JPS6027613A - Recovery of indium-gallium - Google Patents

Abstract

PURPOSE:To recover a valuable In.Ga safely, in high yield, from an In alloy scrap containing III-group and V-group elements, by treating the scrap with molten alkali metal hydroxide. CONSTITUTION:An In alloy scrap composed mainly of In and containing III- group and V-group elements such as Ga, As, P, etc. as alloy components is treated with molten alkali metal hydroxide to effect the separation and recovery of Ga from the alloy. When the liquid-phase epitaxial growth scrap composed mainly of indium is treated with molten alkali, a part of the unreacted compound semiconductor powder is suspended in the form of fine powder in the alkali scum, and the remaining part thereof is left in the form attached to the crude In. The fine powder of the compound semiconductor dissolved or suspended in the scum and the component (Ga.In) are precipitated together with gallium hydroxide precipitate and recovered in the recovery of Ga by neutralizing the leached liquid of the scum.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for forming GaAs-GaP as a main component and Ga as an alloy component, or GaAs-GaP as an alloy component.
In contained as a mixture of compound semiconductors such as P
The present invention relates to a method for recovering n*Ga, which is a valuable material, from alloy scrap.

In is used as a solvent for liquid phase epitaxial growth (Lpg) of ternary and quaternary m-v group compound semiconductors such as GagIn, -rAsyP, and -y. Most of the In will be scrapped. Usually, this LPEt scrap is an alloy whose main component is In and contains Gat-(101~2).
In the As-P table, approximately 0.01 to 14 group V elements are added, mainly in the form of a group IV compound semiconductor.

In-Ga is an expensive rare element, and it is important to economically recover these valuables using high-yield vehicles.

An object of the present invention is to safely separate and recover In-Ga, which is a valuable material, from the above-mentioned LPIn scrap at a high yield.

The process of recovering valuables from LPE scrap includes (
There are steps such as a) decomposition of the 1t-v group compound semiconductor contained, (b) separation of n and Ga, and (C) recovery of nia. Among these, (a) In-Ga recovery is as follows: (a) (b)
), it is sufficient that In-Ga can be recovered in a form that can be returned to the In-Ga production process.

The method for decomposing the compound semiconductor (a) is (1) thermal decomposition method, which is a conventional method for processing GaAθ scrap.

(11) Wet processing methods can generally be applied, but since the compound semiconductor scrap content in LPE scrap is small, the above (i) (it
Both of the above methods are inappropriate, and it is more advantageous to separate the compound semiconductor portion and the alloy portion through some pretreatment and then decompose only the collected semiconductor portion. Furthermore, even if only the semiconductor part is separated and decomposed, in the thermal decomposition method (1), the As-P component of the compound semiconductor will volatilize and condense, producing toxic and pyrophoric yellow phosphorus and yellow arsenic. Processing operations are dangerous. In addition, in the wet processing method (+1), it is generally necessary to perform leaching treatment using a large excess of concentrated sulfuric acid or an oxidizing reagent for the compound semiconductor.
In-Ga from the leachate containing a large amount of acids
Recovering Ga in a form that can be returned to the process is difficult.

Regarding the separation of In and Ga in (b), ordinary wet separation methods9 such as solvent extraction and ion exchange methods can be applied, but in order to separate Ga, which is contained in a small amount relative to n, it is necessary to Melting is uneconomical.

The present invention is a method that overcomes the drawbacks of the above-mentioned conventional techniques. (1) Separation of In and Ga using the difference in reactivity to molten alkali; (2) Separation of In alloy and compound semiconductor using an additional process of melt filtration; ■By combining five methods of decomposing compound semiconductors using molten alkali containing an oxidizing agent,
The purpose is to separate and recover n-Ga from LPE scrap.

Next, the methods and conditions of each invention will be explained.

First, the invention described in claim 1 will be described.

It is said that In-Ga reacts with molten alkali to remove alkali scum. For example, it is said that reactions expressed by equations (1) and (2) occur with respect to molten NaOH.

2Ga+6NaOH-+ 2Na, Ga01+5H,-
-------(1) 2nd n + 6NaOH-+ 2Na3nd n03+3H1- (2) As a result of the inventors' studies under various conditions, it was found that there is a large difference in the reaction rate between equations (1) and (2). Yes, the reaction of Ga dissolution in (l) is fast, but I in (2)
n dissolution was found to be relatively slow. For this reason, In
If an alloy of and Ga is melted and an alkali is applied to it, then G
a is selectively dissolved in alkali, and the Ga content in the alloy decreases.

Separation of In and Ga is possible. On the other hand, Ga dissolved in the alkali scum is easily recovered by leaching the scum with water and neutralizing the solution, which precipitates as gallium hydroxide. Therefore, by this method, L containing indium as the main component
Ga in PE scrap can be easily separated and Xn can be recovered as a crude metal.

As a result of various studies, it was found that among the compound semiconductors contained in LPB scrap whose main component is indium, nP
It was found that metal In was decomposed by the action of molten alkali to liberate metal In. For example, NaOH was m-. In this case, this reaction is expressed by the following formula:

2nP + 1ONaOH- + 2In + 2Na3P
O, + 2Na, O+ 5H, -+31 while other i-
Group V compound semiconductors have poor reactivity compared to InP,
It was found that some of it decomposed and dissolved into scum, but the majority remained unreacted. When scrap is treated with molten alkali to produce LP' containing indium as a main component, some of the unreacted compound semiconductor powder becomes fine powder and is suspended in the alkali scum, and the rest remains attached to the crude In. Compound semiconductor fine powder and components (Ga,
In), when neutralizing the scum leachate and recovering Ga,
It precipitates together with gallium hydroxide and is recovered.

As an alkali used for molten alkali treatment.

Alkali metal hydroxides such as Na0H-KOH and other inorganic salts added to them to lower the melting point and accelerate the reaction can be used, but from the point of view of price, NaOH
is appropriate.

In the treatment using NaOH, if the temperature of the melt is equal to or higher than the melting point of IJaOH, a Ga dissolution reaction from the scrap occurs. The higher the temperature, the faster the Ga removal rate, but at the same time the amount of In dissolved in the alkali increases, so it is disadvantageous to use an extremely high temperature.9 The reaction temperature is 350 to 400.
C., preferably around 380.degree. C. is suitable.

The amount of alkali used needs to be adjusted depending on the Ga content in the scrap, but when using Na0Ei, the amount of alkali used is 10 to 15 times the total Ga content in the scrap (for the reaction of equation (1)). It is sufficient if 5.8 to a7 times equivalent) is used. However, it is necessary to use a sufficient amount of alkali to completely cover the surface of the scrap melted in the zero reaction vessel, so even if the Ga content in the scrap is small, it is necessary to use at least NaOH in an amount of about 10 times the total amount of scrap. be.

An example of an apparatus for molten alkali treatment is shown in FIG. Figure 1
2 is a reaction vessel, and 2 is an impeller for stirring the solution, which are made of iron or stainless steel in consideration of corrosion resistance to molten alkali. Alkali 3 and scrap 4 are placed in a container and heated and melted at about 380°C in an electric furnace. The processing equipment.

It is covered with a lid 5 to prevent alkali droplets from scattering, and the whole is exhausted from an exhaust port 6 to remove mist, H, and gas. The reaction time needs to be adjusted depending on the Ga content in the scrap before treatment and the size of the reaction vessel, but the loss of In dissolution into alkali can be 0.1 if the temperature, amount of chemicals used, and reaction time are selected correctly. Stay below the relevant level.

After the treatment, the In that has accumulated at the bottom of the container is poured out by tilting it into the container while it is still hot, or it is sufficiently cooled and water is leached out to dissolve the scum, and then heated to take out the metal In.

In.Gafi mixed in the scum is recovered by water leaching, neutralization, and filtration operations.

Next, the invention described in claim 2 will be described.

The present inventors found that when In alloy scrap containing In as a main component and As and P in the form of an m-v group compound semiconductor was melted, As and P were mostly present in the residue floating on the surface of the melt. It was found that the

Therefore, P-As included in LPΣ scrap is In
It is hardly dissolved in metal, and most of it is In and Ga.
It was found that the compound semiconductor particles, which have a specific gravity smaller than that of metal In, are precipitated on the surface layer. Therefore, L
If PIn scrap is melted and maintained near its melting point and filtered through pores in the container wall, most of the P・A8 contained in the scrap will be removed in the form of compound semiconductor fine powder, and PIn
-A metallic In or In-Ga alloy that does not contain Aθ can be obtained. The p-filtration operation can be applied to both (1) IIpB scrap raw material and (il) rough material obtained by removing Ga from LEE scrap by molten alkali treatment.

The container for melt filtration is preferably made of a material that easily reacts with molten indium, such as glass, quartz, or stainless steel, and has one or more holes with a diameter of 0.1 to 14 in the bottom surface.

Finally, the invention described in claim 6 will be described.

By using a molten alkali containing an oxidizing agent (hereinafter also referred to as oxidizing molten alkali), it is possible to easily decompose a group IV compound semiconductor that is difficult to decompose using a molten alkali alone.

As an oxidizing agent.

Most materials that can be mixed with molten alkali can be used; for example, when RaOH is used as the alkali, sodium nitrite NaN01 is useful. Na
If an OH-based oxidizing flux is used.

All the components in the compound semiconductor are dissolved into the alkali scum by the following reaction.

InP + bhoH+ 4(o) Na1InOB
+Na5PO, +3H10-=・(41GaAs +
61iaO) I+ 4(0) → Na, GaO, +Na1
AeO, -14) 1,0=-=- (5) Metal In also easily dissolves in oxidizing molten alkali.

2nd + 6 NaOH+ 3(0) → 2Nal
O@+3H! O-(6) Therefore, the mixture of metal In and compound semiconductor powder residue obtained by the melt filtration treatment described in (1) is easily dissolved into scum by the oxidizing alkali.

Among the components dissolved in the scum, Ga and In precipitate as hydroxides when the scum water leachate is neutralized and are easily separated and separated.
It will be collected. Collect nine precipitates.

It is possible to separate and recover Ga.In by a normal wet method.

The amount of reagent used in the treatment varies depending on the composition of the scrap, but it is necessary to use two to three times the theoretically required amount of both the alkali and the oxidizing agent. When using a NaOH-NaMO1 mixture, sufficient decomposition can be achieved by using a 5:1 mixture of MaOH and Nano by 10 times the weight of the scrap.

If the temperature is above the melting point of the alkali, the reactions (4) to (6) will proceed smoothly, but if the temperature is above 450°C, there will be problems with the corrosion resistance of the container, and the reaction will be violent and cause danger. It is preferable to decompose at extremely high temperatures. Na0
In the case of H-Nano.

It is safe to process at a temperature in the range of 350 to 400°C.

The scrap to be processed is to facilitate the reaction.

It is preferable to pulverize and shred the metal In and compound semiconductor powder, and it is sufficient to make the mixture of metal In and compound semiconductor powder into a size similar to that of bedding.

For the treatment with oxidizing molten alkali, the same type of equipment as that used for the molten alkali treatment described in the description of the company's first invention can be used, except that it is provided with a raw material scrap charging port 4. An example of this is shown in FIG.

In the figure, 1 is a reaction vessel, 2 is an impeller for stirring the solution, and these are made of iron or stainless steel in consideration of corrosion resistance. The alkali and oxidizing agent are placed in a container 1 in advance, and the whole is heated and melted in an electric furnace. While stirring the molten alkali, add scrap 7 using addition funnel 4. At this time, in order to prevent a sudden force reaction, it is preferable to add scrap little by little and adjust the temperature of the solution to be maintained at 400° C. or less. The processing device is covered with a lid 5 to prevent alkali droplets from scattering, and gas and mist are exhausted from an exhaust port 6.

If there is an excess of reagent, the decomposition reaction will be completed within 30 minutes after the end of scrap addition. After the reaction, the whole is allowed to cool and the scum is leached with water. Ga is.

In is completely dissolved as gallium ion, and In is partially dissolved in water and also suspended in Obe Kosha hydroxide solution. When the leachate is neutralized to a pH of 6 to 8, the Ga dissolved and suspended in the liquid becomes hydroxide and almost completely precipitates. The ν solution after separating the precipitate is subjected to a Mu θ removal treatment by a known method and then discarded.

I decided to combine the above three inventions.

Separation of valuables (Ga, In) from LPFi scrap
It can be recovered. An example of this processing flow is shown in FIG. Here, we have shown an example in which first Ga is removed from the alloy by the molten alkali treatment (■), and then the compound semiconductor component is separated by filtration (2). It is also possible to treat the alloy from which the P content has been removed with molten alkali. In addition, if the content of the compound semiconductor component is extremely small, it may be possible to perform only steps (1) and (2).

Finally, the present invention will be explained by examples.

Example 1 In a stainless steel 100-beaker (sogx7oh), alloy 200f of n99qb-Ga21 and 1/i ~ 32
The mesh (1 to 0.5 pieces) is crushed GaAs +
Mix and take 19 pieces of P powder, and add 50f of NaOH (Ga
7.3 times equivalent) and heated the whole thing in an electric furnace at 380°C.
The contents were melted and stirred for 3 hours. Engineering nP 4
7'1. 57% of the GaAe was mainly mixed into the fine suspension and the alkali scum, and the remaining nP-GaAs remained attached to the alloy surface after treatment. The Ga content in the alloy after treatment decreased by 0.021i or less. In the recovered In obtained by filtering the treated alloy to remove surface powder, no P was detected by qualitative luminescence analysis, and the presence of As was barely recognized.

The scum water leachate was neutralized to pH 7, and the G dissolved in the liquid was
a was precipitated. The amount of In-Ga dissolved in the solution after neutralization is 1
Less than ppm, In-
Ga content was completely precipitated. The precipitate was leached out using 371 HOI, leaving the unreacted compound semiconductor powder behind.
The hydroxide was dissolved and recovered.

The amount of n dissolved into the scum was 110q, and the In loss rate from scrap of 1 yuan was α055qb.

Example 2 A stainless steel 100mm beaker (50cm x 70h) was heated with a rabbit OH15f, Halo, and a 5ft electric furnace.
It was heated to 0°C to melt. cL5~ without stirring the solution
1 ton of sample was added and reacted for 30 minutes. The processed sample is (1
)1nF, (ii) Ga'F, (iii) I
nAs, (iv) GaAs powder (16 to 52 mesh), and (v) metal In and metal nP powder mixture. All samples were completely decomposed, the scum water leachate was neutralized, and Ga.In was recovered as hydroxide. The recovery rate was as shown in Table 1.

Table 1

[Brief explanation of drawings]

Figure 1 shows an example of an apparatus for treating molten alkali, and Figure 2 shows an example of an apparatus for treating oxidizing molten alkali. FIG. 3 shows the overall processing flow. Patent applicant: Japan Mining Co., Ltd. Patent attorney (7569) Keishi Namikawa September 1980 Z Patent Office Commissioner Kazuo Wakasugi 1. Case description 1982 Patent application No. 130j95 2. Name of the invention Indium gallium Recovery method 3 Relationship with the case of the person making the amendment Patent applicant address 2-10-1 Toranomon, Minato-ku, Tokyo Name Nippon Mining Co., Ltd. Representative Yukio Kasahara 4 Agent 105 Telephone 582-2111 Address Location: 2-10-1 Toranomon, Minato-ku, Tokyo Contents of the Z amendment (1) On page 3, line 7 of the specification, “(a) In-Ga recovery” is changed to “(C) In-Ga recovery” and correct it. (2) On page 14, line 9 of the specification, "ke shattered" is amended to "ke shattered". (3) Change “addition” in line 1o on page 14 of the specification to “addition J
and correct it. that's all

Claims (2)

[Claims] (1) In containing In as a main component and containing Group V elements such as Ga, A, and P as alloy components or mixtures.
From alloy scrap, In・Ga tl-
During recovery, the scrap is treated with molten alkali metal hydroxide to separate ()a1 from the alloy.
A method for recovering indium and gallium. (2) In separating the ks-P containing component from the In alloy scrap containing In as a main component and As-P in the form of a lin-V group compound semiconductor, M scrap is treated in a molten state. How to recover indium and gallium. (s) In-G as valuable material from compound semiconductor scrap whose main components are I-V compound semiconductors and metal In.
a11- A method for recovering indium-gallium, which comprises treating the scrap with a molten alkali metal hydroxide containing an oxidizing agent.