JP3199184B2 - Method for recovering In from Pb-Sn-In alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
More particularly, 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 a Pb-Sn-In alloy. The Pb-
Since the Sn-In alloy has a low melting point, it is widely used as a brazing filler metal for a sputtering target or the like.

Incidentally, since In is an expensive metal and a rare substance, a method of recovering In from various scraps including In has been developed.

Conventionally, various methods have been proposed for 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 resulting 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 of purifying this, or (2) adding a sulfurizing agent to a solution obtained by dissolving the In-containing raw material with sulfuric acid, removing the formed precipitate,
The precipitate obtained by neutralizing the obtained solution is dissolved with hydrochloric acid, a sulfurizing agent is added to the obtained solution again, the pH of the solution after separating the generated sulfide is adjusted, and Zn powder and the like are added. Crude In
Is available. 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 method of collecting.

[0005] In the above-mentioned Pb-Sn-In alloy as well, the amount of scrap increases as the amount of use increases, and therefore, attention has been paid to the recovery and reuse of In from the scrap.

[0006] From the viewpoint of alloy recycling, Pb-Sn
It is most desirable to be able to easily process -In alloy scrap such as remelting. However, since such Pb-Sn-In alloy scrap contains impurities, it is generally impossible to obtain a reusable Pb-Sn-In alloy simply by re-melting and adjusting the composition ratio. It is. Therefore, it can be said that selective recovery of In and addition of the high-purity In metal obtained and generated to the Pb-Sn alloy is optimal for reuse of In.

Further, the above-mentioned 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 at the time of melting. There is. When the dry method is applied, In
Not only Pb but also Pb is volatilized as chloride.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is
Another object of the present invention is to provide a method for separating and recovering In from Sn-In alloy scrap.

[0009]

According to a method of the present invention for solving the above-mentioned problems, a Pb-Sn-In alloy is heated and melted to form a composite, and the temperature of the composite is set to 350 to 500 ° C. It is characterized in that ammonium chloride is allowed to react with the alloy while maintaining, and In in the alloy is separated and collected as dross.

[0010] Further, 0.1 to 1.
The method is characterized in that adding 0% of ammonium chloride to the composite and separating the dross generated is repeated until the grade of In in the composite becomes a desired value or less.

[0011]

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

[0012] Ammonium chloride is used as a chlorine source because ammonium chloride decomposes at 350 to 450 ° C, and ammonia as a decomposition product volatilizes and does not accumulate in the melt.

The reason for setting the melt temperature to 350 to 500 ° C. is 3
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 separation between dross and metal decreases,
This is because the evaporation loss of InCl increases.

The reason why the addition amount of ammonium chloride is 0.1% to 1.0% of the weight of the metal is that if it is less than 0.1%, the amount of dross generated is small and the productivity is reduced. Yes, if it exceeds 1.0%, the amount of dross generated will increase,
This is because the quality of In in the dross is reduced, and the efficiency of the subsequent step of recovering In from the dross is reduced.

When the In grade in the melt decreases, the In grade in the obtained dross may decrease. In this case, the dross can be added to a new Pb-Sn-In composite to provide a dross with high In grade. In this case, the amount of dross to be repeated is 0.1 to
If it is 1.0%, it is not necessary to newly add ammonium chloride.

Considering the efficiency in the recovery of In from the dross in the next step, the In grade in the dross is generally 20%.
% Is preferable. For this reason, it is preferable to adopt a repetitive method rather than performing dross of In at once.

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

[0018]

Next, an embodiment of the present invention will be described.

[0019]

Example 1 250 kg of alloy scrap consisting essentially of 10.7% of In, 54% of Sn, and the balance being substantially Pb was charged into a graphite crucible, and the graphite crucible was placed in 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 thereto, sufficiently stirred, and then allowed to stand. After about one and a half hours, dross formed on the surface was scooped and removed with a ladle. This operation of stirring, standing, and removing 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 integrated bank were examined, and the results are shown in Table 1.

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

Next, the following tests were carried out using the 16th to 24th dross of the obtained dross. That is, Sn4
400% alloy consisting of 3%, 8.5% In and the balance of Pb
The mixture was heated to 0 ° C. to dissolve, the 16th dross was charged, sufficiently stirred, and allowed to stand for 1.5 hours, and then the dross was scooped. Next, the 17th dross was charged, sufficiently stirred, allowed to stand for 1.5 hours, and then scooped up.
This was repeated until the 24th dross. Table 2 shows the obtained analysis values of the even-numbered dross and the integrated financial body and the amount of dross generated.

From Table 2, it can be seen that by repeating the low In grade dross, a high In grade dross can be easily obtained and the In grade in the integrated bank can be reliably reduced.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

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

[0027]

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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-166238 (JP, A) JP-A-53-71623 (JP, A) JP-A-56-169127 (JP, A) JP-A-1- 191753 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C22B 58/00

Claims (2)

(57) [Claims] 1. A Pb—Sn—In alloy is heated and melted to form a composite, and the temperature of the composite is set to 350 to 500 ° C.
A method for recovering In from a Pb-Sn-In alloy, wherein ammonium chloride is caused to react with the alloy while the In is kept in the alloy, and In in the alloy is separated and recovered as dross. 2. 0.1% to 1.0% of the weight of the integrated bank
2. The method according to claim 1, wherein the step of adding ammonium chloride to the alloy and separating the dross produced is repeated until the grade of In in the alloy becomes a desired value or less. A method for recovering In from a Pb-Sn-In alloy.