JP2001294944A - Method for producing agglomerate including carbonaceous material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method in which a high strength agglomerate including carbonaceous material is produced which is, chargable into a vertical furnace, such as blast furnace, cupola, without adding any binder and even reducing the consumption of a caking coal. SOLUTION: This producing method of the agglomerate including the carbonaceous material consists of a hot-forming of the mixture of a powder iron ore and a powder carbonaceous material at 250-550 deg.C. The carbonaceous material is constituted of one or more kinds of carbonaceous materials, and at least one kind of the carbonaceous material is the material having soft fusibility of log MF>1 (MF is Gieselei maximum fluidity), and the total volume ratio of the material having the soft fusibility is made to >=30% of the total mixture volume.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an agglomerated carbonaceous material as a raw material for a vertical furnace such as a blast furnace or a cupola.

[0002]

2. Description of the Related Art In addition to sinter ore, pellets and lump ore conventionally used as blast furnace raw materials, solid carbonaceous materials (eg, coal powder, coke powder, etc.) and fine ore or ironmaking dust (carbon, oxidized Cold-formed carbon material-containing cold pellets or briquettes (hereinafter referred to as carbon-material-containing cold pellets) formed by adding a binder to a mixture of iron or the like. It has been reported that when carbon pellets and other cold pellets are charged into a blast furnace, the gas utilization rate is improved [Inoue et al .: Iron and Steel (1986) S885]. It is expected to contribute, and furthermore, unlike conventional production of sinters and pellets, there are significant advantages such as the elimination of fired fuel and exhaust gas treatment.
In addition, there has been proposed a method in which cold pellets or the like containing carbon material are charged together with coke into a vertical furnace such as a cupola and reduced and melted to produce hot metal.

[0003]

However, a certain strength (crushing strength of about 500 N) is used so that the cold pellets with carbonaceous material and the like are not powdered during transportation or charging into a vertical furnace such as a blast furnace or a cupola. / Or more), and a method of adding cements as a binder during cold forming is generally used. In this method, it takes a few days for the carbon material-containing cold pellets and the like to develop strength, so a vast curing space is required.In addition, the slag ratio is increased in a blast furnace or the like, and the liquid permeability is deteriorated. There is a concern that the reduction may be delayed due to a delay in temperature rise due to endotherm when the crystal water is decomposed. On the other hand, when a binder other than cements is used to improve these, the cost is high and the cost merit is lost.

On the other hand, the applicant of the present application has disclosed Japanese Patent Application Laid-Open No. H11-092.
No. 833 proposes a method capable of producing a high-strength carbonaceous material agglomerate (briquette) without adding a binder by hot forming and then degassing a mixture of fine ore and caking coal. However, in this method, since the cost of the caking coal is high, there remains a problem that even if the cost of the binder can be reduced, the cost reduction effect is small.

Therefore, the present invention has been made to solve the above-mentioned problems, and without adding a binder,
It is an object of the present invention to provide a method capable of producing a high-strength carbonaceous interior agglomerate even when the amount of caking coal used is reduced.

[0006]

SUMMARY OF THE INVENTION The gist of the present invention is to provide a method for producing a carbonaceous interior agglomerate, which is performed by hot-forming a mixture of a powdery iron ore and a powdery carbon material at 250 to 550 ° C. And
The carbon material is composed of one or more types of carbon materials,
At least one of the carbonaceous materials is a carbonaceous material having a softening and melting property with a maximum flowability MF of log MF> 1 and the total volume of the softening and melting carbonaceous material is 30% or more of the volume of the mixture. A method for producing a carbonaceous material interior agglomerate, characterized in that:

The maximum flowability MF of the above-mentioned carbon material having softening and melting properties is logMF> 1.5, and the total volume of the carbon material having softening and melting properties is 20% or more of the volume of the mixture. This is a method for producing the carbonaceous interior agglomerate. Also, a method for producing a carbonaceous material interior agglomerate, which is performed by hot forming a mixture of powdery iron ore, ironmaking dust and powdery carbonaceous material at 250 to 550 ° C. 20% or less of the volume of the mixture, wherein the carbon material is composed of one or more carbon materials, and at least one of the carbon materials has a maximum flow rate
F is a carbon material having a softening and melting property of logMF> 1.5, and the total volume of the softening and melting carbon material is 30% or more of the volume of the mixture. This is a method for producing a compound.

A carbon material having softening and melting properties starts a thermal decomposition reaction when the temperature exceeds about 250 ° C., softens and melts, and solidifies when the temperature exceeds about 550 ° C. Therefore, when a carbon material having softening and melting properties is mixed with the powdered iron ore in this temperature range and pressed and molded, the molten carbon material easily penetrates into the voids between the particles of the powdered iron ore, and Strongly connect each other. Even if a carbon material that does not soften and melt is mixed in addition to the powdered iron ore, a strong connection is similarly formed by mixing a carbon material having softening and melting properties and press-molding. For this reason, a binder is not required, and an increase in the amount of slag in the blast furnace can be prevented.

Most of the volatile and tar components contained in the carbonaceous material are devolatilized and detarred during hot forming, and even if the agglomerates are charged into a blast furnace, the tar content is reduced. Volatilizes,
The problem of sticking to the gas treatment equipment does not occur.

When a carbon material having a maximum flowability MF of log MF> 1 is used as the carbon material having a softening and melting property, the volume of the softening and melting carbon material is determined by the powdered iron ore before hot forming. The volume is preferably 30% or more of the volume of the mixture of the stone and the carbonaceous material. The porosity of the mixture before hot forming is 3
It is about 0 to 40%, and the carbon material melted at the time of hot forming almost fills the voids of the mixture, so that a strong bond is obtained after the carbon material solidifies.

[0011] As a carbon material having softening and melting properties, the maximum flowability MF of the ghee cellar is log MF> 1.5, preferably lo
When a carbon material having a gMF> 3 is used, the volume of the carbon material having softening and melting properties may be 20% or more of the volume of the mixture. The molten carbon material has a low viscosity, and the molten carbon material expands due to generation of volatiles from the inside of the molten carbon material, so that the voids of the mixture can be filled with a small amount of the carbon material.

Part of the fine iron ore can be replaced with iron making dust. However, since iron-made dust has a very small particle size and the molten carbon material does not easily enter gaps between the iron-made dust particles, the mixing ratio of iron-made dust is limited to 20% or less by volume and has softening and melting properties. As a carbonaceous material, the highest flow rate MF of the low viscosity viscous melter is log MF>
It is necessary to set the carbon material of 1.5, preferably logMF> 3 to 30% or more by volume.

The volume of the carbon material refers to an apparent volume including pores in the carbon material particles, and can be obtained by dividing the mass by the apparent specific gravity. The same applies to iron ore.

Further, the solidified carbonaceous material in the agglomerate adheres to the fine iron ore (and iron making dust), and the contact area between the solidified carbon material and the fine iron ore (and iron making dust) increases. Therefore, when the agglomerate is charged into a blast furnace together with conventional blast furnace raw materials such as sintered ore, pellets, ore ore, etc., when the conventional blast furnace raw material alone is charged, a reaction does not occur in a low temperature region (700 to 700). Approximately 800 ° C), the carbon material and iron oxide in the agglomerate apparently undergo a direct reduction reaction (FeO + C → Fe
+ CO etc.). C generated by direct reduction reaction
O gas is used for reducing raw materials such as sinter, pellets, and ore between agglomerates, thereby improving the gas utilization rate and decreasing the fuel ratio. In addition, the CO ₂ gas generated by the reduction reacts preferentially with the carbon material contained in the agglomerate, so that the reaction with the lump coke charged from the furnace top is suppressed. And the air permeability in the blast furnace is improved.

[0015]

Embodiments of the present invention will be described below in detail.

FIG. 1 shows a conceptual diagram of a production flow of a carbonaceous interior agglomerate according to an embodiment of the present invention. Iron ore (and ironmaking dust) and carbon materials that do not soften and melt (for example,
Coke powder, steam coal, anthracite, oil coke, etc.)
If necessary, pulverize to 70% of particles of 74 μm or less.
Make powder of degree. Of the carbonaceous materials, the carbonaceous material having softening and melting properties (eg, caking coal, SRC, etc.) does not need to be as fine as the above-mentioned softening and non-melting carbonaceous materials, but it does not require powdered iron ore (and iron-making dust) and softening and melting. It is desirable to pulverize it to about 1 mm or less in order to maintain a good mixed state with the non-carbonaceous material.

Regarding the drying and preheating of the powdered iron ore and the carbonaceous material, the carbonaceous material is dried at a temperature of 200 ° C. or less by a rotary drier or the like to remove adhering moisture. On the other hand, iron ore is preheated to about 400 to 800 ° C. by a rotary kiln or the like so that the target temperature becomes 250 to 550 ° C. when mixed with the carbonaceous material. However, when ironmaking dust (blast furnace dust, converter dust, electric furnace dust, mill scale, etc.) is used to replace a part of iron ore, since ironmaking dust contains carbon and metallic iron, it burns when preheated. Steelmaking dust is used as it is without preheating.

The mixing of the dried and preheated carbonaceous material with the iron ore (and non-preheated ironmaking dust) is commonly used in this industry, where the carbonaceous material can be mixed in a short time to prevent overheating. For example, a biaxial mixer is used. Also, the mixer is kept warm to secure the molding temperature. The mixed carbonaceous material and iron ore (and ironmaking dust) are pressure-formed into agglomerates (briquettes) using, for example, a twin-roll type forming machine for hot forming. Pressure molding has a strength of about 5 which is sufficient for the agglomerate to withstand handling from the molding machine to the top of the blast furnace.
In order to obtain 00N / piece (for a size of about 30 mm × 25 mm × 15 mm), the molding pressure is set to 10 kN /
cm or more, preferably 20 kN / cm or more. In the agglomerate formed in this manner, the molten carbonized material having softening and melting properties penetrates into the gaps between the iron ore (and the ironmaking dust) and the carbon material particles that do not soften and melt, and the iron ore (and the ironmaking dust) In addition, the particles of the carbon material that are not softened and melted are strongly connected to each other, and the contact area between the iron ore (and the ironmaking dust) and the carbon material after being melted and solidified is also increased. In addition, the mixer and the molding machine have a closed structure, and the pyrolysis gas of the carbon material generated by the mixer and the molding machine is mainly composed of hydrocarbons. Therefore, this gas is suctioned and collected using an ejector or the like. Used as heating fuel for rotary kilns.

The formed agglomerates are cooled by an inert gas in a bunker, then discharged from the bunker and sieved. The powder under the sieve is returned to the mixer again to be used as a raw material. It becomes a high strength blast furnace raw material.

In the invention of JP-A-11-92833, a degassing step is provided in order to reduce volatile components remaining in the agglomerate after molding. However, the present invention does not necessarily require a degassing step. do not do. JP-A-11-92833
Since the agglomerate of the invention of the invention is charged into a reduction furnace in a high-temperature atmosphere of 1200 to 1400 ° C., a degassing step is provided for the purpose of preventing the agglomerate from being powdered due to sudden generation of the remaining volatile components. On the other hand, the agglomerate produced by the method of the present invention is charged into a blast furnace and gradually heated in the blast furnace. Powdering of the compound is not a problem.

When ironmaking dust containing a high concentration of Zn is used to replace a part of the iron ore, the iron ore is used so as not to cause a problem such as adhesion to furnace wall refractories due to Zn circulation in the blast furnace. The amount needs to be limited.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description, "coking coal" refers to the maximum flow rate MF> 10 ddpm (logMF>
1) refers to coal, and “steam coal” means MF <1dd
pm.

(Embodiment 1) FIG. 2 shows an outline of a hot forming machine used in this embodiment. Baking coals having different Geeseler maximum fluidity (MF) were added to steam coal B shown in Table 1 and iron ore C shown in Table 2 in a volume ratio of caking coal 30%, steam coal B 20%, and iron ore C 50%. After preheating only iron ore C to 600 to 700 ° C. in an electric furnace (not shown), the mixture was charged into a mixer kept at 400 to 500 ° C. by an oil heater and mixed to 440 to 450 ° C., and a twin-roll molding machine was used. Roll rotation speed 6 rpm, molding pressure 20 to 28 kN / c using
m was molded into an oval briquette (agglomerated product) of 30 mm × 25 mm × 15 mm, and the change in crushing strength was examined. The result is shown in FIG. The maximum flow rate of the gee cellar is JI
It was measured based on S-M8801. In addition, the volume of each of the carbonaceous materials and the iron ore is determined in advance by JIS-K21
It was determined by dividing by the respective apparent densities measured according to the method of 51 or JIS-M8716.

[0024]

[Table 1]

[0025]

[Table 2]

As shown in FIG. 3, as the maximum flow rate (MF) increases, the crush strength increases, and log MF increases.
Was about 1 or more, and a crushing strength of 500 N / piece or more was obtained. It was also found that the crushing strength was substantially constant when logMF was 1.5 or more.

Example 2 As in Example 1, the hot forming machine shown in FIG. 2 was used. Caking coal A and thermal coal B shown in Table 1.
And iron ore C shown in Table 2 was made into 50% by volume of iron ore C and 50% by volume of the total of caking coal A and general coal B, and caking coal A
Was changed into a briquette (agglomerate) under the same molding conditions as in Example 1, and the change in crushing strength was examined. FIG. 4 shows the results. In addition, about molding pressure, it implemented also about 29-38 kN / cm other than 20-28 kN / cm.

As shown in FIG. 4, as the volume ratio of the caking coal increases, the crushing strength of the briquette (agglomerated material) increases, and the caking coal (caking coal A) having a log MF of 3 or more is obtained. It was confirmed that a crushing strength of about 500 N / piece or more can be obtained by mixing about 20% or more in proportion. As described in the first embodiment, since the crushing strength becomes almost constant when the log MF is 1.5 or more, the log MF does not necessarily need to be 3 or more, but may be 1.5 or more.

Example 3 As in Examples 1 and 2, the hot forming machine shown in FIG. 2 was used. Caking coal A shown in Table 1, Table 2
The iron ore C shown in Table 3 and the blast furnace dry dust D shown in Table 3 were mixed and the volume ratio of caking coal A was changed so that the total Fe / C was 3.2 (constant) (corresponding to the iron ore). C and the blast furnace dry dust D were adjusted in volume) and molded into briquettes (agglomerated products) under the same molding conditions as in Example 2, and the change in crushing strength was examined. The result is shown in FIG.

[0030]

[Table 3]

As shown in FIG. 5, when ironmaking dust (blast furnace dry dust D) is used in place of a part of iron ore, the mixing ratio of ironmaking dust (blast furnace dry dust D) is about 20% by volume.
% Or less, the log MF is 3 or more caking coal (caking coal).
By mixing about 30% or more by volume of A), it was confirmed that a crushing strength of 500 N / piece can be obtained by molding with an appropriate pressure of 29 to 38 kN / cm. As in Example 2, the logMF of the caking coal does not necessarily need to be 3 or more, but may be 1.5 or more.

Further, the briquettes (agglomerated products) produced in the above Examples 1 to 3 were subjected to a tumbler rotational strength test based on JIS-M8712, and
FIG. 6 shows the relationship between the mm powder ratio and the crushing strength. As shown in FIG. 6, when the crushing strength becomes 500 N / piece or more, -1 m
The m powder ratio was reduced to 15% by mass or less, and it was confirmed that the powder was sufficiently resistant to handling when charged into a blast furnace.

[0033]

As described above, according to the present invention, without using a binder, a carbon material interior that can secure sufficient strength to be charged in a vertical furnace such as a blast furnace or a cupola even if expensive caking coal is reduced. The production method of agglomerates could be established. As a result, the production cost of the carbonaceous interior agglomerate was reduced.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a production flow of a carbonaceous material interior agglomerate according to an embodiment of the present invention.

FIG. 2 is a diagram showing an outline of a hot forming machine used in the present embodiment.

FIG. 3 is a graph showing the relationship between the maximum fluidity (MF) of caking coal and the crushing strength of agglomerates.

FIG. 4 is a diagram showing the relationship between the volume ratio of caking coal and the crushing strength of briquettes (agglomerates) when only iron ore is used.

FIG. 5 is a diagram showing the relationship between the volume ratio of caking coal and the crushing strength of briquettes (agglomerates) when blast furnace dry dust is used by replacing part of iron ore.

FIG. 6 is a diagram showing the relationship between -1 mm powder ratio and crushing strength in a tumbler rotational strength test of briquettes (agglomerated products).

Claims (3)

[Claims] 1. A method for producing a carbonaceous interior agglomerate, comprising hot-forming a mixture of a powdery iron ore and a powdery carbon material at 250 to 550 ° C., wherein the carbon material is one type. Alternatively, at least one of the carbonaceous materials is a carbonaceous material having a softening / melting property of which the maximum flowability MF is logMF> 1 and at least one of the carbonaceous materials has a softening and melting property. A method for producing a carbonaceous interior agglomerate, wherein the total volume is 30% or more of the volume of the mixture. 2. The carbonized material having softening and melting properties according to claim 1, wherein the maximum flow rate MF of the gee cellar is l.
A method for producing an agglomerate of carbonaceous material interior, characterized in that ogMF> 1.5 and the total volume of the carbonaceous material having softening and melting properties is 20% or more of the volume of the mixture. 3. A method for producing a carbonaceous material interior agglomerate, comprising hot-forming a mixture of powdery iron ore, ironmaking dust and powdery carbonaceous material at 250 to 550 ° C. Is not more than 20% of the volume of the mixture, and the carbonaceous material is composed of one or more types of carbonaceous materials, and at least one type of the carbonaceous materials has a maximum flow rate M
F is a carbon material having a softening and melting property of logMF> 1.5, and the total volume of the softening and melting carbon material is 30% or more of the volume of the mixture. A method for producing a compound.