JP6996268B2 - Charcoal interior ore and its manufacturing method - Google Patents

Description

The present invention relates to a carbonaceous interior ore used as a raw material for iron making in a blast furnace and the like, and a method for producing the same.

In recent years, in order to reduce the ratio of reducing agent in blast furnace operation, it has been proposed to use a carbonaceous material interior ore obtained by mixing and molding an iron oxide-containing raw material and a carbonaceous material.

The charcoal interior ore is superior in reducing property to the sintered ore and pellets. Is required to be low.

For example, in Patent Document 1, an iron-containing raw material containing high water of crystallization ore, a powdered carbonaceous material, and a water-hard binder such as cement are mixed and molded to control the pore ratio to 20 to 30%. A method for producing a coal-containing agglomerate ore having excellent reduced pulverization property is disclosed.

Further, Patent Document 2 describes a method for producing a carbonaceous material interior ore having excellent reducible pulverization property by defining the amount of hematite contained in the iron oxide-containing raw material and the amounts of C and H in the organic binder. It has been disclosed.

Further, Patent Document 3 discloses that a twin-roll type briquette machine is used in a molding step in a method for reducing electric furnace dust, and the molding linear pressure thereof is set to 44 kN / cm or more.

International Publication No. 2011/021560 Japanese Unexamined Patent Publication No. 2016-108580 Japanese Unexamined Patent Publication No. 2009-52141

As described above, Patent Documents 1 and 2 provide a method for producing a carbonaceous material interior ore having excellent reducing pulverization property. However, in blast furnace operation, there is a demand for a carbonaceous material interior ore having higher strength and excellent reduction pulverization property.

The powder mass product described in Patent Document 3 is not intended to be used in a blast furnace.

Therefore, an object of the present invention is to provide a carbonaceous wood interior ore and a method for producing the same, which can be suitably used as a raw material for iron making even in a blast furnace because of its high strength and excellent reducing pulverization property.

In order to solve the above-mentioned problems, the present inventors have conducted a diligent study on the carbonaceous interior ore, and found that even when an iron oxide-containing raw material having a high hematite content is used, the line when forming the carbonaceous interior ore is formed. We have found that by controlling the pressure, it is possible to effectively produce a carbonaceous material interior ore having high strength and excellent reducing pulverization property, and completed the present invention.

That is, in the method for producing a carbonaceous interior ore according to one aspect of the present invention, an iron oxide-containing raw material having a hematite content of 75% by mass or more, a carbonaceous material, and a binder are kneaded to obtain a kneaded product. It includes roll compression at a linear pressure of 0.4 kN / mm or more and 2.0 kN / mm or less.

In the method for producing an iron oxide interior ore according to one aspect of the present invention, the ratio of the iron oxide content raw material in the carbonaceous material interior is preferably 70% by mass or more and 95% by mass or less.

Further, in the method for producing a carbonaceous material interior ore according to one aspect of the present invention, at least one of pulp waste liquid and molasses as a binder is 1% by mass or more with respect to a total of 100% by mass of the iron oxide-containing raw material and the carbonaceous material. It is preferable to use 10% by mass or less.

Further, the present invention provides a carbonaceous material interior ore having high strength and excellent reducing pulverization property.

The carbonaceous material interior ore according to one aspect of the present invention contains an iron oxide-containing raw material having a hematite content of 75% by mass or more, a carbonaceous material, and a binder, and has a reduced pulverization index of 40% or less.

In the carbonaceous material interior ore according to one aspect of the present invention, the crushing strength is preferably 1.0 kN or more.

According to one aspect of the present invention, it is intended to provide a charcoal interior ore which is a carbonaceous interior ore having high strength and excellent reducing pulverizability and which can be suitably used as a raw material for iron making for a blast furnace. Can be done.

It is a figure which shows the relationship between the reduced pulverization index (RDI) of the dry lump, and the linear pressure of each of Test Example 1 and Test Example 2. FIG. It is a figure which shows the relationship between the reduction rate and the linear pressure at the time of RDI test of the mass after drying in Test Example 1. FIG. It is a figure which shows the relationship between the crushing strength and the linear pressure in Test Example 1.

In the method for producing a carbonaceous material interior ore according to the present embodiment (hereinafter referred to as "the present production method"), an iron oxide-containing raw material having a hematite content of 75% by mass or more, a carbonaceous material, and a binder are used. It includes kneading and rolling compression molding the obtained kneaded product at a linear pressure of 0.4 kN / mm or more and 2.0 kN / mm or less. First, the raw materials used in this production method will be described.

[Charcoal interior ore]
In the present specification, the carbonaceous material interior ore means an iron-making raw material used in a blast furnace, and more specifically, a lumpy product obtained by densely mixing an iron oxide-containing coal material and a charcoal material, which will be described later.

(Iron oxide-containing raw material)
The iron oxide-containing raw material used in this production method is a raw material containing at least hematite (Fe ₂ O ₃ ) as iron oxide.

Hematite contained in the iron oxide-containing raw material is a well-known compound. The content of hematite in the iron oxide-containing raw material may be 75% by mass or more. In addition to hematite, the iron oxide-containing raw material may contain one or more of iron (II) oxide, calcium oxide, silicon dioxide, aluminum oxide and the like.

Examples of the shape of the iron oxide-containing raw material include powder and particles having a particle size of 0 to 10 mm.

(Charcoal material)
In the present specification, the carbonaceous material means a raw material containing a carbon source. Examples of the coal material include coke breeze, steam coal, anthracite, coke dust, and primary ash from a blast furnace, which is a type of dust generated in the iron making process.

Examples of the shape of the carbonaceous material include powder and particulate matter having a particle size of 0 to 10 mm.

(binder)
The binder used in this production method may be any binder as long as it has a function as a binder for binding the iron oxide-containing raw material and the carbonaceous material. Examples of such a binder include organic binders and inorganic binders.

As the organic binder, for example, one kind or two or more kinds selected from the group consisting of pulp waste liquid (for example, lignin sulfite etc.), molasses, starch and the like, and carboxymethyl cellulose may be used as appropriate. can.

Further, if necessary, an inorganic binder such as quicklime and bentonite may be added to the organic binder as long as the amount of slag in the carbonaceous material interior ore does not adversely affect the blast furnace operation.

In this production method, it is preferable to use at least one of pulp waste liquid and molasses as a binder. When the binder is a mixture of pulp waste liquid and molasses, the mixing ratio is 1 to 10, preferably 2 to 4 in terms of weight ratio (pulp waste liquid / molasses).

(This manufacturing method)
Next, a specific process of this manufacturing method will be described.

In this production method, the above-mentioned iron oxide-containing raw material, carbonaceous material, and binder are kneaded, and the obtained kneaded product is roll-compressed at a linear pressure of 0.4 kN / mm or more and 2.0 kN / mm or less. including.

In this production method, the amount of the charcoal material added is not particularly limited, but may be 5% by mass or more and 30% by mass or less with respect to the total 100% by mass of the iron oxide-containing raw material and the charcoal material. preferable.

In the present production method, the ratio of the iron oxide-containing raw material in the coal lumber interior ore is preferably 70% by mass or more and 95% by mass.

The amount of the binder added is not particularly limited, but it is preferable to add 1% by mass or more and 10% by mass or less with respect to 100% by mass of the total of the iron oxide-containing raw material and the carbonaceous material.

The iron oxide-containing raw material, the carbonaceous material, and the binder may be kneaded, for example, by appropriately adding water or the like to the mixture containing the iron oxide-containing raw material, the carbonaceous material, and the binder.

The obtained kneaded product is molded by roll compression at a linear pressure of 0.4 kN / mm or more and 2.0 kN / mm or less to obtain a lump.

As used herein, roll compression means compressing a sample between a pair of rotating rolls. Further, the linear pressure means a load applied per unit length in the width direction of the roll.

For roll compression of the kneaded product, a known device such as a roll type briquette machine (there is no other roll compression) may be used. The roll type briquette machine is a kind of granulation machine, and a plurality of pockets are provided on the surface of a pair of rotating rolls. Then, by adjusting the pocket, it is possible to obtain a mass having a desired shape such as a pillow shape, an almond shape, or a spherical shape.

In this production method, finally, the lump is dried to obtain a carbonaceous interior ore. The method for drying the lump is not particularly limited, and examples thereof include heat drying and natural drying.

When the lump is heated and dried, the heating temperature is not particularly limited, but is preferably 100 ° C. or lower. The heating time at this time is not particularly limited, but is preferably 2 hours or more.

The carbonaceous interior ore obtained by this production method contains an iron oxide-containing raw material having a hematite content of 75% by mass or more, a carbonaceous material, and a binder, and the reduced pulverization index of this carbonaceous material interior ore is 40% or less. Is. Further, the crushing strength of the carbonaceous material interior ore obtained by this production method is preferably 1.0 kN or more, and more preferably 1.5 kN or more.

In this embodiment, the crushing strength is measured based on JIS M8718. In addition, the reduction powder test shall be conducted based on JIS M8720.

As described above, the carbonaceous material interior ore according to the present embodiment has high strength and is also excellent in reducing pulverization property. Therefore, the carbonaceous material interior ore according to the present embodiment is difficult to be pulverized even in a temperature range in which blast furnace is likely to be pulverized at 500 to 600 ° C., and can be suitably used as a raw material for steelmaking.

In order to confirm the effect of the present invention, the following tests were carried out.

[Examination test]
An iron source containing the components shown in Table 1, a powdery coke for sintering as a carbonaceous material, and a binder containing the components (unit: mass%) shown in Table 2 were used as raw materials. At that time, the raw material composition was set to the ratio shown in Table 3. Then, the raw materials were kneaded while adding water to obtain a kneaded product. The obtained kneaded product was rolled and compressed with a briquette machine to form a lump. Further, the obtained lump was dried at 105 ° C. for 2 hours or more to obtain a dried lump, which was used as a test sample.

(Device)
Bricket machine: Shinto Kogyo Co., Ltd., model number: BGS-1V
Roll pocket size: 28mm x 26mm x 6.5mm
Roll speed: 5 rpm
Roll gap: 0.7mm
Screw speed: 25-90 rpm
[Compressive strength measurement]
The compressive strength measurement was performed based on JIS M 8718.

[Reduced powderability test]
The reduced pulverization property test was carried out based on JIS M 8720.

The results are shown in FIGS. 1 to 3. FIG. 1 shows the relationship between the reduced pulverization index (RDI) of the dried mass of each of Test Example 1 and Test Example 2 and the linear pressure. FIG. 2 shows the relationship between the reduction rate and the linear pressure of the dried mass in Test Example 1 during the RDI test. FIG. 3 shows the relationship between the crushing strength and the linear pressure in Test Example 1.

As shown in FIG. 1, when steel mill dust having a low hematite content was used as the iron source, the RDI was very small at 20% or less regardless of the linear pressure, and the influence of the linear pressure on the RDI was small. ..

This is considered to be due to the volume expansion that occurs during the reduction of hematite to magnetite. That is, it is considered that the amount of hematite contained in the steelworks dust was as low as about 40% by mass, and the amount of reduction from hematite to magnetite, which causes reduction powdering, was small, so that the RDI was very low regardless of the linear pressure. ..

On the other hand, when South American iron ore having a relatively high hematite content was used as the iron source, the lower the linear pressure during roll compression, the worse the RDI. When the linear pressure was less than 0.4 kN / mm, the RDI exceeded 45%. From this result, if the linear pressure is less than 0.4 kN / mm, the air permeability in the blast furnace may be deteriorated when the obtained agglomerates after drying are used as a raw material for iron making for a blast furnace.

Further, when iron ore produced in South America was used as the iron source, as shown in FIG. 2, the reduction rate at the time of the RDI test decreased as the linear pressure decreased. The amount of reduction from hematite to magnetite increases as the linear pressure decreases. In other words, when iron ore produced in South America is used as the iron source, it is considered that the reason why the RDI deteriorated as the linear pressure decreased was that the amount of reduction from hematite to magnetite increased.

From the above results, it can be said that even when a hematite content with a high content is used as an iron source, a carbonaceous material interior ore with good reducing powderability can be produced by setting the linear pressure to 0.4 kN / mm or more. ..

Further, when iron ore produced in South America was used as the iron source, as shown in FIG. 3, the crushing strength tended to decrease gradually as the linear pressure increased. Further, when the linear pressure exceeded 2 kN / mm, many cracks and defects were observed at the ends of the lumpy material. Therefore, from the viewpoint of crushing strength, it can be said that it is desirable to set the linear pressure to 2.0 kN / mm or less when producing the carbonaceous material interior ore.

[Examples 1 to 5]
According to the composition of the components shown in Table 4, a dried lump was obtained by the same procedure as in the above-mentioned test example. Then, the linear pressure, the crushing strength and the RDI of the obtained dried lumps were measured by the same procedure as in the above-mentioned test example. These results are shown in Table 4.

[Comparative Examples 1 to 5]
According to the composition of the components shown in Table 4, a dried lump was obtained by the same procedure as in the above-mentioned test example. Then, the linear pressure, the crushing strength and the RDI of the obtained dried lumps were measured by the same procedure as in the above-mentioned test example. These results are shown in Table 4.

From the results shown in Table 4, when the linear pressure at the time of roll compression is in the range of 0.4 kN / mm or more and 2.0 kN / mm or less, the crushing strength of the test sample is high and the RDI of the sample is high. Was less than 40%, and both crushing strength and reduced pulverizability were good.

On the other hand, in Comparative Examples 1 and 2 in which the linear pressure was less than 0.4 kN / mm, the crushing strength was as good as 1 kN / mm or more, but the RDI was much higher than 40%, and the powder was reduced. The sex was inferior. Further, in Comparative Example 3 in which the linear pressure was 1.8 kN / mm or more, the RDI was good at less than 40%, but the crushing strength was as low as less than 1 kN, and many defects were observed in the test sample.

Claims (4)

A raw material containing iron oxide having a hematite content of 75% by mass or more, a carbonaceous material, and a binder are kneaded, and the obtained kneaded product is kneaded at a linear pressure of 0.4 kN / mm or more and 2.0 kN / mm or less. A method for producing a carbonaceous material interior ore, including roll compression. The mass ratio of the iron oxide-containing raw material in the carbonaceous material interior ore is 70 or more and 95 or less when the total mass of the iron oxide-containing raw material and the carbonaceous material in the carbonaceous material interior ore is 100. , The method for producing a carbonaceous material interior ore according to claim 1. As the binder, at least one of pulp waste liquid and molasses is added by a mass of 1 or more and 10 or less when the total mass of the iron oxide-containing raw material and the charcoal material in the coal material inner ore is 100. The method for producing a carbonaceous material interior ore according to claim 1 or 2. It contains an iron oxide-containing raw material having a hematite content of 75% by mass or more, a carbonaceous material, and a binder, and has a reduced pulverization index of 40% or less .
A charcoal interior ore with a crushing strength of 1.0 kN or more .

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