JPH09314531A - Dryer for ceramic slurry - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dryer for ceramic slurry which is excellent in area productivity and can dry efficiently. SOLUTION: There are provided a belt conveyor 20 with a belt 23 having water repellent surface, a slurry discharging device 14 for continuously discharging ceramic slurries S on a belt at the start end of the belt conveyor 20 by fixed quantities in a single row or a plurality of rows, and a drying furnace 30 for drying the ceramic slurries S by conveying them with the belt conveyor 20. The ceramic slurries S on the belt conveyor 20 are dried so as to be formed into a continuous string-like molding D during their passages through the drying furnace 30. The dried string-like molding D is divided into uniform sizes by a divider 40 arranged at the terminal end of the belt conveyor 20 and pelletized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic slurry drying device, and more particularly to a device for dehydrating and drying slurry after mixing and dispersing ceramic raw materials before calcination.

[0002]

2. Description of the Related Art In a manufacturing process of a ceramic electronic component, a drying and granulating process is required for reasons such as quality stabilization after main firing and easy handling in a calcination process. The following methods are typical drying and granulating methods. (A) A method of extruding a wet raw material powder with a screw or the like to granulate it into pellets. (B) A method of adding water while stirring the dry raw material and compacting it with a stirring blade to granulate. (C) A hollow Method of sandwiching the dry raw material between certain two rollers and compacting it (d) The raw raw material that has been slurried is made into a cake by a filtration and dehydration step, and after heating and drying, it is passed through a coarse sieve to produce a granule having a predetermined particle size. Method for obtaining granules (e) A large number of comb-teeth-shaped protrusions are immersed in a slurry, the slurry is attached to the tip, stamped on a plate, the drip of the slurry is transferred, and then the granules are dried. How to get

[0003]

Of the above methods,
The dry and semi-dry methods (a) to (c) are not suitable for products that require a uniform composition such as electronic ceramics when mixing a plurality of materials from a microscopic viewpoint. This causes quality instability in the production process. On the other hand, the wet method such as (d) or (e) can achieve more stable quality than the dry method or the semi-dry method, but in the case of (d), rather than the opening of the filter in the filtration step. There is a problem that fine raw materials, dispersants, ionized raw materials, etc. pass through the filter and cause deviation from the composition at the time of formulation, and moreover, there are many manufacturing processes because it is molded and then dried. There was a drawback. The method (e) has the advantage that it can be dried and granulated directly from the slurry, but since the stamping mechanism has to reciprocate between the slurry layer and the plate, the equipment area is large and the area production is large. It had the drawback of being poor in nature.

Therefore, an object of the present invention is to provide a ceramic slurry drying apparatus which is excellent in area productivity and can be efficiently dried.

[0005]

In order to achieve the above object, the drying apparatus according to claim 1 has a belt conveyor having a belt having at least a water-repellent surface, and a ceramic slurry on the belt surface of the belt conveyor. It is equipped with a slurry discharge device that discharges a fixed quantity continuously in a single row or multiple rows and a drying means for drying the ceramics slurry while it is being conveyed by a belt conveyor. Is characterized by being dried into a continuous string-shaped body. In the above drying device, it is desirable to provide a dividing device for dividing the dried cord-shaped molded body into equal sizes at the end of the belt conveyor.

Further, in the drying apparatus according to the third aspect, at least the belt conveyor having the belt having the water-repellent surface, and the ceramic slurry is intermittently discharged in a single row or a double row on the belt surface of the belt conveyor. It is equipped with a slurry discharge device and a drying means for drying the ceramics slurry while it is being conveyed by a belt conveyor, and while passing through the drying means, the ceramics slurry on the belt conveyor is dried into intermittent granular or string-shaped compacts. It is characterized by being done.

When the slurry in which the ceramic raw material is mixed and dispersed in the dispersant is continuously discharged in a single row or a double row from the slurry discharging device on the belt surface of the belt conveyor in a fixed amount, the slurry extends in the belt conveying direction. It is formed into a continuous straight line. Since the surface of the belt is made of a water-repellent material, the dispersant does not soak into the belt and the surface tension maintains the formability. In this state, when the ceramic slurry on the belt conveyor passes through the drying means, the slurry is dried and solidified into a cord-shaped molded body. After drying, the ceramic molded body is naturally peeled off at the terminal end of the belt conveyor by using the reversal of the belt and is collected. In this case as well, since the surface of the belt has water repellency, it can be easily peeled from the belt even if the amount of water in the dried molded product changes a little.

When the dividing device is provided at the terminal end of the belt conveyor, the dried and solidified cord-shaped molded body is divided into equal sizes, and a homogeneous granulated body can be obtained. This allows
Handling becomes easier in the subsequent calcination step.

The cord-shaped ceramic molded body discharged from the drying furnace has cracks and cracks due to shrinkage during dehydration / drying, and when it falls into the collecting device at the end of the belt conveyor, It is naturally divided into a certain length by the drop impact. Therefore, it is possible to granulate the molded product, although there is some variation in length without providing a separate dividing device. In addition, after collecting in the collection device,
The molded body may be granulated separately.

Further, when the ceramic slurry is intermittently discharged from the slurry discharge device onto the belt conveyor in a single row or a double row as described in claim 3, the ceramic slurry is passed through a drying furnace. Becomes a granular or intermittent string-shaped molded body on the belt conveyor. Therefore, it is possible to obtain a granulated body without providing a dividing device.

As the water repellent material formed on the surface of the belt conveyor, for example, a fluororesin material can be used. Also, improve the heat absorption efficiency in the drying oven,
In addition, in order to remove static electricity generated during collection after drying,
Carbon powder may be added to the belt.

As the slurry discharge device, for example, a device in which a plurality of tubes or nozzles for discharging the slurry from the tank onto the belt conveyor are arranged in parallel is desirable. In this case, it is easy to add tubes to increase the processing capacity. Further, in order to balance the discharge amounts, it is desirable to provide a flow rate adjusting valve on each tube.

In order to obtain a cord-shaped molded product having a uniform thickness, it is necessary to discharge the slurry on the belt conveyor in a fixed amount.
Therefore, it is mechanically simple to control the liquid level of the tank storing the slurry to be constant and discharge the slurry in a fixed amount by the head pressure.

[0014]

FIG. 1 shows an example of a ceramic slurry drying apparatus according to the present invention. The primary tank 1 is equipped with an agitator 2 for agitating and mixing the ceramic raw material and water, and agitates so that the composition of the slurry S can be maintained. The slurry S in the primary tank 1 is sent to the secondary tank 5 via the supply pipe 3 and the mud pump 4. Secondary tank 5
Also, a stirrer 6 for preventing the sedimentation of the slurry S is provided. The liquid level of the slurry S in the secondary tank 5 is detected by the float 7, and the movement of the float 7 is monitored by the monitoring sensor 8. As the liquid level monitoring sensor 8,
The liquid level is not limited to being detected by the movement of the float 7, but a sensor that directly detects the liquid level may be used.

The detection signal of the sensor 8 is sent to a control device 9 including a programmable controller as shown in FIG. The controller 9 performs a predetermined calculation process, sends a pump drive signal to the mud pump 4, and drives the pump 4.
Perform stop control. That is, the control device 9 controls the pump 4 so that the liquid level in the secondary tank 5 is always constant. In addition, the secondary tank 5 by the chattering of the pump 4
In order to suppress the internal liquid level fluctuation, a dead time may be provided so that the pump 4 is controlled only when the input of the sensor 8 continues for a certain time.

As shown in FIG. 3, a plurality of distribution tubes 10 are connected to the bottom of the secondary tank 5, and a flow rate adjusting valve 11 is provided in the distribution tube 10. The flow rate adjusting valve 11 includes a valve body 12 that inserts and holds the distribution tube 10. The valve body 12 is provided with a plurality of flow rate adjusting screws 13 that are in pressure contact with each tube 10 in the orthogonal direction as shown in FIG. I am fit. With these screws 13, the throttle amount can be adjusted so as to eliminate the discharge variation of the slurry S discharged from each tube 10. The above primary tank 1, mud pump 4, secondary tank 5, distribution tube 1
0, the flow rate adjusting valve 11, etc.
Is configured.

The belt conveyor 20 has a belt 23 wound around a drive pulley 21 and a driven pulley 22, and the lower end of the tube 10 is close to the belt surface at the starting end thereof. The belt 23 is driven at a constant speed in the direction of the arrow by the drive pulley 21, and when the slurry S is continuously discharged from the tube 10 onto the surface of the belt 23 in a double row as shown in FIG. The belt 23 is formed into a continuous linear shape extending in the conveying direction.

Instead of the discharge method shown in FIG. 5, the tip 10a of the tube or nozzle 10 is bent in the conveying direction of the belt 23 as shown in FIG. 6 so that the slurry S is discharged in parallel with the conveying direction. You may In this case, the spread of the slurry S discharged onto the belt 23 is suppressed,
It can be molded into a more beautiful straight line.

The belt 23 is made of a fluororesin-based material so that at least its surface has water repellency.
For example, since it is used under repeated heating, it is preferable that glass cloth is used as a base material and impregnated with a fluororesin to add strength. Further, in order to make the belt surface smoother, it is desirable to use one having a structure in which a fluororesin film is laminated on the surface. It is desirable to add carbon fine powder to the belt 23.

The belt conveyor 20 is inserted through the drying furnace 30. The drying furnace 30 of this embodiment has a tunnel shape in order to prevent heat dissipation and realize efficient drying, and the upper section of the furnace has a semi-circular shape or a shape similar to this, and vaporized steam is evaporated. It has a shape that makes it easy to exhaust. A heater 31 is provided inside the drying furnace 30.
Is arranged. The heating method of the heater 31 may be any of far infrared rays, warm air, microwaves, induction heating, electric heating, and the like, and is selected so that a desired drying rate and water content can be obtained. The linear ceramic slurry S discharged from the tube 10 onto the belt 23 is dried by the drying furnace 30.
It is dried and solidified while passing through to form a cord-shaped molded body D.

When the belt 23 to which the carbon fine powder is added is used, the absorption of heat from the heater 31 is promoted, the drying efficiency is improved, the thermal conductivity is improved, and the heat distribution in the belt width direction is improved. It can be made uniform. Therefore, the molded body D having a uniform water content can be obtained. Further, since the belt 23 becomes conductive by adding the carbon fine powder, as described later, static electricity generated when the granule D is separated and collected from the belt 23 can be easily removed.

A dividing device 40 is arranged at the end of the belt conveyor 20. This dividing device 40 is provided with a crushing gear 41 having teeth 42 at equal intervals on the outer peripheral surface as shown in FIG. Since the crushing gear 41 is connected to the drive pulley 21 via a connecting mechanism 43 such as a timing belt or a chain, the crushing gear 41 keeps the compact D on the belt 23 constant in synchronization with the conveying speed of the belt conveyor 20. Granules G are obtained by dividing into dimensions. Therefore, even if the conveyance speed of the belt conveyor 20 changes, the length of the granulated body G does not change.

The divided granules G are still in the belt 2
Although it is attached to No. 3, it is naturally peeled off by utilizing the reversal of the belt 23 by the drive pulley 21, and is recovered by the recovery hopper 44. In particular, since the surface of the belt 23 has water repellency, even if the water content of the dried granule G is slightly changed, it can be easily peeled from the belt 23. The granules G collected in the hopper 44 are carried to the next calcination step. The belt 23
When the granulation body G cannot be completely peeled off even if the reversal of is used, it may be peeled off using a simple scraper.

In the case of the structure in which the surface of the belt 23 is further laminated with a fluororesin film, the fine irregularities on the surface, which are the drawbacks of the conventional fluororesin, can be eliminated, and fine powder of raw material, oil, etc. can penetrate into the irregularities. The phenomenon of impairing the water repellency of the belt surface can be eliminated, and the belt life is improved. Further, since the surface of the belt is smooth, the collecting mechanism of the granules G at the end portion of the belt can be simplified, the cleaning mechanism of the belt can be simplified, and the labor for maintenance and inspection can be saved.

FIG. 8 shows another example of the dividing device. That is, a pair of upper and lower crushing gears 45 and 46 are provided behind the terminal end of the belt conveyor 20, and the compact D is divided between these gears 45 and 46. Also in this case, in order to synchronize the gears 45 and 46 with the belt 23, the gears 45 and 46 are synchronously driven by the drive pulley 21 via the coupling mechanisms 47 and 48. In this embodiment, since the crushing gears 45 and 46 do not come into contact with the belt 23, there is an advantage that an extra load is not applied to the belt 23.

FIG. 9 shows a second embodiment of the drying apparatus of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. An opening / closing control valve 50 composed of an electromagnetic valve is provided in the middle of the distribution tube 10, and the control valve 50 is controlled by a control device 51. The control device 51 is the opening / closing control valve 5.
0 is periodically opened and closed, and the ceramic slurry S is discharged on the belt conveyor 20 in a drip or intermittent manner. The discharged slurry S maintains a drip-like or intermittent string-like form due to surface tension. Drying oven 30 in this state
When the slurry S passes through, the slurry S changes into a granular or intermittent string-shaped molded body D, which is naturally peeled off by utilizing the inversion of the belt 23 by the drive pulley 21 and is collected by the collecting hopper 44. In this embodiment, since the slurry is already divided at the discharging stage, the drying and granulation can be performed without providing a dividing device at the end of the belt conveyor 20, and the device can be simplified.

The present invention is not limited to the above embodiment. For example, in the above embodiment, as the slurry discharge device,
Although the primary tank and the secondary tank are provided, the primary tank may be omitted and only the secondary tank may be provided. In addition, in order to discharge the slurry on the belt in a fixed amount, the liquid level of the secondary tank was controlled so that the slurry was discharged by the water head pressure.However, instead of the water head pressure, a discharge pump was used to discharge the slurry on the belt. May be discharged in a fixed amount. The drying means is not limited to the tunnel furnace-shaped drying furnace as in the embodiment, and any means can be used as long as the slurry can be continuously dried while being conveyed by a belt conveyor.

[0028]

As is apparent from the above description, according to the present invention, a series of steps such as discharging, molding, drying, and recovering the ceramic slurry is continuously performed along with the conveyance of the belt conveyor. The efficiency is greatly improved and the mechanism is very simple. Therefore, conventional drying,
The installation area can be significantly reduced compared to the granulator, and the area productivity is improved. Also, since the surface of the belt conveyor has water repellency, the surface tension makes it possible to maintain the moldability of the slurry at the time of discharge, and improves the releasability of the molded product from the belt after drying. The body can be recovered.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an example of a drying device according to the present invention.

FIG. 2 is a configuration diagram of a liquid level control mechanism of a secondary tank.

FIG. 3 is a perspective view of a main part of the slurry discharge device.

FIG. 4 is a sectional view of a flow rate adjusting valve.

FIG. 5 is an enlarged view showing a state in which the slurry is discharged onto the belt surface.

FIG. 6 is an enlarged view of another example showing a state in which the slurry is discharged onto the belt surface.

FIG. 7 is an enlarged side view of the dividing device.

FIG. 8 is a side view of another example of the dividing device.

FIG. 9 shows a second embodiment of the drying device of the present invention.

[Explanation of symbols]

 S Ceramics slurry D Molded body G Granulated body 1 Primary tank 4 Mud pump 5 Secondary tank 10 Distribution tube 11 Flow control valve 14 Slurry discharge device 20 Belt conveyor 23 Belt 30 Drying furnace 40 Dividing device

Claims (3)

[Claims] 1. A belt conveyor having a belt having at least a water-repellent surface, a slurry discharging device for continuously discharging a fixed amount of ceramic slurry on a belt surface of the belt conveyor in a single row or in a double row, and a ceramic slurry. A ceramics slurry on the belt conveyor is dried into a continuous string-shaped product while passing through the drying means, and the ceramics slurry is dried. apparatus. 2. The drying device according to claim 1, wherein a dividing device for dividing the dried cord-shaped molded body into equal sizes is provided at a terminal end portion of the belt conveyor. Ceramic slurry drying equipment. 3. A belt conveyor having a belt having a water-repellent surface at least, a slurry discharging device for intermittently discharging ceramic slurry on the belt surface of the belt conveyor in a single row or in multiple rows, and a ceramic slurry belt conveyor. The ceramic slurry on the belt conveyor is dried into intermittent granular or string-shaped molded products while passing through the drying means. Drying device.