FIELD OF THE INVENTION
The present invention relates to iron ore sintering process and sintering machine and ,in
particular, to iron ore sinter manufacture and system therefore which would enable faster
sintering speed and increase in productivity sintering machine. Importantly, the process of
sintering and the system provided is adapted to increase the burn through point temperature
and also thereby improve the productivity of sintering machines.
BACKGROUND ART
It is welknown that sinter is produced from finely divided iron ore, which is roasted with coke
and lime by incipient fusion. Usually, such iron ore sinter is produced in sintering machines.
The productivity of sintering machine i.e. the speed of sintering depends on three basic
parameters, which indude (i) volumetric airflow rate (m3/min.), (ii) heat capacity of gas and
(iii) the heat capacity sinter mix involved. It is well known that normally the productivity of
sintering machines are increased by increasing of volumetric flow rate by increased suction
below grate and reduction of bed resistance, preferably by lowering of bed height and
improving the average grain size of the sinter mix partides.
It would be apparent from the above that apart from the increase in the volumetric airflow
rate and the selective use of sinter mix, the heat capacity of gas also plays an important role
in the speed of sintering in a sintering machine. While the volumetric flow rate can be
increased by increasing suction below grate and the reduction of bed resistance and is
conventionally followed the need for further improving the sintering speed is always found to
be desirable to improve the productivity of the sintering machine. Also, the sinter mix while
contributing to the productivity is not always within the desired constitution to favour the
increase of speed of sintering machine and in turn benefit improved productivity.
OBJECTS OF THE INVENTION
It is the basic object of the present invention to provide for a process for sintering to produce
the iron ore sinter which would favour increasing the heat capacity of the air /gas and
thereby facilitate increasing the vertical speed of sintering.
Another object of the present invention is to provide for a simple and cost effective manner of
increasing the heat capacity of gas / air in a sintering process/machine whereby the speed of
sintering can be improved and also the productivity of sintering machine increased to the
desired extent.
Yet further object of the present invention is directed to a system for sintering iron ore which
would be adapted for increasing the heat capacity of air / gas and in tum also increase in the
vertical speed of sintering.
Yet another object of the present invention is directed to a simple and cost effiective system
of sintering of iron ore which would enable user friendly application and use of sintering
machine by increasing the speed of sintering and also the productivity of the system.
SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided a process for
sintering iron ore adapted for faster sintering comprising:
providing the desired sinter mix in a sinter machine;
providing volumetric air flow through the sinter bed ; and
increasing the heat capacity of the air during sintering by humidification of air by steam
injection.
In the above process for sintering iron ore the humidification of air by steam injection is
carried out in the selected locations of the sintering machine. Preferably, the humidification of
air by steam injection is carried out in the selected location of the sintering machine such that
hot zone (>600°C width at the discharge end is reduced to take care of high FeO sintering
operations. The steam is injected into sinter bed by transverse rows of sprays preferably
through nozzles into the sinter bed in the location 50% to 65% length of the machine from
the charging side. In particular, the steam spray is sucked into the sinter bed by the suction
created in the wind boxes.
Thus in the above process for sintering of iron ore a mixture of steam and air is sucked
through the bed whereby the humidity of the air is increased to about 60 gm/Nm3 in the
localized zone.
Preferably, the location of injection of steam is selectively at the zone where the sinter
process speed is minimum (volumebric flow of air through the zone is minimum) such that the
hot zone (>600°C) width extension is restricted.
Thus in the above process extension of the hot zone wklth is controlled such that the air flow
through 65 to 100% (from the charging side) is improved due to the lesser resistance of
sinter bed. Importantly, the bum through point temperature, waste gas temperature at the
last wind box of sinter machine is increased to preferably 390°C. from 370°C.
In accordance with another aspect of the present invention there is provided an iron ore
sintering machine for carrying out the above process for sintering iron ore adapted for faster
sintering comprising:
a sinter bed for carrying the sinter mix;
means for volumetric flow of air through the sinter bed;
means for injecting steam into sinter bed through nozzles in the selected locations of the
sinter machine for increasing the heat capacity of the air/gas for faster sintering.
The above disdosed sinter machine of the invention thus comprises nozzle means to inject
steam into the sinter bed by transverse rows of sprays into the sinter bed in the location
preferably at the zones where the sinter process speed is minimum more preforably at about
50% to 65% length of the machine from the charging side.
In particular, the system is adapted such that the steam spray is sucked into sinter bed by
the suction created in the wind boxes.
In accordance with an embodiment, the sinter machine of the invention thus comprises pipes
of diameter about 50 mm are laid across the wridth of pallet with the arrangement of flange
joint in one side and resting on strand on the other preferably about five numbers of parallel
pipes are provided across the width at locations of 50 to 65 % length of the machine from the
charging side.
It is thus possible by way of the above disclosed manner of producing iron ore sinter in a
sintering machine /system which would enable increasing the heat capacity of gas / air by
steam injection which in tum would fovour increasing the speed of sintering and the
productivity of the sintering plant.
It is found by way of the present invention that by way of the above disclosed selective
humidification of air by steam injection, the heat capacity of air can be increased which in
tum would fovour increasing the speed of sintering. Importantly, by selective humidlfication
of air by steam injection in the specified location of the sinter machine, hot zone (>600°C)
width at the discharged end is reduced to take care of situation of high FeO sintering
operation.
Preferably, in accordance with an aspect of the invention the steam is injected into the sinter
bed by transverse rows of sprays into the sinter bed in the kxatkm 50% to 65% length of the
sintering machine from the charging side. The steam spray is sucked into the sinter bed by
the suction created in the wind boxes.
Usually, in case of conventional sintering process only atmospheric air is sucked into the
sinter bed and it is proposed by way of present invention to carry out the sintering in a
sintering machine / system adapted such that a mixture of steam and air can be sucked
through the sinter bed. In such manner of sintering involving the injection of steam along
with air, it is possible to increase the natural humidity of the air in a localized zone within the
sinter machine and thereby increase the heat capacity of the air. In particular, usually the
natural humidity around the air is in the range of 10-30 gm. / Nm3. Following the process of
steam injection in the sintering machine in accordarnce with the present invention, It is
possible to increase the humidity of air to about 60gm / Nm3 in the required localized zone of
the machine. In such manner of injection of steam into the sintering bed the invention
achieves increasing the required heat capacity of the air in the sintering process. Importantly,
such increase in the heat capacity favours increasing the vertical sintering speed from
19.35mm to 20.1mm. and in turn the productivity of sintering machine / system.
In accordance with the another aspect of the present invention in order to achieve effective
humidification of air by steam, injection to improve the heat capacity of the air the
humidification of air by steam injection is selectively attended in specified location of sintering
machine, hot zone wkith at the discharge end being reduced to take care of situation of high
FeO sintering operation. Preferably, the location of the injection of steam is selected at the
zone where the sinter process speed is minimum i.e. the volumetric flow of the air through
the zone is minimum such that the hot zone (>600°C) width extension is restricted.
Considering that the extension of the hot zone width is thus controlled, the air flow through
about 65 to 100% from the charging side would also be improved due to lesser resistance of
sinter bed.
The details of the invention, its objects and advantages are explained in greater details in
relation to the non-limiting following accompanying figure of the air humidification system in
sinter machine in accordance with the present invention.
BRIEF DESCRIPTION OF ACCOMPANYING FIGURE
Figure 1: is a plan view of sinter machine bed adapted for humidification of air by injection in
accordance with the present invention.
Reference is invited to figure 1 which shows a plan view of the sinter machine bed provided
with air humidification facility.
As apparent from figure 1, the humidification of air is achieved by injecting steam into sinter
bed (SB) through nozzles (NZ) provided in the pipe (PI). The pipe (PI) can be of diameter of
about 50mm which is laid across the width of the pallet with the arrangement of the flanged
joint in one side and resting on strand on the other so that in case of shut down or
maintenance the pipe can be easily re-located. Preferably, five numbers of parallel pipes as
illustrated in the embodiment of the figure 1 are provided across the width at location of 50-
65% length of machine from the charge side.
It is thus possible by way of the above arrangement of steam injection in the sintering bed to
increase the humidity of air from its natural range of about 10-30 gm / Nm3 to 60 gm/Nm3 in
the localized zone. The heat capacity of the air could be increased by such injection of steel in
the bed. The location of the injection of the steel is preferably selected at the zone where the
sinter process speed is minimum i.e. volumetric flow in the air is minimum and in the process
the hot zone width extension is restricted.
Importantly, the test trials carried out in sinter plants involving the above air humidification
system and its comparative study with conventional sinter plant performance (without steam
injection) has confirmed that by way of air humidification by steam in sinter plant in
accordance with the invention it is possible to increase the heat capacity of the air and that
the burn through point temperature (waste gas temparature at the last wind box of sinter
machine) could be increased from 370 to 390°C and vertical sintering speed increased from
19.35mm. to 20.1mm. Also, the above trials have confirmed that by way of air
humidification by steam in sinter plants it is possible to increase the productivity of sinter
machine from 1.28 to 1.37 t/m2 /hr. i.e. the productivity could be increased by about 7%.
It is thus possible by way of the present invention to provide for a process and system for
sintering to produce the iron ore sinter which would favour increasing the heat capacity of the
air /gas and thereby facilitate increasing the speed of sintering. Importantly, the invention
would fovour increasing the speed of sintering and also the productivity of sintering machine
to the desired extent for wide scale, cost -effective and user friendly sintering of iron ore.
WE CLAIM:
1. A process for sintering iron ore adapted for faster vertical sintering speed and higher
productivity comprising :
providing the desired sinter mix in the bed of the sinter machine;
providing volumetric air flow through the sinter bed ; and
increasing the heat capacity of the air during sintering by humidification of air by
steam injection.
2. A process for sintering iron ore as claimed in daim 1 wherein the humidification of air
by steam injection is carried out in the selected locations of the sintering machine.
3. A process for sintering iron ore as claimed in anyone of claims 1 or 2 wherein the
humidification of air by steam injection is carried out in the selected location of the
sintering machine such that hot zone (>600°C) width at the discharge end is reduced
to take care of high FeO sintering operations.
4. A process for sintering iron ore as claimed in anyone of claims 1 to 3 wherein the
steam is injected into sinter bed by transverse rows of sprays preferably through
nozzles into the sinter bed in the location 50% to 65% length of the machine from the
charge side.
5. A process for sintering of iron ore as claimed in anyone of claims 1 to 4 wherein the
steam spray is sucked into the sinter bed by the suction created in the wind boxes.
6. A process for sintering of iron ore as claimed in anyone of claims 1 to 5 wherein a
mixture of steam and air is sucked through the bed.
7. A process for sintering of iron ore as claimed in anyone of claims 1 to 6 wherein the
humidity of the air is increased to about 60 gm/Nm3 in the localized zone.
8. A process for sintering of iron ore as claimed in anyone of claims 1 to 7 wherein the
location of injection of steam is selectively at the zone where the sinter process speed
is minimum (volumetric flow of air through the zone is minimum) such that the hot
zone width extension is restricted.
9. A process for sintering of iron ore as claimed in anyone of Claims 1 to 8 comprising
injection of steam such as to result in increasing the vertical speed of sintering from
19.35mm to 20.1mm. by increasing the heat capacity of waste gases.
10. A process for sintering of iron ore as claimed in anyone of claims 1 to 9 wherein the
extension of the hot zone (>60°C) width is controlled such that the air flow through
65 to 100% (from the charging side) is improved due to the lesser resistance of sinter
bed.
11. A process for sintering of iron ore as claimed in anyone of claims 1 to 10 wherein the
bum through point temperature, waste gas temperature at the last wind box of sinter
machine is from 370 to 390°C preferably 390°C.
12. An iron ore sintering machine for carrying out the above process for sintering iron ore
as claimed in anyone of claims 1 to 11 adapted for faster sintering with higher
productivity comprising :
a sinter bed for carrying the sinter mix;
means for volumetric flow of air through the sinter bed;
means for injecting steam into sinter bed through nozzles in selected locations of the
sinter machine for increasing the heat capacity of the air/gas for faster sintering.
13. A sinter machine as claimed in daim 12 comprising nozzle means to inject steam into
the sinter bed by transverse rows of sprays into the sinter bed in the location
preferably at the zones where the sinter process speed is minimum mote preferably at
about 50% to 65% length of the machine from the charging side.
14. A sinter machine as claimed in anyone of claims 12 or 13 adapted such that the steam
spray is sucked into sinter bed by the suction created in the wind boxes.
15. A sinter machine as claimed in anyone of claims 12 to 14 comprising pipes of diameter
about 50 mm are laid across the width of pallet with the arrangement of flange joint in
one side and resting on strand on the other preferably about five numbers of parallel
pipes are provided across the width at locations of 50 to 65 % length of the machine
from the charging side.

Iron ore sintering process and sintering machine and, in particular, to iron ore sinter
manufacture and system therefore which would enable faster sintering speed and
increase in productivity sintering machine. The process and system of the invention
basically involves providing the desired sinter mix in a sinter machine; providing
volumetric air flow through the sinter bed ; and increasing the heat capacity of the
air during sintering by humidification of air by steam injection.
Importantly, the process of sintering and the system provided is adapted to increase
the burn through point temperature and also thereby improve the productivity of
sintering machines.