Claims:WE CLAIM:

1. A process for sinter production including wettability of sinter feed mix and related granulation fitness and productivity benefits comprising :

iv) providing sinter feed mix ;
v) carrying out dry mixing of the sinter feed mix in a first mixer drum ;
vi) providing sinter feed mix in a secondary mixing drum ( SMD ) involving supplying water for granulating of the feed mix wherein the water for granulating the feed mix involved pre-heated water favouring easy dispersion of water among sinter feed mix for effective granulation fitness including improved granulation and balling index.

2. A process for sinter production as claimed in claim1 wherein said pre-heated water involved in said secondary mixing drum for granulation is in the temperature range of 85 to 1000C preferably 90 to 95 0C and said secondary drum mixing is carried on for a period of 4 to 6 minutes preferably about 5 minutes for desired enhancement in granulation index in the range of 87.0 to 94.0 % and balling index 1.6 to 1.9 % .

3. A process for sinter production as claimed in anyone of claims 1 or 2 including steps of charging of the thus obtained pre-heated water treated green pellet agglomerations to conventional sintering with improved sinter yield of 82.0 to 85.0 %.

4. A process for sinter production as claimed in anyone of claims 1 to 3 wherein said water for granulation is pre-heated involving the waste heat of the sintering process.

5. A process as claimed in anyone of claims 1 to 4 comprising involving sinter feed mix comprising :

Iron bearing material 79-84%; Limestone 4-6 %;Dolomite 5-7 %; Quicklime 2.2.-3.3 % and coal 4.5 -5.2 %

wherein said step of involving pre-heated water favouring easy dispersion of water among sinter feed mix favour effective granulation fitness enable variable enhancement of yield 82.0 to 85.0 %, productivity in the range of 2.0 to 2.3 and increased FeO% of sinter in the level of 10.0 to 12.0 %.

6. A process as claimed in anyone of claims 1 to 5 wherein by involvement of said preheated water for secondary drum mixing sintering time involved was decreased to about 21.8 to 21.2 minutes and also related increase in vertical sintering speed from 0.027 m/min to 0.028 m/min based on the pre-heated water temperature used in said water for granulating sinter feed mix.

7. A process as claimed in anyone of claims 1 to 6 wherein the sinter feed included :

iron ore fines and other feed material including limestone, dolomite, mill scale, GCP dust, quicklime, flue dust and coal fines for useful blast furnace burden material for hot metal production and the raw feed material included different sizes preferably iron ore fines (-10 mm), coke breeze, limestone, dolomite, mill scale, GCP dust (-3mm) and return sinter (-5 mm) and the sinter produced included

Fe(T) FeO MgO SiO2 CaO Al2O3
54.2-56.5 9.8-11.2 1.8-2.2 4.37-4.70 10.94-12.07 2.69-3.5

8. A process as claimed in anyone of claims 1 to 7 comprising adding pre-heated water at high temperature 90°C to sinter feed mix, whereby the high temperature reduced the surface tension which in turn decreases the surface cohesive force, said reduced surface cohesive force enabled increase in the dispersion of water among the sinter feed mix inside SMD with said effective granulation fitness for suitable for generating improved sinter properties including Productivity increases by 4.7%, sinter yield increases by 2.1% and T.I increases by 1.6% with improved sinter chemistry, particularly FeO% increases by 15.8%. the increase in FeO% and with sinter agglomeration properties including B.I and G.I achieved with significant change with addition of pre-heated water for agglomeration of sinter feed mix including B.I increases by 9.7% and G.I increases by 5.3%.

9. A process as claimed in anyone of claims 1 to 8 wherein require heat source for said step of pre-heating the water for agglomeration of feed mix is sourced by tapping the waste heat of the sintering process and heating the water.

10. A system for carrying out the sinter production including wettability of sinter feed mix and related granulation fitness and productivity benefits as claimed in anyone of claims 1 to 6 comprising :

Primary mixing drum for said dry mixing of sinter feed mix;
Secondary mixing drum for wet mixing of said sinter feed mixing in the presence of pre-heated water:
Means for preheating the water and supply of preheated water into said secondary mixing drum;
Pallet car for sintering process;
Colling means for cooling of sinter product and
wherein said means for pre heating the water to temperature in the range of 85 to 1000Cpreferably about 90 -95 0C comprise sourcing supply of waste heat of sintering process collected via waste heat chimney operatively connected to the cooling means for cooling of sinter product from 700-800 to below 600C.

Dated this the 31st day of August, 2020
Anjan Sen
Of Anjan Sen & Associates
(Applicants’ Agent)
IN/PA-199
, Description:FIELD OF THE INVENTION:
The present invention relates to a process for sintering iron ore involving granulation of sinter feed mix adding pre-heated water for improved sinter property and productivity. More particularly, said method includes addition of pre-heated water in secondary mixing drum (SMD) to produce a green feed mix granules with improved BI and GI for sintering process. Water is pre-heated using waste heat from sinter plant. Importantly, the present invention is directed to a simple, cost effective and environment friendly process for sinter production ensuring improved bed permeability, sinter yield and higher productivity by utilizing pre-heated water for improved granulation.

BACKGROUND OF THE INVENTION:
The existing system in sinter making utilizes raw material like iron ore fines, limestone, dolomite, mill scale, GCP dust, quicklime, flue dust and coal fines to produce the feed mix required for iron ore sintering process. Due to excessive fineness of these raw material, they are pelletized (balling) /nodulized to a size range of 3-4 mm, before being used in sinter making.
However, the water added for granulation for pelletizing/nodulizing does not granulate all the raw material because increased surface area increases the demand for more water for effective palletization. Increasing water for granulation in preparing green mix increases the total water load which in turn affects the coal consumption and sinter productivity.
It is well known that in sinter making, formation of green balls facilitates bed permeability. Higher the extent of ball formation and bigger the size of balls, higher is the bed permeability. Higher bed permeability favor achieving higher sinter productivity. Calcium oxide due to its excellent binding properties tends to facilitate ball formation.
Patent application No:4732/CHE/2012 dated 12.11.2012 disclosed use of higher size burnt lime with a size range of 0-10 mm in order to increase the sinter productivity by ensuring improved permeability. Another patent application no.1114/KOL/2013 dated 27-09-2013 discloses use of milk of lime by using burnt lime with size -10 mm in order to increase sinter yield and productivity in a pot sinter test. However, the above works requires a capital investment and regular maintenance which will add the overhead cost to company. Also, consumption of binders will increase with increase of raw material fineness.
S.Dharaet. al. [October 2018 www.steeltimesint.com] has passed the water for granulation using magnetic conditioner in mixer drum. This increases the dispersion of water among the sinter feed mix owing to decrease in surface tension of water.

Considering a huge requirement for better granulation of sinter raw mix, without employing any additional capital investment, a necessity to innovate a different method for addition of water in mixer drum has been felt, which can reduce water load to sintering process without compromising any existing technological benefits of mixing material in SMD.
Research and Development Centre for iron and steel of JSW Steel, Ltd., at Dolvi Works, has successfully developed a new method for addition of “pre-heated water in sinter mix” to improve the quality of sinter and productivity of sinter plant through laboratory based pot sintering tests. The new method alsoresults in increase in FeO% in iron ore sinter.

OBJECTS OF THE INVENTION:
The basic object of the present innovation is thus directed to a process for sintering iron ore with addition of pre-heated water to sinter mix during granulation in SMD to improve bed permeability and sinter productivity.
A further object of the present innovation is to provide a process for sinter production using pre-heated water which will increase the granulation in SMD measured by balling index, such that this improvement in ball formation results in increase in sinter productivity.
A still further object of the present innovation is directed to provide a process for sinter production using pre-heated water addition in sinter mix during SMD, favored decrease in surface tension of water and the decrease in surface tension of water results in more bonding of fine particle mix and improve balling of fine particles.
A still further object of the present innovation is directed to provide a process for sinter production using pre heated water addition in sinter mix during SMD, favored increase in FeO% of sinter mix and this increase in FeO% is attributed to increase in the total heat supplied to sinter mix via pre-heated water.
Another object of the present innovation is directed to provide a process for sinter production using pre heated water addition in sinter mix during SMD, causes an increase in FeO% which will result in decrease in RDI of sinter mix and reduce the fine generation in top part of blast furnace.
Yet another object of the present innovation is to said process for sinter production using pre heated water addition in sinter mix during SMD, where the sinter chemistry remains unchanged except FeO%.
A further object of the present innovation is to provide a process for sinter production using pre heated water addition in sinter mix during SMD, favored an increase in the important phase SFCA-I.
A still further object of the present innovation is directed to provide a process for sinter production using pre heated water addition in sinter mix during SMD which would require no additional equipment and can be implemented in existing plant with a supply source of preheated water in secondary mixing drum.
A still further object of the present innovation is directed to provide a process for sinter production using pre heated water addition in sinter mix during SMD which would utilize waste heat from sinter plant for preheating water and thus is an energy efficient process.

SUMMARY OF THE INVENTION
The basic aspect of the present invention is directed to a process for sinter production including wettability of sinter feed mix and related granulation fitness and productivity benefits comprising:

i) providing sinter feed mix ;
ii) carrying out dry mixing of the sinter feed mix in a first mixer drum ;
iii) providing granulated sinter feed mix in a secondary mixing drum ( SMD ) involving supplying water for granulating of the feed mix wherein the water for granulating the feed mix for green pellet agglomeration involved comprise pre-heated water favoring easy dispersion of water among sinter feed mix for effective granulation fitness including improved granulation and balling index.

A further aspect of the present invention is directed to said process for sinter production wherein said pre-heated water involved in said secondary mixing drum for granulation is in the temperature range of 85 to 1000C preferably 90 to 95 0C and said secondary drum mixing is carried on for a period of 4 to 6 minutes preferably about 5 minutes for desired enhancement in granulation index in the range of 87to 94% and balling index 1.6 to 1.9% .
A still further aspect of the present invention is directed to said process for sinter production including steps of charging of the thus obtained pre-heated water treated green pellet agglomerations to conventional sintering with improved sinter yield of 82.0 to 85.0%.

A still further aspect of the present invention is directed to said process for sinter production wherein said water for granulation is pre-heated involving the waste heat of the sintering process.

A still further aspect of the present invention is directed to said process comprising involving sinter feed mix comprising:

Iron bearing material 79-84%; Limestone 4-6 %;Dolomite 5-7 %; Quicklime 2.2.-3.3 % and coal 4.5 -5.2 %

wherein said step of involving pre-heated water favouring easy dispersion of water among sinter feed mix favors effective granulation fitness enables variable enhancement of yield 82.0 to 85.0 %, productivity in the range of 2.0 to 2.3 and increased FeO% of sinter in the level of 10.0 to12.0 %.

A still further aspect of the present invention is directed to said process wherein by involvement of said preheated water for secondary drum mixing sintering time involved was decreased to about 21.8 to 21.2 minutes and also related increase in vertical sintering speed from 0.027 m/min to 0.028 m/min based on the pre-heated water temperature used in said water for granulating sinter feed mix.

A still further aspect of the present invention is directed to said process wherein the sinter feed included:

iron ore fines and other feed material including limestone, dolomite, mill scale, GCP dust, quicklime, flue dust and coal fines for useful blast furnace burden material for hot metal production and the raw feed material included different sizes preferably iron ore fines (-10 mm), coke breeze, limestone, dolomite, mill scale, GCP dust (-3mm) and return sinter (-5 mm) and the sinter produced included

Fe(T) FeO MgO SiO2 CaO Al2O3
54.2-56.5 9.8-11.2 1.8-2.2 4.4-4.7 10.9-12.1 2.7-3.5

Another aspect of the present invention is directed to said process comprising adding pre-heated water at high temperature 90°C to sinter feed mix, whereby the high temperature reduced the surface tension which in turn decreases the surface cohesive force, said reduced surface cohesive force enabled increase in the dispersion of water among the sinter feed mix inside SMD with said effective granulation fitness for suitable for generating improved sinter properties including Productivity increases by 4.7%, sinter yield increases by 2.1% and T.I increases by 1.6% and improved sinter chemistry, particularly FeO% increases by 15.8%. the increase in FeO% and with sinter agglomeration properties including B.I and G.I achieved with significant change with addition of pre-heated water for agglomeration of sinter feed mix including B.I increases by 9.7% and G.I increases by 5.3%.

Yet another aspect of the present invention is directed to said process wherein require heat source for said step of pre-heating the water for agglomeration of feed mix is sourced by tapping the waste heat of the sintering process and heating the water.

A still further aspect of the present invention is directed to a system for carrying out the sinter production including wettability of sinter feed mix and related granulation fitness and productivity benefits as described above comprising:

Primary mixing drum for said dry mixing of sinter feed mix;
Secondary mixing drum for wet mixing of said sinter feed mixing in the presence of pre-heated water:
Means for preheating the water and supply of preheated water into said secondary mixing drum;
Pallet car for sintering process;
Cooling means for cooling of sinter product and
wherein said means for pre heating the water to temperature in the range of 85 to 1000C preferably about 90 -95 0C comprise sourcing supply of waste heat of sintering process collected via waste heat chimney operatively connected to the cooling means for cooling of sinter product from 700-8000C to below 600C.

The above stated and other objects and advantages of the present invention are described hereunder in greater details with reference to following accompanying non limiting illustrative drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1: shows the flow chart for existing sintering process.
Figure 2:shows the flow chart for the sintering process according to present invention involving the mixing and granulation of feed mix using pre heated water.
Figure 3: illustrates schematic of pot sinter unit utilized for experimental trials according to the present invention.
Figure 4: shows graphically the improvement in (a) Granulation Index(GI) and (b) Balling Index(BI) for green mix obtained by the process for different temperature of pre heated water used in SMD.
Figure 5:shows graphically the improvement in (a) Yield, (b) Productivity and (c)Tumbler Index(TI), of product sinter with use of preheated water at different temperatures in SMD.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
The present invention is thus directed to a process for sinter production with improved quality of wet mixing and granulation of sinter mix for higher productivity and sinter yield using pre-heated water for granulation.
The existing sintering process is illustrated through a flow chart as per accompanying Figure 1. Sintering is a technology for agglomeration of iron ore fines and other material such as limestone, dolomite, mill scale, GCP dust, quicklime, flue dust and coal fines into useful Blast furnace burden material for hot metal production. The raw materials used for sintering are of different sizes such as iron ore fines (-10 mm), coke breeze, limestone, dolomite, mill scale, GCP dust (-3mm) and return sinter (-5 mm). The proportioned raw material is than mixed and moistened using normal process water in a secondary mixer drum i.e. SMD. The mix is then loaded on sinter machine through a feeder on a moving grate to produce product sinter.
More particularly, the present innovation relates to a new method for sintering wherein the addition of water in mixer drum for agglomerating the feed mix fines is replaced by addition of “pre-heated water” in sinter–mix to improve the granulation of fines and improve sinter yield and productivity. Accompanying Figure 2 shows the flow chart to illustrate the sintering process according to present invention.
In the present method, pre-heated water is maintained at temperature at around 90-95°C, and added in sinter mix for wet mixing and granulation in SMD in place of adding water for granulation and wet mixing at ambient temperatures in SMD.
In existing granulation process water for moisture addition in sinter feed mix is added at ambient temperature in SMD which is shown in process flow chart. No change in granulation fitness like Balling and Granulation index was observed.
However, with addition of pre heated water (1 in fig 2) at 90°C (modified sintering process), improvement in Balling and granulation index was observed. This was attributed to decrease of surface tension of waterat higher temperature.

Therefore, the method of sintering according to present invention for achieving higher productivity compromising the steps: providing sinter raw mix such as iron ore fines, and other material such as limestone, dolomite, mill scale, GCP dust, quicklime, flue dust and coal fines in weighed proportion and then transfer of the sinter raw mix through conveyer in a first mixer drum first, where dry mixing of sinter feed mix takes place and then it is transferred to SMD where pre heated water is added for moistening the feed mix to obtain granulated sinter feed mix. Moisture content in sinter feed mix is very important parameter in the granulation stage because the process of adhering fine particles to the nuclei to achieve the agglomeration of fines is very much dependent on the moisture available in SMD. Research has been carried out into the effect of moisture addition and wettability on agglomeration by determining the contact angle between the iron oxide and water and the iron ore granulation fitness (Balling index). Moisture capacity increases in line with the external surface area and decreases as the ore pore volume rises.
When dry solid particles come in contact with water, the ore surface is wetted and subsequently coated with a water film. On contact surfaces between particles, water surface tension causes bridges to form. Subsequent rotation inside SMD and contact of individual water droplets each containing one or many ore grains resulting in granulation. This process continues resulting in more and more entrapment of water molecules between particles and result in granulation.
In this new method, when the pre-heated water is added in sinter mix in SMD, at varying temperatures (30, 60& 90 °C), facilitates the easy wettability of sinter feed mix and improves the granulation of sinter feed mix. An additional heating vessel will be required for pre heating the water using waste heat of gases emitting from sinter plant, and no other additional equipment is necessary.With increase in temperature in water for granulation, the surface tension of water decreases and this facilitates easy dispersion of water among sinter feed mix. Hence each sinter feed mix now has sufficient water to form strong water bridges without compromising on feed rate or residence time in SMD. The granules thus formed are stronger in terms of compression with subsequent reduction in breakage due to abrasion in SMD indicated by increase in balling index.
The disclosed method of addition of “pre-heated” water in SMD for improved granulation of sinter has been successfully designed, developed and established through laboratory based pot sintering trials. Water at ambient temperature 30°C and Pre – heated water at 60 and 90°C have been added to SMD in sintering process and pot sintering test were done to find out the effect of “pre-heated” water addition on sinter properties like sinter yield and tumbler index and its effect on sinter chemistry.Accompanying Figure 3 illustrates schematic of pot sinter unit utilized for experimental trials according to the present invention.

POT SINTERING TESTS
Pot sintering was carried out on the actual sinter feed mix used for making sinter in sinter plant. Normal process water at ambient temperatures (30°C) are used for wet mixing of sinter feed mix in SMD. Continuous rotation of material was carried out for five minutes in SMD for producing granules of sinter feed fines. Sufficient number of pot sintering experiments were carried out with pre-heated water at 60 & 90 °C. Temperature 90°C was chosen for experiments because at this temperature water has lowest surface tension of 59 dyne/cm (Ref-http://hyperphysics.phy-astr.gsu.edu/hbase/surten.html)
Although, increase the temperature of water will result in decrease in surface tension of water but water temperature more than 100 degrees Celsius is not considered because present study is only for temperature >90°C at 1atm. Also increasing temperature of water above 100°C at 1 atm will result in phase change of water i.e. from liquid to gas i.e. water to vapor. Steam injection instead of hot water is not a part of the scope of this invention.
Various process data during pot sintering test were collected for analysis to understand the technological benefits/changes in sinter properties due to addition of “pre-heated” water at different temperatures.
Furthermore, applicants also conducted pot trials for temperature of water at 60°C and results are shown in accompanying Figures 4 & 5. Significant change in sinter properties like tumbler index is observed due to increase in B.I & G.I but no change is observed in productivity and sinter yield(at 60°C) compared to base case(at 30°C). Whereas, at 90-95°C, all sinter properties like sinter yield, tumbler index, productivity, B.I & G.I changes significantly.

The following procedure was followed in the experimental trials of pot sintering tests:

a) Preparation of samples for physico-chemical analysis:
All the raw material samples are subjected to both chemical and physical analysis tests. In the physical analysis test the raw materials are screened to different size fractions shown in Table -1, and chemical analysis of the feed mix is done by using XRF shown in Table-2.

Table 1 Size distribution of raw materials (mass%)
Sieve size (mm)
Raw material -10+8 -8+6 -6+3 -3+1 -1+0.5 -0.5+0.15 -5

Iron ore 16.5 35.5 26.5 10 9.5 2
Limestone 35 30 35
Dolomite 35 30 35
Return fine 100
Coal 40 30 30
Also, Quicklime is used as -3 mm

Table-2 Chemical analysis of sinter feed mix

Raw materials Fe(T) SiO2 Al2O3 CaO MgO Moisture LOI

Iron ore 59.8-64.5 2.5-5.4 1.8-4.1 0.08-1.29 0.03-0.39 6.0-11.2 2.1-4.8
Limestone 0.6-4.0 0.8-1.9 0.2-0.4 47.3-54.9 0.8-7.2 1.1-3.9 38.9-42.5
Dolomite 0.1-4.5 0.2-5.2 0.3-0.8 32.8-50.5 5.7-19.0 0.9-4.5 39.6-45.1
Quicklime 0.5-1.5 2.3-4.6 0.2-0.8 73.4-90.7 1.8-4.6 -- 3.1-18.3
Coal 0.4-0.6 4.6-7.7 3.0-4.4 0.4-0.7 0.1-0.2 5.9-7.3 81.1-84.1
Return fine 52.2-56.3 4.3-5.5 2.7-3.9 9.68-13.1 1.8-3.5 -- --

b) Charge calculations for pot sinter experiments:
Charge calculations for pot sinter experiments were done on the basis of four equations:
• FeO%
• LOI balance
• Total Fe
• MgO balance

Once the required compositions percentage of different raw materials are found out using the above mass balance equations, the raw material is weighed using electronic balance. Sinterfeed mix distribution (mass%) is shown in followingTable 3:

Table 3:Sinterfeed mix distribution (mass%)
Sl.No. Raw material mass%
1 Iron bearing material 79-84
2 Limestone 4-6
3 Dolomite 5-7
4 Quicklime 2.2-3.3
5 Coal 4.5-5.2

Pot sinter experiment plan were designed with three repeat trials. Pot sinter test conditions are shown in following Table-4.
c) Primary mixing of raw materials in mixer drum:
After weighment of raw materials, all the dry sinter feed mix are fed in for five minutes in primary mixer drum (PMD) for a through mechanized mixing. The PMD is rotated for about 15-17 rpm for about five minutes. After five minutes of mixing the sinter feed are ready for mixing in SMD.
d) Secondary mixing of raw material in mixer drum (SMD):
Water for wet mixing of raw materials is estimated based on the moisture level requirements of the mixture, which also depends on sinter feed mix water absorbing capacity. Water at 90°C temperatures are maintained by heating the water using Induction heater. The water is heated till temperature of water is reached to 100 °C. The rise in temperature of water were measured using data logger.
Water at ambient temperatures 30°C, 60°C and 90°C are added to dry sinter feed mix obtained from PMD in SMD at atmospheric conditions. The raw materials along with added pre-heated water is mixed thoroughly for five minutes. After mixing is completed in SMD samples are taken for moisture analysis and approximately 2.5 kg sinter feed mix samples collected after SMD and PMD to calculate balling index.
After confirmation of required moisture in sinter feed mix, the sinter feed mix (approximately 75 kg) is then fed into sinter pot manually in tray after weighment in digital weighing machine.
In every pot sintering test, the temperature of water is maintained at around 90+/-5°C. Since water addition in SMD took approximately 2-2.5 minutes, causes loss in water temperature by 5-7°C. The water was again pre-heated to maintain the required temperature.

e) Sintering process on sinter mix:
The sinter pot is geometrically cylindrical in shape with 600 mm height and 300 mm internal diameter. The bed height chosen here is as per the actual bed height maintained at the respective sinter plant. It is done so as to simulate the actual sinter plant conditions, so that the test results can be correlated.
The sinter pot with charge is mounted on top of wind box and the gap between sinter pot and wind box is sealed by nuts and bolts. Air blower of capacity 2700 mm WC is switched on to create the necessary suction beneath the grate bar. A suction of around 900 mm WC maintained during ignition (one minute) and then the suction is increased gradually to 1250 mm WC for the rest of the sintering process. During the sintering process, the suction and temperature of wind box is continuously monitored. When the wind box temperature reaches peak, it starts to decline, considering the sintering temperature. This peak wind box temperature is defined as break through point (BTP) marked as end of sintering process. Normally, in pot sinter trials the sintering time takes around 19-22 minutes.
After sintering is completed, it is kept for overnight cooling since it is very hot to handle manually. The sinter pot is then stripped to get sinter cake with the help of hoist crane. The sinter is than subjected to shatter test from a height of 2 m to simulate the star crusher activity in actual sinter plant. The sinter cake in shatter test is allowed to fall on a metal base plate of thickness 0.02 m. this test is carried out for two times to confirm the return sinter balance. After this the sinter samples are subjected to physical screening process. In this the process the sinter is classified as +40 mm, +20 mm, +10 mm, +8 mm and +5 mm fractions to estimate their percentage in the total material.The +5 mm size fractions of sinter are considered as final product of the sintering process.
Tumbler index is calculated using IS: 6495 - 1984
Table-4:Pot sinter test conditions used for pot sinter experiments.
S.I No. Parameters Value
1 Bed height 0.60 m
2 Hearth layer/weight 0.06 m/ 7.5 kg
3 Ignition time 60 s
4 Suction during ignition 900 mm WC
5 Suction during sintering 1250 mm WC
6 Moisture 7.5 +/- 0.2 %

The process is implementable in industrial scale and all the test condition shown in Table-3 is similar to plant scale.
The following parameters were measured during the experiments:
• Sintering time
• BTP temperature
• Suction pressure
Sintering time has been decreased from 21.8 minutes (30°C) to 21.2 minutes (90°C)which results in increase in vertical sintering speed from 0.027 m/min to 0.028 m/min. Accordingly productivity has been improved. Sintering time at 60°C is similar to 30°C pot sinter trial.
The following parameters were calculated through the experiments:
• Sinter yield
• Tumbler index (T.I)
• Productivity
• Vertical sintering speed (VSS)
• Balling Index (B.I)
• Granulation Index (G.I)

The following pot sinter results were obtained using water at three temperatures:
Table 5: Pot sinter test results
Expt. No. Water temperature Productivity
(t/m2/hr.) Sinter yield T. I B. I G. I
1 30 2.1 81.6 60.7 1.65 87.9
2 60 2.1 81.7 61.9 1.82 88.5
3 90 2.2 83.3 61.7 1.81 92.6

Table-6:Chemical analysis of pot sinter test results
Water temperature (°C) T. Fe FeO CaO MgO SiO2 Al2O3 B2
30 56.7 10.1 9.4 2.0 4.9 2.8 1.9
60 56.6 10.3 9.3 1.9 4.9 2.8 1.9
90 56.8 11.7 9.4 2.0 5.0 2.8 1.9
Final sinter product chemistry with range of components in mass% is standardized through additional trials with water temperature at 90-95C as follows:
Fe(T) FeO MgO SiO2 CaO Al2O3
54.2-56.5 9.8-11.2 1.8-2.2 4.37-4.70 10.94-12.07 2.69-3.5

It is observed that all the sintering properties such as sinter yield, T.I and productivity were low when water for agglomerating sinter feed mixes were used at normal temperature i.e. 30°C. the sinter properties. The sinter properties increase when temperature of water is increased to 90°C.
Productivity increases by 4.7%, sinter yield increases by 2.1% and T.I increases by 1.6% with addition of pre heated water at 90°C. Sinter chemistry, particularly FeO% increases by 15.8%. the increase in FeO% is mainly attributed to addition of extra heat through pre heated water at 90°C.
Sinter agglomeration properties such as B.I and G.I also shows significant change with addition of pre-heated water for agglomeration of sinter feed mix. B.I increases by 9.7% and G.I increases by 5.3%.
Above improvement in granulation and sinter products are shown graphically in accompanying Figures 4 & 5.
When water at high temperature (90°C) is added to sinter feed mix, this high temperature reduces the surface tension which in turn decreases the surface cohesive force. This reduced surface cohesive force will now increase the dispersion of water among the sinter feed mix inside SMD. Thus, the resultant effect of this water treatment is that, now each layer has now sufficient water to form stronger water bridges without compromising on feed rate or residence time.
It is thus possible by way of the present invention to provide a process for sinter production using pre heated water at a temperature of 90°C, which would favor the granulation of sinter feed mix in SMD, results in increase in improved agglomeration properties and result in increase in sinter properties. Moreover, the above process also results in increase in Sinter FeO% which will decrease the total coal consumption. Thus, this process of using pre heated water for agglomerating sinter feed mix fines is also capable of tapping waste heat which otherwise goes as waste to environment.