FORM 2
THE PATENT ACT 1970
(39 OF 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
1 TITLE OF THE INVENTION :
AN INJECTION LANCE FOR DE-SULPHURISATION OF HOT METAL BY INJECTING REAGENTS ALONGWITH CARRIER GAS AND A PROCESS THEREOF.
2 APPLICANT (S)
Name : JSW STEEL LIMITED.
Nationality : An Indian Company.
Address : Jindal Mansion, 5-A, Dr. G. Deshmukh Marg, Mumbai - 400 026,
State of Maharastra, India.
3 PREAMBLE TO THE DESCRIPTION
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention relates to an injection lance system for injecting reagents into ladle containing molten metal for removing Sulphur at hot metal de-sulphurisation station (HMDS) before charging into converter for final steel making. More particularly, the present invention is directed to providing an injection lance system with a curved port at the lance bottom where the port exit is at 45° from the axis adapted to imparting a combined rotational and translational flow profile to the carrier gas and reagent, by injecting them at an angle to the lance normal, thereby favouring increase in residence time of the injected reactants, reduction in mixing time of the injected reactants and consequent improvement in desulphurization efficiency.
BACKGROUND OF THE INVENTION
Hot metal or molten iron from iron making units such as blast furnace contains silicon and sulphur as primary impurities and varies significantly from unit to unit and ladle to ladle. These impurities need to be removed during the steel making process. In modern steel making process, hot metal from blast furnace is pre-treated for removing Sulphur at hot metal de-sulphurisation station (HMDS) before charging into converter for final steel making process where silicon is removed. De-Sulphurisation is done by injecting calcium carbide using a dipped lance (T - shaped or straight port) along with a carrier gas.- In this process, Sulphur in hot metal is brought down from the range of 0.06 - 0.08 wt % to 0.015 - 0.010 wt% in a treatment time of 20 - 25 mins. These processes help in maintaining consistent hot metal chemistry for charging in the LD converter.
In the existing lance designs (T - shaped or straight port), the particles are not completely dispersed into the ladles. For the efficiency of the De-sulphurisation process the particles should be dispersed in the ladle as widely as possible to increase the total interfacial area between the molten metal and particles. Mathematical and water modeling experiments show large dead zone in the ladles during processing with existing lance designs. This increases the reaction time and reduces the process efficiency.

There has been therefore a persistent need in de-sulphurisation of hot metal treatment to developing an appropriate system for mixing of reagents with hot metal so as to disperse the particle widely in ladle and enhance residence time of injected reactants in order to improve the de-sulphurisation efficiency favouring attaining desired consistent hot metal chemistry in less time. The present invention is directed to providing an improved lance system ensuring the above favourable conditions of hot metal treatment at hot metal de-sulphurisation station and eliminating the limitations of the conventional process.
OBJECTS OF THE INVENTION
The basic object of the present invention is thus directed to providing an injection lance for injecting reagents into ladle containing molten metal at hot metal de-sulphurisation station (HMDS) and a process for injection using said lance to reduce the de-Sulphurisation time or increase the process efficiency.
A further object of the present invention is directed to an injection lance for injecting reagents into ladle containing molten metal at hot metal de-sulphurisation station (HMDS) wherein curved port lance is provided to generate a more favorable flow profile for more uniform and thorough stirring or swirling type velocity profile in the ladle.
A still further object of the present invention is directed to an injection lance for injecting reagents into ladle containing molten metal at hot metal de-sulphurisation station (HMDS) wherein more uniform mixing of reagent with hot metal is achieved in the ladle thereby reducing dead volumes and turbulence in the ladle.
A still further object of the present invention is directed to an injection lance for injecting reagents into ladle containing molten metal at hot metal de-sulphurisation station (HMDS) wherein lance having a curved port at the bottom injects the reagents in direction tangential to the lance creating create stirring-type or swirling type velocity profile in the ladle.

A still further object of the present invention is directed to an injection lance for injecting reagents into ladle containing molten metal at hot metal de-sulphurisation station (HMDS) which injects the reagents to increase the dispersion of the particles and its residence time.
A still further object of the present invention is directed to an injection lance for injecting reagents into ladle containing molten metal at hot metal de-sulphurisation station (HMDS) which ensure increase in residence time of the injected reactants and reduction in mixing time of the injected reactants with hot metal resulting in improvement in desulphurization efficiency.
A still further object of the present invention is directed to an injection lance for injecting reagents into ladle containing molten metal at hot metal de-sulphurisation station (HMDS) which ensure improvement in reaction kinetics of reagents with hot metal, favouring reduction in reagent consumption.
SUMMARY OF THE INVENTION
The basic aspect of the present invention is directed to an injection lance having injection ports comprising:
a substantially straight longitudinally disposed flow path for said injection purposes in operative communication with radially disposed curved flow path connecting to exit port /ports adjacent the lower end said curved flow path for said exit adapted to inject in a direction tangential to the lance outer surface at said port exit.
A further aspect of the present invention is directed to an injection lance for de-sulphurisation of hot metal by injecting reagents along with carrier gas comprising:
a substantially straight longitudinally disposed flow path for said injecting reagents along with said carrier gas in operative communication with radially disposed curved flow path connecting to exit port/ports adjacent the lower end adapted to inject the reagents along with said carrier gas in a direction tangential to the lance outer surface at said port exit.

A still further aspect of the present invention is directed to said injection lance wherein the curved port exits are disposed at 45° from the axis to thereby provide for a uniform and stirring type or swirling type velocity profile of the injected subject. A still further aspect of the present invention is directed to said injection lance wherein said curved exit port /ports adjacent the lower end adapted to impart a combined rotational and translational flow to the lance normal.
A further aspect of the present invention is directed to an injection lance wherein said curved exit port comprise a pair of diametrically oppositely disposed tangential exit ports adjacent the lower end each operatively connected to said longitudinal flow path through radial curved flow paths.
Yet another aspect of the present invention is directed to a process for de-sulphurization of hot metal comprising the step of de-sulpurization by injecting reagents involving an injection lance as described above comprises:
dipping the said lance in the molten metal and injecting the calcium carbide reagent along with carrier gas though said curved radially disposed flow paths to exit port in said lance to thereby increase the interfacial area between the molten metal and the reagent particles.
A further aspect of the present invention is directed to said process wherein the injection of the said reagent particles through said curved flow path for tangential exit through the exit ports generates favorable flow profile in the ladle with better mixing and higher residence time.
A still further aspect of the present invention is directed to said process wherein the particles are injected into the lance with combined rotational and translational flow profile to the carrier gas and the reagent thereby leading to more uniform mixing in the ladle with reduced dead volumes and turbulence in the ladle during desulphurization of hot metal,
A still further aspect of the present invention is directed to said process wherein the particles are injected into the lance with more uniform and stirring -type or swirling

type velocity profile generated in said ladle with imporved reaction kinetics and reduction in reagent consumption,
The objects and advantages of the present invention are described in greater details with reference to the following accompanying non limiting illustrative drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1: shows the schematic layout of steel manufacturing unit wherein location of the hot metal de-sulphurisation station is shown in relation to the Blast Furnace or COREX plant for iron making to final steel converter and continuous caster.
Figure 2(a) &. 2(b): shows (a) the construction of the conventional T - shaped or straight port configuration of lance bottom and (b) proposed Curved port lance according to the present invention adapted for injecting the carrier gas and reagent at an angle to the lance normal.
Figure 3: shows the cross sectional view of the proposed curved port lance.
Figure 4: is the schematic view showing the orientation and dimensions of the curved port potion of the lance bottom according to the present invention.
Figure 5: is the schematic view of the layout of de-sulphurisation system equipped with the curved port lance according to the present invention.
Figure 6: is the graphical presentation of the improvement achieved in respect of de-sulphurisation efficiency and rate constant/min using curved port lance according to the present invention over the conventional T-shaped lance.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
The present invention is directed to providing an injection lance system for injecting reagents into ladle containing molten metal for removing Sulphur at hot metal de-

sulphurisation station (HMDS) involving a curved port at the lance bottom which injects the reagents in direction tangential to the lance thereby generating more uniform and stirring-type or swirling type velocity profile to increase the dispersion of the particles and its residence time and resultantly to reduce the de-Sulphurisation time or increase the process efficiency.
Reference is first invited to accompanying Figure 1 which shows the schematic layout of steel manufacturing unit wherein location of the hot metal de-sulphurisation station is shown in relation to modern steel making process, wherein hot metal from blast furnace/COREX is pre-treated for removing Sulphur at hot metal de-sulphurisation station (HMDS) before charging into converter for final steel making process where silicon is removed. De-Sulphurisation is conventionally done by injecting calcium carbide using a dipped lance (T - shaped or straight port) along with a carrier gas.
In the existing T - shaped or straight port lance configuration, the particles are not completely dispersed into the ladles. For improving efficiency of the De-sulphurisation process, the particles should be dispersed in the ladle as widely as possible to increase the total interfacial area between the molten metal and particles. There exist large dead zones in hot metal during processing with straight port lance which increased the reaction time and reduced the process efficiency.
In the present work, extensive studies have been conducted through physical and mathematical modeling approach for developing a lance design for injecting reagents into hot metal ladles with for improved process efficiency. Based on the results obtained through CFD simulations and water modeling, a new design of curved port lance has been proposed. Curved port lance is expected to generate a more favorable flow profile in the ladle. A more uniform and stirring-type or swirling type velocity profile can be generated in the ladle using curved lance ports.
Accompanying Figure 2(a) shows the construction of the conventional T - shaped or straight port configuration of lance bottom and Figure 2(b) shows Curved port lance configuration developed according to the present invention adapted for injecting the carrier gas and reagent at an angle to the lance normal. Accompanying

Figure 3 show the cross sectional view of the proposed curved port lance showing the nature of passages through the lance tube.
Accompanying Figure 4 specifically shows the schematic top view of orientation and dimensions of the curved port portion of the lance bottom according to the present invention. It may be clearly apparent from this figure that the curved lance port at lance bottom has a curved profile which ensure that the reagent particles along with carrier gas is injected in direction tangential to the lance. The Lance Exit Port Opening Diameter is maintained at 13 to 15mm and preferably 14 mm and the Radius of Curvature of curved port is 58 mm (i.e. Diameter : 116mm). Also the curved port at the lance bottom is selectively configured where the port exit is at 45° from the axis in order to have injection of particles in tangential direction thus favoring desired swirling velocity profile for uniform and faster mixing.
Accompanying Figure 5 illustrates schematically an embodiment of the de-sulphurisation unit equipped with the curved port lance system according to the present invention. It may be noted in this figure that calcium carbide particles are carried by nitrogen gas in a controlled manner through the lance having the curved port where the port exit is at 45° from the axis, placed through a dust collecting hood and dipped into the hot metal in ladle at the HMDS so that the particles are widely dispersed by injecting in a direction tangential to the lance and providing a swirling motion.
Thus according to the present invention, a swirling lance has been developed which ensure better mixing and higher residence time. The curved port lance according to the present invention imparts a combined rotational and translational flow profile to the carrier gas and reagent by injecting them at an angle to the lance normal. It leads to more uniform mixing in the ladle thereby reducing dead volumes and turbulence in the ladle during desulphurization of hot metal.
Accompanying Figure 6 show the graphical presentation of the improvement achieved in respect of de-sulphurisation efficiency and rate constant/min using curved port lance according to the present invention over the conventional T-shaped lance. It may be noted that the desulphurization efficiency has been improved to

75% by using the curved port lance according to the invention as against the conventional efficiency of 65% achieved using T-shaped lance. Also the rate constant per minute which indicates kinetics of de-suiphurisation process ts improved from 0.08 by conventional T-lance to 0.11 using the curved port lance according to the present invention.
It is thus possible by way of the present invention to providing a lance system for injecting reagents into ladie containing molten metal at hot metal de-sulphurisation station (HMDS) to reduce the de-Sulphurisation time or increase the process efficiency, involving a curved port configuration of the lance bottom whereby the carrier gas and reagent are injected at an angle to the lance normal, ensuring the following advantageous features in processing hot metal at HMDS:
(i) A more uniform and stirring-type or swirling type velocity profile generated in the ladle.
(ii) Increase in residence time of the injected reactants.
(iii) Reduction in mixing time of the injected reactants.
(iv)Improvement in desulphurization efficiency
(v) Improvement in reaction kinetics.
(vi)Reduction in reagent consumption.

We Claim:
1. An injection lance having injection ports comprising:
a substantially straight longitudinally disposed flow path for said injection purposes in operative communication with radially disposed curved flow path connecting to exit port /ports adjacent the lower end said curved flow path for said exit adapted to inject in a direction tangential to the lance outer surface at said port exit.
2. An injection lance for de-sulphurisation of hot metal by injecting reagents
along with carrier gas comprising:
a substantially straight longitudinally disposed flow path for said injecting reagents along with said carrier gas in operative communication with radially disposed curved flow path connecting to exit port /ports adjacent the lower end adapted to inject the reagents along with said carrier gas in a direction tangential to the lance outer surface at said port exit.
3. An injection lance as claimed in anyone of claims 1 or 2 wherein the curved port exits are disposed at 45° from the axis to thereby provide for a uniform and stirring type or swirling type velocity profile of the injected subject.
4. An injection lance as claimed in anyone of claims 1 to 3 wherein said curved exit port /ports adjacent the lower end adapted to impart a combined rotational and translational flow to the lance normal.
5. An injection lance as claimed in anyone of claims 1 to 3 wherein said curved exit port comprise a pair of diametrically oppositely disposed tangential exit ports adjacent the lower end each operatively connected to said longitudinal flow path through radial curved flow paths.
6. A process for de-sulphurization of hot metal comprising the step of de-sulphurization by injecting reagents involving an injection lance as claimed in anyone of claims 1 to 5 comprising:

dipping the said lance in the molten metal and injecting the calcium carbide reagent along with carrier gas though said curved radially disposed flow paths to exit port in said lance to thereby increase the interfacial area between the molten metal and the reagent particles.
7. A process as claimed in claim 6 wherein the injection of the said reagent particles through said curved flow path for tangential exit through the exit ports generate favorable flow profile in the ladle with better mixing and higher residence time.
8. A process as claimed in anyone of claims 6 or 7 wherein the particles are injected into the lance with combined rotational and translational flow profile to the carrier gas and the reagent thereby leading to more uniform mixing in the ladle with reduced dead volumes and turbulence in the ladle during desulphurization of hot metal.
9. A process as claimed in anyone of claims 6 or 7 wherein the particles are injected into the lance with more uniform and stirring -type or swirling type velocity profile generated in said ladle with improved reaction kinetics and reduction in reagent consumption.