JP2006083062A - Fine aggregate and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide good-quality fine aggregate for cement concrete or mortar manufactured from a quickly-cooled blast furnace slag and its manufacturing method. <P>SOLUTION: Water-granulated blast furnace slag obtained by water quenching of molten slag generated by a blast furnace is utilized as the fine aggregate for cement concrete or mortar. Also, the fine aggregate for cement concrete or mortar comprises the water-granulated blast furnace slag containing a fine powder 0.3 mm or smaller in diameter of 8% or less, and is a mixture manufactured by mixing the water-granulated blast furnace slag with other fine aggregate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fine aggregate for cement concrete or mortar using slag generated in a blast furnace for iron making as a raw material, and a method for producing the same.

  Conventionally, fine aggregates for cement concrete and mortar have been often used for sea sand, river sand, land sand, crushed sand such as limestone, and other natural materials. However, in recent years, these resource depletion problems and environmental destruction problems associated with sand collection have occurred. In order to solve this problem, methods for using by-products generated in the industry as fine aggregates have been researched and developed, and several substances are actually used as fine aggregates.

  Further, the problem of degrading sand quality has arisen due to the problem of resource depletion of fine aggregate sand. For example, in land sand, the collection of high-quality parts has been finished, and sand with a small particle size has increased. Low quality fine aggregate sand currently collected has an average particle size of about 0.4 to 0.6 mm, particles of 0.6 mm or less are 50 to 65%, and 0.3 mm. The following particles are present at 20-35%. Because of this particle size configuration, the coarse particle ratio is as small as 1.8 to 2.2. It is difficult to use such low-quality sand as it is as a fine aggregate of mortar or concrete. Therefore, it has been practiced to improve the quality as a fine aggregate by mixing fine aggregates having a large particle size of 2.6 to 3.5.

  On the other hand, there are two methods for treating slag discharged from the blast furnace: a method in which it is poured into a yard in a molten state and gradually cooled, and a method in which it is cooled in water in a soot in which pressurized water is jetted and then rapidly cooled. Among them, the blast furnace slag produced by the water cooling method is a vitreous solid slag called granulated slag having a particle size of 5 mm or less. This granulated slag is finely pulverized and used as a blast furnace cement raw material. In addition, granulated slag is used as a raw material for civil engineering construction that is unprocessed or lightly crushed to replace sand. Among these uses, there are fine aggregates for concrete and mortar. This fine aggregate is used as a substitute for natural sand. Hereinafter, this is referred to as blast furnace slag fine aggregate.

  The slag fine aggregate is required to have different physical properties from the granulated slag used for fine powder for blast furnace cement raw material. As specified in JIS A5012-1981, it is a granulated slag having a relatively large specific gravity and a low water absorption rate. For example, like the method described in Japanese Patent Application Laid-Open No. 55-136151 (Patent Document 1), the cooling method is also different from that for blast furnace cement raw material, and is manufactured under relatively strong cooling conditions. Unprocessed granulated slag produced by cooling (hereinafter referred to as raw ore granulated slag) is mixed with granular material and mixed with needle-like glass. Since this needle-like slag is mixed, it is difficult to form a state where the granulated slag particles are densely packed. As a result, the space occupancy of the particles (hereinafter referred to as the actual volume ratio) was low, and good performance was not exhibited as a fine aggregate. Therefore, in order to solve this problem, the raw ore granulated slag is lightly pulverized using a crusher to reduce the particle size and destroy the acicular slag, thereby increasing the absolute dry specific gravity and unit volume specific gravity. In order to improve and improve the performance as a fine aggregate.

  However, this crushing process reduces the particle size of the blast furnace slag particles, making it unsuitable for use in improving the quality of thin, low-quality fine aggregates. Therefore, in the past, the present inventors may increase the particle size of the blast furnace slag fine aggregate by sieving the granulated slag either before or after the light crushing process and eliminating the small particle size portion. It found out that it was effective and performed invention described in Unexamined-Japanese-Patent No. 2000-319708 (patent document 2). By this invention, the quality of the blast furnace slag fine aggregate is improved, and by mixing this blast furnace slag fine aggregate with a fine low quality fine aggregate, the quality of the fine aggregate is improved and the flow of the ready-mixed concrete is improved. As a result, the effect of facilitating concrete construction is obtained.

JP-A-55-136151 JP 2000-319708 A

  In recent years, sand of fine quality and low quality has been increasing. The blast furnace slag fine aggregate used for the purpose of optimizing the particle size distribution by mixing with this has been required to have a low fine particle ratio. As described above, low-quality fine aggregate sand contains 50 to 65% of particles of 0.6 millimeters or less and 30 to 40% of particles of 0.3 millimeters or less. Because of such a particle size configuration, the coarse particle ratio is 1.9 to 2.2, which is extremely fine sand, and particularly has a large number of fine particles of 0.3 mm or less.

  On the other hand, in the case of a particle size configuration appropriate for fine aggregate, the coarse particle ratio is 2.5 to 2.7, and the average particle size is 0.7 to 1 millimeter. Moreover, particles of 0.6 mm or less are present in 40 to 50%, and particles of 0.3 mm or less are present in 15 to 25%. When this so-called Nakame sand is used, ready-mixed concrete with good fluidity can be produced. In order to reduce the ratio of excessive fine particles in low-quality fine aggregate sand, the blast furnace slag fine aggregate to be mixed is required to have less particles of 0.6 mm or less. In order to make low-quality fine aggregate sand suitable for fine aggregate, a blast furnace slag fine aggregate having a coarse particle ratio of 2.6 or more is mixed.

  However, even in such a blast furnace slag fine aggregate having a high coarse particle ratio, particles of 0.6 mm or less are present in 35 to 45%, and particles of 0.3 mm or less are present in 20 to 25%. Therefore, the normal blast furnace slag fine aggregate has the effect of improving the particle size of the fine aggregate sand which is not so fine with a coarse particle ratio of 2.1 to 2.3. However, in the case of mixing fine blast furnace slag fine aggregate of fine fine aggregate sand having a coarse particle ratio of 2.1 or less, the mixing ratio becomes 50% by mass or more, which is a relatively expensive blast furnace slag fine aggregate. There is a problem of cost increase by using.

  In order to meet this demand, there is an increasing need for improving the particle size of sand having a small particle ratio of 0.3 mm or less and a low coarse particle ratio. As a result, the method for producing fine granulated blast furnace slag fine aggregate by classifying high-granulated slag by sieving has increased in importance, and the above-mentioned JP 2000 The method of classifying blast furnace granulated slag described in Japanese Patent No. 319708 to produce slag fine aggregate is effective. However, even in this method, the effect of removing fine particles is limited.

  The granulated blast furnace slag contains 5 to 15% by mass of water, and fine particles are attached to large particles, which are difficult to separate. Therefore, when a general sieving device is used, it is difficult to classify the screen as it is. For example, when classifying granulated slag having a water content of 5 to 15% by mass using a vibrating sieve which is a general sieving device, it is possible to somehow classify with a sieve mesh of 2 to 3 millimeters. However, in the case of finer mesh, there was a problem that classification could not be performed sufficiently. As a result, fine particles of 0.6 or 0.3 millimeters or less cannot be efficiently removed, the ratio of fine particles of 0.6 millimeters or less is 30 to 40%, and the ratio of fine particles of 0.3 millimeters or less Was only 15-20%.

  As described above, the classification according to the prior art cannot effectively remove particles of 0.6 or 0.3 millimeters or less, so that the effect is limited. In particular, a classification method has been established for producing blast furnace slag fine aggregates that can remove fine particles of 0.3 mm or less and mix with fine sand to produce fine aggregates with an optimal particle size distribution. Was not. Therefore, in order to solve this problem, a new classification method has been established, and a method has been demanded in which blast furnace granulated slag with few fine particles is used as a raw material to produce fine aggregate. Further, there has been a demand for blast furnace slag fine aggregate having an appropriate particle size configuration in order to improve the particle size of the fine sand by the treatment centering on classification.

  Furthermore, the blast furnace slag fine aggregate has a problem of solidification. Granulated blast furnace slag is glassy based on calcium silicate and mullite, and in the presence of moisture, the calcium contained in the leaching powder will be hydrated over several days to several months. A phenomenon in which a large number of particles combine to form a lump due to precipitation in between is solidification. Due to the consolidation phenomenon, when the blast furnace slag fine aggregate is stored, it becomes hardened and difficult to handle. As a result, there is a problem that it becomes difficult to use the blast furnace slag fine aggregate. By using an organic caking retarder of carboxylic acid metal salt, caking delay can be achieved. However, in this method, the caking retarder is expensive, and even if it is used, the hydration reaction is fast and the caking retarding effect is only about 3 weeks when the temperature is higher than 28 ° C. There was a problem that the effect did not last long. In order to use blast furnace slag fine aggregate economically, it is important to prevent consolidation, and a new technology for that purpose has been demanded.

The gist of the present invention is as follows.
(1) Blast furnace slag grains produced by rapidly cooling molten blast furnace slag with cooling water, so-called blast furnace granulated slag grains, having an average particle size of 0.7 to 1.5 millimeters, and Fine aggregate characterized in that the abundance ratio of particles of 3 millimeters or less is 8% or less, and this blast furnace granulated slag may be particles that are crushed after being produced by water cooling.
(2) The fine aggregate as described in (1) above, wherein the actual volume ratio, that is, the space occupation ratio of granulated blast furnace slag particles in the aggregate is 52% or more.
(3) A fine aggregate produced by mixing the fine aggregate described in (1) or (2) above with a fine aggregate of other materials such as natural sand and crushed sand.

(4) The fine aggregate manufacturing method according to any one of (1) to (3), wherein a vibrating screen having a lattice of 0.5 mm or more or a parallel gap is used.
(5) The fine aggregate manufacturing method according to any one of (1) to (3), wherein a vibrating screen having a lattice of 1 to 2 millimeters or a parallel gap is used.
(6) A method for producing fine aggregate, characterized by classifying and producing crushed granulated blast furnace slag particles.

(7) A method for producing fine aggregate, characterized by crushing blast furnace granulated slag particles.
(8) The fine aggregate manufacturing method according to any one of (1) to (3), wherein the crushed blast furnace granulated slag particles are classified and manufactured.
(9) The method for producing fine aggregate according to any one of (1) to (3), wherein the blast furnace granulated slag particles are crushed by the method.

  As described above, the rapid cooling blast furnace slag according to the present invention is efficiently classified, and the excellent effect of obtaining good quality cement concrete and fine bone for mortar by the classification treatment is exhibited.

  First, the present inventors investigated the physical properties of blast furnace slag fine aggregates for mortar and cement concrete, and elucidated that solidification is difficult to occur when the particle ratio is 0.3 mm or less. Consolidation is a phenomenon in which calcium oxide is eluted from vitrified blast furnace slag in the presence of adhering water to form acicular hydrates, which cause bonding between particles. In our study, it has been clarified that the elution of calcium oxide is proportional to the specific surface area.

  The inventors further experimentally manufactured blast furnace slag fine aggregates with various particle size configurations and investigated their characteristics. As a result, it has been found that the particle size distribution affects the consolidation, which is a fact that has not been clarified in the past. The inventors of the present invention conducted a consolidation experiment by reducing the specific surface area of the blast furnace slag fine aggregate except for fine particles. When particles of 0.3 mm or less of the blast furnace slag fine aggregate were reduced to 12% or less, consolidation did not occur even when stored in an environment of 40 ° C. for one month. Therefore, from the viewpoint of preventing caking, it is a condition of the blast furnace slag fine aggregate of the present invention that the particle ratio of 0.3 mm or less in the blast furnace slag fine aggregate is 12% or less. Moreover, this effect becomes remarkable by making the particle | grains of 0.15 millimeters or less into 4% or less. In particular, when it is desired to prevent the consolidation phenomenon for a long period of time, if the particle ratio of 0.3 mm or less is 8% or less, and the particle ratio of 0.15 mm or less is 2% or less, it is consolidated even after storage for 2 months or more. Does not happen.

  On the other hand, as described above, the flowability of raw mortar and ready concrete deteriorates in the fine aggregate with many fine particles. In our study, if the fine aggregate contains particles with a particle size of 0.3 millimeters or less of 30% or more, the fine aggregate is too fine and the mortar and coarse aggregate do not fit well. It turned out to be. This is because the coarse aggregate is 5 to 25 millimeters, but when the particles of 0.3 millimeters or less are as large as 30% or more, there are too few particles of 0.3 to 5 millimeters in the concrete. , There is a gap in the particle size composition. As a result, there is a problem that there are few particles having an intermediate particle size, particularly 0.5 to 2 millimeters, which can blend between the mixture of cement milk and fine particles and the coarse aggregate.

  For this purpose, a blast furnace slag fine aggregate with a small particle size and a small particle size is mixed with such fine fine aggregate. The blast furnace slag fine aggregate used at this time is preferably the one described above. That is, a blast furnace slag fine aggregate having a particle size of 12 mm or less is used. However, since the fine aggregate after mixing needs to have many particles of 0.5 to 2 millimeters, the average particle diameter of the blast furnace slag fine aggregate is 0.7 to 1.5 millimeters.

  In addition, the fine aggregate after mixing is also an important item for producing a high-quality fine aggregate. The present inventors have also clarified that it is an important condition that the fine aggregate after mixing is that the space occupancy of the particles of the blast furnace slag fine aggregate, that is, the so-called actual volume ratio, is 52% or more. Generally, fine aggregates having an actual volume ratio of 56 to 62% are high-quality fine aggregates, but the blast furnace slag fine aggregates of the present invention are classified and have a uniform particle size distribution, so Even at 57%, the quality is equivalent to the range of good real volume ratio of general fine aggregates.

  Since this blast furnace slag fine aggregate has only 12% or less of particles of 0.3 mm or less, fine sand, that is, particles of 0.3 mm or less are 30% or more, and the coarse particle ratio is 1.9-2. It is possible to obtain an appropriate particle size distribution as a fine aggregate for concrete only by mixing it with the sand of .2 at a ratio of about 30% by mass. As a result, the amount of expensive blast furnace slag fine aggregate used can be reduced to a small amount, and economical fine aggregate production becomes possible. In addition, as described above, this blast furnace slag fine aggregate does not have a caking problem, which is the reason for using the fine aggregate of the present invention. Since there is no caking problem, it can be stored in a silo or the like and mechanically cut out quantitatively. From this, when using this for mixing, it has the effect of being able to quantitatively and uniformly mix with fine aggregates such as fine natural sand stored in silos, etc., so the blast furnace of the present invention Slag fine aggregate is excellent for mixing.

  As described above, the blast furnace slag fine aggregate according to the present invention has excellent characteristics. However, as described above, the conventional technique reduces the ratio of particles of 0.3 mm or less on an industrial scale. Such a blast furnace slag fine aggregate did not exist because it was difficult to do so. For this reason, the effect of the present invention has not been elucidated. That is, it was difficult to produce this at low cost, which is why the fine aggregate of the present invention was not found. Therefore, the present inventors conducted research on a method for classifying granulated blast furnace slag at an industrial scale, that is, a throughput per hour of 30 to 200 tons.

  According to experiments, in the case of 5 to 15% by mass of adhering moisture, which is normal moisture, fine particles of 0.3 mm or less in the blast furnace granulated slag adhere to large particles of 1 mm or more. I have clarified that It was also clarified that this adhesive force is strong and it is not easily separated by vibrations that can be caused by ordinary machines. In order to separate fine particles, blast furnace granulated slag that is easy to classify by either drying to reduce moisture or adding excess water until it does not fit between blast furnace granulated slag particles. It was found that this problem can be solved by sieving.

  In the method of reducing the water content of the granulated blast furnace slag, sieving is facilitated by weakening the adhesive force due to the water content between the particles. The present inventors have clarified that it is efficient to improve the separation of the particles and classify them by setting the water content of the granulated blast furnace slag to 3% by mass or less. Since the granulated blast furnace slag immediately after production contains about 20% by mass of water, first, drained water is made 6 to 10% by mass. Next, the water content is 3% by mass or less, preferably 1.5% by mass or less in a drying apparatus. If it will be in this state, blast furnace granulated slag will become easy to flow.

  This low moisture blast furnace granulated slag is classified by the apparatus shown in FIG. FIG. 1 shows a vibrating sieve device which is an example of a device for classifying low-moisture blast furnace granulated slag. The blast furnace granulated slag is cut out from the blast furnace granulated slag supply tank 1 and placed on the dry vibrating screen 2. Here, fine particles are dropped on the granulated blast furnace slag under the mesh of the vibrating screen 2. Large particles remain on the dry vibrating screen 2 and are conveyed in the direction of the discharge unit 3. Granulated blast furnace granulated slag discharged from the discharge unit 3 is stored in the large particle product tank 4. Further, the fine particles falling under the sieve are stored in the small particle product tank 6 via the small particle chute 5.

  As a result of the classification operation, in the process of sieving the low-moisture blast furnace granulated slag, about 50 to 70% of the particles smaller than the width of the sieve mesh (screen gap) fall under the sieve. Therefore, most of the particles on the sieve are larger than the sieve mesh. The sieve screen of the vibrating screen 2 has a grid shape or a parallel gap. Moreover, it is preferable that the width of the sieve mesh is 0.7 mm or more. This is because when the mesh size is 0.7 mm or less, the granulated blast furnace slag is bridging on the mesh and often clogs. For the purpose of dropping 0.3 or 0.6 mm particles under the sieve, the sieve mesh is 2 mm or less. The screen for performing classification is desirably a vibration type as shown in the apparatus of FIG. In addition to the type of vibrating screen of FIG. 1, a type of apparatus that vibrates a circulating and rotating screen is also effective for the method of the present invention.

  Next, the classification method by adding water excessively will be described. Hereinafter, this method is referred to as wet classification. In this system, a proportion of water greater than can be included between the particles is added to the granulated blast furnace slag to allow fine particles to float in the water between the particles. In this state, it is passed through a sieve, and water and fine particles are allowed to flow under the sieve to separate large particles from fine particles. This method has a cleaning effect because water flows through the mesh, and has a feature that clogging of the mesh is difficult to occur. There are several specific methods for carrying out this wet classification. A method of classifying ground granulated blast furnace slag with an almost horizontal vibrating screen, a method of classifying by flowing a slurry of ground granulated blast furnace slag on an arc-shaped sieve, There are methods that combine the two.

  FIG. 2 shows an example of an apparatus for performing wet classification, and shows a type in which blast furnace granulated slag containing excessive water is supplied and classified on a vibrating sieve installed almost horizontally. Blast furnace granulated slag is supplied from the supply tank 1 to the slurry tank 7. In the slurry tank 7, a slurry in which blast furnace granulated slag and water are well mixed is prepared. The mixing ratio of granulated blast furnace slag and water at this time is best in the range of 1 to 2 to 1 to 8 in terms of mass ratio. A slurry containing a large amount of granulated blast furnace slag is supplied onto the wet vibrating screen 7. The wet vibrating screen 7 sends large particles forward while vibrating. The large granulated blast furnace granulated slag particles are transferred from the wet vibrating screen 8 to the conveyor 9 and sent to the yard. Water is sent from the circulating water tank 11 to the slurry tank 7 by a pump 10. Water and fine particles are solid-liquid separated in the precipitation tank 12. The water here is returned to the circulating water tank 11. In some cases, water may spray from the spray 13 on the wet vibrating screen 8 to help the fine particles fall under the screen. This method improves classification efficiency.

  In this classifying method, the water ratio is set to 1: 2 to 1: 8 for the following reasons. When the water ratio is 1 to 2 or less, the fluidity of the slurry is poor, and it becomes difficult to supply the slurry from the slurry tank 5 to the wet vibrating screen 7. When the water ratio is in the range of 1: 2 to 1: 8, it is possible to realize a state in which the slurry is fluid and fine particles are well dispersed in water. Even within this range, when the water ratio is 1: 4 to 1: 8, this effect is almost constant. On the other hand, when the water ratio is 1: 8 or more, the water ratio is too high, and the pump 9 and the circulating water tank 10 for supplying water become large devices, which is not economical. This is the reason why the sieving operation is easy when the ratio of granulated blast furnace slag to water is 1 to 2 to 1: 8.

In the method of classifying by adding water excessively with a sieve device installed almost horizontally, a circulating and moving sieve may be used in addition to the type of sieve device of FIG. In this sieving apparatus, there is a screen that circulates and moves, and slurry blast furnace granulated slag is dropped on this slurry, and water and fine particles are passed under the screen. In addition, in order to classify efficiently, this screen may be vibrated.
Further, in the method using the sieving apparatus such as the type shown in FIG. 2, instead of placing the slurry on the wet vibration type screen 7 or the like, a blast furnace granulated slag particle having a water content of 6 to 20% by mass is placed and a large amount is placed on this. The same effect as the above method can be obtained by spraying water. Also in this case, efficient classification can be performed by using 2 to 8 times as much water as the mass of granulated blast furnace slag.

  In the case of wet classification, the blast furnace granulated slag grains on the screen 7 can be efficiently classified by reducing the thickness to about 5 mm. In order to improve the productivity of the sieve, as in FIG. A vibrating sieve may be used. By vibrating the screen 7, clogging of granulated blast furnace slag particles can be prevented, so that even a layer thickness of 5 mm or more, or in some cases about 20 mm, can be classified without problems. At this time, the vibration state of the screen has an appropriate range. The amplitude is preferably 0.25 mm or more. This is the minimum amplitude to remove particles from a 0.5-1.5 mm wide sieve mesh. Here, the amplitude means the maximum change value of the horizontal component of vibration. Further, when the frequency is 1 hertz or less, there is a problem that it is difficult to remove the particles from the screen mesh, and when the frequency is 20 hertz or more, there is a problem that the vibration is too fast and the time for removing the particles is insufficient. Therefore, the frequency is preferably 1 to 20 hertz.

  FIG. 3 shows another example of an apparatus for performing wet classification, and shows a type in which blast furnace granulated slag containing excessive water is supplied to a sieve of a vent sheave 14 on an arc to perform classification. The slurry of granulated blast furnace slag is allowed to flow from the slurry tank 7 to the vent sheave 14. At this time, fine particles and water pass down from the sieve mesh. Large particles that have passed through the vent sheave 14 are sent to the product yard by the conveyor 8. Fine particles and water are also solid-liquid separated in the precipitation tank 12.

  As a result of these sieving operations, in the wet classification process, about 70 to 80% of the particles smaller than the width of the sieve mesh (screen gap) fall under the sieve. Therefore, most of the particles on the sieve are larger than the sieve mesh. The sieve screen of the vibrating screen 2 has a grid shape or a parallel gap. Moreover, the mesh width is preferably 0.5 mm or more. This is because blast furnace granulated slag grains are often clogged with a sieve width of 0.5 mm or less. In addition, the present inventors have also found that it is desirable that the width of the sieve mesh is about 0.3 to 1 mm larger than the particle diameter (classification point) at the boundary to be classified.

  Blast furnace granulated slag that has not been crushed often has a low actual volume ratio and a low absolute dry specific gravity. For this reason, as it is, the performance as a fine aggregate is slightly inferior. Therefore, in the method for producing the blast furnace slag fine aggregate of the present invention, it is desirable to combine the classification operation and the crushing operation. In addition, although there exists the method of classifying after crushing and the method of crushing after classification, in this invention, you may process in any order. If you want to remove fine particles strictly, classify after crushing operation. When the capacity of the crushing operation is small, crushing is performed after the classification operation.

  Although it depends on the particle size distribution of the granulated blast furnace slag, which is the raw material, in the wet classification method, if the processing is performed with a sieve width of 0.5 to 1.5 mm, the ratio of the particles on the sieve is 0.3 mm or less. Can be reduced. However, the condition of the mesh width is a range in the case of classification after crushing. Moreover, when crushing after classification, the mesh width of 0.7 to 1.5 mm is good. As described above, the classification method of the present invention is particularly effective for separating particles of 0.3 mm or less. However, according to the present invention, not only classification for this purpose but also classification at an arbitrary classification point can be performed efficiently. For example, it is effective to classify into a set having many particles of 1 mm or less and a set having many particles of 1 mm or more. In this case, the mesh width is preferably 0.5 mm or more.

Hereinafter, the present invention will be specifically described with reference to examples.
Table 1 shows the particle size distribution and water content of granulated blast furnace slag used as the raw material for the classification treatment of the present invention. The slag 1 was composed of slightly coarse particles, the average particle diameter was 1.15 millimeters, the coarse particle ratio was 3.2, and the particle ratio of 0.3 millimeters or less was 14%. The slag 2 was composed of slightly fine particles, the average particle diameter was 0.87 millimeters, the coarse particle ratio was 2.8, and the particle ratio of 0.3 millimeters or less was 24%. Slag 3 was obtained by lightly crushing slag 1 with an impact crusher. The average particle size was 0.81 millimeters, the coarse particle ratio was 2.7, and the particle ratio of 0.3 millimeters or less was 25%.

  First to third embodiments are examples of classification using the apparatus of FIG. The dry vibratory screen 2 uses a square mesh screen, and the width of the sieve mesh is 1 mm. The results are shown in Table 2. In Example 1, what dried slag 1 to the moisture of 1.8 mass% was used. As a result of classification, the recovered large particles had an average particle diameter of 1.29 millimeters, a coarse particle ratio of 3.6, and a particle ratio of 0.3 millimeters or less of 6%. In Example 2, as a result of classification of slag 2 having a water content of 0.8% by mass, the average particle diameter was 1.02 millimeters, the coarse particle ratio was 3.2, and the particle ratio of 0.3 millimeters or less was 9%. It was. In Example 3, as a result of classification of slag 3 having a moisture content of 2.6% by mass, the average particle diameter was 0.97 millimeters, the coarse particle ratio was 3.0, and the particle ratio of 0.3 millimeters or less was 12%. It was. Thus, an efficient sieve was made by classification under the conditions of the present invention. In particular, when the blast furnace granulated slag subjected to the crushing treatment of Example 3 was sieved, the actual volume ratio was 55%, which was good.

  On the other hand, in the comparative example 1, it is the result of classifying the slag 1 in the state of moisture 8 mass%. In this example, clogging occurred in the sieve after 12 minutes from the start of the sieving operation. The slag collected on the sieve had an average particle diameter of 1.19 millimeters, a coarse particle ratio of 3.3, and a particle ratio of 0.3 millimeters or less of 12%. Also, the slag under the sieve had a relatively coarse average particle size of 0.92 millimeters and could not be separated sufficiently.

  Examples 4 to 6 are examples of classification using an apparatus in which the wet-vibration screen 7 having meshes with parallel gaps shown in FIG. 2 is installed. The results are shown in Table 3. In Example 4, the slag 1 is classified. First, a slurry was prepared by adding 2.7 times water to the mass of the slag 1, and this was sieved. The width of the sieve mesh was 1.0 millimeter. The particles on the sieve had an average particle size of 1.32 mm, a coarse particle ratio of 3.6, and a particle ratio of 0.3 mm or less was 3%. The particles under the sieve had a small average particle size of 0.47 millimeters.

  In Example 5, a slurry in which 3.3 times the amount of water was added to the mass of the slag 2 was prepared, and this was classified with a sieve mesh width of 0.8 mm, but the particle diameter was relatively small. Therefore, 0.3 times as much water as the mass of the slag 2 was applied to the slag 2 on the wet vibrating screen 7 to promote the separation of fine particles. The particles on the sieve had an average particle diameter of 1.06 millimeters, a coarse particle ratio of 3.1, and a particle ratio of 0.3 millimeters or less was 5%. In Example 6, the slurry which added 4.0 times the water with respect to the mass of the slag 3 was made, and this was classified. The width of the sieve mesh was 0.6 mm. The particles on the sieve had an average particle diameter of 1.00 mm, a coarse particle ratio of 2.9, and the ratio of particles of 0.3 mm or less was 8%. In any of the processes, the amplitude of the vibrating screen 7 was 0.7 mm, and the vibration frequency was 2 hertz.

  In Comparative Example 2, the apparatus of FIG. 2 was used to make a slurry in which 1.5 times the amount of water was added to the mass of the slag 3, and this was sieved. There are too few examples. The width of the sieve mesh was 0.8 mm. The results are also shown in Table 3. In this example, the fluidity of the slurry was insufficient, and water could not be removed from the wet vibrating screen 7, so that classification was possible, but the effect of the sieve was slightly insufficient. . The particles on the sieve had an average particle size of 0.89 meters, a coarse particle ratio of 2.7, and a particle ratio of 0.3 mm or less was 19%. In this process, the ratio of the particles under the sieve was small and the classification efficiency was poor.

  In Comparative Example 3, using the apparatus of FIG. 2, a slurry was prepared by adding 3.0 times the water to the mass of the slag 3, and this was sieved to a sieve mesh width of 0.45 mm. This was an example of a relatively narrow mesh. The results are also shown in Table 3. In this example, the classification process was started, and the process could be performed smoothly for 3 minutes. However, after that, the clogging of the sieve gradually occurred, and after 15 minutes, the process was interrupted. In addition, among the particles on the sieve, the particle ratio of 0.3 mm or less was 21%, and the ratio did not decrease so much.

  Examples 7 to 9 are examples of classification using the apparatus of FIG. The results are shown in Table 4. In Example 7, the slurry which added 2.5 times the water with respect to the mass of the slag 1 was made, and this was sieved. The width of the sieve mesh was 1.4 mm. The particles on the sieve had an average particle size of 1.38 mm, a coarse particle ratio of 3.7, and a particle ratio of 0.3 mm or less was 1%. In this treatment, the ratio of the particles remaining on the sieve of 0.3 mm or less was a good result, but the ratio of the particles on the sieve was 55%. In particular, in order to produce a fine aggregate with large particles, the width of the mesh is 1 mm or more.

  In Example 8, a slurry was prepared by adding 4.0 times water to the mass of the slag 2 and classified. The particles on the sieve had an average particle diameter of 1.01 millimeters, a coarse particle ratio of 3.0, and a particle ratio of 0.3 millimeters or less was 7%. In Example 9, the slurry which added 5 times the water with respect to the mass of the slag 3 was made, and this was classified. The particles on the sieve had an average particle diameter of 1.00 mm, a coarse particle ratio of 2.9, and a ratio of particles of 0.3 mm or less was 4%. In any of the treatments of Examples 7 to 9, the amplitude of the vibrating screen 7 was 0.5 to 1 mm, and the vibration frequency was 2 to 3 hertz.

  In the method described above, as in Examples 4 to 9, the wet classification method is an optimal method for classifying blast furnace granulated slag. However, it is necessary to make the mass ratio and sieve mesh of blast furnace granulated slag and water appropriate. In order to reduce the particle ratio of 0.3 mm or less of the granulated blast furnace slag, it was good to set the mesh width to 0.5 to 1.5 mm.

  Although not described in the table, Example 10 is an example in which the blast furnace granulated slag classified in Example 4 was crushed with an impact crusher. The particles obtained as a result of the crushing treatment had an average particle diameter of 1.17 mm, a coarse particle ratio of 3.1, and a particle ratio of 0.3 mm or less was 7%. The actual product ratio of this crushed product was 55%. The unit volume mass and the absolute dry mass were improved from 1.38 kg / liter to 1.49 kg / liter and from 2.67 to 2.72, respectively. Thus, if a crushing process is performed after a classification process, a favorable blast furnace slag fine aggregate can be manufactured.

  An experiment was conducted on the occurrence of consolidation of blast furnace slag fine aggregate produced by the method described above. In Example 11, particles of 0.3 mm or less obtained in the classification treatment of Example 3 were 12% blast furnace granulated slag, and in Example 12, 0.3 mm or less obtained in the classification treatment of Example 5 Example 13 is an experimental result of granulated blast furnace slag containing 3% of blast furnace, and Example 13 is a granulated blast furnace slag containing 7% of particles of 0.3 mm or less obtained by classification and crushing in Example 10. . Moreover, the comparative example 4 is an experimental result of blast furnace granulated slag in which particles of 0.3 mm or less are 24%.

  In these consolidation experiments, granulated blast furnace slag having a water content of 8% by mass was placed in a steel container having a diameter of 15 centimeters and a height of 20 centimeters, and a weight of 20 kilograms was placed thereon. This experimental specimen was placed in a constant temperature bath at 40 ° C. for experiments. A 5 mm-diameter rod was inserted into this experimental specimen, and the resistance at this time was measured. The point at which this value increased rapidly was determined as the point at which consolidation occurred. Example 11 consolidated after 55 days and Example 13 after 91 days. Moreover, in Example 12, since the ratio of particles of 0.3 mm or less was as small as 3%, it did not solidify even after 120 days. On the other hand, in Comparative Example 4, the particle ratio of 0.3 mm or less was as high as 24%, and thus solidified after 19 days. Thus, when the particle ratio of 0.3 mm or less is 12% or less, consolidation is slow, and when it is 8% or less, the time until consolidation is extremely long. Further, when the particle ratio of 0.3 mm or less is 4% or less, the particles hardly consolidate.

  Examples 13 and 14 are the results of concrete construction using fine aggregate obtained by mixing the blast furnace slag fine aggregate produced in Examples 6 and 10 and fine sand having a coarse grain ratio of 2.19 described in Table 1. . These blast furnace slag fine aggregates had an actual volume ratio of 53% and 55%, which is an important index. Example 13 is an example of a mixed fine aggregate obtained by mixing 30% by mass of the blast furnace slag fine aggregate of Example 6 and 70% by mass of this land sand. Example 14 is an example of a mixed fine aggregate obtained by mixing 30% by mass of the blast furnace slag fine aggregate of Example 6 and 70% by mass of the above-mentioned land sand. The coarse particle ratio of the mixed fine aggregate was 2.47 in Example 13 and 2.52 in Example 14. Comparative Example 5 is a concrete test result using fine sand having a coarse grain ratio of 2.19 as it is.

  Cement concrete using this fine aggregate was manufactured, and the performance of the fine aggregate was judged from the slump measurement result of the ready-mixed concrete. The concrete production conditions were to use 1050 kilograms of coarse aggregate, 710 kilograms of fine aggregate and 175 kilograms of cement per cubic meter of concrete. The mixing ratio of water at this time was a condition that the slump was 18 centimeters with a standard fine aggregate. Judgment as to whether it is a fine aggregate of good quality was based on a slump of 18 ± 1.5 centimeters. The standard fine aggregate was river sand having a coarse grain ratio of 2.52.

  In Example 13, the slump was 17.5 centimeters, and there was no separation of coarse aggregate and mortar, and it was a good ready-mixed concrete. In Example 14, the slump was 17.0 centimeters, and this was also good ready-mixed concrete without separation of coarse aggregate and mortar. The solidified cement strength was the same as that of standard sand. On the other hand, in Comparative Example 5, the slump was too large at 20.5 centimeters, and there was separation of the coarse aggregate and the mortar, and the concrete was rough and had poor fluidity. The solidified cement strength was only about 85% of the standard sand. Moreover, the crack had arisen. As in this example, by mixing the blast furnace slag fine aggregate of the present invention and fine sand, it is possible to produce a high quality mixed fine aggregate by optimizing the particle size distribution. Moreover, the performance of the concrete manufactured using this mixed fine aggregate becomes appropriate.

It is a figure of the vibration-type sieve apparatus which classifies the blast furnace granulated slag with a low water | moisture content which this invention performs. It is a figure of the vibration-type sieve apparatus installed horizontally which classifies the blast furnace granulated slag of the state containing much moisture which performs this invention. It is a figure of the sieving apparatus with the circular arc shape which classifies the blast furnace granulated slag of the state containing much moisture which performs this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Supply tank 2 Dry vibration screen 3 Large particle discharge part 4 Large particle product 5 Small particle chute 6 Small particle product tank 7 Slurry tank 8 Wet vibration screen 9 Conveyor 10 Pump 11 Circulating water tank 12 Precipitation tank 13 Spray 14 Vent sieve


Patent applicant: Nippon Steel Corporation and 1 other
Attorney: Attorney Shiina

Claims (9)

Blast furnace slag grains produced by rapidly cooling molten blast furnace slag with cooling water, the average particle diameter of 0.7 to 1.5 millimeters, and the presence ratio of particles of 0.3 millimeters or less is 8 Fine aggregate characterized by being less than or equal to%. The fine aggregate according to claim 1, wherein a space occupancy ratio of blast furnace slag particles in the aggregate of blast furnace slag particles is 52% or more. A fine aggregate produced by mixing the fine aggregate of claim 1 or 2 with a fine aggregate of another material. The fine aggregate manufacturing method according to any one of claims 1 to 3, wherein a vibrating screen having a lattice of 0.5 mm or more or a parallel gap is used. The fine aggregate manufacturing method according to any one of claims 1 to 3, wherein a vibrating screen having a lattice of 1 to 2 millimeters or a parallel gap is used. A method for producing fine aggregate characterized by classifying and producing crushed blast furnace slag particles produced by rapidly cooling molten blast furnace slag with water. A method for producing a fine aggregate, characterized in that blast furnace slag grains produced by rapidly cooling molten blast furnace slag with water are crushed. The fine aggregate manufacturing method according to any one of claims 1 to 3, wherein the blast furnace slag grains produced by rapidly cooling molten blast furnace slag with water are classified and manufactured. The method for producing a fine aggregate according to any one of claims 1 to 3, wherein a blast furnace slag particle produced by rapidly cooling molten blast furnace slag with water is crushed.

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