Title of Invention	AN IMPROVED METHOD OF PRODUCING LIQUID STEEL IN A BASIC OXYGEN FURNACE
Abstract	This invention relates to an improved method of producing liquid steel in a basic oxygen furnace, the method comprising the steps of providing small size limestone chips and causing the chips to undergo crushing and grinding operation to produce pulvers of desired fineness; the pulvers being fluidized with an inert gas carrier, providing atleast one bottom tuyere (BT) having means (1) for bottom purging of pulverized limestone into the furnace; injecting a predetermined quantity of the fluidized pulvers via the purging means (1) of at least one bottom tuyere (BT) such that the surface area for reaction between the solid flux and the liquid slag increases with the change in particle size injected through bottom charging, leading to substantial increase in the overall reaction rate; and simultaneously adding from the storage hoppers disposed on the top of the furnace, a reduced quantity of calcined lime to form slag for improved refining, the reduction being equivalent to said predetermined quantity of pulverized limestone charged via bottom injection.

Title of Invention

AN IMPROVED METHOD OF PRODUCING LIQUID STEEL IN A BASIC OXYGEN FURNACE

Abstract

This invention relates to an improved method of producing liquid steel in a basic oxygen furnace, the method comprising the steps of providing small size limestone chips and causing the chips to undergo crushing and grinding operation to produce pulvers of desired fineness; the pulvers being fluidized with an inert gas carrier, providing atleast one bottom tuyere (BT) having means (1) for bottom purging of pulverized limestone into the furnace; injecting a predetermined quantity of the fluidized pulvers via the purging means (1) of at least one bottom tuyere (BT) such that the surface area for reaction between the solid flux and the liquid slag increases with the change in particle size injected through bottom charging, leading to substantial increase in the overall reaction rate; and simultaneously adding from the storage hoppers disposed on the top of the furnace, a reduced quantity of calcined lime to form slag for improved refining, the reduction being equivalent to said predetermined quantity of pulverized limestone charged via bottom injection.

Full Text	FIELD OF INVENTION This invention relates to a method of producing liquid steel by adapting the process of basic oxygen steelmaking, using hot metal as the primary raw material. In particular, the invention relates to an improved method of producing liquid steel by adapting bottom-injection technology with partial replacement of calcined lime with pulverized limestone. The invention further relates to a device for implementing the improved method in a basic oxygen furnace. BACKGROUND OF THE INVENTION Different fluxes are generally added during steelmaking in the basic oxygen furnace for the purpose of better slag formation and improved refining. The purpose of adding flux to the BOF is to combine with the oxidation products (SiO2, P2O5, etc.) and form a fluid slag. The fluxes added to BOF during steelmaking consist typically of calcined lime, limestone and dolomite. In addition, some steel plants add other slag formers like bauxite and/or manganese oxide. All such additive materials are added dry in the form of sized lumps or briquettes. The fluxes are kept in storage hoppers above the level of the furnace and each hopper is equipped with a discharge valve at the bottom, along with conveying system for transporting the flux into the BOF. The discharge valve is opened whenever necessary and the flux in the hopper, in required quantity, is charged into the furnace. The lumps / briquettes of flux react with the oxidation products and start dissolving in the slag inside the BOF. However, due to the bulky size, the rate of reaction and dissolution is slow. As a result, the added fluxes take considerable time before getting fully dissolved/reacted. Particles of undissoved lime are often observed floating on liquid slag at the end of steelmaking in BOF. Charging of bulk solids through the top of the furnace is the most conventional and widely used technique for making such additions. Blowing of oxygen may or may not be in progress during such addition. However, portions of the added solids form fines during addition and those are lost in the form of and removed by the exhaust system. This causes wastage of valuable flux materials. The fluxes generally used in the furnace as described hereinabove, constitute: a) Calcined lime (CaO), Calcined lime is required during steelmaking to impart the requisite basicity in the steelmaking slag, thus making the slag fluid and reactive. CaO combines with P2O5 and helps to stabilise the phosphorus content in the slag, thus enabling production of low phosphorus steel. CaO also helps to remove part of the sulphur content from the bath, though the intensity of desulphurisation is less than that of dephosphorisation. Burnt dolomite (CaO-MgO): The main purpose of adding dolomite during steelmaking is to reduce the rate of dissolution of the MgO-based refractory lining into steelmakinq slag. In addition, MgO also helps to reduce the viscosity of the slag, thus enhancing the kinetics of the refining reactions. Synthetic slag (CaO-SiO2-FeOx): Synthetic slag allows rapid formation of liquid slag and enhance the rate of dissolution of calcined lime. It also adds to the overall slag volume, thus favouring the removal of impurities like phosphorus and sulphur. Inert gas is also injected into the BOF during steelmaking for enhancing the kinetics of chemical reactions and reducing chemical and thermal inhomogeneity. Several designs are possible for a tuyere through which the gas is injected. Refractory block with a single round hole Porous plug (sponge-like structure of refractory block) Refractory block with vertical slits Refractory block with multiple numbers of small round channels The basic problems with the prior art processes of steel making in the basic oxygen furnace can be summarised as under: (i) Calcined lime is highly friable and large quantity of CaO dust is generated during transportation of calcined lime through the material handling devices. This dust is carried along with the exhaust gases and the CaO contained in it is thus lost from the basic oxygen furnace. (ii) In addition, calcined lime is extremely hygroscopic and tends to absorb moisture from the atmosphere during its storage and handling. Hydration of the calcined lime, i.e. reaction with moisture from the atmosphere, causes disintegration of lime briquettes (generation of more fines) and makes the powder stick to the conveying and charging equipments. This creates difficulty in maintenance of the plant machinery. (iii) Last, but not the least, problems comes from the highly corrosive nature of CaO. Anv contact with human body creates severe irritation and burn, and its handling is therefore hazardous for the associated workforce. Addition of flux materials in the form of fines / small granules would appear to be a ready solution for enabling rapid dissolution in slag. However, exhaust gases (also called off-gas) escape at very high flow rate through the top portion (mouth) of the BOF and that would cause bulk of the fines to get carried out into the exhaust stream. Therefore, it is not possible to add fines of flux materials through the top of the BOF. Further, the choice of a specific design in a particular steel plant depends on relative cost and the intensity of purging desired. An arrangement of storage hoppers (H1,H2) for top charging of flux materials and bottom tuyeres (Bl) for injection of inert gas according to the prior art is shown in Fig. 3. The flow rate through the bottom tuyeres is typically within 1 - 2% of the oxygen flow through the top lance. OBJECTS OF THE INVENTION It is therefore an object of the present invention propose an improved method of producing liquid steel in a basic oxygen furnace which eliminates the disadvantages of the prior art. Another object of the invention is to propose an improved method of producing liquid steel in a basic oxygen furnace which is economically viable. A further object of the invention is to propose an improved method of producing liquid steel in a basic oxygen furnace which prevents any deterioration of the quality and cleanliness of liquid steel produced by the method. A still further object of the invention is to propose a device for injecting pulverized limestone from the bottom of the basic oxygen furnace in order to partially replace top-charging of calcined lime. SUMMARY OF THE INVENTION Accordingly there is provided an improved method of producing liquid steel in a basic oxygen furnace, the method comprising the steps of; providing small size limestone chips and causing the chips to undergo crushing and grinding operation to produce pulvers of fineness less than 0.5mm; the pulvers being fluidized with an inert gas carrier, providing atleast one bottom tuyere (BT) having means for bottom injecting pulverized limestone into the furnace; injecting a predetermined quantity of the fluidized pulvers via the purging means of at least one bottom tuyere (BT) such that the surface area for reaction between the solid flux and the liquid slag increases with the change in particle size injected through bottom charging, leading to substantial increase in the overall reaction rate; and simultaneously adding from the storage hoppers disposed on the top of the furnace, a reduced quantity of calcined lime to form slag for improved refining, the reduction being equivalent to said predetermined quantity of pulverized limestone charged via bottom injection. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS The present invention will be better understood from the following description with reference to the accompanying drawings in which Figure 1 graphically represents the effect of particle size on the variation of total surface area of a pulverized solid material. Figure 2 shows the variation of total surface area corresponding to practice size, when represented on a logarithmic scale. Figure 3 shows a schematic longitudinal section view of a BOF with flux charging hoppers and bottom injection tuyeres. Figure 4 a shows schematic longitudinal section view of flux bottom tuyeres showing refractory blocks and injection slits, according to the present invention. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Reaction between the solid flux and the liquid slag / metal is restricted to the surface of the solid. Thus, any method that increases the available surface area shall certainly increase the rate of reaction. where, p = rate of reaction K = a constant, function of temperature and turbulence AS/L = surface area available for reaction f(ai) = a function of the activities of the reactant species Fig. 1 shows the variation of total surface area with change in particle size, 1m3 gross volume of the material, containing uniform spherical particles, when taken as the basis for the calculations. Fig. 2 shows the similar variation, on a logarithmic scale. It can be seen clearly from Fig.s 1 and 2 that the surface area available for reactions varies inversely with the mean particle size. Thus, reduction in the particle size gives enormous increase in the overall reaction rate. Pulverised limestone, when injected into the basic oxygen converter during steelmaking, will undergo thermal decomposition to generate nascent CaO and CO2 gas. The evolved CO2 generates large number of bubbles, thus leadjng to strong agitation of the bath : Figure 4. shows a bottom purging device according to the invention. Means for injection of pulverised limestone is incorporated into at least one bottom purging tuyere of the furnace. As shown in figure 4, an injection chamber (1) is provided below the bottom tuyere (BT), wherefrom the limestone fines flow through straight slits or holes (SH) in the refractory block (RB). Small sized limestone chips are put through crushing and grinding in order to produce the pulver of desired fineness. The fines generated during handling of raw limestone can be used directly, after proper sizing. The pulverised limestone is then fluidised with the inert gas to be injected, i.e. Ar (or N2, if the steel cleanliness requirement permits) and conveyed pneumatically to the injection chamber (1) at the bottom of the BOF. Some vibration means can be optionally incorporated into the pneumatic conveyor and/or injection chamber for cleaning in the event of choking or deposition. One or more tuyeres can be equipped for pulverised limestone injection, depending on the requirement. The remaining tuyeres can continue with the normal function of gas purging. ADVANTAGES OF THE PRESENT INVENTION The invention thus provides a technique for addition of pulverized un-calcined limestone through the bottom of basic oxygen steelmaking furnace, which will partly replace the addition of calcined lime from the top of the furnace. The method will enhance reaction rate and reduce the total refining time. The addition of pulverized limestone from the bottom of the basic oxygen furnace will in no way interfere with the oxygen jets issuing from the lance at the top. The loss of calcined lime to the exhaust dust, and adhesion with the material handling equipments, will be reduced. The process will reduce the overall dust generation in the basic oxygen steelmaking process, thus helping to reduce environment pollution. WE CLAIM 1. An improved method of producing liquid steel in a basic oxygen furnace, the method comprising the steps of: - providing small size limestone chips and causing the chips to undergo crushing and grinding operation to produce pulvers of fineness less than 0.5mm; the pulvers being fluidized with an inert gas carrier, as Ar or N2; - providing at least one bottom tuyere (BT) having means (1) for bottom purging of pulverized limestone into the furnace; - injecting a predetermined quantity of the fluidized pulvers via the purging means (1) of at least one bottom tuyere (BT) such that the surface area for reaction between the solid flux and the liquid slag increases with the change in particle size injected through bottom charging, leading to substantial increase in the overall reaction rate; and - simultaneously adding from the storage hoppers disposed on the top of the furnace, a reduced quantity of calcined lime to form slag for improved refining, the reduction being equivalent to said predetermined quantity of pulverized limestone charged via bottom injection. 2. A device for carrying-out the method as claimed in claim 1, comprising: - a crushing and grinding means to produce fine pulvers from limestone chips, the pulvers being fluidized with an inert gas carrier; - at least one tuyere (BT) installable at a bottom refractory lining of the furnace, at least one tuyere being made of refractory block (RB) with a plurality of slit holes (SH); and - an injection chamber (1) disposed below at least one bottom tuyere (BT), being flowably connected to the crushing and grinding means to receive fluidized fine pulvers, the injection chamber (1) conveying the fine fluidized pulvers into at least one bottom tuyere (BT) such that the limestone fines flow through the straight slits/holes (SH) in the refractory block (RB). 3. The device as claimed in claim 2, wherein the injection chamber (1) is provided with a vibrating means. 4. An improved method of producing liquid steel in a basic oxygen furnace as substantially described herein and illustrated with reference to the accompanying drawings. This invention relates to an improved method of producing liquid steel in a basic oxygen furnace, the method comprising the steps of providing small size limestone chips and causing the chips to undergo crushing and grinding operation to produce pulvers of desired fineness; the pulvers being fluidized with an inert gas carrier, providing atleast one bottom tuyere (BT) having means (1) for bottom purging of pulverized limestone into the furnace; injecting a predetermined quantity of the fluidized pulvers via the purging means (1) of at least one bottom tuyere (BT) such that the surface area for reaction between the solid flux and the liquid slag increases with the change in particle size injected through bottom charging, leading to substantial increase in the overall reaction rate; and simultaneously adding from the storage hoppers disposed on the top of the furnace, a reduced quantity of calcined lime to form slag for improved refining, the reduction being equivalent to said predetermined quantity of pulverized limestone charged via bottom injection.

Full Text

FIELD OF INVENTION
This invention relates to a method of producing liquid steel by adapting the
process of basic oxygen steelmaking, using hot metal as the primary raw
material. In particular, the invention relates to an improved method of producing
liquid steel by adapting bottom-injection technology with partial replacement of
calcined lime with pulverized limestone. The invention further relates to a device
for implementing the improved method in a basic oxygen furnace.
BACKGROUND OF THE INVENTION
Different fluxes are generally added during steelmaking in the basic oxygen
furnace for the purpose of better slag formation and improved refining. The
purpose of adding flux to the BOF is to combine with the oxidation products
(SiO2, P2O5, etc.) and form a fluid slag. The fluxes added to BOF during
steelmaking consist typically of calcined lime, limestone and dolomite. In
addition, some steel plants add other slag formers like bauxite and/or
manganese oxide.
All such additive materials are added dry in the form of sized lumps or
briquettes. The fluxes are kept in storage hoppers above the level of the furnace
and each hopper is equipped with a discharge valve at the bottom, along with
conveying system for transporting the flux into the BOF. The discharge valve is
opened whenever necessary and the flux in the hopper, in required quantity, is
charged into the furnace.

The lumps / briquettes of flux react with the oxidation products and start
dissolving in the slag inside the BOF. However, due to the bulky size, the rate of
reaction and dissolution is slow. As a result, the added fluxes take considerable
time before getting fully dissolved/reacted. Particles of undissoved lime are often
observed floating on liquid slag at the end of steelmaking in BOF.
Charging of bulk solids through the top of the furnace is the most conventional
and widely used technique for making such additions. Blowing of oxygen may or
may not be in progress during such addition. However, portions of the added
solids form fines during addition and those are lost in the form of and removed
by the exhaust system. This causes wastage of valuable flux materials.
The fluxes generally used in the furnace as described hereinabove, constitute:
a) Calcined lime (CaO),
Calcined lime is required during steelmaking to impart the requisite basicity in
the steelmaking slag, thus making the slag fluid and reactive. CaO combines with
P2O5 and helps to stabilise the phosphorus content in the slag, thus enabling
production of low phosphorus steel. CaO also helps to remove part of the sulphur
content from the bath, though the intensity of desulphurisation is less than that
of dephosphorisation.

Burnt dolomite (CaO-MgO):
The main purpose of adding dolomite during steelmaking is to reduce the rate of
dissolution of the MgO-based refractory lining into steelmakinq slag. In addition,
MgO also helps to reduce the viscosity of the slag, thus enhancing the kinetics of
the refining reactions.
Synthetic slag (CaO-SiO2-FeOx):
Synthetic slag allows rapid formation of liquid slag and enhance the rate of
dissolution of calcined lime. It also adds to the overall slag volume, thus
favouring the removal of impurities like phosphorus and sulphur.
Inert gas is also injected into the BOF during steelmaking for enhancing the
kinetics of chemical reactions and reducing chemical and thermal inhomogeneity.
Several designs are possible for a tuyere through which the gas is injected.
Refractory block with a single round hole
Porous plug (sponge-like structure of refractory block)
Refractory block with vertical slits
Refractory block with multiple numbers of small round channels

The basic problems with the prior art processes of steel making in the basic
oxygen furnace can be summarised as under:
(i) Calcined lime is highly friable and large quantity of CaO dust is generated
during transportation of calcined lime through the material handling
devices. This dust is carried along with the exhaust gases and the CaO
contained in it is thus lost from the basic oxygen furnace.
(ii) In addition, calcined lime is extremely hygroscopic and tends to absorb
moisture from the atmosphere during its storage and handling. Hydration
of the calcined lime, i.e. reaction with moisture from the atmosphere,
causes disintegration of lime briquettes (generation of more fines) and
makes the powder stick to the conveying and charging equipments. This
creates difficulty in maintenance of the plant machinery.
(iii) Last, but not the least, problems comes from the highly corrosive nature
of CaO. Anv contact with human body creates severe irritation and burn,
and its handling is therefore hazardous for the associated workforce.
Addition of flux materials in the form of fines / small granules would appear to be
a ready solution for enabling rapid dissolution in slag. However, exhaust gases
(also called off-gas) escape at very high flow rate through the top portion
(mouth) of the BOF and that would cause bulk of the fines to get carried out into
the exhaust stream. Therefore, it is not possible to add fines of flux materials
through the top of the BOF.

Further, the choice of a specific design in a particular steel plant depends on
relative cost and the intensity of purging desired. An arrangement of storage
hoppers (H1,H2) for top charging of flux materials and bottom tuyeres (Bl) for
injection of inert gas according to the prior art is shown in Fig. 3. The flow rate
through the bottom tuyeres is typically within 1 - 2% of the oxygen flow through
the top lance.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention propose an improved method of
producing liquid steel in a basic oxygen furnace which eliminates the
disadvantages of the prior art.
Another object of the invention is to propose an improved method of producing
liquid steel in a basic oxygen furnace which is economically viable.
A further object of the invention is to propose an improved method of producing
liquid steel in a basic oxygen furnace which prevents any deterioration of the
quality and cleanliness of liquid steel produced by the method.
A still further object of the invention is to propose a device for injecting
pulverized limestone from the bottom of the basic oxygen furnace in order to
partially replace top-charging of calcined lime.

SUMMARY OF THE INVENTION
Accordingly there is provided an improved method of producing liquid steel in a
basic oxygen furnace, the method comprising the steps of; providing small size
limestone chips and causing the chips to undergo crushing and grinding
operation to produce pulvers of fineness less than 0.5mm; the pulvers being
fluidized with an inert gas carrier, providing atleast one bottom tuyere (BT)
having means for bottom injecting pulverized limestone into the furnace;
injecting a predetermined quantity of the fluidized pulvers via the purging means
of at least one bottom tuyere (BT) such that the surface area for reaction
between the solid flux and the liquid slag increases with the change in particle
size injected through bottom charging, leading to substantial increase in the
overall reaction rate; and simultaneously adding from the storage hoppers
disposed on the top of the furnace, a reduced quantity of calcined lime to form
slag for improved refining, the reduction being equivalent to said predetermined
quantity of pulverized limestone charged via bottom injection.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The present invention will be better understood from the following description
with reference to the accompanying drawings in which
Figure 1 graphically represents the effect of particle size on the variation of total
surface area of a pulverized solid material.

Figure 2 shows the variation of total surface area corresponding to practice size,
when represented on a logarithmic scale.
Figure 3 shows a schematic longitudinal section view of a BOF with flux charging
hoppers and bottom injection tuyeres.
Figure 4 a shows schematic longitudinal section view of flux bottom tuyeres
showing refractory blocks and injection slits, according to the present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
Reaction between the solid flux and the liquid slag / metal is restricted to the
surface of the solid. Thus, any method that increases the available surface area
shall certainly increase the rate of reaction.

where, p = rate of reaction
K = a constant, function of temperature and turbulence
AS/L = surface area available for reaction
f(ai) = a function of the activities of the reactant species
Fig. 1 shows the variation of total surface area with change in particle size, 1m3
gross volume of the material, containing uniform spherical particles, when taken

as the basis for the calculations. Fig. 2 shows the similar variation, on a
logarithmic scale. It can be seen clearly from Fig.s 1 and 2 that the surface area
available for reactions varies inversely with the mean particle size. Thus,
reduction in the particle size gives enormous increase in the overall reaction rate.
Pulverised limestone, when injected into the basic oxygen converter during
steelmaking, will undergo thermal decomposition to generate nascent CaO and
CO2 gas. The evolved CO2 generates large number of bubbles, thus leadjng to
strong agitation of the bath :

Figure 4. shows a bottom purging device according to the invention. Means for
injection of pulverised limestone is incorporated into at least one bottom purging
tuyere of the furnace. As shown in figure 4, an injection chamber (1) is provided
below the bottom tuyere (BT), wherefrom the limestone fines flow through
straight slits or holes (SH) in the refractory block (RB). Small sized limestone
chips are put through crushing and grinding in order to produce the pulver of
desired fineness. The fines generated during handling of raw limestone can be
used directly, after proper sizing.
The pulverised limestone is then fluidised with the inert gas to be injected, i.e. Ar
(or N2, if the steel cleanliness requirement permits) and conveyed pneumatically
to the injection chamber (1) at the bottom of the BOF. Some vibration means
can be optionally incorporated into the pneumatic conveyor

and/or injection chamber for cleaning in the event of choking or deposition. One
or more tuyeres can be equipped for pulverised limestone injection, depending
on the requirement. The remaining tuyeres can continue with the normal
function of gas purging.

ADVANTAGES OF THE PRESENT INVENTION
The invention thus provides a technique for addition of pulverized un-calcined
limestone through the bottom of basic oxygen steelmaking furnace, which will
partly replace the addition of calcined lime from the top of the furnace. The
method will enhance reaction rate and reduce the total refining time. The
addition of pulverized limestone from the bottom of the basic oxygen furnace will
in no way interfere with the oxygen jets issuing from the lance at the top. The
loss of calcined lime to the exhaust dust, and adhesion with the material
handling equipments, will be reduced. The process will reduce the overall dust
generation in the basic oxygen steelmaking process, thus helping to reduce
environment pollution.

WE CLAIM
1. An improved method of producing liquid steel in a basic oxygen furnace,
the method comprising the steps of:
- providing small size limestone chips and causing the chips to undergo
crushing and grinding operation to produce pulvers of fineness less than
0.5mm; the pulvers being fluidized with an inert gas carrier, as Ar or N2;
- providing at least one bottom tuyere (BT) having means (1) for bottom
purging of pulverized limestone into the furnace;
- injecting a predetermined quantity of the fluidized pulvers via the purging
means (1) of at least one bottom tuyere (BT) such that the surface area
for reaction between the solid flux and the liquid slag increases with the
change in particle size injected through bottom charging, leading to
substantial increase in the overall reaction rate; and
- simultaneously adding from the storage hoppers disposed on the top of
the furnace, a reduced quantity of calcined lime to form slag for improved
refining, the reduction being equivalent to said predetermined quantity of
pulverized limestone charged via bottom injection.
2. A device for carrying-out the method as claimed in claim 1, comprising:
- a crushing and grinding means to produce fine pulvers from limestone
chips, the pulvers being fluidized with an inert gas carrier;

- at least one tuyere (BT) installable at a bottom refractory lining of the
furnace, at least one tuyere being made of refractory block (RB) with a
plurality of slit holes (SH); and
- an injection chamber (1) disposed below at least one bottom tuyere (BT),
being flowably connected to the crushing and grinding means to receive
fluidized fine pulvers, the injection chamber (1) conveying the fine
fluidized pulvers into at least one bottom tuyere (BT) such that the
limestone fines flow through the straight slits/holes (SH) in the refractory
block (RB).

3. The device as claimed in claim 2, wherein the injection chamber (1) is
provided with a vibrating means.
4. An improved method of producing liquid steel in a basic oxygen furnace as
substantially described herein and illustrated with reference to the
accompanying drawings.

This invention relates to an improved method of producing liquid steel in a basic
oxygen furnace, the method comprising the steps of providing small size
limestone chips and causing the chips to undergo crushing and grinding
operation to produce pulvers of desired fineness; the pulvers being fluidized with
an inert gas carrier, providing atleast one bottom tuyere (BT) having means (1)
for bottom purging of pulverized limestone into the furnace; injecting a
predetermined quantity of the fluidized pulvers via the purging means (1) of at
least one bottom tuyere (BT) such that the surface area for reaction between the
solid flux and the liquid slag increases with the change in particle size injected
through bottom charging, leading to substantial increase in the overall reaction
rate; and simultaneously adding from the storage hoppers disposed on the top of
the furnace, a reduced quantity of calcined lime to form slag for improved
refining, the reduction being equivalent to said predetermined quantity of
pulverized limestone charged via bottom injection.

Documents:

01299-kol-2006-abstract.pdf

01299-kol-2006-asignment.pdf

01299-kol-2006-claims.pdf

01299-kol-2006-correspondence others.pdf

01299-kol-2006-correspondence-1.1.pdf

01299-kol-2006-description(complete).pdf

01299-kol-2006-drawings.pdf

01299-kol-2006-form-1.pdf

01299-kol-2006-form-2.pdf

01299-kol-2006-form-3.pdf

01299-kol-2006-form-9.pdf

1299-KOL-2006-ABSTRACT-1.1.pdf

1299-KOL-2006-CANCELLED DOCUMENT.pdf

1299-KOL-2006-CLAIMS 1.2.pdf

1299-KOL-2006-CLAIMS-1.1.pdf

1299-KOL-2006-DESCRIPTION (COMPLETE).pdf

1299-KOL-2006-DESCRIPTION COMPLETE 1.1.pdf

1299-KOL-2006-DRAWINGS 1.1.pdf

1299-KOL-2006-DRAWINGS.pdf

1299-KOL-2006-FORM 1 1.1.pdf

1299-KOL-2006-FORM 1.pdf

1299-KOL-2006-FORM 13.pdf

1299-KOL-2006-FORM 2 1.1.pdf

1299-KOL-2006-FORM 2.pdf

1299-kol-2006-granted-abstract.pdf

1299-kol-2006-granted-claims.pdf

1299-kol-2006-granted-correspondence.pdf

1299-kol-2006-granted-description (complete).pdf

1299-kol-2006-granted-drawings.pdf

1299-kol-2006-granted-examination report.pdf

1299-kol-2006-granted-form 1.pdf

1299-kol-2006-granted-form 13.pdf

1299-kol-2006-granted-form 18.pdf

1299-kol-2006-granted-form 2.pdf

1299-kol-2006-granted-form 3.pdf

1299-kol-2006-granted-gpa.pdf

1299-kol-2006-granted-reply to examination report.pdf

1299-kol-2006-granted-specification.pdf

1299-KOL-2006-REPLY F.E.R.pdf

1299-KOL-2006-REPLY TO EXAMINATION REPORT.pdf

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Patent Number

234145

Indian Patent Application Number

1299/KOL/2006

PG Journal Number

24/2009

Publication Date

12-Jun-2009

Grant Date

06-May-2009

Date of Filing

04-Dec-2006

Name of Patentee

TATA STEEL LIMITED

Applicant Address

JAMSHEDPUR

Inventors:

#	Inventor's Name	Inventor's Address
1	SOMNATH BASU	RESEARCH & DEVELOPMENT, TATA STEEL LIMITED, JAMSHEDPUR 831001
2	SOMNATH BASU	RESEARCH & DEVELOPMENT, TATA STEEL LIMITED, JAMSHEDPUR 831001

PCT International Classification Number

C 21 C 5/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA