JP2007261907A - Method for recycling used brick, recycled refractory raw material for monolithic refractory produced using the same, and monolithic refractory - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recycling a used brick adjusting a recycled refractory raw material to a particle size distribution suitable for recycling, increasing the recycling amount of the used brick, and suppressing the amount of disposal, and to provide a recycled refractory raw material for monolithic refractory produced using the same and the monolithic refractory. <P>SOLUTION: The method for recycling a used brick comprises a crushing step of crushing a used brick X; a rough classification step of classifying the crushed used brick into a massive material Xa and a remainder Xr; a fine classification step of classifying the remainder Xr into a course grain Xb and a fine grain Xc; and a raw material production step of mixing the course grain Xb and the fine grain Xc at a predetermined rate to produce a recycled refractory raw material for monolithic refractory. The course grain Xb obtained as a surplus in the raw material production step is sent to the crushing step and crushed together with the used brick X. The recycled refractory raw material for monolithic refractory and the monolithic refractory are produced by this recycling method. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to, for example, a method for recycling used bricks generated from steelworks, a recycled refractory raw material for amorphous refractories, and an amorphous refractory produced using the method.

Conventionally, for example, in steelworks, unshaped refractories or bricks are used as refractories in pots, dip tubes, topped cars, lances, or tundishes. The post-use bricks (hereinafter also referred to as used bricks) that are subject to recycling in the present application are disposed of, for example, landfilled, cannot be used effectively, are expensive to be disposed of, and are not economical. Therefore, the following recycling methods have been proposed.
For example, Patent Document 1 discloses a recycling method in which agglomerated materials and coarse particles of an alumina-silica used refractory in a particle size range of 3 mm to 40 mm are used together with an unused refractory raw material.
Patent Document 2 discloses a recycling method using used refractories of alumina and alumina-magnesia.

JP 2000-143355 A JP-A-9-165270

However, the recycling method disclosed in Patent Document 1 has a particle size range of less than 3 mm, that is, fine particles remain as waste. For this reason, the fine particles cannot be effectively used, and must be disposed of in landfills, which makes it impossible to further increase the amount of recycling and is uneconomical.
Moreover, since the recycling method disclosed in Patent Document 2 does not reuse used refractories less than 5 mm, the fine particles remain as waste. For this reason, as in the case of the above-mentioned Patent Document 1, a product that cannot be reused cannot be used effectively, and it is necessary to dispose of it in landfill.

The present invention has been made in view of such circumstances, and it is possible to adjust the particle size distribution of recycled refractory raw materials to be suitable for recycling, and it is possible to increase the amount of used bricks to be recycled than before, and to dispose of waste. It is an object of the present invention to provide a recycling method of used bricks capable of suppressing the above, a recycled refractory material for an unshaped refractory manufactured using the same, and an unshaped refractory.

The recycling method of used bricks according to the first invention in accordance with the above object includes a crushing process for crushing used bricks, a rough classification process for classifying used bricks crushed in the crushing process into a lump and the remainder, A reclassification step of further classifying the remaining portion classified in the coarse classification step into a coarse product and a fine product, and mixing the coarse product and the fine product at a predetermined ratio to obtain a recycled refractory material for an amorphous refractory. A method for recycling used bricks having a raw material manufacturing process for manufacturing,
Part or all of the coarse particles that are not used in the production of the recycled refractory raw material in the raw material manufacturing process are sent to the crushing process to be crushed together with used bricks.

In the used brick recycling method according to the first aspect of the present invention, the classification threshold A performed in the coarse classification step is in the range of 3 mm to 10 mm, and the classification threshold B performed in the subclassification step is In the range of 0.5 mm or more and less than 3 mm, it is preferable.
In the used brick recycling method according to the first invention, the ratio (A / B) of the threshold value A to the threshold value B is preferably 2 or more and 8 or less.
In the used brick recycling method according to the first invention, the recycled refractory material further includes an unused refractory containing 85% by mass or more of particles having a particle size of 74 μm or less, and 10% by mass of the recycled refractory material. It is preferable to add in an amount of 40% by mass or less.

In the used brick recycling method according to the first invention, the recycled refractory raw material after the addition of the unused refractory is put in a container with the recycled refractory raw material added with moisture, and this recycled refractory raw material is added. Is placed upside down so as to be in contact with the upper surface of the mounting table, and after removing the container, the test method for applying vibration to the mounting table is used, and the water content in the recycled refractory material is 12% by mass. And when the maximum width of the recycled refractory material before applying vibration is 100 mm, the maximum width of the recycled refractory material spread on the mounting table after applying vibration is within a range of 120 mm or more and 250 mm or less. It is preferable to make it.

The recycled refractory material for an irregular refractory according to the second invention that meets the above object is manufactured using the recycling method for used bricks according to the first invention.
The amorphous refractory according to the third invention that meets the above object is manufactured by using the recycling method for used bricks according to the first invention.

Recycled refractory material for irregular refractories manufactured using the method for recycling used bricks according to claims 1 to 5, and the method for recycling used bricks according to claim 6, and the used bricks according to claim 7. The non-standard refractory manufactured using the above recycling method is used to manufacture recycled refractory materials for non-standard refractories using fine particles that have not been used in the past. Surplus can be suppressed. As a result, the amount of recycling can be increased more than before, and the amount of used bricks disposed of can be suppressed.
Moreover, since the recycled refractory raw material for amorphous refractories to be produced contains coarse particles and fine particles, it can be adjusted to a particle size distribution suitable as a recycled raw material, and the fluidity and filling property of the refractory particles can be improved. Here, the irregular refractory manufactured by adjusting the mixing ratio of coarse and fine particles can control the particle size distribution and improve the filling property, for example, mechanical wear out of wear during use. The durability of the amorphous refractory can be ensured against (for example, mechanical wear due to molten metal flow).

And since the recycled refractory raw material for amorphous refractories is manufactured from the coarse particles and fine particles of the same kind of used brick, the constituent chemical components can be easily controlled. Thus, for example, for wear during use, for chemical wear (for example, chemical erosion due to basic slag), depending on the chemical components that make up the used brick, By selecting the intended use of the recycled refractory material, its durability can be ensured.
Furthermore, bricks tend to be hardened by sintering during use, and it is difficult for fine bricks to be generated during pulverization (crushing) of used bricks. For this reason, when the used brick fine particles and coarse particles are mixed at a predetermined ratio to obtain a recycled refractory raw material for amorphous refractories, the fine particles are insufficient and the coarse particles become surplus (relative In particular, there is a tendency for fine particles to be insufficient). Therefore, by sending a part or all of the excess coarse particles that are not used in the production of recycled refractory raw materials for irregular refractories to the crushing process and putting them into used bricks, the coarse particles are used bricks. Since the used bricks are crushed together with the gaps filled, the amount of fine particles generated can be increased. Since this fine particle can be used for the production of a recycled refractory material for an irregular refractory, the amount of excess coarse particles can be reduced, and the effect of suppressing the excess of used bricks can be further increased.

In particular, the recycling method for used bricks according to claim 2 sets the threshold A for classification performed in the coarse classification step and the threshold B for classification performed in the subclassification step within a predetermined range. The particle size of coarse particles and fine particles can be set appropriately. As a result, for example, it is possible to improve classification accuracy by preventing clogging during subclassification, and the particle size can be set appropriately, so that the filling property of the refractory particles is improved, and for the amorphous refractory to be manufactured. The fluidity of recycled refractory materials can be improved, and the corrosion resistance during construction is also improved.
The recycling method for used bricks according to claim 3 sets the ratio between the threshold value A for classification in the coarse classification step and the threshold value B for classification in the fine classification step. The classification particle size of the product can be set more appropriately, the fluidity of the recycled refractory material for the amorphous refractory to be manufactured can be further improved, and the corrosion resistance during construction is also improved.

Since the recycling method of used bricks according to claim 4 can adjust the particle size distribution to an appropriate state by adding a predetermined amount of fine unused refractories to the recycled refractory raw material for irregular refractories, The fall of fluidity | liquidity and a fillability can be suppressed, for example, the fall of the intensity | strength and corrosion resistance of a construction body using the recycled refractory raw material for amorphous refractories can be suppressed.
The recycling method of the used brick according to claim 5 is practically used because the maximum width of the recycled refractory material for the irregular refractory material that has been given vibration and spread on the mounting table is used as a measure of its fluidity. Recyclable refractory raw materials for indeterminate refractories that can withstand can be easily obtained by a simple method.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIG. 1 is an explanatory diagram of a method for recycling used bricks according to an embodiment of the present invention.

As shown in FIG. 1, the used brick recycling method (hereinafter also simply referred to as recycling method) according to one embodiment of the present invention is the same type (brick type X in this embodiment). A crushing step for crushing, a coarse classification step for classifying used bricks crushed in the crushing step into a lump and a residue, and a subclassification step for further classifying the remainder classified in the coarse classification step into a coarse particle and a fine particle A raw material production process for producing a recycled refractory raw material for amorphous refractories (hereinafter also simply referred to as a recycled raw material) by mixing coarse particles and fine particles at a predetermined ratio. The resulting coarse particles are sent to the crushing process, crushed with used bricks and recycled. Hereinafter, this will be described in detail with reference to FIG.

First, a recovery process for recovering used brick X is performed.
The used brick X to be collected is generated from the steelworks, and is used in any one or more of a pan, a dip tube, a topped car, a lance, and a tundish, for example. When collecting used brick X, for example, the chemical components differ depending on the location where used brick X is generated. In the present embodiment, if the component system (for example, alumina-silica system) of each used brick is the same, it is defined as the same kind of used brick.
In addition, used bricks tend to generate many coarse particles due to crushing. This is because, when manufacturing recycled materials from coarse and fine particles after crushing and classifying used bricks, coarse particles and fine particles are used in order to improve the particle packing property and ensure fluidity of the recycled materials. This is because the inventors of the present application have found that the excessive tendency of coarse particles becomes stronger when the blending ratio of the product is determined to be a predetermined ratio.

The collected used brick X has foreign matters such as bullion or slag attached thereto (hereinafter also simply referred to as attached foreign matter) or has entered the interior (hereinafter also simply referred to as inserted foreign matter). .
Therefore, the recovered used brick X is crushed, and a crushing process is performed to remove adhered foreign substances and inserted foreign substances.
Here, first, the collected used brick X is roughly crushed to a size (for example, the maximum width is about 70 mm or more and about 200 mm or less) that can be put into a crusher used in a subsequent process using, for example, a breaker. . By this rough crushing, the foreign matter separated from the used brick X, mainly adhering foreign matter, is separated and removed using, for example, one or both of manual sorting and a magnetic sorting machine.

Subsequently, the used brick X from which the adhering foreign matter has been removed is charged with a surplus of coarse particles Xb (to be described later) (hereinafter also referred to as surplus coarse particles Xd), and is finely crushed (crushed) together. The inserted foreign matter is removed from the removed used brick X.
Here, after the used brick X from which the adhering foreign matter has been removed and the excess coarse particles Xd are continuously supplied to the crusher, for example, it is applied to a magnetic separator. As a result, the used brick X is crushed according to the target particle size, and the foreign matter separated by the pulverization, mainly inserted foreign matter, is removed by the magnetic separator. Further, the surplus coarse particles Xd are crushed according to the target particle size.
Next, a coarse classification step is performed for classifying used brick X (hereinafter also simply referred to as crushed material) crushed together with excess coarse particles Xd. Here, for example, using a sieve sorter, the crushed material is roughly classified into a lump Xa and a remainder Xr. In addition, it is preferable that the threshold value A for classification performed in the coarse classification step is in the range of 3 mm to 10 mm.

Here, when the rough classification threshold A exceeds 10 mm, when a recycled material having such a size is applied as an irregular refractory, for example, an unfilled portion is generated in a corner portion to be filled. In other words, there is a problem that the recycled material that has been constructed is easily peeled off from the joint between the recycled material to be constructed and the construction surface. Furthermore, a lump having a particle diameter exceeding 10 mm has a recycling technique as disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-321968 filed by the present applicants and Patent Document 1, and has sufficient usage.
On the other hand, when the threshold A for coarse classification is less than 3 mm, the amount of particles having a small particle size in the recycled material is relatively increased, and the tap flow value (also referred to as TF value) is deteriorated (fluidity is too bad). ). Further, if the blending amount of the coarse particles contained in the remainder is decreased, the aggregate particles (for example, 1 mm or more) of the recycled material are decreased, and the tap flow value cannot be improved.

From the above, the rough classification threshold A is set in the range of 3 mm to 10 mm, but preferably the upper limit is 8 mm and the lower limit is 4 mm.
The above-described tap flow value is a value obtained by using a flow test method described in JIS R2521-1995 as a method for evaluating the packing property of recycled raw material particles. In the present embodiment, the recycled material added with 12% by mass of water is placed in a container, and this is placed upside down so that the recycled material contacts the upper surface of the mounting table. This is done by applying vibration to the mounting table, and the maximum width of the recycled material spread on the mounting table is obtained as the tap flow value. The container used here is a truncated cone when placed upside down on the mounting table, and the inner diameter of the portion in contact with the mounting table (the upper end portion when the recycled material is added) is 100 mm (error: ± 0). 0.5 mm), the inner diameter of the upper end (bottom when recycling raw materials are added) is 70 mm (error: ± 0.5 mm), and the height is 60 mm (error: ± 0.5 mm).

Next, the remaining Xr classified in the coarse classification process is further classified into a coarse product Xb and a fine product Xc using a sieve sorter. The classification threshold B used in the subclassification step is preferably in the range of 0.5 mm or more and less than 3 mm.
Here, when the threshold B for subclassification is 3 mm or more, the amount of aggregate particles (for example, those having a particle diameter of 1 mm or more) mixed in the fine particles after classification is excessively increased, and the recycled raw material has fluidity. It becomes difficult to control the amount ratio of the particles having a particle diameter of 1 mm or less to the coarse particles.
On the other hand, when the threshold B for subclassification is less than 0.5 mm, for example, when using a mesh, clogging of the mesh, and when using a bar, powder adheres to the bar. As a result, clogging occurs and classification accuracy deteriorates.
From the above, the subclassification threshold B is set in the range of 0.5 mm or more and less than 3 mm, but preferably the upper limit is 2 mm and the lower limit is 0.7 mm.

The ratio (A / B) between the coarse classification threshold A and the fine classification threshold B is preferably 2 or more and 8 or less.
Here, when the ratio (A / B) between the threshold A and the threshold B is less than 2, the width of the granularity range to be controlled, that is, between the threshold A and the threshold B (hereinafter referred to as A The width of -B) becomes too narrow, and the coarse grain part (grain size between AB) and the fine grain part (less than the grain size of threshold B) are biased. Here, when the particle size range is biased toward the fine grain part, the tap flow value is lowered, and when it is biased toward the coarse grain part side, the tap flow value is excessively increased and separation of the recycled raw material and moisture occurs. For this reason, it is not possible to secure the optimum ratio of coarse particles to fine particles from the viewpoint of fluidity.
On the other hand, when the ratio (A / B) between the threshold value A and the threshold value B exceeds 8, the width between A and B to be controlled becomes too wide, and the grain size is reduced in each of the coarse grain portion and the fine powder portion. A peak occurs, the optimal ratio of coarse particles to fine particles cannot be ensured from the viewpoint of fluidity, fluidity deteriorates, and the tap flow value decreases or the particle size distribution becomes nonuniform.

From the above, the ratio (A / B) between the threshold A for coarse classification and the threshold B for subclassification was set in the range of 2 to 8, but preferably the upper limit was set to 7. Let the lower limit be 3.
In the above-described rough classification, used bricks that have been finely crushed are mainly classified. This is because excess coarse particles are coarsely classified in advance.
In the above coarse classification and fine classification, moisture contained in the used brick causes fine particles to adhere to the coarse particles, and the particle size distribution after classification becomes unstable. Therefore, in order to prevent this, the amount of water contained in the used brick is 5% by mass or less, preferably 2% by mass or less, and more preferably 1% by mass or less. Examples of this method include means for storing used bricks in the recovery step indoors, and drying used bricks immediately before the coarse classification step or the fine classification step with a drying device.

Subsequently, a raw material production process for producing a recycled refractory material for an indeterminate refractory containing the coarse particles Xb and the fine particles Xc by mixing the coarse particles Xb and the fine particles Xc classified in the subclassification step at a predetermined ratio. Do.
In the production of this recycled raw material, the lump Xa obtained by coarse classification is not the main target for recycling. This lump Xa has the largest particle size because, for example, there is a recycling method as in Patent Documents 1 and 2, but it may be included in a part of the recycled material. According to the knowledge of the inventors of the present application, it is considered that up to about 5% by mass of the recycled raw material can contain a lump.
In addition, the area | region enclosed with the dotted line in FIG. 1 means the recycling of the used brick currently performed conventionally. Therefore, the processing outside the area is processed by the following method.

In mixing the coarse particles Xb and the fine particles Xc, it is important to ensure the mechanical strength of the construction body using recycled raw materials or the workability of the amorphous refractory. In order to realize these, the filling properties of recycled raw material particles are important. If there are too many fine particles, the added moisture required for construction increases, the filling properties of recycled raw materials decrease, and the mechanical properties of the construction body are reduced. The strength is lowered or the wear resistance when using the actual machine is lowered. Furthermore, since the slipperiness at the time of material conveyance by a fine particle falls, the clogging of the hose used for material conveyance becomes remarkable at the time of material pressure feeding.
Therefore, the inventors paid attention to the flow test method described in JIS R2521-1995 as a method for evaluating the filling property of the recycled refractory raw material particles for the irregular refractory.

This method is a test method for determining the optimum amount of water to be added to a refractory raw material whose particle size distribution is originally determined, but the inventors have determined that the amount of water to be added is a fixed value (12 in this application). It was newly found out that the packing property of the particles can be generally evaluated by comparing the tap flow values as mass%). That is, when there are too many fine particles, the required amount of added water increases, the tap flow value decreases, and the filling property of the construction body decreases. Conversely, if there are too many coarse particles, separation between the particles and the added water occurs, the tap flow value becomes excessive, and the fillability of the construction body decreases.
Note that the present invention mainly intends to manufacture inexpensive recycled raw materials using used bricks that are normally discarded, and to apply them to parts that do not require extremely high durability. It is considered that the evaluation that can withstand practical use is possible by evaluating the filling property of the recycled raw material for the irregular refractory by the flow value.

Here, when the coarse particles Xb and the fine particles Xc are mixed at a predetermined ratio, the properties differ depending on the type of used bricks to be used. Therefore, the coarse particles Xb and the fine particles Xc are 1: 9 to 9 : 9 kinds of combinations in which the coarse product Xb was increased by 1 to 1 and further, the coarse product Xb was increased by 1 to 3.5: 6.5 to 6.5: 3.5 A combination of types is preliminarily made experimentally and determined by evaluating the tap flow value.
In this evaluation, the maximum width (diameter) of the recycled raw material before applying vibration is set to 100 mm (corresponding to the inner diameter of the container), and the spreading width (diameter) of the recycled raw material for amorphous refractory by the subsequent application of vibration is 120 mm or more and 250 mm or less were accepted. Here, insufficient spread means that refractory workability is poor (that is, fluidity is too poor), and excessive spread means that mixed refractory particles are separated again to deteriorate refractory corrosion resistance. .
Therefore, it is preferable that the upper limit value of the tap flow value is 200 mm, further 180 mm, and the lower limit value is 130 mm, further 140 mm.
From the above, the coarse product Xb: fine product Xc is blended, for example, in the range of 1: 9 to 9: 1, preferably 2: 8 to 8: 2, more preferably 3: 7 to 7: 3. It is good to mix in the range.

In addition, the above-described evaluation was performed by using an unused refractory containing 85% by mass or more of a material having a particle size of 74 μm or less in the recycled refractory material for amorphous refractory, and 10% by mass or more of the recycled raw material for amorphous refractory 40 It is preferable to carry out after adding by mass or less. By adding an unused refractory having such a structure, the shape freezing property of the construction body in an undried state immediately after construction is improved as a refractory, and the sinterability during construction as a refractory is improved. It is possible to improve the filling property and fluidity of the refractory particles of the irregular refractory using the recycled raw material.
This unused refractory is made up of particle size-adjusted fine powder (for example, refined alumina powder) that has the role of adjusting the particle size distribution in order to mainly improve the filling and fluidity of the recycled material, and the shape freezing property of the recycled material. Or it is comprised from both the binder (for example, cement) which plays the role of the binder which improves sinterability, and the particle size of 74 micrometers is a specification value. Moreover, the function is not exhibited unless the particle size of 74 μm is contained by 85% by mass or more.
Here, part or all of the particle size-adjusted fine powder may be fly ash. In this way, the use of fly ash can reduce the manufacturing cost of the recycled raw material, and the fly ash that has been conventionally discarded can be recycled, which is environmentally preferable.
This fly ash is fine coal ash present in the combustion exhaust gas of a coal boiler, has a spherical shape with an average particle size of 20 μm or more and 30 μm or less, and the passing weight% of a 74 μm sieve is 70% by mass. The content is 100% by mass or less. Thus, the particle size of fly ash is substantially equivalent to the particle size of the unused refractory used in the present invention.
Further, the fly ash component excluding the remaining carbon content is exemplified by, for example, SiO ₂ : 45 mass% to 74 mass%, Al ₂ O ₃ : 16 mass% to 38 mass%, CaO: 0 0.1 mass% to 14 mass%, MgO: 0.1 mass% to 3 mass%, and Fe ₂ O ₃ : 0.6 mass% to 23 mass%.
As described above, fly ash contains a large amount of iron, but iron is a harmful substance in refractories. For this reason, the present inventors believe that the iron content in the unused refractory material needs to be 2% by mass or less in terms of metallic iron, and fly ash is added to a part or all of the particle size-adjusted fine powder. When using, it thinks that it is necessary to use fly ash in the range from which the iron content density | concentration of an unused refractory becomes 2 mass% or less in conversion of metallic iron. When the amount of Fe ₂ O ₃ contained in the fly ash is small, all of the particle size-adjusted fine powder may be made fly ash.
Further, in the above-described fine crushing (pulverization), the used brick was not crushed to 74 μm or less, but this requires a special crusher and the like, and the cost is increased due to low productivity. It is.
Here, when the amount of the outer refractory added to the outside is less than 10% by mass of the recycled raw material, the particle size of the entire amorphous refractory will be insufficient, and the fluidity and fillability will be reduced. And the strength or corrosion resistance of the construction body to be manufactured is reduced. Therefore, in this case, in order to improve the strength of the construction body, it is advisable to add 10% by mass or more and 40% by mass or less of an unused refractory as an outer covering in the recycled material.

On the other hand, when the external addition amount of the unused refractory exceeds 40% by mass of the recycled raw material, the additional amount of the unused refractory that has a large specific surface area and is likely to proceed with sintering becomes excessive. Since oversintering is likely to proceed during heat reception during use, sintering cracks are likely to occur, which may lead to a decrease in the life of the construction body, and there is a problem that the amount that can be recycled is reduced.
In view of the above, the amount of the outer refractory added to the outside is set to 10% by mass or more and 40% by mass or less of the recycled refractory material for the irregular refractory, but preferably the upper limit is 30% by mass, and the lower limit. Is 10 mass%.
Note that the unused refractory may contain, for example, 85% by mass or more of particles having a particle size of 74 μm or less, for example, 100% by mass of particles having a particle size of 74 μm or less, and a relatively large specific surface area of 1 mm or more. Unused refractories may be included.

As described above, it is preferable to add a predetermined amount of the above-mentioned predetermined particle size so that the recycled raw material has a predetermined particle size distribution, but the unused refractory constitutes an unused refractory other than the particle size. Depending on the material type, the function of the amorphous refractory using the recycled raw material can be improved. The contents will be described below.
As described above, the unused refractory includes a particle size adjusting fine powder having a role of adjusting the particle size distribution and a binder functioning as a binder.
The binder (binding material) is, for example, cement, and has an effect of solidifying by hydration and aggregation of CaO and Al ₂ O ₃ contained therein. In the present invention, since an unused refractory containing 85% by mass or more of particles having a particle size of 74 μm or less is used, the binder also has a function of ensuring fluidity and shape freezing property, but mainly a solidification effect by hydration aggregation. It is expected and if excessively contained, oversintering may occur depending on the amount of unused refractory added to the recycled material. Further, as will be described later, since the particle size-adjusted fine powder has a function of improving sinterability by heating during use, it is not preferable that the entire unused refractory is composed of a binder.
The particle size-adjusted fine powder is, for example, refined alumina powder, and has a function of filling gaps between particles of used refractories, and ensures fluidity and shape freezing property. In addition, by filling the gap, when using the recycled raw material as an amorphous refractory, diffusion bonding between the refractory particles is promoted, so that there is an effect of improving sinterability by heating during use.
From the above, the external addition amount of the binder added to the recycled raw material is 1% by mass or more, and the upper limit is 50% by mass of the amount of the unused refractory added to the recycled raw material (that is, the unused refractory added) When the amount is 10% by mass, 5% by mass or less, and when 40% by mass, 20% by mass or less is appropriate. Moreover, it is desirable that the external addition amount of the particle size-adjusted fine powder added to the recycled material is 5% by mass or more and 39% by mass or less depending on the addition amount of the binder.

When mixing the coarse particles Xb and the fine particles Xc, as described above, if the coarse particles Xb obtained from the same kind of used bricks and the fine particles Xc are continuously mixed at a predetermined ratio, the excess of the coarse particles Xb is obtained. Inevitable. This is because during the use of bricks, the sintering of the raw material tends to harden and harden. The crushing method that is commonly used (for example, the method of pressing and breaking used bricks with a jig, or the use of jigs) In a method of cracking bricks: for example, a jaw crusher, an impeller breaker, or a ball mill), fine particles are insufficient and coarse particles are excessive.
Then, when manufacturing the recycle raw material by mixing the coarse particles Xb and the fine particles Xc, a part of the excess coarse particles Xb that are not used in the production (for example, 10% by mass of the excess coarse particles Xb) 50 mass% or less) or all of them are sent as surplus coarse particles Xd to the crushing step described above, and mixed into used bricks from which the adhering foreign matter has been removed. As a result, as described above, the excess coarse particles Xd are crushed together with the used bricks in a state where the used bricks are filled, and the amount of fine particles Xc generated can be increased from the current level, so that the excess coarse particles Xd become surplus. The amount of coarse particles Xb is reduced, and the effect of suppressing the excess of used brick X can be further increased.
Note that it is impossible at this stage to achieve crushing that achieves a particle size distribution with no surplus.

Therefore, as in this embodiment, the recycled refractory raw material for the irregular refractory is manufactured by mixing the coarse particles Xb and fine particles Xc obtained from the used brick X, and in this case, excess coarse particles By mixing a part or all of the product Xb, that is, the excess coarse particle Xd into the used brick X before crushing, the amount of fine particles generated during crushing can be increased, and the generation of excess coarse particles can be suppressed. .
From the above, by using the recycling method of used bricks of the present invention, it is possible to adjust the recycled raw material to a particle size distribution suitable for recycling, and to increase the amount of used bricks recycled than before. The amount of disposal can be reduced.

In addition, the recycled refractory raw material for amorphous refractories manufactured in the raw material manufacturing process is used for at least a part of the amorphous refractories used in steelworks. Since the manufactured recycled raw material can be filled with increased fluidity, a relatively high strength refractory can be obtained. Moreover, since the same kind of raw material is used, the composition can be made uniform, and if the use of the amorphous refractory is selected according to the component system of the used brick, the durability against chemical wear can be ensured. Therefore, a recycled raw material can be used as the raw material for the amorphous refractory.
In addition, used bricks have a tendency to harden once undergoing a thermal history and harden, and the mechanical wear resistance of the amorphous refractory using at least a part of the recycled material is improved. It can be used in areas where amorphous refractories are applied.
From the above, the recycled raw material can be used for 50% by mass or more (more preferably 70% by mass or more) of the amorphous refractory, and the effect of reducing the amount of fine particles to be discarded can be increased.

Next, examples carried out for confirming the effects of the present invention will be described. Normally, as described above, the same kind of used bricks are used, and the crushed material is subjected to coarse classification and fine classification, respectively, and the conventional lump, coarse particle, and fine particle obtained are used. After recycling, the recycled raw material is manufactured by combining the remaining coarse and fine particles of used brick (see FIG. 1). However, here, in order to simplify the embodiment, conventional recycling is not taken into consideration, and all the coarse particles and fine particles obtained from the same type of used bricks are manufactured as the raw materials for recycling of the present invention. Review the results.
First, Table 1 shows the results of examining the effect of crushing surplus coarse particles returned to the crushing process and crushing with used bricks when the recycled raw material was produced in the raw material production process.

In Examples 1 and 2 shown in Table 1, surplus coarse particles are sent to the crushing step (refluxing amount of Example 1: 40% by mass of the total crushing amount, refluxing amount of Example 2: 30 of the total crushing amount. % By mass) Crushing with used bricks, while Comparative Example 1 is the result of crushing only used bricks without sending excess coarse particles to the crushing step.
For Examples 1 and 2 and Comparative Example 1, alumina-silica chamotte was used as the used brick, and in the raw material manufacturing process, the mixing ratio of the coarse particles and the fine particles (recycled mixing ratio) 4 to 6.
Conventional examples 1 and 2 are the examples described in Patent Document 1, using alumina-silica refractories as used bricks, and used bricks of 10 to 40 mm (lumps referred to in the present invention). Based on the upper limit value and the lower limit value of the mixing ratio of 3 to 10 mm (coarse particles as referred to in the present invention), the mixing amount ratio (recycle mixing amount ratio) of the lump and the coarse particles is 1: 2 and 1: 7. I have to.

Here, the change in the quantity ratio after classification will be described for the case where the excess coarse particles are not refluxed (Comparative Example 1) and the case where the excess coarse particles are refluxed (Example 1). In addition, at the time of crushing used brick, the lump and the fine particle produced | generated 20% at a time.
If the excess coarse particles are not refluxed, all are used bricks, so the mass ratio of crushed material (ie used bricks), coarse particles, and fine particles is 2 to 6 to 2. Become. At this time, since the blending ratio of coarse particles to fine particles to be recycled is 4 to 6, in order to use the fine particles less than the coarse particles to the maximum, 1.33 ( = 2 × 4/6) coarse particles may be used. Thereby, the recyclable amount (recycled amount) is 3.33.
Therefore, the amount of bricks to be discarded (waste amount) was 0 for fine particles and 4.67 (= 6-1.33) for coarse particles, for a total of 4.67.

On the other hand, when the reflux amount of excess coarse particles was 40% by mass of the total crushed amount, the amount of fine particles increased by fine pulverization was 10% by mass. Here, since the crushing object has a crushing amount ratio between used bricks and coarse particles of 6 to 4, the crushing object has a mass ratio of lump, coarse particles, and fine particles of 1.2. (= 6 × 0.2) vs. 6.6 (= 10−amount of lump−amount of fine particles) vs. 2.2 (= (6 + 4) × 0.2 × 1.1). At this time, since the mixing ratio of coarse particles to fine particles to be recycled is 4 to 6, in order to use the fine particles less than the coarse particles to the maximum, 1. 47 (= 2.2 × 4/6) coarse particles may be used. For this reason, the recyclable amount (recycle amount) is 3.67 (= 2.2 + 1.47).
Therefore, the amount of waste was 0 for fine particles and 1.13 for coarse particles (= 6.6-4-1.47), for a total of 1.13.
In addition, Example 2 is a result at the time of making the recirculation | reflux amount of an excess coarse particle into 30 mass% of the total crushing amount, and the amount of fine particles which increases by crushing was 5 mass%.

Further, in the conventional examples 1 and 2, the crushed material in which the quantity ratio of the lump, coarse particles, and fine particles became 0.18 to 5.32 to 4.5 without refluxing excess coarse particles. It is a result at the time of mixing the lump and coarse-grained material of 1: 2 and 1: 7.
Here, in Conventional Example 1, since the mixing amount ratio of the lump and coarse particles to be recycled is 1: 2, in order to use the lump less than the coarse particles to the maximum, 0.18 lump In contrast, 0.36 (= 0.18 × 2) coarse particles may be used. For this reason, the recyclable amount (recycle amount) is 0.54.
Therefore, the amount of waste was 4.5 for fine particles and 4.96 (= 5.32−0.36) for coarse particles, for a total of 9.46.
The conventional example 2 can also be obtained in the same manner as the above method.

As is clear from the above, with regard to the amount of waste, the results in which Examples 1 and 2 were smaller than those in Comparative Examples and Conventional Examples 1 and 2 were obtained. Here, when the amount of waste in Example 1 is 1, it is about 4 times in the comparative example and about 7 to 8 times in the conventional example.
Further, even when the amount of the lump added to the amount of waste is compared, if (the amount of waste + the amount of lump remaining) in Example 1 is 1, the comparison example is about three times, and the conventional example is about 4 times. Doubled.
And about the amount of recycle, like Examples 1 and 2, the amount of fine particles generated after crushing can be increased by about 5 to 10% by adding coarse particles to the used brick, and recycled. It was confirmed that the amount could be increased. When the recycling amount of Example 1 was 1, the comparative example was about 0.9, and the conventional example was about 0.1 to 0.4.
Thus, it has been confirmed that by applying the present invention, the amount of waste can be significantly reduced as compared with the conventional case, and the amount of recycling can be increased.

In addition, about Example 1, 2, it is changing the amount of fine particle production about 5-10 mass%, for example, when removing a bullion or slag from a used brick, by these adhesion situations. This is probably because the degree of crushing is different and the particle size composition of used bricks is fluctuating.
In addition, the amount of coarse particles added to the used brick was 10% by mass or more of the total crushed amount (used brick amount + coarse particle amount). The amount of coarse particles added was 20% by mass or more, and an increase in fine particles of about 5 to 10% by mass was further confirmed.

The TF value of the recycled refractory was measured by adding 25% by mass of an unused refractory containing 98% by mass of a particle size of 74 μm or less to the recycled material. Here, Examples 1 and 2 and Comparative Example 1 were able to ensure good filling properties of the refractory particles, so that good TF values were obtained. However, in the conventional examples 1 and 2, there is a lump, there is little collapse of the shape of the brick on the mounting table, water is separated from the lump, and moisture containing fine refractory particles spreads on the mounting table. The TF value deteriorated.
In Patent Document 1, either 1 or 2 of 3 to 10 mm particles that are unused refractories and particles that are 3 mm or less are blended, but in the unused refractories and used bricks, The properties differ in point, and the quality of the particles after crushing used bricks is not constant. For this reason, it is necessary to determine the blending amount ratio between the coarse and fine particles of used brick according to the quality.
Unused refractory particles are generally dense and uniform in quality.
In addition, when crushing used bricks after the use of unused refractories, the particles after crushing used bricks are often formed in a state where a plurality of particles are combined, and the surface becomes porous. ing.
And the quality of used bricks is non-uniform, for example, the heat history received by the used bricks varies depending on the site where the used bricks are used.
Therefore, even if the unused refractory of Patent Document 1 is simply replaced with used brick, the effect of the present invention cannot be obtained.
Subsequently, Table 2 shows the results of changing the coarse classification and subclassification thresholds A and B and the ratio (A / B) thereof.

Example 8 shown in Table 2 is a result of the coarse classification threshold A being lower than the lower limit of the optimum range described above (2 mm). In Example 7, the subclassification threshold B is optimum. This is the result of exceeding the upper limit of the range (4 mm). Further, Examples 5 to 7 are results in which the ratio between the thresholds A and B is outside the above-described optimum range.
In Examples 1 and 3 to 8, the blending amount of the coarse and fine particles of the recycled material is changed, and the unused refractory having the above-described composition is 25% by mass with respect to the recycled material. It has been added.

The waste amount of used bricks of Examples 1 and 3 to 6 shown in Table 2 can be suppressed to about 3 or less, and is greatly reduced compared to Comparative Example of Table 1 and Conventional Examples 1 and 2. I was able to confirm that I could do it. In Examples 7 and 8, the amount of waste was not measured because coarse particles prepared separately were added to used bricks because coarse particles were insufficient in the production of recycled raw materials.
As for the TF value, as in Examples 5 to 8, any one of the coarse classification threshold A, the fine classification threshold B, and the ratio of the thresholds A and B is the optimum range described above. Although the tendency to fall from Examples 1, 3, and 4 was seen by having remove | deviated from, it was the range which is satisfactory in use.
Next, Table 3 shows the results of changing the amount of unused refractory added or the particle size of 74 μm or less contained therein.

In Examples 11 and 13 shown in Table 3, the amount of unused refractory added is outside the optimum range described above, and Example 10 has a particle size of 74 μm or less contained in the unused refractory. It is outside the optimum range described above.
As for the TF value, as in Examples 1, 9, 12, and 13, an unused refractory having an optimum particle size of 74 μm or less was used, and the amount of the outer refractory added to the outside was set to be equal to or more than the lower limit of the optimum range. In some cases, good results were obtained. However, it was confirmed that the waste amounts of Examples 1 and 9 to 13 shown in Table 3 can be reduced to about 3 or less, and can be significantly reduced as compared with Comparative Example 1 and Conventional Examples 1 and 2 in Table 1. did it.
Table 4 shows the results of casting construction and spraying construction using the refractory raw materials of Examples 1 and 9 to 13.

In addition, about the pouring construction of Table 4, the situation after use can be used without any problem (◎), some damage has occurred but there is no problem in use (○), damage has occurred but can be used (△), The evaluation was made on a scale of 4 in which the damage was so great that it could not be used (x). For spraying construction, nozzle clogging is evaluated based on whether or not construction is possible (construction possible: ○, difficult to construct, but no problem: △, construction impossible: x), and adhesion dripping from the construction surface. (No occurrence of sagging: ◯, degree of sagging but no problem: △), and the overall evaluation can be used without problems (◎), although there are some problems in the construction body, although construction is possible (○), there was a problem with construction and construction body (△), and construction was impossible (x).

Here, the casting construction method will be described with respect to Example 1 in which the addition amount of the unused refractory and the particle size of 74 μm or less included therein are within the optimum range described above.
Alumina-silica brick was used as the same kind of used brick. In accordance with the recycling process described above, two kinds of sieves of 5 mm and 1 mm are used, and 40% by mass of coarse particles having a particle size of 5 mm or less and more than 1 mm are mixed with 60% by mass of fine particles having a particle size of 1 mm or less. The raw material was manufactured. The recycled raw material is further added with 25% by mass of unused amorphous refractory as an outer shell, and 12.5% by mass of water necessary for fluidity is added to this refractory material, and vortex is added. The mixture was kneaded with a mold mixer and poured into the cover of the hot metal pretreatment furnace.
As a result, the refractory material of Example 1 was able to be constructed without problems in fluidity and filling properties. Moreover, as a result of using this cover as an actual machine, it was confirmed that its durability was good and that it was possible to ensure the same life as a refractory used in the past.
In addition, about this casting construction, the amount of the unused refractory was set to the lower limit of the optimum range described in Example 12, and the particle size of 74 μm or less contained in the unused refractory, the lower limit of the optimum range described above. The value of Example 9 was slightly worse than that of Example 1, but was satisfactory.

Next, the spraying construction method will be described with respect to Example 1 in which the amount of unused refractory added and the particle size of 74 μm or less included therein are within the optimum range described above.
A refractory material in which 25% by mass of an unused amorphous refractory is added to the recycled raw material having the above-described structure is mixed in a dry powder state using a vortex mixer, and then air pressure is 0.3 to 0. The hose was pumped at 5 MPa. And at the front-end | tip of a spray nozzle, 20-30 mass% water was added with the outer cover with respect to the refractory material, and the spraying construction to the TPC receptacle with a construction surface temperature of 300-500 degreeC was performed.
As a result, for example, construction was possible without problems with nozzle clogging, adhesion, and rebound, and the wear rate during repair of the refractory at the receiving port could be reduced by 10% compared to the prior art.
About this spray construction, although Example 9 and Example 13 were a little worse results than Example 1, it was a thing of a grade without a problem.
In addition, about Example 10 and 11, although the favorable result was not obtained about any of the casting construction and spraying construction, as above-mentioned, the amount of waste can be reduced rather than before, and choose a use. Can be used sufficiently.

As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and the matters described in the scope of claims. Other embodiments and modifications conceivable within the scope are also included. For example, a method for recycling used bricks according to the present invention by combining some or all of the above-described embodiments and modifications, recycled refractory raw materials for amorphous refractories, and amorphous refractories manufactured using the same Is also included in the scope of rights of the present invention.
In the above embodiment, the case where the coarse classification and the fine classification are performed twice has been described, but it is of course possible to perform the classification three or more times depending on the required quality of the recycled raw material. is there. For example, when performing classification three times, by performing auxiliary classification between the coarse classification and the fine classification, an intermediate particle size between the coarse particles and the fine particles can be taken out by classification. By using this, it is possible to adjust the particle size distribution to a more appropriate state by producing a recycled refractory raw material for an irregular refractory, so that a decrease in fluidity and fillability can be suppressed. A decrease in strength and corrosion resistance can be suppressed.

And in the said embodiment, the coarse grain material which became surplus in a raw material manufacturing process was sent to the crushing process, and the case where it shreds (crushes) with the used brick from which the adhering foreign material was removed was demonstrated. However, it is possible to mix surplus coarse particles and perform coarse crushing and fine crushing on used bricks from which the adhered foreign substances after collection have not been removed, or to crush used bricks from which adhered foreign substances have been removed. After removing the inserted foreign matter by (pulverizing), excess coarse particles may be mixed and finely crushed. Here, when the coarse particles are mixed with the used brick from which the adhering foreign matter and the inserted foreign matter have been removed, since the foreign matter is previously removed from the coarse particle, it is again applied to the magnetic separator together with the used brick. There is no need, the total amount of sorting can be reduced, and the processing efficiency can be improved.

It is explanatory drawing of the recycling method of the used brick which concerns on one embodiment of this invention.

Claims (7)

A crushing step for crushing used bricks, a coarse classification step for classifying used bricks crushed in the crushing step into a lump and the remainder, and the residue classified in the coarse classification step into further coarse particles and fine particles A method for recycling used bricks, comprising: a subclassifying step for classifying; and a raw material manufacturing step for producing a recycled refractory raw material for an amorphous refractory by mixing the coarse particles and the fine particles at a predetermined ratio.
Used bricks characterized in that a part or all of the coarse particles that are not used in the production of the recycled refractory raw materials in the raw material manufacturing process are sent to the crushing process and crushed together with used bricks. Recycling method. The recycling method for used bricks according to claim 1, wherein the threshold A for classification performed in the coarse classification step is within a range of 3 mm or more and 10 mm or less, and the threshold B for classification performed in the subclassification step, A method for recycling used bricks, characterized by being within a range of 0.5 mm or more and less than 3 mm. The used brick recycling method according to claim 2, wherein a ratio (A / B) of the threshold value A to the threshold value B is 2 or more and 8 or less. Method. The used brick recycling method according to any one of claims 1 to 3, wherein the recycled refractory material further includes an unused refractory containing 85 mass% or more of particles having a particle size of 74 µm or less. A method for recycling used bricks, characterized by adding 10% by weight or more and 40% by weight or less of the refractory material. 5. The recycling method of used bricks according to claim 4, wherein the recycled refractory raw material after the addition of the unused refractory is put in a container with the recycled refractory raw material added with moisture, After placing the container upside down so as to contact the upper surface of the mounting table and removing the container, the test method for applying vibration to the mounting table is used, and the water content in the recycled refractory raw material is set to 12% by mass. And, when the maximum width of the recycled refractory raw material before applying vibration is 100 mm, the maximum width of the recycled refractory raw material spread on the mounting table after applying vibration is within a range of 120 mm or more and 250 mm or less. A method for recycling used bricks, characterized by: A recycled refractory raw material for amorphous refractories, which is manufactured using the recycling method for used bricks according to any one of claims 1 to 5. An indefinite refractory manufactured using the used brick recycling method according to claim 5.

Images