JP3304300B2 - Cement raw material processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to wastes containing chlorine, such as fly ash discharged from a refuse incinerator and the like, and dust generated in an alkaline bypass facility and a chlorine bypass facility in cement production, as a cement raw material. The present invention relates to a cement raw material processing method for processing so that it can be used.

[0002]

2. Description of the Related Art Conventionally, fly ash discharged from a refuse incinerator has been designated as a specially controlled municipal waste, and can be any of a melting method (volume solidification), a cement solidification method, a chemical treatment method and a solvent extraction method. It is required to carry out pretreatment by such methods, and after being pretreated by those methods, it is disposed of by landfill. Also, in the method of producing cement while extracting chlorine, sulfur, alkali, etc., which circulates and concentrates in the cement kiln and the pre-heater and causes problems such as blockage of the pre-heater together with the kiln exhaust gas to the outside of the cement kiln, Is mixed with the cement of the product or disposed of and landfilled.

[0003] Here, an alkaline bypass facility and a chlorine bypass facility will be described. The volatile components such as chlorine, sulfur, and alkali brought from the raw materials in the cement production are vaporized in the cement kiln, transported to the pre-heater together with the exhaust gas, and these components again generate compounds in the pre-heater. Enter the kiln with. Those compounds which entered the kiln together with the raw materials are vaporized again and transported to the pre-heater together with the exhaust gas. By repeating such a circulation, chlorine, sulfur, alkali and the like are concentrated between the cement kiln and the preheater. When these components are concentrated in this way, a compound having a low melting point is formed, which causes a blockage in the preheater.

[0004] In order to solve such a problem, chlorine, sulfur, alkali and the like which are volatilized together with the exhaust gas are extracted from the lower part of the preheater near the raw material inlet of the kiln.
The extracted exhaust gas is cooled to a temperature lower than the melting point of a compound such as chlorine, sulfur, or alkali, and these components are recovered. An apparatus for removing chlorine, sulfur, alkali, and the like from a cement kiln in this manner is called an alkali bypass. However, the alkali bypass extracts 10% or more of the exhaust gas, which causes a large calorific value loss. In addition, since the raw material particles other than compounds such as chlorine, sulfur, and alkali are simultaneously recovered, the amount of generated dust (alkali bypass dust) is also reduced. More. In view of such problems, chlorine bypass facilities have been developed. The chlorine bypass facility pays attention to the fact that a factor causing a problem such as blockage of the preheater is chlorine among sulfur, alkali and the like. Since chlorine can be sufficiently removed even at a low bleed rate, the chlorine bleed facility reduces the bleed rate to 10% or less to reduce heat loss. In addition, since chlorine is unevenly distributed particularly on the fine powder side of dust generated by cooling the extracted exhaust gas, a classifier is provided in the chlorine bypass facility, and dust generated with a classification point of 5 to 7 μm is converted to coarse powder. It separates it into fine powder and returns the coarse powder together with the exhaust gas into the cement kiln, while collecting the separated fine powder (chlorine bypass dust). By doing so, the heat loss is further reduced, and the amount of dust is also reduced.

[0005] In recent years, as a waste recycling method, as a waste recycling method, a cement raw material or a fuel has been promoted. However, as the usage of these wastes increases, chlorine, sulfur, The amount of volatile components such as alkali also increases, and therefore, the amount of alkali bypass and chlorine bypass also increases. Conventionally, these dusts have been mixed with cement or discarded and landfilled. However, since the amount of generated dust is expected to increase, development of an effective utilization method is required.

[0006]

As described above, fly ash has conventionally been landfilled by pretreatment, but recently, landfill landfills have become tighter, and the area around landfill disposal sites due to elution of harmful components from fly ash has recently been increasing. Has become a problem.
In addition, since alkali bypass dust and chlorine bypass dust contain a large amount of chlorine compounds, there is a possibility that the quality of the cement will be deteriorated when mixed with the cement of the product. Therefore, the chlorine concentration in cement is regulated by the JIS standard, and the amount of addition is limited. In recent years, as the recycling of waste in cement kilns is promoted, the amount of chlorine brought in from waste is expected to increase,
It is considered that the amount of generation of the alkali bypass dust and the chlorine bypass dust also increases accordingly. Therefore, it is expected that the method in which the alkali bypass dust and the chlorine bypass dust are directly added to the cement as described above cannot be dealt with. In addition, when it is disposed of, there is a cost for it and, like waste incineration fly ash,
Tight landfill sites pose a problem.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the conventional treatment of chlorine-containing waste,
(B) Washing waste containing chlorine with water, removing a large amount of chlorine contained in the waste, recycling fly ash as a raw material for cement, and removing the filtrate discharged here to remove harmful components such as heavy metals. (B) After removing harmful components such as heavy metals, chlorides contained in wastewater are further removed and reused as water for elution of chlorine. (C) The sodium chloride or sodium carbonate is generated from the removed chloride and reused. (D) As waste containing chlorine, refuse incineration fly ash, alkali bypass dust or chlorine bypass dust, or a mixture thereof can be used and recycled as a raw material for cement.

That is, the present invention provides (1) a slurry containing chlorine added to water by adding water to elute the chlorine contained in the waste, filtering and, if necessary, washing the chlorine. chlorine was removed and the desalted cake obtained with use in cement raw materials from the filtrate was filtered off, chelating additive
Precipitation of heavy metals and harmful components
To remove the heavy metals and harmful components.
Add calcium ion to sodium ion by adding additives
The calcium carbonate precipitated at this time is
This is a cement raw material processing method used for cement.

Further, the present invention provides (2) evaporating a filtrate after removing heavy metals and harmful components, precipitating and removing dissolved chloride, and evaporating water is liquefied by a condenser or the like. (3) membrane treatment is performed on the filtrate after removing heavy metals and harmful components, and the filtrate is concentrated;
The concentrated liquid is evaporated to remove the dissolved chloride by precipitation, and the evaporated water is liquefied by a condenser or the like, and used together with the demineralized water after the membrane treatment for slurrying water and washing water again. Including. The present invention provides (4) evaporating a filtrate after adding an additive to replace calcium ions with sodium ions or concentrating by membrane treatment and evaporating to precipitate dissolved sodium chloride. Including methods.

The present invention also provides (5) an ion exchange membrane.
By using this, sodium hydroxide is produced from sodium chloride in the filtrate after adding calcium ion to sodium ion by adding an additive,
Includes methods for reconciliation or reuse for other uses.

[0011] In addition, the present invention is, (6) Solvay Process or
Other by Shioyasu soda process, additives to produce sodium carbonate from sodium chloride in the filtrate after replacing the calcium ions to sodium ions was added and the addition at the time of replacing this calcium ions to sodium ions Includes methods of re-use for agents or other uses.

Further, the present invention includes (7) a method of using fly ash discharged from incineration of refuse as waste containing chlorine. Further, the present invention provides (8) in a cement production facility, circulating and concentrating in a cement kiln and a preheater, extracting chlorine, sulfur, alkali, etc. together with the kiln exhaust gas to the outside of the cement kiln; The method includes a method of using the generated dust as a waste containing chlorine when rapidly cooling to a temperature equal to or lower than the melting point of a compound such as sulfur or alkali to remove these components as dust containing a water-soluble chlorine compound. . Here, chlorine, sulfur, alkali, etc. vaporized in the cement kiln are bled together with the flue gas to 10% or less of the total flue gas outside the kiln, and the bled flue gas is rapidly cooled to a temperature equal to or lower than the melting point of the chlorine compound. Separated fine powder dust may be used as waste containing chlorine in cement manufacturing equipment that separates dust generated using 〜7 μm as a classification point into coarse powder and fine powder and returns the coarse powder together with exhaust gas into the cement kiln. it can.

[0013] The apparatus for carrying out the present invention includes:
Cement raw material with a stirring tank for suspending incinerated fly ash, alkali bypass dust and chlorine bypass dust to elute chlorine, a filtration device for filtering and washing this slurry, and a means for removing heavy metals and other harmful components from this filtrate There is a processing unit. Further, as an apparatus for carrying out the present invention, means for evaporating a filtrate from which heavy metals and other harmful components have been removed to precipitate calcium chloride, and cooling and liquefying the water evaporated here, a stirring tank or a filtration apparatus There is a device that has a path to return to.

Further, as an apparatus for carrying out the present invention, means for replacing calcium ions dissolved in the filtrate from which heavy metals and other harmful components have been removed with sodium ions,
Means for filtering and washing the calcium carbonate precipitated here, a membrane device for concentrating the sodium chloride component of the filtrate,
There are means for evaporating the concentrated liquid to precipitate sodium chloride, and an apparatus having a route for cooling and liquefying the water evaporated here and returning it to a stirring tank or a filtration device.

Further, as an apparatus for carrying out the present invention, means for replacing calcium ions dissolved in the filtrate from which heavy metals and other harmful components have been removed with sodium ions,
Means for filtering and washing the calcium carbonate precipitated here, this filtrate, an ion exchange membrane for producing a sodium hydroxide solution from a sodium chloride solution, and an apparatus for removing the harmful components from the sodium hydroxide solution obtained here There is a device having a path for introducing into

Further, as an apparatus for carrying out the present invention, means for replacing calcium ions dissolved in the filtrate from which heavy metals and other harmful components have been removed with sodium ions,
Means for filtering and washing the calcium carbonate precipitated here, the filtrate, means by the Solvay method or the sodium chloride soda method for producing sodium carbonate from the sodium chloride solution,
There is also an apparatus having means for introducing the sodium carbonate obtained here into an apparatus for replacing calcium ions with sodium ions.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

(A) Converting to Cement Raw Material by Rinsing In the present invention, chlorine components are removed by rinsing in order to use fly ash discharged from a refuse incinerator as a partial substitute for cement raw materials. Fly ash discharged from refuse incinerators contains a large amount of chlorine. In some cases, it may contain more than 20% by weight of chlorine. If this fly ash is to be used as a raw material for cement, it is necessary to remove a large amount of chlorine. If the raw material contains a lot of chlorine,
In the cement sintering process, the suspension preheater is blocked and other devices are corroded or deteriorated, and the cement quality of the product is also reduced. According to JIS standards, the amount of chlorine contained in ordinary Portland cement is 200ppm
It is specified as follows. Therefore, chlorine contained in the fly ash is removed by washing with water to obtain a cement raw material.

In the present invention, alkali bypass dust or chlorine bypass dust for circulating and concentrating in a cement kiln and a preheater to remove chlorine, sulfur, alkali and the like which cause problems such as blockage of the preheater is used as part of a cement raw material. To use as an alternative, remove chlorine components by washing with water. Alkali bypass dust and chlorine bypass dust mainly contain about 20% of chlorine compounds such as calcium chloride, sodium chloride and potassium chloride in addition to main cement components such as silica, alumina and calcium. Therefore, the chlorine contained in the alkali bypass dust or the chlorine bypass dust is removed by water washing as in the case of the refuse incinerator fly ash, and used as a cement raw material.

First, fly ash, alkali bypass dust, chlorine bypass dust, or fly ash and a mixture of these dusts are added with water to a degree of fluidization to form a slurry.
At this time, chlorine contained in the treated product elutes into water, and then the slurry is filtered, and the obtained cake is further washed. The desalted cake from which chlorine has been sufficiently removed in this way contains silica, alumina, calcium or the like as a main component, and is used as a partial substitute for a cement raw material. In addition, in the filtrate discharged by the filtration and the washing, heavy metals exceeding the drainage standard may be eluted, although in a trace amount. Therefore, the filtrate is purified by means for removing such heavy metals and other harmful components and then discharged.

(B) Method for Removing Chlorine from Filtrate In the filtrate from which harmful components such as heavy metals have been removed, fly ash and chlorine eluted from alkali bypass dust and chlorine bypass dust are dissolved. There are no chlorine items in the regulations such as drainage standards, but if such wastewater containing high concentration of salt is discharged into rivers, it may cause environmental destruction. Therefore,
The salt is removed from the filtrate, and the filtrate is reused as slurry water or cake washing water. As a method of desalting the filtrate, there is a method of evaporating the filtrate to crystallize and remove salts. The evaporated vapor is cooled, liquefied and reused.

As another method of desalting from the filtrate, there is a method in which the chloride concentration is concentrated by membrane treatment, and the concentrated water is evaporated to dryness to remove chlorine. The evaporated vapor is cooled and liquefied in the same manner as described above, and is reused. Chlorine contained in fly ash of refuse incinerator is mainly calcium chloride,
Therefore, the chloride obtained by desalting the filtrate is mainly composed of calcium chloride. Calcium chloride is a substance that is very difficult to handle because it has a very high deliquescence, easily absorbs moisture in the air and liquefies, and has high corrosivity. Therefore, calcium ions dissolved in the filtrate from which harmful components such as heavy metals have been removed are replaced with sodium ions by a method of adding sodium hydroxide and carbon dioxide, or a method of adding sodium carbonate, thereby precipitating calcium carbonate. Then, filtration and washing are carried out and taken out. The calcium carbonate thus filtered is used as a raw material for cement. The filtrate is removed by converting chlorine into sodium chloride, which is easy to handle, by the above-described evaporation to dryness or membrane treatment.

(C) Recycling method of aqueous sodium chloride solution Calcium ions dissolved in the filtrate from which harmful components such as heavy metals have been removed are replaced with sodium ions, precipitated as calcium carbonate, filtered, washed and taken out. When used as a cement raw material, the filtrate used in the method of the present invention can be used to regenerate the drug. As a method of this drug regeneration method, there is a method of producing sodium hydroxide by a method of purifying a filtrate in which sodium chloride is dissolved through an ion exchange membrane, and using it as a pH adjuster or the like in the process of the present invention. As another method, there is a method in which sodium carbonate is produced from a sodium chloride solution by a sorbet method or a sodium chloride soda method, and the sodium carbonate is used as an additive for replacing calcium ions and sodium ions in the previous step.

(D) Structure of Desalting Cement Raw Material Processing Apparatus The apparatus for carrying out the present invention is shown in FIGS. FIG. 1 is a flow chart of a system for converting waste incineration fly ash, alkali bypass dust and chlorine bypass dust into a raw material for cement according to the present invention. The apparatus shown in FIG. 1 includes a stirring tank 3, a filtration facility 4, and a facility 8 for removing harmful components such as heavy metals. The object to be treated 1 and the water for suspension 2 are charged into the stirring tank 3 to form a suspension. At this time, the chloride contained in the treated product elutes in water. The suspension is filtered in the next filtration equipment 4, and the cake obtained by the filtration is washed.
The desalted cake 5 from which the eluted chlorine has been sufficiently removed is obtained. Since the desalted cake 5 has sufficiently removed chlorine, it can be used as a raw material for cement. The filter used in the filtration equipment 4 may be a belt filter or a filter press. In the case of a belt filter in particular, filtration and cake washing can be performed in one step, and the amount of cake washing water can be saved, which is effective.

The filtrate 7 exiting the filtration equipment 4 may contain trace amounts of harmful components such as heavy metals that elute from the object to be treated and exceed the standards of wastewater. This filtrate is treated in the harmful component removing equipment 8 to remove harmful components. The kiln exhaust gas (20%
PH adjustment by blowing CO2 gas) or adding a chemical, a chelate addition method, an adsorption method using a chelate resin tower, an adsorption method using activated carbon, and the like are used. The precipitate containing a trace amount of heavy metals removed here (mainly calcium carbonate generated mainly by the reaction of kiln exhaust gas and eluted calcium) is used as a cement raw material. Alternatively, heavy metals such as lead and zinc can be regenerated and used from this precipitate. The waste water 9 from which the harmful components have been removed is discharged outside the system.

The waste water 9 contains fly ash, high-concentration chlorine eluted from alkali bypass dust and chlorine bypass dust (which is considered to be mainly eluted as calcium chloride). Chlorine is not a harmful component, and there is no stipulation in wastewater standards. Therefore, it is possible to discharge chlorine as it is, but if released to rivers, etc., there is a concern that it will affect the surrounding environment. Therefore, FIG. 2 shows a cement raw material treatment system provided with equipment for removing chlorine from wastewater. In the system of FIG. 2, the waste water 9 is evaporated to dryness equipment 11 including a vacuum evaporator and the like.
Evaporated to dryness, chloride (mainly calcium chloride)
12 crystallizes. The steam is liquefied again by a condenser 13 as a steam cooling device, becomes distilled recovered water 14, and is used again as a suspension water and a cake washing water in the stirring tank 3 and the filtration facility 4. Therefore, no waste water is discharged from this equipment, or even if it is discharged, the amount is extremely small.

In the system of FIG. 2, the removed chloride 12 crystallizes mainly as calcium chloride. This calcium chloride has a high deliquescence and is difficult to handle, and also has a high corrosiveness, which may cause deterioration of equipment. In addition, in this system, since it is necessary to evaporate the entire amount of wastewater, running costs may be increased when the system is installed in a place without a heat source.
FIG. 3 shows a system for solving these problems.
In the system shown in FIG. 3, the waste water 9 is introduced into a calcium and sodium substitution reaction device 15, and the dissolved calcium ions are replaced with sodium ions, and the calcium carbonate is replaced with calcium carbonate.
16 generates. For this substitution reaction, a method of adding NaCO3, a method of adding NaOH, and further blowing a kiln exhaust gas to utilize CO2 gas in the exhaust gas are effective. In this way, the wastewater 17 which has been replaced with sodium ions and has become a sodium chloride solution is introduced into the membrane treatment facility 18, where the salt content is more than doubled.
The desalinated water 19 desalted here is reused in the stirring tank 3 and the filtration equipment 4. An electrodialysis membrane (ED) or a reverse osmosis membrane (RO) can be used for the membrane treatment equipment 18. The concentration of the reverse osmosis membrane is about twice, whereas the electrodialysis membrane is about 7 times.
Electrodialysis membranes are more effective because they can be concentrated about twice. The concentrated water 20 concentrated in the membrane treatment equipment is then introduced into an evaporator-to-evaporator 21 and evaporated to dryness, where chlorides 22 mainly composed of sodium chloride are crystallized. In the case of sodium chloride, it is easy to handle, not corrosive, and has a high possibility of being reused. The steam generated in the evaporating and drying equipment 21 is again liquefied in a condenser 23 as a steam cooling device, becomes distilled recovered water 24, is introduced into a stirring tank or a filtration equipment, and is reused.

Next, FIG. 4 shows that sodium hydroxide is produced as one of the effective uses of the aqueous sodium chloride solution 17 in which calcium ions are replaced with sodium ions, and is used for adjusting the pH of waste water in the process of the present invention. Shows the system to do.
The aqueous sodium chloride solution 17 is introduced into a facility 25 for producing sodium hydroxide using an ion exchange membrane, where sodium hydroxide 26 is separated and produced. This sodium hydroxide is introduced into the harmful component removing equipment 8 and used for wastewater treatment such as pH adjustment. The water 27 separated and recovered by the ion exchange membrane is reused in a stirring tank or a filtration facility. Another method of effectively using the aqueous sodium chloride solution 17 is the production of sodium carbonate by the solvay method or the sodium chloride soda method shown in FIG. An aqueous solution of sodium chloride is introduced into a sodium carbonate production facility using the Sorbet method or the sodium salt soda method to produce sodium carbonate 29. This sodium carbonate 29 is used as an additive in a replacement reaction facility 15 for calcium and sodium. In addition, water separated by the Solvay method or the salt and soda method is reused as recovered water 30 in a stirring tank or a filtration facility.

[0028]

Examples of the present invention will be described below. These are examples and do not limit the scope of the present invention. Example 1 An experiment was conducted by temporarily installing the equipment shown in FIG. 2 for an experiment. First, fly ash containing 22% of chlorine and 30% of calcium is charged into the stirring tank 3 at a rate of 15 kg / hr as a treatment object 1, and warm water heated to about 50 ° C. is added thereto at 20 kg / hr. Stirring tank 3
Was set to be about 1 hour and mixed. Next, this suspension was filtered with a belt filter of the filtration equipment 4 and washed with 50 ° C., 55 kg / hr hot water cake. In this way, desalted cake 5 of fly ash was obtained at 22.8 kg-wet / hr. Chlorine in the cake 5 was analyzed to be 0.2%
Chlorine was sufficiently removed (in terms of dry weight), and it could be used as a cement raw material.

[0029]

[Table 1]

Next, the filtrate 7 discharged from the filtration equipment 4 was analyzed for items specified in the drainage standard. Table 1 shows the results. Only lead was 13.7 mg / l, which exceeded the wastewater standard. This filtrate 7 is introduced into a harmful component removing facility 8. This harmful component removing device 8 has a pH
Conditioning equipment, adsorption and removal equipment for harmful components with chelating agents,
It consists of a small filtration device, a chelating resin tower for mercury, and an activated carbon tower. Next, the wastewater 9 that exited the harmful component removing equipment 8 was sampled and analyzed. Table 1 shows the results. The detected lead value was below the detection limit. Thus, the effluent 9 discharged from the harmful component removal equipment 8 does not contain harmful components and satisfies the effluent standards, and may be discharged out of the system at this stage as in the apparatus of FIG. It is possible. Further, a precipitate mainly composed of calcium carbonate containing a trace amount of heavy metals, which is generated here, can be removed by a filter and recycled to a cement raw material. Drainage 9 is 62.2kg / h
r Emitted and contains 5.5% chlorine. This is introduced into the evaporating and drying equipment 11. The wastewater was distilled in the vacuum evaporator of this facility, generating 3.4 kg / hr of chloride mainly composed of calcium chloride. The amount of steam used as a heat source at this time was 30.25 kg / hr
Met. The evaporated vapor was introduced into a condenser 13 as a vapor cooling device, liquefied again, and collected. 48 kg / hr of recovered water 14 was obtained, and all the recovered water was used as a cake washing solution in the filtration equipment 4.

As described above, the apparatus shown in FIG. 2 desalted the incinerated fly ash to a chlorine concentration suitable for use as a cement raw material, and was able to reduce the amount of water used by circulating wastewater produced by washing. . In addition, it was proved that the treatment of harmful components of the wastewater was sufficient equipment, and it was possible to discharge the wastewater without performing the desalination circulation. The experiment was performed continuously for 6 hours after the system was stabilized.

Example 2 Next, an experiment was conducted by temporarily installing the equipment shown in FIG. 3 for an experiment.
Steps 1 to 10 are the same as in Example 1. First, 15 kg of fly ash containing 22% of chlorine and 30% of calcium is placed in the stirring tank 3.
/ hr at a rate of 20k
g / hr, and the mixture was set so that the residence time in the stirring tank was about 1 hour. Next, the suspension is filtered through filtration equipment 4.
And the cake was washed with warm water at 50 ° C and 55 kg / hr. In this way, 22.8 kg-wet / hr of desalted cake 5 was obtained in the same manner as in Example 1. When the chlorine in the cake 5 was analyzed, it was found that the chlorine was also sufficiently removed to be 0.2% (in terms of dry weight). It can be used as a raw material for cement.

The filtrate 7 was used to remove harmful components in a harmful component removal facility 8. In addition, in Example 1, it was confirmed that the treated wastewater 9 was purified so as to sufficiently satisfy the wastewater standards. Therefore, in Example 2, the analysis of the harmful components in the treated wastewater was not performed. However, the analysis for chlorine and calcium was performed. As a result, the chlorine concentration of this wastewater 9 becomes
5.5% and calcium ion concentration were 0.97%. Then 6
The wastewater 9 of 2.2 tkg / hr is introduced into the replacement reactor 15 for calcium ions and sodium ions. The replacement device 15 includes a reaction tank, a NaOH addition device, and a kiln exhaust gas bubbling device. Calcium ions in the wastewater are replaced with sodium ions, and the calcium ions combine with carbonate ions to precipitate calcium carbonate. At this time, about 0.
6 kg / hr sodium hydroxide was added, and calcium carbonate
Generated 1.4kg / hr. The generated calcium carbonate was filtered by a small filtration device. This calcium carbonate can also be used as a cement raw material.

The wastewater 17 of 62.2 kg / hr mainly containing an aqueous solution of sodium chloride leaving the substitution reactor 15 is introduced into a membrane treatment facility 18. This membrane treatment equipment 18 is composed of an electrodialysis membrane, a pretreatment device therefor and peripheral devices. Here, the wastewater 17 is concentrated to obtain a 9.3 kg / hr concentrated water 20. This concentrated water 20
Was introduced into an evaporating and drying device 21 and evaporated to dryness in a vacuum evaporator. 3.6 kg / hr of sodium chloride 22 was obtained. At this time, the amount of steam required as a heat source for evaporating and drying was 5 kg / hr, and the amount of evaporating liquid was reduced by the membrane treatment. The amount was significantly reduced. Also, since the chloride generated here is sodium chloride, it is easy to handle,
In addition, since the corrosion property is low, it is considered that deterioration of the equipment can be reduced. 52.9 kg / hr of demineralized water 19 obtained in the membrane treatment equipment 18
The steam generated in the evaporating and drying equipment 21 is cooled by a condenser 23 as a steam cooling device and reliquefied, and 7.5 kg / hr of recovered water 24 obtained is introduced into the stirring tank 3 and the filtering equipment 4 for reuse. .

As described above, the apparatus shown in FIG. 3 can desalinate incinerated fly ash to a chlorine concentration suitable for use as a cement raw material in the same manner as in Example 1, and circulate wastewater generated by washing. The amount of water used was also saved. Further, by replacing calcium with sodium, the chloride finally taken out can be converted into sodium chloride, which seems to have solved the problems concerning the handling method of chloride and corrosivity. In addition, it was demonstrated that the use of the membrane treatment equipment 18 reduced the amount of wastewater that evaporates to dryness and significantly reduced the amount of steam used. The experiment of Example 2 was also performed continuously for 6 hours after the system was stabilized.

As in the embodiment 2 shown in FIG. 2, the waste water 17 is an aqueous sodium chloride solution. Therefore, it is conceivable to use sodium hydroxide or sodium carbonate to be used in the water treatment step of the present invention from this aqueous sodium chloride solution. As shown in FIG.
Generates 26 and can be used for pH adjustment in removing harmful components of wastewater. Further, as shown in FIG. 5, it is also possible to generate sodium carbonate by a solvay method or a sodium salt soda method and use it as an additive in a substitution reaction between calcium ions and sodium ions. As described above, according to the method of the present invention, fly ash from a refuse incinerator can be recycled as a raw material for cement, and the wastewater discharged from this system is safe and sufficiently satisfies the wastewater standards. In addition, by desalinating and reusing wastewater, the amount of water used can be greatly reduced.

Example 3 The equipment shown in FIG. 1 was temporarily installed for an experiment, and a washing experiment of chlorine bypass dust was performed. First, a chlorine bypass dust containing 15% of chlorine is charged into the stirring tank 3 at a charging rate of 15 kg / hr, and warm water heated to about 50 ° C. is added thereto at 20 kg / hr,
The residence time in the stirring tank 3 was set to be about 1 hour, and the mixture was stirred. Table 2 shows the analysis values of the used chlorine bypass dust.

[0038]

[Table 2]

Next, the suspension was filtered with a belt filter of a filtration device 4 and washed with 50 ° C., 55 kg / hr hot water cake. Thus, about 25 kg of desalted cake was obtained, and the cake was dried and analyzed for chlorine. As a result, it was 0.15%, and chlorine was sufficiently removed. Table 2 shows the analysis values of the chlorine bypass dust used.

Next, cement was actually produced by trial using a desalted cake of chlorine bypass dust. Approximately 4t / day when exhaust gas is extracted from a cement kiln with cement clinker production capacity of 7000t / day at a 4% extraction rate by chlorine bypass equipment.
Of chlorine bypass dust is recovered. If all this chlorine bypass dust is treated by the method of the present invention and it is going to be used as a cement raw material, 6.08 t / da out of 11200 t / day raw material
The chlorine bypass dust desalting cake of y will be used. Therefore, in the present embodiment, the heavy metal-containing compound 10 containing calcium carbonate as a main component, which is a precipitate generated when the desalting cake 5 and the filtrate 7 of the chlorine bypass dust are treated as the raw materials at this ratio, is used for cement. Trial production was performed.

Table 3 shows the quality of the cement thus produced.

[0042]

[Table 3]

As shown in Table 3, the chlorine concentration of the prototype cement was
The concentration was 0.005%, which sufficiently satisfied the JIS standard. Further, 27.5N / mm ² 3 days an age as a result of compressive strength test of the cement by JIS method, at the age 7 days 42.8 N / mm ^2, the age of 28
It was 59.5 N / mm ² per day, and the compressive strength sufficiently satisfied the standard. Next, the filtrate 7 discharged from the filtration equipment 4
The wastewater 9 after treating the wastewater with the harmful component removing equipment 8 was analyzed. Table 4 shows the results. As described above, the wastewater 9 discharged by the method of the present invention satisfies the discharge standards for sewage and the wastewater standards according to the water pollution method for both hazardous substances and environmental items.

[0044]

[Table 4]

As in the above-described Example 3, the method of the present invention enables desalting to a chlorine concentration sufficient to be used as a cement raw material even when chlorine bypass dust is used in the same manner as incineration ash. Also met the emission standards. This wastewater is a solution containing sodium chloride, potassium chloride, and calcium chloride as in the case of treating incineration ash, and this wastewater can be effectively used by the methods shown in Figs. 2, 3, and 4. Clearly, it is possible. It is clear that the same effect can be obtained by using the alkali bypass dust according to the method of the present invention.

[0046]

The following effects can be obtained by the method of the present invention. The fly ash discharged from the refuse incinerator is added to water to form a slurry, and the chlorine contained in the fly ash is eluted,
This can be filtered to sufficiently remove chlorine from the fly ash, thereby enabling the fly ash to be used as a cement raw material. In addition, the filtrate discharged at this time is also safe by removing harmful components by sedimentation and filtration, so that only chlorides are eluted in the wastewater, and harmful components do not flow out of the system. In addition, dissolved in the wastewater
Calcium ions are replaced by sodium ions.
Calcium carbonate precipitated during use as a cement raw material
It is possible to do. As described above, fly ash that has been conventionally landfilled can be effectively used, and it is a solution to the problem of tight landfill sites and the problem of environmental pollution due to elution of harmful substances around the landfill sites.

Further, the wastewater is concentrated by a direct evaporation or membrane treatment and then evaporated to separate chlorides, and the reuse of the distilled water allows the wastewater in which the chlorides are dissolved to be discharged outside the system. In addition, the effect of the chloride solution on the environment of river water can be prevented. Also, by replacing calcium dissolved in the wastewater with sodium, it is possible to prevent scale adhesion to the membrane in the membrane treatment process and extend the life of the membrane, and to replace sodium chloride in the distillation process instead of calcium chloride. Is generated, so that the corrosiveness and deliquescence are reduced, the corrosion of the equipment is prevented, and the handling property of the precipitate is improved.

Further, sodium hydroxide is obtained from a sodium chloride solution obtained by replacing calcium in a chloride solution obtained by washing fly ash with water by sodium ion exchange membrane by an ion-exchange membrane. The production of sodium carbonate is possible, and by using these chemicals in the water treatment process of fly ash washing, the running cost can be reduced, and the disposal of chlorine removed from wastewater is not hindered.

Further, alkali bypass dust and chlorine bypass dust can be used as a cement raw material by washing with water according to the method of the present invention. Conventionally, alkali bypass dust and chlorine bypass dust were directly mixed with cement, but if waste is recycled in a cement kiln, it is expected that the amount of these generated will increase, and it is directly mixed with cement. It is thought that the method cannot cope. In addition, there is a cost for landfilling, and in recent years,
Tight landfill sites are also a problem. The method of the present invention is an effective means for solving such a problem.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an apparatus for performing a cement raw material processing method of the present invention.

FIG. 2 is a configuration diagram of an apparatus of another apparatus for performing the method for converting cement raw material of the present invention.

FIG. 3 is a configuration diagram of still another apparatus for carrying out the method of converting a cement raw material of the present invention.

FIG. 4 is a configuration diagram of still another apparatus for performing the cement raw material processing method of the present invention.

FIG. 5 is a configuration diagram of still another apparatus for carrying out the method for converting a cement raw material of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing target 2 Water 4 Filtration equipment 5 Desalting cake 7 Filtrate 8 Hazardous component removal equipment 9 Drainage 11,21 Evaporation and drying equipment 12,22 Chloride 13,23 Condenser as steam cooling device 15 Ca-Na substitution reaction device 16 Calcium carbonate 18 Membrane treatment equipment 19 Demineralized water 25 NaOH production equipment 26 Sodium hydroxide 28 Sodium carbonate production equipment 29 Sodium carbonate

Continuation of front page (56) References JP-A-62-252351 (JP, A) JP-A-4-77337 (JP, A) JP-A-6-157089 (JP, A) JP-A-5-305279 (JP, A) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 7/38 C04B 18/10 C04B 7/60 C04B 18/30 B09B 3/00

Claims (9)

(57) [Claims] After 1. A eluted chlorine waste in the waste by adding water containing chlorine, a method of using desalted cake obtained this was filtered to cement raw material, waste Metals and harmful components in the filtrate from which chlorine eluted
Min was precipitated, which was filtered to remove the heavy metals and harmful components, added additives to the filtrate after removal of the heavy metals and toxic components
To replace calcium ions with sodium ions, and the calcium carbonate precipitated at this time is used as a raw material for cement.
Cement raw material processing wherein the that. 2. The filtrate from which heavy metals and harmful components have been removed is evaporated to dissolve and remove dissolved chlorides, and the evaporated water is liquefied and used again for chlorine elution. The cement raw material processing method according to claim 1, wherein the method is used for water. 3. Filtration after removing heavy metals and harmful components.
Solution was concentrated by a membrane process, evaporating the concentrated solution to precipitate chloride dissolved and removed, and liquefies the evaporated water, together with demineralized water after membrane treatment, chlorine elution for re The method according to claim 1 or 2, wherein the method is used for water. 4. Evaporating the filtrate after adding an additive to replace calcium ions with sodium ions or concentrating by membrane treatment and evaporating the filtrate to precipitate dissolved sodium chloride. The method according to claim 2 or 3, wherein the cement raw material is treated. 5. Use of an ion-exchange membrane to generate sodium hydroxide from sodium chloride in a filtrate after adding an additive to replace calcium ions with sodium ions, and adjust the pH of wastewater or The method according to claim 2 or 3, wherein the method is reused for other purposes. 6. A method according to the Solvay method or the salty sodium soda method,
After adding an additive to replace calcium ions with sodium ions , sodium carbonate is generated from sodium chloride in the filtrate, and the calcium ions are converted into sodium ions .
The method according to claim 2 or 3, wherein the method is reused as an additive for ion substitution or for other uses. 7. The fly ash discharged from incineration of refuse is used as chlorine-containing waste.
7. The method for treating a cement raw material according to any one of 6 to 6 above. 8. In a cement production facility, circulating and concentrating in a cement kiln and a preheater, extracting chlorine, sulfur, alkali, etc. together with the kiln exhaust gas out of the cement kiln, and extracting the extracted exhaust gas into chlorine, sulfur, alkali, etc. When rapidly cooling to a temperature below the melting point of the compound to remove these components as dust containing a water-soluble chlorine compound,
The method according to any one of claims 1 to 7, wherein the generated dust is used as a waste containing chlorine. 9. After the chlorine, sulfur, alkali, etc. vaporized in the cement kiln are extracted together with the exhaust gas, 10% or less of the total exhaust gas amount is extracted outside the kiln, and the extracted exhaust gas is rapidly cooled to a temperature not higher than the melting point of the chlorine compound. , 5 to 7 μm is classified as a classification point, the separated dust is separated into coarse powder and fine powder, and the separated fine powder dust is used as waste containing chlorine in a cement manufacturing facility in which the coarse powder is returned to the cement kiln together with the exhaust gas. The method according to claim 8, wherein the raw material is used as a raw material for cement.