JP7216462B2 - Slag fine aggregate used for spraying mortar, spraying mortar using the same, and method for producing slag fine aggregate used for spraying mortar - Google Patents

Description

TECHNICAL FIELD The present invention relates to slag fine aggregate used for spraying mortar produced from steelmaking slag produced in a steelmaking process, spraying mortar using the slag fine aggregate, and a method for producing slag fine aggregate for spraying mortar.

In general, mortar is sprayed on slopes or slopes for the purpose of preventing events such as landslides. Conventionally, natural sand such as sea sand, mountain sand, or crushed sand produced by processing crushed stone has been used as a fine aggregate mixed with mortar. However, the extraction of natural sand, especially sea sand, is being banned. For this reason, the cost of using natural sand is increasing due to imports and transportation from distant places. In addition, continued use of these natural sands leads to destruction of the natural environment. In response to this situation, the development of substitute materials for natural sand is underway. For example, as shown in Patent Literatures 1 and 2 below, the utilization of waste molten slag, steel slag, and the like as alternative materials has been studied.

JP-A-2005-67938 JP 2017-222534 A

When I tried to apply steel slag to the mortar for spraying, the following problems arose. That is, when mortar containing steel slag as a material is sprayed onto an object such as a slope or a slope frame, much of the mortar rebounds (rebounds) on the surface of the object. The rebounded mortar must be disposed of as industrial waste, and it is desired to reduce the rebound amount of mortar.

The present invention has been made to solve the above problems, and its object is to reduce the rebound amount of mortar when spraying mortar, and to use it for slag fine aggregate used for spraying mortar. It is an object of the present invention to provide a method for producing mortar for spraying and slag fine aggregate used for mortar for spraying.

The slag fine aggregate used in the mortar for spraying according to the present invention is produced from steelmaking slag and consists of sandy slag having a particle size in the range of 0 mm to 3 mm.

Further, the spray mortar using slag fine aggregate used for the spray mortar according to the present invention is obtained by kneading the above-mentioned slag fine aggregate, cement and water.

Further, the method for producing slag fine aggregate used in the mortar for spraying according to the present invention includes a steelmaking process for obtaining molten steelmaking slag, and a cooling solidification process for cooling and solidifying the molten steelmaking slag obtained in the steelmaking process. and, after the cooling and solidification step, the steelmaking slag is crushed, beneficiated, and classified to obtain sandy slag having a particle size of greater than 0 mm and less than or equal to 3 mm.

According to the fine slag aggregate used for the mortar for spraying of the present invention, the mortar for spraying using the same, and the method for producing the fine slag aggregate for use in the mortar for spraying of the present invention, grains of sandy slag constituting the fine slag aggregate Since the diameter is in the range of 0 mm or more and 3 mm or less, it is possible to reduce the rebound amount of the mortar when the mortar is sprayed.

1 is a flow chart showing a method of manufacturing slag fine aggregate used for spraying mortar according to an embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated with reference to drawings. The present invention is not limited to each embodiment, and can be embodied by modifying the constituent elements without departing from the scope of the invention. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in each embodiment. For example, some components may be deleted from all the components shown in the embodiments. Furthermore, components of different embodiments may be combined as appropriate.

FIG. 1 is a flow chart showing a method of manufacturing slag fine aggregate used for spraying mortar according to an embodiment of the present invention. The slag fine aggregate manufactured by the method of FIG. 1 is used as a material for spray mortar. A spray mortar means a mortar used for spraying an object such as a slope or a slope frame.

The slag fine aggregate of this embodiment is produced by the method shown in FIG. As shown in FIG. 1, the method for producing slag fine aggregate according to the embodiment of the present invention includes a steelmaking process (step S1), a cooling solidification process (step S2) and a sanding process (step S3). is The sanding process (step S3) includes a crushing process (step S3-1), a beneficiation process (step S3-2) and a classification process (step S3-3).

The steelmaking process (step S1) is a process of obtaining molten steelmaking slag. Steelmaking slag means slag produced in the steelmaking process. For example, in the stainless steel manufacturing process, it refers to slag generated when stainless steel is melted. This slag consists of smelting slag generated in the melting process of melting raw materials in an electric furnace to generate stainless steel hot metal, and desulfurization slag generated in the desulfurization process of removing sulfur contained in the generated hot metal. , Refining slag generated in the refining process for removing carbon contained in hot metal after desulfurization treatment in a converter and a vacuum degassing device. This slag also includes impurities in the raw material, products in the steelmaking process, and ingots of useful metals.

In the above stainless steel steelmaking process, as a desulfurization treatment method for hot metal, a desulfurizing agent is added while the hot metal is stirred with a mechanically driven stirring blade, thereby removing sulfur contained in the hot metal by slagging it. The KR method can be used. In the KR method, stirring accelerates the desulfurization reaction between the hot metal and the desulfurizing agent, so a desulfurizing agent containing CaO (quicklime, calcium oxide) as a main component can be used. Therefore, CaF ₂ (fluorite, calcium fluoride), which is known to be useful for promoting the desulfurization reaction, may not be used.

Steelmaking slag contains F, CaO _{, SiO2} and _Al2O3 .
The F content in the steelmaking slag must be more than 0% by mass and less than 0.4% by mass in order to satisfy the criteria for the amount of F eluted into water stipulated in the soil environment standards. In the present invention, since it is not necessary to use fluorite for the desulfurization treatment, the F content in the steelmaking slag can be reduced. Therefore, the F content in slag fine aggregate produced from steelmaking slag can also be reduced, and even mortar containing slag fine aggregate can satisfy soil environmental standards.

CaO is the main component of the desulfurization agent and an essential component for the desulfurization reaction. Therefore, the content of CaO in steelmaking slag must be 35% by mass or more. On the other hand, if the content of CaO in the steelmaking slag becomes excessive, the basicity (CaO/SiO ₂ ) becomes too high, the fluidity of the slag is lowered, and the desulfurization reaction is not promoted. Therefore, the content of CaO in steelmaking slag must be 65% by mass or less.

SiO ₂ is generated from the raw material of stainless steel or as a deoxidation reaction product by a reducing agent. The content of SiO ₂ in steelmaking slag must be 20% by mass or more and 55% by mass or less from the viewpoint of efficient desulfurization of hot metal of stainless steel. If the SiO ₂ content is less than 20% by mass, the basicity becomes too high during the desulfurization treatment, and the desulfurization reaction cannot be accelerated. On the other hand, when the content of SiO ₂ exceeds 55% by mass, the basicity becomes too low during the desulfurization treatment, and a sufficient desulfurization reaction cannot be obtained.

Al ₂ O ₃ is an essential component for ensuring the fluidity of steelmaking slag. Al ₂ O ₃ is also mixed in from raw materials of refractory bricks and stainless steel used in steelmaking. The content of Al ₂ O ₃ in the steelmaking slag should be 1% by mass or more and 15% by mass or less from the viewpoint of ensuring fluidity of the steelmaking slag. If the content of Al ₂ O ₃ is less than 1% by mass or more than 15% by mass, the melting point of the steelmaking slag increases and the fluidity of the steelmaking slag decreases.

The steelmaking slag may further contain components such as MgO _{, Fe2O3 ,} MnO and _Cr2O3 in addition to the above components. The content of these components in the steelmaking slag is not particularly limited.
The basicity (CaO/SiO ₂ ) of steelmaking slag has a great effect on the desulfurization reaction of hot metal. In particular, when the mechanical stirring KR method is used as the desulfurization method and fluorite, which has been used to improve the fluidity of the slag, is not used, the basicity of the steelmaking slag is adjusted to improve the fluidity of the steelmaking slag. must be ensured. Therefore, the basicity of steelmaking slag should be 0.7 or more and 1.7 or less. If the basicity of the steelmaking slag is less than 0.7, a sufficient desulfurization reaction will not occur between CaO contained in the steelmaking slag and S contained in the hot metal during the desulfurization treatment. On the other hand, if the basicity of the steelmaking slag exceeds 1.7, the fluidity of the steelmaking slag becomes low during the desulfurization treatment, and the contact interface between the hot metal and the steelmaking slag decreases, making it impossible to promote the desulfurization reaction.

The composition of steelmaking slag is based on empirical rules regarding the mixing ratio of raw materials and the distribution ratio of elements between slag and stainless steel. The composition and basicity can be controlled by

The cooling and solidification step (step S2) is a step of cooling and solidifying the molten steelmaking slag obtained in the steelmaking step (step S1). The method for cooling and solidifying molten steelmaking slag is not particularly limited, and any method known in the art can be used. For example, molten steelmaking slag is placed in a slag ladle and cooled for 24 hours or more by a cooling method that combines air cooling by natural cooling in the atmosphere and water spray cooling in which water is sprayed on the slag ladle. be. In the cooling process of the steelmaking slag, the steelmaking slag is put into the slag pot, and the temperature rises from about 1100°C at which solidification starts to about 700°C at which the change in the crystal structure of γ-2CaO SiO (that is, phase transformation) is almost completed. It is preferable to slow cool down at a rate of 1.0° C./min or less until the temperature drops (ie between about 1100° C. and about 700° C.). When the temperature of the steelmaking slag is about 700°C or higher, for example, by increasing the amount of water sprayed or by directly spraying water on the steelmaking slag, the steelmaking slag is cooled and solidified at a rate exceeding 1.0°C/min. A slag with low internal density and brittleness may later be obtained. In order to sufficiently cool and solidify the steelmaking slag so that it can be sufficiently crushed in the next crushing process, the steelmaking slag must be cooled for 28 to 30 hours or longer depending on the outside temperature. preferably.

When the steelmaking slag is cooled and solidified at the cooling rate as described above, free lime (f-CaO), free magnesia (f-MgO), γ-2CaO, which are contained in the steelmaking slag and can cause a hydration reaction. A soft portion containing SiO or the like and a high-density hard mineral phase (made of SiO ₂ , Al ₂ O ₃ , etc.) separate from each other and different phases are formed. In the cooling process, the soft portion containing γ-2CaO.SiO and the like pulverizes due to volume expansion due to changes in the crystal structure of γ-2CaO.SiO and the like. In addition, when the cooled and solidified steelmaking slag is subjected to a wet crushing treatment, which will be described later, the soft parts between the hard mineral phases are finely crushed, and many of the hard mineral phases are separated from each other and become lumps. Furthermore, when this massive mineral phase is crushed, it becomes granular. Therefore, in the treatment, the soft part is mainly pulverized, and the hard mineral phase is difficult to pulverize. ) can be separated and recovered.

The crushing step (step S3-1) is a step of crushing the steelmaking slag that has been cooled and solidified in the cooling and solidifying step (step S2). The method for crushing the cooled and solidified steelmaking slag is not particularly limited, and any method known in the art can be used. For example, the cooled and solidified steelmaking slag may be crushed with a jaw crusher and then crushed with a rod mill.

In the jaw crusher crushing process, the steelmaking slag is sandwiched and pressed while in the air between fixed teeth in the jaw crusher and movable teeth that move toward and away from the fixed teeth. Compressed and crushed. Steelmaking slag is roughly dry-crushed by this process. At this time, in the steelmaking slag, the soft portions between the hard mineral phases collapse, thereby separating the hard mineral phases into a large number of lumps.

In the rod mill crushing treatment, the steelmaking slag is put into a rod mill containing water inside, is immersed in water, and is further finely wet crushed by rotating the rod mill. In the wet crushing process, the soft parts contained in the steelmaking slag become more brittle due to hydration reaction, crushed into fine powder and suspended in water. The soft portion crushed into fine powder in this way is hereinafter referred to as "fine powder". On the other hand, massive hard mineral phases are crushed into granules in rod mills. The hard mineral phase crushed into granules in this way is hereinafter referred to as "particulate fraction".

In addition, the above-described crushing treatment separates the base metal contained in the steelmaking slag from the particulate matter together with the soft portion. At this time, if the steelmaking slag is sufficiently solidified by cooling, the base metal can be easily separated during the crushing process.

The beneficiation step (step S3-2) is a step of beneficiation of the beneficiation slag crushed in the crushing step (step S3-1). The method for beneficiation of steelmaking slag is not particularly limited, and any method known in the art can be used. For example, steelmaking slag that has been crushed may be subjected to specific gravity beneficiation and magnetic beneficiation. In the specific gravity beneficiation process, steelmaking slag is put into the treated water, and sorting can be performed using the difference in specific gravity of minerals with a specific gravity sorter. The steelmaking slag selected by the specific gravity beneficiation process as having a high specific gravity is subsequently subjected to a magnetic beneficiation process. In the magnetic separation process, metals can be separated and recovered from high specific gravity steelmaking slag containing metals by a magnetic separator.

The classification step (step S3-3) is a step of classifying steelmaking slag selected as having a low specific gravity in the beneficiation step (step S3-2). Although the classification treatment is not particularly limited, a sieve classification treatment can be used. In the sieve classification process, low-specific-gravity steelmaking slag taken out from the gravity sorter and contained in the treated water is supplied onto the vibrating screen (sieve) of the vibrating sieve, and the size of the screen opening is Those with a height (eg, 3 mm) or less are sorted out. As a result, slag fine aggregate consisting of sand-like slag having a particle size of greater than 0 mm and less than or equal to 3 mm is obtained. The steelmaking slag having a particle size of more than 3 mm that does not pass through the screen is returned to the rod mill crushing treatment together with the treated water, and subjected to wet crushing treatment.

The slag fine aggregate composed of sandy slag produced as described above has substantially the same composition and basicity as the steelmaking slag used as the raw material. That is, the slag fine aggregate contains more than 0% by mass and less than 0.4% by mass of F, 35% by mass or more and 65% by mass or less of CaO, 20% by mass or more and 55% by mass or less of SiO ₂ and 1% by mass or more It also contains 15% by mass or less of Al ₂ O ₃ and has a basicity (CaO/SiO ₂ ) of 0.7 or more and 1.7 or less.

The slag fine aggregate of the present invention is mixed with cement and water to form a spray mortar. Cement is not particularly limited, and those known in the art can be used. Examples of cement that can be used include various Portland cements such as normal, high early strength, super high early strength, low heat, moderate heat, mixed cement, and ecocement.

The water/cement ratio (weight ratio of water to cement) during kneading is not particularly limited, but is 55% or more and 62% or less as an appropriate amount for the slag fine aggregate of the present invention. If the water/cement ratio is less than 55%, the mortar becomes hard and the pumping becomes unstable. On the other hand, if the water/cement ratio exceeds 62%, the strength of the mortar will be insufficient.

Also, the cement unit amount during kneading is not particularly limited, but is 300 kg/m ³ or more and 410 kg/m ³ or less as an appropriate amount for the slag fine aggregate of the present invention. If the cement unit amount ratio is less than 300 kg/m ³ , the strength of the mortar will be insufficient. On the other hand, if the cement unit amount ratio exceeds 410 kg/m ³ , the mortar will become hard and pumping will become unstable.

Furthermore, the slag fine aggregate/cement ratio (weight ratio of slag fine aggregate to cement) during kneading is not particularly limited, but is generally 5.0 or more and 6.8 or less. If the slag fine aggregate/cement ratio is less than 5.0, pumping becomes unstable. On the other hand, when the slag fine aggregate/cement ratio exceeds 6.8, the strength of the mortar becomes insufficient.

The mortar for spraying can further contain known additives in addition to the above components within a range that does not impair the effects of the present invention. Examples of known additives include water reducing agents, antifoaming agents, thickening agents, rust inhibitors, low shrinkage agents, expanding agents, dispersing agents and the like. Moreover, when using a spray mortar in a place where there is a risk of freezing, a commercially available AE agent may be added to the spray mortar to adjust the amount of air.

The mortar for spraying can be produced according to methods known in the art. Specifically, water and slag fine aggregate may be added to cement and mixed. The mixing method is not particularly limited, and may be mixed using a known mixing device in the technical field.

EXAMPLES The present invention will be described in detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these.
(slag fine aggregate)
In the steelmaking process of stainless steel, hot metal was desulfurized by the KR method using a desulfurizing agent containing CaO as a main component. The molten steelmaking slag generated in this steelmaking process was collected in a slag ladle. The molten steelmaking slag contains 0.2 wt% F, 38.7 wt% CaO, 27.3 wt% _{SiO2 ,} 8.7 wt% _Al2O3 and 9.4 wt% MgO. , 3.4% Fe ₂ O ₃ , 2.3% MnO, 3.3% Cr ₂ O ₃ and a basicity (CaO/SiO 2 ) of 1.4. Next, the molten steelmaking slag placed in the slag ladle is cooled to a temperature of about 1100° C. to about 700° C. by a cooling method that combines air cooling by natural cooling in the atmosphere and water spray cooling by spraying water on the slag pot. C. over 7.8 hours at a rate of 0.8.degree. C./min or less, and further cooled from 700.degree.

Next, the cooled and solidified steelmaking slag was crushed with a jaw crusher and then crushed with a rod mill. Next, after the pulverized steelmaking slag is subjected to specific gravity beneficiation treatment, the steelmaking slag selected as having high specific gravity is subjected to magnetic beneficiation treatment to separate and recover the base metal, and is treated as having low specific gravity. The sorted steelmaking slag is subjected to a sieve classification process using a screen with an opening size of 3 mm, and sandy slag (sandy slag A) having a particle size larger than 0mm and within a range of 3mm or less is selected. Obtained. In addition, as a comparative example, a sieve classification process was performed using a screen with an opening size of 5 mm to obtain sand-like slag (sand-like slag B) having a particle size in the range of greater than 0 mm and 5 mm or less. .

(Influence of fine aggregate particle size)
The sandy slag A obtained in the example (having a particle size in the range of 0 mm or more and 3 mm or less) and water were added to ordinary Portland cement and kneaded to obtain Test No. 1 shown in Table 1 below. Spray mortars 1 to 5 were prepared. As a comparative example, sandy slag B (with a particle size of greater than 0 mm and no greater than 5 mm) or crushed sand (with a particle size of greater than 0 mm and no greater than 5 mm) obtained in Examples and water were treated with ordinary Portland cement. Test No. shown in Table 1 below was obtained by kneading in addition to the toner. 6 and 7 spray mortars were prepared. Table 1 shows the blending amount and ratio of each component. The crushed sand used had a water absorption of 0.86% and an absolute dry density of 2.69 g/cm ³ . Test no. The blending amount of Test No. 6, etc. It is the same as the blending amount of 1. Test no. The compounding amount of Test No. 7, etc. It is the same as the compounding amount of 4.

These test nos. The mortar for spraying No. 1 to 7 was sprayed onto an object such as a slope or a slope frame, and the rebound rate (%) was measured. Table 1 shows the results. In addition, the rebound rate (%) was measured by laying a blue sheet directly under the construction surface of the slope, spraying 250 kg / batch of 2 batches of mortar on the construction surface of the slope with a total of 500 kg with a spray machine, The weight of the mortar that had dropped was collected, and the weight was measured, and calculated by rebound rate (%) = (amount collected by dropping / 500) x 100).

As shown in Table 1, test no. The rebound rate of 1-5 was 8.2%, etc., which was less than 10%. In contrast, Test No. 1 using sandy slag B or crushed sand containing particles with a particle size greater than 3 mm. The rebound rates for 6 and 7 were as high as 17.9% and 18.1%. From these results, it was confirmed that the rebound amount of mortar when mortar is sprayed can be reduced by using sandy slag with a particle size in the range of greater than 0 mm and 3 mm or less.

(Influence of compounding conditions)
Next, the above test No. Using samples 1 to 5, 7-day strength (N/mm ² ) and 28-day strength (N/mm ² ) were measured, and workability was evaluated. Test no. 1 to 5 are compounding conditions considered preferable (water/cement ratio during kneading is 55% or more and 62% or less, cement unit amount is 300 kg/m ³ or more and 410 kg/m ³ or less, slag fineness is aggregate/cement ratio of 5.0 or more and 6.8 or less). In addition, as a comparative example, test No. 1 was prepared by mixing under conditions other than those considered preferable. 8 to 14 samples of spray mortar were made. Test no. Table 2 shows the compounding conditions of Nos. 8 to 14. These test nos. Using 8 to 14 samples, 7-day strength (N/mm ² ) and 28-day strength (N/mm ² ) were measured, and workability was evaluated. Table 2 shows the results.

The 7-day and 28-day strengths (N/mm ² ) were measured according to JISA1108, the Japan Society of Civil Engineers standard, JSCE F561-1994. Specifically, at the time of construction, the sample formwork was filled with sprayed material separately from the slope surface, and after the sprayed material solidified, three sample specimens were cored and sampled, and three compressive strength tests were performed. An average of 3 measurements was taken. The goal was to achieve a 7-day strength of 18 N/mm ² or more and a 28-day strength of 21 N/mm ² or more.
Workability was evaluated by discharge stability (clogging, fluctuation, etc.) when a wet mortar hose (inner diameter 70φ) was connected to a length of 100 m and pumped by a mortar gun.

Test no. Good strength and workability were obtained for 1 to 5. On the other hand, sample No. with a low fine aggregate/cement ratio. As for Nos. 8 and 9, there was a tendency to clog or the discharge was unstable, and a good construction evaluation could not be obtained. In addition, Test No. 1 with a high fine aggregate/cement ratio. For 10, the target strength was not obtained. Test No. with low water/cement ratio. As for No. 11, it was somewhat clogged, and a good construction evaluation could not be obtained. Test No. with high water/cement ratio. For No. 12, the target strength was not obtained. Test no. In Test Nos. 13 and 14, crushed sand, which is natural sand, was used within the range of the mixing conditions considered preferable as described above. Test No. 13 is somewhat clogged and has many rebounds and cannot be constructed. No. 14 could not obtain the target strength.

In the method of producing fine slag aggregate used for such mortar for spraying, mortar for spraying using the same, and fine slag aggregate for use in mortar for spraying, the particle size of sandy slag constituting the fine slag aggregate is Since it is in the range of greater than 0 mm and 3 mm or less, it is possible to reduce the rebound amount of mortar when mortar is sprayed.

Further, the water/cement ratio during mortar kneading is 55% or more and 62% or less, the cement unit amount is 300 kg/m ³ or more and 410 kg/m ³ or less, and the slag fine aggregate/cement ratio is 5.0. Since it is more than or equal to 6.8 and less than or equal to 6.8, it is possible to ensure good strength and workability.

Furthermore, in the cooling and solidification step, the steelmaking slag is cooled and solidified over 24 hours or more, and when the steelmaking slag is 700° C. or higher, the temperature of the steelmaking slag is lowered by 1° C. or less per minute. It is possible to avoid obtaining a slag with low internal density and brittleness.

Claims (8)

It consists of sandy slag produced from steelmaking slag and having a particle size in the range of greater than 0 mm and 3 mm or less,
Slag fine aggregate used for spray mortar. Said sandy slag contains more than 0% by mass and less than 0.4% by mass of F, 35% by mass or more and 65% by mass or less of CaO, 20% by mass or more and 55% by mass or less of SiO ₂ and 1% by mass or more and 15% by mass of containing Al ₂ O ₃ at mass % or less and having a basicity (CaO/SiO ₂ ) of 0.7 or more and 1.7 or less;
Slag fine aggregate used for the mortar for spraying according to claim 1. A mortar for spraying in which the fine slag aggregate according to claim 1 or 2, cement and water are kneaded. The water/cement ratio during kneading is 55% or more and 62% or less, the cement unit amount is 300 kg/m ³ or more and 410 kg/m ³ or less, and the slag fine aggregate/cement ratio is 5.0 or more and 6 is less than or equal to .8;
A spray mortar according to claim 3. The cement unit amount is 300 kg/m ³ above and 350kg/m ³ is the following
A spray mortar according to claim 4. A method for producing slag fine aggregate used in the mortar for spraying according to claim 1,
a steelmaking process for obtaining steelmaking slag in a molten state;
a cooling and solidification step of cooling and solidifying the molten steelmaking slag obtained in the steelmaking step;
After the cooling and solidification step, the steelmaking slag is crushed, beneficiated, and classified to obtain sandy slag having a particle size of greater than 0 mm and 3 mm or less.
A method for producing slag fine aggregate used in spray mortar. In the cooling and solidification step, the steelmaking slag is cooled and solidified over 24 hours or more, and when the steelmaking slag is 700°C or higher, the temperature of the steelmaking slag is lowered by 1°C or less per minute.
A method for producing slag fine aggregate used in the mortar for spraying according to claim 6 . Said sandy slag contains more than 0% by mass and less than 0.4% by mass of F, 35% by mass or more and 65% by mass or less of CaO, 20% by mass or more and 55% by mass or less of SiO ₂ and 1% by mass or more and 15% by mass of containing Al ₂ O ₃ at mass % or less and having a basicity (CaO/SiO ₂ ) of 0.7 or more and 1.7 or less;
A method for producing slag fine aggregate used in the mortar for spraying according to claim 6 or 7 .

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