JP2012062208A - Method for treating exhaust gas from cement manufacturing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating exhaust gas from cement manufacturing equipment by which, when an unburned carbon-containing material such as coal ash is used as part of a clinker raw material, the content of unburned carbon in collected dust collected from exhaust gas from the cement manufacturing equipment can simply be reduced at low cost, accordingly the amount of collected dust added to clinker is increased, the amount of collected dust returned to the cement manufacturing equipment is reduced, and the concentration of mercury in exhaust gas discharged to the outside can be reduced.SOLUTION: The method for treating exhaust gas includes: a step where the content of unburned carbon in collected dust collected from exhaust gas by a dust collector 8 is measured, and on the basis of the content, whether or not a part of the collected dust is to be supplied to a high temperature region of a preheater at ≥700°C (e.g., a duct between cyclones 3c, 3d) is determined; and a step where at least a part of the collected dust except dust supplied to the high temperature region is introduced into a finishing mill 7 and added to clinker.

Description

  The present invention relates to a method for treating exhaust gas in a cement production apparatus, and more particularly, a method for treating exhaust gas generated in a cement production apparatus that burns clinker using an unburned carbon-containing substance such as coal ash as part of a clinker raw material About.

In recent years, wastes such as incineration ash, sludge, coal ash, and blast furnace secondary ash are increasingly used as clinker raw materials. And the unburned carbon, heavy metal, etc. are contained in the exhaust gas of the cement manufacturing apparatus using these wastes. Among these, various techniques for removing heavy metals (for example, mercury) from exhaust gas have been developed.
For example, dust is collected from the exhaust gas of the cement manufacturing process, and the collected dust dust is discharged into the clinker pulverization process after cement firing or discharged into the clinker pulverized product. A method for treating cement production exhaust gas characterized by reducing the concentration of volatile metal components (for example, mercury) therein has been proposed (Patent Document 1).
This time, when this inventor examined this processing method, the following thing was found. When this treatment method is carried out using clinker raw material with a large amount of unburned carbon, the dust collection dust contains unburned carbon, so if the amount of dust collection dust added to the clinker is increased, it will be included in the cement. Increases the amount of unburned carbon. When concrete is prepared using cement containing a large amount of unburned carbon, a phenomenon may occur in which unburned carbon floats up in the concrete depending on the formulation. If a large amount of this concrete is cast, the upper surface of the concrete frame is formed by a layer containing a large amount of unburned carbon, and the aesthetic appearance of the concrete frame is impaired, or the joint surface is formed by a layer containing a lot of unburned carbon. (Joint surface) may be formed, which may cause a decrease in strength and a decrease in durability on the joint surface.

In order to improve this problem, it is necessary to remove unburned carbon from the dust collection dust before it is added to the clinker.
As a technique for removing unburned carbon, for example, a hydrophobizing step of hydrophobizing unburnt coal (unburned carbon) by adding a collecting agent to a water slurry of coal ash, and a foaming agent in the water slurry. In the method for treating coal ash comprising the flotation step of adding bubbles to generate bubbles and attaching the unburned coal to the bubbles to float, an anion collector is used as a collector. A method for treating coal ash has been proposed (Patent Document 2).
Although the method using this scavenger is excellent in that unburned carbon can be separated with high accuracy, the treatment process is complicated, wastewater treatment is required, and there are problems such as high cost, Actually, it is difficult to apply to dust collection dust collected from exhaust gas of a cement manufacturing apparatus.
On the other hand, dioxins may be contained in the exhaust gas of a cement manufacturing apparatus that uses waste. As a technique for decomposing and detoxifying these dioxins, for example, dust is collected from exhaust gas using a dust collector, and the collected dust is collected in a high temperature region of a cement manufacturing apparatus (for example, 800 ° C. such as a rotary kiln). It is known to put in the above high temperature region (Patent Documents 3 to 4).

JP 2002-284550 A JP 2003-266057 A JP 2004-244308 A JP 2008-174446 A

As described above, separating unburned carbon from the dust collected from the exhaust gas of the cement manufacturing apparatus is difficult to put into practical use due to a complicated processing step. And when not separating unburned carbon from the dust collection dust, as described in the above-mentioned Patent Document 1, to the clinker for the purpose of reducing the concentration of mercury in the exhaust gas discharged to the outside. Even when dust collection dust is introduced, the above-mentioned problems such as deterioration of the appearance of the concrete frame may occur due to the unburned carbon contained in the cement.
Therefore, the present invention, when using an unburned carbon-containing substance such as coal ash as a part of the clinker raw material, the content of unburned carbon in the dust collection dust collected from the exhaust gas of the cement manufacturing apparatus, Emissions that can be reduced easily and at low cost, resulting in an increase in the amount of dust collection dust added to the clinker and a reduction in the amount of dust collection dust returned to the cement manufacturing equipment. It aims at providing the processing method of the waste gas of the cement manufacturing apparatus which can reduce the density | concentration of mercury in the inside.

  The inventor measures the content of unburned carbon in the dust collected from the exhaust gas of the cement manufacturing apparatus, and based on the measurement result, the dust collected to the high temperature region of 700 ° C. or higher of the preheater. If the necessity of input is determined, the content of unburned carbon in the dust collection dust can always be kept low. As a result, the amount of dust collection dust added to the clinker is increased and returned to the cement production equipment. The present inventors have found that the amount of dust collection dust can be reduced to reduce the concentration of mercury in the exhaust gas discharged to the outside.

That is, the present invention provides the following [1] to [4].
[1] A method for treating exhaust gas of a cement manufacturing apparatus using a clinker raw material containing an unburned carbon-containing material, wherein the content of unburned carbon in dust collection dust collected from the exhaust gas is measured, and the content rate Based on the above, unburned carbon amount measurement for determining whether or not a part of the dust collection dust is supplied as high temperature region return dust to a high temperature region of 700 ° C. or higher of the preheater which is a constituent part of the cement manufacturing apparatus And a clinker addition step of adding at least a part of the dust collection dust other than the high-temperature region return dust as a clinker addition dust to the clinker. .
[2] The cement manufacturing apparatus according to [1], including a high temperature region supply step of supplying the high temperature region return dust to the high temperature region of 700 ° C or higher based on the determination in the unburned carbon amount measurement step. Waste gas treatment method.
[3] Low temperature region supply step of supplying dust collection dust other than the high temperature region return dust and clinker addition dust to a low temperature region of less than 700 ° C. of the preheater or a point on the raw material supply side with respect to the preheater. The method for treating exhaust gas of a cement production apparatus according to the above [1] or [2].
[4] The material according to any one of [1] to [3], wherein the unburned carbon-containing material includes one or more selected from the group consisting of coal ash, blast furnace secondary ash, and fluidized bed boiler ash. A method for treating exhaust gas from a cement manufacturing apparatus.

  According to the exhaust gas treatment method of the present invention, the content of unburned carbon in dust collection dust can be reduced easily and at low cost. As a result, the amount of dust collection dust added to the clinker can be increased and the amount of dust collection dust returned to the cement production equipment can be reduced, reducing the amount of mercury circulating in the cement production equipment, It is possible to reduce the concentration of mercury in the exhaust gas that is released.

It is a figure which shows an example of the processing system for enforcing the processing method of the waste gas of the cement manufacturing apparatus of this invention.

An example of the method for treating exhaust gas of the cement production apparatus of the present invention is as follows. (A) The content of unburned carbon in the dust collected from the exhaust gas of the cement production apparatus is measured, and based on the content, the above collection An unburned carbon amount measuring step for determining whether or not a part of the dust dust is supplied as a high temperature region return dust to a high temperature region of 700 ° C. or higher of the preheater which is a constituent part of the cement manufacturing apparatus; ) Based on the determination in the unburned carbon amount measuring step, a high temperature region supplying step of supplying the high temperature region return dust to the high temperature region of 700 ° C. or higher, and (C) dust collection dust other than the high temperature region return dust. A clinker addition step of adding to the clinker as at least a part of the clinker addition dust, and (D) dust collection dust other than the high temperature region return dust and the clinker addition dust, Area of less than 700 ° C. of Rehita or includes a low-temperature region supplying step, supplying a point of the raw material supply side of the preheater.
Among these, the step (A) and the step (C) are essential steps in the present invention. Step (B) and step (D) are optional steps that can be included as necessary.
Hereinafter, each process will be described in detail.

[Process (A): Unburnt carbon content measurement process]
In step (A), the content of unburned carbon in the collected dust collected from the exhaust gas of the cement manufacturing apparatus is measured, and a part of the collected dust is removed from the cement manufacturing apparatus based on the content. It is a step of determining whether or not to supply the high-temperature region return dust to the high-temperature region of 700 ° C. or higher of the preheater as the constituent part.
In the present invention, as a clinker raw material, an unburned carbon-containing substance such as coal ash, blast furnace secondary ash, fluidized bed boiler ash, and the like are used together with a normal clinker raw material (for example, a raw material for ordinary Portland cement clinker). Moreover, you may use other wastes (usually including heavy metals, such as mercury), such as incineration ash and sludge, for a part of clinker raw material.
Examples of the dust collecting means for collecting dust from exhaust gas and obtaining dust collection dust include an electric dust collector and a bag filter. Two or more kinds of dust collecting means can be used in combination. For example, an electric dust collector and a bag filter may be provided in series, and the exhaust gas after being processed by the electric dust collector may be further processed by the bag filter.
The amount of unburned carbon in the dust collection dust can be obtained, for example, by the following procedures 1) to 3).
1) Dust collection dust and hydrochloric acid are mixed and heated at 100 ° C for 1 hour to remove inorganic carbon, then the total amount of carbon in the insoluble residue (total amount of unburned carbon including oil) is high-frequency heated red Measured by external absorption method.
2) The same sample as the sample (dust collection dust) analyzed in 1) above was dried separately at 105 ° C for 20 hours, and heat-depressurized at 250 ° C and 50 mtorr to reduce the weight. The rate is measured, and the amount corresponding to this weight reduction rate is defined as the amount of oil.
3) The amount of unburnt carbon obtained by subtracting the amount of oil obtained in 2) from the total amount of carbon obtained in 1) above (total amount of unburned carbon including oil).
In consideration of various conditions such as the amount of unburned carbon-containing substances such as coal ash used as the clinker raw material, and measurement data of the amount of unburned carbon obtained when the present invention was implemented in the past, When the amount of unburned carbon in the dust dust can be predicted almost accurately, the value of the amount of unburned carbon can be obtained as a predicted value instead of actual measurement. This case also corresponds to the step (A).
The content of unburned carbon in the dust collection dust, which is a reference value for determining whether or not a part of the dust collection dust is supplied to the high temperature region of 700 ° C. or higher of the preheater, is not particularly limited and should be arbitrarily determined. For example, a value determined between 0.8 and 1.5% by mass can be adopted. For example, when the reference value is set to 1.0% by mass, if the unburned carbon content is 1.0% by mass or more, a part of the dust collection dust is supplied to the high temperature region of 700 ° C. or more of the preheater. If the unburned carbon content is less than 1.0% by mass, the dust collection dust can be determined not to be supplied to the high temperature region of 700 ° C. or higher of the preheater.

[Step (B); High temperature region supply step]
A process (B) is a process of supplying the said high temperature area | region return dust to the 700 degreeC or more high temperature area | region of a preheater based on the determination in a process (A) (unburned carbon amount measurement process).
In the present specification, the preheater is a facility for preheating the clinker raw material to be supplied to the rotary kiln. The preheater includes a plurality of cyclones, a kiln bottom, a calcining furnace provided as necessary, and these components (a cyclone, a kiln). It is defined as including a pipe line for connecting a bottom portion and a calcining furnace). The kiln bottom is the part of the preheater closest to the rotary kiln.
The charging place is preferably a high temperature region in the preheater. The temperature at the charging place is 700 ° C. or higher, preferably 750 ° C. or higher, more preferably 800 ° C. or higher.
The components of the preheater that should be used as the charging place are the kiln bottom, the bottom cyclone, the second cyclone from the bottom, the third cyclone from the bottom, the calciner, and the pipes for connecting them. Preferably, the bottom of the kiln, the lowermost cyclone, the second cyclone from the bottom, the calcining furnace, and a pipe line for connecting them.
In addition, the calcining furnace which is a charging place includes a cooler bleed duct connected to the calcining furnace in addition to the calcining furnace main body.
When dust collection dust is not put into the preheater at a high temperature region of 700 ° C or higher, but is put into a point on the raw material supply side (in other words, above), the unburned carbon in the dust collection dust is burned. However, it is difficult to sufficiently reduce the content of unburned carbon in the dust collection dust. In addition, dust collection dust may be put directly into the rotary kiln without being put into the high temperature region of 700 ° C or higher of the preheater, but if it is put into a place near the kiln (place near the clinker outlet), the clinker mineral In the present invention, the rotary kiln is removed from the charging place because the generation may be insufficient and the quality of the clinker may deteriorate.

[Step (C); Clinker addition step]
In the step (C), at least a part of the dust collection dust other than the dust collection dust (high temperature region return dust) that is put into the high temperature region of the preheater in the step (B) is added to the clinker as clinker addition dust. It is a process.
The usage form of dust collection dust (clinker addition dust) in step (C) is as follows: (a) Clinker, gypsum and dust collection dust are mixed and pulverized to obtain cement; (b) Clinker and gypsum After mixing and pulverizing, the obtained pulverized product and dust collection dust are mixed to obtain a cement. (C) The clinker and gypsum are mixed and pulverized, and then the obtained pulverized product (cement) is used. The usage form etc. which mix dust collection dust, water, etc., and obtain a cement hardening body (paste, mortar, or concrete), etc. are mentioned. The usage forms of (b) and (c) also correspond to “addition to clinker as clinker addition dust” in the present invention.
Especially, the usage form of said (a) is preferable from the viewpoint of management of the usage-amount of the dust for clinker addition, and the quality of cement.
The clinker used in the usage forms such as the above (a) to (c) may be a clinker obtained in a cement manufacturing apparatus (see steps (A) and (B)) used in the present invention, or in the present invention. A clinker obtained by a cement manufacturing apparatus other than the cement manufacturing apparatus to be used may be used.
The amount of dust collection dust (clinker addition dust) used in the step (C) varies depending on the unburned carbon content in the dust collection dust, but is preferably 5 parts by mass or less with respect to 100 parts by mass of the clinker. More preferably, it is 3 parts by mass or less, and particularly preferably 2 parts by mass or less. If the amount exceeds 5 parts by mass, the concentration of unburned carbon in the cement composition such as concrete increases even if the content of unburned carbon in the dust collection dust is relatively small. There is a risk of problems such as deterioration of the appearance of the.
The lower limit value of the amount of dust collection dust (clinker addition dust) used in the step (C) is not particularly limited, but the amount of dust collection dust returned to the cement manufacturing apparatus increases as the amount of dust addition dust increases. In view of the fact that the mercury concentration in the exhaust gas discharged to the outside is reduced, the amount is preferably 0.3 parts by weight, more preferably 0.5 parts by weight, particularly preferably 100 parts by weight of the clinker. 0.8 parts by mass.
In addition, in the step (C), when all of the dust collection dust other than the dust collection dust supplied to the high temperature region of the preheater is used as the clinker addition dust, the step (D) (low temperature region supply step) described below is performed. It becomes unnecessary.

[Step (D); Low temperature region supply step]
Step (D) is a step of supplying dust collection dust other than high temperature region return dust and clinker addition dust to a low temperature region below 700 ° C. of the preheater or a point on the raw material supply side with respect to the preheater.
As an area | region below 700 degreeC of a preheater, the uppermost cyclone is mentioned, for example.
The point on the raw material supply side with respect to the preheater is, for example, a raw material drying / pulverizing machine for clinker raw materials (specifically, limestone, clay, silica stone, iron slag, etc.), or between the raw material drying / pulverizing machine and the preheater. Raw material supply paths (including silos for storage) and the like.
In the step (D), for example, when the amount of dust collected by the dust collecting means is large, it is difficult to put the entire amount of dust collected into a high temperature region of 700 ° C. or higher of the preheater. It can be included in the processing method of the present invention.
The amount of dust collection dust to be supplied to the low temperature region of the preheater in the step (D) can be determined based on, for example, the unburned carbon content obtained in the step (A). For example, when the content of unburned carbon obtained in the step (A) is relatively large, it is desirable to reduce the amount of dust collection dust supplied in the step (D). Conversely, when the unburned carbon content obtained in step (A) is relatively small, the amount of dust collection dust supplied in step (D) can be increased.

Next, an example of a treatment system for carrying out the exhaust gas treatment method of the cement production apparatus of the present invention will be described.
In FIG. 1, first, clinker raw materials (for example, ordinary clinker raw materials such as limestone, clay, silica stone, and iron slag and unburned carbon-containing substances such as coal ash) are dried and pulverized by a raw material drying / pulverizer 1. Then, it is supplied to the suspension preheater 3 via the raw material supply path 2. The raw material dryer / pulverizer 1 may be divided into a raw material dryer and a pulverizer.
In addition, in FIG. 1, the flow of substances, such as a clinker raw material and dust collection dust, is shown as the continuous line, and the flow of exhaust gas is shown with the dotted line. Further, in the present specification, the preheater connects the cyclones 3a to 3d constituting the suspension preheater 3, the calcining furnace 4, the kiln bottom 6, and each of these components (cyclone, calcining furnace, kiln bottom). Includes pipelines.
The suspension preheater 3 is for preheating and decarboxylation of the clinker raw material, and is composed of a plurality of cyclones 3a to 3d and pipes connecting these cyclones.
The temperature in the lowermost cyclone 3d is usually 800 to 900 ° C. The temperature in the second cyclone 3c from the bottom is usually 700 to 850 ° C. The temperature in the third cyclone 3b from the bottom is usually 600 to 750 ° C. The temperature in the calcining furnace 4 is usually 800 to 1000 ° C.

In the suspension preheater 3, the clinker raw material is preheated while sequentially moving from the upper cyclone 3a to the lower cyclone 3b and the cyclone 3c. Supplied with.
As shown in FIG. 1, a calcining furnace 4 may be disposed between the suspension preheater 3 and the kiln bottom 6. The calcining furnace 4 is provided to promote decarboxylation of the clinker raw material. The calcining furnace 4 is provided as necessary, and is not an essential device.
The type of the calcining furnace 4 is not particularly limited. For example, the SF calcining furnace, the MFC calcining furnace, the RSP calcining furnace, the KSV calcining furnace, the DD calcining furnace, the SLC calcining furnace, etc. Can be used.
The clinker raw material introduced into the rotary kiln 5 is baked at a temperature of about 900 to 1500 ° C. to become a clinker. The clinker discharged from the rotary kiln 5 is mixed and finely pulverized in the finishing mill 7 with gypsum and a part of the dust collected by the electric dust collector 8 to become cement.

The exhaust gas generated when the clinker raw material is heated in the rotary kiln 5 or the like moves upward in the suspension preheater 3 and flows into the exhaust gas passage. Thereafter, the exhaust gas is led to the raw material drying / pulverizing machine 1 for use as a heat source, and then led to the electric dust collector 8 through the exhaust gas passage. After the dust is removed by the electric dust collector 8, the exhaust gas is discharged from the chimney 9 into the atmosphere via the exhaust gas path.
For example, as shown in FIG. 1, the dust collected by the electric dust collector 8 is connected to the raw material supply path 2 (for example, a storage silo), the lowest cyclone 3d, and the second cyclone 3c from the bottom. The exhaust gas distribution pipe line and the finishing mill 7 are supplied at a predetermined ratio.

The means for supplying the dust collection dust collected by the electric dust collector 8 to the raw material supply path 2 is, for example, a transport device for transporting the dust collection dust from the electric dust collector 8 to a storage tank (not shown). (Not shown), a storage tank for storing the dust collection dust, and an input device (not shown) for supplying the dust collection dust in the storage tank to the raw material supply path 2 at a predetermined supply speed. The
Here, as a transport apparatus, a screw conveyor, a bucket elevator, a trough chain conveyor, an aeration trough conveyor, etc. are mentioned, for example. These may be used alone or in combination of two or more. In addition, as for a transport apparatus, when transporting dust collection dust, what has high airtightness is preferable so that dust collection dust does not spread | diffuse and a working environment may be deteriorated.
Moreover, as an input device, what can adjust the input amount of dust collection dust is preferable, and a screw feeder, a belt feeder, a rotary feeder, a wing auto feeder, a circle feeder, constant feedware etc. are mentioned specifically ,.
The means for supplying the dust collection dust to the exhaust gas distribution pipe and the means for supplying the dust collection dust to the finishing mill 7 are the same as the above-described means for supplying the raw material supply path 2. In the present specification, the cement production apparatus includes, for example, a raw material drying / pulverizing machine 1, a raw material supply path 2, a suspension preheater 3, a calcining furnace 4, a rotary kiln 5, and a kiln bottom 6. , Including a finishing mill 7 and an electrostatic precipitator 8.

[Example 1]
A clinker raw material consisting of 100 parts by weight of ordinary Portland cement clinker and 6.3 parts by weight of coal ash is supplied to the cement manufacturing apparatus shown in FIG. 1 to burn the clinker and discharge the generated exhaust gas to the electrostatic precipitator 8. To obtain dust collection dust and exhaust gas after treatment. At the initial stage, the entire amount of dust collection dust was guided to the raw material supply path 2. Seven days after starting the supply of the clinker raw material containing coal ash, the content of unburned carbon in the dust collection dust was measured to be 2.3% by mass. This value is a value obtained by subtracting the measured value of the oil from the measured value of the total amount of unburned carbon including the oil (in other words, the amount of unburned carbon as solid carbon not including the oil).
Next, 100 parts by mass of clinker, 3 parts by mass of gypsum, and 0.8 parts by mass of dust collection dust were mixed and pulverized to obtain cement. After 100 parts by mass of cement, 40 parts by mass of water, 0.7 parts by mass of a high-performance AE water reducing agent, and 250 parts by mass of sand were prepared to prepare a mortar, using this mortar, Produced. When the upper surface of the mortar molded body was observed, the upper surface was formed by a layer containing a lot of unburned carbon, and the appearance of the upper surface was inferior.
Next, instead of the raw material supply path 2, the total amount of dust collection dust was led to a pipe line (temperature: 800 to 850 ° C.) between the cyclones 3c and 3d shown in FIG. Seven days after the change, the content of unburned carbon in the dust collection dust was measured and found to be 1.2% by mass. Using this dust collection dust, a mortar molded body was prepared in the same manner as described above (amount of dust collection dust per 100 parts by mass of clinker: 0.8 part by mass), and the top surface was observed. Met.

[Example 2]
The clinker was fired in the same manner as in Example 1 except that the blending amount of coal ash was changed to 3.2 parts by mass. At the initial stage, the entire amount of dust collection dust was guided to the raw material supply path 2. Seven days after starting the supply of the clinker raw material, the content of unburned carbon in the dust collection dust was measured and found to be 1.0% by mass. A mortar compact was produced in the same manner as in Example 1 except that the amount of dust collection dust per 100 parts by mass of the clinker was changed to 1.5 parts by mass, and the top surface was inferior when observed. .
Next, 50% by mass of the dust collection dust was introduced to the raw material supply path 2, and the remaining 50% by mass of the dust collection dust was introduced to the pipe line between the cyclones 3c and 3d shown in FIG. Seven days after the change, the content of unburned carbon in the dust collection dust was measured and found to be 0.7% by mass. Using this dust collection dust, a mortar molded body was prepared in the same manner as described above (amount of dust collection dust per 100 parts by mass of clinker: 1.5 parts by mass), and the top surface was observed. Met.
Next, the entire amount of dust collection dust was guided to the pipe line between the cyclones 3c and 3d shown in FIG. Seven days after the change, the content of unburned carbon in the dust collection dust was measured and found to be 0.5% by mass. Using this dust collection dust, the same as described above (the amount of dust collection dust per 100 parts by mass of clinker: 1.5 parts by mass) to produce a mortar compact, and when the upper surface was observed, the appearance of the upper surface was It was very good. Therefore, a mortar molded body was prepared in the same manner as described above except that the amount of dust collected per 100 parts by mass of the clinker was changed to 2.0 parts by mass, and the top surface was observed. It was.

DESCRIPTION OF SYMBOLS 1 Raw material drying and grinding machine 2 Raw material supply path 3 Suspension preheater 3a-3d Cyclone 4 Calciner 5 Rotary kiln 6 Kiln bottom 7 Finishing mill 8 Electric dust collector 9 Chimney

Claims (4)

A method for treating exhaust gas from a cement manufacturing apparatus using a clinker raw material containing an unburned carbon-containing substance,
The content rate of unburned carbon in the dust collection dust collected from the exhaust gas is measured, and based on the content rate, a part of the dust collection dust is 700 ° C. or higher of the preheater which is a constituent part of the cement manufacturing apparatus. An unburned carbon amount measuring step for determining whether to supply the high temperature region as dust for returning to the high temperature region,
A clinker addition step of adding at least a part of dust collection dust other than the high temperature region return dust to the clinker as clinker addition dust,
A method for treating exhaust gas of a cement manufacturing apparatus, comprising:   The exhaust gas treatment of a cement manufacturing apparatus according to claim 1, further comprising a high temperature region supplying step of supplying the high temperature region return dust to the high temperature region of 700 ° C or higher based on the determination in the unburned carbon amount measuring step. Method.   Including a low temperature region supply step of supplying dust collection dust other than the high temperature region return dust and clinker addition dust to a low temperature region of less than 700 ° C. of the preheater, or a point on the raw material supply side with respect to the preheater, The processing method of the waste gas of the cement manufacturing apparatus of Claim 1 or 2.   The cement-producing apparatus according to any one of claims 1 to 3, wherein the unburned carbon-containing material includes one or more selected from the group consisting of coal ash, blast furnace secondary ash, and fluidized bed boiler ash. Exhaust gas treatment method.

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