JP4555793B2 - How to recycle used refractories - Google Patents

Description

The present invention is, for example, about the recycling how the spent refractory materials generated from ironworks.

Conventionally, for example, in steelworks, unshaped refractories or bricks are used as refractories in pots, dip tubes, topped cars, lances, or tundishes. Of these refractories, the refractories after use (hereinafter also referred to as used refractories) that are subject to recycling in this application are disposed of, for example, landfilled and cannot be used effectively, and the disposal is costly. It is 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, since 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, it is necessary to discard most of the fine particles, which is not preferable for the environment.
Also, with respect to the recycling method disclosed in Patent Document 2, fine particles less than 5 mm are not reused, and this remains as waste. Therefore, as in the case of Patent Document 1 described above, many of them need to be discarded. , Environmentally undesirable.
Furthermore, since the recycling method disclosed in Patent Documents 1 and 2 is a method of mixing a used refractory into an unused refractory, it is not possible to further increase the amount of recycling.
In particular, in the recycling method disclosed in Patent Document 1, when the amount of used refractory recycled is increased, the obtained recycled raw material is poor in fluidity and workability, and refractory manufactured using the refractory. Had a high porosity and a low strength, and was not practically usable. In addition, in the used refractory and the unused refractory, when compared with those of the same particle size after crushing, the quality obtained from the used refractory is not constant, the surface state is porous, It was different from that obtained from unused refractories. For this reason, good results could not be obtained even if the particle size region using the one obtained from the unused refractory was replaced with one obtained simply from the used refractory.

The present invention has been made in view of such circumstances. Recycling of used refractories, which has better quality than before, can increase the amount of used refractories that can be recycled, and can reduce the amount of waste disposal. an object of the present invention is to provide an mETHODS.

The method for recycling a used refractory according to the first invention in accordance with the above object further comprises a rough classification step of crushing a used refractory and classifying the refractory into a lump and a remaining portion, and the remaining portion classified in the rough classification step. Used having a sub-classification step for classifying into coarse particles and fine particles, and a raw material manufacturing step for producing recycled refractory raw materials by mixing the coarse particles and fine particles of the used refractories in a predetermined ratio A method for recycling refractories,
Unused refractories containing 85% by mass or more of those having a particle size of 74 μm or less are added to the recycled refractory materials by adding 10% to 40% by mass to the recycled refractory material. Recycled refractory raw material,
Moisture is added to the recycled refractory raw material for the irregular refractory and placed in a container, which is placed upside down so that the recycled refractory raw material for the irregular refractory contacts the upper surface of the mounting table. After removing, using the test method for imparting vibration to the mounting table, the amount of water contained in the recycled refractory material for the irregular refractory is 12% by mass, and the irregular refractory before imparting vibration. When the maximum width of the recycled refractory material for materials is 100 mm, the maximum width of the recycled refractory material for the irregular refractory material spread on the mounting table after applying the vibration is in the range of 120 mm to 250 mm. And adjusting the mixing ratio of the coarse particles and the fine particles.

In the method for recycling used refractories according to the first invention, the used refractories for obtaining the coarse particles and the fine particles are preferably of the same type.
In the method for recycling used refractories according to the first invention, the used refractories are composed of two or more types, and the used refractories for obtaining the coarse particles and the fine particles are different types. preferable.
In the method for recycling used refractories according to the first invention, the used refractories have different types of bricks and irregular refractories, and part or all of the coarse particles are obtained from the bricks, It is preferable that part or all of the fine particles are obtained from the amorphous refractory.

In the method for recycling used refractories according to the first invention, the unused refractory includes a binder and a particle size adjusting powder, and the binder is added to the recycled refractory raw material in an amount of 1% by mass or more. The upper limit of the amount of the binder added is preferably 50% by mass of the amount of the unused refractory, and the particle size-adjusted powder is preferably added to the recycled refractory material in an amount of 5% by mass to 39% by mass. .
In the method for recycling used refractories according to the first invention, it is preferable that part or all of the particle size-adjusted powder is fly ash.

Recycling how the spent refractory of claims 1 to 6, wherein, using the conventional use fines that have not been, so to produce a recycle refractory material for monolithic refractories, for example, as in the prior art The surplus of fine particles can be suppressed. As a result, it is possible to increase the amount of recycling than before, and the amount of used refractory to be disposed of can be suppressed.
In addition, since the recycled refractory raw material for amorphous refractory to be produced contains coarse and fine particles, it can be adjusted to a particle size distribution suitable as a recycled refractory raw material, and the fluidity and filling property of the refractory particles can be improved. . Furthermore, by adding a predetermined amount of fine unused refractory, the particle size distribution can be adjusted to a more appropriate state, so that deterioration in fluidity and fillability can be suppressed. For example, recycled refractories for amorphous refractories The fall of the intensity | strength and corrosion resistance of the construction body which uses a raw material can be suppressed.

Furthermore, to adjust the mixing ratio of coarse particles and fine particles, vibration is given to the recycled refractory raw material to which fine unused refractories are added, and the widest width of the recycled refractory raw material for irregular refractories spreads. Is used as a measure of its fluidity (that is, moisture is added to the recycled refractory raw material for the irregular refractory and placed in a container, and the recycled refractory raw material for the irregular refractory is placed on the upper surface of the mounting table. The test method for applying vibration to the mounting table after removing the container by placing it upside down so as to contact the surface, and using recycled refractory materials for amorphous refractories that can withstand practical use with good quality, It can be easily obtained by a simple method.
In this way, the amorphous refractory manufactured using the recycled refractory raw material in which the mixing ratio of coarse and fine particles is adjusted can control the particle size distribution and improve the filling property. Among the wear, the durability of the amorphous refractory can be secured against mechanical wear (for example, mechanical wear due to molten metal flow).

In particular, the recycling method of used refractories according to claim 2 is a chemical component constituting the recycled refractory raw material for amorphous refractories to produce coarse and fine particles from the same kind of used refractories. Can be controlled easily. For this reason, for example, with respect to chemical wear (for example, chemical erosion by basic slag) among wear during use, the amorphous refractory manufactured according to the chemical components constituting the used refractory By selecting the intended use of recycled refractory raw materials, the durability can be ensured.
The method for recycling used refractories according to claim 3 is to obtain coarse particles and fine particles from different types of used refractories. It is possible to suppress the surplus of coarse particles or fine particles that are inevitably generated when the fine particles are mixed. Thereby, it becomes possible to aim at the further expansion of the amount of recycling, and can suppress the disposal amount of a used refractory.
In addition, since a single recycling method can be used to handle the recycling of a plurality of types of used refractories, the work can be simplified and the workability is good.

Since the method for recycling used refractories according to claim 4 uses bricks and amorphous refractories as used refractories, coarse particles that tend to be generated more frequently due to crushing of bricks, and irregular refractories Recycled refractory raw materials can be produced by mixing fine particles that tend to be generated by crushing. By mixing such coarse particles and fine particles to produce a recycled refractory raw material, the effect of suppressing the excess of used refractories can be further increased.
The used refractory recycling method according to claim 5 uses an unused refractory containing a predetermined amount of binder and particle size-adjusted powder. For example, an amorphous refractory obtained by recycling used refractory. The quality of can be made more stable. In addition, cracking of the amorphous refractory due to oversintering caused by excessive addition of unused refractory is eliminated.
The method for recycling used refractories according to claim 6 uses fly ash as the particle size-adjusted powder. Therefore, the amount of expensive particle size-adjusted powder can be reduced, and it is economical and fly ash is industrial waste. Can be recycled, which is environmentally preferable.

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 refractories according to one embodiment of the present invention, and FIG. 2 is a relationship between the tap flow value of the recycled refractory raw material, the apparent porosity of the refractory, and the compressive strength. It is explanatory drawing which shows.

As shown in FIG. 1 and FIG. 2, a used refractory recycling method (hereinafter also simply referred to as a recycling method) according to an embodiment of the present invention involves crushing the same type of used refractory and lump And the coarse classification step of classifying the remainder into the remainder, the fine classification step of further classifying the remainder classified in the coarse classification step into coarse particles and fine particles, and the coarse and fine particles of the used refractory are mixed at a predetermined ratio. And a raw material manufacturing process for manufacturing a recycled refractory raw material (hereinafter also simply referred to as a recycled raw material), and the mixing ratio of coarse particles and fine particles in this raw material manufacturing process is determined using a test method described later. It is adjusting. This will be described in detail below.

First, a recovery process for recovering used refractories is performed.
Used refractories to be collected are generated from steelworks, such as pots, dip pipes, topped cars, lances, tundishes, pot covers, upper bodies of secondary smelting (smelting) equipment, nozzles, etc. And one or more bricks such as converters. When collecting used refractories, the chemical components differ depending on, for example, the location and type of used refractories and are collected individually. In addition, in this Embodiment, if the component system (for example, alumina-silica type) of each used refractory is the same, it defines as the same kind of used refractory.
Here, the used refractory can be the same type, for example, brick (for example, chamotte) or amorphous refractory (for example, lower alumina material or high alumina material). Two or more different types of refractories may be used.

The collected used refractories have foreign matters such as bullion or slag attached thereto (hereinafter also simply referred to as attached foreign materials) or have entered the interior (hereinafter also simply referred to as inserted foreign materials). .
Therefore, a collected foreign refractory is roughly crushed and a foreign matter removing step is performed to remove the attached foreign matter.
Here, first, the collected used refractory 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, foreign substances separated from the used refractory, mainly adhering foreign substances (some foreign substances can be removed) can be separated and removed using, for example, one or both of manual sorting and magnetic sorting machines. To do.

Subsequently, the used refractory from which the adhering foreign matter has been removed is further finely crushed (pulverized), the inserted foreign matter is removed, and then the crushed used refractory (crushed material) is classified. .
Here, in the foreign matter removal step, the used refractory from which the attached foreign matter has been removed is continuously supplied to the crusher, and finely crushed according to the target particle size, and the foreign matter separated by fine crushing, mainly inserted foreign matter Is removed using, for example, a magnetic separator.
In addition, when processing two or more types of used refractories as used refractories, the above-described rough crushing and fine crushing are performed individually for each type of used refractory.
In this way, the used refractories from which the foreign matters have been removed and crushed are roughly classified into a lump and a remainder using, for example, a sieve sorter. 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 constructing a recycled raw material of such a size as an indeterminate refractory, for example, an unfilled portion occurs in a corner portion to be filled, There arises a problem that the recycled material thus constructed is easily peeled off from the joint portion 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, a recycled material containing a water content of 12% by mass is placed in a container, placed upside down so that the recycled material contacts the upper surface of the mounting table, and then removed from the container. 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, a fine classification step is performed in which the remainder classified in the coarse classification step is further classified into a coarse particle and a fine particle 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 coarse classification and subclassification, moisture contained in the used refractory material 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 refractory is 5% by mass or less, desirably 2% by mass or less, and more desirably 1% by mass or less. Examples of this method include means for storing the used refractory in the recovery process indoors, and drying the used refractory immediately before the coarse classification process or the subclassification process with a drying device.

Subsequently, what is not processed by the recycling of the used refractories (region surrounded by the dotted line in FIG. 1), that is, coarse particles and fine particles classified in the subclassification step, are mixed at a predetermined ratio, A raw material manufacturing process for manufacturing recycled refractory raw materials including coarse particles and fine particles is performed.
In the production of this recycled material, the lump obtained by coarse classification is not the main target for recycling. This lump 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 raw 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.

Add to the recycled refractory raw material an unused refractory containing 85% by mass or more of particles having a particle size of 74 μm or less. Recycled refractory material. By adding an unused refractory with such a structure, when constructing as a refractory, in the undried state immediately after construction, the shape freezing property of the construction body is improved and the sinterability during construction is also 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 consists of a particle size-adjusting powder that has a role of adjusting the particle size distribution in order to mainly improve the filling property and fluidity of the recycled material, and a combination that improves the shape freezing property or sinterability of the recycled material. It consists of both a binder (also called a binder) that plays the role of a material, and its particle size of 74 μm is a standard value.

This unused refractory does not exhibit the role of adjusting the particle size distribution and the function as a binder unless it contains 85 mass% or more of particles having a particle size of 74 μm. In the above-mentioned fine crushing (pulverization), the unused refractory was added without crushing the used refractory to 74 μm or less because a special crusher or the like is required for crushing, and productivity This is because the cost is increased due to the low value.
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.

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.
From the above, the amount of the outer refractory added to the outer shell is set to 10% by mass or more and 40% by mass or less of the recycled refractory raw material, but preferably the upper limit is 30% by mass and the lower limit is 20% by mass. To do.
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, and for example, 100% by mass of particles having a particle size of 74 μm or less may be used. Unused refractories may be included.

As described above, it is desirable to add a predetermined amount of the above-mentioned predetermined particle size so that the recycled raw material has a predetermined particle size distribution as described above, but depending on the material species constituting the unused refractory material The function of the amorphous refractory using the produced recycled refractory raw material for the amorphous refractory can be improved. The contents will be described below.
As described above, the unused refractory includes a particle size adjusting powder having a role of adjusting the particle size distribution and a binder functioning as a binder.
The binder is, for example, cement, and has an effect of solidifying due to hydrated 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 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 powder is, for example, purified alumina powder, and has a function of filling gaps between particles of recycled raw materials, and ensures fluidity and shape freezing property. In addition, by filling the gap, when using recycled refractory raw materials for amorphous refractories as amorphous refractories, diffusion bonding between refractory particles is promoted to improve sinterability by heating during use. There is also the effect.
From the above, the binder is added to the recycled refractory raw material by 1% by mass or more, and the upper limit of the binder addition amount is 50% by mass of the amount of unused refractory (that is, the amount of unused refractory added is In the case of 10% by mass, it is appropriate to be 5% by mass or less, and in the case of 40% by mass, 20% by mass or less. Moreover, it is desirable that the particle size adjusting powder is added to the recycled refractory raw material in an amount of 5% by mass or more and 39% by mass or less depending on the addition amount of the binder.

Part or all of the particle size adjusting 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 mass% 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 inventors of the present application 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 applied to part or all of the particle size adjusted 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 powder may be made fly ash.

When mixing the above-mentioned coarse, fine, and unused refractories, it is important to ensure the mechanical strength of the construction body using recycled refractory materials for irregular refractories or the workability of irregular refractories. become. In order to realize these, the filling properties of the recycled refractory raw material for amorphous refractories is important. If there are too many fine particles, the added moisture required for construction increases, and the recycled refractory for amorphous refractories increases. The filling property of the raw material is lowered, and the mechanical strength of the construction body is lowered, or the wear resistance when the actual machine is used 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 present inventors set the water content to a constant value (12% by mass). It was newly found out that the packing property of particles can be generally evaluated by comparing the magnitudes of tap flow values. 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.
In addition, this invention mainly manufactures the recycled refractory raw material for indeterminate refractories using the used refractories normally discarded, and applies this to the site | part which does not require very high durability. Since it is intended, it can be considered that evaluation that can withstand practical use is possible by evaluating the filling properties of recycled raw materials for irregular refractories by the tap flow value.

Here, when the coarse particles and the fine particles are mixed at a predetermined ratio, since the properties differ depending on the type of used refractory, the coarse particles and the fine particles are used in a ratio of 1: 9 to 9: 1. Combination of 9 kinds of blends with increasing coarse particles by 1 and further combination of 4 kinds of blends with increasing coarse particles by 1 from 3.5: 6.5 to 6.5: 3.5 Is experimentally prepared in advance and is 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. .
Moreover, there exists a relationship shown in FIG. 2 between this tap flow value and the apparent porosity and compressive strength of the manufactured refractory. In FIG. 2, the refractory used in the test is 25 masses of outer refractory with a grain size of 74 μm or less and 98 mass% on coarse particles obtained from chamotte and fine particles obtained from lower alumina material. % Added and mixed, and then dried by an electric furnace (110 ° C., 24 hours). The tap flow value was adjusted within a range of 110 to 160 mm by variously changing the mixing ratio of coarse particles and fine particles.
As shown in FIG. 2, when the tap flow value was less than 120 mm, the compressive strength (●) of the refractory material tended to decrease rapidly. This is thought to be due to the increase in porosity (■). In addition, the compressive strength and apparent porosity when the tap flow value is 160 mm or more were not measured, but at least 255 mm, separation of the refractory and water was seen, and it was considered unsuitable for implementation. The upper limit was about 250 mm.

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, coarse particles: fine particles are blended in a range of, for example, 1: 9 to 9: 1, preferably 2: 8 to 8: 2, more preferably 3: 7 to 7: 3. It is good to mix.
When mixing coarse particles and fine particles, if coarse particles and fine particles obtained from the same kind of used refractory are continuously mixed at a predetermined ratio, surplus coarse particles are inevitably generated. This is because during the use of refractories (especially bricks), the raw materials tend to sinter and become hard, and a crushing method that is commonly used (for example, a method of cracking used refractories with a jig, Or, in a method of hitting a used refractory with a jig: for example, a jaw crusher, an impeller breaker, or a ball mill), fine particles are insufficient, and coarse particles are excessive.

Therefore, when producing a recycled raw material by mixing coarse particles and fine particles, a part of the excess coarse particles that are not used in the production (for example, 10% by mass to 50% by mass of the excess coarse particles) The following) or the whole may be sent to the coarse classification step and mixed into the used refractory from which the adhering foreign matter has been removed. As a result, the surplus coarse particles are crushed together with the used refractory in a state of being filled in the gaps between the roughly crushed used refractories, and the amount of fine particles generated can be increased from the current level, and therefore surplus. The amount of coarse particles is reduced, and the effect of suppressing the excess of used refractories can be further increased. Here, the excess coarse particles may be sent to the foreign matter removing step.
Note that it is impossible at this stage to achieve crushing that achieves a particle size distribution with no surplus.

Moreover, when mixing coarse particles and fine particles, coarse particles and fine particles obtained from different types of used refractories may be mixed in a predetermined ratio. In this case, as the used refractory, a brick that tends to generate a lot of coarse particles by crushing and an amorphous refractory that tends to generate a lot of fine particles by crushing are used. By mixing such coarse particles and fine particles to produce a recycled refractory raw material, the effect of suppressing the excess of used refractories can be further increased.
From the above, by using the method for recycling used refractories according to the present invention, the recycled raw material can be adjusted to a particle size distribution suitable for recycling, and the amount of used refractories recycled can be increased more than before. It becomes possible and 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 a part or all of the amorphous refractories used in steelworks. Since the manufactured recycled refractory material for an indeterminate refractory can be filled with increased fluidity, a relatively high strength refractory can be obtained. Moreover, when 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 refractory, the durability against chemical wear can be secured. Thus, the recycled refractory material for amorphous refractories can be used as the raw material for amorphous refractories.
In addition, used refractories tend to be hardened after receiving a thermal history once, and tend to harden. Mechanical wear of amorphous refractories using at least part of the above recycled refractory materials for refractories Since the property is improved, it can be used in a site where a conventional amorphous refractory is applied.
From the above, recycled refractory materials for amorphous refractories can be used for 50% by mass or more (more preferably 70% by mass or more) of amorphous refractories, and the effect of reducing the amount of fine particles discarded is also great. it can.

Next, examples carried out for confirming the effects of the present invention will be described. Normally, as described above, the same type or different types of used refractories are used, and the crushed material is roughly classified and subclassified, and the resulting lump, coarse particle, and fine particle are obtained. After performing the conventional recycling used, the remaining raw refractory coarse particles and fine particles are combined to produce a recycled material (see FIG. 1). However, here, in order to simplify the embodiment, the conventional recycling is not considered, and all the coarse particles and fine particles obtained from the same type or different types of used refractories are targeted. Examine the results of manufacturing recycled materials.
First, after sieving into a lump, a coarse particle, and a fine particle, the result of combining the coarse particle and the fine particle is shown in Table 1.

Example 1 shown in Table 1 uses only a lower alumina material that is an amorphous refractory as the used refractory Y, and Example 2 is an alumina-silica brick as the used refractory X. Only chamotte is used. In Example 3, chamotte is used as the used refractory X for obtaining coarse particles, and a lower alumina material is used as the used refractory Y for obtaining fine particles. And Example 4 uses the high alumina material which is an alumina-silica amorphous refractory as the used refractory X for obtaining a coarse product, and used refractory Y for obtaining a fine product. A lower alumina material is used.
On the other hand, Comparative Examples 1 to 3 use chamotte as the used refractory X for obtaining coarse particles, and use a lower alumina material as the used refractory Y for obtaining fine particles, In Comparative Examples 4 and 5, only chamotte is used.

Here, the lower alumina material is, for example, in the case of wear refractories and perm refractories (different refractory types) in the same pan, and when it is difficult to separate and collect both, they must be mixed and recovered. Of these, a plurality of types containing alumina are collected, and in many cases, an amorphous refractory is mainly used. The lower alumina material used here is alumina: 15-40% by mass, silica: 55-80% by mass, carbon: 1-5% by mass, and other alkali metal oxides (Na ₂ O, K ₂ O). ) Is included.
Moreover, although Examples 1-4 and Comparative Examples 4 and 5 are performing coarse classification and subclassification, Comparative Examples 1 to 3 are not performing coarse classification, and coarse particles are applied on the subclassified sieve. As a product, it is mixed with the fine particles which are sub-classified sieves in the quantitative ratios shown in Table 1.
Further, in Examples 1 to 4 and Comparative Examples 1 to 5, an unused refractory containing 98% by mass of particles having a particle size of 74 μm or less is added to the recycled raw material by 25% by mass.

Examples 1 to 4 shown in Table 1 are the results of mixing coarse particles and fine particles at a ratio of 40 to 60. The fluidity was good and the TF value was good at the 140 mm level. Moreover, when the spraying construction was carried out using the recycled raw material of Example 4, there was no nozzle clogging, and when it was applied to the eaves cover, it could withstand the use.
And the surplus used refractory amount ratio (hereinafter also referred to as surplus amount ratio) shown in Table 1 is the result of excluding the lump, and when Example 3 is used as the standard (1.0), other implementations The surplus amount ratio of the example is about 4.5 or less (the target upper limit value is 5), which can be reduced even when compared with Comparative Examples 1 and 3 to 5, and it was confirmed that the amount of recycling can be increased.

On the other hand, since Comparative Examples 1 to 3 do not perform rough classification (threshold A), a used refractory of 10 mm or more is mixed in the recycled material. Since this recycled material contains fine particles, moisture remained between the particles, and no significant separation of the recycled material and moisture occurred, but a lump (particularly, the particle size was 10 mm). The above) caused the deterioration of fluidity (it did not collapse as a stone wall). For this reason, the TF value was on the order of 110 mm, and a good TF value could not be obtained even when the blending ratio of the coarse particles and fine particles was changed.
Thus, since the TF value of the recycled raw materials of Comparative Examples 1 to 3 was too low, nozzle clogging was likely to occur when spraying was performed, and the workability was poor. Even if casting is performed, the strength is low because the porosity is high, and there is a risk of the aggregate dropping off after the construction. For example, the application is limited to a non-contact portion with the molten metal.
Further, as in Comparative Example 2, depending on the blending ratio of the coarse particles and the fine particles constituting the recycled raw material, the excess amount ratio may be good at about 3.6, but the actual use because the TF value is low. There is a need to limit the use destination.

Comparative Examples 4 and 5 are used in the examples described in Patent Document 1, and used refractories having a particle size range of 10 to 40 mm (a lump as referred to in the present invention) and particle size ranges of 3 to 10 mm (referred to in the present invention). Based on the upper limit and the lower limit of the mixing ratio of the used refractory of the coarse particles), the mixing ratio of the lump and the coarse particles (mixing of recycled raw materials) is 1 to 2 (33 to 67) and 1 to 7 (12.5 vs. 87.5).
In this case, there are many lumps in the recycled material, there is little collapse of the shape of the recycled material on the mounting table, water is separated from the block, and moisture containing fine particles spreads on the mounting table (TF value: 255-271), because it causes separation, it was judged that it could not be used at all for the construction work.
Further, the surplus amount ratio was about 7.3 to 8.1, which was larger than that of the example. This is because when a commonly used crushing method is used, the production ratio of the lump is reduced, and as a result, when the lump is composed mainly of lump, mixing of other than lump (coarse and fine) This is because the amount cannot be increased.

Furthermore, in Patent Document 1, either 1 or 2 of particles of 3 to 10 mm which are unused refractories and particles of 3 mm or less are blended, but in unused refractories and used refractories, However, the quality of the particles after crushing the used refractory is not constant. For this reason, it is necessary to determine the blending ratio of the coarse and fine particles of the used refractory according to the quality.
Unused refractory particles are generally dense and uniform in quality.
Moreover, when crushing a used refractory, the crushed used refractory is often formed in a state in which a plurality of particles are combined, and the surface thereof is porous.
And the quality of the used refractory is non-uniform, such as the heat history received by the used refractory varies depending on the used part of the refractory.
Therefore, even if the unused refractory in Patent Document 1 is simply replaced with a used refractory, the effect of the present invention cannot be obtained.

Next, the results of studying the types of used refractories for obtaining coarse and fine particles will be described with reference to Table 1.
Example 2 shown in Table 1 is a result when the used refractory for obtaining coarse particles and fine particles is of the same type, and in comparison with Example 3 using different types of used refractory, surplus The quantity ratio is increasing. However, both were less than the target of 5, which was good.
The recycled raw materials of Examples 2 and 3 were used as a repair material for the receiving port portion of a topy car, for example, where the usage environment is severe, and sprayed. And after performing the receiving 10 times (10 charges), when the damage state was observed visually, when the recycled raw material of Example 3 was used, there were many cracks and peeling damage, and there was little residue. On the other hand, in Example 2, although some melting damage was observed, the remaining state was good. This is because the lower alumina material originally used in the low temperature region contains an alkali metal oxide, so it has a low melting point. If it is used at a relatively high temperature, the recycled material causes oversintering, and the alkali This is thought to be because the liquid phase was generated by the eutectic reaction between the metal oxide and alumina and the erosion easily progressed, and the long life could not be maintained.

Thus, although the use of the recycled raw material is limited by the constituent components of the used refractory, it can be expanded.
For example, when a high-melting-point material such as magnesia or alumina-magnesia is used as a used refractory, it is possible to utilize a recycled material containing this component as a repair material having excellent resistance to melting at high temperatures. is there.
In addition, as a used refractory, by using a material excellent in slag infiltration resistance such as ASC (alumina-SiC-C), a recycled raw material containing this material can be used at a slag line or other erosion site. It can be used as a repair material with excellent melt resistance.
From the above, amorphous refractories manufactured using coarse and fine particles obtained by sieving have a low porosity and a high compressive strength within the preferred range, so mechanical wear resistance Can be secured. Furthermore, by using the same type of used refractories to obtain coarse particles and fine particles, the surplus ratio will increase within the target range, but chemical wear resistance will be secured if the intended use is selected. it can.
Then, the result of having changed the structure of the unused refractory added to the recycling raw material and its addition amount on the basis of Example 3 is shown in Table 2.

In Examples 3, 5, 6 and Comparative Examples 6 to 8 shown in Table 2, chamotte is used as the used refractory X for obtaining the coarse particles, and the used refractory Y for obtaining the fine particles. A lower alumina material is used.
Moreover, Example 5 is the result of setting the ratio of 74 μm or less of the unused refractory to the lower limit (85% by mass) of the above range, and Example 6 sets the amount of the outer refractory to be added to the above range. It is the result set to the lower limit (10 mass%).
On the other hand, Comparative Example 6 is a result in which the ratio of 74 μm or less of the unused refractory falls below the lower limit of the above range (50% by mass), and Comparative Examples 7 and 8 are the amount of the outer refractory added to the outside. Is a result of lowering the lower limit of the range (5% by mass) and a result of exceeding the upper limit (41% by mass).

In Example 5, since the ratio of 74 μm or less of the unused refractory was reduced as compared with Example 3, the TF value is somewhat reduced, but the porosity is within the appropriate range from the results of FIG. Met. Further, the surplus ratio excluding the lump was also good as in Example 3 because the blending ratio of the coarse particles and fine particles was not changed.
On the other hand, as in Comparative Example 6, when the ratio of 74 μm or less of the unused refractory is excessively decreased, the TF value is lower than the lower limit of the above range, the porosity is increased and the strength is decreased. Damage occurred and nozzles were clogged. There may be no problem depending on the use destination. Further, the surplus amount ratio was the same as that of Example 3 and good because the blending ratio of the coarse particles and the fine particles was not changed.

In Example 6, the amount of unused refractory added to the outer refractory was reduced as compared with Example 3, and the amount of unused refractory having a small particle size was reduced. Has been changed to increase. As a result, the TF value of Example 6 was somewhat lower than that of Example 3, but the porosity was within the appropriate range and was practically usable. In addition, although the surplus amount ratio increased compared with Example 3, it was less than the target 5 and was favorable.
On the other hand, in Comparative Example 7, the amount of unused refractory added to the outside is excessively decreased, and the amount of unused refractory is decreased, so the mixing ratio of coarse particles and fine particles is changed so that the fine particles increase. is doing. As a result, the TF value of Comparative Example 7 was further lowered than that of Example 6, the porosity was increased and the strength was reduced, and nozzle clogging occurred during spraying. In addition, in the casting construction, damage may occur, and in practical use, the usage destination is extremely limited. Although the surplus amount ratio of Comparative Example 7 increased as compared with Example 3, it was less than the target of 5.
In Comparative Example 8, the amount of unused refractory added to the outside is excessively increased, and the amount of unused refractory is increased. Therefore, the blending ratio of coarse particles and fine particles is changed so that the fine particles are reduced. is doing. As a result, the TF value of Comparative Example 8 was about the same as that of Example 6, the porosity was also within an appropriate range, and it was able to withstand practical use (during construction). However, the sinterability tends to be excessive, and cracks may be seen on the construction surface during use. The surplus ratio was less than the target of 5.

As shown above, the TF value changes with the blending ratio of the coarse particles and the fine particles constituting the recycled raw material (Tables 1 and 2 show the ratio of the coarse particles and the coarse particles at which the TF value is considered to be the best). The TF value can also be changed by changing the type of the refractory used to screen the crushed material or the used refractory.
Here, it will be described that the TF value can be controlled by changing the mesh for performing sieving.
First, chamotte and lower alumina materials are used as used refractories. When producing recycled materials from coarse particles obtained from chamotte and fine particles obtained from lower alumina materials, coarse classification and sub-classification screening are performed. Table 3 shows the results obtained by changing the sieve mesh.

In Examples 3, 7, and 8 shown in Table 3, the threshold values A and B of the coarse classification and the fine classification and the ratio (A / B) are the results of the optimum range described above.
On the other hand, Comparative Example 11 is a result in which the threshold B for subclassification exceeded the upper limit of the optimum range (ie, 0.5 ≦ B <3) (4 mm), and Comparative Example 12 was a rough result. This is a result of the threshold A for classification falling below the lower limit of the optimum range (that is, 3 ≦ A ≦ 10) (2 mm). Further, Comparative Examples 9 to 11 are results in which the ratio between the threshold values A and B is out of the optimum range (that is, 2 ≦ (A / B) ≦ 8). In Examples 3, 7, 8, and Comparative Examples 9-12, the unused refractory having the above-described composition is added to the recycled raw material by 25% by mass.
The excess amount ratios of Examples 3, 7, and 8 and Comparative Examples 9 to 12 shown in Table 3 are in the range of 0.3 to 3.1, and can be significantly reduced.
On the other hand, as for the TF value, as in Comparative Examples 9 to 12, 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. By deviating from the above, a tendency of lowering than those of Examples 3, 7, and 8 was observed, and it was expected that the porosity was increased and the compressive strength was lowered, and the actual use destination was limited.
As described above, the TF value can be changed by changing the mesh for performing sieving.

Then, the case where the kind of used refractory is changed is demonstrated.
The types of used refractories for obtaining coarse particles and fine particles constituting the recycled raw materials shown in Table 3 are different. Here, a low-alumina material containing carbon is used for the fine particles, and the fine particles tend to repel water (because of containing carbon, the wettability is low). In this case, it is considered that a water film tends not to be generated around the fine particle, and the fluidity is lowered and the TF value is lowered by the direct contact between the fine particles.
In addition, as a used refractory material for obtaining fine particles, when a material that does not contain carbon, for example, chamotte is applied, the TF value increases. For example, when the fine particles of Comparative Examples 9 to 12 are obtained from chamotte, the TF value is improved to about 120 to 130.
Thus, the TF value can be changed by changing the type of used refractory.
However, if the number of changes in sieve mesh increases, the equipment will be shut down, and if the type of used refractory is limited, the surplus will increase. It is also desirable that the type of used refractory to be recycled is not limited. Therefore, for the control of the TF value, it is preferable to mainly use a change in the blending ratio of coarse particles and fine particles.

Next, the effect of reducing the surplus amount will be described.
As a method of reducing the surplus amount, when producing a recycled raw material by mixing coarse particles and fine particles, a part or all of the excess coarse particles that are not used in the production are sent to the coarse classification process and adhered. There are a method of mixing in a used refractory from which foreign substances have been removed and a method of mixing coarse particles and fine particles obtained from different types of used refractory in a predetermined ratio.
Here, a reflux method for sending surplus coarse particles to the coarse classification step will be described first.
This method is suitable for the case where a recycled material is composed of coarse particles and fine particles obtained from the same type of used refractories in order to ensure chemical resistance to melting. The results are shown in Table 4.

In Examples 2, 9, and 10 shown in Table 4, only chamotte is used as a used refractory, and the threshold values A and B of coarse classification and subclassification, and the ratio (A / B) thereof are optimum as described above. The mixing ratio of coarse particles and fine particles is adjusted to 40:60. In Examples 2, 9, and 10, 25% by mass of the unused refractory having the above-described composition is added to the recycled raw material.
Examples 9 and 10 are the results of including excess coarse particles in an amount of 30% by mass or more and 40% by mass or less when crushing used refractories. Example 2 It is the result of crushing only used refractories.

In Examples 9 and 10 in which the coarse particles are refluxed, the excess amount ratio is reduced from 4.0 to about 1.0 to 1.8 compared to Example 2 in which the coarse particles are not refluxed. I was able to.
In addition, when there is too much surplus coarse grain amount added at the time of crushing a used refractory, since the processing amount of a used refractory reduces relatively, it is unpreferable. According to the knowledge of the present inventors, the effect of increasing the fine particles was sufficient by adding about 50% by mass of the excess coarse particles to the used refractory.
In addition, a fine granule production amount changes about 5-10 mass% by adding 30 mass% or more and 40 mass% or less of excess coarse particles to a used refractory. This is considered to be because, for example, when removing bullion or slag from the used refractory, the degree of crushing varies depending on the adhesion situation, and the particle size composition of the used refractory varies. .
In addition, the amount of excess coarse particles added to the used refractory was confirmed to be an increase in the amount of fine particles after crushing at 10% by mass or more of the total crushed amount (used brick amount + coarse particle amount), The increase in the amount of fine particles can be clearly confirmed when the amount of excess coarse particles to be added is 20% by mass or more, and further 30% by mass or more, as shown in Table 4, about 5 to 10% by mass of fine particles. Increase was confirmed.

Next, referring to Examples 2 to 4 in Table 1 described above, a method of mixing coarse particles and fine particles obtained from different types of used refractories at a predetermined ratio to reduce the excess amount ratio. explain.
Both the coarse particles and fine particles of Example 2 use chamotte, and for the reasons described above, the coarse particles tend to be excessive, so that a good value less than the excess amount ratio of 5 is obtained. Compared to Examples 3 and 4, the surplus amount ratio is large.
On the other hand, the coarse particles and fine particles of Example 3 are obtained from different types of used refractories, that is, the coarse particles are obtained from chamotte and the fine particles are obtained from a lower alumina material. Thus, the excess amount ratio could be reduced to 1.0 by obtaining the fine particles from the lower alumina material in which the fine particles tend to be excessive.

The coarse particles and fine particles of Example 4 are obtained from different types of used refractories, that is, the coarse particles are obtained from a high alumina material, and the fine particles are obtained from a lower alumina material. This high alumina material has a smaller amount of coarse particles than chamotte and more than a lower alumina material.
In general, amorphous refractories produce many fine particles by crushing. However, the high alumina material used in Example 4 has few inserted foreign substances when recovered after use, and requires fine crushing when removing inserted foreign substances. The particle size at the time of crushing before coarse classification is large. For this reason, the amount of coarse particles obtained is greater than that of the lower alumina material.
Thus, by obtaining the coarse particles from the high alumina material having less coarse particles than chamotte, the excess amount of the fine particles of the lower alumina material increased, and the excess amount ratio increased to 1.2. It was confirmed that it could be sufficiently reduced as compared with 2.
This is a result of the fact that the used refractory for obtaining the coarse particles is different from the used refractory for obtaining the fine particles, and that the coarse particles are selected from the used refractories with an excessive basis. is there.

Next, Table 5 shows the results of fly ashing part or all of the particle size-adjusted powder constituting the unused refractory added to the recycled material.

Examples 11 to 15 shown in Table 5 use chamotte and lower alumina materials as used refractories, and thresholds A and B of coarse classification and subclassification, and the ratio (A / B) thereof are as described above. The mixture ratio is set within the optimum range, and the mixing ratio of coarse particles and fine particles is adjusted to 40:60.
In Examples 11 to 15, an unused refractory containing 98% by mass of fine powder having a particle size of 74 μm or less is added to the recycled raw material by 25% by mass. In addition, Examples 11-13 are the results of changing the blending ratio of the binder constituting the unused refractory and the particle size adjusting powder (refined alumina powder), and Example 14 fries all of the particle size adjusting powder. Ashes and Example 15 show the results when a part of the particle size adjusting powder is composed of fly ash (the other particle size adjusting powder is refined alumina powder). The used fly ash contains 3.4% by mass of Fe ₂ O ₃ and is less than 2% by mass in terms of metallic iron in the entire unused refractory.

In Examples 11 to 15, the blending ratio of the coarse particles and the fine particles is the same as that of Example 3, and the particle size and the addition amount of the unused refractory are also the same, so the excess amount ratio and the TF value are substantially the same. Met.
Moreover, Examples 11 and 12 are the results of setting the binder amount to 1% by mass and 10% by mass of the recycled raw material, respectively, and the situation of the refractory after construction was good.
Further, Example 13 is a result of setting the amount of binder added to the recycled raw material to an amount (13% by mass of the recycled raw material) exceeding half of the amount of unused refractory to be added. Here, when the state of the refractory after construction using this recycled material is observed, there may be a case where a fine crack considered to be caused by oversintering may be confirmed. It is preferable to make the amount of the binder less than half of the unused refractory.
As in Examples 14 and 15, part or all of the particle size-adjusted powder was fly ash. As a result, the refractory situation after applying this recycled material was as good as in Example 11.
From the above, by applying the recycling method of the present invention, it has been confirmed that the quality is better than before, the amount of used refractories can be increased, and the amount of waste disposal can be reduced. .

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, when a recycle how some or spent refractory of the present invention by combining all of the respective embodiments and modifications described above are also included in the scope of the present invention.

It is explanatory drawing of the recycling method of the used refractory which concerns on one embodiment of this invention. It is explanatory drawing which shows the relationship between the tap flow value of a recycled refractory raw material, the apparent porosity, and compressive strength of a refractory.

Claims (6)

A coarse classification step of crushing a used refractory and classifying it into a lump and a residue, a subclassification step of further classifying the remainder classified in the coarse classification step into a coarse product and a fine product, and the used refractory A raw material manufacturing process for manufacturing a recycled refractory raw material by mixing the coarse particles and the fine particles at a predetermined ratio,
Unused refractories containing 85% by mass or more of those having a particle size of 74 μm or less are added to the recycled refractory materials by adding 10% to 40% by mass to the recycled refractory material. Recycled refractory raw material,
Moisture is added to the recycled refractory raw material for the irregular refractory and placed in a container, which is placed upside down so that the recycled refractory raw material for the irregular refractory contacts the upper surface of the mounting table. After removing, using the test method for imparting vibration to the mounting table, the amount of water contained in the recycled refractory material for the irregular refractory is 12% by mass, and the irregular refractory before imparting vibration. When the maximum width of the recycled refractory material for materials is 100 mm, the maximum width of the recycled refractory material for the irregular refractory material spread on the mounting table after applying the vibration is in the range of 120 mm to 250 mm. And adjusting the mixing ratio of the coarse particles and the fine particles. 2. The method for recycling used refractories according to claim 1, wherein the used refractories for obtaining the coarse particles and the fine particles are of the same type. The method for recycling used refractories according to claim 1, wherein the used refractories are composed of two or more types, and the used refractories for obtaining the coarse particles and the fine particles are different types. Recycling method of used refractories. The method for recycling used refractories according to claim 3, wherein said used refractories have different types of bricks and irregular refractories, and part or all of said coarse particles are obtained from said bricks, A method for recycling a used refractory, wherein a part or all of the fine particles are obtained from the amorphous refractory. The used refractory recycling method according to any one of claims 1 to 4, wherein the unused refractory includes a binder and a particle size adjusting powder, and the binder is applied to the recycled refractory raw material. 1% by mass or more, and the upper limit of the amount of the binder is 50% by mass of the unused refractory, and the particle size-adjusted powder is 5% by mass or more and 39% by mass on the recycled refractory raw material. A method for recycling used refractories, characterized by adding up to 10%. The used refractory recycling method according to claim 5, wherein a part or all of the particle size-adjusted powder is fly ash.

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