JP7237133B1 - Method for desalting chlorine-containing powder - Google Patents

Abstract

A method for desalting chlorine-containing powder is provided, which can effectively reduce the amount of water used in the entire system.
[Solution]
The slurrying step, the chlorine elution step, the desalted cake forming step, the first desalted cake washing step, and the second desalted cake washing step are repeated for each supplied chlorine-containing powder, and the second At least a part of the third filtrate obtained in the desalted cake washing step is collected and stored, and a second filtrate for the first desalted cake washing step corresponding to the chlorine-containing powder to be supplied to the subsequent stage. Recycled as a desalting wash, a third desalting wash for the second desalted cake washing step, or both, and after one or more reuses, for the slurrying step is a method for desalting chlorine-containing powder, wherein the chlorine-containing powder is circulated for use as the first desalting washing liquid.
[Selection figure] None

Description

TECHNICAL FIELD The present invention relates to a desalting method for reducing chlorine content from chlorine-containing powder such as incineration ash.

Incineration ash generated when municipal waste such as general waste and industrial waste is incinerated and clinker dust generated from cement factories are effectively reused as raw materials for cement from the viewpoint of resource and environmental protection. there is However, these powders contain a large amount of chlorine, and the chlorine interferes with the quality of cement and the normal operation of cement manufacturing equipment. At that time, a large amount of washing water is required for washing, and reduction of the amount used has been a problem.

In relation to such problems, for example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-211129) discloses a mixing device for mixing ash and water and a solid for separating the mixture from the mixing device into ash and water. The ash is washed in a plurality of stages, and the ash and water flow countercurrently. A process for washing ash is disclosed which is characterized by dehydrating the ash to a wet ash moisture content of less than 60%. And it is supposed that desalination from ash can be efficiently performed with a small amount of washing water (paragraph 0021 of Patent Document 1).

Further, for example, in Patent Document 2 (Japanese Patent Application Laid-Open No. 2005-246295), a plurality of stages of drum filters for cleaning the incineration ash are provided, fresh cleaning water is supplied to the final stage, and the collected and washed water is sucked and recovered at each stage. In an incineration ash treatment apparatus that uses water as washing water in the preceding stage to wash incineration ash sent from the first stage to the final stage, the drum filters in each stage are sucked and collected by the drum filter. A recovered cleaning water supply means for supplying part of the recovered cleaning water to the mixture held on the outer periphery of the filter at a position on the upstream side in the drum rotation direction with respect to the cleaning water supply position of the stage. Disclosed is an incinerated ash processing apparatus characterized by: In addition, when obtaining the same cleaning effect as the conventional one, the number of drum filter stages can be reduced, and the amount of water used can be reduced (Patent Document 2, paragraph 0014).

Japanese Patent Application Laid-Open No. 2003-211129 JP 2005-246295 A

In the above Patent Documents 1 and 2, when chlorine-containing powder such as incineration ash is desalted, the powder is washed with water to dissolve chlorine into the liquid phase and then dehydrated. In order to efficiently remove residual chlorine in water, it is possible to reduce the amount of water used by providing multiple stages of cleaning equipment for removing the residual chlorine.

However, according to the findings of the present inventors, if the desalted cake is washed by providing a washing device in multiple stages as in Patent Documents 1 and 2, the residual dust attached to the filter cloth and the device itself is washed. However, there is a problem that the amount of water used in the entire system cannot be suppressed because the amount of water used increases.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a desalting method for chlorine-containing powder that can effectively reduce the amount of water used in the entire system.

In order to achieve the above object, the present invention firstly
a slurrying step of mixing the chlorine-containing powder with the first desalting washing liquid to form a slurry;
a chlorine elution step of eluting chlorine contained in the chlorine-containing powder in the slurry into a liquid phase;
a desalted cake forming step of obtaining a first desalted cake and a first filtrate by dehydrating the slurry in which the chlorine has been eluted;
A first desalted cake washing step for obtaining a second desalted cake and a second filtrate by washing the first desalted cake with a second desalted washing liquid separate from the first desalted washing liquid. and,
The second desalted cake is washed with a third desalted washing liquid separate from the first desalted washing liquid and the second desalted washing liquid to obtain a third desalted cake and a third filtrate. a second desalted cake washing step to obtain,
The slurrying step, the chlorine elution step, the desalted cake forming step, the first desalted cake washing step, and the second desalted cake washing step are performed for each supplied chlorine-containing powder. At least part of the third filtrate obtained in the second desalted cake washing step is repeatedly collected and stored, and the first desalted cake washing corresponding to the chlorine-containing powder supplied to the subsequent stage is performed. reused as said second desalting wash for the step, said third desalting wash for said second desalted cake washing step, or both, and reused one or more times The present invention provides a method for desalting chlorine-containing powder, characterized in that the washing liquid for desalting is recycled as the first washing solution for desalting.

According to the method for desalting the chlorine-containing powder described above, the chlorine-containing powder is mixed with the first desalting washing liquid to form a slurry, and the chlorine contained in the chlorine-containing powder is eluted into the liquid phase of the slurry. After dehydrating the slurry, a first desalted cake and a first filtrate are obtained, and the first desalted cake is washed with a second desalting washing liquid separate from the first desalting washing liquid. to obtain a second desalted cake and a second filtrate, and the second desalted cake is subjected to a third desalting washing separate from the first desalting washing and the second desalting washing. Since the third desalted cake and the third filtrate are obtained by washing with the liquid, the third desalted cake from which chlorine is sufficiently removed can be obtained. Therefore, it is useful for converting chlorine-containing incineration ash and the like into a raw material for cement. At least part of the third filtrate obtained in the second desalted cake washing step is collected and stored. It can be reused as a washing liquid for desalination corresponding to the chlorine-containing powder supplied to the subsequent stage. After being reused one or more times, it is recycled as the first desalting washing solution. The amount used can be reduced. Also, by reducing the amount of water used, the elution amount of heavy metals can be suppressed.

In order to achieve the above object, secondly, the present invention provides the desalting method for chlorine-containing powder, wherein the desalting cake forming step, the first desalting cake washing step, and the second desalting step are performed. The cake washing step is performed by a solid-liquid separator using a filter cloth, and at least part of the filter cloth washing wastewater obtained when the filter cloth is washed is used as the second desalting washing liquid, the third To provide the desalting method in which the desalting washing liquid is recycled or both.

According to the above configuration, since a solid-liquid separation device using a filter cloth is used, it is possible to efficiently form a desalted cake from the slurry and wash the chlorine-containing powder supplied in a large amount. . In addition, in order to prevent clogging of the filter cloth of the solid-liquid separation device to be used, it is necessary to constantly wash the device during the operation period. Since the water is recycled as a washing liquid or both, it is possible to further reduce the amount of water used in the entire system.

In order to achieve the above objects, the present invention thirdly provides the desalting method for chlorine-containing powder having the second configuration, wherein the solid-liquid separation device is a filter press or a belt filter. It provides a method.

According to said structure, the existing apparatus system can be utilized as a solid-liquid separator.

In order to achieve the above object, fourthly, in the method for desalting chlorine-containing powder having the second configuration, the solid-liquid separator is a filter press, and at least A desalination treatment method is provided in which a part is solid-liquid separated and the liquid part is recycled as the second desalting washing liquid, the third desalting washing liquid, or both. .

According to said structure, the existing apparatus system can be utilized as a solid-liquid separation apparatus using a filter cloth. A filter press is a device capable of washing a cake, but a general cake washing mechanism is one in which water is passed through the filter cloth from the side opposite to the filtration surface. Therefore, direct use of the filter cloth washing wastewater containing solids as cake washing water (use for the second and third desalting washing solutions) causes clogging of the filter cloth. By solid-liquid separation, it can be suitably used as the second and third desalting washings.

In order to achieve the above objects, the present invention fifthly provides, in the desalting treatment method for chlorine-containing powder, the desalted cake forming step, the first desalted cake washing step, and the second desalted cake. The cake washing step is performed by a solid-liquid separator using a filter cloth, and at least part of the filter cloth washing wastewater obtained when the filter cloth is washed is circulated and used as the first desalting washing liquid. The present invention provides the desalting method.

According to the above configuration, since a solid-liquid separation device using a filter cloth is used, it is possible to efficiently form a desalted cake from the slurry and wash the chlorine-containing powder supplied in a large amount. . In addition, in order to prevent clogging of the filter cloth of the solid-liquid separator to be used, it is necessary to constantly wash it during the operation period of the equipment. As a result, the water usage of the entire system can be further reduced.

In order to achieve the above object, sixthly, the present invention provides a method for desalting chlorine-containing powder,
When reusing the third filtrate obtained in the second desalted cake washing step, whether or not to reuse the third filtrate is checked in a storage tank in which at least part of the third filtrate is collected and stored, The present invention provides the desalting method, which is determined by observing any one or more of the following (1) to (5).
(1) total amount of time reused with the third filtrate (2) amount of water reused with the third filtrate (3) pH of the third filtrate
(4) Chlorine ion concentration of the third filtrate (5) Electrical conductivity of the third filtrate

According to the above configuration, when reusing the third filtrate, it is possible to avoid using a washing liquid inappropriate for washing the desalted cake.

To achieve the above object, seventhly, in the method for desalting chlorine-containing powder, the second filtrate obtained in the first desalting cake washing step is at least partly It is recovered and stored, and reused as the second desalting washing solution for the first desalting cake washing step corresponding to the chlorine-containing powder to be supplied later, and is used once or multiple times. The object is to provide the desalting treatment method in which the desalting solution is recycled as the first desalting washing solution after being reused.

According to the above configuration, by reusing the second filtrate obtained in the first desalted cake washing step, it is possible to reliably reduce the amount of water used in the entire system. In addition, since at least part of the second filtrate is recovered and stored, the chlorine-containing powder supplied to the subsequent stage can be treated without the need to provide multiple stages of equipment for washing the desalted cake. It can be reused as a corresponding desalting wash.

In order to achieve the above object, eighthly, the present invention provides a method for desalting chlorine-containing powder,
When reusing the second filtrate obtained in the first desalted cake washing step, whether or not to reuse the second filtrate is checked in a storage tank in which at least part of the second filtrate is collected and stored, The method for desalting chlorine-containing powder according to claim 7, wherein the determination is made by observing any one or more of the following (1) to (5).
(1) Total amount of time reused with the second filtrate (2) Total amount of water reused with the second filtrate (3) pH of the second filtrate
(4) Chlorine ion concentration of the second filtrate (5) Electrical conductivity of the second filtrate

According to the above configuration, when reusing the second filtrate, it is possible to avoid using a washing liquid inappropriate for washing the desalted cake.

In order to achieve the above object, the present invention provides a ninth aspect of the method for desalting chlorine-containing powder,
washing the first desalted cake with the second desalting washing liquid in the first desalting cake washing step a plurality of times with the second desalting washing liquid; and/or
The desalination treatment method is provided, wherein in the second desalted cake washing step, the second desalted cake is washed with the third desalting washing liquid a plurality of times with the third desalting washing liquid. It is.

According to the above configuration, it is possible to reliably perform the desalting treatment by washing the cake a plurality of times.

In order to achieve the above object, tenthly, the present invention provides a method for desalting chlorine-containing powder,
The desalination method is provided, wherein the amount of water used is 1.5 parts by mass to 4 parts by mass per 1 part by mass of the dry weight of the chlorine-containing powder to be desalted.

According to the above configuration, it is possible to greatly reduce the amount of water used in the desalting treatment of chlorine-containing powder such as incineration ash. Also, by reducing the amount of water used, the amount of elution of heavy metals can be suppressed.

In order to achieve the above objects, the present invention provides an eleventh aspect of the method for desalting chlorine-containing powder,
To provide a desalting treatment method in which the desalted cake forming step, the first desalted cake washing step, and the second desalted cake washing step are performed in one solid-liquid separation device. is.

According to the above configuration, the configuration of the apparatus can be simplified, thereby reducing initial costs and running costs. In addition, it is possible to minimize the use of water for washing residual dust adhering to the filter cloth and the device itself.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a flow chart showing one embodiment of the method for desalting chlorine-containing powder according to the present invention. FIG. 2A is a flow diagram illustrating an aspect in which washing in a desalting cake washing step is performed multiple times with a desalting washing liquid in an example of the method for desalting chlorine-containing powder according to the present invention; FIG. , washing the second desalted cake with the third desalting washing liquid a plurality of times with the third desalting washing liquid, and FIG. A mode in which washing with the washing liquid is performed a plurality of times with the second desalting washing liquid is shown, and FIG. It shows an aspect in which both washing is performed twice. In another example of the method for desalting chlorine-containing powder according to the present invention, a desalted cake forming step, a first desalted cake washing step, and a second desalted cake washing step are combined into one solid-liquid separation apparatus. FIG. 10 is a flow diagram for explaining a mode in which . In another example of the method for desalting chlorine-containing powder according to the present invention, a desalted cake forming step, a first desalted cake washing step, and a second desalted cake washing step are combined into one solid-liquid separation apparatus. and a solid-liquid separation device using a filter cloth is used as the solid-liquid separation device. FIG. 2 is a flow diagram illustrating aspects of Comparative Examples 1 to 7 performed in Test Example 1; FIG. 2 is a flow diagram illustrating aspects of Examples 1 to 5 carried out in Test Example 1; FIG. 10 is a flow diagram illustrating a mode of Example 6 performed in Test Example 1; 2 is a chart showing the relationship between the fresh water ratio and the chlorine concentration of desalted cake after washing, obtained as a result of Test Example 1. FIG. 9A is a graph showing the relationship between the chlorine concentration and the Pb concentration in the waste water component (FIG. 9A) and the relationship between the chlorine concentration and the Zn concentration in the waste water component (FIG. 9B) obtained as a result of Test Example 1. FIG. A chart showing the relationship between the chlorine concentration of the desalted cake and the Pb concentration in the wastewater component (FIG. 10A) and the relationship between the Zn concentration in the chlorine concentration of the desalted cake and the wastewater component (FIG. 10B) obtained as a result of Test Example 1. be. Regarding the value obtained by dividing the chlorine concentration of the desalted cake by the new water ratio obtained as the result of Test Example 1, the difference obtained by subtracting the value of the example from the value of the comparative example at the same new water ratio, and the corresponding It is a chart which shows a relationship with a new water ratio.

The object of the method for desalting chlorine-containing powder according to the present invention is not particularly limited as long as it is a powder containing chlorine. Examples include incinerated fly ash, molten fly ash, and chlorine bypass dust. Conventionally, these wastes have been effectively used as raw materials for cement after desalting. Incineration fly ash”) generally contains chlorine (Cl) at a concentration of about 10% by mass to 30% by mass, and the fly ash generated from the gasification melting furnace (“molten fly ash”) generally contains chlorine at a concentration of about 10% by mass to 40% by mass. On the other hand, chlorine bypass dust, which is dust contained in the cement kiln bleed gas, generally contains chlorine at a concentration of about 10% by mass to 40% by mass.

According to the method for desalting chlorine-containing powder according to the present invention, the concentration of chlorine in the chlorine-containing powder as described above is reduced to about 3% by mass or less, more typically to about 2% by mass or less. , which can be effectively used as a raw material for cement, for example. The concentration of chlorine in the chlorine-containing powder can be measured by a well-known method, for example, potentiometric titration method and ion chromatography method applying JIS A 1154 "Method for testing chloride ions contained in hardened concrete" mutatis mutandis. and the fundamental parameter method by fluorescent X-ray analysis are preferably exemplified.

Hereinafter, the present invention will be described more specifically with reference to the drawings.

FIG. 1 shows a flow chart representing one embodiment of the method for desalting chlorine-containing powder according to the present invention.

As shown in this embodiment, the method for desalinating chlorine-containing powder according to the present invention comprises a slurrying step of mixing chlorine-containing powder with a first desalting washing liquid to form a slurry; a chlorine elution step of eluting chlorine contained in the chlorine-containing powder into the liquid phase; and a desalted cake forming step of obtaining a first desalted cake and a first filtrate by dehydrating the slurry in which the chlorine has been eluted. and washing the obtained first desalted cake with a second desalting washing liquid separate from the first desalting washing liquid to obtain a second desalted cake and a second filtrate. washing step, and washing the obtained second desalted cake with a third desalting washing liquid separate from the first desalting washing liquid and the second desalting washing liquid to obtain a third desalted cake; and a second desalted cake washing step for obtaining a third filtrate.

In order to mix the chlorine-containing powder with the first desalting washing liquid to form a slurry, or to elute the chlorine contained in the chlorine-containing powder in the slurry into the liquid phase, a predetermined It is possible to carry out by using a dissolution tank or the like. Further, in order to dewater the slurry or wash the desalted cake formed by dehydration by adding a desalting washing liquid, it is possible to use a predetermined mixing tank, a dehydrator, etc. well known to those skilled in the art. is. In addition, slurry or liquid can be transferred using a fluid supply device/supply tank, a fluid supply pipe, a predetermined storage tank, or the like, which are well known to those skilled in the art.

Then, the slurrying step, the chlorine elution step, the desalted cake forming step, the first desalted cake washing step, and the second desalted cake washing step are repeated for each supplied chlorine-containing powder. (In FIG. 1, the first stage, the second stage, and the third stage are repeated.) At that time, at least part of the third filtrate obtained in the second desalted cake washing step is recovered. The demineralized water is stored at the bottom and reused as a washing liquid for desalination corresponding to the chlorine-containing powder to be supplied to the subsequent stage. More specifically, it is reused as the second desalting washing liquid for the first desalted cake washing step, the third desalting washing liquid for the second desalted cake washing step, or both. ing. Further, after the third filtrate is reused once or several times, it is recycled as the first desalting washing liquid.

Here, the "chlorine-containing powder supplied later" means that it is different from the chlorine-containing powder that was present in the same step earlier than that in terms of time. Therefore, for example, in the embodiment shown in FIG. 1, the desalting treatment is repeated in chronological order in the first, second, and third stages, and the third filtrate from the first stage is the second stage. This is reused as the second desalting washing liquid, the third desalting washing liquid, or both, corresponding to the chlorine-containing powder supplied to the third stage or later. You may make it

In addition, the desalted cake washing step for further washing the formed desalted cake is divided into first and second steps in the order of the processing time of the desalted cake. Thus, for example, a third desalted cake washing step, a fourth desalted cake washing step, a fifth desalted cake washing step, subsequent desalted cake washing steps, etc., and further multistage desalted cake washing steps are provided. good too. In this case, the filtrate from the desalted cake washing process with an arbitrary number is the same number or the number before it in the chlorine-containing powder supplied to the subsequent stage, with the numbers assigned in order of process time. is preferably reused in the desalted cake washing step.

In the embodiment shown in FIG. 1, at least part of the second filtrate obtained in the first desalted cake washing step is also collected and stored, and The second desalting washing liquid for the first desalting cake washing step is reused. In addition, after the second filtrate is reused once or multiple times, it is recycled as the first desalting washing liquid.

Here, the "chlorine-containing powder to be supplied later" means, as described above, different from the chlorine-containing powder that was present in the same step earlier in terms of time. Therefore, for example, in the embodiment shown in FIG. 1, the second filtrate from the first stage is reused in the second stage. may be reused as the second desalting washing solution corresponding to the above. The desalted cake washing step may be further provided in multiple stages such as a third desalted cake washing step. becomes the first desalting cake washing process, and the desalting washing liquid used in the washing process becomes the second desalting washing liquid.

In addition, in the method for desalting chlorine-containing powder according to the present invention, the recycling of the above-described second filtrate is not an essential configuration. Further, in the embodiment shown in FIG. 1, the first filtrate obtained in the desalted cake forming step is treated as waste water. It is also possible to reuse as the first desalting washing solution corresponding to .

In the embodiment shown in FIG. 1, fresh water is used as the desalting washing liquid used in the desalting treatment of the chlorine-containing powder in the first stage, but this is newly supplied to the system. means water. The new water may be water other than seawater such as industrial water (fresh water), or chlorine-containing water whose chloride ion concentration is adjusted by optionally adding a chloride ion concentration adjuster such as NaCl or KCl as necessary. Water may be used, but in areas where a large amount of industrial water (fresh water) cannot be used, or where the use of industrial water (fresh water) is restricted due to cost, etc., seawater should be used as industrial water (fresh water). ) is convenient to use.

In addition, the chloride ion concentration of the desalting cleaning solution introduced into the system may increase as it is reused. It is preferable to keep it within the range. In the case of the second desalting washing liquid, it is preferable to keep the content within the range of 0.5% by mass to 6% by mass. Further, in the case of the third desalting washing liquid, it is preferable to keep the content within the range of 0% by mass to 2% by mass.

FIG. 2 shows an embodiment in which the desalted cake is washed with a desalting washing liquid a plurality of times in one example of the method for desalting chlorine-containing powder according to the present invention. That is, in the desalting method according to the present invention, for example, as shown in FIG. 2A, the second desalted cake is washed with the third desalting washing liquid a plurality of times. You can do it. Further, as shown in FIG. 2B, the washing of the first desalted cake with the second desalting washing liquid may be performed multiple times with the second desalting washing liquid. Further, as shown in FIG. 2C, washing with the second desalting washing liquid may be performed multiple times, and washing with the third desalting washing liquid may be performed multiple times. After an arbitrary number of uses, it may be treated as waste water, or it may be reused for the chlorine-containing powder to be supplied later.

In FIG. 3, in the method for desalting chlorine-containing powder according to the present invention, a desalted cake forming step, a first desalted cake washing step, and a second desalted cake washing step are shown in one step of solid-liquid separation. Apparatus adapted to perform on the device are shown. Specifically, the solid-liquid separation device may be, for example, a filter press, a belt filter, or the like. That is, in the example shown in FIG. 3, the slurry that has undergone the chlorine elution step is introduced into the solid-liquid separator 1 and dehydrated according to the normal specifications of the apparatus to obtain the first filtrate. In addition, a second desalting washing liquid is introduced into the cake after dehydration held in the device, and the cake is washed according to the normal washing specifications of the device to obtain a second filtrate. Furthermore, the cake after washing with the second desalting washing liquid held in the apparatus is introduced with the third desalting washing liquid and washed according to the normal washing specifications of the apparatus to obtain the third filtrate. I am trying to get Then, the second filtrate and the third filtrate are stored in the storage tank 2 and the storage tank 3, respectively, and are supplied at a desired timing as a washing liquid for the chlorine-containing powder supplied to the subsequent stage. It is possible.

In the example shown in FIG. 3, the storage tank 2 and the storage tank 3 are provided with a measuring device 4 and a measuring device 5, respectively, so that the property of the liquid in the tank can be observed. Observation is not limited, but may be, for example, the following (1) to (5).
(1) Total time of reuse treatment with the second or third filtrate: Measure the operating time of the reused pump with a timer (2) Reuse with the second or third filtrate Total amount of treated water: Measure the amount of water with a flow meter (3) pH of the second or third filtrate: Measure the pH of the liquid in the tank with a pH meter (4) The second or third filtrate Chlorine ion concentration of filtrate: Measure the chloride ion concentration of the liquid in the tank by ion chromatography and potentiometric titration (5) Electrical conductivity of the second or third filtrate: Conductivity meter to measure the electrical conductivity of liquids in

Then, for example, as a guideline for the chloride ion concentration in (4) above, in the case of the second filtrate, 0.5 It is preferable to keep the content within the range of 6% by mass to 6% by mass. Moreover, in the case of the third filtrate, it is preferable to keep the concentration within the range of 0% by mass to 2% by mass.

On the other hand, in the case of the second filtrate, for example, it is preferable to limit the total time in (1) to a range of 0 to 10 minutes. Moreover, in the case of the third filtrate, it is preferable to keep the time within the range of 0 to 20 minutes.

Further, for example, as a guideline for the total amount of water in (2) above, the amount of water used is 0 mass in the case of the second filtrate with respect to 1 part by mass of the dry weight of the chlorine-containing powder to be desalted. parts to 3.5 parts by mass. Further, in the case of the third filtrate, it is preferable to keep the amount in the range of 0 to 3.5 parts by mass.

Further, for example, as a guideline for the pH in (3) above, it is preferable to keep the pH within the range of pH 7 to pH 13 in the case of the second filtrate. In the case of the third filtrate, it is preferable to keep the pH within the range of 7 to 12.5.

Further, for example, as a guideline for the electrical conductivity of (5) above, it is preferable to keep it within the range of 3 S/m to 30 S/m in the case of the second filtrate. Further, in the case of the third filtrate, it is preferable to keep it within the range of 0 S/m to 10 S/m.

FIG. 4 shows another example of the method for desalting chlorine-containing powder according to the present invention. That is, in the desalting treatment method according to the present invention, for example, as illustrated in FIG. The desalted cake washing step may be performed by one solid-liquid separator, and a solid-liquid separator using a filter cloth may be used at that time. Specifically, the solid-liquid separation device 1 can be, for example, a filter press, a belt filter, or the like. In order to prevent clogging of the filter cloth, a solid-liquid separation device using a filter cloth usually requires constant cleaning throughout the operating period of the device. It is stored in a tank 6 so that it can be supplied at a desired timing as a washing liquid for chlorine-containing powder. In this case, since the filter cloth washing wastewater contains insoluble matter washed away from the used filter cloth, it is treated by the solid-liquid separator 7, and the liquid portion is used as washing liquid for the chlorine-containing powder. You may make use of it. In particular, in the case of a filter press, direct use of the filter cloth washing wastewater containing solids as cake washing water (use for the second and third desalting washings) may cause clogging of the filter cloth. By solid-liquid separation, it can be suitably used as the second and third desalting washing liquids or filter cloth washing washing liquids. The solid-liquid separation device 7 can be, for example, a filter press, belt filter, belt press, vacuum drum filter, sedimentation tank, or the like.

In the method for desalting chlorine-containing powder according to the present invention, although not limited, the amount of water used is 1.5 parts by mass to 4 parts by mass with respect to 1 part by mass of the dry weight of the chlorine-containing powder to be desalted. part by mass. Here, as the "amount of water used", the preferable range of the amount of water is calculated by dividing the amount of water newly supplied to the entire system by the dry weight of the chlorine-containing powder supplied to the system per hour. can. In addition, the division of water usage in each process, including recycled water, is about 1.5 parts by mass to 7.0 parts by mass for the slurrying process, and about 1.5 parts by mass to 7.0 parts by mass for the first desalted cake washing process. about 0.5 to 5.0 parts by weight for the second desalted cake washing step, and about 0.5 to 5.0 parts by weight for the second desalted cake washing step. In addition, it is about 0.1 to 2 parts by mass for the filter cloth washing step as necessary.

The present invention is not limited to the above-described embodiments, and various combinations and modifications within the scope disclosed herein are possible, and such embodiments are also within the technical scope of the present invention. It is included.

Hereinafter, the present invention will be described more specifically with reference to test examples. However, the scope of the present invention is not limited by these test examples.

<Test Example 1>
Chlorine bypass dust (chlorine concentration by fluorescent X-ray analysis fundamental parameter method: 20.94%) discharged from a cement factory is slurried, chlorine eluted, desalted cake formation, In addition, the desalted cake was washed, and the effect of recycling the wastewater from the desalted cake washing was investigated. A beaker, propeller stirrer, and Buchner funnel were used for the test. Specifically, a predetermined amount of water and a predetermined amount of dust were mixed in a beaker to form a slurry. A Buchner funnel equipped with a filter paper (quantitative filter paper No. 5c) and a filtrate receiving bottle is used for the slurry, and the slurry placed on the filter paper is dehydrated by decompressing and sucking the inside of the bottle with a vacuum pump. The desalted cake was washed by spraying the washing liquid for washing the desalted cake on the filter paper of the Buchner funnel while the desalted cake was placed on the filter paper of the Buchner funnel. After that, the desalted cake is separated from the filter paper, and after obtaining the desalted cake, the filter paper is again attached to the Buchner funnel, and while the inside of the bottle is decompressed with a vacuum pump, the washing liquid is sprayed on the filter paper to wash the filter paper. , solid-liquid separation was performed at the same time.

More specifically, as shown in FIG. 5, in Comparative Examples 1 to 7, 1.5 to 1.5 parts of fresh water is added to 1 part by mass of the dry weight of the chlorine bypass dust to be subjected to the first stage treatment. Add 5.0 parts by mass to make a slurry (hereinafter, this water ratio is abbreviated as "1.5 equivalents" with respect to the dry weight of the chlorine bypass dust), and add 3.5 equivalents to the desalted cake after dehydration. , 3 equivalents, 2.5 equivalents, 2 equivalents, 1.25 equivalents, or 1 equivalent of fresh water was added to wash. Separately, 1.5 equivalents of fresh water was used for washing the filter paper, and 3 A combination of 0.5, 3, 2, 1.25, or 1 equivalent and 1.5 equivalent of the solids-free filter paper wash effluent discharged from the first stage was used. In Comparative Example 7, the desalted cake was not washed.

Further, as shown in FIG. 6, in Examples 1 to 5, 1.5 to 5.0 equivalents of fresh water was added to the chlorine bypass dust subjected to the first stage treatment to make slurry, and after dehydration, the dust was slurried. 3.5 equivalents, 2.5 equivalents, 1.5 equivalents, 1.25 equivalents, or 1 equivalent of fresh water is added to the desalted cake to wash the desalted cake (first desalted cake washing), Further, washing of the desalted cake was repeated with the same equivalent amount of fresh water (second desalted cake washing). As in Comparative Examples 1 to 7, 1.5 equivalents of fresh water was used to wash the filter paper, and the chlorine bypass dust discharged from the first stage was slurried for the second stage treatment. Use 3.5 equivalents, 2.5 equivalents, 1.5 equivalents, 1.25 equivalents, or 1 equivalent of the second filtrate and 1.5 equivalents of filter paper washing wastewater discharged from the first stage. board. However, in Examples 1-5, 3.5 equivalents, 2.5 equivalents, 1.5 equivalents, 1.25 equivalents, or 1 An equivalent amount was used to wash the first desalted cake in the second desalting treatment.

On the other hand, as shown in FIG. 7, in Example 6, slurrying, first desalted cake washing, second desalted cake washing, and filter paper washing were all performed with 1.5 equivalents of water, provided that , the second filtrate discharged from washing the first desalted cake in the first stage is used for slurrying the chlorine bypass dust to be subjected to the second stage treatment, and the first desalted cake is washed with the second The third filtrate discharged from washing the second desalted cake at the first stage was used, and the filter paper washing wastewater discharged from the first stage was used for washing the second desalted cake.

Chlorine concentration was measured by the fluorescent X-ray analysis fundamental parameter method for the washed material after the treatment. In addition, ICP analysis (Pb, Zn) and ion chromatography analysis (Cl) of the first filtrate discharged during the formation of the desalted cake were performed on the waste water.

Table 2 summarizes the total amount of fresh water used for treating the chlorine bypass dust per stage, the chlorine concentration of the washed material, and the results of component analysis of the waste water.

As a result, the following facts were clarified.

As shown in FIG. 8, the chlorine concentration in the dehydrated cake after washing increased as the ratio of fresh water decreased in both Comparative Example and Example. However, by circulating the washing water as in the example, it was possible to reduce the fresh water ratio (wastewater treatment amount) with the same dehydrated cake chlorine concentration as the comparative example. For example, in Comparative Example 3, the total amount of fresh water used to treat chlorine bypass dust per stage was 4 equivalents, and the chlorine concentration at this time was 0.59%-dry, In Example 1, to obtain a chlorine concentration of 0.57%-dry, which is the same as in Comparative Example 3, 3 equivalents was sufficient as the total amount of fresh water.

On the other hand, the Pb and Zn components in the wastewater are reduced in both Comparative Example and Example due to the increase in Cl concentration in the wastewater due to the decrease in the ratio of fresh water (Fig. 9). Furthermore, by circulating the washing water as in the example, it is possible to lower the chlorine concentration of the dehydrated cake (while maintaining the desalination performance) and reduce the Pb and Zn concentrations in the waste water (Fig. 10). ). Therefore, it can be seen that it is possible to reduce the cost of waste water treatment chemicals required for treating Pb and Zn.

FIG. 11 shows the value obtained by dividing the chlorine concentration of the dehydrated cake by the fresh water ratio, that is, the difference obtained by subtracting the value of the example from the value of the comparative example at the same fresh water ratio for the residual chlorine concentration per unit amount of water. It was calculated and made into a relational diagram with the corresponding new water ratio.

As a result, as shown in FIG. 11, the effect of the desalination treatment by circulating the washing water in the example is more pronounced when the new water ratio is smaller than in the comparative example when the new water ratio is the same. It was.

From the above, it can be seen that by recycling the wash water, it is possible to reduce the amount of water required for the entire system to achieve the purpose of the desalting treatment.

DESCRIPTION OF SYMBOLS 1...Solid-liquid separator (for dehydration of slurry or cake), 2, 3, 6... Reservoir, 4, 5... Measuring device, 7... Solid-liquid separator (for removing washing residue of filter cloth)

Claims (13)

a slurrying step of mixing the chlorine-containing powder with the first desalting washing liquid to form a slurry;
a chlorine elution step of eluting chlorine contained in the chlorine-containing powder in the slurry into a liquid phase;
a desalted cake forming step of obtaining a first desalted cake and a first filtrate by dehydrating the slurry in which the chlorine has been eluted;
A first desalted cake washing step for obtaining a second desalted cake and a second filtrate by washing the first desalted cake with a second desalted washing liquid separate from the first desalted washing liquid. and,
The second desalted cake is washed with a third desalted washing liquid separate from the first desalted washing liquid and the second desalted washing liquid to obtain a third desalted cake and a third filtrate. a second desalted cake washing step to obtain,
The slurrying step, the chlorine elution step, the desalted cake forming step, the first desalted cake washing step, and the second desalted cake washing step are performed for each supplied chlorine-containing powder. At least part of the third filtrate obtained in the second desalted cake washing step is repeatedly collected and stored, and the first desalted cake washing corresponding to the chlorine-containing powder supplied to the subsequent stage is performed. reused as said second desalting wash for the step, said third desalting wash for said second desalted cake washing step, or both, and reused one or more times Later, while circulating as the first desalting washing liquid,
The desalted cake forming step, the first desalted cake washing step, and the second desalted cake washing step are performed by a solid-liquid separator using a filter cloth, and the filter cloth is washed. desalination of chlorine-containing powder, characterized in that at least a part of the filter cloth washing wastewater is circulated as the second desalting washing liquid, the third desalting washing liquid, or both. Processing method. 2. The method for desalting chlorine-containing powder according to claim 1 , wherein said solid-liquid separator is a filter press or a belt filter. The solid-liquid separation device is a filter press, solid-liquid separates at least a part of the filter cloth washing wastewater, and the liquid portion is separated into the second desalting washing liquid, the third desalting washing liquid, or 2. The method for desalting chlorine-containing powder according to claim 1 , wherein both are recycled. a slurrying step of mixing the chlorine-containing powder with the first desalting washing liquid to form a slurry;
a chlorine elution step of eluting chlorine contained in the chlorine-containing powder in the slurry into a liquid phase;
a desalted cake forming step of obtaining a first desalted cake and a first filtrate by dehydrating the slurry in which the chlorine has been eluted;
A first desalted cake washing step for obtaining a second desalted cake and a second filtrate by washing the first desalted cake with a second desalted washing liquid separate from the first desalted washing liquid. and,
The second desalted cake is washed with a third desalted washing liquid separate from the first desalted washing liquid and the second desalted washing liquid to obtain a third desalted cake and a third filtrate. a second desalted cake washing step to obtain,
The slurrying step, the chlorine elution step, the desalted cake forming step, the first desalted cake washing step, and the second desalted cake washing step are performed for each supplied chlorine-containing powder. At least part of the third filtrate obtained in the second desalted cake washing step is repeatedly collected and stored, and the first desalted cake washing corresponding to the chlorine-containing powder supplied to the subsequent stage is performed. reused as said second desalting wash for the step, said third desalting wash for said second desalted cake washing step, or both, and reused one or more times Later, while circulating as the first desalting washing liquid,
The desalted cake forming step, the first desalted cake washing step, and the second desalted cake washing step are performed by a solid-liquid separator using a filter cloth, and the filter cloth is washed. A method for desalting chlorine-containing powder, characterized in that at least a part of the filter cloth washing wastewater obtained in the washing process is recycled as the first desalting washing liquid. At least part of the filter cloth washing waste water obtained when the filter cloth is washed is recycled as the second desalting washing liquid, the third desalting washing liquid, or both. 5. The method for desalting chlorine-containing powder according to 4 above. 6. The method for desalting chlorine-containing powder according to claim 4 or 5, wherein said solid-liquid separator is a filter press or a belt filter. The solid-liquid separation device is a filter press, solid-liquid separates at least a part of the filter cloth washing wastewater, and the liquid portion is separated into the second desalting washing liquid, the third desalting washing liquid, or 6. The method for desalting chlorine-containing powder according to claim 4 or 5, wherein both are recycled. When reusing the third filtrate obtained in the second desalted cake washing step, whether or not to reuse the third filtrate is checked in a storage tank in which at least part of the third filtrate is collected and stored, The method for desalting chlorine-containing powder according to any one of claims 1 to 7 , wherein the determination is made by observing any one or more of the following (1) to (5).
(1) total amount of time reused with the third filtrate (2) amount of water reused with the third filtrate (3) pH of the third filtrate
(4) Chlorine ion concentration of the third filtrate (5) Electrical conductivity of the third filtrate At least a part of the second filtrate obtained in the first desalted cake washing step is collected and stored, and the first desalted cake washing step is performed so as to correspond to the chlorine-containing powder supplied to the subsequent stage. any one of claims 1 to 8 , wherein the washing solution is reused as the second desalting washing solution for washing, and after being reused one or more times, is recycled as the first desalting washing solution. 2. The method for desalting chlorine-containing powder according to 1 or 2 above. When reusing the second filtrate obtained in the first desalted cake washing step, whether or not to reuse the second filtrate is checked in a storage tank in which at least part of the second filtrate is collected and stored, The method for desalting chlorine-containing powder according to claim 9 , wherein the determination is made by observing any one or more of the following (1) to (5).
(1) Total amount of time reused with the second filtrate (2) Total amount of water reused with the second filtrate (3) pH of the second filtrate
(4) Chlorine ion concentration of the second filtrate (5) Electrical conductivity of the second filtrate washing the first desalted cake with the second desalting washing liquid in the first desalting cake washing step a plurality of times with the second desalting washing liquid; and/or
11. Any one of claims 1 to 10 , wherein in the second desalted cake washing step, the second desalted cake is washed with the third desalting washing liquid a plurality of times with the third desalting washing liquid. 2. The method for desalting chlorine-containing powder according to item 1. The chlorine-containing according to any one of claims 1 to 11 , wherein the amount of water used is 1.5 parts by mass to 4 parts by mass relative to 1 part by mass of the dry weight of the chlorine-containing powder to be desalted. A powder desalting method. 13. Any one of claims 1 to 12 , wherein the desalted cake forming step, the first desalted cake washing step, and the second desalted cake washing step are performed in one solid-liquid separation device. 10. A method for desalting chlorine-containing powder according to the above item.

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