JP2002338238A - Apparatus for manufacturing zeolite and method for manufacturing zeolite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for manufacturing zeolite which is capable of efficiently manufacturing the zeolite from fly ash which is heretofore handled as waste as raw material and a method for manufacturing the zeolite. SOLUTION: The apparatus 1 for manufacturing the zeolite is constituted by a slurry preparation chamber 2 which makes a slurry uniform by adding an aqueous sodium hydroxide solution to the fly ash and stirring the mixture, a spreading mechanism 3 which spreads the slurry prepared in the slurry preparation chamber 2 to a prescribed thickness and a heating furnace 4 which heats the slurry spread by the spreading mechanism 3 while conveying the slurry by a conveyance mechanism 23. The zeolite is manufactured by heating the slurry to effect a hydrothermal reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus and a method for producing zeolite using fly ash as a raw material.

[0002]

2. Description of the Related Art In a coal-fired power plant, fly ash discharged after burning coal in a boiler is mainly composed of silicon oxide and aluminum oxide.
It accounts for 0%. The fly ash is sometimes used as a heat insulating material, a cement admixture, a cement raw material, a landfill construction material, a land improvement material, and the like.

[0003]

However, the amount of fly ash generated is enormous, and only a very small portion is actually used effectively, and most of it is dumped as waste. However, there are problems such as the location and cost of dumping.

[0004] Therefore, the inventor paid attention to zeolite and tried to impart usefulness by changing the properties of fly ash. In other words, they noticed that fly ash could be a new resource if it could be converted to zeolite. This is because zeolite is a hydrous silicate mineral containing sodium, potassium, aluminum and the like, and can be used as an adsorbent for water purification treatment or as a catalyst for chemical reactions.

The present invention has been proposed in view of the above, and an object of the present invention is to provide an apparatus and a method for efficiently producing zeolite using fly ash, which is merely waste.

[0006]

Means for Solving the Problems The present invention has been made to achieve the above-mentioned object, and the invention according to claim 1 provides a method for producing a slurry by adding an alkaline solution to fly ash and stirring. , A spreading mechanism for extending the slurry adjusted in the slurry adjusting tank to a predetermined thickness, and a heating furnace for generating a zeolite by performing a hydrothermal reaction by heating the slurry extended by the spreading mechanism And a zeolite manufacturing apparatus.

According to a second aspect of the present invention, the heating furnace comprises:
The zeolite manufacturing apparatus according to claim 1, further comprising a transport mechanism for transporting and passing the slurry therein.

According to a third aspect of the present invention, there is provided a slurry adjusting step of adjusting a slurry by adding an alkaline solution to fly ash and stirring the slurry, and a spreading step of extending the slurry adjusted in the slurry adjusting step to a predetermined thickness. And a heating and generating step of generating a zeolite by heating the slurry stretched in the spreading step to cause a hydrothermal reaction to generate zeolite.

The invention according to claim 4 is characterized in that the heating and producing step is a step of producing a zeolite by carrying out a hydrothermal reaction by heating the slurry stretched in the spreading step while conveying the slurry. Item 4. A method for producing a zeolite according to Item 3.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a zeolite manufacturing apparatus 1 according to one embodiment of the present invention. The zeolite manufacturing apparatus 1 includes a slurry adjusting tank 2 for homogenizing the slurry by adding an aqueous sodium hydroxide solution, which is a kind of alkaline solution, to fly ash, and stirring the slurry. It is roughly constituted by a spreading mechanism 3 for expanding the thickness, and a heating furnace 4 for heating the slurry expanded by the spreading mechanism 3.

The slurry adjusting tank 2 is provided with a hopper 5 at its upper part for introducing fly ash therein,
An opening / closing valve mechanism 6 is provided at a lower end outlet portion of the hopper 5,
Further, an aqueous solution supply pipe 8 for supplying an aqueous solution of sodium hydroxide from an aqueous solution tank 7 is connected, and a stirring mechanism 9 for stirring the supplied fly ash and the aqueous solution of sodium hydroxide is provided therein. 10 is connected to a slurry transfer pipe 12 provided with a transfer pump 11 on the way.

Further, a buffer plate 13 for receiving fly ash is provided inside the slurry adjusting tank 2. The buffer plate 13 has a downward slope from the inner wall of the slurry adjusting tank 2 toward the slurry liquid level below the hopper 5, and if such a buffer plate 13 is provided, fly ash is directly discharged from the hopper 5 to the slurry adjusting tank 2. The slurry can be prevented from dropping into the slurry stored in the slurry 2 and splashing and sticking to the top plate and the side wall of the slurry adjusting tank 2. Therefore, it is possible to prevent the slurry from remaining in the slurry adjusting tank 2 as much as possible.

The on-off valve mechanism 6 comprises a gate valve 14 for opening and closing the outlet of the hopper 5 and a cylinder 15 for driving the gate valve 14 to open and close. And
The opening / closing valve mechanism 6 allows the amount of fly ash to be charged into the slurry adjusting tank 2 to be adjusted.

The stirring mechanism 9 connects a shaft 21 to an output shaft of a motor 20 mounted on the upper part of the slurry adjusting tank 2.
The lower end of the shaft 21 has a plurality of blades 22. When the motor 20 is driven, the blades 22 rotate in the fly ash and the aqueous sodium hydroxide solution, mix the fly ash and the aqueous sodium hydroxide solution to generate a slurry, and make the concentration of the entire slurry substantially uniform. Can be adjusted. The stirring mechanism 9 is not limited to the rotary blade type, and includes a cylinder and a plate attached so as to extend vertically from the rod tip to the rod, and adjusts the concentration of the slurry by reciprocating the plate in the slurry. It may be.

The aqueous solution tank 7 is for adjusting the aqueous sodium hydroxide solution to be supplied to the slurry adjusting tank 2, and includes a water tank 16 for storing water and a sodium hydroxide tank 17 for storing sodium hydroxide. Valve 1
They are connected via pipes provided with 8a and 18b. The aqueous solution tank 7 is provided with a stirrer (not shown) for stirring the water and sodium hydroxide flowing from each of the tanks 16 and 17,
The concentration of the aqueous sodium hydroxide solution can be adjusted uniformly. This stirrer is suitably equipped with a screw rotated by a motor, but is not limited to this as long as it has the same effect.

The valves 18a and 18b can be applied to manually opened / closed valves. However, in order to easily adjust the concentration of the aqueous sodium hydroxide solution in the aqueous solution tank 7 to an appropriate concentration, which will be described later, an electromagnetic open / close control is used. It is preferable to use a valve which can be set in advance so as to supply necessary amounts of water and sodium hydroxide necessary for producing an aqueous sodium hydroxide solution.

One end of an aqueous solution supply pipe 8 for connecting the aqueous solution tank 7 and the slurry adjusting tank 2 is connected to a lower portion of the side surface of the aqueous solution tank 7, and a valve 19 provided on the way supplies water to the slurry adjusting tank 2. The supply amount of the aqueous sodium solution can be adjusted. As for the valve 19, a valve that can be controlled to open and close as described above is suitable.

A transfer pump 11 provided in the middle of the slurry transfer pipe 12 transfers the slurry adjusted in the slurry adjusting tank 2 to the heating furnace 4 side, and an outlet of the transfer pipe 12 connected to its discharge port will be described later. Located above the transport mechanism 23,
The slurry in the slurry adjusting tank 2 is transferred onto the starting end of the transfer mechanism 23. Here, the transfer pump 11 is suitably a slurry pump, but may be any pump capable of transferring a solid-liquid two-phase fluid.

Next, the extension mechanism 3 provided at the starting end of the transport mechanism 23 will be described. The extending mechanism 3 is for extending the slurry transferred from the slurry adjusting tank 2 to an appropriate thickness for causing a hydrothermal reaction in the heating furnace 4.
(A) As shown in FIG.
, A screw shaft 26 rotatably attached to the plate 24 and screwed to the bracket 25, and a handle 27 attached to the upper end of the screw shaft 26. The plate 24 is a guide 28,
28 are slidably fitted between the handle 28
When the plate 7 is rotated forward and backward, the plate 24 moves up and down, so that the distance between the plate 24 and the surface of the transport mechanism 23 described later can be adjusted. Therefore, by passing the slurry under the plate 24, the slurry can be adjusted to a desired thickness.

The heating furnace 4 for heating the slurry extended by the spreading mechanism 3 has a heater 29 and a temperature sensor (not shown) inside the heating furnace 4, and detects the temperature in the furnace from the temperature sensor. In response to the signal, the power supply of the heater 29 is turned on or off to adjust the temperature in the furnace.
The heating furnace 4 is not limited to the above-described means, and may be any heating furnace having a temperature control function in the furnace.

Further, the heating furnace 4 is provided with a transfer mechanism 23 for transferring the slurry through the heating furnace 4 so as to be substantially horizontal through the inside of the heating furnace 4. Further, the collection container 30 for collecting zeolite generated by the hydrothermal reaction of the slurry,
It is arranged below the end of the transport mechanism 23 protruding from the outlet of the heating furnace 4.

A transport mechanism 23 for loading and transporting the slurry
Is an endless belt 31 that is placed with the slurry extended.
And the rollers 32 at both ends of the endless belt 31
32, and a motor (not shown) such as a servomotor for rotating and driving one of the rollers 32, and is arranged in a state where the starting end is located below the outlet of the slurry transfer pipe 12. Here, since the endless belt 31 is heated by passing through the heating furnace 4, a belt made of a material having heat resistance is used, for example, a steel belt is suitable. In addition,
As will be described later, since the temperature condition for causing the hydrothermal reaction of the slurry is about 90 to 100 ° C., an endless belt made of a material that can sufficiently withstand such a temperature may be used.

The plate 24 is placed above the endless belt 31 in order to prevent the spread slurry from further spreading and becoming uneven in thickness and from spilling from the transport mechanism 23.
It is desirable to provide stopper walls 33, 33 from both the left and right ends toward the downstream of the transport mechanism 23. The lower ends of the stopper walls 33 and 33 are always in contact with the surface of the endless belt 31 so that the slurry is brought into contact with the surface of the belt and the stopper walls 33 and 3.
It is preferable to provide it so as not to leak from the gap with the lower end of 3. For example, a plate-like synthetic rubber that is in close contact with the belt surface due to elasticity is suitable.

Next, a zeolite manufacturing method using the zeolite manufacturing apparatus 1 having the above configuration will be described.

First, water is supplied from the water tank 16 and sodium hydroxide is supplied from the sodium hydroxide tank 17 to the aqueous solution tank 7, and the aqueous sodium hydroxide solution is stored in a state adjusted to a predetermined concentration. 5 is charged with fly ash (preparation step).

The opening / closing valve mechanism 6 and the valve 19
, And fly ash and an aqueous sodium hydroxide solution are supplied into the slurry adjusting tank 2 at a predetermined ratio, and the mixture is stirred by the stirring mechanism 9 to form a slurry. Then, stirring is continued to make the concentration of the entire slurry uniform. Keep (slurry adjustment step). At this time, the aqueous sodium hydroxide solution mixed in the aqueous solution tank 7 has a concentration of 3.0 to 4.0 mol.

Next, the slurry whose concentration has been adjusted to be uniform is transferred from the slurry adjusting tank 2 to the endless belt 31 of the transport mechanism 23 by the transfer pump 11, and passes under the extension mechanism 3 to be moved to the endless belt 31. 5-50m above
It is extended to a thickness of about m, and is conveyed into the heating furnace 4 while being placed on the endless belt 31 (extension step).

The slurry conveyed to the heating furnace 4 is heated to about 90 to 100 ° C. in the heating furnace 4 whose temperature has been adjusted, thereby causing a hydrothermal reaction to generate zeolite (heating generation step). At this time, the heating time of the slurry requires about 8 hours. Therefore, the transport speed of the transport mechanism 23 is set so that the time required for the slurry to be carried into and out of the heating furnace 4 and the heating time of the slurry substantially coincide with each other. That is, the endless belt 3
Set the running speed of 1.

When the heated slurry undergoes a hydrothermal reaction, it is converted into zeolite according to the following substance conversion formula. _{^{SiO 2 + 2OH - → SiO 2}} 4- + 2H + Al 2 O 3 + 2OH - → 3H 2 O → 2Al (OH) 4 - SiO 2 4- + Al (OH) 4 - → HO · Si (· O
^{_{H) 2 - Al (· OH}} ) OH HO · Si (OH) 2 Al (· OH) OH + Na + + O
H ⁻ → Na ₆ Al ₆ Si ₁₀ O ₃₂ H ₂ O

FIG. 5 shows the results of X-ray analysis of the slurry after the hydrothermal reaction, and FIG. 6 shows electron micrographs of the slurry before and after the reaction. In FIG. 5, peaks of Al ₆ Si ₁₂ O ₁₃ and Al ₂ SiO ₅ were observed at the arrows, and it was confirmed that they contained a crystalline compound as zeolite. Also, from the fly ash FA shown in FIG. 6A, the zeolite Z shown in FIG.
It can be seen that L has been generated.

The generated zeolite is placed on the transport mechanism 23 and carried out of the heating furnace 4. And the transport mechanism 2
At the end of 3, endless belt 31 carrying zeolite
When the zigzag curve follows the shape of the roller 32, the zeolite is separated from the endless belt 31, and then falls from the endless belt 31 and is collected in the collection container 30.

The above-described slurry thickness, heating temperature, and heating time are merely examples, and various conditions can be set by considering the amount of heat applied to the slurry per unit time.

In the above embodiment, the plate 2
4, the spreading mechanism 3 is used to spread the slurry.
As shown in (b), the same effect can be obtained as the extension mechanism 3 that attaches the rotatable roller 34 to extend the slurry, and a fluorine resin coating or the like is applied to the cylindrical surface of the roller 34 to prevent the slurry from adhering. The surface treatment makes it easy to spread the slurry with a substantially constant thickness at all times.

In the above-described embodiment, there is a possibility that the zeolite may not completely be removed from the endless belt 31 but remain adhered to the end of the transport mechanism 23, so that zeolite which cannot be recovered may come out. Therefore, as shown in FIG. 3, the scraper 35 or
A zeolite removal mechanism 37 such as a brush roll 36 that is driven to rotate may be provided. Such a zeolite removal mechanism 3
By providing 7, the zeolite adhering to the endless belt 31 can be easily collected without being left.

In addition to the above-described embodiment, the transport mechanism 23 may be configured such that a plurality of containers 38 such as buckets and trays are pivotally mounted on the belt surface as shown in FIG. If the transport mechanism 23 is used, the generated zeolite can be manufactured to have a certain shape. If the inner surface of the container 38 has been subjected to a surface treatment such as the above-mentioned fluororesin coating, the zeolite is easily peeled from the container 38 at the time of recovery.

In the above embodiment, the aqueous solution of sodium hydroxide was used to produce the slurry. However, the present invention is not limited to this, and zeolite can be produced by using an alkaline solution containing calcium, potassium, etc. An effect similar to that of the embodiment is obtained.

[0037]

As described above, according to the present invention, the following effects can be obtained. According to the first and third aspects of the present invention, zeolite is produced by adding an alkaline solution to fly ash to form a slurry and then heating it to cause a hydrothermal reaction, thereby producing zeolite. Using fly ash as a raw material, zeolite that can be expected to be used effectively can be efficiently produced. Therefore, fly ash can be used as a new resource.

According to the second and fourth aspects of the present invention, when the slurry is heated to produce zeolite,
Since the slurry is heated while being transported to cause a hydrothermal reaction to generate zeolite, zeolite can be continuously produced. Therefore, it is possible to continuously treat fly ash, which is a huge amount of waste, and to contribute to a reduction in the amount of discarded waste.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a zeolite production apparatus.

FIGS. 2A and 2B are schematic enlarged views of the extension mechanism.

FIGS. 3A and 3B are schematic enlarged views of a slurry removing mechanism.

FIG. 4 is a schematic enlarged view of an example of a transport mechanism.

FIG. 5 is an X-ray analysis result of the slurry after the hydrothermal reaction treatment.

FIG. 6A is an electron micrograph of the slurry before the hydrothermal reaction, and FIG. 6B is an electron micrograph of the slurry after the hydrothermal reaction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Zeolite manufacturing apparatus 2 Slurry adjusting tank 3 Extension mechanism 4 Heating furnace 5 Hopper 6 Opening / closing valve mechanism 7 Aqueous solution tank 8 Aqueous solution supply pipe 9 Stirring mechanism 10 Slurry outlet 11 Transfer pump 12 Slurry transfer pipe 13 Buffer plate 14 Gate valve 15 Cylinder 16 Water tank 17 sodium hydroxide tank 18a, 18b valve 19 valve 20 motor 21 shaft 22 blade 23 transfer mechanism 24 plate 25 bracket 26 screw shaft 27 handle 28 guide 29 heater 30 collection container 31 endless belt 32 roller 33 stopper wall 34 roller 35 scraper 36 brush Roll 37 Zeolite removal mechanism 38 Container FA Fly ash ZL Zeolite

Claims (4)

[Claims] A slurry adjusting tank for homogenizing the slurry by adding an alkaline solution to the fly ash and stirring the slurry; a spreading mechanism for spreading the slurry adjusted in the slurry adjusting tank to a predetermined thickness; and a spreading mechanism. A heating furnace for generating a zeolite by heating the slurry extended by the above to cause a hydrothermal reaction, thereby producing a zeolite. 2. The zeolite production apparatus according to claim 1, wherein the heating furnace includes a transport mechanism for transporting and passing the slurry therein. 3. A slurry adjusting step of adjusting the slurry by adding an alkaline solution to the fly ash and stirring the slurry, a spreading step of spreading the slurry adjusted in the slurry adjusting step to a predetermined thickness, and a slurry expanded in the spreading step. And producing a zeolite through a hydrothermal reaction to produce zeolite by heating the zeolite. 4. The zeolite production according to claim 3, wherein the heating and generating step is a step of generating a zeolite by performing a hydrothermal reaction by heating the slurry stretched in the spreading step while transporting the slurry. Method.