3. Injection methods effectively reduce sulphur
content.
In this method, a strong desulphurizing
reagent in the form of fine powder is injected
(through a lance) in the refined steel bath
along with an inert gas (Argon) as carrier.
Injection reagent may be Metallic like Calcium,
Magnesium or the other form like Lime,
Calcium carbide, Calcium silicide and
Magnesium coke.
INJECTION METALLURGYINJECTION METALLURGY
5. Ladle Capacity:
• 40 T – 300 T
Cycle time:
• About 20-50 minutes depending upon the
aim and final chemistry.
Injection rate:
• The injection rate varies between 2 -4 kg/ton
of melt
INJECTION METALLURGYINJECTION METALLURGY
6. A ladle with deoxidized (killed) molten steel is
transported to the injection stand and placed
under a cover, through which the injection
lance is lowered and immersed into the melt.
Desulfurization agents are injected in argon
stream. Argon bubbles produce stirring of
the molten steel and the slag promotes
desulfurization.
Stirring also provides thermal and chemical
homogenization of the melt.
INJECTION METALLURGYINJECTION METALLURGY
7. The more interfacial area of contact of particles
with the steel bath leads to very efficient
interaction of the reagent with the bath.
The treated steel is covered by a layer of
desulfurizing slag having high solubility of
sulfur and capable to absorb sulfides formed
as a result of active agents injection.
Desulphurization takes place in a short time of
about 8 – 10 minutes and the bath looses
30 – 35o
C temperature.
INJECTION METALLURGYINJECTION METALLURGY
8. When the desulphurizing agents are injected
into molten steel in form of a cored wire
containing powder of desulphurizing agent
stirring by argon bubbling from the porous plug
mounted in the ladle bottom is used.
Fumes formed during the operation are
extracted through the cover.
TN (Thyssen Niederrhein) injection system is
more popular.
INJECTION METALLURGYINJECTION METALLURGY
9. Benefits of Ladle desulphurization by injection
of active agents:
• Sulphur removal (desulfurization);
• Temperature and chemical homogenizing;
• Non-metallic inclusions removal.
• The effective desulphurization allows to
achieve ultra-low concentrations of sulfur in
steel (0.0002%) and decreases sulphide
inclusions, thereby improves Toughness and
Elongation of the Steel.
INJECTION METALLURGYINJECTION METALLURGY
11. Molten steel in a ladle is treated (refined) in a
device called Ladle Furnace (LF).
It is capable of carrying out Vacuum treatment,
slag refining, Injection etc,
Primary functions of LF are:
• Reheating of liquid steel through electric
power conducted by graphite electrodes.
• Homogenization of steel temperature and
chemistry through inert gas stirring
Ladle Furnace (LF)Ladle Furnace (LF)
12. Primary functions of LF are:
• Formation of a slag layer that
• Protects refractory from arc damage,
• Concentrates and transfers heat to the
liquid steel,
• Trap inclusions and metal oxides,
• Provide the means for desulphurization by
synthetic slag or by injection metallurgy.
Ladle Furnace (LF)Ladle Furnace (LF)
13. Primary functions of LF are:
• The slag is primarily modified by the addition
of CaO or CaF2.
• The slag is basic and its typical composition
range is CaO: 50-56%, MgO: 7-9%,
SiO2: 6-12%, Al2O3: 20-25%.
• LF has the ability to make alloying additions.
• LF Provide a means for dephosphorization.
Ladle Furnace (LF)Ladle Furnace (LF)
14. Capacity:
• 10 T - 25 T - DC Ladle Furnace
• 15 T - 150 T - AC Ladle Furnace
Cycle time:
• About 40-50minutes depending upon the aim
and final chemistry and desired temperature
rise.
Ladle Furnace (LF)Ladle Furnace (LF)
16. The ladle is transferred to the Ladle Furnace
stand where it is placed under a cover
equipped with three graphite electrodes
connected to a three-phase arc transformer.
The ladle bottom has a porous refractory plug,
which is connected to the argon supply pipe at
the Ladle Furnace stand.
The LF stand is also equipped with an addition
hopper mounted on the cover and a lance for
injection of desulfurizing agents.
Ladle Furnace (LF)Ladle Furnace (LF)
17.
18. During the treatment process argon is blown
through the bottom plug for continuous metal
stirring.
Molten steel treated in Ladle Furnace is
covered by a layer of desulphurizing slag.
When the graphite electrodes are submerged
into the ladle, the slag protects the ladle lining
from overheating produced by the electric arcs.
The arcs are capable to heat the steel at the
rate about 3°C/min.
Ladle Furnace (LF)Ladle Furnace (LF)
19. Stirring results in,
• distribution of heat produced by the arcs,
• chemical homogenization
• desulfurization of the steel by the slag.
Fumes formed during the operation are
extracted through the cover.
Alloying elements may be added through the
addition hopper.
Besides refining operations Ladle Furnace (LF)
may serve as a buffer station before
Continuous casting.
Ladle Furnace (LF)Ladle Furnace (LF)
20. Advantages of Ladle Furnace (LF):
• Increase productivity
• Decreasing refining time of EAF
• Decreasing tapping temperature at EAF
• Precise temperature control
• Improved inclusions control and cleanliness
of the steel.
Ladle Furnace (LF)Ladle Furnace (LF)
21. Benefits of Ladle Furnace (LF):
• Sulfur removal (desulfurization);
• Controllable reheating by electric power;
• Alloying;
• Temperature and chemical homogenizing;
• Non-metallic inclusions removal (Oxygent
content upto 30ppm can be attained).
Ladle Furnace (LF)Ladle Furnace (LF)
22. Introduction to Modern Steel Making
by Dr.R H Tupkary
Iron Making and Steel Making
by Ahindra Ghosh, Amit Chatterjee
Lecture 23 : Injection Ladle Metallurgy _
Class notes IIT Madras.
Ladle Refining_ www.substech.com
REFERENCES :REFERENCES :