Patent Grant
7402191
The present invention relates to a manufacturing method of a material for sintering that is used when sintered ores for a blast furnace are manufactured by use of a Dwight-Lloyd type sintering machine of downward suction system, and a manufacturing apparatus thereof.
Sintered ores that are used as a material for blast furnaces are generally manufactured by undergoing a treatment process of a sintering material as shown below. As shown in
The blended material including the granulated products is charged on a pallet of a Dwight-Lloyd sintering machine with an appropriate thickness of, for instance, 500 to 700 mm, a solid fuel at a surface thereof is ignited, after the ignition, the solid fuel is combusted with air sucking downwardly, and, by the combustion heat, the blended sintering material is sintered to be a sintered cake. The sintered cake is pulverized and screened, and thereby sintered ores having a particle size larger than a predetermined diameter are obtained. On the other hand, ores having a particle size smaller than the predetermined diameter are returned and used again as the sintering material.
The reducibility of the sintered ore product thus manufactured is, as so far pointed out, a factor that largely controls an operation particularly of the blast furnace. Ordinarily, the reducibility of the sintered ores is defined according to JIS M8713 (JIS: Japanese Industrial Standard, hereinafter referred to as JIS), and here the reducibility of the sintered ores is denoted with JIS-RI.
As shown in
The gas utilization factor (ηco) and the fuel ratio are defined as follows.
Gas utilization factor (ηco)=CO2 (%)/(CO (%)+CO2 (%))
Here, CO2 (%) and CO (%) each mean volume % in a furnace top gas of the blast furnace.
Fuel ratio=(amount of coal+coke used (kg))/amount of pig (1 ton)
Furthermore, the cold strength of the sintered ore product thus manufactured is also an important factor for securing the ventilation in the blast furnace. In the individual blast furnaces, the lower limit of the cold strength is set and operated. Accordingly, the sintered ores preferable for the blast furnace are one that is excellent in the reducibility and high in the cold strength. In Table 1, the reducibility and the tensile strength of four main ore textures that constitute the sintered ores, that is, calcium ferrite (CF): nCaO.Fe2O3, hematite (He): Fe2O3, calcium silicate containing FeO (CS): CaO.xFeO. ySiO2, and magnetite (Mg): Fe3O4 are shown. As shown in Table 1, one that is high in the reducibility is hematite (He) and one that is high in the tensile strength is calcium ferrite (CF).
The desired sintered ore structure that the invention intends is, as shown in
However, so far, as mentioned above, the iron ore M1, SiO2-containing material M2, limestone base powdery material M3 and solid fuel type powdery material M4 are simultaneously mixed and granulated. Accordingly, as shown in
In this connection, so far, various methods have been tried so as to produce much calcium ferrite (CF) and hematite (He). For instance, calcium silicate (CS) is produced a lot when the sintering is carried out at high temperatures. Accordingly, in Japanese Unexamined Patnt Application Publication No. 63-149331, a technology is proposed in which powdery iron ore, together with a binder and limestone, is granulated followed by coating powdery coke that is a heat source on a surface to improve the combustibility of coke, this is sintered at low temperatures and thereby the reducibility is improved.
However, according to the conventional method proposed in Japanese Unexamined Patnt Application Publication No. 63-149331, since CaO and SiO2 in the iron base material or SiO2 base material are in proximity to each other, calcium silicate (CS) is inevitably produced much. Accordingly, in many cases, a structure mainly including calcium ferrite (CF) and hematite (He) is not necessarily obtained.
Furthermore, Japanese Unexamined Patnt Application Publication No. 63-69926 proposes a technology in which after powdery iron ore and/or returned ore is mixed, to the mixed powdery iron ore and/or returned ore limestone, powdery coke and auxiliary raw materials such as scale and silica rock are added to form pseudo particles, thereby the powdery coke can be deposited much on an outer periphery portion of the pseudo particle, thereby the combustion speed of the powdery coke is accelerated, resulting in shortening the combustion time.
However, according to the conventional method proposed in Japanese Unexamined Patnt Application Publication No. 63-69926, since limestone and silica rock in the auxiliary raw materials are present together, calcium silicate (CS) weakest in the tensile strength is produced a lot, resulting in fragile sintered ores low in the strength.
Still furthermore, Japanese Unexamined Patnt Application Publication No. 11-241124 discloses a method of manufacturing low SiO2 sintered ores in which, after iron ore powder, returned ores, part or whole of calcined lime and limestone and part or whole of SiO2 source material are mixed and granulated by use of a primary mixer, powdery coke divided from another system and the slug source such as silica rock and lime are added to the mixed and granulated material followed by granulating by use of a secondary mixer, thereby on a surface portion of the granulated particle a layer of powdery coke and slug source is formed, and thus obtained material is sintered to obtain the low SiO2 sintered ores.
However, according to the technology disclosed in Japanese Unexamined Patnt Application Publication No. 11-241124, in an exterior coating portion of the granulated particle (that is, one corresponding to a pseudo-particle of the invention), the low SiO2-containing material is likely to enter. Thereby, calcium silicate (CS) lowest in the tensile strength among constituent ores of the sintered ore as shown in Table 1 is formed, resulting in lowering the Chatter Index or the Tumbler Index that denotes the cold strength. Furthermore, inside of the granulated particle, the material partially containing limestone enters; accordingly inside of the sintered ore, not only hematite (He) high in the reducibility but also calcium ferrite (CF) inferior in the reducibility to hematite (He) and calcium silicate (CS) much inferior in the reducibility to the hematite (He) are formed; as a result, a dramatic improvement effect in the reducibility cannot be obtained.
Furthermore, Japanese Unexamined Patnt Application Publication No. 61-163220 discloses a pre-treatment method of the sintering material. In the method, a sintering material, in which, pellet is mixed while the humidity therein is controlled, is mixed by use of a primary mixer and subsequently, powdery coke is added to the humidity-controlled and granulated substance which is then subjected to rollintg granulation by use of a secondary mixer.
However, according to the technology disclosed in Japanese Unexamined Patnt Application Publication No. 61-163220, since the material containing limestone enters inside of the pseudo particles, inside of the sintered ores, not only hematite (He) high in the reducibility but also calcium ferrite (CF) inferior in the reducibility to hematite (He) and calcium silicate (CS) remarkably inferior in the reducibility to the hematite (He) are formed. Accordingly, not only the dramatic improvement effect of the reducibility cannot be obtained, but also in the outside of the sintered ore where the cold strength has to be secured, calcium silicate (CS) lowest in the tensile strength among the ingredient ores of the sintered ore is formed, resulting in decreasing in the Chatter Index or the Tumbler Index that denotes the cold strength.
As disclosed in Japanese Unexamined Patnt Application Publication Nos.61-163220, 63-69926 and 11-241124, in the pre-treatment method or manufacturing method of the sintering material in which with the primary and secondary mixers, the mixing and granulation are carried out, fundamentally the primary mixer performs the mixing and granulation mainly consisting of the mixing of the sintering material, and thereafter, the secondary mixer carries out the granulation. When there are the primary and secondary mixers like this (when there are two mixers in total), ordinarily, for the mixing and granulation of the sintering material in the primary mixer, substantially 120 seconds are secured, and for the granulation in the secondary mixer, substantially 180 seconds are secured.
Furthermore, as to the additional coating of powdery coke and limestone, in Japanese Unexamined Patnt Application Publication No.2002-285250, an applicant the same as the present invention discloses a manufacturing method of a sintering material that the present invention intends to obtain. That is, there is proposed a granulation method in which by additionally coating powdery coke and limestone, so-called three-layer pseudo particles are obtained. The additional coating of powdery coke and limestone intends to deposit an auxiliary raw material including the additionally coated powdery coke and limestone on a surface of the pseudo particle. Thereby, to the pseudo particle with a first layer of a coarse particle and a second layer of fine particles surrounding the coarse particle, on a surface layer of the pseudo particle a third layer rich in powdery coke and limestone is formed, and thereby the reducibility JIS-RI value of the sintered ore can be improved.
However, even in the Japanese Unexamined Patnt Application Publication No. 2002-285250, it was found that when powdery coke and limestone were additionally coated in the course of granulation, in the drum mixer, other than an action of forming the pseudo particles owing to rolling of the drum mixer, breaking down of the pseudo particles was repeated in the course of the rolling; in this breaking down process, powdery coke and limestone were contained inside of the pseudo particles; as a result, powdery coke and limestone could not be coated on the surface of the pseudo particles.
Furthermore, in Japanese Unexamined Patnt Application Publication No. 2002-285250, powdery coke and limestone are additionally coated by inserting a belt conveyer into a drum mixer to add.
However, the aditional coating method described in Japanese Unexamined Patnt Application Publication No. 2002-285250, in particular a method that uses a belt conveyer has the following disadvantages. That is, deposit adhered to an inner wall of the drum mixer in the course of the granulation of the material for sintering falls down on the belt conveyer to adhere to and deposit on the belt conveyer. In order to remove the accretion and deposit, it takes a lot of labor. Furthermore, in some cases, a driving part of the belt conveyer is damaged and an operation is interrupted. Still furthermore, when the accretion on the belt conveyer becomes too large, the accretion comes into contact with the inner wall of the drum mixer, or the belt conveyer is bent owing to a weight of the accretion to come into contact with the inner wall of the drum mixer. It was found that such a contact of the inner wall of the drum mixer and the accretion gave rise to a large damage onto the inner wall of the drum mixer, other than the interruption of the operation was caused, there was a large problem also from the viewpoint of safety.
Furthermore, Japanese Unexamined Patnt Application Publication No. 58-189335 discloses another additional coating method. According to the method, over a region from an intermediate portion in a direction in which material in the drum mixer flows to an ore exhaust side (exhaust side), an air stream is used to inject and add from the exhaust side.
However, according to the method disclosed in Japanese Unexamined Patnt Application Publication No. 58-189335, equipment expense for an air stream generator that additionally coats auxiliary raw materials, apparatus for transferring additional coating additives and injection equipment becomes enormous. Furthermore, to a portion that is inside of the drum mixer of the injection equipment, the accretion falls from the inner wall of the drum mixer or dust powder adheres to apparatus portion, resulting in disturbing a smooth operation. Furthermore, according to the method, since the additional coating material is injected and added toward a charge side of the drum mixer by the air stream, the additional coating material is widely scattered within the drum mixer and reaches to the charge side of the drum mixer. As a result, a problem is caused in that since such auxiliary raw material that were scattered up to the charge side are contained in the sintering material in the course of granulation in the drum mixer, the intention of depositing the additional coating auxiliary raw material on the pseudo particle surface cannot be realized.
Still furthermore, a still another additional coating method is proposed in Japanese Unexamined Patnt Application Publication No. 2002-20820. According to the method, in a predetermined region on a sintering material charge side in the drum mixer, by making use of an air stream, a binder consisting limestone powder and hydrated lime and so on is dispersed and added.
However, even according to the method disclosed in Japanese Unexamined Patnt Application Publication No. 2002-20820, since a portion of the apparatus that projects the additional coating auxiliary raw material is always inside of the drum mixer, dust powder (calcined lime and so on) in the drum mixer adheres and solidly sticks to the portion of the apparatus and disturbs the operation. Accordingly, the maintenance operation that periodically interrupts the operation and pulls the portion of the apparatus out to remove the accretion is necessary. However, in the maintenance operation, since it is difficult to pull out the portion of apparatus, the maintenance operation takes a lot of time.
Furthermore, similarly to the Japanese Unexamined Patnt Application Publication No. 58-189335, the additional coating auxiliary raw material is widely scattered in the drum mixer and reaches up to the charge side of the drum mixer. The auxiliary raw material scattered up to the charge side is taken in the sintering material in the course of the granulation by the drum mixer, accordingly there is a problem in that the additional coating auxiliary raw material cannot be deposited onto the pseudo particle surface.
The present invention was carried out to overcome the above-mentioned conventional problems and intends to provide a manufacturing method of a material for sintering that can improve the cold strength and the reducibility of the sintered ore and apparatus therefor. The inventive manufacturing method includes, as a pre-treatment of a process of manufacturing sintered ore, without necessitating huge apparatus, forming pseudo particles by granulating iron ore M1 and SiO2-containing material M2 separately from limestone base material M3 and solid fuel type material M4; and selecting a time to additionally coat limestone base material M3 and solid fuel type material M4 to gradually form pseudo particles, and thereby manufacturing sintered ore having a structure in which a layer rich in the limestone base material M3 and solid fuel type material M4 is formed on a surface portion of the pseudo particle, calcium ferrite (CF) high in the strength is generated on the surface of the sintered ore, and on the other hand toward the inside of the sintered ore, hematite (He) high in the reducibility is selectively formed.
In the present invention, iron ore of material for sintering includes coarse, powdery iron ore and returned ore that is again utilized as the sintering material, and with these generically referring as iron ore, the invention will be explained.
A first aspect of the invention for achieving the above object is a manufacturing method of a material for sintering. The manufacturing method is characterized in that when, with a Dwight-Lloyd type sintering machine of downward suction, as a pretreatment of a manufacturing process of sintered ore for use in a blast furnace, sintering material including iron ore M1, SiO2-containing material M2, limestone base powdery material M3 and solid fuel type powdery material M4 is granulated by means of a drum mixer, the sintering material excepting the limestone base powdery material M3 and solid fuel type powdery material M4 is charged from a charge inlet of the drum mixer to granulate, and, in a region disposed in the middle on a downstream side where a staying time during which the sintering material reaches up to an exhaust outlet of the drum mixer is in the range of from 10 to 90 seconds, the limestone base powdery material M3 and solid fuel type powdery material M4 are added, and thereby until reaching the exhaust outlet, the limestone base powdery material M3 and solid fuel type powdery material M4 (hereinafter in the invention, limestone base powdery material M3 and solid fuel type powdery material M4 are referred to as additional coating auxiliary raw material 8) are deposited and formed on the exterior coating portion of the sintering material.
Furthermore, a second aspect of the invention is a manufacturing method of material for sintering characterized in that, in the first aspect, the sintering material excepting the limestone base powdery material M3 and solid fuel type powdery material M4 is charged from a charge inlet of the drum mixer to granulate, and, in a region disposed in the middle on a downstream side where a staying time during which the sintering material reaches an exhaust outlet of the drum mixer is in the range of from 10 to 90 seconds, after the limestone base powdery material M3 is added, the solid fuel type powdery material M4 is added, and thereby until reaching the exhaust outlet, the limestone base powdery material M3 and the solid fuel type powdery material M4 are deposited in turn and formed on the exterior coating portion of the sintering material.
Still furthermore, a third aspect of the invention is a manufacturing method of material for sintering characterized in that, in the first and second aspects, the drum mixer is divided into a plurality of drum mixers, a final drum mixer is made to have a drum mixer length disposed so that a staying time from the charge inlet up to the exhaust outlet may be in the range of from 10 to 90 seconds.
Furthermore, a fourth invention is a manufacturing method of material for sintering characterized in that, in the first and second aspects, the drum mixer is divided into a plurality of drum mixers, in a region disposed in the middle on a downstream side where a staying time during which the sintering material reaches up to an exhaust outlet of the final drum mixer is in the range of from 10 to 90 seconds, the limestone base powdery material M3 and solid fuel type powdery material M4 are added, and thereby until reaching the exhaust outlet, the limestone base powdery material M3 and solid fuel type powdery material M4 are deposited and formed on the exterior coating portion of the sintering material.
Still furthermore, a fifth aspect of the invention is a manufacturing apparatus of a sintering material characterized in that in a manufacturing apparatus including a drum mixer by which a sintering material is, while rolling and transferring, formed into pseudo particles; and a additional coating conveyer that projects the additional coating auxiliary raw material 8 in the middle of forming pseudo particles of the sintering material into the drum mixer, on an exhaust outlet side of the drum mixer, a additional coating conveyer is disposed so that an exhaust end thereof faces the exhaust outlet of the drum mixer.
Furthermore, a sixth aspect of the invention is characterized in that, in the fifth aspect, the additional coating conveyer can control an initial speed and/or an angle of elevation of a additional coating auxiliary raw material 8 when the additional coating auxiliary raw material 8 is projected into the drum mixer.
Still furthermore, a seventh aspect of the invention is a manufacturing apparatus of a sintering material characterized in that, in the fifth aspect, movement means for moving the additional coating conveyer so that the exhaust end of the additional coating conveyer may move between a predetermined position on an exhaust outlet side inside of the drum mixer and a position outside of the exhaust outlet of the drum mixer are disposed.
Furthermore, an eighth aspect of the invention is a manufacturing apparatus of a sintering material characterized in that, in the sixth or seventh aspect, speed control means for controlling a belt speed of the additional coating conveyer is disposed, and thereby a projection initial speed of the additional coating auxiliary raw material 8 that is projected into the drum mixer is made controllable.
Still furthermore, a ninth aspect of the invention is a manufacturing apparatus of a sintering material characterized in that, in the eighth aspect, a predetermined position on an exhaust outlet side inside of the drum mixer where the exhaust end of the additional coating conveyer is located and the belt speed of the additional coating conveyer are controlled so that the projection position of the additional coating auxiliary raw material 8 may be a region disposed in the middle on a downstream side where a staying time of the sintering material until reaching the exhaust outlet of the drum mixer is in the range of from 10 to 90 seconds.
In the following, situations that led to the completion of the present invention and a gist of specific modes for carrying out the invention will be explained with reference to the drawings.
In the invention, it was found that when a time for adding in particular a limestone base powdery material M3 and a solid fuel type powdery material M4 to deposit and form on a exterior coating portion of a sintering material was set, that is, when after the limestone base powdery material M3 and solid fuel type powdery material M4 are additionally coated and added to the sintering material that is being granulated, a staying time after the addition until the sintering material reaches the exhaust outlet of the drum mixer, so-called granulation period of time (hereinafter simply referred to as “exterior coating time”) after the limestone base powdery material M3 and solid fuel type powdery material M4 are added to deposit and form on the exterior coating portion of the sintering material was set, the effect was largely different.
As shown in
As a result, as shown in
Here, a exterior coating region inside of the mixer where the exterior coating period of time is from 10 to 90 seconds corresponds to, in terms of the number of revolution of the sintering material in the drum mixer, 2 to 36 revolutions, and to 0.5 to 5 m from exhaust outlet end 35 of the drum mixer 4. However, as far as the exterior coating period of time in the mixer is controlled so as to be in the range of from 10 to 90 seconds, a dimension of the exterior coating region is not restricted to the above dimension.
In
In other words, since in the drum mixer, not only the granulation but also the destruction of the pseudo particles simultaneously proceeds, when the exterior coating period of time is set longer than necessary, the limestone base powdery material M3 and solid fuel type powdery material M4 that are added to externally coat are contained owing to the destruction of the pseudo particles and exist in both inner and outer exterior coating. It is confirmed that, as a result, sintered ore having a structure in which on the surface of the sintered ore calcium ferrite (CF) high in the strength is generated, on the other hand toward the inside of the sintered ore hematite (He) high in the reducibility is selectively formed cannot be obtained. That is, proper selection of the exterior coating period of time was found to be important.
Furthermore, as mentioned above, when the exterior coating period of time is set too short, the added limestone base powdery material M3 and solid fuel type powdery material M4 segregate in the sintering material, resulting in non-uniform sintering of the sintering material on the sintering machine. Then, the inventors investigated the exterior coating period of time that does not cause the segregation; as a result, it was found that the exterior coating period of time of 10 seconds or more was necessary. That is, there is a disadvantage in that the exterior coating period of time is under stringent condition, and simple addition of the auxiliary raw material in a later half portion in the drum mixer allows containing the auxiliary raw material inside of the pseudo particle.
When the condition on the exterior coating period of time according to the invention is satisfied, the limestone base powdery material M3 and solid fuel type powdery material M4 can be for the first time externally coated without being contained inside thereof (inner exterior coating); accordingly, a material for sintering is manufactured with, inside of the pseudo particle, the SiO2-containing material M2 separated from the limestone base powdery material M3, that is, without limestone. Thereby, CaO and SiO2 are delayed in the reaction, resulting in suppressing calcium silicate (CS) poor in the reducibility and low in the cold strength from generating.
In the invention, at the interface between the exterior coated limestone base powdery material and iron ore, a calcium ferrite (CF) system melt is formed and covers a circumference of the iron ore, resulting in exhibiting sufficient cold strength. When sintering is performed with this material for sintering, a sintered ore in which calcium ferrite (CF) high in the strength is formed on the surface of the sintered ore and hematite (He) high in the reducibility is selectively formed toward the inside of the sintered ore can be formed.
An example of granulation flow (method A) according to the invention is shown in
As mentioned above, in order to obtain the sintering material adequate for the sintered ore, an additional coating position in the drum mixer 4 of the auxiliary raw material that is the limestone base powdery material M3 and solid fuel type powdery material M4 is important. When the additional coating position of the auxiliary raw material is in a forward end portion in the drum mixer 4, since the pseudo particles that become seed particles have not been sufficiently formed and grown, additionally coated auxiliary raw material is taken into the inside of the pseudo particles. On the other hand, even when the additional coating position of the auxiliary raw material is in an intermediate portion in the drum mixer 4, since in the drum mixer 4, the granulation action (formation of pseudo particles) of the sintering material and the destruction action thereof are simultaneously proceeding, the additional coating auxiliary raw material 8 is taken into the inside of the destroyed pseudo particles. Accordingly, the object to manufacture pseudo particles having a three-layer structure with a layer rich in powdery coke in the outer-most layer cannot be achieved. Furthermore, when the additional coating position of the auxiliary raw material is too close to a back end portion in the drum mixer 4, the additionally coating auxiliary raw material does not uniformly adhere to the outer-most layer of the pseudo particles, in some cases, remains coagulated without adhering, resulting in disturbing a smooth proceeding of the sintering. Accordingly, it is better to additionally coat the auxiliary raw material in a region disposed in the middle on a downstream side where a staying time until the sintering material reaches the exhaust outlet 35 of the drum mixer is in the range of from 10 to 90 seconds.
Such additional coating can be performed by projecting the additional coating auxiliary raw material 8 from back end portion 35 of the drum mixer. However, as shown in
Subsequently, through the belt conveyer 10, the limestone base powdery material M3 (for instance, powdery limestone) and solid fuel type powdery material M4 (for instance, powdery coke) are added to a predetermined region (here, an intermediate position of the exterior coating region), and pseudo particles having a exterior coating portion where on circumference of pseudo particles formed by granulation until reaching the exterior coating region in the drum mixer 4, the limestone base powdery material M3 and solid fuel type powdery material M4 are deposited and formed are granulated. The limestone base powdery material M3 and solid fuel type powdery material M4, when an average particle size is made 1.5 mm or less and preferably 1.0 mm or less, can adhere to the exterior coating portion with ease and can cover outer surface thereof. The method A is a case where a single drum mixer is used.
Furthermore, in
In this case, from a charge inlet of the first drum mixer 4A, iron ore M1 and SiO2-containing material M2 (material containing relatively much SiO2 such as silica rock, serpentine rock, and Ni slag) excepting the limestone base powdery material M3 and solid fuel type powdery material M4 are charged. While repeating the granulation and destruction in the course until reaching from the charge inlet of the first drum mixer 4A to the exhaust outlet, with a coarse particle of iron ore M1 as a seed particle and with fine particles of iron ore and the SiO2-containing material M2 deposited on the circumference of the coarse particle of iron ore, a pseudo particle is granulated. Thereafter, when the pseudo particles are charged into a charge inlet of the second drum mixer 4B, the limestone base powdery material M3 and solid fuel type powdery material M4 that becomes a heat source are fed to a charge inlet of the second drum mixer 4B. Thereby, in the second drum mixer 4B, on the circumference of the pseudo particles, the limestone base powdery material M3 and solid fuel type powdery material M4 are exterior coated and deposited, and thereby the granulation is performed.
In
Furthermore,
According to (method A) or (method B) of the invention, with a coarse iron ore M1 as a seed particle, to the periphery thereof fine iron ore M1 and SiO2-containing material M2 can be deposited, furthermore in the periphery thereof the limestone base powdery material M3 and solid fuel type powdery material M4 (coke) that becomes a heat source can be deposited and formed to the exterior coating portion. Furthermore, according to the (method C) of the invention, when the limestone base powdery material M3 and solid fuel type powdery material M4 (coke) that becomes a heat source are deposited and formed on the exterior coating portion, the solid fuel type powdery material M4 (coke) that becomes a heat source can be deposited and formed on the outer-most exterior coating portion.
Thereby, in the invention, from a charge inlet of the drum mixer 4 the sintering material excepting the limestone base powdery material M3 and solid fuel type powdery material M4 is charged to granulate and in a region disposed in the middle on a downstream side where a staying time during which the sintering material reaches the exhaust outlet 35 of the drum mixer 4 is in the range of from 10 to 90 seconds the limestone base powdery material M3 and solid fuel type powdery material M4 are added. Accordingly, according to the inventive method, since until reaching the exhaust outlet 35, the limestone base powdery material M3 and solid fuel type powdery material M4 can be deposited and formed on the exterior coating portion of the sintering material, in the course of sintering of the material for sintering, a reaction between CaO and SiO2 belatedly occurs, resulting in suppressing calcium silicate (CS) low in the cold strength from generating. As a result, on the surface of the sintered ore calcium ferrite (CF) high in the strength is generated, and toward the inside of the sintered ore hematite (He) high in the reducibility is selectively generated. Thereby, the sintered ore rich in fine pores, excellent in the reducibility and high in the cold strength can be stably manufactured.
Furthermore, in a method of manufacturing material for sintering where as a pretreatment to the process according to which sintered ore for a blast furnace is manufactured by use of a Dwight-Lloyd type sintering machine of downward suction, when a sintering material including iron ore M1, SiO2-containing material M2, limestone base powdery material M3 and solid fuel type powdery material M4 is granulated by use of the drum mixer 4, from the charge inlet of the drum mixer 4, the sintering material excepting the limestone base powdery material M3 and solid fuel type powdery material M4 is charged and granulated and in a region disposed in the middle on a downstream side where a staying time during which the sintering material reaches the exhaust outlet 35 of the drum mixer 4 is in the range of from 10 to 90 seconds the limestone base powdery material M3 is added followed by adding the solid fuel type powdery material M4, and thereby during reaching the exhaust outlet, on the exterior coating portion of the sintering material, the limestone base powdery material M3 and solid fuel type powdery material M4 are deposited and formed in this order, as mentioned above, toward the inside of the sintered ore hematite (He) high in the reducibility is selectively generated and the sintered ore rich in the fine pores, excellent in the reducibility and high in the cold strength can be stably manufactured, in addition, the solid fuel type powdery material M4 that becomes a heat source can be deposited and formed on the outer-most portion of the exterior coating portion, resulting in obtaining an improvement in the combustibility of the added solid fuel type powdery material M4.
In the next place, manufacturing apparatus will be explained.
In
In the next place, an example of the apparatus according to the invention will be detailed. In the apparatus shown in
A configuration of the transfer means 32 will be detailed with reference to
The additional coating conveyer 10, as shown in
In the next place, operations of the manufacturing apparatus 1 of the sintering material will be explained with reference to
The sintering material 7 transferred by the raw material conveyer 2 is equally divided by the shoot 3 and charged into the drum mixer 4 from the charge inlet thereof. Then, the sintering material 7, rolling in the drum mixer 4 toward a right direction in
At a position that is a substantial final step of the formation of the pseudo particle, that is, at a position in the neighborhood of the exhaust outlet 35 of the drum mixer 4, as shown with an arrow mark in
The predetermined position on a side of the exhaust outlet 35 in the drum mixer 4 where the exhaust end D of the additional coating conveyer 10 is positioned and the speed of the belt 14 of the additional coating conveyer 10 are preferably controlled so that a projection position of the additional coating auxiliary raw material 8 may be in a region disposed in the middle on a downstream side where a staying time during which the sintering material 7 reaches the exhaust outlet of the drum mixer 4 is in the range of from 10 to 90 seconds. Thereby, in the course of sintering of the sintering material, a reaction between CaO and SiO2 occurs belatedly, calcium silicate (CS) low in the cold strength being suppressed from generating, calcium ferrite (CF) strong in the strength being generated on a surface of the sintered ore, hematite (He) high in the reducibility being selectively generated toward the inside of the sintered ore, the sintered ore rich in the fine pores, excellent in the reducibility, and high in the cold strength being stably manufactured.
Furthermore, from the viewpoint of safety, when the projection of the additional coating auxiliary raw material 8 is continued, since the exhaust end D of the additional coating conveyer 10 is inside of the drum mixer 4, dust powder (calcined lime and so on) in the drum mixer 4 adheres and solidly sticks to the exhaust end D of the additional coating conveyer 10, resulting in causing disturbance in conveyer operation. Accordingly, when the dust powder in the drum mixer 4 adheres a certain extent to the exhaust end D of the additional coating conveyer 10, an operator rotates the rotation drum 26 by rotation control means in a direction shown by an arrow mark a in
After the cleaning came to completion, the operator, by use of the rotation control means, rotates the rotation drum 26 in a direction shown by an arrow mark c in
Thus, in the manufacturing apparatus 1 of the sintering material shown in
As shown in
On the other hand, in order to inhibit the dust powder from adhering to the exhaust end D of the additional coating conveyer 10, as shown in
In the above, modes for carrying out the invention were explained; however, the present invention, without restricting thereto, may be variously changed and improved.
For instance, the transfer means 32 shown in
Furthermore, as far as a additional coating mode where the additional coating conveyer 10 is inserted (intruded) into the drum mixer 4 to additionally coat is taken, the speed control means 34 for controlling the speed of the belt 14 of the additional coating conveyer 10 is not necessarily disposed.
In the additional coating experiment of the auxiliary raw material, the belt conveyer 10 is not provided with an angle of elevation, however, the additional coating conveyer 10 is preferably provided with elevation angle control means so that not only the initial speed but also the elevation angle may be controlled. Furthermore, when a additional coating angle of the additional coating conveyer 10 and/or a additional coating position in a width direction in the drum mixer 4 is made variable, a dispersion range of the additional coating auxiliary raw material 8 can be preferably widened. In
Pseudo particles that had been granulated according to the granulation flow (method A) of the invention from a sintering material having a compounding ratio shown in Table 2 were transferred to a Dwight-Lloyd type sintering machine and charged on a palette. For comparison, pseudo particles that had been granulated according to a treatment method where iron ore M1, SiO2-containing material M2, limestone base material M3 and coke powder M4 are simultaneously mixed were transferred to a Dwight-Lloyd type sintering machine and charged on a palette. Thereafter, the sintering was performed on the palette followed by measurements of ore composition and the reducibility. Measurements of ones according to the inventive method and the conventional method are shown in Table 3. The measurement was performed of the sintered ore obtained by Dwight-Lloyd type sintering machine having a production capacity of 9300 tons/day.
As shown in Table 3, when the granulation method according to the invention is adopted, as to the ore composition, hematite (He) high in the reducibility increased, calcium silicate (CS) low in the reducibility decreased, and, as shown in
Furthermore, pseudo particles manufactured according to the granulation method (method B) of the invention were similarly supplied to Dwight-Lloyd type sintering machine followed by sintering. Results were similar to the above.
Still furthermore, results of EPMA measurement of cross sections of sintered bodies of the pseudo particles according to the inventive method and conventional method are shown in
Furthermore, pseudo particles manufactured according to the granulation method (method C) of the invention were similarly supplied to Dwight-Lloyd type sintering machine followed by sintering. Results of the sintering and EPMA measurements were similar to the above.
With the apparatus shown in
In the projection experiment, projections were performed with the speed of the belt 14 set at 4 levels of 60 m/min, 180 m/min, 240 m/min and 300 m/min, and with the projection elevation angle of the additional coating auxiliary raw material 8 set at 0 degree, and projection distances from a central axis line of the driving pulley 12 to a position where the additional coating auxiliary raw material 8 reached the ground were measured.
Furthermore, when the additional coating auxiliary raw material 8 is projected, theoretical calculation values of a projection distance from the central axis line of the driving pulley 12 to a place where the additional coating auxiliary raw material 8 reaches the ground and a drop distance from a center of the driving pulley 12 to the ground can be expressed by the following (1) and (2) equations when calculated without considering the air resistance.
Projection distance=V×cos θ×t (1)
Drop distance=V×sin θ×t−g×t2/2 (2)
In the above equations, θ, V, and t, respectively, denote a projection elevation angle, a speed of the belt, and time. g denotes gravitational acceleration.
Then, measurements and calculated values of the projection distance were compared. Results thereof are shown in
With reference to
Accordingly, in the manufacturing apparatus 1 of the sintering material shown in
Furthermore, with the apparatus shown in
With reference to
As mentioned above, according to the manufacturing method of the sintering material of the invention, when the limestone base powdery material and solid fuel type powdery material that is a heat source are added in the exterior coating region disposed in the middle on a downstream side until pseudo particles reach the exhaust outlet of the drum mixer, a pseudo particle material for use in sintering in which the limestone base powdery material and solid fuel type powdery material that is a heat source are deposited and formed on the exterior coating portion of the pseudo particles can be manufactured. Accordingly, in the course of sintering with Dwight-Lloyd type sintering machine, calcium silicate (CS) low in the cold strength is suppressed from generating, calcium ferrite (CF) high in the strength is formed on the surface of the sintered ore, and hematite (He) high in the reducibility is selectively formed toward the inside of the sintered ore. As a result, the sintered ore rich in the fine pores, excellent in the reducibility and high in the cold strength can be manufactured with high productivity.
Other than the above, manufacturing apparatus of the sintering material suitable for the sintered ore that is simple, economical and easy in the maintenance of the apparatus can be provided.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2002-365207 | Dec 2002 | JP | national |
| 2003-036024 | Feb 2003 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP03/03969 | 3/28/2003 | WO | 00 | 6/1/2004 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2004/055224 | 7/1/2004 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5520719 | Okuno et al. | May 1996 | A |
| 20060112786 | Pammer et al. | Jun 2006 | A1 |
| Number | Date | Country |
|---|---|---|
| A 2000-290732 | Oct 2000 | JP |
| A 2002-285250 | Oct 2002 | JP |
| 2002-332526 | Nov 2002 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20050050995 A1 | Mar 2005 | US |
