Contact Angle Measurement

Experimental Set-Up

The sessile drop unit, schematic sketch

Picture

PROCEDURE

200

1100 1100

1250

0

200

400

600

800

1000

1200

1400

0 50 100 150 200 250 300

Time (min)

Te

mp

era

ture

(C

)

1100 C

1250 C

10 C/min

1 C/min

Substrate & Slag Heating schedule Live pictures

Substrate: Magnavibe TCO & TCHSlag: : LC, HC

Comparison of contact angle

0

20

40

60

80

100

120

140

160

180

200

1100 1120 1140 1160 1180 1200 1220 1240

37LC

37HC

36LC

36HC

36H3-HC

Con

tact

an

gle

Temperature

Contact Angle v/s Temperature

Observation of CA experiments The salient observations during CA Experiment:

There was no change in the shape of slag nobule till 1130C

After 1130C slag started softening and changed into a spherical shape and developed a specific contact angle with refractory substrate

This contact angle was constant over a range of temperature from 1130C to 1180C, during which complete softening took place

After 1180C the slag became more fluid and started absorbed into the substrate, by 1250 slag has been completely absorbed.

CONCLUSIONS From CUP Test, it can be concluded that there is no

substantial difference in penetration of slag into refractory material

From XRD and SEM, it can be observed that slag penetrated into refractory material. This shows interaction between working lining and slag.

From Contact Angle measurement, slag started melting from 1130oC.This gives indication of low melting phases present in Slag.

Owing to low melting temperature of slag, some additives (MgO and CaO) should be added to increase its melting point to enhance the life of tundish working lining

THANK YOU THANK YOU ! !

Back up slides

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COMPOSITION of HC and LC

%Fe %CaO %SiO2 %MgO %MnO %Al2O3 %TiO2 %Cr2O3

HC 2.38 14.1 51.25 10.99 7.06 11.69 0.78 0.47

LC 1 14.48 59.47 8.0 8.08 7.92 0.28 0.14

MC

1 15.81 54.37 8.18 13.35 8.20 0.30 0.16

Compositon of TCO and TCH

%Fe %MgO %SiO2 %CaO %Al2O3

TCO 4.34 64.14 28.56 0.55 0.14

TCH 4.28 63.36 29.22 0.52 0.12

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%Weight of pure vibro mass-1

O-K Mg-K Si-K Ca-K Fe-K

2736(3)_pt1 39.98 59.84 0.18

2736(3)_pt2 40.89 24.44 18.37 15.97 0.33

2736(3)_pt3 44.90 32.93 21.55 0.62

2736(3)_pt4 40.51 59.34 0.15

2736(3)_pt5 38.21 23.44 19.71 18.64

2736(3)_pt6 45.04 31.95 21.17 1.85

2736(3)_pt7 42.24 18.39 19.88 19.49

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%Weight of pure vibro mass-2 O-K Na-K Mg-K Al-K Si-K S-K Ca-K Ti-K Fe-K

2736(2)_pt1

40.20 7.40 18.81 33.59

2736(2)_pt2

35.05 7.84 19.96 37.15

2736(2)_pt3

40.99 57.64 0.61 0.35 0.41

2736(2)_pt4

40.53 58.83 0.15 0.08 0.40

2736(2)_pt5

43.89 28.59 20.73 6.80

2736(2)_pt6

48.10 5.71 1.98 0.69 37.03 0.20 5.65 0.63

2736(2)_pt7

45.49 28.05 19.93 6.54

2736(2)_pt8

44.01 28.77 20.88 6.33

2736(2)_pt9

39.94 59.33 0.14 0.59

2736(2)_pt10-

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%Molecular weight in T-18

Mgo Al2O3 SiO2 CaO TiO2 MnO FeO

Pt_1 5.38 2.20 2.81 29.30 4.48 3.84 52.00

Pt_2 16.32 - 38.48 20.96 - 16.11 8.12

Pt_3 - 3.54 47.41 34.06 7.68 5.59 1.71

Pt_4 100

Pt_5 100

Pt_6 27.24 - 37.36 28.60 0.77 6.04 -

%Molecular weight in T-10-1

MgO Al2O3 CaO FeO SiO2 MnO K2O Fe

Pt_1 14.41 76.92

- 2.80 - 5.86 - -

Pt_2 18.39 - 38.55

3.95 31.04

7.28 0.79 -

Pt_3 - - - - - - - 100

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%Molecular weight in T-10-2

MgO Al2O3 CaO FeO SiO2 MnO TiO2 Cr2O3

Pt_1 87.10 7.15 5.75

Pt_2 25.47 34.34 1.70 34.12 4.37

Pt_3 24.66 10.73 2.98 0.98 60.64

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