Field of Invention
[he present invention relates to a system for enhancement of carbon and size
segregation of sinter mix for sinter bed preparation resulting in uniform heat
generation through the sinter bed height. More particularly the invention relates to a
system comprising screen type charging means for segregation of sinter mix along
with means for providing and drawing the sinter mix. The invention particularly
relates to means for segregation of sinter mix according to size and carbon content
employing plurality of moveable rods and stiffeners with defined gaps of
progressively increased size, which comprise the screen type charging means held at a
defined angle.
Background and Prior Art
Sinter (Agglomerate) is a feed material to blast furnace in the steel industry. In the
sinter plant agglomeration of iron ore fines into a lumpy porous mass occurs by
incipient fusion i.e. sintering. In a sinter plant prepared burden i.e. proportionate
mixture of iron ore fines, flux fines, lime fines, coke breeze after balling in a balling
drum is charged to a sinter machine through inclined plate.
In such a conventional charging system segregation is not achieved as large particles
get trapped in the sinter mix and do not get a chance to go the bottom. Segregation is
defined as the ratio of wt% coarser particles at the bottom to the coarser particles at
the top or vice versa i.e.-3mm fraction at top to -3mm fraction at the bottom. This is
known as segregation index and the values should be more than 1.5 for a better
sintering process. In the conventional charging system piling up of quasi-particles
takes place in front of the inclined plate resulting in undesired segregation behaviour.
This results in non uniform generation of heat because of partial segregation of carbon
and size of sinter mix along the height of the bed, leading to a poor quality of sinter.
Thus there is need to enhance the size and carbon segregation of sinter mix to the
strand so that heat generation is uniform through the bed height and good quality
sinter is obtained.
Objects of Invention:
Thus an object of the present hivention is to provide a system for enhancement of
carbon and size segregation of sinter mix comprising screen type charging means
along with means for providing and drawing the sinter mix to the said screen.
A llirtlier object of the present invention is to provide mechanical separation of
different size particles in the sinter mix so as to achieve the smallest size particles at
the top most layer and bigger size particles at the bottom layer of the sinter bed and
high content of carbon in the top layer of sinter bed and lesser carbon content at the
bottom of the sinter bed.
Statement of Invention:
Thus according to main aspect of the present invention there is provided a system for
enhancement of carbon and size segregation of sinter mix for sinter bed preparation
resulting in uniform heat generation through the bed height and providing high quality
sinter, said system comprising:
i) means for providing sinter mix;
ii) means for drawing the sinter mix; and
iii) screen type charging means for segregation of sinter mix.
Detailed Description of Invention:
In the s\stem of the present invention the prepared burden of sinter mix is stored in a
surge hopper with small opening at the bottom. This acts the means for providing the
sinter mix. The means for drawing the sinter mix from hopper is a drum feeder fitted
with suitable drive below the hopper. The screen type charging means of the system
of present invention is so arranged to be at an angle 29 to 31 degrees . preferably 30°
to receive the sinter mix from the drum feeder for segregation of the sinter mix
This screen type charging means comprises preferably 32 number of moveable rods
and preferably 13 numbers of stiffeners/guides for passing the rods with defined gaps
between them and arranged in a manner to form an arc of radius of about 1.4 m.
These rods preferably of 20mm diameter are placed at distance ranging from 12 to 40
mm. The rods at the top are more closely spaced than those at the bottom and are
adapted to screen the particles of increasmg size. The said rods with similar spacing
are grouped together to form plurality of sections. There may be 3 to 6 sections in the
screen type charging means
The alternate rods in the system are adapted to move horizontally in opposite
directions at defined arc length kept at specific angle. The spacing between the
stiffeners is equivalent to the horizontal movement of the rods. The movement of the
rods is carried out by suitable drive assembly. The alternate rods moving in opposite
direction over comes the jamming of sinter mix with a suitable drive.
The raw materials used for the sinter mix are iron ore fines, flux fines coke breeze
fines, return fines and the like which are proportioned and mixed in mixing drum and
then balled in a balling drum by adding moisture. This mix is then provided in the
surge hopper. The mix is next drawn from the hopper by the drum feeder fitted with
suitable drive and passed through the screen type charging means. The passing of
sinter mix through the screen type charging means is carried out by simultaneous
movements of the plurality of rods in the grooves/stiffeners with defined gaps
comprising the said screen type charging means. The alternate rods move in opposite
direction driven by a suitable drive assembly. The alternate rods move horizontally in
the grooves/stiffeners at defined arc length at an angle of 29 to 31 degrees, preferably
30degrees. The rods are spaced with increasing gap between them from top to bottom
through which the sinter mix passes. Accordingly the sinter mix passes through
smallest gap between the said rods at the beginning and the largest gap at the end.
Thus the finer particles pass at the top, medium sized particles to the middle and the
biggest particles to the bottom by the movement of the rods. This results in vertical
segregation of sinter mix according to size with 40% of finer particles at top and 20%
finer particles at the bottom layer. The vertical segregation of sinter mix is achieved
by differential speed of the particles of different size acquired due to movement of the
rods. The segregated sinter mix is collected on the sintering machine pallet to form
uniform sinter bed.
The present system segregates the sinter mix in a manner such that the high content
carbon is in top layer of sinter mix forming the sinter bed. On segregation by the
system of the present invention the carbon percentage in the sinter mix varied from
4.75% to 4.26% from top to bottom
The invention is now described with reference to non- limiting accompanying
drawings
Brief Description of Accompanying Drawings
Fig. 1: Conventional System of segregation of sinter mix
Fig 2: System of present invention with screen type charging means
Fig 3 A: Segregation of Sinter mix according to size along height of sinter bed by
system of present invention
Fig 3B : Graphical representation of segregation of-3mmm fraction of sinter mix and
carbon content along height of sinter bed.
Fig 4 ; Graphical representation of segregation of sinter mix according to mean size
along the sinter bed height by system of present invention
Fig 5: Graphical representation of segregation of -3mm fraction of sinter mix by
conventional system along the sinter bed height
Fig 6: Graphical representation of segregation of -3mm fraction of sinter mix by
system of present invention along the sinter bed height
Fig 7: Graphical representation of segregation of Carbon (%) content of sinter mix by
conventional system along the sinter bed height
Fig 8: Graphical representation of segregation of Carbon (%) content of sinter mix by
system of present invention along the sinter bed height
Detailed Description Of the Accompanying Drawings
Fig 1 describes the conventional system for separation of sinter mix. It comprises
surge hopper (1), drum feeder (2), sinter mix charging chute(3). The sinter mix
charging chute is an inclined plate. There is a stabilizer plate(4) which guides the
motion of rotary drum and a suspension screw (5) for holding the inclined plane in
position. The sinter mix is fed at the top on the surge hopper and then is transferred to
the rotary drum which causes the mix to be placed on the inclined at a speed. The mix
is thus separated by the inclined plane.
Fig 2. The system of the present invention comprises surge hopper (1). drum feeder
(2), screen type charging means for segregation of sinter mix (6). The screen consists
of 32 No. of rods moving in opposite direction in the grooves/stiffeners (13 Nos) at an
arc length of 0.73 m., 1.4 m. length and angle 30 degrees. Spacing between the
stiffeners is Icept at 250mm which is equivalent to the horizontal movement of the rod.
Gap between the rods are so adjusted that the smallest gap i.e. 2mm between the rods
at the top and 40 mm gap between the rods at the bottom. Horizontal movement of
alternate rod in opposite direction in done with the help of suitable drive assembly.
The total screen was supported by 4 nos. of screen.
The screen type charging means for segregation of sinter mix is designed to handle
the sinter mi.x feed rate up to 200 TPH as per plant conditions. This system involves
one motor of 5HP and one warm reduction type gear box. 32 Nos. of stainless steel
rods of diameter 20nim along with 13 Nos. of stiffener/guides to pass the rods. The
system involves the movement of alternate rods in opposite direction to keep the rods
and guides in clean condition. Design of the system is made such that it is easier to
replace rods. The movement of rods were fixed for 250mm which is equivalent to the
gap between the two guides.
Spacing of rods are so adjusted that finer particles get screened at the beginning and
coarser later with a rod spacing from 12 to 40 mm gap in progressive increasing order.
Rod movement is done by motor connected to worm type gear box to avoid jamming
of sinter mix for a flow rate of 200 TPH. Operation of system yielded in the following
benefits. Percentage of-3mm fraction at the top is 40.8% where as in the bottom it is
20.8%.
Carbon percentage in the sinter mix varied from top to bottom i.e. 4.73% at top and
4.26% in the bottom. This help in providing uniform heat
Fig 3A provides the size separation of sinter mix on the bed height following
separation by the system of the present invention. It is evident that the top layer has
smaller particle while the bottom layer of the bed has the large sized particles. A: 15%.
B: 18 %, C:19% D: 39%. E 9% denote the amount of particles of various size range
present in the input of the sinter mix which is to be segregated.
Fig 3B provides the graphical representation of the segregation achieved by the
present invention . Tlie left hand side graph indicates the -3mm fraction along the bed
height. It is evident that the top layer has 70% and the bottom layer has 10% of the
fraction of the sinter mix. Thus the concentration of -3mm particles on top of the
sinter bed is achieved. The amount of carbon in the mix is depicted graphical in the
right hand side. It is found that in a scale of 0 to 8 the amount of carbon at the top
layer is 8 while that at bottom layer is 4.5. Thus segregation of carbon content by
present system is effective with highest amount at top and lowest at the bottom.
Fig 4 graphically demonstrates the segregation of sinter mix particles along the bed
height. It is observed that the smaller particles of 2 mm in size occupy the top layer of
the sinter bed. The larger particles are segregated at the bottom of the bed where
particles above 8mm are deposited. This indicates effective size segregation of sinter
mix particles according to size.
Fig 5 illustrates the segregation of-3mm particles in the sinter mix by conventional
methods employing systems conventionally available. It is evident that the top layer
has 28.7% of-3 mm sized particles while the bottom layer has 42%) of those particles.
Fig 6. illustrates the segregation of-3mm particles in the sinter mix employing
system and process of the present invention. It is evident that after segregation the top
layer of of the sinter bed has 47.5% of-3mm particles while the bottom layer has 25.9
% of such particles. Thus effective segregation of the -3mm particles are obtained
with more of such particles on top of sinter bed and lesser at bottom. On comparing
with fig 5 it would be evident that the segregation obtained by the system of the
present invention is better than that of conventional one. There is progressively lesser
amount of these smaller particles as we go from top to bottom of sinter bed height.
Such vertical segregation is not available by the conventional systems following
con\'entional processes. Moreover with smaller sized particles at top helps in better
and uniform heat generation.
Fig 7 demonstrates the carbon segregation obtained from the sinter mix separation by
conventional methods using conventional systems. The amount of carbon content on
top of sinter bed is 4.35% while at the bottom of the bed is 5.78%).
Fig 8 demonstrates the Carbon segregation obtained by segregation of sinter mix by
tlie present system. It is observed that after segregation of the particles according to
carbon content is achieved . The carbon content on the top layer of the sinter mix is
4.73% while that of the bottom layer is 4.26%. Thus there is a uniform segregation of
carbon from top to bottom of the sinter bed using system of present invention. This
provides uniform heat generation from the sinter mix.
We Claim
1. A system for enhancement of carbon and size segregation of sinter mix for sinter
bed preparation resulting in uniform heat generation through the bed height, said
system comprising:
means for providing sinter mix;
means for drawing the sinter mix; and
screen type charging means for segregation of sinter mix, wherein said screen *
type charging means comprises pluraUty of moveable rods and stiffeners/guides
for passing the rods with defined gaps between them.
2. A system as claimed in any preceding claim wherein the ahemate rods are
adapted to move horizontally in the grooves/stiffeners at an angle of 29 to 31
degrees, preferably 30degrees.
3. A system as claimed in any preceding claim wherein the alternate rods are
adapted to move horizontally in the grooves/stiffeners at defined arc length of
about 1.4 m
4. A system as claimed in any preceding claim wherein rods are spaced with
increasing gap between them from top to bottom adapted to screen the particles of
increasing size.
5. A system as claimed in claim 4 wherein the rods are placed at distance ranging
from 12 to 40 mm from top to bottom.
6. A system as claimed in any preceding claim wherein the said screen type charging
means comprises 32 number of moveable rods and preferably 13 numbers of
stiffeners/guides
7. A system as claimed in any preceding claim wherein the said rods with similar
spacing are grouped together to form plurality of sections.
8. A system as claimed in claim 7 wherein the rods are grouped into 3 to 6 sections.
9. A system as claimed in any preceding claim wherein the spacing between the
stiffeners is equivalent to the horizontal movement of the rods.
10. A system as claimed in any preceding claim wherein the movement of the rods is
carried out by suitable drive assembly
11. A system as claimed in any preceding claim wherein the means for providing the
sinter mix is surge hopper.
12. A system as claimed in any preceding claim wherein the means for drawing the
sinter mix from the surge hopper is drum feeder fitted with suitable drive.
13. A system as claimed in any preceding claim adapted for vertical segregation of
sinter mix according to size of 40% of finer particles at top and 20% finer
particles at the bottom layer of the sinter bed
14. A system as claimed in any preceding claim adapted for vertical segregation such
that the carbon percentage in the sinter mix varied from 4.75% to 4.26% from top
to bottom on the sinter bed.
15. A system for enhancement of carbon and size segregation of sinter mix for sinter
bed preparation resulting in uniform heat generation through the bed height
substantially as herein described with reference to the description and drawings.

A system for enhancement of carbon and size segregation of sinter mix for sinter bed
preparation resulting in uniform heat generation through the sinter bed height. The
system comprises means (1) for providing sinter mix; means (2) for drawing the sinter
mix; and screen type charging means (6) for segregation of sinter mix. The system
segregates sinter mix according to size and carbon content employing plurality of
moveable rods and stiffeners with defined gaps of progressively increased size, which
comprise the screen type charging means held at a defined angle.