Field of the Invention
The present invention relates to an improved compound for desulphurization of hot metal. More particularly, the present invention relates to the improved method of desulphurization of hot metal by using Lime based compound (composition) and Silicon Oil in optimum ratio to avoid the demerits of using Lime alone as a desulphurizer. Moreover this invention also relates to the improved method of desulphurization of hot metal by using Lime based compound (composition) and Silicon Oil in definite ratio to increase the efficiency of present desulphurising compound.
Background of the invention and related prior Art
Desulphurization of pig iron in a steel mill is done in lieu of desulphurization after tapping from the blast furnace or in lieu of desulphurization in a mobile receptacle (torpedo ladle truck) between blast furnace and steel mill. Desulphurization in the steel mill is intended to lower the initial sulphur contents of e.g. 0.035% to 0.095% sulphur in order to create favorable conditions for the blasting process, after which the final sulphur contents of the finished steel are so low that higher quality of steel, such as high-duty steel, steel for the manufacture of electric plate, roller bearing steel and the like may be produced. Desulphurization of crude iron after the blasting process is used to vary the percentage of several components in the iron in order to influence casting and cooling conditions as well as material properties, and also the properties of the finished material.
The applicable metallurgic refining and/or alloying methods for the smelting of metals and metal alloys determine the ultimate properties of the material being worked or the material flux

in the metal smelting plant. The desired properties of the material flux, in turn, determine
planning of the metal smelting
If the metal smelting plant consists of a steel mill, the material being processed goes from pig iron supply (blast furnace or pig iron mixer) and from the junk yard (solid metal) to charging hall in front of the smelting furnaces. The liquid metal (steel) tapped from the furnaces (steel mill converters) is either transported through the charging hall into the hall where it is cast into upright molds, or it is transported to strand-casting facilities on the smelting furnace hall.
In accordance with a familiar proposal (technical magazine "Steel and Iron" issue of Oct. 26th 1972, pages 1088/1089) pig iron may be desulphurized in torpedo ladles outside the steel mill a treatment stand between blast furnace and steel mill. Placing such treatment stand inside steel mill, however, will result in shorter transport distances and consequently decreased loss in the liquid metal. With a treatment stand inside the steel mill, the temperatures of liquid metal before and after desulphurization and/or dephosphorization and/or desilicificati may be maintained more closely
The invention of the document CN101392310 states a sulfur-fixing agent for hot
pretreatment magnesium injection deep desulphurization and a desulphurization method, which
pertains to the technical field of hot metal pretreatment in the steelmaking process. The
fixing agent is added before hot metal charging or during hot metal charging in the LD for
metal pretreatment and the addition range is 2.0 kg/t to 4.0 kg/t iron which contains following components by the weight percentages: CaO: 68 percent to 90 percent; MgO:

percent to 12 percent, Si02: 1 percent to 5 percent, CaF2: 8 percent to 12 percent, A1203: percent to 3 percent, MnO: 0 percent to 2 percent, S: less than 0.025 percent, and P205: less than 0.06 percent. The weight percentages of various slagging constituents in the sulfur-fixing agent are as follows: quick lime: 80 percent to 95 percent and fluorite: 5 percent to 20 percent. The sulfur-fixing agent has the advantages that: slag formed by adding the sulfur-fixing agent into the molten iron after magnesium injection has very high sulfur absorption capability, relatively small viscosity and relatively low melting point; after magnesium injection, a slag conglomeration agent is added to cause the slag to conglomerate into blocks which are easy to remove and resulfiirization is prevented.
The other document CN101392309 states a slag conglomeration agent applied to hot metal
pretreatment magnesium injection deep desulphurization and an application method thereof,
which pertain to the technical field of hot metal pretreatment in the steelmaking process. The
slag conglomeration agent is sealed and packaged at 3 kg to 7kg after magnesium injection or
scattered on the slag surface evenly in the form of particulate. The addition amount is 0.5 kg/t to
1.0kg/t iron which contains the following components by the weight percentages: MgO: 32
percent to 40 percent, Si02: 0.4 percent to 1.1 percent, S: 0.010 percent to 0.025 percent, water:
) percent to 0.5 percent, and the rest is CaO and inevitable impurities.; The weight percentages
if various slagging constituents in the slag conglomeration agent are as follows: light-burned
olomite: 85 percent to 100 percent, and quick limet 0 percent to 15 percent. The slag
Onglomeration agent has the advantages that: the slag conglomeration agent can be added
timed iately after magnesium injection to cause slag to form into blocks which are easy to
move, and resulfiirization is prevented by adding acid slag conglomeration agent that is
Sierally adopted

SUMMEary of the invention
The present invention relates to an improved method of desulphurization of hot metal. More particularly, the present invention relates to the improved method of desulphurization of hot metal by using desulphurizing compound having both advantages Lime and magnesium. Invention also relates to using premix of desulphurizing compound for mono injection process. Moreover this invention also relates to the improved method of desulphurization of hot metal by using Lime based compound and magnesium in particular ratio to increase the efficiency of present desulphurizing compound. This invention also relates to the method which has a plurality of advantages of reasonable simple process of mono injection, safe and reliable operation with low cost.
Detailed description of the invention
The present invention is based on the method of desulphurization of hot metal using calcium
carbide and magnesium based composition.
The present invention will be understood and its advantages more apparent in view of the
following detailed description and accompanying drawings with two sheet according to the
present invention.
Another object of the present invention is to an improved product of desulphurization of hot
metal.
Still other object of the present invention is to provide the improved product of desulphurization of hot metal by using Lime based and magnesium in particular ratio to avoid the demerits of using magnesium and calcium carbide alone as a desulphuriser.

Another object of the present invention is to provide the method which has a plurality
advantages of reasonable simple process, safe and reliable operation with low cost.
Another object of the present invention is that the desulphurizer composition in the improved-product for desulphurization of hot metal is Fluidized Lime %, CaO is 80-98 , CaF2 is 1-4%, SiC>2 is 1.8-3% and A1203 is 1-3% in which size of the material less than 1mm.
Another object of the present invention is to provide the advantages of Fluidized Lime with Silicon Oil in specified ratio as a desulphurizer, high quality and grade of product, process simplification, cost reduction, etc.
Another object of the present invention is that an improved method of desulphurization of hot metal which comprises,
a) Tapping of high sulphur contained hot metal from torpedo to transfer ladle;
b) The desulphurizing composition is injected into the hot metal through the dip lance;
c) The composition reacts with the sulphur in hot metal;
d) After the injection the lance is pulled up and the slag is easily raked from the top of the bath.
Lime based compound (composition) is used for external desulphurization of hot metal whose efficiency can be increased by addition of certain additives. Magnesium is the strongest desulphuriser known but magnesium alone cannot be used as a desulphurizer because of following reasons-
a) Excess magnesium evaporate without reaction due to its Low melting (650°C)
& Vaporizing Temp (1105°C),

b) Low injection rates, limited because of the violent magnesium reaction,

c) Not suitable at high HM temperatures and
d) High Cost and volatile market prices.
Novelty of this instant invention lies on the composition for desulphurization of hot metal using Lime and magnesium based reagent along with certain additives as a premix for
injection . The invention itself, additional objects and advantages thereof, will best understood from the following description of certain specific embodiments, when read connection with the accompanying drawings, in which:
FIG. 1 illustrates the diagram of the Injection of DS compound through lance of the invention;
FIG. 2 illustrates the specific consumption in different heats of and present calcium carbid
based compound of the present invention;
FIG. 3 illustrates the Flow Chart of method of desulphurization of hot metal of the preser
invention;
Basically three kinds of injection technique used for hot metal desulphurization for injection desulphurising reagents, like Mono- injection, Co-injection and Multi injection. Mostly injection technique is preferred by all the integrated steel plants. In this technique desulphurising reagents can be injected at through a dip lance. Usually Lime based Magnesium based desulphurisers are used in co injection process. The new innovative product a mixture of Lime, magnesium and other additives in controlled ratio as a single reagent desulphurization through mono injection technique.

The following reactions which takes place during desulphurization process through the product:
CaO + FeS _> CaSi+ FeO (1)
Mg(s) —► Mg(g) (2)
Mg(g) + FeS —► MgS + Fe (3)
For a Ladle capacity of 100T To 200T and temperature of hot metal greater than 1350°C the following table shows test results using the compound-

Average injection time is found to be 10-15 min with average temperature drop of 10-25° C. The composition/ product has following advantages over calcium carbide based reagents during monoinjection-

Advantages:
The following are the advantages observed with the compound-
1) Present invention is a effective Compound (composition) to reduce the sulfur content of hot metal;
2) Increases the efficiency of present Lime based compound,
3) It Cost effective Desulphurizing compound;

4) Can be used as a single desulphurizing reagent in mono injection method; 5) Can be used as desulphurising reagent in Co-injection method along with magnesium specified ratio.
6) Reduces the injection and total cycle time of desulphurizing operations.
7) Reduce metal loss.
8) Less temperature drop of hot metal.
Therefore, the foregoing is considered as illustrative only of the principles of the invention Further, since numerous modifications and changes will readily occur to those skilled in the it is not desired to limit the invention to the exact formulation as described, and accordingly,
suitable modifications and equivalents may be resorted to, falling within the scope of
invention.

We claim:

1)A Lime based fluidized lime compound (composition) and Silicon Oil in optimum ratio K* the method of desulphurization of hot metal which comprises of CaO, CaF2. Mg, Si02 ar~ AI2O3 in a particular ratio.
2)The composition for the method of desulphurization of hot metal as claimed in claim wherein major ingredients are lime and Silicon Oil in optimum ratio.
3)The Lime based fluidized compound (composition) for the method of desulphurization of r*t metal as claimed in claim 1 wherein Lime based % CaO is 80-98%, CaF2 is 1-4%, Mg is CT 5 %, Si02 is 1.0-5 % and A1203 is 1-3% in a particular ratio.
4)The Lime based composition for the method of desulphurization of hot metal as claims in claim 1 wherein mono-injection/Co-injection technique is used for feeding premix.

5)The Lime based composition for the method of desulphurization of hot metal as claimed in claim 1 wherein the weight of the composition used in certain specific amount in the total ^ hot metal charge in the ladle.
6)The Lime based composition for the method of desulphurization of hot metal as claimed in claim 1 wherein the certain amount of specific consumption of the Lime based composition of compound added/ton of hot metal/point sulphur drop.
7)The Lime based composition for the method of desulphurization of hot metal as claimed in claim 1 which helps in slag fluidizing and reduces the metal loss.
8)The Lime based composition for the method of desulphurization of hot metal as claimed in claim 1 wherein the bath temperature for heating is in a range of 1350-1450°C.
9)The Lime based composition for the method of desulphurization of hot metal as claimed in claim 1 wherein the size of the ingredients is less than 1mm.

10)The New developed compound tor desulphurization of hot metal is simple , Non Hazardous and provides substantial cost savings and ease of maintenance, and increases productivity.
1l)The Lime based composition for the method of desulphurization of hot metal substantially as hereinbefore described with particular reference in accompanying drawings.