WO2010030038A1

WO2010030038A1 - Method for producing pulverized waste plastic and solid fuel or mineral reduction material

Info

Publication number: WO2010030038A1
Application number: PCT/JP2009/066205
Authority: WO
Inventors: 梶岡正彦; 浅沼稔; 鶴田秀和
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2008-09-12
Filing date: 2009-09-10
Publication date: 2010-03-18
Also published as: KR101134809B1; KR20110036771A; CN102149526A; JP2010089500A; CN102149526B; JP4775485B2

Abstract

Provided is a method for producing a pulverized waste plastic wherein it is possible to produce at a low cost and with improved productivity a pulverized product by micropulverization of waste plastic. The method for producing a pulverized waste plastic is characterized in that waste plastic is kneaded at a shear speed of 100 (1/second) or greater as it is being melted at a temperature that is the softening and melting temperature or greater, preferably 160°C, but is a temperature at which flammable decomposition gases are not generated, preferably 270°C or lower, and then is cooled and solidified and the solid product is pulverized. Melting and kneading are preferably performed using an extruder, particularly a biaxial extruder.

Description

Method for producing waste plastic crushed material and solid fuel or ore reducing material

The present invention relates to a method for producing a waste plastic pulverized product for producing ore reducing material, solid fuel and the like by reprocessing waste plastic.

In recent years, methods for producing ore reducing materials, solid fuels, and the like from waste plastics have been studied as a solution for effective use of waste plastics. This is because pulverization of plastic can dramatically improve combustibility and become a useful fuel resource.

The conventional technology for converting plastic to solid fuel is, for example, directly pulverizing plastic with a pulverizer (see, for example, Non-Patent Document 1). However, in this method, hard plastic can only be pulverized to a particle size of 1 to 2 mm, and this pulverization requires a lot of time and cost, and fiber and film plastics are difficult to pulverize. For this reason, there is a problem that the process must be pulverized after being melted and solidified, resulting in a complicated process.

In addition, it is known that when waste plastic is finely pulverized, it can be made into a fuel that can be used as a combustion furnace such as a power generation boiler (see, for example, Patent Document 1). Is not described, and there is no technical disclosure regarding improvement of grindability of waste plastic itself.

Plastic having a particle size of 2000 μm or less is excellent as a solid fuel, and is known to be produced by a dry pulverization method or a wet pulverization method (for example, see Patent Document 2). In particular, it is said that a jet mill or a vibration ball mill is suitable as a method for obtaining fine powder, but a technique for improving the pulverization property of waste plastic itself is not known.

On the other hand, for example, when waste plastic discharged from homes is used as a reducing material such as a blast furnace reducing material or fuel, chlorine-containing plastics such as polyvinyl chloride (hereinafter referred to as PVC) are mixed in the waste plastic. Therefore, when used as it is, there are problems such as generation of hydrogen chloride and corrosion of the furnace. For this reason, the technique (for example, refer patent document 3) which isolate | separates and removes chlorine containing plastics, such as PVC, performs a granulation process, and obtains a granular plastic molding is known.

In addition, as a technology for pulverizing waste plastic containing chlorine-containing waste plastic, waste plastic is heated, dechlorinated, cooled and solidified, then pulverized and put into a furnace ( For example, techniques such as Patent Document 4 and Patent Document 5) are known.

Japanese Patent Laid-Open No. 7-111992 Japanese Patent Laid-Open No. 4-332792 JP 2002-67029 A JP-A-11-192469 JP 2006-241442 A

In general, plastics are excellent in impact resistance, so it is very difficult to pulverize them as they are. Especially when pulverizing to a particle size of 0.5 mm or less, the pulverization time is lengthened or repeatedly put into the pulverizer several times. The method of doing is taken. In this case, depending on the type of pulverizer, there are cases where the plastic is heated by shearing heat generation during pulverization and melts or the pulverized product becomes fibrous. In order to prevent this phenomenon, it is conceivable to cool the pulverizer or the pulverized product, but the equipment cost and the operating cost increase.

So-called freeze pulverization is also an effective method for pulverizing plastic. That is, it is a method in which a plastic is cooled to a temperature range where a general plastic causes brittle fracture, for example, tens of degrees below zero, and then pulverized. However, since this method requires the plastic to be cooled in advance, the equipment cost and operation cost increase.

According to the so-called waste plastic melting and dechlorination method including the methods described in Patent Document 4 and Patent Document 5 described above, PVC after dechlorination becomes carbonized and embrittled. It is possible to improve. However, it is necessary to treat exhaust gas containing chlorine generated by dechlorination treatment, which is expensive. Although it is possible to recover chlorine from the exhaust gas and effectively use it as hydrochloric acid, it also increases the equipment cost. In order to produce finely pulverized waste plastic at a low cost, it is important to reduce the equipment cost and improve the productivity.

Accordingly, the object of the present invention is to solve such problems of the prior art, and to pulverize waste plastic at a low cost to obtain a pulverized product, and to improve the productivity of the pulverized product. It is in providing the manufacturing method of a thing.

The features of the present invention for solving such problems are as follows.
(1) Waste plastic is melted at a temperature higher than the softening melting temperature and at a temperature at which flammable decomposition gas is not generated, and further kneaded at a shear rate of 100 (1 / second) or more, and then cooled and solidified to obtain a solidified body. A method for producing a waste plastic pulverized product, wherein the solidified product is pulverized.
(2) The method for producing a waste plastic pulverized product according to (1), wherein the softening and melting temperature is 160 ° C., and the temperature at which the combustible decomposition gas is not generated is 270 ° C. or less.
(3) The waste plastic is melted at 160 ° C. to 270 ° C., kneaded at a shear rate of 100 (1 / second) or more, then cooled and solidified to form a solidified body, and the solidified body is pulverized. The manufacturing method of waste plastic ground material.
(4) The method for producing a pulverized waste plastic according to any one of (1) to (3), wherein melting and kneading are performed using an extruder.
(5) The method for producing a waste plastic pulverized product according to (4), wherein the extruder is a twin screw extruder.
(6) Any one of (1) to (5), wherein solid particulates other than waste plastic are mixed and kneaded together with waste plastic before and / or during melting and kneading of waste plastic A method for producing a waste plastic pulverized product according to claim 1.
(7) The method for producing a pulverized waste plastic according to any one of (1) to (6), wherein the particle size of the solidified body that has been pulverized by passing through a sieve is adjusted.
(8) An ore reducing material or a solid fuel which is a pulverized product produced in any one of (1) to (7).
(9) The ore reducing material or solid fuel according to (8), which passes through a sieve having an aperture of 0.5 mm.

According to the present invention, a solid fuel or ore reducing material having excellent combustibility can be produced at low cost using waste plastic as a raw material without providing facilities for treating exhaust gas from waste plastic. Productivity of waste plastic crushed material is also improved.

Also, by using the waste plastic processing method of the present invention, a large amount of waste plastic can be economically implemented.

It is a graph which shows the relationship between the temperature which melt | dissolves waste plastic, and the decomposition rate of plastic. It is a graph which shows the relationship between the shear rate of a plastic, and a viscosity.

The present invention cools waste plastics and container packaging materials contained in municipal waste, industrial waste, general waste, etc., and waste plastics generated in the process of dismantling electrical appliances, automobiles, etc. after heating, melting and kneading. The present invention relates to a technology for producing a solidified body, pulverizing the solidified body, and producing a solid fuel, an ore reducing material, and the like. As described above, waste plastic is a mixture of a plurality of types of plastics, and it is effective to melt and knead various types of plastics as a method for improving the pulverization properties of waste plastics and easily pulverizing them. Since most waste plastics contain chlorine by mixing PVC or the like, conventionally, waste plastic is melted and kneaded at a high temperature that generates chlorine gas to generate chlorine-containing gas, Dechlorination treatment to remove the chlorine component was performed.

However, for sufficient dechlorination, for example, when treated at a temperature of 300 ° C. or higher, PET (polyethylene terephthalate) and paper / wood (cellulose, hemicellulose, lignin), etc. contained in the waste plastic simultaneously with the dehydrochlorination reaction Pyrolysis and hydrolysis generate flammable decomposition gas (flammable organic matter). Most of these combustible cracked gases are solid at room temperature and generally have sublimation properties, so that the structure of the collection device becomes complicated and it is necessary to treat them separately. Furthermore, the collected material often contains about several percent of chlorine, and is difficult to become a fuel.

Therefore, in the present invention, a method for melting and kneading at a relatively low temperature was examined in order to prevent generation of flammable decomposition gas generated when melting and kneading waste plastic. The problem was that chlorine could not be removed sufficiently from waste plastic when melted at a relatively low temperature, but if waste plastic with low chlorine content is used, waste plastic with low chlorine concentration without dechlorination treatment. A solidified body and a pulverized product can be produced. Therefore, in the present invention, it is preferable to use a waste plastic having a low chlorine content (for example, a chlorine concentration of 2 mass% or less). Further, as a result of examination, it has become clear that a certain amount of chlorine may be allowed, and dechlorination treatment is not necessarily required in all cases. For example, when waste plastic pulverized material is used as ore reducing material for a blast furnace, the slag component present in the furnace reacts with chlorine to be immobilized, so dechlorination can be omitted depending on the amount of chlorine contained in the waste plastic. It turns out that. In addition, even if the chlorine content of the waste plastic is high and the chlorine content of the pulverized product is high, it does not mean that it cannot be used as an ore reducing material or solid fuel. By adjusting appropriately according to this, generation | occurrence | production of problems, such as corrosion of a furnace, can be avoided. Therefore, even if it is a waste plastic pulverized product manufactured without dechlorination, there is no practical problem if it is sufficiently pulverized.

On the other hand, by performing the melting treatment at a relatively low temperature, the PVC after dechlorination becomes carbonized, and the effect of embrittlement cannot be obtained, so the pulverization property of the produced waste plastic solidified body is lowered, and the productivity is reduced. Decreasing becomes a problem. Regarding this, it has been found that by sufficiently increasing the degree of kneading in the melting and kneading process of the waste plastic, it is possible to suppress the decrease in pulverization to a level where there is no problem. At the same time, by melting at low temperature and preventing the generation of flammable cracked gas, the components that should have been removed as flammable cracked gas can be taken in as waste plastic crushed material, improving yield. In addition, the productivity of the pulverized product is improved as a whole.

As described above, by performing the heat treatment of the waste plastic at a temperature equal to or higher than the softening and melting temperature and not generating flammable decomposition gas, the solid yield after the treatment is increased. At this time, the residual chlorine concentration in the solidified material after the treatment is somewhat higher. For example, when used as a reducing material in a blast furnace, it reacts with calcium present in the blast furnace, so even if the chlorine is somewhat high, It will not cause any major trouble. In addition, when dechlorination occurs, the calorific value of the solidified body is considered to increase by the amount of chlorine. However, since the organic matter decomposes and separates as a side reaction, the calorific value of the solidified body after treatment is rather small. is there. Therefore, by performing the heat treatment of the waste plastic at a temperature equal to or higher than the softening melting temperature and not generating flammable decomposition gas, the calorific value of the solidified body does not decrease.

According to Patent Document 4, for example, according to Patent Document 4, the heating temperature when waste plastic is heated, melted, cooled, and solidified is increased to a temperature for removing low-boiling compounds originally contained and / or generated by thermal decomposition. Heating is a major premise, specifically 150 to 450 ° C., more preferably 200 to 400 ° C., and even more preferably 250 to 380 ° C. In such a temperature range, combustible decomposition gas is generated together with hydrogen chloride by heating at a high temperature.

In general, in order to dechlorinate plastics containing chlorine, it is preferable to heat to 300 ° C. or higher. In this case, equipment for treating and recovering the generated chlorine gas is required.

Therefore, on the premise of dechlorination treatment of waste plastic, in equipment that heats waste plastic and cools it after melting, it becomes a solidified body. Combustion furnace and hydrochloric acid recovery device for waste plastic decomposition gas generated in the waste plastic heating and melting process A chlorination facility such as is required. Since such equipment is expensive, the present inventors have set the temperature at which combustible cracked gas is generated when cooling and solidifying into a solidified body after melting and kneading to reduce the processing cost of waste plastic. 1 was found, and the relationship shown in FIG. 1 was found for the temperature at which the waste plastic was heated and melted and the decomposition rate of the plastic. The decomposition rate is defined as (1−recovered amount / processed amount) × 100 (mass%) using the ratio of the amount of waste plastic used for processing (processed amount, dry base) and the recovered amount after processing. Is done.

According to FIG. 1, the generation of waste plastic decomposition gas is very low up to 270 ° C. Therefore, the waste plastic is heated, melted and kneaded below the temperature at which such cracked gas is generated, and cooled and solidified, so that no cracked gas treatment equipment such as a combustion furnace is required, and the waste plastic is processed at low cost. A waste plastic solidified body can be produced.

If the chlorine remaining in the waste plastic is low in concentration, there is often no problem when used for ore reducing material, solid fuel, etc., and the waste plastic treated in the present invention uses a low chlorine concentration. It is preferable. For example, a waste plastic having a chlorine concentration of 2 mass% or less treated by the method of the present invention can be sufficiently used for blowing blast furnace as an ore reducing material.

The temperature at which the flammable decomposition gas is not generated varies slightly depending on the type of waste plastic, but in the normal case, it is preferably 270 ° C. or less from the result of FIG. Furthermore, if it is 200 degrees C or less, generation | occurrence | production of combustible gas can be prevented more reliably. The temperature in this case is the highest temperature in the resin. The maximum temperature in the resin can be measured by a general method such as inserting a thermocouple into the resin. The temperature at which flammable decomposition gas is not generated is a temperature at which flammable organic substances are not substantially generated from waste plastic by heating, and is generated due to impurities in waste plastic (for example, liquefied gas in disposable lighters). Such gases are outside the scope of combustible cracked gas in this case.

The lower limit of the melting temperature is set to a temperature at which the waste plastic is softened and melted so that the waste plastic can be kneaded well as described later. The softening and melting temperature varies depending on the type of waste plastic, but since the main components of ordinary waste plastic are polyethylene (PE) and polypropylene (PP), the lower limit of the softening and melting temperature is preferably 160 ° C. If the waste plastic is mainly composed of PE, the temperature can be set to 120 ° C.

However, it is not practical to carry out the melting / kneading treatment at less than 160 ° C. because the waste plastic to be treated is a mixture of various plastics. That is, the only plastic that melts below 160 ° C is mainly PE, and if it is processed forcibly, the required power required for kneading becomes extremely large, and a blockage occurs in the processing apparatus, making it difficult to continue the processing. It may become.

“Melting and further kneading” the waste plastic means that the waste plastic is kneaded simultaneously with the melting of the waste plastic or kneaded in a molten state after the melting. Here, the kneading is performed at a shear rate of at least 100 (1 / second) or more. By sufficiently kneading, different types of plastics are mixed and highly dispersed, the number of different types of plastics increases, and the starting point of fracture is expressed. Plastics have different characteristics depending on the type, and when these different types of plastics are melt-kneaded and then cooled and solidified, the polymers solidify while being sufficiently mixed with each other, but the bonding interface is not chemically. While it is merely in physical contact, the molding shrinkage of different plastics differs depending on the plastic, and during the cooling process, the different plastics shrink according to their molding shrinkage and the bonding interface is separated. For this purpose, the inside must be evacuated (vacuum voids), and when void formation does not occur, a stress that "shall be separated but cannot be separated" remains at the bonding interface (residual stress). A dissimilar plastic highly dispersed by sufficient kneading has many adhesion interfaces, and the solidified body necessarily has a strong residual stress. When an impact is applied to the solidified body, stress concentration occurs at these different plastic bonding interfaces, and a breakage starting point is generated relatively easily. In addition, since there is no element that stops the propagation of cracks, the entire structure becomes brittle and the grindability is improved. In addition to molding shrinkage, differences in dissolution parameters and the like also affect pulverizability improvement.

Solid particulates other than waste plastics are also incompatible with plastics in most cases, so they are discarded before waste plastic melting and kneading, or during melting and kneading, or both before melting and kneading and during melting and kneading. By mixing solid particulates other than plastic with waste plastic and kneading with the waste plastic, after solidification by cooling, the solid particulate matter becomes a starting point of destruction, and the pulverization property of the solidified body can be further improved.

As a method for mixing before melting and kneading, for example, a tumbler or the like may be used to mix waste plastic and solid particulate matter in advance. As a method of mixing at the time of melting and kneading, waste plastic and solid particulates may be separately supplied to the melting and kneading apparatus and mixed in the apparatus, or one of them is supplied first and then the other is supplied. May be. When the melting point of the solid granular material is higher than the melting start temperature of the waste plastic, it is preferable to add the solid granular material after supplying the waste plastic first and achieving a certain molten state.

Solid particulates include fossil fuels such as coal, coke and asphalt, synthetic polymers such as virgin plastic, natural polymers such as starch and cellulose, metals such as iron and aluminum, and those ores such as iron ore and bauxite, Examples include inorganic substances such as mica and talc. Moreover, it is preferable to use what is called biomass solids, such as waste derived from agricultural products, such as rice husk, tea husk, and coffee husk (rice husk), and lignin-containing plants such as wood, charcoal, and bamboo, as the solid particulate matter. In particular, it is useful from the viewpoint of protecting the global environment to use wastes derived from agricultural crops and waste wood such as thinned wood and construction waste. As mentioned above, solid particulates other than waste plastics are incompatible with plastics in most cases, so after kneading with molten waste plastic and cooling and solidifying, it becomes a starting point of destruction and can improve grindability. However, it is particularly preferable because the biomass solid contains ash and is likely to be a starting point of destruction. Furthermore, the rice husk tends to be elongated, and is further pulverized when kneading molten waste plastic, so that it can be effectively used as a starting point for destruction. In addition, it is preferable that the compounding quantity of the solid granular material in this case shall be less than 100 mass parts of solid granular materials with respect to 100 mass parts of waste plastics. This is because if the solid granular material is 100 parts by mass or more, the waste plastic is pulverized after the kneading process, and handling becomes difficult. Moreover, it is preferable to set it as 5 mass parts or more of solid granular materials with respect to 100 mass parts of waste plastics. This is because the effect of adding the solid particulate matter can be exhibited better. These solid particulate materials can be used if they can be introduced into the processing apparatus.

It is preferable to heat and melt the waste plastic while kneading using an extruder. By using an extruder, the waste plastic can be heated and kneaded at a shear rate of 100 (1 / second) or more at the same time. The extruder can be further improved in kneadability by using a biaxial extruder.

By crushing the produced waste plastic solidified body, waste plastic pulverized product can be produced, and ore reducing material and solid fuel can be produced. The solidified product cooled and solidified after heating and melting has improved pulverization properties, and a fine powder having a particle size of 2 mm or less can be easily produced using a normal pulverizer. The crushed solidified body is preferably passed through a sieve to adjust the particle size. The particle size after pulverization can be set by appropriately changing the sieve mesh. For example, fine powder which is a waste plastic pulverized product having a particle size of 0.5 mm or less can be obtained by passing through a sieve having an aperture of 0.5 mm using the production method of the present invention.

Hereinafter, an embodiment of the present invention will be described as I.D. Plastic, II. Melting / kneading step, III. Cooling and solidifying step, IV. This will be described in more detail in the order of the pulverization step.

[I. Plastics] Waste plastics subject to the present invention, that is, raw material plastics in the present invention include waste plastics and container packaging materials contained in municipal waste, industrial waste, general waste, etc., and dismantling of electrical products, automobiles, etc. Examples include waste plastic generated in the process.

Specifically, polyolefins such as polyethylene and polypropylene, polyvinyl chloride, polyvinylidene chloride, chlorinated polyethylene, polystyrene, polyethylene terephthalate, polycarbonate, nylon, and other thermoplastic resins and thermosetting resins are all applicable. In this case, a plastic material in which any two or more of the plastics are mixed is used. Normally, it contains some chlorine-containing plastic due to the nature of waste plastic, which is waste, but the present invention can be used even with waste plastic that does not contain chlorine-containing plastic.

The shape of the plastic to be heat-treated may be roughly pulverized, and a size of about 10 cm square is sufficient. For general waste plastic, it is not necessary to pulverize again, and it is processed in the recovered state. Yes, film, sheet, and fiber plastics can be processed as they are. Of course, it may be finely pulverized, but the processing cost increases accordingly.

[II. Melting / kneading step] Examples of the melting / kneading step include the following steps. That is, the waste plastic is melted at 160 ° C. or higher at a temperature at which combustible decomposition gas is not generated in a reactor or an extruder. The temperature at which the combustible decomposition gas is not generated varies depending on the composition of the waste plastic, but the upper limit is usually 270 ° C. In the temperature range where the combustible decomposition gas is not generated, it is preferable to melt at a higher temperature, preferably 200 ° C. or higher, more preferably 230 ° C. or higher.

Kneading is performed at a shear rate of at least 100 (1 / second). FIG. 2 shows the results of measuring the change in melt viscosity with respect to the shear rate at 150 ° C. of various low-density polyethylenes (MI: Melt Index = 7, 50, 200) measured with a capillary rheometer. The molten plastic is a non-Newtonian fluid, and as shown in FIG. 2, the melt viscosity of low density polyethylene (LDPE) is substantially constant in the region where the shear rate is low. However, in any LDPE having any MI, in the region where the shear rate is 100 (1 / second) or more, the viscosity decreases as the shear rate increases. That is, from the viewpoint of kneadability, kneading in a region where the shear rate is 100 (1 / second) or more is extremely effective for lowering kneading power and improving kneading efficiency.

By melting and further kneading, the pulverizability of the plastic processed product can be improved. This makes it possible for dissimilar plastics in the waste plastic to mix with each other, but they hardly melt together and have no mutual interaction. As a result, the overall impact resistance is lost. The melting and kneading treatment may be a batch type or a continuous type. An intermediate type such as batch switching may also be used. As the continuous processing apparatus, an extruder is preferable, and a twin screw extruder is more preferable from the viewpoint of kneadability.

Processing time is suitably 0.5 minutes to 30 hours. When the treatment time is less than 0.5 minutes, it is difficult to control the temperature in the reactor, and it is difficult to sufficiently knead the molten waste plastic product. Moreover, when processing time exceeds 30 hours, processing efficiency falls and it is not economical.

In the melting / kneading process, a heat medium can be allowed to coexist.

[III. Cooling and solidifying step] The waste plastic after the melting treatment is cooled and solidified by supplying a fixed amount of the molten plastic to a belt cooler by a molten plastic conveying device. The amount of heat removal is calculated from the amount of enthalpy between the temperature after heat treatment and the temperature until fully solidified, and the treatment speed. For example, when including container packaging waste plastic, the center temperature after cooling is about 110 ° C. It is sufficient to control so that

Also, when using a continuous heating and melting apparatus, it can be cooled at the outlet of the apparatus, or it can be cooled without being cut, such as air cooling or charging into water.

[IV. Pulverization step] The solidified body that has undergone the cooling and solidification step is preferably pulverized so as to have a predetermined particle size. The pulverization of the plastic treated product, which is a cooled solidified body obtained by the above-described method of the present invention, can be performed very easily as compared with the pulverization of untreated plastic. That is, the processed plastic product obtained by the method of the present invention can be pulverized by any type of pulverizer, and for example, a jaw crusher, a roll crusher, a ball mill, a centrifugal mill, or the like can be used.

The particle size after pulverization may be determined according to the purpose of use of the processed plastic. If the particle size is adjusted to a predetermined particle size, for example, ore reducing material such as iron ore, that is, pig iron such as blast furnace is produced. It can be used as raw fuel such as reducing material for vertical furnaces, reducing material for converters, combustion fuel such as boilers and kilns, cupola fuel, and raw materials for coke ovens. Moreover, it can be used as a solid fuel other than the above-mentioned use.

Hereinafter, the present invention will be described more specifically based on examples.

[Invention Example 1] General waste container packaging waste plastic was pulverized to about 1 cm, melted at 180 ° C. with a twin screw extruder, and kneaded. The shear rate at the time of kneading was 243 (1 / second) (screw diameter 31 mm, screw-barrel gap 0.2 mm, screw rotation speed 30 rpm, shear rate π × 31 × 30/60 / 0.2 = 243) . Generation of moisture (water vapor) was observed from the vent of the extruder, but no combustible decomposition gas was confirmed. This was air-cooled as it was to obtain a mass (solidified body) of about 30 mm.

The solidified body yield was calculated from the raw material charge amount and the solidified body recovered amount at this time. Further, the chlorine concentration in this solidified body (solidified body residual chlorine concentration) and the calorific value of the solidified body were measured. The results are shown in Table 1.

This solidified body was coarsely pulverized by a small pulverizer (cutter mill) manufactured by Horai Co., Ltd., and passed through a 9 mm screen.

The coarsely pulverized product was finely pulverized with an ACM pulverizer (hammer mill) manufactured by Hosokawa Micron Corporation, and then subjected to a classification test with a test sieve to measure the particle size distribution. The results are shown in Table 2.

The average particle size was calculated from the particle size distribution. First, substituting the mass fraction and sieve diameter of each of the four fractions obtained in the classification test into the following equation (2) obtained by modifying the following equation (1) (Rosin-Rammeler-Bennet equation) Then, the proportionality constants n and b of the following formula (2) were obtained by the least square method.
R (Dp) = 100 · exp {− (Dp / De) n} (1)
log {log [100 / R (Dp)]} = n · logDp + log (b) (2)
In the above formulas (1) and (2), R (Dp) is the mass% on the integrated sieve of the sieve mesh Dp, De is the particle size characteristic number [R (Dp) is the number corresponding to mass%], and n is an equal number ( Index for evaluating the uniformity of the particle size distribution of the granular material), b is a constant and indicates an index for evaluating the fineness of the granular material.

D50 (50% passing sieve diameter) was calculated from the obtained n and b, and the average particle diameter was calculated. The average particle size is also shown in Table 1. The average particle size of the waste plastic pulverized product of Example 1 of the present invention that was melt-treated at 180 ° C. was less than 500 μm and was sufficiently fine.

[Invention Example 2] The same operation as in Invention Example 1 was conducted except that 70 parts by mass of general waste container packaging waste plastic pulverized to about 1 cm and 30 parts by mass of rice husk were mixed and supplied to the twin screw extruder. The solidified product and the pulverized product thereof were manufactured. Tables 1 and 2 show the results of measurement of the solidified body yield, the residual chlorine concentration in the solidified body, the calorific value of the solidified body, the calculation result of the average particle size, and the measurement result of the particle size distribution after pulverization.

The solidified body yield increased, the residual chlorine concentration in the solidified body decreased, and the calorific value of the solidified body decreased somewhat compared with Example 1 of the present invention. This shows that most of the rice husk containing about 20 mass% of ash remains in the solidified body after the treatment. Moreover, the average particle diameter after grinding | pulverization became small, and the grindability improvement effect by rice husk addition was recognized.

[Invention Example 3] Invention Example except that 70 parts by mass of general waste container packaging waste plastic pulverized to about 1 cm and 30 parts by mass of coal (brand: Xinglongzhuang) were mixed and supplied to a twin screw extruder. The same operation as in No. 1 was performed to produce a solidified product and a pulverized product thereof. Tables 1 and 2 show the results of measurement of the solidified body yield, the residual chlorine concentration in the solidified body, the calorific value of the solidified body, the calculation result of the average particle size, and the measurement result of the particle size distribution after pulverization.

The solidified body yield increased, the residual chlorine concentration in the solidified body decreased, and the calorific value of the solidified body somewhat decreased compared with Example 1 of the present invention. This indicates that most of the coal containing about 10 mass% of ash remains in the solidified body after treatment. Moreover, the average particle diameter after grinding | pulverization became small and the grindability improvement effect by coal addition was recognized. Compared to Example 2 of the present invention, the average particle size after pulverization is smaller, but this is because the added coal itself has better pulverizability than rice husk.

[Comparative Example 1] A solidified product and a pulverized product thereof were produced in the same manner as in the above-mentioned Invention Example 1 except that the kneading temperature by the twin screw extruder was 335 ° C. In addition to moisture, exhaust gas consisting of hydrogen chloride gas and organic substances was observed from the vent of the twin screw extruder. Terephthalic acid was detected as an exhaust gas component. Tables 1 and 2 show the results of measurement of the solidified body yield, the residual chlorine concentration in the solidified body, the calorific value of the solidified body, the calculation result of the average particle size, and the measurement result of the particle size distribution after pulverization.

In Comparative Example 1, the residual chlorine concentration in the solidified body was sufficiently reduced. Moreover, although the average particle diameter is small and pulverized, the main cause was a high ratio of ultrafine powder of 75 μm or less. The ultra fine powder of 75 μm or less has safety problems such as dust explosiveness, and costs for countermeasures such as nitrogen filling are required.

[Comparative Example 2] A classification test was performed in the same manner as in the above-mentioned Invention Example 1 except that the shear rate during kneading with the twin screw extruder was 81 (1 / second) (screw rotation speed: 10 rpm). . Tables 1 and 2 show the results of measurement of the solidified body yield, the residual chlorine concentration in the solidified body, the calorific value of the solidified body, the calculation result of the average particle size, and the measurement result of the particle size distribution after pulverization.

In comparison example 2 where the shear rate during kneading is out of the range of the present invention as compared with example 1 of the present invention, it is clear that the average particle size is large and not pulverized.

[Comparative Example 3] A classification test was performed in the same manner as in the above-mentioned Invention Example 2 except that the kneading temperature by the twin screw extruder was 335 ° C. In addition to moisture, exhaust gas consisting of hydrogen chloride gas and organic substances was observed from the vent of the twin screw extruder. Terephthalic acid was detected as an exhaust gas component. Tables 1 and 2 show the results of measurement of the solidified body yield, the residual chlorine concentration in the solidified body, the calorific value of the solidified body, the calculation result of the average particle size, and the measurement result of the particle size distribution after pulverization.

In Comparative Example 3, the average particle size was small and pulverized, but the main cause was a high proportion of ultrafine powder of 75 μm or less. The ultra fine powder of 75 μm or less has safety problems such as dust explosiveness, and costs for countermeasures such as nitrogen filling are required.

[Comparative Example 4] The same processing as in Example 1 of the present invention was attempted except that the processing temperature at the time of kneading with a twin-screw extruder was set to 140 ° C. However, the screw motor stopped due to overload about 5 minutes after the start of the treatment, and the treatment could not be continued. When the screw was extracted after cooling the twin screw extruder, unmelted waste plastic solid was clogged inside.

From the above results, it can be seen that in Examples 1 to 3 of the present invention, all the pulverized products could be finely pulverized to an average particle size of 500 μm or less, despite being melted and kneaded at a low temperature. By adding rice husk and coal, the grindability is further improved. When Example 1 of the present invention and Comparative Example 1 were compared, in Example 1 of the present invention, the residual chlorine concentration in the solidified body did not decrease, but the solidified body yield increased and the calorific value of the solidified body increased. This clearly improves the productivity of the pulverized product. In Comparative Example 1, this is thought to be due to the fact that terephthalic acid, which is a combustion component, is also removed during the dechlorination process, but the combustion component remains in the present invention example.

On the other hand, when Comparative Example 3 is compared with Comparative Example 1, the average particle size is increased despite the addition of rice husk, and at first glance, it seems that the grindability is lowered. However, although the average particle size in Comparative Example 3 was slightly larger, according to Table 2, Comparative Example 3 has a higher particle size ratio of 150 to 500 μm and 75 to 150 μm than Comparative Example 1, and the width of the particle size distribution is It is narrower and the grindability is improved. Therefore, the effect of “better crushability is exhibited by forming the starting point of fracture” by adding rice husk was recognized.

Claims

The waste plastic is melted at a temperature not lower than the softening melting temperature and does not generate flammable decomposition gas, and further kneaded at a shear rate of 100 (1 / second) or more, and then cooled and solidified to obtain a solidified body. A method for producing a pulverized waste plastic, characterized by pulverizing.
The method for producing a waste plastic pulverized product according to claim 1, wherein the softening and melting temperature is 160 ° C, and the temperature at which flammable decomposition gas is not generated is 270 ° C or less.
Waste plastic characterized in that waste plastic is melted at 160 ° C. to 270 ° C., kneaded at a shear rate of 100 (1 / second) or more, then cooled and solidified to form a solidified body, and the solidified body is pulverized. Manufacturing method of plastic pulverized material.
The method for producing a waste plastic pulverized product according to any one of claims 1 to 3, wherein melting and kneading are performed using an extruder.
The method for producing a waste plastic pulverized product according to claim 4, wherein the extruder is a twin screw extruder.
The solid granular material other than the waste plastic is mixed and kneaded together with the waste plastic before and / or during the melting / kneading of the waste plastic. Of waste plastic crushed material.
The method for producing a waste plastic pulverized product according to any one of claims 1 to 6, wherein the particle size of the solidified product pulverized by passing through a sieve is adjusted.
An ore reducing material or a solid fuel which is a pulverized product produced according to any one of claims 1 to 7.
The ore reducing material or solid fuel according to claim 8, wherein the ore reducing material or the solid fuel passes through a sieve having an opening of 0.5 mm.