JP2006312786A - Method for pretreating raw material for sintering - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for pretreating a raw material for sintering, by which an iron ore material containing fine powder in an amount larger than before can be dealt with, pellets having pelletization characteristics and strength more improved than before can be prepared and a sintered ore with superior quality can be manufactured. <P>SOLUTION: Pellets containing an iron ore having a content of crystal water of ≥3 mass%, e.g., Maramanba ore, pisolite ore or high phosphorous Brockman ore at least in one part and pelletized in the presence of water are dried at a temperature of ≥40 and ≤250°C before it is charged into a sintering machine 21. Thereby, the decomposition of crystal water is suppressed and further inhibited because the drying temperature is controlled to be ≥40 and ≤250°C. Further, the breakdown and degradation of the pellets can be suppressed and further prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

In recent years, the supply amount of iron ore such as hematite, which has been conventionally used in sintering machines, has decreased, and the supply amount of iron ore having a high crystal water content (3 mass% or more) has increased. This iron ore with a high content of water of crystallization contains more fine powder than the iron ore that has been used in the past, so if this iron ore is charged into the sintering machine without pretreatment, the air permeability of the sintering machine will be reduced. The sinter with good quality cannot be produced with good productivity. For this reason, it is necessary to granulate iron ore before charging it into the sintering machine, but it has the disadvantage that it is poor in wettability with water and has low granulation properties compared to iron ore that has been used in the past. Therefore, a technique for granulating this has become necessary.
Therefore, for example, Patent Document 1 discloses a technique of pulverizing iron ore and limestone so that 250 μm or less is 80% by weight or more and producing a granulated product in the presence of water. Patent Document 2 discloses a technique for producing a granulated product of fine ore through two granulations.

Japanese Patent Laid-Open No. 4-80327 JP-A-53-123303

However, the conventional sintering raw material pretreatment method still has the following problems to be solved.
The method disclosed in Patent Document 1 requires time and labor for pulverizing all limestone serving as a binder, is not economical because of an increase in production cost due to pulverization, and the productivity of the granulated product is very poor. . Further, if the pulverized particle size of 250 μm or less is merely 80% by weight or more, the strength of the granulated product produced using this, that is, the P-type granulated product cannot be increased to the intended strength. When the granular material is conveyed via a plurality of belt conveyors, the granulated material may be pulverized during the transfer.
Moreover, the method disclosed in Patent Document 2 may improve the strength of the granulated product. However, for example, in the case of producing a granulated product in which fine powder is adhered to coarse particles serving as core particles, that is, an S-shaped granulated product, the thickness of fine powder deposited cannot be controlled. For this reason, if the adhesion thickness is thick, coke is buried inside the granulated material, making it difficult to produce sintered ore with the desired quality, leading to a decrease in yield of sintered ore, Productivity is impaired.

The present invention has been made in view of such circumstances, and can be used for raw materials of iron ore containing a larger amount of fine powder than before, and can produce a granulated product with improved granulation properties and strength than before. An object of the present invention is to provide a method for pre-processing a sintering raw material capable of producing a sintered ore with excellent quality.

The sintering raw material pretreatment method according to the first aspect of the present invention is a granulation method in which two or more types of iron ore containing coarse particles and fine powders are used as raw materials, and fine particles are adhered to the coarse particles that become core particles. A first granulator for producing a product S, and a second granulator for producing a granulated product P for granulating only fine powder or mainly fine powder, the granulated product S and the granulated product A pretreatment method of a sintering raw material using P,
The granulated product S adjusts the fine powder blending amount to the first granulator so that the fine powder adhesion average thickness to the core particles is 50 to 300 μm,
The remaining fine powder not supplied to the first granulator is used as a raw material for the second granulator.

The sintering raw material pretreatment method according to the second invention in accordance with the above object uses two or more types of iron ore containing coarse particles and fine powders as raw materials, and granulates by attaching fine powders to coarse particles that become core particles. A first granulator for producing a product S, and a second granulator for producing a granulated product P for granulating only fine powder or mainly fine powder, the granulated product S and the granulated product A pretreatment method of a sintering raw material using P,
The granulated product S adjusts the amount of coarse particles blended in the first granulator so that the fine powder adhesion average thickness on the core particles is 50 to 300 μm.

Here, when producing a granulated product S (hereinafter also referred to as “S-type granulated product”) in which fine powder is adhered to coarse particles serving as core particles, to core particles (coarse iron ore or coarse coke). When the fine powder adhesion thickness increases, the granulated material does not easily burn to the inside, and the productivity of sintered ore in the sintering machine deteriorates. In addition, when producing a granulated product P (hereinafter also referred to as a P-type granulated product) that is granulated with only fine powder or mainly composed of fine powder, it is optimal for making iron ore into a P-type granulated product. It is necessary to grind everything up to the particle size, which imposes a heavy load on the grinder and is not realistic.

Therefore, in the pretreatment method of the sintered raw material according to the first invention, the optimum fine powder adhesion average thickness for improving the productivity of the sintered ore in the sintering machine, that is, the average thickness of 50 to 300 μm (preferably Adjust the amount of fine iron ore powder supplied to the first granulator so that an S-type granulated product having an upper limit of 250 μm, more preferably 220 μm can be produced, and the remaining fine powder is P-type granulated. Used as a raw material. In addition, the adjustment method which does not supply fine powder to a 1st granulator is also contained in adjustment of fine powder compounding quantity.
Moreover, in the pre-processing method of the sintering raw material which concerns on 2nd invention, optimal fine powder adhesion average thickness which makes favorable the productivity of the sintered ore with a sintering machine, ie, average thickness of 50-300 micrometers (preferably Feeds coarse particles, which are core particles of iron ore, to the first granulator so that an S-type granulated product having an upper limit of 250 μm, more preferably 220 μm can be produced. At this time, by increasing the number of core particles relative to the amount of fine powder, the average thickness of the fine particle adhesion can be made thinner than the current state, and by reducing the number of core particles relative to the amount of fine powder, The average thickness can be made thicker than it currently is.

The pretreatment method of the sintering raw material according to the third invention is the pretreatment method of the sintering raw material according to the second invention, wherein the coarse particles supplied to the first granulating device are the second granulation device. Coarse grains in the iron ore excluding fine powder supplied to the apparatus are included.
In the pretreatment method of the sintering raw material according to the third invention, when the two or more types of iron ores containing coarse particles and fine powder are separately processed in the first and second granulating apparatuses, Coarse grains in iron ore that are not suitable as raw materials for P-type granules produced with a granulator are used as core particles for S-type granules produced with the first granulator without being pulverized. It becomes possible to do.

The sintering raw material pretreatment method according to the fourth aspect of the invention that meets the above-mentioned object uses two or more types of iron ore containing coarse particles and fine powder as raw materials, and granulates by attaching fine powder to coarse particles that become core particles. A first granulator for producing a product S, and a second granulator for producing a granulated product P for granulating only fine powder or mainly fine powder, the granulated product S and the granulated product A pretreatment method of a sintering raw material using P,
The iron ore to be supplied to the second granulator is sieved with a sieve mesh in the range of 0.5 to 10 mm, preferably 0.5 to 7 mm (more preferably 0.5 to 2 mm). The stone is crushed and sized so that the 500 μm under (more desirably 100 μm under) is 40 mass% or more and the 22 μm under is 5 mass% or more to obtain the raw material of the granulated product P. The remaining iron ore not supplied to the second granulator is supplied to the first granulator.

In order to improve the productivity of sintered ore in the sintering machine, it is necessary to ensure the air permeability of the sintering machine.
Here, when fine powder of 1 mm or less, for example, is mixed in the iron ore charged into the sintering machine, the air permeability of the sintering machine is hindered. In addition, among the fine powders of 1 mm or less, for example, fine powders of 250 μm or less become adhering fine powders to the core particles of the S-type granulated product, so that the air permeability of the sintering machine can be prevented. Further, among fine powders of 1 mm or less, fine powders of more than 250 μm and 1 mm or less become core particles of S-type granulated material and intermediate particles that do not become adhering fine powders, which may still cause the air permeability of the sintering machine to be hindered. However, the conventional iron ore does not contain many of these intermediate particles, and it has been difficult to realize as a problem that deteriorates the productivity of the sintered ore in the sintering machine.

However, iron ore with a high crystal water content (3 mass% or more) whose supply amount has increased in recent years has a large amount of fine powder, and the problem of worsening the productivity of the sintered ore in the sintering machine becomes obvious.
Therefore, in the pretreatment method of the sintered raw material according to the fourth invention, for the purpose of improving the productivity of the sintered ore and suppressing or reducing the increase of the intermediate particles, the sieve mesh is 0.5 to 10 mm ( The lower limit is preferably 0.8 mm, and more preferably 1 mm. As a result, the yield of sintered ore is improved by optimizing the average fine powder adhesion thickness of the S-type granulated product, and the intermediate particles are pulverized and used as the raw material for the P-type granulated product to allow the air permeability of the sintering machine. Improved. In addition, it is not necessary to perform this sieving to all the iron ores supplied to the sintering machine, and it may be applied to at least one ore type or ore brand.
Moreover, as a sieving method, it can be performed using a conventionally known sieving machine.
The crushing under the sieve is not particularly limited as long as it is a method of reducing the particle diameter. It is preferable to use it. In this case, due to the pressing pressure of the roll, there is also an effect of granulation simultaneously with pulverization.
When the sieving iron ore after the pulverization does not have a predetermined particle size distribution, for example, when 22 μm under is less than 5 mass%, a fine powder with 22 μm under may be separately added and sized. When the addition is not necessary, the particles may be sized only by pulverization.

As mentioned above, in the pre-processing method of the sintering raw material which concerns on 1st, 2nd and 4th invention, as an iron ore (also called iron ore seed | species) each containing a coarse grain and a fine powder, for example, a maramamba ore (local brand name: West Angelus), pisolite ore (local brands: Yandy, Robe River), high phosphorus Brockman ore, etc. can be used. In addition, since a component structure and a particle size structure will generally change if a production brand is different, the case where a production brand is different is made into a different iron ore kind in this application.
Moreover, as a 1st, 2nd granulator, a drum mixer, an Eirich mixer, a disk pelletizer, a Prosha mixer etc. can be used, for example.

The pretreatment method of the sintering raw material according to the fifth invention is the pretreatment method of the sintering raw material according to the fourth invention, wherein the size of the sieve mesh is determined according to the fine powder adhesion average thickness of the granulated product S. By changing the thickness, the average thickness of the fine powder adhesion is within a predetermined range.
In the sintering raw material pretreatment method according to the fifth invention, the target predetermined range of the fine powder adhesion average thickness is 50 to 300 μm, preferably 50 to 250 μm, and more preferably 50 to 220 μm.

A sintering raw material pretreatment method according to a sixth invention is the sintering raw material pretreatment method according to the fourth invention, in which the size of the sieve mesh is changed and the sieve to the second granulating device is changed. Change the supply of iron ore below. Thereby, the production | generation according to the manufacturing capability of any one or both of the said 2nd granulation apparatus and the pre-processing apparatus with which this 2nd granulation apparatus is equipped can be performed.
Examples of the pretreatment device include a sieve sorter, a pulverizer, and a stirring device.
Here, the amount of iron ore supplied to the first and second granulators (for example, the iron ore supply ratio) can be controlled by changing the size of the sieve mesh. At this time, it is possible to adjust the particle size of the iron ore supplied to the first and second granulators.

The pretreatment method of the sintering raw material according to the seventh invention is the pretreatment method of the sintering raw material according to the first to third inventions, wherein the fine powder as the raw material of the granulated product P is pulverized, and an under 500 μm is present. Granulated in the presence of moisture after being sized so that 90 mass% or more and 22 μm under is more than 80 mass%.
The pretreatment method of the sintering raw material according to the eighth invention is the pretreatment method of the sintering raw material according to the fourth to sixth inventions, wherein the predetermined particle size of the sieving iron ore crushed and sized is 500 μm. Granulation is performed in the presence of 90 mass% or more of the under and more than 80 mass% of the 22 μm under and further in the presence of moisture.

The pretreatment method of the sintering raw material according to the ninth invention is the pretreatment method of the sintering raw material according to the first to third inventions, wherein the fine powder used as the raw material of the granulated product P is pulverized and an under 500 μm is present. The particles are sized so that 80 mass% or more and 22 μm under is more than 70 mass% and not more than 80 mass%, further granulated in the presence of moisture, and then dried.
The sintering raw material pretreatment method according to a tenth aspect of the invention is the sintering raw material pretreatment method according to the fourth to sixth aspects of the invention, wherein the iron ore under the sieve that has been crushed and sized has an underside of 500 μm and 80 mass. % And 22 μm under is more than 70 mass% and not more than 80 mass%, and is further granulated in the presence of moisture and then dried.

The pretreatment method of the sintering raw material according to the eleventh aspect of the invention is the pretreatment method of the sintering raw material according to the first to third aspects of the invention. The particles are sized so that 40 mass% or more and 22 μm under is 5 mass% or more and 70 mass% or less, further granulated in the presence of moisture and a binder, and then dried.
The pretreatment method of the sintering raw material according to the twelfth invention is the pretreatment method of the sintering raw material according to the fourth to sixth inventions, wherein the iron ore under the sieve that has been pulverized and sized is under 500 μm and 40 mass. % And under 22 μm is 5 mass% or more and 70 mass% or less, and further granulated in the presence of moisture and a binder and then dried.

As mentioned above, in the pre-processing method of the sintering raw materials according to the seventh to twelfth inventions, the P-type granulated material uses only the fine powder as the raw material or mainly uses the fine powder. It is necessary to increase the value to an appropriate value. For example, a plurality of belt conveyors are used to convey the granulated material, and the granulated material is pulverized at the connecting portion, and this is inserted into the sintering machine to impede the air permeability of the sintering machine. The granulated material may collapse in the pallet of the sintering machine and impair air permeability.
Such a situation is more prominent in the P-type granulated product than in the S-type granulated product. Therefore, it is necessary to take measures particularly in the P-type granulated product.

In general, when fine particles are granulated in the presence of a liquid, the strength of the granulated product may depend on the surface tension of the liquid (larger strength) and the particle diameter (smaller strength) from the Rumpf equation. Are known.
In addition to the above-mentioned known matters, the present inventors have newly paid attention to extremely fine particles incorporated in iron ore particles, and that these extremely fine particles can be effectively used to improve the strength of the granulated product. Newly found.
In recent years, when the iron ore particles of 50 μm to 1 mm of iron ore having a high content of crystallization water with an increased supply amount (3 mass% or more) were investigated, extremely fine particles having a particle size of submicron class from under 22 μm It has been found that there are iron ore species that may contain a lot of (for example, Maramamba ore, high phosphorus block man ore, etc.).
From this, the iron ore described above is pulverized and sized to take out the extremely fine particles contained therein, and (a) 500 μm under is 40 mass% or more and 22 μm under is 5 mass% or more, and (b) preferably 500 μm under. 80 mass% or more, and 22 μm under exceeds 70 mass%, (c) More preferably, 500 μm under is 90 mass% or more and 22 μm under exceeds 80 mass% particle size distribution, so that extremely fine particles are present, It is possible to expect further improvement in strength of the granulated product with the intervening.

In addition, the above-mentioned improvement in strength by extremely fine particles is manifested when the particle size is 80 mass% or more when the particle size is 500 μm and more than 70 mass% and less than 80 mass% when the particle size is 22 μm. Can be expected.
Therefore, in the pretreatment method of the sintered raw material according to the seventh and eighth inventions, the iron ore is prepared in the presence of moisture so that the particle size of the iron ore is not less than 90 mass% for 500 μm under and over 80 mass% for 22 μm under. The desired strength can be obtained by granulating.
In the pretreatment method of the sintered raw material according to the ninth and tenth inventions, the average particle size of the iron ore is such that the particle size of the iron ore is not less than 80 mass% for 500 μm under and more than 70 mass% for under 22 μm. The increase in the diameter is compensated by drying performed after granulation in the presence of moisture to further improve the strength.

And in the pre-processing method of the sintering raw material which concerns on 11th and 12th invention, the particle size of the iron ore is the average particle diameter by having made 500 micrometer under 40 mass% or more and 22 micrometer under 5 mass% or more and 70 mass% or less. The increase is compensated by using moisture and a binder, and after granulating this, it is compensated by drying to further improve the strength.
Although the binder contributes to the improvement of the strength of the granulated product, the conventional inorganic binders such as quick lime and limestone need to be mixed in the granulated product, and thus need to be pulverized. When using a binder such as an aqueous solution such as cornstarch or a colloidal organic substance, a dispersant that promotes solid crosslinking (including an aqueous solution or colloid added with a dispersant), etc. Is preferred.

A sintering raw material pretreatment method according to a thirteenth invention is the sintering raw material pretreatment method according to the ninth to twelfth inventions, wherein the drying temperature of the granulated product P is 40 ° C. or higher and 250 ° C. or lower. . In the pretreatment method of the sintering raw material according to the thirteenth invention, the iron ore that is the raw material of the P-type granulated material is, for example, one having a high crystallization water content (3 mass% or more). The drying temperature is set to suppress and further prevent water decomposition.

The sintering raw material pretreatment method according to a fourteenth aspect of the present invention is the sintering raw material pretreatment method according to the first to thirteenth aspects of the invention, wherein the size of the granulated product P is in the range of 1 to 10 mm.
In the pretreatment method of the sintering raw material according to the fourteenth invention, when the size of the P-type granulated product exceeds 10 mm, the center of the P-type granulated product can be sintered at the time of producing the sintered ore. This is not possible and the quality of the sintered ore is reduced. On the other hand, when the size of the P-type granulated product is less than 1 mm, it is densely filled when charged into the sintering machine, and improvement in the air permeability of the sintering machine cannot be expected.
Therefore, the lower limit of the size of the P-type granulated product is defined as 1 mm, preferably 2 mm, more preferably 3 mm, and the upper limit is defined as 10 mm, preferably 9 mm, more preferably 8 mm. It is possible to appropriately sinter the mold granulated material up to the inside thereof to produce a sintered ore of good quality.

The pretreatment method of the sintering raw material according to the fifteenth aspect of the invention is the pretreatment method of the sintering raw material according to the first to fourteenth aspects of the invention, wherein the raw material is further added with an iron-containing raw material consisting essentially of fine powder. It has been. In the sintering raw material pretreatment method according to the fifteenth aspect of the present invention, examples of the iron-containing raw material consisting of only fine powder include dust having a particle size of about 100 μm or less (kneaded dust, dust dust), pellet raw material having about 250 μm or less (pellet) Feed: PF) or the like can be used.

In the pretreatment method of the sintering raw material according to the sixteenth aspect of the present invention, the granulated product containing at least a portion of iron ore having a crystallization water content of 3 mass% or more and granulated in the presence of moisture, When drying before charging into the sintering machine, drying is performed at 40 ° C. or more and 250 ° C. or less.
In the pretreatment method of the sintering raw material according to the sixteenth invention, examples of the iron ore having a crystal water content of 3 mass% or more include maramamba ore, pisolite ore, and high phosphorus block man ore. Thus, in the granulated product of iron ore having a high crystallization water content (3 mass% or more), when the crystallization water is decomposed, the granulated product is disintegrated and powdered.
For this reason, in the pretreatment method of the sintering raw materials according to the thirteenth and sixteenth inventions, the lower limit of the drying temperature is 40 ° C., preferably 100 ° C., the upper limit is 250 ° C., preferably 240 ° C. The theoretical temperature for decomposition is preferably 239 ° C.

A sintering raw material pretreatment method according to a seventeenth aspect of the present invention in accordance with the above object is the sintering raw material pretreatment method according to the first to fifteenth aspects of the invention, wherein the iron ore having a crystal water content of 3 mass% or more is used. Used for some or all of the raw materials.
In the pretreatment method of the sintering raw material according to the seventeenth invention, examples of the iron ore having a crystallization water content of 3 mass% or more include, for example, maramamba ore (local brand: West Angelus), pisolite ore (local brand: Yandy, Low ribber), high phosphorus block man ore, etc. can be used. In general, since the composition of constituents and the composition of grain sizes change when the production brand is different, it is better to treat it as a different iron ore species when the production brand is different.
Furthermore, as a ratio of using iron ore with a crystal water content of 3 mass% or more, 40 mass% or more of new raw materials of iron ore (excluding return ore used as raw materials after passing through a sintering machine) An iron ore with a crystal water content of 3 mass% or more is preferable. This is because when the amount is 40 mass% or more, the increase in fine powder becomes remarkable and the effect of the invention becomes remarkable. This is because if it is less than 40 mass%, the effect of the invention is obtained, but not significant.

The pretreatment method of the sintering raw material according to the first invention and the seventh, ninth, eleventh, thirteenth to fifteenth, and seventeenth inventions subordinate thereto is the fine powder into the core particles of the granulated product S. Since the amount of fine powder blended into the first granulator is adjusted so that the average adhesion thickness is optimized, a sintered ore with good quality can be produced. Moreover, since the remainder fine powder which is not supplied to the 1st granulator is used as a raw material of a 2nd granulator, the granulated material which improved granulation property and intensity | strength compared with the past can be manufactured easily.
In this way, it is possible to provide a sintering raw material pretreatment method that can cope with iron ore raw materials containing a larger amount of fine powder than before.

The pretreatment method of the sintering raw material according to the second invention and the third, seventh, ninth, eleventh, thirteenth to fifteenth, and seventeenth inventions subordinate thereto is the core particle of the granulated product S. Since the amount of coarse particles blended in the first granulator is adjusted so that the average fine powder adhesion thickness is optimized, it can cope with iron ore raw materials containing a larger amount of fine powder than before, It is possible to produce sintered ore with quality.
In particular, the pretreatment method of the sintering raw material according to the third invention is the first granulation of coarse particles in the iron ore excluding fine powder supplied to the second granulating apparatus for producing the granulated product P. Since it supplies to an apparatus, the iron ore of the particle size suitable for manufacture of the granulated material S and the granulated material P can be used, for example, without performing a grinding | pulverization process etc., and a granulated material can be manufactured economically.

The pretreatment method of the sintering raw material according to the fourth invention and the fifth, sixth, eighth, tenth, twelfth to fifteenth, and seventeenth inventions subordinate thereto is the sieving on the sieve With this iron ore, the average fine powder adhesion thickness of the S-type granulated product can be optimized, and the yield of sintered ore can be improved. Moreover, the air permeability of a sintering machine can be improved by grind | pulverizing and sizing the iron ore under the sieve which performed sieving, and using it for the raw material of a P-type granulated material.

Since the pretreatment method of the sintering raw material according to the fifth invention changes the size of the sieve according to the average fine powder adhesion thickness of the granulated product S, for example, a change in the particle size distribution of the iron ore used occurs. Even in such a case, a granulated product capable of improving the air permeability of the sintering machine can be easily produced.

Since the pretreatment method of the sintering raw material according to the sixth invention changes the size of the sieve mesh and changes the supply amount of the iron ore under the sieve to the second granulation apparatus, for example, the granulated material P The production according to the production capacity of the second granulation apparatus and the pretreatment apparatus can be performed, and the granulated product P can be produced stably even when the particle size distribution of the iron ore used changes.

In the pretreatment method of the sintered raw material according to the seventh and eighth inventions, the iron ore is granulated in the presence of water so that the particle size of the iron ore is 90 mass% or more for 500 μm under and 80 mass% for 22 μm under. Thus, a granulated product P having a desired strength can be produced depending on the surface tension and particle diameter of the liquid.

In the pretreatment method of the sintered raw material according to the ninth and tenth inventions, the average grain size of the iron ore is such that the particle size of iron ore is 80 mass% or more for 500 μm under and more than 70 mass% for 80 μ% or less for 22 μm under. The increase in the diameter can be compensated by drying performed after granulation in the presence of moisture, and a granulated product P with further improved strength can be produced.

In the pretreatment method of the sintered raw material according to the eleventh and twelfth inventions, the average particle size of the iron ore is such that the particle size of iron ore is 40 mass% or more of 500 μm under and 5 mass% or more and 70 mass% or less of 22 μm under. It is possible to manufacture a granulated product P that is further improved in strength by supplementing the increase in water using moisture and a binder, granulating this, and then compensating by drying.

Since the sintering raw material pretreatment method according to the thirteenth and sixteenth inventions has a drying temperature of 40 ° C. or higher and 250 ° C. or lower, the decomposition of the crystal water is suppressed and further prevented, and the granulated material collapses. It is possible to suppress and further prevent powdering.

Since the pretreatment method of the sintering raw material according to the fourteenth invention regulates the size of the granulated product P in the range of 1 to 10 mm, the sintering of the granulated product P in the sintering machine can be performed up to the inside. Properly, it becomes possible to produce a sintered ore of good quality, and it becomes possible to improve the yield of the sintered ore than before.

The pretreatment method of the sintering raw material according to the fifteenth aspect of the present invention can use fine powder, for example, iron ore such as dust, pellet raw material, etc., which tends to be restricted in conventional usage, without restriction.

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 sintering raw material pretreatment method according to an embodiment of the present invention, and FIG. 2 is an explanatory view showing the influence of the fine powder adhesion thickness of the S-type granulated product on the coke combustion index. FIG. 3 is an explanatory diagram showing the crushing strength required for suppressing the collapse of the P-type granulated product, and FIG. 4 is an explanatory diagram showing the influence of the production conditions of the P-type granulated product on the crushing strength.

As shown in FIG. 1, the sintering raw material pretreatment method according to one embodiment of the present invention includes three types of iron ore containing coarse grains and fine powder, that is, a psolite ore, a maramamba ore, and a high phosphorus block. S-type granulated product (granulated product S) made of man ore as raw material and fine particles adhering to coarse particles as core particles, and P-type granulated product (granulated product P) granulated mainly with fine powders It is a method of manufacturing. In addition, iron ore substantially consisting only of fine powder, that is, kneaded dust generated in the steel mill, pellet feed (ore type: MBR-PF), and other iron ores are further added to the raw material. This will be described in detail below.

Maramamba ore, pisolite ore, and high phosphorus block man ore are also called limonite (Fe ₂ O ₃ · nH ₂ O), and are iron ores with a crystal water content of 3 mass% or more. In this embodiment, it has a coarse particle of about 8 mm) to a fine powder of 250 μm or less.
S-type granulation is produced using this pisolite ore, fine coke, other iron ores, and limestone, and P-type granulation using maramamba ore, high phosphorus blockman ore, kneaded dust, and pellet feed Manufacturing things.

First, the manufacturing method of S type granulated material is demonstrated.
As shown in FIG. 1, pisolite ore containing coarse particles and fine powder is sieved by a sieve sorter 10. In addition, in this Embodiment, although the thing of 3 mm was used as a sieve mesh of the sieve sorter 10, it is not limited to this.
Since the iron ore on the sieved sieve is coarse, it is used as the core particle as it is without being treated. On the other hand, the iron ore under the sieve is charged into the Eirich mixer 11 and is kneaded and granulated with a binder such as limestone.

The above-mentioned kneaded granulated material is charged into an S-type drum mixer (an example of a first granulating device) 12 together with powdered coke, other iron ores, and limestone, and powdered coke, etc. around the core particles Iron ore and fine powder (for example, 250 μm or less) contained in limestone are adhered. Thereby, the S type granulated product in which the average thickness of the fine powder adhered to the periphery of the core particle is 50 to 300 μm is manufactured. At the time of production of the S-type granulated product, some of the particles having a particle size exceeding 250 μm contained in the powdered coke, other iron ores, and limestone, together with the S-type granulated product, are drum mixers for S type. 12 is discharged from the inside.

Here, the reason why the average fine powder adhesion thickness of the S-shaped granule is defined in the range of 50 to 300 μm will be described with reference to FIG.
The average fine powder adhesion thickness, which is the horizontal axis in FIG. 2, was calculated by the following procedure using the produced S-shaped granulated product.
(1) First, the target raw material is completely separated into fine particles, coarse particles, etc. by washing with water, etc., and sieved under the sieve order of 5 mm, 2 mm, 1 mm, 0.5 mm, and 0.25 mm. Then, the weight ratio of each particle size section was obtained (weight g of each particle size section when the whole is 100 g).

(2) The representative particle diameter (7.5 mm, 3.5 mm, and 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 the core particles was determined to be 100 g as a whole. The number of core particles for each representative particle size was calculated from the weight ratio of each particle size section. 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, which becomes a powder adhering to the core particles, for each core particle section, each core particle section is proportional to the core particle weight ratio of each core particle section. The weight of fines to be dispensed 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) and the fine powder weight distributed and determined in (3). At that time, the bulk density of the adhered powder layer was set to 2 g / cm ³ .
(5) The weight of the adhered powder in each core particle section was weighted and averaged with the weight ratio of each particle section to obtain the fine powder deposited average thickness.

The coke combustion index on the vertical axis in FIG. 2 corresponds to the yield of sintered ore obtained by sintering the S-type granulated product, and as the coke combustion index increases, Yield is also improved.
FIG. 2 shows the relationship between the fine powder adhesion thickness (μm) and the coke combustion index in a test in which raw materials having various particle size distributions were granulated and then sintered in a pan test.
As shown in FIG. 2, the coke combustion index increased with increasing thickness until the fine powder adhesion thickness reached 100 μm, and thereafter decreased with increasing thickness.
Considering that the above does not affect the yield deterioration of the sintered ore, the average fine powder adhesion thickness is defined as 50 to 300 μm, preferably the upper limit is 250 μm, more desirably 220 μm. .

Based on the above knowledge, there are three types of S that have a fine powder adhesion average thickness of 204 μm (current situation), a thinner adhesion thickness of 88 μm, and a thicker adhesion thickness of 327 μm. Mold granulated materials were prepared, and each S-shaped granulated material was charged into a sintering machine, and the influence on the yield of sintered ore was investigated.
In addition, since each S type granulated material is manufactured under a fixed amount of iron ore, the 327 μm S type granulated material (only pulverized) is obtained by pulverizing iron ore with an insufficient amount of fine powder. It was manufactured by adhering to the periphery of the core particles and charged into a sintering machine. The 88 μm S-type granulated product was produced by granulating the remaining fine powder not used in the S-type granulated product. The mold is granulated (pelletized) and charged into the sintering machine. Here, the survey result of the 88 μm S-type granulated product is not only the result of the S-type granulated product, but the blending amount of the P-type granulated product is small (for example, S-type granulated product and P-type granulated product). 20-30 mass% of the total amount of the product), and since powder coke as a heat source is not contained in the P-type granulated product, the obtained result can substantially correspond to the result of the S-type granulated product Conceivable.
As a result of the above investigation, the yield of sintered ore along the coke combustion index of the result of the pan test in FIG. 2 was obtained.

Next, the manufacturing method of P type granulated material is demonstrated.
As shown in FIG. 1, the maramamba ore and the high phosphorus block man ore containing coarse particles and fine powder are sieved by a sieve sorter 13. In addition, the sieve mesh of the sieve sorter 13 is set in a range of 0.5 to 10 mm (3 mm in the present embodiment). The iron ore under the sieve that has been sieved by the sieve sorter 13 is pulverized by a pulverizer 15 and charged into a mixer 17 together with kneaded dust and pellet feed (MBR-PF) and mixed. In addition, the sieve sorter 13 and the pulverizer 15 each constitute a pretreatment device.
At this time, subsequent processing is performed according to the pulverized particle size distribution of the iron ore used to produce the P-type granulated product.

When sieving iron ore that is the raw material of P-type granulated material is pulverized and sized so that 500 μm under 90% or more and 22 μm under 80% by mass, P-type drum mixer (second granulation An example of an apparatus) 18 is charged, granulated using water (for example, 5 to 15 mass% in an external portion), and then sieved by a sieve sorter 19. In addition, when sieving iron ore that is a raw material for P-type granulated material is pulverized and sized so that the 500 μm under is 80 mass% or more and the 22 μm under is more than 70 mass% and not more than 80 mass%, the P type drum After being charged into the mixer 18 and granulated using water (for example, 5 to 15 mass% as an external component), the mixture is sieved with a sieve sorter 19 and further dried with a dryer 20.
And when sieving iron ore that is the raw material of P-type granulated material, and sized so that 500 μm under is 40 mass% or more and 22 μm under is 5 mass% to 70 mass%, P type drum mixer 18, for example, an organic binder such as pulp waste liquid and corn starch (for example, preferably 0.01 to 3% by mass, more preferably 0.1 to 3% by mass) and After granulation using water (for example, 5 to 15 mass% as an external component), the mixture is sieved with a sieve sorter 19 and further dried with a dryer 20.
In addition, drying is performed in an atmosphere set to 40 ° C. or higher and 250 ° C. or lower, for example, for about 20 to 60 minutes. Moreover, when measuring mass% of fine powder particles such as 500 μm under and 22 μm under, a laser diffraction scattering measuring instrument (MICROTRAC FRA type, measurement range: 0.1 to 700 μm manufactured by Nikkiso Co., Ltd.) was used.

Here, the reason why each of the subsequent processes is changed according to the particle size distribution of the crushed and sized iron ore will be described.
When fine powder is used as a raw material for a P-type granulated product (hereinafter also referred to as pellets), the strength (crushing strength) of the P-type granulated product is low, and it is necessary to increase this strength to an appropriate value. For this reason, if this necessary strength is defined in consideration of having a strength that does not cause any problem even if the belt conveyor (not shown) is connected five times or more (equivalent to an actual machine connection), the diameter is as shown in FIG. It turns out that the intensity | strength of 2 kgf (2kgf / 10mmphi * 1 piece) or more is required per 10 mm P-type granulated material.
Therefore, a processing method that satisfies this 2 kgf / 10 mmφ · 1 or more will be described with reference to FIG. In addition, the used raw material is what crushed 3 mm or less of maramamba ore, pellet feed, and kneaded dust.

As shown in FIG. 4, (1) pulverization treatment only, (2) pulverization treatment and drying treatment, (3) pulverization treatment, drying treatment, and binder addition treatment, (1) → (2) → The tendency of the crushing strength of the pellets to increase as (3) was obtained. The amount of water used for granulation is 10% by mass in the outer portion, the amount of binder (pulp waste liquid) added is 1% by mass in the outer portion, and drying is performed at 250 ° C. for 30 minutes, and is contained in the granulated product. The amount of water was reduced to 5 mass% with an external component. Here, when the iron ore is only pulverized, if the average particle size is 20 μm or less (500 μm under is 90 mass% or more and 22 μm under is over 80 mass%), the produced pellet is 2 kgf / 10 mmφ × 1 piece. The above conditions can be satisfied.

Further, when this granulated product is further subjected to a drying treatment, the average particle size is increased to 100 μm or less (500 μm under is 80 mass% or more and 22 μm under is more than 70 mass% and 80 mass% or less). The condition of 2 kgf / 10 mmφ · 1 or more can be satisfied.
Furthermore, when the granulated product to which the binder has been added is subjected to a drying treatment, the average particle size is further increased to 700 μm or less (500 μm under is 40 mass% or more and 22 μm under is 5 mass% or more and 70 mass% or less). The satisfied pellets can satisfy the condition of 2 kgf / 10 mmφ · 1 or more.
From the above, the above-described treatment was performed according to the pulverized particle size.

The sieve mesh of the sieve sorter 19 for sieving the granulated product granulated by the P-type drum mixer 18 is adjusted so that the granulated product having a particle size in the range of 1 to 10 mm can be sieved. Yes. The granulated product having a particle size of less than 1 mm is charged again into the mixer 17 without being processed, and the granulated product having a particle size of more than 10 mm is crushed by a crusher (not shown) and again. The particle size is adjusted by charging the mixer 17.
Thereby, as described above, the granulated product whose particle diameter is adjusted to the range of 1 to 10 mm is subjected to a drying treatment as necessary to become a P-type granulated product.

In addition, the iron ore on the sieve generated by sieving the maramamba ore and the high phosphorus block man ore with the sieve mesh set in the range of 0.5 mm to 10 mm of the sieve sorter 13 in the production of the P-type granulated product. Is not suitable as a raw material for P-type granules. As described above, if the pulverization treatment is not performed, it is difficult to ensure the strength of the manufactured P-type granulated product, and there is a relatively large pulverization load compared to the sieving iron ore. This is because a load is applied. Therefore, the iron ore on the sieve is mainly used as the core particle of the S-type granulated product without being pulverized.
Thus, the fine powder contained in the Mara Mamba ore and the high phosphorus block man ore is adjusted to a state in which the fine powder blending amount is adjusted by the mesh of the sieve sorter 13, that is, not supplied to the S-type drum mixer 12. The remainder that is not supplied to the drum mixer 12 as much as possible, that is, almost all the fine powder, is used as a raw material for the P-type drum mixer 18.

Here, according to the fine powder adhesion average thickness of the S-type granulated product, the sieve mesh of the sieve sorter 13 is changed in size, and the iron ore in the iron ore excluding the fine powder supplied to the P-type drum mixer 18 is used. By adjusting the blending amount of the coarse particles into the S-type drum mixer 12, the average fine powder adhesion thickness can be set to a target predetermined range of 50 to 300 μm.
For example, when the fine powder adhesion average thickness of the S-type granulated product increases due to the change in the particle size distribution of the iron ore used, it is supplied to the S-type drum mixer 12 using a sieve mesh close to 1 mm within a range of 1 mm or more. By increasing the amount of core particles of the S-shaped granulated product, the average fine powder adhesion thickness can be optimized. On the other hand, for example, when the fine powder adhesion average thickness of the S-type granulated material decreases due to the change in the particle size distribution of the iron ore used, the S-type supplied to the S-type drum mixer 12 using a sieve mesh close to 10 mm. By reducing the amount of core particles in the mold granulated product, the average fine powder adhesion thickness can be optimized.

Further, the sieve mesh of the sieve sorter 13 is changed in size according to the production capacity of one or both of the P-type drum mixer 18 and the pretreatment device, and the supply amount of iron ore to each device is changed. Can be controlled (changed).
For example, if there is a margin in the production capacity of each device for producing P-type granulated material due to changes in the particle size distribution of the iron ore used, the raw material for producing P-type granulated material using a sieve mesh close to 10 mm The supply amount of can be increased. On the other hand, for example, when the production capacity of each device for producing a P-type granulated product is insufficient due to a change in the particle size distribution of the iron ore to be used, a sieve mesh close to 0.5 mm is used, and the P-type granulated product is used. The amount of raw material to be manufactured can be reduced. At this time, when the iron ore under the sieve is temporarily stocked (stored) and the capacity of each device for producing the P-type granulated material is sufficient, measures such as processing the stocked iron ore should be taken. It can also be used as necessary.

Moreover, when adjusting the sieve mesh of the sieve sorter 13, intermediate particles (for example, more than 250 μm and 1 mm or less) that are difficult to become core particles contained in the iron ore on the sieve do not adhere to the S-type granulated product. It is often discharged from the S-type drum mixer 12. In addition, this intermediate particle can be used as a raw material for the P-type granulated product by pulverization or as an adhering fine powder of the S-type granulated product.
The S-type granulated product and the P-type granulated product produced by the above method are sintered without being mixed so that, for example, 70 to 80 mass% of the total amount becomes the S-type granulated product. 21 is charged to produce sintered ore.
As a result, it is possible to cope with iron ore raw materials containing a larger amount of fine powder than before, producing granulated products with improved granulation properties and strength, and producing sintered ores with good quality. it can.

As described above, the present invention has been described with reference to one embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and is described in the claims. Other embodiments and modifications conceivable within the scope of the above are also included. For example, a case in which the sintering raw material pretreatment method 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 present invention.
Moreover, in the said embodiment, although the case where a pisolite ore, a maramamba ore, and a high phosphorus block man ore were used as three types of iron ores containing a coarse grain and a fine powder, respectively, a coarse grain and a fine powder were respectively used. 2 or more types of iron ores may be used, for example, use of pisolite ore and maramamba ore, and other iron ores such as magnetite (Fe ₃ O ₄ ), hematite (Fe ₂ O ₃ ) Etc. can also be used. Of course, it is also possible to configure the raw materials by adding other iron sources, for example, iron sources generated in the ironworks, to these iron ores.
And in the said embodiment, when manufacturing the P-type granulated product, when the particle size after pulverization and pulverization of the fine powder is set to 90 mass% or more for 500 μm under and 80 mass% for 22 μm under, a binder is added. However, it is also possible to perform either one or both of binder addition and drying treatment as necessary. In addition, when the particle size after pulverization and pulverization of the fine powder is 80 mass% or more for 500 μm under and more than 70 mass% and not more than 80 mass% for 22 μm under, granulation is performed without adding a binder, followed by drying treatment and baking. Although it was charged into the kneading machine, it is possible to add a binder as required.

It is explanatory drawing of the pre-processing method of the sintering raw material which concerns on one embodiment of this invention. It is explanatory drawing which shows the influence of the fine powder adhesion thickness of S type granulated material which acts on a coke combustion index. It is explanatory drawing which shows the crushing intensity | strength required for the collapse suppression of P-type granulated material. It is explanatory drawing which shows the influence of the manufacturing conditions of P type granulated material which gives to crushing strength.

Explanation of symbols

10: Sieve sorter, 11: Eirich mixer, 12: S-type drum mixer (first granulator), 13: Sieve sorter, 15: Crusher, 17: Mixer, 18: P-type drum Mixer (second granulator), 19: sieve sorter, 20: dryer, 21: sintering machine

Claims (1)

When the granulated product containing iron ore having a crystal water content of 3 mass% or more in at least a part and granulated in the presence of moisture is dried before being charged into a sintering machine, it is 40 ° C. or more and 250 ° C. A pretreatment method of a sintering raw material characterized by drying in the following.

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