Claims:1. A system for pre-hydrating calcined lime and its subsequent addition to one or more raw material during sintering at sinter plant, wherein said system comprising:
at least one lime slaker assembly to receive powdered calcined lime and water at an optimum concentration ratio of 50 grams to 80 grams per litres of water, and produce said hydrated calcined lime solution;
at least one classifier compartments adapted to receive said hydrated calcined lime solution by means of an open weir and segregate un- hydrated lime particles from said solution;
at least one storage tank wherein said hydrated lime solution is transferred from at least one output of said classifier, said storage tanks provided with agitators for producing homogenous lime-water solution, wherein said homogenous lime-water solution pumped to at least one primary mixing drum by means of at least one transfer pumps;
wherein, said system further comprises means to regulate flow of water during adding of water to said lime slaker assembly and/or supplying of said homogenous lime-water solution to said primary mixing drum.

2. The system as claimed in claim 1, wherein said means to regulate flow of water is rotameters.

3. The system as claimed in claim 2, wherein said rotameters positioned in the inlet water line to said lime slaker assembly and outlet of said storage tanks.

4. The system as claimed in claim 1, wherein said lime slaker assembly comprises motorized bladed agitator, preferably made of stainless steel.

5. The system as claimed in claim 1, wherein said classifier compartments comprises rakes, preferably made of stainless steel.

6. The system as claimed in claim 1, wherein said agitators in said storage tanks is a motorized bladed agitator, preferably made of stainless steel.

7. The system as claimed in claim 1, wherein said transfer pumps comprises at least one impeller preferably made of stainless steel, and drive motor.

8. The system as claimed in claim 1, wherein primary mixing drum provided with spray nozzles for spraying said hydrated lime solution to said raw materials for subsequent agglomeration.

9. The system as claimed in claim 1, wherein said raw material is sinter feed

10. The system as claimed in claim 9, provides control supply of hydrated lime solution in sinter feed as per the moisture requirement in said sinter feed during sintering.

11. A method for pre-hydrating calcined lime and its subsequent addition to one or more raw material during sintering at sinter plant, wherein said method comprising the steps:
mixing of powdered calcined lime with water at an optimum concentration ratio of 50 grams to 80 grams of lime per liter of water to form a hydrated calcined lime solution, wherein said water is supplied at a controlled flow rate;
separating un-hydrated calcined lime from said hydrated calcined lime solution and thereby transferring said hydrated calcined lime solution to at least one storage tank for storing;
supplying said hydrated calcined lime solution to a mixing drum at an optimum feed rate of 1m3/hr to 2m3/hr, wherein control supply of said hydrated calcined lime solution is carried out by means of at least one rotameter; and thereby
enabling mixing of said hydrated calcined lime solution with said raw materials for carrying out the subsequent process of sintering.

12. The process as claimed in claim 11, wherein said powdered calcined lime is uncrushed and preferably of size 15mm to 25 mm.

The process as claimed in claim 11, wherein said hydrated lime solution is maintained at an optimum temperature of 40-50°C
, Description:TECHNIAL FIELD

[001] The present subject matter described herein, in general, relates to a process of pre-hydrating calcined lime during sintering at sinter plants. More specifically, the present invention relates to an improved technique of utilizing a pre-hydrated calcined lime and its subsequent addition in sinter feed during the process of sintering.

BACKGROUND

[002] The Sintering process is a pre-treatment step in the production of sinter pellets wherein, fine particles of iron ores, coke, fluxes, that includes but not limited to, lime stone and dolomite, calcined lime (CaO) fines, return sinter fines, mill scale and the like, which is thereby agglomerated by combustion at sinter plants.

[003] Sinter Plant is one of the major sources of dust generation, which pollutes the atmospheric air. Pollution control of industries is becoming more critical and its regulations are getting severe day by day. Therefore calcined lime is used in the sinter feed to improve the strength of sinter pellets, such as to reduce dust generation due to weak sinter production.

[004] Therefore, in sintering process, calcined lime is used as a very good process intensifier in sinter making and hence calcined lime is added in sinter-feed as a binder for improving agglomeration of sinter-feed fines. Further, addition of lime fines with other raw materials of sinter mix, improves granulation, permeability and vertical sintering speed, which results in increase in productivity of sinter machine. Besides, dry calcined lime fines of size < 3mm at addition rate of 30 Kg / ton-sinter yields maximum technological benefits in sintering. Thus, due to the technology benefits of calcined lime fines in sintering, almost every sinter plant has facility of adding dry calcined lime fines in sinter-feed.

[005] However, calcined lime as a binder, acts slowly due to its slow rate of solidification as a result of the hydration of calcium oxide and intergrowth of crystals of calcium hydroxide. So, for improved bonding efficiency of lime in sinter mix, the calcined lime need sufficient time for its completion of hydration process.

[006] However, in the conventional sintering system and process, the calcined lime (CaO) fines is added in a solid powdered form on a belt conveyor with other raw materials of sinter, through pneumatic conveying system. Water is added with sinter-feed in parts in Mixing Drum and / or Balling Drum, as per the need of moisture in the process. During the mixing in Mixing Drum, calcined lime reacts with water for hydration. However the time provided for mixing in the Mixing or Balling drum is very limited, due to the chain of upstream and downstream processes. As the time in mixing drum is limited, the calcined lime does not complete its hydration process fully, and hence some portion of calcined lime goes as waste (un-hydrated lime) along with output sinter. This results in reduced amount of calcined lime available for effective bonding process in sinter-feed for better agglomeration, leads to reduction in balling efficiency of sinter mix. The un-hydrated lime goes as waste along with product sinter leads to reduction in the yield and hence increases the cost of sintering. Similarly, in the existing method of adding the calcined lime in dry fines form over the moving belt conveyor, wastage of calcined lime is un-avoidable in different material handling process.

[007] Thus, summarizing the drawbacks of the conventional lime addition methodas follows:

i. The effectiveness of lime as a bonding agent is very low, as the lime does not completes its hydration process, due to low lime hydration process time. This in-complete lime hydration process causes increased requirement of calcine lime in sintering to compensate its deficiency, for maintaining other parameters of sintering.The in-complete hydration process of lime in water causes low bonding among the particles, leading to poor agglomeration and hence forms weak agglomerated particles.

ii. The calcined lime is added to sinter-feed in dry powdered form on an open belt conveyor. The leads to wastage of calcined lime in different handling processes.

iii. In the existing system of calcined lime addition in sinter-feed, wastage of calcined lime is around 10 to 15% in different handling processes and wastage of calcined lime as unprocessed condition is around 10 to 15%. Due to in-complete hydration of lime, the requirement of calcined lime in sintering process increases.

iv. In conventional (existing) system of calcined lime addition in sinter-feed, calcined lime of appropriate size in dry fines form is brought from Lime Plant after various material handling processes such as crushing, screening. At Sinter Plant, the lime is added on an open belt conveyor, after passing through various material handling systems such as pneumatic unloading system from the closed transportation vessel, pneumatic conveying to storage hopper through pipeline, de-dusting system, loss-in-weight feeding system, rotary lock with screw feeding system etc. This auxiliary material handling systems necessary for calcined lime addition in sinter-feed increases the overall cost and the system and involves larger space for installation.

[008] Considering both the importance of technological benefits of calcined lime addition in sinter-feed and the drawbacks/deficiencies/constraints in the existing mode of addition of calcined lime in dry fines form, the necessity for finding an alternate method of calcined lime addition in sinter-feed has been originated.

[009] To improve the effectiveness of calcined lime in sintering for better bonding efficiency in sinter-mix, it is necessary to allow the lime to complete its hydration process within the available time duration in conventional process. Accordingly, there is dire need for an improved mechanism that can be applied to sintering process so as to replace the conventional method of adding calcined lime as a dry powdered form in a sinter feed. The need for the improved mechanism is to fully allowthe calcined lime to hydrate in presence of water before its addition as hydrated lime solution in sinter-feed, to improve its performance as a bonding agent in sinter-mix

SUMMARY OF THE PRESENT INVENTION

[0010] The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

[0011] The basic object of the present invention is thus directed to provide an improved and efficient method of addition of calcined lime in sinter-feed, to improve the effectiveness of calcined lime as a bonding agent in sinter-mix.

[0012] Another object of the present invention is to provide an improved method of adding calcined lime as hydrated lime solution in sinter-feed, such as to overcome the drawbacks of the existing conventional method of adding calcined lime in sinter-feed as dry powdered form.

[0013] Yet another object of the present invention is to provide a system and method for preparation of hydrated lime solution at an optimum concentration ratio and then its subsequent addition in sinter feed at an optimum feed rate during sintering process.

[0014] Accordingly, in first aspect of the present invention, there is provided a system for pre-hydrating calcined lime and its subsequent addition to one or more raw material during sintering at sinter plant, wherein said system comprising:

at least one lime slaker assembly to receive powdered calcined lime and water at an optimum concentration ratio of 50 grams to 80 grams per litres of water, and produce said hydrated calcined lime solution;
at least one classifier compartments adapted to receive said hydrated calcined lime solution by means of an open weir and segregate un-hydrated lime particles from said solution;
at least one storage tank wherein said hydrated lime solution is transferred from at least one output of said classifier, said storage tanks provided with agitators for producing homogenous lime-water solution, wherein said homogenous lime-water solution pumped to at least one primary mixing drum by means of at least one transfer pumps;
wherein, said system further comprises means to regulate flow of water during adding of water to said lime slaker assembly and/or supplying of said homogenous lime-water solution to said primary mixing drum.

[0015] In second aspect of the present invention, there is provided amethod for pre-hydrating calcined lime and its subsequent addition to one or more raw material during sintering at sinter plant, wherein said method comprising the steps:
• mixing of powdered calcined lime with water at an optimum concentration ratio of 50 grams to 80 grams of lime per liter of water to form a hydrated calcined lime solution, wherein said water is supplied at a controlled flow rate;
• separating un-hydrated calcined lime from said hydrated calcined lime solution and thereby transferring said hydrated calcined lime solution to at least one storage tank for storing;
• supplying said hydrated calcined lime solution to a mixing drum at an optimum feed rate of 1m3/hr to 2m3/hr, wherein control supply of said hydrated calcined lime solution is carried out by means of at least one rotameter; and thereby
• enabling mixing of said hydrated calcined lime solution with said raw materials for carrying out the subsequent process of sintering.

[0016] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

[0017] Figure 1 illustrates a block diagram representation of the system for pre-hydrating calcined lime during sintering process, according to the present invention.
[0018] Figure 2 illustrates a schematic diagram of the system showing the steps of the process in accordance with an embodiment of the present invention.
[0019] Figure 3 illustrates a schematic representation of a deployed system at sinter plant, in accordance with an embodiment of the present invention.

[0020] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0021] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

[0022] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0023] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0024] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0025] By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

[0026] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

[0027] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0028] In one implementation, the present invention achieves the objectives by replacing the use dry-powdered form of calcined with the pre-hydrated lime solution in sinter-mix. In the earlier conventional method of calcined lime addition in sinter-feed, calcined lime is added in ‘dry fines form’ on an open belt conveyor, carries other raw materials (sinter-feed) to Mixing Drum wherein, the water is added separately as mixing media. However, in the present invention, calcined lime can be added in sinter-feed inside the Mixing Drum in ‘liquid form’ after transforming the calcined lime fines in to hydrated lime solution separately. Installation and commissioning of a system suitable for generation of hydrated lime solution at an appropriate concentration level and its addition into sinter-feed at an appropriate feed rate

[0029] In one implementation, reference is made to figure 1 wherein a block diagram representation of the system for pre-hydrating calcined lime during sintering process is illustrated.

[0030] In one implementation, a system as shown in figure 1 may be utilized for generation of ‘hydrated lime solution’ (calcium hydroxide) at an appropriate concentration ratio and then its addition in sinter-feed at Mixing Drum of Sinter Plant at an appropriate feed rate to improve different technological benefits of calcined lime in sinter-feed, that may include but not limited to, balling efficiency, air filtration velocity, strength of sinter and the like that can be achieved at sinter plants.

[0031] In one implementation, the system can be suitable to generate ‘hydrated lime solution’ through fully completed lime hydration process by mixing dry calcined lime fines with normal process water at an appropriate concentration ratio and then its addition in sinter-feed at primary mixing drum at an appropriate rate. This system for alternate method of adding calcined lime in sinter-feed of approximately 4 m3/hr capacity, can be installed at ground level, near the Primary Mixing Drum at the sinter plants.

[0032] In one implementation, reference is made to figure 2 wherein a schematic diagram of the system showing the steps of the process is illustrated. The elements used in the system is as follows:
(1) Lime slaker assembly
(2) Classifier
(3) Storage tank
(4) Transfer pumps
(5) and (14) Manual control valve
(6) Primary Mixing Drum (PMD)
(7) and (8) Agitator
(9) and (10) Rotameter
(11) Grit Collection Trolley
(12) Calcined Lime-inlet
(13) Process water-inlet
(15) Strainer
(16) water header

[0033] In one implementation, the system consists of major equipment / sub-systems facilitated to generate hydrated lime solution (Ca (OH)2 ) at an appropriate lime to water concentration ratio suitable for steel plants, the equipment / sub-systems includes:
• lime slaker cum classifier assembly having motorized racker assembly, agitator in slaker tank,
• agitator installed hydrated lime solution storage tanks,
• slurry pumps with their drives,
• pipelines,
• electric hoist for lifting lime bags,
• electric panel,
• strainer,
• rotameters

[0034] In one implementation, reference is made to figure 3 wherein a schematic representation of a deployed system at sinter plant is illustrated.

[0035] In one implementation, as shown in figure 2, calcined lime can be added into the lime Slaker assembly (1) manually through inlet opening at top (12). Process water can thereby be added into the Slaker assembly through opening (13). Lime along with water forms ‘hydrated lime solution’ and passes to Classifier compartment (2) wherein the un-hydrated lime particles such as the Grits, can be separated through continuously operated scrapper. The grits can be collected in a moveable trolley (11) provided below the classifier outlet mouth. The final product, that is the hydrated lime solution can be stored in one of the storage tanks (3) before it is pumped out by transfer pumps (4) to Primary Mixing Drum (6) for subsequent addition into sinter-feed. Suitable rotameters (9 & 10) can be provided in water line to slaker and final product line to PMD (9) to measure their respective flow rates. One strainer (15) can be provided at inlet point of water line tapped from the header.

[0036] In one implementation, as shown in figure 3, the deployed system as at Sinter Plant. It shows all the equipment / sub-systems involved in the system at its actual positions at site. Calcined lime with water can be mixed inside for hydrated lime solution preparation in Slaker (1) through continuous agitation by agitators. After separation of un-hydrated lime (Grits), the final product can be transported from the Classifier (2) to one of the storage tanks (3). The grits are discharged through classifier outlet (5) into grit collecting moveable trolleys (4). The final product can be pumped out to Primary Mixing Drum from the storage tanks through pump and its drive assemblies (6) for addition into sinter-feed.

[0037] In one implementation, when calcined lime is hydrated fully, it’s surface area increases manifolds and hence its wet ability around other particles increases significantly. The increased wet ability of lime around ore particles increases the bonding efficiency among the fine particles leads to improve and strong agglomerated bigger particles for better bed permeability.

[0038] In one implementation, Calcined lime (CaO) of size preferably < 25 mm, can be brought to Sinter Plant in portable poly bags and stored in a room near the Primary Mixing Drum (PMD) area of Sinter Plant. Then the CaO contained poly bags are lifted from ground level to above the charge opening of the Lime Slaker assmbly by a monorail electric hoist and manually charged into the slaker hopper (1) by opening the poly bags. Process water from nearby existing header (16) can be tapped and charged into the slaker hopper through inlet (13). The feed rate of CaO and water into slaker assembly can be manually controlled as per the process requirement of hydrated lime solution in sintering. The slaker assembly(1) can be provided with a four bladed stainless steel made agitator fan (7) inside to provide suitable agitation to the lime solution, to prevent settling of lime particles at bottom of the slaker tank. The slaked lime solution from the slaker tank may then be passed to the connected Classifier (2) compartment through open weir. In the classifier, continuously operated racker blades assembly, discharges the lime grits through scrapping in to a wheeled trolley collector (11).

[0039] In the above implementation, the hydrated lime solution prepared in the Slaker assembly can then transferred to one of the storage tanks (3) placed on gravity mode. Both the storage tanks are suitably provided with agitators (8) for proper homogeneous lime-water solution. After filling the first storage tank, the output of the slaker classifier can be transferred to the second storage tank for storing. From the storage tank, lime-water solution (hydrated lime solution)can be pumped out by suitable pumps and motors (4) through pipeline to the Primary Mixing Drum (6). The outlet of the discharge pipeline (inside the PMD), can suitably be provided with wide angle spray nozzles for covering maximum sinter-mix inside the PMD. Appropriate rotameters (9) can be provided at the inlet water line to the slaker-classifier assembly and outlet of the storage tanks. With manual control valves (14 & 5) and respective rotameter (9 & 10), the flow of inlet water to the slaker and outlet of lime-water solution to the PMD can be regulated as per the requirement.

[0040] In one implementation, the critical parameters of the system and the method is elucidated in the following table:

Size of calcined lime used in the slaker 15 mm to 25 mm, uncrushed
Purity: 85% -90%
Water used in the slaker Industrial process water
Mode of adding process water into slaker-classifier Tapped through pipeline from the existing main header through isolation valve, rotameter and control valve.
Optimum concentration ratio of hydrated lime solution 50 grams to 80 grams per liter of water
Optimum temperature of hydrated lime solution maintained 40 to 500 C

Optimum location for addition of hydrated lime solution with sinter-feed Inside the Primary Mixing Drum (PMD)
Optimum feed rate of hydrated lime solution in PMD 1 m3/hr to 2 m3/hr

[0041] Some of the noteworthy features of the present invention:

1. The present invention provides a method for addition of calcined lime at commercial scale level in sinter feed of sinter plant.

2. The present invention provides asystem for controlled addition of calcined lime at commercial scale level in sinter-feed of sinter plant.

3. The system can be installed at sinter plant for generation of hydrated lime solution at an appropriate concentration ratio(50-80 grams per liter of water) of lime and water in solution and its further controlled addition (1 m3/hr to 2 m3/hr) in sinter-feed of sintering plant.

4. The system consists of a Lime slaker with stainless steel bladed motorized agitator, rack-classifier with stainless steel made rakes, storage tanks with stainless steel bladed motorized agitators, transfer pumps with stainless steel impellers and its drive motors, electric mono rail hoist for lifting lime contained poly bags, control panel for controlling all drives, spray nozzles inside the mixing drum.

5. The system is capable of generating hydrated lime solution at variable concentration ratio up to 100 grams of lime per liter of water.

6. The system is capable to control the hydrated lime solution’s addition rate in sinter-feed as per the moisture requirement in sinter-feed of sintering process.

[0042] The comparative data of the present invention and the existing conventional system includes:

1. In conventional system of calcined lime addition in sinter-feed, in-complete hydration process of lime in water presence causes low bonding among the particles, leads to poor agglomeration and hence forms weak agglomerated particles. Whereas in the present invention, calcined lime is allowed fully to complete its hydration process in presence of water causes increased bonding efficiency among the particles of sinter-feed and hence forms strong agglomerated particles.

2. In conventional system of calcined lime addition in sinter-feed, calcined lime is added in sinter-feed, in dry powdered form on an open belt conveyor, leads to wastage of calcined lime in different handling processes. Whereas in the present invention, calcined lime is added in sinter-feed in liquid solution form (hydrated lime solution) inside the Mixing Drum through pipeline, leads to no wastage of calcined lime in handling processes.

3. In conventional system of calcined lime addition in sinter-feed, wastage of calcined lime (around 10 to 15%) in different handling processes and wastage of calcined lime as unprocessed condition (around 10 to 15%) due to in-complete hydration of lime has increases the requirement of calcined lime in sintering process. Whereas in the present invention, little or no wastage of calcined lime in handling the calcined lime in liquid form and little or no wastage in the sinter process as lime is fully hydrated before adding to sinter-feed has reduces the requirement of calcined lime in the sintering process.

4. In conventional system of calcined lime addition in sinter-feed, calcined lime of appropriate size ( < 3 mm) in dry fines form is brought from Lime Plant after various material handling processes such as crushing, screening etc. At Sinter Plant, the lime is added on an open belt conveyor, after passing through various material handling systems such as pneumatic unloading system from the closed transportation vessel, pneumatic conveying to storage hopper through pipeline, de-dusting system, loss-in-weight feeding system, rotary lock with screw feeding system etc. A material handling systems necessary for calcined lime addition in sinter-feed need huge cost investment and larger space requirement for installation. Whereas in the present invention, calcined lime can be brought from Lime Plant in poly bags on an open transportation vehicle. The size of calcined lime does not matter much as lime to be simply diluted in water and hence no need of crushing and screening systems at Lime Plant. At sinter plant, calcined lime is converted into hydrated lime solution in presence of water in a ‘Lime Slaker Classifier’ system and added to sinter-feed at Mixing Drum, by pumps and conveying pipelines. As the material handling system necessary in the present invention is very simple, the cost of investment on the material handling systems and the space requirement is very low.

5. In conventional system of calcined lime addition in sinter-feed, it is necessary that calcined lime of < 3 mm is to be added in sinter-feed at a rate of 30 Kg / tons-of-sinter to achieve maximum technological benefits in sinter making operation. Whereas in the present invention, it is necessary that calcined lime is added in liquid form as hydrated lime solution at an optimum concentration ratio of 50 to 80 grams of lime per liter of water and at an optimum feed rate of 2 tons/hr inside the Mixing Drum to achieve equivalent amount of technological benefits of the earlier conventional system.

[0043] The following are the major technological benefits achieved through the controlled addition of calcined lime in sinter-feed as ‘hydrated lime solution form’ in comparison to non-addition of any calcined lime in sinter-feed:

Conventional method of addition of dry calcined lime in sinter feed The improved method addition of calcined lime in sinter-feed as ‘hydrated lime solution form’
Average Balling Index: 1.7 Average Balling Index: 1.9
Degree of granulation: 27 % Degree of granulation: 32%
Increase in Air Filtration velocity: 0.14 m/s Increase in Air Filtration velocity: 0.15 m/s
Reduction in suction of wind-main: 540 mmWC Reduction in suction of wind-main: 453 mmWC
Increase in temperature at wind-main: 113°C Increase in temperature at wind-main:
123°C
Reduction in generation of CO in waste gas: 0.06% Reduction in generation of CO in waste gas: 0.03 %

[0044] Thus, the advantages of the present invention is as follows:
• Addition of hydrated lime solution in sinter-mix at primary mixing drum, improves the balling efficiency of the sinter charge mix significantly, as the effectiveness of bonding agent of the charge mix i.e., calcined lime as hydrated lime solution increases manifold, in comparison to the conventional dry form of lime addition in sinter charge mix.
• The present invention also results in increase air filtration velocity due to improved bed permeability.
• As the calcined lime in hydrated lime solution form completes its hydration process fully, well before it is added to the charge mix, the surface area of lime particles increases and hence it’s binding efficiency improves among the particles, compared to the incomplete hydration process in case of conventional lime addition system.
• The addition of calcined lime is added in sinter-feed in liquid solution form (hydrated lime solution) inside the Mixing Drum through pipeline, leads to no wastage of calcined lime in handling processes.
• The present invention reduces the requirement of calcined lime in the sintering process by at least by 50% from the existing conventional system.

[0045] Although a system and method for treating pre-hydrated calcined lime during sintering have been described in language specific to structural features and/or methods, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or methods or elements described herein. Rather, the specific features are disclosed as examples of implementations of the system and method for treating pre-hydrated calcined lime during sintering.