JP5652309B2 - Spray drying granulator and method for producing ceramic granule using the same - Google Patents

Description

  The present invention relates to a spray-drying granulator used for producing a granulated body by drying a slurry, and a method for producing ceramic granules using the same.

  Ceramic materials are widely used as constituent materials for electronic components. For example, a ceramic body such as a ferrite core is manufactured by a method in which ceramic granules (granulated material) are filled in a mold and pressure-molded.

  As a method for producing ceramic granules used for such applications, a method is known in which ceramic granules are obtained as dry powder (granulated material) by spray drying a slurry containing a ceramic material.

  As a device for producing dry powder by spray drying, for example, a spray drying device as in Patent Document 1 has been proposed.

The spray drying apparatus of Patent Document 1 includes: (a) a slurry sprayer that sprays slurry-like raw material powder; a hot air inlet that introduces hot air; and first drying that discharges dry powder obtained by drying with hot air from the lower end. A main body (dry granulation chamber) having a powder discharge port and an air discharge port for discharging hot air used for drying; and (b) unrecovered dry powder contained in the discharged air discharged from the main body. A cyclone provided with a second dry powder discharge port for collecting and discharging (c), and (c) a return pipe for returning the dry powder collected in the cyclone to the main body is extended from the second dry powder discharge port. At the same time, the return opening is provided at a position within 1/3 of the upper end of the distance from the upper end to the air outlet in the main body.
And according to this spray-drying apparatus, it is supposed that the dispersion | variation in a composition and particle size of the dry powder obtained can be suppressed (refer paragraph 0006, FIG. 1, etc. of patent document 1).

  By the way, in the conventional spray drying granulation apparatus including the above-described spray drying apparatus of Patent Document 1, the collection of the dried powder (dried granulated body) is usually performed in a waste disposed directly under the drying granulation chamber. It is performed by discharging dry powder (dry granulated material) from the outlet or after separating the dry granulated material and drying air with a cyclone from the outlet of the dry granule of the cyclone. In order to keep the inside of the grain chamber airtight, a rotary valve, a double damper, or the like is used for the take-out part of the dried granulated body. The rotary valve is also used in the spray drying apparatus of Patent Document 1. .

  However, when a rotary valve is used for the takeout part for taking out the dried granulated material, the rotary valve has a clearance between the rotary rotor and the inner wall of the main body case so that the rotary rotor can rotate. When the dry granule is taken out, the dry granule enters the clearance and is crushed to produce fine powder. As a result, there is a problem in that fine powder is mixed into the recovered dried granulated body, resulting in a variation in particle size.

  Also, when using a double damper, the dry granulated material is sandwiched between the damper that opens and closes and the member that the damper contacts, and is crushed to produce fine powder. Similarly, there is a problem in that fine powder is mixed into the recovered dried granulated body, resulting in a variation in particle size.

JP 2007-285619 A

  The present invention solves the above problems, and in the step of discharging (collecting) the granulated product after dry granulation from the dry granulation chamber, the granulated product is not crushed to produce fine powder, It is an object of the present invention to provide a spray-drying granulator capable of efficiently producing a granulated body with little variation in particle diameter and a method for producing ceramic granules using the same.

In order to solve the above problems, the spray drying granulation apparatus of the present invention,
A slurry supply mechanism including a solid content, a gas supply port to which a heating gas for drying is supplied, and a gas discharge port from which a gas used for drying is discharged, are solid at a pressure lower than atmospheric pressure. A drying granulation chamber for performing dry granulation of the slurry containing
A granulation body granulated in the drying granulation chamber, and a granulation body discharge port for discharging the granulated body to the outside at a higher pressure than the drying granulation chamber,
The granule outlet has flexibility, is deformed into a flat shape due to a pressure difference between the dry granulation chamber and the outside, and the main portions of the opposed inner peripheral surfaces are in close contact with each other, A cylindrical member configured such that a gap portion where the opposed inner peripheral surfaces are not in close contact is formed at both end portions parallel to the axial direction, and the gap portion becomes a flow path through which the granulated body passes. Arranged,
The granulated body is configured to be discharged to the outside through the flow path.

  In the spray-drying granulator of the present invention, it is preferable that the material constituting the cylindrical member is a rubber material.

  Moreover, this invention is applicable when the said slurry containing the said solid content is a ceramic slurry containing a ceramic powder.

  Moreover, the manufacturing method of the ceramic granule of this invention is characterized by performing dry granulation of a ceramic slurry using the spray-drying granulation apparatus in any one of Claims 1-3, and making it a ceramic granule.

  The spray-drying granulator of the present invention comprises a drying granulation chamber that performs dry granulation of a slurry at a pressure lower than atmospheric pressure, and a granulated body granulated in the drying granulation chamber under pressure higher than that of the drying granulation chamber. In a spray-drying granulator equipped with a granule discharge port for discharging to a high outside, the granule discharge port has flexibility and is flattened by a pressure difference between the dry granulation chamber and the outside. The main portions of the inner peripheral surfaces facing each other are in close contact with each other, and void portions where the inner peripheral surfaces facing each other are not in close contact are formed at both ends parallel to the axial direction. Since a cylindrical member configured to be a flow path through which the granulated body passes is disposed and the granulated body is discharged to the outside through the flow path, a rotary valve, a double damper, etc. As in the case of using the granulated body, it prevents the outside of the granulation from being crushed and Consisting of variations (incorporation of fines) less granule can be efficiently produced.

  In addition, the flexible cylindrical member can be configured using a simple material such as a tube made of a rubber-based material or a resin-based material without requiring complicated processing. The equipment cost can be reduced as compared with the case of using a rotary valve or a double damper.

  As described in the background section, the operation of the spray-drying granulator has been conventionally performed under a negative pressure in the drying granulation chamber in order to avoid the discharge of dust around the device. Use a rotary valve, double damper, etc. to prevent the air-tightness of the dry granulation chamber from being impaired immediately below the dry granulation chamber or directly under a solid-gas separation device such as a cyclone. It is common. Here, if the granulated body is taken out by rotating the rotor of the rotary valve or operating the opening / closing mechanism (movable part) of the double damper, the granulated body is crushed to produce fine powder. However, according to the present invention, a cylindrical shape made of a flexible material disposed at the granule discharge port of the dry granulation chamber is problematic. Since the granulated material is discharged to the outside from the flow path formed at both end portions of the member parallel to the axial direction, the granulated material is not crushed and the particle size varies at the granule take-out part. It is possible to efficiently produce a granulated body with less (fine powder mixing).

  In addition, the cylindrical member is deformed into a flat shape due to a pressure difference between the drying granulation chamber and the outside, and the main portions of the inner peripheral surface are in close contact with each other, but both ends parallel to the axial direction are between the inner peripheral surfaces. Is not in close contact, and communicates with the outside to become a passage for the granulated body. The amount of drying gas supplied from the gas supply port to the drying granulation chamber and the drying gas after use discharged from the gas discharge port Since the dry granulation chamber is maintained at a predetermined negative pressure from the relationship of the discharge amount, a large amount that impairs the sealing performance of the dry granulation chamber from the passage (cannot be maintained at the predetermined negative pressure). There is no inflow of outside air.

  Note that if the inner peripheral surfaces of the cylindrical member are completely in close contact with each other, the granulated material cannot be recovered, so that the cylindrical member is deformed by a pressure difference between the dry granulation chamber and the outside. The main parts of the inner peripheral surface are in close contact with each other, but both end portions parallel to the axial direction have characteristics (physical properties) that the inner peripheral surfaces are not in close contact with each other and communicate with the outside to become a passage for the granulated body. The provided cylindrical member is used.

  Therefore, when selecting the cylindrical member, the physical properties of the material constituting the cylindrical member (softness and flexibility, heat resistance to withstand the heat of the granulated body heated in the dry granulation process, etc. It is important to consider dimensions and shapes such as thickness and length.

  Further, as the cylindrical member, the shape before deformation is usually a circular shape when viewed from the direction along the axial direction, that is, a cylindrical shape. Various shapes such as an elliptical cylindrical shape, a long cylindrical shape, and a deformed cylindrical shape can be used.

  Further, in the spray drying granulation apparatus of the present invention, when a rubber-based material is used as a material constituting the cylindrical member, desired characteristics are selected from materials having various cylindrical shapes distributed in the market. Can be easily and economically procured, and the present invention can be made more effective.

  Moreover, the spray-drying granulation apparatus of this invention can be applied suitably when carrying out spray-drying granulation of the ceramic slurry containing a ceramic powder.

  Moreover, the manufacturing method of the ceramic granule of this invention is made to dry-granulate a ceramic slurry using the spray-drying granulation apparatus in any one of the above-mentioned Claims 1-3, and it is set as a ceramic granule. Therefore, it is possible to efficiently produce ceramic granules with little variation in particle size (mixing of fine powder).

  The ceramic granule obtained by the method for producing a ceramic granule of the present invention is suitable for use in producing a ceramic molded body such as a ferrite core by, for example, filling a mold in a dry type and press molding. Can be used.

  Further, when the proportion of fine powder in the granulated body is increased, the fluidity is lowered, and there is a problem that the filling property to the mold is deteriorated, such as variation in filling to the die. Ceramic granules produced by this method have a small proportion of fine powder, high fluidity, and good filling properties in the mold, so that compact and complex shaped products can be produced by the dry molding method. In this case, it can be particularly preferably used.

It is a figure which shows the whole structure of the spray-drying granulation apparatus concerning one Example (Example 1) of this invention. (a) is a figure which shows the principal parts (The cylindrical member attached to the granule discharge port and the granule discharge port etc.) of the spray-drying granulation apparatus concerning Example 1 of this invention, (b) is a cylinder. It is a bb sectional view taken on the line. (a) is a figure which shows the principal part (The cylindrical member attached to the granule discharge port and the granule discharge port etc.) of the spray-drying granulation apparatus concerning Example 1 of this invention, Comprising: The figure which shows the state which the member deform | transformed, (b) is the bb sectional view taken on the line of the deformed cylindrical member.

  Examples of the present invention will be described below to describe the features of the present invention in more detail.

  FIG. 1 shows a schematic configuration of a spray-drying granulation apparatus according to an embodiment (Example 1) of the present invention, which is used for producing a granulated body (ceramic granule) by dry granulating ceramic slurry. FIG.

  As shown in FIG. 1, the spray-drying granulator of Example 1 includes a slurry supply mechanism 1, a hot air supply mechanism 2, a spray dryer body 3, and an exhaust mechanism 4.

The slurry supply mechanism 1 includes a raw material tank 11, a raw material supply pump 12, and the like.
The hot air supply mechanism 2 includes a blower 21 and a hot air generator 22.

  The spray dryer body 3 is used for a dry granulation chamber (chamber) 31 that performs dry granulation of ceramic slurry, a gas supply port 32 for supplying hot air from the hot air supply mechanism 2, and dry granulation. A gas outlet 33 for discharging the generated gas, a granule outlet 34 for discharging the granulated body (ceramic granules) 50 (FIGS. 3A and 3B), an atomizer 35 including the disk D, and the like. ing.

  Further, the exhaust mechanism 4 includes a cyclone 41, a dust collecting means such as a bag filter 42, an exhaust fan 43, and the like.

  In performing dry granulation of a slurry (ceramic slurry) using this spray drying granulator, air heated to a predetermined temperature (for example, 270 to 290 ° C.) from the hot air supply mechanism 2 is supplied to the spray dryer main body 3. While being sent to the gas supply port 32, the ceramic slurry is supplied from the slurry supply mechanism 1 to the dry granulation chamber 31, and in the horizontal circumferential direction as fine droplets having a predetermined particle size by the atomizer 35 including the disk D. Sprayed.

  At this time, the droplets of the ceramic slurry fall downward from the disk D by gravity, as indicated by the dotted line L in FIG.

Since the inside of the dry granulation chamber 31 is heated by the supplied air at a predetermined temperature (for example, 270 to 290 ° C.), the sprayed slurry is dried to form granules as the granules in the dry granulation chamber 31. It accumulates in the lower granule outlet 34.
On the other hand, hot air containing fine powder is discharged to the exhaust mechanism 4 through the gas outlet 33.

And in the spray-drying granulation apparatus of this Example 1, as shown to FIG. 2 (a), (b), the cylindrical member 51 which consists of a material which has flexibility in the granule discharge port 34 is shown. Are connected and fixed by a band-shaped fastening member (fixing jig) 53.
In this embodiment, a cylindrical tubular body made of silicone rubber having a hardness of 40 (JIS K 6253) and having a diameter of 150 mm, a thickness of 2 mm, and a length of 700 mm is used as the tubular member 51.

  As shown in FIGS. 3A and 3B, the cylindrical member 51 is deformed into a flat shape due to a pressure difference between the drying granulation chamber 31 and the outside, and a main portion 51a on the opposed inner peripheral surface. Are formed in both end portions 51b parallel to the axial direction, and a gap 52 is formed in which the opposing inner peripheral surfaces are not in close contact, and the gap 52 passes through the granulated body (ceramic granules) 50. It is configured to be a road.

  Even if the cylindrical member 51 is deformed and a gap 52 serving as a passage for the granulated body (ceramic granule) 50 is formed at both end portions 51b parallel to the axial direction, it is for drying into the drying granulation chamber 31. From the relationship between the supply amount of gas and the discharge amount of the drying gas after use, the inside of the drying granulation chamber 31 is maintained at a predetermined negative pressure, and the sealing property of the drying granulation chamber 31 from the passage 52 is impaired ( It will not be possible to maintain a predetermined negative pressure).

<Production test of ceramic granules by spray drying granulation>
Next, ceramic granules were produced by the method described below using the spray drying granulator.

First, a calcined powder of a ferrite composition made of Fe ₂ O ₃ , NiO, CuO, and ZnO was prepared. Then, a predetermined amount of water, a dispersant, an antifoaming agent, and a plasticizer were added to the calcined powder, and pulverization and stirring / dispersing treatment were performed to prepare a slurry.

  Next, this slurry was spray dried and granulated using the spray drying granulator. In performing this spray-drying granulation, the temperature of the hot air supplied from the gas supply port 32 is set to 200 ° C., and the temperature of the gas used for dry granulation (exhaust temperature) discharged from the gas discharge port 33 is set. It was set to 120 degreeC.

Further, the gas supply amount and the gas discharge amount were adjusted so that the pressure in the dry granulation chamber 31 was 0.05 kPa to 0.10 kPa lower than the outside air.
Then, the obtained granule (ceramic granules), measuring the particle size distribution using a Shimadzu laser diffraction particle size distribution measuring apparatus SALD-2200, average particle size (D _50), and a particle size 44μm or less The ratio of fine powder (fine powder ratio) was determined.

  Moreover, 200 cc granulated body (ceramic granule) was put into a funnel having a passage hole with a diameter of 2.5 mm, and the time until the whole amount flowed down (flowing time) was examined.

For comparison, instead of using the cylindrical member 51 described above, a spray drying granulation apparatus as a comparative example in which a rotary valve is disposed at the granule discharge port 34, and in the case of the above example, Ceramic granules were produced under the same conditions. Then, the obtained ceramic granules, the same conditions, the average particle diameter (D _50), the following proportions of fines particle size 44 .mu.m (fines ratio), and was determined flow time.

As shown in Table 1, a flexible tubular member 51 is disposed in the granule discharge port 34, and a granule (ceramic) is formed using a gap 52 formed in the tubular member 51 as a flow path. In the case of the embodiment in which the granule) 50 is discharged, a rotary valve is disposed in the granule discharge port 34, and the granule (ceramic granule) is discharged through this rotary valve. It was confirmed that the proportion of fine powder having a particle diameter of 44 μm or less (fine powder ratio) was reduced, and the flow time was shortened accordingly.
From this result, it can be seen that by using the spray-drying granulator of the present invention, a granulated body having a low fine powder ratio and a small variation in particle size can be efficiently produced.

In this embodiment, the cylindrical member 51 is made of silicone rubber, but it is also possible to use a synthetic rubber material such as other butadiene rubber or a material made of a natural rubber material. .
In that case, it is usually desirable to use a material having a hardness measured by a durometer of 10 to 70 based on JIS K 6253 and having a thickness in the range of about 0.5 mm to 5 mm.

  Further, the material constituting the cylindrical member 51 is not limited to the above-described material, and is deformed from the cylindrical shape due to the pressure difference between the dry granulation chamber 31 and the outside, and the main inner peripheral surfaces facing each other are deformed. Various materials that form a void portion that forms a flow path through which the granulated body can be discharged to the outside without causing the inner peripheral surfaces to be in close contact with each other, while the portions 51a are in close contact with each other. Can be used.

  In this case, the physical properties of the material constituting the cylindrical member (softness and flexibility, heat resistance to withstand the heat of the granulated body heated in the dry granulation process, etc.), thickness, length, etc. It is necessary to consider the size and shape of the.

  In addition, the present invention is not limited to the above-described embodiments in other respects, but the specific dimensions of the cylindrical member, the method of fixing the cylindrical member to the granule discharge port, and the drying granulation chamber Various applications and modifications can be made within the scope of the invention with respect to the specific structure, the conditions of the ceramic slurry to be granulated, the type of ceramic constituting the ceramic slurry, and the like.

DESCRIPTION OF SYMBOLS 1 Slurry supply mechanism 2 Hot air supply mechanism 3 Spray dryer main body 4 Exhaust mechanism 11 Raw material tank 12 Raw material supply pump 21 Blower 22 Hot air generator 31 Drying granulation chamber (chamber)
32 Gas supply port 33 Gas discharge port 34 Granule discharge port 35 Atomizer with disk 41 Cyclone 42 Bag filter 43 Ventilator 50 Granulator (ceramic granule)
51 Cylindrical member 51a Main portion of inner peripheral surface of cylindrical member 51b Both end portions parallel to the axial direction of the cylindrical member 52 Gap portion serving as a flow path through which the granulated body passes 53 Fixing jig

Claims (4)

A slurry supply mechanism including a solid content, a gas supply port to which a heating gas for drying is supplied, and a gas discharge port from which a gas used for drying is discharged, are solid at a pressure lower than atmospheric pressure. A drying granulation chamber for performing dry granulation of the slurry containing
A granulation body granulated in the drying granulation chamber, and a granulation body discharge port for discharging the granulated body to the outside at a higher pressure than the drying granulation chamber,
The granule outlet has flexibility, is deformed into a flat shape due to a pressure difference between the dry granulation chamber and the outside, and the main portions of the opposed inner peripheral surfaces are in close contact with each other, A cylindrical member configured such that a gap portion where the opposed inner peripheral surfaces are not in close contact is formed at both end portions parallel to the axial direction, and the gap portion becomes a flow path through which the granulated body passes. Arranged,
The spray-drying granulator is configured so that the granulated body is discharged to the outside through the flow path.   The spray-drying granulator according to claim 1, wherein the material constituting the cylindrical member is a rubber-based material.   The spray-drying granulator according to claim 1 or 2, wherein the slurry containing the solid content is a ceramic slurry containing ceramic powder.   A method for producing ceramic granules, characterized in that the ceramic slurry is dried and granulated using the spray-drying granulator according to any one of claims 1 to 3.

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