FIELD OF THE INVENTION
1. This invention relates to a superior quality, high strength iron ore
fine pellet to improve the DRI unit performance.
2. The Pellet is generally used in direct reduction of iron (DRI) in
ironmaking route in the iron and steel plant.

3. The Pellets also help to enhance the performance of the pellet plant
itself, thereby enhancing the overall performance of the ironmaking DRI
route by increasing the overall productivity of the Pellet plant and DRI plant.
4. The present invention further discloses a methodology for producing
a superior quality pellet as mentioned above characterized by physical
strength (CCS) and metallurgical analysis (RDI & RI).
BACKGROUND OF THE INVENTION
5. The production of hot metal through blast furnace (BF) has
remained unchanged for more than 20 decades, and simultaneously the steel
demand increased significantly globally. Therefore to cater for the steel
requirement, the production of steel has been increased considerably. Hence,
the need for iron ore increased, and the quantity of generated iron ore fines
increased accordingly. This generated iron ore fines or blue dust cannot be
used directly into the blast furnace due to the inherent limitation of the blast
furnace process, like blockage of the passage for ascending gas inside the
feed. Hence, generated iron ore fines utilize in the sintering and pelletization
process.
6. In general, the sinter plant can use a good quality of iron ore fines
that contain a good amount of iron (Fe) and the rest low-grade iron ore fine
utilized in the pelletization process for making iron ore pellet in the pellet
plant. Therefore it is necessary to use generated fines wastes effectively to
conserve resources and produce the optimal cost of hot metal.

007. In the pelletization process, iron ore fines converted into iron ore
pellets that can be used into the direct reduced iron (DRI) or directly charged
in blast furnaces to produce hot metal. These pellets contribute to faster
reduction and high metallization rates. In the DRI plant, the shaft furnace is
a vertically mounted cylindrical vessel divided into two zones, viz., reduction
zone and the lower cone. The shaft furnace feeding system begins with the
charge hopper and processing the oxygen concentration in various iron ore or
pellets. Hence, in this process, the iron ore fines convert the ore/pellet
without melting it below 1200 °C to metallic iron. The prepared iron ore pellet
discharged from the discharging hopper, and it stored into the stock line
inside the shaft furnace.
008. The pelletization process combines different raw materials (like
iron ore fines, lime, dolomite, coal, mill-scale and binders), forming the green
pellet, which needs a thermal treatment to bake the green pellet into hard
spheres. The raw material rolled into a ball, then fired in a kiln to sinter the
particles into a hard-sphere. The configuration of iron ore pellets as packed
spheres in the DRI plant allows air to flow between the pellets, decreasing the
resistance to the air that flows up through the layers of material during the
smelting. The green pellets are dried and preheated on a travelling grate
machine. The drying process consists of an updraft drying section, downdraft
drying section, preheating section I and Section II. The Roasting and
solidification process of pellet is done in the rotary kiln and rolled along the
circumference of the rotary kiln. A coal powder burner installed at the
discharge end of the kiln. The flame length and temperature position adjusted
with the help of the air-powdered coal ratio. With heat radiation action inside
the kiln, the pellet is roasted simultaneously as rolling to ensure uniform
roasting. The roasting temperature of the pellet is 1250 -1350°C. The pellets
discharged from the rotary kiln is about 1250 °C and uniformly distributed
on the pellet cart of the annular cooler through receiving hopper of the
annular cooler. The pellet is then cooled to below 100°C and is further
oxidized in the annular cooler so that the FeO content is reduced to below
1%. The discharging hopper of the annular cooler discharges finished pellet
at 90-100°C to the finished product belt conveyor and then to the product

stockyard through the tripper conveyor. For the de-dusting purpose, plant
de-dusting ESP has been installed. The dust collected is fed pneumatically to
a collecting bin in proportioning building, and the same is reused as raw
material. The pellets are screened to meet the size specification, with
undersized, chipped and or broken into fines are crushed and returned to the
balling drums. The soft pellets are then delivered to the roller feeder to remove
the fines, which returned to balling circuits finally. Hence, the pellet meets
the specification conveyed to the pellet stockpiles or storage yard.
009. The direct reduction (DR) processes include reducing iron oxides
in the solid-state, below the fusion temperature of pure iron (1535°C), utilizing
hydrocarbon gases and or carbon-bearing materials as reducing–carburizing
agents. Direct reduced iron (DRI) is a highly metallized solid that still contains
slag. Since direct reduction processes, only oxygen inherent to the iron oxide
feedstocks removed from the system. The DRI produced has a similar but
more porous physical form than the iron oxide feed materials utilized. Thus,
due to this porous structure, DRI is often called sponge iron.
010. Based on availability of low grade Iron ore fine (Fe: 62-64%; Al2O3:
3.5 – 4%), the produced pellet have less strength (CCS: 240- 260) and
therefore the undersize generation is high (-10 mm: ~ 9-10%). Due to the
higher percentage of undersize generation, the operational efficiency of DRI
plant goes down which is directly affects the productivity of the plant. Hence
the present invention helps for enhancing the productivity by producing
superior quality of pellet from the available low grade iron ore fines.
OBJECTS OF THE PRESENT INVENTION
11. It is therefore the primary object of the present invention to provide
a superior quality, high strength iron ore fine pellet, which is a by-product
produced during the casting and rolling process, contains more than 70%
(70 – 75%) Fe and the material also fines.
12. Another object of the present invention is to provide a high quality

iron ore pellet, chiefly composed of magnetite, and it is almost free of any
silica or alumina type gangue.
013. Yet another object of the present invention is to provide a method
for a superior quality pellet.
014. Further another object of this invention is to propose a process
for increasing the productivity of DRI (Direct Reduced Iron) plant through
using the improved pellets.
015. Still another object of this invention is to propose a process for
reducing the generation of fines by increasing the CCS, RI and reducing the
RDI of the Pellet during handling/transportation.
016. Further, an object of this invention is to propose a process for
increasing the Fe% in the improved pellet.
SUMMARY OF THE INVENTION
017. One or more drawbacks of conventional systems and process for
a method for utilizing of low grade Iron Ore fines to produce the desired quality
of Pellet in terms of CCS, RDI and RI. With the help of present invention, the
pellet quality issues had been overcome, and additional advantages are
provided through the method as claimed in the present disclosure. Additional
features and advantages are realized through the technicalities of the present
disclosure. Other embodiments and aspects of the disclosure are described in
details herein and are considered to be part of the claimed disclosure.
018. The present invention provides a superior quality iron ore pellet
to improve the DRI unit performance, which comprises of iron ore fines, Coal,
Limestone, mill-scale particles and bentonite.
019. The iron ore pellet is characterized in that pellet comprises iron
ore powder with ~90.5% iron ore fines, coal ~1.5% and binder (bentonite:

0.5%). All the raw material is evenly mixed, and the mixture is then supplied
to a forming device for forming treatment so that the pellet is obtained which
is called a green pellet.
20. The prepared green pellet is dried at 100 -260 °C and then
preheats at 700 – 800 °C. The preheat pellet is then fed into a roasting device
for oxidation treatment, and the temperature is controlled 1100- 1200 °C,
and roasted pellet cooled, and thus the finished pellet is obtained.
21. Various objects, features, aspects, and advantages of the
inventive subject matter will become more apparent from the following
detailed description of preferred embodiments, alongwith the accompanying
drawing figures.
22. It is to be understood that the aspects and embodiments of the
disclosure described above may be used in any combination with each other.
Several of the aspects and embodiments may be combined to form a further
embodiment of the disclosure.
023. The foregoing summary is illustrative only and is not intended
to be in any way limiting. In addition to the illustrative aspects,
embodiments, and features described above, further aspects, embodiments,
and features will become apparent by reference to the drawings and the
following detailed description.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
024. The illustrated embodiments of the subject matter will be best
understood by reference to the drawings, wherein like parts are designated
by like numerals throughout. The following description is intended only by
way of example, and simply illustrates certain selected embodiments of
system processes that are consistent with the subject matter as claimed
herein, wherein:

25. Figure 1 illustrates the schematic layout of the pellet plant for
the production of iron ore pellet.
26. The figure depict embodiments of the disclosure for purposes
of illustration only. One skilled in the art will readily recognize from the
following description that alternative embodiments of the methods
illustrated herein may be employed without departing from the principles
of the disclosure described herein.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
27. While the embodiments of the disclosure are subject to various
modifications and alternative forms, specific embodiment thereof have been
shown by way the figures and will be described below. It should be
understood, however, that it is not intended to limit the disclosure to the
particular forms disclosed, but on the contrary, the disclosure is to cover all
modifications, equivalents and alternative falling within the scope of the
disclosure.
28. It is to be noted that a person skilled in the art would be
motivated from the present disclosure to arrive at a method for producing
higher productivity of DRI in furnace. Such a method for evaluating the same
may vary based on configuration of one or more workpieces. However, such
modifications should be construed within the scope of the disclosure.
Accordingly, the drawings illustrate only those specific details that are
pertinent to understand the embodiments of the present disclosure, so as
not to obscure the disclosure with details that will be clear to those of
ordinary skill in the art having benefit of the description herein.
29. As used in the description herein and throughout the claims that
follow, the meaning of “a”, “an”, and “the” includes plural reference unless
the context clearly dictates otherwise. Also, as used in the description herein,
the meaning of “in” includes “in” and “on” unless the context clearly dictates
otherwise.

030. The terms “comprises”, “comprising”, or any other variations
thereof used in the disclosure, are intended to cover a non-exclusive
inclusion, such that a method, system that comprises a list of components
does not include only those components but may include other components
not expressly listed or inherent to such method, or assembly, or method.
031. The full form of some abbreviation are given below:
BF : blast furnace
CCS : cold crushing strength
DRI : direct reduction of iron
RDI : reduction degradation index
RI : reducibility index
h : hours
MTD : Metric tons per day
TPH : ton per hour
032. In other words, one or more elements in a system or device
proceeded by “comprises…..a” does not, without more constraints, preclude
the existence of other elements or additional elements in the system,
apparatus or device.
33. The present subject matter relates to a superior quality high strength
pellets, which produced through the addition of mill scale in the input raw
material, which is a by-product produced during the casting and rolling
process, contains 70-75 % Fe and the material also fines.
34. The pellet is consists of magnetite, and it is almost free of any silica
or alumina type gangue.
035. The pellet raw material included iron ore fines 90.28%, Coal
1.4%, Limestone 1.8, mill-scale 6% and bentonite 0.52%%.

036. The comparison of the normal or conventional pellet and the
improved pellets as claimed hereinafter is given in below table 1:

Table 1
Particulates Normal
Pellet Pellet as per the
present invention
Iron ore find
addition, % 96 90.28
Coal, % 1.5 1.4
Limestone, % 2 1.8
Mill scale, % 0 6
Bentonite, % 0.52 0.52
Fe, % 64.71 65.38
SiO2, % 2.63 2.22
Al2O3, % 2.88 2.68
037. The comparison in the quality and characteristic feature
between the normal pellet and improved pellet as claimed is given in table 2.

Table 2
Particulates Normal
Pellet Pellet as per
the present
invention
Production
Production, MT/h 400 500
Production,
MT/DAY 9500 12000

Chemical Analysis of Pellets
Fe, % 64.71 65.38
SiO2, % 2.63 2.22
Al2O3, % 2.88 2.68
Physical Analysis of Pellets
CCS, kg/pellet 262-270 286-290
Tumble Index, % 2.63 2.22
Abrasion Index, % 2.88 2.68
Metallurgical Analysis of Pellets
RDI, % >12 <8
RI, % <65 >73
038. The properties of mill scale material as mentioned is given in
table 3 :
Table 3: Properties of mill-scale material

Fe, % FeO, % SiO2, % Al2O3, % LOI
70 - 75 50-65 0.35 – 0.60 0.25 – 0.75 (-7.5) to (-6.6)
039. In accordance to the embodiment of the present invention, there
is provided a process for producing superior quality of pellet with the optimal
CCS and RDI comprising the steps of:
Taking iron ore fines, lime, dolomite, mill scale and bentonite used as a
feed of pellet plant;
iron ore pellet produced at pellet plant;
using of iron ore fines pellet as feed material in DRI plant.
040. The method comprises the steps of :

i. uniformly mixing of the above raw materials such as iron ore fines,
Coal, Limestone , mill-scale and bentonite and preparing as feed for
producing the pellet, and the pelletized pellets with a size of 8-16 mm
account for more than 85% (89%-92%) of the total weight of the pellets;
ii. drying of the prepared green pellets at a temperature of 100-250 °C
and then preheated at a temperature of 700-800 °C;
iii. transferring the preheated pellets into the calcining device for
oxidation treatment, with controlling the temperature at 1100 -1200
°C;
iv. the fired pellets are cooled to obtain a final product
41. In this method, the said iron ore is crushed to a fineness of 85%
below minus 200 mesh.
42. The iron ore pellet is high in CCS 286 - 290 compared to the
traditional pellet (262-270), and the RI is >73 compared to earlier <65. The
utilization of pellet as per the present invention in the DRI plant has
increased, and hence the productivity of DRI increased significantly; thereby,
the production cost for ironmaking is reduced.
43. The overall process flow sheet of the process is mentioned in
Figure 1.
44. Pelletizing process involves mixing very finely ground particles
of iron ore fines, additives like limestone, dolomite, coal, mill-scale, and
bentonite. After that, it shapes them into near-spherical balls. The size of the
balls is in the range of 8 mm to 16 mm in diameter by a pelletizer/balling
disc and then hardening the balls by firing with a fuel. It is an agglomerating
process of converting iron ore fines into ‘uniformed sized iron ore pellets
which can be charged directly into a blast furnace (BF) or a vertical furnace
or rotary kiln used for the production of direct reduced iron (DRI).

45. The raw material is first dry at the dryer and then feed into a
grinder and balling disc for the desired size. The selected size material then
feed into the rotary kiln through a travelling grate to produce the hot pellet
at around 1200 °C. These hot pellets charged directly into the shaft furnace
(DRI furnace) via diverter gate with the help of the feed hopper of the DRI
furnace for further processing. After completion of the process, the charged
hot pellet converts into the direct reduced iron.
46. The present invention uses pelletizing process which involves
mixing very fine particles of iron ore fines with additives (like limestone, coal
& bentonite) and then shaped them into near-spherical balls with the size in
the range of 8 mm to 16 mm in diameter by a pelletizer/balling disc and then
hardening the balls by firing with a fuel. It is an agglomerating process that
converting iron ore fines into ‘uniformed sized iron ore pellets which can be
charged directly into a blast furnace (BF) or into a vertical furnace or rotary
kiln generally used for the production of direct reduced iron (DRI). However,
to determine the optimum level of the moisture and binder (bentonite) added
to achieve maximum possible strength under set conditions.
47. The pelletizing process combines mixing of the raw material,
forming the pellet and a thermal treatment baking the soft raw pellet to hard
spheres. The raw material is rolled into a ball, fired in a kiln to sinter the
particles into a hard-sphere. The configuration of iron ore pellets as packed
spheres in the DRI plant allows air to flow between the pellets, decreasing
the resistance to the air that flows up through the layers of material during
the smelting. The configuration of iron ore powder is more tightly packed and
restricts the airflow. This is the reason that iron ore is preferred in the form
of pellets rather than in the form of finer particles. Raw material iron ore
fines are fed to an iron ore grinding system for grinding the ore to 85% below
200 mesh. The slurry produced is then fed to the filter press. The filter press
system used to remove the excess water from the slurry to produce filter
cakes of approximately 8.5 – 9.0 % moisture. The produced filter cakes are
then transported to the proportioning building by belt conveyor.

48. In the present invention, to utilize the mill-scale, plant trials
were conducted to determine the extent of mill scale usage in pellet plant.
For this, a different combination of iron ore fines%, mill-scale%, anthracite
coal% and limestone% were selected to optimize the optimum percentage of
the input material for producing the superior quality of pellet as per the
present invention.
49. The mill-scale mainly contains FeO and Fe3O4, hence during
induration of pellet, oxidation of FeO and Fe3O4 takes place with the
liberation of exothermic heat oxidation, which helps in diffusion bonding and
enhances recrystallization of hematite grains.
050. The possible reactions are: since this process is exothermic and
therefore the additional heat help to reduce the coal input and also help in
lower firing temperature. Hence, the RDI improved as the alumina content
decreased with the addition of mill-scale. Based on the overall, by utilization
of mill-scale in the input raw material, the Midrex DRI plant was able to
achieve a production rate of 230 TPH against their design capacity of 225
TPH, which was earlier 180 -200 TPH.
051. Table 4 discloses the Indurating furnace process parameters

Table 4
Particulates Normal Pellet Pellet as per the
present invention
Total Disc feed, TPH 550 720
Bed height, mm 530 530
Hearth layer, mm 65 50
Feed to machine, TPH 480 580
Machine speed, m/min 2.35 2.7
DRM Temp., °C 880 1020

PH-1 Temp., °C 250 260
PH-2 Temp., °C 320 340
PH-3 Temp., °C 505 550
PH-4 Temp., °C 580 680
Burn through Temp., °C 445 360
Zone -1 Temp., °C 960 980
Zone -2 Temp., °C 1050 1070
Zone -3 Temp., °C 1170 1190
Zone -4 Temp., °C 1235 1260
Zone -5 Temp., °C 1300 1305
Zone -6 Temp., °C 1320 1330
Zone -7 Temp., °C 1330 1330
Zone -8 Temp., °C 1215 1270
052. The non-limiting advantages of the present invention are
given below:
i. the cold crushing strength (CCS) of the improved pellet is (286-290)
high as compared to traditional pellet (262-270).
ii. the reducibility index RI of said pellet RI has improved from 65 to 74.
iii. DRI of said Pellet DRI metallization increases from 91% to 94%.
iv. The RDI of said Pellet reduces from 12 to 8.
v. the productivity of Pellet plant increased from 9500 MTD to 12000
MTD by about ~25% by changing the raw material composition in the
pellet mix as claimed.
vi. the productivity of DRI also increased by about ~15% from the current
level by utilization of the claimed Pellet in DRI.

vii. the operating parameter of the indurating furnace, especially Phase
1-Pase 4 and Zones 1 –Zone 8, improved the pellet plant operation
efficiency.
viii. the fines generation is less by approximately 5% due to avoid multi
handling of pellets in pellet feed, and ~5% fine reduces inside the
furnace, directly affects the productivity and operational efficiency of
the DRI plant. It also reduces the production cost.
53. Each of the appended claims defines a separate invention, which for
infringement purposes is recognized as including equivalents to the various
elements or limitations specified in the claims. Depending on the context, all
references below to the “invention” may in some cases refer to certain specific
embodiments only. In other cases, it will be recognized that references to the
“invention” will refer to subject matter recited in one or more, but not
necessarily all, of the claims.
54. Groupings of alternative elements or embodiments of the invention
disclosed herein are not to be construed as limitations. Each group member
can be referred to and claimed individually or in any combination with other
members of the group or other elements found herein. One or more members
of a group can be included in, or deleted from, a group for reasons of
convenience and/or patentability. When any such inclusion or deletion
occurs, the specification is herein deemed to contain the group as modified
thus fulfilling the written description of all groups used in the appended
claims.
Equivalents:
055. With respect to the use of substantially any plural and/or
singular terms herein, those having skill in the art can translate from the
plural to the singular and/or from the singular to the plural as is appropriate
to the context and/or application. The various singular/plural permutations
may be expressly set forth herein for sake of clarity.

56. It will be understood by those within the art that, in general,
terms used herein, and especially in the appended claims (e.g., bodies of the
appended claims) are generally intended as “open” terms (e.g., the term
“including” should be interpreted as “including but not limited to”, the term
“having” should be interpreted as “having at least”, the term “includes”
should be interpreted as “includes but is not limited to”, etc.). It will be
further understood by those within the art that if a specific number of an
introduced claim recitation is intended, such an intent will be explicitly
recited in the claim, and in the absence of such recitation no such intent is
present.
57. The above description does not provide specific details of
manufacture or design of the various components. Those of skill in the art
are familiar with such details, and unless departures from those techniques
are set out, techniques, known, related art or later developed designs and
materials should be employed. Those in the art are capable of choosing
suitable manufacturing and design details.
58. The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of the present
disclosure. It will be appreciated that several of the above-disclosed and other
features and functions, or alternatives thereof, may be combined into other
systems or applications. Various presently unforeseen or unanticipated
alternatives, modifications, variations, or improvements therein may
subsequently be made by those skilled in the art without departing from the
scope of the present disclosure as encompassed by the following claims.
059. The claims, as originally presented and as they may be
amended, encompass variations, alternatives, modifications, improvements,
equivalents, and substantial equivalents of the embodiments and teachings
disclosed herein, including those that are presently unforeseen or
unappreciated, and that, for example, may arise from applicants/patentees
and others.

060. While various aspects and embodiments have been disclosed
herein, other aspects and embodiments will be apparent to those skilled in
the art. The various aspects and embodiments disclosed herein are for
purposes of illustration and are not intended to be limiting, with the true
scope and spirit being indicated by the following claims.

WE CLAIM:
1. A superior quality iron ore pellet to improve the DRI unit performance
comprises of iron ore fines, Coal, Limestone, mill-scale particles and
bentonite.
2. The pellet as claimed in claim 1 , comprises the ingredients as follows:
iron ore fines :- 90.28%
Coal :- 1.40%
Limestone:- 1.80%
mill-scale particles :- 6.00%
bentonite:- 0.52%.
3. A method for producing superior quality of pellet for producing
superior quality of pellet with the optimal CCS and RDI, said method
comprising the steps of:
i) uniformly mixing of the above raw materials such as iron ore
fines, Coal, Limestone , mill-scale and bentonite and preparing
as feed for producing the pellet;
ii) drying of the prepared green pellets and then preheated at a
temperature of 700-800 °C;
iii) transferring the preheated pellets into the calcining device
for oxidation treatment;
iv) the fired pellets are cooled to obtain a final product .
4. The method as claimed in claim 3, wherein the pelletized pellets with
a size of 8-16 mm account for 89-92% of the total weight of the pellets.

5. The method as claimed in claim 3, wherein the green pellet is dried
at a temperature of 100-250 °C.
6. The method as claimed in claim 3, wherein the temperature of
calcining device is controlled at 1100-1200 °C.
7. The method as claimed in claim 3, wherein the said iron ore is
crushed to a fineness of 85% below minus 200 mesh.
8. The method as claimed in claim 3, wherein the said process the
cooling efficiency of the Product Cooler has been improved by the addition of
Coke Oven Gas in the existing system.