FIELD OF INVENTION:
This invention relates to process for producing Low Phosphorus Steel.
BACKGROUND OF THE INVENTION:
There is no effective process and Dephosphorising compound available
for doing dephosphoriation in induction furnace.
OBJECTS OF THE INVENTION:
An object of this invention is to propose a process for producing low
phosphorus steel.
Another object of this invention is to propose a process to reduce
the phosphorus content in the induction furnace and steel making
ladles.
Further object of this invention is to propose a process to overcome
the restriction in reducing phosphorus in induction furnace.
Yet another object of this invention is to propose a process for
producing steel having phosphorus content less than 0.015 %.

Still further object of this invention is to propose a process for producing
low phosphorus steel which will be beneficial to meet the current
demand.
BRIEF DESCRIPTION OF THE INVENTION:
According to this invention there is provided a process for
producing low phosphorus steel comprising:
(a) adding scrap , DRI and other material to the induction furnace,
(b) heating the charge and adding dephosphorising compound,
(c) adding dephosphorising compound and fluidizer to the total
charge once it melts,
(d) raking out slag as much as possible,
(e) adding dephosphorising compound and fluidizer to the
remaining melt at 15000C -17000C,
(f) Retaining slag and tapping the processed steel.
DETAILED DESCRIPTION OF THE INVENTION:
In practice phosphorus is considered as harmful impurities except in few
grades of steel where it is used as an alloying additive. The technique of
removing phosphorus from the bath is done in oxidizing atmosphere. The
newly developed Dephosphorising compounds [JDEP -I] and Fluidizer
[JFLUD] are found very effective in removing

phosphorus from the bath. The compositions of these compounds are as
follows:
• Composition of Dephosphorising compounds [JDEP -I]:

• Composition of Fluidizer [JFLUD]

Basic Reaction Principle:
Newly developed Dephosphorising compound [JDEP -I] which has certain
% FeO which takes part in removing phosphorus from the Induction
furnace which has basic refractory lining is based on its oxidation by
[conditional] the reactions which evolve heat when moving to the right.
The P2O5 formed is bound in a stable compound in the slag that inhibits
the reverse reaction; it cannot exist in the free stable stage since it is
unstable at high temperature.

2[P] + 5 (FeO)= (P2O5) + 5 [Fe]
or,
2[Fe2P] + 5 (FeO) = (P2O5) + 9[Fe]
In presence of FeO, P2O5 also formed iron triphosphafe in the bath.
The reaction is as follows:
3FeO + P2O5=(FeO)3P2O5
The certain % of CaO content in the Dephosphorising compound
helps to form most stable compound with P2O5. The reaction takes
place as follows:
4 (CaO) + (P2O5) = (CaO) 4P2O5
The strong bond between CaO and P2O5 can be destroyed by SiO2
present in the free State:
(CaO)4 P2O5 + 2 (SiO2) = 2 (CaO)2 SiO2+ (P2O5)
For effective Dephosphorisation sufficient amount of CaO is added
in dephosphorising compound to ensure the formation of (CaO) 4
P2O5 and (CaO) 2 SiO2 with certain surplus left over in the slug. The
amount of CaO by addition of this Dephosphorising compound also
ensures the formation of other mineral compounds.

The Dephosphorisation reaction can be written as:

The addition of fluidizer also plays a very important role in the
dephosphorisation process. Suitable mixing of CaF2 and AI2O3 acts
as an effective fluidizer in the bath and helps in removing slag
which directly improves the efficiency of the dephosphorisation
process of the bath.
The complete detail is shown in the accompanying Figure 1 Process
Flow Chart.
EXAMPLES:
The complete details shown in accompanying Figure 1.
• Addition of scrap and the raw material in induction furnace.
• After complete addition of charge mix in the Induction Furnace
when it becomes red hot 20 % - 35 % of Dephosphorising
compound (JDEP-1) added into the bath.

• After melting of total charge mix again 30 % - 45 % Dephosphorising
compound (JDEP-1) along with 25 % - 45 % of fluidizer added into
the bath.
• Take temperature and sample for analysis.
• Rake out slag as much as possible.
• Take sample and temperature.

• After proper slag removal add 20 % - 50 % Dephosphorising
compound(JDEP-l)along with the remaining 55 % - 75 % of fluidizer
at temperature of about 1500°C - 1700° C.
• Rake out slag as much as possible.
• Take final sample and temperature.
• After completion of the total refining process tap the steel.
We have conducted 5 Nos of trial in 50 Kg Induction furnace. Initial
chemistry of the charge mix is as follows:


After addition of newly developed Dephosphorising compound along
with the fluidizer the results obtained are as follows:
• HEAT 1 :
o Weight of Scrap charge : 25 Kgs
o After addition of 2.24 kg Dephosphorising compound along
with the fluidizer (JDEP -1 and JFLUID)
- Metal Temperature : 1636° C
- Metal Analysis:

HEAT 2:
o Weight of CRS Scrap charge : 50 Kgs
o After addition of 2.81 kg De Dephosphorising compound along
with the Fluidizer (JDEP -land JFLUID)
- Metal Temperature : 15690C
- Metal Analysis


HEAT 3:
• Weight of CRS Scrap charge : 50 Kgs
After addition of 2.16 kg Dephosphorising compound along with
the fluidizer (JDEP -land JFLUID)
- Metal Temperature :1619°C
- Metal Analysis

HEAT 4:
Weight of Scrap charge: 50 Kgs
After addition of 2.16 kg Dephosphorising compound along with the
Fluidizer (JDEP-1 and JFLUID)
- Metal Temperature : 1600°C
- Metal Analysis


HEAT 5:
• Weight of CRS Scrap Charge : 25 Kgs
After addition of 1.03 kg Dephosphorising compound along with the
fluidizer (JDEP-land JFLUID)
- Metal Temperature : 1527°C
- Metal Analysis

10. Other findings:
Aim: P less than 0.020 % after treatment.
Chemical required: Dephosphorising compound along with the
fluidizer
Procedure: As mentioned earlier.
The bath temperature of the Induction Furnace is kept within the range of
1500°- 1700°C. The quantity of compound added is about 4 % -5 % of
charge weight to reduce Phosphorus from 0.082 % to a lower percentage
which is less than 0.015 % in 25 kg to 50 kg charge mix. However this
quantity of dephosphorising compound along with the fluidizer can

reduce further in higher capacity Induction furnace.
The present invention consists of dephosphorisng compound along with
fluidizer which comprises certain % of FeO, CaO in Dephosphorising
compound and CaF2 and AI2O3 in fluidizer and systematic process of
addition for achieving phosphorus level less than 0.015 % after treatment
in Induction furnace.
FIGURE 1 Process Flow Chart

WE CLAIM:
1. A process for producing low phosphorus steel comprising:
(a)adding scrap , DRI and other material to the induction furnace,
(b) heating the charge and adding dephosphorising compound,
(c) adding dephosphorising compound and fluidizer to the total
charge once it melts,
(d) raking out slag as much as possible
(e) adding dephosphorising compound and fluidizer to the
remaining melt at 15000C-17000C,
(f) retaining slag and tapping the processed steel.
2. The process as claimed in claim 1, wherein the said
dephosphorising compound is:
% CaO: 60 % - 85 % and
%FeO: 15%-40%
3. The process as claimed in Claim 1 .wherein the said fluidizer is
%CaF2: 15%-35% and
%Al2O3:65%-85%

4. The process as claimed in claim 1, wherein the amount of
dephosphorising compound is added in step (b) is 20 % - 35 % .
5. The process as claimed in claim 1, wherein the amount of
dephosphorising compound and fluidizer added in step ( c ) is 40
% - 45 % and 25 % - 45 % respectively.
6. The process as claimed in claim 1, wherein the amount of
dephosphorising compound and fluidizer added in step ( c ) is 20
%-50% and 55%-75% respectively.

According to this invention, a process has been developed for
producing low phosphorus steel comprising:
(a)adding scrap and other material to the induction furnace,
(b)heating the charge and adding dephosphorising compound
(c)adding dephosphorising compound and fluidizer to the total
charger once it melts,
(d)raking out slag as much as possible,
(e)adding dephosphorising compound and fluidizer to the metal
bath at 15000C-17000C,
(f) Retaining slag and tapping the processed steel.