JPS6262119A - Combustion method for liquid organic halides - Google Patents

Abstract

PURPOSE:To completely decompose liquid organic halides such as PCB etc. to make them harmless, by making in advance liquid organic halides such as PCB etc. into a solid composition having specific composition, and then heating it to high temperature, causing vaporized organic halides being released to be burnt with oxygen. CONSTITUTION:Prior to burning treatment, liquid organic halides are in advance made to form a solid composition composed of liquid organic halides, calcium hydroxides and/or magnesium hydroxides, water-soluble polymers, organic acid metallic salts, silicates, and extending agents. The solid composition wherein liquid organic halides are fixed is heated to high temperatures in the presence of or in the absence of oxygen to cause vaporized organic halides to be released from said solid composition. When said vaporized organic halides are burnt at high temperatures with oxygen, they are completely decomposed, with the result that organic halides themselves can not be detected in the combustion flue gases and also can not be detected in the solid composition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a combustion treatment method for rendering liquid organic halides such as PCB harmless.

[Prior art]

Liquid organic halides such as PCB (polychlorinated biphenyls) are extremely stable compounds and are also toxic, making their disposal extremely difficult.

Currently, some companies that own liquid PCN, when its use was first banned, quickly established a treatment method for it by storing it for a short period of time, and assumed that the treatment would be completed, and for temporary storage. , drums, thin iron plate tanks, or transformers have been stored in warehouses, etc. However, over the years, it has leaked from corroded drums, iron plates, etc., and waste metal has been collected by waste iron recovery companies.

There have also been reports of transformers being brought in with their PCBs inside and leaking from abandoned items.

These are just the tip of the iceberg, and the actual state of storage at the end of the world is unknown, 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 render PCB harmless, but the combustion method is considered to be advantageous in terms of processing efficiency. However, the combustion method eliminates 100% PCBs.
It is difficult to decompose and completely render harmless, and to achieve this goal, for example, a three-stage combustion process, namely 140
It is said that the steps of primary combustion at 0°C or higher, secondary combustion at 1500°C or higher, and tertiary combustion at 1400°C or higher are required.

〔the purpose〕

An object of the present invention is to provide a method of detoxifying liquid organic halides such as PCBs by a combustion method, which is highly workable and relatively simple.

〔composition〕

According to the present invention, the liquid organic halide is mixed with calcium hydroxide and/or the liquid organic halide in advance.
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 rod-shaped composition is prepared in the presence or absence of oxygen, A method for combustion treatment of a liquid organic halide is provided, which comprises heating the solid composition to a high temperature and burning the vaporous organic halide released from the solid composition with oxygen.

In the present invention, prior to the combustion treatment, the liquid organic halide is mixed with the liquid organic halide, lucium hydroxide and/or magnesium hydroxide, a water-soluble polymer, an organic acid metal salt, and a silicic acid. A solid composition is formed from a salt and a filler.

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 between calcium oxide and/or magnesium oxide and water generates a large amount of heat, and calcium oxide and/or magnesium oxide reacts with calcium hydroxide and/or magnesium oxide.
Or converted to 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, carboxymethylcellulose, sodium polyacrylate, acrylic amide/acrylic ester copolymer,
Examples include styrene/maleic anhydride copolymer alkali salt, sodium alginate, gelatin, and casein. Such water-soluble polymers contain many parent 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 It is thought that it is converted into a water-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, lylunic 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.

In general, it is preferred 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 also has an effect on insolubilizing halides.

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,
It is thought that water-insoluble compounds 1, such as gehlenite, are formed.

Various inorganic compounds and clay minerals are used as fillers, such as calcium carbonate, gypsum, silica, zeolite, perlite, and sepiolite.

Examples include white clay, neutral china clay, kaolin, bentonite, and loess. Such extenders have the effect of diluting the exothermic reaction and also have the effect of converting the product into a powder solid that is easy to handle.

Next, to describe the proportions of each component used in the present invention, calcium oxide and/or magnesium oxide is 40 to 70% by weight, and water-soluble polymer is 1.5 to 10% by weight.
, organic acid metal salt 2-10% by weight, silicate 5-15% by weight
, 15-30% by weight of filler.

To preferably produce the solid composition, each component is added to a mixer and stirred uniformly, and then water is added and stirred. Although this operation causes an exothermic reaction and the temperature rises, the organic halide to be treated is added at about 120 to 150° C. and stirring is continued. This stirring is usually done for 1
~5 minutes with Ishiya.

A powdered processed product is obtained. In this case, various changes are possible. For example, water can be added first before mixing each additive 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 1 The 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. What is the usage ratio of each of the above additive components to the organic halide?

It varies depending on the type of organic halide and reaction conditions.

Generally, the total amount of the added components is about 25 to 200 parts by weight per 100 parts by weight of the organic halide. 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.

Further, although this product is in the form of a powder, it can be formed into any shape such as pellets or lumps, if necessary. Incidentally, such a composition used in the present invention is described in JP-A-60-139263.

According to the research of the present inventors, the solid composition of the above-mentioned liquid organic halide can be converted into vapor by heating it to a high temperature in the presence or absence of oxygen. When an organic halide is released and the 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. It was found that it was not detected even in solid compositions.The reason why liquid organic halides are completely decomposed by such heat treatment is not clearly understood, but When heated, the solid composition contains metal compounds such as calcium hydroxide and/or magnesium hydroxide, organic acid metal salts, and silicates. The organic halide that exhibits a decomposition catalytic action and vaporizes from the solid composition is partially decomposed and converted into an unstable structure, that is, a highly combustible structure. Conceivable.

In the method for burning a liquid organic halide according to the present invention, the reaction step includes a step of releasing a vaporized halide with increased combustibility from a solid composition by heating;
It consists of a combustion process of the released vaporous halide. 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, the heating for releasing 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 this heating is generally carried out in the presence of oxygen, although the presence of oxygen is not necessarily required. Next, in the combustion of vaporous organic halides from solid compositions with oxygen, 80
Temperature conditions of 0 to 1500°C, preferably 900 to 1300°C are employed. The combustion of vaporous organic halides is
It 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,
These include metals such as manganese, iron, copper, nickel, and cobalt, and their oxides.

When the present invention is carried out industrially, the combustion furnace does not necessarily need to be divided into two chambers, a heating chamber and a combustion chamber, as described above, and in fact, a combustion furnace with one combustion chamber may be used. It can be implemented using

That is, in this case, the above-described release of the vaporous organic halide by heating the solid composition and the combustion of the vaporous organic halide with oxygen are performed 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 The processing agent containing the ingredients shown in Table 2 below is PC.
It was used for fixing B-containing transformer oil.

Table 2 The composition of the PCB human retrans oil was as described in Table 3.

Table 3 200 grams of the processing agent shown in Table 2 was placed in a small mixer, and 40 cc of water was added and stirred to cause an exothermic reaction. After the temperature reached 142° C. in about 20 seconds, 100 grams of transformer oil containing PCB 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, a PCBA elution 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, an alumina reaction tube 1 with a length of 1500 mm and an inner diameter of 261 nI11.
A combustion chamber A (length 700 mm) formed by winding an electric heating coil around the combustion chamber A and a heating chamber B (length 200 mm) formed by winding an electric heating coil on the flow side thereof is used. there was.

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 inside the heating chamber. Push in the sample. Next, air is supplied from the air cylinder 8 to the flow meter 7 and the line 6.
After blowing 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, the temperature of the heating chamber is started to rise. After raising the temperature of the heating chamber to 1000° C. and maintaining that temperature for about 10 minutes, the heating chamber and combustion chamber a are allowed to cool while flowing air. The heat treatment conditions in this case are as shown in Table 4. In addition, the average temperature increase rate of the heating chamber was 15~b. Collection of PCBs from combustion exhaust gas was carried out in accordance with the Environmental Agency's notification ``Gas phase PCB measurement procedure J (1972)''.
As shown in the drawing, the exhaust gas coming out from the tip of the alumina reaction tube 1 is introduced into the empty bottle 11 through the tube 9, and then 10% N
A0111150 mΩ is placed in the air washing bottle 12 for ventilation cleaning, then two air washing bottles 13 and 14 each containing 150 mQ of n-hexane are passed in sequence, and the air is discharged to the atmosphere through the Florigi force ram 15. Note that each bottle 11.
12, 13 and 14 are all water baths (1 to 5
℃).

(3) PCl3 analysis sample and heat treatment residue were mixed with 200 m of n-hexane (1 in 2
A Soxhlet extraction treatment was performed for 4 hours, and the treatment formula shown below was applied to obtain a test sample solution (A).

In addition, the air washing bin 1 that collects PCBs in the combustion exhaust gas
2 10% Na0II solution and the air washing bottle 13.14
of n-hexane is collected in a branch funnel. Next, these three air washing bottles and the empty air washing bottle 11 are each washed three times with 50 mα of n-hexane, and the washing liquid is added to the separating funnel. The hexane layer from this separating funnel is subjected to treatment A shown below to obtain a test sample solution (B).

[Processing A]

The n-hexane layer is washed twice with 200 mQ of purified water, dehydrated with anhydrous sodium sulfate, and concentrated to about 5 mQ or less using a KD concentrator. This concentrated n-hexane layer was taken into a 25 mQ test tube, 5 mQ of IN-KOH/ethanol was added thereto, and after vigorous shaking, it was left to stand for days and nights. Purified water in an amount three times that of ethanol is added to this, and after shaking and standing, the upper layer of n-hexane is separated. This n-hexane layer was I
After washing with NKOI+ and purified water, clean up by passing through a Floridian power ram. Next, this column is eluted with ethyl ether, and the eluted ethyl ether/hexane layer is concentrated to 3+nQ using a D concentrator.

The test sample solution obtained as described above was subjected to 'tcp-GC analysis to measure PCBs contained therein.

Further, the chlorine content contained in the 10% Na11 layer obtained from the separating funnel was measured according to JIS 0102.

(4) Experimental Results The measurement results of the pcn are shown in Table 5 in correspondence with the experiment numbers shown in Table 4 above.

Table 5 The results of the chlorine analysis are shown in Table 6 in correspondence with the experiment numbers in Table 4. Note that the numerical value shown in parentheses after the chlorine value in the exhaust gas in Table 6 indicates the ratio (%) of the chlorine content to the total chlorine in the sample.

In addition, in this experiment, the heating temperature was set at 1000 to 1200°C.
Although the heating was carried out under conditions of a residence time of 2 to 5 seconds, the heating temperature can be lowered by increasing the residence time.

Table 6 [Effects] 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, in the case of the present invention.

It is easy to implement, considering that conventionally it has been extremely difficult to decompose PCBs into their original form using combustion treatment methods.

The industrial significance of the present invention is enormous.

[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. Designated Agent: Naoyuki Todo, Director, Institute of Chemical Technology, Agency of Industrial Science and Technology

Claims (1)

[Claims] (1) A liquid organic halide is prepared in advance from the liquid organic halide, calcium hydroxide and/or magnesium hydroxide, a water-soluble polymer, an organic acid metal salt, a silicate, and an extender. After forming the solid composition, heating the solid composition to a high temperature in the presence or absence of oxygen, and burning the vaporous organic halide released from the solid composition with oxygen. A method for combustion treatment of liquid organic halides, characterized by: