SYSTEM FOR IMPROVED SEGREGATION OF CHARGE
MATERIAL OF SINTER-MIX
Field of invention
The present invention relates to a system for improved segregation of charge
material of sinter-mix. More particularly the present invention relates to a system
for segregation of charge material through a magnetic chute thereby enhancing
the sinter speed and sinter quality and reducing the consumption of solid fuel in
sintering.
Background of the invention
Research & Development Centre for Iron and Steel (RDCIS), Ranchi and
Durgapur Steel Plant (DSP), Durgapur have designed and installed an improved
segregation of charge material of sinter mix through magnetic chute at Sinter
Plant-II, DSP.
In the prior art, a specification DE2842259 describes procedure aims to an used
variety of filter stages and air separators off at as complete a separation of the
components of a solid particle mixture as possible and. This method supplies
with a separation of the individual components of the particle mixture, as far as
with this sufficient differences exist in the density and/or form; however is the
technical effort by the need of n + 1 air separators with n filter stages very high.
Thereby an economic feasibility of the method is hardly more attainable.
Another specification DE3527179 discloses a method wherein the separation is
essentially done by sieving in several stages and by a Mitstrom air separation of
the remaining fine-grained particles made. Here it is to be regarded as adverse
that multistage sieving represents the flow rate to limiting bottleneck in the
method, because to the adhesion among themselves and at the screens as well

as at the larger particles bending fine particles by all filter stages of sieving must
run. In order to guarantee a sufficient flow rate, the screens for sieving large
dimensioned must be provided, which the technical effort increased, in addition
the use of a Mitstrom air separator is required for the method, which represents a
very complicated and expensive and apparatus delicate in their operating
parameter attitudes.
The object places itself to indicate a method to that initially mentioned type which
avoids the listed disadvantages and which in particular smaller technical effort
required and so that economic is feasible, an high throughput and the processing
large particle quantities of possible, which is reliable in service, is relative simple
with which the adjustment of the process parameters and which is adaptable at
the same time flexible at different compositions of the particle mixtures which can
be processed.
Due to the low crushing index of coke breeze, the sintering temperature of top
layer of sinter bed remain low resulting inadequate heat quantity to the top layer.
Moreover operating at higher bed height leads to higher bulk density of bottom
layer which in turn reduces the bed permeability, machine speed and finally
affects the productivity of sinter machine. In order to make the favorable
condition of low temperature sintering, it is necessary to bring low melting
components such as return-sinter and mill scales of the charge material to top
layer of sinter bed by suitable segregation method. In this necessity, a magnetic
plate based sinter mix charging system was designed, developed and installed at
SP-II, DSP.
Objects of the invention
Segregation of low-melting sinter raw-materials such as return sinter and mill
scales from the remaining charge materials of sintering to bring to the top layer of
the sinter bed through introduction of magnetic field on the segregation chute of

sinter machine, in order to improve the top layer yield of sinter bed. The low
melting, mill scales and return sinter at the top of the sinter bed shall improve
significantly the quality and productivity of sinter, through improvement in air
filtration velocity across the width of pallets. This resulted in increase in machine
speed even at higher bed height. The quality of pallet sinter also improved w.r.t.
tumbler index.
Therefore such as herein described a system for improved segregation of charge
material of sinter-mix comprising of: a raw mix charging hopper; a drum feeder;
and a charging chute including a mother plate, a magnetic plate and a protective
cover.
As per one of the embodiment of the present invention a plate magnet (Ferrite
permanent magnet) is provided by arranging small individual pieces of magnets
placing in rows and columns.
As per another embodiment of the present invention the strength of the magnetic
plate is set to a optimum value on the basis of laboratory testing on the raw
charge material and simulating the actual flow pattern on a pilot scale model.
As per yet another embodiment of the present invention, the induced magnetic
force applied on the surface of the segregation chute is configured for
segregating the return-sinter and mill-scales from the remaining charge mix, by
reducing their dropping velocity.
As per one of exemplary embodiment of the present invention, a honeycomb
structure made of stainless steel is designed to accommodate number of
individual magnetic pieces, facilitating easy removal and fixing of individual
pieces of magnets at in-situ position to modify the magnetic field area according
to the process requirement.

Further embodiment of the present invention is to provide a magnetic chute,
which is on top surface of the existing mild steel base plate installed through
quick operated fixtures, for easy maintenance approach.
Yet another embodiment of the present invention is to provide a non-magnetic
stainless steel liner with hard faced coating on top of its surface, over the top of
the magnetic plate.
Brief description of the accompanying drawing
Fig 1 illustrates the basic working diagram of the system in accordance with the
present invention;
Detailed description
Poor crushing index of coke breeze in the charge material of sintering creates the
sintering temperature of top layer of sinter bed remain low resulting inadequate
heat quantity to the top layer. Moreover operating at higher bed height leads to
higher bulk density of bottom layer which in turn reduces the bed permeability,
machine speed and finally affects the productivity of sinter machine. In order to
make the favorable condition of low temperature sintering, it is necessary to bring
low melting components such as return-sinter and mill scales of the charge
material to top layer of sinter bed by an improved segregation method.
Considering the necessity, a permanent magnet based segregation chute was
designed and developed.
By introducing magnetic field on top surface of the segregation chute, the falling
velocity of the charge mix is reduced considerably, and thus increases the void
fraction in the sinter bed. At the same time it also segregate the para-magnetic
particles, such as return sinter and mill scales of the charge mix, which are easily
attracted by magnet, to the upper layer of the sinter bed. The coalescence of

pore is accelerated by the improvement of melt fluidity with the blending of return
sinter and mill scale.
It is found that applying a magnetic field to the charge sinter mix during charging
in to the pallet, increases the FeO content at the top of sinter bed. This is
attributed to the fact that return sinter and mill scale particles are easily attracted
by magnet 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 and magnetite which are strongly magnetic
substances. Due to the differences in magnetic properties of raw materials in
sinter mix, the falling trajectory of sinter mix got dispersed. Hence the void
fraction in the sintering bed is increased by a spread in the falling area and return
fine and mill scale are segregated to the upper layer.
A permanent type magnet of approximately same size to the base plate of the
segregation chute was fabricated and fitted on the top surface of the base plate
of the chute to induce magnetic force on the charge materials while they
dropping down through the chute.
The magnetic plate based segregation chute at Sinter Plant - II, DSP was
designed, developed and installed considering the following input data:



In the newly installed magnetic plate system, the polyurethane liners provided
earlier at the top of the existing base plate of the segregation chute was removed
and the "Magnetic plate" was installed on its place.
The "Magnetic plate" of overall size of 2800 mm x 1300 mm (approx) was made
by arranging numbers of individual magnetic pieces of size 900 mm x 156 mm
each in 3 columns x 7 rows. A honeycomb designed structure made of stainless
steel was developed in 3 x 7 matrix format to hold the individual magnetic pieces.
The honeycomb designed structure facilitates easy removal & fixing of magnetic
pieces in-situ condition.
The total magnets assembly was covered by stainless steel sheet enclosure. The
magnetic plate was installed at the middle of the existing base plate of the
segregation chute by leaving around 250 mm space at the top and bottom, along
the width of the base plate. The G.A of the installed magnetic plate installed on
the top of the base plate of segregation chute is depicted in Fig-1.
On the top of the magnetic plate, 10 mm thick SS-304 liner plate was provided to
prevent the magnets from direct contact with the charge materials to increase its
service life. Additionally the top surface of SS liner was hard faced with chemical
coating for 2 mm thick. The overall dimensions of the SS 304 liner plate was
matched with the existing base plate, so that the magnetic plate sandwiched
between the liner plate and the base plate is well protected against the charge
material.

Liner Plate
Stainless Steel liner plate is installed on the top of the magnetic plate to ensure
protection against direct contact from the charge sinter-mix. The size of the liner
plate is maintained similar to the base plate of the segregation chute.
The SS liner plate is vertically parted in 3 pieces, length wise for easy handling
during maintenance and replacement. The liner plates shall form the top most
part of the magnetic segregation chute assembly.
The liner plate fitted on the top of the magnetic plate and base plate assembly
forms the magnetic plate based segregation chute.


Highlight of the innovations
> A plate magnet (Ferrite permanent magnet) of approximate size 2800 mm
(width) x 1200 mm (height) x 40 mm (thick) was made by arranging small
individual pieces of magnets of size 900 mm x 156 mm in 3 columns x 7 rows.
The overall size of the magnetic plate was estimated considering covering as
much as possible surface area of the existing base plate (mother plate) and
existing space constraints.
> The strength of the magnetic plate was arrived at 850 + 50 gauss on the basis
of laboratory testing on the raw charge material and simulating the actual flow
pattern on a pilot scale model.
> The induced magnetic force on the surface of the segregation chute is
segregates the return-sinter and mill-scales from the remaining charge mix, by
reducing their dropping velocity. This magnetized segregation facilitates the
return-sinter and the mill-scales to form the top layer of the sinter bed. As the
magnetic force does not affect the other constituents of charge mix, they are
dropping freely and reaches the bottom of the sinter bed. The other constituents
of charge materials are normally consist of iron ore, limestone etc.
> A honeycomb designed structure of 3 x 7 matrix made of stainless steel to
accommodate 21 nos. of individual magnetic pieces, facilitating easy removal
and fixing of individual pieces of magnets at in-situ position to modify the
magnetic field area according to the process requirement.
> The arrangement of individual magnetic pieces by maintaining a suitable
polarity of magnetic field, which needs to facilitate the material flow towards
downwards in to the pallet.

> The location of the magnetic chute, which is on top surface of the existing mild
steel base plate installed through quick operated fixtures, for easy maintenance
approach. This particular location of the magnetic plate on top surface of the
base plate facilitates the existing slope variation mechanism and bed height
changing arrangements of the base plate to operate freely as earlier.
> The non-magnetic stainless steel liner with hard faced coating on top of its
surface, provided on the top of the magnetic plate shall act as a protective cover
to the magnets, which can be easily replaced if required.
Techno-economic benefits
The new system of magnetic segregation chute was subjected to industrial trials,
which was conducted before and after installation of magnetic plate charging
system. Trials were carried out to estimate some performance evaluation
parameters such as 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 etc.
The following are the analysis of the trials:
• The average air filtration velocity has improved from 0.32 m/s to 0.41 m/s and
is more uniform across the width of sinter bed.
• The sinter machine speed has improved from 2.25 m/min to 2.40 m/min with
bed height of 600 mm.
• The tumbler index (Tl) has improved from 72.2 to 75.9
• -5mm sized finished sinter has reduced from 8.9 to 6.5%

• The FeO in sinter mix of top layer of sinter bed increased by 1.0 % w.r.t sinter
mix from drum feeder
Although the foregoing description of the present invention has been shown and
described with reference to particular embodiments and applications thereof, it
has been presented for purposes of illustration and description and is not
intended to be exhaustive or to limit the invention to the particular embodiments
and applications disclosed. It will be apparent to those having ordinary skill in the
art that a number of changes, modifications, variations, or alterations to the
invention as described herein may be made, none of which depart from the spirit
or scope of the present invention. The particular embodiments and applications
were chosen and described to provide the best illustration of the principles of the
invention and its practical application to thereby enable one of ordinary skill in the
art to utilize the invention in various embodiments and with various modifications
as are suited to the particular use contemplated. All such changes, modifications,
variations, and alterations should therefore be seen as being within the scope of
the present invention as determined by the appended claims when interpreted in
accordance with the breadth to which they are fairly, legally, and equitably
entitled.

Claims:-
1. A system for improved segregation of charge material of sinter-mix comprising
of:
a raw mix charging hopper;
a drum feeder; and
a charging chute including a mother plate, a magnetic plate and a protective
cover.
2. A system for improved segregation of charge material of sinter-mix as claimed
in claim 1, wherein the magnetic plate is sandwiched between the mother plate
and the protective cover.
3. A system for improved segregation of charge material of sinter-mix as claimed
in claim 1, wherein the magnetic plate is made by arranging small individual
pieces of magnets of size 900 mm x 156 mm each in 3 columns x 7 rows.
4. A system for improved segregation of charge material of sinter-mix as claimed
in claim 1, wherein the strength of the magnetic plate is at 850 + 50 gauss.
5. A system for improved segregation of charge material of sinter-mix as claimed
in claim 1, wherein the induced magnetic force on the surface of the segregation
chute is configured for the segregation of the return-sinter and mill-scales from
the remaining charge mix, by reducing their dropping velocity.
6. A system for improved segregation of charge material of sinter-mix as claimed
in claim 1, wherein the magnetized segregation facilitates the return-sinter and
the mill-scales to form the top layer of the sinter bed and does not affect the other
constituents of charge mix as they drop freely and reaches the bottom of the
sinter bed.

7. A system for improved segregation of charge material of sinter-mix as claimed
in claim 1, wherein the magnetic plates comprises a honeycomb designed
structure of 3x7 matrix made of stainless steel to accommodate 21 nos. of
individual magnetic pieces, facilitating easy removal and fixing of individual
pieces of magnets at in-situ position.
8. A system for improved segregation of charge material of sinter-mix as claimed
in claim 7, wherein the arrangement of individual magnetic pieces maintains a
polarity of magnetic field, which facilitates the material flow towards downwards
in to the pallet.
9. A system for improved segregation of charge material of sinter-mix as claimed
in claim 1, wherein the location of the magnetic plate on top surface of the
mother plate facilitates the existing slope variation mechanism and bed height
changing arrangements of the base plate to operate freely as earlier.
10. A system for improved segregation of charge material of sinter-mix as
claimed in claim 1, wherein the charging chute comprises a non-magnetic
stainless steel liner with hard faced coating on top of its surface, provided on the
top of the magnetic plate act as a protective cover to the magnets.

The present invention relates to a system for improved segregation of charge
material of sinter-mix comprising of a raw mix charging hopper; a drum feeder ;
and a charging chute including a mother plate, a magnetic plate and a protective
cover.