AU703494B2 - Dechlorination process of organnochlorine compound - Google Patents

Description

Heisei 7-8572, Heisei 7-313620).

The inventions of the inventions disclosed in the foregoing publications are quite effective and superior methods.

However, it has been known excessive amount of alkali has to be used in order to obtain better results (Japanese Unexamined Patent Publication No. Heisei 7-313620).

Accordingly, it is important task to collect excessive alkali together with collection of polar-solvent in order to further enhance practicality and economical efficiency.

On the other hand, in the conventional method, it is encountered a problem of long reaction period to lower PCB concentration by this reaction to be lower than or equal to an analytic detection limit by means of high sensitivity gas chromatograph mass-spectrometer (GC-MS). It is also the task to shortening the reaction period.

[DISCLOSURE OF THE INVENTION] In order to solve such problems, the inventors have now worked out a more economical novel process as a result through strict experiments. According to the present invention, it has been found a dechlorination process for an organochlorine compound comprising the steps of: a) stirring and mixing the organochlorine compound in a relatively high concentration and excessive alkali in an aprotic solvent at 100 0 C to 300 0 C in a reaction bath; b) separating and collecting excessive and non-reacted alkali from the resulting reaction liquid and recycling alkali for dechlorination reaction; c) separating solid component generated after cooling of the reaction liquid and dissolving, separating and collecting alkali contained in said solid component with a lower alcohol and recycling for dechlorination reaction; d) separating and collecting aprotic polar solvent as it is, or in part or in most part from the reaction liquid and recycling for dechlorination reaction and converting the reaction liquid into an alkali-hydrochloride acid salt and a dechlorinate of a material organochlorine compound, to make them a defused OT general waste.

2 P:\WPDOCS\CRN\SPECI\661082.SPE 29/1/99 According to a further aspect of the present invention it has been found a adechlorination process for an organochlorine compound comprising: a) stirring and mixing an organochlorine compound in a relatively low concentration and excessive alkali in an aprotic polar solvent to 100 0 C to 3000 C in a reaction bath; b) separating and collecting excessive and non-reacted alkali from the reaction product/liquid formed and recycling alkali for dechlorination reaction; c) separating the solid component generated in a relatively small amount after cooling of the reaction liquid and dissolving, separating and collecting alkali contained in said solid component with a lower alcohol and recycling for dechlorination reaction; Sd) separating and collecting aprotic polar solvent as it is, or in part or in most part and recycling for dechlorination reaction and e) and converting said reaction product into an alkali-hydrochloride acid salt and S: a dechlorinate of a material organochlorine compound, to make them a defused general waste.

In the present invention, organnochlorine compound represents organnochlorine compound difficult to be dissolved, such as PCB, 20 polychlorodibenzodioxine, or 1, 2, 3-trichloro-4'-nitro-bythenylether (CNP). Alkali represents at least one compound selected among a group consisted of caustic soda, caustic alkali of potassium, sodium lower alcoxide, calcium hydroxide, calcium oxide or the mixture of two or more thereof. Also, what is particularly desirable in view of economical efficiency, is caustic soda.

3 P:\WPDOCS\CRN\SPECI\661082.SPE .29/1/99 The inventors have found that means for collecting alkali by lower alcohol is quite effective for dechlorination reaction. Namely, alkali is dissolved by alcohol, and alkali collected by lower alcohol is more effective for promoting reaction than the newly added alkali. Mechanism of reaction or the like and its scientific explanation are now on search and will be worked our in due course.

Therefore, according to the present invention, the excessive alkali is collected from the solid component separated from the reaction liquid by filtration by lower alcohol or the like and is employed in next dechlorination reaction by batch 10 reaction liquid by filtration by lower alcohol or the like and is employed in next dechlorination reaction by batch reaction. The solvent of filtrate is collected by I* •distillation as is, or in part or in most part and used for next batch reaction.

In the present invention, when the concentration of organochlorine compound for reaction is relatively high, the aprotic polar solvent in the residue separated the solid component therefrom is distillated and collected as it is, or in a part or in most part, and is recycled for dechlorination reaction.

In the present invention, the collected alkali dissolved and collected by lower alcohol and recycled for dechlorination reaction is supplied to the reaction bath together with alkali amount for compensating the consumed amount in dechlorination.

P:\WPDOCS\CRN\SPECI\661082.SPE 29/1/99 In the present invention, in filtration of reaction liquid, centrifugal separation, pressure filtration, suction vacuum filtration or the like is appropriate, which will be selected in consideration of the condition of concentration of material organnochlorine compound, viscosity of system or the like. Distillation and collection of solvent in filtration, suction vacuum filtration or the like is appropriate, which will be selected in consideration of the condition of concentration of material organnnochlorine compound, viscosity of system or the like. Distillation and collection of solvent in the filtration is not specified the form of implementation as long as the method is efficient, such as vacuum distillation, vacuum diaphragm S 10 distillation or the like. If it is convenient that the distillation residual becomes dry 9..

solid form, thorough distillation is performed, the solid component is crushed and filtered, and alkali may be collected by extracting and washing the solid component by lower alcohol. In case of high viscous fluid, lower alcohol is diluted together with go"' several batches, and salts are filtered and alkali in the filtrate is analyzed for use in material of next batch reaction.

What is convenient in the present invention is alkali is filtered and separated by selecting the aprotic polar solvent appropriately, most economically selecting ~alkali, since the reaction product and inorganic salt are not well dissolved in aprotic solvent, filtration and separation can be done relatively easily. Also, since only alkali S 20 is easily dissolved in lower alcohol, extraction and collection can be advantageously performed.

As set forth above, it is one example of superior point in the shown process in that the alkali substance collected by lower alcohol has higher reaction activity than the initially used alkali.

In the present invention, what is further important is to restrict the moisture content in the lower alcohol to be less than or equal to 10%, particularly preferably to be only deposited moisture. Large amount of moisture should cause corrosion of device and well dissolve the reaction product, it has been found to interfere dehydrohalogenation at termination point of reaction. However, while action of quite fine moisture is not yet clear, in view of distribution of the reaction product, it is considered to perform some effective action.

Therefore, as lower alcohol to be used for separation and collection of alkali, a mixture consisted of at least one or two or more selected among a group consisted of alcohol containing one to four carbons containing less than or equal to of moisture.

On the other hand, when a concentration of organnochlorine compound for reaction is relatively low, a solid substance is generated in relatively small amount after cooling of a reaction liquid by performing said dechlorinating reaction, statically placing cooled said reaction liquid to separate the reaction liquid into two phases of the aprotic.

polar solvent and dechlorination compound, collecting the aprotic polar solvent for recycling in next dechlorinating reaction, and for using in another application after said dechlorinating reaction.

It is preferred that upon separation into two phases of aprotic polar solvent and said reaction liquid, a lower alcohol to be used for correcting alkali, is added to promoting separation of the non-aprotic polar solvent and said reaction liquid.

In the present invention, aprotic polar solvent contains more than or equal to 50% of one or a mixture of more than two kinds selected among a group consisted of sulphone, dimercaptosuccinic acid (hereinafter referred to as DMSO), 1,3dimethyl-2-imidasolidinon, dimethyl polyalkylene glycol (hereinafter referred to as DMI), detramethyl urea, Nmethylpyrrolidone. Containing more than or equal to 50% of DMSO, DMI, dimethyl polyalkylene glycol are particularly preferred in view of chemical safety, cost and so forth. When the content of the solvent is less than 50%, complete removal of chlorine becomes quite difficult.

As a temperature for stirring organnochlorine compound and alkali in aprotic polar solvent, it is appropriate at 100 C to 300 oC. In case of the process temperature lower than or equal to 100 C, quite a long period is required. In case of the process temperature is higher than or equal to 300 oC, it is possible to cause unexpected formation of gel or so forth for transpiration and secondary reaction of aprotic solvent and organnochlorine compound, When no particular additive is used, 'wi it is desirable to perform at 150 °C to 250 °C.

In the present invention, concerning organnochlorine compound to be supplied to the reaction bath, collected alkali to be recycled, newly supplied alkali, newly supplied aprotic polar solvent and collected aprotic polar solvent to be recycled, it is desirable to preliminarily supply two or ore or more with mixing in the reaction bath.

At this time, as a method for preliminarily mixing, a mixing bath with a stirrer and static mixer are used alone or in combination. In this case, as a method of using said mixing bath with the stirrer, after charging a part of the collected aprotic polar solvent and the newly supplied aprotic polar solvent into the mixing bath with the stirrer, finely crushed solid caustic soda or caustic alkali of potassium and the collected alkali are mixed in slurry form, then a pair of mixture of the aprotic polar solvent already supplied in the reaction bath and the organnochlorine compound are mixed with the slurry to supply to the reaction bath.

PCB is preferably reacted with the solvent, such as DMI or the like under presence of excessive alkali. In order to lower the PCB concentration in the order of ppb, it is required to progress reaction even at quite low PCB concentration. On the other hand, when high concentration PCB is processed, PCB concentration becomes lower during progress of reaction.

Accordingly, in order to progress reaction, it is inherent that PCB molecule and alkali molecule are contacted. Therefore, it is necessary to rise mixing degree by shearing and mixing the liquid. Upon mixing, energy consumption due to the pressure loss before and after mixer is relatively smaller than stirrer.

Accordingly, mixing effect can be obtained at smaller energy.

On the other hand, reaction is progressed in liquid phase of alkali dissolved in aprotic polar solvent, such as DMI or the like, and PCB to cause dechlorination reaction.

Therefore, in order to promote reaction, it becomes necessary to maintain high alkali concentration dissolved in DMI to promote contact between alkali molecule and PCB molecule. Therefore, alkali to be used for reaction has to be easily dissolved in DMI.

Suspending finely crushed solid caustic soda or caustic alkali of potassium, it becomes necessary to compensate alkali dissolved in DMI consumed in the dechlorination reaction.

Concerning method, as a result of various study, suspension liquid is prepared by mixing DNI and finely crushed alkali with the mixing bath with the stirrer. In comparison with the method for mixing by directly supplying the suspension liquid to PCB in the reaction bath with the stirrer, the method to withdraw the liquid containing PCB from the reaction bath to pass through the static mixer and thereafter to form a circulation line returning to the reaction bath, and to admixing the suspension to the inlet of the static mixer to pass through the static mixer promotes dissolving of alkali in the DMI to make operation easier. As set forth, dechlorination action is progressed with supplying suspension liquid or with after supplying, the reaction bath is elevated the temperature. Even in this process, dechlorination process is progressed with maintaining the reaction temperature constant. Even in this process, a part of the reaction liquid is constantly recalculated through the static mixer. By this, dechlorination reaction is progressed to achieve the desired result.

The foregoing method may achieve good result even in application for hydrocarbon oil containing any concentration of organnochlorine compound, such as PCB contaminated transfer oil or 100% PCB. In certain case, hydrocarbon oil may be regenerated and recycled.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is an illustration showing a typical flow sheet of a process, to which the present invention is applied; Fig. 2 is an illustration showing a typical flow sheet of another process, to which the present invention is applied; Fig. 3 is an illustration showing one example of material balance with respect to the case where alkali and solvent collection is not effected in the flow experiments relating to the process, to which the present invention is applied; Fig. 4 is an illustration showing one example of material balance with respect to the case where alkali and solvent collection is effected in the flow experiments relating to the process, to which the present invention is applied; Fig. 5 is an illustration showing one example of process for supplying a material to a reaction bath in the process, to which the present invention is applied; Fig. 6 is an illustration showing a typical flow sheet of another process, to which the present invention is applied; Fig. 7 is an illustration showing recycling of defused insulation oil to a fuel oil, in the process, to which the present invention is applied; and, Fig. 8 is an illustration showing a material balance upon recycling into the fuel oil after recycling DMI and collected alkali for fifteen times in the flow test of the process, to which the present invention is applied.

(Explanation of Reference Numerals) Reference Numerals in Fig. 1 1 DMI 2 caustic soda 3 stirrer 4 reaction bath jacket 6 filter (1) 7 filter (2) 8 distiller 9 PCB containing insulation oil filtrate (1) 11 cake (1) 12 cake (2) 13 filtrate (2) 14 collected DMI still residue 1) 11 16 collected ethanol 17 ethanol 18 supplementary ethanol 19 dissolver reaction fluid 36 collected DMI storage bath 37 condenser 38 condenser Reference Numeral in Fig. 2 21-1 separating bath 21-2 separating bath 22 ethanol/NaOH 23 wash/neutralization bath 24 oil phase water phase 26 water 27 acid The reference numerals other than those listed above are common to those shown in Fig. 1.

Reference Numeral of Fig. 28 circulation pump 29 static mixer circulation line 31 piping of reaction supply liquid 32 supply pump 1 2 33 stirrer 34 mixing bath heating heater The reference numerals other than those listed above are common to those shown in Figs. 1 and 2.

Reference Numeral of Fig. 7 39 adjusting bath cooling bath 41 filtrate receptacle bath 42 distillated liquid (DMI) receptacle bath 43 separator 44 high pressure insulative oil (TFO) receptacle bath still residue receptacle bath 46 alkali dissolver 47 alcohol dissolver 48 alkali containing alcohol solution storage bath 49 alkali supply bath cake storage bath 51 material (PCB containing TFO) supply bath 52 solvent (DMI) supply bath 53 new alkali supply bath 54 stirring drive motor TFO washing bath 56 TFO washing receptacle bath 57 TFO heavy oil mixing bath The reference numerals other than those listed above are common to those shown in Figs. 1 and 2.

[BEST MODE FOR IMPLEMENTING THE INVENTION] In order to deepen understanding of the process according to the present invention, the present process will be discussed with reference to the drawings. The typical flow sheet of the shown process is shown in Figs. 1, 2, 5, 6 and 7.

Fig. 3 illustrates one example of material balance in the case where collection of alkali and solvent is not effected, Fig. 4 illustrates one example of material balance in the case where collection of alkali and solvent is effected, and Fig. 8 illustrates one example of material balance in the case where DMI and collected alkali are recycled. It should be noted that the material balance shown in Figs. 3 and 4, in each of the frames, the figures in the left side frames as viewed in facing to the drawing, correspond respective element in Fig. 1, and the figures in the right side frames as viewed in facing to the drawing, correspond to balance values corresponding to the element shown in the left side frame.

In implementation of the shown process, it should be obvious to effect modification in the extent not changing principle of the flow adapting to the material or the condition of the implementation site and not limited to the drawings as long as not departing from the spirit of the invention, and should not be any negative factor for the superiority of the shown process.

C'j 1 4

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EMBODIMENT

I

Fig. I shows one example for the case implementing the present invention. The reference numeral 9 represents a PCB containing insulation oil of relatively high concentration, and contains approximately 7% of PCB. The reference numeral I denotes an aprotic polar solvent DMI), 2 denotes alkali caustic soda), 14 denotes DMI collected by a distillator after reaction, 13 denotes a lower alcohol ethanol).

These are supplied to a reaction bath 4 with stirrer with a jacket 5, and heated at about 210 (C by passing a hot heating medium through the jacket 5 to perform reaction under atmospheric pressure for 1 to 4 hours. After reaction, PCB in the reaction liquid is analyzed to terminate reaction at a timing where the content becomes lower than or equal to a detection limit. This liquid is cooled down to the normal temperature by passing a low temperature coolant through the jacket 5. Then, the reaction liquid in slurry form containing solid NaCl is filtered by a filters as labeled as 6 The filtrate 10 is supplied to the distiller 8 to recover a solvent for use in the next batch reaction. With respect to the still residue 15 thus obtained, PCB analysis was performed.

The PCB content obtained as a result was less than or equal to the detection limit of 0.5 ppb (result of GC-MS).

Separated cake at 11 is dissolved the non-reacted alkali component contained in the cake in ethanol in the dissolving bath 19, and then filtered by a filter to separate into the filtrate 13 and the cake at 12. The filtrate 13 is ethanol dissolved collected alkali and is recycled for use in the next reaction. Here, the filters 6 and 7 are separated into two.

However, instead of separating into two, and the same one may be used in separate manner. It should be noted that 3, 14, 16, 17, 18, 36, 37, 38 are stirrer, the collected MDI, collected ethanol, ethanol, supplemented ethanol, collected DMI bath, first condenser and second condenser, respectively.

Fig. 3 shows the case where the insulation oil containing relatively high concentration of PCB is decomposed, and alkali and solvent are not recycled. On example of material balance of first batch operation is generally shown.

EMBODIMENT 2 Fig. 4 is the case decomposing the insulation oil containing relatively high concentration PCB, and shows one example of material balance with respect to the embodiment of the case where alkali and solvent are recycled.

EMBODIMENT 3 Fig. 2 shows another example of the case where the present invention is implemented. The reference numeral 9 denotes the insulation oil containing relatively low concentration of PCB, in which about 20 ppm of PCB is contained.

Here, low concentration represents low PCB concentration, at which precipitation of reaction product is relatively small even by cooling after reaction. Other numbers are the same as or are those similar in function and property to those explained in Fig. i. Operation of the stirring reaction bath is the same as that in the case of the embodiment 1. However, since the reaction liquid 20 does not contain any solid matter other than finely crushed caustic soda of reaction of dechlorination, it is supplied to distiller 8 as is to perform collection of the solvent. The still residue 15 is dissolved the non-reacted alkali by ethanol in the dissolver 19. The solution is then separated into oil phase and alcohol phase 24 dissolving alkali by the separating bath 21-1. The alcohol phase 22 is recycled for next batch reaction by batch operation. The oil phase is neutralized by acid after washing with water 26 by the washing/neutralizing bath 23 and is separated into oil phase 24 and water phase 25 by the separating bath 21-2. As a result of analysis of PCB with respect to the oil phase 24 thus obtained, it has been found that PCB was eliminated to be less than or equal to detection limit, as being less than or equal to ppb.

EMBODIMENT 4 Fig. 5 shows one example of a method for supplying a material to a reaction bath. The numbers shown herein are common to those if Figs. 1 and 2. These materials are preliminarily mixed in a mixing bath 34 with the stirrer 33, and thereafter, are admixed to a reaction liquid circulation line 30 through a piping 31 by means of the supply pump 32.

The admixed reaction circulating liquid is completely mixed by the static mixer 29 having a heating heater 35, thereafter, is 1 7 returned to a reaction bath 4 with the stirrer 3 (stirring reaction bath) and is further stirred by the stirrer 3.

Since the static mixer 29 draws a part of the liquid subject to stirring operation within the reaction bath 3 via the circulation pump 28, it is naturally necessary to select the mixing strength in the static mixer 29 to be stronger than the mixing strength in the stirring reaction bath.

Alkali is supplied in solid form and is heavier in comparison with the specific weight of the liquid. Thus, a part of alkali may precipitate on the bottom of the stirring reaction bath. Thus, in case of the reactor vessel primarily effecting centrifugal mixing, colloidal condition cannot be maintained to have a tendency to make contact with the reaction liquid insufficient. As a method for improving these, the precipitated solid component is withdrawn from the bottom portion and is passed through the static mixer to maintain and improve colloidal condition in the reaction liquid. This operation is continuously performed even after supplying of the material.

Furthermore, in Fig. 5, 35 denotes a heater for heating the static mixer portion to compensate lowering of temperature due to thermal loss in the circulation line and to elevate temperature as required for effecting to enhance reaction speed.

When reaction is performed at a reaction temperature in the stirring reaction bath of 210 0 C under normal pressure in the method set forth above, as a result of comparison with respect to material supply method between the method directly supply into the reaction bath and the method to supply by the static mixer, the following effect can be obtained.

In comparison with the direct supply method, the method providing the mixing bath is easier in charging operation.

Precipitation of alkali solid substance on the bottom in the reaction bath can be prevented, and this colloidal condition can be maintained to promote reaction.

As a result, when the static mixer is used, the desired task has been achieved at about 80% of required period of the direct method.

EMBODIMENT The embodiment 5 shows an example of process with respect to the insulation oil containing relatively low concentration of PCB in the process flow of Fig. 2. Here, in addition to the reaction bath, distiller is provided separately and collection of solvent is performed therein. When DMI is employed as the solvent, the boiling point is 225.5 0 C at normal temperature, and in contrast to this, the boiling point of the insulation oil is 250 to 470 0 C, they can be easily separated by simple distillation. Therefore, the reaction bath can also used as the distiller. Thus, the process can be simplified and investment can be saved to lower processing cost.

This example is shown in Fig. 6.

It should be noted that distillation may also be performed under reduced pressure in consideration of the temperature of the heating source. For example, for absolute 19 pressure of 40 mmHg, DNI can be distilled and separated from the reaction liquid at 150 C.

In this process, by recycling DMI and alkali dissolved in alcohol, PCB can be removed from TFO (insulation oil) quite economically. Furthermore, defused insulation oil removed PCB can be recycled as fuel oil. In this example, the process flow of this example is shown in Fig. 7, and the material balance at this time is shown in Fig. 8.

In Fig. 7, 39, 40, 41, 42, 43, 44 and 45 denote balancing tank, cooling bath, filtrate receptacle bath, distilled liquid (DMI) receptacle bath, separator, high pressure insulation oil (TFO) receptacle bath, still residue liquid receptacle bath, respectively. 46, 47, 48, 49, 50, 51, 52 denote alkali dissolving bath, case storage, material (PCB containing TFO) supply bath, solvent (DMI) supply bath, new alkali supply bath, respectively. 54, 55, 56 and 57 denote stirring drive motor, TFO washing bath, TFO washing receptacle bath and TFO heavy oil mixing bath, respectively.

Here is shown an example, in which collected DMI is recycled for 15 times, and alkali corrected with modified ethyl alcohol could recycled for more than or equal to 15 times.

At first, utilizing new DMI and new caustic soda, dechlorination reaction of PCB in new TFO containing 80 ppm of PCB is performed. Subsequently, the liquid is separated into TFO phase and DMI phase (solid liquid phase containing solid of caustic soda). The DMI phase (containing caustic soda) is used for reaction again. To TFO lO0Og containing 80 ppm of PCB, 2 0 ON l00Og of DMI and 60g of caustic soda are added to put into the reaction bath. Then, temperature is elevated up to 200 0 C to perform stirring over 2 hours. After 2 hours, residual concentration of PCB in the system becomes 0.55 ppb (less than or equal to detection limit The reaction liquid is at first separated in phase to separate into TFO phase and DMI phase. At this time, if necessary, in order to promote reaction and phase separation, small amount of lower alcohol (containing less than or equal to 10% of water) may be added. Furthermore, in order to assist phase separation, simple filtration is performed once (under increased or reduced pressure), and then phase separation is performed. The TFO phase is mixed with heavy oil after washing to be recycled as fuel oil. DMI in the DMI phase and caustic soda are recycled for dissolving reaction of PCB in new TFO.

Repeating this for 15 times. For reaction, it is possible to add small amount of DMI and small amount of caustic soda. DMI phase containing caustic soda, reaction product and sodium chloride is normally filtered by centrifugal filter, at first, and effect solid liquid separation. Liquid phase filtrate is distilled to recover DMI. This DMI is recycled for next reaction. On the other hand, solid phase component (cake) is added modified ethyl alcohol in sufficient amount for dissolving caustic soda to be used for dechlorination reaction and subsequently residual caustic soda is recovered. At this time, most part of the reaction product and generated sodium chloride may not be dissolved in the modified ethyl alcohol, Y )L

I

1 i) they may be present in solid phase. Such mixed substances are filtered out by centrifugal filtration to perform solid liquid separation. Most of caustic soda may be transferred to the filtrate and recycled for next reaction. Recovery ratio of DMI and alkali was 99% and 91% respectively.

[EMBODIMENT 6] The is the embodiment of the process, in which the material balance of the process is substantially the same as the embodiment 5, reaction is taken place with using triethylene glycol ether (boiling point 216 or tetraethylene glycol dimethylether (boiling point 275.3 o C) as solvent in place of DMI, and using caustic soda as alkali, which are recycled for times. In phase separation of the solvent and TFO, watercontaining methanol (containing 10% of water) is used.

[INDUSTRIAL APPLICABILITY] As set forth above, in the present invention, good result can be obtained even in application for treatment of hydrocarbon oil containing any concentration of an organnochlorine compound, such as PCB contaminated transformer oil or 100% PCB. In certain case, the hydrocarbon oil can be regenerated and recycled. Therefore, dechlorination process of the organnochlorine compound according to the present invention is directed to a process for quite economically dechlorination and defusing organnochlorine compound. By implementing the present invention, environment can be improved economically and saf el y.

2 3 P:\WIIDOCS\CRN\661082.SPE 29/1/99 The claims defining the invention are as follows: 1. A dechlorination process for an organochlorine compound comprising the steps of: a) stirring and mixing the organochlorine compound in a relatively high concentration and excessive alkali in an aprotic polar solvent at 100 C to 300 C in a reaction bath; 10 b) separating and collecting excessive and non-reacted alkali from the resulting 000 *reaction liquid and recycling alkali for dechlorination reaction; c) separating solid component generated after cooling of the reaction liquid and dissolving, separating and collecting alkali contained in said solid component with a lower alcohol and recycling for dechlorination reaction; d) separating and collecting aprotic polar solvent as it is, or in part or in most part Sfrom the reaction liquid and recycling for dechlorination reaction and e) converting the reaction liquid into an alkali-hydrochloride acid salt and a dechlorinate of a material organochlorine compound.

20 2. A dechlorination process for an organochlorine compound comprising the steps of: a) stirring and mixing the organochlorine compound in a relatively low concentration and excessive alkali in an aprotic polar solvent at 100 C to 300 C in a reaction bath; b) separating and collecting excessive and non-reacted alkali from the resulting reaction liquid and recycling alkali for dechlorination reaction; c) separating the solid component generated in a relatively small amount after cooling of the reaction liquid and dissolving, separating and collecting alkali z contained in said solid component with a lower alcohol and recycling for

Claims (9)

1. 3. A dechlorination process for an organochlorine compound according to claim 2, wherein cooled reaction liquid is placed statically to separate the reaction liquid into two phases of the aprotic polar solvent and organochlorine compound and the aprotic polar solvent is collected for recycling in the next dechlorination reaction, and for use in another application after said dechlorination reaction.
2. 4. A dechlorination process for an organochlorine compound according to claim 3, wherein a lower alcohol to be used for collecting alkali is added to promote separation of the non-aprotic polar solvent and said reaction liquid.
3. 5. A dechlorination process for an organochlorine compound according to claim 1, wherein the aprotic polar solvent in the residual liquid separated from the solid component, is distilled and collected as is, or in part or in most part, and recycled for o 20 dechlorination reaction.
4. 6. A dechlorination process for an organochlorine compound according to claims 1 or 2, wherein the lower alcohol to be used for separating and collecting alkali comprises one or more alcohols having one to four carbons with less than or equal to 10% moisture.
5. 7. A dechlorination process for an organochlorine compound according to claims 1 or 2, wherein said aprotic polar solvent contains 50% or more of at least one solvent from the group consisting of sulphone, dimercaptosuccinic acid, 1, 3-dimethyl-2- P:\WPDOCS\CRN\661082.SPE 29/1/99 imidasolidinon, dimethyl polyalkylene glycol, detramethyl urea and N- methylpyrrolidone.
6. 8. A dechlorination process for an organochlorine compound according to claim 1 or 2, wherein by supplying alkali dissolved and collected by lower alcohol and recycled for said dechlorination reaction and for compensating the amount consumed in dechlorination to the reaction bath, and elevating the temperature together with aprotic polar solvent for initiating reaction, most of the lower alcohol is distilled out of the system and collected for recycling for use in alkali collection after next dechlorination reaction. o
7. 9. A dechlorination process for an organochlorine compound according to claim 1 or claim 2, wherein amongst collected alkali to be recycled, newly supplied "i alkali, newly supplied aprotic polar solvent and collected aprotic polar solvent to be recycled, two or three or more are preliminarily mixed and then supplied to the reaction bath. 4
8. 10. A dechlorination process for organochlorine compound according to claim 9, wherein as a method for preliminarily mixing a mixing bath with a stirrer and 20 static mixer are used alone or in combination.
9. 11. A dechlorination process for an organochlorine compound according to claim wherein as a method of using said mixing bath with the stirrer, after charging a part of the collected aprotic polar solvent and the newly supplied aprotic polar solvent into the mixing bath with the stirrer, finely crushed solid caustic soda or caustic alkali of potassium and the collected alkali are mixed in slurry form, then a pair of mixture of the aprotic polar solvent already supplied in the reaction bath and the organochlorine compound and mixed with the slurry to supply the reaction bath. P:\WPDOCS\CRN\661082.SPE 29/1/99 DATED this 29th day of January 1999 By Its Patent Attorneys RESEARCH AND INSTITUTE FOR PRODUCTION AND DEVELOPMENT MITSUI COMPANY LIMITED NEOS COMPANY LIMITED *0 0*00: 0 @55. 0* 5@ SO S. @5 S S S. S b 5* S 5. S. 0 'A 2 O~' ABSTRACT In order to process an organnochlorine compound which is generally difficult to dissolve in a method having no problem in the process and superior in safety and economical efficiency, upon dechlorination of a PCB containing insulation oil (9) containing organnochlorine, such as PCB or the like by reacting with alkali, such as caustic soda or the like in aprotic polar solvent, such as 1,3-dimethyl-2-imidasolidinon or the like, process is made complete by using excessive amount of alkali. The excessive alkali is dissolved and collected by a lower alcohol, such as ethanol and the aprotic polar solvent is collected. Thus, safety, economical efficiency and practicality is increased and the defused oil is recycled as fuel oil and the like. The resource can be used effectively. 2 9