JP2013035708A - Method for producing cement clinker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of rapidly and economically producing cement clinker by firing a large quantity of waste in a cement production facility without using a special agent such as limestone.SOLUTION: A first and a second cement production facilities each provided with a preheater 5, a rotary kiln 3 and a cooler 7 are prepared. In the first cement production facility, a fired material is obtained while sprinkling water from the preheater 5 and the kiln inlet of the rotary kiln 3 in the first cement production facility, and a mixture of the fired material and a separately prepared cement raw material is introduced into the second cement production facility, where cement clinker is obtained.

Description

  The present invention relates to a method for producing a cement clinker from waste such as building waste, building generated soil, waste plastic, sludge, and contaminated soil.

In recent years, various economic developments have generated a large amount of waste as described above, and its disposal has become an important social problem.
Various proposals have been made as methods for treating waste. For example, Patent Document 1 discloses a method for producing a cement clinker by using two cement firing facilities and firing the waste in two stages. Proposed.

Japanese Patent No. 4118632

The method of Patent Document 1 is a very significant technique from the viewpoint that industrial waste can be reused industrially, but there are still problems to be solved in order to treat a large amount of waste.
For example, in the above method, the waste is mixed with the cement raw material and fired in the rotary kiln of the cement manufacturing facility. However, the waste includes various materials, and generally, inorganic chloride such as NaCl is contained. Many are included. The presence of such inorganic chloride causes a coating trouble in the cement manufacturing facility. That is, when the waste is heated to a high temperature, non-combustible materials such as inorganic chlorides melt and are fused to the wall surface of a relatively low temperature part such as a preheater (cyclone) in a cement manufacturing facility. It will cause inconvenience such as clogging. In order to prevent such a coaching trouble when using waste, in Patent Document 1, limestone is mixed with waste and used. Specifically, 20% by weight or more of limestone in terms of CaO must be blended in the fired product fired in the rotary kiln.

  That is, in the method of Patent Document 1, the more waste to be processed, the more limestone must be used. In addition, a huge amount of waste is generated at the time of a disaster such as an earthquake, so that a huge amount of limestone is required, which makes it difficult to process quickly and causes a problem of cost.

  Therefore, an object of the present invention is to provide a method capable of producing a cement clinker quickly and economically by firing a large amount of waste in a cement production facility without using a special agent such as limestone. provide.

According to the present invention, a first cement production facility comprising a preheater for preheating cement raw material, a rotary kiln for firing preheated cement raw material, and a cooler for cooling a fired product obtained from the rotary kiln, and Prepare a second cement production facility,
After drying and pulverizing the waste using a dryer and pulverizer, it is introduced into the first cement production facility,
In the first production facility, the waste is preheated to a temperature of 300 to 800 ° C. by a preheater while sprinkling water from the kiln bottom of the preheater and the rotary kiln, and then at a temperature of 800 to 1100 ° C. by a rotary kiln. Baked, then cooled by a cooler,
The fired product obtained in the first cement production facility is mixed with a separately prepared cement raw material,
Introducing the mixture into a second cement production facility;
In the second cement production facility, the mixture is subjected to preheating by a preheater, firing by a rotary kiln and cooling by a cooler to obtain a cement clinker.
A method for producing cement clinker from waste is provided.

In the production method of the present invention,
(1) After washing the fired product obtained in the first cement manufacturing facility with water, mixing with the cement raw material and introducing it into the second cement manufacturing facility;
(2) The second cement production facility is provided with an extraction facility for removing chlorine, exhaust gas discharged from the preheater of the first cement production facility is supplied to the extraction facility, and chloride is removed from the exhaust gas. To do,
(3) exhausting the exhaust gas discharged from the preheater of the first cement manufacturing facility after contacting and cooling the waste before being introduced into the preheater;
(4) introducing the exhaust gas discharged from the pre-heater of the first cement manufacturing facility into the rotary kiln of the second cement manufacturing facility, heating it to a high temperature, and exhausting it;
Is preferred.

In the present invention, waste water containing various waste materials is preheated to a temperature of 300 to 800 ° C. by the preheater while watering the preheater, and then supplied to the rotary kiln while watering from the kiln bottom. Firing is performed at a temperature of 1100 ° C. In other words, water overspreading from the preheater and the kiln bottom effectively prevents overheating of the inner wall of the preheater and rotary kiln. As a result, melting and fusing of incombustible components in waste due to such overheating Is effectively prevented.
As described above, in the present invention, it is possible to effectively prevent deterioration of the cement production facility due to fusion of incombustible components in the waste, even though no special agent such as limestone is used. .

  Furthermore, in the present invention, the calcined product obtained in the first cement production facility can be washed with water to remove chloride present in the calcined product. That is, after the dehydrated and / or dried calcined product from which the chloride has been removed by washing with water is mixed with other cement components and introduced into the second cement manufacturing facility, the second derived from the chloride is obtained. Coaching troubles in cement production facilities can be effectively prevented.

  Moreover, in the exhaust gas discharged from the preheater of the first cement production facility, chlorine derived from chloride contained in the waste is present, and such chlorine is present in the second cement production facility. It can be easily removed using the chlorine extraction equipment provided for chlorine removal.

  Further, the exhaust gas discharged from the preheater of the first cement production facility is a gas having a dioxin decomposition temperature (about 800 ° C.) or higher exhausted through the preheater, and has a temperature of 300 ° C. or higher. doing. Therefore, the exhaust gas does not substantially contain dioxin, but dioxin may be re-synthesized in the process of cooling the exhaust gas.

  However, by cooling such exhaust gas in contact with waste before being introduced into the pre-heater, the heat of the exhaust gas can be used effectively, and at the same time, generation of dioxins can be effectively prevented. . Moreover, generation | occurrence | production of dioxin can be effectively prevented also by introduce | transducing this waste gas into the rotary kiln of a 2nd cement manufacturing equipment, and heating it to high temperature.

The schematic of the cement manufacturing equipment used by this invention. The figure which shows the process of the manufacturing method of the cement clinker of this invention implemented using the cement manufacturing equipment of FIG.

  In the present invention, a cement clinker is manufactured from waste using two cement manufacturing facilities (first and second cement manufacturing facilities). That is, the waste is fired using the first cement manufacturing facility to obtain a powder fired product from which organic substances have been removed, and this fired product is mixed with the cement raw material and fired using the second cement manufacturing facility. Thus, a cement clinker is manufactured.

  Wastes used as raw materials include inorganic materials that can be used as cement raw materials. For example, waste materials such as building waste materials, building generated soil, waste plastics (containing inorganic fillers), sewage treatment facilities, etc. Examples include contaminated soil contaminated with organic matter, and even organic matter such as waste wood can be used in combination with inorganic-containing waste.

  Moreover, the 1st and 2nd cement manufacturing equipment used in this invention is conventionally used in cement manufacture, for example, has the structure shown in FIG.

  In FIG. 1, a cement manufacturing facility indicated by 1 as a whole has a rotary kiln 3, a preheater 5, and a cooler 7.

  The rotary kiln 3 performs high-temperature firing under rotation by a burner arranged in front of the kiln. The pre-heater 5 is connected to the kiln bottom of the rotary kiln 3 and is composed of a plurality of cyclones to preheat the raw material by heat exchange with the high-temperature exhaust gas from the rotary kiln 3. Furthermore, the cooler 7 is for cooling the high-temperature fired material discharged | emitted from before a kiln.

  In the present invention, the cement clinker is manufactured from the above-mentioned waste using the two cement manufacturing facilities having the above structure, and a representative example of the process is shown in FIG.

  That is, the waste used as a raw material is dried by the dryer 11 and then introduced into a pulverizer 13 such as a mill and pulverized to an appropriate size. In this case, it is possible to perform pulverization first and then dry, but since pulverization in the presence of moisture is less efficient, it is generally preferable to pulverize after first drying. .

  The raw material dried and pulverized as described above is introduced into the first cement manufacturing facility 1a having the structure described above. That is, the raw material is introduced into the preheater 5a provided in the first cement manufacturing facility 1a, preheated by the preheater 5a, and then introduced into the rotary kiln 3a to be fired, and the fired product obtained. Is cooled by a cooler 7a and taken out from the first cement production facility 1a.

In the present invention, preheating in the preheater 5a is performed while sprinkling water and is performed in the range of 300 to 800 ° C. That is, if the preheating is simply performed without watering, the preheater 5a overheats, the non-combustible components in the waste melt, and it becomes easy to cause a coating trouble that is fused to the wall surface of the preheater 5a (cyclone). End up. However, preheating under watering can effectively prevent overheating of the preheater 5a and avoid fusion of incombustible components.
In addition, when preheating temperature is lower than 300 degreeC, preheating becomes inadequate with an excessive water sprinkling, and it will become easy to produce the raw burn of a baked product. On the other hand, when the preheating temperature is higher than 800 ° C., the watering is insufficient, and it becomes difficult to prevent the coating drool in the preheater.

The waste preheated by the pre-heater 5a is introduced into the rotary kiln 3a, and by firing under rotation, organic components and chlorine compounds are volatilized to obtain a fired product that becomes a cement raw material. Firing by the rotary kiln 3a is performed by spraying water from the kiln bottom, and the firing temperature is set to 800 to 1100 ° C. That is, the coating dripping in the rotary kiln 3a can be effectively prevented by firing under watering, and the dioxins generated during the preheating in the preheater 5a can be decomposed.
In addition, when a calcination temperature is lower than 800 degreeC, volatilization of an organic component or a chlorine compound becomes inadequate, and it becomes impossible to obtain a granular or powdery baked product. In addition, it becomes difficult to decompose dioxins in the rotary kiln. Furthermore, when the firing temperature is higher than 1100 ° C., there is no particular advantage and energy is wasted.

  The fired product obtained by firing in the rotary kiln 3a as described above is cooled by the cooler 7a and discharged from the first cement manufacturing facility 1a.

The fired product discharged from the first cement manufacturing facility 1a is mixed with an inorganic material containing other cement raw materials, for example, CaO, SiO ₂ , Al ₂ O _3, Fe ₂ O _{3, and the} like, and this mixture is mixed with the second material. The target cement clinker can be obtained by firing the cement manufacturing facility 1b.

In the present invention, as shown in FIG. 2, it is preferable to wash the fired product prior to mixing with other cement raw materials. That is, by washing the fired product with water, chlorides (for example, NaCl) that cause generation of coating troubles and dioxins can be removed.
The fired product washed with water may be immediately mixed with other cement raw materials, or may be temporarily stored in a raw material storage silo, taken out if necessary, and mixed with other cement raw materials.

  The mixture of the fired product and the other cement raw material may be performed after pulverizing the other cement raw material, or may be performed simultaneously with the pulverization of the other cement raw material.

  The mixing ratio of the calcined product obtained from the first cement production facility 1a and other cement raw materials may be determined as appropriate according to the composition of the calcined product, but generally the content of the calcined product in the mixture is 10 to The proportion is preferably 50% by weight. That is, it is preferable because the component adjustment of the cement clinker obtained in the second cement firing facility 1b can be performed with a wide adjustment range.

  Firing of the mixture of the fired product and the other cement raw material using the second cement manufacturing facility 1b is performed by a method known per se. Specifically, the mixture is introduced into the pre-heater 5b of the second cement production facility 1b and preheated, the preheated mixture is introduced into the rotary kiln 3b and baked, and the obtained baked product is cooled by the cooler 7b. The target cement clinker can be obtained by cooling and taking out.

  The preheating temperature in the preheater 5b and the firing temperature in the rotary kiln 3b vary depending on the composition of the fired product and the type of other cement raw materials to be mixed, and cannot be generally defined. 400-1000 degreeC and a calcination temperature are set to the range of 1300-1600 degreeC.

  The cement clinker thus obtained is commercialized as a cement by adding gypsum or the like as necessary and pulverizing.

  In the present invention described above, combustible waste (for example, waste plastic and waste wood) becomes fuel, and therefore, after drying and pulverizing as necessary, it is not introduced into the preheater 5b, and the first cement production facility It can be incinerated by supplying it directly to the kiln bottom of 1a or the second cement production facility 1b.

In the present invention, the exhaust gas discharged from the pre-heater 5a of the first cement manufacturing facility 1a contains chloride derived from waste used as a raw material, and the presence of such chloride causes the occurrence of dioxins and coaching troubles. It becomes a factor.
For example, as shown in FIG. 2, such an exhaust gas can be introduced into a chlorine removal extraction facility provided in the second cement production facility 2 b and exhausted. That is, this chlorine removal bleed facility can condense and separate the chlorine compounds contained in the exhaust gas, and then remove the dust through a dust collector such as an electric dust collector or a bag filter and exhaust it.
If the first cement production facility 1a is provided with a chlorination extraction facility, the facility condenses and separates the chlorine compounds contained in the exhaust gas, and then uses an electrostatic precipitator, bag filter, etc. Dust can be removed and exhausted through a dust collector.

Further, the exhaust gas discharged from the preheater 5a is obtained by discharging a gas having a dioxin decomposition temperature of 800 ° C. or higher through the preheater 5a. Therefore, dioxin is not contained in the exhaust gas, but dioxin may be re-synthesized in the course of cooling. In order to prevent such re-synthesis of dioxin, as shown in FIG. 2, it is brought into contact with the waste of the raw material and introduced into the dryer 11 together with the raw material waste, for example, and then the dust is passed through the dust collector. It is possible to evacuate after removing. In other words, dioxin resynthesis can be effectively prevented by contacting the low temperature raw material waste to rapidly cool the exhaust gas, and the raw material waste can be dried and crushed by effectively using the heat of the exhaust gas. It can be done efficiently.
In the example shown in FIG. 2, the exhaust gas brought into contact with the raw material waste is introduced from the dryer 11 to the dust collector, but may be introduced from the pulverizer 13 to the dust collector and exhausted.

  Furthermore, as shown in FIG. 2, the exhaust gas discharged from the preheater 5a can be directly introduced into the rotary kiln 3b of the second cement production facility 1b. In this case, even if dioxin is re-synthesized in the process of cooling the exhaust gas, it is decomposed in the rotary kiln 3b that is fired at a temperature of 800 ° C. or higher. In this case, the exhaust gas discharged from the pre-heater 5b connected to the rotary kiln 3b contains chloride derived from waste, and this exhaust gas is condensed and separated through chloride extraction equipment for chlorine removal. Exhaust through a dust collector.

The method for producing a cement clinker of the present invention is extremely useful for the treatment of a large amount of waste, and a cement clinker can be produced at low cost using waste as a raw material without using a special agent such as limestone.
In addition, even when a large amount of salt or the like is attached to the waste, it is possible to effectively avoid the occurrence of coaching troubles and dioxins derived from the salt.

DESCRIPTION OF SYMBOLS 1a: 1st cement manufacturing equipment 1b: 2nd cement manufacturing equipment 11: Dryer 13: Crusher 5: Preheater 3: Rotary kiln 7: Cooler

Claims (5)

A first cement production facility and a second cement production facility each comprising a preheater for preheating cement raw material, a rotary kiln for firing the preheated cement raw material, and a cooler for cooling the fired product obtained from the rotary kiln. Prepare
After drying and pulverizing the waste using a dryer and pulverizer, it is introduced into the first cement production facility,
In the first production facility, the waste is preheated to a temperature of 300 to 800 ° C. by a preheater while sprinkling water from the kiln bottom of the preheater and the rotary kiln, and then at a temperature of 800 to 1100 ° C. by a rotary kiln. Baked, then cooled by a cooler,
The fired product obtained in the first cement production facility is mixed with a separately prepared cement raw material,
Introducing the mixture into a second cement production facility;
In the second cement production facility, the mixture is subjected to preheating by a preheater, firing by a rotary kiln and cooling by a cooler to obtain a cement clinker.
A method for producing cement clinker from waste.   The method according to claim 1, wherein the fired product obtained in the first cement production facility is washed with water, and then mixed with the cement raw material and introduced into the second cement production facility.   An extraction facility for removing chlorine is provided in the second cement production facility, exhaust gas discharged from a preheater of the first cement production facility is supplied to the extraction facility, and chloride is removed from the exhaust gas. The method according to 1 or 2.   The method according to claim 1 or 2, wherein the exhaust gas discharged from the preheater of the first cement production facility is cooled after being brought into contact with the waste before being introduced into the preheater and then cooled.   The method according to claim 1 or 2, wherein the exhaust gas discharged from the preheater of the first cement production facility is introduced into a rotary kiln of the second cement production facility, heated to a high temperature, and then exhausted.

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