JP5076197B2 - Method for producing high-strength glassy hollow sphere - Google Patents

Description

  The present invention relates to a novel method for producing high-strength vitreous hollow spheres using any glassy volcanic ejecta as a raw material.

  Among lightweight fillers, glassy hollow microspheres are lightweight and heat resistant, and are isotropic, so they can impart impact resistance without giving anisotropy to the matrix material, and fluidity In addition, it is widely 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.

Later, it was found that glassy volcanic products other than Shirasu, such as ores such as obsidian, pine stone, and pearlite, were also used as raw materials for glassy hollow spheres, and many production methods using these raw ores were proposed. Has been.
Recently, a method for producing a foamed material using a high-temperature fluidized bed has been developed (see Patent Document 2), and a method for producing glassy microhollow spheres using an internal combustion heat medium fluidized bed furnace using the same. In the past, a mixture of fine particles of a volcanic glassy deposit and a hydrophilic reducing agent that reduces the hydrophilicity of the fine particles at 900 to 1200 ° C. using a fluidized bed heating furnace. method for producing a fine hollow glass to heat treatment (see Patent Document 3), a less average particle size 20 [mu] m, a volcanic glass raw ore comprising grains fraction of more than 40μm or less 48% 25% or more by internal combustion fluidized bed furnace the air flow containing the hollow glass body obtained by foaming, tapping bulk density 0.25 g / cm ³ or less is supplied to the plurality of cyclones which are coupled in series, the average particle diameter of 20μm or less of the hollow glass microspheres and the mean particle A method of continuously producing two or more types of hollow glass spheres having different temperatures (see Patent Document 4), using ceramic balls in an internal combustion fluidized bed furnace, and supplying a mixed gas of fuel gas and air to the ceramic balls Then, the temperature of the ceramic ball is raised to 900 ° C. or higher by the combustion heat of the fuel gas, the temperature is controlled within a set temperature ± 3 ° C., and at the same time, the raw material powder of the fine hollow glass sphere is accompanied with the mixed gas. A method for producing fine hollow glass spheres by supplying (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 900-1100 ° C., and loosening A continuous production method of fired foam pumice having a specific gravity of 0.18 to 0.31 (see Patent Document 6) has been proposed.

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 to 0.1 to 2% by mass, 30 to 200% by volume of a high melting point fine powder is then mixed with this and subjected to foam firing at a temperature of 900 to 1300 ° C. in 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)

  Glassy hollow spheres obtained from glassy volcanic ejecta as a raw material by conventional manufacturing methods have low resistance to shearing forces, and when blended as fillers in resins, cements, etc., they have the disadvantage of being easily disintegrated by mixing operations. is there. Attempts have been made to reduce the size to increase pressure resistance and increase the strength as a solution, but no satisfactory results have been obtained so far.

  Under such circumstances, the present invention is an improvement that can uniformly give high-strength glassy hollow spheres regardless of the use of any ore, and can expand the field of use as a filler material. It was made for the purpose of providing a manufacturing method.

  The present inventors have developed a novel method capable of obtaining glassy hollow spheres with significantly higher strength than conventional glassy hollow spheres using any of a wide variety of glassy volcanic products as raw materials. As a result of intensive research, the raw material was dried under controlled temperature conditions using the exhaust gas from the fluidized bed furnace when the volcanic glass ore was supplied to the internal combustion medium fluidized bed furnace and fired. In addition, a novel glassy hollow sphere with unexpectedly high strength can be obtained by classifying the dried raw material with a plurality of cyclones and feeding only a specific fraction into the fluidized bed furnace for continuous firing. This was found to be suitable as a lightweight filler material, and the present invention was made based on this finding.

That is, the present invention classifies volcanic glass ore, supplies a predetermined fraction to an internal combustion medium fluidized bed furnace, fires to produce a glassy hollow sphere,
(B) a volcanic glass ores charged into conduit, is contacted with the combustion-powered medium fluidized bed furnace tube passage and the high-temperature exhaust gas discharged from, drying by heat exchange between them,
(B) Volcanic glass ore after contact is composed of two cyclones and two reverse cyclones, and is a raw ore fraction zone formed by connecting pipes in the order of cyclone, reverse cyclone, reverse cyclone, and cyclone. , Heavy mineral fraction, coarse-grain fraction with a particle size of 515 μm or more, medium-grain fraction with a particle size of 300-515 μm, fine-grain fraction with a particle size of 7-300 μm, and ultrafine-grain fraction with a particle size of less than 7 μm Classification into 5 fractions,
(C) supplying only the fine particle fraction in the fraction to the internal combustion medium fluidized bed furnace and firing at 900 to 1150 ° C., and (d) exhaust gas from the internal combustion medium fluidized bed furnace, It leads to the conduit into which the volcanic glass ore is introduced through a conduit, and the temperature of the volcanic glass ore at the first contact point between the volcanic glass ore and exhaust gas is controlled to 250 to 490 ° C. A method for producing a high-strength glassy hollow sphere is provided.

  As the volcanic glass ore used in the method of the present invention, Shirasu used for the production of ordinary Shirasu balloons, for example, Kakuto Shirasu, Yoshida Shirasu, as well as Shirasu as a raw material for producing glassy hollow spheres. There are weathered volcanic ash such as white clay and Biei white clay, and volcanic eruptions such as obsidian, pearlite, pine stone, natural pumice, mullet and kora. 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.

In the method of the present invention, these volcanic glass ores have a water content that dehydrates from room temperature to 200 ° C. (hereinafter referred to as low temperature water content) at a maximum of 13% by mass, and a water content that dehydrates from 200 ° C. to 800 ° C. In the method of the present invention, the high-temperature water content of the volcanic glass ore is previously reduced by high-temperature drying to 0. 2%. It is preferable to adjust in the range of 90-2.90% by mass.
If the high-temperature water content of the volcanic glass ore is originally within the above range, of course, such adjustment is not necessary.
The high-temperature water content can be determined by measuring the amount of dehydration that evaporates from 200 ° C. to 800 ° C. at a rate of temperature increase of 10 ° C./min in thermal mass spectrometry.

  In the conventional method for producing glassy hollow spheres, in order to reduce the low-temperature water content, which reduces the foaming efficiency only by removing the heat of evaporation without contributing to the foaming source, a drying process is performed in advance using a rotary kiln or dryer. It is necessary to sinter so as not to lose moisture by controlling the temperature rise temperature while strictly adjusting the high-temperature water content within an appropriate range while taking care not to reduce the high-temperature water content contributing as a foaming source as much as possible. there were.

In the method of the present invention, it is a rapid heating method using a fluidized bed furnace using a heat medium, and in advance, the volcanic glass ore is mixed with high-temperature exhaust gas discharged from the fluidized bed furnace. Since the volcanic glass ore is dried by heat exchange, it is not necessary to adjust the water content of the ore. In addition, heavy minerals consisting of rocks such as quartz and feldspar that are inappropriate for the raw material of hollow spheres and coarse particles that are too large and clog the holes in the dispersion plate can be removed easily and automatically. There is no need to take the above-mentioned troubles and considerations, and there is an advantage that it is possible to supply the volcanic glass ore such as the mined pyroclastic flow deposits in a moist state without adjusting the particle size.
However, the volcanic glass ore can obtain higher-quality glassy hollow spheres by adjusting the high-temperature water content of the fine particle fraction supplied to the fluidized bed furnace.

  The adjustment of the high-temperature water content is performed by heating the volcanic glass ore to a relatively high temperature of 350 to 500 ° C, for example. This high temperature drying condition is preferably changed according to the initial high temperature water content of the volcanic glass ore. For example, when the high temperature water content in the volcanic glass ore is 3.0 mass% or more, the high temperature water content is Is 1.46-2.90% by mass, and when the high-temperature water content in the volcanic glass ore is less than 3.0% by mass, it is performed until 0.90-2.45% by mass. Is desirable.

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 volcanic glass ore is 3.0% by mass or more. Yes, when the high-temperature water content of the volcanic glass ore is less than 3.0% by mass, it is in the range of 1.3 to 2.4% by mass, particularly 1.80 to 2.38% by mass.
The time required for this high-temperature drying is shorter as the drying temperature is higher and the particle size of the volcanic glass ore is smaller. Therefore, it is advantageous to dry one having the smallest particle size as possible. Further, depending on the firing conditions of the internal combustion medium fluidized bed furnace, if classification in the method of the present invention is performed, the classified particle diameter is even when the high-temperature water content of the volcanic glass ore is 3.0% by mass or more. The high-temperature water content of the fine particle fraction of 7 to 300 μm may be adjusted within a desired range of 0.90 to 2.90% by mass.

  Therefore, just because the high-temperature water content of the volcanic glass ore is 3.0% by mass or more, it is not always necessary to adjust the high-temperature water content of the volcanic glass ore before classification. Only when the high-temperature water content of the fine particle fraction of 7 to 300 μm after classification of the volcanic glass ore is 3.0% by mass or more, the high-temperature water content is adjusted by a predetermined drying method. desirable.

About such a fraction, the drying time in the case of drying at the temperature of 350-500 degreeC is about about 20-60 minutes. This high temperature drying is performed using an electric furnace, a hot air drying furnace, or the like.
Classification in the method of the present invention is carried out by passing through a plurality of cyclones the heat-exchanged between the volcanic glass ore and the exhaust gas from the internal combustion medium fluidized bed furnace and drying.

  In this way, in the process before supplying the volcanic glass ore to the internal combustion medium fluidized bed furnace, many cyclones are connected and used in addition to the particle size adjustment shown above and the inner wall of the pipe and the ore. In order to disperse the agglomerated particles apart and to improve the shape of the raw ore particles. In other words, by repeating the collision of the ore particles with the inner wall of the pipe in the cyclone and the pipe, and the collision between the particles, the corners of the ore particles with an angular shape are taken and brought closer to a rounded shape. As a result, the sphericity of the glassy hollow sphere can be improved.

  In the method of the present invention, the heavy mineral that is first separated varies depending on the type of volcanic glass ore and the place of production, but is usually contained in an amount of about 3 to 10% by mass based on the mass of the ore. Mineralogically composed of quartz, feldspar, etc., has high heat resistance, and can be effectively used as a heat medium in the present invention.

Next, the method of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing an example of an apparatus for carrying out the method of the present invention. The volcanic glass ore is quantitatively supplied from the raw material hopper 1 by the belt feeder 2 through the inlet 3 through the pipe 4 to the high-temperature pipe 5 and enters the ore fraction zone. This ore fraction zone is composed of a small-capacity cyclone 6, a reverse cyclone 8 and a reverse cyclone 11, and a small-capacity cyclone 14. At the inlet 3, the suction force to the pipe line 4 caused by the exhaust blower 19 works, and smooth ore input without clogging is possible. At the first contact point (point A in the figure) between the ore and the exhaust gas, rapid heat exchange occurs by contacting the exhaust gas at 250 to 490 ° C. or the inner wall of the high-temperature pipe. The mixed flow (gas-solid mixed flow) of the exhaust gas and the ore is sent to the small-capacity cyclone 6 so as to face the air flow blown from below, and most of the ore is conveyed to the opposite flow. Then, the air flows into the pipe 7 and is conveyed above the small-capacity cyclone 6. In the small-capacity cyclone 6, the ore is rubbed against the inner wall of the cyclone intensely by centrifugal force, and heat exchange is promoted, and the agglomerated particles lump due to collision between the inner wall and particles, They try to fall down as they rotate. However, it comes into contact with the air flow blown upward from below, and most of the ore is transported to this counter flow and transported toward the pipe 7. An opposing air flow from the lower side to the upper side of the small-capacity cyclone 6 is introduced from the outside air by the suction force of the exhaust blower 19. Here, in terms of mineralogy, only heavy minerals having a particle size of about 1 mm or more, which is made of quartz, feldspar, etc., with a specific gravity greater than 2.4 are separated from the small-capacity cyclone 6 by falling.

  And most of the ore is a gas-solid mixed flow, passes through the pipeline 7, and the reverse ore cyclone 8 in which the inlet and outlet of the cyclone are connected in reverse, the ore coarse grain fraction, that is, the fraction having a particle size of about 515 μm or more. Is discharged downward by the rotary valve 9 and separated. The fraction with a particle size of about 515 μm or less that was transported to the pipe line 10 in the air flow without being separated by the reverse cyclone 8 was again air-classified by the reverse cyclone 11, and the fraction of the ore medium grain having a particle size of about 300 μm or more. Are separated by air flow classification and discharged downward by the rotary valve 12.

  The ore fine particle fraction having a particle size of about 300 μm or less, which is transported to the pipe line 13 by the air flow without being separated by the reverse cyclone 11, is separated by a strong centrifugal force by the small-capacity cyclone 14 and is lowered by the rotary valve 15. And is supplied to the dry raw material hopper 16. The ore ultrafine fraction having a particle size of about 7 μm or less, which is carried by the air flow without being separated by the cyclone 14, is separated by the bag filter 18, and only the exhaust gas is discharged from the exhaust blower 19.

  In other words, the volcanic glass ore is made up of a heavy mineral having a particle size of about 1 mm or more due to an ore fraction zone composed of a small-capacity cyclone 6, reverse cyclone 8, reverse cyclone 11, and small-capacity cyclone 14. 6, the coarse ore coarse particle fraction having a particle size of about 515 μm to about 1 mm is removed by the reverse cyclone 8, the intermediate ore fraction having a particle size of about 300 to 515 μm is removed by the reverse cyclone 11, The ore ultrafine fraction of about 7 μm or less is removed by the small-volume cyclone 14, and only the ore fine-grain fraction having a particle size of about 7 μm to 300 μm is recovered to the dry raw material hopper 16 by the rotary valve 15 from below the small-volume cyclone 14. Is done.

  The recovered ore fine particle fraction is sent from the screw feeder 20 to the ore supply zone. This ore supply zone is composed of a roots blower 21 and an internal combustion medium fluidized bed furnace 28 via a conduit 22. The raw ore fine particle fraction supplied from the screw feeder 20 is pumped through the pipeline 22 with compressed air by the roots blower 21, where the raw ore fine particle fraction is cooled to near the air temperature in the air stream. The fuel gas is introduced from the fuel gas inlet 23 in the middle of the pipe line 22, and the raw ore fine particle fraction is pumped while being dispersed by the mixed gas, and enters the lower part of the internal combustion medium fluidized bed furnace 28. When the raw ore fine particle fraction pumped from below into the internal combustion fluidized bed furnace controlled at 900 to 1150 ° C. is introduced into the fluidized bed fluidized at a high temperature, Due to heat conduction by contact and intense infrared heating from a high-temperature heat medium, volcanic glass particles soften instantaneously and gasification occurs due to evaporation of water inside the particles, and instantly foams like a water vapor explosion to form a glassy hollow Become a sphere.

  The vitreous hollow spheres are conveyed to the exhaust gas and enter the hollow sphere fraction zone from the internal combustion medium fluidized bed furnace 28 to be separated and recovered into coarse particles and fine particles. The hollow sphere fraction zone includes a conduit 29 through which exhaust gas discharged from the internal combustion medium fluidized bed furnace 28 is sent, a large capacity cyclone 30 for separating coarse hollow spheres, a conduit 32, and a fine hollow sphere separating device. A small-capacity cyclone 33 and a pipe line 35 are included.

  The vitreous hollow spheres transported to the exhaust gas are air-classified into coarse glassy hollow spheres of about 20 to 600 μm with a weak centrifugal force by a large-capacity cyclone 30 for separating the coarse hollow spheres via the pipe 29, and the rotary valve 31 is separated and recovered downward. Fine glassy hollow spheres that have not been separated by the large-capacity cyclone 30 for separating coarse hollow spheres are transported to the exhaust gas and are passed through a pipe 32 to a small-capacity cyclone 33 for separating fine hollow spheres with a strong centrifugal force and about 20 μm. The following fine glassy hollow spheres are air-flow classified and separated and recovered downward by the rotary valve 34. The hot exhaust gas is introduced into the ore fraction zone through the pipe 35 and is effectively used for adjusting the volcanic glass ore.

  The internal combustion medium fluidized bed furnace 28 includes a vertically long cylindrical body 27, a dispersion plate 24 that divides the inside into an upper fluidized bed forming section and a lower wind box section, and a heat medium 26 loaded in the upper section. Yes. The temperature in the furnace is measured at the position of the thermocouple 25, and the total supply amount of the mixture of compressed air and fuel gas fed from the roots blower 21 and the mixing ratio of air and fuel gas are adjusted to 900 to 1150. Temperature control is performed with accuracy within ± 5 ° C within the temperature range of ° C. The vertically long cylindrical body 27 is made of a corrosion-resistant and heat-resistant material such as stainless steel, and its size 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.

  The dispersion plate 24 is a perforated plate in which holes having a diameter of 1.5 to 5 mm are drilled at a ratio of 2 to 5% in a plate having a thickness of 2 to 8 mm, which is a corrosion-resistant and heat-resistant metal, for example, stainless steel. It is used. As the heat medium 26, heat-resistant ceramic balls having a diameter of 2.0 to 3.5 mm, for example, mullite balls, are used. In the method of the present invention, heavy minerals having a particle diameter of 1 mm or more removed from the volcanic glass ore, Efficiency can be improved by using crushed mullite having a particle size of 1.7 mm or more.

  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 10 to 300 kg / hr. It is preferable to operate.

  In the method of the present invention, in order to obtain a desired high-strength glassy hollow sphere, if the temperature of the raw material mixture at the initial contact point (point A in FIG. 1) between the volcanic glass ore and the exhaust gas is too high, foaming occurs. Since the shell wall is thin (1 μm or less) and becomes a multi-bubble hollow sphere structure with low pressure strength, the temperature of the raw material mixture at the first contact point (point A) needs to be 790 ° C. or less.

  It has been confirmed that the strength of the glassy hollow sphere greatly affects the water content of the volcanic glass ore and the drying method (drying temperature and processing time), and the initial contact point, contact method and contact time have an effect. In the present invention, the volcanic glass ore can be directly introduced into the apparatus. Although air drying and air classification are performed by skillfully combining a plurality of cyclones, the strength of the obtained glassy hollow sphere measured by hydrostatic pressure levitation rate is 50 MPa. It has been found that as a condition that can be set to% or more, it is necessary to control the temperature of the first contact point (point A in FIG. 1) to 250 to 490 ° C., preferably 260 to 480 ° C. If it is 250 degrees C or less, in the case of a volcanic glass ore with much moisture, drying will become inadequate and the supply amount of a volcanic glass ore cannot be increased. In order to increase the temperature to 490 ° C. or higher, the internal temperature of the internal combustion medium fluidized bed furnace must be set to 1130 ° C. or higher as a heat source. This is not preferable for continuous production.

This temperature range can be limited by the design of the internal combustion medium fluidized bed furnace, the cyclone connected to it, the pipes, the dimensions of the connecting pipes and their insulation coating materials, etc. It can be carried out by increasing or decreasing the feed rate of the ore and the firing temperature in the fluidized bed furnace, that is, the mixing ratio and the supply amount of the mixed gas of fuel gas and air injected into the fluidized bed furnace.
In the ore fraction zone of the volcanic glass ore combined with a plurality of cyclones as described above, heat exchange is performed with high-temperature exhaust gas whose temperature is controlled, and the ore particles are uniformly preheated and dried. This is a very important factor for obtaining glassy hollow spheres.

  In this way, a novel vitreous hollow sphere having a hollow sphere structure with a particle size of 10 to 300 μm and having a pressure strength corresponding to a hydrostatic levitation rate of 50% or more at 8 MPa for 1 minute is 30 based on the fired body. % Recovery rate can be obtained.

  A conventional vitreous hollow sphere having a particle size of 30 to 300 μm has a hydrostatic pressure levitation rate of 8% or less at 8 MPa for 41 minutes or less, and thus the method of the present invention provides such a high-strength vitreous hollow sphere. What was done was totally unexpected.

  The conventional glassy hollow sphere has a shell wall thickness of 1 μm or less, whereas the glassy hollow sphere of the present invention has a thick shell wall having an average of 1.3 to 3.0 μm. But there is a clear structural difference between the two. Furthermore, according to the present invention, it is also possible to produce glassy fine hollow spheres having a film thickness of 3.0 μm or more.

  In addition, the hydrostatic levitation rate at 8 MPa for 1 minute used as a factor indicating the pressure strength in the present invention is the shirasu described in the VSI workshop standard published by the VSI workshop “Volcanic ejecta that builds a new era”. It is a factor indicating the pressure resistance of the balloon, and is the only standard that is practically used to express the pressure resistance 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 a hydrostatic levitation rate of 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.

  Conventional commercially available volcanic glassy hollow spheres have a pressure resistance of 8 MPa and a low hydrostatic pressure levitation rate of 41% or less, so that when used as a lightweight filler material, the field of use is avoided. However, the filler material of the present invention has an effect that the application field can be expanded because the compressive strength in terms of the hydrostatic levitation rate for 1 minute at 8 MPa is as high as 50% or more.

Next, the best mode for carrying out the present invention will be described by way of examples.
As an internal-combustion medium fluidized bed furnace, a hole having a diameter of 1.7 mm is formed in a stainless steel plate having a thickness of 4.0 mm in a stainless steel cylindrical container having an inner diameter of 129 mm and a height of 1.8 m. The dispersion plate provided in (1) was placed, and the bottom air box was loaded with magnetic balls having a diameter of 26 to 31 mm for preventing backfire. As the heat medium, a heavy mineral having a particle diameter of 1 mm or more recovered from volcanic glass ore was used.

  The volcanic glass ore using the apparatus of FIG. 1 is a natural moist state (adhesive water, that is, water that evaporates at 105 ° C. or lower is 8.60 ° C.) that is an Ito pyroclastic flow deposit produced in Osaki, Kagoshima Prefecture. A volcanic glass ore (average particle size of 290 μm) having a mass% and a high-temperature water content of 2.51 mass% was used. This volcanic glass ore is low in volcanic glass content and is not used as a raw material for conventional Shirasu balloons.

  This volcanic glass ore was supplied from the raw material hopper 1 to the ore fractionation zone at 67.8 kg / h via the inlet 3 by the belt feeder 2 for 1 hour. The temperature of the first contact point between the ore and the exhaust gas (point A in FIG. 1) was 429 ° C. With a small-capacity cyclone 6, 3.2 kg of heavy mineral having a particle size of 1 mm or more was recovered. This heavy mineral had a moisture content of 0.1% and was sufficiently dried. If the ore is not sufficiently dried, the aggregated particles are not sufficiently separated, and the recovery rate of the later-described ore fine particle fraction (raw material of glassy hollow sphere) is lowered.

  Most of the volcanic glass ore was transferred to the air stream, and 38.8 kg of the ore coarse-grain fraction was recovered downward by the reverse cyclone 8 in which the inlet and outlet of the cyclone were connected in reverse. This coarse-grained fraction has a glass content of 80% or less, contains a large amount of coarse particles, and is unsuitable as a raw material for glassy hollow spheres. However, it can be effectively used as a fine aggregate for concrete. Those that could not be separated by the reverse cyclone 8 were transported to the exhaust gas, and the reverse cyclone 11 recovered 6.3 kg of the raw ore medium grain fraction downward. This medium grain fraction has a glassy content of 90% or more and can be used as a raw material for glassy hollow spheres. However, since it contains particles having a particle size of 300 μm or more, it is not fired in the present invention. For those that could not be separated by the reverse cyclone 11, 12.0 kg of the ore fine particle fraction was recovered downward by the small-volume cyclone 14. The ratio of the particle size of 300 μm or less in this ore fine particle fraction was 99.8% by mass. 0.2 kg ore ultrafine particles of 7 μm or less that could not be separated by the small-capacity cyclone 14 were collected by a bag filter 18 connected in front of the exhaust blower 19. Most of the remaining recovery loss is evaporated moisture.

  The raw ore fine fraction 12.0 kg (average particle size 56.2 μm, high temperature water content 2.44 mass%) is sent to the lower dry raw material hopper 16 by the rotary valve 15, and 12 kg is supplied to the ore supply zone by the screw feeder 20. A fixed amount was supplied for 1 hour at a rate of / h. The ore fine particle fraction is a mixed gas of compressed air and fuel gas supplied by the roots blower 21 and is pumped to the lower part of the internal-combustion medium fluidized bed furnace 28 via the conduit 22.

  An internal combustion medium fluidized bed furnace 28 includes a vertically long cylindrical body 27 (inner diameter 129 mm, height 1.8 m) made of heat-resistant stainless steel and a dispersion plate 24 that divides the inside into an upper fluidized bed forming portion and a lower windbox portion. And the heat medium 26 loaded in the upper compartment.

  As the dispersion plate 24, a perforated plate in which holes having a diameter of 1.7 mm were drilled at a ratio of 2.9% in a stainless steel plate having a thickness of 4 mm was used. As the heat medium, 3.2 kg of heavy mineral having a particle diameter of 1 mm or more, which was separately adjusted by the method of separating and removing from the volcanic glass ore in the above ore fractionation zone, was used.

  The temperature of the fluidized bed furnace was controlled at 1050 ° C. ± 5 ° C. by adjusting the supply amount of the fuel gas mixture of compressed air fed from the roots blower 21 and the mixing ratio of air and fuel gas. The static bed height of the fluidized bed was 183 mm and the superficial velocity was 1.1 m / s.

  This volcanic glass ore was foamed through the internal-combustion medium fluidized bed furnace 28 to become vitreous hollow spheres, conveyed to the exhaust gas, separated from the exhaust gas by the cyclone 30 for separating the coarse hollow spheres, and recovered 11.5 kg. The yield of the high-strength glassy hollow spheres obtained by separating the recovered glassy hollow spheres with water is 34.0%, the average particle size is 107.3 μm, the loose apparent specific gravity is 0.35, and the hydrostatic pressure levitation rate. Was 72.7%. In the cyclone 33 for separating fine hollow spheres, 0.2 kg of vitreous hollow spheres having a particle size of 20 μm or less was recovered downward. The remaining recovery loss is evaporated water. 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.

  An electron micrograph (using JSM-840 manufactured by JEOL Ltd., acceleration voltage 15 kV, secondary electron image) of the high-strength glassy hollow sphere is shown in FIG. Its sphericity was 0.65. 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.

  The electron micrograph of the particle | grain cross section of the high intensity | strength glassy hollow sphere obtained in this example is shown in FIG. The shell wall thickness was 2.0 μm. The film thickness of the shell wall was determined by dispersing glassy hollow spheres in cold-embedded epoxy resin, curing at room temperature for 24 hours, rough polishing with No. 320 water-resistant abrasive paper, and precision polishing with No. 2400 water-resistant abrasive paper. After drying, the gold-deposited material was observed with an electron microscope, and four points on the shell wall in the particle cross section of the glassy hollow sphere were measured, and the average value was calculated.

Similar to Example 1 using a pearlite pulverized pearlite (low-temperature water content 0.08 mass%, high-temperature water content 2.92 mass%) crushed to 1 mm or less with a roller mill as the volcanic glass ore Processed.
That is, the volcanic glass ore was supplied from the raw material hopper 1 in FIG. 1 by the belt feeder 2 at 54.0 kg / h through the inlet 3 for 1 hour. The temperature at the first contact point between the ore and the exhaust gas at this time was adjusted to 430 ° C.
Subsequently, classification was performed in the raw ore fraction zone in the same manner as in Example 1. Those descending below the small-capacity cyclone 6 (equivalent to heavy minerals) were not recovered. In addition, 27.3 kg of raw ore coarse-grained fraction, 7.7 kg of raw ore intermediate-grained fraction, 18.3 kg of raw ore fine-grained fraction, and 0.3 kg of raw ore ultrafine-grained fraction were obtained. The rest is unrecovered.
Internal combustion charged with 18.3 kg of the above ore fine particle fraction (high-temperature water content 2.86% by mass, average particle size 38.2 μm) and 3.2 kg of pulverized mullite having a particle size of 1.7 to 2.8 mm. It supplied to the type | formula fluidized bed furnace 28, and baked at 1050 degreeC. 17.4 kg of vitreous hollow spheres separated by the cyclone 30 for separating coarse hollow spheres was recovered. The yield of the high-strength glassy hollow spheres obtained by separating the collected glassy hollow spheres with water is 37.4%, the average particle size is 66.3 μm, the loose apparent specific gravity is 0.29, and the hydrostatic pressure levitation rate. Was 61.1%. In the cyclone 33 for separating fine hollow spheres, 0.5 kg of vitreous hollow spheres having a particle size of 20 μm or less was recovered downward. The rest is unrecovered.
An electron micrograph of the high-strength glassy hollow sphere obtained in this example is shown in FIG.

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

  Thus, the commercially available shirasu balloons are non-uniform in shape, 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 present invention is useful as a method for producing a vitreous fine hollow sphere suitable as a lightweight filler material.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic solution which shows one example of the apparatus for implementing this invention method. The electron microscope surface photograph figure of the high intensity | strength glassy hollow sphere obtained in Example 1. FIG. The electron microscope cross-sectional photograph figure of the high intensity | strength glassy hollow sphere obtained in Example 1. FIG. The electron microscope surface photograph figure of the high intensity | strength glassy hollow sphere obtained in Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw material hopper 2 Belt feeder 3 Input port 4, 5, 7, 10, 13, 17, 22, 29, 32, 35 Pipe line 6, 14 Small capacity cyclone 8, 11 Reverse cyclone 9, 12, 15, 31, 34 Rotary valve 16 Dry raw material hopper 18 Bag filter 19 Exhaust blower 20 Screw feeder 21 Roots blower 23 Fuel gas inlet 24 Dispersion plate 25 Thermocouple 26 Heat medium 27 Long cylindrical body 28 Internal combustion medium fluidized bed furnace 30 For coarse particle hollow sphere separation Large-capacity cyclone 33 Small-capacity cyclone for separating fine hollow spheres

Claims (3)

In a method for classifying volcanic glass ore, supplying a predetermined fraction to an internal combustion medium fluidized bed furnace, and firing to produce a glassy hollow sphere,
(B) a volcanic glass ores charged into conduit, is contacted with the combustion-powered medium fluidized bed furnace tube passage and the high-temperature exhaust gas discharged from, drying by heat exchange between them,
(B) Volcanic glass ore after contact is composed of two cyclones and two reverse cyclones, and is a raw ore fraction zone formed by connecting pipes in the order of cyclone, reverse cyclone, reverse cyclone, and cyclone. , Heavy mineral fraction, coarse-grain fraction with a particle size of 515 μm or more, medium-grain fraction with a particle size of 300-515 μm, fine-grain fraction with a particle size of 7-300 μm, and ultrafine-grain fraction with a particle size of less than 7 μm Classification into 5 fractions,
(C) supplying only the fine particle fraction in the fraction to the internal combustion medium fluidized bed furnace and firing at 900 to 1150 ° C., and (d) exhaust gas from the internal combustion medium fluidized bed furnace, It leads to the conduit into which the volcanic glass ore is introduced through a conduit, and the temperature of the volcanic glass ore at the first contact point between the volcanic glass ore and exhaust gas is controlled to 250 to 490 ° C. A method for producing a high-strength glassy hollow sphere.   The method according to claim 1, wherein a high-strength vitreous hollow sphere having a particle diameter of 10 to 300 µm having a compressive strength corresponding to a hydrostatic levitation rate of 50% or more at 8 MPa for 1 minute is produced.   The method according to claim 1 or 2, wherein a heavy mineral fraction having a particle size of 1 mm or more separated and recovered from a volcanic glass ore is used as a heat medium in an internal combustion medium fluidized bed.