JPH0357061B2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention relates to a method for producing salt-free aggregate, and its purpose is to crush acidic or neutral natural igneous rock with a silicic acid content of 59% or more. The resulting aggregate is made of so-called crushed sand, and it does not contain any salt that causes concrete to deteriorate and collapse over time.
The purpose of the present invention is to provide a salt-free aggregate production method that can provide aggregate with an extremely low content of powder (mm) sieve pass.

(Conventional technology and its drawbacks) Generally, crushed sand (aggregate obtained by crushing natural rock)
Generally, concrete walls are strongly alkaline, and the deterioration and collapse of concrete walls constructed using such alkaline aggregates over time has become a major social problem in recent years.

In other words, concrete walls constructed using basic mountain sand with a high alkaline content in the aggregate mixed as an extender for cement materials tend to crack and collapse after about 10 to 15 years, making buildings and buildings more susceptible to collapse. Accidents in which the inner walls of tunnels fall have occurred repeatedly and have become a social problem.

However, since there are restrictions on the extraction of natural river sand and sea sand, it is often necessary to procure aggregate from mountain sand. Rather, it often contains salt (basic sand with a high alkaline content), making unsalted natural sand extremely rare and in extremely limited supply.

Therefore, salt-free crushed sand is desired in the industry, but salt-free crushed sand has not yet been developed.

Therefore, the inventors attempted to produce salt-free crushed sand.

For example, by excavating igneous rocks such as cakouite, rhyolite, senryonite, andesite, and basalt, and other sedimentary rocks,
This is a prototype technology in which this natural rock is first coarsely crushed and adjusted, and the coarsely crushed rock is finely crushed to produce salt-free mountain sand.

That is, this technique involves first coarsely crushing and conditioning the igneous rock, and then finely crushing the coarsely crushed rock to produce salt-free mountain sand.

However, the crushed sand produced by this trial technique inevitably contained a large amount of washing loss (powder with a sieve pass of 0.074 mm), making it impossible to obtain aggregate of desirable quality.

Therefore, in an attempt to remove this washing loss (powder at a 0.074 mm sieve pass) in advance, the finely crushed rock is washed with running water, and this finely crushed stone is classified and used as aggregate. This aggregate was also not desirable because it did not contain sand with a sieve size of 0.3 to 0.15 mm, which improves the strength of concrete walls.

Furthermore, in order to improve the crushed sand aggregate obtained by this method, the finely crushed rock is washed and classified with running water, and then natural river sand or natural sea sand equivalent to a sieve size of 0.3 mm to 0.15 mm is added. There was also a method of producing aggregate with a suitable distribution of each particle size.
In this improvement method, basic sand was mixed in from the natural sand that was added at the end, and in the end it was not possible to obtain a salt-free aggregate.

Moreover, even if the natural sand added at the end is omitted, basic sand may still be mixed in, making it impossible to obtain a salt-free aggregate.

On the other hand, in order to improve the heat resistance of concrete, igneous rocks such as andesite and basalt are crushed into aggregate and other foam materials are used in the "method for manufacturing heat-resistant concrete" already disclosed in Japanese Patent Application Laid-open No. 58-69768. A technique for blending is disclosed.

Furthermore, in Japanese Patent Application Laid-Open No. 53-136929 "Construction Method for Concrete Floors", SiO ₂ 30-42%, CaO 36
45%, Al ₂ O ₃ 9-17%, and MgO 3-13%, a technique for making beautiful floors using artificial aggregate and cement has been disclosed, as disclosed in JP-A-53-136930.
In the publication "Aggregate for concrete", SiO ₂ 31~
42%, CaO 36-45%, _{Al2O3 9-17} %, MgO
Techniques for pulverizing artificial aggregate having a composition of 3 to 13% and using it as aggregate for concrete have been disclosed.

However, the SiO ₂ content is
Since basalt with an alkaline content of less than 50% is used, deterioration in alkaline strength is unavoidable, and there were problems with the stability of the concrete over time because there was no consideration given to removing impurities such as salt or adjusting particle size.

In addition, the latter ``Method for constructing concrete floors'' in JP-A-53-136929 and ``Aggregate for concrete'' in JP-A-53-136930 also contain silicic acid containing 31 to 42% SiO ₂ . It was found that in both cases, it was unavoidable that alkaline strength deterioration of the concrete would occur because a rare alkaline artificial aggregate was used.

Therefore, among natural rocks, the prototype technology of the inventors uses only igneous rocks with a clear chemical composition, and even if the igneous rocks are natural rocks, they are acidic or neutral natural rocks with a silicic acid content of 59% or more. Only igneous rocks, such as acidic rocks such as cakouite and rhyolite, and neutral rocks such as senryonite and andesite, are excavated and the SiO ₂ content is 50.
% or less” is not made from alkaline basalt, etc.
In addition, research has been conducted to develop an aggregate that clearly reduces the content of washing losses (powder at a 0.074 mm sieve pass) and does not contain salt.

(Solution Means) This invention was made to solve the above-mentioned drawbacks of the prior art, namely, it does not contain salt or basic sand, and the particle size distribution is from 5 mm to 0.15 mm.
This method has been completed to produce crushed sand aggregate that is uniformly distributed down to the mm sieve pass and meets JISA5005 Class I regulations.

That is, in this invention, an acidic or neutral natural igneous rock with a silicic acid content of 59% or more is dug down, and this natural igneous rock is first coarsely ground to a particle size of about 150 mm sieve pass. After rough crushing, the rock is dried and finely crushed to adjust the particle size to a 5mm sieve pass.
Next, this finely crushed stone is divided into 0.074 by an air classifier.
This invention relates to a method for producing salt-free aggregate, which comprises removing powder passing through a mm sieve and adjusting the particle size distribution to 98% or more with a 5 mm to 0.074 mm sieve.

(Example) An embodiment of this invention method will be described in detail below.

The acidic or neutral natural igneous rock with high silicic acid (SiO ₂ ) content used in this invention is
Hanaoka Rock ( _SiO2 69.92%), Andesite (SiO2 59.59
%), liumonite (SiO ₂ 72.60%), senryonite (SiO ₂ 59.77%), etc. In this invention, basic rocks such as basalt (SiO ₂ 48.75%) and sedimentary rocks whose composition is unknown are not used.

Such rocks are excavated in a rocky area, and adhering soil, such as sand, adhering to the excavated rock is washed with water.

The washed rock is further crushed using a crusher and the particle size is adjusted to a 150 mm sieve pass using a vibrating sieve.

In order to adjust this particle size to a 150mm sieve pass,
The pulverizing step using the crusher and the classifying step using the vibrating sieve are repeated.

In addition, water may be added in the crushing process if necessary to avoid heating of the crusher.

Next, the crushed rock obtained by rough crushing whose particle size has been adjusted to a sieve pass of 150 mm is either temporarily stored or finely crushed without storage.

This fine grinding is performed for the purpose of passing through a 5 mm sieve.

This crushing device is designed to supply hot air into the device (while drying the wet, coarsely crushed rock).
A ball mill that grinds with steel balls, that is, an El-Fall type mill, can be preferably used.

Through this process of drying and pulverizing, even if salt, dust, dirt, etc. are contained, these impurities are separated from the crushed igneous rock and pulverized into a fine powder.

Incidentally, the fine powder generated during this pulverization is removed using a cyclone or the like, and this fine powder is collected and used for seedbeds or asphalt addition.

This finely crushed stone is passed through a 5 mm sieve using a vibrating sieve.

The crushed stone with a 5 mm sieve mesh is subjected to a fine crushing process again.

Next, this finely crushed stone is passed through an air classifier.
Removes powder from 0.074mm sieve pass, 5mm to 0.074
Adjust the particle size distribution to 98% or more on the mm sieve.

In the method of this invention, this step is the most important step. Conventionally, there is no equipment that can efficiently remove powder with a sieve pass of 0.074 mm, and in particular, the classification of crushed sand is performed using wet classification (using water). This overturns the common technical wisdom that conventional dry-type classification equipment must be used with precision equipment such as those used in the chemical industry, which scatters dust around the equipment and degrades the working environment for workers. It was believed that dry classifiers that do not produce a high degree of separation could not be used in processes such as civil engineering work because they would not improve work efficiency.

However, as mentioned above, in the wet classifier, not only the powder in the 0.074 mm sieve pass but also crushed sand with a particle size of 0.3 mm to 0.074 mm sieve pass, which affects concrete strength, was washed away.

The dry classifier shown in Figure 1 is an air classifier created by this inventor, and is suitable for rough work processes such as civil engineering work, and has good workability and reliably removes only powder with a sieve pass of 0.074 mm. can.

Furthermore, by using this dry air classifier, salt that is separated from the crushed igneous rock by being crushed while drying in the crushing device and made into a fine powder;
Among impurities such as dust and dirt, impurities that have not been removed by the cyclone etc. can also be blown away at the same time.

The air classifier 1 shown in FIG. 1 will be explained below, but the method of this invention is not necessarily limited to this air classifier, and other air classifiers may also be used. Any device can be used as long as it has a structure that can remove only the powder in the eye path.

In Fig. 1, 2 is a crushed sand inlet, 3 is a rotating drum, and 4 is threads or blades that are installed on the inner wall of the drum 3 in a continuous spiral manner or at regular intervals. be.

5 is a crushed sand outlet, 6 is a compressed air outlet, 7
8 is an air delivery port, 8 is a cyclone, 9 is a bag filter, 10 is a vacuum pump, 11 is a suction port of this vacuum pump 10, and 12 is a compression port.

In order to carry out the classification process according to the present invention using the air classifier 1 having such a configuration, first 5 steps are required.
A crushed stone having a mesh size of mm is introduced through the crushed sand inlet 2, and the drum 3 is rotated.

At the same time, the vacuum pump 10 is activated to remove the drum 3.
Compressed air is sent into the drum 3, and at the same time, the air inside the drum 3 is sucked through the bag filter 9 and the cyclone 8.

At this time, the compressed air and suction pressure as well as the rotational speed of the drum 3 are selected appropriately and set to conditions that can reliably remove only the powder with a sieve pass of 0.074 mm.

The crushed sand is agitated by threads or blades 4 in the drum 3, moves within the drum 3 toward the crushed sand outlet 5, and is discharged from the crushed sand outlet 5 to the drum 3.

The fine powder passing through the 0.074 mm sieve is captured by a bag filter 9 and a cyclone 8.

Incidentally, the finely pulverized rock collected by the bag filter 9 and the cyclone 8 may be used as an asphalt additive or a seedbed.

The crushed sand discharged from the crushed sand outlet 5 to the outside of the drum 3 does not require a drying process again, and can be used as it is by being mixed into mortar as an aggregate-free material.

(Effects of the Invention) As detailed above, the method for producing salt-free aggregate according to the present invention involves digging down acidic or neutral natural igneous rock with a silicic acid content of 59% or more, and first reducing the natural igneous rock to 150 mm. Roughly grind and adjust the particle shape to about the size of a sieve pass,
This roughly crushed rock is finely crushed while drying to adjust the particle size to a 5mm sieve pass, and then the finely crushed stone is passed through an air classifier to remove powder with a 0.074mm sieve pass, and the grain size is adjusted to a 5mm sieve pass. 98 to particle size distribution of 0.074mm sieve mesh
Since it is a salt-free aggregate manufacturing method that involves adjusting the amount of salt to 10% or more, it has the following effects.

Since natural igneous rock is used as the starting material and a manufacturing process that does not mix salt, it contains almost no salt.Furthermore, after drying and pulverizing, the fine particles are blown away using an air classifier, so there is no salt, dirt, dust, etc. Even if it contains impurities, it can be classified and removed, making it possible to produce high-quality salt-free aggregate that does not contain salt.

This is so-called crushed sand obtained by crushing natural rocks, and since the natural rocks used as raw materials are limited to igneous rocks with a silicate content of 59% or more and no other igneous rocks or sedimentary rocks are used as raw materials, there is no basic sand content. It is possible to produce aggregates that do not contain

Therefore, this aggregate is an aggregate that does not cause concrete to degrade and disintegrate over time due to alkaline deterioration.In addition, the content of washing loss (powder in the 0.074 mm sieve pass) that causes concrete strength deterioration is extremely small, and increase strength
The aggregate contains particles with a sieve size of 0.3mm to 0.074mm and passes JIS standard I class.

Furthermore, it has good workability and is suitable for mass production.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an air classifier used in one embodiment of the method of this invention. 1...Air classifier.

Claims (1)

[Claims] 1. Acidic or neutral natural igneous rock with a silicic acid content of 59% or more is excavated, and this natural igneous rock is first
Roughly grind and adjust the grain shape to about 150mm sieve pass.
This roughly crushed rock is finely crushed while drying to adjust the particle size to a 5mm sieve pass, and then the finely crushed stone is passed through an air classifier to remove powder with a 0.074mm sieve pass, and the grain size is adjusted to a 5mm sieve pass. 98 to particle size distribution of 0.074mm sieve mesh
% or more.