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 :
DRI AND ITS PROCESS OF MANUFACTURE FROM IRON ORE FINES ELIMINATING INDURATION.

2 APPLICANT (S)
Name : Nationality ; Address :

JSW Steel Limited.
An Indian Company.
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.


FILED OF THE INVENTION
The present invention relates to Direct Reduced Iron (DRI) and in particular directed to convert iron ore fines directly into DRI eliminating induration of agglomerates. The present invention would thus favour converting iron ore fines into DRI, the green pellets can be converted to DRO with good strength of more than 75 kg/pellet with a metallization as high as 81%. Importantly the product DRI of the invention from iron ore fines can replace steel scrap and serve as a cost-effective alternative to manufacture of DRI. Moreover, the agglomerates obtained from such process had strong affinity to magnet, with good metallization and sufficient strength for handling and transporting. The present invention is thus capable of providing an alternative process for production of DRI in a simple, fast and cost effective manner facilitating substituting the use of steel scrap in converter/arc furnace or the like for steel making favoring wide industrial application.
BACKGROUND ART
It is well known in the art of steel manufacturing that steel scrap is used as a coolant in steel making through LD converter. This scrap addition not only helps in cushioning the bottom part of LD converter and but also resists its wear. Steel scrap is also used for making steel via Arc furnace and Induction furnace route. In order to replace the costly scrap and particularly those scrap having unknown impurities, DRI has so long been used to some limited extent as a replacement of steel scrap in steel production. The DRI used in steel making is produced either from lump ore or pellets. The lump ore or pellets are sent to DRI kilns along with coal fines and some flux as a source of heat and reducing agent. With diminishing and scarce resources of lump ore, agglomeration through pelletisation has become more popular way of DRI production. In this process the iron ore fines are mixed with some flux, binder, carbon source and sent to balling disc for making green pellets in the size range 8-16mm. The green pellets are then sent to induration furnace for firing them into strong fired pellets. These pellets are sent to kilns along with coal fines and some flux for producing DRI.
Several attempts have been made in the past to replace the use of expensive steel scrap in steel making. DRI had been used as a replacement to some extent but with limitations as stated above. The process of conversion of DRI from iron ore fines involved several stages
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such as agglomeration, induration and then conversion making the conversion time consuming, complex and costly. Efforts have been on to simplify the process, make it faster and economic to provide for the DRI for steel making while meeting the requirements in terms of quality and quantity and at the same time providing means for recycling of waste material/metals.
There has therefore been a persistent need in the art to developing a process for producing DRI wherein the iron ore fines could be converted directly to DRI avoiding induration of green agglomerates. A novel technique of direct conversion of iron ore fines to DRI without induration has been attempted by way of the present invention. Coal fines are used as source of Carbon to act as a reducing agent for reduction, besides use of some flux as per requirement to facilitate agglomeration. The iron ore fines mixed with requisite amount of carbon material, flux and moisture, before sending to balling disc. The green agglomerates are then sent to a furnace having reducing or inert conditions along with sufficient amount of coal/coke fines. The agglomerates obtained from such process having desirable properties for large scale substitution of steel scrap in steel production in converter or other furnaces. The process also eliminates the use of lump ore or pellletisation process and thus avoids the time consuming induration furnace operation for firing of pellets in conventional process.
OBJECTS OF THE INVENTION
It is thus the basic object of the present invention to provide DRI and developing a method for production of such DRI by directly converting iron ore fines into Direct Reduced Iron (DRI) eliminating induration of agglomerates and in the process further replace scrap in steel making.
A further object of the present invention is directed to developing DRI and a method for production of such DRI by directly converting iron ore fines eliminating induration of agglomerates to replace steel scrap in steel making with the DRI obtained having strong affinity to magnet, with good metallization and sufficient strength for handling and transporting.
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A further object of the present invention is directed to developing DRI and a method for its production by directly converting iron ore fines eliminating induration of agglomerates to replace steel scrap in steel making by selective involvement of the amount of iron ore fines, coal fines and lime fines of desired particle size as starting materials.
A still further object of the present invention is directed to developing a method for production of DRI by directly converting iron or fines to replace steel scrap in steel making wherein Coal fines were used as source of Carbon to act as a reducing agent for reduction.
A still further object of the present invention is directed to developing a method for production of DRI by directly converting iron or fines to replace steel scrap in steel making wherein iron ore fines are mixed with requisite amount of carbon material, flux and moisture and are obtained of green pellets of 5-20 mm size.
A still further object of the present invention is directed to developing a method for production of DRI by directly converting iron or fines to replace steel scrap in steel making wherein the green pellets/agglomerates could be fired in a kiln to required temperature and duration for achieving desired good metallization and sufficient strength for handling and transporting in said DRI.
A still further object of the present invention is directed to developing a method for production of DRI by directly converting iron or fines to replace steel scrap in steel making wherein green agglomerates could be fired in a furnace having reducing or inert conditions along with sufficient amount of coal/coke fines.
SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided for DRI comprising
obtained from iron ore fines and free of any required induration of green agglomerates
and having
Fe(T) in the range of 60 to 100

Fe(Met) in the range of 50 to 100
strength in the range of 0 to 150 kg/pellet; and
metallization properties of 60 to 100 %.
According to another aspect of the present invention is directed to DRI obtained of pellets comprises:
iron ore fines - 75-100 wt. %;
lime fines - 0 -20 wt %;
carbon in green pellets - 0-5 %;
coal fines of green pellets- 10-50 %;
A further aspect of the present invention is directed to DRI comprising:
Fe(T): 60 to 100 % preferably about 82 ; Fe(Met): 50 to 100 % preferably about 66; FeO : 0 to 30 % preferably about 25; C : 0 to 4 % preferably about 0.53; S: 0 to 1.0 % preferably about 0.071
A still further aspect of the present invention is directed to a process for the manufacture of DRI comprising direct conversion of iron ore fines to DRI without induration following the steps of:
selectively mixing the iron ore fines with amount of carbon material, flux and moisture before providing in balling disc for obtaining green pellets;
forming green pellets in the balling disc;
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subjecting the green agglomerates to heating in a furnace having reducing or inert condition alongwith desired amount of coal/coke fines to thereby obtain the DRI agglomerates.
A still further aspect of the present invention is directed to said process for the manufacture of DRI comprising the steps of:
(i) providing iron ore fines, coal fines and lime fines and mixing thoroughly ,
followed by grounding such as to maintain about -325 # greater than 50% in the
total mix; (ii) adding water to the above mix to maintain moisture content in the range of 5 to
15 % preferably 8-10%; (iii) obtaining green pellets of the size ranging from 5-20 mm; (iv) mixing the green pellets with coal fines in the range of 10-50% and (v) obtaining the DRI by heating in the furnace in the temperature range of 800 to
1300°C for a period of 10-40 hrs preferably about 20hrs.
According to yet another aspect of the present invention is directed to said process comprising screening the DRI to remove the ash and any un-burnt coal fines.
A still further aspect of the present invention is directed to a process comprising utilizing the following as blend for pellet making:
iron ore fines - 75-100 wt. %;
Lime fines: 0-20%;
Carbon In green pellets 0-5%; and
Coal fines,% of green pellets: 10-50 %.
The present invention and its objects and advantages are described in greater details with reference to the accompanying non limiting illustrative figures.
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BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Figure 1(a), (b): is the flow chart showing the steps of process route for the conventional DRI making use of (a) Lump ore and (b) using iron ore fines following conventional method.
Figure 2: is the flow chart showing the steps involved in process route for the direct conversion of iron fines to DRI avoiding induration of the agglomerates/pellets, according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING FIGURES
The present invention relates to a method for direct conversion of iron ore fines into Direct Reduced iron (DRI) used in steel making in order to replace costly recycled steel scrap used in converter/furnace to act as coolant. More particularly, the present invention is directed to convert iron ore fines into DRI directly eliminating induration of agglomerates to replace scrap in steel making. The present method for converting iron ore fines into DRI involves mixing with Coal fines used as source of Carbon to act as a reducing agent for reduction, beside some flux as per requirement to facilitate agglomeration. The agglomerates obtained from such process had strong affinity to magnet, with good metallization and sufficient strength for handling and transporting-
Reference is first invited to the accompanying Figure 1(a) and (b) that illustrates the steps involved in production of DRI from (a) Lump ore and (b) from iron ore fines wherein the number of steps involved is more and the agglomerate produced is indurated in a furnace consuming much of time thu£ making the DRI production expensive and complex.
Reference is now invited to the accompanying Figure 2 that schematically illustrates the process steps involved in the DRI from iron ore fines by direct conversion in easy, fast and reliable manner meeting desired quality criteria of such agglomerates/pellets for steel manufacturing substituting use of steel scraps.
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The present process is directed to make use of the iron ore fines as starting materials that are mixed with requisite amount of carbon material, flux and moisture, before sending to balling disc. The green agglomerates are then sent to a furnace having reducing or inert conditions along with sufficient amount of coal/coke fines. The agglomerates obtained from such process had strong affinity to magnet, with good metallization and sufficient strength for handling and transporting. The steps involved in the process of DRI production by direct conversion of iron fines avoiding induration of agglomerates and thus making the process faster and productive, are summarized as follows according to an exemplary embodiment of the method as of the present invention:
(i) providing required amount of iron ore fines, coal fines and lime fines are
measured and mixed thoroughly. The raw material proportion in mix used in the
process presented below in accompanying Table-1; (ii) The above materials were ground so as to maintain particle size of -325# for
more than 50% of different fines in the total mix. (iii) Water is added to the above mix to maintain moisture content in the range of 5
to 15% preferably 8-10%. (iv) The mix is then sent to balling disc to make green pellets of size range 5-20 mm; (v) The green pellets are then mixed with coal fines in the range of 10-50% and sent
to furnace to produce DRI. The time is in the range of 10-40 h preferably 20h for
the direct reduction of iron to complete, (vi) The DRI is then screened to remove the ash and any unburnt coal fines, (vii) The DRI is then sent for chemical analysis and for physical testing, results of
which are shown in accompanying Table-3). (viii) Based on the properties of the DRI so produced, it is found suitable for use as a
replacement of costly steel scrap in steel making.
The proportion of various constituents of desired fineness in the starting mix, indicating utilization of the solid wastes for DRI making are given in the following Table I:
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Table I:

Constituents in mix wt. percent
Iron ore fines, % 75-100
Lime fines, % 0-20
Carbon in green pellets, % 0-5
Coal fines, % of green pellets 10-50
The typical analysis of iron ore fines used in laboratory scale trials is presented in the following table II.
Table II:

Blue dust Iron ore Lime Dust
Size Analysis
+2mm, % 14 14
+lmm, % 22 28
+0.5mm, % 14 16
-0.5mm, % 50 42
Chemical Analysis
Fe(Total), % 64.67 0.91
Si02, % 3.32 3.47
Al203, % 1.63 2.18
CaO, % 0.08 68.6
MgO, % 0.015 4.03
Ti02, % 0.067 0.054
S, % 0.01 0.116
LOI 1.91 19.78
The results of the analysis of the DRI finally produced following the method according to the invention and its metallurgical properties obtained, to justify its application as substitution to steel scrap in steel manufacturing process is summarized in the following Table III.

Table III:

The laboratory scale experiments with DRI production from iron ore fines mixed with other constituents derivable from the solid wastes in the proposed direct reduction route avoiding induration of agglomerates saving processing time thus ensure achieving following results:
(I) The iron ore fines are adapted to be converted into DRI.
(II) The green pellets can be converted to DRI and demonstrate good strength of more than 75 kg/pellet with a metallization as high as 81% on selectively optimizing the ratio of coal fines and green pellets as the variable process parameters.
(III) The end product obtained as DRI exhibited strong affinity to magnet, indicating reduction of hematite ore to metallic form.
It is thus possible by way of the present invention to developing a method for conversion of iron ore fines into DRI for substitution of steel scrap in steel manufacturing. The conversion process according to the invention involve the steps of starting with iron fines along with other metallic/nonmetallic fines like coal fines and lime fines etc., obtained from the solid wastes and grinded in desired fineness of particles, mixing them thoroughly, adding required moisture/water in order to form pellets in the balling disc. The green pellets so obtained having sizes in the range of 5-20mm and preferably 8-16mm is fired in a separate kiln, instead of the time consuming induration in furnace, for direct reduction in presence of reducing carbon as coal fines in desired proportion and fired at required temperature for desired time duration so that the desired metallurgical properties are obtained in resulting DRI. The present method of producing DRI is thus free of time consuming induration furnace operation for agglomerates for conversion to DRI and a reliable method of direct

reduction of pellets/agglomerates in presence of reducing carbon in a faster process to improve productivity and quality of DRI production for substitution of steel scrap in steel production in converters as well as induction or arc furnaces. The present invention thus provide for a method of DRI production using iron ore fines in a simple, efficient and cost effective manner to substitute use of scarp steel scrap in steel production in converter/furnaces favoring wide industrial application.


WE CLAIM:
l.DRI comprising
obtained from iron ore fines and free of any required induration of green agglomerates
and having
Fe(T) in the range of 60 to 100
Fe(Met) in the range of 50 to 100
strength in the range of 0 to 150 kg/pellet; and
metallization properties of 60 to 100 %.
2, Iron enriched DRI as claimed in claim 1 obtained of pellets comprises:
iron ore fines - 75-100 wt, %;
lime fines -0 -20 wt %; carbon in green pellets - 0-5 %; coal fines of green pellets- 10-50 %;
3. Iron enriched DRI as claimed in anyone of claims 1 or 2 comprising:
Fe(T): 60 to 100 % preferably about 82 ;
Fe(Met): 50 to 100 % preferably about 66;
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FeO : 0 to 30 % preferably about 25;
C : 0 to 4 % preferably about 0.53; S: 0 to 1.0 % preferably about 0.071
4. A process for the manufacture of DRI as claimed in anyone of claims 1 to 3 comprising direct conversion of iron ore fines to DRI without induration following the steps of:
selectively mixing the iron ore fines with amount of carbon material, flux and moisture before providing in balling disc for obtaining green pellets;
forming green pellets in the balling disc;
subjecting the green agglomerates to heating in a furnace having reducing or inert condition alongwith desired amount of coal/coke fines to thereby obtain the DRI agglomerates.
5.A process for the manufacture of DRI as claimed in claim 4 comprising the steps of:
(i) providing iron ore fines, coal fines and lime fines and mixing thoroughly ,
followed (ii) by grounding such as to maintain about -325 # greater than 50% in the total
mix; (iii) adding water to the above mix to maintain moisture content in the range of 5 to
15 % preferably 8-10%; (vi) obtaining green pellets of the size ranging from 5-20 mm; (vii) mixing the green pellets with coal fines in the range of 10-50% and (viii) obtaining the DRI by heating in the furnace in the temperature range of 800 to
1300°C for a period of 10 -40 hrs preferably about 20hrs.
6. A process as claimed in anyone of claims 4 or 5 comprising screening the DRI to remove the ash and any un-burnt coal fines.

7. A process as claimed in anyone of claims 4 to 6 comprising utilizing the following as
blend for pellet making:
iron ore fines : 75-100 wt. %;
Lime fines: 0-20%;
Carbon in green pellets: 0-5%; and
Coal fines,% of green pellets: 10-50 %.
8. DRI and its process of manufacture substantially as hereindescribed and illustrated with
reference to the accompanying examples.