JP2002233732A - Waste smoke treating agent and method for producing cement by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a waste smoke treating agent which, when it becomes wastes, can be easily used as a cement material without carrying out a complicated calculation for proportioning raw materials and to provide a method for producing a cement by using the same as a part of the raw materials. SOLUTION: The waste smoke treating agent has a composition of 60-70 mass % CaO, 10-17 mass % SiO2, 1-5 mass % Al2O3, and 1-3 mass % Fe2O3. When the agent becomes a soot-containing one after it is used, it is washed with water and is then fed into a cement production process in the position where the temperature is in the range of 700-1,100 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a flue gas treating agent for purifying flue gas from a refuse incinerator or the like, and the use of the flue gas treating agent as a part of raw materials after the flue gas treatment. The present invention relates to a method for producing cement.

[0002]

2. Description of the Related Art A flue gas treatment agent is a chemical for removing harmful substances such as hydrogen chloride and sulfur oxides and harmful substances such as dioxins from flue gas generated by incineration of refuse. is there. Calcium hydroxide is often used as a main component of the flue gas treatment agent. Activated carbon for adsorbing dioxin and mercury is often added to this. Also, diatomaceous earth may be added in order to improve the filterability of flue gas with a garbage incinerator bag filter.

[0003] The flue gas treating agent is usually blown dry or wet into the flue of the flue gas, reacts with various harmful substances on the flue or the bag filter, and adsorbs and removes harmful substances from the flue gas. The flue gas treatment agent that has adsorbed harmful substances is collected by a bag filter or an electric dust collector, and is discharged from the refuse incineration process as used smoke treatment agent. The spent flue gas treatment agent generated in this way is interim disposed by methods such as solidification of cement, chemical treatment, acid washing or melting, and is then reclaimed at the final disposal site. Due to tightness, there is a demand for the reduction and volume reduction or recycling of used flue gas treatment agents.

[0004] On the other hand, the cement manufacturing process includes a process of firing the raw material at a high temperature, and the cement can be manufactured as long as the raw material supplied to the firing process has a predetermined chemical composition. Taking advantage of these characteristics, cement manufacturing has been actively used in recent years in order to contribute to waste treatment and to reduce the cost of cement manufacturing by using waste as a part of raw materials. Waste has been used as raw material for cement. Smoke treatment agents that have become used after adsorbing and removing harmful substances have also been used as a part of raw materials in cement production due to social demands as described above.

[0005]

However, the used flue gas treating agent usually has a large difference in chemical composition from the cement raw material, and also hinders the production of cement such as harmful components such as dioxins and chlorine. Contains ingredients. Therefore, when using used flue gas treating agent as a part of cement raw material, it is necessary to perform complicated raw material mixture calculation or to reduce the amount of used flue gas treating agent so that it does not affect cement production. There was a problem that it had to be limited to a small amount.

[0006]

Means for Solving the Problems The inventors pay attention to the components of the flue gas treating agent, and if the flue gas treating agent of a specific component is used,
After being used, they found that cement can be easily used as a raw material for cement, and found that CaO, which is the main component of the flue gas treatment agent, is contained in the cement production intermediate. The present invention has been completed.

Specifically, the flue gas treating agent of the present invention comprises:
(1) 60% to 70% of CaO in oxide mass basis, the SiO ₂ 10 to 17
%, The Al ₂ O ₃ 1 to 5%, flue gas treatment agent containing Fe ₂ O ₃ 1 to 3%, or (2) 60% to 70% of CaO in oxide mass basis, the SiO ₂ 10
To 17% Al ₂ O ₃ 1-5%, the inorganic powder 10 containing Fe ₂ O ₃ 1~3%
It is a flue gas treatment agent containing 0 parts by weight and 1 to 35 parts by weight of activated carbon. Further, the flue gas treatment agent of the present invention includes (3) one in which the specific surface area of activated carbon is 1000 m ² / g or more, and (4) one in which half or more of CaO is free lime. Further, the flue gas treating agent of the present invention contains 60 to 70% of CaO and 10 to 17% of SiO _{2 based} on the mass of the oxide.
%, 1 to 5% of Al ₂ O _3, and a component containing 1 to 3% of Fe ₂ O ₃ are (5)
700 to 1100 of cement firing process including pre-heater
(6) Cement firing process including a preheater, which is an inorganic powder during firing extracted from the temperature range of ℃.
Includes those obtained by digesting inorganic powder during calcination extracted from the temperature range of 700 to 1100 ° C. and converting part or all of CaO to calcium hydroxide. Further, the present invention provides (7) using the above-mentioned flue gas treating agent for flue gas treatment, and converting the flue gas treating agent containing used dust to 700 to 1100 ° C. in a cement firing step including a pre-heater. The cement manufacturing method of the present invention includes a cement manufacturing method of charging from a position in a temperature range, and (8) a cement manufacturing method of cleaning the used flue gas treating agent using water and then inputting it to a cement manufacturing process. including.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The flue gas treating agent of the present invention is an oxidizing substance.
60-70% CaO, SiO_Two10 ~ 17%, Al_TwoO_Three1 to 5
%, Fe_TwoO_Three1 to 3%. CaO, SiO_Two,
Al_TwoO_Three, Fe_TwoO_ThreeIs the main component of cement clinker. C
In the production of cement, limestone, clay, iron raw materials, etc.
60-70% of CaO, SiO_TwoIs 10-17%, Al_TwoO_Three
1-5%, Fe_TwoO_ThreeCrushed so that is within the range of 1-3%
It is mixed and supplied to a cement firing furnace. In the firing furnace
Is CaO, SiO_Two, Al_TwoO_Three, Fe_TwoO _ThreeThe mixture containing
The ash content in the fuel supplied to the
In addition, the optimal component set for forming the cement clinker
Will be successful. In the present invention, the composition of the flue gas treatment agent is
60-70% CaO, SiO_TwoIs 10-17%, Al_TwoO_ThreeIs 1 to 5
%, Fe_TwoO_ThreeIs in the range of 1 to 3%. It is made of cement
Limestone, clay, iron raw materials, etc. are ground and mixed during the
It is close to the composition when supplied to the furnace,
Used as a result of the addition of dust from incineration
When it becomes, the composition suitable for forming the cement clinker
It has the effect of becoming a minute composition. Moreover, the flue gas treatment agent
As for the performance of absorbing harmful substances in flue gas,
The equivalent of conventional flue gas treatment agents is obtained. Composition is in this range
If it is out of the surroundings, the composition after using it for smoke
May be out of the range suitable as a raw material for That
Therefore, when used as a cement raw material, the composition must be adjusted again.
It is not preferable because it becomes necessary. CaO, S in the flue gas treatment agent
iO_Two, Al_TwoO_Three, Fe_TwoO_ThreeAre within the scope of the present invention.
If the other components do not interfere with cement production,
Can be used to adsorb and remove dioxins.
Activated carbon can be mixed or used in combination. Ma
In addition, in order to improve the filterability of smoke exhaust with a bag filter,
Diatomaceous earth may be added.

[0009] When using activated carbon, 60% to 70% of CaO in oxide mass basis, the _{SiO 2 10~17%, Al 2 O} 3 1-5%,
Activated carbon 1 per 100 parts by weight of inorganic powder containing 1-3% Fe ₂ O ₃
It is preferred to add up to 35 parts by weight. If the amount of activated carbon is less than 1 part by weight, dioxins in the flue gas cannot be sufficiently adsorbed. If the amount of activated carbon is too large, it is uneconomical because the amount of the flue gas treating agent increases and the amount of the used flue gas treating agent increases. In addition, an increase in the amount of activated carbon is not preferable because the filtration step may be hindered in the washing treatment of the used flue gas treating agent described below. If the specific surface area of the activated carbon is 1000 m ² / g or more, the adsorption efficiency of dioxins is high, and the amount of activated carbon in the flue gas treatment agent can be suppressed to 1 to 15% by mass. In the water washing treatment of the treating agent, the filtering step is more efficient, which is particularly preferable. The type of activated carbon is not particularly limited, and may be any of plant-based and mineral-based.

[0010] CaO in the flue gas treatment agent of the present invention, if it is in the form of free lime, ie, calcium hydroxide or calcium oxide, is mixed with harmful substances (acid gas such as hydrogen chloride and sulfur oxide) in the flue gas. High reactivity. Therefore, it is preferable that at least half or more of CaO in the flue gas treatment agent of the present invention is in the form of calcium hydroxide or calcium oxide, or a mixture thereof.

[0011] Of the flue gas treatment agent of the present invention, 60% to 70% of CaO in oxide mass basis, the _{SiO 2 10~17%, Al 2 O} 3 1-5%,
As the component containing 1 to 3% of Fe ₂ O ₃ , inorganic powder in the middle of firing extracted from a temperature range of 700 to 1100 ° C. in a cement firing step including a preheater can be used. The components extracted from the temperature range of 700 to 1100 ° C in the cement firing process including the pre-heater in the cement manufacturing process have a component composition on an oxide mass basis within the scope of the invention and have been used. After that, not only can it be used as a cement raw material without adjusting the components, but also CaO is in the form of calcium oxide, which is highly reactive with hydrogen chloride and sulfur oxides, It is suitable. Further, each component of SiO ₂ , Al ₂ O ₃ , and Fe ₂ O ₃ has a function as a filter aid for flue gas with a bag filter, and is more suitable as a flue gas treatment agent. If the temperature range of the extraction point is lower than 700 ° C., a part of the CaO content is not preferable because it has a form of calcium carbonate having insufficient activity as a smoke exhaust treatment agent. On the other hand, the temperature range of the cement manufacturing process was 11
The position exceeding 00 ° C. is a rotary kiln, and it is difficult to extract inorganic powder during firing from the rotary kiln on an apparatus. Even if it is extracted, the calcination proceeds and almost no CaO content in the form of free lime is obtained, which is unsuitable as a flue gas treatment agent. The position where the components of the smoke exhausting agent are extracted is, for example, the lower part of the lowermost cyclone of the preheater. For the extraction, for example, an opening is provided at the extraction position, and a powder conveying device, for example, a screw conveyor, or a tube equipped with a mechanism that can be suctioned by an external suction pump is inserted into the opening, and then dropped. It may be carried out by a method such as receiving the incoming cement intermediate product with a powder conveying device and carrying it out of the cement production system. Immediately after the extraction, if the extract is exposed to the outside air, the calcium oxide in the extract may react with carbon dioxide and water in the air and reduce the activity as a flue gas treatment agent. It is preferable to take countermeasures such as adopting a structure that can be used.

Some or all of the calcium oxide in the extract may be digested to form calcium hydroxide. The digestion method is not particularly limited as long as it reacts with moisture while preventing a decrease in activity due to carbonation.
In order to increase the specific surface area of calcium hydroxide, various digestion methods such as adding an organic solvent such as alcohol to digestion water as a digestion reaction retarder have been proposed, and can be selected from these conventional methods. .

The flue gas treating agent of the present invention can be blown in a refuse incineration plant or the like by using a conventional flue gas treating agent blowing device as it is. The greater the amount of the smoke treatment agent blown into the flue, the greater the amount of harmful substances adsorbed and the higher the effect of purifying the smoke. It is uneconomical to inject the agent. Therefore, the blowing amount of the flue gas treating agent depends on the component composition of the flue gas generated by the incineration of the refuse, but is preferably about equivalent to about 10 times the amount of the dust in the flue gas.

[0014] In the cement production method of the present invention, the above-mentioned flue gas treating agent is used for flue gas treatment, and the spent flue gas treating agent containing soot and dust is used in a cement firing step including a pre-heater in a cement sintering step. This is a method for producing cement that is charged from a temperature range of 1100 ° C. The used flue gas treating agent can be mixed with the blended raw material in the cement manufacturing process, and can be put into the cement firing furnace together with the blended raw material. However, in recent years, the amount of dioxins discharged together with flue gas has been regulated, and therefore, a technique of adsorbing and removing dioxins from flue gas using a flue gas treating agent mixed with activated carbon has been used. The flue gas treatment agent obtained by such a method contains dioxins, and therefore, when put into a cement firing furnace together with the prepared raw materials, a relatively low temperature (200 to 400 ° C.) of the upstream portion of the firing furnace (preheater) is used. There is a concern that dioxins will be volatilized at the position of and the dioxin will be discharged from the cement production facility. It is well known that dioxins must not be generated in recycling waste. In the present invention, in the cement firing step including the preheater, the used flue gas treating agent is charged at a position of 700 to 1100 ° C. The dioxins charged together with the used flue gas treatment agent are immediately exposed to a high temperature of 700 to 1100 ° C, and are guided to a high-temperature rotary kiln, where they are instantaneously decomposed. Therefore, cement can be manufactured using the used flue gas treating agent without generating secondary pollution. The temperature at the point of introduction is 700 ° C
If it is less than 1, the dioxin volatilized from the flue gas treating agent may not be completely decomposed, which is not preferable. On the other hand, the position in the cement firing step where the temperature exceeds 1100 ° C. is inside the rotary kiln, and it is difficult to provide an inlet for the flue gas treating agent in the middle of the rotary kiln. The present invention utilizes the fact that the spent flue gas treating agent has a composition suitable for cement production. Therefore, it is not necessary to adjust the composition at the time of mixing the raw materials, and in principle, it can be directly input to the cement firing step. Further, there is an advantage that the input amount can be remarkably increased as compared with the conventional used flue gas treating agent. The charging position of the used flue gas treating agent is, for example, a calciner, a rotary kiln inlet (kiln bottom), or the like. Provide openings with double dampers at those positions, suitable powder conveying device,
For example, the used flue gas treatment agent may be charged using a screw conveyor, a pump, or the like.

[0015] The cement production method of the present invention includes a cement production method in which the used flue gas treating agent is washed with water and then put into a cement production step. The used flue gas treatment agent may contain dioxins as described above, and also contains chlorine. If chlorine remains in the cement, it may cause rust on the reinforcing steel bars, which is not preferable.
Further, the chlorine component generates a compound which is easily volatilized in the cement firing furnace. These compounds volatilize in the rotary kiln and condense on the pre-heater and solidify, sometimes causing clogging of the pre-heater, which hinders the production of cement. Therefore, the amount of the used flue gas treating agent as a cement raw material may be limited. In the present invention, by washing the used flue gas treating agent with water in advance, it is possible to remove chlorine that hinders cement production, and does not hinder cement production.
Large amounts of used flue gas treatment agents can be used for cement production. The water washing method may be performed by, for example, putting water in an appropriate dissolving tank, adding a used flue gas treating agent and stirring, filtering the suspension with a filter press, a belt filter, etc., and dehydrating the suspension. The obtained dehydrated cake is used as a cement raw material. Since the filtrate is alkaline due to the calcium content in the flue gas treatment agent, it is neutralized, the precipitate generated by the neutralization is removed, the wastewater is removed by removing dissolved heavy metals, etc., and then the wastewater is drained. I just need.

[0016]

The present invention will be described below with reference to examples. (Example 1) In the cement firing step, the powder during firing was extracted from the lower part of the cyclone closest to the rotary kiln of the preheater to obtain a flue gas treating agent. The temperature at the extraction position was 1000 ° C. Extracted flue gas treatment agent was analyzed by component a fluorescent X-ray analyzer, CaO 65% as an oxide mass, SiO ₂ is 14% Al ₂ O ₃ is 3.5%, the Fe ₂ O ₃
1.5% was included. 0.5 g of this powder is weighed into a combustion boat, placed in a borosilicate glass reaction tube having an inner diameter of 3 cm, and heated to 200 ° C. in a tubular furnace, while containing 20% of water and 2,000 ppm of HCl.
Nitrogen gas was flowed at a flow rate of 0.5 m / min for 3 hours to allow the flue gas treatment agent to absorb HCl gas. The amount of HCl absorbed by the flue gas treating agent was 0.13 g per 1 g of CaO in the flue gas treating agent, which was equivalent to that of a commercially available flue gas treating agent. Next, the flue gas treatment agent and activated carbon (specific surface area 1050 m ² / g) were mixed in a mass ratio of 9: 1, and immediately before the bag filter of the refuse incinerator, about 5 times the mass of the dust was blown. And the flue gas treating agent were collected by a bag filter to obtain a used flue gas treating agent. Table 1 shows the components of the obtained used flue gas treating agent. This spent flue gas treatment agent is put into the cement baking furnace at a temperature of 1000 ° C from the position of 120 kg per 1 t of cement clinker production,
Other than that, cement was manufactured in the usual process,
Dioxins were not detected in the exhaust gas from the cement sintering furnace, and the obtained clinker was of exactly the same quality as a normal clinker as shown in Table 1.

(Example 2) A bag filter of a refuse incinerator in which garbage containing a large amount of chlorine is being incinerated after mixing activated carbon with the flue gas treating agent obtained in the same manner as in Example 1 Immediately before, about 5 times the mass of the dust was blown, and the dust and the smoke-treating agent were collected by a bag filter to obtain a used smoke-treating agent. Table 1 shows the components of the obtained used flue gas treating agent.
Shown in After adding and stirring 10 L of water per 1 kg of the used flue gas treating agent, the mixture was filtered using a filter press to obtain a dehydrated cake. Table 1 shows the components (dry state) after washing with water. After drying this dewatered cake, the cement baking furnace temperature from 1000 ° C
The cement was manufactured in the usual process except that it was charged for 120 kg, but dioxins were not detected in the exhaust gas from the cement firing furnace, and the obtained clinker was completely equivalent to the normal clinker as shown in Table 1. It was quality.

(Comparative Example) A commercially available flue gas treating agent (JIS R 9001)
0.5 g of special lime (lime) was weighed into a combustion boat in the same manner as in Example 1, placed in a borosilicate glass reaction tube having an inner diameter of 3 cm, and heated to 200 ° C. in a tubular furnace to remove 20% of water and HCl. 20
Nitrogen gas containing 00 ppm was flowed at a flow rate of 0.5 m / min, and the flue gas treatment agent absorbed HCl gas. The amount of HCl absorbed by the flue gas treating agent was 0.14 g per 1 g of CaO in the flue gas treating agent. Next, a commercially available flue gas treatment agent (JIS R 9001 special lime slaked)
After mixing activated carbon in the same manner as in Example 1, about 5 times the mass of the dust was blown from immediately before the bag filter of the refuse incinerator during incineration, and the dust and the flue gas treatment agent were collected by the bag filter. A used flue gas treating agent was obtained. Table 1 shows the components of the obtained used flue gas treating agent. This spent flue gas treating agent was charged at a temperature of 1000 ° C. in a cement sintering furnace, and the cement was manufactured in the usual process except for the above. The quality of the obtained cement was completely equivalent to that of ordinary cement when the used flue gas treatment agent was used in an amount of 30 kg per 1 t of cement clinker production. However, when the input amount was set to 60 kg per 1 t of cement clinker production, as shown in Table 1, the free lime content in the clinker was 1.3%, which was a defective product. Therefore, when the used flue gas treatment agent of this comparative example is used as a cement raw material, the input amount must be less than 60 kg per 1 t of cement clinker production amount at the maximum.
This is the input amount in the case of Examples 1 and 2 (120 k
It was considerably smaller than g).

[0019]

[Table 1]

[0020]

According to the present invention, a large amount of used flue gas treating agent is used for a part of the raw material in each stage as compared with the case of using the conventional flue gas treating agent without complicated formulation calculation. Cement can be produced by the method, and it is possible to contribute to further reduction of waste while achieving labor saving in cement production. Furthermore, since a large amount of used flue gas treating agent is used as a part of the raw material, it is also effective in reducing the cost of cement production.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B01J 20/10 B01D 53/34 134A 20/20 ZAB B09B 3/00 134E C04B 7/24 124Z 7/38 B09B 3/00 303B 7/44 303L 304Z 304G F-term (Reference) 4D002 AA02 AA19 AA21 AB01 AC04 BA03 BA04 BA14 CA01 CA11 DA05 DA11 DA12 DA16 DA22 DA41 DA46 EA13 FA02 GA01 GB08 GB12 HA01 HA04 4D004 AA37 AA50 BA10 CA30 CB09 A03A06 4 AA17B AA20B AA22B AA27B AA43B AA75A CA07 CA31 CA33 DA02 FA11 FA22 FA34 FA37

Claims (8)

[Claims] (1) 60 to 70% of CaO, SiO ₂
The 10 to 17%, the Al ₂ O ₃ 1 to 5% flue gas treatment agent comprising Fe ₂ O ₃ 1~3%. 2. 60% to 70% of CaO, SiO ₂
Flue gas treating agent containing 10 to 17%, the Al ₂ O ₃ 1 to 5% and the inorganic powder 100 parts by weight containing Fe ₂ O ₃ 1 to 3 percent, and activated carbon 1-35 parts by weight. 3. The flue gas treating agent according to claim ² , wherein the specific surface area of the activated carbon is 1000 m ² / g or more. 4. A flue gas treating agent according to claim 1, wherein at least half of CaO is free lime. 5. CaO content of 60 to 70% based on oxide mass, SiO ₂
The 10 to 17%, the Al ₂ O ₃ 1 to 5% is component comprising Fe ₂ O ₃ 1 to 3% of the cement burning process including preheater 700-1
The flue gas treating agent according to any one of claims 1 to 4, wherein the inorganic powder is a calcined inorganic powder extracted from a temperature range of 100 ° C. 6. 60-70% of CaO based on oxide mass, SiO ₂
The 10 to 17%, the Al ₂ O ₃ 1 to 5% is component comprising Fe ₂ O ₃ 1 to 3% of the cement burning process including preheater 700-1
The waste powder according to any one of claims 1 to 4, wherein the inorganic powder in the course of firing extracted from the temperature range of 100 ° C is digested to convert a part or all of the CaO content into a form of calcium hydroxide. Smoke treatment agent. 7. A method according to any one of claims 1 to 6, wherein the flue gas treating agent is used for flue gas treatment, and the spent flue gas treating agent containing dust is used in a cement firing step including a preheater. Among them, the cement production method which is charged from a position in the temperature range of 700 to 1100 ° C. 8. The cement production method according to claim 7, wherein the used flue gas treating agent is washed with water and then put into a cement production step.