JPH0597439A - Refining device for diarsenic trioxide - Google Patents

Abstract

PURPOSE:To enhance the efficiency of separating impurities, such as Sb, and to obtain high-purity As2O3 as well as to prevent the generation of environmental pollution with splashing of the As2O3 by providing a constant-temp. heating container of the raw material As2O3 which can be moved by specific constitution. CONSTITUTION:A reduced pressure sublimation chamber 1, a raw material supplying chamber 2 which is connected to its flank, and the constant-temp. heating container 3 which is movable between these two chambers are provided. A valve 9 for discharge is mounted in the raw material supplying chamber 2, by which the raw materials are supplied while gases are discharged from this valve. The pollution of the working environment by splashing of the raw material As2O3 powder is prevented.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an apparatus for purifying diarsenic trioxide.

[0002]

2. Description of the Related Art Diarsenic trioxide (As)
₂ O ₃ ) is important as a starting material for metallic arsenic and its alloys, chalcogenide glasses of arsenic, and various inorganic or organic arsenic compounds in various fields such as chemistry and electronics industry.

As ₂ O ₃ is usually supplied to the market by resublimating low-grade As ₂ O ₃ obtained by roasting a metal arsenide in a reflex furnace equipped with a sedimentation chamber. However, in such an industrial scale sublimation method (dry method), it was difficult to sublimate As ₂ O ₃ alone for purification because the temperature distribution in the reverberatory furnace was non-uniform, and it was obtained. Impurities such as antimony (Sb) are present in As ₂ O ₃ at a concentration of several tens ppm to several hundreds ppm, which is not preferable as a raw material for producing a high-purity arsenic compound. Furthermore, in the dry method, when the raw material As ₂ O ₃ is supplied to the reverberatory furnace or the purified As ₂ O ₃ obtained
When taking out ₃ , there is a problem that highly toxic As ₂ O ₃ scatters and pollutes the working environment.

On the other hand, various wet methods have been proposed to replace the dry method. For example, recrystallization from hot water,
Known methods include a recrystallization method from hydrochloric acid or an alkaline aqueous solution, a method in which arsenic trichloride is replaced by distillation, and then hydrolysis is performed. However, in these wet methods, treatment of wastewater containing a toxic arsenic compound is a problem, and thus a large amount of investment is required.

Therefore, as a method for purifying As ₂ O ₃ , S
There is a demand for a method capable of effectively removing impurities such as b) without causing problems such as waste water and scattered dust.

The object of the present invention is to provide high-purity As ₂ O ₃ having a high efficiency of separating impurities such as Sb,
A that does not cause environmental pollution due to the scattering of As ₂ O ₃
It is to provide a purifying device for s ₂ O ₃ .

[0007]

The above object of the present invention is characterized by having a decompression sublimation chamber, a raw material supply chamber connected to the side surface thereof, and a constant temperature heating container movable between the two chambers. It is achieved by the refining device of.

In the apparatus of the present invention, by separating the vacuum sublimation chamber for the purification of As ₂ O ₃ and the raw material supply chamber, the raw material As ₂ O ₃ is purified from As. Mixing with ₂ O ₃ is prevented. In addition, since the raw material As ₂ O ₃ is heated in a heating container capable of maintaining a constant temperature, uniform constant temperature heating is possible, and As ₂ O ₃ can be accurately performed.
Only As can be sublimated, contamination of impurities such as Sb can be prevented, and high-purity As ₂ O ₃ can be obtained.

Further, when an exhaust valve is attached to the raw material supply chamber, the raw material is supplied while being exhausted from the exhaust valve to prevent contamination of the work environment due to scattering of As ₂ O ₃ powder of the raw material. can do.

[0010]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 shows an example of a preferred embodiment of the As ₂ O ₃ purifying apparatus of the present invention.

The reduced pressure sublimation chamber 1 is a portion for sublimating As ₂ O ₃ under reduced pressure for purification, and is made of a stainless steel material or the like. At the top of the vacuum sublimation chamber 1, there is a valve 4 for connecting to the vacuum line, and at the bottom is the precipitated purified As ₂ O ₃
There is an outlet 5. In the device of the present invention, the take-out port 5
After the packaging bag is attached to the product, the valve can be opened to bag the product, thereby preventing the product from scattering. In addition, the operation of taking out this product may be linked with the weighing machine.

A raw material supply chamber 2 is connected to the side surface of the reduced pressure sublimation chamber 1. An open / close lid 6 for supplying As ₂ O ₃ and an air inlet valve 7 for returning to normal pressure at the end of the reaction are attached to the upper part of the raw material supply chamber 2. The air feeding valve 7 is not limited to this position, and may be located at any position, and may be installed in the decompression sublimation chamber 1. In addition, a discharge container 8 for collecting sublimation residues is provided in the lower part of the raw material supply chamber 2 if necessary.
An exhaust valve 9 may be attached to the upper part of the discharge reservoir container 8, and when the raw material is supplied, the exhaust valve 9 is opened to make the supply chamber a negative pressure to prevent the scattering of As ₂ O ₃ powder. it can. The mounting position of the exhaust valve 9 is not limited to this portion, and may be an arbitrary portion of the raw material supply chamber 2.

The heating container 3 is made of a stainless steel material or the like and is constructed so as to be movable between the reduced pressure sublimation chamber 1 and the raw material supply chamber 2. A heater and a temperature sensor are installed in the heating container 3 to enable constant temperature heating. For example, the heating container may be made of a double-walled material, and the heater and the temperature sensor may be installed inside the heating container. The heating container 3 is fixed to a stainless pipe 10, and leads of a heater and a temperature sensor are led through the pipe 10 and connected to a temperature control power supply 11. The pipe 10 is fixed to a moving partition 12 which divides the decompression sublimation chamber 1 and the raw material supply chamber 2, and the other end is held by a lid 14 provided with a leak prevention seal 13. The moving partition 12 also moves between a stopper 15 provided at the boundary between the decompression sublimation chamber 1 and the raw material supply chamber 2 and a lid 14 to position the heating container 3 in the decompression sublimation chamber 1 and the raw material supply chamber 2. To do. In the moving partition 12, the contact portion 16 is preferably made of a material such as polytetrafluoroethylene (PTFE) in order to smoothly move the bottom of the raw material supply chamber. Further, the heating container 3 can be rotated above the discharge reservoir 8 in order to remove the sublimation residue.

Each connecting part of the device is tightly tightened by using a gasket or an O-ring, and 26.6 × 10 Pa (20
mmHg) or less, preferably 13.3 × 10 to 1.
It should withstand a decompression operation of about 33 × 10 Pa.

A method for purifying As ₂ O ₃ using the apparatus of the present invention will be described below.

First, in the raw material supply chamber 2, the open / close lid 6 for supplying the raw material is opened to put the industrial As ₂ O ₃ 17 of the raw material into the heating container 3. At the time of supplying the raw material, preferably, the exhaust valve 9 is evacuated to bring the raw material supply chamber 2 to a negative pressure. Then tighten each connection and open valve 4 to 26.6 ×
About 10 Pa (20 mmHg) or less, preferably 13.
The heating container 3 is moved to the reduced pressure sublimation chamber 1 in a reduced pressure state of about 3 × 10 to 1.33 × 10 Pa. Then, the heating container 3 is heated to about 200 to 350 ° C., preferably 250 to 28 ° C.
As ₂ O _{3 is} sublimated while maintaining a constant temperature between 0 ° C. At a temperature of 350 ° C. or higher, As ₂ O ₃ melts and corrodes the container, and the sublimation rate, the purity of As ₂ O _{3 and} the like decrease, which is not preferable.

When the sublimation is completed, the heating is stopped and the valve 7
Open and gradually add air to return to atmospheric pressure. Next, the heating container 3 is returned to the raw material supply chamber 2, the next raw material is added from the opening / closing lid 6, and sublimation is performed again. When there is a large amount of sublimation residue, the residue in the heating container 3 is scraped off, the container is rotated 180 degrees, and collected in the discharge storage container 8 and taken out. Alternatively, if this operation is complicated, a cartridge type in which another raw material tray is put in the heating container 3 may be used. Usually, sublimation is repeated several times by supplying raw materials, and after the sublimate reaches a unit weight, the purified As ₂ O ₃ 18 is taken out from the bottom of the vacuum sublimation chamber 1.

When the depressurization conditions and the heating temperature are in the optimum ranges, high-purity As ₂ O ₃ having an Sb content of about 1 to 20 ppm is used as a raw material from industrial As ₂ O ₃ containing about 500 to 50 ppm of Sb. Obtainable.

The following operation example using an operation example the invention device.

As the raw material, the sample No. shown in Table 1 below was used.
Three types of industrial As ₂ O _{3 of 1} to ₃ were used.

Table 1 Sample Ignition residue Chloride Iron (Fe) Sulfide Heavy metal Se Sb Content No %%% (S) %% ppm ppm ppm% 1 0.1 0.01 0.02 0.02 0.15 10 500 98.8 2 0.05 0.002 0.004 0.01 0.10 5 220 99.5 3 0.08 0.01 0.02 0.02 0.10 3 100 99.0 Move the heating container 3 (content 6.8 liters) to the raw material supply chamber 2, open the open / close lid 6 for feeding the raw material, and exhaust from the exhaust valve 9. After putting 8 kg of the raw material into the heating container 3, each connection part was tightened, and the pressure was reduced to 6.6 × 10 Pa (5 mmHg) with a vacuum pump through the valve 4.

The moving partition 12 is pushed to the position of the stopper 15 to move the heating container 3 to the decompression sublimation chamber 1 (internal volume about 230).
Liter) and activate the power supply to heat it to 280 ° C., while maintaining the pressure at 6.6 × 10 Pa or less,
Left for hours. The valve 7 was opened to gradually return to atmospheric pressure, the heating container 3 was returned to the raw material supply chamber side, 8 kg of raw material As ₂ O ₃ was again added from the open / close lid 6 for feeding raw material, and the same operation was repeated.

After four operations, the opening / closing lid 6 is opened to open the container 3
Scrape off the residue of, and rotate the container 3,
The residue was collected and discarded. Then, the above operation was repeated to perform sublimation.

The sublimated As ₂ O ₃ hardly adheres to the wall of the decompression sublimation chamber 1 and settles at the bottom of the decompression sublimation chamber 1. Therefore, remove the cap of the take-out port 5 and take out the product bag. Attach to mouth 5, open the cock and purify As ₂ O
By collecting ₃ , purified A without scattering
s ₂ O ₃ was obtained.

The yield of purified As ₂ O ₃ by the four treatments was about 30 kg, and the yield was about 94%, although it varied somewhat depending on the raw material. The content of Sb which is difficult to remove is as shown in Table 2 below. The other impurities had a content corresponding to JIS special grade. For comparison, the results using a conventional atmospheric sublimation device are also shown.

Table 2 Sample Raw material As ₂ O ₃ purified As ₂ O ₃ purified As ₂ O ₃ No Sb (ppm) Sb (ppm) Sb (ppm) (invention method) (conventional method) 1 500 20 120 2 220 20 From the results of 100 3 100 10 50 or more, according to the purification apparatus of the present invention, As ₂ O having a high purity can be obtained, as compared with the case of using the conventional atmospheric sublimation apparatus.
It turns out that ₃ is obtained.

[0028]

According to the refining apparatus of the present invention, As ₂ O ₃
By separating the vacuum sublimation chamber and the raw material supply chamber for the purification, the raw material in providing the purified As ₂ O
₃ raw material As ₂ O ₃ is prevented from being mixed into. Further, since the sublimation under reduced pressure is carried out in a heating vessel capable of maintaining a constant temperature, it is possible to set a strict temperature, and the separation efficiency of As ₂ O ₃ and Sb ₂ O ₃ is improved. Therefore, high-purity As ₂ O ₃ can be obtained, and there is an advantage of energy saving as compared with the case of using a reverberatory furnace. Further, since it is possible to prevent the scattering of dust when the raw materials are charged and the purified product is taken out, it is extremely valuable in terms of preventing environmental pollution.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a refining device of the present invention.

[Explanation of reference numerals] 1 decompression sublimation chamber 2 raw material supply chamber 3 heating container 4 decompression valve 5 product outlet 6 open / close lid for raw material supply 7 air inlet valve 8 discharge reservoir 9 exhaust valve 10 pipe 11 temperature Power source 12 Moving partition wall 13 Seal for leak prevention 14 Lid 15 Stopper 16 Contact part of moving partition wall 17 Raw material As ₂ O ₃ 18 Purified As ₂ O ₃

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Harudou Yamashita 946-6 Naeba Ko, Utsumi-cho, Shozu-gun, Kagawa Prefecture (72) Toshiaki Yasumura 1-52-1115 Higashi-Awaji, Higashiyodogawa-ku, Osaka-shi, Osaka

Claims (2)

[Claims] 1. An apparatus for purifying diarsenic trioxide, comprising a decompression sublimation chamber, a raw material supply chamber connected to the side surface of the chamber, and a constant temperature heating container movable between the chambers. 2. The apparatus for purifying arsenic trioxide according to claim 1, wherein an exhaust valve is provided in the raw material supply chamber.