JP4933969B2 - Equipment and method for reducing the water absorption rate of recycled fine aggregate - Google Patents

Description

  The present invention relates to equipment and a method for reducing the water absorption rate of recycled fine aggregate having a particle size of less than 5 mm among recycled aggregates obtained by crushing concrete waste.

  Of the architectural waste generated in large quantities due to the dismantling, improvement and reconstruction of buildings, concrete waste accounts for about 40%. About 50% of this concrete waste is reused as roadbed material for road paving and backfilling, but the remaining 50% is actually discarded.

  On the other hand, a large amount of aggregate is used for concrete, but it is becoming difficult to collect high-quality natural aggregates such as gravel and river sand, which eliminates the problem of depletion of aggregate resources and makes effective use of concrete waste. From both sides, it has been studied to recycle and collect aggregates from waste concrete and reuse them as coarse aggregates and fine aggregates.

  In order to regenerate and collect aggregate from waste concrete, a method of crushing waste concrete with a crusher such as a cone crusher, a jaw crusher, or a ball mill has been conventionally attempted. However, in this method, if the material is retained in the crusher for 30 minutes or more and is not subjected to friction crushing, the most important absolute dry density and water absorption standards (absolute absorption) among the quality regulations established for JIS A5021 recycled aggregate H for concrete. It was difficult to satisfy a dry density of 2.5 kg / L or more and a water absorption of 3.5% or less.

  On the other hand, the applicant of the present invention, in Patent Document 1, by setting the filling rate and combination of the crushing medium of the vibration type crusher as a specific condition, a recycled aggregate that satisfies the standard of the absolute dry density and the water absorption rate. A method has been disclosed that can be reliably manufactured with less power.

However, when the regenerated aggregate obtained by this method was evaluated precisely, it was found that some regenerated fine aggregates having a particle size of less than 5 mm did not satisfy the water absorption criteria.
JP 2006-111523 A

  The problem to be solved by the present invention is to provide a facility and method for reducing the water absorption rate of recycled fine aggregate having a particle size of less than 5 mm.

  In order to solve the above-mentioned problems, the inventors of the present invention have conducted research. As a result, it is possible to reduce the water absorption rate by grinding a regenerated fine aggregate having a particle size of less than 5 mm using an inertia cone grinder. As a result, the present invention has been completed.

That is, the facility for reducing the water absorption rate of the recycled fine aggregate of the present invention is a facility for reducing the water absorption rate of the recycled fine aggregate having a particle size of less than 5 mm among the recycled aggregates obtained by crushing the concrete waste. An inertia cone grinding machine for grinding the recycled fine aggregate, and accepting the milled product discharged from the inertia cone grinding machine, and classifying the recycled fine aggregate and cement fine particles in the ground product. And a classifier for obtaining recycled fine aggregate, wherein the inertia cone grinder includes a shell, a spherical seat support provided on the shell, a spherical seat attached to the spherical seat support, A conical head supported on a spherical seat and driven to rotate eccentrically, a mantle attached to the conical head, a cone cave attached to the shell opposite to the mantle, and an unbalance attached below the mantle Hue And a preparative, by the conical head is rotated while the eccentric on the spherical seat state, and are not grinding the reproduced fine aggregate between mantle and Konkebu further reproduction fine aggregate It is characterized by having a classification mechanism for classifying and removing fine powder having a particle size of 0.6 mm or less in the regenerated fine aggregate in a stage before being put into the inertia cone grinder .

The method for reducing the water absorption rate of the recycled fine aggregate according to the present invention is a method for reducing the water absorption rate of the recycled fine aggregate having a particle size of less than 5 mm among the recycled aggregates obtained by crushing the concrete waste. A grinding step of grinding the recycled fine aggregate with an inertia cone grinding machine, and classifying the recycled fine aggregate and cement fine particles in the ground material discharged from the inertia cone grinding machine. A classifying step for obtaining a fine aggregate, and as the inertia cone grinder, a shell, a spherical seat support provided on the shell, a spherical seat attached to the spherical seat support, and a spherical seat A conical head that is supported and rotated eccentrically, a mantle attached to the conical head, a cone cave attached to the shell opposite the mantle, and an unbalanced weight attached below the mantle Wherein said by the conical head is rotated while the eccentric on the spherical seat, using those grinding playback fine aggregate between mantle and Konkebu, prior to about the milling step, reproducing fine The fine powder having a particle size of 0.6 mm or less in the aggregate is classified and removed .

  In the present invention, there is provided a circulation line for returning the regenerated fine aggregate obtained by the classifier to the inertial conical grinder, and the water absorption of the regenerated fine aggregate is performed by repeating the grinding step and the classification step. The rate can be reliably reduced until it meets the required criteria. Further, by adjusting the degree of repetition of the grinding step and the classification step, it is possible to control the quality such as the water absorption rate of the regenerated fine aggregate so as to achieve the desired quality.

In the present invention, the fine particle having a particle size of 0.6 mm or less, preferably 0.3 mm or less in the recycled fine aggregate is classified before the recycled fine aggregate is put into the inertial conical grinder. the classification mechanism for removing provided, this before as milling step by the following particle size 0.6mm playing fine aggregate, preferably removed and classified following fine grain size 0.3 mm. That is, the fine particle having a particle size of 0.6 mm or less, particularly 0.3 mm or less, in the recycled fine aggregate contains a large amount of cement fine particles, and is compressed when ground by an inertia cone grinder. It becomes a pressure piece (secondary particle) of about 10 mm. Originally, this pressed piece is intended to be removed to the cement fine particle side by a classifier after the grinding process. However, since the classifier is subjected to the classification action with the pressed piece, it is mixed into the regenerated fine aggregate on the coarse grain side and absorbed. Causes the rate to rise (prevent the decline). Therefore, the particle size 0.6mm following fines in reproducing fine aggregate, you remove it ago milling step.

  Here, the inertia cone grinding machine used in the present invention has an unbalanced weight below the mantle, and the grinding force can be easily changed by adjusting the unbalanced weight and changing the rotational speed of the cone head. can do. In particular, the adjustment of the grinding force by changing the rotation speed of the conical head can be performed arbitrarily during operation according to the properties of the recycled fine aggregate (the material to be ground) by adopting inverter control. However, it does not overgrind and only the cement content on the surface of the regenerated fine aggregate can be peeled off. In other words, the surface of the regenerated fine aggregate is set to a “grinding” grinding force that can peel only the cement content on the surface of the regenerated fine aggregate, and is ground at high speed rotation (a large amount of grinding is performed with a low grinding force). Only the cement content can be efficiently peeled off, and the water absorption rate can be reduced.

On the other hand, for example, in the case of a cone crusher, the grinding force cannot be adjusted. Therefore, overgrinding occurs in a normal exit gap, and the aggregate portion is ground. Therefore, it is necessary to widen the exit gap so as not to overgrind. If the exit gap is widened, the passage speed is increased accordingly, the grinding time (retention time in the grinding machine) is shortened, and the number of times of grinding is reduced. Normally the rotational speed of the cone crusher is ^{250min -1 ~300min} -1, grinding砕回number HiMigaku grind undergoes grinding砕中, when if grinding time between (the attritor residence time) and 1 minute , 250 to 300 times.

In the case of the inertia cone grinder used in the present invention, since the grinding force can be adjusted as described above, the outlet gap is reduced with a low grinding force to reduce the passage speed, and the grinding time (retention time in the grinder). Can be lengthened. In addition, the normal rotational speed of the inertia cone grinder is 800 min ^{−1 to} 1150 min ⁻¹ , which is 3 to 4 times that of the cone crusher. If the internal residence time is also 1 minute, it is 800 to 1150 times, 3 to 4 times the cone crusher.

  According to the present invention, it is possible to reliably and efficiently reduce the water absorption rate of recycled fine aggregate having a particle size of less than 5 mm.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows the equipment configuration of equipment for reducing the water absorption rate of the recycled fine aggregate of the present invention.

  The concrete waste material is preliminarily crushed to a particle size of 40 mm or less and continuously fed into the vibration crusher 1. The drum-shaped crushing chamber 1a of the vibration crusher 1 is filled with two types, a large-diameter crushing medium rod having a rod diameter of about 50 to 30 mm and a small-diameter crushing medium rod having a rod diameter of less than 30 to about 19 mm. By vibrating the crushing chamber 1a with a vibrator, the cement attached to the aggregate surface is peeled off, and the size of the aggregate is crushed to a particle size of about 25 mm or less and discharged from the discharge port 1b. Classification air is introduced from the discharge port 1b, and fine powder (mainly cement) having a particle size of about 0.3 mm or less is discharged from the exhaust port 1c together with the classification air. The fine powder is sucked and transferred by the blower 7a, collected by the cyclone 5a and the bag filter 6a, and discharged as dust. That is, fine powder of about 0.3 mm or less is removed from the crushed material (recycled aggregate having a particle size of about 25 mm or less) by the classification mechanism using the classification air.

  The recycled aggregate having a particle size of about 25 mm or less from which the fine powder has been removed is applied to the screen 2 and screened. The screen 2 includes an upper screen 2a having a size of 20 mm and a lower screen 2b having a size of 5 mm, and coarse particles on the upper screen 2a are returned to the vibration crusher 1 and crushed again. Then, the aggregate having a particle size of less than 20 mm to 5 mm on the lower screen 2b is recovered as a recycled coarse aggregate. Further, the recycled aggregate having a particle size of less than 5 mm under the lower screen 2b is recovered as a recycled fine aggregate, and is then put into the inertia cone crusher 3.

  The inertia cone grinder 3 will be described in detail later. In the inertia cone grinder 3, the cement content on the surface of the regenerated fine aggregate is separated by the mutual grinding by the centrifugal grinding mechanism, and the bone The material is sized and discharged into round particles by mutual grinding.

  The ground product (mixture of recycled fine aggregate and exfoliated cement fine particles) discharged from the inertia cone grinder 3 is put into a ladder type wind power sorter 4 as a classifier. In the ladder-type wind power sorter 4, the introduced ground material passes through the zigzag from the top to the bottom and falls. At that time, only dust (mainly separated cement fine particles) is sucked and classified by the suction force of the blower 7b from the suction port 4a provided in the upper part of the main body. The sucked dust is collected by the cyclone 5b and the bag filter 6b. That is, the recycled fine aggregate from which the dust (cement fine particles) has been removed is discharged from the lower part of the main body of the ladder type wind power sorting device 4. A damper 4b is provided at the lower part of the main body, and 0 to 90% of the recycled fine aggregate discharged from the lower part of the main body is returned to the inertia cone grinder 3 through the circulation line 8, and the remaining 100 to 10% is good quality. Collect as recycled fine aggregate. Thus, by returning to 0-90%, grinding and classification are repeated again, and a desired fine recycled fine aggregate can be obtained.

  Here, the reason for circulating grinding by returning to 0-90% is that the concrete waste is a waste recovery product, the properties of the concrete aggregate (physical properties such as water absorption) and the type of cement used This is because the degree of grinding must be changed depending on the content in concrete and concrete, and further, the required physical properties of the desired recycled fine aggregate. That is, when the circulation rate is increased, a recycled fine aggregate close to the water absorption rate of the original aggregate can be obtained. If the water absorption rate of the recycled fine aggregate raw material is about 7 to 6% that satisfies the recycled fine aggregate M standard, it depends on the quality of the raw aggregate, but by adjusting the circulation rate, the recycled fine aggregate H It is possible to obtain a recycled fine aggregate having a physical quality that sufficiently satisfies the standard.

  Next, the structure of the inertia cone grinder 3 which plays an important role in the facility for reducing the water absorption rate of the recycled fine aggregate of the present invention will be described with reference to FIG.

  The inertia cone grinder 3 has an aggregate inlet 10 in the upper part, a spherical seat support 11 in the middle part, and a substantially cylindrical shell 13 having a bearing part 12 in the lower part supported by the vibration isolating rubber 14. A cone cave 15 having an inverted conical surface is attached to the lower portion of the aggregate inlet 10 of the shell 13, a spherical seat 16 is attached to the spherical seat support 11, and the lower bearing portion 12 is attached to the lower bearing portion 12. A drive shaft 20 driven from the motor 17 via the V belt 18 and the pulley 19 is supported. One end of a spindle shaft 21 capable of transmitting rotation and swinging is supported on the drive shaft 20, and the other end of the spindle shaft 21 is connected to the main shaft 22 so as to be swingable and swingable. An unbalanced weight 23 is attached to the lower part of the main shaft 22, and a conical head 24 supported on the spherical seat 16 is attached to the upper part. A mantle 25 is opposed to the cone cave 15 on the upper surface of the conical head 24. It is attached. The conical head 24 can rotate on the spherical seat 16 and can swing along the spherical surface. Reference numeral 26 denotes a dust seal 26 provided on the spherical seat support 11 so as to seal between the conical head 24 and the spherical seat support 11.

  The grinding action of the inertia cone grinding machine 3 will be described with reference to FIG.

  First, at the left end of the crushing chamber constituted by the cone cave 15 and the mantle 25 in the state of FIG. 3A, the mantle 25 is in a state where the gap with the cone cave 15 is close to 0 mm due to the centrifugal force generated by the rotation of the unbalance weight 23. Thus, the inner surface of the corn cave 15 rolls to grind the recycled fine aggregate 28. Since the crushing chamber vibrates at the right end, the filled state of the recycled fine aggregate becomes a high density state.

  Next, when the mantle 25 rolls to the state shown in FIG. 3B, the recycled fine aggregate that has been compressed and ground is discharged by gravity and vibration at the left end of the crushing chamber. Further, when the mantle 25 rolls to the state of FIG. 3C, the reclaimed fine aggregate is filled at the left end of the crushing chamber, and at the right end, the regenerated fine aggregate in the high density state is filled, contrary to FIG. 3A. Since the rolling between the mantle 25 and the corn cave 15 is close to 0 mm, there is no escape space for the regenerated fine aggregate, the cement paste on the surface of the aggregate is separated from the particles by grinding, and the regenerated fine bone The material becomes rounded particles.

In the inertia cone grinder 3, the grinding force can be easily changed by adjusting the unbalance weight 23 and changing the rotational speed of the cone head 24 as described above. For example, the fixed weight of the unbalance weight 23 is fixed. By shifting the angular position, the aggregate itself is not crushed, and it can be adjusted to the last grinding force at which only the cement on the surface of the aggregate peels. And according to this inertia cone grinder 3, in the conventional grinder, the two synergistic effects of (1) long residence time in the grinder and (2) high rotation speed are combined. While it is necessary to repeat the crushing process by the grinder 3 to 4 times, the inertia cone grinder has the quality regulation defined in the recycled aggregate certification standard for building structures in one or the continuous grinding process. Among them, the most important dry density of 2.5 kg / cm ³ or more and water absorption of 3.5% or less can be satisfied.

  Moreover, in a cone crusher, since 3 to 4 times must be crushed with the same crusher, a process process becomes a batch process and a continuous process cannot be performed. In contrast, in the inertia cone crusher, a single treatment or a continuous circulation treatment may be used, so that a continuous treatment process can be realized.

  As described above, according to the present invention, (1) continuous processing can be performed, so that production efficiency can be improved. (2) processing according to the quality of the recycled fine aggregate raw material or required quality can be performed. The product can be saved, and a great effect can be obtained in improving productivity.

The recycled fine aggregate raw material (absolute dry density 2.28 g / cm ³ , water absorption 6.61%) collected under the lower screen 2b in FIG. 1 is used as a test material, and this is used as the rotational speed of the inertia cone crusher 3. Grinding to 820 min ⁻¹ , adjusting the amount of suction from the suction port 4a of the ladder-type wind power sorting device 4, and obtaining a recycled fine aggregate with a classification point of 1.0 mm or a classification point of 0.3 mm as a target. At this time, the circulation rate of returning from the lower part of the main body of the ladder-type wind power sorter 4 to the inertia cone grinder 3 was set to 0%. That is, the recycled fine aggregate raw material was ground once.

The physical properties of the obtained recycled fine aggregates were as follows: the absolute dry density was 2.58 g / cm ³ , and the water absorption was 3.10%. Moreover, in the test result which attracted | sucked aiming at the classification point 0.3mm, the absolute dry density was 2.56g / cm < ³ > and the water absorption rate was 3.42%. All of them satisfied the quality regulations defined for recycled aggregate H for JIS A5021 concrete.

Recycled fine aggregate raw material with a water absorption rate of 7.5% recovered under the lower screen 2b in FIG. 1 is used as a test material, and this is ground at a rotational speed of the inertia cone grinder 3 of 820 min ⁻¹ to obtain a ladder type wind power. The amount of suction from the suction port 4a of the sorting device 4 was adjusted, and a recycled fine aggregate was obtained with a classification point of 0.3 mm as a target. At this time, the circulation rate returned from the lower part of the main body of the ladder-type wind power sorter 4 to the inertia conical grinder 3 was changed, and the relationship between this circulation rate and the water absorption rate of the obtained recycled fine aggregate was investigated.

  The result is shown in FIG. As shown in the figure, when the circulation rate is increased, the water absorption rate is decreased. In this example, by setting the circulation rate to about 50%, the quality regulation (water absorption rate 3) defined for the recycled aggregate H for JIS A5021 concrete is used. Regenerated fine aggregate satisfying .5% or less) was obtained.

  The present invention can be applied to equipment for remanufacturing and manufacturing fine aggregate from concrete waste.

The equipment structure of the equipment which reduces the water absorption rate of the reproduction | regeneration fine aggregate of this invention is shown. The structure of the inertia cone grinder used by this invention is shown. The operation of an inertia cone grinder is shown. The relationship between the circulation rate and the water absorption rate of recycled fine aggregate is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vibrating crusher 1a Crushing chamber 1b Discharge port 1c Exhaust port 2 Screen 2a Upper screen 2b Lower screen 3 Inertial conical grinder 4 Ladder type wind sorter 4a Suction port 4b Damper 5a, 5b Cyclone 6a, 6b Bag filter 7a, 7b Blower 8 Circulation line 10 Aggregate inlet 11 Spherical seat support 12 Bearing portion 13 Shell 14 Vibration-proof rubber 15 Cone cable 16 Spherical seat 17 Motor 18 V-belt 19 Pulley 20 Drive shaft 21 Spindle shaft 22 Main shaft 23 Unbalanced weight 24 Conical head 25 Mantle 26 Dust seal 27 Spherical bearing

Claims (2)

Among the recycled aggregates obtained by crushing waste concrete, it is a facility that reduces the water absorption rate of recycled fine aggregates having a particle size of less than 5 mm,
An inertia cone grinder for grinding the recycled fine aggregate;
It is equipped with a classifier that receives the milled product discharged from the inertia cone grinder, classifies the recycled fine aggregate and cement fine particles in the milled product, and obtains the recycled fine aggregate,
The inertia cone grinder includes a shell, a spherical seat support provided on the shell, a spherical seat attached to the spherical seat support, a cone supported on the spherical seat, and rotationally driven while being eccentric. A head, a mantle attached to the conical head, a cone cave attached to the shell opposite to the mantle, and an unbalanced weight attached to the lower part of the mantle, wherein the conical head is eccentric on the spherical seat by being rotated while state, and are not grinding the reproduced fine aggregate between mantle and Konkebu,
Furthermore, the water absorption of the regenerated fine aggregate is equipped with a classification mechanism that classifies and removes fine powder having a particle size of 0.6 mm or less in the regenerated fine aggregate before the regenerated fine aggregate is put into the inertia cone grinding machine. Equipment that reduces the rate. Among the recycled aggregates obtained by crushing concrete waste, it is a method of reducing the water absorption rate of recycled fine aggregate having a particle size of less than 5 mm,
A grinding step of grinding the recycled fine aggregate with an inertia cone grinding machine;
Classifying the recycled fine aggregate and cement fine particles in the ground product discharged from the inertia cone grinder to obtain a recycled fine aggregate,
As the inertia cone grinder, a shell, a spherical seat support provided on the shell, a spherical seat attached to the spherical seat support, a cone supported on the spherical seat and driven to rotate while being eccentric. A head, a mantle attached to the conical head, a cone cave attached to the shell opposite to the mantle, and an unbalanced weight attached to the lower part of the mantle, wherein the conical head is eccentric on the spherical seat By using the one that grinds recycled fine aggregate between the mantle and corn cave by being driven while rotating ,
A method of reducing the water absorption rate of the regenerated fine aggregate by classifying and removing fine powder having a particle size of 0.6 mm or less in the regenerated fine aggregate before the grinding step .

Images