JP2018168043A - Method for producing cement clinker, method for producing cement and method for processing organic sludge and construction based waste plastic - Google Patents

Abstract

To provide a method for producing a cement clinker capable of suppressing generation of coating in a method for producing a cement clinker in which construction based waste plastic is added to a calcination step.SOLUTION: There is provided a method for producing a cement clinker which comprises: a calcination step of calcining a raw material for a cement clinker to produce a cement clinker; and a reduction step of reducing a sulfur component contained in a mixture obtained by mixing construction based waste plastic and an organic sludge containing anaerobic bacteria for generating hydrogen sulfide from sulfur oxide by fermentation and reducing the water content of the mixture, wherein the mixture obtained in the reduction step is added to the calcination step. There is provided a method for producing a cement clinker in which in the reduction step, the mixture is preferably is fermented by aerobic bacteria after fermentation by anaerobic bacteria. There is provided a method for producing a cement clinker in which the reduction step is preferably carried out until the water content of mixture is 40 mass% or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing cement clinker, a method for producing cement, and a method for treating organic sludge and waste plastic.

  Conventionally, construction waste plastics can be cited as waste discharged from construction waste and the like. As a method for treating waste plastic, for example, Patent Document 1 describes that waste plastic is charged into a cement clinker firing step.

JP 2002-348154 A

  As a result of diligent research, the present inventors have found that when construction waste plastic is put into a cement firing process, problems such as generation of coaching in the preheater of the kiln and blockage of the preheater due to the coaching occur. It was. As a result of further diligent research, the present inventors have found that the generation of coaching in the kiln is caused by sulfur content mixed in construction waste plastic, and that sulfur content is mixed in construction waste plastic. Because it is derived from waste gypsum, therefore, by introducing construction plastic waste with reduced sulfur content in the waste gypsum mixed into the cement clinker firing process (cement clinker manufacturing process), The inventors have found that the production can be suppressed, and have reached the present invention.

  A main object of the present invention is to provide a cement clinker manufacturing method capable of suppressing the generation of coating in a cement clinker manufacturing method in which construction waste plastics are charged into a firing step.

  The method for producing a cement clinker according to the present invention is a method for producing a cement clinker including a firing step for producing a cement clinker by firing a raw material of the cement clinker. The method for producing a cement clinker according to the present invention further includes a reduction step. In the reduction process, by mixing and recycling fermented waste plastic and organic sludge containing anaerobic bacteria that generate hydrogen sulfide from sulfur oxide by fermentation, the sulfur component contained in the mixture is reduced, Reduce the water content of the mixture. The mixture obtained in the reduction step is put into the firing step.

  Generally, construction waste plastic separated from construction waste generated at a construction site includes gypsum (waste gypsum board and its crushed material) and the like. For this reason, when construction waste plastic is input into the firing process, waste gypsum containing sulfur is also input together with the plastic. Therefore, the mixture of waste plastics for construction and organic sludge usually contains sulfur.

  In the method for producing a cement clinker according to the present invention, the sulfur content of the mixture is reduced by fermentation with anaerobic bacteria performed in the reduction step. For this reason, generation | occurrence | production of coaching is suppressed in a baking process. Therefore, problems such as blockage of a kiln and the like due to coaching are unlikely to occur.

  In addition, plastics contained in construction waste plastics have a high amount of heat per unit weight. For this reason, more calorie | heat amount can be obtained from a mixture. Therefore, the fuel required for manufacturing the cement clinker can be reduced. Therefore, the manufacturing cost of cement clinker can be suppressed. In particular, in the present invention, since the sulfur content contained in the construction waste plastic can be reduced, the amount of construction waste plastic that generates a large amount of heat can be increased. Therefore, the fuel required for manufacturing the cement clinker can be further reduced. Therefore, the manufacturing cost of cement clinker can be further reduced.

  Furthermore, fermentation heat is generated in the reduction process. This fermentation heat dries the mixture. For this reason, the mixture thrown into the baking process is a mixture with a reduced moisture concentration. By introducing the mixture having a reduced moisture concentration into the firing step, the amount of heat necessary to remove the moisture contained in the mixture can be reduced, and the mixture can be suitably used as a fuel. In other words, more heat can be obtained from the mixture. Therefore, the fuel required in the firing process can be further reduced. Therefore, the manufacturing cost of the cement clinker can be further reduced.

  Thus, in the cement clinker manufacturing method according to the present invention, the construction waste plastic and the organic sludge can be suitably treated without adversely affecting the firing apparatus such as the kiln, and the production of the coaching is suppressed while being small. Since the firing process can be performed with fuel, the manufacturing cost of cement clinker can be reduced.

  In the method for producing a cement clinker according to the present invention, it is preferable that the mixture is further fermented with aerobic bacteria after fermentation with anaerobic bacteria in the reduction step.

  In the cement clinker manufacturing method according to the present invention, in the reduction step, the construction waste plastic is crushed by crushing the construction waste plastic, and the fluff or fragment construction waste plastic and the organic waste are produced. It is preferable to mix and ferment sludge.

  In the method for producing a cement clinker according to the present invention, in the firing step, it is preferable to introduce the mixture into at least one of the preheater, the calcining furnace and the kiln bottom of the kiln.

  In the method for producing a cement clinker according to the present invention, the organic sludge preferably contains sewage sludge.

  In the method for producing a cement clinker according to the present invention, it is preferable to perform the reduction step until the water content of the mixture becomes 40% by mass or less.

  In the method for producing a cement clinker according to the present invention, in the reduction step, it is preferable to ferment the construction waste plastic and the organic sludge using anaerobic bacteria in a state where they are deposited so that open cells are not formed.

  In the method for producing a cement clinker according to the present invention, it is preferable that the construction waste plastic includes gypsum.

  The cement manufacturing method according to the present invention includes a step of manufacturing a cement clinker by the method of manufacturing a cement clinker according to the present invention and a step of manufacturing a cement from the cement clinker.

  In the method for treating organic sludge and construction waste plastic according to the present invention, the mixture of organic sludge and construction waste plastic is fermented by anaerobic bacteria that generate hydrogen sulfide from sulfur oxides by fermentation to produce waste waste plastic. While reducing the sulfur component contained, the water content of organic sludge is reduced, and a mixture having a low content of sulfur component and a low water content is obtained.

  In the method for treating organic sludge and construction waste plastic according to the present invention, it is preferable to further perform fermentation of the mixture with aerobic bacteria after fermentation with anaerobic bacteria.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the cement clinker which can suppress the production | generation of a coaching can be provided in the manufacturing method of the cement clinker which throws construction-type waste plastics into a baking process.

It is a schematic diagram of a part of a cement manufacturing apparatus according to an embodiment of the present invention.

  Hereinafter, an example of the preferable form which implemented this invention is demonstrated. However, the following embodiment is merely an example. The present invention is not limited to the following embodiments.

  FIG. 1 is a schematic view of a part of a cement manufacturing apparatus 1 according to the present embodiment. Specifically, FIG. 1 shows a cement clinker firing device 10 and a fermentation unit 20 in the cement manufacturing apparatus 1.

  As shown in FIG. 1, raw materials are charged into the firing apparatus 10. Examples of the raw material charged into the baking apparatus 10 include limestone, clay, silica, and waste-based raw materials (for example, organic sludge). The cement burning fuel is input from the calcining furnace 12 and the kiln bottom 13a. Examples of cement fired fuel include organic sludge.

  The raw materials are pulverized and mixed by a raw material pulverizer (raw material mill) (not shown) and then charged into the firing apparatus 10 shown in FIG. Specifically, the raw material is charged into the preheater 11 of the baking apparatus 10. The raw material is preheated by the preheater 11. In addition, it is preferable that the preheater 11 is comprised by the suspension preheater, for example. This is because the preheating efficiency of the raw material can be improved.

  A calciner 12 is connected to the preheater 11 in order to further improve the preheating efficiency. The raw material preheated in the preheater 11 is transferred to the calcining furnace 12. Most of the limestone in the preheated raw material is decarboxylated.

  The calcining furnace 12 is connected to a kiln 13 such as a rotary kiln. The raw material calcined in the calcining furnace 12 is put into the kiln bottom 13 a of the kiln 13. The charged raw material is heated by a main burner (not shown) provided in front of the kiln 13 in the kiln 13 to generate a cement clinker.

  A front kiln 13 of the kiln 13 is connected to a clinker cooler 14. The cement clinker generated in the kiln 13 is cooled in the clinker cooler 14, and the cooled cement clinker is discharged from the clinker cooler 14.

  In the present invention, the baking apparatus used in the baking process may be provided with a kiln and does not necessarily include a preheater or a calcining furnace.

  The manufactured cement clinker is connected to a finishing mill (not shown). In this finishing mill, cement is manufactured by being pulverized and mixed with cement clinker and gypsum, blast furnace slag, fly ash, and the like that play a role in adjusting the hardening rate of the cement.

  As shown in FIG. 1, the cement production apparatus 1 is provided with a fermentation unit 20. The fermentation unit 20 is supplied with a mixture containing construction waste plastic and organic sludge. Construction waste plastic is obtained by sorting plastics from construction waste generated at construction sites or building demolition work. Usually, it is practically difficult to separate only plastic from construction waste, and gypsum (waste gypsum board and its crushed material) is mixed in the construction waste plastic.

  The construction-type waste plastic is preferably supplied in a state of being crushed so as to increase the specific surface area. The construction waste plastic is preferably supplied as, for example, fluffy or fragmented crushed material.

  There are no particular restrictions on the method of mixing construction waste plastic and organic sludge, and various types of mixers such as screw mixers and pan-type mixers can be used, and mixing can be performed using heavy equipment such as excavators.

  Specific examples of the organic sludge include, for example, sewage sludge, human waste sludge, factory wastewater sludge, blue sea urchin, bottom mud, food processing residue and the like. Specific examples of food processing residues include beer grounds, tea grounds, livestock residues and the like. As will be described later, in this embodiment, sewage sludge, human waste sludge, industrial wastewater sludge, blue sewage sludge, bottom mud, etc. having a high water content are supplied to the fermentation unit 20 in order to perform fermentation and drying. Is preferred. One kind of organic sludge can be used, or a plurality of kinds can be used.

  Organic sludge contains moisture and organic components that promote the activity of bacteria, and is suitable for generating hydrogen sulfide from sulfur oxides. In general, in the case of sewage sludge, the moisture content is about 50% by mass to 90% by mass.

  Organic sludge often contains anaerobic bacteria that generate hydrogen sulfide from sulfur oxides by fermentation. For example, sewage sludge containing such anaerobic bacteria can be used as organic sludge as it is, and when using organic sludge that does not contain such anaerobic bacteria, Anaerobic bacteria that generate hydrogen sulfide from sulfur oxide may be mixed and used. Since it is not necessary to add anaerobic bacteria, it is more preferable to use sewage sludge containing anaerobic bacteria as the organic sludge.

  The mixture supplied to the fermentation unit 20 may include raw materials or fuels other than construction waste plastics and organic sludge. For example, the mixture may include garbage, wood chips and the like.

  Since air is supplied to the mixture by mixing organic sludge and construction waste plastic, aerobic fermentation may be performed immediately after mixing. Due to the heat generated at this time, the mixture has a temperature suitable for anaerobic fermentation (30 ° C. to 40 ° C.), and by stopping the turning of the mixture, air is not supplied and anaerobic fermentation proceeds.

  In the fermentation part 20, the mixture containing the construction system waste plastic mixed with waste gypsum board containing sulfur and organic sludge is fermented by anaerobic bacteria that generate hydrogen sulfide from sulfur oxide by fermentation. The generated hydrogen sulfide volatilizes and escapes from the mixture. Thereby, the sulfur component contained in the mixture is reduced, and the mixture is dried by fermentation heat generated along with fermentation to reduce the moisture content of the mixture (reduction step). In the fermentation part 20, the mixture in which the sulfur component content and the water content are reduced is input to the firing step.

  Examples of anaerobic bacteria that generate hydrogen sulfide from sulfur oxide by fermentation include sulfate-reducing bacteria. Examples of sulfate-reducing bacteria include eubacteria such as gram-negative bacteria and gram-positive bacteria, archaea, and the like. Specific examples of sulfate-reducing bacteria include, for example, the genus Desulfovibrio, the genus Desulfotocumum. Only one kind of these anaerobic bacteria may be used, or a plurality of kinds may be used.

  In addition, oxygen is essential in order to perform fermentation using aerobic bacteria. For this reason, in order to perform fermentation using aerobic bacteria, vents for introducing oxygen are formed in the construction waste plastic and organic sludge deposits, or mixed periodically to introduce oxygen into the interior. It is necessary to do. Therefore, the fermentation process becomes complicated.

  On the other hand, when an anaerobic bacterium is used as in this embodiment, oxygen is not required, so there is no need to form a vent for introducing oxygen or to stir periodically. . Therefore, by using anaerobic bacteria, the fermentation process can be prevented from becoming complicated, and high fermentation efficiency can be realized.

  From the viewpoint of improving the fermentation efficiency by anaerobic bacteria, it is preferable that the construction waste plastic is crushed into fragments. By doing so, in a reduction process, a mixture can be fermented in the state accumulated so that an open cell may not be formed. For this reason, since it can suppress that oxygen penetrate | invades into the deposited mixture, the anaerobic fermentation efficiency by anaerobic bacteria can be improved. The construction waste plastic is preferably a fragmented or fluffy crushed material having a maximum particle size of 50 mm or less, and more preferably a fragmented or fluffy crushed material of 30 mm or less. This is because if the particle size of the construction waste plastic is large, an aeration path is formed in the deposit and the fermentation efficiency due to anaerobic bacteria may be reduced. Moreover, since the combustion efficiency in a baking process increases by making the maximum particle diameter of construction waste plastic small, it is more preferable. From the same viewpoint, the construction waste plastic is more preferably in the form of a fluff.

  It is preferable that the deposited mixture is not frequently turned over. However, in order to promote the volatilization of hydrogen sulfide, the mixture may be turned over to such an extent that the fermentation efficiency of anaerobic bacteria is not reduced.

  In the cement clinker manufacturing method of the present embodiment, when fermentation is performed in the reduction process, sulfur contained in waste gypsum mixed in construction waste plastic, or when organic sludge contains sulfur. Reduces its sulfur content. For this reason, generation | occurrence | production of coaching is suppressed in a baking process. Therefore, problems such as blocking of the preheater 11 and the like due to coaching are unlikely to occur. That is, construction waste plastics and organic sludge can be suitably treated while suppressing the generation of coaching.

  Furthermore, fermentation heat is generated by fermentation by bacteria in the reduction process. Due to this heat of fermentation, the water in the mixture is evaporated and dried. For this reason, the mixture thrown into the baking process is a mixture with a reduced moisture concentration. By introducing the mixture having a reduced moisture concentration into the firing step, the fuel required to remove moisture contained in the mixture can be reduced, and the mixture can be suitably used as a fuel. In other words, more heat can be obtained from the mixture.

  Furthermore, plastics have a high amount of heat per unit weight. For this reason, more heat can be obtained from the mixture of construction waste plastic and organic sludge. Therefore, the fuel required for manufacturing cement can be reduced. In particular, in this embodiment, since the sulfur content contained in construction waste plastic can be reduced, the amount of construction waste plastic that generates a large amount of heat can be increased. Therefore, the fuel required for manufacturing the cement clinker can be further reduced. Therefore, the manufacturing cost of cement clinker can be further reduced.

  Since heat generation by anaerobic fermentation is less than that of aerobic fermentation, drying of the mixture can be further promoted by utilizing aerobic fermentation. That is, it is possible to dry the mixture faster by promoting the aerobic fermentation by turning back the mixture and supplying air to the mixture in anticipation of the end of the anaerobic fermentation. When turning the mixture back, drying by aerobic fermentation can be further promoted by adding and mixing organic sludge.

  In addition, from the viewpoint of sufficiently reducing the amount of heat necessary for removing water contained in the mixture, the water content of the mixture is preferably 40% by mass or less, and more preferably 30% by mass or less. However, the more the moisture content of the mixture is reduced, the longer it takes to dry the mixture. Therefore, from the viewpoint of not reducing the production efficiency of the cement clinker, the water content of the mixture is preferably 20% by mass or more.

  As described above, in the method for producing a cement clinker according to the present embodiment, construction waste plastic and organic sludge can be suitably treated without adversely affecting the firing device 10 such as a kiln, and the generation of coaching can be achieved. Since the firing process can be performed with a small amount of fuel while suppressing, the manufacturing cost of cement clinker can be suppressed.

  The mixture to be fermented may contain, for example, raw garbage having a high water content. Even in that case, the activity of the bacteria is promoted by the moisture and organic content of the garbage, and the moisture content of the mixture can be effectively reduced by the heat of fermentation. Therefore, the amount of heat required for removing water from the mixture can be reduced.

  Hydrogen sulfide generated by fermentation in the fermentation unit 20 may be used as a kiln combustion gas, or may be treated by adsorbing hydrogen sulfide on activated carbon.

  The place where the mixture is introduced is not particularly limited. The mixture can be charged into at least one of the preheater 11, the calciner 12, and the kiln 13, for example. Among these, the mixture is preferably charged into at least one of the preheater 11, the calcining furnace 12, and the kiln bottom 13 a of the kiln 13, and more preferably charged into the calcining furnace 12. This is because the mixture can be used not only as a cement raw material but also as an auxiliary fuel in the calcining furnace 12.

1: Manufacturing apparatus 10: Baking apparatus 11: Preheater 12: Calciner 13: Kiln 13a: Kiln bottom 13b: In front of kiln 14: Clinker cooler 20: Fermentation section

Claims (11)

A method for producing a cement clinker comprising a firing step of producing a cement clinker by firing a raw material of the cement clinker,
By mixing and recycling fermented waste plastics and organic sludge containing anaerobic bacteria that generate hydrogen sulfide from sulfur oxide by fermentation, the sulfur component contained in the mixture is reduced, and It further includes a reduction process for reducing the moisture content,
A method for producing a cement clinker, wherein the mixture obtained in the reduction step is introduced into the firing step.   The method for producing a cement clinker according to claim 1, wherein, in the reduction step, fermentation of the mixture by aerobic bacteria is further performed after fermentation by the anaerobic bacteria.   In the reduction step, the construction waste plastic is crushed by crushing the construction waste plastic, and the fluff or fragment construction waste plastic is mixed with the organic sludge and fermented. The manufacturing method of the cement clinker of Claim 1 or 2 made.   The method for producing a cement clinker according to any one of claims 1 to 3, wherein, in the firing step, the mixture is charged into at least one of a preheater, a calciner, and a kiln bottom of a kiln.   The manufacturing method of the cement clinker as described in any one of Claims 1-4 in which the said organic sludge contains a sewage sludge.   The manufacturing method of the cement clinker as described in any one of Claims 1-5 which performs the said reduction process until the moisture content of the said mixture becomes 40 mass% or less.   The manufacturing method of the cement clinker as described in any one of Claims 1-6 which ferments the said construction waste plastic and the said organic sludge in the said reduction process in the state accumulated so that an open cell may not be formed.   The method for producing a cement clinker according to any one of claims 1 to 7, wherein the construction waste plastic includes gypsum. A step of producing a cement clinker by the method for producing a cement clinker according to any one of claims 1 to 8,
Producing cement from the cement clinker;
A method for producing cement, comprising: A method for treating organic sludge and construction waste plastic,
A mixture of organic sludge and construction waste plastic is fermented by anaerobic bacteria that generate hydrogen sulfide from sulfur oxide by fermentation, reducing sulfur components contained in the construction waste plastic, and water content of the organic sludge A method for treating organic sludge and construction waste plastic, which reduces the rate and obtains a mixture having a low sulfur content and a low water content. The method for treating organic sludge and construction waste plastic according to claim 10, wherein fermentation of the mixture with aerobic bacteria is further performed after fermentation with the anaerobic bacteria.

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