JPH05247556A - Method for covering in from pb-sn-in alloy - Google Patents

Abstract

PURPOSE:To recover high-purity In from Pb-Sn-In alloy scrap at a high yield by adding ammonia chloride to the melt of the Pb-Sn-In alloy scrap and separating In as InCl dross. CONSTITUTION:The scrap of the Pb-Sn-In alloy is put into a graphite crucible and is melted in an electric furnace. While this scrap melt is maintained in a 350 to 500 deg.C range, NH4Cl is added at 0.1 to 1.0wt.% ratio to the melt and the melt is stirred. The In the molten scrap floats as dross on the surface of the molten alloy. This treatment is repeated and continued until the In content in the molten alloy decreases to a desired value or below and until the grater part of the In the molten alloy turns to the dross. Concd. hydrochloric acid and water are added to the resultant dross and the dross is stirred and dissolved. The hydrochloric acid liquid contg. the dissolved In is filtered and separated from the undissolved matter and an NaOH soln. is added thereto. The generated precipitate is removed and thereafter, Zn powder is added thereto to precipitate the high-purity In. This In is separated and recovered.

Description

Detailed Description of the Invention

[0001]

The present invention relates to In from In-containing materials.
The present invention relates to a method for recovering In from a Pb-Sn-In alloy containing Pb, Sn, and In as main components.

[0002]

2. Description of the Related Art In is mainly produced as a by-product in zinc smelting, and is used as various alloy materials such as Pb-Sn-In alloy. Pb-
Since the Sn-In alloy has a low melting point, it is widely used as a brazing material for bonding such as a sputtering target.

By the way, since In is an expensive metal and is a rare substance, a method for recovering In from various scraps containing In has been developed.

Conventionally, various methods have been proposed as a method of recovering In from an In-containing raw material. In the wet method,
For example, (1) In-containing raw material is dissolved with sulfuric acid, neutralized with alkali hydroxide, the formed precipitate is redissolved with sulfuric acid, and a reducing agent such as Zn powder is added to the obtained solution to obtain crude In. , A method for purifying it, or (2) adding a sulfiding agent to a solution obtained by dissolving an In-containing raw material with sulfuric acid to remove the formed precipitate,
The precipitate obtained by neutralizing the obtained solution was dissolved with hydrochloric acid, the sulfiding agent was added again to the obtained solution, the pH of the solution after separating the produced sulfide was adjusted, and Zn powder and the like were added. Crude In obtained
There is a method of purifying. In the dry method, an In-containing raw material is mixed with a chlorinating agent and heated to volatilize In as a chloride,
There is a way to collect it.

In the above Pb-Sn-In alloy as well, since the amount of scrap increases with the increase in the amount used, the recovery and reuse of In from the scrap has been drawing attention.

From the viewpoint of alloy reuse, Pb-Sn
It is most desirable to be able to easily process the In alloy scrap such as remelting. However, since such a Pb-Sn-In alloy scrap contains impurities, it is generally impossible to obtain a reusable Pb-Sn-In alloy only by remelting and adjusting the composition ratio. Is. Therefore, it can be said that it is optimum for reuse of In to selectively collect In and add the high-purity In metal obtained by the generation to the Pb-Sn alloy.

Further, the wet method is relatively complicated,
When the wet method is applied to the Pb-Sn-In alloy which is the object of the present invention, sulfuric acid or hydrochloric acid is used during melting, so that a precipitate such as lead sulfate or lead chloride is formed on the surface of the raw material to make the raw material insoluble. There is. When the dry method is applied, In
Not only Pb but also volatilize as chlorides.

[0008]

The object of the present invention is to provide Pb
-Providing a method for separating and recovering In from Sn-In alloy scrap.

[0009]

According to the method of the present invention for solving the above problems, a Pb-Sn-In alloy is heated and melted to form a joint financial body, and the temperature of the joint financial body is adjusted to 350 to 500 ° C. It is characterized by reacting ammonium chloride with the financial instrument while maintaining it, and separating and collecting In in the financial instrument as dross.

In addition, 0.1 to 1.
The method is characterized in that 0% ammonium chloride is added to the financial instrument, and the dross produced is separated until the In grade in the financial instrument falls below a desired value.

[0011]

According to the method of the present invention, Pb and S which are alloy constituent elements are used.
This utilizes the difference in affinity between n, In and chlorine.
That is, since In has a greater affinity than Pb and Sn, when chlorine acts on the melt of the Pb-Sn-In alloy, it becomes InCl, which is separated as dross and floats on the surface of the melt.

Ammonium chloride is used as the chlorine source because ammonium chloride decomposes at 350 to 450 ° C. and the decomposition product, ammonia, volatilizes and does not accumulate in the melt.

It is 3 that the melt temperature is 350 to 500 ° C.
This is because if the temperature is lower than 50 ° C., the fluidity of the melt is low and the contact and reaction between ammonium chloride and In become insufficient.
If the temperature exceeds 0 ° C, the separability between dross and metal will decrease,
This is because InCl has a large volatilization loss.

The amount of ammonium chloride added is set to 0.1% to 1.0% of the weight of metal because if it is less than 0.1%, the amount of dross generated is small and the productivity is lowered. Yes, if it exceeds 1.0%, the amount of generated dross increases,
This is because the In quality in the dross is lowered and the efficiency in the In recovery process from the dross in the next step is lowered.

When the In grade in the melt is lowered, the In grade in the obtained dross may be lowered. In this case, the dross can be added to a new Pb-Sn-In compound financial body to form a dros with a high In quality. In this case, the amount of repeating dross is 0.1 to 10% by weight of the melt.
If it is 1.0%, it is not necessary to newly add ammonium chloride.

Considering the efficiency of recovering In from the dross in the next step, the In quality in the dross is generally 20.
% Or more is preferable. For this reason, it is preferable to adopt a repeating method for converting In to dross at once.

In can be recovered from the dross by an ordinary method, for example, by dissolving in excess hydrochloric acid, adjusting the pH to about 1 with an alkali, precipitating Pb and a trace amount of Sn, and separating them. A reducing agent such as Zn powder is added to the solution to precipitate In. The In powder thus obtained is mixed with caustic soda and dissolved to obtain an In ingot.
The In thus obtained has a high purity and can be used as it is as an additive for alloys.

[0018]

EXAMPLES Next, examples of the present invention will be described.

[0019]

Example 1 250 kg of alloy scrap consisting of In of 10.7%, Sn of 54% and the balance substantially of Pb was charged into a graphite crucible, and the graphite crucible was put into an electric furnace and heated and melted at 400 ° C.

After confirming that the scrap was completely dissolved, 1.5 kg of ammonium chloride was added, stirred thoroughly, and then allowed to stand. After about one and a half hours, the dross formed on the surface was removed by scooping with a ladle. Then, this stirring-stationary-removal operation was performed 24 times. The amount of dross obtained every even number of times and the quality of In, Sn and Pb,
The grades of In, Sn, and Pb of the joint financial body were examined, and the results are shown in Table 1.

From Table 1, it can be seen that In
Although the quality deteriorates, the In quality of dross up to the 14th time is 20% or more. In addition, In
It can be seen that 22 times of repetition are necessary to reduce the quality to 1% or less.

Next, the following tests were carried out using the dross obtained 16th to 24th times. That is, Sn4
400% alloy containing 3%, In8.5% and the balance Pb
The mixture was heated to 0 ° C. to dissolve it, the 16th dross was added, the mixture was thoroughly stirred, and allowed to stand for 1.5 hours, and then the dross was scooped. Then, the 17th dross was added, thoroughly stirred and allowed to stand for 1.5 hours, and then the dross was scooped.
This was repeated until the 24th dross. Table 2 shows the analysis values and the amount of generated dross of the obtained even-numbered dross and the financial institutions.

From Table 2, it can be seen that by repeating the dross having a low In quality, it is possible to easily obtain the dross having a high In quality and surely reduce the In quality in the financial instrument.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

Example 2 1.5 kg of dross obtained by mixing the dross from the first time to the fourth time in Example 1 was added to 50 l of concentrated hydrochloric acid.
And water were added and dissolved by stirring at room temperature. Then
The undissolved substance was separated by filtration to obtain 146 l of filtrate. A 20% caustic soda solution was added to the filtrate to adjust the pH to 1.5. The formed precipitate was separated and removed, and the obtained solution was purified to a purity of 9
1 equivalent of zinc powder of 9.2% (purity of metal Zn 97.3%) was added with stirring to precipitate In. The obtained In powder and 0.4 kg of NaOH were put into a stainless steel boat and melted by heating to obtain 6.7 kg of indium ingot having a purity of 99.6%.

[0027]

As described above, according to the method of the present invention, In can be separated easily and reliably from the Pb-Sn-In alloy scrap as dross, and In having a higher purity than the obtained dross can be easily obtained. Can be obtained.

Claims (2)

[Claims] 1. A Pb-Sn-In alloy is heated and melted to form a combined financial body, and the temperature of the combined financial body is 350 to 500.degree.
A method for recovering In from a Pb-Sn-In alloy, characterized in that ammonium chloride is allowed to react with the financial instrument while maintaining the above, and In in the financial instrument is separated and recovered as dross. 2. 0.1 to 1.0% of the weight of the financial institution
2. The method according to claim 1, wherein the ammonium chloride is added to the financial instrument and the dross formed is separated until the In grade in the financial instrument falls below a desired value. A method for recovering In from a Pb-Sn-In alloy.