JP2009052087A - Method of pretreating raw material for sintering - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of pretreating a raw material for sintering, by which an iron ore raw material containing fine powder in an amount larger than before can be dealt with and pellets having excellent air permeability and oxidative heat generation characteristics can be manufactured and sinterng productivity can be improved. <P>SOLUTION: The method of pretreating a raw material for sintering comprises: a first pelletizer 10 where two or more iron ores each containing coarse grains and fine powders are used as a raw material and the fine powders are allowed to adhere to the coarse grains to be core grains to prepare pellets S; and a second pelletizer 11 where pelletization is performed using fine powders alone or using mainly fine powders in the presence of water and binder to prepare pellets P. These pellets S and pellets P are used in the pretreatment method. After a moisture value when pelletizing the pellets S is regulated to 7 to 10 mass%, the pellets S and the pellets P after drying treatment are supplied into a sintering machine 14. At that time, the pellets P after the drying treatment, having the following moisture value, are used: a moisture value capable of reducing the average moisture value of the pellets consisting of the pellets S and the pellets P, by >0 to 3 mass% as compared with the moisture value of the pellets S alone. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a pretreatment method for a raw material for sintering.

In recent years, with the deterioration of iron ore, ores containing much fine powder are increasing. A typical ore includes limonite containing 3% by mass or more of crystal water (also referred to as high crystal water ore), but is not limited to this, and hematite is also an ore containing a lot of fine powder. There are riodose ore and denpo ore.
When these ores containing a large amount of fine powder are charged into the sintering machine as they are, the air permeability is deteriorated and the productivity of the sintered ore is hindered. It is directed to improve the granulation of ores.

As a specific method, for example, as shown in FIG. 6, the raw material is rolled by a drum mixer 90, fine powder is adhered around the core particles, and the adhesion thickness of the granulated fine powder is determined by a water addition device. There is a method of adjusting the amount of water added from 91. However, since this granulated material is conveyed by the belt conveyor 92 and directly sent to the sintering machine 94 via the supply device 93, if the moisture value at the time of granulating the granulated material is increased, the sintering machine As a result, a large amount of moisture is brought into 94, which significantly impairs the productivity of sintered ore in the sintering machine 94.
In particular, since the high crystal water ore has many fine pores in the surface layer portion, it is difficult to granulate with the amount of water used in normal granulation treatment, and the amount of water needs to be set higher.

However, when a granulated product having excessive moisture is charged into the sintering machine, the granulated product is heated and the moisture is evaporated before the granulated product is fired in the sintering process. Since the product is easily broken and the vapor moving to the unfired part of the granulated product is condensed, there is a problem that the air permeability in the sintering machine is hindered. Furthermore, a large amount of condensed water flows into, for example, a SOx gas suction duct generated during the sintering process, but this SOx gas dissolves in the water and causes problems such as equipment corrosion of the exhaust gas treatment system.
Therefore, a technique for achieving both the strengthening of the ore granulation and the moisture suppression has been required.
For example, Patent Document 1 discloses a technique of gas drying until a raw material once granulated is charged into a sintering machine. Patent Document 2 discloses a technique in which a part of a raw material mainly composed of a fine powder raw material is selected, granulated, dried, and charged into a sintering machine together with other granulated products.

JP 2006-336064 A JP 2007-77512 A

However, the conventional pretreatment method for sintering raw materials still has the following problems to be solved.
In the method disclosed in Patent Document 1, after the whole raw material is granulated with moisture of 7.5 to 9.0% by mass, the raw material is dried before being charged into the sintering machine, and the moisture is reduced to 0.2. This is a method of decreasing by ˜2% by mass.
However, since this method is intended for pseudo particles of a granulated product (so-called S-type granulated product) that attaches fine powder around the core particles only with moisture, and this is a method of directly drying with hot air or the like, The effect of the granulated material is insufficient, such as the amount of moisture reduction due to drying remains at 0.2 to 2% by mass.

In addition, the method disclosed in Patent Document 2 extracts a first granulator for producing a granulated product S (ie, an S-type granulated product) by attaching fine powder to core particles, and a raw material mainly composed of fine powder. It is provided with a second granulating apparatus that separates, crushes, kneads, granulates, and performs various treatments such as granulation and drying to form a strong granulated product P (that is, P-type granulated product). And agglomerated powder P are charged together in a sintering machine to reduce the amount of fine powder that inhibits aeration and to reduce the thickness of adhering fine powder that inhibits oxidation heat generation of carbon. .
However, there is no description about the optimization of moisture for granulation in the first granulator and the moisture optimization of the final charging raw material using the dried granulated material, and there is room for further improvement in productivity. ing.

The present invention has been made in view of such circumstances, and can be used for iron ore raw materials containing a larger amount of fine powder than before, and can produce a granulated product excellent in air permeability and oxidation heat generation, and can be sintered. It is an object of the present invention to provide a pretreatment method of a raw material for sintering that can improve the process.

The sintering raw material pretreatment method according to the present invention that meets the above-described object is a granulated product obtained by using two or more types of iron ore containing coarse particles and fine powder as raw materials, and attaching fine powder to coarse particles that become core particles. A first granulator for producing S, and a second granulator for producing a granulated product P by granulating in the presence of water and a binder consisting mainly of fine powder or mainly in the form of fine powder; It is a pretreatment method of a raw material for sintering using the product S and the granulated product P,
After the moisture value when granulating the granulated product S is 7% by mass or more and 10% by mass or less, when supplying the granulated product S and the granulated product P after the drying treatment to a sintering machine, After the drying process having a moisture value that reduces the average moisture value of the granulated product obtained by combining the granulated product S and the granulated product P by more than 0 and 3% by mass or less than the moisture value of the granulated product S alone. The granulated product P is used.

In the pretreatment method of the raw material for sintering according to the present invention, the iron ore supplied to the first granulator preferably has a mass ratio of fine powder of 500 μm under 5 to 40 mass%. .
In the pretreatment method of the raw material for sintering according to the present invention, the iron ore containing fine powder of 500 μm or less is separated from the iron ore to be supplied to the first granulator by sieving, and the obtained sieving Is preferably supplied to the second granulator.
In the pretreatment method of the raw material for sintering according to the present invention, the iron ore containing coarse particles over 500 μm is separated from the iron ore to be supplied to the second granulator by sieving, and the obtained sieve The top is preferably supplied to the first granulator.

In the pretreatment method of the raw material for sintering according to the present invention, the moisture value of the granulated product P after the drying treatment is preferably 0 or more than 0 and 5% by mass or less.
In the pretreatment method for a raw material for sintering according to the present invention, it is preferable to use a high crystal water ore having a crystal water content of 3% by mass or more for a part or all of the raw material.

Since the pretreatment method of the raw material for sintering according to claims 1 to 6 sets the moisture value when granulating the granulated product S to 7% by mass or more and 10% by mass or less, which is higher than before, it is simulated. Particles (fine powder) under 500 μm that are difficult to be taken into the particles can be taken into the pseudo particles as much as possible. Thereby, the fine powder which inhibits ventilation | gas_flowing at the time of baking of the granulated material S is further reduced, and the productivity of a sintered ore improves.
Moreover, since the granulated material P which has only a fine powder or mainly a fine powder is strongly granulated with water and a binder, it is possible to adjust a moisture value freely by subsequent drying treatment. As a result, when the granulated product S and the granulated product P after the drying treatment are combined, it becomes possible to reduce the average moisture value from the moisture value of the granulated product S alone, particularly exceeding 0 and 3% by mass. Sintering productivity can be further improved by using the granulated product P after the drying process having a moisture value to be reduced.
As described above, the moisture value of the granulated product S is reduced by the granulated product P absorbing the moisture of the granulated product S. Therefore, compared with the drying method in which hot air is directly blown to the granulated product S, The disintegration of the granule S can be extremely suppressed, and the moisture value of the granule S can be quickly reduced, which is effective for improving the sintering productivity.
Furthermore, the present invention in which the granulated product P is directly brought into contact with the granulated product S, and the moisture of the granulated product S is absorbed by the granulated product P is not directly blown with hot air in a high-temperature atmosphere. Compared with the drying method, the moisture value of the granulated product S can be reduced in a short time.

In particular, the pretreatment method of the raw material for sintering according to claim 2 makes the mass ratio of the fine powder of 500 μm or less of iron ore supplied to the first granulator 5 to 40% by mass. While reducing the amount of fine powder that is not granulated, it is possible to prevent the fine powder from adhering to the surface of the core particle from becoming excessively thick. Thereby, sintering productivity can further be improved.
The sintering raw material pretreatment method according to claim 3 separates the iron ore containing fine powder from the iron ore to be supplied to the first granulation apparatus by sieving, so the fine powder adhesion thickness of the granulated product S Can be optimized, and sintering productivity can be improved. Moreover, since the separated sieve is supplied to the second granulating apparatus, it can be effectively used as a raw material for producing the granulated product P.
The pretreatment method of the raw material for sintering according to claim 4 sieving and separating the iron ore containing coarse particles from the iron ore to be supplied to the second granulating apparatus, so that the particle size adjustment of the granulated product P Can be optimized, and sintering productivity can be improved. Moreover, since the separated sieve top is supplied to the first granulator, it can be effectively used as a raw material for producing the granulated product S.

The pretreatment method of the raw material for sintering according to claim 5 is such that the moisture value of the granulated product P after the drying treatment is 0 or more than 0 and 5% by mass or less. Even when it is set higher than usual, the granulated product P can efficiently absorb excess moisture of the granulated product S.
The pretreatment method of the raw material for sintering according to claim 6 uses a high crystal water ore having a crystal water content of 3% by mass or more for a part or all of the raw material, so that there are fine pores in the surface layer portion, Granulation P can absorb excessive moisture in granulated product S even when using high crystal water ore, which is difficult to granulate with the moisture value normally used, and the moisture value to be used needs to be set higher. . For this reason, the effect of this invention appears more notably.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIG. 1 is an explanatory view of a pretreatment method of a sintering raw material according to an embodiment of the present invention, and FIG. 2 is a granulation moisture content and granulation of the granulated product S manufactured by the first granulation apparatus. FIG. 3 is a graph showing the relationship between the proportion of fine powder of 500 μm under remaining after the granulation, FIG. 3 is a graph showing the relationship between the amount of water for granulation of the granulated product S and the fine powder adhesion thickness around the core particles, and FIG. FIG. 5 is a graph showing the relationship between the moisture content for granulation of the product S and the productivity index, and FIG. 5 is a graph showing the relationship between the moisture value and the proportion of fine powder under 500 μm.

As shown in FIG. 1, the pre-processing method of the raw material for sintering which concerns on one embodiment of this invention uses the 2 or more types of iron ore each containing a coarse grain and a fine powder as a raw material, and becomes the coarse grain used as a core particle. An S-type drum mixer (an example of a first granulating device) 10 for producing a granulated product S (hereinafter also referred to as S-type granulated product) by attaching fine powder, and water alone with fine powder or mainly fine powder. A P-type drum mixer (an example of a second granulating apparatus) 11 for producing a granulated product P (hereinafter also referred to as a P-type granulated product) by granulation in the presence of a binder is provided. This is a pretreatment method in the case of sintering using the granulated material P. In measuring the mass% of the fine powder particles, a laser diffraction scattering measuring instrument (MICROTRAC FRA type manufactured by Nikkiso Co., Ltd., measuring range: 0.1 to 700 μm) is used. This will be described in detail below.

Examples of the iron ore used as a raw material include limonite (Fe ₂ O ₃ .nH ₂ O) containing 3% by mass or more of crystal water, hematite (Fe ₂ O ₃ ) containing a lot of fine powders, and the like. In addition, although iron ore uses limonite for a part, it is good also as all limonite.
Here, examples of limonite include high crystal water ores such as maramamba ore (local brand: West Angelus), Australian pisolite ore (local brand: Yandi, Loeb River), and high phosphorus block man ore. In addition, examples of hematite include Yanpy ore, riodose ore, and denpo ore.
In addition, the iron ore is not limited to this, and magnetite (Fe ₃ O ₄ ) can be used as another iron ore as long as the iron ore contains coarse particles and fine powder. Moreover, it is of course possible to construct the raw material by adding other iron sources, for example, iron sources generated in the steelworks, to these iron ores.
This raw material has, for example, coarse particles of about 10 mm to fine powder of 250 μm or less.

First, the above-described raw materials are sieved by the sieve sorter 12.
The sieving is preferably performed so that the mass ratio of the fine iron ore powder of 500 μm or less supplied to the S-type drum mixer 10 is 5% by mass or more and 40% by mass or less (preferably 30% by mass or less). As this method, there are the following methods.
(1) From the iron ore to be supplied to the S-type drum mixer 10, iron ore containing fine powder of 500 μm or less is separated by sieving, and the obtained sieve is supplied to the P-type drum mixer 11. At this time, iron ore containing fine powder without sieving may be used as a part of the raw material supplied to the P-type drum mixer 11. The sieving is preferably performed with a threshold value in the range of 0.5 mm to 3 mm, for example.
(2) From the iron ore to be supplied to the P-type drum mixer 11, iron ore containing coarse particles over 500 μm is separated by sieving, and the obtained sieve top is supplied to the S-type drum mixer 10. At this time, iron ore containing coarse particles may be used as a part of the raw material supplied to the S-type drum mixer 10 without performing sieving. The sieving is preferably performed with a threshold value in the range of 1 mm to 10 mm.

In the methods (1) and (2) described above, the sieve sorter 12 is used, but without using the sieve sorter 12, iron ore is transferred to the S-type and P-type drum mixers 10 and 11. Each can also be supplied.
In this case, iron ore having a fine powder ratio of less than 500 μm is supplied to the S-type drum mixer, and iron ore having a high fine powder ratio is supplied to the P-type drum mixer.
In place of the above-described S-type drum mixer and P-type drum mixer, for example, an Eirich mixer, a disk pelletizer, or a professional mixer may be used.
Using the method shown above, the granulated product S is manufactured using the raw material S supplied to the S-type drum mixer 10 in the S-type granulation step, and the P-type drum mixer 11 in the P-type granulation step. The granulated product P is manufactured using the raw material P supplied to the slag, and the granulated product S and the granulated product P are supplied to the sintering machine 14 via the supply device 13.

The granulated material S described above supplies the raw material S having iron ore, carbon as a coagulant, and limestone (binder) to the S-type drum mixer 10, and further supplies moisture from the moisture adding device 15, It is produced by attaching fine iron ore, carbon, and limestone around the coarse iron ore as particles.
Since this granulated product S is conveyed by a belt conveyor (an example of a conveying means) 16 and directly sent to the sintering machine 14 after the granulation is completed, if the granulation moisture value is increased, the sintering machine A large amount of moisture is brought into 14, and the productivity of sintered ore in the sintering machine 14 is significantly hindered.
Therefore, the moisture value when the granulated product S is granulated (hereinafter also referred to as moisture for granulation) is 7 mass% or more and 10 mass%.

In addition, the moisture value at the time of granulating the granulated material S (the moisture value at the point P1 in FIG. 1) is 100% by mass based on the total mass supplied to the S-type drum mixer 10, and the raw material S It is indicated by the ratio of the total mass of moisture contained in (that is, iron ore, carbon, and limestone) from the beginning and moisture added from the moisture addition device 15 for granulation.
Here, the total mass supplied to the S-type drum mixer 10 is the raw material S supplied to the S-type drum mixer 10, the moisture contained in the raw material S from the beginning, and the moisture adding device 15 for granulation. The water added from (includes the liquid binder when a liquid binder is used). In addition, from the total mass of moisture described above, the water content of iron ore crystal water and the amount of moisture in the case of using a liquid binder are excluded.

In addition, the above-described granulated product P is mixed with the raw material P having only iron powder or iron ore mainly composed of fine powder in the kneading machine 17, and after adding water and a binder from the water and binder adding device 18, the P It is manufactured by granulating with a mold drum mixer 11. The size of the granulated product P is preferably 3 mm or more and 10 mm or less, for example, from the viewpoints of sinterability and air permeability during sintering.
The iron ore is used after being pulverized by the pulverizer 19, but may be used as it is without being pulverized according to the particle size. Here, when the pulverization process is performed, it is preferable to perform the pulverization process so that the particle size under 22 μm is 5 mass% or more. This increase in the amount of fine powder after pulverization leads to further improvement in the strength of the granulated product P, and is effective in suppressing the collapse of the granulated product P during the drying process performed after granulation.
The raw material P may be mixed with, for example, kneaded dust and pellet feed.
And the moisture value at the time of granulating the granulated material P shall be 8 mass% or more and 11 mass% or less, for example.

The moisture value when granulating the granulated product P is 100% by mass based on the total mass supplied to the P-type drum mixer 11, and the moisture contained in the raw material P (mainly iron ore) from the beginning. And the total mass of moisture and moisture added from the binder addition device 18 for granulation (including the liquid binder when a liquid binder is used).
Here, the total mass supplied to the P-type drum mixer 11 refers to the raw material P supplied to the P-type drum mixer 11, the moisture contained in the raw material P from the beginning, and moisture and an addition device for granulation. Water added from No. 18. In addition, from the above-mentioned total mass of moisture, the amount of moisture is excluded when crystal water of iron ore and a liquid binder are used.

As a binder used in order to granulate this granulated material P, a dispersing agent, an adhesive binder, or quicklime can be used, for example. Hereinafter, the amount of each binder added will be described.
When a dispersant is used as the binder, the solid content (active ingredient) amount of the dispersant is 0.001% by mass or more and 1% by mass or less (preferably, the lower limit is 0.005% by mass, the upper limit is the amount of the raw material P) Is preferably in the range of 0.5% by mass.
Moreover, when using an adhesive binder as a binder, it is in the range of 0.1 mass% or more and 5 mass% or less with respect to the quantity of the raw material P (preferably, a minimum is 0.05 mass% and an upper limit is 3 mass%). It is preferable to do. This adhesive binder bonds particles by the adhesiveness of the adhesive binder itself. For example, bentonite, lignin sulfite (pulp waste liquor), starch, sugar, molasses, water glass, cement, gelatin, corn starch Etc.
And when using quicklime as a binder, with respect to the quantity of the raw material P, 0.1 mass% or more and 2 mass% or less (preferably, a minimum is 0.5 mass%, an upper limit is 1.5 mass%) and It is preferable to do.

The granulated product P is further dried by the dryer 20 and then supplied to the sintering machine 14.
Here, the moisture value of the granulated product P after the drying treatment (the moisture value at the point P2 in FIG. 1) is adjusted by, for example, the drying time, the gas temperature during drying, or the size of the granulated product P However, it is preferably 0 or more than 0 and about 5% by mass or less. In addition, the drying process by the dryer 20 is performed about 20 to 60 minutes, for example in the atmosphere set to 40 to 250 degreeC.
The moisture value of the granulated product P after the drying treatment is 100% by mass, with the raw material P supplied to the P-type drum mixer 11 and the total mass of moisture remaining in the granulated product P even after the drying treatment, It is the ratio which the mass of the water | moisture content which remains in the raw material P of these accounts. In addition, the crystal water of iron ore is removed from the mass of the remaining water.
Thus, since the granulated product P is granulated with fine powder using moisture and a binder, it becomes a strong granulated product, and unlike the granulated product S described above, when dried with hot air But it won't collapse. For this reason, the moisture value of the granulated material P after a drying process can be adjusted freely.

The granulated product S and the granulated product P produced by the above method are supplied to the sintering machine 14. The granulated product S and the granulated product S may be supplied separately to the sintering machine 14, or may be supplied to the sintering machine 14 after combining the granulated product S and the granulated product P. Good.
As described above, the granulated product S and the granulated product P are supplied to the sintering machine 14, but at the time of sintering, the productivity is hindered due to the deterioration of the air permeability due to moisture condensation to the lower part in the sintering bed, and in the exhaust gas. There are concerns such as an increase in the amount of exhaust gas accompanying the increase in water content and corrosion of the exhaust gas system. For this reason, it is desirable to reduce the moisture supplied to the sintering machine 14 as much as possible.
As this method, when the dried granulated product P is combined with the granulated product S, an operation of reducing the average moisture value of the granulated product after mixing can be considered by the reduced moisture value of the granulated product P. It is necessary to stop within a range in which the collapse of the granulated material S can be suppressed.

Therefore, as described above, after the granulated product S is granulated with a moisture value of 7 mass% or more and 10 mass% or less, the granulated product S and the granulated product P are supplied to the sintering machine 14. The average moisture value of the granulated product obtained by combining the granulated product S and the granulated product P is less than the moisture value of the granulated product S only by 0% and 3% by mass or less after the drying treatment. It is necessary to use the granulated product P (moisture value: 0 or more than 0 and preferably 5% by mass or less).
The average moisture value (the moisture value at the point P3 in FIG. 1) of the granulated product described above is the total mass supplied to the S-type drum mixer 10 and the mass of the raw material P supplied to the P-type drum mixer 11. The total mass of moisture remaining in the granulated product P even after the drying treatment is 100% by mass, and the ratio of moisture contained in the granulated product is shown. The moisture contained in the granulated product is the moisture contained in the raw material S (that is, iron ore, carbon, and limestone) from the beginning, the moisture added from the moisture adding device 15 for granulation, and the raw material P. It is the total moisture remaining in the water. In addition, from the above-mentioned total water | moisture content, when using a crystal water of an iron ore and a liquid binder, the water content is remove | excluded.

Here, the moisture value at the time of granulating the granulated product S, the moisture value of the granulated product P after the drying treatment, and the average moisture value of the granulated product combining the granulated product S and the granulated product P, The reason specified in the above numerical range will be described.
First, regarding the granulation behavior of the granulated product S in the first granulator, the relationship between the moisture value during granulation (the amount of moisture for granulation) and the proportion of fine powder under 500 μm remaining after granulation is shown. This will be described with reference to FIG. In addition, in FIG. 2, the result of having adjusted the ratio of the fine powder under 500 micrometers to 20 mass%, 30 mass%, and 40 mass%, respectively is shown. An S-type drum mixer was used for the first granulator.

As shown in FIG. 2, by granulating while gradually increasing the amount of moisture for granulation, the proportion of fine powder of 500 μm under remaining after granulation was reduced. This is because by increasing the moisture content for granulation, 500 μm-under fine powder adheres to the periphery of the core particles, and the amount of 500 μm-under fine powder not used in the granulation treatment decreases.
Moreover, when the moisture content for granulation was the same, the proportion of fine powder remaining after granulation was further reduced by reducing the proportion of fine powder under 500 μm in the raw material S supplied to the S-type drum mixer. This is because if the amount of fine powder to be used decreases, the remaining fine powder ratio naturally decreases.

Next, regarding the granulation behavior of the granulated product S in the first granulator, FIG. 3 showing the relationship between the moisture value at the time of granulation (amount of moisture for granulation) and the fine powder adhesion thickness around the core particles. The description will be given with reference. In addition, in FIG. 3, the result of having adjusted the ratio of the fine powder under 500 micrometers to 20 mass%, 30 mass%, and 40 mass%, respectively is shown. An S-type drum mixer was used for the first granulator.
As shown in FIG. 3, by granulating while gradually increasing the amount of moisture for granulation, the thickness of fine powder adhering around the core particles increased. This is because by increasing the moisture content for granulation, the fine powder under 500 μm easily adheres to the periphery of the core particles, and the adhesion thickness increases.
Moreover, the thickness of the fine powder adhering to the circumference | surroundings of a core particle became thin when the moisture content for granulation was the same by reducing the fine powder ratio of 500 micrometers under in the raw material S supplied to an S type drum mixer. This is because, as the amount of fine powder to be used decreases, the amount of fine powder attached naturally decreases.

In addition, the adhesion thickness of the fine powder of the above-described granulated product S was calculated by the following procedure.
(1) First, the target raw material is completely separated into fine particles, coarse particles, etc. by washing, etc., and the sieving is performed in the order of sieving of 5 mm, 2 mm, 1 mm, 0.5 mm, and 0.25 mm. The mass ratio of each particle size section was obtained by sieving (mass g of each particle size section when the whole was 100 g).
(2) The representative particle diameter (7.5 mm, 3.5 mm, 1.5 mm, respectively) of each section of 5 mm or more, less than 5 mm, 2 mm or more, and less than 2 mm, or 1 mm or more to be each particle was determined to be 100 g as a whole. The number of core particles for each representative particle size was calculated from each particle size interval mass ratio. At that time, the core particle density was set to 4 g / cm ³ .

(3) When distributing fine powder of 0.25 mm or less that becomes powder adhering to the core particles for each core particle section, each core particle is proportional to the core particle mass ratio of each core particle section. The mass of fines distributed to the section was determined.
(4) The adhesion thickness of each core particle was calculated from the number of core representative particle diameters of the core particle calculated in (2) above and the fine powder mass distributed and calculated in (3). At that time, the bulk density of the adhered powder layer was set to 2 g / cm ³ .
(5) Then, the thickness of the adhering powder in each core particle section was weighted and averaged with the mass ratio of each particle size section to obtain the average powder thickness.

The result of evaluating the productivity (sintering productivity) of the sintered ore using the result of the granulation process shown above will be described with reference to FIG.
Note that the productivity index in FIG. 4 indicates that the granulated product P granulated by the second granulator is mixed into the granulated product S, and the firing rate (kg / hour) is measured using a firing test device for an actual machine. ) And the product yield (mass%) excluding the sinter after the pulverized sintered ore particle size is less than 6 mm, and the product yield is calculated by multiplying these.
Here, the moisture value of the granulated product P after the drying treatment is such that the average moisture value of the granulated product obtained by combining the granulated product S and the granulated product P is 1% by mass than the moisture value of the granulated product S alone. The drying process was adjusted so as to reduce it. An S-type drum mixer was used for the first granulator, and a P-type drum mixer was used for the second granulator.

As shown in FIG. 4, when the proportion of fine powder of 500 μm under in the raw material S supplied to the S-type drum mixer is as large as 40% by mass, in the range where the moisture for granulation of the granulated product S rises to 7% by mass. There is an improvement in productivity. However, even with more moisture, the improvement effect is small and unclear. Rather, increasing the moisture for granulation to 10% by mass tends to decrease slightly although the productivity index does not change substantially. is there. The improvement in productivity means an improvement in air permeability by reducing the amount of condensed water during firing of the sintered ore, and an adverse effect on the air permeability of the granulated product S collapse accompanying the reduction in the moisture for granulation (inhibition of air permeability). ).
For this reason, when the proportion of fine powder under 500 μm exceeds 40% by mass, the tendency for the productivity index to decrease when the granulation moisture is 10% by mass increases, so the granulation moisture is 7% by mass to 9% by mass. It is preferable to keep within the range.

On the other hand, when the fine powder under 500 μm in the raw material S supplied to the S-type drum mixer is reduced to 30% by mass or less (30% by mass, 20% by mass), the productivity increases stepwise. Furthermore, in addition to this phenomenon, even when the granulation S has a granulation water content of 7% by mass or more, the productivity improves as the granulation water rises, and the 500 μm undersize remaining after the granulation is reduced. The effect appears up to the range of 10% by mass of granulation water in which fine powder is almost eliminated.
From the above, that is, from the relationship with the ratio of the remaining fine powder, the adhesion thickness of the fine powder, and the productivity index, the moisture value when granulating the granulated product S is 7 mass% or more and 10 mass% or less (preferably The upper limit was defined as 9% by mass).

Two mechanisms contribute to this mechanism: a decrease in the amount of ungranulated fine powder that affects aeration, and a decrease in adhesion thickness that affects oxidation heat generation.
The productivity of sintering is greatly influenced by the air permeability in the sintering bed and the oxidation heat generation of carbon as a coagulant. This aeration is greatly affected by fine powder remaining in the granulated product S even after granulation, particularly fine powder under 500 μm, and can be improved by reducing this (this is the first mechanism).
On the other hand, the oxidation exothermicity of carbon is greatly affected by the thickness of fine powder adhering to the periphery of the core particles, and if it is excessive, carbon is buried and the oxidation exothermicity deteriorates, so the firing rate and yield decrease. Inhibits productivity (second mechanism).

This mechanism is contrary to productivity improvement in the means for increasing the moisture for granulation within a predetermined range (granulation strengthening means). However, first, a reduction in the amount of ungranulated fine powder is greatly effective in improving productivity, and in order to further improve productivity stably, it is preferable to reduce the adhesion thickness of fine powder.
Here, in order to reduce the adhesion thickness of the fine powder, the mass ratio of the fine powder under 500 μm of the iron ore supplied to the S-type drum mixer 10 is 5 mass% to 40 mass% (preferably 30 mass% or less). Various methods can be applied.
Next, when the dried granulated product P is combined with the granulated product S, the operation of reducing the moisture value of the granulated product S by the granulated product P whose moisture value has been reduced by the drying process is shown in FIG. The description will be given with reference.

FIG. 5 shows the decrease behavior of the residual fine powder ratio when the moisture for granulation of the granulated product S in the first granulator is increased, and the granulated product granulated with 8.8% by mass of the granulating moisture. The change of the generation amount of the fine powder when S is dried is shown. In addition, in the reduction | decrease of the water | moisture content of the granulated material S, the comparative examination was carried out about the case where it mixes with the granulated material P (Example), and the case where it is based on gas (hot air) drying (comparative example). Here, an S-type drum mixer was used for the first granulator. The amount of 500 μm under in the raw material S used for granulation of the granulated product S was 40% by mass.
As is clear from FIG. 5, by granulating while gradually increasing the amount of moisture for granulation, the proportion of fine powder of 500 μm under remaining after granulation was reduced (♦ in FIG. 5). This is the same as the result of FIG.

When the produced granulated product S was gas-dried (Δ in FIG. 5), the generation amount of fine powder increased with the same tendency as the behavior during granulation as the moisture value contained in the granulated product S decreased. . This has shown that the granulated material has disintegrated in proportion to the reduction | decrease of the moisture value of the granulated material S. FIG.
On the other hand, the dried granulated product P is mixed into the granulated product S, and the average moisture value of the granulated product obtained by combining the granulated product S and the granulated product P is reduced from 8.6% by mass to 5% by mass. In this case, the granulated product S slowly decays until the average moisture value decreases to 5.8% by mass, and thereafter, the granulated product S collapses in the same tendency as gas drying (FIG. 5). Inside circle).

In addition, when the average moisture value of the granulated product was 8.2% by mass, a significant difference was observed in the amount of fine powder increased as compared with gas drying. This is because gas drying evaporates moisture from the surface to the inside of the granulated product S and causes the fine powder to be peeled off. This is because when the product P is mixed, the absorption of moisture by the granulated product P makes it difficult for the fine powder adhering to the granulated product S to peel off and the granulated product S to collapse.
That is, in the drying of the granulated product S, the difference between whether the water is evaporated by water evaporation or the liquid P is absorbed by the granulated product P as it is is shown. For this reason, when supplying the granulated product S and the granulated product P to a sintering machine, it is preferable to increase the contact area of the granulated product S and the granulated product P. As this method, for example, after the granulated product S and the granulated product P are mixed, the mixed granulated product is supplied to a sintering machine, or the granulated product mixed with the granulated product P is alternately laminated. There is a method in which the granulated product S is supplied to the sintering machine while the granulated product S is laminated on the granulated product P supplied to the sintering machine.

Here, when the moisture of the granulated product S is absorbed by the granulated product P, the granulated product S is granulated in a range in which the fine powder ratio is small if the reduction amount (reduction cost) of the moisture value of the granulated product S exceeds 0% by mass. The moisture value of the thing S can be reduced.
On the other hand, when the reduction amount of the moisture value of the granulated product S is more than 3% by mass, even when combined with the dried granulated product P, as shown in FIG.
From the above, drying is performed so that the average moisture value of the granulated product obtained by combining the granulated product S and the dried granulated product P is more than 0% by mass and less than 3% by mass from the moisture value of the granulated product S. It is necessary to adjust the moisture value of the granulated product P after the treatment.
About this adjustment, when it is desired to reduce the moisture value of the granulated product S to 3% by mass, to lower the moisture value after drying the granulated product P, and to reduce the moisture value to 0% by mass. , By raising the moisture value after drying the granulated product P.

Moreover, the moisture value of the granulated product S is reduced by changing the mixing ratio (mass ratio) of the granulated product S and the granulated product P while keeping the moisture value of the granulated product P after the drying treatment constant. It is also effective to control.
However, in general, the production amount (for example, ton / hour) of the granulated product S and the granulated product P is likely to depend on the particle size distribution of the iron ore raw material used, and therefore the mixing ratio cannot be arbitrarily controlled. Therefore, it is considered most effective to control the moisture value after the drying treatment of the granulated product P.
As shown above, in order to produce the granulated product S and the granulated product P to be supplied to the sintering machine 14 individually, the granulating water of the granulated product S and the granulated product P is granulated. It can be granulated by adjusting the amount suitable for the size. Further, since the produced granulated product P is strongly granulated with a binder, the drying treatment can be carried out to a level according to the purpose, and the granulated product S granulated with a higher granulation moisture than usual. The moisture value can be absorbed by the granulated product P.
In addition, as a method of drying the granulated product P, a band drier that ventilates in a stationary state is the best because it can suppress the collapse of the granulated product P. Is also applicable. This is because the collapse of the granulated product P can be sufficiently suppressed by the gas cushion effect. Here, the method of applying a mechanical impact such as a kiln is remarkably collapsed and is difficult to apply.
From the above, by applying the present invention, a granulated product excellent in air permeability and oxidation exothermic property can be manufactured, and the sintering productivity can be improved.

Next, in order to confirm the effect of this invention, the result of having implemented various tests by changing granulation conditions is demonstrated.
First, the raw material is subjected to sieving without sieving, and a granulated product S is produced using an S-type drum mixer in the S-type granulation step, and the P-type drum in the P-type granulation step. A granulated product P was produced using a mixer.
And these granulated material S and granulated material P which gave these pre-processing are laminated | stacked on a grate, a fixed negative pressure is given from the downward direction, air is attracted | sucked from an upper layer, it ignites from the upper part, and is baked to the lower part. did.
At this time, when the granulated product P is combined with the granulated product S, the average moisture value of the granulated product S and the granulated product P is a predetermined value (exceeding 0 and 3 mass% from the moisture value of only the granulated product S). In the following, the granulated product P was dried so as to decrease, and the water content was appropriately adjusted. In addition, Comparative Examples 1-3 show the case where the reduction margin of the moisture value is outside the appropriate range.
Hereinafter, each test condition will be described in detail.

Comparative Example 1 is a result of using a plurality of types of iron ores including maramamba ore and pisolite ore as raw materials, supplying the whole amount to an S-type drum mixer and granulating only with water.
On the other hand, Comparative Examples 2 and 3 and Examples 1 to 7 sieved a portion of the maramamba ore and pisolite using a sieve having an opening of 1 mm (extraction of fine powder), and other raw materials on the sieve It is the result of granulating with only water by supplying to the S-type drum mixer together with the raw materials. Thereby, the amount of fine powder in the raw material was reduced.
The raw material (extracted fine powder) in which fine powder is concentrated is first pulverized, then kneaded while adding a dispersant as a binder using a kneader, and further granulated with a P-type drum mixer. And then dried.
The produced granulated product S and granulated product P were combined and supplied to a sintering machine.

In Examples 8 to 10, the granulated product P produced by pulverizing, granulating, and drying using the above-described various apparatuses without sieving a part of the maramamba ore was used as the remaining maramamba. It was supplied to the sintering machine together with the granulated product S granulated using the ore (adjustment of fine powder under 500 μm) and other raw materials (hematite). In addition, the maramamba ore supplied to each of the S-type granulation step and the P-type granulation step is the same, and no processing such as sieving by a sieve sorter is performed.
In Comparative Examples 2 and 3 and Examples 1 to 10 shown above, the moisture value of the granulated product P after the drying treatment is the average moisture value of the granulated product S and the granulated product P. Each is determined so as to have a moisture value.
Table 1 shows the above granulation conditions.

In Table 1, “−500 μm” indicates the mass ratio of 500 μm under contained in the raw material S provided to the S-type drum mixer, and “moisture value” indicates that the granulated product S is similarly prepared using the S-type drum mixer. The moisture value at the time of granulation is shown, respectively. The calculation method of “−500 μm” and “moisture value” is shown below.
“−500 μm (mass%)” = “{mass (kg) of raw material under 500 μm (excluding moisture, including crystal water) supplied to S-type granulation process}} / {raw material supplied to S-type granulation process Mass of S (excluding water, including crystal water) (kg)} ”× 100
“Moisture value (mass%)” = “moisture value when granulating the granulated product S” = “{the moisture contained in the raw material S (ie, iron ore, carbon, and limestone) from the beginning (crystals of iron ore) (If water and liquid binder are used, exclude the water content) (kg)} + {moisture added for granulation (kg)} "/ {total mass (kg) supplied to S-type drum mixer } × 100

“Presence / absence of extraction of fine powder” indicates the presence / absence of raw material separation in the P-type granulation step. The separated raw material was pulverized, kneaded with a dispersant as a binder and added with water, and granulated with a P-type drum mixer (Comparative Examples 2, 3 and Examples). 1-7).
And "the reduction allowance of the average moisture value of S + P" means that the average moisture value of the granulated product obtained by combining the granulated product S and the granulated product P is greater than the moisture value of the granulated product S alone. Also shows a reduced amount.
Further, the “productivity index” is a value obtained by calculation in the above-described embodiment. Specifically, the productivity per pallet of 1 m ³ is calculated from the firing rate in the sintering machine and the product yield. It is the value compared. Here, the productivity of Comparative Example 2 was set to 100, and the productivity of each condition was compared.

In Comparative Example 2 shown in Table 1, the fine powder in the raw material is extracted, and the proportion of 500 μm under in the raw material supplied to the S-type drum mixer is reduced to 30% by mass. It was found that productivity was improved more.
Moreover, the comparative example 3 is the result which made the reduction allowance of an average moisture value 4 mass% by match | combining the granulated material P which strengthened the drying process with the granulated material S in the process similar to the comparative example 2. However, since the granulated material collapsed due to excessive drying, no improvement in productivity was observed.
Hereinafter, Examples 1 to 10 will be described using Comparative Example 2 in which productivity is most improved among Comparative Examples 1 to 3 as a reference (“Productivity Index” is 100).

In Example 1, by setting the reduction allowance of the average moisture value to 3% by mass, the granulated product S was prevented from collapsing due to excessive drying, and the improvement in productivity was recognized remarkably. In addition, in Example 1, since the mass ratio of the 500 micrometer under in the raw material supplied to an S type | mold drum mixer was reduced with respect to Example 6 to 40 mass%, even if the moisture value of the granulated material S shall be 10 mass% It was confirmed that the productivity could be improved by suppressing the influence of the increase in the fine powder adhesion thickness. Furthermore, as in Examples 2 to 5, it was also confirmed that the productivity can be stably improved by reducing the 500 μm under to 30% by mass.
In addition, the moisture value of the granulated product S is increased to 10% by mass as in Examples 4 and 5, and the drying treatment of the granulated product P is adjusted as in Examples 3 and 5 to obtain an average moisture content. It was confirmed that productivity was improved synergistically by reducing the reduction allowance of the value as much as possible within the range of up to 3% by mass.

Further, as in Examples 6 and 7, when the proportion of fine powder of 500 μm under in the raw material is excessive, or separation of fine powder is insufficient, 500 μm under remains in the S-type drum mixer in excess of 40% by mass, Since the adhered thickness of the granulated product becomes excessive, although productivity is improved as compared with Comparative Example 2, it is relatively small.
On the other hand, Examples 8-10 are the results of supplying raw materials independently to each of the S-type and P-type granulation steps without carrying out sieving of the raw materials. In this S-type granulation process, hematite with less 500 μm underage was frequently used, and in order to adjust the ratio of 500 μm under, maramanba ore with much fine powder was appropriately added.
In all of Examples 8 to 10, the same productivity improvement effect was obtained as compared with the case of sieving.
From the above results, by applying the present invention, it is possible to deal with raw materials of iron ore containing a larger amount of fine powder than before, producing granulated products with excellent breathability and oxidation heat generation, and sintering productivity We were able to confirm that

As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and the matters described in the scope of claims. Other embodiments and modifications conceivable within the scope are also included. For example, a case where the pretreatment method for a sintering raw material of the present invention is configured by combining some or all of the above-described embodiments and modifications is also included in the scope of the right of the present invention.
Moreover, although the iron ore used for a raw material uses limonite for a part, the effect of this invention appears more notably by using limonite for all.

It is explanatory drawing of the pre-processing method of the raw material for sintering which concerns on one embodiment of this invention. It is a graph which shows the relationship between the moisture content for granulation of the granulated material S manufactured with the 1st granulator, and the fine powder ratio of 500 micrometer under which remains after granulation. It is a graph which shows the relationship between the moisture content for granulation of the granulated material S, and the fine powder adhesion thickness around a nucleus particle. It is a graph which shows the relationship between the moisture content for granulation of the granulated material S, and a productivity index. It is a graph which shows the relationship between a moisture value and the fine powder ratio of 500 micrometers under. It is explanatory drawing of the pre-processing method of the raw material for sintering which concerns on a prior art example.

Explanation of symbols

10: S-type drum mixer (first granulator), 11: P-type drum mixer (second granulator), 12: Sieve sorter, 13: Feeder, 14: Sinter, 15: Moisture Addition device, 16: belt conveyor (conveying means), 17: kneading machine, 18: moisture and binder addition device, 19: pulverizer, 20: dryer

Claims (6)

A first granulator for producing a granulated product S by using two or more types of iron ore containing coarse particles and fine powder as raw materials, and attaching the fine powder to coarse particles as core particles, and only fine powder or fine powder A pre-processing method for a sintering raw material using the granulated product S and the granulated product P, comprising a second granulator for producing the granulated product P by granulating in the presence of water and a binder as a main component Because
After the moisture value when granulating the granulated product S is 7% by mass or more and 10% by mass or less, when supplying the granulated product S and the granulated product P after the drying treatment to a sintering machine, After the drying process having a moisture value that reduces the average moisture value of the granulated product obtained by combining the granulated product S and the granulated product P by more than 0 and 3% by mass or less than the moisture value of the granulated product S alone. A method for pre-processing a raw material for sintering, wherein the granulated product P is used. 2. The pretreatment method of a raw material for sintering according to claim 1, wherein the iron ore supplied to the first granulator has a mass ratio of fine powder of 500 μm under 5 to 40 mass%. A pre-processing method of a raw material for sintering characterized. 3. A pretreatment method for a raw material for sintering according to claim 2, wherein iron ore containing fine powder of 500 μm or less is separated from the iron ore to be supplied to the first granulator by sieving, and the obtained sieve The pretreatment method of the raw material for sintering characterized by supplying the bottom to the said 2nd granulator. 3. A pretreatment method for a raw material for sintering according to claim 2, wherein the iron ore containing coarse particles over 500 μm is separated from the iron ore to be supplied to the second granulator by sieving, and obtained. A pretreatment method for a raw material for sintering, characterized in that a sieve top is supplied to the first granulator. The pretreatment method of the raw material for sintering according to any one of claims 1 to 4, wherein a moisture value of the granulated product P after the drying treatment is 0 or more than 0 and 5 mass% or less. A pre-processing method of a raw material for sintering characterized. In the pre-processing method of the raw material for sintering of any one of Claims 1-5, using the high crystal water ore whose crystallization water content rate is 3 mass% or more for a part or all of the said raw material. A pre-processing method of a raw material for sintering characterized.

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