We Claim:

1. A system (100) for removing moisture from a sinter bed (2), the system (100) comprising:
at least one furnace (1) positioned over the sinter bed (2), wherein the at least one furnace (1) is configured for sintering;
at least one suction device (3) positioned below the sinter bed (2) and configured to draw air from the sinter bed (2);
at least one flow creation device (4) positioned proximal to the sinter bed (2) wherein, the at least one flow creation device (4) is configured to direct hot air through the sinter bed (2); and,
an updraft flow of the hot air generated by the at least one flow creation device (4) sinters the sinter bed (2).

2. The system (100) as claimed in claim 1, wherein at least one flow creation device (4) is positioned below the sinter bed (2) and is configured to direct hot air through the sinter bed (2) from bottom of the sinter bed (2) to atmosphere.

3. The system (100) as claimed in claim 1, wherein at least one solenoid (5) is connected to the at least one flow creation device (4) to induce the updraft flow of the hot air in a sinusoidal wave form through the sinter bed (2).

4. The system (100) as claimed in claim 1, wherein the at least one furnace (1) ignites the sinter bed (2) at a rate of 10 mm/min to 30 mm/min for the siter bed (2) height ranging from 500 mm to 600 mm.

5. The system (100) as claimed in claim 1, wherein the sinter bed (2) is categorized into a wet zone (8), a drying zone (9), a reaction zone (10), and a cooling zone (11).

6. The system (100) as claimed in claim 5 wherein, thickness of the wet zone (8) is smaller than the thickness of the drying zone (9), the reaction zone (10), and the cooling zone (11).

7. The system (100) as claimed in claim 1, wherein overall temperature of the sinter bed (2) ranges from 1290 ºC to 1310 ºC.

8. The system (100) as claimed in claim 1 wherein, the hot air directed from the at least one flow creation device (4), traverses from a bottom portion of the sinter bed (2) to a top portion of the sinter bed (2).

9. The system (100) as claimed in claim 1 wherein, the evaporated moisture traverses to the bottom portion of the sinter bed (2) and condenses in the bottom portion of the sinter bed (2).

10. The system (100) as claimed in claim 1 wherein, the solenoid (5) includes a valve that is configured to open and close at a pre-determined frequency for inducing the sinusoidal wave form to the hot air directed from the at least one flow creation device (4).

11. The system (100) as claimed in claim 10 wherein, the valve in the solenoid (5) is operated at the pre-determined frequency ranging from 30 seconds to 40 seconds.

12. The system (100) as claimed in claim 10 wherein, the valve in the solenoid (5) is operated at 30% to 60% and at a rate of 30 seconds to 40 seconds for inducing the sinusoidal wave form to the air from the at least one flow creation device (4).

13. The system (100) as claimed in claim 1 wherein, the air is directed from the at least one flow creation device (4) at time intervals of 1 minute.

14. The system (100) as claimed in claim 1 wherein, the pressure of the air directed from the at least one flow creation device (4) ranges from 200 mm of water column to 600 mm of water column.

15. The system (100) as claimed in claim 1 wherein, the temperature of the air directed from the at least one flow creation device (4) ranges from 70 ºC to 100 ºC.

16. A method for sintering a sinter bed (2), the method comprising:
directing a hot air to the sinter bed (2) by at least one flow creation device (4) positioned proximal to the sinter bed (2).

17. The method as claimed in claim 16, wherein inducing by at least one solenoid (5), an updraft flow of the hot air in a sinusoidal wave form through the sinter bed (2) wherein, the at least one solenoid (5) is connected to the at least one flow creation device (4).

18. The method as claimed in claim 16, wherein, the updraft flow of the hot air evaporates and removes moisture in the sinter bed (2).

19. The method as claimed in claim 16 wherein, the furnace (1) ignites the sinter bed (2) at a rate of 10 mm/min to 30 mm/min for the siter bed (2) height ranging from 500 mm to 600 mm.

20. The method as claimed in claim 16 wherein, the air directed from the at least one flow creation device (4), traverses from a bottom portion of the sinter bed (2) to a top portion of the sinter bed (2).

21. The method as claimed in claim 16 wherein, the evaporated moisture traverses to the bottom portion of the sinter bed (2) and condenses in the bottom portion of the sinter bed (2).

22. The method as claimed in claim 16 wherein, the sinusoidal wave form is induced to the hot air directed from the at least one flow creation device (4) by configuring the valve in the solenoid (5) to open and close at a pre-determined frequency.

23. The method as claimed in claim 16 wherein, the valve in the solenoid (5) is operated at the pre-determined frequency ranging from 30 seconds to 40 seconds.

24. The method as claimed in claim 16 wherein, the hot air is directed from the at least one flow creation device (4) at time intervals of 1 minute.
, Description:TECHNICAL FIELD

Present disclosure generally relates to a field of material science and metallurgy. Particularly, but
not exclusively the present disclosure relates to a sintering process. Further, embodiments of the disclosure disclose a system and method of removing moisture from a sinter bed during the sintering process.

BACKGROUND OF THE DISCLOSURE

Sintering is a process which includes processes of compacting and forming solid mass of material
by application of heat or pressure or both. The sintering process is conducted through a Dwight-LloydTM machine. During sintering process, application of heat or pressure is carried out in a controlled manner where the temperature and pressure are controlled just enough to a liquation temperature. During sintering process, blended raw materials including such as limestone may be used. Additionally, flux material such as quartz is also used along with coke breeze as fuel. Optionally, water may be added to the iron ores and mixed with each other for granulating. The granulated mixture/ sinter mix may be then fed into sintering bed in a wet condition. During sintering, air may be sucked from a lower portion of the sintering machine underneath the sinter bed, and fuel such as coke breeze contained in the blended raw material may be burned. Therefore, fine iron ore may be melted and thus the mixture may be solidified. Later, the burning zone may be gradually shifted from the upper surface layer to the lower layer, where the charged iron ore gets sintered.

In conventional sintering process, heat deficiency at a top portion of the sinter bed is persistent, due insufficient presence of fuel materials at the top portion. Consequently, weak sinter fines are generated which leads to reduction in yield of sinter production. The heat pattern in the sintering bed of an actual sintering machine is nonuniform in the vertical direction of the bed, and there is a general tendency that the maximum temperature reached in the bed increases with increasing depth and that the temperature-fall speed slows down accordingly. During sintering process, the upper portion of the Sintering material layer is lower in the bulk temperature. Further, the total exposure time to elevated temperature or exposure to the flame by the furnace is lower when compared to the intermediate and lower portions. Consequently, the sintered ore formed in the upper portion is low in melt bonding and hence lower in mechanical strength due to reduced sintering yield. When the flame travels beneath the sinter bed, the top layer of sinter experiences the maximum amount of thermal shock. Hence the top layer of sinter is fragile.

Further, the sintering capacity is dependent on the permeability of the charge. The permeability of the charge can be increased in multiple ways. The most usual method is to increase the amount of coarse particulate return-sinter admixed with the charge. However, large quantities of coarse return-sinter increase the amount of fuel required per unit weight of final sinter and incur additional handling costs. Another method often used involves the aspect of the charge mixture being subjected to a subsequent rolling process in a drum. Although the permeability of the charge is increased to a certain extent by this method, it is necessary to control accurately the amount of moisture present, and normally the amount of water needed is significantly more than the required amount for the thermal progress of the sintering operation at the desired low level of fuel consumption. Under such circumstances, the charge produced tends to become compacted when subjected to high pressure.

Conventionally, multiple methods have been used to increase the permeability of the charge by micro-pelletizing one or more of the iron-oxide products making up the charge. However, this technique requires the provision of additional and expensive pelletizing apparatus, such as drum or pan pelletizers. Further, only extremely fine grain material can be micro-pelletized, and normally it is necessary to use a binder, together with an accurately controlled addition of water. The usage of binder may result in bogging in the lower regions of the charge during the sintering process.

Flame-front speed has a large influence on sinter quality, productivity, and sintering time. The flame-front is the region where coke particles are combusting and where coke begins to combust. However, the temperature at which coke particle starts to combust depends on size, oxygen partial pressure, volatile content, and component types in the coke. The temperature time profiles are measured by means of thermocouples embedded in the sintering bed. Conventionally, the technique of drying preliminarily the raw material mix with hot air prior to ignition has been practiced. Generally, the technique of preheating the mix with a low-oxygen air to a temperature higher than the ignition point of coke has been used. The technique aims at complete removal of the moisture content of the mix prior to ignition. The preheating is affected at 800° C. for a period of about 10 to 15 minutes. Consequently, this method requires extended preheating and use a great amount of energy as a heat source for preheating. The above-mentioned techniques that perform preliminary hearing of the mix before ignition require a long time to achieve the intended purpose, and the techniques that finishes dehydration, calcination and reduction before sintering requires a large volume of heated non-oxidative air. Therefore, the above techniques are very difficult to implement with a Dwight-Lloyd machine.

Japanese Patent Public Disclosure No. 52903/76 discloses the technique of elevating only the upper layer of the mix (the top layer 30 mm deep from the surface) to about 200-degree C. and igniting the layer with reduced thermal impact upon ignition. But this technique does not pay attention to the moisture content of the mix before it is laid down on pallets or to the moisture content of every part of the mix from the top layer to bottom layer after it is laid down on the pallets. The technique intends to decrease the resistance to air permeation of the mix at the top layer to thereby enhance the productivity of the sintering process as well as to reduce the coke consumption, but it does not at all consider the possibility of improving the characteristics of the sintered ore product at high temperatures.
In conventional sintering, the overall process is carried out in downdraft suctions system wherein the moisture has tendency to get accumulate at the bottom of the sinter bed and hence affects the sinter bed permeability and further process of sintering.
The present disclosure is directed to overcome one or more limitations stated above or any other limitations associated with the conventional arts.

The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

SUMMARY OF THE DISCLOSURE

One or more shortcomings of the prior art are overcome by an assembly and a method as disclosed and additional advantages are provided through the assembly and the method as described in the present disclosure.

Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In a non-limiting embodiment of the disclosure, a system for removing moisture from a sinter bed is disclosed. The system includes at least one furnace positioned over the sinter bed, where the at least one furnace is configured for sintering. The at least one suction device is positioned below the sinter bed and is configured to draw air from the sinter bed. Further, at least one flow creation device is positioned proximal to the sinter bed where, the at least one flow creation device is configured to direct hot air through the sinter bed. An updraft flow of the hot air is generated by the at least one flow creation device which sinters the sinter bed.

In an embodiment of the disclosure, at least one flow creation device is positioned below the sinter bed and is configured to direct hot air through the sinter bed from bottom of the sinter bed to the atmosphere.

In an embodiment of the disclosure, at least one solenoid is connected to the at least one flow creation device to induce the updraft flow of the hot air in a sinusoidal wave form through the sinter bed.

In an embodiment of the disclosure, the at least one furnace ignites the sinter bed at a rate of 10 mm/min to 30 mm/min for the siter bed height ranging from 500 mm to 600 mm.

In an embodiment of the disclosure, the sinter bed is categorized into a wet zone, a drying zone, a reaction zone, and a cooling zone.

In an embodiment of the disclosure, thickness of the wet zone is smaller than the thickness of the drying zone, the reaction zone, and the cooling zone.

In an embodiment of the disclosure, overall temperature of the sinter bed ranges from 1290 ºC to 1310 ºC.

In an embodiment of the disclosure, the hot air directed from the at least one flow creation device, traverses from a bottom portion of the sinter bed to a top portion of the sinter bed.

In an embodiment of the disclosure, the evaporated moisture traverses to the bottom portion of the sinter bed and condenses in the bottom portion of the sinter bed.

In an embodiment of the disclosure, solenoid includes a valve that is configured to open and close at a pre-determined frequency for inducing the sinusoidal wave form to the hot air directed from the at least one flow creation device.

In an embodiment of the disclosure, the valve in the solenoid is operated at the pre-determined frequency ranging from 30 seconds to 40 seconds.

In an embodiment of the disclosure, the valve in the solenoid is operated at 30% to 60% and at a rate of 30 seconds to 40 seconds for inducing the sinusoidal wave form to the air from the at least one flow creation device.

In an embodiment of the disclosure, the air is directed from the at least one flow creation device at time intervals of 1 minute.

In an embodiment of the disclosure, the pressure of the air directed from the at least one flow creation device ranges from 200 mm of water column to 600 mm of water column.

In an embodiment of the disclosure, the temperature of the air directed from the at least one flow creation device ranges from 70 ºC to 100 ºC.

In a non-limiting embodiment of the disclosure, a method for sintering a sinter bed is disclosed. The method includes the aspect of directing a hot air to the sinter bed by at least one flow creation device positioned proximal to the sinter bed.

It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

The novel features and characteristics of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives, and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

Fig. 1 is a schematic representation of a system for sintering iron ore, in accordance with an embodiment of the present disclosure.

Fig. 2, Fig. 3, and Fig. 4 illustrates step-by-step process of sintering the iron ore, in accordance with an embodiment of the present disclosure.

Fig. 5, Fig. 6, and Fig. 7 illustrates schematic view of sinter bed, formed by system/process of the present disclosure, in accordance with an embodiment of the present disclosure.

Fig. 8. is a magnified view of the sinter bed, in accordance with an embodiment of the present disclosure.

Fig. 9. Illustrates a bar graph of moisture analysis of top portion in the sinter bed with varying pressure and time, in accordance with an embodiment of the present disclosure.

Fig. 10. Illustrates a bar graph of moisture analysis of middle portion in the sinter bed with varying pressure and time, in accordance with an embodiment of the present disclosure.

Fig. 11. Illustrates a bar graph of moisture analysis of bottom portion in the sinter bed with varying pressure and time, in accordance with an embodiment of the present disclosure.

Fig. 12. Illustrates a graph indicative of a comparison of tumbler index for the sinter bed, in accordance with an embodiment of the present disclosure.

Fig. 13. Illustrates a graph indicating a comparison of sinter return fines, in accordance with an embodiment of the present disclosure.

Fig. 14. Illustrates a graph indicating a comparison of sinter time for the sintering process, in accordance with an embodiment of the present disclosure.

Fig. 15. Illustrates a graph indicating a comparison of burn through temperature, in accordance with an embodiment of the present disclosure.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the system for illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION

The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other devices for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the scope of the disclosure. The novel features which are believed to be characteristic of the disclosure, as to its organization, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will be described below. It should be understood, however that it is not intended to limit the disclosure to the form disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.

The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a system that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such mechanism. In other words, one or more elements in the device or mechanism proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the mechanism.

The following paragraphs describe the present disclosure with reference to Figures. 1 to 15. In the figures, the same element or elements which have similar functions are indicated by the same reference signs. For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to specific embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended, such alterations and further modifications in the illustrated methods, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention pertains.

The following detailed description is merely exemplary in nature and is not intended to limit application and uses. Furthermore, there is no intention to be bound by any theory presented in the preceding background or summary or the following detailed description. It is to be understood that the disclosure may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices or components illustrated in the attached drawings and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions or other physical characteristics relating to the embodiments that may be disclosed are not to be considered as limiting, unless the claims expressly state otherwise. Hereinafter, preferred embodiments of the present disclosure will be described referring to the accompanying drawings. While some specific terms directed to a specific direction will be used, the purpose of usage of these terms or words is merely to facilitate understanding of the present invention referring to the drawings. Accordingly, it should be noted that the meanings of these terms or words should not improperly limit the technical scope of the present invention.

Fig. 1 illustrates a schematic view of a system (100) for sintering iron ore, before the iron ore is fed into a blast furnace. The system (100) includes a plurality of feeding stations [not shown]. Each of the plurality of feeding stations may be configured to proportionately feed raw materials onto a sinter bed (2). In an embodiment, the raw materials may be a mixture of iron ore fines, limestone fines with solid fuel [anthracite coal/coke fines], and sinter return fines. Water or binder such as lime fines may be sprayed with the raw materials to form a wet granulated mixture [this mixture of material may be referred to as a green sinter]. The sinter bed (2) of the system (100) may include the green sinter (2a). The sinter bed (2) may be disposed on a pallet car [not shown]. The pallet car may be disposed such that, it may move in a forward direction and the sinter bed (2) accommodated on the pallet car may also move forward along with the pallet car. The pallet car may be configured with a first roller (6a) and a second roller (6b) on either end. The first roller (6a) and the second roller (6b) facilitate the forward movement of the pallet car. As apparent from Fig. 1, the system (100) may include at least one furnace (1) [herein after referred to as the furnace], which may be configured to generate a flame in the sinter bed (2). In other words, the sinter bed (2) moving on the pallet car may come under the at least one furnace (1). The sinter bed (2) may be categorized into a top portion (13), a middle portion (14) and a bottom portion (15). Further, the top portion (13) of the sinter bed (2) gets ignited and flames may be generated in the sinter bed (2). In an embodiment, the system (100) may include a plurality of wind boxes (7) positioned below the sinter bed (2). The plurality of wind boxes (7) may be configured to create a suction force. This suction force may cause the air (3a) to be extracted through the sinter bed (2), which may cause the flame to travel through the sinter bed (2) from the top portion (13) towards the bottom portion (15) of the sinter bed (2). In an embodiment, the plurality of wind boxes (7) may be fluidly coupled to the at least one suction device (3) through a manifold (8) as shown in Fig. 1. The suction device (3) may draw out or pull air (3a) from the sinter bed (2) through the plurality of wind boxes (7). The flames from the furnace (1) ignites the green sinter (2a) in the sinter bed (2) and the green sinter (2a) is converted to fired sinter (2b).

The system (100) also includes at least one flow creation device (4) [herein referred to as flow creation device] that is configured to remove moisture from the sinter bed (2). The flow creation device (4) may be connected to at least one solenoid (5) [hereinafter referred to as the solenoid] through a manifold (8). The flow creation device (4) may be configured to create a positive flow of air (4a) or may blow air (4a) that is directed to the solenoid (5) through the manifold (8). The solenoid (5) may include a valve and the valve may be configured to create an updraft wave or may induce oscillatory motion to the flow of the air (4a). The valve in the solenoid (5) may be configured to open and close at a pre-determined frequency. The opening and closing of the valve in the solenoid (5) may be controlled by an external circuit. The circuit may be provided with adjustable knobs to set the on and off times of the valve. When the valve is closed, no pulsating effect is induced, or no oscillatory flow is induced to the air (4a).

When the valve is opened, the atmospheric pressure lowers the pressure drop inside the solenoid (5). Consequently, opening and closing of the valve at a particular frequency gives the pulsating or oscillate effect to the air from the flow creation device (4). The valve in the solenoid (5) may be operated such that the air (4a) is induced with a sinusoidal waveform or oscillatory motion. This oscillating flow of air may further be directed to the sinter bed (2). The oscillating flow of air (4a) evaporates most of the moisture from the sinter bed (2) with minor thickness or presence of moisture on the top of the sinter bed (2). The above illustrated set up of the solenoid (5) with the flow creation device (4) may be configured before the furnace (1). As seen from Fig. 1, the furnace (1) is configured on the sinter bed (2) at one particular length of the sinter bed (2). The solenoid (5) and the flow creation device (4) may be configured to lie before the furnace (1) such that the green sinter (2a) in the sinter bed (2) is subjected to the oscillate flow of air before being exposed to the flame from the furnace (1).

The working of the system (100) is explained below with reference to Fig. 2 to Fig. 7. The working of the system (100) is herein explained by means of an example with the sinter bed (2) height of 600 mm. The height of the sinter bed (2) or other operational parameters must not be considered as a limitation since, the operational parameters may be varied based on the required output of the sinter. Initially, iron ore fines for sintering are prepared by blending the iron ore fines with coke, limestone and return sinter fines. This mixture [green sinter] is pre-agglomerated by mixing with water. Consequently, fine materials (the adhering particles) are coated onto coarser materials (the nucleus particles). Thus, the mean diameter of the green sinter (2a) is increased by forming granules or quasi-particles. Increase in mean diameter of the green sinter (2a), improves the permeability of sinter bed (2). In this particular embodiment, the green sinter (2a) may include a mixture of iron ore fine, limestone fine, lime fines and coke breeze along with MgO source material like olivine and pyroxenite. The green sinter (2a) may include moisture in the range of 6% -8%.

With reference to Fig. 2 and Fig. 5, air (4a) is initially directed from the flow creation device (4) to the solenoid (5). The valve in the solenoid (5) is operated at the pre-determined frequency and the solenoid (5) induces an oscillatory flow to the air (4a) from the flow creation device (4). The air (4a) is directed to the sinter bed (2) through the manifolds (8). Further, the sinter bed (2) is herein categorized into the top portion (13), the middle portion (14) and the bottom portion (15). A plurality of thermocouples (17) [hereinafter referred to as the thermocouples] may be configured at multiple locations including but not limited to the top portion (13), the middle portion (14) and the bottom portion (15) of the system (100) for measuring and monitoring the temperature of the sinter bed (2). The thermocouples (17) may also be configured to measure the temperature of the air (4a) that is being directed to the sinter bed (2). Initially, the updraft wave of air (4a) or the oscillate flow of air (4a) across the packed sinter bed (2) allows the moisture to travel through the green sinter (2a) towards the top portion (13) of the green sinter (2a). The valve in the solenoid (5) is operated at the pre-determined frequency ranging from 30 seconds to 40 seconds. Further, the valve in the solenoid (5) is operated at 30% to 60% and at a rate of 30 seconds to 40 seconds for inducing the sinusoidal wave form to the air from the at least one flow creation device (4). The flow creation device (4) is operated at time intervals of 1 minute. In this particular embodiment, the flow rate of the air (4a) that is directed to the sinter bed (2) may range from 200 water column -600 mm water column. The overall time of exposure of the green sinter (2a) to the hot air is a controlling parameter of overall decrease in the moisture content of the sinter bed (2).

The sinter bed (2) permeability may be measured and denoted by a Japanese permeability unit (JPU). The permeability of the sinter bed (2) may be measured by the below indicated equation 1.

Based on the calculated permeability of the sinter bed (2), the pulsating flow of air (4a) from the solenoid (5) and the flow creation device (4) may be varied to achieve the required moisture levels in the green sinter (2a). Further, as seem from Fig. 3 and Fig, 6, the moisture in the green sinter (2a) is removed. The moisture partially condenses along the top portion (12) of the sinter bed (2). The high temperature of the pulsating air (4a) that is blown or directed onto the sinter bed (2), dries and preheats the green sinter (2a) in the sinter bed (2). The evaporated moisture begins to condense in the top portion (13) of the sinter bed (2) when the dew point temperature of the air is reached which is typically in the range 55 °C to 65 °C.

The next step involves the aspect of subjecting the green sinter (2a) to the flame from the furnace (1). Reference is made to the Fig. 3, Fig. 4, Fig. 6, and Fig. 7. As the pellet car moves forward, the sinter bed (2) is exposed to the furnace (1). The furnace (1) may be configured to generate the flame in the sinter bed (2). The sinter bed (2) moving on the pallet car may come under the at least one furnace (1). Further, the top portion (13) of the sinter bed (2) gets ignited and flame may be generated in the sinter bed (2). The pallet car is configured to move at a speed such that the flame that ignites the sinter bed (2) progresses in the range of 10 mm/min - 30 mm/min. The temperature of the flame from the furnace (1) may be configured in the range of 1200 °C -1250 °C. Further, the sinter bed (2) may be ignited for a time period in the range of 1 minute to three minutes.

The plurality of wind boxes (7) positioned below the sinter bed (2), may create suction force. This suction force may cause the air (3a) to be extracted through the sinter bed (2), which may cause the flame to travel through the sinter bed (2) from the top portion (13) towards the bottom portion (15) of the sinter bed (2). The plurality of wind boxes (7) may be fluidly coupled to the suction device (3) which may take out or pull the air (3a) from the sinter bed (2) through the plurality of wind boxes (7). Subsequent to the ignition of the sinter bed (2), the wind boxes (7) and the suction device (3) may create the suction of the air (3a) from the sinter bed (2) in the range of 1200 water column – 1300 water column. Further, the temperature of the air (3a) that is drawn through the suction device (3) may be monitored through the thermocouples (17). Once, the temperature of the air (3a) reaches a pre-determined limit, the suction device (3) may be stopped, and the sinter bed (2) may be allowed to cool to room temperature. The flame from the furnace (1) ignites the green sinter (2a) in the sinter bed (2) and the green sinter (2a) is converted to the fired sinter (2b) as seen from Fig. 8. The absence of the moisture in the sinter bed (2) due to the pulsating flow of hot air through the sinter bed (2), reduces the overall load on the sintering process and heat requirement to dry and ignite the green sinter (2a) in the sinter bed (2). Subsequent to the generation of fired sinter (2b), the pellet car may be configured to partially tilt. The fired sinter (2b) may be configured to fall on a spike crusher. The fired sinter (2b) is crushed by the spike crusher and is transported to a sinter cooler. The cooled sinter of acceptable quality may further be used in a blast furnace and the sinter of sub-par quality may be re-cycled.

Fig. 8. is a magnified view of the sinter bed (2) with multiple zones. The sinter bed (2) may include a wet zone (8), a drying zone (9), a reaction zone (10) and a cooling zone (11). The wet zone (8) of the sinter bed (2) may lie at a temperature lower than 100°C and may include condensed moisture. The wet zone (8) of the sinter bed (2) subsequent to the sinter bed (2) being exposed to the pulsating air (4a) may lie along the top portion (13) of the sinter bed (2). The drying zone (9) of the sinter bed (2) may lie in the temperature ranging from 100 °C and 500 °C. The drying zone (9) is the region where the vaporization of moisture takes place and subsequent dehydration of hydroxides takes place. Further, the maximum temperature of the reaction zone (10) ranges from w1300 °C - 1480 °C. Multiple reactions occur in the reaction zone (10) and the reactions are coke combustion (exothermal), carbonates decomposition (endothermal), solid phase reactions, reduction, re-oxidation of iron oxides and reactions of formation of the sintered mass. Lastly, the cooling zone (11) lies immediately after the reaction zone (10). The cooling and re- crystallization of the fired sinter (2b) takes place in the cooling zone (11). The sinter bed (2) is also defined by a flame front portion (12). The portion where the flame directly impacts the sinter bed (2) may herein be defined as the flame front portion (12). As clearly seen from Fig. 2, the thickness of the wet zone (8) is significantly lesser due to the reduction in moisture by the pulsating air (4a) from the solenoid (5).

Example and experimental study:

Embodiments of the present disclosure will now be described with an example of particular compositions of raw materials. Experiments have been carried out for a specific composition of raw materials, subjected to conventional sintering process and sintering process of the present disclosure.

In this example, 10 sets of sinter pot tests were made to simulate the conventional sintering method as well as method proposed in the present disclosure. Effect of proposed method of partial updraft drying sintering by changing the direction of the flow creation device (4) in the drying zone (9) of the sinter bed (2) before ignition the sinter bed (2) is studied. Further, sinter process parameters and physical properties was also established and forming the wave or oscillate flow of air is also established.

Table 1: - Chemistry of raw materials
Material T. Fe CaO SiO2 MgO Al2O3 FeO LOI
Iron ore fines 62.93 0.00 0.08 0.01 2.58 2.77 3.36
Pyroxenite 5.26 0.00 39.43 50.12 1.25 0.65 1.57
Lime Fines 0.17 68.90 2.12 0.56 1.31 0.56 27.54
Limestone 0.00 45.25 5.62 7.49 2.12 -- 48.25
Dolomite 0.83 36.35 2.14 18.62 4.00 0.67 43.65
Coke breeze -- 12.5 0.24 5.2 -- 79.22

Iron ore used for sinter base mix preparation was first screened at -10 mm fraction. These materials were then mixed is preferred proportion in such the way that the basicity (CaO/SiO2) around 2.6. The material is mixed in a granulating drum along with moisture ranging from 6 % - 8 %. The green sinter (2a) was produced having mean particle size of 2 mm – 3 mm. 10 sets of pot grate sintering test were taken where the normal green sinter (2a) was made without giving any partial updraft drying in downward suction (negative suction).

The green sinter (2a) was made with target chemistry i.e., the basicity (CaO/SiO2) of 2.3 and MgO at 1.9 %. The Coke rate in all set of trials was kept constant at 6.5 %. The bulk density of green sinter (2a) in 600 mm pot is maintained around 1.8 g/cc to 2 g/cc while in normal sintering it is in the range of 2.2 g/cc - 2.4 g/cc. The sinter of 100 kg was mixed in mixer drum and moisture was also added to convert the fines into micro ball having mean particle size of 2.5 mm to 3 mm. The green sinter (2a) was then transferred to pot sinter. The initial suction rate and the ignition flame temperature for firing the sinter in sintering process was kept constant at 1200 mm of water column and at 1100 0C respectively. While in remaining pot test (9 numbers) the pressure and time period are shown in the below table 2.
Table 2: - Design of experiment for Pot Test Trials

Trial Nos
Process
1 Normal sintering
2 Updraft sinter with 200 mm of water column, 1 minutes
3 Updraft sinter with 200 mm of water column, 2 minutes
4 Updraft sinter with 200 mm of water column, 3 minutes
5 Updraft sinter with 400 mm of water column, 1 minutes
6 Updraft sinter with 400 mm of water column, 2 minutes
7 Updraft sinter with 400 mm of water column, 3 minutes
8 Updraft sinter with 600 mm of water column, 1 minutes
9 Updraft sinter with 600 mm of water column, 2 minutes
10 Updraft sinter with 600 mm of water column, 3 minutes

The valve in the solenoid (5) in opened and the suction is normally as in initial stage of the sinter. During normal sintering, the suction pressure across the sinter bed (2) is gradually decreased because of melt formation in the sinter bed (2) and hence it affects the bed permeability which in turn reduce the negative pressure in the sinter bed. During subsequent wave form flow, the positive pressure drops to the magnitude level of 500 mm of water column - 600 mm of water column depends on the position of valve in the solenoid (5) (30% or 60 % closed). During sintering process, the time to complete the sintering process was noted i.e., after achieving the burn through temperature of sinter bed (2) (maximum temperature of waste air). The fired sinter (2b) was then removed and stabilized by dropping the whole mass of the fired sinter (2b) for 4 times from 2-meter height. After subsequently, - 5 mm fraction of sinter fines was removed and weighed. The remaining sinter was further screened in size range - 40 mm to + 10 mm for tumbler test. The sinter is then tested for microstructural analysis. During sintering process, the top temperature of sinter bed (2) was measured to note the thermal behavior of the sinter bed (2).

As shown in the above table 2, the updraft flow of air is carried out across the sinter bed (2). The temperature of the air (4a) is maintained around 80 ºC - 100 ºC. In order to estimate the effect of partial updraft wave or oscillate flow of hot air (4a), the moisture analysis is carried out at different portions of sinter bed (2) i.e., the top portion (13), the middle portion (14) and the bottom portion (15). The moisture analysis is shown in the Fig. 9 - 11. The valve in the solenoid (5) is operated at the rate of 30 % - 60 % of the total valve opening and at the rate of 30 sec - 40 sec for each cycle. The updraft oscillated flow of method used in present experiment is carried out at the frequency level of 30 % and 60 % i.e., more pressure drop is observed at the valve closing of 60%.

It was found that the with increasing the updraft pressure and time, more moisture is saturated on the top portion (13) of the sinter bed (2). This phenomenon helps in removing the moisture from bottom portion (15) to the top portion (13) and then to the atmosphere on further ignition of the top portion (13). Upon ignition of the sinter bed (2), the flame travel through the top portion (13) to the dried middle portion (14) and the bottom portion (15).

As shown in the below table 3, the permeability of sinter bed (2) is measured by using anemo-meter device. The permeability is the measure of the flow rate of sucking air (3a) across the sinter bed (2). Owing to updraft flow of the air, more space is created in the sinter bed (2) which increases the bed permeability and reduces the charge density before ignition of the sinter bed (2).

Table 3: - Permeability of sinter bed (JPU)
Updraft Pressure JPU of bed
Time in minutes
1 2 3
200 mm of water column 42 44 48
400 mm of water column 52 57 62
600 mm of water column 54 59 62

Table 4: - Time interval distribution of thermocouple embedded in sinter bed
Time above 1200 ºC, minutes
Process Bed thermocouple1 Bed Bed thermocouple3 Total time
thermocouple 2
Normal sintering not reach the temp 2 7 9
Updraft sinter with 200 mm of water column, 1 minutes 1 4 4 9
Updraft sinter with 200 mm of water column, 2 minutes 2 5 5 12
Updraft sinter with 200 mm of water column, 3 minutes 2 5 5 12
Updraft sinter with 400 mm of water column, 1 minutes 3 5 4 12
Updraft sinter with 400 mm of water column, 2 minutes 3 5 5 13
Updraft sinter with 400 mm of water column, 3 minutes 4 5 5 14
Updraft sinter with 600 mm of water column, 1 minutes 5 6 4 15
Updraft sinter with 600 mm of water column, 2 minutes 5 7 6 18
Updraft sinter with 600 mm of water column, 3 minutes 6 7 6 19

It is found that at lower bulk density of green sinter (2a), the fired sinter density is also maintained/improved with increased porosity. The fired sinter (2b) density was found to be 3-3.6 g/cc against 3.1-3.3 g/cc in normal sintering process.

The results of the test are provided in the Fig. 12 to Fig. 15 and the same are described below.

With reference to the Fig. 12, it was found that partial updraft sintering process of the present disclosure, helps in increasing the tumbler index of sinter to 5-6 points which increases the magnitude of pressure and time. The updraft helps in maintaining the flame temperature and speed. The updraft also enables the flame front to cover the entire section of sinter smoothly at lower time. Consequently, strong sinter is produced at top portion (13) of the sinter (around 300-400 mm of total bed of 600 mm). The retention of sinter at higher temperature for more than 5 minutes - 6 minutes allows the formation of SFCA/SFCA-I and primary hematite phase which is beneficial for increasing the tumbler strength of the iron ore sinter.

With reference to the Fig. 13, when the flame travels beneath the sinter bed (2), the top portion (13) of sinter bed (2) experiences the maximum amount of thermal shock. The temperature drop of the top portion (13) is higher in magnitude compared to the middle portion (14) and the bottom portion (15). Hence the top portion (13) of the sinter bed (2) is fragile owing to results in sinter fine and the same is more crucial as per the yield of sinter plant is considered. The partial pressure of oxygen is also high at the top portion (13) and hence the coke burns at faster rate in top portion (13) as compares to the middle portion (14) and the bottom portion (15). The excess available oxygen in top portion (13) results in conversion of hematite, and so the top portion (13) is porous and fragile. Around 20 % - 30 % of the total sinter bed (2) is unusable owing to its fragile nature and hence it is always reported as return sinter fines (-5mm). In the present disclosure the percentage of return fines of sinter is largely reduced to 5 % - 7 % and hence it helps in increasing the productivity. As the maximum moisture get driven from bottom portion (15) to the top portion (13), the permeability of sinter bed (2) is suddenly increased to the higher values and hence the flame travels at higher speed and the time of sinter are largely influenced. Consequently, the time of sinter is reduced to the range of 4 minutes - 6 minutes of total sinter time.

With reference to Fig. 15, the burn through temperature is also increased in trial no 8, 9 and 10 owing to maximum moisture removal from the sinter bed (2) to the atmosphere due to the partial updraft flow of air to the atmosphere.

It is also concluded from the pot test trials that the best combination is found out at 600 mm of water column at 2 minutes - 3 minutes. Such combination is used to carry out the pot test trial at lower coke rate 5.5 % in sinter base mix against 6.5% and it was found out that the tumbler index, sinter return fines and sintering time is more or less comparable with sinter made with 6.5% coke rate. Hence the coke rate can be easily reduced in partial updraft flow sintering process in the present disclosure. The below Table 4 shows the results with low coke rate at 5.5% in sinter mixture.
Table 4: - Pot sinter trials at 5.5% Coke rate in sinter mixture
Process
Tumbler index Return fines Sintering Time burn through temperature
Normal sintering 68 24.65 23 245
Updraft sinter with 600 mm of water column 1 mints 72.15 21 18 282
Updraft sinter with 600 mm of water column 2 mints 72.21 19 17 290
Updraft sinter with 600 mm of water column 3 mints 72.97 18 17 291

In an embodiment, the updraft flow of air or the oscillate wave form of the air induced by the solenoid (5) removes moisture from the sinter bed (2). In an embodiment, the solenoid (5) and the flow creation device (4) induce a positive flow of air with pulsating effect which removes the moisture from the sinter bed (2). This dried sinter bed (2) is very well permeable and is of a lower charge density which allow the air to pass through the bed uniformly.

In an embodiment, the flame can be broader as compared to normal sintering process. The area under the temperature distribution graph across the sinter bed is more which also enables the sinter to remain at higher temperature for longer period of time.

Equivalents:

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system (108) having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances, where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system (108) having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.” While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Referral Numerals:

Referral numeral Description
1 Furnace
2 Sinter bed
2a Green sinter
2b Fired sinter
3 Suction device
4 Flow creation device
5 Solenoid
6a, 6b Rollers
7 Wind box
8 Wet zone
9 Drying zone
10 Reaction zone
11 Cooling
12 Flame front
13 Top portion
14 Middle portion
15 Bottom portion
16 Hearth
17 Thermocouple
100 System