JP2012166121A - Method and apparatus for reducing halogen from cement producing facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for reducing halogen from cement producing facility by which halogen circulated and concentrated in the cement producing facility can be effectively reduced.SOLUTION: In the cement producing facility, during a period until combustion exhaust gas produced in a rotary kiln for firing a cement raw material is discharged to outside air, dust recovered from a settling chamber, a stabilizer, a dust collector and a bag filter is slurried, and then subjected to dehydration treatment and solid-liquid separation. The obtained filtrate is subjected to wastewater treatment to remove contained halogen from the cement producing facility and a solid obtained by solid-liquid separation is reutilized by being mixed with a raw material. Thus, there are provided the method and the apparatus for reducing halogen from the cement producing facility. The method is preferably implemented when a cement raw material crusher included in the cement producing facility stops.

Description

  The present invention relates to a method and an apparatus for reducing halogen from a cement production facility, and more particularly to a method for reducing halogen such as bromine circulating in the cement production facility and an apparatus for reducing halogen such as bromine.

  In recent years, cement production facilities have been using them as raw fuels for the effective use of construction waste soil, sludge, dust, food waste, waste plastics, etc. Along with the increase in the amount of waste raw fuel, the problems of destabilization of the operating state of cement production facilities and deviation of the cement composition from JIS standards are caused by the trace components contained in these wastes.

When waste plastics or waste resins containing halogen-based flame retardants such as bromine and fluorine are used as raw material for cement, bromine is circulated and concentrated in the cement production facility, and coaching occurs in the preheater and is contained in the cement. Problems such as an increase in halogen concentration occur.
Accordingly, it is necessary to reduce halogen such as bromine that is circulated and concentrated in the cement production facility.

As a method of reducing halogens such as bromine in cement production facilities, conventionally, a method of extracting exhaust gas containing halogen such as bromine at a high concentration from the kiln bottom of a cement rotary kiln (desalting bypass) is used. Halogens such as bromine are reduced in the facility.
Such a desalting bypass device extracts chlorine from the kiln bottom of the cement kiln and cools it to remove volatile components such as chlorine that have been repeatedly concentrated and volatilized and condensed between the cement kiln and the preheater. It is a device that removes chlorine from the cement kiln by generating chlorine bypass dust in which volatile components mainly composed of compounds such as these are solidified and discharging the chlorine bypass dust out of the system.

However, in such a desalting bypass method, exhaust gas containing a high concentration of halogen such as bromine is extracted, so it is possible to reduce halogen in the cement facility, but with an increase in the exhaust gas extraction amount. This is not preferable because heat loss increases.
In addition, due to operational restrictions in the cement manufacturing process, the amount of exhaust gas extracted by the desalting bypass is approaching the upper limit.

Japanese Patent Laid-Open No. 2005-97005 (Patent Document 1) discloses a method for effectively and stably preventing the accumulation of harmful substances such as mercury and dioxin accumulated in the facility when manufacturing cement. In a method for producing cement, exhaust gas generated in a rotary kiln for cement raw material firing is discharged from a chimney through a preheater for preheating the cement raw material, a dryer and a dust collector for drying the cement raw material, After exhausted from the preheater, a part of the exhaust gas at a temperature of 350 ° C. or higher that circulates in the pipe or device until reaching the chimney is extracted, dust is separated from the extracted exhaust gas, and then the gas is at a temperature of 100 ° C. or lower Describes a method for producing cement, in which the vaporized material is condensed by cooling.
In such a method, dust is recycled as it is in the raw material system, and it is insufficient to effectively reduce halogen such as bromine that is circulated and concentrated in the cement production facility.

In JP-A-2002-147722 (Patent Document 2), a PCB-containing material brought into a cement factory from the outside is put into a rotary kiln and heated with heat (1000 ° C. or higher) when the cement clinker is fired. There has been proposed a method of decomposing and exhausting the exhaust gas generated during the thermal decomposition out of the rotary kiln and then rapidly cooling it at a cooling rate of 20 ° C./second or more.
Such a method can decompose chlorine-containing substances carried from outside the cement production facility, but is insufficient to effectively and effectively reduce halogens such as bromine circulating and concentrated in the cement production facility. It is.

  In the future, waste recycling at cement production facilities will continue to progress, and the amount of halogen such as bromine from waste will also increase. To expand the effective use of such waste resources, bromine The establishment of a desalination technology for cement production facilities that can accept raw fuels such as industrial wastes with high halogen content is desired.

JP 2005-97005 A JP 2002-147722 A

Accordingly, an object of the present invention is to solve the above-described problems and to effectively reduce halogen such as bromine that is circulated and concentrated in the cement production facility, and a novel method and apparatus for reducing halogen from cement production facility Is to provide.
Specifically, waste plastics and waste resins containing halogen-based flame retardants such as bromine and fluorine, waste building materials, waste interior parts, shredder dust, etc. are used as raw materials for cement, especially in cement rotary kilns. It is to provide a novel method and apparatus for reducing halogen from cement production equipment, which can reduce the concentration and amount of halogen such as bromine derived from cement raw fuel that is circulated and concentrated between the preheater and the preheater. .

  The method for reducing halogen from a cement production facility according to the present invention is a method for slurrying dust recovered from exhaust gas until the combustion exhaust gas generated in a rotary kiln for cement raw material firing is released into the outside air in the cement production facility. Then, dehydration treatment is performed for solid-liquid separation, and the obtained filtrate is treated with waste water to remove contained halogen from the cement production facility, and the solid content obtained by the solid-liquid separation is mixed with the raw material and recycled. A method for reducing halogen from a cement production facility, characterized in that it is used.

Preferably, in the method for reducing halogen from the cement production facility of the present invention, the dust is recovered from at least one place selected from the group consisting of a sedimentation chamber, a stabilizer, a dust collector, and a bag filter. .
More preferably, in the method for reducing halogen from the cement production facility according to the present invention, the dust collector is provided with a plurality of electric fields, and the dust is recovered from at least the most downstream electric field of the exhaust gas flow. Features.

Preferably, in the method for reducing halogen from the cement production facility of the present invention, after recovering useful metals from the filtrate obtained by solid-liquid separation, the halogen is removed from the cement production facility by treating with waste water. It is characterized by doing.
More preferably, in the method for reducing halogen from the cement production facility of the present invention, the solid content obtained by solid-liquid separation is dried, and after the dried solid content is mixed with the raw material, the preheater is used. It is introduced and reused.

Preferably, the method for reducing halogen from the cement production facility according to the present invention is performed when the cement raw material crushing device included in the cement production facility is stopped. This is a reduction method.
More preferably, when the method for reducing halogen from the cement production facility according to the present invention is performed when the raw material crushing apparatus is stopped, when the cement raw material crushing apparatus is in operation, a rotary kiln for cement raw material firing is used. The dust recovered from the exhaust gas until the generated combustion exhaust gas is released into the outside air is mixed with the raw material and then introduced into the preheater and circulated.
More preferably, in the method for reducing halogen from the cement production facility of the present invention, the halogen is bromine.

  The apparatus for reducing halogen from the cement production facility according to the present invention includes a raw material calcining apparatus including a rotary kiln for cement raw material calcining and a preheater, a slurrying apparatus for dust recovered from exhaust gas discharged from the raw material calcining apparatus, and dehydrating the slurry. A solid-liquid separation device, a wastewater treatment device for a filtrate obtained by the solid-liquid separation, and a raw material mixing / feeding device for mixing the solid content obtained from the solid-liquid separation with the raw material. It is a device for reducing halogen from cement production facilities.

Preferably, the apparatus for reducing halogen from the cement production facility of the present invention includes a sedimentation chamber, a stabilizer, a dust collector, and a bag filter that collect dust from the exhaust gas.
More preferably, in the apparatus for reducing halogen from the cement production facility of the present invention, the dust collector is provided with a plurality of electric fields.
More preferably, in the halogen reduction apparatus from the cement production facility of the present invention, a useful metal is further added from the filtrate obtained from the solid-liquid separation apparatus between the solid-liquid separation apparatus and the wastewater treatment apparatus. A useful metal recovery device for recovery is provided.

  Preferably, in the halogen reduction apparatus from the cement production facility of the present invention, a solid content obtained by the solid-liquid separation is further provided between the solid-liquid separation apparatus and the raw material mixing / feeding apparatus. A raw material mixing / feeding device and a preheater are installed so that the raw material mixed with the solid content by the raw material mixing / feeding device is introduced into the preheater.

Preferably, the halogen reduction device from the cement production facility according to the present invention operates when the cement raw material crushing device included in the cement production facility is stopped. Device.
More preferably, in the halogen reduction apparatus from the cement production facility of the present invention, when the cement raw material crusher is in operation, the combustion exhaust gas generated in the rotary kiln for cement raw material firing is released into the outside air. The dust collected from the exhaust gas is introduced into the raw material mixing / feeding device and mixed with the raw material, and the raw material mixing / feeding device and the preheater are installed so as to be introduced into the preheater. .
More preferably, in the halogen reduction apparatus from the cement production facility of the present invention, the halogen is bromine.

With the method and apparatus for reducing halogen from a cement production facility according to the present invention, the concentration and amount of halogen such as bromine circulating in the cement production facility can be reduced.
In particular, circulating and concentrating in the preheater, and circulating and concentrating by mixing dust trapped in the exhaust gas with fresh raw materials and supplying them as raw materials for cement production, such as bromine in cement facilities The concentration and amount of halogen can be reduced.

In addition, by using a method other than desalting bypass, the amount of bromine and other halogens discharged outside the cement facility can be increased to reduce the amount of circulating concentration in the cement manufacturing facility. There is no problem of heat loss due to exhaust gas exhaustion.
Furthermore, it is possible to efficiently reduce the concentration and amount of halogen circulating in the cement production facility, both when the raw material crusher is on and when it is off.

  In addition, by using the method and apparatus of the present invention, it is possible to expand the effective use of waste resources in cement production facilities, and accept raw fuel such as industrial waste with a high halogen content such as bromine. It is possible to establish a cement manufacturing facility corresponding to the above.

It is a figure which represents typically an example of the conventional cement manufacturing equipment. It is a figure which represents typically an example of the reduction apparatus for implementing the halogen reduction method from the cement manufacturing equipment of this invention. It is a figure which shows an example of the change of the bromine density | concentration in the raw material and supply apparatus of the conventional cement manufacturing equipment. It is a figure which shows an example of the change of the bromine density | concentration in the raw material and supply apparatus at the time of applying the halogen reduction method from the cement manufacturing equipment of this invention. It is a figure which shows another example of the change of the bromine density | concentration in the raw material and supply apparatus of the conventional cement manufacturing equipment. It is a figure which shows another example of the change of the bromine density | concentration in the raw material and supply apparatus at the time of applying the halogen reduction method from the cement manufacturing equipment of this invention.

A typical example of a conventional cement production facility will be schematically described with reference to FIG.
FIG. 1 is a diagram showing a typical flow of a conventional cement manufacturing facility.
The cement raw material supplied to the preheater 2 is preheated by the exhaust gas from the cement rotary kiln 1, decarboxylated in the calcining furnace 3, sent to the rotary kiln 1 and fired.
Most of halogens such as bromine contained in cement raw materials and cement fuel are circulated and concentrated between the preheater 2 and the kiln bottom of the cement rotary kiln 1, and some of them are scattered in the exhaust gas treatment system and captured as dust. The raw material is mixed with the fresh cement raw material in the raw material mixing / feeding device 10 and recirculated in the cement manufacturing facility as cement raw material / fuel.
In this case, halogens such as bromine are discharged to the outside of the cement facility through desalination bypass, exhaust of the bag filter 9, exhaust of the air quenching cooler (AQC) dust collector 21 (AQC-EP), and clinker 18. In the steady state, the amount of halogen introduced such as bromine is equal to the amount of discharge.

  In such a normal case, the dust collected from the settling chamber 4, the stabilizer 5, the dust collector 8, and the bag filter 9 passes through the preheater 2 and the calcining furnace 3 together with the cement raw material, and is fired in the rotary kiln 1. In this case, however, a part of the halogen such as bromine contained in the dust is separated from the cement raw material before moving downward of the preheater 2 and scattered upward, and is included again in the supplied raw material. Therefore, circulation concentration is performed in the preheater 2.

In addition, a part of halogen such as bromine contained in the dust is separated from the cement raw material and scattered upward before moving to the lower side of the preheater 2, flows into the exhaust gas pipe together with the exhaust gas, and is adsorbed by the dust. . The halogen adsorbed by the dust traces the process of capturing again in the dust collector 8, the bag filter 9 and the like and re-introducing it into the cement manufacturing apparatus, and repeats this process.
In this way, since halogen circulates repeatedly, when waste is supplied as part of the cement raw material, the concentration of halogen contained in the dust gradually increases, and as a result, the concentration of halogen in the cement facility also increases. It will increase.

Therefore, the present invention increases the discharge amount of halogen such as bromine and decreases the circulation concentration amount of the halogen in the cement equipment.
The method for reducing halogen from a cement production facility according to the present invention is to slurry dust collected from exhaust gas until the combustion exhaust gas generated in the rotary kiln for cement raw material firing in the cement production facility is released into the outside air. Next, it is dehydrated and separated into solid and liquid, and the resulting filtrate is treated with waste water to remove the contained halogen from the cement production facility. The solid content obtained by the solid and liquid separation is mixed with the raw material and reused. This is a method for reducing halogen from cement production equipment.
Preferably, the dust is recovered from at least one location selected from the group consisting of a sedimentation chamber, a stabilizer, a dust collector and a bag filter.
In particular, the method for reducing halogen from the cement production facility of the present invention is effective when the cement raw material crushing device included in the cement production facility is stopped.

In addition, the halogen reduction apparatus from the cement production facility of the present invention includes a raw material firing apparatus including a rotary kiln for cement raw material firing and a preheater, a slurry slurrying apparatus for recovering dust collected from exhaust gas discharged from the raw material firing apparatus, and dewatering the slurry. Cement production facility comprising a solid-liquid separation device to be treated, a wastewater treatment device for a filtrate obtained by the solid-liquid separation, and a raw material mixing / feeding device for mixing the solid content obtained from the solid-liquid separation with the raw material Is a device for reducing halogens.
Preferably, a settling chamber, a stabilizer, a dust collector, and a bag filter for collecting dust from the exhaust gas are provided.
In particular, it is effective that the apparatus for reducing halogen from the cement production facility of the present invention operates when the cement raw material crushing device included in the cement production facility is stopped.

FIG. 2 is a diagram schematically showing an example of a reduction device for carrying out the method for reducing halogen from a cement production facility according to the present invention. The present invention will be described in detail with reference to FIG. It is not limited.
1 and 2, the solid line represents the flow of gas, and the dotted line represents the flow of material such as a raw material.
The cement manufacturing raw material is pulverized and mixed by the raw material pulverizer 6 and supplied to the upper portion of the preheater 2 and the preheater 2 d via the raw material mixing / supply system device 10.
Here, as the cement raw material, for example, limestone, clay, silica stone, iron slag, waste such as main ash generated by incineration of sludge and municipal waste can be used, and in these raw materials, particularly in waste, Contains a lot of halogen such as bromine.

The preheater 2 is composed of a plurality of cyclones 2a, 2b, 2c, and 2d, and the number thereof is not limited.
The cement raw material is preheated in the preheater 2 while sequentially moving from the upper cyclone 2d to the lower cyclone 2c, cyclone 2b, and cyclone 2a, and is introduced into the lowermost cyclone 2a. Supplied with.

Furthermore, a calcining furnace 3 may be provided between the preheater 2 and the rotary kiln 1 and is provided in order to efficiently promote calcining of the cement raw material.
As the calcining furnace 3, any known calcining furnace can be used, for example, SF calcining furnace, MFC calcining furnace, RSP calcining furnace, KSV calcining furnace, DD calcining furnace, SLC calcining furnace. An example is a kiln.
When the calcining furnace 3 is provided, the calcined cement raw material is supplied to the rotary kiln 1.
In the present invention, the cement rotary kiln 1, the preheater 2, and the calcining furnace 3 are referred to as a raw material baking apparatus.

The cement raw material supplied into the rotary kiln 1 is fired to produce a clinker.
The manufactured cement clinker is introduced into an air quenching cooler (AQC) 7, cooled, and then stored in a clinker silo 18. The exhaust gas from the AQC is guided to the AQC sedimentation chambers 19 and 20 and the AQC dust collector 21 and processed, and is exhausted from the chimney 22 to the outside.
These AQC7, AQC sedimentation chambers 19 and 20, the AQC dust collector 21 and the like are not particularly limited, and are processed by a known method using a known apparatus.

The exhaust gas generated when the cement raw material is heated and fired in the rotary kiln 1 is discharged from the rotary kiln 1 and flows into the preheater 2a.
As shown in FIG. 2, when the calcining furnace 3 is provided, the high-temperature exhaust gas discharged from the rotary kiln 1 is used for calcining the cement raw material in the calcining furnace 3, It flows into the furnace 3. The exhaust gas generated in the calciner 3 also flows into the preheater 2a.
Further, the exhaust gas discharged from the rotary kiln 1 is partially extracted and subjected to a desalting bypass process.

The exhaust gas flowing into the cyclone 2a sequentially flows into the cyclone 2b, the cyclone 2c, and the cyclone 2d, moves upward in the preheater 2, and is discharged from the uppermost cyclone 2d. The temperature of the exhaust gas at that time is usually around 400 ° C.
The exhaust gas in the preheater comes into contact with the supplied raw material to preheat the raw material. At that time, halogen such as bromine contained in the exhaust gas is adsorbed by the supplied raw material and recirculated in the preheater 2.
Some halogens such as bromine contained in the exhaust gas are discharged from the preheater 2 in a state of being contained in the exhaust gas.

The exhaust gas discharged from the preheater 2 (the uppermost cyclone 2d) is introduced into the sedimentation chamber 4, but the sedimentation chamber 4 is not an essential device and can be arbitrarily provided.
By introducing the exhaust gas into the settling chamber 4, the dust contained in the exhaust gas discharged from the preheater 2 can be settled and recovered.
Preferably, the collected dust or the like is introduced into the raw material mixing / feeding device 10 (indicated by “a” in FIG. 2) when the raw material crushing device such as the raw material mill is on (operating). When the raw material crushing apparatus such as a raw material mill is turned off (not in operation), it is mixed with a fresh raw material and introduced into a preheater. 2 (indicated by “b” in FIG. 2), but is preferably stored in the dust storage tank 12 first.

Next, the flow of the exhaust gas discharged from the sedimentation chamber 4 differs when the raw material crusher 6 is on and off.
When the raw material crushing device 6 is on, the exhaust gas passes through a stabilizer 5 provided as necessary, and is then introduced into the raw material crushing device 6. Also, when the raw material crushing device 6 is off, it is necessary. After passing through the stabilizer 5 provided according to the above, it is introduced into the dust collector 8.
By introducing the exhaust gas into the stabilizer, the dust contained in the exhaust gas can be settled and recovered.
Even if the stabilizer 5 is provided separately in two systems when the raw material crushing device 6 such as the raw material mill is on and when the raw material mill 6 is off, the stabilizer 5 is shared when the raw material mill 6 is on and off. Alternatively, it may be provided only when the raw material mill is off or in any case.
Preferably, the collected dust or the like is introduced into the raw material mixing / feeding device 10 (indicated by “a” in FIG. 2) when the raw material crushing device such as the raw material mill is on (operating). When the raw material crushing apparatus such as a raw material mill is turned off (not in operation), it is mixed with a fresh raw material and introduced into a preheater. 2 (indicated by “b” in FIG. 2), but is preferably stored in the dust storage tank 12 first.

First, the case where the raw material crusher 6 is turned on will be described. In FIG. 2, the flow indicated by the white arrow is the flow of the exhaust gas when the raw material crusher 6 is on.
The exhaust gas discharged from the settling chamber 4 is introduced into a slabilizer 5 provided as necessary, introduced into the raw material pulverizer 6, and used for drying the raw material in the raw material pulverizer 6. Here, the raw material crushing device 6 includes a raw material mill and / or a raw material dryer and / or an impact dryer.

Most of halogens such as bromine in the exhaust gas are collected by the raw material crushing device 6 such as a raw material mill (50 to 80%). Therefore, a dust collector 8 and a bag filter 9 installed on the downstream side of the raw material crushing device 6. The amount of bromine contained in the dust collected in step # 1 is drastically reduced as shown in Table 1 below, compared to when the raw powder crusher 6 is off.
Dust collected by the settling chamber 4 and the stabilizer 5 installed on the upstream side of the raw material pulverizer 6 is not affected by the case where the raw material pulverizer 6 is ON or OFF, but the amount of the dust is treated with the exhaust gas treatment. 10-30% of the total amount of dust recovered in the system, which affects the amount of desalting, but when removing a large amount of halogen such as bromine, the absolute amount is insufficient, and dust collector dust 8 In addition, it is necessary to perform desalting treatment including the bag filter dust 9.
In this case, it is more efficient to perform the desalting operation with the raw material crusher 6 turned off because the concentration of halogen such as bromine in the dust is high.

  When the raw material crusher 6 is off, the flow indicated by the black arrow in FIG. 1 is the flow of exhaust gas. When the raw material crusher 6 is off, the exhaust gas that has passed through the stabilizer 5 is introduced into the dust collector 8.

That is, exhaust gas that has passed through the raw material pulverizer 6 when the raw material pulverizer 6 is on and the stabilizer 5 when the raw material pulverizer 6 is off is introduced into the dust collector 8. As the dust collector 8, an electric dust collector is usually used, but other dust collectors (for example, a gravity dust collector, an inertial dust collector, a centrifugal dust collector, a filtration dust collector, etc.) may be used.
In addition, a plurality of dust collectors 8 may be installed, and a plurality of electric fields may be provided.
Preferably, the dust collected by the dust collector 8 is introduced into the raw material mixing / feeding device 10 (“a” in FIG. 2) when a raw material crushing device such as a raw material mill is on (operating). When the raw material crushing apparatus such as a raw material mill is turned off (not operating), it is mixed with fresh raw materials and reused after being introduced into the preheater. Although introduced into the slurrying device 13 (indicated by “b” in FIG. 2), it is preferably stored in the dust storage tank 12 first.

The exhaust gas discharged from the dust collector 8 is introduced into the bag filter 9 to capture finer dust and the like.
Preferably, dust or the like collected by the bag filter 9 is introduced into the raw material mixing / feeding device 10 when a raw material crushing device such as a raw material mill is on (operating) (see “a” in FIG. 2). )), Mixed with fresh raw material, introduced into a preheater and reused. On the other hand, when a raw material crusher such as a raw material mill is off (not operating), the recovered dust and the like are Although introduced into the dust slurrying device 13 (indicated by “b” in FIG. 2), it is preferably stored in the dust storage tank 12 first.
The exhaust gas that has passed through the bag filter 9 is released from the chimney 11 into the atmosphere.

  In the present invention, the objects of desalination treatment are settling chamber dust 4, stabilizer dust 5, dust collector dust 8, and bag filter dust 9, and the settling chamber dust 4, stabilizer dust 5, dust collector dust described above. 8 Table 1 shows the bromine concentration of dust in the bag filter dust 9. Table 1 shows both the case where the raw material mill which is the raw material crusher 6 is operating (ON) and the case where it is stopped (OFF). In the sedimentation chamber 4, the particles are gravity settled by slowing the gas flow rate, and relatively large particle dust is captured. In the stabilizer 5, the gas flow rate is slowed down in the apparatus and the gas flow direction is changed. Since particles are captured by inertia, relatively large particles are captured. In addition, since halide (bromine) is discharged from the preheater in the form of powder, and halide (bromine) is expected to be fine powder, supplementing fine particles with a dust collector, bag filter, etc. It is thought that the supplement of bromine increases.

  In the present invention, the amount of dust to be desalted can be appropriately determined in consideration of the amount of bromine brought into the cement production facility of the cement raw fuel. The dust to be desalted is dust collected from at least one of the settling chamber dust 4, the stabilizer dust 5, the dust collector dust 8, and the bag filter dust 9. Depending on the amount of desalting, Some may be processed. The bromine removal effect is maximized when the total amount of sedimentation chamber dust 4, stabilizer dust 5, dust collector dust 8, and bag filter dust 9 is desalted.

  From Table 1 above, the concentration of bromine in the dust is larger in the dust collector dust 8 and the bag filter dust 9 than in the settling chamber dust 4 and the stabilizer dust 5, and therefore the dust collector dust 8 regardless of whether the raw material crusher 6 is on or off. The bag filter dust 9 is processed efficiently because the amount of dust processing can be reduced. In particular, by desalting the dust collected when the raw material crushing device 6 is off, the desalting treatment can be effectively performed, and the halogen concentration circulating and concentrating in the cement manufacturing facility can be reduced.

The dust collector 8 may be provided with a plurality of electric fields (for example, a first electric field, a second electric field, and a third electric field), and the bromine concentration of dust recovered from each electric field in this case is shown. Table 1 shows both the case where the raw material mill which is the raw material crusher 6 is operating (ON) and the case where it is stopped (OFF).
The merged dust refers to dust collected from all electric fields of the first electric field, the second electric field, and the third electric field.

  From Table 2 above, when the raw material mill 6 is off and the dust collector 8 is provided with a plurality of electric fields (for example, a first electric field, a second electric field, and a third electric field), the exhaust gas It can be seen that it is more effective to treat the dust collected in the electric field (third electric field) arranged at least on the most downstream side of the flow because bromine is concentrated.

A method for recovering halogen such as bromine contained from the dust stored in the dust storage tank 12 will be described.
As a recovery method, water is added to the dust, and a slurry is formed by the slurrying device 13.
Preferably, about 4 to 20 mass of water is added to the mass 1 of the dust to form a slurry, which is sufficiently stirred to dissolve soluble bromine (halogen) in the dust in water.
As water, secondary water discharged from tap water, industrial water, cement manufacturing process, or the like can be used. Moreover, in order to raise solubility, you may raise the temperature of the slurrying apparatus 13 to 40 degreeC or more, for example.
As the slurrying device 13, any known slurrying device can be used.

  Next, the obtained slurry solution is sent to a solid-liquid separator 14 such as a dehydrator and pressed to perform solid-liquid separation to separate the dehydrated cake and the filtrate. As the solid-liquid separation device 14, any known device such as a commercially available dehydration device, filter press, centrifugal dehydrator, screw press, etc. can be used, and the water content of the dehydrated cake, which is a solid content, is based on mass. It dehydrates so that it may become 50 mass% or less, Preferably it is 40 mass% or less.

  The dehydrated cake is dried by the drying device 15 and then introduced into the raw material mixing / feeding system device 10, mixed with the raw material introduced from the raw material crushing device 6, and circulated and supplied to the cyclone 2d above the preheater as a cement production raw material. Is done.

The useful metal is recovered from the filtrate after the dehydration by a useful metal recovery device.
The filtrate after the dehydration treatment may contain useful metals, and it is desirable to recover these for effective use.
The recovery method of useful metals is not particularly limited, and any known recovery method and recovery device 16 can be applied. For example, a pH adjuster is added, and a polymer flocculant or a chelating agent is added. Then, the useful metal is precipitated and collected by solid-liquid separation using the filtration device 16. Moreover, you may provide an electrolysis process as needed. The useful metal recovered in this way is used for reuse.

After removing the useful metals, the filtrate is treated by the waste water treatment device 17 until it satisfies the release standards stipulated in the Water Pollution Control Law, Sewerage Law, etc., for example, water treatment, and then discharged to public water areas or sewers. To do.
Further, if necessary, a fine filtration step may be provided to remove fine suspended solids and then discharge them.

Such dust desalination treatment effectively releases halogen such as bromine from the cement facility to the outside of the cement production system, and can effectively reduce the concentration and amount of halogen such as bromine that is circulated and concentrated in the cement facility. It becomes possible.
In particular, only when the raw material crushing apparatus such as a raw material mill is not in operation, the amount of halogen to be circulated can be rapidly reduced by carrying out the dust desalting process of the present invention. It is an extremely excellent halogen reduction device and reduction method that can reduce the running cost by making the operation of the reduction device intermittent. For example, if the desalination treatment apparatus is operated for about 9 hours / day when the raw material crushing apparatus such as the raw material mill is stopped, the amount of circulating halogen can be drastically reduced, and the operation time of the desalination treatment apparatus can be reduced. It can be reduced to 9/24.
Therefore, it is possible to ensure the stability of operation in the cement facility.

(Examples 1-2, Comparative Examples 1-2)
In the embodiment, the raw material mixing / feeding device when dust is collected from the dust collector using the cement manufacturing facility provided with the halogen reduction device shown in FIG. 2 and in the comparative example using the cement manufacturing facility shown in FIG. The bromine concentration in the (storage silo) was measured and expressed as a change with the operating time of the cement production facility.

However, it implemented on the conditions shown in following Table 3.
In Examples 1 and 2, the dust from the dust collector (combined dust) is treated with the amount of treatment shown in Table 3 below for the dust desalination treatment of the present invention only during 9 hours / 1 day when the raw material mill is off. It applied and processed so that the desalination rate from the dust collect | recovered from the dust collector 8 might be 70 mass%.
Other conditions were the same in all examples and comparative examples.

The results are shown in FIGS.
FIG. 3 shows the results of measurement of the bromine concentration in the raw material mixing / feeding device (storage silo) in Comparative Example 1, FIG. 4 in Example 1, FIG. 5 in Comparative Example 2, and FIG. Weekly measurements from the day)).
FIG. 3 shows that in Comparative Example 1, the bromine concentration of the raw material mixing / feeding device (storage silo) is changing at about 365 ppm.
On the other hand, FIG. 4 shows that when the method of the present invention is applied, the bromine concentration of the raw material mixing / feeding device (storage silo) is reduced from the initial 365 ppm to about 250 ppm.

Further, FIG. 5 shows that the bromine concentration in the raw material mixing / feeding device (storage silo) when the amount of raw material containing bromine is doubled is increased from 365 ppm to about 640 ppm.
On the other hand, as shown in FIG. 6, when the method of the present invention is applied, the bromine concentration of the raw material mixing / feeding device (storage silo) is reduced from the initial 365 ppm to about 325 ppm and is kept in the raw material. It is clear that the increase in the amount of bromine contained is reduced by the method of the present invention.

  The method and apparatus for reducing halogen from a cement production facility according to the present invention can be effectively applied to a cement production facility that uses waste as a raw material.

DESCRIPTION OF SYMBOLS 1 ... Rotary kiln 2 ... Preheater 3 ... Calciner 4 ... Sedimentation chamber 5 ... Stabilizer 6 ... Raw material crusher 7 ... Air quench cooler (AQC)
8 ... Dust collector 9 ... Bag filter 10 ... Raw material mixing / feeding device 11, 22 ... Chimney 12 ... Dust storage tank 13 ... Dust slurrying device 14 ... Solid-liquid separation device DESCRIPTION OF SYMBOLS 15 ... Drying apparatus 16 ... Useful metal collection | recovery apparatus 17 ... Waste water treatment apparatus 18 ... Cement clinker 19, 20 ... AQC type sedimentation chamber 21 ... AQC type dust collector X ... Cement manufacture Facility

Claims (16)

  In a cement production facility, the dust recovered from the exhaust gas before the combustion exhaust gas generated in the rotary kiln for firing the cement raw material is released into the outside air is slurried, then dehydrated and solid-liquid separated, and obtained. The halogen from the cement production facility is characterized by removing halogen contained in the cement production facility by treating the filtrate with waste water, and the solid content obtained by the solid-liquid separation is mixed with the raw material and reused. Reduction method.   The method for reducing halogen from a cement production facility according to claim 1, wherein the dust is recovered from at least one location selected from the group consisting of a sedimentation chamber, a stabilizer, a dust collector, and a bag filter. How to reduce halogen from equipment.   The method for reducing halogen from a cement production facility according to claim 2, wherein the dust collector is provided with a plurality of electric fields, and the dust is collected from at least the most downstream electric field of the exhaust gas flow. Halogen reduction method from cement production facilities.   4. The method for reducing halogen from a cement production facility according to claim 1, wherein after recovering useful metals from the filtrate obtained by the solid-liquid separation, the halogen is removed from the cement production facility by treating with waste water. A method for reducing halogen from a cement production facility.   In the method for reducing halogen from the cement production facility according to claims 1 to 4, after the solid content obtained by the solid-liquid separation is dried, the dried solid content is mixed with the raw material, and then introduced into the preheater. A method for reducing halogen from a cement manufacturing facility, characterized by being reused.   The method for reducing halogen from a cement production facility according to any one of claims 1 to 5, wherein the method for reducing halogen from a cement production facility is performed when a cement raw material crushing device included in the cement production facility is stopped. Reduction method of halogen.   7. The method for reducing halogen from a cement production facility according to claim 6, wherein when the cement raw material crusher is in operation, the exhaust gas generated until the combustion exhaust gas generated in the rotary kiln for cement raw material firing is released into the outside air. A method for reducing halogen from a cement manufacturing facility, wherein the dust recovered from the mixture is mixed with a raw material, and then introduced into a preheater and circulated.   The method for reducing halogen from a cement production facility according to claim 1, wherein the halogen is bromine.   A raw material calciner equipped with a rotary kiln for cement raw material firing and a preheater, a slurrying device for dust recovered from exhaust gas discharged from the raw material calciner, a solid-liquid separator for dehydrating the slurry, and obtained by the solid-liquid separation An apparatus for reducing halogen from a cement production facility, comprising: a wastewater treatment apparatus for a filtrate; and a raw material mixing / feeding apparatus for mixing the solid content obtained by the solid-liquid separation with the raw material.   The apparatus for reducing halogen from a cement production facility according to claim 9, comprising a sedimentation chamber, a stabilizer, a dust collector and a bag filter for collecting dust from the exhaust gas. .   The apparatus for reducing halogen from a cement production facility according to claim 10, wherein the dust collector is provided with a plurality of electric fields.   The apparatus for reducing halogen from a cement production facility according to any one of claims 7 to 11, further comprising a useful metal from the filtrate obtained by the solid-liquid separation between the solid-liquid separation device and the wastewater treatment device. A device for reducing halogen from a cement production facility, characterized in that a useful metal recovery device for recovering slag is provided.   The apparatus for reducing halogen from a cement production facility according to any one of claims 7 to 12, wherein the solid content obtained by the solid-liquid separation is further dried between the solid-liquid separation device and the raw material mixing / feeding device. An apparatus for reducing halogen from a cement production facility, characterized in that a drying apparatus is provided.   The apparatus for reducing halogen from a cement production facility according to any one of claims 7 to 13 is operated when the cement raw material crushing device included in the cement production facility is stopped. Halogen reduction device.   The halogen reduction apparatus from the cement production facility according to claim 14, wherein when the cement raw material pulverizing apparatus is in operation, the combustion exhaust gas generated in the rotary kiln for cement raw material firing is discharged from the exhaust gas until it is released into the outside air. From the cement production facility, the collected dust is introduced into the raw material mixing / feeding device and mixed with the raw material, and the raw material mixing / feeding device and the preheater are installed so as to be introduced into the preheater. Halogen reduction device.   16. The apparatus for reducing halogen from a cement production facility according to claim 7, wherein the halogen is bromine.

Images