JP2009292665A - Production method of highly spherical shirasu balloon and shirasu balloon obtained thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new production method capable of obtaining a shirasu balloon having the high sphericity and the high pressure resistance by one-time calcination even if using any shirasu raw ore recovered from nature. <P>SOLUTION: A residual part after a heavy ore component is removed from the shirasu raw ore, is supplied to an impact treatment in a high-speed air flow to be crushed, thereafter sieved so that an optional division of the particle diameter in the range of 20-150 μm is recovered, and calcined at 900-1,150°C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a shirasu balloon, particularly a high sphericity shirasu balloon having a sphericity of 0.9 or more, and a novel high sphericity and high pressure resistant shirasu balloon obtained thereby.

  Among lightweight fillers, glassy hollow microspheres, such as Shirasu balloons, are lightweight and heat resistant, and exhibit isotropic properties, so they can impart impact resistance without imparting anisotropy to the matrix material. In addition, since it is excellent in fluidity and handling properties, it is frequently used as a filler for cement-based building materials, paper clay, and plastics (see Non-Patent Document 1).

  Shirasu balloon, which is representative of this glassy micro-hollow sphere, is made by firing and foaming shirasu of glassy volcanic eruption deposits, but since the raw materials are readily available and can be foamed relatively easily, Since its development, many manufacturing methods have been proposed.

  As a manufacturing method of this shirasu balloon, first, a method of firing using an electric furnace or a rotary kiln is performed. For example, shirasu is classified and fine particles are separated, and this is divided into 800 to 1200 by an electric furnace or an external heating rotary kiln. There is known a method for producing fine hollow glass spheres (see Patent Document 1) by performing specific gravity separation in water (hereinafter referred to as floating water separation) or air classification after heat treatment at 10 ° C. for 10 seconds to 10 minutes.

Thereafter, a method for producing a foamed material using a high-temperature fluidized bed was developed (see Patent Document 2), and a method for producing glassy hollow microspheres using an internal combustion heat medium fluidized bed furnace using the same dominates. So far, fine hollow particles in which a mixture of fine particles of volcanic glassy deposits and a hydrophilic reducing agent that reduces the hydrophilicity of the fine particles is heat treated at 900 to 1200 ° C. using a fluidized bed heating furnace. A method for producing glass spheres (see Patent Document 3), obtained by foaming a volcanic glass raw material having an average particle diameter of 20 μm or less and containing particles of 40 μm or more in a range of 25% to 48% in an internal fluidized bed furnace. the air flow containing the hollow glass, tapping bulk density 0.25 g / cm ³ or less is supplied to the plurality of cyclones which are coupled in series, different average particle size 20μm or less of the hollow glass microspheres and the mean particle size of 2 A method for continuously producing spherical glass spheres of the kind or higher (see Patent Document 4), using ceramic balls in an internal fluidized bed furnace, supplying a mixed gas of fuel gas and air to the ceramic balls, The ceramic ball is heated to 900 ° C. or higher with the combustion heat of the fuel gas, and the temperature is controlled within the set temperature ± 3 ° C., and at the same time, the raw material powder of the fine hollow glass sphere is supplied along with the mixed gas. (See Patent Document 5), natural pumice is supplied to the fluidized bed from the exhaust side of the internal combustion heat medium fluidized bed furnace, calcined at 900 to 1100 ° C., and loose apparent specific gravity is 0 A continuous production method of fired foamed pumice stone of 18 to 0.31 (see Patent Document 6) has been proposed so far.

On the other hand, for spherical pearlite that has a multi-bubble structure consisting of open-type bubbles without taking a hollow sphere structure, natural glassy rocks that have been crushed and adjusted in particle size are preheated at a temperature lower than their softening point to reduce the water content. After adjusting the content to 0.1 to 2% by weight, and then mixing 30 to 200% by volume of a high melting point fine powder and foaming and firing it at a temperature of 900 to 1300 ° C. with a rotary kiln or electric furnace, A method of separating from a melting point fine powder (refer to Patent Document 7) and a rhyolitic non-granulated rock grain as a raw material, an average particle diameter of 5 mm or less, a sphericity of 0.7 or more, and a compressive strength of 25 N / mm ² When the above-mentioned hard foamed pearlite and rhyolitic non-granulated rock grains having an average particle size of 0.6 to 5 mm and a water content of 3 wt% or less are fired in one step, firing is performed according to the compressive strength of the foamed perlite after firing. Who chooses the temperature And the like are known (see Patent Document 8).

“Industrial Materials”, published by Nikkan Kogyo Shimbun, Volume 42, 1994, p. 102-111 Japanese Patent Publication No. 48-17645 (claims and others) Japanese Patent Publication No. 51-22922 (claims and others) Japanese Patent Publication No. 7-24299 (Claims and others) JP 2002-338280 A (Claims and others) Japanese Patent Laid-Open No. 11-11960 (Claims and others) JP 2004-91283 A (Claims and others) JP-A-9-183612 (Claims and others) JP 2007-320805 A (Claims and others)

  The conventional Shirasu balloon has a low sphericity of less than 0.8, lacks isotropy, and has a compressive strength, that is, a hydrostatic pressure levitation rate of 8 MPa for 1 minute, which is low at 41% or less. When used as a filler for clay and plastic, fluidity and pressure resistance are insufficient, and it is inevitable that the field of use is limited.

  Under such circumstances, the present invention can obtain a shirasu balloon having high sphericity and high pressure strength by one firing even if any shirasu ore collected from nature is used. The present invention has been made for the purpose of providing a novel manufacturing method capable of achieving the above.

  As a result of intensive research to obtain a high sphericity shirasu balloon, the present inventors classified the remainder obtained by removing the heavy mineral component from the shirasu ore in a high-speed air current, It was found that a shirasu balloon having a high sphericity and a high pressure resistance can be obtained by collecting and firing the components, and based on this finding, the present invention has been made.

  That is, in the present invention, the residue from which the heavy mineral components are removed from the shirasu ore is subjected to a high-speed air current impact treatment and pulverized, and then sieved to obtain an arbitrary fraction having a particle diameter of 20 to 150 μm. The present invention provides a method for producing a high sphericity shirasu balloon, which is collected and fired at 900 to 1150 ° C., and a shirasu balloon having high sphericity and high pressure strength obtained thereby.

  As the shirasu ore used in the method of the present invention, shirasu used in the production of ordinary shirasu balloons, such as Kakuto shirasu and yoshida shirasu, as well as Shirasu as a raw material for producing glassy hollow spheres , There are weathered volcanic ash such as Biei white clay, and volcanic eruptions such as obsidian, pearlite, pine stone, natural pumice, mullet, cora. According to the method of the present invention, pyroclastic flow deposits such as shirasu forming a shirasu plateau in south Kyushu, which is considered unsuitable as a raw material for shirasu balloons because of its large amount of heavy minerals, can be used. In addition, Kanuma soil composed of weathered pumice that is mainly composed of volcanic glass and Kanoya soil in Minami Kyushu can be used in the same manner.

These Shirasu ores have a low-temperature water content (dehydration amount from room temperature to 200 ° C.) of 0.3 to 13%, and a high-temperature water content (dehydration amount from 200 ° C. to 800 ° C.) of 1.8 to 6.0. % Have different water contents over a wide temperature range. The low-temperature water content is a dehydration amount that evaporates from room temperature to 200 ° C. at a heating rate of 10 ° C./min in thermogravimetric analysis, and the high-temperature water content is a dehydration that also evaporates from 200 ° C. to 800 ° C. It is a quantity.
In the method of the present invention, in order to reduce the low-temperature water content, which hardly contributes as a foaming source and reduces the foaming efficiency only by taking the heat of evaporation, the high-temperature water content contributing to the foaming source is reduced to 0 by performing a high-temperature drying treatment in advance. It is preferable to calcinate so as not to lose moisture by adjusting the high temperature water content within an appropriate range while taking care not to reduce it to less than 4%.

  The removal of heavy minerals in the method of the present invention can be easily performed, for example, by classifying the raw ore at room temperature and air flow classification. The heavy mineral having a particle diameter of 1 mm or more removed in this manner varies depending on the type of the ore and the production area, but is usually about 3 to 10% by mass based on the mass of the ore.

Next, the impact treatment in a high-speed air stream in the method of the present invention is a method that has been used so far for pulverizing cosmetics, medical products, toners, and the like. For example, powder is a high-speed air stream of 80 to 150 m / second, preferably 90 to 110 m / second This is a method of adhering and immobilizing small particles on the surface of large particles by agitation and mixing in the particles to make particles collide and give strong mechanical energy to the surface. Particles can be obtained.
In the method of the present invention, relatively small particles having a particle diameter of 1 to 10 μm adhere to the surface of relatively large particles having a particle diameter of 20 to 200 μm, and are hybridized to obtain spherical particles having a high sphericity. The treatment time at this time depends on the desired particle size, but is usually in the range of 20 seconds to 30 minutes. This impact treatment in high-speed air current is performed using a hybridizer.

The following generation mechanism can be considered for the hybrid of Shirasu ore by impact treatment in high-speed air current.
(1) Generation of ultrafine particles of 10 μm or less by pulverization of large particles and grinding of the convex portions of the particles.
(2) Reattachment and aggregation of ultrafine particles of 10 μm or less on the surface of large particles by van der Waals force and electrostatic attraction.
(3) Immobilization of ultrafine particles by the impact force and compression shear force on the large particle surface caused as a result of mixing and stirring action.
(4) Multilayering of adhesion of ultrafine particles to the surface of large particles by repeating the above generation mechanisms (1) to (3).

The hybrid shirasu ore is fired so as not to lose moisture by controlling the heating rate, thereby obtaining a desired high sphericity shirasu balloon. For example, when an internal combustion medium fluidized bed furnace is used as the firing furnace, it can be fired and foamed at a temperature 30 to 100 ° C. lower than the firing temperature of the untreated shirasu ore, which has the advantage of reducing the firing cost. is there.
In addition, the obtained high sphericity shirasu balloon has a color such as pink or brown, and the physical properties clearly differ from those obtained from untreated shirasu ore regardless of the same firing conditions. I have to. Naturally, the Shirasu balloon obtained by the present invention is higher in sphericity, higher pressure resistance, and different from the one obtained from the untreated Shirasu ore.

Next, the structure and operation of the hybridizer will be described with reference to the attached drawings.
FIG. 1 is a schematic cross-sectional view of an example of a hybridizer, which is a flat cylindrical jacket 1, a rotor 2 and blades 3 disposed therein, and a circulation circuit 4 for circulating a solid-gas mixed flow. It consists of and. The circulation circuit 4 is connected to a raw material inlet 5 with an open / close valve, and the jacket 1 is provided with discharge valves 6 and 6 ′ for discharging the pulverized powder.

  In the method of the present invention, the shirasu powder introduced into the jacket 1 from the raw material inlet 5 is transported by the high-speed rotation of the rotor 2 with the blade 3 and a high-speed circulating air flow of 100 m / s generated by the circulation circuit 4. The interaction between particles in a high-speed air flow is repeated while the solid-gas mixed flow in which the solid and the gas are mixed for a predetermined time is circulating at high speed while repeatedly colliding with the blade 3 and the pipe wall surface and friction. Thus, electrostatic and mechanical forces work in a complicated manner, whereby pulverization and spheroidization are performed, and high sphericity shirasu granules having a particle size of 5 to 200 μm are obtained. The broken line in the figure indicates the movement path of the particles.

  In the method of the present invention, the shirasu powder subjected to the impact treatment in a high-speed air stream is screened to separate a fraction having a particle size of 20 to 150 μm, which is used for the production of a high sphericity shirasu balloon. In this case, the sieving is usually preferably performed using a vibrating screen, but in addition, it may be performed using a gas phase separation such as a wind screen.

In order to produce a shirasu balloon using the shirasu raw material powder obtained in this way, an electric furnace heating and firing method, a rotary kiln method, etc., which are used for ordinary shirasu balloon production may be used, but it is particularly preferable. Is an internal combustion medium fluidized bed furnace method using a heat medium.
This method uses an internal combustion medium fluidized bed furnace comprising a vertically long cylindrical body, a dispersion plate that divides the inside into an upper fluidized bed forming section and a lower wind box section, and a heat medium loaded in the upper section. Done.

  The vertically long cylindrical body is made of a corrosion-resistant and heat-resistant material such as stainless steel, and the size thereof is appropriately selected according to the production amount of the target glassy hollow sphere. When implemented industrially, it is usually selected within a range of an inner diameter of 50 to 1000 mm and a height of 1 to 10 m, but there is no particular limitation.

  As the dispersion plate, a perforated plate in which holes having a diameter of 1.5 to 5 mm are drilled in a ratio of 2 to 5% in a plate of corrosion resistant and heat resistant metal such as stainless steel having a thickness of 2 to 8 mm is used. It has been. As the heat medium, heat-resistant ceramics having a diameter of 2.0 to 3.5 mm, for example, mullite balls, are used. In the method of the present invention, the particle size 1 is made of crushed mullite that is cheaper and easier to fluidize than mullite balls. Efficiency can be improved by using a thing of .7 mm to 2.8 mm. Moreover, what was fractionated from the heavy mineral with a particle diameter of 1 mm or more previously removed from the Shirasu ore can be used in the same manner.

  In the method of the present invention, the temperature of the fluidized bed furnace is set to 900 to 1150 ° C., preferably 950 to 1100 by adjusting the supply amount of the mixture of the fuel gas and air pumped from the compressor and the ratio of the fuel gas and air. Control within the range of ° C. The vitreous hollow spheres produced in the internal combustion medium fluidized bed furnace are sent to a cyclone for separating hollow spheres and collected. The particle diameter of the high sphericity shirasu balloon thus obtained is usually 30 to 300 μm.

  In the method of the present invention, the static bed height of the fluidized bed is 50 to 300 mm, the superficial velocity is 0.4 to 2.0 m / s, and the volcanic glass ore supply rate is 5 to 40 kg / hr. It is preferable to operate.

  According to the method of the present invention, a single bubble hollow having a high sphericity of 0.9 or higher, which could not be obtained by the conventional method, and having a hydrostatic pressure levitation rate of 50% or higher at 8 MPa for 1 minute. A shirasu balloon having a spherical structure can be obtained.

Next, the best mode for carrying out the present invention will be described by way of examples.
In the examples, a hybridizer type I manufactured by Nara Machinery Co., Ltd. is used as an apparatus for performing impact treatment in a high-speed air stream, and a shirasu powder is used at a peripheral speed of 100 m / s, a charging amount of 300 g / Batch, The treatment time was 180 seconds. In order to prevent contamination from inside the apparatus, the inside of the jacket of the hybridizer and the circulation circuit were made of alumina lining, and the rotor and blade were made of alumina.
In addition, the firing treatment is carried out by using a stainless steel cylindrical container having an inner diameter of 129 mm and a height of 1.8 m as an internal combustion medium fluidized bed furnace, and a hole diameter ratio of 1.7 mm in a 4.0 mm thick stainless steel plate. A dispersion plate provided at 2.9% was disposed, and a magnetic box having a diameter of 26 to 31 mm for preventing backfire was loaded on the bottom air box portion. As the heat medium, 2.8 kg having a particle size of 1.7 mm to 2.8 mm obtained by sieving and sorting mullite crushed material manufactured by ITOCHU CERATECH was used.

As a volcanic glass ore, Shirasu Kakuto produced in Ebino City, Miyazaki Prefecture (volcanic glass content 95% or more, low temperature water content 0.36%, high temperature water content 3.86%, average particle size 62.2μm) hot air drying What was dried at 300 ° C. for 6 hours (low-temperature water content 0.04%, high-temperature water content 1.86%) was subjected to impact treatment in high-speed air current for 3 minutes with an air flow of 100 m / s. After pulverization, a 30-60 μm fraction was collected by a vibration sieve.
Next, when the above fraction was put into an internal combustion medium fluidized bed furnace and baked at 1050 ° C., a brown shirasu balloon having an average particle size of 74.8 μm and a sphericity of 0.94 consisting of almost a single bubble structure was obtained. Obtained.
The floated product had a hydrostatic levitation rate of 55.6% for 1 minute at 8 MPa. The surface SEM photograph of this is shown in FIG. 2, and the cross-sectional SEM photograph is shown in FIG.

Comparative Example 1
The same volcanic glass ore as used in Example 1 is pulverized by a normal method, and the pulverized product is air-flow classified by a cyclone, and a fraction having a particle size of 8.5 to 208.9 μm is collected. Firing was carried out in the same manner as in Example 1. The obtained shirasu balloon had a hydrostatic pressure levitation rate of 8 MPa at 1 MPa for 2 minutes and a low sphericity of 0.74. The surface SEM photograph of this product is shown in FIG. 4, and the cross-sectional SEM photograph is shown in FIG. Unlike the example 1, the obtained shirasu balloon has a multi-bubble structure in most of the particles.

Comparative Example 2
For comparison, Table 1 shows the hydrostatic levitation rate, sphericity, and shape of a commercially available shirasu balloon.

  Thus, the commercially available shirasu balloons are non-uniform in shape, mostly foamy, and all have a hydrostatic levitation rate of 41% or less and a shell wall thickness of 1 μm or less as a whole. The sphericity is less than 0.80.

  Since a high sphericity and high pressure resistant shirasu balloon useful as various fillers and cosmetics can be easily obtained, it can be widely used.

FIG. 3 is a schematic cross-sectional view of an example of a hybridizer. FIG. 2 is an electron microscope surface photograph of the high sphericity shirasu balloon obtained in Example 1. FIG. FIG. 3 is an electron microscopic cross-sectional photograph of the high sphericity shirasu balloon obtained in Example 1. The electron microscope surface photograph figure of the shirasu balloon obtained in the comparative example 1. FIG. The electron microscope cross-sectional photograph figure of the shirasu balloon obtained in the comparative example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flat type cylindrical jacket 2 Rotor 3 Blade 4 Circulation circuit 5 Raw material inlet 6, 6 'discharge valve

Claims (8)

  The residue from which the heavy mineral components are removed from the shirasu ore is subjected to impact treatment in a high-speed air stream and pulverized, and then sieved to collect an arbitrary fraction having a particle size of 20 to 150 μm. A method for producing a high sphericity shirasu balloon, characterized by firing at 0 ° C.   The method for producing a high sphericity shirasu balloon according to claim 1, wherein the impact treatment in the high-speed air stream is performed for 20 seconds to 30 minutes with an air flow of 80 to 150 m / s.   A high-speed air current impact treatment is performed until a particle having a relatively small particle size of 1 to 10 μm adheres to the surface of a particle having a relatively large particle size of 20 to 200 μm and hybridizes. 3. A method for producing a high sphericity shirasu balloon according to 1 or 2.   4. The high sphericity shirasu balloon has a sphericity of 0.9 or more and has a pressure resistance equivalent to a hydrostatic levitation rate of 50% or more at 8 MPa for 1 minute. Manufacturing method of high sphericity shirasu balloon.   The method for producing a high sphericity shirasu balloon according to any one of claims 1 to 4, wherein the obtained shirasu balloon has a single-bubble hollow structure.   A high sphericity shirasu balloon characterized by having a compressive strength corresponding to a hydrostatic levitation rate of 50% or more at 8 MPa for 1 minute.   The high sphericity shirasu balloon according to claim 6 having a sphericity of 0.9 or more.   The high sphericity shirasu balloon according to claim 6 or 7, having a single-bubble hollow structure.