JP2012012293A - Lightweight hollow particles with suppressed bulk density change and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for producing lightweight hollow particles such as perlite with suppressed bulk density change.SOLUTION: The method for producing lightweight hollow particles is characterized in that lightweight hollow particles are pneumatically transported through a pipe line having corner parts, and lightweight hollow particles are chosen using, as an index, a change in bulk density before and after pneumatic transportation by destruction of a part of lightweight hollow particles by collision with the corner parts of the pipe line. For example, lightweight hollow particles are pneumatically transported under an air pressure of 5-100 m/sec through a pipe line having 1-25 (n) corner parts whose angle (R) is 80-135°, within the range of 100≤n×V×(90/R)≤500, and lightweight hollow particles having a bulk density ratio (B/A) of ≤2 or a bulk density difference (B-A) of ≤0.2 g/cmare recovered, wherein A represents a bulk density before pneumatic transportation, and B represents a bulk density after pneumatic transportation.

Description

The present invention relates to a method and apparatus for producing lightweight hollow particles having a small change in bulk density. More specifically, the present invention relates to a method and apparatus for producing lightweight hollow particles in which bulk density changes are suppressed for lightweight hollow particles such as pearlite obtained by heating and foaming a mineral material.

Perlite has independent bubbles inside, and is used as a lightweight aggregate. Perlite is used as a weight-reducing material because of its low bulk density, and it is used as a heat insulating material, a heat insulating material, etc., because it has voids inside the particles. As the weight reducing material such as pearlite, a material having a bulk density suitable for the final product to have a target density is used, and the amount of addition is adjusted. Therefore, the bulk density of pearlite is an important quality control factor.

On the other hand, pearlite is a lightweight hollow particle with an internal space, and the shell thickness is very thin compared to fly ash balloons and glass balloons, and the thickness of the shell is generally several tenths or less of the outer diameter. It is a structure that is very easy to collapse. Moreover, since it is manufactured from a natural raw material, the dispersion | variation in the intensity | strength of each pearlite particle | grain itself is large. For this reason, part of the product is damaged during transportation, storage, packaging, bulk car or truck after production, or transportation, and the bulk density gradually increases. In particular, when pearlite is pneumatically transported from the manufacturing process to the storage process using a transport pipe, the pearlite impacts the wall surface and is destroyed, causing an increase in bulk density.

The durability against air transportation depends on the strength of the pearlite particles, but if the foaming rate is reduced to increase the strength of the pearlite, the lightness will be lost, while if the foaming rate is increased to increase the lightness, There is a problem that the particle strength decreases.

As a method of increasing the strength of pearlite, a method of heating and foaming after preheating the raw material powder is known. Specifically, in pearlite made from nacre, the moisture contained in nacre acts as a foaming agent, the moisture evaporates by heating, and foams by the vaporized vapor when the temperature reaches the melting point or higher. If the amount of water is too large at this time, excessive foaming occurs, and the shell becomes thin and the strength is weakened. Therefore, there is known a method for preventing excessive foaming by preheating to control the water content in the pearlite and then heating to the foaming temperature (Patent Documents 1 and 2).

In addition, after the raw material powder is preheated to adjust the moisture content, this raw material powder is mixed with the high melting point fine powder and foamed, and then the resulting foam (perlite) is separated from the high melting point fine powder. A method is also known (Patent Document 3). This production method is a method of producing spherical pearlite with less surface irregularities by uniformly foaming a preheated raw material powder into a high melting point fine powder and foaming.

JP-A-7-277851 JP 2007-320805 A Japanese Patent No. 3528390

Even if manufactured by the above-described conventional manufacturing method, damage to pearlite in the transportation process or storage process after manufacture cannot be avoided at all, and if the amount of damage is large, the bulk density of pearlite will change significantly.

In the present invention, in order to obtain light-weight hollow particles with stable quality from light-weight hollow particles containing brittle particles produced in this way, the bulk density change after production of inorganic hollow light-weight particles such as pearlite is suppressed in advance. Specifically, a method for producing high-quality lightweight hollow particles having a small change in bulk density and a method for producing the lightweight hollow particles by selecting one having a change amount of the bulk density before and after pneumatic feeding below a reference amount. provide.

[1] The amount of change in the bulk density before and after pneumatic feeding is caused by pneumatically feeding lightweight hollow particles through a pipe having a corner, and a part of the lightweight hollow particles colliding with the corner of the pipe and being broken. A method for producing lightweight hollow particles, characterized in that lightweight hollow particles are selected as an index.
[2] The amount of change in the bulk density before and after pneumatic feeding is expressed as the bulk density ratio (B / A) of the bulk density B after pneumatic feeding to the bulk density A before pneumatic feeding, or the difference in bulk density (BA). The method for producing lightweight hollow particles according to the above [1], wherein the lightweight hollow particles are selected using as an index the change in the bulk density of the lightweight hollow particles before and after pneumatic feeding.
[3] Lightweight hollow particles as described in [2] above, which collect lightweight hollow particles having a bulk density ratio (B / A) of 2 times or less or a bulk density difference (BA) of 0.2 g / cm ³ or less. Manufacturing method.
[4] When pneumatically sending light-weight hollow particles at a flow rate of 5 to 100 m / sec through a pipe having a corner number (n) of 1 to 25 and a corner angle (R) of 80 ° to 135 °, Lightweight hollow particles as described in [3] above, wherein the number of corners (n), angle (R), and air pressure (V) are selected so as to be within the range of the following formula [1], and the lightweight hollow particles are pneumatically fed. Manufacturing method.
100 ≦ n × V × (90 / R) ² ≦ 500 [1]
[5] The bulk density ratio (B / A) before and after pneumatic feeding when the lightweight hollow particles are pneumatically fed through a pipe line having a corner against which the lightweight hollow particles abut is less than double, or the bulk density difference (BA) Lightweight hollow particles having a particle size of 0.2 g / cm ³ or less.
[6] The lightweight hollow particles according to the above [5], which are pearlite obtained by heating and foaming a mineral material or inorganic hollow particles obtained by heating and foaming inorganic particles contained in a foaming agent.
[7] It has a conduit through which lightweight hollow particles flow, and a pneumatic feeding means for flowing the lightweight hollow particles into the conduit, and the conduit is formed with corners against which the lightweight hollow particles flowing in the tube abut. In addition, a light hollow particle manufacturing apparatus with a small density change, characterized in that a filter part for allowing air to escape and collect light hollow particles is provided at the rear part of the pipe.
[8] The number of corners (n) is 1 to 25, the angle (R) of the corners is 80 ° to 135 °, and light-weight hollow particles are pumped with an air pressure (V) of 5 to 100 m / sec. [7] A lightweight hollow particle production apparatus according to [7].

In the production method of the present invention, when light-weight hollow particles are pneumatically fed through a pipe having a corner, the light-weight hollow particles that are brittle and easily broken collide with the corner of the pipe and are broken, thereby breaking the bulk of the light-weight hollow particles. Since the density changes, the amount of change in the bulk density before and after the pneumatic feeding is used as an index, and lightweight hollow particles with a small amount of change are selected, so that high-quality lightweight hollow particles with a small change in bulk density are obtained when the product is used. be able to.

The production method of the present invention can be applied not only to pearlite obtained by heating and foaming a mineral material, but also to lightweight hollow particles obtained by heating and foaming inorganic particles containing a foaming agent.

The graph which shows the relationship between the parameter | index of a damage state, and bulk density ratio about pearlite B2. The graph which shows the relationship between the parameter | index of a damage state, and bulk density ratio about pearlite B3 The graph which shows the relationship between the parameter | index of a damage state, and bulk density ratio about pearlite C1 Schematic diagram of pneumatic transport equipment

Hereinafter, the present invention will be specifically described based on embodiments.
The present invention pneumatically feeds light hollow particles through a pipe having a corner, and the amount of change in bulk density before and after pneumatic feeding due to a portion of the light hollow particles colliding with the above-mentioned corner of the pipe and being destroyed. It is a manufacturing method of the lightweight hollow particle characterized by selecting a lightweight hollow particle as a parameter | index.

In the production method of the present invention, the lightweight hollow particles are pearlite obtained by heating and foaming a mineral material, inorganic lightweight hollow particles obtained by heating and foaming inorganic particles containing a foaming agent, and the like. Hereinafter, pearlite will be described as a representative example.

Perlite is produced by heating and foaming mineral materials. Specifically, the raw material is nacre, pine sebite, obsidian, shirasu, etc. with water inside. Alternatively, the silica glass raw material powder is granulated by adding a foaming agent such as SiC, or fly ash containing unburned carbon inside. The raw material is inorganic kiln containing foaming agent. The raw material is heated and foamed in a heating furnace such as a furnace or a fluidized bed firing furnace. The quality of the manufactured pearlite is evaluated by the bulk density, the floating rate, the particle size, and the like, and those having a quality corresponding to the application are used.

Usually, manufactured pearlite is stored in a product silo or the like, but transportation to the silo is mainly performed by pneumatic transportation. In pneumatic transportation, pearlite flows through the transport pipe by compressed air, so the pearlite flowing in the pipe receives air pressure. Further, since there is a curved portion in the middle of the path, the pearlite flowing in the tube is often rubbed against the tube wall. Furthermore, impact and pressure are applied to the pearlite during loading into the silo, storage, and transportation by truck or lorry vehicle. At this time, the weak bulky pearlite is broken, and if the broken fine particles are included, the overall bulk density is increased. In addition, if a part of the pearlite shell breaks, the closed cells inside become bubbles that are open to the outside (communication bubbles), and water etc. enters the internal space, so the floating rate is greatly reduced. .

In general, the degree of destruction of pearlite depends on its strength. The strength of pearlite can be measured by a uniaxial compression test or a hydrostatic pressure test. However, even if it is determined that the strength is high by these measurement methods, it may be fragile. For example, when the mass of the pearlite particles is large, the collision energy increases, so that the particles are easily broken.

Therefore, the manufacturing method of the present invention pneumatically feeds light hollow particles through a pipe having a corner, and before and after pneumatic feeding by a part of the light hollow particles colliding with the corner of the pipe and being broken. Lightweight hollow particles are selected using the change in bulk density as an index. Specifically, for example, the bulk density ratio (B / A) of the bulk density B after pneumatic feeding with respect to the bulk density A before pneumatic feeding, or the bulk density difference (BA) is used as an index of the change in bulk density, These recover lightweight hollow particles below the reference amount. This reference amount has a bulk density ratio (B / A) of 2 times, a bulk density difference (BA) of 0.2 g / cm ³ , and a bulk density ratio (B / A) of 2 times or less, or a bulk density. Light weight hollow particles having a difference (B−A) of 0.2 g / cm ³ or less are recovered.

When the bulk density ratio (B / A) exceeds twice, it often fails to meet the target product standard, so twice the bulk density ratio (B / A) may be used as a reference for the amount of change. Further, the lightweight hollow particles ranging bulk density of ^{0.1g / cm 3 ~0.25g / cm 3} , which bulk density difference (B-A) exceeds 0.2 g / cm ^3, the bulk density ratio ( Since B / A) generally exceeds twice, the number of products that do not meet the target product standards increases.

When the light-weight hollow particles having a bulk density ratio (B / A) of 2 times or less or a bulk density difference (BA) of 0.2 g / cm ³ or less are used in a mixture with mortar or the like, The amount of destruction at the time of use is remarkably small, and a high quality mortar product can be obtained. The lightweight hollow particles of the present invention have a bulk density ratio (B / A) of 2 times or less, or a bulk density difference (BA) of 0.2 g / cm ³ or less.

In the production method of the present invention, a hollow pipe having a corner is used, and light hollow particles are pneumatically fed through the pipe to collect the light hollow particles having a small change in bulk density. It is preferable that the corner portion of the pipe has an angle of 80 ° to 135 ° in the traveling direction (angle θ with respect to the traveling direction V in FIG. 3). If the angle θ of the corner is smaller than 80 °, the ratio of the particles flowing through the pipeline stagnating at the corner increases. On the other hand, when the angle θ is larger than 135 °, more pearlite passes without colliding with the corners, and it is difficult to obtain a sufficient effect.

The number of corners of the pipeline is preferably 1 to 25, suitably 2 to 20 and preferably 4 to 8. A sufficient effect can be obtained when the number of corners is two or more than one. If there are more than 25 corners, too much pearlite is damaged, which is not suitable.

As for the size (caliber) of the pipe, a pipe having an inner diameter of 10 mm to 30 mm is suitable for a pearlite having a general particle diameter of 0.1 to 1 mm. However, the diameter of the pipe line is not a basic condition because it may be selected according to the amount of lightweight hollow particles to be pumped and the air pressure.

Pneumatic pressure (wind speed) is preferably 5 to 100 m / sec. When the air pressure is less than 5 m / sec, the collision energy is small and it is difficult to obtain a sufficient effect. On the other hand, when the air pressure exceeds 100 m / sec, the collision energy becomes excessive, and too much pearlite is damaged.

Further, when light-weight hollow particles are pneumatically fed at a flow rate of 5 to 100 m / sec through a pipe line having a corner number (n) of 1 to 25 and a corner angle (R) of 80 ° to 135 °, The number of corners (n), the angle (R), and the air pressure (V) are selected so as to be within the range of the formula [1], and the lightweight hollow particles are pneumatically fed.
100 ≦ n × V × (90 / R) ² ≦ 500 [1]

When the hollow hollow particles are pneumatically fed by a combination of the number (n) of corners where the value of [1] is less than 100, the angle (R), and the air pressure (V), the bulk density ratio (B / A) and Although the difference in bulk density (B-A) is small, it is not preferable because the brittle and fragile particles tend not to be sufficiently excluded.

When pneumatically sending lightweight hollow particles by combining the number of corners (n) with the value of [1] exceeding 500, the angle (R) and the air pressure (V), too many particles are destroyed. Not appropriate.

FIG. 4 shows a specific configuration example of a pipe having a corner used in the manufacturing method of the present invention. The illustrated manufacturing apparatus has a pipe line 10 through which light-weight hollow particles flow, and a front part thereof is a part for sucking the light-weight hollow particles into the pipe line, and a pneumatic feeding means (not shown) is connected through a valve 20. is doing. Pneumatic feeding is a mechanism in which air flows from the stabilization part to the recovery part direction (right side in FIG. 4) through the valve 20, and by introducing compressed air into the pipe, lightweight hollow particles are sucked into the pipe. The light-weight hollow particles sucked and flowed through the entire length of the pipeline by compressed air.

The pipe 10 is formed with corners 11 to 14 where lightweight hollow particles flowing inside the pipe 10 abut. In the illustrated apparatus, the corners 11 to 14 are bent at substantially right angles. This part is a bulk density stabilization part. Light-weight hollow particles pass through the four corners, and while being led to the rear part of the pipeline, the fragile particles collide when passing through the corners. However, the subsequent change in the bulk density is suppressed in advance by being destroyed.

A filter portion 15 is provided at the rear portion of the pipe line 10 to allow air to escape and collect lightweight hollow particles. Light-weight hollow particles that have passed through the corners of the pipeline are collected by a filter and collected. In addition, about the manufacturing apparatus of the lightweight hollow particle of this invention, although the material of the pipe line which has a corner | angular part has a higher hardness than a lightweight hollow particle, it is not limited to this. As a suitable example, a carbon steel pipe such as SGP or a stainless steel pipe can be cited. Also, resin piping such as vinyl chloride may be used. Examples of a method for collecting the light hollow particles include a dust collector such as a bag filter.

The Example of this invention is shown with a comparative example. The measuring method of a bulk density and a floating rate is shown below.
〔The bulk density〕
A sample is filled into a container with a constant volume S (cm ³ ), the portion protruding from the opening is ground, the total weight G1 is measured, and the weight G2 of the container is subtracted from this to obtain the powder weight G3 (g). The powder weight G3 [G3 / S] g / cm ³ with respect to the volume S was defined as the bulk density.
[Floating rate]
Floating rate is about 10 g of sample placed in a 200 ml graduated cylinder, filled with water, allowed to stand after sufficient agitation and placed until the water is no longer turbid. The floating rate was calculated from Va / (Va + Va) × 100.

[Example 1]
For the pearlite shown in Table 1, using the apparatus shown in FIG. 4 (pipe length 5 m, corner number n = 8, corner R = 90 °), the pearlite is pneumatically fed at a transportation speed (V) of 30 m / sec. The density ratio before and after pumping was measured. The perlites A1 to A3 are made from the same pearlite, and the pearlites B1 to B3 and C1 to C3 are made from pearlite from different places.

Table 2 shows the bulk density before and after pneumatic feeding, the bulk density ratio (b / a), and the bulk density difference (ba). As shown in Table 2, all of A1, B1 and C1 have a bulk density ratio (b / a) of 2 times or more and a bulk density difference (ba) of 0.2 g / cm ³ or more. Out of target range. On the other hand, A2 and A3, B2, B3, C2 and C3 have a bulk density ratio (b / a) and a bulk density difference (ba) within the scope of the present invention.

Light weight mortar was prepared by blending pearlite after pneumatic feeding into mortar, and pearlite was evaluated in comparison with the amount of pearlite mixed to obtain a set mortar density. As the evaluation criteria, the blending amount of the design value was 100%, and the mixing amount was less than 110% as the best (％), 110% to 140% as good (◯), and 140% or more as the rejection (x). The results are shown in Table 2.

As shown in Table 2, there is a correlation between the density ratio and bulk density difference of pearlite and the quality of the mortar product, and the bulk density ratio (b / a) before and after pumping is less than twice, or the bulk density difference before and after pumping ( When ba) is less than 0.2 g / cm ^{3, a} blending amount with a small error from the design value is sufficient. Especially when the bulk density ratio is 1.8 times or less, the blending is close to the design value. On the other hand, when the bulk density ratio exceeds twice or the difference in bulk density exceeds 0.2 g / cm ³ , the weight is not reduced unless the mixing amount of the lightweight hollow particles is significantly increased from the design value.

[Example 2]
The condition of the transport pipe [number of corners (n) and angle (R), air pressure (V)] was changed and the air pressure was fed, and the bulk density before and after the pumping was measured to obtain the bulk density ratio. Perlite used was B2, B3 and C1 in Table 1. The apparatus conditions and results are shown in Table 3.
As an index of the fracture state by pumping, the value of the formula [1] [n × V × (90 / R) ² ] was calculated. For B2 and B3, when the value of the formula [1] exceeds 500, a lightweight hollow particle having a bulk density ratio (b / a) of 2 or less cannot be obtained. On the other hand, if the value of the expression [1] is smaller than 100, the bulk density ratio (b / a) is similar to C1, and accurate evaluation becomes difficult.

The relationship between the value of equation [1] and the bulk density ratio before and after transportation is shown in FIG. 1, FIG. 2, and FIG. 1 shows the case where pearlite B2 is used, FIG. 2 shows the case where pearlite B3 is used, and FIG. 3 shows the case where pearlite C1 is used. As shown in FIGS. 1 and 2, pearlite B2 and B3 have a primary correlation, and the value of the expression [1] [n × V × (90 / R) ² ] that is an indicator of the destruction state is It is proportional to the bulk density ratio before and after the pumping, and therefore can be determined in the range of 100 ≦ n × V × (90 / R) ² ≦ 500.

On the other hand, for pearlite C1, the value of the expression [1] is approximately a straight line up to about 500. However, beyond this, the coefficient of the primary relational expression is greatly different, and it is difficult to discriminate good pearlite. . In addition, when the index is 100 or less, the difference is remarkably small, and it is difficult to determine whether it is good or bad. In addition, as shown in Table 1 of Example 1, pearlite C1 has a bulk density ratio exceeding twice, and the bulk density difference exceeds 0.2 g / cm ³ , and the evaluation when used in a mortar product is unacceptable. is there.

10-pipe, 11-14 corners, 15-filter, 20-valve, θ-angle

Claims (8)

Lightweight hollow particles are pneumatically fed through a pipe having a corner, and the amount of change in the bulk density before and after pneumatic feeding due to a portion of the lightweight hollow particles colliding with the above-mentioned corner of the pipe and being broken is used as an indicator. A method for producing lightweight hollow particles, wherein hollow particles are selected. The amount of change in the bulk density before and after pneumatic feeding is expressed by the bulk density ratio (B / A) of the bulk density B after pneumatic feeding to the bulk density A before pneumatic feeding, or the bulk density difference (BA). The method for producing lightweight hollow particles according to the above [1], wherein the lightweight hollow particles are selected using the amount of change in the bulk density of the lightweight hollow particles before and after as an index. The method for producing lightweight hollow particles according to [2] above, wherein the lightweight hollow particles having a bulk density ratio (B / A) of 2 times or less or a bulk density difference (BA) of 0.2 g / cm ³ or less are recovered. . When pneumatically feeding light-weight hollow particles at a flow rate of 5 to 100 m / sec through a pipe having a corner number (n) of 1 to 25 and a corner angle (R) of 80 ° to 135 °, the following formula [ 1. The method for producing lightweight hollow particles according to [3] above, wherein the number of corners (n), angle (R), and air pressure (V) are selected so as to be within the range of 1], and the lightweight hollow particles are pneumatically fed. .
100 ≦ n × V × (90 / R) ² ≦ 500 [1] The bulk density ratio (B / A) before and after pneumatic feeding when the lightweight hollow particles are pneumatically fed through a pipe having a corner where the lightweight hollow particles abut is less than twice, or the bulk density difference (BA) is 0. Lightweight hollow particles of 2 g / cm ³ or less. The lightweight hollow particle according to the above [5], which is pearlite obtained by heating and foaming a mineral material or inorganic hollow particles obtained by heating and foaming inorganic particles contained in a foaming agent. It has a pipe line through which lightweight hollow particles flow, and a pneumatic feeding means for flowing the lightweight hollow particles into the pipe line, the pipe line is formed with corners against which the lightweight hollow particles flowing through the pipe abut, An apparatus for producing lightweight hollow particles having a small density change, characterized in that a filter part for collecting air-borne hollow particles by allowing air to escape is provided at the rear part of the pipeline. In the above [7], the number (n) of corners is 1 to 25, the angle (R) of corners is 80 ° to 135 °, and light-weight hollow particles are pumped with an air pressure (V) of 5 to 100 m / sec. Equipment for producing lightweight hollow particles to be described.

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