JPS6176627A - Recoverying method of callium - Google Patents

Abstract

PURPOSE:To recover Ga by dry process easily by a simple stage without generating any waste water contg. toxic substances such as arsenic, by decomposing arsenides and/or phosphides of Ga by means of heating in an inert atmosphere, and by recovering the residual Ga. CONSTITUTION:Arsenides and/or phosphides of Ga are decomposed by heating in an inert atmosphere composed of gases such as N2 or the like. And the resulting decomposition products are separated severally as simple substances to be recovered: especially Ga is recovered by a simple process. In this case, when N2 is used as an inert gas, the use of extreme high purity N2 gas is preferred; >=99.999% purity, <=0.5ppm O2 content. And further, the heating temp. is necessarily higher than the temp. at which GaAs or GaP can be decomposed. Namely, when the substance to be decomposed is arsenide of Ga, the temp. range is preferably 750-150 deg.C; in case of phosphide of Ga, 550-1,500 deg.C. As and P as decomposition products can be condensed and collected at a prescribed section.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for recovering gallium from gallium arsenide and/or phosphide.

(Prior art) Gallium is an extremely important metal as a raw material for electronic materials, but there are no ores that contain abundant gallium, and industrial production methods include, for example, gi-xite ore containing a small amount of gallium. There is only a method of recovering alumina from the so-called Bayer one-step liquid, which produces more alumina. Since there is no ore rich in gallium, the waste generated when processing crystalline materials such as GaP and GaAs into electronic material elements is also an extremely valuable resource.

These gallium wastes are increasing year by year with the development of the electronic industry, and many techniques for recovering gallium from wastes have been proposed.

For example, as a method for recovering gallium from waste,
There is a method described in Japanese Patent No. 6-38661. This method uses waste containing gallium.

That is, a composition containing gallium, such as an intermetallic compound consisting of gallium and a group VB element, is prepared in the presence of an oxidizing agent.

After dissolving in an acidic or basic solution, adjusting the pH to precipitate the gallium component, separating the precipitate, then dissolving these separated substances in an alkaline solution, and recovering gallium by electrolyzing this. be. In this case, precipitates often form in the kale, and in this case, it is necessary to maintain the precipitates under heating and ripen them as described in column 4, lines 13 to 20 of the above-mentioned publication. Separation of precipitates is done by sedimentation, filtration,
It is said that this can be done by known means such as centrifugation. This process involves lysis, neutralization, and gel separation.

Since it requires a large number of steps such as electrolysis and a cell separation step, it requires extensive equipment and is extremely complicated in terms of work.

Furthermore, when GaAs is treated with this method, when dissolved in an acidic or basic solution in the presence of an oxidizing agent, arsenic becomes an oxide and is eluted into the solution, resulting in the generation of arsenic-containing wastewater. .

Arsenic is stipulated by the Water Pollution Control Law to be within the wastewater standard of 0.5 to 0.5, so wastewater treatment equipment must be installed, and in addition, new waste containing arsenic is generated from this equipment. There is a serious drawback in that this must be handled.

As a recovery method from GaAs scrap, JP-A-57-10
There is a method described in Japanese Patent No. 1625. This method uses GaAs scraps with a residual pressure of 1.01 x 10 to 1 x 10''
m + nHg at a heating rate of 0.5-20°C per minute, 25
After increasing the temperature to ~1150 °C and removing arsenic by vacuum pyrolysis, the temperature was increased to 50 °C with a variable cooling rate of 0.05 to 15 °C per minute.
This is a method of obtaining gallium by cooling it to a temperature of 100°C. In this process, the residual pressure is 1°0IXIO~
It requires 1Xl0 rmHg and high vacuum, and it is also necessary to control heating and cooling under high vacuum, making the equipment complex and expensive.The power cost to maintain high vacuum cannot be ignored. There are drawbacks such as.

(Problems to be Solved by the Invention) Among the conventional techniques for recovering metallic gallium from gallium arsenide and/or phosphide, wet processing is a complicated process and requires a lot of effort in terms of equipment and work. , and especially when it comes from arsenide, it has the disadvantage of requiring sophisticated wastewater treatment. Also, since the vacuum pyrolysis method is a dry method,
Although it does not have the above-mentioned drawbacks, since the heat treatment is performed under a high vacuum, the equipment is large-scale, and the power cost cannot be ignored.

Therefore, the present inventors have developed a method for recovering metallic gallium using a dry method, which is a simple process and does not generate wastewater containing harmful substances such as arsenic, and which is a simple method that does not require expensive equipment such as vacuum pyrolysis. The present invention was completed by developing a new collection method.

Therefore, an object of the present invention is to recover metallic gallium from gallium arsenide and/or phosphide by a simple method.

(Means and effects for solving the problem) The present invention has the following features:
The gist of this invention is a method for recovering gallium arsenide and phosphide, which is characterized by thermally decomposing gallium arsenide and/or phosphide in an inert atmosphere and recovering the remaining gallium.

The gas constituting the inert atmosphere refers to a gas that does not react with gallium, arsenic, or phosphide, or decomposition products such as gallium, arsenic, and phosphorus when heated. Therefore, the decomposition products can be separated and recovered as individual substances.

Specifically, one or a mixture of two or more gases of nitrogen, alkone, helium, hydrogen, etc. can be used.

Since gallium, arsenic, and phosphorus all have the property of being highly oxidized, when using nitrogen as the gas constituting the inert atmosphere, ultra-high purity nitrogen gas (purity of 99.999% or higher) must be used. , oxygen content o, s ppm or less). When using an alcone, it is desirable to use one of high purity, especially one with less impurities such as oxygen.

Next, the heating temperature needs to be higher than the decomposition temperature of QaAs or GaP. GaAs is about 750℃
Therefore, C, aP starts to decompose at about 550° C., and the decomposition rate increases as the heating temperature increases. On the other hand, the vapor pressure of gallium is 1 x 10-1 Hg at 1300°C,
1 pharyngeal Hg at 1500℃, l OmmH at 1750℃
g increases as the temperature increases, so increasing the heating temperature accelerates the volatilization of gallium and rapidly increases the loss of gallium.

Therefore, the heating temperature is preferably in the range of 750°C to 1500°C when the decomposition material is gallium arsenide, and in the range of 550°C to 1500°C when the decomposition material is gallium phosphide.

Thermal decomposition takes place in an inert atmosphere.

The decomposition may be carried out either in a closed system or in an air stream, but if thermal decomposition is carried out in an air stream: 1) Arsenic and phosphorus, which are decomposition products, are removed from the surroundings of the object to be decomposed, so that the decomposition reaction is promoted.

2) Decomposition products such as arsenic and phosphorus can be condensed and collected in a certain location.

3) Equipment, as there is no need to seal the reaction vessel.

Easy to operate.

There are advantages such as.

Arsenic and phosphorus in metallic gallium obtained from athlete's foot are both 1. Stay below ppm. Among the impurities, zinc, tellurium, etc., which are more volatile than gallium, are reduced by volatilization, but they are less volatile than gallium.

Since aluminum etc. have low volatility, metal, f IJ
It remains in the um. Remaining impurities can be removed by acid washing and recrystallization purification using known methods.

(Example) Example 1 1 kg of gallium arsenide scrap containing 0.1% by weight of zinc and 0.011% by weight of aluminum was placed in an alumina crucible,
In a recovery apparatus equipped with a condenser shown in FIG. 1, thermal decomposition was carried out in an ultra-high purity nitrogen gas stream.

Chin gas was aerated so that the average residence time was 6 to 12 minutes. Heating rate 3~b After heating up to 1200℃ and holding for 2 hours, 50~10
Cooled to 0°C. Liquid gold arsenic 3 x 10 at the bottom of the tube
% by weight.

What was attached to the condenser was confirmed to be metal arsenic by X-ray diffraction.

Example 2 Gallium phosphide cuttings containing 0.2% by weight of inzoum, tellurium o, os, and Izz were fired in an open electric furnace, and
After burning and removing attached lubricating oil and other organic matter, the first
In a recovery device equipped with a condenser as shown in the figure, thermal decomposition was carried out in an ultra-high purity nitrogen gas stream.

Chin gas was aerated so that the average residence time was 6 to 12 minutes. Heating rate 3~b Raise the temperature to 1300℃, hold for 3 hours, then 50~100℃
Cooled to .

0.68 kg of liquid metal gallium remained at the bottom of the crucible for 1 kg of the decomposed material. Impurities in gallium are
Innoum 0.2% by weight, Tellurium I X 1o-'xi
It was phosphorus 4 x 10' seriously poisoned.

The vapor of soot was condensed and adhered to the condenser.

Comparative Example 1 1 kg of gallium arsenide scrap similar to Example 1 was placed in an alumina crucible, placed in an electric furnace equipped with a condenser as shown in Fig. 1, and heated at a heating rate of 3 to 3 in an air atmosphere. After raising the temperature to 1200℃ in 10°min and holding it for 2 hours,
Cooled to 0°C. White crystals remained at the bottom of the crucible and when weighed, they weighed 0.64 kg and were found to be gallium oxide by X-ray diffraction. On the other hand, white crystals attached to the condenser were identified as arsenite A8203.

(Effects) According to the present invention, since the process is simple, gallium arsenide and phosphide can be produced using extremely simple equipment and operations.
Metallic gallium can be recovered.

Furthermore, when treating gallium arsenide, volatilized arsenic can be recovered as metal arsenic with low toxicity, and there is no need for wastewater treatment equipment for removing harmful substances as in the case of wet treatment.

[Brief explanation of drawings]

FIG. 1 shows a schematic diagram of a gallium recovery apparatus according to the present invention. 1... Electric furnace, 2... Crucible, 3... Condenser, 4
... Chin gas, 5... Flowmeter, 6... Δ Lup, 7
···Cooling water.

Claims (1)

[Claims] 1. Recovery of gallium from gallium arsenide and phosphide, characterized by thermally decomposing the gallium arsenide and/or phosphide in an inert atmosphere and recovering the remaining gallium. Law. 2. The method for recovering gallium according to claim 1, wherein the inert gas is one or more of nitrogen, argon, helium, and hydrogen. 3. If the product to be decomposed is gallium arsenide, the thermal decomposition temperature is 750°C to 1500°C. If the decomposable product is gallium phosphide, the thermal decomposition temperature is 550°C to 1500°C.
A method for recovering gallium according to claim 1 or 2, characterized in that the temperature is 500°C.