JP6718323B2 - Refractory manufacturing method that reuses used refractories - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a refractory material by reusing a used refractory material generated in a steel factory or the like.

Refractory materials such as refractory bricks and unshaped refractory materials are lined in refining furnaces such as converters and electric furnaces used in steelworks, and incidental equipment such as ladle and gutters. This refractory lining is melted by molten metal or slag, so that it is replaced with a new refractory when the remaining thickness becomes thin. On the other hand, the used refractory generated by refilling is difficult to reuse because slag containing metal etc. adheres to the surface or infiltrates inside, so that it is Most were discarded.

In recent years, it has been required to reuse used refractories in order to effectively use resources and reduce raw material costs, but as mentioned above, used refractories contain slag, and the amount of contamination If the amount is large, the durability of the refractory that is reused from the used refractory is reduced, so it is necessary to select and reuse the used refractory that contains less slag. However, in the past, when trying to select a portion of a used refractory material with a small amount of slag (adhesion, infiltration), most of the work is manual work, which requires a lot of labor and time, and a large amount of used refractory material. It is virtually difficult to process things. In addition, it is not easy to accurately determine the presence or absence and the degree of slag inclusion (adhesion, infiltration) by visual observation.

In patent document 1, after performing primary magnetic force sorting on a used refractory to remove the metal, it is crushed and sieved, and secondary magnetic force sorting is performed for each grain size with a magnetic force larger than the primary magnetic force sorting. The used non-magnetic material is separated into magnetic and non-magnetic materials, and if necessary, the used refractory of the selected non-magnetic material is colored by a color sorter to identify the presence or absence of a slag infiltration layer, and slag infiltration is performed. A method for treating used refractories is shown, in which the layers are separated from those without a layer and those with a slag infiltrated layer.

JP, 2003-88845, A

However, the method of Patent Document 1 has a problem that the equipment cost increases because a special device for magnetic force selection and color selection is required. In addition, it is difficult to accurately sort used refractories with a small amount of slag mixed in, if a sorting process is not performed, such as performing a combination of special high magnetic force sorting and color sorting as shown in Patent Document 1.
Therefore, an object of the present invention is to solve the problems of the conventional techniques as described above, and to manufacture a refractory having stable durability efficiently and inexpensively, using scraps of used refractories as raw materials. To provide a method.

The present inventors have conducted a detailed study to find a technique capable of solving the above problems, and as a result, a refractory manufactured without adding CaO as a refractory raw material Can estimate the amount of slag mixed with its CaO content. Therefore, when manufacturing a refractory using this used refractory as at least a part of the raw material, the slag content is determined using the CaO content of the refractory raw material as an index. It has been found that a refractory material having stable durability can be manufactured by controlling the mixed amount.
The present invention has been made on the basis of such findings, and has the following gist.

[1] In a method for producing a refractory without mixing CaO as a refractory raw material (excluding CaO contained as an unavoidable impurity in the refractory raw material),
A refractory manufactured by not mixing CaO as a refractory raw material (excluding CaO contained in the refractory raw material as an unavoidable impurity), and dismantling scrap of a used refractory is used as a refractory raw material. In manufacturing refractory as at least part of
The CaO content was measured for the dismantled scraps (a ₀ ) obtained by performing the disassembly to remove the adhered foreign matter and the unnecessary material portion, and the CaO content and the mixing ratio of the dismantled scraps (a) in the refractory raw material Based on the above, the dismantling scraps (a ₀ ) are selected from the dismantling scraps (a ₀ ) so as to have a CaO content of 2.5% by mass or less. A method for manufacturing a refractory material that reuses a used refractory material, characterized in that a) is used as a refractory material.
[2] In the manufacturing method of the above-mentioned [1], after disassembling debris (a ₀ ) obtained by carrying out a separate dismantling to remove adhered foreign matters and unnecessary material parts, and crushing the metal by magnetic sorting, Pulverized and then classified to be disassembled scraps (a ₀ ) for each particle size, and the CaO content of the disassembled scraps (a ₀ ) after the crushing or the disassembled scraps (a ₀ ) after the classification was measured. A method for manufacturing a refractory material that reuses a used refractory material, characterized by selecting the dismantled waste material (a) based on the amount and the mixing ratio of the dismantled waste material (a) in the raw material of the refractory material.

[3] A method for producing a refractory without adding CaO as a refractory raw material (excluding CaO contained as an unavoidable impurity in the refractory raw material),
A refractory manufactured by not mixing CaO as a refractory raw material (excluding CaO contained in the refractory raw material as an unavoidable impurity), and dismantling scrap of a used refractory is used as a refractory raw material. In manufacturing refractory as at least part of
The CaO content of the dismantled scraps (a ₀ ) obtained by performing the disassembly to remove the adhered foreign matter and the unnecessary material portion was measured, and based on the CaO content, the CaO content of the refractory product to be manufactured was 2. 5 wt% or less and comprising as to obtain the mixing ratio of the demolition debris in refractory raw material (a _0), spent, which comprises using the demolition debris of the proportion (a ₀₎ as refractory material A method for manufacturing a refractory material by reusing the refractory material.
[4] In the manufacturing method of the above-mentioned [3], after demolition scraps (a ₀ ) obtained by subjecting the disassembled wastes and the unnecessary material portions to the dismantling disintegration are crushed and the metal is removed by magnetic sorting, Pulverized and then classified to be disassembled scraps (a ₀ ) for each particle size, and the CaO content of the disassembled scraps (a ₀ ) after the crushing or the disassembled scraps (a ₀ ) after the classification was measured. A method for manufacturing a refractory material that reuses a used refractory material, characterized in that a blending ratio of demolition scrap (a ₀ ) in the refractory material is obtained based on the amount.

[5] The used refractory material according to any one of the above-mentioned [1] to [4], characterized in that the mixing ratio of the demolition waste (a) in the refractory raw material is 10 to 80% by mass. A method for manufacturing a refractory material that is reused.
[6] In the manufacturing method according to any one of the above [1] to [5], when dismantling debris (a ₀ ) is temporarily placed in a temporary storage space, demolition debris (a ₀ ) is used as (i) or (ii) below. A method for manufacturing a refractory material that reuses used refractory material, which is characterized in that it is temporarily placed and carried out under the conditions described above.
(I) When dismantling debris (a ₀ ) is temporarily placed on the ground in the temporary storage area, and when dismantling debris (a ₀ ) is carried out from the temporary storage area, the dismantling debris portion in contact with the ground remains, Only the dismantled waste (a ₀ ) above it is carried out.
(Ii) in advance, covered with litter consisting of demolition debris of spent refractory to ground temporary field, placed temporarily disassembling debris (a ₀₎ on the litter storage site, demolition debris (a ₀ ) Is removed from the temporary storage area, only the demolition debris (a ₀ ) on the laying material is carried out.

According to the present invention, it is possible to manufacture a refractory having a stable durability by using a scrap of a used refractory as a raw material. In the present invention, since it is only necessary to control the CaO content of the refractory raw material, a large amount of used refractories recovered by performing relatively simple separation disassembly (separation disassembly that removes adhered foreign matter and unnecessary material parts). (Demolition waste) can be easily reused as a refractory raw material, and a refractory having stable durability can be efficiently and inexpensively manufactured. Further, the refractory obtained in the present invention, due to the stabilization of durability, it was difficult to apply the refractory made from the used refractory as a raw material in the past. it can. As a result, the reuse application range and reusable amount of used refractories are increased, waste treatment costs are reduced due to the reduction of waste, and the amount of used refractory used as an inexpensive refractory raw material is reduced. As a result, the manufacturing cost of the refractory material can be reduced.

Graph showing the relationship between CaO content and corrosion resistance (corrosion index) for refractories manufactured by reusing used refractories as raw materials for refractories

The used refractory to be reused is separated and disassembled to remove foreign matter and unnecessary material, but slag that adheres to the surface of the refractory or has entered the gaps such as joints and cracks of the refractory Metals and ingots are inevitably mixed in the collected materials even if they are separated and disassembled. These ingots and slags have a low melting point of 1000 to 1400° C., and since the slag is in a pre-melted state where it is once melted, it causes a decrease in refractory degree when mixed in a large amount in refractory, and a small amount. Even if mixed, there is concern that the corrosion resistance will decrease.

Of the slag mixed in the used refractory, most of the slag with a large amount of metal and iron is removed in the magnetic separation process generally performed in the recycling process, but many slag remains in the refractory as it is. I will end up. Therefore, it is important to control so that the amount of slag mixed is kept low in order to reuse the used refractory as a refractory raw material.
The present inventors considered that slag in used refractory is difficult to detect as a single substance, and therefore some chemical component should be used as an index for management as a refractory raw material used in a large amount.

Main component of general steel slag _CaO, a SiO 2, _Al 2 _{O 3} and iron. Of these components, most of the iron content is removed in the magnetic separation process as described above, so it may be possible to manage with the remaining three main components, but steel slag is produced with different compositions depending on the refining target. In particular, since the difference between the contents of SiO ₂ and Al ₂ O ₃ is large, these two components (SiO ₂ , Al ₂ O ₃ ) are not suitable for controlling the amount of slag mixed. On the other hand, CaO is generally present in the slag in an amount of about 40% by mass, and since the content thereof does not differ greatly depending on the refining target, it is suitable as an index for managing the amount of slag mixed in the used refractory. I knew that.

When a refractory containing CaO as a raw material is reused like a dolomite refractory, it is difficult to determine whether it is refractory-derived CaO or slag-derived CaO. It is difficult to use it as an index to control the amount of refractory slag mixed. On the other hand, general refractory materials such as magnesia carbon refractory, alumina SiC carbon refractory, and alumina refractory do not have CaO added (blended) as a raw material, It only contains about 0.5% by mass of CaO. Therefore, regarding a general refractory material to which CaO is not added as such a raw material, it can be considered that the increase of the CaO component in the recovered used refractory material originates from the inclusion of slag. Therefore, by using the CaO component in the used refractory as an index, it becomes possible to control the quality (mixing of slag) of the recycled raw material.

According to the knowledge of the present inventors, when the CaO content of the refractory produced by reusing the used refractory as a refractory raw material exceeds 2.5% by mass, the slag mixed in the used refractory is present. As a result, the corrosion resistance of the refractory material deteriorates rapidly and stable durability (corrosion resistance) cannot be obtained.
Therefore, in the present invention, the CaO content of the refractory is used as an index, and the refractory is manufactured by controlling the amount of slag mixed so that the CaO content of the manufactured refractory is 2.5 mass% or less. Specifically, in the first production method of the present invention, CaO content such that the CaO content of the manufactured refractory is 2.5% by mass or less based on the measured CaO content of the used refractory. Used refractories (demolition scraps) of the content are selected and used as a refractory raw material. Moreover, in the second manufacturing method of the present invention, the used refractory having a CaO content of 2.5% by mass or less is used, based on the measured CaO content of the used refractory. The compounding ratio of the waste (demolition waste) is determined, and the used refractory (dismantling waste) having this compounding ratio is used as a refractory raw material.

In the present invention, the content of CaO derived from slag is used as a management index for the amount of slag mixed, and therefore it is a premise that a refractory is manufactured without mixing CaO as a refractory raw material. However, it does not prevent inclusion of CaO as an impurity in the refractory raw material. Usually, CaO contained as an impurity in a new refractory raw material (virgin raw material) is about 0.5 mass% at the maximum.
Further, for the same reason, the target of recycling in the present invention is a refractory produced without mixing CaO as a refractory raw material (however, like the above, CaO is unavoidable as an impurity in the refractory raw material. It does not prevent inclusion) and is a used refractory. The present invention manufactures a refractory by using the scraps of such a used refractory as at least a part of the refractory raw material.

Hereinafter, the first manufacturing method of the present invention will be described.
In the first manufacturing method of the present invention, the CaO content is measured with respect to dismantled scrap a ₀ obtained by subjecting used refractory materials to a separated dismantling process for removing adhering foreign matters and unnecessary material portions, and the CaO content and fire resistance are measured. based on the mixing ratio of the demolition debris a in the object raw material, from among dismantled scrap a _0, the demolition debris a of CaO content, such as CaO content of the refractory material produced is 2.5 wt% or less It is selected, and the scraps a are used as a refractory raw material.

In the present invention, demolition debris a ₀ of the spent refractory to be reusable object is usually subjected respect spent refractory, a relatively simple fractionation dismantling for removing extraneous foreign material and unwanted material part obtained It has been done.
Here, the used refractory to be separated and dismantled is the refractory used to come into contact with the slag generated in the steel manufacturing process, and therefore it was mainly lined in vessels such as refining furnaces and ladle. Used refractory (degraded refractory part), but is not limited to this.

In general, heavy machinery is often used to dismantle used refractories in terms of work safety and efficiency. Even when dismantling with a heavy machine, it is possible to relatively easily remove the deposits on the refractory surface and the container upper surface. Furthermore, when there is unnecessary material above the container when it is reused, it is possible to dismantle up to that range.
When a used refractory is subjected to separate dismantling to remove adhered foreign matter and unnecessary material parts, usually the adhered foreign matter is first removed, then the unnecessary material parts are disassembled and removed, and then reused. The refractory to be used is dismantled, and the dismantled scrap a ₀ to be reused is collected.

The separation and disassembly performed in the present invention is intended to remove adhering foreign matters and unnecessary material parts and to collect refractory materials to be reused, and for example, it is lined in a container such as a refining furnace or a ladle. In the case of refractory materials, after removing the adhering foreign matter and unnecessary material parts, the work refractory material on the operating surface and the waste brick or perm refractory material on the back surface are dismantled at the same time, and the entire amount is recovered.
The adhered foreign matter is solidified slag (such as blast furnace slag and slag generated during hot metal pretreatment), pig iron, or a mixture thereof adhered to the surface, cracks, joints, etc. of the refractory. The adhered foreign matter is generally removed by crushing the surface with a large heavy machine such as a pecker. If it cannot be removed by cutting into the joints of the refractory, the refractory may be removed together.

The unnecessary material part is a part that does not need to be recovered as a refractory raw material.For example, a refractory part whose material system is different from that of the refractory to be recovered, or a fireproof product whose quality is significantly different. The thing part etc. are mentioned. In general, in the case of vessels such as refining furnaces and ladles, the walls and floors are constructed with bricks (standard refractory), while the tops of the vessels and hot metal payouts are constructed with irregular refractories. In many cases, this irregular shaped refractory material may be an unnecessary material part. Generally, in the present invention, bricks (standard refractory materials) are often collected as demolition scraps a ₀ , and irregular refractory materials are often removed as unnecessary material portions. In addition, in the upper part of the wall that does not come into contact with the hot metal, a refractory material different from the hot metal contact area is often used (for example, high alumina brick), but such refractory material is an unnecessary material part. In some cases. The dismantling and removal of this unnecessary material part is performed following the above-mentioned removal of adhered foreign substances, using a large heavy machine such as a pecker to dismantle while crushing the target range from the upper end of the container, scrapping scraps with a heavy machine, Invert the container and discharge to the outside.

During this operation, the adhered foreign matter that has been removed or the scraps of the unnecessary material may cover the container surface and create a blind spot, which may result in incomplete removal of the adhered foreign matter. It is desirable to discharge the dismantling scraps later, and more desirably, when the dismantling scraps (adherent foreign substances and unnecessary material parts) are discharged multiple times during removal of adhered foreign materials and dismantling of unnecessary material parts, reuse as refractory raw material It is possible to prevent impurities from being mixed into the demolition waste a ₀ .
In addition, recovery rate of dismantled scrap a ₀ can be obtained by devising a step such as a step at the boundary between the unnecessary work part (unnecessary material part) and the reusable work part (refractory to be reused) so that both do not collapse at the same time during dismantling. Is improved. In addition, unifying all the containers with the same system material (refractory) and collecting all of them also contributes to the improvement of the recovery rate of the demolition waste a ₀ .

After removing the adhering foreign matter and the unnecessary material portion as described above, the refractory to be reused is dismantled to obtain dismantled scrap a ₀ of the used refractory to be reused. The refractory to be reused is usually the refractory of the work part.
If you want to leave the permanent part at the time of disassembly, it is desirable to throw a brick on the back of the work part. The material of the discarded bricks is preferably the same as that of the work part or a material contained as a raw material of the work part so as not to cause any trouble when reused. For example, in the case where the work part is alumina-pyroxene-SiC-carbon brick, the pyrophyllite brick can be used as a raw material. Therefore, if this is used as a waste brick, there is no problem in reuse.

Dismantle scrap a ₀ obtained by dismantling the refractory is discharged from the container and collected. If, during this discharge, other demolition debris, ground dust, and earth and sand (especially the earth and sand on the ground of the steel mill and accumulated dust contain a large amount of CaO derived from slag, and the CaO concentration is high), etc. Since it becomes an impurity of the refractory to be removed, it is preferable that the demolition scrap a ₀ is discharged to a place cured on an iron plate or concrete. In addition, if the disassembly frequency is high, it is desirable to provide a dedicated discharge place.

Next, after crushing the recovered demolition waste a ₀ , the metal that has entered the joints and cracks is removed by magnetic force selection. The metal removal equipment may share the same equipment as other demolition debris and slag, and these may be mixed as impurities during metal removal. For this reason, it is desirable that the metal removal equipment be idled or cleaned to remove the residual material before processing the recovered demolition waste a ₀ . It is also effective to increase the amount to be treated at one time, for example, by installing a temporary storage place for dismantling scraps a ₀ before removing the metal, because it leads to a decrease in the concentration of impurities.

The demolition scrap a ₀ from which the metal has been removed is sent to a raw material processing factory, where it is crushed to a desired particle size and then classified and managed for each particle size to be used as a refractory raw material. When the demolition waste a ₀ has a high water content, a drying step may be added to the raw material treatment. Furthermore, if the dismantling scrap a ₀ is temporarily placed before the raw material treatment and mixed after processing multiple lots of dismantling scrap a ₀ , the dispersion of the material components will be small and the refractory material used as the raw material will have stable stability. Lead to

Before dismantling the metal, after removing the metal, or when temporarily disposing of the dismantling scraps a ₀ at the material processing plant, it is produced when the dust and earth on the ground are mixed in, similar to the place where the dismantling scraps a ₀ are discharged from the container. Since it becomes an impurity of refractory material, it is better to discharge (temporarily store) dismantling scrap a ₀ to a place where it is cured on an iron plate or concrete. In addition, when the dismantling frequency is high, it is desirable to provide a dedicated discharge place (temporary storage place). If iron plates cannot be installed or concrete curing cannot be performed at a series of temporary storage sites, a special temporary storage site is prepared, and dismantling scrap a ₀ is temporarily stored and carried out under the conditions of (i) or (ii) below. It is preferable to prevent impurities from being mixed into the demolition waste a ₀ as a raw material from the ground side.
(I) When dismantling debris a ₀ is temporarily placed on the ground (such as topsoil) in the temporary storage area, and when dismantling debris a ₀ is carried out from the temporary storage area, the dismantling debris portion in contact with the ground remains, Only the dismantled waste a ₀ above it is carried out.
(Ii) A laying material consisting of dismantled scraps of used refractories is laid in advance on the ground (topsoil etc.) of the temporary storage area, and dismantling waste a ₀ is temporarily placed on the laying material of the temporary storage area to dismantle the waste material a. When carrying out ₀ from the temporary storage area, only the demolition waste a ₀ on the flooring material is carried out.

In the present invention, the measurement of the CaO content of the dismantling scrap a ₀ (component analysis) and the selection of the dismantling scrap a (the dismantling scrap as the refractory raw material) based on this can be performed at any stage. That is, the dismantled scraps a ₀ recovered through the separated dismantling are crushed to remove the metal by magnetic sorting, and then crushed to a desired particle size, and then classified to be disassembled scraps by particle size. The CaO content of the demolition debris a ₀ at any stage (for example, before removal of the demolition debris a ₀ of the ingot, after removal of the ingot, after grinding, or classification) The measurement (component analysis) and the disassembly scrap a based on the measurement can be performed.

Among them, from the viewpoint of efficiently and accurately selecting the dismantling scraps a, the dismantling scraps a ₀ after removal of the metal are crushed to a desired particle size, or the dismantling scraps are classified after crushing and classified by particle size. It is preferable to measure the CaO content (component analysis) and sort the dismantled waste a based on the above. In this case, earlier any one or more stages (e.g., pre-bullion removal of demolition debris a _0, after bullion removed, one or more stages of the post-grinding) even dismantling scrap a ₀ The CaO content may be measured, and demolition debris exceeding a predetermined CaO content may be separated and removed from the demolition debris a ₀ . Since the chemical composition analysis of the demolition waste a ₀ is generally performed for raw material management, the cost of the present invention does not increase significantly.

In the present invention, when selecting the dismantling scrap a from the dismantling scrap a ₀ , the blending ratio (or the upper limit of the blending ratio) of the dismantling scrap a in the refractory raw material used for manufacturing is determined in advance, Based on the mixing ratio of the dismantling scrap a and the measured CaO content, the dismantling scrap having a CaO content such that the CaO content of the refractory produced from the dismantling scrap a ₀ is 2.5% by mass or less. The a is selected, and the dismantled waste a is used as a refractory raw material.
In the present invention, the refractory is manufactured by using the dismantling scrap a as all or a part of the refractory raw material. When the refractory is manufactured by using the demolition waste a as a part of the refractory raw material, as the remaining refractory raw material, a novel refractory raw material (virgin raw material) containing no CaO as an additive component is used.

In general, the novel refractory raw material (virgin raw material) not containing CaO as an additive component has a CaO content of 0.5% by mass or less. Therefore, for example, when the mixing ratio of the dismantling waste a is 50 mass% and the rest is the virgin raw material and the CaO of the dismantling waste a is 4.5 mass% or less, the CaO content of the refractory product to be produced is 2 Since it can be 0.5% by mass or less, the dismantling scrap a ₀ having a CaO content of 4.5% by mass or less is selected from the dismantling scrap a ₀ , and the dismantling scrap a is used as a refractory raw material. Moreover, when the mixing ratio of the dismantling waste a is 60 mass% and the rest is a virgin raw material and the CaO of the dismantling waste a is 3.8 mass% or less, the CaO content of the refractory product to be produced is 2.5. Since the content can be made less than or equal to mass %, the disassembly waste a ₀ having a CaO content of 3.8 mass% or less is selected from the disassembly waste a ₀ , and this disassembly waste a is used as a refractory raw material.

There is no particular limitation on the blending ratio of the dismantling scrap a in the refractory raw material, but if it is less than 10% by mass, the reuse ratio of the used refractory will be reduced, while the virgin such as ultrafine powder and clay for molding is required. At least about 20% by mass of the raw material should be mixed, so that it is generally preferable that the disassembly scrap a is mixed in a proportion of 10 to 80% by mass. As described above, in general, the CaO content of the new refractory raw material (virgin raw material) in which CaO is not added as an additive component is 0.5% by mass or less, so the blending ratio of the dismantling waste a is 80% by mass as the upper limit. In that case, if the CaO content of the demolition waste a is 3.0% by mass or less, the CaO content of the refractory product to be manufactured can be 2.5% by mass or less.

If the CaO content of the refractory produced by reusing the used refractory as a refractory raw material exceeds 2.5 mass%, the corrosion resistance of the refractory due to the slag mixed in the used refractory will deteriorate sharply. , Stable durability (corrosion resistance) can not be obtained, but since the dismantling waste a is selected with the CaO content as an index as described above, according to the present invention, the CaO content is 2.5. It is possible to manufacture a refractory having a small amount of slag of less than mass%.

Hereinafter, the second manufacturing method of the present invention will be described.
In the second production method of the present invention, the CaO content is measured with respect to the dismantled scrap a ₀ obtained by subjecting the disassembled waste a ₀ to remove adhered foreign matters and unnecessary material parts, and the fire resistance produced based on this CaO content is measured. such as CaO content of the object is 2.5 wt% or less, determined the proportion of the demolition debris a ₀ in the refractory raw material, used demolition debris a ₀ for this proportion as a refractory material.
In this second manufacturing method, the details of the used refractory to be reused, the method of separating and dismantling, the method of recovering dismantled scrap a ₀ , the method of processing until it is made into a raw material, etc. are the same as those of the present invention described above. This is the same as the first manufacturing method.

In the present invention, the measurement (component analysis) of the CaO content of the demolition waste a ₀ can be performed at any stage. That is, the dismantled scraps a ₀ recovered through the separated dismantling are crushed to remove the metal by magnetic sorting, and then crushed to a desired particle size, and then classified to be disassembled scraps by particle size. The CaO content of the demolition debris a ₀ at any stage (for example, before removal of the demolition debris a ₀ of the ingot, after removal of the ingot, after grinding, or after classification) Measurement (component analysis) can be performed. Among them, it is preferable to measure the CaO content (component analysis) for the crushed demolition waste a ₀ after removing the metal to a desired particle size, or for the crushed particles classified according to particle size.

Based on this CaO content, the compounding ratio of the dismantling scrap a ₀ in the refractory raw material such that the CaO content of the manufactured refractory is 2.5% by mass or less is obtained, and the dismantling scrap of this compounding ratio is obtained. a ₀ is used as a refractory raw material.
Also in the second manufacturing method of the present invention, the refractory is manufactured by using the dismantling waste a as the whole or a part of the refractory raw material. When the refractory is manufactured by using the demolition waste a as a part of the refractory raw material, as the remaining refractory raw material, a novel refractory raw material (virgin raw material) containing no CaO as an additive component is used. The mixing ratio of the demolition waste a in the refractory raw material is the same as that of the first manufacturing method described above.

In general, the novel refractory raw material (virgin raw material) not containing CaO as an additive component has a CaO content of 0.5% by mass or less. Therefore, for example, when the CaO content of the dismantling waste a is 4.5% by mass, if the mixing ratio of the dismantling waste a is 50% by mass or less and the rest is the virgin raw material, the CaO content of the refractory to be manufactured is Since the content can be 2.5% by mass or less, the demolition waste a is used as a refractory raw material in such a mixing ratio. When the CaO content of the demolition waste a is 3.8% by mass, the CaO content of the refractory to be produced is 2. If the mixing ratio of the demolition debris a is 60% by mass or less and the rest is the virgin raw material. Since it can be 5% by mass or less, the scrap a is used as a refractory raw material in such a mixing ratio.

If the CaO content of the refractory produced by reusing the used refractory as a refractory raw material exceeds 2.5 mass%, the corrosion resistance of the refractory due to the slag mixed in the used refractory will deteriorate sharply. However, stable durability (corrosion resistance) cannot be obtained, but the mixing ratio of the dismantling waste a is determined by the CaO content as an index as described above. Therefore, according to the present invention, the CaO content is A refractory containing less than 2.5 mass% of slag can be manufactured.

Refractory produced from dismantling scrap a as a raw material as described above is stable compared to refractory produced only from new refractory raw material (virgin raw material), with reduced service life within a range that does not hinder use. The durability can be demonstrated. This refractory can be applied to the same parts and equipment as before reuse, where it was difficult to apply the refractory using the used refractory as a raw material due to stabilization of durability. As a result, the reuse application range and reusable amount of used refractories are increased, the waste treatment cost is reduced due to the reduction of waste, and the amount of used refractory used as an inexpensive refractory raw material is reduced. By increasing the number, the refractory manufacturing cost can be reduced. Further, this refractory is usually used as a fixed refractory such as unfired brick, but it can also be used as an irregular refractory.

Used refractories generated during repair of hot metal containers used in steel mills were reused as refractory raw materials. Alumina-pyroxene-SiC-carbon brick is used for the work part of the hot metal container, and pyroxene brick is used for the permanent part and the waste brick. An Almag castable is installed on the upper part of the hot metal container. When the hot metal container was repaired, it was separated and disassembled. First, the adhered foreign matter was broken with a heavy machine, and then the castable upper part (unnecessary material part) was disassembled. After these pieces of demolition waste were discharged, the rest of the work piece and the discarded bricks were dismantled at the same time, and the demolition waste a ₀ was discharged to the ground of the iron plate and collected. The recovered demolition debris a ₀ is reused as a refractory raw material and is hereinafter referred to as “recovered demolition debris a ₀ ”.

The recovered demolition waste a ₀ was crushed to a particle size of about 40 mm or less, and after the metal was removed by a magnetic separator, it was temporarily placed directly on the topsoil at two adjacent temporary storage sites. When carrying out the recovered demolition scraps a ₀ from these two temporary storage sites, at one temporary storage site, as a measure to prevent contamination of impurities, the recovered demolition waste parts (collecting a thickness of about 200 mm from the surface soil surface) Dismantled waste) is left so that only the collected dismantled waste a ₀ is carried out (in the case of “measures for preventing contamination of impurities: Yes” in Table 1), and in the other temporary storage area, all of the recovered soil is recovered. Dismantled waste a ₀ was carried out (in the case of “Measures to prevent impurity contamination: None” in Table 1).
Since it was used for a comparative example, demolition debris that had not been separately disassembled was also collected. This was stored after being crushed to a particle size of about 40 mm or less by a cone crusher for the purpose of being used for civil engineering work and removing the metal by a magnetic separator.

After the recovered dismantled scraps a ₀ (including the dismantled scraps collected for use in the comparative example) was dried, it was crushed to a maximum particle size of 3 mm or less using a jaw crusher and a disc mill. The recovered demolition waste a ₀ after crushing was respectively shrunk, and samples were collected and then classified with a predetermined sieve mesh.
The chemical components of the sample collected from the recovered demolition waste a ₀ were analyzed to determine the CaO content. In the present invention example, the CaO content and the compounding ratio of the demolition debris a in the refractory raw material (30 mass%, 50 Mass%, 70% by mass), dismantling scrap a having a CaO content such that the CaO content of the manufactured refractory is 2.5% by mass or less is selected, and this dismantling scrap a is used as a refractory raw material. Using.

The blending ratio of the dismantling scrap a in the refractory raw material was set to 30% by mass, 50% by mass, and 70% by mass, and the dismantling scrap a was blended with a new refractory raw material (virgin raw material) to newly prepare alumina-fused stone- A SiC-carbon unfired brick was produced. At this time, a brick was manufactured aiming at 50% by mass of alumina (Al ₂ O ₃ ) and 30% by mass of silica (SiO ₂ ), which are composition values of the brick using only the virgin raw material as the comparative material. The new refractory raw materials used band shale as the alumina source and pyrophyllite as the silica source. Further, graphite and SiC were used to make up for the insufficient amount brought in from the dismantling waste a.

The heat spalling resistance and corrosion resistance of each manufactured brick were evaluated as follows.
In the heat spalling resistance evaluation test, each brick sample was placed in a horizontal electric furnace heated to 1500° C. in an argon gas atmosphere, and after the furnace atmospheric temperature was restored to 1500° C., the sample was held for 15 minutes. Then, the cycle of immersing the sample in cold water kept at 15° C. was repeated 10 times. The evaluation was performed by observing the state of crack generation during the test, but no crack was observed in any of the samples during 10 repetitions, and no difference was observed.

For the evaluation of corrosion resistance, an erosion test using a rotating drum tester was performed. For the erosion test, a synthetic slag prepared so that the ratio of CaO and SiO ₂ was 2.2 was used. Further, the slag was blended so that the total content of FeO and MnO was 17% by mass. The erosion test was carried out by heating the sample lined in the rotary drum tester with a burner while rotating it, and after reaching a test temperature of 1500° C., adding synthetic slag and holding for 3 hours. For the evaluation, the change in thickness of the sample before and after the test was measured, and the erosion index was used, where the change in thickness of the brick using only the virgin raw material as the comparative material was 100. The test was performed twice for each sample, and the erosion index was calculated from the average value. The test results are shown in Table 1 together with the brick manufacturing conditions.

FIG. 1 summarizes the relationship between the CaO content and the corrosion resistance (corrosion index) of the bricks manufactured in this example, and when the CaO content in the bricks exceeds 2.5% by mass, the relationship between the CaO content and the corrosion resistance is rapidly increased. On the other hand, while the erosion index becomes high and the corrosion resistance is remarkably deteriorated, when the CaO content in the brick is 2.5% by mass or less, good corrosion resistance is obtained.
Further, from the comparison between Comparative Example 1 and Example 1 of the present invention, the comparison between Comparative Example 2 and Example 2 of the present invention, and the comparison between Comparative Example 3 and Example 3 of the present invention, by carrying out separation and demolition, recovered demolition waste It can be seen that the CaO content in the inside can be lowered. Further, measures for preventing contamination of impurities are taken from the comparison between Inventive Example 1 and Inventive Example 4, the Inventive Example 2 and Inventive Example 5, and the Inventive Example 3 and Inventive Example 6. Thus, it can be seen that the CaO content can be further reduced.
From the above test results, when using the recovered demolition scraps obtained by fractional dismantling as the refractory raw material, the CaO content of the refractory raw material is controlled under the conditions such that the CaO content is 2.5% by mass or less. It can be seen that, by producing the unfired brick, it is possible to produce the unfired brick which has good heat spalling resistance and stable durability (corrosion resistance).

Claims (6)

In a method for producing a refractory without adding CaO as a refractory raw material (excluding CaO contained as an unavoidable impurity in the refractory raw material),
A refractory manufactured by not mixing CaO as a refractory raw material (excluding CaO contained in the refractory raw material as an unavoidable impurity), and dismantling scrap of a used refractory is used as a refractory raw material. In manufacturing refractory as at least part of
The CaO content was measured for the dismantled scraps (a ₀ ) obtained by performing the disassembly to remove the adhered foreign matter and the unnecessary material portion, and the CaO content and the mixing ratio of the dismantled scraps (a) in the refractory raw material Based on the above, the dismantling scraps (a ₀ ) are selected from the dismantling scraps (a ₀ ) so as to have a CaO content of 2.5% by mass or less. A method for manufacturing a refractory material that reuses a used refractory material, characterized in that a) is used as a refractory material. Dismantled scraps (a ₀ ) obtained by performing a separate dismantling to remove adhered foreign matters and unnecessary material parts are crushed to remove the metal by magnetic sorting, and then crushed and then classified to be disassembled scraps by particle size (A ₀ ),
Wherein the demolition waste after pulverization (a ₀₎ or demolition debris after the classification (a ₀₎ to measure the content of CaO, based on the proportion of the demolition debris (a) in the CaO content and refractory raw material The method for manufacturing a refractory material that reuses the used refractory material according to claim 1, wherein the dismantling waste (a) is selected. In a method for producing a refractory without adding CaO as a refractory raw material (excluding CaO contained as an unavoidable impurity in the refractory raw material),
A refractory manufactured by not mixing CaO as a refractory raw material (excluding CaO contained in the refractory raw material as an unavoidable impurity), and dismantling scrap of a used refractory is used as a refractory raw material. In manufacturing refractory as at least part of
The CaO content of the dismantled scraps (a ₀ ) obtained by performing the disassembly to remove the adhered foreign matter and the unnecessary material portion was measured, and based on the CaO content, the CaO content of the refractory product to be manufactured was 2. 5 wt% or less and comprising as to obtain the mixing ratio of the demolition debris in refractory raw material (a _0), spent, which comprises using the demolition debris of the proportion (a ₀₎ as refractory material A method for manufacturing a refractory material by reusing the refractory material. Dismantled scraps (a ₀ ) obtained by performing a separate dismantling to remove adhered foreign matters and unnecessary material parts are crushed to remove the metal by magnetic sorting, and then crushed and then classified to be disassembled scraps by particle size (A ₀ ),
The demolition debris after pulverization (a ₀₎ or demolition debris after the classification for (a ₀₎ to measure the content of CaO, based on the CaO content, blending of demolition debris in refractory raw material (a ₀₎ The method for producing a refractory material by reusing the used refractory material according to claim 3, wherein a ratio is obtained. The refractory material made by recycling the used refractory material according to any one of claims 1 to 4, characterized in that the blending ratio of the dismantling waste (a) in the refractory material is 10 to 80% by mass. Method. When the dismantling debris (a ₀ ) is temporarily placed in the temporary storage area, the dismantling debris (a ₀ ) is temporarily placed and carried out under the following condition (i) or (ii). A method for manufacturing a refractory material by reusing the used refractory material according to any one of the claims.
(I) When dismantling debris (a ₀ ) is temporarily placed on the ground in the temporary storage area, and when dismantling debris (a ₀ ) is carried out from the temporary storage area, the dismantling debris portion in contact with the ground remains, Only the dismantled waste (a ₀ ) above it is carried out.
(Ii) in advance, covered with litter consisting of demolition debris of spent refractory to ground temporary field, placed temporarily disassembling debris (a ₀₎ on the litter storage site, demolition debris (a ₀ ) Is removed from the temporary storage area, only the demolition debris (a ₀ ) on the laying material is carried out.

Images