JP2014062028A - Utilization method of plastic waste in firing furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a utilization method of a plastic waste in a firing furnace in which when the plastic waste is used as fuel in the firing furnace (rotary kiln or the like) to produce a burned product (calcium oxide, burnt dolomite or the like), attachment generation to a furnace wall part of an inside of the furnace by an impurity component (ash) included in the plastic waste can be prevented.SOLUTION: A utilization method of a plastic waste in a firing furnace is a method in which when a raw material in the firing furnace is heated by burning of fuel to produce a burned product, the plastic waste is used as a part of the fuel, and is characterized in that the plastic waste is added with an inorganic compound, and glass transformation temperature of a mixture of ash included in the plastic waste and the added inorganic compound is raised to at least 1250°C.

Description

  The present invention relates to a method in which waste plastic, which has not been used as a fuel so far, is burned by being blown into a kiln such as a rotary kiln for producing a calcined product such as quicklime, calcined dolomite, and Portland cement, and used as a fuel.

  Waste plastic, which is a used plastic, can be used as a heat source having a high calorific value, but has conventionally been subjected to landfill treatment and incineration treatment. However, the waste plastic has a low bulk density, and therefore, there are problems that the landfill disposal site is quickly approaching, and environmental problems such as generation of harmful components when the waste plastic is incinerated. Therefore, there is a growing demand for recycling of waste plastic. For example, in the steel industry, waste plastic is recycled in large quantities by using waste plastic as a carbon material in blast furnaces and coke ovens.

  As a technique paying attention to the fact that waste plastic can be used as a heat source having a high calorific value, a method for producing a cement clinker using waste plastic is known (for example, see Patent Document 1). However, in the technique described in Patent Document 1, cement clinker can be manufactured at low cost by adding waste plastic to the raw material in the rotary kiln for manufacturing cement clinker, but the specific method for adding waste plastic is unknown. It is.

  Conventionally, it is well known that quick lime, calcined dolomite, Portland cement and the like are manufactured using a rotary kiln. The rotary kiln is convenient for burning various fuels because the space through which the combustion gas passes is relatively large relative to the charge.

  In a rotary kiln, quick lime and calcined dolomite are produced by supplying limestone and raw dolomite from a silo to a great preheater for preheating the raw ore, preheating with exhaust gas from the rotary kiln, and then charging the rotary kiln.

  A rotary kiln is a cylindrical heating furnace in which a refractory is lined with a circular iron skin, and rotates around a cylindrical axis at a constant speed. The charged limestone and the like pass through the rotated furnace and move toward the exit. The raw material charging inlet is inclined 3/100 to 4/100 upward with respect to the outlet direction, and the charged limestone or the like moves in the furnace while rotating in the furnace while being fired.

  At the outlet, a device for supplying fuel is provided. The fuel is blown into the furnace through a nozzle and burned with air to keep the furnace at a high temperature of 1000 ° C. or higher. The limestone and raw dolomite ore are baked by this combustion heat and changed to quick lime or baked dolomite.

  The air for fuel combustion exchanges heat with quicklime and calcined dolomite and is blown into the rotary kiln as high-temperature air to burn the fuel. The temperature inside the rotary kiln is around 600 ° C on the outlet side, and the part where the flame where the fuel burns is partially 1500 ° C or higher, and the temperature decreases with the decomposition reaction of limestone and dolomite, and on the gas outlet side Decreases to about 1000 ° C. This high temperature exhaust gas of about 1000 ° C. is used for preheating limestone and dolomite.

  The above is the outline of the rotary kiln facility for producing quicklime or calcined dolomite. Conventionally, rotary kilns mainly use pulverized coal as fuel, and partly use heavy oil. However, these fuels are all expensive. By using waste plastic having a high calorific value as fuel, quick lime or calcined dolomite can be manufactured at a lower cost, and it is expected to lead to fuel reduction and resolution of environmental problems.

  In the rotary kiln, waste plastic is blown into the rotary kiln together with the main fuel and burned, and (a) a step of making the waste plastic particles into a fine bundle flow; and (b) a fine bundle flow of the waste plastic particles in the main fuel. There is known a method of burning waste plastic in a rotary kiln having a step of blowing and burning as fuel into the rotary kiln from the upper side of the blowing position (see, for example, Patent Document 2). In Patent Document 2, it is preferable to blow the waste plastic particles blown into the rotary kiln as a fine bundle flow so that the landing range in the furnace is in the range of 1/10 to 2/3 of the flame length of the main fuel. It is said that.

  Patent Document 3 describes the use of waste plastic as an auxiliary fuel for cement firing. In the technique described in Patent Document 3, in order to enhance the combustibility of waste plastic, liquid waste is mixed in advance, and the slurry mixture is sent to an auxiliary fuel outlet provided in a part of the main fuel burner of the rotary kiln. This is a method in which the fuel is supplied and blown into the rotary kiln from the outlet and burned.

Japanese Unexamined Patent Publication No. Sho 46-15037 Japanese Patent Laid-Open No. 8-280533 JP 2007-84434 A

Patent Documents 1 to 3 describe a method for increasing the effective utilization rate (combustibility) of waste plastic in a firing furnace, for example, a method for defining the particle size of waste plastic to be blown, waste A method in which plastic is blown into the high-temperature part of the main burner, or a method in which it is mixed with liquid waste and blown in. These Patent Documents 1 to 3 focus on only combustibility, but various impurities are mixed in plastics that are usually discarded in the process of being discarded. For example, as the impurities, earth and sand, glass, metal, food residue and the like can be raised. In addition, industrially used plastics are mixed with pigments, extenders, fillers, and the like according to their applications. For example, they _{may, SiO 2, Al 2 O 3} , CaO, MgO, oxides such as TiO ₂ and the like. When waste plastic containing impurities is used as fuel for limestone firing furnaces or cement firing furnaces, it adheres to the furnace wall in the furnace due to melting of the impurities, and kiln rings are generated, so stable operation cannot be continued. . When a kiln ring is generated, the firing furnace is cooled and the kiln ring is removed, resulting in a decrease in operating rate.

  This invention is made | formed in view of the above situations, and when manufacturing a baked product (quick lime or baked dolomite etc.) using waste plastic as a fuel of a baking furnace (rotary kiln etc.), it is made into a waste plastic. It is an object of the present invention to provide a method for using waste plastic in a firing furnace that can prevent the generation of deposits on the furnace wall in the furnace due to the contained impurity components (ash).

  The inventors of the present invention have made extensive studies on a method for preventing the generation of deposits (generation of kiln rings) on the furnace wall when waste plastic is used as fuel in a baking furnace (such as a rotary kiln). As a result, the glass transition temperature of the ash (Ash component) contained in the waste plastic is measured in advance, and inorganic compounds (alumina, silica, calcia, magnesia) are added so that the glass transition temperature is 1250 ° C or higher. Then, it was found that by blowing waste plastic into the position in the firing furnace, the melting of ash (rubber state, liquid state) is suppressed and the generation of kiln rings can be prevented appropriately. Specifically, it was found that the formation of deposits can be prevented by adding (alumina, silica, calcia, magnesia).

  As for the above glass transition temperature, when an amorphous solid is heated, it does not exhibit fluidity at low temperatures, but the viscosity rapidly decreases and fluidity increases at a certain temperature. This temperature is called the glass transition temperature. An amorphous state lower than the glass transition temperature is referred to as a glass state, and at a temperature higher than the glass transition temperature, the substance is in a liquid or rubber state. In other words, the glass transition temperature is the temperature at which the liquid or rubber state returns to the glass state. That is, the glass transition temperature is not the melting point but the temperature at which the liquid phase starts to be generated, and is lower than the melting point. Incidentally, the glass transition temperature is measured with a differential thermal analyzer at a heating rate of 10 ° C./min.

  The present invention is based on the above findings and has the following characteristics.

  [1] A method of using a waste plastic as a part of the fuel when a raw material in a firing furnace is heated by combustion of fuel to produce a fired product, and an inorganic compound is added to the waste plastic, A method for using waste plastic in a firing furnace, wherein the glass transition temperature of a mixture of ash contained in waste plastic and an added inorganic compound is increased to 1250 ° C or higher.

  [2] The method for using waste plastic in a firing furnace as described in [1], wherein the inorganic compound is added to granulate waste plastic.

  [3] In the firing furnace according to [2], when the waste plastic is granulated by adding the inorganic compound, the waste plastic and the inorganic compound are simultaneously supplied to a ring die and granulated. To use waste plastic.

  [4] The firing furnace according to any one of [1] to [3], wherein the inorganic compound is one or more selected from silica, magnesia, and calcia. How to use waste plastic.

  [5] The method for using waste plastic in a firing furnace according to any one of [1] to [4], wherein the raw material in the firing furnace is limestone or dolomite.

  According to the present invention, when waste plastic is used as a fuel for a calcining furnace (rotary kiln or the like) such as limestone, dolomite, or cement, it is possible to prevent generation of deposits on the furnace wall in the furnace due to impurities contained in the waste plastic. Therefore, it is possible to stably operate without reducing the operating rate of the baking furnace, and to manufacture a fired product at a low cost.

Explanatory drawing which shows the condition in a rotary kiln. Waste plastic processing flow for rotary kilns. Schematic of an example of a granulator used in the compression molding granulation method (ring die granulator). The graph which shows the relationship between the addition rate at the time of adding an inorganic compound to the ash content contained in waste plastic, and a glass transition temperature.

  One embodiment of the present invention will be described.

  Here, the firing furnace used in the present invention is a furnace for firing the raw material by heating the raw material and fuel in a container, and specifically includes a rotary kiln, a Merz furnace, and the like. Now, a case where a rotary kiln is used will be described as an example. And as a baked product, quick lime or baked dolomite shall be manufactured.

Moreover, the waste plastic used as a part of the fuel of the baking furnace is a used plastic, and is usually in a state where foreign substances or a plurality of types of plastics are mixed. General waste plastic, which is a waste from general households, is often contaminated with foreign substances, and usually requires pretreatment when used for recycling, but industrial waste plastics are generally less contaminated with foreign substances and have many types of plastics. It may not be a mixed state. Pigment Such waste plastics, and fillers and the like are contained, as the ash concentration in industrial analysis, several to several tens of percent, in terms of oxide as the composition of the ash, SiO _2, Al ₂ O ₃ , CaO, MgO, Fe ₂ O ₃ , TiO ₂ , Na ₂ O, K ₂ O, etc., halogen such as chlorine is contained.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

First, FIG. 1 (a), (b) is explanatory drawing which shows the condition in a rotary kiln. As shown in FIG. 1A, the raw material 3 (limestone or dolomite rough (CaCO ₃ .MgCO ₃ )) supplied to the rotary kiln 1 from the inlet 2 is composed of the main fuel A blown into the burner 5 on the rotary kiln outlet 4 side. Heated by the combustion gas generated by the reaction of the combustion air B, it becomes quick lime or calcined dolomite and moves to the outlet 4. The residence time of the raw material is generally about 60 minutes. In FIG. 1, the landing range of the waste plastic C blown into the rotary kiln 1 as fuel from the waste plastic blow-in port 6 in the rotary kiln (inside the furnace) is mainly viewed from the rotary kiln outlet in order to improve combustibility. It is in the range of 1/2 to 2/3 of the length of the fuel flame 7. The raw material (limestone or dolomite) 3 is charged into the rotary kiln 1, de-CO ₂ is removed by the high-temperature gas generated by the combustion of the opposing main fuel A and / or waste plastic C, and the calcined product (quick lime or calcined dolomite) 9 is obtained. It is recovered from the outlet 4 of the rotary kiln 1.

  The solid (raw material) 3 and gas temperature in the rotary kiln 1 are shown in the graph of FIG. As shown in FIG. 1B, the raw material (limestone or dolomite) 3 is gradually heated in the rotary kiln 1, and in the case of limestone, it is decarboxylated at about 900 ° C. and converted to quick lime. Decarboxylation occurs from about 550 ° C.

  On the other hand, the waste plastic C used as the fuel for the rotary kiln generates a high-temperature gas by combustion with air (preheated air), but the ash contained in the waste plastic C becomes a combustion residue. A part of the combustion residue is discharged out of the furnace together with the calcined product (quick lime or calcined dolomite) 9 (some of them react with quick lime or calcined dolomite to form a composite oxide). The remaining combustion residue remains in the pores of the furnace wall bricks or the uneven portions generated by the brick being worn with the movement of the raw material 3, and melts and adheres as deposits when the furnace wall bricks are hot. Furthermore, this becomes a nucleus and deposits grow, producing a kiln ring in which stable operation is impossible.

Therefore, in this embodiment, when waste plastic C is used as fuel, the glass transition of ash contained in waste plastic C in advance in order to prevent the formation of deposits (generation of kiln rings) on the furnace wall. The temperature is measured, an inorganic compound is added so that the glass transition temperature is 1250 ° C. or higher, and granulated waste plastic C is blown. As an inorganic compound to be added, MgO, SiO ₂ , CaO, or the like may be used as long as it does not cause a problem in the steel making process using quick lime. As a result, melting (liquid phase) of ash is suppressed, and the generation of deposits (generation of kiln rings) on the furnace wall can be accurately prevented.

  Next, a specific method of using waste plastic in a rotary kiln will be described with reference to FIG. The waste plastic is preferably used after being granulated, and the method for granulating the waste plastic will be described in detail below.

  According to the processing flow shown in FIG. 2, waste plastic is crushed by a crusher in the crushing step 21, and then foreign matter removal using magnetic separation, wind separation, etc. and cleaning with water are performed in the foreign matter removal step 22, and foreign matter other than plastic can be produced After removing as much as possible, an inorganic compound is added to the waste plastic so that the glass transition temperature is 1250 ° C. or higher, and the granulated product is processed into a granulated product in the granulating step 23. The obtained granulated material is blown into the rotary kiln by the blowing means in the blowing step 24 and is baked in the rotary kiln in the baking step 25.

  At that time, in the granulation step 23, the crushed material from which the foreign matter has been removed is extruded and granulated to obtain a granulated product. The granulated product thus obtained has very few foreign substances, has a constant property (narrow particle size range and stable quality), and is suitable as a fuel to be injected into a rotary kiln. Further, by adding an inorganic compound, it is possible to produce a strong granulated product with less pulverization during the transportation (blowing) process.

  In the granulation step 23, a known method used when granulating ordinary waste plastics may be used. For example, a granulation method such as the compression molding granulation method shown below can be used. This compression molding granulation method is particularly suitable for the granulation of a film-like waste plastic.

  In the compression molding granulation method, waste plastic is granulated by compressing and extruding waste plastic from a hole of a ring die having a plurality of die holes penetrating therethrough. For example, a compression molding apparatus including a ring die having a plurality of die holes penetrating the entire periphery thereof, and a rolling roller that is rotatably disposed in contact with the inner peripheral surface of the ring die inside the ring die The waste plastic thrown into the ring die is pressed into the die hole of the ring die while being compressed and crushed by the rolling roller with the inner peripheral surface of the ring die, and passes through the die hole. By cutting or scraping the plastic molded product extruded to the outer surface side of the ring die from the outer surface of the ring die, a granular plastic molded product as a furnace blowing material is obtained. A plastic molded product (granulated product) is obtained mainly by at least a part of the waste plastic being semi-molten or melted by frictional heat in the die hole and then solidified.

  As a granulating apparatus used in the compression molding granulation method, for example, a ring die having a plurality of die holes penetrating the entire circumference and rotatably supported by the apparatus main body and rotated by a driving apparatus, and an apparatus main body It is known to have one or two or more rolling rollers that are rotatably supported and arranged in contact with the inner peripheral surface of the ring die inside the ring die. The rolling roller is pressed and granulated into the die hole of the ring die while being compressed and crushed between the inner peripheral surface of the ring die.

  A schematic view of an example of a granulating apparatus used in the compression molding granulation method is shown in FIG. This plastic compression molding apparatus includes a ring die 11 having a plurality of die holes 10 penetrating the entire periphery thereof, and a rolling element disposed rotatably inside the ring die 11 so as to contact the inner peripheral surface of the ring die. The roller 12 (12a, 12b) and the cutter 13 arrange | positioned on the outer side of the ring die 11 are provided.

  The ring die 11 is composed of a ring body having an appropriate width, is rotatably supported by a device body (not shown), and is rotationally driven by a drive device (not shown). A plurality of die holes 10 are provided in the circumferential direction and the width direction of the ring die 11. These die holes 10 are provided so as to penetrate between the inner side (inner peripheral surface) and the outer side (outer peripheral surface) of the ring die 11 along the radial direction of the ring die 11. The hole diameter (diameter) of the die hole 10 is determined according to the size (diameter) of the granular plastic molding to be granulated, but is usually about 2 to 15 mm. The length of the die hole 10 (the thickness of the ring die 11) is usually about 30 to 150 mm.

  The rolling rollers 12a and 12b are rotatably supported by the apparatus main body and are disposed in a state of facing the inner side of the ring die 11 by 180 °. These rolling rollers 12a and 12b are non-driving free roller bodies and are in contact with the inner peripheral surface of the ring die 11, and thus rotate with the rotation of the ring die 11 due to friction with the inner peripheral surface. The number of the rolling rollers 12 is arbitrary, and one or three or more may be provided.

  The cutter 13 is provided so that the cutting edge thereof is in contact with the outer peripheral surface of the ring die 11 or located in the vicinity of the outer peripheral surface, and a plastic molded product that is extruded in a rod shape from the die hole 10 to the outside of the ring die 11 is appropriately used. It is cut into a long length (or scraped off from the outer peripheral surface of the ring die).

  In the plastic compression molding apparatus as described above, the ring die 11 is driven to rotate in the direction of the arrow in the drawing, and the rolling rollers 12a and 12b are rotated accordingly. Waste plastic is put inside, and the thrown plastic is mixed in the ring die 11 and is compressed and crushed between the inner peripheral surface of the ring die 11 by the rolling rollers 12a and 12b. It is pushed into the die hole 10. The waste plastic pushed into the die hole 10 passes through the die hole and is sequentially extruded in the form of a rod on the outer surface side of the ring die 11, and this plastic molding is appropriately lengthened by the cutter 13. The cylindrical plastic granulated material 15 is obtained by being cut into pieces. Reference numeral 16 denotes a discharge port.

  The inorganic compound may be added to the waste plastic in advance before entering the granulation step 23, or as shown in FIG. Also good.

  The granulated product of waste plastic produced by the above method is used as a part of fuel in a rotary kiln for producing quicklime or calcined dolomite. As a method of using as fuel, waste plastic granulated material may be blown into the rotary kiln using a lance or a dedicated burner by a normal air flow transportation method.

  At that time, the glass transition temperature of the ash content of the waste plastic granule is measured in advance, and the addition rate of the inorganic compound is adjusted so that the glass transition temperature is 1250 ° C. or higher. When the glass transition temperature of the ash content of the waste plastic granulated product is 1250 ° C. or higher, it is not necessary to add an inorganic compound. In other words, the present invention is effective when the glass transition temperature of the ash content of the waste plastic granule is less than 1250 ° C.

  Incidentally, FIG. 4 shows the relationship between the inorganic compound addition rate and the glass transition temperature measurement result when an inorganic compound is added to the ash contained in the waste plastic. In addition, an addition rate is a ratio with respect to the ash content contained in waste plastic. The influence on the glass transition temperature (the amount of increase in the glass transition temperature with respect to the addition rate of the inorganic compound) varies depending on the inorganic compound to be added, and is as follows from the slope of FIG.

MgO: 134 ° C / 10% added, CaO: 12 ° C / 10% added, SiO ₂ : 22 ° C / 10% added

  Examples of the present invention will be described.

[Invention Example 1]
According to the flow of FIG. 2, the waste plastic is granulated by using the granulating apparatus (ring die granulating apparatus) shown in FIG. 3 to obtain a plastic molding (granulated product), and then the rotary kiln shown in FIG. Limestone was calcined using (rotary kiln for calcining lime).

  The waste plastic used is waste from general households. In the state where multiple types of plastic and foreign materials are mixed, polyethylene 32 mass%, polypropylene 31 mass%, polystyrene 22 mass%, polyvinyl chloride 4 mass%, and others (paper, etc.) ) 11 mass% and contained 1.32 mass% of chlorine. As a result of industrial analysis, the ash content is 4.66%. Table 1 shows the chemical composition of waste plastic. The waste plastic was ashed in air at 950 ° C., and the glass transition temperature of the ash was measured at 10 ° C./min with a differential thermal analyzer.

  The waste plastic was granulated by supplying it to a granulator at a condition of 1.0 t / h and MgO at 4.7 kg / h (10% based on ash). The granulator has a ring die inner diameter of 840 mm, a width of 240 mm, a ring die thickness (die length) of 60 mm, a rolling roller diameter of 405 mm, 10,000 holes with a die diameter of 6 mm, a diameter of about 6 mm, and a length of about 10 to 20 mm. A cylindrical granule was produced. The produced waste plastic was incinerated at 950 ° C. in the air, and the glass transition temperature of the ash was measured at a heating rate of 10 ° C./min with a differential thermal analyzer.

  This plastic granulated product was blown into a rotary kiln for calcining lime (inner diameter: 3.2 m, length: 53 m, inclination angle: 1/1000) with a calcined lime production amount of 500 t / day (main fuel is heavy oil, calorific value) : 9800 kcal / kg). The position of the main fuel burner at the exit of the rotary kiln was the center of the furnace, and the plastic granulated material injection port (65A) was installed on the main burner at 0.2 m (extrusion length into the furnace: 1.0 m). That is, the blowing conditions in FIG. 4 described above (the position of the blowing port at the rotary kiln quicklime outlet is 0.2 m above the furnace center, the protruding length into the furnace is 1.0 m, and the kiln inclination angle is 1/1000). The same. The waste plastic blowing angle was set to 0 degree upward. The carrier gas flow rate of the plastic granulated product was set to 26 m / s. As a result, the amount of deposits on the furnace wall was negligible, and stable operation for 60 days was possible.

[Invention Example 2]
As an inorganic compound, it was carried out in the same manner as Example 1 except that MgO was added in an amount of 2.3 kg / h (5% based on ash). This plastic granulated product was incinerated at 950 ° C. in the air, and the glass transition temperature of the ash was measured at a heating rate of 10 ° C./min with a differential thermal analyzer. As a result, the generation of deposits on the furnace wall was negligible, and stable operation for 45 days was possible.

[Invention Example 3]
As an inorganic compound, it was carried out in the same manner as Example 1 except that 18.6 kg / h (40% based on ash) of CaO was added. This plastic granulated product was incinerated in air at 950 ° C., and the glass transition temperature of the ash was measured at a heating rate of 10 ° C./min with a differential thermal analyzer. As a result, the generation of deposits on the furnace wall was negligible, and stable operation for 50 days was possible.

[Invention Example 4]
As an inorganic compound, it was carried out in the same manner as Example 1 except that 23.3 kg / h (50% based on ash) of CaO was added. This plastic granulated product was incinerated at 950 ° C. in the air, and the glass transition temperature of the ash was measured at a heating rate of 10 ° C./min with a differential thermal analyzer. As a result, the generation of deposits on the furnace wall was negligible, and stable operation for 50 days was possible.

[Invention Example 5]
As an inorganic compound, it was carried out in the same manner as Example 1 except that 9.3 kg / h (20% based on ash) of SiO ₂ was added. This plastic granulated product was incinerated at 950 ° C. in the air, and the glass transition temperature of the ash was measured with a differential thermal analyzer at a heating rate of 10 ° C./min. As a result, the generation of deposits on the furnace wall was negligible, and stable operation for 45 days was possible.

[Comparative Example 1]
A waste plastic granulated product was produced in the same manner as in Example 1 except that no inorganic compound was added, and was blown into a rotary kiln. The furnace wall temperature at the dropping position at that time was about 1280 ° C., which exceeded the glass transition temperature (1210 ° C.) of the ash content of the waste plastic.

  And when the plastic granulated material was blown for 7 days, the kiln ring produced | generated to 5-8m from the furnace front, the plastic blowing was stopped for the deposit removal, and the rotary kiln was stopped.

[Comparative Example 2]
A waste plastic granulated material was produced as an inorganic compound in the same manner as in Example 1 except that MgO was 0.9 kg / h (2.0% based on ash content), and was blown into a rotary kiln. This plastic granulated product was incinerated at 950 ° C. in air, and the glass transition temperature of the ash was measured at a heating rate of 10 ° C./min with a differential thermal analyzer.

  And when the plastic granulated material was blown for 14 days, the kiln ring produced | generated to 5-8m from the furnace front, the plastic blowing was stopped for adhering matter removal, and the rotary kiln was stopped. The height of the kiln ring was 20 cm at maximum, and the kiln inner diameter was reduced to 2.8 m.

  Table 2 shows the implementation conditions (inorganic compound addition rate and the like) and the implementation results (glass transition temperature) of Examples 1 to 5 of the present invention and Comparative Examples 1 and 2.

1 Rotary kiln 2 Entrance 3 Raw material (limestone or dolomite)
4 Exit 5 Burner 6 Waste plastic inlet 7 Flame of main fuel 9 Burned product (quick lime or calcined dolomite)
DESCRIPTION OF SYMBOLS 10 Die hole 11 Ring die 12 (12a, 12b) Rolling roller 13 Cutter 14 Input port 15 Plastic granulated material 16 Discharge port 21 Crushing process 22 Foreign substance removal process 23 Granulation process 24 Blowing process 25 Baking process A Main fuel B Combustion Air C Waste plastic

Claims (5)

  A method of using waste plastic as a part of the fuel when heating the raw material in the firing furnace by combustion of fuel to produce a fired product, and adding an inorganic compound to the waste plastic, A method for using waste plastics in a firing furnace, wherein the glass transition temperature of a mixture of ash contained in the mixture and added inorganic compound is increased to 1250 ° C. or higher.   The method for using waste plastics in a firing furnace according to claim 1, wherein the waste plastics are granulated by adding the inorganic compound.   The waste plastic in the firing furnace according to claim 2, wherein when the waste plastic is granulated by adding the inorganic compound, the waste plastic and the inorganic compound are simultaneously supplied to a ring die and granulated. How to Use.   The method for using waste plastics in a firing furnace according to any one of claims 1 to 3, wherein the inorganic compound is one or more selected from silica, magnesia, and calcia.   The method for using waste plastic in a firing furnace according to any one of claims 1 to 4, wherein the raw material in the firing furnace is limestone or dolomite.

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