Mdmw-iron30

Blowing

Blowing Pattern

Functions

•De-Siliconisation •De-Carburisation •De-Phosphorisation •Optimization of steel temperature

Reactions •

•

The hot metal charge is refined by rapid oxidation reactions on contact with the injected oxygen, under conditions far removed from thermodynamic equilibrium with the other elements present: C + ½ O2 → CO Other oxidation reactions occurring during refining include: Si + O2 → SiO2 2P + (5/2)O2 → P2O5

•

Mn + ½O2 → MnO

•

Fe + ½O2 → FeO

•

2Fe + (3/2)O2 → Fe2O3

•

These oxides combine with the other oxides charged (lime, dolomitic lime) to form a liquid slag which floats on the surface of the metal bath

• • •

Top Blowing

Bottom Blowing

Converter blowing

Metal

Slag

Gases

De-Siliconisation De-Carburisation De-Phosphorisation

End point control

Slag path

Tap to tap time • Scrap Charging

 5 mins

• Hot metal charging

 6 mins

• Oxygen Blowing

 17mins

• Turn down and sampling  6 mins • Tapping

 6 mins

• Deslagging

 3 mins

Total

• Inspection

---

45 mins

 2 mins

Tapping and Slag Control Dart

To limit High FeO BOF slag from entering into Steel Ladle High Aluminium Recovery Higher Ferro-alloy recovery Better steel Quality due to lesser inclusions

Mass and Heat balance Mass and heat balances are the basic tool for: • charge calculation • simulation of the refining path (evolution of steel composition and temperature during the oxygen blow) • adjustment of the composition of certain entities (slag, …) • adjustment of steel temperature • diagnostic to evaluate materials and heat losses

Mass and Heat balance

Consumption • Oxygen

60 – 65 Nm3/t

• Lime

70 – 75 kg/t

• Dolomite

30 – 35 kg/t

• Iron ore

12 -15 kg/t

• Scrap

10%

Commonly used terms • Re-blow • Slopping • Steel Yield

Vessel Temperatures

1650 o C

Converter Process Steps Tapping temp: 1600 - 1700 deg C. Tap to tap time: 45 mins

Lining protection techniques 1. Avoid the most aggressive slags 2. Protective slag coating 3. Local repairs Critical Areas Tap hole Tap Pad Trunnion Drive side Trunnion Non-Drive side Charge Pad

Slag Splashing Slag splashing is a process of coating of left over slag on the refractory lining of the vessel It cools, solidifies, and creates a solid layer

of

slag

that

serves

consumable refractory layer.

Initial Refractory Thickness

: 900 mm

as

a

Slag Mushrooming

To increase the life of bottom plugs

Selective Splashing

To splash the areas of localized erosion

Benchmarking Organization

Highest Heats Recorded

JSW Steel

13771

Bhilai Steel Plant

6200

Vizag Steel

4200

Durgapur Steel Plant

3438

Rourkela Steel Plant

3417

Bokaro Steel Ltd

2657

JFE Japan

8458

Bao Steel, China

9539

Whuang works, China

18114

Gas Cleaning

Steel Making at JSW

Plant Facility for 4 mt capacity S L A B S

HMDS-1 MIXER-1

LHF-2

HM FROM COREX

CONVERTER-1

CASTER-1

T O H S M

HMDS-2

CONVERTER-2

LHF-1

CASTER-2 RH-OB

MIXER-2

S L A B S E X P O R T

HMDS-3

CONVERTER-3

CAS-OB

CASTER-3