JP2003326232A - Method and apparatus for washing calcium-containing dust with water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To continue the operation of a belt filter and a mixing tank stably by preventing the clogging of a grid of the belt filter and the scaling trouble of the mixing tank, a filtrate pipeline, or the like, by washing calcium-containing dust such as fly ash and chlorination-bypassed dust with water. <P>SOLUTION: Gypsum dihydrate is suspended in water together with the calcium- containing dust in this method for washing the calcium-containing dust with water, namely, when the calcium-containing dust is mixed with water to obtain slurry, a water-soluble component is dissolved in the water and then the water containing the water-soluble component is removed. In the concrete, water is mixed forcibly with gypsum dihydrate, to which the calcium-containing dust is then added to obtain the slurry being the mixed solution of the calcium-containing dust, water and gypsum dihydrate, the water-soluble component of the calcium-containing dust is dissolved in the water and then the water containing the water-soluble component is removed. It is suitable that water, gypsum dihydrate and the calcium-containing dust are mixed forcibly with one another, the water-soluble component of the calcium-containing dust is dissolved in the water and then the water containing the water-soluble component is removed. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for washing calcium-containing dust with water.
The present invention relates to a method and apparatus for washing calcium-containing dust, which removes water-soluble chlorine compounds from dust containing calcium such as chlorine bypass dust by washing with water.

[0002]

2. Description of the Related Art In recent years, recycling of waste such as incinerated fly ash by using it as a raw material for cement has been promoted. However, as the amount of waste treated increases, the amount of volatile components such as chlorine brought into the cement kiln also increases. It has been increasing, causing problems such as clogging of preheaters in cement manufacturing equipment. Therefore, it is used as a raw material for cement after removing chlorine components from incineration fly ash in advance.

At this time, by utilizing the water-soluble chlorine compound's property of being easily dissolved in water, chlorine is eluted by mixing incineration fly ash and the like with water and then filtered using a belt filter to obtain the resulting dewatered product. Salt cake is used as a raw material for cement. In addition, the wastewater from the belt filter is purified so that incineration fly ash can be effectively used without causing environmental pollution.

On the other hand, chlorine, sulfur, alkali, etc. which cause problems such as clogging of the preheater in the cement manufacturing facility, paying attention to the fact that chlorine is a problem, from the kiln bottom of the cement kiln to the bottom cyclone. Chlorine bypass equipment is used to remove chlorine by extracting part of the combustion gas from the kiln exhaust gas flow path.

In this chlorine bypass facility, for example, as described in International Patent Application PCT / JP96 / 03545 (International Publication Number: WO97 / 21638), chlorine is added to the fine powder side of dust produced by cooling the extracted exhaust gas. Is unevenly distributed, the dust is separated into coarse powder and fine powder by a classifier, the coarse powder is returned to the cement kiln system, and the separated fine powder (chlorine bypass dust) containing potassium chloride (KCl) is recovered. Then, it was added to the cement grinding mill system.

However, as described above, in recent years, the recycling of waste as a raw material for cement or conversion to fuel has been promoted, and as the amount of waste processed increases, the volatilization of chlorine, sulfur, alkali, etc., brought into the cement kiln. The amount of components has also increased, and the amount of chlorine bypass dust generated has also increased. Therefore, all chlorine bypass dust could not be used in the cement crushing process and was washed with water,
Since it is expected that the amount of chlorine bypass dust generated will further increase in the future, the development of an effective utilization method has been required.

From this point of view, Japanese Patent Laid-Open No. 11-100
In the method for treating cement as a raw material for cement described in Japanese Patent No. 243, in order to effectively utilize chlorine bypass dust, which has been conventionally landfilled, as a raw material for cement, water is added to waste containing chlorine to generate waste. The water-soluble chlorine compounds in the product are eluted and filtered, and the resulting desalted cake is used as a cement raw material, and the wastewater is purified and treated to effectively use chlorine bypass dust without causing environmental pollution. .

A water washing apparatus as shown in FIG. 4 is used for desalting dust such as incineration fly ash and chlorine bypass dust.

This water washing treatment device 21 includes a mixing tank 22 and a bed.
Water filter W ₂, W₃And Dust D
Is mixed and stirred in a mixing tank 22 to form a water-soluble slurry.
After dissolving the components, the slurry S is put into the slurry pump 24.
Therefore, the water W is supplied to the belt filter 23.₁By
Remove water with vacuum pumps 25 and 26 while washing with water
To obtain desalted cake C from which water-soluble chlorine compounds have been removed.
It is used as a ment ingredient. Also, the vacuum pump 2
Water containing water-soluble chlorine compounds, which was removed by suction in 5 and 26
W₂And some water W₃Is returned to the mixing tank 22 and water W_FourIs pure
Is processed.

Belt filter 23 used here
Is, for example, as shown in FIG.
Vacuum trays 27A and 27B communicating with the
The grid 28 is provided above the grids 7A and 27B, and the endless belt-shaped filter cloth 29 running above the grid 28 is provided.

The vacuum trays 27A and 27B are provided with rails 30.
It is possible to reciprocate on the rail 30 along the traveling direction of the filter cloth 29 by a driving unit (not shown) via a plurality of rollers 31 arranged above.

As shown in FIG. 6, the grid 28 has a plurality of rectangular openings 2 in a plate member 28a made of resin or the like.
8b is bored, and a plurality of leg portions 28c are projectingly provided on the lower portion of the plate member 28a.

As shown in FIG. 5, the filter cloth 29 is supported by a plurality of rollers 34 and rotates in the direction of the arrow. A supply tray 32 for supplying the slurry S and a cleaning water tray 33 for supplying water W ₁ for cleaning the slurry S are arranged above the filter cloth 29.

Then, the slurry S is supplied from the supply tray 32 onto the filter cloth 29 while the vacuum degree of the vacuum trays 27A and 27B is increased by the vacuum pumps 25 and 26.
The desalted cake C is obtained by moving the filter cloth 29 and vacuum-filtering the slurry S while washing with the water W ₁ supplied from the washing water tray 33.

[0015]

However, in the above-mentioned conventional washing treatment apparatus 21 (see FIG. 4), for example, incineration fly ash is mixed with water alone in the mixing tank 22 to elute the water-soluble chlorine compound. After that, if it is filtered using the belt filter 23, the belt filter 2 is removed after 1 to 2 months.
The grid 28 of No. 3 (see FIG. 5) is clogged and the operation cannot be continued. When chlorine bypass dust is mixed with incineration fly ash and treated in the same manner, chlorine bypass dust contains a large amount of calcium. For example, when chlorine bypass dust is added at about 40% by weight,
The grid 28 of the belt filter 23 becomes clogged in about 10 days. Furthermore, when chlorine bypass dust is mixed with water alone to elute the water-soluble chlorine compound and then filtered using the belt filter 23, the grid 28 becomes clogged in about 12 hours, and operation becomes impossible. was there.

Therefore, the present invention has been made in view of the above-mentioned problems in the prior art. When the dust containing calcium such as incinerated fly ash and chlorine bypass dust is washed with water, the belt filter grid is used. An object of the present invention is to provide a method and apparatus for washing calcium-containing dust with water, by which stable operation can be continued by preventing clogging of the like.

[0017]

In order to achieve the above object, the present invention provides a calcium-containing dust which is prepared by mixing calcium-containing dust with water to form a slurry, dissolving a water-soluble component in water, and then dehydrating the mixture. In the water washing method, gypsum dihydrate is suspended together with the dust.

According to the washing method of the present invention, by suspending gypsum dihydrate together with dust,
Gypsum dihydrate can be used as a seed crystal to deposit and grow calcium components around it, and by keeping the precipitated calcium components on the belt filter, it is possible to prevent scale deposits in subsequent processing systems and the like. . As a result, clogging of the grid of the belt filter can be minimized, and scale troubles in the mixing tank and the like can be eliminated. further,
The filterability of the desalted cake can be improved with the decrease in the adhesiveness of the calcium component.

The present invention is also a device for washing calcium-containing dust with water, which comprises a mixing tank for mixing calcium-containing dust with water to form a slurry, and dehydration while washing the calcium-containing dust and water slurry. And a supply device for supplying gypsum dihydrate to the mixing tank.

According to the rinsing device of the present invention, calcium-containing dust and water are mixed in the mixing tank to form a slurry, and dihydrate gypsum is supplied to the mixing tank by the supplying device to obtain dihydrate gypsum. As a seed crystal, a calcium component can be attached and grown around the seed crystal to obtain the effects described above.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Next, specific examples of embodiments of a method and apparatus for washing calcium-containing dust according to the present invention will be described with reference to the drawings.

FIG. 1 shows the calcium-containing dashes according to the present invention.
An example of a water washing device for a strike is shown, and this water washing treatment device 1
Is equipped with a mixing tank 2 and a belt filter 3, and water W₂,
W₃And dust D are mixed and stirred in the mixing tank 2 to form a slurry
After dissolving the water-soluble component, the slurry S is slurried.
-Supply the water to the belt filter 3 by the pump 4
₁Water with vacuum pumps 5 and 6 while washing with water
And desalinated cake C from which water-soluble chlorine compounds have been removed
obtain. Water-soluble chlorine sucked and removed by vacuum pumps 5 and 6
Water containing compound W₂And some water W₃Returned to mixing tank 22
And water W_FourIs purified. Belt used here
The filter 3 is the same as the belt filter 23 shown in FIG.
Since it has the same configuration, detailed description will be omitted.

The above-mentioned dust D is a dust containing calcium such as incineration fly ash and chlorine bypass dust. In the case of incineration fly ash, for example, the ratio of dust 1 to water 5 is equal to that of chlorine. In the case of the bypass dust, the dust is slurried at a ratio of 1 to the water 7, but such a dust D easily causes the clogging of the grid of the belt filter 3 as described above. The main purpose of the present invention is to continue stable operation of the washing processing apparatus 1 by minimizing clogging of the grid of the belt filter 3.

The present invention is characterized in that when the dust D is mixed with water W ₂ and W ₃ in the mixing tank 2 to produce the slurry S, gypsum dihydrate is suspended together with the dust D. Then, by using gypsum dihydrate as a seed crystal and adhering and growing a calcium component around the seed crystal, the clogging of the grid of the belt filter 3 in the subsequent stage is minimized and the scale trouble in the mixing tank 2 or the like is eliminated. be able to.

Here, there are various possible positions for supplying gypsum dihydrate in the washing treatment apparatus 1, but as shown in FIG. 1, a method for directly supplying gypsum dihydrate G ₁ to the mixing tank 2, a gypsum dihydrate. as G _2, a method of supplying to the mixing tank 2 fed to with water W ₃ on the discharge side of the vacuum pump 5, and a gypsum G _3, water W ₂ is supplied to the discharge side of the vacuum pump 6
There is also a method of supplying it to the mixing tank 2. In either method, the amount of gypsum dihydrate G added is 0.1% or more and 10% or less of the weight of the water stored in the mixing tank 2 in order to promote the attachment and growth of the calcium component to the seed crystal. It is preferable. In addition, for the same reason, the temperature of water is 20 ° C or higher, 6
It is preferably 0 ° C. or lower.

When the gypsum dihydrate is supplied to the mixing tank 2, it is preferable to forcefully mix the gypsum dihydrate and water, or to forcefully mix the water, gypsum dihydrate and dust. This makes it possible to further increase the precipitation amount of the calcium component, as will be described later.

In forcibly mixing the gypsum dihydrate and the water, as shown in FIG. 2, the gypsum dihydrate G and the water W are mixed by the mixing pump 7, and the hose pump 8 and the static mixer 9 are used. There is a method of supplying to the mixing tank 2.
Here, the static mixer 9 is 2 kg / cm ²
It is a device for forcibly mixing and stirring the gypsum dihydrate G and the water W supplied at a high pressure of a certain degree through a large number of projections implanted inside. The dust D is supplied to the mixing tank 2 by another transportation device (not shown).

Further, in forcibly mixing water, gypsum dihydrate and dust, as shown in FIG. 3, water W, gypsum dihydrate G and dust D are mixed in the stirring tank 10 and the hose pump 8 is used.
Alternatively, there is a method of supplying to the mixing tank 2 via the static type mixer 9.

In any of the above cases, water, dihydrate gypsum and dust are slowly added in the mixing tank 2 for 10 minutes or more and 2 hours or less in order to more effectively attach and grow the calcium content on the seed crystal. It is preferable to store while stirring, and it is optimal to store while performing slow stirring for 30 minutes or more and 1 hour or less.

In the above washing apparatus 1, when adding gypsum dihydrate to the mixing tank 2 or the like, it is difficult to add it little by little using, for example, an apron feeder, etc., so that the dust D is dissolved. It is preferable from the viewpoint of handling that gypsum dihydrate is dispersed in water different from the water to be added and then added as a slurry using a slurry pump.

Next, a test example of a method for washing calcium-containing dust with water according to the present invention will be described.

In washing the chlorine bypass dust with water, 0.5% or 1.0% of dihydrate gypsum is added to the water stored in the mixing tank 2 as a seed crystal in the mixing tank 2 of FIG. When a water washing test was performed using the belt filter shown in FIG. 5, the operation could be continued for about 3 months. This is a significant improvement as compared with the conventional case where the operation could not be continued due to the clogging of the grid of the belt filter in about 12 hours when the seed crystal was not used. Also in the mixing tank 2,
In the past, scales with high adhesiveness grew, whereas
When the seed crystals were added, only scales of less than 1 mm were attached, and the particles settled at the bottom of the mixing tank 2 were fine but had little adhesion.

Here, the weight increase of the grid of the belt filter was observed when the seed crystal was added to the mixture of chlorine bypass dust and incineration fly ash (25% by weight of chlorine bypass dust) and when no seed crystal was added. Table 1 shows a comparison.

[0034]

[Table 1]

As is clear from this table, the weight increase of the grid after operating for 3 days is about 1/4 in the case where the seed crystal is added, as compared with the case where the seed crystal is not added. As a result, it can be understood that the operation can be performed four times longer than before.

Further, the filterability of the desalted cake was improved along with the decrease in the adhesiveness due to the addition of the seed crystals. The filtration area of the belt filter is determined by the goodness of the water in the cake, the goodness of the air, etc., but as shown in Table 2, when the temperature of the mixing tank 2 is 55 ° C. and seed crystals are added. In addition, the filtration area could be reduced by about 25% as compared with the case where it was not added.

[0037]

[Table 2]

Next, a test example regarding forced mixing by the static mixer 9 will be described.

When the chlorine bypass dust and water are slurried, the case where the static type mixer 9 is forcibly mixed, the case where seed crystals are not added, and the case where the slurry is stirred and then filtered are used. Table 3 compares the weight of the permeated components. In the test, 50 ° C. water was used, the slurry was stirred for 30 minutes, and then filtered.

[0040]

[Table 3]

As is clear from the table, in the case where forced mixing was carried out by the static type mixer 9 and the case where seed crystals were added, as compared with the case where neither was carried out, the floating particles passing through the filter cloth were Since the amount of the substance is decreasing, it is presumed that the dissolved calcium adhered and grew on the seed crystal. Furthermore, when both forced mixing and seed crystal addition were performed, the amount of suspended particulate matter that passed through the filter cloth was 1/10 of that in the case where neither was performed.
The following is assumed, and it is estimated that a large amount of calcium adhered and grew on the seed crystal.

[0042]

As described above, according to the present invention,
When washing dust containing calcium such as incineration fly ash and chlorine bypass dust with water, it is possible to continue stable operation by preventing clogging of the grid of the belt filter.

[Brief description of drawings]

FIG. 1 is a flow chart showing an embodiment of a device for washing calcium-containing dust with water according to the present invention.

FIG. 2 is a flow chart showing an example of a forced mixing device used in the water washing processing device of FIG.

FIG. 3 is a flowchart showing another example of the forced mixing device used in the water washing processing device of FIG.

FIG. 4 is a flow chart showing an example of a conventional water washing treatment apparatus for desalting dust such as incinerated fly ash and chlorine bypass dust.

FIG. 5 is a schematic configuration diagram showing an example of a belt filter used in a conventional water washing apparatus.

FIG. 6 is a schematic view showing an example of a grid of a conventional belt filter, (a) is a front view, (b) is a plan view,
(C) is a side view.

[Explanation of symbols]

1 Water washing equipment 2 mixing tanks 3 Belt filter 4 Slurry pump 5 vacuum pump 6 vacuum pump 7 mixing pump 8 hose pump 9 Static type mixer 10 stirring tank

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tomomi Nakamura             5378 Mikajiri, Kumagaya, Saitama Prefecture Pacific sem             Technology Development Center, Equipment Engineering Department             Within (72) Inventor Soichiro Okamura             5378 Mikajiri, Kumagaya, Saitama Prefecture Pacific sem             Technology Development Center, Equipment Engineering Department             Within F-term (reference) 4D004 AA36 AB06 CA13 CA15 CA40                       CB50 CC03 CC11 DA03 DA06                       DA11                 4D026 BA03 BC12 BE05 BF04 BF19

Claims (9)

[Claims] 1. A method of rinsing calcium-containing dust in which calcium-containing dust is mixed with water to form a slurry to dissolve a water-soluble component in water and then dehydrated, in which gypsum dihydrate is suspended together with the dust. A method for washing calcium-containing dust with water. 2. The water and the gypsum dihydrate are forcibly mixed,
The slurry containing the calcium-containing dust is slurried in a mixed solution of the water and the gypsum dihydrate, the water-soluble component in the calcium-containing dust is dissolved in the water, and then dehydrated. The method for washing calcium-containing dust with water according to item 1. 3. The water, the gypsum dihydrate and the dust containing calcium are forcibly mixed, the water-soluble component in the dust containing calcium is dissolved in water, and then dehydrated. The method for washing calcium-containing dust with water according to item 1. 4. The method for washing calcium-containing dust with water according to claim 1, wherein the temperature of the water is 20 ° C. or higher and 60 ° C. or lower. 5. The water, the gypsum dihydrate and the dust containing calcium are stored for 10 minutes or more and 2 hours or less while being slowly stirred, and then dehydrated. 4. The method for washing calcium-containing dust with water according to any one of 4 above. 6. The addition amount of the gypsum dihydrate is 0.1% or more and 10% or less of the weight of water mixed with the dust when the calcium-containing dust is slurried. Item 6. A method for washing calcium-containing dust with water according to any one of Items 1 to 5. 7. The dust is incinerated fly ash and / or chlorine bypass dust.
The method for washing calcium-containing dust with water according to any one of 1. 8. A mixing tank for mixing calcium-containing dust with water to form a slurry, a belt filter for dehydrating the calcium-containing dust and water slurry while washing with water, and gypsum dihydrate supplied to the mixing tank. And a water supply device for the calcium-containing dust. 9. The apparatus for washing calcium-containing dust according to claim 8, wherein the supply device includes a slurry pump for supplying a slurry of gypsum dihydrate and water.