JP2007244957A - Treatment method of waste plastics - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment method of waste plastics which controls the putrefaction of easily decomposable organic substance adhering to waste plastics and utilizes the waste plastics as a fuel for cement calcination. <P>SOLUTION: The treatment method of the easily decomposable organic substance attached waste plastics comprises mixing quicklime containing powder with the easily decomposable organic substance attached waste plastics, sterilizing the mixture with the reaction heat of the moisture included in the easily decomposable organic substance and quicklime and controlling the putrefaction of the easily decomposable organic substance under conditions of moisture removal by the reaction and the high pH environment due to the produced slaked lime, thereby enabling the normal temperature storage of the waste plastics until utilized as a fuel for cement calcination. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a treatment method for using a waste plastic to which an easily decomposable organic substance is attached as a fuel.

  With the enforcement of the Food Recycling Law, waste food is being converted into feed and fertilizer, but easily degradable organic substances such as food residues are attached to the container and packaging plastic separated from the waste food. Waste plastics with readily decomposable organic substances are also discharged in food retailers and restaurants. Furthermore, general waste discharged from households contains many similar waste plastics. Many of this type of waste plastic is simply incinerated or landfilled. However, waste plastics have a calorific value equivalent to that of coal and heavy oil, and simple incineration and landfill are not desirable from the viewpoint of effective use of resources.

  When trying to recycle waste plastic to which easily decomposable organic matter has adhered, the easily degradable organic matter that has been attached will decay in the process of collection and storage, and pollutants such as sewage, odor, and flies will be generated. When stored in an airtight container, leakage of sewage, odor, etc. cannot be sufficiently prevented because the container expands and breaks due to gas generated by decay. In addition, there is a method of storing in a cool and dark place in order to suppress spoilage and ventilating or deodorizing the storage, but it is bulky and requires a large volume and consumes a lot of energy, which is not a desirable method.

  In addition, in order to recycle waste plastic with easily decomposable organic matter attached, it is necessary to carry out processes such as separation, washing, and drying. However, wastewater generated by washing and odors associated with drying and other operations are treated. This requires a lot of cost. However, the plastic obtained through such a process is not an expensive valuable resource. In addition, value-added technologies such as waste plastic gasification, oil conversion, and alternative use of coke have been developed, but the current situation is that the profitability is not met.

  The present invention has been made in view of such circumstances, and provides a method for suppressing the decay of easily decomposable organic substances adhering to waste plastic and using the waste plastic as a cement firing fuel.

  The processing method of the easily decomposable organic substance-attached waste plastic of the present invention is characterized by mixing quick-lime-containing powder with the easily decomposable organic substance-attached waste plastic and suppressing the decay of the easily decomposable organic substance.

  Moreover, this invention includes using easily degradable organic substance adhesion waste plastics which mixed the quicklime containing powder as a raw material for cement baking, and / or a part of fuel. The waste plastic can be put into a calcining furnace and / or kiln bottom in a cement firing process. In addition, the waste plastic can be crushed and fed from a calciner and / or a burner before the kiln. Further, the waste plastic may be put into a sorter to remove excess quicklime-containing powder, and then crushed and put from the burner.

  Moreover, this invention can use the cement baking intermediate goods fractionated from the middle of the cement baking process as quicklime containing powder. Further, as the quicklime-containing powder, a coarse powder fraction separated and recovered by a classifier from a gas extracted from the cement firing step by a chlorine bypass device (Patent Document: Japanese Patent Laid-Open No. Sho 62-252349) of a cement firing facility is used. You can also.

In the present specification, “easy-degradable organic matter” refers to organic matter having a high water content (generally 50% by mass or more) mainly derived from living organisms, such as food residues and straws, and easily perishable at room temperature. It is a concept that includes boiled juice and fruit juice. Therefore, the thing in which inorganic salts, such as salt, were mixed is also included.
JP 62-252349 A

  According to the present invention, it is possible to suppress the decay of readily decomposable organic matter adhering to the waste plastic during storage and handling until the waste plastic is used as a part of the cement firing fuel. There is an advantage that energy and cost for processing are not required. Further, the quicklime-containing powder used in the treatment method of the present invention can be used as a part of the cement raw material, and in particular, separated and recovered from a cement fired intermediate product or a chlorine bypass device separated from the middle of the cement firing process. In the case of using the coarse powder component, there is an advantage that it can be input into the cement firing step without adjusting the components.

Embodiments of the present invention will be described below.
As the easily decomposable organic substance-attached waste plastics subject to the treatment method of the present invention, for example, expired sales lunch boxes and side dishes discharged from retail stores were crushed together with plastic containers and separated from food parts with a vibrating sieve Mention may be made of plastic.

When powder containing quicklime is mixed with readily degradable organic substance-attached waste plastic, the moisture and quicklime react with the easily decomposable organic substance attached to the waste plastic. Evaporate excess moisture. After sterilizing with the heat of reaction accompanying hydration, the slaked lime produced can further reduce the growth of miscellaneous bacteria and reduce spoilage by reducing the water activity and the high pH environment.
CaO + H ₂ O → Ca (OH) ₂

  The mixing device used for the mixing of the present invention is not particularly limited as long as it can mix solids and powders of several centimeters to several tens of centimeters. For example, a raking blade is provided internally. Examples include a rotary mixer, a paddle mixer equipped with a forced stirring mechanism, and a pro-share mixer. The mixture subjected to the treatment of the present invention can be stored at room temperature for one week or more because it prevents decay of easily decomposable organic substances.

  In the present invention, the quicklime-containing powder is obtained by using quicklime as a component and reacting with moisture attached to the readily decomposable organic substance-attached waste plastic to produce slaked lime. The quicklime-containing powder is not particularly limited as long as it contains quicklime in an amount of 20% by mass or more, preferably 40% by mass or more, and components other than quicklime do not adversely affect the production and quality of cement. Specifically, quick lime, calcined dolomite, intermediate powder collected from a suspension preheater, for example, during the cement firing process, and coarse powder separated and recovered from a chlorine bypass device widely used in cement firing equipment Minutes. In the suspension preheater of the cement firing equipment, the cement raw material is heated to 850 to 900 ° C. until reaching the lowest cyclone, and almost all of the lime contained in the cement fired intermediate product becomes quick lime. The content of quicklime in the cement-fired intermediate product fractioned from the lowermost cyclone of the suspension preheater is approximately 40 to 65% by mass. In addition, in the chlorine bypass device widely used to separate alkali metal chlorides from the cement firing process, a part of gas at about 1,000 ° C is extracted from the vicinity of the kiln bottom of the rotary kiln, and the extracted gas is cooled to 600-700 ° C. After that, it is guided to a classifier, and the coarse powder in the gas (particle size is approximately 10 μm or more) is separated and recovered. This coarse powder is a cement calcined intermediate product taken out together with gas from the cement calcining step, and the content of quick lime is approximately 45 to 70% by mass. Cement calcined intermediate products separated or separated and recovered from suspension preheaters and chlorine bypass devices of cement calcining equipment can be input as part of the cement raw material into the cement calcining process without adjusting the components as they are. It is particularly preferable to use it as a quicklime-containing powder in the treatment method of the present invention. Furthermore, the coarse powder separated and recovered from the chlorine bypass device is diverted from what is returned to the cement calcining kiln after separation and recovery, and does not require the installation of a new device for separation and recovery, which is particularly advantageous. .

  The mixing ratio of the readily decomposable organic substance-attached waste plastic and quicklime-containing powder is adjusted so that the moisture content of the easily decomposable organic substance after the reaction between moisture and quicklime is 30% by mass or less. Depending on the amount of moisture adhering to the readily decomposable organic substance-attached waste plastic and the content of quicklime contained in the quicklime-containing powder, 5 parts of quicklime-containing powder is added to 100 parts by weight of the easily decomposed organic substance-attached waste plastic -100 mass parts, 10-50 mass parts is preferable practically. When the mixing amount of quicklime-containing powder is small, sterilization by reaction heat and removal of moisture in easily decomposable organic matter become insufficient, and there is a possibility that the rot during storage of waste plastics cannot be suppressed sufficiently. When the mixing amount of quicklime-containing powder is excessive, it is not only economically inefficient, but also unreacted quicklime reacts with moisture in the air during storage and accumulates heat, resulting in thermal decomposition of waste plastic, There is also a risk of fire. In addition, when there are many easily decomposable organic substances adhering to the waste plastic, it is desirable to separate the waste plastic and the easily decomposable organic substance by a vibration sieve or the like before the treatment of the present invention.

  Waste plastics that have undergone the mixing treatment of the present invention are added with other adjustment components as needed, together with quicklime-containing powder in which most of the lime content has been converted to slaked lime by reaction with moisture contained in readily degradable organic matter. Then, it is put into a calcining furnace and / or kiln bottom of a cement firing facility, used as heat in the cement firing process, or used as a part of a cement firing raw material to become a cement clinker. The means for introducing the waste plastic into the calcining furnace and / or the kiln bottom of the cement firing equipment is not particularly limited as long as it is a means for carrying in solids. For example, direct injection by a hopper, mechanical equipment such as a pusher, screw feeder, etc. Input can be mentioned.

In addition, the waste plastic subjected to the mixing treatment of the present invention is crushed so that the approximate mass is 60 mg or less, and is supplied as a part of cement burning fuel from a calcining furnace of a cement burning facility and / or a burner before the kiln. can do. The burner for blowing waste plastic may be provided with a nozzle in the vicinity of the main fuel burner independent of the main fuel burner. Moreover, it can also blow in with the composite burner integrated with the main fuel burner (for example, the method as described in patent document: Unexamined-Japanese-Patent No. 2000-310410). Although the waste plastic crushing means is not particularly limited, for example, a crusher including a biaxial cutter can be mentioned. Moreover, you may use a heat-melt granulator. When using a hot melt granulator, the quicklime-containing powder, in which most of the lime is converted to slaked lime due to the reaction with moisture contained in the readily decomposable organic matter, becomes the core of the melt granulation, and the granulator It works to prevent waste plastic from welding to the walls of the instrument. If the crusher is heavily worn, the excess quicklime-containing powder may be separated and removed by a sorter such as a vibration sieve before crushing the waste plastic.
JP 2000-310410 A

(Example)
Easily decomposable organic waste plastic:
Expired lunch boxes and side dishes discharged from retail stores were crushed together with plastic containers, and the plastic and food parts were separated using a vibrating sieve. The readily decomposable organic matter such as food residue attached to the plastic part was 30% by mass of the easily decomposable organic matter-attached waste plastic, and the moisture content of the easily decomposable organic matter was 80% by mass. That is, the moisture content in the readily decomposable organic matter-attached waste plastic was 24% by mass.
Quicklime containing powder:
A cement fired intermediate product separated from the bottom stage of the suspension preheater of the cement firing equipment and a coarse powder separated and recovered by a chlorine bypass device were prepared. The quick lime contents of the cement-fired intermediate product and the chlorine bypass separated coarse powder fractionated from the suspension preheater were 60% by mass and 64% by mass, respectively.
Mixing and storage:
20 kg of quicklime-containing powder (cement calcined intermediate product or chlorine bypass coarse powder) is added to 100 kg of readily degradable organic substance-attached waste plastic prepared as described above, and after natural cooling after mixing for 3 minutes with a pro-share mixer, This was packed in a flexible container bag and stored in a warehouse at room temperature (about 25 ° C.). No special change was observed after one week when either the cement-fired intermediate product or the chlorine bypass coarse powder was used.

(Comparative Example 1)
100 kg of the same readily decomposable organic substance-attached waste plastic as used in the examples was packed in a flexible container bag as it was, and stored in a warehouse at room temperature (about 25 ° C.) as in the examples. A rot odor occurred from the second day, and a large amount of flies was observed from the third day.

(Comparative Example 2)
After spraying water to the chlorine bypass coarse powder used in the examples, digesting the lime, and using the dried one instead of the quicklime-containing powder, the flexible container bag was placed in the warehouse. And stored at room temperature (about 25 ° C.). A rot odor occurred from the fifth day.

Claims (7)

  A processing method for easily decomposable organic matter-attached waste plastic, comprising mixing quick-lime-containing powder with easily decomposable organic matter-attached waste plastic, and suppressing the decay of the easily decomposable organic matter.   2. The method for treating easily decomposable organic matter-attached waste plastic according to claim 1, wherein the easily decomposable organic matter attached waste plastic mixed with quicklime-containing powder is used as a raw material for cement firing and / or a part of fuel. .   The easily decomposable organic matter-attached waste plastic mixed with quicklime-containing powder is put into a calcining furnace and / or kiln bottom of a cement firing process, wherein the easily decomposable organic matter-attached waste plastic is treated according to claim 2 Method.   3. The easily decomposable organic substance-attached waste plastic mixed with quicklime-containing powder is crushed, and the crushed material is charged from a calcining furnace and / or a burner before the kiln in the cement firing process. A method for processing readily decomposable organic waste plastics.   The easily decomposable organic matter-attached waste plastic mixed with quicklime-containing powder is put into a sorting machine, and after removing excess quicklime-containing powder, the easily decomposable organic matter-attached waste plastic is crushed. 4. The processing method of easily decomposable organic substance adhesion waste plastics of 4.   The method for treating readily decomposable organic substance-attached waste plastic according to any one of claims 1 to 5, wherein an intermediate product of cement fired from the middle of the cement firing step is used as the quicklime-containing powder.   6. The coarse powder separated and recovered by a classifier from the gas extracted from the cement firing process by the chlorine bypass device of the cement firing facility is used as the quicklime-containing powder. Of easy-to-decompose organic plastic waste plastic.