JPH0773679B2 - Method for producing crushed sand for concrete - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing crushed sand for concrete, more specifically, to obtain crushed sand for concrete by stirring medium stone, raw sand and water in a rotating cylindrical drum. To the improvement of the manufacturing method.

[0002]

2. Description of the Related Art Conventionally, a device called a rod mill has been known as a device for producing crushed sand for concrete, but this rod mill has a plurality of metallic members in an internal stirring chamber of a cylindrical drum. The rod is housed in a rollable manner, the raw sand and water are supplied into the rod, and the cylindrical drum is rotated to forcibly crush the raw sand by the impact force of the metal rod to obtain crushed sand. It is configured as follows. However, the hardness of the metal rod is much higher than the hardness of the raw sand, and therefore the impact force applied to the raw sand from the metal rod becomes extremely large. Since it is merely crushing the raw sand and can only perform some frictional action, it cannot naturally perform the action of gradually grinding the surface of the raw sand. The crushed sand produced in this way is of extremely low quality as fine aggregate, which is the main raw material for concrete. In particular,
Of naturally existing river sand, mountain sand, sea sand or land sand, etc.
It is known that river sand, which is hard and whose grain shape is almost spherical, has the highest quality as fine aggregate, and the rate of grain shape judgment by this washed sample of river sand (JIS A 5004 The value obtained by dividing by dry specific gravity) is 57 to 59%, while the crushed sand obtained by the rod mill has a grain shape determination performance rate of around 53%. And, the crushed sand obtained by the rod mill has various defects such that the grain shape is not spherical but flat and angular, the surface (skin) is not smooth, and cracks are generated. , The workability and the fluidity of the concrete are adversely affected.

In order to deal with such a problem, the applicant of the present invention proposes to produce crushed sand as follows in the previous patent application (JP-A-2-222736 [US Pat. No. 4,995,561]). did. That is, as shown in FIG. 1, a plurality of medium stones 3 ... 3 are provided in the internal stirring chamber 2 of the cylindrical drum 1.
In the state of being stacked, the raw sand 4 and the water 5 are continuously fed thereinto, and the cylindrical drum 1 is rotated by the operation of the drive device so that the medium stones 3 ... The raw sand 4 and the water 5 are stirred, and the crushed sand 6 generated by this stirring action is continuously taken out together with the water from the discharge port 7. According to this, since the medium stone, the raw sand and the water are agitated, the entire surface of the raw sand is ground under substantially the same conditions as the generation process of the river sand. It has all the advantages that the impurities adhering to the surface are removed, and that it has various advantages that river sand has, that is, the grain shape is close to a sphere, it is not flat, the surface is smooth, and cracks do not occur. Crushed sand will be obtained in a short time.

[0004]

However, even with the crushed sand manufacturing means for concrete proposed by the applicant, there are still problems to be solved in order to manufacture crushed sand of higher quality. That is, the amount of the medium stones 3 ... 3 stacked in the internal stirring chamber 2 of the cylindrical drum 1 is not too small or too large, and the raw sand 4 ... 3 is not obtained, and even if the amount is once appropriate, the medium stones 3 ... Regarding the number of revolutions of the cylindrical drum 1 per unit time, if the number of revolutions is too large, the medium stones 3 ... 3 are lifted to the upper part along the inner peripheral surface of the cylindrical drum 1 to obtain a frictional effect. On the other hand, if the number of rotations is too small, the raw sand 4 ... 4 cannot move well in the axial direction of the cylindrical drum 1, and therefore the input raw sand 4 ... 4.
Has a problem in that it does not flow smoothly toward the discharge port 7. Furthermore, the relationship between the input amount of the raw sands 4 ... 4 and the input amount of the water 5 is also an extremely important factor, and if this relationship is not appropriate, the fluidity of the raw sands 4 ... 4 at the time of stirring is required. As a result, there arises a problem that the raw sands 4 ... 4 and the medium stones 3 ... 3 are not uniformly mixed.

The present inventor has conducted extensive studies on a method for producing crushed sand for concrete. As a result, the relationship between the size of the cylindrical drum and the amount of medium stones, the relationship between the amount of raw sand and the amount of water input , and further
The water introduced into the cylindrical drum is discharged from the cylindrical drum.
It was found that the passage distance passing through the cylindrical drum before being discharged is an extremely important factor in producing high quality crushed sand for concrete, and the present invention was completed. It has come. Therefore, the present invention aims to improve the manufacturing process of crushed sand for concrete and to obtain high quality crushed sand by making each of the above factors most appropriate.

[0006]

The method for producing crushed sand for concrete according to the present invention, which has been made to achieve the above technical problems, has the following features. That is, while stacking a plurality of medium stones in the internal stirring chamber of the cylindrical drum, while feeding the raw sand and water into the internal stirring chamber,
The cylindrical drum is rotated by the operation of a driving device, whereby the medium stone, raw sand and water are stirred in the internal stirring chamber,
When the crushed sand obtained by this stirring action is taken out from the internal stirring chamber together with water, the amount of the plurality of medium stones
Is 1/4 to 1/3 of the diameter of the inner peripheral surface of the cylindrical drum.
Temperature range and keep it from the internal stirring chamber.
Internal stir chamber of other cylindrical drum if needed
Concrete that was re-introduced into the tank to continue stirring
In the method for producing crushed sand for use in raw sand to the internal stirring chamber
Set the input amount, then proportionally to the input amount of the raw sand
Set the amount of water input to the internal stirring chamber to be approximately proportional
Then, based on the input amount of water,
Before being discharged from the internal stirring chamber, the internal stirring chamber
Calculate the distance traveled through the
Make sure the passing distance is within the preset optimum range
To determine the number of cylindrical drums used for stirring
It was done. And preferably, the internal stirring chamber
The optimum range of the water passage distance is 100 to 150 m .

[0007]

According to the above means, a plurality of medium stones selected so as to have a predetermined particle size distribution are housed in the cylindrical drum, and the medium stones and water are used to perform the grinding action on the raw sand. However, the amount by which the medium stones are stacked is within a height range of ¼ to ⅓ of the diameter of the inner peripheral surface of the cylindrical drum. That is, medium stones are piled up to a height of ¼ to ⅓ of the inner peripheral surface diameter measured from the lowest portion on the inner peripheral surface of the cylindrical drum. Then, when the medium stone is worn away due to stirring and the position of the upper surface of the stack is lowered,
Medium stones are additionally charged so that the diameter does not fall below 1/4 of the inner peripheral surface diameter, and at the time of additional charging, it does not exceed 1/3 of the inner peripheral surface diameter. As a result, the medium stone is always maintained within the height range of 1/4 to 1/3 of the inner peripheral surface diameter. Then, it may be necessary to change the size of the cylindrical drum due to a problem of installation space, a problem of equipment cost, etc. In such a case, the inner peripheral surface diameter of the cylindrical drum becomes large. By reducing the number of rotations of the cylindrical drum in accordance with the above, the peripheral speed of the inner peripheral surface of the cylindrical drum is always the optimum speed, and the raw sand and the medium stone are lifted to the upper part more than necessary or the lifting amount is insufficient. Problems such as sticking are avoided. In addition, when trying to increase the amount of crushed sand for concrete taken out from the cylindrical drum, it is necessary to increase the input amount of raw sand, but in such a case, increase the input amount of raw sand. By increasing the amount of water input in proportion to or approximately in proportion to, the fluidity of the raw sand inside the cylindrical drum is adjusted to an appropriate state, and an even grinding action is performed on the raw sand from the medium stone. In this way, crushed sand for concrete with consistent quality is manufactured. That
In the present invention, if necessary, a plurality of cylindrical drums are connected.
Although the raw sand is continuously stirred, the present inventor
Water introduced into the cylindrical drum is discharged from the cylindrical drum
Before passing through the internal stirring chamber of the cylindrical drum
The size of the passing distance is very large for the quality of the crushed sand produced.
It has been found that it will affect the water inside this internal stirring chamber.
The optimum range of passage distance (preferably 100 to
The number of the cylindrical drum used so that it fits within 150 m)
I try to determine the number. That is, one cylindrical drum
The water's passage distance in the cylindrical drum only by stirring with
Is smaller than the lower limit of the optimum range, the
By increasing the number of drums used to 2 or more,
The water passage distance in the cylindrical drum is within the optimum range.
Adjusted so that it will be crushed, and the crushed sand produced by this
It is intended to improve quality. In addition, water to the cylindrical drum
Water in the internal stirring chamber of the cylindrical drum based on the input amount of
Calculation of the passage distance of is performed as follows. Immediately
The amount of water input to the internal stirring chamber and the internal stirring chamber
It is necessary for the water charged in the chamber to be discharged from the internal stirring chamber.
The relationship with the passage time
Put. At the same time, based on the quality of the crushed sand produced,
The optimum range of passage time of water in the internal stirring chamber,
The quality of the crushed sand that has been produced and meets the specified requirements
Find and set the range of transit times that can be achieved. And within the above
Time of water passing through the internal stirring chamber and the size of the internal stirring chamber
From this, calculate the water passage distance in the internal stirring chamber,
As a result, the amount of water input to the internal stirring chamber and the internal stirring
In addition to obtaining the relationship with the water passage distance in the stirring chamber,
Based on the optimum range of water transit time in the internal stirring chamber,
If the optimum range of water passage distance in the internal stirring chamber is obtained,
good.

[0008]

EXAMPLES Examples of the present invention will be described below, but the examples are not intended to limit the present invention. First, as a preliminary step, a plurality of rounded medium stones obtained by subjecting a crushed stone produced in a crushed stone manufacturing plant or the like to a predetermined process are treated with a first group having a grain size of 100 to 80 mm and a grain size of 100 to 80 mm. With a second group of 80 to 60 mm,
A third group with a particle size of 60-40 mm and a particle size of 4
A fourth group of 0 to 20 mm and a grain size of 20 to 13
mm and the fifth group. From each of these groups, the weight% is 5% for the first group, 12.5% for the second group, and 20% for the third group.
27.5% of the 4th group and 35% of the 5th group
Each medium stone is selectively taken out so that

The medium stones synthesized as described above are stacked inside a cylindrical drum of the same crushed sand manufacturing apparatus as described in the above-mentioned "Prior art" section, and stirred with raw sand and water. The amount of medium stones stacked in this case is within the range of 1/3 to 1/4 of the inner peripheral surface diameter L of the cylindrical drum, as shown in FIG. That is, the upper surface of the stack of medium stones is set within the range shown by the hatched portion M in the figure. Therefore, when the medium stone is worn down and reaches the lower limit (1/4 of L) with stirring by the rotation of the cylindrical drum, the medium stone is supplemented to prevent the medium stone from falling below the lower limit. The amount of stones is the upper limit (1 / L of L
3), so that 1/3 to 1 of L
It should be within the range of / 4. This is because when the amount of medium stones deviates from the above range, a good stirring action cannot be performed, and for example, when the amount of medium stones is too large, the movement of medium stones is restricted, which is an optimum condition. If the amount of medium stones is too small, sufficient movement for stirring is prevented, and if the amount of medium stones acts on the raw sand varies, the optimum grinding action cannot be performed due to insufficient weight or the like. The reason is that. In this case, as the raw sand, sea sand having a particle diameter of 5 mm or less, mountain sand, dust collected at a quarry, or the like is used.

Regarding the amounts of water and raw sand to be fed, while the raw sand and water are continuously fed into the inside of the tubular drum, the tubular drum is rotated, and the amount of raw sand and the amount of water fed in this state are set. As a result of an experiment in which the state such as the fluidity of the raw sand is determined by appropriately changing the input amount of the raw sand, as shown in the graph of FIG. 3, the input amount of the raw sand and the input amount of water are proportional. Alternatively, they have found that it is optimal to have a substantially proportional relationship. This Figure 3
The relationship shown in the graph is invariable even if the size or the rotation speed of the cylindrical drum changes.

Then, with the medium stones being loaded into the cylindrical drum up to about 1/3 of L, the cylindrical drum is rotated at a rotation speed of 26 rpm, and the water passage time in this state, that is, the cylindrical drum The time from when water was poured into the inside until it was taken out from the outlet was measured. In this measurement, a cylindrical drum with a diameter of 120 cm (inner diameter of 116.5 cm) and a length of 200 cm was used.
A total of 930 kg of medium stones were piled up to cm. The measurement result is shown in the graph of FIG.

Next, the water passage distance is calculated by multiplying the water passage time, which is the result of this measurement, the circumference of the cylindrical drum, and the rotational speed of the drum. The calculation result is shown in the graph of FIG. Then, the crushed sand obtained by actually stirring the raw sand, the medium stone and the water inside the cylindrical drum from the passage distance of the water shown in FIG. 5 is JIS A5.
Determine the water passage distance to meet the 004 standard and meet the JIS A 5308 standard. As a result, 10
It was found that a passing distance of 0 m to 150 m is optimum. Here, the above-mentioned JIS A 5004 has been described in the above-mentioned "Prior Art" column, and also JIS A 5308.
Is for determining whether or not the result of the alkali silica reactivity test is harmless. For example, JIS A 5308-1989 Annex 7 “Alkali silica reactivity test method for aggregates (chemical method)” and There is Appendix 8 “Testing method for alkali silica reactivity of aggregates (mortar bar method)”. If the result of the alkali-silica reactivity test is not harmless, it causes a problem such that the cement is combined with the alkali of the cement and expands to collapse the concrete, or when the reinforced concrete is used, the reinforcing bar corrodes. Therefore, prior to the actual stirring, it is preferable to perform the alkali silica reactivity test on the medium stone as well.

When actually stirring, for example, 20 t
In the case of a sand throw rate of / h, the water throw rate is set to 6.5 t / h based on the graph of FIG. 3, and the water passage time is about 37 seconds according to the graph of FIG. 4 and the graph of FIG. We know that the distance that water passes is about 60 m. In this case, it is optimal to set the water passage distance to 100 m to 150 m as described, so if the sand throwing amount is 20 t / h and the water throwing amount is 6.5 t / h, once the cylindrical drum is used. If the crushed sand taken out from the discharge port is put into the same cylindrical drum again and taken out from the discharge port, the water passage distance is calculated to be 120 m.
Therefore, the value falls within the above optimum range. In this way, high-quality crushed sand can be obtained by actually stirring the raw sand, the medium stones, and water under the condition that the water passage distance falls within the range of 100 m to 150 m.

In the above measurement, the diameter is 12
The rotation speed was set to 26 rpm because the cylindrical drum having a diameter of 0 cm was used. However, when the cylindrical drum having a diameter of 60 cm is used, the rotation speed is optimally set to 27 rpm. This is because if the number of rotations of the cylindrical drum is increased more than necessary, the peripheral velocity of the inner peripheral surface of the cylindrical drum increases and the medium stones are lifted to the upper part more than necessary, and only the impact force is excessive. This is because the frictional action is not performed and the rotation speed is made smaller than necessary, the peripheral speed becomes insufficient and the passage of the raw sand becomes abnormal. Therefore, it is necessary to change the rotation speed according to the diameter of the cylindrical drum so that the peripheral speed of the inner peripheral surface of the cylindrical drum becomes an appropriate value. In this case, when using the cylindrical drum having a diameter of 60 cm as described above, the medium stones are stacked in the same manner as described above and the rotation speed is 27 rpm.
The cylindrical drum is rotated with to measure the water passage time in this state, and the relationship between this water passage time and the amount of water thrown is shown in a separate graph, and this water passage time and the circumference of the cylindrical drum are shown. And the number of revolutions are multiplied to calculate the relationship between the amount of water thrown and the passage distance of water, and the calculation result is shown in a separate graph. Then, the amount of water thrown with respect to the amount of sand thrown is determined from the graph of FIG. 3, and the water passage distance is set to fall within the range of 100 m to 150 m based on the separately created graph.
In this way, the generated crushed sand, like the above,
It meets the JIS A 5004 standard and conforms to the JIS A 5308 standard.

[0015]

As described above, according to the method for producing crushed sand for concrete according to the present invention, the upper limit of the amount of medium stones stacked inside the cylindrical drum is 1 / the diameter of the inner peripheral surface of the cylindrical drum. 3 and its lower limit is set to 1/4 of the diameter of the inner peripheral surface of the cylindrical drum, so that it is always between these two,
The milling action on the raw sand is performed in an optimum state, which is very useful for obtaining high-quality crushed sand for concrete . Further, the relationships between the input amount and the input amount of water of the original sand as appropriate, that is, by which the proportional or approximately proportional relationship <br/>, various conditions such as the fluidity of the raw sand during agitation Is preferable, and the efficiency of the grinding action by the medium stone is further improved. Further, in the present invention,
Depending on the number of cylindrical drums, the raw sand is continuously stirred.
The raw sand to the internal stirring chamber of the cylindrical drum.
Determine the amount of water input to the internal stirring chamber based on
Based on the amount of water input to this internal stirring chamber.
And calculate the passage distance of water in the internal stirring chamber.
So that the passing distance of
Since the number of cylindrical drums to be used was decided,
The quality of the crushed sand produced can be further improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing an apparatus used for carrying out a method of the present invention.

FIG. 2 is a schematic side view for explaining the method of the present invention.

FIG. 3 is a graph showing the relationship between the input amount of water and the input amount of raw sand.

FIG. 4 is a graph showing a passage time of introduced water.

FIG. 5 is a graph showing the relationship between the amount of water input and the passage distance .

[Explanation of symbols]

 1 Cylindrical drum 3 Medium stone 4 Raw sand 5 Water 6 Crushed sand L Diameter of inner surface of cylindrical drum

Claims (2)

[Claims] 1. In a state in which a plurality of medium stones are stacked in an inner stirring chamber of a cylindrical drum, raw sand and water are charged into the inner stirring chamber, and the cylindrical drum is rotated by an operation of a driving device. , Thereby stirring the medium stone, the raw sand and the water in the internal stirring chamber, and taking out the crushed sand obtained by the stirring action together with the water from the internal stirring chamber ,
The amount of medium stones is 1/4 to the diameter of the inner peripheral surface of the cylindrical drum.
While maintaining within a height range of 1/3, the internal stirring
If necessary, the crushed sand taken out of the chamber can be stored in another cylindrical drum.
In the method for producing crushed sand for concrete which is again charged into the internal stirring chamber to continue stirring, the amount of raw sand to be charged into the internal stirring chamber is set, and subsequently,
The internal stirring is adjusted so that it is proportional or approximately proportional to the input amount of raw sand.
Set the amount of water input to the stirring chamber and continue to set the amount of water input.
Based on the above, the water that has been input is discharged from the internal stirring chamber.
Calculate the distance that passes through the internal stirring chamber until
However, the passing distance of water in the internal stirring chamber was set in advance.
The cylindrical drive used for stirring should be included in the optimum range.
Method for producing a concrete crushed sand, characterized in that the so that to determine the number of beam. 2. The maximum distance of water passing through the internal stirring chamber.
The suitable range is 100-150 m, The manufacturing method of the crushed sand for concrete of Claim 1 characterized by the above-mentioned.