JPS58217412A - Method for recovering metallic selenium from dry copying drum - Google Patents

Abstract

PURPOSE:To strip and recover a metallic selenium film from a dry copying drum by heating the drum to a specified temp, to roughen the surface of the film and immersing the drum in a mineral acid bath. CONSTITUTION:A dry copying drum having a formed metallic selenium film is heated to 60-200 deg.C to roughen the surface of the film. The heating is carried out by immersion in hot water, putting in a gas furnace, an electric furnace or a high frequency furnace, or other method. The heated drum is immersed in a mineral acid bath contg. 2-30wt% nitric acid, 5-50wt% sulfuric acid or 3-6% hydrochloric acid at room temp. for 1-1.5 days or at 80 deg.C for 1-2hr.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering metallic selenium from a dry copying drum used in a dry copying apparatus, in which the metal selenium is recovered in the form of flakes from the dry copy drum.

In recent years, various types of dry-type or wet-type office copying devices have been widely used, and the spread of dry-type copying devices is remarkable, and the number of copying drums that are disposed of is increasing accordingly. In other words, copying drums to be disposed of have various histories, such as those that are defective during manufacturing, those that have reached the end of their useful life, those that have become defective due to incorrect operation during use, or those that have become defective for other reasons. It depends on the cause. Therefore, a copying drum in which metallic selenium having a purity of 99.99 wt% to 99.999 wt. In the early days, there were few copying drums to be disposed of.

The waste drums were simply melted and processed to recover only the aluminum, with no consideration given to the recovery of metallic selenium. With the increase in the number of discarded drums, recovery of metallic selenium has started to be considered, but there is no suitable method for recovering only metallic selenium, and the method of dissociating selenium through heat treatment causes the selenium to vaporize and become harmful to the working environment. aggravates skin and respiratory tract irritation,
Corrosive effect Danger of causing poisoning symptoms such as dizziness and evil spirits Dust 9 The permissible concentration of selenium in the working environment is 0.1 mg.
/ Because it is quiet, it is necessary to have recovery equipment that does not leak the selenium vapor generated during heat treatment to the outside, and there are many problems such as the treatment process after recovery, work environment, equipment-related, etc. , a simple method for recovering metal selenium film was developed.

As a result of various studies to solve these problems, the inventors of the present invention have found that if a dry copying drum on which a metal selenium film is formed is heat treated to roughen the metal selenium film and then treated with mineral acid, the metal selenium will be removed. The present invention was made based on the recognition that it is possible to recover the sludge in the form of flakes. That is, in the present invention, a dry copying drum on which a metal selenium film has been formed is heat-treated to 60 to 200°C to roughen the surface of the metal selenium film, and then immersed in a mineral acid bath to form a metal selenium film on the drum. This is a method 7 for recovering metallic selenium from a dry copying drum.

As mentioned above, the dry copying drum used in the present invention is coated with 10 to 100 μm of metallic selenium with a purity of 99.99 wt% to 99.999 wt%.
The metal selenium film is usually deposited on the surface of an aluminum drum in an amorphous and mirror-like manner using a vapor deposition method to a thickness of 2.

In this development i, this copy tram is first
The surface of the metal selenium film is roughened by heat treatment at ℃. The temperature range in this surface roughening treatment is limited to 60 to 200°C based on the fact that the transformation temperature at which amorphous selenium crystallizes is 60 to 80°C, and the melting point of metallic selenium is 2202°C. As the heat treatment means, an appropriate method such as a heating method by immersion in hot water, a heating method in a heating furnace such as a gas furnace, an electric furnace, or a high frequency furnace, or a heating method using an air bath can be applied. However, the heat treatment time is
It is appropriately selected depending on the heat treatment means, heating temperature, etc. For example, in the case of immersion in hot water at 100° C., it is preferable to conduct the treatment for at least 2 hours. As a result of this heat treatment, the surface of the copying drum loses its shine from a shiny mirror surface to a rough surface with fine irregularities. Therefore, the state of this change can be visually observed and processed.

The heat treated copying drum 14' is then immersed in a mineral acid bath. The mineral acids used here are preferably nitric acid, sulfuric acid, hydrochloric acid, etc., and these mineral acids can be used as a single bath or as an appropriate mixed bath. Therefore, the concentration of the mineral acid bath, the treatment temperature, the treatment time, etc. are determined by the type of acid used.

That is, when using a single mineral acid bath, nitric acid has a concentration of 2 to 3 wt%, sulfuric acid has a concentration of 5 to 50 wt%,
For hydrochloric acid, an aqueous solution with a concentration range of 3 to 6 wt is used, and at concentrations below the respective lower limits, the peeling phenomenon of metallic selenium is hardly observed, and at concentrations above the respective upper limits.

The dissolution of metallic selenium becomes intense, and the rate of recovering metallic selenium as peeled pieces decreases significantly.

Also, when using a mixed bath as a mineral acid bath.

In a bath containing 2 to 30 wt% nitric acid or 5 to 50 wtL% sulfuric acid.

It is preferable to use an aqueous solution to which 0.3 to 0.6 wt % of hydrochloric acid is added. Although the use of a mixed bath slightly increases the amount of metal selenium and aluminum dissolved, the processing time can be significantly reduced. but.

When the amount of hydrochloric acid added is less than 0.3 wt%, almost no effect is observed, and when it is added more than 0.6 wt%, the amount of dissolved metallic selenium increases and black color appears on the aluminum drum. This is undesirable because undissolved matter becomes attached, the recovery rate of metal selenium flakes decreases, and cleaning of the drum becomes necessary.

The treatment temperature in this immersion treatment ranges from room temperature to 100°C.
However, since the reaction rate increases as the temperature rises, the processing time required for peeling can be shortened. However, when the bath temperature is 60° C. or higher, the surface of the metal selenium film is also roughened, and peeling progresses quickly, but at the same time, the amount of metal selenium and aluminum dissolved also increases. Therefore, when increasing the processing temperature to 60°C or higher,
The mineral acid bath concentration is 2 to 20 wt for nitric acid and 5 to 20 wt for sulfuric acid.
It is preferable to use it in a concentration range of about 30 wt%.

In addition, from an industrial perspective, it is a matter of course to set the temperature in consideration of energy costs, throughput, etc.

The treatment time for immersion treatment depends on the type of acid used,
It is determined by taking into account mineral acid concentration, treatment temperature, amount of dissolved metal selenium, aluminum, and reuse of aluminum drums.In other words, in the case of a 6 wt% nitric acid bath, it is necessary to remove the metal selenium film. 1 to 1.5 at room temperature.
Although it takes several days, the treatment may be carried out for 1 to 2 hours at 80°C. However, at room temperature, the amount of dissolved metal selenium and aluminum is small, and the surface condition of the aluminum drum after peeling off the metal selenium film is good, and it can be reused by crumbling. The amount of metal selenium and aluminum dissolved tends to increase slightly. In addition, the sulfuric acid bath showed the same tendency as the nitric acid bath.

Leather processing time varies depending on concentration and processing temperature. In other words, in a 10 wt% sulfuric acid bath, the treatment time was reduced by 17% when the temperature was 80°C above room temperature, and even at the same temperature of 80°C, 50 wt%
In the case of a sulfuric acid bath, if the treatment is carried out for the same period of time, the amount of metal selenium dissolved increases. moreover.

A similar tendency is observed in the case of hydrochloric acid bath, but the treatment time required to peel off the metal selenium film is the longest. however.

When the hydrochloric acid concentration is high or the processing temperature is high,
Since the amount of dissolved aluminum increases and there is a risk that the hydrogen generated at this time will react with selenium to generate toxic hydrogen selenide, it is preferable to carry out the treatment at a relatively low treatment temperature within the above-mentioned concentration range.

In addition, when a mixed acid bath is used, the treatment time can be greatly reduced as described above.

By processing under such processing conditions, the metal selenium film is completely peeled off, and the peeled flakes, which are mainly in the size range of about 1 to 3 crn angle on average, are formed on the copying drum. It is peeled off from the surface and collected. However, smaller flakes may also be formed and some may dissolve in the mineral acid bath. Therefore, it can be easily separated from the mineral acid bath by placing a fine mesh in the treatment tank or by filtration. After recovery, it can be appropriately post-treated and reused to form a metal selenium film on the aluminum drum surface. Furthermore, the aluminum drum can also be thoroughly cleaned and reused as a copying drum.

Note that in the present invention, before or after heat treatment to roughen the surface of the copying drum, the copying drum is cut into small pieces, or the surface of the copying drum is scratched in a scribe-like manner. Applying the method of the invention or simultaneously using auxiliary means such as applying vibration to the copying drum or stirring the bath during immersion treatment in a mineral acid bath is a means of shortening the processing time. It is effective and there are no problems.

In the present invention, a dry copying drum having a metal selenium film formed on the aluminum drum surface is first heat-treated to roughen the surface, and then immersed in a mineral acid bath, so that the metal selenium can be peeled off. It has the great effect of being able to be recovered in the form of a mineral acid bath, is easy to separate from the mineral acid bath, can be easily reused, can extremely reduce the amount of metal selenium dissolved in the bath, and can also reduce the amount of dissolved aluminum. The amount is extremely small, and it can be washed thoroughly with water to form a metal selenium film and reused as a copying drum. Furthermore, since it is mainly wet processed, there is no release of selenium powder or gas into the air, making it safe for the working environment. Therefore, the equipment is simple, almost no capital investment is required, and the cost per collection is low, and many other effects are recognized.

Next, an example will be described.

Example 1 Aluminum copying drum formed with a metal selenium film that has been used to its service life limit (outer diameter 120 mm, length 340 mm, wall thickness 4 mm; aluminum 1336!P, gold M selenium 432)
) was heat-treated by immersing it in boiling water for 3 hours to roughen the surface of the metal selenium film, and then.

A 6.1 wt% nitric acid bath was used as the mineral acid bath, and the bath temperature was 20.
The immersion treatment was carried out by immersing the roughened copying drum in a bath at a treatment temperature of .degree. As a result, the metal selenium film was peeled off in 37 hours in the form of peeled pieces of 1 g square to 3 crn square. The recovery rate of metallic selenium was 965%. The amount of metallic selenium dissolved in the bath is:

0422, the amount of dissolved aluminum is 32, and the aluminum drum after peeling off the metal selenium is 1
The surface condition was good and it was possible to reuse it as a copying drum.

Example 2 The same procedure as in Example 1 was carried out except that a 6.1 wt% nitric acid bath was used and the treatment temperature was 80°C.The treatment time was 2 hours, and the peeled pieces of metallic selenium were The recovery rate was 80%.

Example 3 A defective dry copying drum at the same manufacturing stage as Example 1 was heat treated at 150°C for 1 hour using an electric furnace to roughen the metal selenium film, and then treated with 25wt% as a mineral acid bath.
(As a result of immersion treatment using an IIFT acid bath at a bath temperature of 70°C, the metal selenium film was peeled off from the entire surface in 20 hours. At this time, the amount of metal selenium dissolved in the bath was 5
2, the amount of aluminum dissolved was 92, and the recovery rate of metal selenium peeled pieces was 884%.

Example 4 A copying drum of the same shape as Example 1, which had been discarded due to scratches on its surface due to misoperation after four months of use, was heated to 170°C using a heating furnace using combustion gas.
After heat treatment for 1 hour for hydration, a mixed bath of 10 wt% nitric acid and 0.36 wt% hydrochloric acid was used as the mineral acid bath, and the mixture was stirred at 100 r, p, m at a treatment temperature of 30°C. The immersion treatment was performed while As a result, the metal selenium film was completely peeled off in 17 hours, and the recovery rate of metal selenium peeled pieces was 92.8%.

Patent applicant: Nippon Light Metal Co., Ltd.

Claims (1)

[Claims] 1) A dry copying drum with a metal selenium film formed on it
Collecting metal selenium from a dry copying drum, characterized in that the metal selenium film is roughened by heat treatment at 00°C and then peeled and recovered from the drum by immersion treatment in a mineral acid bath. Method.