JP5747467B2 - Production method of raw materials for blast furnace - Google Patents

Description

  The present invention relates to a method for producing a raw material for a blast furnace for directly recycling a fine-grained magnetic deposit among the magnetic deposits recovered by magnetic separation from slag generated in a steel making process.

  Since metallic iron contained in the slag generated in the steelmaking process, so-called metal content, is useful as a resource, it is usually sorted and recovered by magnetic force in the slag crushing and classification process for the purpose of reuse. Among the metal components selected and collected as magnetic deposits in this way, a massive magnetic deposit having a relatively large particle size is a processing furnace in which various processes in the steelmaking process (hot metal pretreatment, decarburization blowing, etc.) are performed, It is thrown into the blast furnace and electric furnace as iron sources and recycled. On the other hand, finely magnetized magnetic deposits have a high water content, so there is a danger of a steam explosion if they are put directly into a high-temperature furnace. For this reason, in order to put into a high-temperature furnace as described above, it is necessary to perform a drying process in advance, which increases the processing cost.

In addition, when recycling the finely magnetized magnetic deposits to the blast furnace, there is a problem that the air permeability in the furnace deteriorates if it is put into the blast furnace as it is. For this reason, in order to recycle the fine-grained magnetic deposits into the blast furnace, it is necessary to agglomerate them to a certain size (particle size) as in the case of sintered ore.
As a technique for recycling fine-grained magnetic deposits, for example, Patent Document 1 discloses a method of using a recovered metal (magnetized deposit) of 5 mm or less as a part of a sintering raw material, that is, sintering fine-grained magnetic deposits. Technology to recycle to blast furnace as part of ore is shown.

JP 2001-192741 A

  However, when a fine-grained magnetic deposit is used as a sintering raw material, metallic iron is oxidized in the sintering process and is included in the sintered ore as iron oxide. When this sintered ore is recycled to the blast furnace, the iron oxide is reduced again to metallic iron by a reducing material such as coke. In other words, the method of blending finely magnetized magnetic deposits into the sintering raw material and recycling it to the blast furnace involves oxidizing what was originally metallic iron and then reducing it again, consuming unnecessary reducing materials and energy. Will be.

  Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art and to recycle the finely divided magnetic material collected by magnetic separation from the slag generated in the steelmaking process directly to the blast furnace. An object of the present invention is to provide a production method capable of producing a massive blast furnace raw material made of kimono at low cost and efficiently.

The gist of the present invention for solving the above problems is as follows.
[1] A kneaded product obtained by adding a binder and water to a fine-grained magnetic material collected by magnetic separation from slag generated in a steelmaking process is kneaded so that the flow value of the kneaded material at the end of kneading is 105 to 140 mm . A method for producing a raw material for a blast furnace, characterized in that after hydrating and curing, a crushing treatment and a classification treatment are performed to obtain a massive raw material for a blast furnace.
[2] A method for producing a raw material for a blast furnace according to [1], wherein the binder is blast furnace cement .

[3] In the production method of [1] or [2 ] above, the finely magnetized magnetic product has a particle size in which the ratio of the particle size of 10 mm or less is 70% by mass or more, and the produced bulk blast furnace raw material is a granule The manufacturing method of the raw material for blast furnaces characterized by having the particle size whose ratio of diameter 10-100mm is 70 mass% or more.
[4] In the manufacturing method according to any one of [1] to [3] , the kneaded material is placed in a layer in a yard, the cured kneaded material is roughly crushed with a breaker, and then crushed with a crusher A method for producing a raw material for a blast furnace, characterized by classifying with a sieve.
[5] In the manufacturing method of [4] above, in the yard, after mixing the fine magnetic adhering material and the binder with a shovel, water is added and kneaded, and then the kneaded material is made to a thickness of 500 mm or less with a shovel. After laying in layers in the yard and curing for 3 days or more, the cured product is roughly crushed to 300 mm or less with a breaker, then crushed to 100 mm or less with a crusher, and then classified with a sieve. A method for producing a raw material for a blast furnace, characterized in that the product on the sieve is used.

  According to the present invention, the material for a granular magnetic deposit recovered by magnetic separation from the slag generated in the steel making process is used as a material, and the bulk blast furnace raw material is inexpensively oxidized without oxidizing the metallic iron contained therein. It can be manufactured efficiently. For this reason, the metallic iron which comprises a fine-grained magnetic deposit can be directly recycled to a blast furnace as an iron raw material, and reduction | restoration materials, such as coke in a blast furnace operation, and the improvement of production capacity can be aimed at.

The graph which shows the relationship between the compounding rate of a binder, and the compressive strength of an agglomerate about the case where blast furnace cement, Portland cement, and blast furnace slag fine powder are each used as a binder in the manufacturing method of this invention. In the production method of the present invention, a graph showing the relationship between the flow value of the kneaded product at the end of kneading and the compressive strength of the agglomerated product The manufacturing method of this invention WHEREIN: The graph which shows an example of the relationship between the flow value of the kneaded material at the time of completion | finish of kneading | mixing, and the amount of added water In the production method of the present invention, in the case where 91% by mass of magnetic deposit and 9% by mass of blast furnace cement are blended and the amount of added water is 7-10% by mass with respect to 100% by mass of magnetic deposit + blast furnace cement, curing of the kneaded product Graph showing the relationship between days and compressive strength Explanatory drawing which shows one Embodiment in the case of performing a series of manufacturing processes in a yard in the manufacturing method of this invention.

In the method for producing a raw material for a blast furnace according to the present invention, a binder and water are added and kneaded to a fine-grained magnetic material collected by magnetic separation from slag generated in a steelmaking process, and the kneaded material is hydrated and cured. The blast furnace raw material is obtained by crushing and classification.
The slag generated in the steelmaking process (hereinafter referred to as steelmaking slag) contains a considerable amount of metallic iron, and for the purpose of reusing this metallic iron, magnetic separation is performed in the steelmaking slag crushing and classification process, Metallic iron is recovered as a magnetic deposit. Usually, this magnetized material is divided into lumpy and fine granular materials by sieving, etc., and the lumpy ones are processed as they are in various processes in the steelmaking process (hot metal pretreatment, decarburization blowing, etc.). Since it can be recycled to a blast furnace, an electric furnace, etc., a fine-grained magnetic deposit that cannot be recycled as it is is used as a material (raw material) of the production method of the present invention.

As the steelmaking slag, for example, steelmaking slag generated in processes such as hot metal pretreatment, converter blowing, casting, etc. (for example, decarburization slag, hot metal dephosphorization slag, hot metal desulfurization slag, hot metal desulfurization slag, ingot slag, etc. ), Electric furnace slag, and the like, and may include two or more of these.
Although there is no particular restriction on the particle size of the fine-grained magnetic material used in the present invention, in general, a magnetic material having a particle size exceeding 10 mm can be used by directly putting it into a blast furnace without agglomeration. In this case, a magnetic material having a large ratio of particle size of 10 mm or less is used. From the viewpoint of sufficiently obtaining the effect of the present invention that finely magnetized magnetic deposits can be directly recycled to a blast furnace, generally, those having a particle size in which the ratio of particle size of 10 mm or less (under 10 mm) is 70% by mass or more. It is preferable to use, and it is more preferable to use a particle having a particle size of 70% by mass or more with a particle size of 5 mm or less (5 mm under sieve).
Further, the iron content (total content of iron contained as metallic iron and iron oxide) of the fine-grained magnetic deposit is not particularly limited, but is preferably 50% by mass or more from the viewpoint of improving the efficiency of iron recycling.

As the binder, cement, blast furnace slag fine powder, or the like can be used, and cement is particularly preferable. In addition, as the cement, any of various cements such as Portland cement and blast furnace cement may be used. However, when the blast furnace cement is used, the strength of the agglomerated material to be produced becomes higher.
FIG. 1 shows the blending ratio of the binder and the compressive strength of the obtained agglomerate (after 3 days of curing) when blast furnace cement, Portland cement and fine powder of blast furnace slag were used as the binder in the production method of the present invention. (Compressive strength). For the measurement of compressive strength, in accordance with the strength test of JIS-R-5201: Physical test method for cement, magnetic materials, binders and water were put into a kneader for mechanical kneading and kneaded for 2 minutes, then use a vibrator. A 40 mm × 40 mm × 160 mm specimen was prepared by packing it in a triple molding mold for a mortar specimen, and the strength (compressive strength) was measured after curing for 3 days.

According to FIG. 1, the compressive strength is highest when blast furnace cement is used as the binder. This is magnetically attached of fine granular many percentage of slag fraction, the slag includes the CaO or Ca _{(OH) 2,} the CaO and Ca _{(OH) 2} becomes alkaline stimulant, blast furnace cement This is thought to be because strength development is enhanced in order to effectively extract the latent hydraulic properties of the blast furnace slag fine powder contained therein. On the other hand, when only blast furnace slag fine powder is blended as a binder as shown in FIG. 1, the minimum compressive strength can be secured, but the strength is not improved so much even if the blending amount is increased. Further, in the case of Portland cement, it is considered that Ca (OH) ₂ contained in the magnetized material is excessive, and the strength is slightly inhibited.
Accordingly, the binder is preferably cement or a material containing cement as a main material, and among them, a material containing blast furnace cement or a blast furnace cement as a main material is preferable.

Although there is no special restriction | limiting in the compounding quantity of a binder, About 7-13 mass% is suitable for the compounding quantity of a binder, when the total mass of a magnetic deposit and a binder is 100 mass%. If the blending amount of the binder is less than 7% by mass, the strength of the agglomerated material is low, and even if the strength of the agglomerated material can be maintained by adjusting the moisture content, the product yield may be lowered. On the other hand, when the blending amount of the binder exceeds 13% by mass, particularly in the case of cement, the strength is developed in a short period of time, and the compressive strength exceeds 10 N / mm ² after curing for 3 days. May decrease. Further, when the blending amount of the binder is increased, the material cost is increased, and the ratio of the magnetic deposit is relatively reduced, so that the merit of blast furnace recycling is reduced.

When kneading by adding a binder and water to a fine-grained magnetic deposit, usually the binder is first added to the magnetic deposit and mixed, and then water is added and kneaded. Water is added so that the flow value (mortar flow value) at the end of kneading is within the proper range.
The flow value (mortar flow value) of the kneaded product at the end of kneading is desirably 105 to 140 mm, and preferably 110 to 130 mm. For this purpose, the amount of water added is appropriately adjusted. If the flow value of the kneaded product at the end of kneading is less than 105 mm, kneading tends to be insufficient, and the strength and yield variation of the agglomerated product to be produced tend to increase. On the other hand, when the flow value exceeds 140 mm, the fluidity of the kneaded product is improved, but the strength of the agglomerated product tends to be lowered.

  FIG. 2 shows the relationship between the flow value of the kneaded product at the end of kneading and the compressive strength (compressed strength after 7 days of curing) of the agglomerated product in the production method of the present invention. In the measurement of the flow value (mortar flow value) at the end of kneading, in accordance with the flow test of JIS-R-5201: Physical test method for cement, magnetic materials, binders and water are put into a kneader for mechanical kneading for 2 minutes. After kneading, the flow value was measured. At that time, it was added respectively in the case of a blending ratio of 92.6% by mass of the magnetic deposit and 7.4% by mass of blast furnace cement and in a blending ratio of 91.0% by mass of the magnetic deposit and 9.0% by mass of blast furnace cement. The flow value was changed by changing the amount of water. In addition, a 40mm x 40mm x 160mm specimen was prepared by packing in a triple mold for mortar specimen, and after 7 days curing, the strength (compressive strength) was measured, and the relationship between flow value and compressive strength was investigated. did.

According to FIG. 2, it can be seen that the compressive strength tends to decrease in the range where the flow value of the kneaded product at the end of kneading exceeds 140 mm.
FIG. 3 shows an example of the relationship between the flow value of the kneaded product at the end of kneading and the amount of added water, and it can be seen that the flow value of the kneaded product can be adjusted by the amount of added water. Therefore, the amount of water added may be appropriately adjusted based on the relationship between the flow value and the amount of added water.

The kneaded product can be hydrated and cured (cured) in any form. For example, the kneaded product may be poured into a suitable form and cured by hydration, or placed in a yard such as outdoors to form a hydrate. It may be cured. This curing period is until a target compressive strength (compressive strength suitable for crushing treatment) is obtained. Here, as the compressive strength suitable for the crushing treatment, about 4 to 10 N / mm ² is appropriate. When the compressive strength is less than 4 N / mm ² , the yield tends to be reduced due to fineness during rough crushing. On the other hand, when the compressive strength exceeds 10 N / mm ² , workability of crushing treatment such as rough crushing may be reduced.

FIG. 4 shows a mixture of 91% by mass of magnetic deposit and 9% by mass of blast furnace cement (binding material), and the amount of added water is 7 to 10% by mass with respect to 100% by mass of magnetic deposit and blast furnace cement. This shows the relationship between the number of days of product curing and the compressive strength, and the target compressive strength of 4 N / mm ² or more is reached after curing for about 3 days. In addition, in preparation of a compressive strength test piece and a strength test, according to the strength test of JIS-R-5201: Physical test method of cement, a magnetic material, a binder, and water are put into a kneader for mechanical kneading and kneaded for 2 minutes. After that, a 40 mm × 40 mm × 160 mm specimen was prepared by packing in a triple molding mold for mortar specimens without using a vibrator, and the strength (compressive strength) was measured after curing for a predetermined period.

The cured body having a predetermined strength by curing is crushed and then classified by sieving to obtain an agglomerated product (lumped blast furnace raw material) having a predetermined particle size. There is no particular restriction on the particle size of the agglomerate thus produced, but for the purpose of the present invention to agglomerate the fine-grained magnetized material to a size that can be charged into a blast furnace, the particle size is 10 mm. It is preferable that the ratio of ultra 100 mm or less is 70% by mass or more, and it is more preferable if sieving is performed within this range.
The compressive strength of the agglomerated product (bulk blast furnace raw material) as a product is preferably 7 N / mm ² or more. If the compressive strength is less than 7 N / mm ² , there is a possibility that problems such as deterioration of the air permeability of the blast furnace may occur due to cracking and fine graining caused by dropping impact when being introduced from the top of the blast furnace.

  For mixing finely divided magnetic materials and binders and kneading by adding water to the mixture, you may use normal mixing equipment for fresh concrete, but use heavy machinery for civil engineering such as excavators. You can also go outside in a yard. Mixing and kneading with an excavator can be uniformly mixed by first thoroughly mixing the magnetic deposit and the binder, and then adding water and mixing. Next, the kneaded material is placed in a layer in the yard (laying down) and hydrated and cured (cured). The cured product of the kneaded product is usually subjected to classification treatment after being subjected to crushing treatment in two or more stages to become a product. For example, the cured body is first roughly crushed with a breaker, then main crushed with a crusher, and then classified with a sieve to obtain the product on the sieve.

FIG. 5 shows an embodiment in which a series of manufacturing steps are performed in a yard in the manufacturing method of the present invention. Hereinafter, a case where cement is used as the binder will be described as an example.
The magnetic deposit A recovered from the steelmaking slag is, for example, sieved to 5 mm, and the magnetic deposit a having a particle size of 5 mm or less (under 5 mm sieve) is used as a raw material. The amount of the magnetic deposit a is suitably about 100 to 300 ton / batch. If it is less than 100 ton / batch, the number of kneading increases, and a wide kneading place is required, which is not efficient. On the other hand, if it exceeds 300 ton / batch, it takes too much time to knead and the coagulation of the binder proceeds, and the fluidity of the kneaded material may be deteriorated and workability may be deteriorated.

In the mixing and kneading by a heavy machine in the yard (hereinafter described as an example of an excavator), first, the magnetized material and the cement are sufficiently mixed, and then water is added and kneaded. At that time, it is advisable to build a circular bank with a mixture of magnetic deposit and cement, put water therein, and gradually knead the mixture and water. In this case, as shown in FIG. 5, first, a circular bank whose center is recessed with a magnetic deposit a is made, and a predetermined amount of cement b (for example, blast furnace cement) is added thereto with a lorry vehicle. Subsequently, after mixing well with shovel, building bank with recessed again centered mixture x ₀ of magnetically attracted material a cement b. A predetermined amount of water is added to the dent from a water truck and kneaded with an excavator. If kneading shovel, it is added a large amount of water at a time, since flows out before mixing with the mixture x _0, can be uniformly mixed when water is added while confirming the degree and fluidity of the kneaded .

  The flow value of the kneaded product x is measured, and when the target flow value is reached, the kneading is terminated. Next, the kneaded material x is placed in layers in the yard so as to have a predetermined thickness with an excavator (lay out). If this casting thickness is too thick, the workability of rough crushing after curing deteriorates, so the casting thickness is preferably 500 mm or less, and usually about 300 mm is appropriate. Further, in order to improve the workability of rough crushing after curing, using an excavator tip or the like, the kneaded material x placed in a layer shape is arranged in parallel at an appropriate interval (for example, 0.5 to 2 m) or It is preferable to form grooves in a lattice shape or the like.

  After curing for 3 to 6 days after placement, the cured body y is roughly crushed to an appropriate size (for example, 300 mm or less) with a breaker. Furthermore, after curing for about 2 to 5 days as necessary, the material is crushed to a maximum diameter of the product (for example, 100 mm or less) with a crusher. Next, in order to remove the fine particles, sieving is performed with, for example, 5 mm, and classification is performed, and the product on the sieve is used as a product (lumped blast furnace raw material). On the other hand, the sieve is used again as a material.

As a method of agglomerating a fine-grained material, it is conceivable to add a binder and water to the material and granulate, but this method requires a dedicated facility for granulation. On the other hand, as described above, the present invention has an advantage that it can be carried out without special equipment as long as a place can be secured.
The agglomerates (bulk blast furnace raw material) obtained by the method of the present invention can recycle the metal iron contained in the magnetic deposits to the blast furnace as it is, and also deteriorate the air permeability of the blast furnace because it is agglomerated. No problem arises. Further, CaO contained in the binder becomes a part of the auxiliary material of the blast furnace.

A, a Magnetic deposit b Cement x ₀ mixture x Kneaded material y Hardened body

Claims (5)

A binder and water are added to and kneaded into a fine-grained magnetic product recovered from the slag generated in the steel making process by magnetic separation , and the flow value of the kneaded product at the end of the kneading is set to 105 to 140 mm. A method for producing a blast furnace raw material, characterized by obtaining a massive blast furnace raw material by curing and classifying after curing. The method for producing a blast furnace raw material according to claim 1, wherein the binder is blast furnace cement . The fine-grained magnetized product has a particle size in which the ratio of the particle size of 10 mm or less is 70% by mass or more. The method for producing a raw material for a blast furnace according to claim 1 or 2, characterized by comprising: The kneaded product was Da設in layers yard, the kneaded product was cured crude crushed in a breaker, then after crushing with a crusher, to any one of claims 1 to 3, characterized in that classified with a sieve The manufacturing method of the raw material for blast furnaces of description. In the yard, after mixing the fine magnetic material and the binder with a shovel, water is added and kneaded, and then the kneaded material is placed in a layer in the yard so as to have a thickness of 500 mm or less. After curing for 3 days or more after installation, the cured product is roughly crushed to 300 mm or less with a breaker, then crushed to 100 mm or less with a crusher, classified with a sieve, and the product on the sieve is used. The manufacturing method of the raw material for blast furnaces of Claim 4 to do.

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