FIELD OF INVENTION:
This invention relates to reagent for producing low phosphorous steel
BACKGROUND OF THE INVENTION:
There is no effective dephosphorising reagent available for doing dephosphorisation in induction furnace.
OBJECTS OF THE INVENTION:
An object of this invention is to propose a reagent for producing low
phosphorous steel.
Another object of this invention is to propose a reagent to reduce the
phosphorous content in the induction furnace and steel making ladles
Further object of this invention is to propose a reagent to overcome the
restriction in reducing phosphorous in induction furnace
Yet another object of this invention is to propose a reagent for producing
steel having phosphorous content less than 0.015%
Still further object of this invention is to propose a reagent for producing
low phosphorous steel which will be beneficial to meet the current
demand.
BRIEF DESCRIPTION OF THE INVENTION:
According to this invention there is a reagent for producing low phosphorous steel, the process of production comprises of:
a) Adding scrap, DRI and other material to the induction furnace,.
b) Heating the charge and adding dephosphorising reagent,
c) Adding dephosphorising reagent and fluidizer to the total charge once it melts,
d) Raking out slag as much as possible
e) Adding dephosphorising reagent and fluidizer to the remaining melt at 1500°C-1700°C

DETAILED DESCRIPTION OF THE INVENTION:
In practice phosphorous is considered as harmful impurities except in few grades of steel where it is used as an alloying additive. The technique of removing phosphorous from bath is done in oxidizing atmosphere. The newly developed dephosphorising reagent and fluidizer are found very effective in removing phosphorous from the bath. The compositions of these reagents are as follows:
Composition of dephosphorising reagents:
%CaO: 30%-85% %FeO: 10%-50%
Composition of fluidizer
%CaF2: 5%-40%
%A1203: 60%-85%
Basic Reaction Principle:
Newly developed dephosphorisng reagent which has certain % FeO which takes part in removing phosphorous 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 triphosphate in the bath.
The reaction is as follows:
3FeO + P2O5 = (FeO)3 P2O5
The certain% of CaO content in the dephosphorising reagent helps to form most stable compound with P2O5. The reaction takes place as follows:
4(CaO) + (P2O5) = (CaO)4 P2O5
The strong bond between CaO and P2O5 can be destroyed by Si02 present in the free state:
(CaO)4 P2O5 + 2(Si02) = 2(CaO)2 Si02 + (P205)
For effective dephosphorisation sufficient amount of CaO is added in dephosphorising reagent to ensure the formation of (CaO)4 P2O5 and (CaO)2 Si02 with certain surplus left over in the slag. The amount of CaO by addition of this dephosphorising reagent also ensures the formation of other mineral compounds.
The dephospohorisation reaction can be written as:
2[P] + 5(FeO) = (P2O5) + 5[Fe]
(P2O5) + 3(FeO) = (3FeO P2O5)
(3FeO P2O5) + 4(CaO) = (4CaO. P2O5) + 3(FeO)
2[P] + 5 (FeO) + 4 (CaO) = (4CaO. P2O5) + 5[Fe}
The addition of fluidizer also plays a very important role in the dephospharisation 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 flowchart.
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 reagent added into the bath.
• After melting of total charge mix again 30-45% dephosphorising reagent 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 temperatue
• After proper slag removal add 20-50% dephosphorising reagent along with the remaining 55-75% of fluidizer at temperature of about 1500oC-1700oC
• 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 5nos of trial in 50kg induction furnace. Initial



After addition of newly developed dephosphorising reagent along with the fluidizer the results obtained are as follows:
Heat 1:
Weight of scrap charge: 25kgs
After addition of 2.24kg dephosphorising reagent along with the fluidizer
-Metal Temperature: 1636°C
-Metal Analysis

Heat 2:
Weight of CRS scrap charge : 50kgs
After addition of 2.81kg dephosphorising reagent along with the fluidizer
-Metal Temperature : 1569°C
-Metal Analysis:

Heat 3:
Weight of CRS scrap charge : 50kgs

After addition of 2.16kg dephosphorising reagent along with the fluidizer
-Metal Temperature : 1619°C
-Metal Analysis:

Heat 4:
Weight of scrap charge: 50kgs
After addition of 2.16kg dephosphorising reagent along with the fluidizer
-Metal Temperature: 1600°C
-Metal Analysis:

Heat 5:
Weight of CRS scrap charge: 25kgs
After addition of 1.03kg dephosphorising reagent along with the fluidizer
-Metal Temperature: 15270C
-Metal Analysis:


10. Other Findings:
Aim: P less than 0.02% after treatment
Chemical required: Dephosphorising reagent along with the fluidizer
Procedure: As mentioned earlier
The bath temperature of the induction furnace is kept within the range of 1500°C-1700°C. The quantity of reagent added is about 4-5% of charge weight to reduce phosphorous 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 reagent along with the fluidizer can reduce further in higher capacity induction furnace.

WE CLAIM:
1. A reagent for producing low phosphorous steel comprising:
a) Adding scrap, DRI and other material to the induction furnace
b) Heating the charge and adding dephosphorising reagent
c) Adding dephosphorising reagent and fluidizer to the total charge once it melts
d) Raking out slag as much as possible
e) Adding dephosphorising reagent and fluidizer to the remaining melt at 1500oC-1700oC
f) Retaining slag and tapping the processed steel
2. The reagent as claimed in claim 1, wherein the said
dephosphorising reagent is:
%CaO: 30% - 85%. and
%FeO: 10% - 50%
3. The reagent as claimed in claim 1 wherein the said fluidiser is
%CaF2: 5% - 40% and
%A1203: 60%-85%
4. The reagent as claimed in claim 1, wherein the amount is added in step (b) is 20-35%
5. The reagent as claimed in claim 1, wherein the amount of reagent and fluidizer added in step (c) is 40-45% and 25-45% respectively
6. The reagent as claimed in claim 1, wherein the amount of reagent and fluidizer added in step (c) is 20-50% and 55-75% respectively.