JP2002241853A - Non-burning agglomerate for blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drastically improve a carbon content at higher level than that in the conventional material while avoiding the lowering of strength caused by the carbon inclusion in a non-burning agglomerate for blast furnace. SOLUTION: In the non-burning agglomerate 1 for blast furnace, grains of sintered ore having >5 mm diameter or lump ore are made to nucleus grains 2 and the outer peripheral layer 3 enveloping the nucleus grain 2 is composed of iron-containing dust and/or iron ore having <=0.25 mm diameter, and a carbonaceous material having <=0.25 mm diameter and a binding structure. Further, the ratio of the carbonaceous material in the outer peripheral layer 3 is made to 10-50 mass%, and the ratio of the thickness of the outer peripheral layer 3 to the radius of the nucleus grain 2 is made to <=30%. A coke can be used for the nucleus grain 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a raw material for iron making, and more particularly to an unfired agglomerate for a blast furnace having high reducibility and sufficient strength.

[0002]

2. Description of the Related Art As agglomerates for using fine iron ore and iron-containing dust as raw materials for blast furnaces, calcined agglomerates and non-calcined agglomerates are currently used. Among these, uncalcined agglomerates are mainly spherical agglomerates obtained by solidifying fine or pulverized iron ore or iron-containing dust with a binder. Portland cement, blast furnace slag powder, bentonite, molasses Various types are used depending on the application. The manufacturing process generally includes crushing and mixing of raw materials, granulation and molding by a dish-shaped granulator or a briquette machine, and curing by a yard.
Conventionally, iron sand is often used as a core of granulation in order to smoothly perform granulation, and the produced agglomerate ore has a core of iron iron having a size of about 1 mm as shown in FIG. 5 has a large number of structures in the agglomerate ore 4.

Japanese Unexamined Patent Application Publication No. 9-170033 discloses a method for improving the efficiency of reduction at the center where the reduction is most delayed, as shown in FIG. The non-calcined agglomerate for ironmaking 6 is characterized in that the ore is core particles 7 and the outer peripheral layer 8 surrounding the core particles 7 is a granulated product composed of a mixture of an iron raw material, a carbon material, and a binder. Has been described.

[0004]

In the case of uncalcined agglomerate, a carbonizing agent can be contained in the agglomerate for the purpose of accelerating the reduction reaction, which is called carbonization. Although a larger amount of the carbonizing agent is preferable for reduction, there is a disadvantage that the strength is reduced. If the rotary hearth is used as a reducing furnace, as in the case of the INMETCO method or the Fast Met method, the strength of the carbonized agglomerate ore is not a problem.
Carbonized carbonaceous ore containing up to about 30% is used. However, when used as a raw material for blast furnaces, strength is an important constraint, so the carbonized content of carbonized agglomerate is limited to about 10%. Have been.

The uncalcined agglomerate for iron making described in Japanese Patent Application Laid-Open No. 9-170033 improves the reduction efficiency by improving the permeability of the reducing gas in the center of the uncalcined agglomerate. It is not enough as a measure to prevent a decrease in strength when the carbon content increases.

An object of the present invention is to provide an uncalcined agglomerate for a blast furnace capable of avoiding a decrease in strength due to carbonization and capable of significantly increasing the carbon content as compared with the prior art. Improve blast furnace productivity and fuel ratio by using ore.

[0007]

The unfired agglomerate for a blast furnace according to the present invention has the following features. (1) Particles of sintered ore or lump ore having a diameter of more than 5 mm are used as core particles, and the outer layer containing the core particles has a diameter of Iron-containing dust and / or iron ore up to 0.25 mm,
And a carbonaceous material having a diameter of 0.25 mm or less, and a connective tissue, wherein the ratio of the carbonaceous material in the outer peripheral layer is 10 to 50% by mass, and the ratio of the thickness of the outer peripheral layer to the radius of the core particle is 30.
% Or less, and (2) iron-containing dust having a coke core particle and an outer layer containing the core particle having a diameter of 0.25 mm or less and / or
And iron ore, a carbonaceous material having a diameter of 0.25 mm or less, and a connective structure, wherein the ratio of the carbonaceous material in the outer peripheral layer is 10 to 50% by mass, and the ratio of the thickness of the outer peripheral layer to the radius of the core particle is 30% or less. A non-fired agglomerate for a blast furnace, characterized in that:

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is to avoid a decrease in the strength of uncalcined agglomerate due to an increase in carbonizing agent by providing core particles for ensuring the strength. That is, as shown in FIG. 1, the agglomerate ore 1 of the present invention has a structure including a core particle 2 at the center and an outer peripheral layer 3 containing the core particle 2, and the core particles 2 at the center ensure the strength. Therefore, as the core particles 2, particles of sintered ore or lump ore having a diameter of more than 5 mm are used. If the diameter is 5 mm or less, sufficient strength cannot be secured.

The iron-containing dust in the outer peripheral layer 3 is dust containing iron enough to be recycled as a raw material for iron making, and means blast furnace secondary dust, sintered dust, converter dust, and the like. In addition, the carbonizing agent means solid substances such as coal, coke, and dust having a high carbon content generated in the coke manufacturing process. Connective tissue is Portland cement,
A portion derived from a binder such as blast furnace slag, bentonite, molasses and the like, and is a portion for fixing the core particles 2 and the powder of the outer peripheral layer 3.

The reason that the particle diameter of the iron-containing dust, iron ore, and carbonaceous material in the outer peripheral layer is specified to be 0.25 mm or less is that if the particle diameter exceeds this, the smooth forming operation in the dish granulator is hindered. At the same time, the strength of the agglomerate decreases.
In addition, the ratio of the carbonaceous material in the outer peripheral layer 3 is 10 to 50% by mass.
The reason for the definition is that if the content is less than 10% by mass, it is possible to contain the same without a decrease in strength, and if the content exceeds 50% by mass, a decrease in strength cannot be avoided even if the core particles 2 are present. The reason why the thickness of the outer peripheral layer 3 is specified to be 30% or less with respect to the radius of the core particles 2 is that if the thickness exceeds 30%, the outer peripheral layer 3 becomes too thick with respect to the core particles 2 and causes a decrease in strength. It is.

Also, coke particles can be used as the core particles 2. The coke particles have sufficiently high strength as compared with the outer peripheral layer 3, similarly to the particles of the sintered ore and the lump ore. Therefore, the coke particles can also contribute to the improvement of the strength of the agglomerate ore similarly to the particles of the sintered ore and the lump ore.

FIG. 2 shows an example of the production process of the agglomerate ore of the present invention. The raw material 11 for the core particles is supplied to the granulator 17 after being preliminarily hydrated so that the raw material for the outer peripheral layer easily adheres to the surface thereof. On the other hand, the carbonaceous material 12, the iron-containing dust or / or iron ore 13, and the powdery binder 14 such as Portland cement, which are raw materials for the outer layer, are supplied to the granulator 17 in a separate system,
Granulate while adding water. As a result, a granulated product having a structure in which the raw material of the outer peripheral layer 3 is attached around the core particles 2 shown in FIG. 1 is obtained. After the granulation, the granules are cured in the yard 18, where the strength of the granules is developed by the hardening action of the binder, and then used as blast furnace agglomerate. At this time, it is preferable that the raw materials for the outer peripheral layer 12 to 14 are mixed in advance by the mixer 15 and then supplied to the granulator 17 in that a homogeneous granulated product is obtained. A liquid binder 16 such as molasses
Is used, it is supplied directly into the granulator 17 instead of water.

[0013]

[Example] Converter dust as iron-containing dust as carbonaceous material
Table 1 shows an example in which DQ powder was added and solidified with Portland cement to obtain a carbon-containing pellet having a diameter of 13 to 17 mm.

The converter dust is obtained by dewatering a thickener sludge obtained by wet-collecting dust in the converter exhaust gas with a filter press and then drying it in the sun in a yard. 0.25
The particle size is not more than mm. Also, CDQ powder is
Dust collected from the circulating gas when the red hot coke after the carbonization was cooled by the CDQ facility, and its particle size was approximately 0.1 mm or less.

In the comparative examples and examples, sintered ore was used for the core particles, and the diameters were set to three types of 10 mm, 12 mm, and 14 mm in order to see the influence of the relative ratio between the core particles and the outer peripheral layer. At this time, the ratio of the thickness of the outer peripheral layer to the radius of the core particles was 40%, 30%, and 20%.

For the granulation, a dish-shaped granulator having a diameter of 1 m was used. In the production of the coal-containing pellets of the conventional example, a predetermined amount of CDQ powder, converter dust and Portland cement are mixed in advance, and then supplied to a granulator to form pellets having a diameter of 13 to 17 mm while adding water. For 2 weeks. In Comparative Examples and Examples, the sinter ore serving as the core particles was immersed in water in advance and sufficiently watered was supplied to a granulator, and while being sprinkled therewith, CDQ powder previously mixed in a predetermined ratio, a converter A mixture of dust and Portland cement was fed and granulated and similarly cured in a yard for two weeks. In each case,
The strength was measured using an autograph, and 30
The average value was determined and evaluated.

In Conventional Examples 1 to 3, the crushing strength was reduced due to an increase in the amount of CDQ powder, and in particular, when the content exceeded 20%, the strength was significantly reduced. On the other hand, in Examples 1 and 2, even at a carbon content of 20%, strength equal to or higher than that of Conventional Example 2 was secured.
In a comparative example in which the thickness of the outer peripheral layer is excessively larger than 30%,
A decrease in strength was observed.

[0018]

[Table 1]

[0019]

According to the present invention, the productivity and fuel ratio of the blast furnace iron making method can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing the structure of the agglomerate ore of the present invention.

FIG. 2 is a diagram illustrating an example of a production process of agglomerate ore of the present invention.

FIG. 3 is a view showing a structure of a conventional agglomerate ore.

[Explanation of symbols]

 Reference Signs List 1 agglomerate ore 2 core particle 3 outer layer 4 agglomerate 5 nucleus 6 agglomerate 7 core particle 8 outer layer 11 raw material for nuclear particle 12 carbonaceous agent 13 iron-containing dust or / and iron ore 14 powdery binder 15 mixer 16 Liquid binder 17 Granulator 18 yards

Claims (2)

[Claims] Claims: 1. Sinter ore or lump ore particles having a diameter of more than 5 mm are used as core particles, and an outer layer containing the core particles has an iron-containing dust and / or iron ore having a diameter of 0.25 mm or less.
And a carbonaceous material having a diameter of 0.25 mm or less, and a connective tissue, wherein the ratio of the carbonaceous material in the outer peripheral layer is 10 to 50% by mass, and the ratio of the thickness of the outer peripheral layer to the radius of the core particle is 30.
% Or less, characterized by being not more than 0.1%. 2. An iron-containing dust having a diameter of 0.25 mm or less and / or an outer peripheral layer containing core particles containing coke as core particles.
And iron ore, a carbonaceous material having a diameter of 0.25 mm or less, and a connective structure, wherein the ratio of the carbonaceous material in the outer peripheral layer is 10 to 50% by mass, and the ratio of the thickness of the outer peripheral layer to the radius of the core particle is 30% or less. An uncalcined agglomerate for a blast furnace, characterized in that: