JP3397251B2 - Method and apparatus for modifying coal ash - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing modified coal ash for effectively utilizing a large amount of coal ash generated in a power plant or the like using coal as an energy source.

[0002]

2. Description of the Related Art In recent years, with the expansion of coal utilization, the amount of coal ash discharged has reached enormous amounts. However, although most of such coal ash is disposed of in landfills, it is becoming difficult to secure such landfills year by year.

On the other hand, a simple method of using coal ash that has been used conventionally is to use it as a raw material for cement or a roadbed material. Since no significant increase in demand can be expected, regarding coal ash treatment measures, reforming of coal ash has become an important issue to promote effective utilization that can be utilized in new fields of application.

[0004] In order to solve the above problems, as an effective utilization method due to recycling by such a coal ash is high added value, by the coal ash by adding an alkali solution such as caustic soda to hydrothermal treatment, A method for modifying the artificial zeolite, which is a porous crystalline material, is described in, for example, Green Japan 83, 1990.7, pp. 35-37.

The method for producing the artificial zeolite will be described in detail.

First, coal ash and an aqueous sodium hydroxide solution whose concentration and temperature have been adjusted in advance are charged into a reaction tank, stirred and boiled to reform the coal ash into a porous crystalline substance (zeolite formation). .

[0007] Next, the porous crystalline material containing slurry after the hydrothermal treatment is transferred to a buffer tank, subsequently, the feed to the filter is drained machine than the buffer tank, the aqueous alkaline solution contained in the slurry Drain the liquid. Of these, the alkaline deliquored liquid is recovered and circulated and used as a raw material of an aqueous sodium hydroxide solution. On the other hand, the filter cake of the slurry that has been deliquored by the deliquoring machine is conveyed by a conveyor and loaded into a washing tank. At the same time, a large amount of washing water is supplied to the washing tank to perform stirring washing.

Next, the slurry containing the porous crystal substance, which has been washed in the water washing tank, is sent to a filter which is a dehydrator for dehydration treatment. Of this, a part of the dehydrated liquid is recovered, circulated and used as a raw material for the sodium hydroxide aqueous solution, and sent to the drainage treatment device outside most of the rest, and then drained.
On the other hand, solid matter containing artificial zeolite, which is a porous crystalline substance obtained by dehydration with a dehydrator, is conveyed by a conveyor, and depending on the application, it is necessary in addition to the product dried by air-drying as it is. It is described that the product is sent to equipment and subjected to granulation processing or the like to obtain a product.

The artificial zeolite, which is a porous crystalline substance obtained by these methods, has a cation exchange function and an adsorption function, and therefore can be used as a soil improver or an adsorbent.

However, the method for producing the above artificial zeolite (Green Japan 83, 1990.7, 35-35)
(Page 37, etc.) only describes a method for producing an artificial zeolite by using sodium hydroxide in an alkaline aqueous solution, and does not describe an ion exchange method for further ion exchanging them.

On the other hand, calcium-type zeolite is indispensable as a zeolite used for soil conditioner and special deodorization (especially for ammonia), and even in the above artificial zeolite, sodium ion is used as calcium when it is used for such a purpose. Although it is necessary to perform ion exchange with ions, there is no technical disclosure or suggestion regarding artificial zeolite for such an ion exchange method.

In addition to the above-mentioned artificial zeolite, natural zeolites such as mordenite zeolite and clinoptilolite zeolite which are naturally produced as zeolite, sodium hydroxide, sodium silicate,
So far, synthetic zeolites industrially produced from colloidal silica, sodium aluminate, etc. have been known.

Among these natural zeolites and synthetic zeolites, calcium-type zeolite is essential for the soil conditioner and the zeolite used for special deodorization (especially ammonia).

Of these, natural zeolite can be produced by crushing natural calcium-type zeolite rock as it is, calcinated and processed, and therefore has an advantage that it can be produced at a lower cost than synthetic zeolite. Therefore, the soil improvers currently on the market are of natural zeolite type.

However, in the case of the above natural zeolite, as one index for judging the quality of the zeolite, it is a cation exchange capacity (an index showing how much cation can be ion-exchanged). Hereinafter, simply referred to as CEC), but synthetic zeolite is 400
˜600 meq / 100 g, and further 150 to 350 meq / 100 g for the artificial zeolite, whereas the natural zeolite is as low as 150 meq / 100 g or less. Therefore, at present, it is desired to establish a low-cost, high-performance calcium exchange method for the artificial zeolite as an alternative to natural zeolite.

On the other hand, in the case of synthetic zeolite, the method for exchanging calcium is described in Chemical Process Collection, Tokyo Kagaku Dojin, pp. 249-252.

In the above calcium exchange method, first, as a crystallization step, raw materials of sodium hydroxide, sodium silicate and sodium aluminate are accurately weighed and added to a mixing tank, and a constant pH and a constant pH are obtained while stirring and mixing. After adjusting the concentration, the adjusted slurry is sent to a reaction tank (crystallization tank) and crystallized at about 100 ° C. under normal pressure to form a zeolite. Subsequently, in the filtration step, after completion of the reaction (crystallization), the slurry is sent to a rotary vacuum filter to separate a solid liquid and the zeolite as a filter cake. Further, in the ion exchange step, the filter cake is sent to an ion exchange tank by a conveyor, suspended in a heated calcium aqueous solution, and the temperature and contact time of the solution are adjusted to keep the ion exchange rate constant (about 40%).
%) To carry out an ion exchange reaction, and after the ion exchange is completed, it is filtered in the same manner as in the above filtration step to be separated as a zeolite filter cake, and then dried as it is to obtain a product, Alternatively, a method of forming a product after further granulating is described.

However, in the case of synthetic zeolite, silica gel and alumina, which are raw materials, are very expensive.
It is extremely expensive. Therefore, it is necessary to effectively utilize the excellent catalytic function of synthetic zeolite in a field where performance is more important than price, and it is not practical to use it as a soil conditioner.

Further, the present inventors have applied the above-mentioned synthetic zeolite calcium exchange method to the above-mentioned artificial zeolite, that is, using a filter cake after deliquoring, and suspending it in a heated calcium aqueous solution, As a result of carrying out ion exchange, it was confirmed that the ion exchange rate was about 50%, which was about the same as the conversion rate of the above synthetic zeolite, but the operation was actually performed because the filtration treatment after ion exchange was almost impossible. It turns out that it has many of the challenges above.

Therefore, it has been the current situation that no inexpensive and high-performance calcium exchange method using artificial zeolite has been found to date.

[0021]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a novel coal ash reforming method for effectively utilizing a large amount of coal ash generated in a power plant using coal as an energy source, especially calcium. your method of manufacturing-type zeolite
And a device therefor .

[0022]

In order to achieve the above-mentioned object, the present inventor has conducted earnest research on a new method for reforming coal ash, particularly a method for producing calcium-type zeolite, and as a result, the conventional calcium exchange method. In the case of using the filtered cake after deliquoring, and suspending this in a heated calcium aqueous solution for ion exchange, the alkaline aqueous solution remaining in the filter cake suspended the filtered cake in the heated calcium aqueous solution. At this time, the pH of the aqueous solution is about 1
It is as high as 2.5, and calcium in the aqueous solution produces needle crystals of calcium hydroxide, the crystal product increases aeration resistance during filtration, and the filtration treatment becomes impossible, and further, the ion exchange rate. Was significantly affected by the concentration of alkali metal ions such as sodium contained in the filter cake, and by removing the alkaline aqueous solution (alkali metal ions) remaining in the filter cake before performing the ion exchange, It has also been found that the pH can be reduced to less than 12.0 and the alkali metal ion concentration can be reduced, and further, ion exchange can be sufficiently performed at room temperature, which improves the filtration treatment after ion exchange. We also know that we can achieve a dramatic improvement in the ion exchange rate and produce the desired calcium-type zeolite. Which has led to the completion of the present invention based on.

[0023]

The object of the present invention is: (1) Add an alkaline aqueous solution to coal ash and make a slurry while stirring to obtain a temperature of 90.
After hydrothermal treatment at ˜100 ° C., the slurry is separated into an excess alkaline aqueous solution and a crystal product, and the slurry is cooled to a temperature of 70 ° C. or lower by heat exchange with water washing / drainage in the system, A coal characterized by separating the slurry into an excess alkaline aqueous solution and a generated crystal product, washing the crystal product with water, adding a calcium compound to the crystal product, and performing ion exchange at a pH of less than 12. It is also achieved by the method of ash modification.

Another object of the present invention is to ( 2 ) wash the crystal product with water, add a calcium compound and water to the dehydrated crystal product to form a slurry again, and perform ion exchange at a pH of less than 12. It is also achieved by the method for reforming coal ash shown in (1 ) above.

Another object of the present invention is that after ( 3 ) ion exchange is performed, the slurry is separated into a calcium-substituted crystal product and a solution, and then the calcium-substituted crystal product is washed with water. It is also achieved by the method for producing coal ash described in (1) or (2) above.

[0027] Another object of the present invention, (4) a crystallization step, by adding an alkali aqueous solution to coal ash, performing hydrothermal treatment at a temperature 90 to 100 ° C. was slurried with stirring
It has a hydrothermal reaction tank, and subsequently, as a filtration step, the produced slurry after completion of the reaction is cooled to a temperature of 70 ° C. or less by heat exchange.
And a filter for separating and filtering the slurry after the heat exchange into an excess alkaline aqueous solution and a crystal product. Further, as an ion exchange step, a calcium compound is added to form a crystal product. In the coal ash reformer having an ion exchange tank for performing ion exchange and a filter for separating and filtering the slurry after completion of the ion exchange into a calcium-substituted crystal product and a solution, ion exchange is performed in the ion exchange step. This can also be achieved by a coal ash reforming device characterized in that a washing tank for washing the crystal product with water is provided in advance.

[0028] Another object of the present invention, (5) an ion exchange step, the coal ash shown in the above (4), characterized in that a washing tank for performing washing separate filtered calcium substituted crystalline product It is also achieved by a reformer.

[0029]

[0030]

The present invention will be described in more detail based on the embodiments.

FIG. 1 is a schematic view showing an embodiment of a manufacturing apparatus used in the method for reforming coal ash according to the present invention.

As shown in FIG. 1, as the structure of the reforming apparatus 1 used in the method for reforming coal ash, first, a coal ash hopper 2 and a reaction liquid tank 3 are provided, which are equipped with a stirrer 6 through pipes 4 and 5. A transfer pump 8 is provided on the path of the pipe 5 connected to the upper tank portion of the reaction tank 7 provided. The lower tank part of the reaction tank 7 is connected to the upper part of the buffer tank 9 by a pipe 10, and a transfer pump 11 is provided on the path of the pipe 10.

Next, the lower portion of the buffer tank 9 is connected to the liquid remover 12 by a pipe 13, and a transfer pump 14 and a heat exchanger 15 are provided on the route of the pipe 13. A conveyor 16 is continuously provided below the liquid remover 12,
The other end of the conveyor 16 extends to the washing tank 17.
Further, the washing tank 17 has a pipe 18 for supplying washing water from outside the system.
Is provided, and a valve 19 is provided on the pipe 18.

Further, the lower tank portion of the water washing tank 17 is a dehydrator 2
0 and a pipe 21 are connected, and a transfer pump 22 is provided on the route of the pipe 21. The dehydrator 20
A conveyor 23 is continuously provided below.

Further, the drainer 12 is provided with the receiver tank 2
4 and a pipe 25, and the receiver tank 24 is connected to the vacuum pump 26 and the reaction solution tank 3 by a pipe 27, respectively.
A drainage pump 29 is provided on the path of the pipe 28.

An alkaline solution tank 30 is connected to the reaction solution tank 3 by a pipe 31, and a transfer pump 32 is provided on the path of the pipe 31.

Further, the dehydrator 20 is connected to a receiver tank 33 by a pipe 34, and the receiver tank 33 is connected to a vacuum pump 36 by a pipe 35. Further, the receiver tank 33 is connected to a wastewater treatment device (not shown) outside the system by a pipe 37 and is connected to the reaction liquid tank 3 by a pipe 38 branched from the pipe 37. A drainage pump 39 is provided on the path of the pipe 37, and a valve 40 and the heat exchanger 15 are provided on the path of the pipe 38.

Next, the other end of the conveyor 23 extends to the ion exchange tank 41. Further, a calcium storage tank 42 is connected to the ion exchange tank 41 by a pipe 43, a lower portion of the ion exchange tank 41 is connected to a dewatering device 44 by a pipe 45, and a transfer pump 46 is provided on a path of the pipe 45. It is provided. A conveyor 47 is continuously provided below the liquid remover 44, and the other end of the conveyor 47 extends to a washing tank 48. A pipe 49 for supplying washing water from outside the system is provided in the washing tank 48, and a valve 50 is provided on the pipe 49.

Further, the lower tank portion of the washing tank 48 is the dehydrator 5
1 and a pipe 52, and a transfer pump 53 is provided on the route of the pipe 52. The dehydrator 51
A conveyor 54 is continuously provided below.

The liquid remover 44 is provided in the receiver tank 5
5 and the pipe 56, and the receiver tank 55 is connected to the vacuum pump 57 and the ion exchange tank 41 by the pipe 5 respectively.
A drainage pump 60 is provided on the path of the pipe 59.

Further, the dehydrator 51 is connected to a receiver tank 61 by a pipe 62, and the receiver tank 61 is connected to a vacuum blower 64 by a pipe 63. The receiver tank 61 is connected to a wastewater treatment device (not shown) outside the system by a pipe 65, and a drainage pump 66 is provided on the path of the pipe 65.

A method of reforming coal ash using the reformed coal ash manufacturing apparatus 1 having the above structure will be described in detail.

First, the coal ash from the coal ash hopper 2, the alkali solution sent from the reaction solution tank 3 in advance from the alkali solution tank 30, and the alkali recovery liquid and the recovery cleaning water recirculated through the pipes 28 and 38. The alkali solution whose concentration and temperature have been adjusted by using is adjusted and charged into the reaction tank 7 through pipes 4 and 5, respectively, so as to have a predetermined solid-liquid ratio, and the reaction tank 7 is provided at a predetermined temperature. Stirring and boiling are performed by the stirrer 6 that is present, and a reaction for reforming the coal ash into a porous crystalline substance (zeoliticization) is performed.

The raw material coal ash used in the present invention is not particularly limited, and for example, fly ash, clinker ash, coal fuel ash or the like can be used. Such coal ash is, for example, a coal ash produced as a by-product when pulverized coal or the like is burned in thermal power generation or the like, and is collected from the airflow of a flue or the like. Therefore,
Although the particle size of coal ash at the time of collection is quite fine and it is possible to use it as it is, in order to enhance the reactivity (contact area), particles having a particle size of 50 μm or less are usually 98% or more, and particles having a particle size of 20 μm or less are 50% or less. % Or more, more preferably 1
It is desirable that the particles of 0 μm or less are crushed to be used in an amount of 30% or more. When 30% of the particles of the coal ash have a size of 30 μm or less, the contact area with the alkaline aqueous solution is reduced, the reaction efficiency is lowered, and the crystallization rate is lowered, which is not preferable.

The alkaline aqueous solution used in the present invention is not particularly limited and, for example, an aqueous solution of sodium hydroxide, potassium hydroxide or the like can be used.

The concentration of the alkali aqueous solution whose concentration has been adjusted is not particularly limited, but is usually 1 to 4
N, preferably 1.5 to 3N, more preferably 1.8 to
The range is 2.3N. The concentration of the alkaline aqueous solution is 1N
When it is less than 4, the cation exchange capacity (CEC) of the obtained porous crystal is not sufficient, and when it exceeds 4 N, the CEC of the obtained porous crystal is sufficient, but the porous crystal is The crystal structure of the product is significantly reduced for those with the Phillipsite structure (effective minimum diameter 4-5 angstroms),
Since the number of those having a hydroxy sodalite structure (effective minimum diameter of 2 to 3 angstroms) increases rapidly, it becomes difficult to adsorb gas such as ammonia ions having a large molecular weight, which is not preferable.

The temperature of the temperature-adjusted alkaline aqueous solution is usually 85 to 100 ° C., preferably 90 to 10 ° C.
The temperature is 0 ° C, and more preferably 98 to 100 ° C. When the temperature is less than 85 ° C, it takes time to heat to a predetermined reaction temperature, and when it exceeds 100 ° C,
Since it is necessary to heat using a pressure vessel, the equipment is large and the operating cost is high, which is not preferable. As such a temperature adjusting method, for example, a heater is provided in the reaction solution tank 3,
A method of providing a heating device on the path of the pipe 5 may be used.

The solid-liquid ratio of the coal ash used in the present invention and the alkaline aqueous solution is usually 0.5 to 3.0 liter / kg, preferably 1.5 to 2.5 liter / kg,
The range is more preferably 2.0 to 2.2 liter / kg. When the solid-liquid ratio is less than 0.5 liter / kg, the aqueous alkali solution is insufficient to form a slurry, and the mixture can be kneaded into a viscous paste state and cannot be sufficiently modified. If it exceeds 0 liter / kg, the solid concentration decreases and the relative speed between the solid and the liquid due to stirring decreases, so that the contact efficiency decreases and a sufficient reaction rate cannot be obtained, which is not preferable.

The boiling temperature during the reaction is usually 90 to 10
0 ° C, preferably 95-100 ° C, more preferably 98
Is in the range of -100 ° C If the temperature is lower than 90 ° C., the reaction rate will be significantly reduced and the reaction will take a long time. If the temperature is higher than 100 ° C., large high-pressure equipment will be required, which is commensurate with the cost required for heating. It is not preferable because the sufficient effect (improvement of crystallization rate, etc.) cannot be obtained.

The fluid velocity required for stirring in the present invention varies depending on the reaction solid-liquid ratio and the viscosity of the liquid, but is usually 0.7 to 3 m / sec, preferably 0.7 to 2 m / sec. , More preferably 1 to 2 m / se
The range is c. When the fluid velocity is less than 0.7 m / sec, the solid concentration used is large, so sufficient mixing (solid-liquid contact) by stirring is not performed, and a large amount of coal ash remains deposited on the bottom of the reaction tank 7. Is not preferable, and when it exceeds 3 m / sec, a sufficient effect (improvement in crystallization rate) commensurate with an increase in stirring force cannot be obtained, which is not preferable. Therefore, it is necessary to select the shape, size, number or the like of the stirring blades used in the stirrer 6 provided in the reaction tank 7 so as to achieve the above fluid velocity.

[0051] Incidentally, the porous crystalline material to be modified from the coal ash according to the invention are those obtained by treating hydrothermally in an alkaline one having a non-crystalline structure contained in the coal ash, generally chemical The composition is MeO ・ Al ₂ O ₃・ mSiO
₂・ nH ₂ O (Me varies depending on the alkali component used in alkali metals or alkaline earth metals such as Na ₂ and K ₂ ) and its crystal structure is mainly P type (phillipsite) However, by changing the concentration of the alkaline aqueous solution and the like, it is possible to manufacture those having a structure of H type (hydroxysodalite), Y type, A type and the like.

Next, the porous crystalline material containing slurry after the hydrothermal treatment is supplied with continued stirring, the aqueous alkaline solution from the newly reaction tank 3 in order to increase the solid-liquid ratio of the slurry in the reaction vessel 7 After being adjusted, it is transferred to the buffer tank 9 through the pipe 10.

Here, the solid-liquid ratio of the porous crystal-containing slurry is usually 2.5 to 3.5 liter / kg, preferably 2.5 to 3 liter / kg, more preferably 2.
The range is 5 to 2.7 liters / kg. When the solid-liquid ratio is less than 2.5 liters / kg, the solid concentration is too high, and therefore, pipe clogging and filtration failure when performing dewatering separation using a rotary vacuum suction filter in the dewatering device 12 may occur. It is not preferable because it occurs. Also, when a large excess of alkaline aqueous solution exceeding 3.5 liter / kg is used, the above-mentioned trouble does not occur, and recycling is possible by recovery,
It is not preferable because it requires a long time for cleaning in the subsequent step and requires an increase in the size of the device for large-scale use.

If the slurry has a solid-liquid ratio within the range, after the slurry is transferred to the buffer tank 9,
Further, an alkaline aqueous solution is added from the reaction solution tank 3 to the reaction tank 7
It is desirable that the inside of the pipe 10 can be cleaned by cleaning the inside of the tank and then supplying the buffer tank 9 through the pipe 10 to prevent the residual slurry from sticking to the inner wall of the reaction tank or the inner wall of the pipe. It is a thing.

As the alkaline aqueous solution to be supplied to the above-mentioned slurry, those adjusted to the same concentration and temperature as those supplied at the time of reaction can be used as they are, but these concentrations and temperature are not particularly important. May be unadjusted.

[0056] In the buffer tank 9, for continuously the subsequent step, the completed slurry reaction so as not to precipitate a solid component of the slurry, sequentially slurry with <br/> stirring by using a stirrer It is for temporary storage to transfer. For example, continuous processing capacity is 1.5t / h
In the case of r, assuming that the reaction time in the reaction tank 7 is completed in 5 hours, the reaction tank 7 and the buffer tank 9 can efficiently perform continuous treatment if the volumes are about 7.5 t. It should be noted that a huge reaction tank 7 and a buffer tank 9 are required for continuous processing with the same processing capacity when the reaction time is long as in the prior art, which requires equipment costs and operating costs. It was

Subsequently, the slurry is introduced from the buffer tank 9 into the heat exchanger 15 through the pipe 13, and while passing through the heat exchanger 15, heat exchange with the recovered washing water flowing through the pipe 38 causes a predetermined temperature. After cooling to, the slurry is continuously sent to the dewatering device 12 through the pipe 13 to dewater the alkaline solution contained in the slurry. Of these, the alkali dewatered liquid is collected by the vacuum pump 26 to the receiver tank 24 through the pipe 25,
Further, it is returned to the reaction liquid tank 3 through the pipe 28 by the drainage pump 29 and circulated for use.

The liquid remover 12 used in the present invention is not particularly limited as long as it can perform solid-liquid separation, but it is desirable that it can continuously perform solid-liquid separation. For example, a rotary vacuum suction filter, a centrifugal filter, etc. can be used. When the rotary vacuum suction filter is used, the degree of vacuum is 450 to 450 depending on the temperature of the slurry and the capacity of the vacuum pump 26 described later.
If it is 650 mmHg and the rotation speed is in the range of 1 to 5 rpm, it is possible to preferably continuously operate.

Further, the heat exchanger 15 used in the present invention is not particularly limited, and for example, a commonly used one such as a multi-tube heat exchanger or a countercurrent plate heat exchanger can be used. Can be used. At this time, it is necessary to select the heat transfer area, the pipe diameter, the structure, etc. in consideration of the required temperature condition, the flow rate, the pressure loss due to the viscosity of the fluid (slurry, cleaning water) used, and the like.

Further, the slurry temperature after being cooled by heat exchange with the recovered washing water flowing through the pipe 38 while passing through the heat exchanger 15 is usually 70 ° C. or lower, preferably 40 to 70 ° C. More preferably, it is in the range of 40 to 50 ° C. When the slurry temperature exceeds 70 ° C., the treatment capacity is suppressed to a very low level, the recovery rate of the excess alkaline aqueous solution becomes extremely low, and the filter cake after deliquoring becomes a sticky state, so that it is transferred to the conveyor 16. In addition to the difficulty in loading, the washing cost in the washing tank 17 in the next step requires an extremely large amount of washing water and time, which undesirably increases the manufacturing cost.

As the refrigerant used for heat exchange,
The above-mentioned recovered cleaning water is preferable, but in addition to the recovered cleaning water, the cleaning water drained through the pipe 37 may be drained after being used for the entire heat exchange, and a fresh refrigerant from outside the system may be used. (Solid, liquid and gas) may be used for heat exchange.

In the production method of the present invention, the method of cooling the slurry to a temperature of 70 ° C. or lower after the hydrothermal treatment is not limited to the above-mentioned heat exchange method. Any method can be used as long as it can be used as a conventional technique. For example, a method in which a refrigerant is directly added to the slurry from outside the system and cooled, or a buffer tank 9 is used. Any method such as a method of providing a cooling device and cooling in advance may be used.

Further, the vacuum pump 26 required for the present invention.
The suction capacity of the syrup depends on the temperature of the slurry, the viscosity, the temperature of the alkaline aqueous solution, etc.
~ 650 mmHg, preferably 480-600 mmH
g, and more preferably 520 to 580 mmHg. If the suction capacity is less than 450 mmHg, a sufficient suction force of the alkaline aqueous solution cannot be obtained, and the alkaline aqueous solution dewatered in the dewatering device 12 stays in the dewatering device 12, resulting in poor filtration. On the other hand, if it exceeds 650 mmHg, the amount of cake adhering decreases, and the processing capacity decreases significantly, which is not preferable.

On the other hand, the filter cake of the slurry that has been deliquored by the deliquoring machine 12 is conveyed by the conveyor 16 and loaded into the washing tank 17. At the same time, a large amount of washing water is supplied to the washing tank 17 through the pipe 18 to perform stirring washing.

Here, the solid-liquid ratio of the filter cake (solid) and the washing water (liquid) at the time of stirring and washing in the washing tank 17 is usually 7 to 20 liter / kg, preferably 10 to 15 liter / kg. It is a range. If the solid-liquid ratio is less than 7 liters / kg, the cleaning effect becomes insufficient, and depending on the intended use,
Due to residual alkali and alkali metal ions contained in the obtained porous crystal-containing solid, there is a problem that the ion exchange rate is lowered during the ion exchange in the next step and the pH of the solution is increased, resulting in poor filtration treatment. It is not preferable because it occurs. If the solid-liquid ratio exceeds 20 liters / kg, the washing is sufficient, but it is not preferable because it is not possible to expect an effect commensurate with an increase in equipment cost and an increase in operating cost due to the size of the washing tank 17. As the cleaning water, industrial water having excellent economy is generally used. However, when an aqueous solution of sodium hydroxide is used as the alkaline aqueous solution, if a large amount of alkali metal such as potassium is contained in the washing water, the ions are exchanged with sodium during washing, so that the ion exchange of the obtained porous crystalline material is performed. Since the function and the adsorption function are different, it is necessary to pay attention to the washing water used depending on the intended use.

In the present invention, the alkaline aqueous solution (alkali metal ion) remaining in the filter cake of the porous crystal-containing slurry is washed with a large amount of washing water as described above before the ion exchange. Although it is to be removed, the method for removing the alkaline aqueous solution (alkali metal) of the present invention is not limited to the above-mentioned water washing method, and the following conventionally used methods can also be used. However, as the method for removing the alkaline aqueous solution of the present invention, it is possible to use a neutralization treatment with an acidic solution such as hydrochloric acid, but the salt produced is left in the filter cake only by the neutralization treatment method. Therefore, the removal of the alkali metal is not sufficient and the ion exchange rate is lowered, which is not preferable, and in this case, it is necessary to sufficiently remove the salt with the washing water or the like.

Next, the porous crystal substance-containing slurry washed in the water washing tank 17 is transferred to the pipe 21 by the transfer pump 22.
To the dehydrator 20 for dehydration. Of these, the dehydrated liquid is collected by the vacuum pump 36 in the receiver tank 33, and a part of the dehydrated liquid is stored in the valve 4
0 is opened and is sent to the heat exchanger 15 through the pipe 37 and the branch pipe 38 by the drainage pump 39, and when passing through the inside of the heat exchanger 15, after exchanging heat with the porous crystal-containing slurry described above and raising the temperature. , Through the pipe 38, returned to the reaction liquid tank 3 and circulated for use, and most of the remaining dehydrated liquid is
It is sent to a drainage treatment apparatus outside the system through a pipe 37, treated, and then drained.

The dehydrator 20 used in the present invention is not particularly limited as long as it can perform solid-liquid separation, but it is desirable that it can continuously perform solid-liquid separation. For example, a rotary vacuum suction filter, a centrifuge or the like can be used.

The period in which the valve 40 is opened and the dehydrated liquid is supplied to the pipe 38 must be supplied at least while the porous crystal substance-containing slurry is being transferred to the heat exchanger 15 through the pipe 13. Otherwise, it is not preferable because the above-mentioned problems occur when the slurry is drained to the drainer 12 as described above.

On the other hand, the solid substance containing the porous crystalline substance according to the reforming method of the present invention obtained by dehydrating with the dehydrator 20 is
It is conveyed by the conveyor 23 and loaded into the ion exchange tank 41. Further, the ion exchange tank 41 is charged with a calcium-containing aqueous solution from a calcium storage tank 42 through a pipe 43 and a calcium recovery liquid which is recirculated through a pipe 59, and is stirred by a stirrer provided in the ion exchange tank 41. While slurrying again, the pH is usually adjusted to a predetermined pH at normal temperature, and ion exchange is performed in the slurry.

The pH of the slurry in the ion exchange tank 41 is usually less than 12.0, preferably 9-12, more preferably 9.5-10.5. When the pH is 12.0 or more, needle-like crystals of calcium hydroxide are produced, and after ion exchange is performed, the slurry is filtered during deliquoring separation into a calcium-substituted crystal product and a solution. In the case of (1), the needle-like crystals increase the ventilation resistance, which makes the filtration process impossible, which is not preferable.

The temperature and pressure of the slurry in the ion exchange tank 41 do not need to be adjusted, and ion exchange can usually be carried out at room temperature and atmospheric pressure in a short time.

Furthermore, the calcium-containing aqueous solution added to the solid substance containing the above-mentioned porous crystal is prepared by stirring and mixing water and a calcium compound in advance, but the present invention is not limited to the above-mentioned embodiment. However, water and the calcium compound may be separately added to the ion exchange tank 41.
Although the calcium compound is not particularly limited, it is preferably easily soluble in water, and examples thereof include calcium chloride, calcium bromide, calcium iodide, calcium nitrate and calcium acetate.

Further, since the calcium compound to be added has a different crystallization rate of the produced porous crystal due to the content of the non-crystalline component contained in the coal ash used, the ion content of the porous crystal is different. The amount of calcium ions used for exchange is also different, but usually 1 for the total weight of the coal ash.
It is 0 to 20% by weight, more preferably 13 to 17% by weight. If it is less than 10% by weight, ion exchange cannot be sufficiently carried out, and if it exceeds 20% by weight, sufficient effects cannot be obtained by the addition, and equipment and the like are undesirably large.

Next, the calcium-substituted crystal product-containing slurry after the completion of the ion exchange is continuously sent to the dewatering device 44 through the pipe 45 by the transfer pump 46 to dewater the solution contained in the slurry. Of these, the dewatered liquid is collected by the vacuum pump 57 into the receiver tank 55 through the pipe 56, and further returned to the ion exchange tank 41 through the pipe 59 through the drainage pump 60 for circulation and use.

Here, the liquid remover 44 used in the present invention is not particularly limited as long as it can perform solid-liquid separation, but it is desirable that it can continuously perform solid-liquid separation. For example, a rotary vacuum suction filter, a centrifugal filter, etc. can be used. When the rotary vacuum suction filter is used, the degree of vacuum is 450 to 450 depending on the temperature of the slurry and the capacity of the vacuum pump 26 described later.
If it is 650 mmHg and the rotation speed is in the range of 1 to 5 rpm, it is possible to preferably continuously operate.

On the other hand, the filter cake of the slurry dewatered by the dewatering device 44 is conveyed by the conveyor 47 and loaded into the washing tank 48. At the same time, a large amount of washing water is supplied to the washing tank 48 through a pipe 49 to perform stirring washing.

Here, the solid-liquid ratio of the filter cake (solid) and the washing water (liquid) at the time of stirring and washing in the washing tank 48 is usually 7 to 20 liter / kg, preferably 10 to 15 liter / kg. It is a range. If the solid-liquid ratio is less than 7 liters / kg, the cleaning effect becomes insufficient, and depending on the intended use,
Adhesion of sodium chloride and the like contained in the obtained calcium-type porous crystal-containing solid material is not preferable because it causes problems such as salt damage when used as a soil conditioner. If the solid-liquid ratio exceeds 20 liters / kg, washing is sufficient, but
This is not preferable because it is not possible to expect an effect commensurate with an increase in equipment cost and an increase in operating cost due to the increase in size of the washing tank 48. As the cleaning water, industrial water having excellent economy is generally used. However, when a large amount of alkali metal is contained in the washing water, ion exchange occurs during washing, and the ion exchange function and adsorption function of the obtained calcium-type porous crystal are different. Should also pay attention to the wash water used.

Next, the calcium type porous crystal-containing slurry that has been sufficiently washed in the water washing tank 48 is sent to the dehydrator 51 through the pipe 52 by the transfer pump 53 to be dehydrated. Of these, the dehydrated liquid is collected by the vacuum blower 64 in the receiver tank 61, and the dehydrated liquid is sent to a drainage treatment device outside the system through a pipe 65 by a drainage pump 66, and then drained.

The dehydrator 51 used in the present invention is not particularly limited as long as it can perform solid-liquid separation, but it is desirable that it can continuously perform solid-liquid separation. For example, a rotary vacuum suction filter, a centrifuge or the like can be used.

On the other hand, the solid substance containing the calcium-type porous crystal substance according to the reforming method of the present invention obtained by dehydration with the dehydrator 51 is conveyed by the conveyor 54, and is air-dried as it is depending on the application. In addition to drying it to produce a product, it is sent to the necessary equipment and subjected to granulation and the like to be processed into a product such as an adsorbent or a soil modifier.

[0082]

EXAMPLES Examples of the present invention will be described below.

Example 1 A calcium-type porous crystal product was produced using the production apparatus 1 used in the method for reforming coal ash shown in FIG.

First, from the coal ash hopper 2, particles of 50 μm or less of 100% fly ash 7.5 t, and from the reaction solution tank 3 having a heater function, the sodium hydroxide solution sent from the alkaline solution tank 29 in advance. The sodium hydroxide recovery liquid recirculated through the pipes 27 and 37 and the aqueous sodium hydroxide solution adjusted to a temperature of 100 ° C. using the recovered industrial water were reacted and solidified in the reaction tank 7 through the pipes 4 and 5, respectively. The mixture was adjusted and charged so that the liquid ratio was 2.2 liters / kg, and stirred and boiled by a stirrer 6 provided in the reaction tank 7 at a temperature of 100 ° C. at a fluid velocity of 1 m / sec. , From fly ash, the chemical composition is mainly Na ₂ O ・ Al ₂ O ₃ ・
3.5SiO went ₂ · 4.5H ₂ P type represented by O (Philip site) 5 hours reforming reaction to sodium form porous crystalline material serving artificial zeolite having a crystal structure of the.

[0085] Next, the porous crystalline material containing slurry after the hydrothermal treatment, with continued stirring, the porous crystalline material with an aqueous alkaline solution from the newly reaction tank 3 after the hydrothermal treatment was fed into the reaction vessel 7 The solid-liquid ratio of the contained slurry is 3.0 liters /
After adjusting to kg, it was transferred to the buffer tank 9 through the pipe 10.

Subsequently, the slurry is introduced from the buffer tank 9 through the pipe 13 into the multi-tube heat exchanger, which is the heat exchanger 15, and the pipe 3 is passed while passing through the heat exchanger 15.
After being cooled to a temperature of 50 ° C. by heat exchange with the collected wash water flowing through 8, the slurry is continuously sent through a pipe 13 to a continuous rotary vacuum suction filter which is a liquid remover 12, and a liquid removal treatment temperature is set. 50 ° C, vacuum suction force of the filter 48
The alkaline solution contained in the slurry was drained at 0 to 600 mmHg and a rotation speed of 1 to 5 rpm.

Of these, the alkali deliquoring is performed by the vacuum pump 2
By suctioning at 480-600 mmHg by 6,
It was recovered in the receiver tank 24 through the pipe 25, returned to the reaction liquid tank 3 through the pipe 28 by the drainage pump 29, and circulated for use.

On the other hand, the filter cake of the slurry dewatered by the dewatering machine 12 is conveyed by the conveyor 16 and charged into the washing tank 17, and a large amount of industrial water is filtered through the pipe 18 into the washing tank 17 to filter cake. The (solid) and industrial water (liquid) were supplied so as to have a solid-liquid ratio of 10.0 liter / kg, followed by stirring and washing.

Next, the porous crystal substance-containing slurry washed in the water washing tank 17 is supplied to the pipe 21 by the transfer pump 22.
To the vacuum suction filter, which is the dehydrator 20, for continuous dehydration treatment. Of these, the dehydrated liquid is the vacuum pump 36
It collects in the receiver tank 33 by sucking by
Some of the dehydrated liquid opens the valve 40 and the drainage pump 39
Through the pipe 37 and the branch pipe 38 by the heat exchanger 1
5, when passing through the inside of the heat exchanger 15, heat exchange with the above-mentioned porous crystal substance-containing slurry to raise the temperature to 70 ° C., and then return to the reaction liquid tank 3 through the pipe 38 for circulation. Most of the remaining dehydrated liquid used was sent to a drainage treatment device outside the system through a pipe 37, and then drained.

On the other hand, the solid substance containing the porous crystalline substance according to the reforming method of the present invention obtained by dehydrating with the dehydrator 20 is
It was conveyed by the conveyor 23 and loaded into the ion exchange tank 41. Further, the ion exchange tank 41 was charged with the calcium chloride aqueous solution from the calcium storage tank 42 through the pipe 43 and the calcium recovery liquid recirculated through the pipe 59. These charges were re-slurried while being stirred by a stirrer provided in the ion exchange tank 41, and the pH was 10.5 and the calcium ion content was 15% by weight based on the total weight of the coal ash at normal temperature. Ion exchange was carried out in the slurry by adjusting so that

Next, the calcium-substituted crystal product-containing slurry after completion of the ion exchange is transferred to the drainer 44 through the pipe 45 by the transfer pump 46 and the vacuum degree of 600 to 650 mm.
The solution contained in the slurry was drained by continuously sending it to a rotary vacuum suction filter having Hg and a rotation speed of 1 to 5 rpm. Of these, the dewatered liquid was collected by the vacuum pump 57 into the receiver tank 55 through the pipe 56, and returned to the ion exchange tank 41 through the pipe 59 through the drainage pump 60 for recycling.

On the other hand, the filter cake of the slurry dewatered by the dewatering device 44 was conveyed by a conveyor 47 and loaded into a washing tank 48. At the same time, a large amount of industrial water was supplied to the washing tank 48 through a pipe 49 at a solid-liquid ratio of the filter cake (solid) and the industrial water (liquid) of 10 liter / kg to perform stirring and washing.

Next, the calcium type porous crystal-containing slurry that had been sufficiently washed in the water washing tank 48 was sent to the rotary vacuum suction filter, which is the dehydrator 51, through the pipe 52 by the transfer pump 53 to be dehydrated. Of these, the dehydrated liquid is
It was collected in the receiver tank 61 by sucking it with the vacuum blower 64, and the dehydrated liquid was sent to the drainage treatment device outside the system through the pipe 65 by the drainage pump 66, and then drained.

On the other hand, the solid substance containing the calcium-type porous crystal substance according to the reforming method of the present invention obtained by dehydration with the dehydrator 51 is conveyed by the conveyor 54 and left as it is.
It was dried at 0 ° C. to obtain a solid powder containing a calcium type porous crystal.

1 g of the obtained solid powder was washed with 50 cc of ethyl alcohol, and 100 cc of 1N was added.
As a result of extraction with an aqueous solution of ammonium chloride and measurement of calcium ions in the solution by atomic absorption spectrometry, it was confirmed that the ion exchange rate and the exchange rate were 100%.

Further, in this example, needle crystals of calcium hydroxide were not formed in the filter cake at the time of removing liquid after ion exchange, and the aeration resistance of the filter cake was small, It was confirmed that the treatment can be performed extremely well.

[0097]

INDUSTRIAL APPLICABILITY According to the present invention, in the deliquoring treatment after ion exchange, the ventilation resistance of the filter cake is large and the filtration treatment becomes impossible, so that troubles such as the continuous operation of the subsequent steps cannot be continued occur. It is possible to produce an artificial zeolite, which is a high-performance calcium-type porous crystal substance with high stability and reliability without any cost. It becomes possible to use the coal ash as an effective resource.

Further, the artificial zeolite, which is a calcium type porous crystal obtained by the present invention, has an excellent ion exchange function and adsorption function. Therefore, if necessary, granulation is performed to replace the natural zeolite. It can be expected to be used in a wide range of fields such as soil modifiers and special deodorizers (especially for ammonia).

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a manufacturing apparatus used in a method for reforming coal ash according to the present invention.

[Explanation of symbols]

1 ... Coal ash reformer, 2 ... Coal ash hopper, 3 ... Reaction liquid tank, 4, 5,
10, 13, 18, 21, 25, 27, 28, 31, 3
4, 35, 37, 38, 43, 45, 49, 52, 5
6, 58, 59, 62, 63, 65 ... Piping, 6 ... Stirrer, 7 ... Reaction tank, 8, 11,
14, 22, 32, 46, 53 ... Transfer pump, 9 ... Buffer tank, 12, 44 ... Deliquor,
15 ... Heat exchanger, 16, 23, 47, 54 ... Conveyor,
17, 48 ... Washing tank, 19, 40, 50 ... Valve,
20, 51 ... dehydrator, 24, 33, 55, 61
... receiver tank, 26, 36, 57 ... vacuum pump,
29, 60 ... Drainage pump, 30 ... Alkaline solution tank, 39, 66 ... Drainage pump, 41 ... Ion exchange tank, 42 ... Calcium storage tank, 6
4 ... Vacuum blower.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A 61-178416 (JP, A) JP-A 54-40299 (JP, A) JP-A 6-100314 (JP, A) JP-A 6- 144829 (JP, A) JP 63-182214 (JP, A) JP 59-86687 (JP, A) JP 59-35019 (JP, A) JP 3-232716 (JP, A) JP-A-3-69509 (JP, A) JP-A-3-45512 (JP, A) JP-A-2-198630 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C01B 33/00-39/54

Claims (5)

(57) [Claims] 1. An alkaline aqueous solution is added to coal ash, which is slurried with stirring and hydrothermally treated at a temperature of 90 to 100 ° C., and then the slurry is subjected to heat exchange with washing / drainage in the system.
After cooling to a temperature of 70 ° C. or less by means of , the slurry is separated into an excess alkaline aqueous solution and a crystal product, the crystal product is washed with water, and a calcium compound is added to the crystal product to adjust the pH to less than 12. A method for reforming coal ash, characterized by performing ion exchange. 2. After washing the crystalline product, dried and reslurried by adding a calcium compound and water to the crystalline product, to claim 1, characterized in that the ion-exchange at less than pH12 A method for reforming coal ash as described. After the 3. ion exchange, after separating the slurry into a calcium-substituted crystalline product and solution according to claim 1 or 2, characterized in that the water washing treatment the calcium-substituted crystalline product Method for producing coal ash. 4. As a crystallization step, an alkaline aqueous solution is added to coal ash, and the mixture is slurried with stirring to a temperature of 90 to
A hydrothermal reaction vessel for performing hydrothermal treatment at 100 ° C., as subsequently filtration step, the resulting slurry after completion of the reaction the heat exchange
A heat exchanger for cooling to a temperature of 70 ° C or lower is provided,
An ion exchange tank having a filter for separating and filtering the slurry after the heat exchange into an excess alkaline aqueous solution and a crystal product, and an ion exchange step for ion exchanging the crystal product by adding a calcium compound as an ion exchange step, and In a coal ash reformer having a filter for separating and filtering the slurry after completion of the ion exchange into a calcium-substituted crystal product and a solution, washing the crystal product with water before performing ion exchange in the ion exchange step. An apparatus for reforming coal ash, characterized in that it is provided with a washing tank for performing. 5. The apparatus for reforming coal ash according to claim 4 , further comprising a washing tank for washing the separated and filtered calcium-substituted crystal product with water in the ion exchange step.