FIELD OF THE INVENTION
The present invention relates to a sinter mix charging system for sinter machine adapted
to enhance productivity and yield. More particularly, the present invention is directed to
charging system for sinter machine including atleast one of (i) Magnetic Braking Feeder
(MBF) and Magnetic Dispersing Feeder (MDF). The charging system of the invention is
adapted to accelerate the process of pore coalescence during sintering through the
enhancement of melt fluidity with the blending of return sinter and mill scale. The system
and method of sinter mix charging in sintering machine according to the invention favour
enhancing sinter machine speed, increased air filtration velocity, increased productivity
with reduced solid fuel consumption and thus favouring prospect of wide scale
application/installation of such system in sintering machines in large steel plants with
significant cost advantage.
BACKGROUND ART
Conventional charging system for sinter plant of the applicants had a charging system
comprising 3 piece sector gate, drum feeder, deflector plate and segregation plate. The
segregation plate consisted of mild steel as mother plate. Over the mild steel plate
polymer liners were installed. There was no segregation plate cleaning device and
cleaning was done manually. Control of loading of sinter mix on pallet was done by angle
of repose system. The loading of the system was not a free fall one. The thickness of
sinter mix on segregation plate is around 350 mm and the segregation plate angle is 57°.
A number of disadvantages were observed in such traditional charging system in the
sinter plant which needed improved system to overcome the problems. It was observed
that a sinter machine with an area of 180 m2 achieved a production rate of 225.18 t/h
with a suction level of 1203 mmwc. This sinter plant achieved comparatively much lower
productivity than the internationally achieved productivity levels. The coke crushing index
has been reported to 72 - 77 % against the internationally achieved value of 90 %. The
suction value was also much lower than the international levels of 1700 - 2000 mmwc.
Lime addition rate was 6 kg/t of sinter whereas high performing sinter plants use 20-25
kg/t of sinter. It was also observed that +10 mm in ore fines are 8-10 %. On the other
hand, internationally -5 mm ore fines are used.

For the improvement of productivity and yield in the downdraft sintering process, the
control of void fraction in the sintering bed and the increase of the sinter yield in the
upper layer are important. A number of charging devices for the sinter mix have been
developed to date in order to improve sinter machine productivity. However, their effect
is limited to vertical size segregation of the sinter mix and they are not effective in
segregating raw materials with the same size such as return sinter and mill scale.
There has been thus a need in the art to developing a sinter machine charging system
that would enable faster and complete sintering of the charge on sinter bed to improve
the productivity and yield. The charging system would ensure segregating iron bearing
feed to the top layer of the sinter bed, increase in void fraction of sinter bed and thus
higher suction head, allow use of finer ore fines, enhancing melt fluidity to thereby
increase the productivity and yield of the sinter plant. In order to improve the production
rate and to reduce the solid fuel consumption, magnetic segregation plate based sinter
mix charging system has been proposed by way of the present invention.
OBJECTS OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided for sinter
machine charging system adapted to accelerate the process of pore coalescence during
sintering through the enhancement of melt fluidity with the blending of return sinter and
mill scale.
Another object of the present invention is thus directed to providing a magnetic braking
feeder based sinter mix charging system for sinter machines adapted to improve the
productivity and yield of the plant.
Another object of the present invention is directed to providing a magnetic braking feeder
based sinter mix charging system which would selectively charge the constituents in the
mix under influence of magnetic field such as the return sinter fines, mill scale, coke and
the iron ore fines in a manner that the iron bearing fractions e.g. the return fines and the
mill scales go to the upper layer of the sinter bed.
Yet another object of the present invention is directed to providing a magnetic braking
feeder based sinter mix charging system which would favour increasing the void fraction
of the sinter charge on sinter bed.

A further object of the present invention is directed to providing a magnetic braking
feeder based sinter mix charging system for sinter machine which would ensure
increased uniform air filtration velocity and enhanced suction across the sinter bed.
A still further object of the present invention is directed to providing a magnetic braking
feeder based sinter mix charging system for sinter machine wherein power consumption
is not increased due to use of permanent magnets in the charging system.
A still further object of the present invention is directed to providing a magnetic braking
feeder based sinter mix charging system which would favour increased sinter machine
speed.
A still further object of the present invention is directed to providing a magnetic braking
feeder based sinter mix charging system which would favour achieving enhanced melt-
fluidity during sintering.
SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided a sinter
charging system for sinter machine comprising:
means adapted for application of magnetic field to the sinter mix during charging such as
to reduce the falling velocity of the sinter mix and /or disperse the falling sinter mix by
generation of magnetic field to the sinter mix during charging.
A further aspect of the present invention is directed to a sinter charging system wherein
said means adapted for application of magnetic field comprises at least one of (i)
Magnetic Braking Feeder (MBF) and Magnetic Dispersing Feeder (MDF).
A still further aspect of the present invention is directed to a sinter charging system
wherein said Magnetic Braking Feeder (MBF) comprises magnetic plates preferably fitted
at the back side bottom of the segregation chute sinter mix charging system whereby the
falling velocity of the mix gets reduced by the magnetic breaking effect which in turn

increases the void fraction in the sinter bed while at the same time the strongly magnetic
materials including return sinter and mill scale get segregated to the upper layer.
A still further aspect of the present invention is directed to a sinter charging system
wherein said Magnetic Dispersing Feeder( MDF) comprises magnet mounted inside the
drum feeder and adapted to apply magnetic force to the sinter mixture during charging
whereby due to the difference in magnetic properties of raw materials in sinter mix ,the
falling trajectory of sinter mix gets dispersed and thus the void fraction in the sintering
bed increases by a spread in the falling area and the return fine and mill scale get
segregated to the upper layer.
A still further aspect of the present invention is directed to a sinter charging system
comprising magnetic segregation plate assembly comprising of individual magnetic
pieces, fixed in appropriate rows and columns and enclosed all around by stainless steel
enclosure.
A still further aspect of the present invention is directed to a sinter charging system
wherein said enclosure comprises top SS 304 liner plate of about 10 mm thick provided
with surface coating at top surface with smooth finish, the SS 304 liner plate providing
protection to the magnetic plate assembly and the uncovered portion of the existing base
plate against wear & tear by abrasion of the material flow, the overall thickness of the
magnetic plate segregation chute assembly (excluding the existing base plate) being
about 55 mm.
A still further aspect of the present invention is directed to a sinter charging system
wherein the magnetic plate segregation chute was installed at the top and middle of
existing mother plate of the sinter charging system leaving around 250 mm space at the
top and bottom, along the width of the mother plate, the SS304 surface coated liner
plate of same size as that of the mother plate was installed above the magnetic plate
enclosure with polymer liners installed on the inner sides of the existing mother plate.
According to a further aspect of the present invention is directed to a downdraft sintering
process involving the sinter charging system as described above comprising controlling
the void fraction in the sinter bed and increasing the sinter yield in the upper layer.
A still further aspect of the present invention is directed to said downdraft sintering
process wherein the void fraction in the sintering bed is increased by soft landing and

segregating the return sinter and mill scale to the upper layers and enhancing the melt-
fluidity during sintering.
The objects and advantages of the present invention is described in greater details with
reference to the following accompanying non limiting illustrative drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Figure 1: is the illustration of the conventional charging system for sinter machine
involving segregation plate and drum feeder.
Figure 2: is the graphical plot of magnetic characteristics showing the magnetic
behaviour of constituents of sinter mix in an applied magnetic field.
Figure 3: is the illustration of the magnetic braking feeder based sinter mix charging
system for improved productivity of sinter machine according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING FIGURES
The present invention relates to a magnetic braking feeder (MBF) based sinter mix
charging system adapted to enhance the productivity of sinter machine.
Accompanying Figure 1 illustrates the conventional sinter mix charging system
consisting of 3 piece sector gate, drum feeder, deflector plate and segregation plate.
The segregation plate consists of mild steel as mother plate. Over the mild steel plate
polyurethane liners are installed. There was no segregation plate cleaning device and
cleaning was done manually. Control of loading of sinter mix on pallet was done by angle
of repose system. The loading of the system was not a free fall one. The thickness of
sinter mix on segregation plate is around 350 mm and the segregation plate angle is 57°.
This sinter plant achieved comparatively much lower productivity than the internationally
achieved productivity levels.

For the improvement of productivity and yield in the downdraft sintering process, the
control of void fraction in the sintering bed and the increase of the sinter yield in the
upper layer are important. A number of charging devices for the sinter mix have been
developed to date in order to improve sinter machine productivity. However, their effect
is limited to vertical size segregation of the sinter mix and they are not effective in
segregating raw materials with the same size such as return sinter and mill scale.
In order to improve the production rate and to reduce the solid fuel consumption,
magnetic plate sinter mix charging system has been introduced by way of the present
invention. This system increases the void fraction in the sintering bed achieving a soft
landing and the return sinter and mill scale get segregated to the upper layers and also
enhances the melt fluidity during sintering operation.
The MBF technology works on the principle of reduction of the falling velocity of sinter
mix. In MBF, magnetic plates are fitted at the back side bottom of the segregation chute
sinter mix charging system. The falling velocity of the mix gets reduced by this magnetic
braking effect, which in turn increases the void fraction in the sinter bed. At the same
time strongly magnetic materials such as return sinter and mill scale gets segregated to
the upper layer. The process of pore coalescence gets accelerated through the
enhancement of melt fluidity with the blending of return sinter and mill scale.
Application of magnetic field to the sinter mix during charging also increases FeO content
at the top (about 100 mm) of sinter bed. This is attributed to the fact that return sinter
and mill scale particles are easily magnetized in comparison with iron ore, coke and other
sinter mix constituents. This is because return sinter contains magnetite and calcium
ferrite and mill scale contains metallic iron which is strongly magnetic substances.
Accompanying Figure 2 graphically shows the magnetic characteristics of different
constituents of raw materials of sinter charge in a magnetic field.
According to an embodiment of magnetic braking based sinter mix charging system for
sinter machine of the present invention as illustrated in accompanying Figure 3, the
magnetic segregation plate assembly consists of individual magnetic pieces, fixed in
appropriate rows and columns and enclosed all around by SS 304 enclosure.

The top SS 304 liner plate of 10 mm thick is provided with surface coating at top surface
with smooth finish. The SS 304 liner plate ensures protection to the magnetic plate
assembly and the uncovered portion of the existing base plate against wear & tear by
abrasion of the material flow. The overall thickness of the magnetic plate segregation
chute assembly (excluding the existing base plate) is 55 mm. Based on field trials the
maximum magnetic strength that can be achieved with 1 inch magnet is about 1200
gauss (gap-5 mm) and depending on actual dynamic loading conditions prevailing in
sinter plant, magnetic strength of 900 - 1000 gauss is selected for optimum
performance.
The magnetic braking feeder based sinter mix charging system has been installed with
the existing polyurethane liners being removed. The magnetic plate segregation chute
has been installed at the top and middle of the existing mother plate leaving around 250
mm space at the top and bottom, along the width of the mother plate. The SS304
surface coated liner plate of same size as that of the mother plate has been installed
above the magnetic plate enclosure. Polyurethane liners have been installed on the inner
sides of the existing mother plate.
Trials have been conducted before and after installation of magnetic plate charging
system for estimation of -5 mm and tumbler index of sinter, air filtration velocity of
sinter bed, FeO analysis of sinter mix from drum feeder and top layer of sinter bed and
study of pallet sinter before and after installation of magnetic plate charging system. The
following are the observations based on analysis of the said trials:
(i) The average air filtration velocity has been improved from 0.32 m/s to
0.41m/s and the air filtration velocity is also more uniform after installation
of magnetic plate charging system compared to before installation,
(ii) The sinter machine speed has been increased from 2.25 m/min to 2.40
m/min with bed height of 600 mm.
(iii)The tumbler index and -5mm of finished sinter has also been improved
from 72.2 to 75.9 and from 8.9 to 6.5% respectively after installation of
system.
(iv)The FeO in sinter mix of top layer of sinter bed has been increased by 1.0
% w.r.t sinter mix from drum feeder after installation of magnetic plate
charging system.

(v) The pallet sinter study reveals that the tumbler index of pallet sinter has
also been improved.
(vi)Production rate increased from 219.5 t/hr to 235.2 t/hr.
Utilization of the above described magnetic braking feeder based sinter mix charging
system according to the invention resulted in increase in productivity by 8% for the
sinter machine. The sinter yield in the upper layer shows a remarkable improvement and
total yield also shows an improvement of approximately 2%.
According to an alternative embodiment, charging devices for the sinter mix using
magnetic force is based on magnetic dispersing feeder (MDF) wherein the magnet is
mounted inside the drum feeder and applies magnetic force to the sinter mixture during
charging. Due to the differences in magnetic properties of raw materials in sinter mix,
the falling trajectory of sinter mix gets dispersed. Hence the void fraction in the sintering
bed is increased by a spread in the falling area and therefore, return fine and mill scale
are segregated to the upper layer.
It is thus possible by way of the present invention to developing a magnetic braking
feeder based sinter mix charging system for sinter machine that would ensure
segregating iron bearing feed such as the return fines and the mill scales to the top layer
of the sinter bed, increase in void fraction of sinter bed and thus higher suction head,
allow use of finer ore fines, enhancing melt fluidity to thereby increase the productivity
and yield of the sinter plant. Thus in order to improve the production rate and to reduce
the solid fuel consumption in sinter machines, magnetic segregation plate based sinter
mix charging system provides a viable and cost effective solution with prospect of wide
industrial application.

We Claim:
1. A sinter charging system for sinter machine comprising:
means adapted for application of magnetic field to the sinter mix during charging such as
to reduce the falling velocity of the sinter mix and /or disperse the falling sinter mix by
generation of magnetic field to the sinter mix during charging.
2. A sinter charging system as claimed in claim 1 wherein said means adapted for
application of magnetic field comprises at least one of (i) Magnetic Braking Feeder (MBF)
and Magnetic Dispersing Feeder( MDF).
3. A sinter charging system as claimed in claim 2 wherein said Magnetic Braking Feeder
(MBF) comprises magnetic plates preferably fitted at the back side bottom of the
segregation chute sinter mix charging system whereby the falling velocity of the mix gets
reduced by the magnetic breaking effect which in turn increases the void fraction in the
sinter bed while at the same time the strongly magnetic materials including return sinter
and mill scale get segregated to the upper layer.
4. A sinter charging system as claimed in claim 2 wherein said Magnetic Dispersing
Feeder( MDF) comprises magnet mounted inside the drum feeder and adapted to apply
magnetic force to the sinter mixture during charging whereby due to the difference in
magnetic properties of raw materials in sinter mix, the falling trajectory of sinter mix
gets dispersed and thus the void fraction in the sintering bed increases by a spread in the
falling area and the return fine and mill scale get segregated to the upper layer.
5. A sinter charging system as claimed in anyone of claims 1 to 4 comprising magnetic
segregation plate assembly comprising of individual magnetic pieces, fixed in appropriate
rows and columns and enclosed all around by stainless steel enclosure.
6. A sinter charging system as claimed in claim 5 wherein said enclosure comprises top
SS 304 liner plate of about 10 mm thick provided with surface coating at top surface with
smooth finish, the SS 304 liner plate providing protection to the magnetic plate
assembly and the uncovered portion of the existing base plate against wear & tear by
abrasion of the material flow, the overall thickness of the magnetic plate segregation
chute assembly (excluding the existing base plate) being about 55 mm.

7. A sinter charging system as claimed in claim 5 wherein the magnetic plate segregation
chute was installed at the top and middle of existing mother plate of the sinter charging
system leaving around 250 mm space at the top and bottom, along the width of the
mother plate, the SS304 surface coated liner plate of same size as that of the mother
plate was installed above the magnetic plate enclosure with polymer liners installed on
the inner sides of the existing mother plate.
8. A downdraft sintering process involving the sinter charging system as claimed in
anyone of claims 1 to 7 comprising controlling the void fraction in the sinter bed and
increasing the sinter yield in the upper layer.
9. A downdraft sintering process as claimed in claim 8 wherein the void fraction in the
sintering bed is increased by soft landing and segregating the return sinter and mill scale
to the upper layers and enhancing the melt-fluidity during sintering.
10. A sinter charging system for sinter machine and downdraft sintering process
involving the same substantially as herein described and illustrated with reference to the
accompanying examples/figures.

The present invention relates to a sinter mix charging system for sinter machine adapted
to enhance productivity and yield. More particularly, a magnetic braking feeder based
sinter machine charging system is disclosed which reduces the falling velocity of the mix
by magnetic braking effect, which in turn increases the void fraction in the sinter bed.
Moreover, the charging system segregates the magnetic materials such as return sinter
and mill scale to the upper layer during down draft sintering process. This accelerates the
process of pore coalescence during sintering through the enhancement of melt fluidity
with the blending of return sinter and mill scale. The system and method of sinter mix
charging in sintering machine according to the invention favour enhancing sinter machine
speed, increased air filtration velocity, increased productivity with reduced solid fuel
consumption and thus favouring prospect of wide scale application/installation of such
system in sintering machines in large steel plants with significant cost advantage.