FIELD OF THE INVENTION
00001. This invention relates to a method for producing direct reduced
iron (DRI) in a furnace. It provides a process for producing higher productivity
of DRI with lowest energy and cost by charging the hot pellets in a vertical
shaft furnace, which reduces energy consumption and increases the
productivity in vertical shaft furnace.
BACKGROUND OF THE INVENTION
2. The production of hot metal through blast furnace (BF) has
remained unchanged worldwide for more than 200 years. Hence, this increases
of steel production, consumption of iron ore increases. To meet the iron ore
requirement, huge amount of iron ore fines is generated. This generated iron
ore fines or blue dust cannot be charged directly into the blast furnace due to
the operational issue i.e., blockage of the passage for ascending gas inside the
feed. Therefore, some quantity of fines (having good quality of iron) has been
utilized through sintering and pelletization process. In recent past effort has
been made to utilize low grade iron ore fine deposits. This is necessary to
utilize generated fines wastes effectively to conserve resources and produce
optimal cost of hot metal.
3. The process of pelletization is converting iron ore fines into iron ore
pellets that can be charged into the direct reduced iron (DRI) or directly
charged in blast furnaces for production of hot metal. These pellets contribute
to faster reduction and high metallization rates. In DRI plant, shaft furnace is
a vertically mounted cylindrical vessel which is divided into two zones namely
reduction zone and the lower cone. The shaft furnace feeding system begins
with the charge hopper and during processing the oxygen contained in various
forms of iron ore or pellets, in order to convert the ore/pellet without melting it
below 1200 °C, to metallic iron. The pellet is discharged from the discharging
hopper and it stored into the stockline inside the shaft furnace.
4. The process of pelletizing combines mixing of the raw materials
(iron ore fines, lime, dolomite and binders i.e., bentonite), forming the pellet
and a thermal treatment baking the soft raw pellet to hard spheres. The raw
material is rolled into a ball (-200 mesh), 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 travelling grate
machine. The drying process consists of 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 rotary kiln. Specially designed powder coal burner is installed
at kiln discharge end and the flame length, high temperature position and, air-
powdered coal ratio. With heat radiation action inside the kiln, the pellet is
roasted at the same time of rolling so as to ensure uniform roasting. The
roasting temperature of pellet is 1250 °C -1350 °C. The pellets discharge from
rotary kiln is about 1250°C and is uniformly distributed on the pellet cart of
annular cooler through receiving hopper of 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 annular cooler
discharges the <100 °C finished pellet to finished product belt conveyor and
then to product stock yard through tripper conveyor. For 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 for
final removal of the fines, which are return to balling circuits. Hence, the pellet
meets the specification are conveyed to the pellet stockpiles or storage yard.
5. Since, both Pellet and DRI plants are the independent plant and
operate as a single unit and therefore pellet is transported at ambient
temperature to various DRI plants.
6. Hence, the cooling to hot pellet in ambient temperature cost more
energy and hence it is expensive.
7. But the present invention checks this drawback of implant cooling
of hot pellets, rather the temperature has reduced to 1200°C to 800°C than
1200°C to 40°C and provides an energy efficient process.

OBJECTS OF THE PRESENT INVENTION
8. It is therefore the primary object of the present invention to
provide a method for reducing the energy consumption for producing direct
reduced iron (DRI).
9. Another object of the present invention is to provide a method for
increasing the productivity of direct reduced iron (DRI) by use of hot pellets.
10. Yet another object of the present invention is to provide a method
for reducing the generation of fines by avoid pellet handling/transportation of
pellets.
11. Further, object of the present invention is to provide a method for
used of hot pellet which improves the process efficiency.
SUMMARY OF THE INVENTION
000012. One or more drawbacks of conventional systems and process for a
method for reducing the production efficiency through the generation of more
pellet fines during the transportation of Pellet from Pellet plant to DRI plant
which are 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.
000013. The method for producing of direct reduced iron (DRI) in a furnace
comprises the steps of :
- taking raw material such as iron ore fines, lime, dolomite along with a
binder such as bentonite in the pellet plant;
- drying said raw material and feeding into grinder and balling disc to
achieve the desired size;
- feeding of the material into the rotary kiln through travelling gate for
producing hot pellets at 1200°C-1250°C;
- direct charging of said hot pellets in the shaft furnace whereby the hot
Pellets are converted into direct reduced iron;

- Characterized in that the direct charging of hot pellets is achieved
through a diverter gate with the help of feed hopper and thereby saves
significant amount of heat.
14. Various objects, features, aspects, and advantages of the inventive
subject matter will become more apparent from the following detailed
description of preferred embodiments, along with the accompanying drawing
figures.
15. 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.
16. 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
17. 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:
18. Figure 1 illustrates the schematic layout of pellet plant for
production of iron ore pellet.
19. Figure 2 illustrates the schematic layout of DRI plant.
20. Figure 3 illustrates the schematic layout of proposed pellet cum
DRI plant.
21. Figure 4 illustrates the schematic layout of diverter gate valve for
diverting the green pellet into the annular cooler or DRI.

22. Figure 5 illustrates the schematic layout for feeding the hot pellet
to DRI feed hopper in DRI plant.
23. The figures 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
24. 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.
25. 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.
26. 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.
27. 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.
000028. The full form of some abbreviation are given below:
BF : blast furnace
CGP : coal gasification plant
DRI : direct reduction of iron
Gcal : giga calories
h : hours
kcal : kilo calories
PGC : process gas compressor
t : ton
TGS : top gas scrubber
TPH : ton per hour
29. 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.
30. The present subject matter relates to a novel process for producing
higher productivity form of direct reduced iron (DRI) in furnaces, which reduce
the energy consumption and cost significantly.
31. In this method, the hot pellet is directly charged in a vertical shaft
furnace.
32. In accordance with an embodiment of the present invention, the
pellet plant and shaft furnace of DRI furnace is treated as a combined unit so
that the hot pellet having a temperature of 800°C - 850°C can be subjected to
charging directly into the vertical shaft furnace. This phenomenon enhances
the productivity by about 25% and reduce the energy consumption by 65%.

000033. The method comprises the steps of :
i) taking raw material such as iron ore fines, lime, dolomite along with
the binder such as bentonite in the pellet plant;
ii) first drying the raw material and feed into grinder and balling disc to
achieve the desired size;
iii) feeding of the material into the rotary kiln through traveling gate for
producing the hot pellet at 1200°C-1250°C;
iv) direct charging of hot pellets in the shaft furnace and the hot pellet
is converted into the direct reduced iron;
34. In this method, the direct charging of hot pellets is achieved
through a diverter gate with the help of feed hopper and thereby saves
significant amount of heat.
35. The overall process is illustrated in Fig 3.
36. The direct charging of hot pellet takes place in shaft furnace at
800°C and Fig 4 clearly illustrates the diverter valve through which the hot
pellet is transferred from pellet plant to DRI furnace.
37. In accordance with an embodiment of the present invention, Fig 1
illustrates the diagram of pellet plant, where different raw materials such as
iron ore, lime stone, bentonite are taken and these are drying and then
subjected to grinding in balling disc and transferred through feeder, travelling
gate, rotary kiln to the annular cooler and pellet is formed and stored in the
pellet storage area.
38. Fig 2 also illustrates about the structural or shaft diagram of the
DRI plant. The shaft furnace is a vertically mounted cylindrical vessel which is
divided into two zones namely reduction zone and the lower cone. The shaft
furnace feeding system begins with the charge hopper and during processing
the oxygen contained in various forms of iron ore or pellets, in order to convert
the ore/pellet without melting it below 1200 °C, to metallic iron.

39. Further, the feed hopper is attached to TGS and PGC (kindly let us
have the full form), then the raw materials are treated for CO2 removal and
other ingredients such as feed gas mixer, syn gas are used.
40. In the present invention, hot pellets (~800°C) directly charged to
the vertical shaft furnace and hence saved the significant amount of heat i.e.,
3,79,68,750 kcal/hr which is the less requirement of heat by about 65% by
cooling of hot pellet from 1250°C to 40°C as compare to 1250°C to 800°C . The
power saving is also quite significant. Therefore, in the present invented
process lot of energy saved by unnecessary cooling the pellet from 1250°C
(temperature after the production of pellets in to the shaft furnace) to 40°C
(ambient temperature). Also for further processing of the DRI almost minimal
heat is required for converting pellet to DRI. Hence, by adopting the said
process, 30,000 kcal/ton energy is saved. The energy balance of DRI plant,
pellet plant and energy balance of proposed process are presented in Table 5,
Table 6 and Table 7 respectively.
41. The power is saved is 0.5% dry and cooling of hot pellet in annular
cooler and specific energy reduces by 30,000 kcal/ton due to hot pellet
discharge.
42. Further as per the present invention, the productivity of DRI has
increased by about 20% by utilization of hot pellet (800-850°C) in DRI furnace
and the fines generation is less by approximately 7 - 8% due to avoid multi
handling of pellets which is also reduces the transportation cost.
43. Table 1, 2 and 3 provides the thermal energy balance of the
combined plant as claimed, pellet plant and DRI plants.
44. The tables are given below :
Table 1: Thermal/energy balance of the plant as claimed hereinafter

45. Fig 5 also illustrates how the hot pellet transfer from shaft furnace
to direct reduced iron.
46. It comprises some feed legs when the pocking holes are inserted.
47. The process equipment used different raw materials such as iron
ore, lime, dolomite, feed silos, dryer, grinder, balling disc, feeder, traveling gate,
rotary kiln, shaft furnace, TGS, PGC, CO2 removal, feeder gas mixer, Syn gas
and CGP with reducing gas heater and bentonite was used as a binder.

48. These raw materials, bentonite and the iron ore dust collected in
the plant is subjected to automatic weight proportioning with set proportioning
ratio according to production requirements. However, to find out the optimum
level of the moisture and binder (bentonite) added to achieve maximum
possible strength under set conditions.
49. Different properties of ore fines, lime, dolomite and bentonite are
given in tables 4 to 7.
000050. The tables are given below :

Table 5: Properties of limestone fines

Table 6: Properties of dolomite fines

Table 7: Properties of bentonite
Table 4: Properties of iron ore fines


51. The present invention uses direct reduction process which
includes reduction of 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. Due to the fact that during
direct reduction processes only oxygen inherent to the iron oxide feed stocks is
removed from the system, the DRI produced has a similar but more porous
physical form than the iron oxide feed materials utilized.
52. As per the present invention, the process of pelletizing 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 air flow. 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 Iron ore grinding system for grinding the ore
to 85% below 200 mesh. The slurry produced is then fed to 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.
BASIC ASSUMPTIONS FOR CALCULATION OF THERMAL BALANCE
Production of DRI : 225 TPH
Iron Ore feed rate : 337.5
Moisture content in oxide : 3.0%
Flow rate of Bustle Gas : 312212 Nm3/h
Enthalpy of Bustle Gas : 376 kcal/Nm3
Flow rate of Syn Gas : 9000 Nm3/h
Enthalpy of Syn Gas : 3525 kcal/Nm3
Flow rate of Top Gas : 553016 m3/h

Sp. heat of Flue Gas : 0.24 kcal/kg °C
Density of Top Gas : 0.588 kg/m3
Temperature of Top Gas : 365 °C
Reference Temperature : 25 °C
000053. 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.
000054. 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.
000055. The nonlimiting advantages of the present invention are given
below:
i) The power is saved ~0.5% during the cooling of hot pellet in annular cooler;
ii) The specific energy reduces by 30,000 kcal/t due to hot pellet discharge;
iii) The productivity of DRI increased by about 20% by utilization of hot pellet
(800- 850 °C) in DRI;
iv) The process efficiency of DRI claims significant improves by charging of hot
pellets in DRI;
v) The fines generation is less by approximately 7-8% due to avoid multi
handling of pellets which is also reduces the transportation cost.
vi) The process increases the process efficiency of DRI plant

vii) The process reduces the transportation and hence fines one generated less.
Equivalents:
56. 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.
57. 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.
58. 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.
000059. 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.

60. 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.
61. 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 method for producing of direct reduced iron (DRI) in a furnace comprises
the steps of:
- taking raw material such as iron ore fines, lime, dolomite along with a
binder such as bentonite in the pellet plant;
- drying said raw material and feeding into grinder and balling disc to
achieve the desired size;
- feeding of the material into the rotary kiln through travelling gate for
producing hot pellets at 1200°-1250°C;
- direct charging of said hot pellets in the shaft furnace whereby the hot
Pellets are converted into direct reduced iron;
characterized in that the direct charging of hot pellets is achieved
through a diverter gate with the help of feed hopper and thereby saves
significant amount of heat.
2. The method for producing of direct reduced iron (DRI) as claimed in claim 1,
wherein the charging of hot pellet takes place at 800-850°C in shaft furnace.
3. The method for producing of direct reduced iron (DRI) as claimed in claim 1,
wherein the hot pellet in produced into the rotary kiln at 1200°C - 1250°C.
4. The method for producing of direct reduced iron (DRI) as claimed in claim 1,
wherein the temperature of hot pellet cools from 1200°C to 800°C.
5. The method for producing of direct reduced iron (DRI) as claimed in claim 1,
wherein the heat is saved about 3,79,68,750 kcal/h or 65.2% during the
cooling of hot pellet in annular cooler.