JP3502011B2 - Manufacturing method of carbonized interior agglomerates - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a carbonaceous material-containing agglomerate as a charging material for a vertical furnace such as a blast furnace and a cupola.

[0002]

2. Description of the Related Art In addition to sinter, pellets and lump ores that have been conventionally used as blast furnace raw materials, solid carbonaceous materials (for example, coal powder, coke powder, etc.) and powdered ores or ironmaking dust (carbon, oxidation) There is a so-called carbonaceous material-containing cold pellet or briquette (hereinafter referred to as carbonaceous material-containing cold pellet) cold-formed by adding a binder to a mixture of iron or the like). It has been reported that the use of carbonaceous materials such as cold pellets in a blast furnace improves the gas utilization rate [Inoue et al .: Iron and Steel (1986) S885], which improves the productivity of the blast furnace and reduces the fuel ratio. It is expected to contribute, and unlike the conventional production of sinter or pellets, it does not require burning fuel and exhaust gas treatment, which is a great advantage.
Further, it has been proposed that carbonaceous material-containing cold pellets and the like, together with coke, are charged into a vertical furnace such as a cupola to be reduced and melted to produce hot metal.

[0003]

However, in order to prevent the carbonaceous material-containing cold pellets, etc. from being pulverized during transportation or charging into the blast furnace, a certain strength (a crushing strength of about 400 N /
It is necessary to secure the number of cement or more, more preferably about 500 N / unit or more), and a method of adding cements as a binder during cold forming is usually used. This method requires a vast curing space because it takes several days for the carbonaceous material-containing cold pellets, etc. to develop strength, and further, the slag ratio rises in the blast furnace and the liquid permeability deteriorates, and the cement crystals There is a concern that the reduction may be delayed due to the delay in temperature rise due to the endotherm when water is decomposed.
On the other hand, when a binder other than cement is used to improve these, the cost is high and the cost merit is lost.

Therefore, the applicant of the present application has filed Japanese Patent Application Laid-Open No. 11-09.
No. 2833 proposed a method capable of producing a high-strength carbonaceous material-containing agglomerate (briquettes) without adding a binder by hot-forming a mixture of powdered ore and caking coal and then degassing. However, in this method, depending on the type and particle size of the iron ore used, the pyrolysis gas generated from the heated carbonaceous material loosely fills the mixture of the powdery iron ore and carbonaceous material before charging into the hot molding machine. Therefore, if the hot-molded agglomerate is not easily bitten into the hot-molding machine when it is charged into the hot-molding machine while it is sparsely packed, the hot-molded agglomerate has a structure with many voids, and the crushing strength decreases and molding is not possible. Occurred. further,
When the particle size of the powdered iron ore is large, the contact area between the iron ore and the carbonaceous material is decreased, and the substrate strength of the agglomerate is reduced, and the crushing strength is also reduced.

Therefore, the present invention has been made to solve the above-mentioned problems. Even if the pyrolysis gas or powdered iron ore generated from heated carbonaceous material has a large particle size, it is charged into a hot molding machine. Providing a method capable of producing a high-strength carbonaceous material-containing agglomerate by closely packing the mixture of the previous powdered iron ore and carbonaceous material even if the mixture is loosely packed The purpose is to do.

[0006]

The gist of the present invention is a method for producing an agglomerate containing carbonaceous material, which is carried out by hot forming a mixture of a powdery iron-containing raw material and a powdery carbonaceous material at 250 to 550 ° C. There
In the method for producing a carbonaceous material-containing agglomerate, the powdery iron-containing raw material has a bulk density of 1.5 g / cm ³ or more.

For example, a powdery iron ore having a bulk density of 1.5 g / cm ³ or more is heated to 400 to 800 ° C., a powdery carbonaceous material is dried at 250 ° C. or less, and then the powdery iron ore and the powder The method for producing a carbonaceous material-containing agglomerate is characterized in that the carbonaceous material is mixed to form a mixture at 250 to 550 ° C., and the mixture is hot-molded.

Alternatively, after the mixing ratio of the powdery iron ore and the iron-making dust is determined such that the bulk density of the mixture when the powdery iron-ore and the iron-making dust are mixed is 1.5 g / cm ³ or more. Heating the pulverized iron ore to 400 to 800 ° C., drying the pulverized carbonaceous material at 250 ° C. or lower, and then mixing the pulverized iron ore, the pulverized carbonaceous material and the iron dust not heated to 250 to 250 as a mixture at 550 ° C
It is a method for producing a carbonaceous material-containing agglomerate, which comprises hot-forming a mixture at 550C.

A method for producing a carbonaceous material-containing agglomerate, which is performed by hot forming a mixture of a powdery iron-containing raw material at 250 to 550 ° C. and a powdery carbonaceous material, wherein the mixture is subjected to vibration and densely packed. Crushing strength 4 characterized by hot forming after
This is a method for producing a carbon material- containing agglomerate of 00 N / piece or more .

Further, the bulk density of the powdery iron-containing raw material is preferably 1.4 g / cm ³ or more.

For example, a powdery iron ore having a bulk density of 1.4 g / cm ³ or more is heated to 400 to 800 ° C., a powdery carbonaceous material is dried at 250 ° C. or less, and then the powdery iron ore and the powder Charcoal- containing agglomerates having a crushing strength of 400 N / piece or more, characterized in that the carbonaceous materials are mixed to form a mixture of 250 to 550 ° C., the mixture is vibrated to be densely packed, and then hot-molded. Is a manufacturing method.

Alternatively, when powdered iron ore and ironmaking dust are mixed, the bulk density of the mixture is 1.4 g / cm ³
After determining the mixing ratio of the powdery iron ore and the iron-making dust as described above, the powdery iron ore is heated to 400 to 800 ° C., the powdery carbonaceous material is dried at 250 ° C. or lower, and then the powder Iron ore, the powdered carbonaceous material, and the iron dust that is not heated are mixed to form a mixture at 250 to 550 ° C., 25
After vibrating the mixture at 0 to 550 ° C. to close the mixture,
Crush strength 400N / piece or less characterized by hot molding
It is a method for producing the above agglomerate containing carbon material.

The "iron-containing raw material" means a raw material mainly containing iron oxide such as iron ore, iron-making dust (blast furnace dust, converter dust, electric furnace dust, mill scale, etc.), and "carbonaceous material". Means a carbonaceous material such as coal or SRC that exhibits softening and melting properties when heated.

The "bulk density" is a loosely packed bulk density measured based on JIS-Z2504 used for metal powder.

When the carbonaceous material exceeds about 250 ° C., a thermal decomposition reaction starts and it softens and melts, and when it exceeds about 550 ° C., it solidifies. Therefore, if the carbonaceous material having softening and melting property is mixed with the powdery iron-containing raw material in this temperature range and pressure-molded, the melted carbonaceous material easily penetrates into the voids between the particles of the powdery iron-containing raw material and becomes powdery. The iron-containing raw materials are firmly connected to each other. Therefore, the binder is not required, and the increase in the amount of slag in the blast furnace can be prevented.

Further, most of the volatile components and tar components contained in the carbonaceous material are devolatilized and tar-free during hot molding, and even if the agglomerates are charged into the blast furnace, the tar components will remain. Volatilize,
There is no problem of sticking to gas treatment equipment.

It is preferable that the powdery iron-containing raw material maintain a high bulk density (1.5 g / cm ³ or more) by adjusting the particle size distribution and the like. Even if the mixture with powdery carbonaceous material expands due to the pyrolysis gas generated from the carbonaceous material, the mixture can still maintain a dense packing state at the time of charging the hot forming machine, so agglomeration after hot forming The compound has a dense structure with few voids and can increase the crush strength. Further, by crushing so that the bulk density becomes high, the contact area between the iron ore and the carbonaceous material increases, and there is also an effect that the crushing strength of the agglomerate after hot forming becomes higher.

Alternatively, instead of maintaining the bulk density of the powdered iron-containing raw material at a high level, vibration is applied to the mixture loosely filled with the pyrolysis gas before hot forming to bring the mixture into a close packed state. The biting is improved, and the same effect can be obtained during hot molding.

The solidified carbonaceous material in the agglomerate thus produced adheres to the powdery iron-containing raw material, and the contact area between the solidified carbonaceous material and the iron-containing raw material increases. Therefore, when the agglomerate is charged into the blast furnace together with the conventional blast furnace raw materials such as sinter, pellets, and lump ores, the reaction does not occur in the low temperature range (700- 80
From about 0 ° C), the carbonaceous material and the iron oxide in the iron-containing raw material in the agglomerate are apparently directly reduced (for example, FeO + C → Fe).
+ CO) to start. Since the gas generated by the direct reduction reaction is mainly CO, it is directly used for the reduction of raw materials such as sinter, pellets, and lump ores between agglomerates, improving the gas utilization rate and lowering the fuel ratio. To do. Further, the CO ₂ gas generated by the reduction reaction preferentially reacts with the carbonaceous material contained in the agglomerate, so that the reaction with the agglomerated coke charged from the furnace top is suppressed, and as a result, the amount of coke powder generated is reduced. And the air permeability in the blast furnace is improved.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below.

FIG. 1 shows a conceptual diagram of a production flow of a carbonaceous material-containing agglomerate according to the present invention. As an iron-containing raw material,
A powdery iron ore having a bulk density of 1.5 g / cm ³ or more measured in advance is used. When powdered iron ore having a bulk density of less than 1.5 g / cm ³ is used, it may be further pulverized to adjust the bulk density to 1.5 g / cm ³ or more. However, as will be described in Example 1 to be described later, since bulk density is rather lowered when pulverized too much, the bulk density may be adjusted by the following method. That is, the crushing particle size is changed by changing the crushing time of a small amount of iron ore in advance, the bulk density is measured for each crushing particle size, and the crushing particle size (crushing time)
The bulk density is 1.5g in advance.
The particle size (crushing time) of crushing / cm ³ or more may be selected. Alternatively, the mixing ratio may be determined so that the bulk density becomes 1.5 g / cm ³ or more when two or more kinds of powdery iron ore (or powdery iron ore and iron-making dust) are mixed. The particle size of the carbonaceous material is not particularly limited, but it is desirable that the carbonaceous material be pulverized to 1 mm or less in order to maintain a good mixed state with the powdery iron-containing material.

Regarding the drying and preheating of the powdery iron ore and the carbonaceous material, the carbonaceous material is dried with a rotary dryer or the like at a temperature of 250 ° C. or lower to remove the attached water. On the other hand, the iron ore is preheated to about 400 to 800 ° C. in a rotary kiln or the like so that the target temperature is 250 to 550 ° C. when mixed with the carbonaceous material. However, when iron-making dust is used by replacing a part of the iron ore, the iron-making dust contains carbon and metallic iron and therefore burns when preheated. Therefore, the iron-making dust is used as it is without being preheated.

The dry and preheated carbonaceous material and iron ore (and iron dust that is not preheated) are mixed in a short time in order to prevent overheating of a part of the carbonaceous material, which is commonly used in this industry. 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-molded into an agglomerate (briquette), preferably using a molding machine for hot molding having an indenter. Pressure molding is a crushing strength of about 400 N / piece (30 mm × 25 mm × 1) sufficient for the agglomerate to withstand handling from the molding machine to the blast furnace top charging.
In order to obtain (for a size of about 5 mm), the molding pressure is 10 MPa or more, preferably 20 MPa or more. The agglomerate molded in this way is such that the molten softening and melting carbonaceous material penetrates into the spaces between the closely packed iron ore (and iron making dust) particles, and the iron ore (and iron making dust) particles They are firmly connected to each other, and the contact area between the iron ore (and iron-making dust) and the carbon material after melting and solidification is also large. Also, the mixer and the molding machine have a closed structure, and the pyrolysis gas of the carbonaceous material generated in the mixer and the molding machine is mainly composed of hydrocarbons, so this gas is suctioned and collected using an ejector or the like, and the collected gas is Used as heating fuel for rotary kilns.

Since the agglomerated product having a high temperature immediately after molding is soft and has low strength, it is cooled with an inert gas in the bunker to develop sufficient strength, then discharged from the bunker and sieved, and the powder under the sieve is mixed again. Return to and use as raw material. The upper part of the sieve is an agglomerate having a desired high strength of about 400 N / piece or more. Relationship between -1mm powder ratio and crushing strength generated from agglomerates in a tumbler rotation strength test (JIS-M8712) that simulates handling of agglomerates to the blast furnace top and loading during blast furnace top loading Is shown in FIG. As shown in FIG. 6, the crush strength is 400
If it is N / pieces or more, the -1 mm powder ratio is as small as 17% by mass or less, so that pulverization of the agglomerate by the above handling does not pose a problem.

In the invention of Japanese Patent Laid-Open No. 11-92833, a degassing step is provided to reduce the volatile content remaining in the agglomerate after molding, but the degassing step is not always necessary in the present invention. do not do. Japanese Patent Laid-Open No. 11-92833
Since the agglomerate of the present invention is charged into a reducing furnace in a high temperature atmosphere of 1200 to 1400 ° C., a degassing step is provided for the purpose of preventing agglomeration of the agglomerate due to rapid generation of residual volatile components. On the other hand, the agglomerate produced by the method of the present invention is charged into the blast furnace and gradually heated up in the blast furnace, so that the remaining volatile components are gradually removed. The pulverization of the product is not a problem.

When iron-making dust containing a high concentration of Zn is used by replacing a part of the iron ore, use it so that problems such as adhesion to the furnace wall refractory due to Zn circulation in the blast furnace do not occur. You need to limit the amount.

Instead of using the powdery iron-containing raw material having a bulk density of 1.5 g / cm ³ or more, for example, a vibrator is installed in the chute at the exit of the mixer, and the carbonaceous material and iron ore (and ironmaking) mixed in the mixer are mixed. When the mixture of (dust) is cut into a molding machine through a chute, vibration may be applied by a vibrator to increase the bulk density, and then pressure molding may be performed by the molding machine. Even if the mixture expands in the mixer due to pyrolysis gas generated from the carbonaceous material, the mixture is densely packed in the chute by applying vibration, and the agglomerated product after molding has a dense structure with few voids and crush strength. Becomes higher. The degree of close packing can be adjusted by appropriately changing the length of the chute and the vibration intensity of the vibrator.

Also in the method of applying vibration to the above mixture, it is preferable to keep the bulk density of the powdery iron-containing raw material high to some extent because the crushing strength of the agglomerate can be increased. For example, as shown in Example 2 below, 1.4 g / c
It is preferably m ³ or more, and more preferably 1.5 g / cm ³ or more.

[0029]

EXAMPLES (Example 1) FIG. 2 shows an outline of the hot molding machine used in this example. Caking coal A shown in Table 1 is used as the carbonaceous material, and iron ore B shown in Table 2 is used as the iron-containing raw material.
Or C was used. The iron ore C was crushed with a ball mill at different crushing times, and the bulk density was changed by changing the particle size. The bulk density was measured for each crushed particle size, and the results are shown in FIG. The volume average diameter was used as an index showing the pulverized particle size. From FIG. 3, the bulk density slightly increases as the crushed particle size (volume average diameter) is decreased, but the bulk density becomes maximum at a certain crushed particle size (volume average diameter), and when the crushed particle size (volume average diameter) is further decreased. On the contrary, it was found that the bulk density was decreased. Caking coal A is 22% by mass, iron ore B or C is 78% by mass, and only iron ore B or C is preheated to 600 to 700 ° C. in an electric furnace not shown, and then 400 to 500 by an oil heater. The mixture is charged into a mixer kept at ℃ and mixed at 450 to 460 ℃, using a twin roll type molding machine, roll rotation speed 6 rpm, molding pressure 20 to 29 k
It was molded into an egg-shaped briquette (agglomerate) having a size of 30 mm × 25 mm × 15 mm at N / cm, and changes in crushing strength were examined. The result is shown in FIG.

[0030]

[Table 1]

[0031]

[Table 2]

As shown in FIG. 4, the crush strength increases as the bulk density of the iron ore increases, and if the bulk density is 1.5 kg / cm ³ or more, the crush strength is about 400 N /
It was confirmed that a more preferable crushing strength of about 500 N / piece or more can be obtained when the density is 1 or more and the bulk density is 1.77 kg / cm ³ or more.

Example 2 In order to confirm the effect of close packing by applying vibration to the mixture before hot molding, as shown in FIG. 5, the mixer outlet of the hot molding machine used in Example 1 was used. A vibrator was installed on the chute. The same raw material as in Example 1 was used, except that the vibrator was operated.
It was molded into a briquette (agglomerate) under the same molding conditions as above and the change in crushing strength was examined. The vibration intensity of the vibrator is as follows: amplitude 1 mm, vibration frequency 2333 rpm, 0.15 k
W. The results are also shown in FIG.

As shown in FIG. 4, the bulk density was 1.42 g which could hardly be molded before the installation of the vibrator.
It was confirmed that even when a powdered iron ore of / cm ³ was used, a crushing strength of about 400 N / piece was obtained by vibrating the mixture before hot forming with a vibrator to close the mixture.

[0035]

As described above, according to the method of the present invention, a mixture obtained by mixing powdery carbonaceous material with a powdery iron-containing raw material having a bulk density of 1.5 g / cm ³ or more is hot molded at 250 to 550 ° C. By doing so, a high-strength carbonaceous material-containing agglomerate that can be charged into the blast furnace can be manufactured.

After the mixing ratio of the powdery iron ore and the iron-making dust is determined so that the bulk density of the mixture becomes 1.5 g / cm ³ or more when the powdery iron-ore and the iron-making dust are mixed. The powdery iron ore is heated to 400 to 800 ° C., the powdery carbonaceous material is dried at 250 ° C. or less, and then the powdery iron ore, the powdery carbonaceous material and the iron dust not heated are mixed to form 250. ~ 550 ° C as a mixture, 250
By hot-molding the mixture at ˜550 ° C., it is possible to manufacture a high-strength carbonaceous material-containing agglomerate that can be charged into the blast furnace even when using iron-making dust.

Furthermore, after vibrating the mixture to make it densely packed, it is hot-molded to be charged into the blast furnace even if the bulk density of the powdery iron-containing raw material is lower than 1.5 g / cm ^3. It is possible to produce a high-strength carbon material-containing agglomerate.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an outline of a hot molding machine used in this example.

FIG. 3 is a diagram showing a relationship between a crushed particle size (volume average diameter) of iron ore and a bulk density.

FIG. 4 is a diagram showing the relationship between the bulk density of iron ore and the crush strength of briquettes (agglomerates).

FIG. 5 is a view showing a situation where a vibrator is installed on a chute of an exit of a mixer.

[Fig. 6] -1 m during tumbler rotation strength test of agglomerates
It is a figure which shows the relationship between m powder rate and crushing strength.

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) C22B 1/00-61/00 C21B 5/00

Claims (7)

(57) [Claims] 1. A method for producing an agglomerate containing carbonaceous material, which is carried out by hot forming a mixture of a powdery iron-containing raw material and a powdery carbonaceous material at 250 to 550 ° C. A method for producing a carbonaceous material-containing agglomerate, which has a hardness density of 1.5 g / cm ³ or more. 2. A powdery iron ore having a bulk density of 1.5 g / cm ³ or more is heated to 400 to 800 ° C. to obtain a powdery carbonaceous material of 250.
The carbonaceous material-containing agglomerate characterized by being dried at a temperature of not higher than 0 ° C, and then the powdery iron ore and the powdery carbonaceous material are mixed to form a mixture at 250 to 550 ° C, and the mixture is hot-molded. Method. 3. After the mixture ratio of the powdery iron ore and the iron-making dust is determined so that the bulk density of the mixture becomes 1.5 g / cm ³ or more when the powdery iron-ore and the iron-making dust are mixed. , Heating the powdery iron ore to 400 to 800 ° C., drying the powdery carbonaceous material at 250 ° C. or lower, and then mixing the powdery iron ore, the powdery carbonaceous material and the iron dust that is not heated to 2
A method for producing a carbonaceous material-containing agglomerate, which comprises forming a mixture of 50 to 550 ° C. and hot molding the mixture of 250 to 550 ° C. 4. A method for producing a carbonaceous material-containing agglomerate, which is performed by hot forming a mixture of a powdery iron-containing raw material at 250 to 550 ° C. and a powdery carbonaceous material, wherein vibration is applied to the mixture. Crushing strength 4 characterized by performing hot forming after dense packing
A method for producing a carbon material- containing agglomerate of 00 N / piece or more . 5. The method for producing a carbonaceous material-containing agglomerate according to claim 4, wherein the powdery iron-containing raw material has a bulk density of 1.4 g / cm ³ or more. 6. A powdery iron ore having a bulk density of 1.4 g / cm ³ or more is heated to 400 to 800 ° C. to obtain a powdery carbonaceous material of 250.
Characterized in that it is dried below ℃, and then the powdered iron ore and the powdered carbonaceous material are mixed to form a mixture of 250 to 550 ° C., and the mixture is vibrated to be densely packed, and then hot-molded. A method for producing a carbonaceous material- containing agglomerate having a crushing strength of 400 N / piece or more . 7. The mixing ratio of the powdery iron ore and the ironmaking dust is determined so that the bulk density of the mixture becomes 1.4 g / cm ³ or more when the powdery iron ore and the ironmaking dust are mixed. , The powdery iron ore is heated to 400 to 800 ° C., the powdery carbonaceous material is dried at 250 ° C. or lower, and then the powdery iron ore, the powdery carbonaceous material, and the iron dust not heated are mixed to obtain 25
Production of a carbonaceous material- containing agglomerate having a crushing strength of 400 N / piece or more, which is characterized by forming a mixture of 0 to 550 ° C., vibrating the mixture of 250 to 550 ° C. to close packing, and then hot molding. Method.