JP5145498B2 - Manufacturing method of high strength, high sphericity shirasu balloon - Google Patents

Description

  The present invention relates to a method for producing a fine glassy hollow sphere having high strength and high sphericity, that is, a glass balloon, using shirasu as a raw material.

  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.

“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) JP 7-24299 A (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)

  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% or less at 8 MPa, which is as low as 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.

  And, when producing a Shirasu balloon from Shirasu ore, if you want to obtain a product with high strength and high sphericity, there is the annoyance that firing conditions must be strictly controlled for each particle size of the raw material In addition, there was an inconvenience that the yield was significantly reduced.

  The present invention provides a method for producing a shirasu balloon, which can easily obtain a shirasu balloon without changing the firing conditions and firing means corresponding to the composition and particle size of the raw material, and without reducing the yield. It was made for the purpose.

  In the method of the present invention, a volcanic eruption deposit known as Shirasu is used as a raw material, and the main component of Shirasu is volcanic glass and further contains a trace amount of water. When the shirasu particles are rapidly heated, the moisture is gasified and foamed in the softened glass particles to form fine hollow spheres, that is, glass balloons. Therefore, the amount of moisture in the shirasu becomes a large factor that affects the quality of the shirasu balloon.

  By the way, the water | moisture content of shirasu is the sum of the low temperature water content and the high temperature water content, and the water | moisture content is in the range of 4.5-15.0 mass% normally. Compared with the high-temperature water content, the high-temperature water content is roughly divided into those with relatively low water content of less than 3.0% by mass and those with relatively high water content of 3.0% by mass or more, depending on the origin and eruption age. The

  The present inventors have conducted various studies in order to develop a method for producing a shirasu balloon having a high pressure strength and a good sphericity with high yield. After drying at a high temperature to a high water content of 1.46 to 2.90% by mass at ˜500 ° C. and then firing at 980 to 1090 ° C. After high-temperature drying to a high-temperature water content of 0.90 to 2.45% by mass, by calcination at 980 to 1130 ° C., it has been found that a high-pressure strength and good sphericity shirasu balloon can be obtained in high yield. The present invention has been made based on this finding.

  Here, the high-temperature water content is the water content corresponding to the low-temperature water content, and the dehydration amount that evaporates from room temperature to 200 ° C. at a temperature rising rate of 10 ° C./min in thermogravimetric analysis is the low-temperature water content. The amount of dehydration that evaporates from 200 ° C. to 800 ° C. is the high-temperature water content. The present inventors have found that the low temperature water content hardly contributes to the foaming of the shirasu balloon, and the high temperature water content greatly contributes.

  That is, the present invention is to dry a Shirasu ore powder having a high-temperature water content of 3.0% by mass or higher at 350 to 500 ° C. to a high-temperature water content of 1.46 to 2.90% by mass, and then to an internal combustion medium fluidized bed. It is fired within a temperature range of 980 to 1090 ° C. using a furnace, and has a pressure strength equivalent to a hydrostatic levitation rate of 50% or more after hydrostatic pressing at 8 MPa for 1 minute and a true strength of 0.80 or more. A high strength, high sphericity shirasu balloon manufacturing method having a sphericity, and a shirasu ore powder having a high temperature water content of less than 3.0% by mass at 350 to 500 ° C., a high temperature water content of 0.90 to 2.45 mass The hydrostatic levitation rate is 50% or more after hydrostatic pressing at 8 MPa for 1 minute, characterized in that it is dried at a high temperature up to 50% and then fired in a temperature range of 980 to 1130 ° C. using an internal medium fluidized bed furnace. Pressure resistance and 0. 0 or more high strength having sphericity, there is provided a process for producing a high sphericity Shirasu balloons.

  Here, the hydrostatic levitation rate (%) after hydrostatic pressurization at 8 MPa for 1 minute is the pressure resistance of the shirasu balloon described in the VSI Study Group standard published by the VSI Study Group It is a factor indicating the strength, and is the only standard that has been put into practical use and represents the pressure resistance strength of the Shirasu balloon. It is measured by the following method.

A predetermined amount of sample is placed in a sample container formed by contacting a mesh sieve of JIS Z 8801 with a nominal size of 32 μm on the top and bottom of a transparent plastic pipe with an inner diameter of 20.0 ± 0.5 mm and a height of 70.0 ± 0.5 mm. Is submerged in a pressure vessel filled with water having an effective height of 1.2 times or more of the sample vessel.
Next, the pressure vessel is sealed, the internal pressure is increased to 8 MPa over 1 minute or more, and the pressure vessel is held for 1 minute or more. Then, the pressure vessel is opened and the sample vessel is taken out. Next, the entire contents of the sample container are transferred to a floatation / sink separator, and after the floated material and sediment are completely separated, the floated material is poured into a crucible glass filter and suction filtered. Next, the crucible glass filter is dried at 105 ± 2 ° C. for 8 hours or more. This operation is repeated twice. The hydrostatic levitation rate H (mass%) is obtained according to the following formula for each, and the two measurements are averaged to obtain the hydrostatic buoyancy after hydrostatic pressing for 1 minute at 8 MPa.
H = [(m ₁ −m ₀ ) / S] × 100
Here, m ₁ is the total mass (g) of the glass filter and the floating sample in water, m ₀ is the mass (g) of the empty glass filter, and S is the mass of the sample.

In the method of the present invention, the shirasu ore powder is pulverized using, for example, a jet mill to obtain a powder, which is directly used as a raw material. In the conventional method, as described above, it is necessary to adjust the particle size according to the quality of the target product and to perform processing under the corresponding processing conditions. In the method of the present invention, such a particle size is required. Adjustment is not necessarily required.
However, if desired, the particle size may be adjusted by sieving or air classification.

In the method of the present invention, the Shirasu ore powder is first dried by heating to a relatively high temperature of 350 to 500 ° C. The drying conditions at this time need to be changed depending on the proportion of moisture contained in the Shirasu ore powder. That is, when the high-temperature water content in the Shirasu ore powder is 3.0% by mass or more, the high-temperature water content in the Shirasu ore powder is performed until the high-temperature water content becomes 1.46 to 2.90% by mass. Is less than 3.0% by mass, the hot water content is 0.90 to 2.45% by mass. Whether the high-temperature moisture content is lower or higher than this range, the pressure resistance of the shirasu balloon obtained after firing is significantly reduced.
The preferable high-temperature water content after drying is 1.6 to 2.7% by mass, particularly 1.95 to 2.15% by mass when the high-temperature water content of the Shirasu ore is 3.0% by mass or more. When the high-temperature water content of the ore is less than 3.0% by mass, it is 1.3 to 2.4% by mass, particularly 1.80 to 2.38% by mass.

The time required for this high-temperature drying becomes shorter as the drying temperature is higher and the particle size of the raw mineral powder is smaller. Therefore, it is advantageous to dry the finely pulverized product as high as possible.
Therefore, the shirasu ore powder is pulverized to an average particle size of 20 to 100 μm and dried at a temperature of 400 to 500 ° C. The drying time under such conditions is generally in the range of 20 minutes to 1 hour.
The high temperature drying is performed using an electric furnace, a hot air drying furnace, or the like.

  The shirasu ore powder dried at high temperature in this way is screened as it is or as desired, collected as a fraction having a particle size of 7 to 210 μm, preferably 10 to 150 μm by air classification, and sent to the subsequent firing step.

In the method of the present invention, when the high-temperature water content of the shirasu ore is 3.0% by mass or more, the shirasu ore powder adjusted to a high-temperature water content of 1.46 to 2.90% by high-temperature drying is obtained from 980 to 1090. When the high temperature water content of the Shirasu ore is less than 3.0% by mass, the Shirasu ore powder adjusted to a high temperature water content of 0.90 to 2.45% by mass is 980 to 1130 ° C. Each is fired in the temperature range.
When the temperature is lower than 980 ° C., the foaming is not sufficiently performed, so that the yield is lowered. At a high temperature exceeding the above-described temperature range, a shirasu balloon having a low pressure strength is easily generated due to excessive foaming. , The desired high-strength shirasu balloon cannot be obtained. When the temperature is higher than 1130 ° C., when a large amount of shirasu raw material mineral powder is supplied, it is easy to fuse in the furnace and cause clogging in the reactor, and mass production cannot be performed.

Next, an example of the firing step in the method of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic explanatory diagram in the case of firing using an internal combustion medium fluidized bed furnace. The raw material mineral powder dried at high temperature is supplied from an inlet 1 and passes through a discharge pipe 3 from a fluidized bed furnace 2. The exhaust gas is mixed with the exhaust gas and then sent to the screw feeder 7 via the pipe 4, the reverse cyclone 5 and the large-capacity cyclone 6. Next, the raw material mineral powder supplied to the raw material supply pipe 8 by the screw feeder 7 is mixed with the air sent from the compressor 9 and the fuel gas introduced from the fuel gas introduction port 10 provided in the raw material supply pipe 8 to flow. It is press-fitted into the lower part of the floor furnace 2. At this time, the fine-grain fraction separated by the large-capacity cyclone 6 is sucked by the suction blower 11 together with the exhaust gas, and separated and collected by the small-capacity cyclone 13 via the pipe line 12.

  The internal combustion medium fluidized bed furnace 2 includes a vertically long cylindrical body 14, a dispersion plate 15 that divides the inside of the vertically long cylindrical body 14 into an upper fluidized bed forming portion and a lower wind box portion, and a heat medium loaded in the upper compartment. ing. The vertically long cylindrical body 14 is made of a corrosion-resistant and heat-resistant material such as stainless steel, and its size is usually selected within a range of an inner diameter of 50 to 1000 mm and a height of 1 to 10 m, but is not particularly limited.

  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, a heat-resistant ceramic ball having a diameter of 1.5 to 3.5 mm, for example, a mullite ball is used. A heavy mineral having a particle diameter of 1 mm or more contained in shirasu can also be used as a heat medium.

  The temperature of the fluidized bed furnace is controlled within a range of 950 to 1130 ° C. by adjusting the supply amount of the mixture of air and fuel gas fed from the compressor 9 and the mixing ratio of the fuel gas and air. The shirasu balloon generated in the internal-combustion medium fluidized bed furnace 2 is sent to the cyclone 16 for separating the hollow sphere through the discharge pipe 3 and collected.

In the method of the present invention, it is preferable to operate the fluidized bed at a static bed height of 50 to 300 mm, a gas flow rate of 30 to 80 Nm ³ / hour, and a feed rate of the raw mineral powder of 5 to 40 kg / hr. .

According to the present invention, as described above, a high-strength, high-sphericity shirasu balloon having an average particle diameter of 10 to 300 μm or more, ie, most having a single-bubble structure can be obtained.
In general, it is thought that the strength of the shirasu balloon having a multi-bubble structure is low, but the shirasu balloon obtained by the method of the present invention has a hydrostatic levitation after hydrostatic pressure at 8 MPa for 1 minute even if it has a multi-bubble structure. A high pressure strength corresponding to a rate of 50% or more is exhibited.
Further, in the production of a shirasu balloon, if it is intended to obtain a product with high strength and high sphericity, the yield is inevitably lowered. However, according to the method of the present invention, hydrostatic pressure is applied at 8 MPa for 1 minute. High hydrostatic pressure levitation rate of 50% or higher and sphericity of 0.80 or higher, and high strength and high sphericity products based on the mass of raw mineral powder, 28% or higher, and in some cases 50% or higher The yield can be obtained.

  Next, the best mode for carrying out the present invention will be described by way of examples, but the present invention is not limited thereto.

Reference example 1
Shirasu powder from Kakuto, Ebino-shi, Miyazaki Prefecture (high temperature water content 4.16% by mass, average particle size 62.2 μm) is dried at high temperature at a temperature of 350 to 450 ° C. in an electric furnace, and then pulverized by a jet mill. Shirasu powder samples with different hot water contents ranging from 1.25 wt% to 3.19 wt% were prepared.
Next, in these systems, 3.2 kg of mullite crushed material having a particle size of 1.7 to 2.8 mm was used as a heating medium in the system shown in FIG. 1, the stationary layer height of the heating medium was 164 mm, the raw material supply amount was 8.3 kg / When the gas flow rate was 50 Nm ³ / hour, the firing temperature was continuously fired at 1050 ° C. for 30 minutes to produce a shirasu balloon.
The hydrostatic pressure levitation rate (%) of the obtained shirasu balloon after hydrostatic pressing for 1 minute at 8 MPa was measured, and the relationship between the high-temperature water content (mass%) of the shirasu dry powder and the hydrostatic pressure levitation rate (%) A graph is shown in FIG. 2 (Δ mark).
As can be seen from this figure, a high-strength shirasu balloon having a hydrostatic levitation rate of 50% or more can be obtained within the range of the high-temperature water content of 1.46% by mass and 2.90% by mass.

Reference example 2
Shirasu powder (high water content 2.65% by mass, average particle size 290.0μm) from Osaki-cho, Kagoshima Prefecture, dried at 400 ° C in high temperature hot air, and then classified by air flow with a cyclone to obtain a high temperature water content of 0.75%. % To 2.50% by weight of Shirasu dry powder was prepared.
Next, these shirasu dry powders were processed in the same manner as in Reference Example 1 to produce shirasu balloons,
About the obtained shirasu balloon, the hydrostatic pressure levitation rate (%) after hydrostatic pressing for 1 minute at 8 MPa was measured, and the relationship between the high-temperature water content (mass%) of the shirasu dry powder and the hydrostatic pressure levitation rate (%) A graph is shown in FIG.
As can be seen from this figure, a high-strength shirasu balloon with a hydrostatic levitation rate of 50% or more can be obtained within the range of high-temperature water content of 0.90% by mass and 2.45% by mass.

Reference example 3
Shirasu balloons were produced by firing under the same conditions as in Reference Example 1 except that the dried Shirasu powder with a high water content of 1.96% by mass obtained in Reference Example 1 was used and the firing temperature was changed in the range of 950 to 1150 ° C. did.
The obtained shirasu balloon was measured for hydrostatic pressure levitation rate (%) after hydrostatic pressing for 1 minute at 8 MPa, and the relationship between the firing temperature and hydrostatic pressure levitation rate (%) is shown as a graph in FIG. Show.
As can be seen from this figure, when a shirasu raw material powder having a high-temperature water content of 3.0% by weight or more (high-temperature water content of 4.16% by mass) is used, a hydrostatic levitation rate of 50 within a firing temperature range of 985 to 1086 ° C. % Of high strength shirasu balloon can be obtained.

Reference example 4
A shirasu balloon was produced using the dried shirasu powder having a high water content of 1.79% by mass obtained in Reference Example 2 and changing the firing temperature in the same manner as in Reference Example 3.
The obtained shirasu balloon was measured for hydrostatic pressure levitation rate (%) after hydrostatic pressing for 1 minute at 8 MPa, and the relationship between the firing temperature and hydrostatic pressure levitation rate (%) is shown as a graph in FIG. Show.
As can be seen from this figure, when a shirasu raw material powder having a high-temperature water content of less than 3.0% by weight (high-temperature water content of 2.65% by mass) is used, a hydrostatic levitation rate of 50 within a range of a firing temperature of 985 to 1127 ° C % Of high strength shirasu balloon can be obtained.

The apparatus shown in FIG. 1 was used as the apparatus, and a shirasu balloon was manufactured using shirasu from Kakuto, Ebino-shi, Miyazaki (high water content 4.16% by mass, average particle size 62.2 μm) as the shira material.
That is, the shirasu material mineral powder was heated in an electric furnace at 350 ° C. for 1 hour, and then the dried product was pulverized with a jet mill to obtain a shirasu material having an average particle size of 26.4 μm and a high-temperature water content of 2.64% by mass. Prepared.
This shirasu raw material was fed into the raw material supply section from the inlet 1 of FIG. This raw material supply unit includes an exhaust pipe 3 and an inlet 1 through which exhaust gas discharged from an internal combustion medium fluidized bed furnace 2 described later is sent, and exhaust gas separated from glassy hollow spheres by a cyclone 16 for separating hollow spheres. It is comprised from the pipe line 4 which supplies the mixture with a shirasu raw material to a raw material fractionation zone.

  The mixture of the shirasu raw material and the exhaust gas (discharged from the hollow sphere separation cyclone 16) that has passed through this raw material supply section is removed from the coarse fraction by the reverse cyclone 5, sent to the raw material fractionation zone, and dried in the air stream. As a result, only the medium fraction having a particle size in the range of 7 to 210 μm is recovered by the large-capacity cyclone 6. The raw material was sent to the lower part of the fluidized bed furnace through the screw feeder 7 and the raw material supply pipe 8 and was pressure-fed by a mixed gas of air and fuel gas supplied by the compressor 9.

  The internal combustion medium fluidized bed furnace 2 includes a vertically long cylindrical body 14 (inner diameter 129 mm, height 1.8 m) made of heat-resistant stainless steel, and a dispersion plate 15 that divides the inside into an upper fluidized bed forming portion and a lower wind box portion. And a heat medium loaded in the upper compartment.

  As the dispersion plate 15, a perforated plate in which holes having a diameter of 1.7 mm were drilled in a stainless steel plate having a thickness of 4 mm at an opening ratio of 2.9% was used. As the heat medium, 3.2 kg of mullite crushed material having a particle size of 1.7 to 2.8 mm manufactured by ITOCHU CERATECH was used.

  The temperature of the fluidized bed furnace was controlled at 1025 ° C. ± 5 ° C. by adjusting the supply amount of the mixture of air and fuel gas fed from the compressor 9 and the mixing ratio of the fuel gas and air. The fluidized bed was operated at a stationary bed height of 164 mm and a shirasu feed rate of 9.3 kg / hr in the screw feeder 7.

  The shirasu raw material powder was foamed through the internal-combustion medium fluidized bed furnace 2 to become a shirasu balloon, conveyed to the exhaust gas, and separated from the exhaust gas by the cyclone 16 for shirasu balloon separation. The yield of high-strength shirasu balloons obtained by separating the collected shirasu balloons with water is 37.8%, the average particle size is 50.2 μm, the loose apparent specific gravity is 0.60, and hydrostatic pressure is applied for 1 minute at 8 MPa. The subsequent hydrostatic levitation rate was 63.0%. Loose apparent specific gravity is measured by depositing the test powder in a dedicated metal cup (internal volume 100 ml) through a dedicated vibrating screen in 20-30 seconds using a powder tester PT-E made by Hosokawa Micron. did.

  FIG. 4 shows an electron micrograph (using JSM-840 manufactured by JEOL Ltd., acceleration voltage 15 kV, secondary electron image) of the high-intensity, high sphericity shirasu balloon thus obtained. Its sphericity was 0.87. The sphericity is taken as a ratio of the maximum diameter MD and the diameter BD (BD / MD) perpendicular to this by taking a photograph with an electron microscope magnification of 150 times. The closer the sphericity is to 1, the closer to the sphere. Become. In this example, the average value of 20 measurements was taken as the value of sphericity.

  Moreover, the electron micrograph of the particle | grain cross section of this thing is shown in FIG. From the particle cross section, it can be seen that most of the high-strength shirasu balloons consist of single-bubble balloons. For cross-sectional observation, shirasu balloon was dispersed in a cold-embedded epoxy resin, cured at room temperature for 24 hours, coarsely polished with No. 320 water-resistant abrasive paper, precision polished with No. 2400 water-resistant abrasive paper, and dried. The gold-deposited material was observed with an electron microscope.

  A shirasu balloon was manufactured according to the system shown in FIG. As the shirasu raw material powder, the same powder as in Example 1 was used. The Shirasu material was sent from the inlet 1 to the material supply section. This raw material supply unit includes an exhaust pipe 3 and an introduction port 1 through which exhaust gas discharged from an internal combustion medium fluidized bed furnace 2 which will be described later is sent, and exhaust gas and shirasu material separated from a shirasu balloon by a cyclone 16 for shirasu balloon separation. And a conduit 4 for supplying the mixture to the raw material fractionation zone.

  The mixture of the shirasu raw material and the exhaust gas (discharged from the shirasu balloon separation cyclone 16) that has passed through this raw material supply section is removed from the coarse fraction by the reverse cyclone 5, sent to the raw material fractionation zone, and dried in the air stream. As a result, only the medium fraction having a particle size in the range of 7 to 210 μm is recovered by the large-capacity cyclone 6. The raw material was pumped to the lower part of the fluidized bed furnace through the screw feeder 7 and the raw material supply pipe 8 by a mixed gas of air and fuel gas supplied by the compressor 9. Other firing conditions were the same as in Example 1. However, the temperature of the internal combustion medium fluidized bed furnace 2 was controlled at 1050 ° C. ± 5 ° C. by changing the feed rate of the screw feeder 7 to 9.1 kg / hour. The yield of the high-strength shirasu balloon having a single-bubble hollow sphere structure obtained by floating and separating the shirasu balloon recovered by the cyclone 16 for separating the shirasu balloon of FIG. 1 is 54.3%, and the average particle size is 50. The hydrostatic levitation rate after hydrostatic pressing for 1 minute at 0 μm and 8 MPa was 55.3%. FIG. 6 shows an electron micrograph of the high strength, high sphericity shirasu balloon thus obtained. The sphericity of this product was 0.90. Moreover, the electron micrograph of the particle | grain cross section of this thing is shown in FIG. From the particle cross section, it can be seen that most of the high-strength shirasu balloons consist of single-bubble balloons.

The same shirasu raw material powder used in Example 1 was dried at a high temperature for 1 hour in an electric furnace at 400 ° C. and then pulverized by a jet mill, and a raw material having an average particle size of 27.9 μm and a high temperature water content of 2.05% by mass. Shirasu was prepared.
Next, using this shirasu, hydrostatic flotation after hydrostatic pressing for 1 minute at 8 MPa was performed by continuous firing for 30 minutes under the same conditions as in Example 1 except that the raw material supply amount was changed to 9.2 kg / hour. A shirasu balloon having a single-bubble and multi-bubble structure with a rate of 62.2%, a sphericity of 0.91, and an average particle size of 48.0 μm was obtained in a yield of 28.8%. An electron micrograph of the high-intensity, high sphericity shirasu balloon thus obtained is shown in FIG. 8, and an electron micrograph of the particle cross section is shown in FIG.

The same shirasu raw material powder used in Example 1 was dried at a high temperature for 1 hour in an electric furnace at 450 ° C. and then pulverized by a jet mill, and a raw material having an average particle size of 28.4 μm and a high temperature water content of 1.96% by mass. Shirasu was prepared.
Then, using this shirasu, hydrostatic flotation after hydrostatic pressing for 1 minute at 8 MPa by continuous firing for 30 minutes under the same conditions as in Example 1 except that the raw material supply rate was changed to 20.0 kg / hour. A shirasu balloon consisting of an almost single-bubble structure with a rate of 62.0%, a sphericity of 0.90 and an average particle size of 51.3 μm was obtained in a yield of 32.7%. FIG. 10 shows an electron micrograph of the high strength, high sphericity shirasu balloon thus obtained, and FIG. 11 shows an electron micrograph of the particle cross section.

The same shirasu raw material powder used in Example 1 was pulverized with a jet mill and then dried at a high temperature in an electric furnace at 350 ° C. for 1 hour to obtain a raw material having an average particle size of 32.2 μm and a high temperature water content of 1.72% by mass. Shirasu was prepared.
Next, by using this shirasu, by firing under the same conditions as in Example 1 except that the raw material supply rate was changed to 6.1 kg / hour and the firing temperature was changed to 1100 ° C. ± 5 ° C., still water at 8 MPa for 1 minute A shirasu balloon having an almost single-bubble structure having a hydrostatic levitation rate of 50.0% after pressurization, a sphericity of 0.96, and an average particle size of 64.1 μm was obtained in a yield of 36.8%. An electron micrograph of the high-intensity, high sphericity shirasu balloon thus obtained is shown in FIG. 12, and an electron micrograph of the particle cross section is shown in FIG.

The same shirasu raw material powder used in Reference Example 2 was dried with high-temperature hot air at 400 ° C. and then classified by air classification with a cyclone, so that the average particle size was 56.9 μm and the high-temperature water content was 1.79% by mass. A raw material shirasu was prepared.
Then, using this shirasu, except that the raw material supply rate was 9.0 kg / hour, the heating medium amount was 3.1 kg, the stationary layer height of the heating medium was 160 mm, and the firing temperature was changed to 1000 ° C. ± 5 ° C. By firing under the same conditions as in No. 1, the hydrostatic levitation rate after hydrostatic pressing at 8 MPa for 1 minute is 54.0%, the sphericity is 0.81, and the average particle size is 101. An 8 μm high strength, high sphericity shirasu balloon was obtained with a yield of 33.2%. The electron micrograph of this is shown in FIG. 14, and the electron micrograph of the particle cross section is shown in FIG.

Comparative Example The same shirasu raw material powder used in Example 1 was not dried at high temperature, but was simply pulverized by a vibration mill and used as a raw material except for particles having a particle size of 30 μm or more. This had an average particle size of 17.0 μm and a high-temperature water content of 4.16% by mass.
This was fired under the conditions of a raw material supply rate of 7.3 kg / hour, a heat medium amount of 2.8 kg, a heat medium static layer height of 143 mm, and a firing temperature of 900 ° C. ± 5 ° C. The shirasu balloon thus obtained has a hydrostatic pressure levitation rate of 25.3% after hydrostatic pressing at 8 MPa for 1 minute, a sphericity of 0.78, an average particle size of 55.7 μm, and has almost a multi-bubble structure. It was made up of. An electron micrograph of the shirasu balloon thus obtained is shown in FIG. 16, and an electron micrograph of the particle cross section is shown in FIG.

  The method of the present invention can be used as a method for producing a high strength, high sphericity shirasu balloon suitable as a lightweight filler material.

Brief explanation drawing in the case of baking using an internal combustion medium fluidized bed furnace. The graph which shows the relationship between the high-temperature water content (mass%) of the shirasu dry powder obtained by the reference example 1 and the reference example 2, and a hydrostatic pressure floating rate (%). The graph which shows the relationship between the calcination temperature (degreeC) of a shirasu balloon obtained in the reference example 3 and the reference example 4, and a hydrostatic pressure levitation rate (%). 4 is an electron micrograph of a high-strength, high-sphericity shirasu balloon obtained in Example 1. FIG. The electron micrograph figure of the particle cross section of the high intensity | strength and high sphericity shirasu balloon obtained in Example 1. FIG. The electron micrograph figure of the high intensity | strength and high sphericity shirasu balloon obtained in Example 2. FIG. The electron micrograph figure of the particle cross section of the high intensity | strength and high sphericity shirasu balloon obtained in Example 2. FIG. The electron microscope photograph figure of the high intensity | strength and high sphericity shirasu balloon obtained in Example 3. FIG. The electron micrograph figure of the particle section of the high intensity and high sphericity shirasu balloon obtained in Example 3. The electron microscope photograph figure of the high intensity | strength and high sphericity shirasu balloon obtained in Example 4. FIG. The electron micrograph figure of the particle cross section of the high intensity | strength and high sphericity shirasu balloon obtained in Example 4. FIG. The electron microscope photograph figure of the high intensity | strength and high sphericity shirasu balloon obtained in Example 5. FIG. The electron microscope photograph figure of the particle | grain cross section of the high intensity | strength and high sphericity shirasu balloon obtained in Example 5. FIG. The electron microscope photograph figure of the high intensity | strength and high sphericity shirasu balloon obtained in Example 6. FIG. The electron microscope photograph figure of the particle | grain cross section of the high intensity | strength and high sphericity shirasu balloon obtained in Example 6. FIG. The electron microscope photograph figure of the shirasu balloon obtained in the comparative example. The electron micrograph figure of the particle | grain cross section of the shirasu balloon obtained by the comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inlet 2 Fluidized bed furnace 3 Discharge pipes 4, 12 Pipe line 5 Reverse cyclone 6 Large capacity cyclone 7 Screw feeder 8 Raw material supply pipe 9 Compressor 10 Fuel gas inlet 11 Suction blower 13 Small capacity cyclone 14 Long cylindrical body 15 Dispersion plate 16 Cyclone for hollow sphere separation

Claims (4)

  Shirasu ore powder having a high-temperature water content of 3.0% by mass or more is dried at 350 to 500 ° C. to a high-temperature water content of 1.46 to 2.90% by mass, and then 980 to 980 using an internal combustion medium fluidized bed furnace. High strength having a compressive strength equivalent to a hydrostatic pressure levitation rate of 50% or more after hydrostatic pressing at 8 MPa for 1 minute and a sphericity of 0.80 or more, characterized by firing within a temperature range of 1090 ° C. The manufacturing method of a high sphericity shirasu balloon.   Shirasu ore powder having a high temperature water content of less than 3.0% by mass is dried at 350 to 500 ° C. to a high temperature water content of 0.90 to 2.45% by mass, and then 980 to 980 using an internal medium fluidized bed furnace. High strength having a compressive strength equivalent to 50% or higher hydrostatic pressure levitation rate after hydrostatic pressing at 8 MPa for 1 minute and a sphericity of 0.80 or higher, characterized by firing within a temperature range of 1130 ° C. The manufacturing method of a high sphericity shirasu balloon.   The method for producing a high strength, high sphericity shirasu balloon according to claim 1, wherein 90% by mass or more of the obtained high strength shirasu balloon is a single-bubble balloon.   The method for producing a high strength, high sphericity shirasu balloon according to claim 1 or 2, wherein a high strength shirasu balloon having a sphericity of 0.85 or more is obtained.