JPS648242B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a combustion treatment method for rendering liquid organic halides such as PCBs harmless. [Prior Art] Liquid organic halides such as PCBs (polychlorinated biphenyl) are extremely stable compounds and are also toxic, making their disposal extremely difficult. Currently, some companies that have liquid PCBs are
When its use was first banned, a treatment method was quickly established by storing it for a short period of time, and the treatment was completed, so drums, drums,
They have been stored in warehouses in thin iron plate tanks or transformers. However, over the years, there have been reports of leaks from corroded drums, iron plates, etc., or leaks from transformers that have been brought to waste metal recovery companies with PCBs in them and left unattended. ing. These are just the tip of the iceberg.
The actual situation of storage at the terminal is not known, and the situation is extremely worrying. Furthermore, even companies that have spent a huge amount of money on storage facilities are concerned about leakage and contamination due to collapse, etc., in the event of a natural disaster such as an earthquake. Conventionally, various methods have been provided to make PCBs harmless, but the combustion method is considered to be advantageous in terms of processing efficiency. However, it is difficult to decompose 100% of PCBs and make them completely harmless by the combustion method, and to achieve this goal, for example, 3
It is believed that a staged combustion process is required, that is, a first combustion at 1400°C or higher, a second combustion at 1500°C or higher, and a tertiary combustion at 1400°C or higher. [Objective] The object of the present invention is to provide a method for detoxifying liquid organic halides such as PCBs by a combustion method, which is easy to work with and relatively simple.
The purpose is to provide a method to reliably render it harmless. [Configuration] According to the present invention, a liquid organic halide is prepared by combining the liquid organic halide, calcium hydroxide and/or magnesium hydroxide, a water-soluble polymer, an organic acid metal salt, and a silicate in advance. , and an extender, the solid composition is heated to a high temperature in the presence or absence of oxygen, and the vaporous organic halide released from the solid composition is heated. , a method for combustion treatment of liquid organic halides is provided, which is characterized by combustion with oxygen. In the present invention, prior to the combustion treatment, the liquid organic halide is mixed with the liquid organic halide, calcium hydroxide and/or magnesium hydroxide, a water-soluble polymer, and an organic acid metal salt.
A solid composition is formed of a silicate and an extender. To produce such a solid composition, when calcium oxide and/or magnesium oxide is reacted with water, a water-soluble polymer, an organic acid metal salt, a silicate, and a liquid organic halide are added to the reaction system. This can be done by adding fillers. In this case, the reaction of calcium oxide and/or magnesium oxide with water generates a large amount of heat, and the calcium oxide and/or magnesium oxide is converted into calcium hydroxide and/or magnesium hydroxide. Various conventionally known water-soluble polymers are used, including polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, methylcellulose, ethylcellulose, and carboxymethylcellulose, sodium polyacrylate, and acrylic acid amide. /acrylic acid ester copolymer, styrene/maleic anhydride copolymer alkali salt, sodium alginate, gelatin, casein, etc. Such water-soluble polymers contain many hydrophilic groups such as carboxyl groups and hydroxyl groups in their molecules, and under alkaline conditions they react with organic halides and silicates, or become gel-like substances, and eventually release water. It is thought that it is converted into an insoluble substance. As the organic acid metal salt, various conventionally known aliphatic and aromatic ones having a carboxyl group are used, such as stearic acid, capric acid, lauric acid, myristic acid, palmitic acid, linoleic acid, and linolenic acid. , metal salts of higher fatty acids such as oleic acid, and aromatic carboxylic acids such as benzoic acid, salicylic acid, p-hydroxybenzoic acid, naphthoic acid, and tannic acid. Further, examples of metal salts include aluminum, manganese, cobalt, calcium, magnesium, iron, zinc, and nickel. Generally, it is preferable to use organic acid metal salts that are used as metal soaps. Such organic acid metal salts are water-insoluble, have the effect of making the product produced after the reaction into a smooth powder, and also form coordination bonds with organic halogen compounds and the above-mentioned polymers, and form organic It is thought that it is also effective in making halides insoluble. Examples of the silicate include sodium silicate, calcium silicate, magnesium silicate, sodium calcium silicate, etc., and use of magnesium calcium silicate is preferred. Moreover, silicic acid includes ortho-silicic acid and meta-silicic acid. Naturally occurring silicates can be advantageously used as such silicates. Such silicates react with organic halides to produce organohalopolysiloxanes, or react with various metal elements present in the reaction system to form water-insoluble compounds such as gehlenite. considered to be a thing. Various inorganic compounds and clay minerals are used as fillers, such as calcium carbonate, gypsum,
Silica, zeolite, perlite, sepiolite, white clay, neutral china clay, kaolin, bentonite,
Examples include yellow clay. Such extenders have the effect of diluting the exothermic reaction and also have the effect of converting the product into a powdered solid that is easy to handle. Next, regarding the usage ratio of each component used in the present invention, calcium oxide and/or magnesium oxide is 40 to 70% by weight, water-soluble polymer
1.5 to 10% by weight, organic acid metal salt 2 to 10% by weight, silicate 5 to 15% by weight, and filler 15 to 30% by weight. To preferably produce the solid composition, each component is added to a mixer and stirred uniformly, and then water is added and stirred. This operation causes an exothermic reaction and the temperature rises, but the organic halide to be treated is added at about 120 to 150°C and stirring is continued. When this stirring is usually performed for about 1 to 5 minutes, a powdery treated product is obtained. In this case, various changes are possible. For example, water can be added first before mixing each additional component, and the order of mixing each component can be arbitrary. The reaction can be carried out by dissolving it in an organic solvent in advance and adding it to water, and then adding this to a mixture of other additive components and the organic halide.
Furthermore, it is possible to form a homogeneous mixture of each additive component in advance, and then mix and react this mixture, water, and organic halide on site.
An example of such a mixture is shown in the table below.

[Table] The above reaction is carried out at a temperature below the boiling point of the organic halide, and in the case of PCB, it is preferably carried out at about 90 to 145°C. The reaction temperature can be adjusted by adjusting the amount of inorganic extender added. As the reactor, a sealed type is used. The usage ratio of each of the above additive components to the organic halide varies depending on the type of organic halide and reaction conditions, but in general, the total amount of the additive components is 25 to 200 parts by weight per 100 parts by weight of the organic halide. It is about 100%. The ratio of water used is about 5 to 100 parts per calcium oxide and/or magnesium oxide. The product obtained as described above is a product in which the organic halide is immobilized, and elution of the organic halide from the solid substance is hardly observed.
Furthermore, although this product is in the form of a powder, it can be formed into any desired shape such as pellets or lumps, if necessary. The composition used in the present invention is described in Japanese Unexamined Patent Application Publication No. 1989-1999.
It is described in Publication No. 139263. According to the research of the present inventors, the solid composition in which the liquid organic halide is immobilized can be heated to a high temperature in the presence or absence of oxygen to convert the solid composition into a vaporized organic halide. When a halide is released and this vaporized organic halide is burned at high temperature with oxygen, the liquid organic halide is virtually completely decomposed, and no organic halide itself is detected in the combustion exhaust gas, and the solid It was also found that no detection was observed in the composition. The reason why the liquid organic halide is completely decomposed by such heat treatment is not clearly clarified, but when the solid composition is heated, the solid composition contains calcium hydroxide and/or magnesium hydroxide. These metal compounds act as decomposition catalysts for liquid organic halides, and the organic halides vaporized from solid compositions are partially Those with unstable structures that have been subject to decomposition,
In other words, this is thought to be due to conversion to a structure with high combustibility. In the method of combustion of a liquid organic halide according to the present invention, the reaction step includes a step of releasing a vaporous halide with increased combustibility from a solid composition by heating, and a step of releasing a vaporous halide with increased combustibility from a solid composition by heating. It consists of a combustion process. Therefore, when implementing the present invention, it can be implemented using a combustion furnace provided with a heating chamber and a combustion chamber, and the conditions of the heating chamber and the combustion chamber can be changed. In this case, heating to release the vaporous organic halide from the solid composition is carried out at 800-1500°C, preferably at 850°C.
Temperature conditions of ˜1200° C. are employed, and the heating is generally carried out in the presence of oxygen, although the presence of oxygen is not necessarily required. Next, combustion of the vaporous organic halide from the solid composition with oxygen is carried out at temperatures of 800 to 1500°C, preferably 900 to 1500°C.
A temperature condition of 1300℃ is adopted. The combustion of vaporous organic halides can be carried out in the presence of an oxidation catalyst, and in this case, conventionally known oxidation catalysts are used, such as silver, titanium, manganese, iron,
These include metals such as copper, nickel, and cobalt, and their oxides. When the present invention is carried out industrially, the combustion furnace does not necessarily have a heating chamber and a combustion chamber, as described above.
It is not necessary to divide it into two chambers; in fact it can be implemented with one combustion chamber. That is, in this case, the vaporous organic halide is released by heating the solid composition described above;
Combustion of the vaporous organic halide with oxygen takes place in the same combustion chamber. When the present invention is carried out industrially, a combustion furnace of either a vertical type or a horizontal type, preferably a rotary kiln type, is used, and the solid composition as a feedstock is in the form of a powder, It can be fed into the furnace in any form such as pellets or lumps. Example (1) Preparation of solid composition A processing agent containing the ingredients shown in Table 2 below was used to fix PCB-containing transformer oil.

[Table] The composition of the transformer oil containing PCB was as described in Table 3.

[Table] 200 grams of the processing agent shown in Table 2 was placed in a small mixer, and 40 c.c. of water was added and stirred to cause an exothermic reaction. After reaching 142℃ in about 20 seconds, the PCB
100 grams of trans oil was added and stirring was continued. The temperature was measured after about 2 minutes and was 96°C. After measuring the temperature, the mixture was further stirred for 1 minute, and the powdered mixture was taken out. This temperature was 82°C. After air-drying this powder and bringing it to room temperature, the PCB
A dissolution test was conducted. The test method was in accordance with the Environment Agency Notification No. 13 (a) of 1972. As a result, no elution of organic halides was observed. (2) Combustion furnace treatment of solid composition The combustion furnace has the structure shown in the drawing, that is, a combustion furnace formed by winding an electric heating coil around an alumina reaction tube 1 with a length of 1500 mm and an inner diameter of 26 mm. Room a
(length 700 mm) and a heating chamber b (length 200 mm) formed by similarly winding an electric heating coil on the upstream side thereof. In order to heat-treat the sample of the solid composition (powder) obtained in (1) above, first, the combustion chamber a was heated to a predetermined temperature, and then the sample was collected in a combustion boat in the heating chamber b. Push in the sample. Next, air is blown from the air cylinder 8 through the flowmeter 7 and line 6 into the alumina reaction tube 1 from the tip of the conduit 5 inserted into the lid 4 at a constant rate for about 5 minutes, and then air is blown into the heating chamber. Start raising the temperature of b. After raising the temperature of heating chamber b to 1000℃ and maintaining this temperature for about 10 minutes, while flowing air,
The heating chamber b and the combustion chamber a are allowed to cool. The heat treatment conditions in this case are as shown in Table 4. Moreover, the average temperature increase rate of heating chamber b is 15 to 19°C/min.

[Processing A]

Wash the n-hexane layer twice with 200 ml of purified water,
After dehydration with anhydrous sodium sulfate, approximately 5
Concentrate to less than ml. This concentrated n-hexane layer was
ml test tube, add 5 ml of 1N-KOH/ethanol
After shaking vigorously, let stand overnight. Add 3 times as much purified water as ethanol to this,
After shaking and standing still, the upper layer of n-hexane is separated.
After washing this n-hexane layer with 0.1NKOH and purified water, it is cleaned up through a floridical column. Next, this column was eluted with ethyl ether, and the eluted ethyl ether/hexane layer was
Concentrate to 3 ml using a KD concentrator. The test sample solution obtained as described above was subjected to ECD-GC.
The PCBs contained therein were analyzed. In addition, the chlorine content contained in the 10% NaOH layer obtained from the separatory funnel was measured in accordance with JIS K0102. (4) Experimental Results The measurement results of the PCB are shown in Table 5 in correspondence with the experiment numbers shown in Table 4 above.

[Table] The results of the chlorine analysis are shown in Table 6 in correspondence with the experiment numbers in Table 4 above. In addition, Table-6
The value shown in brackets after the chlorine value in the exhaust gas indicates the ratio (%) of that chlorine content to the total chlorine in the sample. In addition, in this experiment, the heating temperature was 1000 to 1200℃.
Although this was carried out under the conditions of a residence time of 2 to 5 seconds, the heating temperature can be lowered by increasing the residence time.

[Table] [Effect] As can be seen from the results shown in Table 5 above,
It is clear that according to the present invention, PCBs are completely decomposed and rendered harmless. Moreover, the present invention is easy to implement, and considering that conventionally it has been extremely difficult to completely decompose PCBs using combustion treatment methods, the present invention has great industrial significance.

[Brief explanation of drawings]

The drawings show a system diagram of an apparatus used to carry out the present invention. 1... Alumina reaction tube, 2, 3... Electric heating coil, 7
...flow meter, 8... air cylinder, a... combustion chamber, b... heating chamber.

Claims (1)

[Claims] 1 A liquid organic halide is mixed in advance with the liquid organic halide, calcium hydroxide and/or
Or, after forming a solid composition consisting of magnesium hydroxide, a water-soluble polymer, an organic acid metal salt, a silicate, and an extender, the solid composition is treated in the presence or absence of oxygen, A method for combustion treatment of a liquid organic halide, which comprises heating the solid composition to a high temperature and burning the vaporous organic halide released from the solid composition with oxygen.