JP5547879B2 - Carbonaceous material-incorporated iron oxide agglomerate, method for producing the same, and method for producing reduced iron or metallic iron - Google Patents

Description

  The present invention relates to a carbonaceous material-containing iron oxide agglomerate used as a raw material for a rapid heating reduction furnace such as a rotary hearth type reduction furnace for producing reduced iron or metallic iron. Moreover, this invention relates to the manufacturing method of this carbon material interior iron oxide agglomerate, and the method of manufacturing reduced iron or metallic iron from this carbon material interior iron oxide agglomerate.

  The conventional reduced iron production process has limitations such as requiring expensive natural gas as a reducing agent and that the location of the plant is usually limited to the production area of natural gas.

  For this reason, in recent years, a process for producing reduced iron using coal, which is relatively inexpensive and has reduced geographical restrictions on plant location, has attracted attention as a reducing agent.

  As a method of using this coal, a carbonaceous material-containing iron oxide agglomerated material (hereinafter simply referred to as “agglomerated material”) obtained by agglomerating a powdery mixture of iron ore (iron oxide raw material) and coal (carbonaceous material). Many methods have been proposed for producing solid reduced iron by charging it in a rotary hearth furnace (rapid heating reduction furnace) and heating and reducing it in a high temperature atmosphere (for example, Patent Document 1). , 2).

  Further, as in the above method, the carbonaceous material-containing iron oxide agglomerate is charged into a rotary hearth type reduction furnace (rapid heating reduction furnace), and in a higher temperature atmosphere than the method of producing the above solid reduced iron. There has also been proposed a method for producing high-quality granular metallic iron by heating and reducing and melting to separate a slag component (see Patent Document 3).

  Generally, pellets or briquettes are employed as the carbonized iron oxide agglomerates used as raw materials for these rotary hearth type reduction furnaces (rapid heating reduction furnaces).

  As pellets, for example, iron ore whose particle size is adjusted to contain 80% by mass or more with a pulverizer or the like, coal whose particle size is adjusted similarly, and basicity adjustment such as limestone if necessary In addition, an organic binder such as starch and granulated water are added as a binder, and granulated into raw pellets having an average particle size of 13 to 19 mm with a pelletizer, and this is dried with a dryer. In the temperature range of 80 to 220 ° C. at which the organic binder does not burn, a material dried to a moisture content of 1% by mass or less is used (see Patent Document 4).

In addition, as briquettes, for example, iron ore whose particle size is adjusted to contain 80% by mass or more in a pulverizer or the like, similarly to coal whose particle size is adjusted, and base such as limestone if necessary. After adding an organic binder such as starch and granulating water, and forming into a raw briquette having a volume of about 10 cm ^{3 with} a briquette machine, the pellet is mixed with the above pellets. In the same temperature range of 80 to 220 ° C., the one dried to a moisture content of 1.0% by mass or less is used.

  In this way, the agglomerates such as pellets and briquettes are dried to an adhering moisture content of 1% by mass or less when the adhering moisture content in the agglomerates is high, the furnace atmosphere temperature is usually higher than 1000 ° C. The agglomerates are rapidly heated when charged in the rotary hearth type reduction furnace (rapid heating furnace) held in the chamber, and the water adhering to the inside suddenly becomes water vapor. This is to prevent the explosion from bursting.

  On the other hand, in recent years, the quality of iron ore tends to deteriorate globally, and in particular, the production rate of so-called high crystal water ore containing a large amount of crystal water is increasing. For this reason, although the development of a large amount of technology for using high-crystal water ore to sinter or pellets, which are blast furnace raw materials, has been actively conducted, from the viewpoint of maintaining quality as blast furnace raw materials, There is a limit to the use of high crystal water ore. Therefore, there is a need to actively use high crystal water ore for the carbonized iron oxide agglomerates that are raw materials such as reduced iron.

  However, when the agglomerated material is produced by the above-mentioned method using high-crystal water ore as the iron oxide raw material, the adhering water can be removed with a dryer, but the dissociation temperature of crystal water is usually 250 ° C. or higher. Since it is higher than the temperature (80-220 ° C.), it can hardly be removed in advance. Therefore, when the agglomerate is charged into the rotary hearth furnace (rapid heating reduction furnace) and rapidly heated while containing crystal water, the crystal water dissociates inside the agglomerate and the water vapor pressure rises rapidly. It is conceivable that water vapor cannot overflow from the gaps between the particles constituting the agglomerated material and the agglomerated material bursts (bursting). Moreover, since coal normally used as a carbon material has a volatile component, this volatile component is also devolatilized by rapid heating and gasified, and combined with the water vapor derived from the crystal water further increases the gas pressure inside the agglomeration. There is concern.

  As a means for avoiding such a bursting problem, as disclosed in Patent Document 5, a pre-tropical zone is provided in the front stage of the heating zone of the rotary hearth type reducing furnace, for example, in the pre-tropical zone. After preheating in a relatively low temperature range of about 300 to 500 ° C. to remove crystallization water and volatile matter while preventing bursting, reduction is performed by heating in a heating zone at a high temperature range of 1000 ° C. or higher. However, if the size of the reduction furnace is maintained, the productivity of reduced iron, etc. will be greatly reduced, while if the productivity of reduced iron, etc. is ensured, there will be a problem that the reduction furnace will be significantly enlarged. .

Further, as another means for avoiding the above bursting problem, it is conceivable to increase the strength of the agglomerate by increasing the amount of the organic binder, but a large amount of expensive organic binder is used. Since it is necessary, the production cost of the agglomerated product increases, and as a result, there is a problem that the production cost of reduced iron and the like increases.
JP 2004-269978 A JP-A-9-192896 JP 2002-339909 A Japanese Patent No. 3040978 JP 11-337264 A

  Accordingly, the present invention provides a rapid heating reduction without causing a decrease in productivity of reduced iron or the like, an increase in the size of a reduction furnace, or an increase in production cost of reduced iron or the like even when a high crystal water ore is used as an iron oxide raw material. An object of the present invention is to provide a carbonaceous material-containing iron oxide agglomerate that can reliably prevent bursting in the furnace. Another object of the present invention is to provide a method for producing this carbonaceous material-incorporated iron oxide agglomerate and a method for producing reduced iron or metallic iron from this carbonaceous material-incorporated iron oxide agglomerate.

  The inventor is concerned about the bursting when the carbonaceous material-containing iron oxide agglomerate using the high crystal water ore is charged into the rapid heating reduction furnace, as described above, the dissociation of the crystal water, The iron ore with various crystal water contents and coal with various volatile contents are considered to be caused by the pressure increase inside the agglomerate due to the gas generated by the devolatilization of volatile components in the interior carbon materials such as coal. The agglomerated material was produced by combining with the above, and this was charged into a small heating furnace in a high temperature atmosphere to investigate the presence or absence of bursting. As a result, it was found that the presence or absence of the occurrence of bursting can be arranged by the total content of crystal water and volatile matter in the agglomerated product.

  Based on the above findings, further studies have been made and the following invention has been completed.

The invention according to claim 1 is a carbonaceous material-containing iron oxide agglomerate used as a raw material for a rapid heating reduction furnace, and the volatilization of crystal water and carbonaceous material in the carbonaceous material- incorporated iron oxide agglomerated product. A carbonaceous material-containing iron oxide agglomerate having a total content of 10.5% by mass or less (dry basis, the same shall apply hereinafter) and a moisture content of 1.0% by mass or less It is. Here, “attached moisture” refers to moisture that physically adheres to the surface of the particles constituting the carbonaceous material-containing iron oxide agglomerated material.

  The invention according to claim 2 is the carbonaceous material-incorporated iron oxide agglomerated product according to claim 1, wherein the content of the crystal water in the carbonaceous material-incorporated iron oxide agglomerated product is 4% by mass or more.

The invention according to claim 3, charcoal according to claim 1 or 2 basicity of the carbonaceous material furnished oxide TetsukatamariNaru product (CaO / SiO ₂₎ is 0.5 to 1.5 in mass ratio It is an iron oxide agglomerated material.

The invention according to claim 4 is a method for producing a carbonaceous material-containing iron oxide agglomerate used as a raw material for a rapid heating and reduction furnace, wherein The step of blending the iron oxide raw material and the carbonaceous material so that the total content with the volatile matter of the carbonaceous material is 10.5% by mass or less, and granulating the iron oxide raw material and the carbonaceous material into an agglomerated product And a step of drying the agglomerated product until the content of adhering moisture in the agglomerated product is 1.0% by mass or less. Is the method.

  The invention according to claim 5 is characterized in that, in the step of blending the iron oxide raw material and the carbonaceous material, the crystallization water content in the carbonaceous material-incorporated iron oxide agglomerated product is 4% by mass or more. It is a manufacturing method of the carbonaceous material interior iron oxide agglomerate of Claim 4 which mix | blends an iron oxide raw material and the said carbonaceous material.

According to a sixth aspect of the present invention, in the step of blending the iron oxide raw material and the carbonaceous material, the basicity (CaO / SiO ₂ ) of the carbonaceous material-incorporated iron oxide agglomerated product is 0.5 to 1. It is a manufacturing method of the carbonaceous material interior iron oxide agglomerate of Claim 4 or 5 which mix | blends the said iron oxide raw material and the said carbonaceous material so that it may become 5 or less.

  The invention according to claim 7 is the carbonaceous material-incorporated iron oxide agglomerated product according to any one of claims 4 to 6, wherein a calcium oxide supply substance is further blended in the step of blending the iron oxide raw material and the carbonaceous material. It is a manufacturing method.

The invention according to claim 8 is a method for producing reduced iron, the step of charging a carbonaceous material-containing iron oxide agglomerate into a rapid heating reduction furnace, A step of heating the carbonaceous material-containing iron oxide agglomerate by moving the temperature inside the rapid heating reduction furnace from a region of 200 ° C. or less to a region of 1000 ° C. or more in a time of 20 seconds or less; A step of reducing the iron oxide of the material-incorporated iron oxide agglomerate to reduced iron with a carbonaceous reducing agent in the carbonaceous material-incorporated iron oxide agglomerate, and a step of cooling and solidifying the reduced iron, The material-incorporated iron oxide agglomerated product has a total content of crystallization water and a volatile content of the carbon material in the carbonized material-incorporated iron oxide agglomerated material of 10.5% by mass or less, and a content of adhering moisture of 1.0. It is a manufacturing method of reduced iron characterized by being below mass%.

  The invention according to claim 9 is the method for producing reduced iron according to claim 8, wherein the carbonaceous material-incorporated iron oxide agglomerate has a content of the crystal water of 4% by mass or more.

The invention according to claim 10 is characterized in that the carbonaceous material-containing iron oxide agglomerate has a basicity (CaO / SiO ₂ ) of 1.5 or less in mass ratio. It is a manufacturing method.

The invention according to claim 11 is a method for producing metallic iron, the step of charging a carbonaceous material-containing iron oxide agglomerate into a rapid heating reduction furnace, A step of heating the carbonaceous material-containing iron oxide agglomerate by moving the temperature inside the rapid heating reduction furnace from a region of 200 ° C. or less to a region of 1000 ° C. or more in a time of 20 seconds or less; Reducing the iron oxide of the material-incorporated iron oxide agglomerate with a carbonaceous reducing agent in the carbonaceous material-incorporated iron oxide agglomerate to produce metallic iron and by-produce slag; and The carbonaceous material-incorporated iron oxide agglomerated product is a crystal water in the carbonized material-incorporated iron oxide agglomerated product, comprising the steps of agglomerating in granular form while separating from the slag, and cooling and solidifying the metallic iron. the total content of 10.5 mass with the volatile content of carbonaceous material Hereinafter, a method for producing metallic iron, wherein the amount of water attached is not more than 1.0 mass%.

  The invention according to claim 12 is the method for producing metallic iron according to claim 11, wherein the carbonaceous material-containing iron oxide agglomerated product has a content of the crystal water of 4% by mass or more.

The invention according to claim 13 is characterized in that the carbonaceous material-containing iron oxide agglomerated product has a basicity (CaO / SiO ₂ ) of 0.5 or more in terms of mass ratio. It is a manufacturing method.

According to the present invention, the total content of crystal water and the volatile content of the carbonaceous material , which is a gasification component in the agglomerated material, is limited to a predetermined value (10.5% by mass) or less, so that the iron oxide raw material Even when an agglomerate using high crystal water ore is charged into a rapid heating reduction furnace, the gas pressure generated inside the agglomerate is suppressed, and the occurrence of bursting can be reliably prevented. In addition, since there is no need to provide a pre-tropical zone in the reduction furnace, there is no need to increase the amount of binder such as organic binder without reducing the productivity of reduced iron and reducing the size of the reduction furnace. Therefore, the production cost of reduced iron or the like is not increased.

  Hereinafter, the present invention will be described in more detail.

The carbonaceous material-incorporated iron oxide agglomerate according to the present invention has a total content of crystal water and volatile matter of the carbonaceous material ( hereinafter simply referred to as volatile matter) in the carbonaceous material-incorporated iron oxide agglomerated product. 10.5% by mass (based on dry weight, the same shall apply hereinafter) or less, and the content of adhering moisture is 1.0% by mass or less.

Furthermore, the content of crystal water is preferably 4% by mass or more. Moreover, it is preferable that the basicity (CaO / SiO ₂ ) of the carbonaceous material-incorporated iron oxide agglomerated material is 0.5 to 1.5 in terms of mass ratio.

  Hereinafter, the reasons for limiting the numerical values of the requirements in the above configuration will be sequentially described.

(1) The total content of crystallization water and volatile matter in the agglomerated material is 10.5% by mass or less From the results of Test-4 in the examples described later (see FIG. 3), This is because the total content (mass basis) of crystal water and volatile matter in the chemical can be arranged, and the critical value is 10.5% by mass.

(A) Validity of being able to be evaluated by the total content of crystal water and volatile matter Here, as schematically shown in FIG. 1, the gas (water vapor) generation temperature range accompanying dissociation of crystal water is 200 to 400 ° C. Although the gas generation temperature range 300 to 700 ° C. accompanying devolatilization of volatile components partially overlaps, most of them do not overlap, so the presence or absence of bursting should be evaluated based on the total content of crystal water and volatile components. There may be doubts.

  However, the gas generation behavior as shown in FIG. 1 shows the gas generation behavior under conditions close to a steady state where the rate of temperature increase is small (usually 5 to 10 ° C./min). The range is clearly distinguished. On the other hand, when charged in a high temperature atmosphere of 1000 ° C. or higher, the temperature increase rate of the agglomerate becomes very large. And the gas generation temperature range accompanying the devolatilization of the volatile matter are both in the process of raising the agglomerate, and it is considered that the temperature ranges of both gas generations almost overlap.

  Therefore, it is considered that water vapor derived from water of crystallization and gas generated from volatile matter are generated almost at the same time after the agglomerate is charged into the rapid heating and reduction furnace. It is judged that it can be evaluated by the total content of and volatile matter.

(B) Appropriateness of being able to evaluate the total content of crystal water and volatile matter on a mass basis In addition, since the occurrence of bursting is due to the pressure increase accompanying the gas generation inside the agglomerate, the mass There may be doubts that it would be more reasonable to evaluate on the basis of gas volume (or mole) at the time of gasification rather than the total content on the basis.

Therefore, in order to confirm the validity of the evaluation based on the total content on the mass basis, respective molecular weights when the crystal water and the volatile component were gasified were compared. Naturally, the molecular weight of water vapor (H ₂ O) derived from crystal water is 18.0. On the other hand, the component composition of the generated gas derived from the volatile matter is considered to be different depending on the coal type, the rate of temperature rise, etc. First, considering the influence of the coal type, the content of the volatile content used in the examples described later For three different types of coals CA, HO, and YA, the average molecular weight of generated gas derived from volatile matter was estimated by the following method. That is, the component of the generated gas derived from the volatile matter is the ratio of CO and CO ₂ in the generated gas immediately after charging in a test in which carbonaceous iron-containing iron oxide pellets having a particle size of 16 mm were charged in an atmosphere of 1300 ° C. Was referred to as CO: CO ₂ = 71: 29 (volume ratio). C in the volatile matter is CO and CO ₂ , H is H ₂ O, N is NO ₂ , S is SO ₂ , and O is the CO, CO ₂ , H ₂ O, NO ₂ and SO _2. (As a gas component derived from volatile components immediately after devolatilization, by analogy from the component composition of coke oven gas, it should contain a lot of CH ₄ , H _2, etc. While moving from the inside of the agglomerate to the surface, iron oxide in the agglomerate is reduced, and when the gas itself is oxidized and released from the surface of the agglomerate, CH ₄ , H _2, etc. are CO, CO _2. It is considered that it is in the form of an oxide such as H ₂ O.) And the generation | occurrence | production ratio of each said gas component was computed from the analytical value of each coal, and the average molecular weight of the generated gas derived from the volatile matter of each coal was computed from this. Here, C in the volatile matter is T.I. C (elemental analysis C) and F.I. Differences from C (fixed carbon in industrial analysis) were used, and H, N, and S values in elemental analysis were used for H, N, and S, respectively. As a result of the estimation calculation, the composition of the generated gas derived from the volatile matter in each of the coals CA, HO, and YA is as shown in Table 1 below, and the average molecular weight of each generated gas is approximately 20 as shown in the table. The range was ± 0.5. Since the average molecular weight of these generated gases is assumed to change depending on the heating rate, the average molecular weight of water vapor derived from crystal water and the average molecular weight of generated gas derived from volatile matter are not much different, and the volume (mole) Even if the presence or absence of bursting is evaluated based on the total content of crystallization water and volatile matter based on the mass content without using the standard, it is determined that there is substantially no problem.
(C) Summary From the examination results of the above (a) and (b), the total content of crystal water and volatile matter in the agglomerated material is defined to be 10.5% by mass or less. The total content of crystal water and volatile matter in the agglomerated product is more preferably 9% by mass or less.

(2) Adhesive moisture content in the agglomerated material is 1.0% by mass or less The carbonaceous material-containing iron oxide agglomerated material according to the present invention is rapidly heated to 1000 ° C. or higher during the production of reduced iron or metallic iron. Is done. Therefore, in order to prevent bursting due to adhering moisture of the agglomerated material, the adhering moisture content in the agglomerated material is set to 1.0 mass% or less as in the invention described in the above cited reference 4. Preferably, it is 0.3 mass% or less. In addition, by restricting the moisture content in the agglomerate in this way, the crushing strength of the agglomerate is increased, preventing the agglomerate from being pulverized during the transportation process until it is charged into the reduction furnace. Effect is also obtained.

(3) The content of crystallization water in the agglomerated material was 4% by mass or more. The content of crystallization water in the agglomerated material was 4% by mass or more. Many high crystal water ores expected to be used have a crystal water content of about 5% by mass or more (for example, maramamba ore, lobe river ore, yandi ore). And since the compounding ratio of the ore and carbon | charcoal material in an agglomerate is about 80:20 normally, when a high crystal water ore is used as an iron oxide raw material, the content of crystal water in an agglomerate This is because it often becomes 4% by mass or more. Thereby, since a high crystal water ore can be used in a high ratio, the cost reduction effect is acquired.

(4) The basicity (CaO / SiO ₂ ) of the agglomerated material is 0.5 to 1.5 in mass ratio. When producing reduced iron using the agglomerated material as a raw material, the produced reduced iron is used as a blast furnace or electric When used as a raw material for a furnace or the like, the basicity (CaO / SiO ₂ ) of the agglomerate is set to facilitate the dissolution of reduced iron by promoting the slag formation of gangue and ash in the agglomerate. It is recommended to keep it high. The basicity (CaO / SiO ₂ ) of the agglomerated product is preferably 1.0 or more. However, if the basicity (CaO / SiO ₂ ) of the agglomerated material is excessively increased, the slag melting point rises, and on the contrary, the slag formation of gangue and ash in the reduced iron is inhibited, and the dissolution of the reduced iron is delayed. The basicity (CaO / SiO ₂ ) of the agglomerated product is desirably 1.5 or less. More preferably, it is 1.3 or less.

On the other hand, when producing high-grade granular metallic iron using the agglomerated material as a raw material, the basicity of the agglomerated material (CaO / SiO ₂₎ is improved in order to improve separation of the granular metallic iron and slag in the rapid heating reduction furnace. ) Is preferably 0.5 or more. More preferably, it is 1.2 or more. Moreover, 1.4 or less is preferable.

Therefore, the range of suitable basicity of agglomerates suitable to any production of reduced iron and granular metallic iron (CaO / SiO ₂₎ is 0.5 to 1.5.
[Production method of carbonized iron oxide agglomerates]
The carbonaceous material-containing iron oxide agglomerate according to the present invention is a raw material for producing reduced iron or metallic iron, and is charged into a rapid heating reduction furnace such as a rotary hearth type reduction furnace or a linear reduction furnace. And Here, the “rapid heating reduction furnace” means that the object to be heated is moved from a low temperature region of 200 ° C. or lower to a high temperature region of 1000 ° C. or higher in the furnace in a time of approximately 20 seconds or less. Refers to a heating reduction furnace that heats. The moving time of the object to be heated from the low temperature region to the high temperature region is preferably 12.5 seconds or less. As a rapid heating and reducing furnace, for example, a charging area (low temperature area) and a combustion heating area (high temperature area) in the furnace are separated by walls, and the charging material on the hearth is loaded by rotating the hearth. There is a rotary hearth type reduction furnace that can be moved from the entrance region to the combustion heating region in about 12.5 seconds. The rapid heating and reducing furnace may not have a pre-tropical zone for heating the charged raw material from room temperature to about 300 to 500 ° C. When the carbonaceous material-containing iron oxide agglomerate according to the present invention is heated in the rapid heating reduction furnace, as described above, the water vapor derived from crystal water and the gas derived from the volatile matter are almost from the carbonaceous material-containing iron oxide agglomerated product. It occurs at the same time.

[Production method of carbonized iron oxide agglomerates]
The carbonaceous material-incorporated iron oxide agglomerate having the above structure can be produced as follows.
For example, when only one type of high-crystal water ore of a specific brand is used as an iron oxide raw material, the total content of crystal water and volatile matter in the carbonaceous material agglomerated material is 10.5% by mass or less. Depending on the content of crystal water in the high-crystal water ore of the specific brand, one type of coal having an appropriate volatile content is selected.

  And the above-mentioned high crystal water ore whose particle size is adjusted so that the particle size of 1 mm or less is contained by 80% by mass or more is adjusted to the same particle size, and an amount sufficient to reduce iron oxide in the high crystal water ore. Add an appropriate amount of the above coal and starch as an organic binder, add water, granulate with a pelletizer to make green pellets, and dry it with a dryer until the amount of water attached is 1% by mass or less. By doing, the carbonaceous material interior iron oxide pellet (carbon material interior iron oxide agglomerate) which satisfies the structure of this invention can be manufactured. The amount of carbon material added is desirably 1.3 times or more (on a mass basis) the amount required to reduce iron oxide in the iron oxide-containing material.

In addition, in order to adjust the basicity (CaO / SiO ₂ ) of the carbonaceous material-incorporated iron oxide agglomerate, a predetermined amount of a calcium oxide supply substance (CaO supply substance) such as limestone or slaked lime may be added to the granulated raw material. .

Here, when a calcium oxide supply substance is added to the carbonized iron-incorporated iron oxide agglomerate, when the agglomerate is charged into the rapid heating reduction furnace, in addition to the generation of gas derived from the crystal water and volatile matter, oxidation Since the calcium supply substance is decomposed to generate CO ₂ gas or water vapor, there is a concern that bursting is more likely to occur.

  However, when limestone is used, as shown in FIG. 1, the gas generation temperature range accompanying decomposition is 670 to 1200 ° C., and the gas generation temperature range 200 to 400 ° C. accompanying dissociation of crystal water is completely different from Does not overlap. For this reason, even if both temperature ranges approach at a rapid temperature rise, the addition of limestone to the agglomerate has little effect on the increase in gas pressure inside the agglomerate, but rather agglomeration. Since the total content of crystallization water and volatile matter in the compound is diluted and lowered, the amount of gas generated from the crystallization water and volatile matter is reduced, and it works in the direction of suppressing the generation of bursting. 3).

  On the other hand, when slaked lime is used, although not shown in FIG. 1, the gas generation temperature range accompanying the decomposition is 100 to 580 ° C., which overlaps with the gas generation temperature range accompanying the decomposition of crystal water and volatile matter. Since the gas generation temperature range accompanying the decomposition of slaked lime is very wide, the influence on the gas generation rate inside the agglomerated material is small. Therefore, the addition of slaked lime to the agglomerated material has almost no effect on the increase in gas pressure inside the agglomerated material, as in the case of limestone, but rather the crystal water and volatiles in the agglomerated material. Therefore, the amount of generated gas derived from crystallization water and volatile matter is reduced and the generation of bursting is suppressed (see Test-3 in Examples below).

  Therefore, even if a calcium oxide supply substance is added to the agglomerated material, the binder may not be excessively increased as long as the total content of crystal water and volatile components is not more than a specified value (10.5% by mass). There is no need to worry about the occurrence of bursting.

(Modification)
Although the rotary hearth type reduction furnace is exemplified as the rapid heating reduction furnace using the agglomerated material as a raw material, it is naturally applicable to a linear furnace.

  As a method for producing the agglomerated material, a method for producing pellets has been exemplified, but, of course, a method for producing briquettes may be employed.

  Moreover, although the example which uses only one kind of high-crystal water ore of a specific brand as an iron oxide raw material was shown, you may mix and use the high-crystal ore of multiple brands (different crystallization water content) suitably. Furthermore, when using a high crystal water ore (for example, lobe river ore, yandi ore) with a very high crystal water content of 7% by mass or more, the crystal water content in the agglomerated product is 4% by mass or more. As long as it can be maintained, ordinary hematite ore, steel mill dust, or the like having a low crystallization water content or no crystallization water may be appropriately mixed and used.

  Moreover, although the example which selects and uses only 1 type of coal which has an appropriate volatile content as a carbon material was shown, several types of coal from which a volatile content differs is mixed, and volatile content is appropriate. You may adjust and use for the range. In addition to coal, coke, oil coke, charcoal, wood chips, waste plastic, old tires, and the like can also be used.

  In order to confirm the effect of the present invention, the following tests were performed using iron ore and coal shown in Table 2 below.

[Test-1] Effect of water of crystallization in agglomerates First, in order to investigate the effect of water of crystallization in agglomerates, two types of iron ore shown in Table 2 (a) above, with significantly different water contents of crystallization Using stones (Y ore and M ore), an agglomerate (pellet) was produced with a simple iron ore without blending carbonaceous materials, and a rapid heating test was performed (see Table 3 below).

  First, 0.5% by mass of wheat flour as a binder is added to Y ore containing 10.8% by mass of crystallization water, and an appropriate amount of water is added to granulate raw pellets having a diameter of 16 mm in a drier. Drying at 20 ° C. for 20 hours completely removed adhering water. Six of the dried pellets are arranged in a layer on a stainless steel mesh basket, and the stainless steel mesh basket is moved so as to reach the soaking zone heated to 1300 ° C in a vertical heating furnace from the furnace port in 20 seconds. I let you. The atmosphere in the heating furnace is 100% nitrogen gas. By this heating, all the pellets collapsed and separated into small chips (Test No. 1). The rapid heating condition simulates a case where the agglomerated material is moved from the charging region to the combustion heating region in about 12.5 seconds and heated in a rotary hearth type reduction furnace.

  On the other hand, except that M ore containing no crystal water was used and the binder was changed to 0.8% by mass of bentonite, the above test no. As a result of producing a pellet under the same conditions as in No. 1 and conducting a heating test, all the pellets remained healthy and did not collapse at all (Test No. 2).

  From the above results, it was confirmed that the crystal water of iron ore is greatly involved in the occurrence of bursting even without adhering water.

[Test-2] Effect of volatile content of agglomerate Next, in order to investigate the effect of volatile content in the agglomerate, two types of coal with significantly different volatile content in M ore containing no crystal water (CA charcoal and HO charcoal, see Table 2 (b)) were respectively prepared to produce a carbonaceous material-incorporated iron oxide agglomeration (pellet), and after removing adhering water completely, the same as test-1 above A rapid heating test was performed (see Table 4 below). The mixing ratio of iron ore and coal is based on the result of the heat reduction test of the iron oxide pellets in the carbonaceous material carried out in the past, and the mixing ratio is such that the iron oxide in the iron ore is sufficiently reduced by coal. In order to adjust the degree, slaked lime was added as a calcium oxide supply substance.

  When HO charcoal with a small amount of volatile matter was used, cracks (cracks) were observed on the pellet surface, but there was almost no grain reduction (micronization).

  On the other hand, when CA charcoal with a high volatile content was used, the upper part of the pellet collapsed and scattered. This is considered to be because the gas pressure in the pellet was increased by the amount of the volatile component, and a part was separated.

[Test-3] Effect of addition of calcium oxide supply substance to agglomerate Next, in order to investigate the influence of calcium oxide supply substance added to agglomerate, carbonaceous material is added to Y ore with a lot of crystal water. Without adding slaked lime and limestone respectively, the agglomerated material (pellet) was prepared for the case of no addition, and the following rapid heating test was carried out after completely removing adhering water (Table 5 below) Test No. 5-7 reference).

In this test-3, the rapid heating test method is different from the method in which the stainless steel wire cage used in the above tests-1 and 2 is charged into the vertical heating furnace, and the heating state is closer to that of the actual rotary hearth type reducing furnace. In order to simulate this, four dried pellets were placed on a lightweight alumina tray and loaded into the 1300 ° C soaking zone in a horizontal heating furnace replaced with an N ₂ atmosphere in 20 seconds from the furnace port. Then, it was held at that position, heated for a time when the reduction rate of the pellet was 90% or more, then moved to the cooling zone of the horizontal heating furnace and cooled to room temperature in an N ₂ atmosphere.
Furthermore, in order to investigate the influence of the addition of calcium oxide supply substances to the agglomerates when blending carbonaceous materials, various blending ratios of Y ore with a lot of crystal water and YA charcoal with a medium volatile content were changed. After adding limestone to produce an agglomerated product (pellet) and completely removing adhering water, a rapid heating test similar to Tests 1 and 2 was performed (Test No. 8 in Table 5 below). -10).

  Test No. From 5 to 7, it can be seen that when limestone or slaked lime is added as a calcium oxide supply substance, the occurrence of bursting tends to be suppressed as compared with the case of simple iron ore. In addition, Test No. From 8 to 10, it can be seen that regarding the bursting resistance of the agglomerated material, the influence of crystallization in the iron ore and the volatile matter in the coal is large, and the influence due to the addition of the calcium oxide supply substance is small.

[Test-4] Investigation of anti-bursting properties of agglomerates using various iron ores and various coals Next, iron ores with different crystallization water contents and coals with different volatile contents under various compounding conditions Based on the following conditions (A) and (B) in addition to the agglomerated materials subjected to the rapid heating test in the above tests 1 to 3 in order to investigate the bursting resistance properties of the produced agglomerated materials (pellets). The proportion of small particles was measured as described below with respect to the agglomerates prepared and subjected to the rapid heating test.
Condition (A): Test No. in Table 6 below using M ore and HO charcoal. Agglomerates were prepared under the blending conditions of 11-14. And like the said test-1, after removing adhering water completely with a dryer, the rapid heating test was implemented with the vertical heating furnace (refer test No.11-14 of Table 6).
Condition (B): Test No. in Table 6 below using Y ore and CA charcoal. An agglomerated product was prepared under 15 blending conditions. And like the said test-1, after removing adhering water completely with a dryer, the rapid heating test was implemented with the horizontal heating furnace similarly to the said test-3 (refer test No. 15 of Table 6).

  FIG. 2 shows an example in which the state of the pellets tested by this rapid heating test method before and after heating is observed from above. Although this pellet is cracked after heating but does not generate separated pieces, it is regarded as a pellet having good bursting resistance.

  In order to quantitatively evaluate the resistance to bursting, the pellets are taken out after cooling, and small particles of 3.35 mm or less (also expressed as “−3.35 mm”) are separated by a sieve, and the mass of the small particles is The evaluation was based on the proportion of the whole pellet, and when the proportion of small particles of 3.35 mm or less was 5% or less, the bursting resistance was defined as good (the same applies to tests 1 to 3). To evaluate the anti-bursting properties.) This evaluation method was formulated based on the fact that even if the pellets are cracked, if the metallic iron is sintered and not separated into small pieces, it can be put into practical use as a product (reduced iron or metallic iron). It is.

  In addition, the reason for adopting the method of rapidly charging the soaking zone at 1300 ° C. is that the carbonaceous material-containing iron oxide agglomerates are heated to a high temperature in as short a time as possible in order to produce reduced iron most efficiently. Therefore, in evaluating the bursting resistance, 1300 ° C. corresponding to a sufficiently high furnace atmosphere temperature in the case of producing reduced iron in a rotary hearth type reducing furnace was selected.

  The results of the test-4 are shown in the following Table 6 and FIG. 3 together with the results of the tests-1-3. As shown in the figure, even when heated rapidly in a vertical heating furnace using the stainless steel mesh cages of Tests 1-3, and when heated rapidly in a horizontal heating furnace using the alumina tray of Test-4 However, it can be seen that the same tendency is shown within the range of variation.

  As apparent from Table 6 and FIG. 3, when the total content of water of crystallization (LOI) and volatile matter (VM) in the agglomerate exceeds 10.5% by mass, the proportion of small particles of 3.35 mm or less Increases rapidly to 40 to 63% (see Test Nos. 9, 10, and 15), whereas the total content of crystal water (LOI) and volatile matter (VM) in the agglomerate is 10. In the case of 5% by mass or less, the proportion of small particles of 3.35 mm or less (−3.35 mm) is always less than 5%, which indicates that the resistance to bursting is very excellent (Test No. 3, 4, see 11-14).

  Moreover, from Table 6, in order to ensure the bursting resistance, the total content of crystal water (LOI) and volatile matter (VM) in the agglomerated material is set to 10.5% by mass or less. It can be seen that 0.8 mass% is sufficient for the addition amount of wheat flour (starch) as an agent, and it is not necessary to increase the binder excessively (see Test Nos. 11 to 14).

The relationship between heating temperature and gas generation rate is schematically shown to explain the gas generation behavior associated with each decomposition reaction of iron ore crystallization water, coal volatile matter, and limestone in the agglomerates of carbonaceous materials. FIG. It is a figure which shows the mode of the carbonaceous material interior iron oxide pellet before and behind a rapid heating test. It is a graph which shows the relationship between the total content of the crystal water and volatile matter in a carbonaceous material interior iron oxide agglomerate, and the ratio of the small particle of 3.35 mm or less after a rapid heating test.

Claims (13)

A carbonaceous material-containing iron oxide agglomerate used as a raw material for a rapid heating and reduction furnace,
The total content of crystal water and the volatile content of the carbonaceous material in the carbonaceous material- incorporated iron oxide agglomerate is 10.5% by mass (dry basis, the same shall apply hereinafter) or less, and the content of adhered water is 1. Carbonaceous iron-incorporated iron oxide agglomerates characterized by being 0% by mass or less.   The carbonaceous material-incorporated iron oxide agglomerated product according to claim 1, wherein a content of the crystal water in the carbonized material-incorporated iron oxide agglomerated material is 4% by mass or more. The basicity (CaO / SiO ₂ ) of the carbonaceous material-incorporated iron oxide agglomerated product is 0.5 to 1.5 in mass ratio, and the carbonaceous material-incorporated iron oxide agglomerated product according to claim 1 or 2. A method for producing a carbonaceous material-containing iron oxide agglomerate used as a raw material for a rapid heating reduction furnace,
In the carbonaceous material-incorporated iron oxide agglomerate, a step of blending the iron oxide raw material and the carbonaceous material so that the total content of crystal water and the volatile content of the carbonaceous material is 10.5% by mass or less;
Granulating the iron oxide raw material and the carbonaceous material into agglomerates;
Drying the agglomerated product until the content of adhering moisture in the agglomerated product is 1.0% by mass or less, and producing the carbonized iron oxide agglomerated product. In the step of blending the iron oxide raw material and the carbonaceous material,
The carbonaceous material-incorporated iron oxide ingot according to claim 4, wherein the iron oxide raw material and the carbonaceous material are blended so that the content of the crystal water in the carbonized material-incorporated iron oxide agglomerate is 4% by mass or more. A method for producing chemical compounds. In the step of blending the iron oxide raw material and the carbonaceous material,
Wherein As carbonaceous material furnished oxidation TetsukatamariNaru products of basicity (CaO / SiO ₂₎ is 0.5 to 1.5 in mass ratio, claim 4 formulating the iron oxide raw material and the carbonaceous material or 5. A method for producing an agglomerated iron oxide agglomerated material according to item 5. In the step of blending the iron oxide raw material and the carbonaceous material,
Furthermore, the manufacturing method of the carbonaceous material interior iron oxide agglomerated material in any one of Claims 4-6 which mix | blend a calcium oxide supply substance. A method for producing reduced iron, comprising:
Charging the carbonized iron oxide agglomerate into a rapid heating reduction furnace;
By moving the carbonaceous material-containing iron oxide agglomerated material from the region where the furnace temperature of the rapid heating reduction furnace is 200 ° C. or lower to the region where the temperature is 1000 ° C. or higher in 20 seconds or less, Heating the agglomerates;
Reducing the iron oxide of the carbonaceous material-incorporated iron oxide agglomerate to reduced iron with a carbonaceous reducing agent in the carbonaceous material-incorporated iron oxide agglomerate;
Cooling and solidifying the reduced iron,
The carbonaceous material-incorporated iron oxide agglomerated product has a total content of crystal water and a volatile content of the carbonaceous material in the carbonized material-incorporated iron oxide agglomerated material of 10.5% by mass or less, and a content of adhering moisture is 1. The manufacturing method of reduced iron characterized by being 0.0 mass% or less.   9. The method for producing reduced iron according to claim 8, wherein the carbonaceous material-containing iron oxide agglomerated product has a content of the crystal water of 4% by mass or more. The method for producing reduced iron according to claim 8 or 9, wherein the carbonaceous material-incorporated iron oxide agglomerated product has a basicity (CaO / SiO ₂ ) of 1.5 or less in terms of mass ratio. A method of producing metallic iron,
Charging the carbonized iron oxide agglomerate into a rapid heating reduction furnace;
By moving the carbonaceous material-containing iron oxide agglomerated material from the region where the furnace temperature of the rapid heating reduction furnace is 200 ° C. or lower to the region where the temperature is 1000 ° C. or higher in 20 seconds or less, Heating the agglomerates;
Reducing iron oxide of the carbonaceous material-incorporated iron oxide agglomerate with a carbonaceous reducing agent in the carbonaceous material-incorporated iron oxide agglomerate, thereby generating metallic iron and by-producing slag;
Aggregating the metallic iron into particles while separating from the slag;
Cooling and solidifying the metallic iron,
The carbonaceous material-incorporated iron oxide agglomerated product has a total content of crystal water and a volatile content of the carbonaceous material in the carbonized material-incorporated iron oxide agglomerated material of 10.5% by mass or less, and a content of adhering moisture is 1. The manufacturing method of metallic iron characterized by being 0.0 mass% or less.   12. The method for producing metallic iron according to claim 11, wherein the carbonaceous material-containing iron oxide agglomerated product has a content of the crystal water of 4% by mass or more. The method for producing metallic iron according to claim 11 or 12, wherein the carbonaceous material-containing iron oxide agglomerated product has a basicity (CaO / SiO ₂ ) of 0.5 or more in terms of mass ratio.

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