CA2649510A1

CA2649510A1 - Decomposition method of waste plastics and organics, decomposition apparatus, and decomposition system

Info

Publication number: CA2649510A1
Application number: CA 2649510
Authority: CA
Inventors: Tatsuo Kitamura; Yoshihide Kitamura; Itsushi Kashimoto
Original assignee: Individual
Current assignee: Rapas International Ltd; RAPAS CO Ltd
Priority date: 2006-04-19
Filing date: 2007-03-27
Publication date: 2007-11-01
Anticipated expiration: 2027-03-27
Also published as: WO2007122967A1; KR20090025212A; JP4380783B2; JPWO2007122967A1; AU2007242207A1; KR101508016B1; JP2009270123A; CA2649510C

Abstract

An object of the present invention is to provide a method of efficiently decomposing waste plastics, organics, and particularly medical waste composed of varieties of plastics, decomposition apparatus, and decomposition system.
To solve the above-mentioned problems, the inventors of the present invention established optimizing conditions in a decomposition process, and a decomposition apparatus and a decomposition system which allow the catalyst to circulate therein, thus perfected the present invention.

Description

TITLE OF THE INVENTION

DECOMPOSITION METHOD OF WASTE PLASTICS AND ORGANICS, DECOMPOSITION APPARATUS, AND DECOMPOSITION SYSTEM
Field of the Invention [0001]

The present invention relates to a decomposition method of waste plastics, organics, and particularly medical waste composed of various plastics and organics and infectious medical waste, more specifically to a high efficient decomposition method of waste plastics and organics by optimizing respective conditions of decomposition method of waste plastics and organics.

Further, the present invention relates to an apparatus of catalyst-circulation type for decomposing waste plastics and organics, and to a system thereof at high efficiency. The decomposition apparatus further includes a means for separating and recovering metals and inorganics which are mixed in the waste plastics or which are vapor-deposited or adhered to at least a portion of the waste plastics.

This application claims the priority of Japanese Patent Application No.2006-297194 No.2006-115920, No.2006-115925 and No.2007-016087.

Related Background of the Invention [0002]

Recentl.y, there have been proposed various methods of treating and recycling waste plastics, and a part thereof are practically employed. As a useful method of recycling and reusing such waste plastics, there is proposed a method and apparatus for gasifying the waste plastics by heating chips of the waste plastics in the presence of a decomposition catalyst of titanium oxide known as a photocatalyst under irradiation of ultraviolet light (Referring to Patent Documents 1, 2).

Further, catalysts used for decomposition treatment of the waste plastics chips have been variously studied (Patent Documents 3 to 5).

[0003]

The decomposition apparatus using the above decomposition method of waste plastics, however, cannot conduct efficient decomposition treatment of waste plastics, and requires large treatment cost and large apparatus. Furthermore, the treatment of waste containing polyvinylchloride is known to generate hydrogen chloride gas. Also, the treatment of Teflon is known to generate toxic hydrogen fluoride gas. The treatment of those kinds of gases becomes a problem.

[0004]

Organics such as plastics are difficult for treating on discarding them. Incineration treatment of them raises a danger of generating toxic substances such as dioxins.

Plastics pieces often contain metals such as aluminum and copper, and inorganics, and have metals vapor-deposited or adhered to the surface of plastics, depending on the uses of the plastics. If those plastics pieces are incinerated, toxic gases may be generated or the incineration furnace may be damaged.

Accordingly, organics such as plastics pieces are treated bylandfilling in some cases. As plastics, however, they are not decomposed in the ground. In addition, the availability of landfill sites has become difficult.
Although there are biodegradable plastics, they have drawbacks of taking a long period of time until they are decomposed and of need of a very large area for biodegradation. Furthermore, reusable metals, rare metals, and inorganics mixed in the waste plastics and organics cannot be separated therefrom, and they are simply landfilled or incinerated together with the waste plastics and organics.

[0005]

There exists a conventional process for decomposing organics utilizing a catalyst, as illustrated in Fig. 23.
According to the existing process, organics such as plastics are crushed into granules in a crusher 101, and then the crushed organics are charged into a reactor 102 in drum shape, the reactor 102 containing catalyst granules in advance. After that, agitation blades 103 are rotated in the reactor 102 to agitate the catalyst with the organics, while supplying hot air into the reactor 102 using an air-supply blower 104. The work of the catalyst enhances the decomposition of the organics, thus the organics are gasified.

Although the catalyst is left behind in the reactor 102, the gasified organics pass through a separator 106 consisting mainly of cyclone dust collector, and only water vapor and carbon dioxide are emitted to atmosphere as the exhaust gas. By above gasification of the organics charged into the reactor 102, new organics at an, amount corresponding to the amount of gasified organics can be charged to the reactor 102, thereby allowing the above process to continuously operate without interruption.

[0006]

Above existing decomposition apparatus, however, cannot conduct efficient treatment for decomposing waste plastics, and requires large treatment cost and large apparatus.

Furthermore, the treatment of waste containing polyvinylchloride is known to generate hydrogen chloride gas and nitrogen compounds. In addition, the treatment of Teflon is known to generate toxic hydrogen fluoride gas.
The treatment of those kinds of gases becomes a problem.

[0007]

Regarding the prevention of secondary infection caused by infectious medical waste discharged from hospitals, dialysis facilities, and the like, a guideline specifying the treatment method of that kind of waste was issued from the Ministry of Health and Welfare on November 7, 1989, and was enforced on April 1, 1990. The guideline orders the hospitals, dialysis facilities, and the like to conduct in-house or on-site sterilization of the medical waste, in principle.

In this regard, there is wanted the development of a decomposition method for waste plastics, in particular the infectious medical waste containing polyvinylchloride, applicable in hospitals or clinics safely without using large scale apparatus.

[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-363337 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-182837 [Patent Document 3] Japanese Patent Application Laid-Open No. 2005-066433 [Patent Document 4] Japanese Patent Application Laid-Open No. 2005-205312 [Patent Document 5] Japanese Patent Application Laid-Open No. 2005-307007 SUMMARY OF THE INVENTION

[Problems to be Solved by the Invention]

[0008]

In order to satisfy the above requirements, an object of the present invention is to provide a method of efficiently decomposing waste plastics and organics, particularly medical waste composed of varieties of plastics, biological substances such as blood, and plastics with adhered biological substances. Further, another object is to provide a decomposition method which can remove HC1 generated during decomposition of chlorine-based plastics such as polyvinylchloride, sulfur compounds and nitrogen compounds generated during decomposition of biological waste and varieties of medical waste plastics;
hydrogen fluoride generated during decomposition of fluorine compounds such as Teflon , and the like.

[0009]
Further, large portion of industrial waste including medical waste is occupied by plastics, organics, and the like. The waste also contains aluminum thin films vapor-deposited on inner face of packages, and syringe needles. Those metals remain in the reactor even after the entire organics are gasified. If the metals are aluminum and the like, continuous operation of decomposition while aluminum and the like remaining in the reactor induces vigorous oxidation of aluminum and the like, which results in difficulty in recycling the aluminum and the like.

If the above operation is stopped to successively take out the metals from the reactor, the mass or volume of organics being able to be decomposed within a specified period of time, (hereinafter referred to as the "throughput"), becomes small. If the metals are to be separated outside the reactor, the catalyst temperature at the activation temperature becomes low at every catalyst-takeout cycle, which needs reheating, thereby wasting the thermal energy.

In a conventional decomposition apparatus, the catalyst which is powdered and emitted is discarded without recycling to the reactor. The reason is that, if the catalyst is in an approximate size range from 1 to 3 mm, flow of catalyst occurs in entire zone in the reactor accompanied with the rotation of the agitation blades, and that the powdered catalyst, however, is difficult to flow, and is difficult to mix with the waste plastics and organics.
The problem hinders the scale up of reactor because the phenomenon becomes significant with the increase in the amount of catalyst accumulated in the reactor, and further hinders the increase in the throughput.

To recover metals from waste plastics and organics containing the metals including aluminum and copper, such as silver foil composite, without oxidizing them, carbonization treatment or the like is applied. Use of a vacuum melting furnace, however, increases the cost for metal recovery. The melting treatment to the plastics pieces oxidizes the metals, which fails to recover high purity metals.

Furthermore, there is a problem to hinder the practical application of decomposition apparatus. The problem is the treatment of: HCl generated during decomposition of chlorine-based plastics such as polyvinylchloride; sulfur compounds and nitrogen compounds generated during decomposition of biological waste and varieties of medical waste plastics; hydrogen fluoride generated during decomposition of fluorine compounds such as Teflon ; and other substances.

Therefore, the present invention has been derived to solve the above problems, and an object of the present invention is to provide an apparatus and a system for decomposing a large amount of waste plastics and organics efficiently while elongating the catalyst life.

Another object of the present invention is to provide a decomposition apparatus and a decomposition system for separating and recovering metals and/or inorganics in a process of circulating and/or agitating catalyst.

A further object of the present invention is to provide a decomposition apparatus and a decomposition system for removing: HC1 generated during decomposition of chlorine-based plastics such as polyvinylchloride; sulfur compounds and nitrogen compounds generated during decomposition of biological waste and varieties of medical waste plastics; hydrogen fluoride generated during decomposition of fluorine compounds such as Teflon ; and other substances.

[Means for Solving the Problems]

[0010]

As a result of the intensive study to achieve the aforementioned objects, the present inventors established a method of efficiently decomposing waste plastics, organics, and particularly medical waste mainly composed of varieties of plastics by optimizing conditions in a decomposition process and introducing a process of adsorbing and removing generated harmful gases.

Furthermore the present inventors established a apparatus of catalyst-circulation type for decomposing waste plastics and organics, and to a system thereof.

Thus the present invention perfected.

[0011]

Namely, the present invention is as follows:

"1. A decomposition method of waste plastics and organics by gasifying the waste plastics and/or organics, the method comprising the process of heating and agitating the waste plastics and/or organics together with a catalyst composed of titanium oxide granules in which the active ingredient is titanium oxide, wherein the heating temperature of the catalyst is within the range of 420 C to 560 C.

2. The decomposition method according to preceding clause 1, wherein the titanium oxide of titanium oxide granules have the following characteristics:

I

(1) the specific surface area from 35 to 50 m2/g; and (2) the granule size of 3.5 mesh (5.60 mm) or smaller.
3. The decomposition method according to preceding clause 1 or 2, wherein a treatment amount of the waste plastics and/or organics per hour with respect to 100 kg of the titanium oxide granules is 3.0 to 40.0 kg.

4. The decomposition method according to any one of preceding clauses 1 to 3, further comprising a lime neutralization treatment process.

5. The decomposition method according to any one of preceding clauses 1 to 4, further comprising an oxidation catalyst treatment process.

6. The decomposition method according to preceding clause 5, further comprising an alumina catalyst treatment process before the oxidation catalyst treatment process.

7. The decomposition method according to any one of preceding clauses 1 to 6, further comprising the process of separation of metals and/or inorganics.

8. An apparatus of catalyst-circulation type for decomposing waste plastics and organics, comprising:

(1) a means for treating waste plastics and organics, and (2) a means for treating oxidation catalyst.

9. The apparatus for decomposing waste plastics and organics according to preceding clause 8, wherein the means for treating waste plastics and organics includes:

a reactor which circulates a catalyst in the reactor;

and a means for circulating and/or agitating waste plastics and/or organics, charged from a charge opening of the reactor, together with the catalyst, (a circulation and/or agitation means), the waste plastics and/or organics being gasified in the step of circulating the waste plastics and/or organics together with the catalyst in the reactor.

10. The apparatus for decomposing waste plastics and organics according to preceding clause 9, wherein the circulation and/or agitation means is one or more screw feeders which have spiral blades mounted to the respective rotary shafts rotated by the respective drive sources, the rotary shafts being inserted into the reactor.

11. The apparatus for decomposing waste plastics and organics according to preceding clause 10, wherein the two screw feeders are located in substantially horizontal position in the reactor, and the rotation of the two screw feeders circulates the waste plastics and/or organics together with the catalyst in the reactor substantially in horizontal direction.

12. The apparatus for decomposing waste plastics and organics according to preceding clause 9, wherein the means for treating waste plastics and organics includes:

a reactor which circulates a catalyst from upstream end to downstream end in the reactor; a circulation means which circulates waste plastics and/or organics charged from a charge opening of the reactor together with the catalyst from the upstream end to the downstream end; an agitation means which agitates the catalyst and the waste plastics and/or organics in the reactor; and a returning passage which guides the catalyst from the downstream end to the upstream end in the reactor, the waste plastics and/or organics being gasified in the step of circulating the waste plastics and/or organics together with the catalyst from the upstream end to the downstream end in the reactor.

13. The apparatus for decomposing waste plastics and organics according to preceding clause 12, wherein the reactor is divided into a first stage tank having the upstream end, and a second stage tank having the downstream end and being located at higher position than the position of first stage tank, thereby the catalyst being guided from the downstream end in the second stage tank into the returning passage to flow down to the upstream end in the first stage tank.

14. The apparatus for decomposing waste plastics and organics according to preceding clause 12, wherein the upstream end and the downstream end in the reactor are located substantially in horizontal position, thereby the catalyst after sliding down from the downstream end by the self weight being guided into the returning passage, and then flowing up to the upstream end.

15. The apparatus for decomposing waste plastics and organics according to any one of preceding clauses 12 to 14, wherein the circulation means is a screw feeder which has a spiral blade mounted to a rotary shaft rotated by a drive source, the rotary shaft being inserted into the reactor.

16. The apparatus for decomposing waste plastics and organics according to preceding clause 15, wherein the spiral blade has an auxiliary blade.

17. The apparatus for decomposing waste plastics and organics according to preceding clause 9, wherein the means for treating waste plastics and organics includes:

a reactor which circulates a catalyst from upstream end to downstream end in the reactor; a cage which can position the waste plastics and/or organics in the reactor;
and a returning passage which guides the catalyst from the downstream end to the upstream end in the reactor, the waste plastics and/or organics in the cage being contacting with the catalyst and further being gasified in the step of dropping (circulating) the catalyst from the upstream end to the downstream end in the reactor.

18. The apparatus for decomposing waste plastics and organics according to any one of preceding clauses 9 to 17, wherein the reactor can supply a carrier gas from a plurality of holes opened on the bottom of the reactor directly into the catalyst in a uniformly distributed manner.

19. The apparatus for decomposing waste plastics and organics according to any one of preceding clauses 9 to 18, wherein the step of circulation in the reactor has a means for separating and recovering metals and/or inorganics.

20. The apparatus for decomposing waste plastics and organics according to preceding clause 19, wherein the means for separating and recovering metals and/or inorganics is a means for separating the catalyst from a mixture of the waste plastics and/or organics and the catalyst in the step of circulation in the reactor.

21. The apparatus for decomposing waste plastics and organics according to preceding clause 20, wherein the means for separating the catalyst from a mixture of the waste plastics and/or organics and the catalyst is a means for separating the metals and/or inorganics from the catalyst based on the size difference therebetween.

22. The apparatus for decomposing waste plastics and organics according to preceding clause 21, wherein the means for separating the metals and/or inorganics from the catalyst based on the size difference therebetween installs a sieve which allows the catalyst to pass therethrough in the step of circulation in the reactor.

23. The apparatus for decomposing waste plastics and organics according to any one of preceding clauses 8 to 22, further has one or more of the following means:

(1) alumina catalyst treatment means (2) crushing means (3) carrier gas supply means (4) cyclone dust collection means (5) dust collection means with bag filter (6) heat exchange means (7) preheater means (8) exhaust blower means (9) cooling means (10) heat recovery means (11) HC1 continuous measurement means (12) CO continuous measurement means (13) alarm means (14) lime neutralization treatment means.

24. A decomposition system for waste plastics and organics using an apparatus for decomposing waste plastics and organics according to any one of preceding clauses 8 to 23, thereby decomposing the waste plastics and organics while controlling the heating temperature of the catalyst, composed of titanium oxide granules in which the active ingredient is titanium oxide, within the range of 420 C to 560 C.

25. The decomposition system according to preceding clause 24, wherein the titanium oxide as the active ingredient is titanium oxide have characteristics of:

(1) the specific surface area from 35 to 50 m2/g; and (2) the granule size of 3.5 mesh (5.60 mm) or smaller.

26. The decomposition system according to preceding clause 25, wherein the titanium oxide granules are a mixture of titanium oxide as the activate ingredient and any one of below (1) and (2) :

(1) aluminum oxide, and (2) silicon oxide. "
[Effects of the Invention]
[0012]

According to a decomposition method of the present invention, there can be treated efficiently waste plastics, organics, and particularly medical waste composed of varieties of plastics, biological substances such as blood, and plastics with adhered biological substances. Further, there can be easily treated plastics which generate HC1, hydrogen fluoride, sulfur compounds, nitrogen compounds, and the like during decomposition process, organics, biological substances such as blood, and fluorine compounds generating hydrogen fluoride.

[0013]

According to the decomposition apparatus and the decomposition system of the present invention, the supply of hot air heated by the heating means into the reactor in which the catalyst is circulating can heat the catalyst to the activation temperature. Once the catalyst is heated, the decomposition heat of waste plastics and organics can be utilized to maintain the optimum activation temperature of the catalyst in the reactor, and can suppress the energy supply from outside, thereby allowing effective use of thermal energy.

When the waste plastics and organics are charged from the charge opening of the reactor, the waste plastics and organics are circulated in the reactor together with the catalyst by a circulation means. In this step, since the waste plastics and organics are agitated by an agitation means together with the catalyst, the contact between the catalyst and the waste plastics and organics is repeated, thus keeping the density of catalyst and waste plastics and organics constant, thereby enhancing the efficient decomposition based on the catalyst action. As a result, the waste plastics and organics charged from the charge opening of the reactor are gasified until they make about a round (one circulation) in the reactor.

Alternatively, a cage containing the waste plastics and organics is placed in the reactor. During the step of falling the catalyst down from the upstream end to the downstream end in the reactor, (the step of circulation), the waste plastics and/or organics are brought into contact with the catalyst, and are gasified. In this case, above-described agitation means for the waste plastics and organics with the catalyst is not required.

The catalyst keeps circulating in the reactor.

According to an embodiment of Example 9 described below, the catalyst circulates horizontally in the reactor.
According to another embodiment of Examples 10 to 12, the catalyst once travels from the upstream end to the downstream end in the reactor, which is then guided by the returning passage to return to the upstream end in the reactor, thus circulating in the reactor. Consequently, the catalyst keeps circulating in the reactor. When additional waste plastics and organics are charged into the rector, they are efficiently gasified by the action of catalyst circulating in the reactor.

According to the embodiment of Examples 9 to 11, the organics which occupy the large portion of waste plastics and organics are gasified during the step of circulating the waste plastics and organics together with the catalyst in the reactor by the circulation means. The metals and inorganics mixed in the waste plastics and organics are, however, left in the catalyst. Since these metals and inorganics are separated and recovered by the means for separating and recovering metals and/or inorganics in the step of circulating the waste plastics and organics together with the catalyst, these metals and inorganics can be taken out from the catalyst.

The decomposition apparatus and the separation system therefore suppress the oxidation of metals and inorganics without leaving large amounts of metals and inorganics in the reactor, and achieve the recycle of metals and inorganics. Furthermore, since there is no need to stop operation of the circulation means and the agitation means during the separation and recovery of metals by the means for separating and recovering the metals and/or inorganics, the throughput of the waste plastics and organics can maintain a high level. In addition, on classifying the metals and inorganics by the separation and recovery means, there is no need to open the reactor, or there is no need of taking out the catalyst from the decomposition apparatus to separate the metals and inorganics. Therefore, the thermal efficiency of the decomposition apparatus and the decomposition system can maintain a high level.

According to the decomposition apparatus or the decomposition system of the present invention, they comprise a means for treating oxidation catalyst, and preferably further comprise a lime neutralization means.
Consequently, they can conduct high efficiency treatment of waste plastics, organics, in particular industrial waste such as medical waste composed of varieties of plastics, biological substances such as blood, and plastics with adhered biological substances. Furthermore, they can easily conduct the treatment of plastics which generate HC1, hydrogen fluoride, sulfur compounds, nitrogen compounds, and the like during decomposition step, of organics, of biological substances such as blood, and of fluorine compounds generating hydrogen fluoride.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[00I4]

The "heating temperature of the catalyst"-according to the present invention needs at least 300 C or above and 600 C or below, preferably 350 C or above, more preferably from 420 C to 560 C, still preferably from 450 C to 530 C, and most preferably about 480 C.

The heating temperature is the catalyst temperature in the reactor to bring the catalyst and the waste plastics and/or organics into reaction condition, and is the set temperature to keep the set temperature of catalyst. That is, even when the set temperature is 480 C, the range of fluctuation of the catalyst temperature in the reactor becomes about 30 C from the set temperature.

Furthermore, at a certain position in the reactor, the temperature may become higher or lower than the specifically preferred "heating temperature of catalyst"
of the present invention depending on the shape and size of the reactor. Since, however, the catalyst is circulating in the reactor, only requirement is for the most part of the catalyst to maintain the more preferable heating temperature of catalyst.

In the examples, the heating temperatures of the catalyst have been variously studied. As a result, the optimum heating temperature for waste plastics decomposition has been set.
[0015]

The catalyst of the present invention is preferably the one made by titanium oxide granules containing titanium oxide as the active ingredient. The catalyst composed of titanium oxide granules is not only the titanium oxide granules made only of titanium oxide as the active ingredient, but also includes granules of a mixture of titanium oxide with at least one of aluminum oxide and silicon oxide, (hereinafter also referred to as the "titanium oxide mixture") As already known, since the titanium oxide has a function of photocatalyst, the decomposition of waste plastics and organics using any of above catalysts may be conducted, as needed, by irradiating light, specifically irradiating ultraviolet light, while heating and agitating the catalyst and the waste plastics and organics. However, for the case of decomposition of single article of varieties of waste plastics and organics, or decomposition of varieties of materials containing their solid, liquid, or containing metals or inorganics, the irradiation of ultraviolet light achieves little effect in terms of practical application.

To this point, decomposition method and/or the decomposition system for waste plastics and organics according to the present invention allows the decomposition of waste plastics and organics at high efficiency without applying light irradiation by the use of a suitable decomposition apparatus, by the optimization of decomposition condition, and by the use of suitable catalyst.

[0016]

The titanium oxide granules are manufactured by drying a sol of titanium oxide to a gel of titanium oxide, firing the gel in a temperature range from 450 C to 850 C, and then crushing and edge-treating the fired product. The granules of a mixture of titanium oxide are manufactured by mixing and drying the sol of titanium oxide and at least one sol of alumina sol and silica sol to prepare a gel, firing the gel in a temperature range from 450 C to 850 C, and then crushing and edge-treating the fired product. The used titanium oxide is preferably an anatase-type titanium oxide.

[0017]

The shape of the titanium oxide granules used in the decomposition method or decomposition system for waste plastics and organics according to the present invention is 3.5 mesh (5.60 mm) or smaller, and preferably 10 mesh (1.70 mm) or smaller.

More preferably, the shape of the titanium oxide granules before use is from 5. 60 mm to 110 u m, or from 3. 50 mm to 150 m.

In detail, a percentage of the titanium oxide granules having shape of 0.1 mm or above is preferably, from 0.1 mm or above to 5.60mm or smaller is more preferably, 90% or above(referring to fig.13 and 14).

A preferred shape of the titanium oxide granules or the granules of mixture of titanium oxide in the conventional decomposition method or decomposition system for waste plastics is the one having a particle size distribution in which the percentage of particles having 0.5 to 1.18 mm in size is 50 to 95% by weight, and the percentage of particles having 1.18 to 1.7 mm in size is to 50% by weight, and having 2. 0 0 or less of abrasion rate;
and more preferably the one having a particle size distribution in which the percentage of particles having 0.5 to 1.18 mm in size is 60 to 90% by weight, and the percentage of particles having 1.18 to 1.7 mm in size is to 40% by weight, and having 1.0% or less of abrasion rate.

However, the applicable shape of the titanium oxide granules used in the decomposition method or decomposition system for waste plastics and organics according to the present invention is widened to a broad range beyond the limitation of shape and particle size of the titanium oxide granules which were accepted in the above conventional method owing to the optimization of the conditions and/or decomposition apparatus in the decomposition process. As a result, the titanium oxide granules having sizes not applicable in the conventional method can be used, and the simplification of process and manufacturing method of manufacturing titanium oxide is attained.

However, naturally the above conventional granules are sufficiently applicable for decomposing the waste plastics and organics.

[0018]

As described above, the "catalyst composed of titanium oxide granules" according to the present invention is the titanium oxide granules or granules of a mixture of titanium oxide, have shapes of 3. 5 mesh (5. 60 mm) or smaller, preferably 10 mesh (1.70 mm) or smaller, and have 2.0% or less, preferably 1.0% or less, of abrasion rate after edge-treatment. As a result, the present invention allows waste plastics and organics to be decomposed at high efficiency over a long period of time by using the above-described catalyst.

[0019]

The method to manufacture the granules having above shape is not specifically limited. For example, as described above, the granules having the above shape may be prepared by firing gel, crushing the fired product, and edge-treating the crushed product, followed by classifying (using sieves having the respective mesh sizes), or after edge-treatment, classifying to mix to an adequate sizes, thus obtaining the granules having above shape.

i [0020]

Among the titanium oxides prepared by varieties of methods, the titanium oxide prepared by drying a sol of titanium oxide to a gel of titanium oxide, which gel is then fired at temperatures in a range from 450 C to 850 C, as described above, provides excellent performance as the decomposition catalyst for waste plastics. As crushed state, however, the catalyst is easily abraded to generate fine powder, thus increasing the loss.

[0021]

To this point, according to the present invention, the crushed fired-gel of titanium oxide is subjected to edge-treatment to preliminarily eliminate sharp corners, thussignificantly reducing the abrasion rate. As a result, the waste plastics and organics can be decomposed at high efficiency, and also the catalyst keeps its preferable shape to maintain the high catalyst efficiency over a long period of time. The effect is the same to the catalyst composed of granules of a mixture of titanium oxide. That type of edge-treatment is conducted by, for example, crushing a gel of titanium oxide or a gel mixture of the gel of titanium oxide and at least one gel of alumina and silica, which crushed product is then treated by a rolling granulation apparatus which is known as a granulator. The apparatus is, however, not limited to the rolling granulation apparatus.

[0022]

The abrasion rate of the titanium oxide granules of the present invention is determined by the following method.

The determination is given by the abrasion rate tester illustrated in Fig. 1. The abrasion rate tester is composed of a sample vessel 201 having 63 mm in inner diameter and 86 mm in depth, equipped with an agitator 202. The agitator 202 has three-piece agitation blades 204 in elliptical shape each having 20 mm in length, attached to the lower end portion of the shaft body 203 at intervals of 60 extending in the radial direction from the shaft body 203.
The agitation blade inclines by 45 from the horizontal direction, while positioning the lowermost edge thereof at 8 mm above the bottom of the sample vessel.

[0023]

The procedure for determining the abrasion rate of the titanium oxide granules is the following. A 150 mL of titanium oxide granules is measured by a 200 mL measuring cylinder, the weight is recorded, and then all the weighed content is charged into a sample vessel. After agitating the content by the agitator at 300 rpm for 30 minutes, all the content is taken out from the sample vessel, and is put on a sieve having 0.5 mm of opening. The sample passed the sieve is weighed. The abrasion rate A of the sample is defined as A = (W/Wo) x 100 ( o) , where the W is the sample weight passed the 0. 5 mm opening sieve, and Wo is the sample weight for the measurement.

[0024]

The "catalyst composed of the titanium oxide granules" according to the present invention has the specific surface area of titanium oxide as the active ingredient of 30 m2/g or more, preferably in a range from 33 to 65 m2/g, and more preferably from 35 to 50 m2/g. Also, the specific surface area of titanium oxide as the active ingredient before use is preferably from 35 to 50 m2/g.
Larger specific surface area increases more the contact area with the waste plastics, and increases the decomposition efficiency. However, excessively large specific surface area deteriorates the heat resistance, and likely collapsing the granule to lead to powdering.

The method of determining the specific surface area of the catalyst composed of titanium oxide granules can use known methods. Among these methods, the present invention uses the BET method, which is described below in detail.
[0025]

The BET method determines the specific surface area of sample by bringing molecules having a known adsorption occupying area to be adsorbed onto the surface of powder particles at liquid nitrogen temperature, and the adsorbed amount is measured to obtain the specific surface area.

The present invention adopts the specific surface area meter Model 2300 Automatic Testing Apparatus (manufactured by Shimadzu Corporation).

[0026]

The "catalyst composed of titanium oxide granules"
according to the present invention has the micropore volume of the titanium oxide as the active ingredient in a range from 0.05 cc/g to 0.70 cc/g, and preferably from 0.10 cc/g to 0.50 cc/g.

The method of determining the micropore volume of the catalyst composed of titanium oxide granules may be known methods. Among these methods, the present invention adopts the mercury intrusion method, which method is described below in detail.

[0027]

The mercury intrusion method determines the micropore volume utilizing the large surface tension of mercury. That is, pressure is applied to intrude the mercury into micropore of the powder, and the micropore volume is determined based on the applied pressure and the intruded mercury amount.

The present invention uses a porosimeter (mercury intrusion method, maximum pressure of 200 MPa) manufactured by Thermo Finnigan.

[0028]

The "catalyst composed of titanium oxide granules"
according to the present invention has intensity distribution as showed by Fig.13 and Fig.14. The catalyst has a particle size distribution in which the percentage . of particles having 1. 4 mm or above is 20 to 30%, in which the percentage of particles having 1.0 to 1.4 mm is 10 to 15%, in which the percentage of particles having 0. 6 to 1. 0 mm is 15 to 20%, in which the percentage of particles having 0.3 to 0.6 mm is 18 to 25%, in which the percentage of particles having 0.125 to 0.3 mm is 10 to 18% when 50 KN
or 70 KN is specified pressure.

Measurement of intensity distribution is as follows.
(1) titanium oxide granules 350g, which has been agitated, is put in mold for testing compression (produced by SAKAI
CHEMICAL INDUSTRY CO.,LTD, referring to fig.11 and 12).
(2) The mold is placed in center of 300KN compression tester (produced by MARUI & CO.,Ltd.,).

(3) The mold is charged to loading little by little. The loading is then stopped when specified pressure reaches 50KN or 70KN.

(4) The mold is taken out in the tester.

(5) The granules in the mold are transferred to bag and combined uniformly.

(6) The granules 25g, which are combined uniformly, is subject to precise weighing and sieve.

(7) The granules, which remain mesh, is subject to weight measurement. And, intensity distribution of the granules is calculated based on the weight.

[0029]

According to the present invention, if the amount of waste plastics and/or organics is small compared with the amount of titanium oxide granules, the waste plastics and organics are readily decomposed, and the heat for maintaining the suitable temperature for decomposition of the titanium oxide utilizing the decomposition reaction heat becomes insufficient, which requires heating from the outside, thus deteriorating the decomposition energy efficiency. If, however, the amount of waste plastics and/or organics increases compared with the amount of the titanium oxide granules, the treating materials exceeding the capacity of contact decomposition of the titanium oxide granules become non-decomposed gas, or further result in loss of activity caused by covering the surface of the titanium oxide by the organics, thereby failing in decomposing the materials.

To this point, by selecting suitable amount of the titanium oxide granules and the amount of the treating waste plastics and/or organics, the decomposition reaction heat is utilized to maintain the suitable temperature for the decomposition of titanium oxide, thus minimizing the externally supplying energy. In addition, surplus reaction heat above the suitable temperature for decomposition can be recovered and reused through the cooling-control of the reactor. For example, the heat can be recovered in a form of steam and hot water. Therefore, the recovered heat can be utilized in hot water supply to the plant facilities or in melting snow. The uses of the recovered heat are, however, not limited to those given above.

[0030]

An amount to treat the waste plastics per hour is 3.0 to 40.0 kg, preferably from 6.0 to 35.0 kg, with respect to 100 kg of the titanium oxide granules of the present invention.

The optimum treating amount is obtained from the results in the following Example 4.

[0031]

A decomposition apparatus and a decomposition system according to the present invention will be described below referring to the drawings. In the following description, known technologies including drive source, air-supply blower, and screw feeder may not be described or given in the drawing. The shape of the decomposition apparatus, the arrangement of individual elements, and the scale of them are given preferentially for the convenience of illustration, and they are not the practical ones.

[0032]

As shown in Figs. 15 and 16, the means for treating waste plastics and organics 1, (Example 9), of the present invention has at least a reactor 3 in which a catalyst 2 is circulating, a circulation means 5 which circulates waste plastics and organics 4 charged into the reactor 3 together with the catalyst 2, an agitation means 6 which agitates the catalyst 2 and the waste plastics and organics 4, and a charge opening 7. The means for treating waste plastics and organics 1 further preferably has an air-supply blower 19 as a carrier gas (air) supply means, a heating means 9 which supplies heat necessary for the decomposition reaction, an air-blowing chamber 10, a partition wall 11 which allows smooth circulation of catalyst, a paddle 12 which changes the flow of catalyst, and an vent opening39. Furthermore, the means for treating waste plastics and organics 1 has a discharge opening 18 for metals and inorganics, the opening 18 being a means for directly recovering large lumps of metals and inorganics from the reactor.

[0033]

As shown in Fig. 16(1), the circulation means 5 is a twin screw feeder, which has each rotary shaft rotated by a drive source, equipped with a spiral blade. Each rotary shaft is inserted into the reactor. The twin screw feeder is preferably located in substantially horizontal position in the reactor. The arrow in Fig. 16(1) directs the clockwise circulation direction of catalyst. Change of the rotational direction of the twin screw feeder changes the direction of catalyst circulation to counterclockwise.

The rotary shaft 14 is rotated by a drive source M such as a motor.

Although in Fig. 16(1) two paddles 12 for changing the flow of the catalyst are located on a diagonal line of the reactor, the paddles may be changed to other means if only the means can change the flow of the catalyst.

As shown in Fig. 16 (2), if four screw feeders are located in substantially horizontal position in the reactor, the catalyst circulation is established.

Furthermore, as shown in Fig. 16 (3), if the reactor is in an elliptical shape, only two screw feeders can achieve the catalyst circulation.

In addition, as shown in Fig. 16 (5), if three screw feeders are located in substantially horizontal position in the reactor, the catalyst circulation is established and solid waste plastics and organics, which is not crushed, can be threw charge opening of solid waste plastics and organics 24 and decomposed around degradation site of waste plastics and organics 25 in the reactor 3.

When the circulation means 5 adopts screw feeder, the spiral blade 21 (refer to Fig. 21) also agitates the catalyst 2 with the waste plastics and organics 4, adding to performing the circulation step, thus the circulation means 5 also functions as the agitation means 6. That is, the screw feeder provides both the circulation means 5 and the agitation means 6. In addition, the spiral blade 21 is preferably equipped with an auxiliary blade.

[0034]

The above decomposition means can be provided with a means for separating and recovering metals and/or inorganics 15. As illustrated in Fig. 16(1), the separation and recovery means 15 may have a wire mesh 16 having an opening to allow greatest dimension of the catalyst 2 to pass through fitting to any position in the circulation route in the reactor 3. Preferably, however, the wire mesh 16 is fitted in the vicinity of the end point in the circulation route. A pocket 17 for recovering the metals and inorganics caught by the wire mesh is attached to the wire mesh 16. By locating the wire mesh 16 at higher position than the position of the pocket 17, (by creating a slope from the wire mesh to the pocket), the metals and inorganics caught by the wire mesh slide down into the pocket 17 by their self weight. Alternatively, by vibrating the wire mesh using a motor or the like, the metals and inorganics caught by the wire mesh 16 can be recovered by dropping them into the pocket 17. The pocket 17 has a two-stage shutter to allow the metals and inorganics to be recovered at arbitrary time during the decomposition .reaction. Nevertheless, when the metals and inorganics are accumulated to some volume, they may be recovered from the pocket 17.

According to the present invention, when the means i for separating and recovering metals and/or inorganics 15 separates and recovers the metals and inorganics from the pocket 17, there is no need of stopping the circulation means 5 and/or the agitation means 6 so that the throughput of the waste plastics and organics can maintain a high level.
In addition, when the separation and recovery means separates the metals and inorganics, there is no need of opening the reactor 3 so that the thermal efficiency of the decomposition apparatus and the decomposition system can maintain a high level. However, the separation and recovery of the metals and/or inorganics can naturally be done after opening the reactor 3.

Furthermore, when valuable metals are mixed in the waste plastics and organics 4, a discharge opening for metals and inorganics 18 is used as a method to efficiently recover the metals. For example, the waste plastics and organics 4 containing valuable metals are put in wire mesh (which allows the catalyst 2 to pass through and has shape of not to cause an obstraction of the catalyst-circulation (example, cube, polyhedron)), which wire mesh is then charged from the charge opening 7. The waste plastics and organics in the wire mesh are gasified in the course of circulating the shape wire mesh in the reactor. The metals which are not gasified are left behind in the wire mesh.
The shape wire mesh is directly recovered from the discharge opening of metals and inorganics 18, thereby allowing the metals remained in the shape wire mesh to be efficiently recovered.

Different from above case, when the size of the recovering metal is smaller than that of the catalyst 2, the means for separating and recovering metals and/or inorganics 15 is preferably a wire mesh located at:
lowermost position in a concave portion 13 in Fig. 16(4) for Example 9; and lowermost position in a returning passage 20 for Examples 10 and 11. If the metal-collecting vessel is placed below the wire mesh, the metals separated from the waste plastics and organics 4 can automatically be collected.

With the above structure, the decomposition apparatus of the present invention also provides an excellent method for separating and recovering metals and/or inorganics.

[0035]

According to an embodiment of the above examples of the present invention, as shown in Fig. 16 ( 4), the wire mesh 16 having an opening to allow greatest dimension of the catalyst 2 to pass through is positioned at right-bottom corner of the decomposition means 1 in plan view, (the wire mesh 16 is not shown in Fig. 16(4)). There is formed the concave portion 13 at peripherai area of the wire mesh 16, and the concave portion 13 connects with the charge opening 7. The concave portion 13 is equipped with the circulation means 5(D) to circulate the waste plastics and organics 4, charged from the charge opening 7, from the concave portion 13 to bottom-left corner of the decomposition means 1 in plan view. The paddle 12 is located at left-bottom corner and at right-top corner in the decomposition means 1 in plan view. The arrangement of these paddles 12 is not limited to that given in Fig. 16(4).

According to the above embodiment, the sieving operation is conducted corresponding to the mesh-opening of the wire mesh 16, thereby recovering the metals and inorganics left on the wire mesh 16 into the pocket 17, while the catalyst 2 is sieved down into the lower part of the concave portion, which is then recirculated in the reactor 3 together with newly charged waste plastics and organics 4 by the circulation means 5(D).

[0036]

The driving force of the circulation means 5(D) according to the present invention is not specifically limited, and screw feeder, conveyer (especially, bucket conveyer), paddle, piston and the like may be applicable.

The position of the charge opening 7 and of the means for separating and recovering metals and/or inorganics 15 may be close with each other, or may be opposing from each other, as needed. A preferable embodiment adopts the positioning of the charge opening 7 and the means for separating and recovering metals and/or inorganics 15 at close positions with each other because the decomposition of waste plastics and organics immediately after charged preferably uses the catalyst 2 which does not contain the waste plastics and organics in the course of decomposition.
The decomposition apparatus for waste plastics and organics of the present invention is an apparatus which can bring the catalyst 2 after circulated, (the catalyst which does not contain waste plastics and organics in the course of decomposition), to join the reaction of the newly charged waste plastics and organics. Different from the conventional decomposition apparatus, the apparatus of the present invention can decompose the waste plastics and organics at a high efficiency.

[0037]

For the decomposition means 1 according to the present invention, the waste plastics and organics 4 are not charged from the top of the reactor 3 onto the surface of the catalyst 2, but are preferably charged from the charge opening 7 to inside the circulating catalyst 2, as shown in Fig. 15. The inventors of the present invention found that the direct charge of the waste plastics and organics 4 to inside of the catalyst 2 attains high efficiency decomposition effect.
According to the decomposition means 1 of the present invention, however, decomposition is also attained when the waste plastics and organics 4 are charged from the charge opening 8 at top of the reactor 3 onto the surface of the catalyst 2.

Furthermore, according to the decomposition means 1 of the present invention, two or more charge openings may be given to allow conducting any of above charge methods.
In addition, the charge openings 7 and 8 are not only used for charging the waste plastics and organics 4 but also can be used for charging the catalyst 2.

The charge openings 7 and 8 in the following Examples and 11 are the same as those in above examples.
[0038]

As illustrated in Fig. 17, the means for treating waste plastics and organics 1, (Example 10) , of the present invention has at least the reactor 3 in which the catalyst 2 is accumulated, the agitation means 5(A) , 5(B) , and 5(C) , which circulate the waste plastics and organics 4 charged into the reactor 3 together with the catalyst 2, the agitation means 6 which agitates the catalyst 2 and the waste plastics and organics 4, the charge opening 7, and the returning passage 20. The means for treating waste plastics and organics 1 preferably further has the air-supply blower 19 as the carrier gas (air) supply means, the air-blowing chamber 10, the heating means 9 for supplying heat necessary for decomposition reaction, and the vent opening 39.

[0039]

As shown in Fig. 17, inside of the reactor 3 is divided into a first stage tank 31 and a second stage tank 32 which is located at higher position than the position of the first stage tank 31. The first stage tank 31 has a first permeable bottom 35 fixed in the reactor 3. The first permeable bottom 35 has an upstream end 33 at one end thereof in the longitudinal direction, (left side in.Fig. 17), and a discharge end 34 at the other end thereof (right side in Fig. 17 ). The second stage tank 32 has a second permeable bottom 38 fixed in the reactor 3. The second permeable bottom 38 has a downstream end 36 at one end thereof in the longitudinal direction, and a charge end 37 at the other end thereof.

[0040]

As illustrated in Fig. 17, the circulation means 5(A) is a screw feeder having the rotary shaft 14 equipped with the spiral blade 21, the rotary shaft being inserted into the first stage tank 31 in horizontal position along the longitudinal direction of the first stage tank 31. The circulation means 5(B) is a screw feeder in which the lower end portion of the rotary shaft 14 having the spiral blade 21 is positioned close to the discharge end 34 of the first stage tank 31, while the top end portion of the rotary shaft 14 is positioned upright close to the charge end 37 of the second stage tank 32. The circulation means 5(C) is the same as above circulation means 5(A) except that the circulation means 5(C) is positioned inside the second stage tank 32. Each of the rotary shafts 14 of the respective transfer means 5(A) , 5(B) , and 5(C) is rotated by a drive source M such as a motor.

[0041]

As illustrated in Fig. 18, each of the first and second permeable bottoms 35 and 38 is a wire mesh having a circular arc shaped cross section opened upward. The wire mesh is a material which receives the catalyst 2 and which allows the gas to pass therethrough. The permeable bottom is, however, not limited to wire mesh. Although the first and the second permeable bottoms 35 and 38 are isolated by a partition wall 30 from each other, their upper faces are opened and connected inside the reactor 3. Furthermore, the air-blowing chamber 10 is located beneath the first and the second permeable bottoms 35 and 38.

[0042]

In addition, as shown in Fig. 17, the second stage tank is located at a position higher than the position of the first stage tank. As a result, for returning the catalyst from the downstream end in the second stage tank to the upstream end in the first stage tank, no forceful transfer of the catalyst applying conveyer, screw feeder, and the like is required. The returning passage 20 is a chute which connects the upstream end 33 in the first stage tank 31 with the downstream end 36 in the second stage tank 32.

[0043]

Fig. 18 does not show the spiral blade 21, showing a blade row 22 mounted as the agitation means to the rotary shaft 14 of the respective circulation means 5. The blade row 22 is formed by fixing three blades 81 to the rotary shaft 14 at a pitch of 120 degrees. With the configuration, the circulation means 5 circulates the waste plastics and organics 4 together with the catalyst 2, (circulation means ), and agitates the catalyst 2 with the waste plastics and organics 4 favorably, (agitation means) . As a result, the catalyst 2 and the waste plastics and organics 4 are prevented from becoming lumps in gaps between the spiral blades 21 independent of the shape of catalyst 2 either in powder shape or in granular shape. More preferably, the spiral blade 21 has an auxiliary blade.

[0044]

Similar to the means for treating waste plastics and organics in Example 9, the wire mesh 16 having an opening to allow the catalyst 2 of large size to pass through as the means for separating and recovering metals and/or inorganics 15 may be fitted in the returning passage 20.
With the configuration, the metals and/or inorganics can be separated and recovered similar to Example 9.

[0045]

As illustrated in Fig. 19, according to another means for treating waste plastics and organics 1, (Example 11), the reactor 3 in a long size having the upstream end 33 at one end thereof in the longitudinal direction, and the downstream end 36 at the other end thereof has at least the circulation means 5, the agitation means 6 (riot shown) , the charge opening 8, and the returning passage 20. The reactor 3 preferably further has the air-supply blower 19 as the carrier gas (air) supply means, the heating means 9 which supplies heat necessary for decomposition reaction, the air-blowing chamber 10, and the vent opening 39.

The catalyst 2 is circulated between the upstream end 33 and the downstream end 36. When the waste plastics and organics 4 charged from the charge opening 8 to near the upstream end 33 in the reactor 3 is circulated from the upstream end 33 to the downstream end 36 in the reactor 3 together with the catalyst 2 by the circulation means 5, the waste plastics and organics 4 can be gasified in the course. Fig. 19 shows the reactor 3 in horizontal position.
However, the reactor 3 may be tilted so as the downstream end 36 to become higher than the upstream end 33. In that case, the catalyst 2 which is transferred by 'the circulation means 5 to the downstream end 36 can be brought to slide down through the returning passage 20 by its own weight, thus returning to the upstream end 33.

[0046]

Since the catalyst 2 is circulated by the circulation means 5 from the upstream end 33 toward the downstream end 36, the catalyst which reaches the downstream end 36 is guided by the returning passage 20 to return to the upstream end 33. As a result, the catalyst is circulated in the reactor so that the waste plastics and organics newly charged into the reactor can further be gasified by the action of the catalyst.

Although the catalyst which reaches the downstream end 36 is to return to the upstream end 33 by the screw feeder, paddle, bucket conveyer and piston may be applicable in Fig.
19.

[0047]

As illustrated in Fig. 20, a further means for treating waste plastics and organics 1, (Example 12), has at least the reactor 3 having the upstream end 33 at top of the drawing, and the downstream end 36 at bottom of the drawing, a cage 40 which can position waste plastics and/or organics, a charge opening 41 which allows the cage to charge into the reactor 3, and the returning passage 20.
The means for treating waste plastics and organics 1 further preferably has the air-supply blower 19 as the carrier gas (air) supply means, the heating means 9 for supplying heat necessary for decomposition reaction, a mesh 42 which controls the amount of dropping catalyst, and the vent opening 39.

There may be installed an agitation apparatus in the vicinity of the upstream end 33 and of the downstream end 36 to assure uniform distribution of the catalyst. Further in Fig. 20, the carrier gas is directly supplied into the reactor. However, the carrier gas may be supplied into the reactor via an air-blowing chamber as in the case of Examples 9 to 11. The vent opening 39 also functions as the charge opening to charge the catalyst into the reactor.
The catalyst charge opening, however, may be provided separately.

A cage 40 containing waste plastics and organics is placed in the reactor 3 through the charge opening 41. Then, during the course of dropping the catalyst from the upstream end to the downstream end in the reactor 3, the waste plastics and/or organics contact with the catalyst and are gasified.

[0048]

Since the catalyst 2 drops (circulates) from the upstream end 33 to the downstream end 36, the catalyst which reaches the downstream end 36 is guided by the returning passage 20 to return to the upstream end 33. As a result, the catalyst 2 circulates in the reactor 3. The driving force for returning the catalyst 2, which rea'ches the downstream end 36, to the upstream end 33 guided by the returning passage 20 is a screw feeder which is structured by a rotary shaft, rotated by the driving source, having a spiral blade thereon, and being inserted into the returning passage. The driving force, however, is not i specifically limited, and other driving force such as bucket conveyer, paddle and piston may be applied.

The cage 40 capable of positioning the waste plastics and/or organics is preferably a wire mesh which allows the flowing-down catalyst 2 to pass through, which does not allow the charged waste plastics and organics to pass through, and which does not allow the metals and inorganics which are mixed in the waste plastics or which are vapor-deposited or adhered to at least a portion of the waste plastics to pass through. For attaining further efficient contact between the catalyst 2 and the waste plastics and organics, the cage 40 may be rotated and/or vibrated in the reactor 3.

Even if fine waste plastics and organics pass through the cage 40 to drop onto the downstream end 36, the action of the catalyst 2 which reaches the downstream end 36 gasifies the waste plastics and organics.

The mesh 42 which controls the amount of dropping catalyst is preferably wire mesh, which uniformly flows down the catalyst 2 from the upstream end to the downstream end. The mesh 42 is preferably made by two or more sheets of wire mesh, and sliding of pluralities of wire meshes with each other controls the amount of flowing-down catalyst.

[0049]

Different from the means for treating waste plastics and organics 1 in the above Examples 9 to 11, the means for treating waste plastics and organics 1 in Example 12 illustrated in Fig. 20 does not need the agitation means for agitating the catalyst with the waste plastics and organics. Accordingly, the size of the reactor 3 is designed small compared with the reactor size of the conventional decomposition apparatus. Furthermore, the waste plastics and organics can be placed in the cage 40 in the reactor 3 through the charge opening 41 without crushing them. As a result, there is no need of the crushing apparatus to crush the waste plastics and organics.

In addition, the means for treating waste plastics and organics 1 illustrated in Fig. 20 may bring to horizontal position as in the case of Example 9, (refer to Fig. 16 ( 1 ) to ( 5)). In this case, the screw feeder as the circulation means is applied to circulate the catalyst 2.
Furthermore, the catalyst 2 may be circulated in the reactor 3 by rotating the cage 40 containing the waste plastics and organics 4. The operation increases the contact efficiency between the catalyst 2 and the waste plastics and organics 4, thereby conducting efficient decomposition of waste plastics and organics 4.

[0050]

For any of the above described means for treating waste plastics and organics in above examples, the screw feeder has the following advantages. The screw feeder plays the role of the circulation means 5 and of the agitation means 6 at a time. Independent of the shape of catalyst 2 in powder or in granule, the screw feeder surely circulates the catalyst 2 without retaining at a position.
Increase in the volume of catalyst 2 accumulated in the reactor 3 consumes considerably large torque to rotate the agitation blade. To this point, compared with the conventional agitation blade, the screw feeder can decrease the increased amount of torque to rotate the rotary shaft 14. Consequently, use of screw feeder as the circulation means 5 and/or the agitation means 6 is advantageous for increasing the capacity of the reactor 3 in the means for treating waste plastics and organics.

As another example, public known rotary kiln and apparatus comprising reactor, in which the several paddle place, can circulate the catalyst in the reactor.

[0051]

The heating means 9 of any of above examples is the one to heat the supplied air or the like via the carrier gas supply means such as the air-supply blower 19. That is, in the step of supplying the air fed by the air-supply blower and the like into the air-blowing chamber 10, the heating means 9 heats the air to heat the catalyst to the catalyst-activation temperature necessary for the decomposition reaction. Although electricity is preferred as the heat source, the heat source is not specifically limited. Referring to Fig. 17, the hot air is supplied to the air-blowing chamber 10, and ascends through the fist permeable bottom 35 into the reactor 3.
The heating means is required to increase the temperature of catalyst 2 to the catalyst-activation temperature at the beginning of the decomposition reaction. Once the decomposition reaction proceeds, however, the decomposition heat of the waste plastics and organics keeps the catalyst-activation temperature so that the heating means is not necessarily required after that period. For the case that the waste plastics and organics 4 generate small amount of heat, however, the heating means 9 heats the air supplied from the air-supply blower 19, as needed, to supply the heat to the reactor 3.

[0052]

Any of the above air-blowing chamber 10 plays two roles of what is called the carrier gas supply tank and of a tank to supply heat necessary in the initial period of reaction. With the presence of the air-blowing chamber 10, a plurality of holes opened on the first permeable bottom 35 allows the carrier gas supplied from the air-supply blower 19 or the like to uniformly distribute to entire inside of the catalyst.

[0053]

The means for treating waste plastics and organics 1 according to the present invention is preferably a spiral blade not intermittently divided, more preferably a spiral blade having small auxiliary blade between the pitches of the spiral blade, and most preferably a spiral blade with attached small auxiliary blade 85. The presence of the auxiliary blade 85 further increases the contact efficiency between the catalyst 2 and the waste plastics and organics 4.

Other than the above, the agitation means in any of the examples may be a spiral blade which is intermittently divided. That is, as shown in Fig. 21(a), if the spiral blade forms a plurality of notches 82 at appropriate positions, a portion of circulating powdery or granular catalyst 2 and waste plastics and organics 4 pass through the notch 82. The action induces the agitation of the powdery or granular catalyst 2 with the waste plastics and organics 4, thus playing the role of both the circulation means 5 and the agitation means 6. Alternatively, as shown in Fig. 21 (b) , the agitation means 6 may be a plurality of axial flow blades 83 which rotate centering on the rotary shaft 14 to give driving force to the powdery or granular catalyst 2 and the waste plastics and organics 4. In that case, the spiral blade may be eliminated, or a projected piece 84 may be attached to adequate position on the rotary shaft 14.

[0054]

Furthermore, the apparatus for decomposing waste plastics and organics according to the present invention contains a means for treating oxidation catalyst adding to the above means for treating waste plastics and organics, and preferably contains a lime neutralization treatment means.

[0055]

The decomposition apparatus according to the present invention can have one or more of the following-described means, (refer to Fig. 22).

[0056]

(1) Alumina catalyst treatment means The method or apparatus for decomposing waste plastics according to the present invention preferably adopts the "alumina catalyst treatment means" before the oxidation catalyst treatment step. The alumina catalyst treatment means prevents adhesion of Si, Mg, Cr, Pb, Fe, and the like, or dust or the like to the oxidation catalyst.
The alumina catalyst is preferably positioned before the oxidation catalyst tank. An alumina catalyst tank may be installed separately. The heating temperature of alumina catalyst is preferably 350 C or above.

[0057]

(2) Crushing means The crushing means according to the present invention is a means (apparatus) which crushes waste plastics and organics to a size (pieces) suitable for the reactor of the means for treating waste plastics and organics.

Accordingly, the crushing means is not specifically limited if only the means can crush the waste plastics and organics.
Preferably, however, the crushing means has a capacity being able to crush corrugated cardboard, and in particular for the case of treating infectious treatment articles in the medical field, the crushing means preferably has two-stage shutter and has sterilization lamp.

[0058]

(3) Carrier gas supply means The carrier gas supplied to the reactor is preferably oxygen. Normally, however, air is applied. Alternatively, an inert gas may be applied as needed. The method for supplying the carrier gas uses the air-supply blower 19 and the like, and supplies the carrier gas distributing uniformly into the titanium oxide granules. The supply rate is preferably 1.3 to 4.0 times the theoretically required oxygen amount using air at normal temperature, containing oxygen by an amount necessary for oxidation and decomposition of the decomposing organics. From the point of decomposition efficiency, 1.6 to 3.0 times thereof is preferred. Although blower and the like can be used, they are not specifically limited.

For example, a plurality of holes are provided on the bottom of the reactor 3, through which holes oxygen or the like is supplied. According to the means for treating waste plastics and organics of the present invention, the carrier gas, preferably air, is directly supplied into the catalyst circulating in the reactor through the pluralities of holes opened on the bottom of the reactor, which significantly increases the decomposition efficiency compared with the conventional method of supplying the carrier gas from top of the reactor.

[0059]

Dust collection means The dust collection means according to the present invention recovers metals and inorganics and/or catalyst discharged and scattered from the reactor in the means for treating waste plastics and organics. The recovered catalyst can be reused. As shown in Fig. 22, preferably the dust collection means has two of them sandwiching the lime neutralization treatment means. Furthermore, the first dust collection means is preferably a cyclone dust collection means (apparatus), and the second dust collection means is preferably a dust collection means (apparatus) equipped with bag filter.

(4) Cyclone dust collection means (first dust collection means) The catalyst recovered by the first dust collection means is collected by a cyclone, and then is recycled to the reactor through the returning passage connected to the reactor, thereby utilizing for the catalyst circulation.
The inventors of the present invention confirmed, by an experiment, that the first dust collection means recovers about 95% to about 99% of the catalyst.

(5) Dust collection means equipped with bag filter, (second dust collection means) If the catalyst recovered by the second dust collection means is fine powder, the catalyst can be returned to the reactor after forming the fine powder catalyst to dumplings of a desired size.

[0060]

(6) Heat exchange means The heat exchange means is a means for recovering heat from a hot air containing carbon dioxide and trace amount of water through the heat exchange. The obtained heat source can be utilized in the heating means, though the use thereof is not specifically limited. For example, the uses thereof include the heating of supply air, the supply to a preheater, the supply to hot water in the plant facilities, or to melt snow.

[0061]

(7) Preheater means Before the oxidation catalyst treatment, preheating (preliminarily heat holding) is preferred by a heater means.
The preheating is suitable for the oxidation catalyst to surely act in the reaction in the case of low concentration gas or of low heat generation in the decomposition tank.

[0062]

(8) Exhaust blower means The exhaust blower means is a means to discharge a safe air containing carbon dioxide gas and trace amount of water, generated by decomposition of waste plastics and organics, to outside the decomposition apparatus for the waste plastics and organics of the present invention.

[0063]

(9) Cooling means The cooling means is a means to cool the catalyst in the reactor in the case that the reactor exceeds the optimum activation temperature zone of the catalyst. The cooling method recovers the heat from the reactor preferably by flowing cooling water external or internal of the reactor, (preferably using latent heat or heating the cooling water) The method is, however, not specifically limited, and cooling water may be introduced into blade or the like.

[0064]

(10) Heat recovery means The heat recovery means is a means to hold or utilize the heat obtained from the cooling water. The recovered heat can be used in hot-water supply in the plant facilities or in melting snow. The uses of the recovered heat are, however, not limited to those given above.

[0065]

(11) HC1 continuous measurement means The HC1 continuous measurement means is a means to confirm whether the HC1 is absorbed and removed by the lime neutralization treatment means. That is, the means prevents the HC1 concentration at or above specified level from emitting outside the decomposition apparatus for waste plastics and organics of the present invention.

[0066]

(12) CO continuous measurement means The CO continuous measurement means is a means to confirm whether the oxidation catalyst treatment means converts CO into carbon dioxide. That is, the means prevents the CO concentration at or above specified level from emitting outside the decomposition apparatus forwaste plastics and organics of the present invention.

[0067]

(13) Alarm means Although the decomposition apparatus of the present invention conducts safe operation conforming to the legal regulations, the apparatus stops operation if the safe zone is overridden even to a slight degree. That is, the alarm means notifies the abnormality when the measurements in the HC1 continuous measurement means and/or the CO continuous measurement means detect CO or HC1 concentration above the standard level even at a slight degree. Preferably, in case of abnormality detection, toxic gases are not allowed to emit outside the apparatus using a safety means (apparatus).

[0068]

Decomposition system of waste plastics and organics of the present invention The decomposition system of waste plastics and organics of the present invention uses any of the above-described decomposition apparatuses, and furthermore uses favorable catalyst and/or favorable decomposition condition to conduct the decomposition of waste plastics and organics.

The decomposition system of waste plastics and organics of the present invention can use a decomposition apparatus given in Fig. 23, containing the conventional means for treating organics, having a batchwise reactor, thus conducting the decomposition of waste plastics and organics.using further suitable catalyst and decomposition condition, (refer to Fig.6).

[0069]

Further, according to the decomposition method or decomposition system of waste plastics and organics of the present invention, when the waste plastics to be treated are various medical waste plastics, such as polyvinylchloride, polyurethane, and Teflon , there are generated hydrogen chloride, sulfur compounds, hydrogen fluoride, cyan gas, nitrogen-containing compounds, in the treatment process. Hydrogen chloride and the like would not be emitted into atmosphere as they are. Therefore, the "lime neutralization treatment process" is introduced.
The lime neutralization treatment process means a process of adsorbing to remove hydrogen chloride, sulfur compounds, hydrogen fluoride, cyan gas, nitrogen-containing compounds, and the like to prevent them from being emitted into atmosphere. The lime neutralization treatment means is a means (apparatus) for adsorbing to remove those not to emit them into atmosphere.

Specifically the process uses a lime material consisting mainly of quicklime, slaked lime, or their mixture, which lime material is then molded into 2 mm or larger porous pellet of hydrogen chloride-absorber. Thus prepared pellets are packed in a removal vessel. The gases containing the aforementioned decomposed waste plastics-originated hydrogen chloride, and the like are brought to pass through the removal vessel, thus letting the hydrogen chloride, and the like react and absorb into the pellets.

[0070]

The lime material according to the present invention may be quicklime, slaked lime, or a mixture of them. It is preferred that the lime material be molded to 2 mm or larger porous pellet. The method of molding the pellets is arbitrary, and simple kneading with water to dry or to fire may be applied. For examples, powder of lime material is mixed with water to a moldable hardness, which is then extruded from an extruder to cut into pellets.

The shape of the pellet is arbitrary, and spherical, disk, circular cylinder shapes may be adopted. The size of pellet is 2 mm or larger. If the size is smaller than 2 mm, the pellets become close to powder, which raises problems on apparatus caused by pressure loss of air, on emission and entrainment of powder, on filter, and the like.
Although coarse pellets can be used in principle, increased size decreases efficiency. For practical applications, size of 10 mm or smaller is preferable, and an experiment given by the inventors of the present invention showed a favorable range of size from 3 to 7 mm.

[0071]

The lime material used in the "lime neutralization treatment process" according to the decomposition method of waste plastics of the present invention prefers to use quicklime rather than slaked lime. The finding was derived from a measurement of chlorine-fixing rate using lime materials (porous quicklime and slaked lime) given by the inventors of the present invention (referring to Fig. 2).

[0072]

Further, the water content (ppm) in the lime material is preferably small to 20% or less, and more preferably 10%
or less. The finding was derived from a measurement for various water contents in lime materials (slaked lime and quicklime) given by the inventors of the present invention (referring to Fig.3).

[0073]

The heating temperature in the lime neutralization treatment process is preferably from 150 C to 500 C, more preferably from 200 C to 400 C, and most preferably from 250 C to 350 C. The finding was derived from calculation of the theoretical chlorine-fixing concentrations (referring to Fig. 4) . In the related art, the adsorption treatment of hydrogen chloride and the like is conducted at normal temperature and using slaked lime. The incineration furnace or the like in the related art conducts the adsorption treatment of hydrogen chloride and the like after decreasing the temperature of flue gas after combustion. Since the powder of slaked lime is used in the related art, the handling of slaked lime is troublesome, and the apparatus is large using bag filters with large area and in switching operation. However, the adsorption and removal treatment of the lime material according to the present invention can be done at the flue gas temperature after the decomposition reaction.

[0074]

For the lime neutralization treatment process, a lime neutralization treatment apparatus (means) is suitably employed. In the lime neutralization treatment apparatus, there is utilized a packed tank. The pellets drop from top of the packed tank toward the bottom thereof, while the gas to be treated flows from bottom to top while contacting with the lime pellets. A pellet-stock portion is located at upper portion of the packed tank, and a discharge portion for the used pellets is located at lower portion of the packed tank. The packed tank is isolated from the reaction vessel tank by a shutter, a rotary valve, or the like. The discharge rate is controlled by the treatment concentration and the treatment rate. The apparatus is provided with a heater to prevent deliquescence phenomenon. The decomposition method conducts the treatment at a high temperature so that no deliquescence phenomenon appears.
Nevertheless, a heater process is preferably applied to respond to the non-heating state.

[0075]

An "oxidation catalyst treatment process" may be introduced into the decomposition method of waste plastics and organics, and a "means for treating oxidation catalyst"
may be introduced into the decomposition system of waste plastics and organics according to the present invention.

The oxidation catalyst treatment process is conducted, because the waste plastics and organics decomposed by the heated titanium oxide catalyst have a possibility of being not-perfectly decomposed, and that the non-reacting matter and intermediate products may leave the reactor. Thus, according to the present invention, the succeeding oxidation catalyst treatment process is preferably conducted for further oxidation or decomposition. The oxidation catalyst treatment process is preferably given after the lime neutralization treatment process.

[0076]

The oxidation catalyst is the one which generally initiates oxidation and decomposition reactions at lower temperature and shorter time than those in the case of non-catalytic reactions. There are varieties of known oxidation catalysts of that type, and they are commercially available. Generally the reaction temperature is in a range from 200 C to 500 C. According to the present invention, however, 300 C or above, and preferably 350 C
or above, is adopted. That is because, for the case of decomposition of varieties of waste plastics and organics, the generated non-decomposed gas is not necessarily a single substance. Therefore, 350 C or higher temperature is preferred to completely decompose mixed non-decomposed gases. From the point of efficiency and of effectiveness of apparatus, the present invention prefers a honeycomb type catalyst.

Platinum catalyst is suitable for a reaction converting carbon monoxide to carbon dioxide, and for decomposition of lower hydrocarbons and VOCs (volatile organic compounds). Palladium catalyst is suitable for methane gas decomposition. As of these catalysts, palladium and platinum catalysts are preferred in the present invention. The treatment order of application of them is preferably palladium catalyst followed by platinum catalyst.

It is preferable to conduct a pre-heating treatment (previous heat retention) before the catalyst treatment, in order to treat the oxidation catalyst steadily when a gas having a low concentration flows into, or the heat generation at the decomposition tank is low.

[0077]

The oxidation catalyst affects considerably the oxidation of non-combustion substances such as carbon monoxide and hydrocarbons. With oxygen and at a certain temperature, almost all the substances are immediately oxidized to decompose. Carbon monoxide becomes carbon dioxide, and hydrocarbons become carbon dioxide and water.

[0078]

Further, the method of decomposing waste plastics according to the present invention preferably adopts the "alumina catalyst treatment process" before the oxidation catalyst treatment process. The alumina catalyst treatment process prevents adhesion of Si, Mg, Cr, Pb, Fe, and the like, or dust or the like to the oxidation catalyst.
The alumina catalyst is preferably positioned before the oxidation catalyst tank. An alumina catalyst tank may be installed separately (referring to Fig.5). The heating temperature of alumina catalyst is preferably 350 C or above.

[0079]

As described above, the present invention can combine: the oxidation and decomposition by titanium oxide;
the removal of hydrogen chloride, hydrogen fluoride, sulfur compounds, nitrogen-containing compounds, and the like using the l.ime neutralization treatment; removal of dust and the like by the alumina catalyst treatment; and/or further oxidation and decomposition by an oxidation catalyst.

[0080]

The flow of decomposition method or decomposition system for waste plastics and organics for waste plastics and organics according to the present invention is illustrated in Fig. 6. As given in Fig. 6, the decomposition method of the present invention can contain, adding to the above-described processes, the air-supply process, the cooling process using cooling water, the emitted titanium oxide recovery and reuse process using cyclone separator, the heat exchange process using heat exchanger, the dust collection process to remove fine powder, the exhaust gas process using exhaust blower, the exhaust gas safe control process using hydrogen chloride detector, and the exhaust gas safe control process using CO detector.

i The above individual steps can be naturally eliminated or modified.

[0081]

Furthermore, the decomposition method or decomposition system for waste plastics and organics for waste plastics and organics according to the present invention may adopt the "process of separating metals and/or inorganics." The waste plastics and decomposed materials which are oxidized or decomposed by the above heated catalyst may contain metals such as stainless steel, iron, aluminum, and copper, and inorganics, and may have vapor-deposited or adhered metals on the surface thereof.
Those kinds of metals are not decomposed, different from the waste plastics and organics, and enter the catalyst to accumulate in the reactor. Therefore, the process of separating metals and/or inorganics separates and recovers the metals from the catalyst. Not only the waste, there are many materials in which the plastics or organics are integrated with metals and inorganics. The present invention is able to decompose only the plastics or organics in the materials integrated with metals and inorganics, thus taking out the metals and inorganics.

[0082]

For the method of separating and recovering metals and/or inorganics, for example, a sieve having an opening to allow greatest dimension of the granular titanium oxide catalyst to pass through is located in the reactor. When only the metals and inorganics caught by the wire mesh are taken out, the metals and inorganics left in the reactor become minimum volume. Alternatively, the catalyst and the metals and inorganics may be separated from each other by the difference in the specific gravity. Metals such as aluminum thin foil which have smaller specific gravities than that of catalyst float above the catalyst during the process of agitating the titanium oxide catalyst, thus they are selectively recovered. If the recovering metal is a magnetic one, magnetism or magnetic field may be used to separate the metal from the catalyst. The method of separating metals from catalyst is not limited to above described ones.

[0083]

The agitation of the catalyst composed of the titanium oxide granules and the waste plastics is conducted at a rotation speed of 5 rpm to 70 rpm, preferably 10 rpm to 40 rpm, depending on differences of a volume of the reactor, the shape of the agitation blade and the agitation method.
It is preferable to employ the same rotation speed even if the reactor is for batch type or circulation type.

This value is determined by considering the fact that abrasion of the titanium oxide become large when the rotation speed is too high, and that contact efficiency of the titanium oxide and waste plastics and/or organics is lowered when the rotation speed is low.

In other words, it is preferable to apply a load at 0.75 kW to 1.5 kW to 100 kg of the titanium amount while regulating an inverter at 30 Hz to 70 Hz.

[0084]

The carrier gas supplied to the reactor is preferably oxygen. Normally, however, airisapplied. Alternatively, an inert gas may be applied as needed. The method of supplying the carrier gas preferably supplies the carrier gas distributing uniformly into the titanium oxide granules.
The supply amount is preferably 1.3 to 4.0 times the theoretically required oxygen amount using air at normal temperature, containing oxygen by an amount necessary for oxidation and decomposition of the decomposing organics.
From the point of decomposition efficiency, 1. 6 to 3. 0 times thereof is preferred. For example, there is a method of supplying oxygen and the like from a numerous small holes provided on the bottom of the reactor.

[0085]

The waste plastics and organics applicable to the decomposition method, decomposition apparatus, and decomposition system according to the present invention are not specifically limited, and, adding to the general-purpose thermoplastic plastics such as polyethylene and polypropylene, the thermosetting plastics can be decomposed and gasified by the method of the present invention. Although the waste plastics and organics are preferably crushed to several millimeters square, in view of decomposition efficiency, they are also able to be decomposed without crushing.

The materials which can be decomposed by the decomposition system for waste plastics and organics according to the present invention include but are not specifically limited to organics, and examples of these applicable materials are: plastics including polyethylene, polypropylene, polyester, polyethyleneterephthalate, polystyrene, polycarbonate, polyurethane, polyvinylchloride, Teflon ; diaper; artificial dialyzer;
anticancer drugs; treated articles relating to gene research; information-relating device terminals;
confidential information-relating devices (such as CD-R);
waste plastics generated from automobiles and household electric appliances; valuable metal recovery; and separation of organics from metals and inorganics. For the case of medical waste, there are often existing metals such as stainless steel and aluminum depending on the uses, or existing vapor-deposited or adhered metals on the surface thereof. The waste plastics are not limited to the used plastics but also include non-used but unnecessary plastics and organics.

[0086]

The present invention will be described in the following by referring to examples, but the present invention is not limited to those examples.

[Example 1]

[0087]
Study of heating temperature The optimum heating temperature for the catalyst composed of the titanium oxide granules and the waste plastics was studied. Conditions are as follows:

1. Experimental device (reactor): Agitation type decomposition experimental machine (2200 mL) 2. Air flow to be introduced: 50 L/min 3. Inside temperature of reactor: 300 C, 320 C, 350 C, 380 C, 400 C, 420 C, 450 C, 480 C, 500 C, 530 C, 550 C, 560 C, 570 C, 580 C, 600 C

4. Used catalyst: 700 g of titanium oxide catalyst (SSP-G
Lot.051108 available from SAKAI CHEMICAL INDUSTRY Co., Ltd.) 5. Waste plastics: Polyethylene pellets 1 g/one charge For measurement of a gas concentration (NOx, CO, C02, 02, CH4) , a gas concentration continuous measuring device PG-250 (manufacture: HORIBA, Ltd.) was used.

[0088]

The waste plastic was decomposition-treated at the above temperature. The results are shown in Fig. 7.
The waste plastic was not able to decomposed at a heating temperature of 300 C. This is because, when a heating temperature is 300 C or less, the titanium oxide has no activity and no decomposition ability functions, the waste plastic was merely melted at a temperature of 300 C
and almost all thereof adhered and was deposited on the surface of the titanium oxide. When heating at 300 C
continuously; the surface of the titanium oxide was covered with the organics derived from the waste plastics to make the catalytic activity of the titanium oxide lost.

At a heating temperature of 350 C, though the reaction was slightly occurred, the result was the same as that at 300 C.

At a heating temperature of 600 C, the waste plastic was burnt out at the same time when charged into the reactor.
That is, at a heating temperature of 600 C or more, the waste plastic ignited at the instant when charged. This is not decomposition of the waste plastic by catalytic action of the titanium oxide, and a large amount of un-decomposed gases were generated due to burning.

At heating temperatures of 570 C and 580 C, the waste plastic ignited and was burnt out after 5 to 15 seconds from charge.

At a heating temperature of 350 C, 35 to 45 minutes was required for one decomposition.

At a heating temperature of 380 C, 15 to 25 minutes was required for one decomposition.

At a heating temperature of 400 C, 6 to 8 minutes was required for one decomposition.

At a heating temperature of 420 C, 3 to 5 minutes was required for one decomposition.

At a heating temperature of 450 C, 1 minute and 30 seconds to 2 minutes was required for one decomposition.
At a heating temperature of 480 C, 30 to 40 seconds was required for one decomposition.

At a heating temperature of 500 C, 30 seconds was required for one decomposition.

At a heating temperature of 530 C, 25 seconds was required for one decomposition.

At a heating temperature of 550 C, 20 seconds was required for one decomposition.

At a heating temperature of 560 C, 20 seconds was required for one decomposition.

At heating temperatures of 350 C to 420 C, since the decomposition proceeded slowly, the decomposition was not efficient and was not practical. From 450 C to 560 C, good decomposition of the waste plastic was observed. Further, most efficient decomposition of the waste plastic was observed at a heating temperature of 480 C from viewpoints of decomposition efficiency, reaction stability, safety due to variation range of reaction temperature, and the like.

As the results thereof, it has been found that the optimum heating temperature was in a quite narrower range than the heating temperature known in the prior arts, and a highly efficient decomposition reaction was achieved only in that range. The practical application also corresponded to that range. When experiments were conducted by changing an amount of oxygen supply, though the decomposition rate changed, the optimum heating temperature did not change.

[Example 2]

[0089]
Determination of dioxin generated during the processes of the decomposition method according to the present invention An amount of dioxin generated during the processes of the decomposition method according to the present invention was determined. The used plastic was a waste plastic containing 20 % polyvinylchloride that generates a large amount of dioxin and hydrogen chloride by burning.
The measuring conditions were as follows:

1. Decomposition apparatus: 100kg titanium oxide agitation type decomposition apparatus 2. Used catalyst: 100 kg of titanium oxide catalyst (SSP-G
Lot.050323 available from SAKAI CHEMICAL INDUSTRY Co., Ltd.) 3. Kind and amount of used plastic: Mixture of polyvinylchloride and polyethylene (20:80%by weight), 117 g/min i 4. Heating temperature of titanium oxide granules: 480 C
5. Air flow to be introduced: 3.9 m3/min 6. Lime neutralization treatment process 7. Oxidation catalyst treatment process The concentration of the gases was measured by the particular research organization.

[0090]

The results of determining amounts of dioxin generated during the processes of the decomposition method according to the present invention are shown in Fig. 8. The measured values of concentrations of dioxins and coplanar PCB in any of flue gas (after oxidation catalyst treatment) , titanium oxide granules in the decomposition tank (catalyst in decomposition tank), lime substance after the lime neutralization treatment process (neutralizing agent in the neutralization apparatus) were low, and further, a toxicity equivalent was very small. The results revealed that the amount of dioxin generated during the processes of the decomposition method according to the present invention was lower than the legal control value.

Generally, when burning out the material containing 20 % vinyl chloride, large amount of dioxin and hydrogen chloride is generated, and thus treatment has been difficult. Also, by using a usual incinerator, generation of dioxin occurs at the initial time depending on the condition of charged substance, and an incinerator ash containing a large amount of dioxin remains. When carrying out at a high temperature treatment, it is hard to maintain because large heat energy is required and the incinerator deteriorates seriously. The present invention, however, makes it possible to conduct the treatment at a lower temperature and to maintain the incinerator easier in comparison to the prior incinerator, and moreover, any dioxin that is legally controlled is not generated.
Therefore, the decomposition method according to the present invention is a groundbreaking decomposition method, because no organic residue remains even though the decomposition is conducted at a low temperature.

[Example 3]

[0091]
Study of specific surface area of catalyst composed of titanium oxide granules The optimum specific surface area of catalyst composed of titanium oxide granules was studied.
Conditions are as follows:

1. Experimental device (reactor): Agitation type decomposition experimental machine 2. Heating method: Air-introducing heating system 3. Air flow to be introduced: 50 L/min 4. Inside temperature of reactor: 480 C
5. Agitation speed: 35 rpm 6. Used catalyst: 700 g of titanium oxide catalyst (SSP-G

Lot.051108 available from SAKAI CHEMICAL INDUSTRY Co., Ltd.) 7. Waste plastic: Polyethylene 1 g/min charge 8. Specific surface area of catalyst composed of titanium oxide granules: 30 m2/g, 40 m2/g, 70 m2/g [0092]
(1) Titanium oxide granules having specific surface area of 30 m2/g and a micropore volume of 0.20 cc/g The polyethylene of waste plastic was charged to the titanium oxide granules in the reactor. Just after the charge, the waste plastic was turned black as a lump, and then the lump was broken into a powder form. The waste plastic in the form of powder was spread all over the catalyst and the whole of the catalyst was turned black.
The catalyst turned black changed in its color to the original color gradually, and was returned to the original color in about 40 to about 60 seconds. When the lump was broken to be spread just after the charge of the waste plastic, a smoke was observed slightly. Efficiency was bad because of long decomposition time.

(2) Titanium oxide granules having specific surface area of 40 m2/g and a micropore volume of 0.23 cc/g The polyethylene of waste plastic was charged to the titanium oxide granules in the reactor. Just after the charge, the waste plastic was turned black as a lump, and then the lump was broken into a powder form. The waste plastic in the form of powder was spread all over the catalyst and the whole of the catalyst was turned black.
The catalyst turned black changed in its color to the original color gradually, and was returned to the original color in about 30 to about 40 seconds. Decomposition efficiency was good.

(3) Titanium oxide granules having specific surface area of 70 m2/g and a micropore volume of 0.26 cc/g The polyethylene of waste plastic was charged to the titanium oxide granules in the reactor. Just after the charge, the waste plastic was turned black as a lump, and then the lump was broken into a powder form. The waste plastic in the form of powder was spread all over the catalyst and the whole of the catalyst was turned black.
The catalyst turned black changed in its color to the original color gradually, and was returned to the original color in about 30 to about 45 seconds. Breaking up and spreading of the lump prepared just after the charge of the waste plastic occurred slowly. In addition, handling was bad because the titanium oxide itself was broken up into a powder form and spread.

From the above results, the waste plastic was decomposed sufficiently when the specific surface area was not less than 30 m2/g. The waste plastic was, however, decomposed more efficiently when the specific surface area was not less than 35 m2/g. When the specific surface area i is made too large, the heat resistance was low and the granules were broken up to a powder form.

Therefore, it has been found that the titanium oxide granules having a specific surface area from 33 mZ/g to 65 m2/g, more preferably from 35 m2/g to 50 m2/g can decompose the waste plastic at a high efficiency.

[Example 4]

[0093]
Study of the optimum treating amount by catalyst composed of titanium oxide granules The optimum treating amount by catalyst composed of titanium oxide granules was studied.

A maximum amount being able to be treated was calculated by gradually increasing a treating amount of polystyrene pellets. The treatments were conducted by using 350 g titanium catalyst at 1 g/min, 2 g/min x 5 times, 2 g/min x 5 times continuous feed, 3 g/min continuous feed, 4 g/min continuous feed, 5 g/min continuous feed.

In the case of 4 g/min continuous feed, vigorous ignition and burning were happened. Because turning black of the catalyst was extremely increased even in the case of 3 g/min, it has been decided that a maximum amount being able to be treated is 2 g/min continuous feed.

[0094]

From the above experiments, a weight ratio of the maximum amount of waste plastic being able to be treated with respect to the used amount of the catalyst is 100: 34.2.
From the results, as a maximum amount being able to be treated, it has been found that an optimum amount to treat the waste plastic per hour with respect to 100 kg of the titanium oxide granules according to the present invention is 3.0 kg to 40.0 kg, preferably 6.0 kg to 35.0 kg.

[Example 5]

[0095]
Decomposition of polyethylene and polystyrene The aforementioned each waste plastic was decomposed by using the titanium oxide granules (SSP-G Lot.051108 available from SAKAI CHEMICAL INDUSTRY Co., Ltd.) heated at 480 C. Details are as follows.

As a decomposition apparatus, a cylindrical vessel and a heating device controlled by heated air were used.
The vessel was charged with 700 g of titanium oxide.
Subsequently polyethylene pulverized to particles was fed by 0. 6 g/30sec each and agitated at 35 rpm with an agitator.
All of the exhaust gas at a flow rate of 100 L/min was recovered. Substances contained in the exhaust gas were determined with time.

For measurement of a gas concentration, a gas concentration continuous measuring device PG-250 (manufacture: HORIBA, Ltd.) was used.

[0096]

After 30 seconds from the feed of polyethylene, exhaustion of carbon dioxide gas and CO were observed in the exhaust gas. After that, the concentrations were returned to a normal state. Synchronizing with that, the fed polyethylene was turned black as a lump, and then the lump was broken into a powder form. The waste plastic in the form of powder was spread all over the catalyst and the whole of the catalyst was turned black. The catalyst turned black returned to the original color gradually. The waste plastic was decomposed after 30 seconds without smoking.
Separately, when using inactive titanium oxide granules having the same particle size as a control, the polyethylene was burned with black smoke as the case of usual burning.
These results show that the decomposition with titanium oxide is not burning, but is catalytic decomposition. The same results were obtained with respect to polystyrene.

From the above results, similar to the results in Example 1, according to the decomposition method of waste plastics of the present invention, when the heating temperature of the catalyst composed of titanium oxide granules and the waste plastic was set at about 480 C, polyethylene and polystyrene were decomposed at a high efficiency.

[Example 6]

[0097]
Decomposition of polyvinylchloride, polyurethane, and Teflon Polyvinylchloride contains chlorine atoms in its molecule, polyurethane contains nitrogen atoms in its molecule, and Teflon contains fluorine atoms in its molecule. By using the decomposition method according to the present invention, research has been done as to whether or not the plastics generating those harmful gases in decomposition processes could be decomposed, and further whether or not those gases could be removed by adsorption.

Namely, after the titanium oxide treatment process, the lime neutralization treatment process, and further the oxidation catalyst treatment process with platinum were conducted. By recovering the gases after each process, ingredients contained in the gases were determined. The same determination was conducted with respect to polyethylene and polystyrene.

The measuring conditions were as follows:

1. Decomposition apparatus: 100kg titanium oxide agitation type decomposition apparatus 2. Used catalyst: 100 kg of titanium oxide catalyst (SSP-G
Lot.060829 available from SAKAI CHEMICAL INDUSTRY Co., Ltd.) 3. Kind and amount of used plastic: polyvinylchloride (70 g/min), polyurethane (120 g/min), Teflon (30 g/min), polyethylene (100 g/min), polystyrene (100 g/min) 4. Heating temperature: 480 C (polyethylene, polystyrene, polyvinylchloride), or 490 C (polyurethane, Teflon ) 5. Lime neutralization treatment process 6. Palladium platinum oxidation catalyst treatment process The concentration of the gases was measured by the particular research organization.

[0098]

The results of determined gases generated by the decomposition of each waste plastic are shown in Fig. 9.
With respect to the decomposition of polyvinylchloride, after the lime neutralization treatment process, HC1 and chlorine were removed to an extent having no environmental problem. With respect to the decomposition of polyurethane, NO, NO2 and.HCN were removed sufficiently. With respect to the decomposition of Teflon , after the lime neutralization treatment process, hydrogen fluoride was removed to an extent having no environmental problem.

With respect to every waste plastic, VOC (volatile organic compound) and lower hydrocarbons were removed sufficiently.

The above results show that, though it is difficult to decompose Teflon and the like which generate a harmful gas, particularly hydrogen fluoride by the prior incinerator, according to the decomposition method of the present invention, Teflon and the like can be decomposed at a high efficiency and further the harmful gases can be treated safely without exhausting out of the apparatus.

[Example 7]

[0099]

Study of decomposition of medical wastes In the aforementioned examples, it was confirmed that waste plastic could be decomposed sufficiently. In this example, it was checked whether or not medical wastes (centrifugal tube, blue chip, swine blood, infusion set, neo-tube, syringe, cell scraber, Sure-Fuser, sure flow, dialyser, latex rubber, chip, kimtowel) could be decomposed.

The measuring conditions were as follows:

1. Decomposition apparatus: circulation type testing machine (volume: 385 L) 2. Used catalyst: 200 kg of titanium oxide catalyst (approach pass 100 kg, return pass 100 kg, SSP-G Lot.060116 available from SAKAI CHEMICAL INDUSTRY Co., Ltd.) 3. Heating temperature: 480 C

4. Rotation speed of agitation: approach pass (decomposition part) 10 rpm, return pass 35 rpm 5. Temperature of oxidation catalyst: 400 C
6. Air flow rate: 2.75 m3/min [0100]
(1) Treated medical wastes (total 3.45 kg) : 2 kg of 36 plastic petri dishes (large), 0.25 kg of 10 petri dishes ( small ), 0. 4 kg of 30 centrifugal tubes (50 ml ), 0. 2 kg of blue chip, 0.6 kg of a corrugated box for medical wastes were crushed.

In each case of feed at 84 g/min or feed at 120 g/min, the wastes could be decomposed within 30 minutes.

(2) Treated medical wastes (total 7.007 kg) : After 4 kg of 72 plastic petri dishes (large) , 0.5 kg of 20 petri dishes (small), 0.8 kg of 60 centrifugal tubes (50 ml), 0.4 kg of blue chip, 0.6 kg of a corrugated box for medical wastes were crushed, 707 g of swine blood (including washing water, water-absorbable polymer) was admixed.

In case of feed at 120 g/min, the wastes could be decomposed stably.

(3) Treated medical wastes ( total 7.185 kg) : 2. 6 kg of two sets of 50 infusion sets, 1. 63 kg of two sets of 100 neo-tubes (vacuum collecting tube), 1.97 kg of two sets of syringe (20 ml), 385 g of one bag of cell scraber, 0.6 kg of a corrugated box for medical wastes were crushed.

In case of feed at 156 g/min for 40 minutes, 7280 g of the wastes could be decomposed.

(4) Treated medical wastes (total 6. 703 kg) : 773 g of swine blood (including washing water, water-absorbable polymer) was admixed to 5.93 kg of the same wastes as that of the aforementioned (3).

In case of feed at 120 g/min, the wastes could be decomposed stably.

(5) Treated medical wastes (total 3.055 kg) : 765 g of one set of 5 Sure-Fusers, 340 g of 20 syringes, 620 g of 2 sure flows, 670 g of 6 dialysers (excluding aluminum laminate), 660 g of a corrugated box were crushed.

The wastes could be decomposed at feed at 63 g/min or 84 g/min.

(6) Treated medical wastes (total 3.82 kg) : 720 g of swine blood (including washing water, water-absorbable polymer) was admixed to 3.1 kg of the same wastes as that of the aforementioned (5).

All of the wastes could be decomposed at feed at 85 g/min for 45 minutes.

(7) Treated industrial wastes (total 4.755 kg) : 2.2 kg of three sets of latex rubber glove, 400 g of chips, 945 g of two sets of kimtowel, 560 g of syringes, 650 g of a corrugated box were crushed.

All of the wastes could be decomposed at feed at 480 g/min for 10 minutes.

(8) Treated medical wastes (total 5.37 kg) : 670 g of swine blood (including washing water, water-absorbable polymer) was admixed to 4.7 kg of the same wastes as that of the aforementioned (7).

1540 g of the wastes could be decomposed at feed at 77 g/min for 20 minutes. Further, 3840 g of the wastes could be decomposed at feed at 96 g/min for 40 minutes.

[0101]

From the above results of (1) to (8), the medical wastes could be decomposed. Particularly, according to the decomposition method of the present invention, it has been confirmed that the nitrogen compounds such as NOx could be treated safely in the decomposition of wastes such as blood derived from living body, and the sulfur compounds such as hydrogen sulfide and hydrogen sulfurous acid gas could be treated safely by the lime neutralization treatment process.

[Example 8]

[0102]

Check of fungus adhered to titanium oxide granules After decomposition treatment of a petri dish in which a fungus was incubated, whether or not the fungus was adhered to titanium oxide granules after the decomposition treatment was checked. In detail, in an agitation type experimental machine and a determination machine, titanium oxide granules were recovered after treating E.coli and other organics, and bacteria contained therein were checked.
Experimental method is in the followings.

(1) In the agitation type experimental machine, about 260 g of used titanium oxide was washed by adding 200 ml of distilled water. A part of the washed water was added to SCD medium and various media, and incubated at 35 C for 24 hours and 48 hours. After incubation, thus formed colonies were observed and counted.

(2) In the determination machine, when exchanging titanium oxide, about 50 g of titanium oxide was collected, 35 ml of a phosphate buffer was added, and then buffer was recovered as washed water after sufficient agitation. A
part of the washed water was added to SCD medium and various Petan check media, and incubated at 35 C for 24 hours and 48 hours. After incubation, thus formed colonies were observed and counted.

[0103]

The results of the aforementioned (1) and (2) are shown in Fig. 10. In each case, none of E. coli and the like was detected in the washed waters obtained from the titanium oxide granules after the decomposition treatment of waste plastics.

From the above, according to the decomposition treatment process of the present invention, E.coli was deadened.

[0104]

The examples in the following describe the process to treat the medical waste such as used syringes, packages, or bottles, which are discarded by hospitals and the like using the means for treating waste plastics and organics of decomposition apparatus in the present invention. The elements described before apply the same name or same reference symbol.

[Example 9]

[0105]

The air-supply blower 19 or the like as the i carrier-gas supply means supplies air to the reactor 3.
Then, the heating means 9 is actuated to heat the air supplied by the carrier-gas supply means. The heated air (hot air) is supplied into the reactor 3 containing the catalyst 2, thereby increasing the temperature of the catalyst 2 to a range from 420 C to 560 C.

[0106]

The crushing apparatus shown in Fig.22 crushes medical waste to a size of several cubic millimeters and of larger than the size of the catalyst. The crushed medical waste is charged from the charge opening 7 of the reactor 3 into the concave portion 13, (refer to Figs.
16(4)). The charged medical waste circulates together with the catalyst 2 in the reactor by the action of the circulation means 5 (D) and the circulation means S. In the circulation step, the catalyst 2 and the medical waste are continuously agitated by the screw feeder as the agitation means 6, thus the contact between the catalyst 2 and the medical waste is repeated, which enhances the decomposition of waste plastics and organics 4 in the medical waste by the action of the catalyst 2. Through the process, all the waste plastics and organics 4 in the medical waste charged into the reactor 3 are gasified in the catalyst circulation step. During the gasification process of the waste plastics and organics 4, the decomposition of them generates gas consisting mainly of carbon dioxide and water i vapor.

[0107]

The gas (gasified organics) is sent to the lime neutralization treatment means and then to the oxidation catalyst treatment means. The step of removing toxic ingredients in the exhaust gas is not described in the example.

[0108]

In the above circulation step, the waste plastics and organics 4 occupying the medical waste are gasified. The metals existing in the medical waste, however, are left behind in the catalyst 2 even after the circulation. Those metals may further be brought to be separated together with the catalyst 2 in the circulation step. For example, the wire mesh 16 having an opening to allow greatest dimension of the catalyst 2 to pass through is inserted in the reactor as the means for separating and recovering metals and/or inorganics, (refer to Fig. 16(4)). Then, the pocket 17 which can recover the metals and inorganics caught by the wire mesh is located, thus recovering the metals and inorganics from the pocket.

[0109]

Therefore, according to the means for treating waste plastics and organics of the present invention, the metals and inorganics in the medical waste are not left in the reactor 3, and are brought into recycle use while suppressing the oxidation of the metals. Furthermore, on separating the metals by the means for separating and recovering metals and/or inorganics, there is no need to stop the circulation means 5 and/or the agitation means 6 so that the throughput of the medical waste maintains a high level. In addition, when the means for separating and recovering metals and/or inorganics 15 separates metals, there is no need to open the door of the reactor 3 so that the thermal efficiency of the means for treating waste plastics and organics maintains a high level.

[Example 10]

[0110]

The charge opening 7 of the reactor 3, shown in Fig.
17, is opened, and the catalyst 2 is let flow down to near the upstream end 33 in the first stage tank 31. At the same time, the circulation means 5 is actuated. Thus, the circulation means 5(A) transfers the catalyst 2 firstly toward the discharge end 34 of the first stage tank 31, and to the lowermost end of the rotary shaft 14 of the circulation means 5(B). Succeedingly, the circulation means 5(B) pushes up the catalyst 2 to the charge end 37 of the second stage tank 32, and finally the circulation means 5(C) transfers the catalyst 2 to the downstream end 36 in the second stage tank 32. At this moment, the catalyst 2 exists and circulates in the circulation passage from the upstream end 33 in the first stage tank 31 to the downstream end 36 in the second stage tank 32.

[0111]

When the circulation means 5 is kept operating while flowing down the catalyst 2 as described above, the catalyst 2 slides down through the returning passage 20 by its own weight, then returns to the upstream end 33 in the first stage tank 31. The flowing down of the catalyst 2 is stopped when the volume or mass of the catalyst 2 accumulated in the circulation passage reaches a desired value. After closing the charge opening 7, the heating means 9 heats the catalyst 2 in the reactor 3 to a range from 420 C to 560 C.
Since the catalyst is not deteriorated even retaining in the reactor, the succeeding decomposition operation can begin from the step of heating the catalyst 2 in the reactor 3.

[0112]

Next, the crushing apparatus shown in Fig. 22 crushes medical waste to a size of several cubic millimeters and of larger than the size of the catalyst. The crushed medical waste is charged from the charge opening 7 into near the upstream end 33 in the first stage tank 31. The circulation means 5 circulates the medical waste together with the catalyst 2 through the circulation passage. In the circulation step, the catalyst 2 and the medical waste are continuously agitated by the screw feeder as the agitation means 6, thus the contact between the catalyst 2 and the medical waste is repeated, which enhances the decomposition of organics in the medical waste by the action of the catalyst 2. Through the process, all the organics 4 in the medical waste charged into the reactor 3 is gasified during the circulation between the upstream end 33 in the first stage tank 31 and the downstream end 36 in the second stage tank 32. During the gasification process of the organics, the decomposition of them generates gas consisting mainly of carbon dioxide and water vapor.

[0113]

When the catalyst 2 reaches the downstream end 36 in the second stage tank 32, the catalyst 2 slides down through the returning passage 20 to return to the upstream end 33 in the reactor 3, thereby the catalyst 2 circulates in the reactor 3. Accordingly, when medical waste which is crushed by the crushing means is newly charged into the reactor 3, the same catalyst 2 is able to repeatedly gasify the organics in the newly charged medical waste. Since the position of the second stage tank 32 is higher than the first stage tank 31, returning the catalyst 2 from the downstream end 36 in the second stage tank 32 to the upstream end 33 in the first stage tank 31 is performed without forceful use of conveyer, screw feeder, and the like.

[0114]

The above gas (gasified organics) is sent to the lime neutralization treatment means, and then to the oxidation catalyst treatment means. The step of removing toxic ingredient in the exhaust gas is not described in the example.

[0115]

In the above circulation step, the organics occupying a large portion of the medical waste are gasified. The metals existing in the medical waste, however, are left behind in the catalyst 2 even at the downstream end 36 in the second stage tank 32. Those metals may further be brought to be separated together with the metals in the step of circulating the catalyst 2. For example, the wire mesh 16 having an opening to allow greatest dimension of the catalyst 2 to pass through is inserted in the returning passage 20 as the means for separating and recovering metals and/or inorganics 15. In this case, the returning passage 20 may be located outside the reactor 3 so as the metals caught by the wire mesh not to expose to the high temperature gas. Thus, when the metals caught by the wire mesh are taken out by opening the returning passage 20, the metals can be removed from the catalyst 2 before the metals enter the medical waste being newly charged into the reactor 3.

[0116]

The present invention is able to be carried out in modes after applying varieties of improvements and modifications based on,the knowledge of persons skilled in the art within a range not to depart from the scope of the i present invention. For example, there is a case of not needing the circulation means 5(B). For instance, the first permeable bottom 35 is located in a tilting position so as the discharge end 34 to become higher than the upstream end 33, thereby letting the catalyst 2, which is transferred by the transferring means 5 to the discharge end 34 of the first permeable bottom 35, down directly to the charge end 37 of the second permeable bottom 38.

[Example 11]

[0117]

The charge opening 8 shown in Fig. 19 is opened, and the catalyst 2 is let flow down to near the upstream end 33. At the same time, the circulation means 5 is actuated.
Thus, the circulation means 5 transfers the catalyst 2 firstly from the upstream end 33 toward the downstream end 36. At this moment, the catalyst 2 exists and circulates in the circulation passage from the upstream end 33 to the downstream end 36.

[0118]

The flowing down of the catalyst 2 is stopped when the volume or mass of the catalyst 2 accumulated in the circulation passage reaches a desired value. After closing the charge opening, the heating means 9 heats the air supplied by the air-supply blower 19, and supplies the hot air to the reactor 3, thereby heating the catalyst 2 in the reactor 3 to a temperature range from 420 C to 560 C.

i Since the catalyst is not deteriorated even retaining in the reactor, the succeeding decomposition operation can begin from the step of heating the catalyst 2 in the reactor 3.

[0119]

Next, the crushing apparatus shown in Fig. 22 crushes medical waste to a size of several cubic millimeters and of larger than the size of the catalyst. The crushed medical waste is charged from the charge opening 8 into near the upstream end 33. The circulation means 5 circulates the medical waste together with the catalyst 2 through the above circulation passage. In the circulation step, the catalyst 2 and the medical waste are continuously agitated by the screw feeder as the agitation means 6, thus the contact between the catalyst 2 and the medical waste is repeated, which enhances the decomposition of organics in the medical waste by the action of the catalyst 2. Through the process, all the organics 4 in the medical waste charged into the reactor 3 are gasified during the circulation between the upstream end 33 and the downstream end 36.
During the gasification process of the organics, the decomposition of them generates gas consisting mainly of carbon dioxide and water vapor.

[0120]

When the catalyst 2 reaches the downstream end 36, the catalyst 2 slides down through the returning passage 20 to return to the upstream end 33 in the reactor 3, thereby the catalyst 2 keeps circulating in the reactor 3.
Accordingly, when medical waste which is crushed by the crushing means is newly charged into the reactor 3, the same catalyst 2 is able to repeatedly gasify the organics in the newly charged medical waste.

[0121]

The above gas (gasified organics) is sent to the lime neutralization treatment means, and then to the oxidation catalyst treatment means. The step of removing toxic gas in the exhaust gas is not described in the example.

[0122]

Preferably the returning passage 20 has the means for separating and recovering metals and/or inorganics 15, and connects the downstream end 36 in the reactor 3 with the upstream end 33 therein. As described below in detail, the separation means 15 separates the remained metals and inorganics from the catalyst 2 transferred to the downstream end 36. The returning passage 20 returns the catalyst 2, from which the- metals are removed by the separating and recovering means 15, to the upstream end 33.

[0123]

The separation means 15 is the wire mesh 16 having an opening to allow greatest dimension of the catalyst 2 to pass through, and is inserted in the course of the returning passage 20. When the amount of metals caught by the wire mesh reaches a certain volume, the returning passage 20 is opened to take out the metals and/or inorganics, which passage 20 does not allow the metals in the waste plastics and organics 4 to remain in the reactor 3, while suppressing the oxidation of metals, thus realizing the recycle use of the metals.

[0124]

With thus described apparatus for treating waste plastics and organics, the metals (aluminum, A1) of 98.9%
of average purity were recovered. A sheet 'of plastic film with vapor-deposited Al thereon was crushed to about 5 cm square pieces, which pieces were then mixed and agitated with the catalyst (titanium oxide) 2 in 1 to 3 mm of size, heated to about 480 C, to circulate in an apparatus for treating waste plastics and organics for 10 minutes. At every one circulation of the catalyst 2 in the means for treating waste plastics and organics 1, thin Al pieces having several square centimeters in size were recovered.
The recovered plastics pieces were decomposed to gasify, and high purity aluminum metal was recovered. Shorter circulation time expects higher purity of recovered metal.

[0125]

Embodiments and examples for the apparatus for treating waste plastics and organics according to the present invention are described above. The present invention is, however, not limited to above embodiments.

According to the above examples, the metal pieces are left on the wire mesh. However, the catalyst 2 may be left on the wire mesh. Since the size of recovering metal pieces may differ with the conditions of kind of recovering metal, heating temperature of the catalyst 2, oxygen concentration, and the like, the recovery condition, the size of the catalyst 2, the opening of the wire mesh, and the like are preliminarily adjusted so as the large metal pieces to be left on the wire mesh to recover the target metals.

[0126]

Fig. 19 shows the means for treating waste plastics and organics 1 in horizontal position. The reactor 3 may be tilted so as the downstream end 36 to become higher than the upstream end 33. When the downstream end 36 is positioned higher than the position of upstream end 33, the catalyst 2 which was transferred by the circulation means to the downstream end 36 can be slid-down through the returning passage 20 by its own weight, thus can be returned to the upstream end 33. In that case, the returning passage 20 may be a chute to connect the downstream end 36 in the reactor 3 with the upstream end 33 therein.

[Example 12]

[0127]

As illustrated in Fig. 20, petri dishes as the medical waste were put in the cage 40. The cage 40 containing the Petri dishes is put in the reactor 3 through the charge opening 41.

Then, the catalyst 2 was let flow down into the reactor 3 through the vent opening 39. Thus the catalyst 2 flows down from the upstream end 33 in the reactor 3 to the downstream end 36 therein. Next, the screw feeder is actuated. Thus the catalyst 2 accumulated near the downstream end 36 returns to the upstream end 33 in the reactor 3 via the returning passage 20. The flowing-down of the catalyst 2 is stopped when the volume or mass of the catalyst 2 accumulated in the circulation passage reaches a desired value.

The heating means 9 heats the system so as the temperature of the catalyst 2 in the reactor 3 to become in a range from 420 C to 560 C. Since the catalyst is not deteriorated even retaining in the reactor, the succeeding decomposition operation can begin from the step of heating the catalyst 2 in the reactor 3.

[0128]

During the course of flowing down (circulation) of the catalyst 2 at the catalyst-activation temperature from the upstream end 33 in the reactor 3 to the downstream end 36 therein, the Petri dishes contact with the catalyst 2, and are gasified. Gasification of Petri dish generates gas consisting mainly of carbon dioxide and water vapor.

[0129]

Since the catalyst 2 which reaches the downstream end 36 in the reactor 3 returns to the upstream end 33 in the reactor 3 via the returning passage 20, the catalyst 2 circulates in the reactor 3. Consequently, the catalyst 2 at high activation state can be successively charged onto the Petri dishes.

[0130]

The above gas (gasified organics) is sent to the lime neutralization treatment means, and then to the oxidation catalyst treatment means. The step of removing toxic gas in the.exhaust gas is not described in the example.

[Example 13]

[0131]

Decomposition system for waste plastics and organics according to the present invention Using the decomposition apparatus described in Example 9, the titanium oxide granules in the reactor 3 are further heated to a temperature range from 420 C to 560 C.
The characteristics of the titanium oxide as the active ingredient in the applied titanium oxide granules are (1) specific surface area in a range from 35 to 50 m2/g, and (2) size of granules of 3.5 mesh (5.60 mm) or smaller.

The applied waste plastics and organics are the, plastics which generate chlorine, hydrogen chloride, sulfur compounds, nitrogen compounds, and the like in the decomposition step.

[0132]

Compared with the conventional decomposition method, the above-described decomposition system shows significantly high decomposition efficiency. Furthermore, with the lime neutralization treatment step using the lime neutralization means and with the oxidation catalyst treatment step using the oxidation catalyst treatment means, the above decomposition method conducts easily the treatment of plastics and organics generating HC1, hydrogen fluoride, sulfur compounds, nitrogen compounds, and the like in the decomposition step, of biological substances such as blood, and of fluorine compounds generating hydrogen fluoride. In addition, the above decomposition method easily conducts separation and recovery of metals and inorganics which are mixed in the waste plastics and organics or which are vapor-deposited or adhered to at least one side of the surface thereof.

[0133]

All the examples of the present invention described above can be carried out in modes after applying varieties of improvements, modifications, and changes on the basis of the knowledge of the persons skilled in the art within a range not to depart from the scope of the present invention.
[Industrial Applicability]

[0134]

The decomposition method, decomposition apparatus, and decomposition system according to the present invention are the useful technology for treating all kinds of waste including plastics, not limited to medical waste.

BRIEF DESCRIPTION OF THE DRAWINGS

[0135]

Fig. 1 illustrates an apparatus for determining an abrasion rate of titanium oxide.

Fig. 2 shows comparison of abilities as to immobilization of chlorine.

Fig. 3 shows influences of water content in lime materials.

Fig. 4 shows study of heating temperature in lime neutralization treatment process.

Fig. 5 illustrates a schematic view of an alumina catalyst tank.

Fig. 6 illustrates a flow of the decomposition method of waste plastics according to the present invention.
Fig. 7 shows the results of decomposition of waste plastics at various temperatures.

Fig. 8 shows detection of dioxin generated in the processes of decomposition method according to the present invention.

Fig. 9 shows the results of measurement of gases generated by decomposition of various waste plastics.
Fig. 10 shows the results of check of adhered fungus to the titanium oxide granules after decomposition treatment.

Fig. 11 shows a part of compression mold upper-presser (measure: mm).

Fig. 12 shows a part of compression mold lower-presser (measure: mm).

Fig.13 shows intensity distribution of catalyst (without edge-treating).

Fig.14 shows intensity distribution of catalyst (with edge-treating).

Fig.15 shows a schematic drawing illustrating the main parts of the means for treating organics according to example 9 of the present invention.

Fig. 16 shows schematic drawings illustrating various modes of the means for treating organics according to example 9 of the present invention.

Fig.17 shows a schematic drawing illustrating the main parts of the means for treating organics according to example 10 of the present invention.

Fig.18 shows a cross sectional view of the means for treating organics according to example 10 of the present invention.

Fig.19 shows a schematic drawing illustrating the main parts of the means for treating organics according to example 11 of the present invention.

Fig.20 shows a schematic drawing illustrating the main parts of the means for treating organics according to example 12 of the present invention.

Figs.21(a) and 21(b) show perspective views of modification examples of the transfer means and the agitation means, respectively, applied to the means for treating organics according to the embodiments of the present invention.

Fig. 22 shows a block flow diagram of the decomposition apparatus for waste plastic and organics according to the examples of the present invention.

Fig.23 shows a block diagram of conventional apparatus for decomposing organics.

[Explanation of Reference Numerals]

[0136]

1: means for treating waste plastics and organics 2: catalyst 3: reactor 4: waste plastics and organics 5: circulation means 6: agitation means 7: charge opening 8: charge opening 9: heating means 10: air-blowing chamber 11: partition wall 12: paddle 13: concave portion 14: rotary shaft 15: means for separating and recovering metals and/or inorganics 16: wire mesh having an opening to allow greatest dimension of the catalyst 2 to pass through 17: pocket for collecting metals and/or inorganics 18: discharge opening for metals and inorganics 19: air-supply blower 20: returning passage 21: spiral blade 22: blade row 23: crushing means 24: charge opening of solid waste plastics and organics 25: degradation site of waste plastics and organics 30: partition wall 31: first stage tank 32: second stage tank 33: upstream end 34: discharge end 35: permeable bottom 36: downstream end 37: charge end 38: permeable bottom 39: vent opening 40: cage 41: charge opening 42: mesh 81: three-piece blades 82: notch 83: axial flow blade 84: projected piece 85: projected piece 101: crusher 102: reactor 103: agitation blade 104: blower 105: removal apparatus 106: separator 107: correction tank 201: sample vessel 202: agitator 203: shaft body 204: agitation blade

Claims

1. A decomposition method of waste plastics and organics by gasifying the waste plastics and/or organics, the method comprising a process of heating and agitating the waste plastics and/or organics together with a catalyst composed of titanium oxide granules in which the active ingredient is titanium oxide, wherein the heating temperature of the catalyst is within the range of 420°C
to 560°C.

2. The decomposition method according to Claim 1, wherein the titanium oxide of titanium oxide granules have the following characteristics:

(1) the specific surface area from 35 to 50 m2/g; and (2) the granule size of 3.5 mesh (5.60 mm) or smaller.

3. The decomposition method according to Claim 1 or 2, wherein a treatment amount of the waste plastics and/or organics per hour with respect to 100 kg of the titanium oxide granules is 3.0 to 40.0 kg.

4. The decomposition method according to any one of Claims 1 to 3, further comprising a lime neutralization treatment process.

5. The decomposition method according to any one of Claims 1 to 4, further comprising an oxidation catalyst treatment process.

6. The decomposition method according to Claim 5, further comprising an alumina catalyst treatment process before the oxidation catalyst treatment process.

7. The decomposition method according to any one of Claims 1 to 6, further comprising the process of separation of metals and/or inorganics.

8. An apparatus of catalyst-circulation type for decomposing waste plastics and organics, comprising (1) a means for treating waste plastics and organics, and (2) a means for treating oxidation catalyst.

9. The apparatus for decomposing waste plastics and organics according to claim 8, wherein the means for treating waste plastics and organics includes:

a reactor which circulates a catalyst in the reactor;
and a means for circulating and/or agitating waste plastics and/or organics, charged from a charge opening of the reactor, together with the catalyst, (a circulation and/or agitation means), the waste plastics and/or organics being gasified in the step of circulating the waste plastics and/or organics together with the catalyst in the reactor.

10. The apparatus for decomposing waste plastics and organics according to claim 9, wherein the circulation and/or agitation means is one or more screw feeders which have spiral blades mounted to the respective rotary shafts rotated by the respective drive sources, the rotary shafts being inserted into the reactor.

11. The apparatus for decomposing waste plastics and organics according to claim 10, wherein the two screw feeders are located in substantially horizontal position in the reactor, and the rotation of the two screw feeders circulates the waste plastics and/or organics together with the catalyst in the reactor substantially in horizontal direction.

12. The apparatus for decomposing waste plastics and organics according to claim 9, wherein the means for treating waste plastics and organics includes:

a reactor which circulates a catalyst from upstream end to downstream end in the reactor;

a circulation means which circulates waste plastics and/or organics charged from a charge opening of the reactor together with the catalyst from the upstream end to the downstream end;

an agitation means which agitates the catalyst and the waste plastics and/or organics in the reactor; and a returning passage which guides the catalyst from the downstream end to the upstream end of the reactor in the reactor, the waste plastics and/or organics being gasified in the step of circulating the waste plastics and/or organics together with the catalyst from the upstream end to the downstream end of the reactor.

13. The apparatus for decomposing waste plastics and organics according to claim 12, wherein the reactor is divided into a first stage tank having the upstream end, and a second stage tank having the downstream end and being located at higher position than the position of first stage tank, thereby the catalyst being guided from the downstream end in the second stage tank into the returning passage to flow down to the upstream end in the first stage tank.

14. The apparatus for decomposing waste plastics and organics according to claim 12, wherein the upstream end and the downstream end in the reactor are located substantially in horizontal position, thereby the catalyst after sliding down from the downstream end by the self weight being guided into the returning passage, and then flowing up to the upstream end.

15. The apparatus for decomposing waste plastics and organics according to any of claims 12 to 14, wherein the circulation means is a screw feeder which has a spiral blade mounted to a rotary shaft rotated by a drive source, the rotary shaft being inserted into the reactor.

16. The apparatus for decomposing waste plastics and organics according to claim 15, wherein the spiral blade has an auxiliary blade.

17. The apparatus for decomposing waste plastics and organics according to claim 9, wherein the means for treating waste plastics and organics includes:

a reactor which circulates a catalyst from upstream end to downstream end in the reactor;

a cage which can position the waste plastics and/or organics in the reactor; and a returning passage which guides the catalyst from the downstream end to the upstream end of the reactor in the reactor, the waste plastics and/or organics in the cage being contacting with the catalyst and further being gasified in the step of dropping (circulating) the catalyst from the upstream end to the downstream end of the reactor.

18. The apparatus for decomposing waste plastics and organics according to any of claims 9 to 17, wherein the reactor can supply a carrier gas from a plurality of holes opened on the bottom of the reactor directly into the catalyst in a uniformly distributed manner.

19. The apparatus for decomposing waste plastics and organics according to any of claims 9 to 18, wherein the step of circulation in the reactor has a means for separating and recovering metals and/or inorganics.

20. The apparatus for decomposing waste plastics and organics according to claim 19, wherein the means for separating and recovering metals and/or inorganics is a means for separating the catalyst from a mixture of the waste plastics and/or organics and the catalyst in the step of circulation in the reactor.

21. The apparatus for decomposing waste plastics and organics according to claim 20, wherein the means for separating the catalyst from a mixture of the waste plastics and/or organics and the catalyst is a means for separating the metals and/or inorganics from the catalyst based on the size difference therebetween.

22. The apparatus for decomposing waste plastics and organics according to claim 21, wherein the means for separating the metals and/or inorganics from the catalyst based on the size difference therebetween installs a sieve which allows the catalyst to pass therethrough in the step of circulation in the reactor.

23. The apparatus for decomposing waste plastics and organics according to any of claims 8 to 22, further comprising one or more of the following means:

(1) alumina catalyst treatment means (2) crushing means (3) carrier gas supply means (4) cyclone dust collection means (5) dust collection means with bag filter (6) heat exchange means (7) preheater means (8) exhaust blower means (9) cooling means (10) heat recovery means (11) HCl continuous measurement means (12) CO continuous measurement means (13) alarm means (14) lime neutralization treatment means.

24. A decomposition system for decomposing waste plastics and organics using an apparatus for decomposing waste plastics and organics according to any one of claims 8 to 23, thereby decomposing the waste plastics and organics while controlling the heating temperature of the catalyst, composed of titanium oxide granules in which the active ingredient is titanium oxide, within the range of 420°C to 560°C.

25. The decomposition system according to claim 24, wherein the titanium oxide as the active ingredient have characteristics of:

(1) the specific surface area from 35 to 50 m2/g; and (2) the granule size of 3.5 mesh (5.60 mm) or smaller.

26. The decomposition system according to claim 25, wherein the titanium oxide granules are a mixture of titanium oxide as the active ingredient and any one of below (1) and (2) :

(1) aluminum oxide, and (2) silicon oxide.