JPS6024331A - Treatment of scrap of iii-v group compound semiconductor - Google Patents

Abstract

PURPOSE:To recover easily metallic In in a high yield from scraps of InP as a III-V group compound semiconductor by treating the scraps with an alkali metallic hydroxide. CONSTITUTION:Scraps of InP as a III-V group compound semiconductor are ground and reacted with a molten alkali metallic hydroxide such as molten KOH or NaOH in a vessel. The scraps contain scarcely compound semiconductors other than InP. Only metallic In accumulated on the bottom of the vessel is separated. By this method, metallic In is easily recovered in a high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering In, which is a valuable material, from scrap whose main component is -Q + -nP of an m-v group compound semiconductor.

The manufacturing process of devices using m-v group compound semiconductors includes (
1) Group IIl (Al-Ga・N), Group V (p-As-
Synthesis of compounds from raw material elements such as sb), (2) Production of single crystals from the synthesized compounds, (3) Processing such as cutting and polishing eggs from single crystals, (4) Elements on the surface of processed single crystals. Although there are steps such as preparation, the product yield in these steps is low, and generally around 90% of the raw materials used are a loss in the process. The scrap produced in these processes contains Ga.
Large amounts of expensive rare elements such as In are contained mainly in the form of compound semiconductors, and recovering these valuables has important meaning in terms of economic efficiency and effective use of resources.

The present invention occurs particularly in the process of manufacturing and processing InP. From scrap mainly composed of industrial nP, the valuable In
The aim is to safely recover the substances in a high yield.

Several methods have already been proposed for recovering Ga from GaAe, which is an m-v group compound semiconductor like nP. Of these processing methods.

Examples of methods that can be applied to the In recovery method from InP include (
There are two methods: 1) thermal decomposition method and (2) wet processing method.

However, when InP is treated by the thermal decomposition method in (1), the phosphorus component evaporates as a hot vapor, and when it is cooled, it releases toxic and pyrophoric yellow phosphorus, making the treatment difficult. It is extremely dangerous and difficult to create and operate the device. on the other hand,
As a result of the inventors' own study regarding the wet treatment in (2), it was found that extremely concentrated acids and strong oxidizing chemicals were used in a large excess amount relative to the wet treatment process, as the reactivity of the engineering nP and acid was small. It turned out that it was necessary to use. As described above, it is technically difficult to recover NF from a leachate containing a large amount of acids relative to In, but there is a problem in terms of economy.

As a result of repeated studies to improve the above-mentioned points, the inventors discovered a reaction in which phosphor nP is decomposed by the action of a molten alkali metal hydroxide, thereby liberating kinko-n. The present invention uses nP scrap using a processing method using molten alkali.

This method is characterized by safely, economically, and in a high yield, recovering the methane in a fully flexed state.

Next, the processing method and conditions will be explained.

■As a molten alkali used for decomposing nP.

Alkali metal hydroxides such as NaOH and KOH and other inorganic salts can be used to lower the melting point and to promote or control the reaction.

N,a due to being cheap and easy to obtain
O11 is suitable. As a result of experiments, it was found that the reaction of nP by molten NaOH was of the first order type.

2 nP + 10 NaOH-> 2 In+ 21
1a3PO4+ 2 Na2O+ 5 I(2-・-(
1) As long as the conditions described below (InP particle size, addition method, temperature, etc.) are observed, there will be almost no side reactions, and yellow phosphorus and
No toxic substances such as hydrogen phosphide were produced. Na3Po is generated as the reaction progresses.

Therefore, the viscosity of the melt increases, making mixing and stirring difficult.
Since V is generated and the reaction is hindered, it is necessary to use an alkali in excess of the theoretically required amount.

For example, in the case of NaOH, it is preferable to use 1.5 to 4 times the theoretical equivalent.

The scrap that is subject to treatment with molten alkali is
As long as the main component is P"f, its form can be in the form of lumps or powder. Impurities that are mixed into ordinary engineering nP scrap include inorganic substances such as graphite, ceracola, quartz, and glass, and wax.・There are organic substances such as cutting oil.

These are either decomposed by molten alkali treatment and dissolved into alkali scum, or remain unreacted and insoluble in the metal In, so they can be easily separated from the recovered In.
When there are many foreign substances other than nP, it is preferable to remove the foreign substances by pretreatment.

In order to facilitate two reactions during processing.

Crush engineering nP scrap. The grains are 16 mesh (1
) If it is orange below, it can be processed without any problem.

When the treatment temperature is raised, the 1nP decomposition reaction becomes faster, but the dissolution reaction of metal In into alkali also becomes faster, so the recovery rate of In decreases. The reaction temperature is suitably higher than the melting point of NaOH, preferably around 380°C (670-400°C).

(2) When reacting nP powder with an alkali, if both are mixed in their entire amounts from the beginning and then heated and melted, the temperature will rise rapidly due to the heat of reaction and an extremely violent reaction will occur. Therefore, in the treatment, it is preferable to add the nP powder to the pre-molten alkali according to the decomposition rate. In
The P addition rate needs to be adjusted depending on the InP particle size, processing temperature, reaction vessel size, heat dissipation rate, etc.

FIG. 1 shows an example of an apparatus for treating nP scrap with molten alkali according to the present invention. In the figure, 1 is a reaction vessel, and 2 is an impeller for agitating the solution. These are made of iron or stainless steel, taking into account the side effects of molten alkali. Alkaline 3.

Place it in container 1 in advance and heat it to 380℃ in an electric furnace.
Heating and melting. While stirring the molten alkali, using the addition funnel (No. 4), add the powder 7 of KonP while controlling the temperature.

The processing apparatus is covered with a lid 5 to prevent alkali droplets from scattering, and the entire apparatus is evacuated to remove H2 gas. 6
is an exhaust port.

The overall processing flow is shown in Figure 2. The scrap to be treated is pulverized and then sieved to have a diameter of 1 or less, and then subjected to molten alkali treatment using the above-mentioned apparatus. After the molten alkali treatment, metal In accumulated at the bottom of the container can be poured out by tilting the container while it is still hot, or it can be sufficiently cooled and then leached with water to wash away alkali scum and foreign substances other than In. Heat to melt and take out. The recovery rate of In in the fully bent state is up to 9% compared to the In in the raw material scrap.
Reach sections 8-99. When pure InP powder is decomposed, one recovered In contains a very small amount of Na and F'e contaminated from the container.
It is approximately 99.9% pure.

Less than 2% of the In in the raw material is dissolved in the alkali scum. When the alkali scum water leachate is neutralized to pH 6 to 8, this In content becomes a hydroxide and precipitates, and is easily recovered. Even if unreacted InP fine powder is mixed into the scum, it is caught up in the gel-like precipitate of In hydroxide by neutralization and easily separated from the liquid.

The recovered metal work is 9 normal metal work n manufacturing process 9 e.g. I
By returning it to the electrolytic refining process, it can be easily measured and regenerated to a purity (99,991 or higher) that is acceptable for industrial use.

In addition, the In-containing precipitate recovered from the scum is dissolved and leached with dilute mineral acid.

It can be used as a raw material for In wet manufacturing process.

As described above, according to the present invention, compound semiconductor scrap containing nP as a main component can be safely manufactured with high yield.
Most can be recovered in metal form.

Finally, the present invention will be explained by examples.

Example 1 Stainless steel 'J 100 me beaker (5011JX
At 70h), 3Of NaOH was taken, placed in an electric furnace, and heated and melted. The temperature of the solution was set to 380°C, and the mixture was ground to 16 to 32 meshes (1 to 0.5 wn) with constant stirring.
Sieved engineering nP powder10. The mixture was added over a period of 50 minutes, and heated and stirred for another 20 minutes after the addition, and then the beaker was taken out and allowed to cool. The alkali scum was dissolved and removed with water, and the metal In accumulated at the bottom of the beaker was taken out. Almost no unreacted InP was observed. The amount of Kinkuko n recovered was 17 to 789, and the recovery rate with respect to the reacted fnP was 99 or higher. The results of the luminescence qualitative analysis of the recovered metal In were as shown in Table 1.

The In dissolved in the scum is 2% of the total In in the raw material.
These techniques reduce the scum exudate to a pH of 6 to 8.
When neutralized, all precipitated and was completely recovered.

Example 2 100 tons of scrap from the nP single crystal cutting process (less than 100 mesh, nP content 91%) containing impurities such as graphite, ceracola, and wax were prepared. 50
0 me stainless steel beaker (80t15X130h)
Next, take 300f of NaOH, heat and melt it in an electric furnace,
While stirring at a temperature of 380° C., the above scrap powder was added over 60 minutes, and the reaction was further allowed to occur for 20 minutes after the addition. After cooling, alkali scum and unreacted powder were removed by washing with water, and metal In71.1f was recovered (recovery rate: 99).

The results of the luminescence qualitative analysis of the recovered metal In were as shown in Table 1.

Table 1 0: Not recognized 1: Very weakly recognized 2:
Weakly recognized 3: Clearly recognized 4: Strongly recognized 5: Very strongly recognized

[Brief explanation of drawings]

Figure 1 shows an example of equipment for molten alkali treatment. FIG. 2 shows the overall processing flow. Patent applicant Nippon Komou Co., Ltd. Agent Patent attorney (7569) Keishi Namikawa September 76, 1980 Commissioner of the Patent Office Kazuo Wakasugi Tono 1 Case description 8 Showa year patent application No. 130'993゜3, Amended Patent applicant address: 2-10-1 Toranomon, Minato-ku, Tokyo Name: Japan Mining Co., Ltd. Representative: Yukio Kasahara 4, agent: 105 Phone: 582-2111 Address: Tokyo Minato Toranomon 2-10-1-7, ? f
g Correct contents (1) In the 9th line of page 7 of the specification, amend "Only containing Fe" to "Only containing Fe."that's all

Claims (1)

[Claims] When recovering FE as a valuable resource from m-v group compound semiconductor scrap, which is mainly composed of InP and contains almost no compound semiconductors other than InP, it is recommended to treat the scrap with molten alkali metal hydroxide. A method for processing m-v group compound semiconductor scrap characterized by: