FIELD OF THE INVENTION:
The present invention relates to an improved process for manufacturing of sinter
product to achieve high granulability Index (GI) of base mix thereby increasing
productivity of sinter plant (SP#3).
BACKGROUND OF THE INVENTION:
In sinter making process the primary raw material is the base mix which is fired
by ignition furnace on a traveling rate, top sustain the process and combustion a
fixed amount solid fuel trimming is added, which is ignited under the Ignition
Furnace. The base mix is pretreated in a equipment known as Mixing Nodulizing
Drum (MND) where the main material base mix is mixed uniformly with finely
grinded flux, plant return fines and solid fuel. The primary aim of the Mixing
Nodulizing Drum (MND) is to give good permeability in the sinter bed. For this
the particle come out after treatment in Mixing Nodulizing Drum (MND) must
have a homogenous, uniform and granular shape. To achieve this we add
calcined lime powder and water in graduated quantity as per the feed rate.
World over this is the convention adopted in all sinter plant and at our sinter
plant (SP#3) we also follow the similar process. To check the efficiency of this
process there is a process parameter called as GI (Granulability Index). Since the
commissioning of sinter plant (SP#3) this GI level were abnormally low
compared to the standards of 60% as obtained in sinter plant (SP#1) and sinter
plant (SP#3). Higher values of GI indicated that the base mix is of uniform and
regular shape thus giving better permeability higher sinter productivity and
quality. Further investigations revealed that there was basic difference in the
input raw material characteristics at sinter plant (SP#1) and sinter plant (SP#2).

There the base mix contains about 12% plant return sinter i.e., under size
obtained from sinter screening at Steel House of F and G BF. There is no such
provision at sinter plant (SP#3). Further in sinter plant (SP#1) and sinter plant
(SP#2) there facility of hot screening of sinter, where under size obtained as HRF
(Hot Return Fines) are fed along with base mix in the Mixing Nodulizing Drum
(MND). Theoretical studies so that return fines act as perfect nucleating particle
for formation of good granules in Mixing Nodulizing Drum (MND) which improves
permeability.
A published paper of Institute for mechanics and University of California entitled
"Theory of sintering: from discrete to continuum" which discloses a teaching -
Theoretical concepts of sintering were originally based upon ideas of the discrete
nature of particulate media. However, the actual sintering kinetics of particulate
bodies are determined not only by the properties of the particles themselves and
the nature of their local interaction with each other, but also by macroscopic
factors. Among them are externally applied forces, kinematic constraints (e.g.
adhesion of the sample's end face and furnace surface), and inhomogeneity of
properties in the volume under investigation (e.g. inhomogeneity of initial density
distribution created during preliminary forming operations). Insufficient
treatment of the questions enumerated above was one of the basic reasons
hindering the use of sintering theory. A promising approach is connected with
the use of continuum mechanics, which has been successfully applied to the
analysis of compaction of porous bodies. This approach is based upon the
theories of plastic and nonlinear-viscous deformation of porous bodies. Similar
ideas have recently been embodied in a continuum theory of sintering. The main
results of the application of this theory for the solution of certain technological
problems of sintering are introduced including their thermo-mechanical aspects.

A further published paper of Chemical Engineering Science 57 (2002) 1685-1693
entitled "Modelling of granulation by a two-stage auto-layering mechanism in
continuous industrial drums" which discloses a teaching of -
A mechanistic model for the granulation of particulate materials with a wide size
distribution in a large-scale continuous drum is presented. It takes cognizance of
the effect of relevant process variables: feed size distribution, moisture content,
binders such as lime, residence time distribution, feed rate, etc. The model is
based on the auto-layering mechanism of granule growth and incorporates a
piecewise linear model for granulation kinetics. Laboratory scale tests on a batch
drum are used to provide kinetic parameters. The size-dependent residence time
distribution of agglomerating mass in the continuous drum is represented by a
combination of mixed and plug flow regimes operating in parallel. The model is
customized for a continuous drum in an iron ore fines sintering plant. The
predicted granule size distributions are in good agreement with the plant data
under widely varying operating conditions. The modeling framework provides
scope for modifying the individual modules for drum residence time distribution
or the granulation mechanism and growth kinetics.
None of the above cited documents discloses anything how to achieve higher
granulability Index of the sinter product.
The present invention discloses a teaching of how to achieve a higher
granulability Index of the sinter product to achieve higher productivity in the
Blast Furnace.
OBJECTS OF THE INVENTION:
It is therefore an object of the present invention to propose an improved process

for higher productivity of sinter by improving the Granulability Index which
eliminates the disadvantages of prior Art.
Another object of the present invention is to propose an improved process of
sinter product manufacturing to achieve high Granulability Index, which improves
in production.
A further object of the present invention is to propose an improved process of
sinter product manufacturing to achieve high Granulability Index which utilizes
the sensible heat from the plant which was otherwise getting lost.
A still further object of the present invention is to propose an improved process
of sinter product manufacturing to achieve high Granulability Index which saves
heat energy in terms of no steam being which may have been used.
An yet further object of the present invention is to propose an improved process
of sinter product manufacturing to achieve high Granulability Index which
increases sinter production without use additional expenses or resources.
A still another object of the present invention is to propose an improved process
of sinter product manufacturing to achieve high Granulability Index which occurs
low cost of maintenance.
An yet another object of the present invention is to propose an improved process
sinter product manufacturing to achieve high Granulability Index which helps
environment Conservation and Ergonomically suitable.

SUMMARY OF THE INVENTION:
The present invention is provided with an improved process for manufacturing of
sinter product to achieve high Granulability Index comprises a preparation of
good blending in primary raw materials, limestone, plant return sinter with hot
water (70°C) nodulization of blend in a mixing nodulizing drum with an extended
retainer chamber; characterized in that mixing of blend and formation of nodules
take place in nodulizing drum and homogenization of nodules takes place in the
retainer chamber which in turn increases the Granulability Index.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING:
Fig 1 shows a graphical exposure of improvement of Granulability Index of sinter
product with modification of Mixing Nodulizing Drum.
DETAILED DESCRIPTION OF THE INVENTION:
With these above constraint identified we at sinter plant (SP#3) set about in
improving the Granulability Index (GI) of sinter plant (SP#3) base mix coming
out from the drum. For this we adopted a three-step strategy. In the First SD of
Sep-06 the inner Tega liner which had become worn out were replaced. The
lifters inside the drum for mixing was replaced and modified. In the second along
the circumference at the exit of the Mixing Nodulizing Drum (MND) a retainer
dam was fabricated for increasingly holding time of material inside the drum. In
the third step which is the primary focus of our patent application a method was
devices, fabricated and commissioned with entire inter locater and control for

extracting sensible heat from down comers to waste gas main and sinter cool by
means of water as conveying medium. The extracted heat in hot water was then
added the Mixing IModulizing Drum (MND). The process of heat extraction
involved laying of pipe lines from common clarifies water line header by means
of water flow regulating manifolds as baffles on the hot surface Wind Box down
comers. These baffles which has water flowing through extracted significant
amount of heat. A similar sensible heat extraction process was adopted for
capturing radiation heat from circular sinter cooler. The extracted heat in terms
of hot water makes its way in Mixing Nodulizing Drum (MND). A separate control
system with pneumatic control valves and mag flow meters have installed, to
control the hot water flow into Mixing Nodulizing Drum (MND) as per the process
requirement. The cumulative increase in water temperature is above 70°C.
This hot water acts as a source of heat for reactivity of lime with water for better
binding. After two cycles of PDCA this process of hot water is now fully
operational from the first week of Dec-06. There has been increase in
granulability sinter production by 100t/shift. The most remarkable achievement
has been steady improvement in Granulability Index (GI) from a lower value of
25% to an average value of 35%+. The Granulability Index (GI) 0.25 mm is also
achieved a higher value of 50%+. So after implementation of this hot water
addition system the benefit has been threefold: 1. Improve in Production. 2.
Improvement. 3. Utilization of sensible heat otherwise getting lost from sinter
cooler and waste gas main down comers.

WE CLAIM:
1. An improved process for manufacturing of sinter product to achieve high
Granulability Index comprises:
- a preparation of good blending in primary raw materials, limestone,
plant return sinter with hot water (70°C)
- nodulization of blend in a mixing nodulizing drum with an extended
retainer chamber;
characterized in that mixing of blend and formation of nodules take
place in nodulizing drum and homogenization of nodules takes place in
the retainer chamber which in turn increases the Granulability Index.
2. The process as claimed in claim 1 wherein the mixing the nodulizing drum
comprises with a retainer drum along the circumference at the exit of
Mixing Nodulizing Drum with an object to increase holding time of
material inside the drum.
3. The process as claimed in claim 1, wherein extracting of sensible heat as
carried out from down comers to waste gas main and sinter cooler to heat
water.
4. The process as claimed in claim 1 wherein the hot water acts as a source
of heat for reactivity of lime with water for better binding.
5. An improved process for manufacturing sinter product to achieve high
Granulability Index as substantially described and illustrated herein along
with accompanying drawings.

ABSTRACT

AN IMPROVED PROCESS FOR MANUFACTURING OF SINTER
PRODUCT TO ACHIEVE HIGH GRANULABILITY INDEX
The present invention is provided with an improved process for manufacturing of
sinter product to achieve high Granulability Index comprises a preparation of
good blending in primary raw materials, limestone, plant return sinter with hot
water (70°C) nodulization of blend in a mixing nodulizing drum with an extended
retainer chamber; characterized in that mixing of blend and formation of nodules
take place in nodulizing drum and homogenization of nodules takes place in the
retainer chamber which in turn increases the Granulability Index.