JP5674018B2 - Perlite manufacturing method, inorganic foam material manufacturing method, and foam material manufacturing apparatus - Google Patents

Description

  The present invention relates to a foam material such as pearlite.

  Perlite is a weight reduction material used for weight reduction. For example, the weight of the product can be reduced by mixing pearlite with mortar, roof tile, and outer wall material.

  Now, pearlite is mainly produced by pulverizing pearlite raw materials (for example, acidic volcanic rocks such as rhyolite (pearlite, obsidian, etc.)), heating and foaming. For heating and foaming, an airflow firing furnace and a rotary kiln have been used so far. When an airflow firing furnace is used for heating and foaming, a high-temperature gas (or a flame formed in the furnace) and the pearlite raw material come into contact with each other for about 0.1 to 30 seconds, for example. As a result, the pearlite raw material is foamed into pearlite. When a rotary kiln is used for heating and foaming, the pearlite raw material slides along the rotary kiln wall. At this time, the pearlite raw material receives heat from the furnace wall, such as radiant heat, burner frame, and furnace hot gas. By this heat, the pearlite raw material is foamed into pearlite.

  By the way, generally, when the pearlite raw material is fine, an air flow firing furnace is used to manufacture pearlite. When the pearlite raw material is large (coarse), it is difficult to carry it by an air flow, and therefore, an air flow firing furnace is often not used. The airflow firing furnace is, for example, a vertical cylindrical firing furnace, and includes a raw material charging port at the top and a burner at the bottom. Accordingly, the airflow firing furnace is generally compact. When the pearlite raw material charged from the upper part is heated by the burner and the pearlite raw material is foamed and lightened, the foamed pearlite is carried by the air from below to above, and the product (perlite) is collected. Uniform heating of the pearlite raw material during the heating is difficult. Therefore, some of the pearlite raw materials are not heated and are conveyed by air without being heated. On the other hand, some pearlite raw materials are heated too much, the surface bursts during foaming, and holes are formed in the surface. That is, the uniformity of foaming is poor. And the energy efficiency utilized for foaming is bad.

  When the pearlite raw material is large (coarse), a rotary kiln is used to produce pearlite. The rotary kiln is, for example, a horizontal cylindrical firing furnace. The cylinder is inclined. The pearlite raw material is conveyed by the rotation of the cylinder. There are two types of rotary kilns, an external heating type and an internal heating type. In the manufacture of pearlite, an externally heated rotary kiln is mainly used. When a rotary kiln is used, sufficient heat can be applied to the pearlite raw material. In addition, the heating time is as long as several minutes to several tens of minutes. Accordingly, when a rotary kiln is used, highly uniform pearlite can be obtained. However, when a powdery (small particle size) pearlite raw material is fired in a rotary kiln, the raw material adheres to and accumulates on the rotary kiln wall surface when the firing temperature (heating temperature) exceeds the melting point of the raw material. For this reason, stable firing cannot be performed. Therefore, it cannot be applied to powdery pearlite raw materials. Of course, even if the particle size of the pearlite raw material is large, the above phenomenon occurs when a powdery material is included. Therefore, the powder must be removed. For this reason, generally, a process increases.

  Foam materials such as pearlite are desired to have high strength and low water absorption. The reason is as follows. If the strength is low, damage is likely to occur. When the water absorption rate is high (for example, since the surface has pores, the water absorption rate is high). For example, when kneaded with cement or water, water penetrates into the pearlite (inside the hole). The water that has entered and retained the interior of the pearlite is not easily released to the outside. For this reason, it is difficult to achieve the purpose of weight reduction. Furthermore, when used in cold regions, the water inside the pearlite freezes. As a result, pearlite expands. And damage occurs.

  In order to increase the strength of the foam material (pearlite), it is conceivable to (1) reduce the expansion ratio and (2) increase the thickness of the shell. For this purpose, a method of firing at a low temperature can be considered. The firing at a low temperature narrows the width of the foaming temperature range. For this reason, it is difficult to sufficiently transfer heat to some pearlite raw materials. This produces unfoamed particles. Therefore, it is difficult to obtain uniform pearlite. In order to solve this problem, if high-temperature firing is performed, excessive foaming occurs. There are holes in the surface.

  There have been the following proposals for pearlite manufacturing technology.

  For example, in Japanese Patent Application Laid-Open No. 7-277851, a pearlite or pinestone adjusted in particle size within a certain range is preheated to a temperature of room temperature to 400 ° C. in a rotary kiln, and thereafter, an external heating type rotary kiln is used for 500 A method for producing pearlite having a quality equivalent to or higher than that of conventional obsidian granular foamed pearlite has been proposed by heating to ˜1100 ° C. and foaming.

  JP-A-2008-19149 discloses a method for producing an airtight low water-absorbing pearlite having a balloon shape, and obtaining a foamed pearlite having a large number of bubbles generated by heat-treating fine stone; A step of melting the outer surface of the foamed pearlite again by heating to form an outer shell that closes the opening hole of the bubbles existing on the outer surface of the foamed pearlite. A method for producing a low water absorption pearlite has been proposed.

JP-A-7-277851 JP 2008-19149 A

  The technique of Patent Document 1 uses a rotary kiln. Therefore, only a relatively large pearlite raw material is used. That is, when a powdery raw material is used or when a raw material containing powder is used, the raw material adheres to and accumulates on the inner wall of the rotary kiln as time passes. As a result, it becomes inoperable.

  The technique of Patent Document 2 includes a step of melting the outer shell surface again by heating as a new step, and forming an outer shell that closes the open holes of the bubbles present on the outer shell surface of the foamed pearlite. It is.

  Therefore, the problem to be solved by the present invention is to solve the above problems. That is, it is to provide pearlite (inorganic foam material) having high productivity and low production cost, and having high strength and low water absorption.

The above issues are
A pearlite manufacturing method comprising:
A step of heating the pearlite raw material at 400 to 750 ° C .;
It is solved by a pearlite manufacturing method comprising a B step of heating and foaming the product heated in the A step in a fluidized bed firing furnace.

Preferably, a pearlite manufacturing method,
A step of heating the pearlite raw material at 400 to 750 ° C .;
It is solved by a pearlite manufacturing method comprising the B step of heating and foaming the product heated in the A step to 800 to 1200 ° C. in a fluidized bed firing furnace.

  Preferably, the pearlite manufacturing method is solved by the pearlite manufacturing method, wherein the heating time in the step A is 5 to 90 minutes.

In the production of pearlite, as a raw material, for example, one kind or two or more kinds selected from the group of nacre, shirasu, pine stone, obsidian, and koga stone are used. The pearlite raw material preferably has a 100 µm sieve passage of 5 to 30% by mass. The average particle diameter is preferably 100 to 500 μm. The density is preferably 2.0 to 2.4 g / cm ³ .

The above issues are
In the above-mentioned pearlite production method, the problem is solved by a production method of an inorganic foam material, wherein a raw material of an inorganic foam material is used instead of the pearlite raw material.

The raw material of the inorganic foam material preferably has a 100 μm sieve passage of 5 to 30% by mass. The average particle diameter is preferably 100 to 500 μm. The density is preferably 1.8 to 2.4 g / cm ³ .

The above issues are
A foam production apparatus,
A rotary kiln that heats the raw material of the inorganic foam material at 400 to 750 ° C .;
The problem is solved by a foam production apparatus comprising a fluidized bed firing furnace for heating and foaming a material heated by the rotary kiln at 800 to 1200 ° C.

  After the raw material is heated to 400 to 750 ° C., for example, in a rotary kiln, the heated raw material is heated, for example, to 800 to 1200 ° C. in a fluidized bed firing furnace. Foam (perlite) can be obtained with good productivity and low cost. In particular, even when a raw material having a sieve passage of 5 to 30% by mass is used, the above-described features are exhibited.

Schematic diagram of the device of the present invention

The first invention is a method for producing pearlite. This manufacturing method comprises A process in which a pearlite raw material is heated at 400-750 degreeC. The heating temperature in step A is preferably 650 ° C. or lower. The heating time is 5 to 90 minutes. Preferably, it is 10 minutes or more. Preferably it is 60 minutes or less. The step A is preferably performed using a rotary kiln. That is, since the heating time is relatively long, the treatment with the rotary kiln is preferable. This manufacturing method includes the B process in which the product heated in the A process is heated and foamed in a fluidized bed firing furnace. In the step B, the heating temperature is preferably 800 to 1200 ° C. More preferably, it is 950 degreeC or more. More preferably, it is 1050 degrees C or less. The processing time in the fluidized bed firing furnace is 10 to 300 seconds. In the production of pearlite, as a raw material, for example, one kind or two or more kinds selected from the group of nacre, shirasu, pine stone, obsidian, and koga stone are used. The pearlite raw material preferably has a 100 µm sieve passage of 5 to 30% by mass. The average particle diameter is preferably 100 to 500 μm. The density is preferably 2.0 to 2.4 g / cm ³ .

The second invention is a method for producing an inorganic foam material. This production method is performed according to the pearlite production method. In the production of the inorganic foam material, the raw material is preferably one having a 100 μm sieve passage of 5 to 30% by mass. The average particle diameter is preferably 100 to 500 μm. The density is preferably 1.8 to 2.4 g / cm ³ . Examples of the inorganic foam material include artificial bone materials obtained by pulverizing the above raw materials and adding a foaming agent such as SiC. Of course, it is not limited to this.

  The third invention is a foam material (including pearlite) manufacturing apparatus. This manufacturing apparatus comprises a rotary kiln that heats the raw material of the inorganic foam material at 400 to 750 ° C. This manufacturing apparatus includes a fluidized bed firing furnace that heats and foams the product heated by the rotary kiln at 800 to 1200 ° C. The rotary kiln and the fluidized bed firing furnace are preferably connected. That is, the raw material that has been preheated in the rotary kiln is supplied to the fluidized bed firing furnace without being exposed to the outside air.

  Various types of rotary kilns are used as the rotary kiln. For example, a rotary kiln described in JP-A-7-277851 is used. Other known rotary kilns are also used as appropriate.

As the fluidized bed firing furnace, various types of fluidized bed firing furnaces are used. For example, a fluidized bed firing furnace described in Japanese Patent Application Laid-Open Nos. 2001-240439 and 2002-338280 is used. Other types of fluidized bed firing furnaces may be used. For example, the fluidized bed firing furnace proposed by the present inventor can be used. This fluidized bed firing furnace has a heat medium. The fluidized bed firing furnace is preferably a plate that holds the heat medium (for example, a metal or ceramic plate: a dispersion plate. A dispersion plate holds a medium without dropping it. Further, formation of a good fluidized bed by pressure loss) Installed for the purpose). That is, the heat medium is placed on the plate. A heat flow (fluidized gas) is supplied from the lower side of the plate. Therefore, the plate has a hole. The hole is smaller than the size of the heat medium so that the heat medium does not fall from the hole. A net may be used instead of the plate. In other words, any structure can be used as long as it has a structure that can hold the heat medium and that allows the heat flow to flow from the bottom to the top. The fired product (fired / foamed product) is preferably discharged from the upper side of the heat medium layer by the flow of the heat flow. A feed port for the raw material (the raw material preheated in the rotary kiln) fired in the fluidized bed firing furnace is configured to correspond to the lateral side portion of the heat medium layer disposed in the fluidized bed firing furnace. Yes. The supply port may be a lateral side portion of the heat medium layer, but is preferably as low as possible. This is because the distance passing through the heat medium layer becomes longer and the firing time becomes longer. The firing furnace is generally cylindrical. However, it is not limited to a cylindrical shape. The amount of the heat medium disposed in the firing furnace is preferably H / D when the heat medium is disposed in a cylinder having a height (H) and a diameter (inner diameter) D. Was 1-4. The heat medium preferably has an average particle size of 0.5 to 3 mm. The heat medium preferably has a density of 1 to ³ g / cm ³ . In the fluidized bed firing furnace, N (N is an integer of 2 or more, preferably 3 to 5) plates are stacked and arranged in the furnace. The arrangement position of the plate body is preferably the upper part of the firing zone (firing zone). More preferably, the firing zone is upstream (fluidized bed side) from the free board. The N plates are stacked and arranged at intervals. Preferably, they are stacked and arranged with an interval of about 3 to 15 cm (more preferably, 5 to 10 cm). More preferably, the (K + 1) th plate located at the bottom (K + 1 (where K is an integer not less than 1 and not greater than (N−1))) is the Kth plate located at the Kth from the bottom. Arranged directly above (arranged so that the center of the (K + 1) th plate is above the center of the Kth plate). Particularly preferably, the N plate bodies are arranged so that the center positions thereof are located on the vertical center line of the furnace. At least one of the N plates has an opening. At least one of the N plates has no opening. If the plate is configured as described above, the flow of fluid in the furnace is smooth and less disturbed. As a result, a high-quality fired product can be obtained efficiently. In the present apparatus, the plate having an opening is preferably located at a position other than the lowermost part. More preferably, all the plate bodies other than the lowermost part have openings. This opening is preferably larger as the plate located on the upper side. That is, the opening area is larger toward the upper side. And the plate body which has opening, Preferably, an external shape is so large that it is located above. The opening is more preferably 0.9 × [size of outer shape of Kth plate] ≦ [size of opening of (K + 1) th plate] ≦ 1.2 × [size of outer shape of Kth plate] S] (the K-th plate is the plate located at the Kth (where K is an integer from 1 to N) from the bottom). The first plate located at the lowermost part preferably does not have an opening. The size of the first plate located at the lowermost part is preferably 1/10 to 4/10 (particularly 2/10 to 3/10) of the sectional area of the furnace. That is, if an opening is provided also in the first plate located at the lowermost part, the heat medium existing in the fluidized bed part is likely to jump out. That is, the heat medium in the fluidized bed is likely to flow out (disappear). And the pressure fluctuation and temperature difference distribution in the fluidized bed become large. On the other hand, when no opening is provided in the first plate located at the lowermost part, the heat medium existing in the fluidized bed portion is effectively shielded and is not easily washed away. Difference distribution is small. It is preferable that the following conditions are satisfied for the N plates stacked and arranged. That is, when N plates are irradiated with light in a direction along the furnace wall, the projected area of the light from the N plates is 9/10 or more of the cross-sectional area of the furnace (more preferably 95/100 or more). ). This value may be 100/100. However, this value of 100/100 means that the plate having the largest outer shape is in contact with the furnace wall. If it does so, the workability | operativity of plate body arrangement | positioning is inferior. Therefore, it is actually less than 100/100.

  And when the technique demonstrated by the said embodiment was used, the high intensity | strength and the low water absorption pearlite (inorganic foam material) were obtained. Moreover, even when a raw material having a wide particle size distribution is used, pearlite (inorganic foam) having high strength and low water absorption was obtained.

  Hereinafter, specific examples will be given and described in detail.

  FIG. 1 is a schematic view of an apparatus according to the present invention.

In FIG. 1, 1 is a raw material supply hopper. 2 is a rotary kiln. 3 is a heating furnace. 4 is a fluidized bed firing furnace. The fluidized bed firing furnace 4 is a cylindrical (diameter D = 300 mm) firing furnace. A dispersion plate is provided below the firing furnace 4. The dispersion plate has holes having a diameter (for example, about 0.5 to 2 mm) smaller than the size of the heat medium. On the dispersion plate, a heat medium having a diameter of about 0.5 to ³ mm and a density of about 1 to ³ g / cm ³ is placed so as to have a thickness of 600 mm (H = 600 mm: H / D = 2). Yes. The heat medium is ceramic particles such as alumina or mullite. A raw material supply port (input port) is provided in a lateral side portion of the region (layer) where the heat medium exists in the firing furnace 4. The diameter of the raw material supply port is larger than the diameter of the hole of the dispersion plate or the heat medium, for example, about 1 to 5 cm in diameter.

The pearlite was manufactured using the apparatus of FIG.
The perlite raw material is nacre. The chemical composition of this nacre was as follows. The water content in the chemical composition is the amount of weight loss when heated from 100 ° C to 1000 ° C.
Water content: 3.9 wt% _SiO 2: 70.3 wt% _Al 2 _O 3: 14.1 wt% minor components _{(Na 2 O, K 2 O} , CaO, Fe 2 O 3 , etc.): Battery Chemical Two types of pearlite were prepared.
Pearlite a Average particle size: 165 μm 100 μm Passed by sieve: 21% by mass
Pearlite b Average particle size: 171 μm 100 μm Screen passage: 8% by mass

  That is, the nacre was supplied from the raw material supply hopper 1 into the rotary kiln 2. And it heated at 600 degreeC (Temperature measuring device: Chino radiation thermometer (IR-AHS), a measurement location: the highest temperature part is measured from the kiln bottom opening) with the heating furnace 3. The heating time of the pearlite a by this rotary kiln was 10 minutes. Pearlite a heated in the rotary kiln 2 is supplied into the fluidized bed firing furnace 4 and heated to 1050 ° C. (temperature measurement device: Chino radiation thermometer (IR-AHS), measurement location: measured from inspection hole). It was done. The heating time in the fluidized bed firing furnace 4 was 15 seconds. Note that the heating time in the fluidized bed firing furnace 4 may be appropriately determined in consideration of the degree of foaming and the like. In this way, pearlite was obtained (Example 1).

  In the said Example 1, it carried out similarly except the heating temperature by the heating furnace 3 being 650 degreeC, and the pearlite was obtained (Example 2).

  In the said Example 1, it carried out similarly except the heating temperature by the heating furnace 3 being 750 degreeC, and the pearlite was obtained (Example 3).

  In the said Example 1, it carried out similarly except the heating temperature by the fluidized-bed baking furnace 4 being 950 degreeC, and the pearlite was obtained (Example 4).

  In the said Example 1, it carried out similarly except the heating temperature by the fluidized-bed baking furnace 4 being 1100 degreeC, and the pearlite was obtained (Example 5).

  In the said Example 1, it carried out similarly except the heating time by the heating furnace 3 being 5 minutes, and the pearlite was obtained (Example 6).

  In the said Example 1, it carried out similarly except the heating time by the heating furnace 3 being 60 minutes, and the pearlite was obtained (Example 7).

  Pearlite was obtained in the same manner as in Example 1 except that nacre b was used in place of nacre a used in Example 1 above (Example 8).

  In Example 1 above, pearlite was obtained in the same manner except that an airflow furnace (heating temperature: 1000 ° C.) was used instead of the fluidized bed firing furnace (Comparative Example 1).

  In Example 1, the same procedure was performed except that a rotary kiln (heating temperature: 1000 ° C.) was used instead of the fluidized bed firing furnace (Comparative Example 2).

  In the above Example 1, the pearlite a was directly supplied from the raw material supply hopper to the fluidized bed firing furnace without being preheated (600 ° C.) by the rotary kiln, and heated to 1000 ° C. to obtain pearlite. (Comparative Example 3).

  Pearlite a was supplied from the raw material supply hopper to the rotary kiln and heated to 1000 ° C. (Comparative Example 4).

  Pearlite a was supplied from the raw material supply hopper to the airflow furnace and heated to 1000 ° C. to obtain pearlite (Comparative Example 5).

  Pearlite b was supplied from the raw material supply hopper to the rotary kiln and heated to 1000 ° C. to obtain pearlite (Comparative Example 6).

Since the characteristics of the pearlite obtained in each of the above examples were examined, the results are shown in Table-1.
In addition, the measuring method of intensity | strength puts a sample in the pressurized container filled with water with the sample container, and pressurizes for 1 minute with 8 MPa. After pressurization, the entire amount of the pressurized sample is taken out and placed in a graduated cylinder, and 200 ml of water is added and left still. When the turbidity of water disappears after standing, the volume of the sample particles floating is measured by a method according to the above method for measuring the floating rate, and is set as a pressurized floating rate (floating rate) W2 under 8 MPa pressure. A sample having the same amount as the pressurized sample is measured by the same measurement method except that the sample is not pressurized and is at normal pressure, and is defined as a non-pressurized floating rate (floating rate) W1. It was set as the hydrostatic pressure levitation residual rate based on the formula of pressurized sample buoyancy rate W2 / non-pressurized levitation rate W1 × 100 (%). The greater the value, the greater the strength because the hollow is not broken by hydrostatic pressure.
The water absorption is sufficient when water is added to the pearlite, and after removing moisture on the surface until it becomes surface dried, the surface dry mass is A, and the sample mass when dried at 100 ° C. is B. (B−A) / A × 100 (%) was defined as the water absorption rate.
The density is filled with a sample in a container having a constant volume S (cm ³ ), the portion protruding from the opening is ground, the total weight G1 is measured, and the weight G2 of the container is subtracted from this to obtain the powder weight G3 (g). The powder weight G3 [G3 / S] g / cm ³ with respect to the volume S was determined as the bulk density.
Table-1
Strength (%) Water absorption (%) Density (g / cm ³ )
Example 1 60 10 0.28
Example 2 65 12 0.35
Example 3 73 15 0.44
Example 4 68 12 0.40
Example 5 55 18 0.25
Example 6 51 13 0.25
Example 7 77 11 0.41
Example 8 55 11 0.24
Comparative Example 1 26 30 0.18
Comparative Example 2 Comparative Example 3 incapable of producing pearlite 45 32 0.20
Comparative example 4 Comparative example 5 21 55 0.15 incapable of pearlite production
Comparative Example 6 33 22 0.22

  According to Table 1 above, it can be seen that the present invention can provide high strength and low water absorption pearlite with high productivity and low cost. In particular, it can be seen that even if a fine powdery material is included as a raw material, pearlite with high strength and low water absorption can be provided with high productivity and at low cost. In other words, preheating reduces the moisture contained in the raw material, suppresses foaming, and then heats uniformly in the fluidized bed firing furnace, so that the shell of foamed particles (perlite) is thick and uniform. Therefore, it was considered that the strength and water absorption were remarkably improved.

  On the other hand, when preheating is not performed even if a fluidized bed firing furnace is used, as shown in Comparative Example 3, a high-strength and low water-absorbing pearlite as obtained in the present invention is obtained. It has not been done. However, when it is supplied to the rotary kiln without being preheated and heated to 1000 ° C. (Comparative Example 4), or when it is supplied to the airflow furnace without being preheated and heated to 1000 ° C. (Comparative Example) Compared to 6), the pearlite obtained by the method of Comparative Example 3 is excellent. In particular, when pearlite a containing a large amount of fine powder is used as a raw material and fired at 1000 ° C. in a rotary kiln (Comparative Example 4), fine powder adheres to the kiln wall surface, making it impossible to manufacture. I fell. When fired in an airflow furnace (Comparative Example 5), the strength was small and the water absorption rate was large. According to the observation with a microscope, many particles having pores on the surface and many damaged particles were observed. This is thought to be due to the fact that strong heat was applied partially and foamed too much and burst.

  Even when preheating at 600 ° C. by a rotary kiln is performed, when a fluidized bed firing furnace is not used, that is, when an airflow furnace is used instead of a fluidized bed firing furnace, a comparative example is used. As shown in FIG. 1, a high-strength and low water-absorbing pearlite as obtained in the present invention has not been obtained.

  Even when preheating at 600 ° C. by a rotary kiln was performed, when a fluidized bed firing furnace was not used, that is, when a rotary kiln was used instead of a fluidized bed firing furnace, a comparative example was used. As shown in FIG. 2, a high-strength and low water-absorbing pearlite as obtained in the present invention has not been obtained. In the case of Comparative Example 2 in which a rotary kiln was used, fine powder adhered to the wall surface of the kiln, and production was impossible.

  Moreover, the same tendency was confirmed also when SiC etc. were added to the raw material of the said Example.

1 Raw material supply hopper 2 Rotary kiln 3 Heating furnace 4 Fluidized bed firing furnace 5 Cooling device

Claims (7)

A pearlite manufacturing method comprising:
A step of heating the pearlite raw material to 400 to 750 ° C. with a rotary kiln ;
A pearlite manufacturing method comprising: a step B in which the product heated in the step A is heated and foamed in a fluidized bed firing furnace. 2. The method for producing pearlite according to claim 1, wherein the heating time in step A is 5 to 90 minutes. The pearlite manufacturing method according to claim 1 or 2, wherein the heating temperature in the fluidized bed firing furnace is 800 to 1200 ° C. The method for producing pearlite according to any one of claims 1 to 3, wherein the pearlite raw material has a 100 µm sieve passage of 5 to 30% by mass. The method for producing pearlite according to any one of claims 1 to 4, wherein the pearlite raw material is one or more selected from the group consisting of pearlite, shirasu, pine stone, obsidian, and cogastone. . A method for producing an inorganic foam material,
6. The method for producing an inorganic foam material according to claim 1, wherein the raw material for the inorganic foam material is used in place of the pearlite raw material. A foam production apparatus,
A rotary kiln that heats the raw material of the inorganic foam material at 400 to 750 ° C .;
An apparatus for producing a foam material, comprising: a fluidized bed firing furnace for heating and foaming a material heated by the rotary kiln at 800 to 1200 ° C.

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