A method for melt extraction and separation of gallium arsenide waste

Abstract

The present invention discloses a method for melt extraction and separation of gallium arsenide waste. Elemental aluminum and the gallium arsenide waste are co-heated to a set temperature for melt extraction to obtain a molten system. After the extraction is completed, the molten system is cooled in stages and condensed step by step to obtain aluminum arsenide, aluminum, and gallium-aluminum alloy in sequence. The present invention can achieve efficient separation of arsenic and aluminum in gallium arsenide, and at the same time obtain high-value products such as aluminum arsenide, aluminum, hydrogen gas, and pure gallium products, without generating waste arsenic-containing wastewater. In the process, the auxiliary material aluminum used has no other consumption except for being consumed in the hydrolysis of forming arsenic-aluminum alloy and gallium-aluminum alloy to produce hydrogen. The remaining aluminum can be continuously returned to the aluminum melt extraction process, realizing reagent recycling and low consumption.

Description

Technical Field

[0001] The present invention relates to the field of comprehensive resource recovery and high-value utilization, and particularly to a method for melt extraction and separation of gallium arsenide waste. Background Art

[0002] Gallium arsenide is the most important, most mature in related technologies, and most widely used material among the second-generation new semiconductor materials after single-crystalline silicon. It is widely used in multiple fields such as the new generation of mobile communications, electronic information technology, global positioning system, cruise guidance, satellite radar, etc. With the continuous development of related industries, the demand for gallium arsenide is increasing day by day, generating a large amount of gallium arsenide waste; at the same time, a large amount of defective products and scraps will also be generated during the production process of gallium arsenide. Aluminum arsenide and AlGaAs with high aluminum components have strong selectivity, and the formed oxide layer has stable performance, good electrical insulation, and low refractive index. This oxidation process has broad application prospects in the preparation of III-V semiconductor devices and optoelectronic integration. The existing gallium arsenide waste treatment processes mainly include: (1) nitric acid decomposition-neutralization precipitation separation of gallium arsenide waste; (2) nitric acid decomposition-sulfide precipitation separation of gallium arsenide waste; (3) chlorination decomposition-distillation separation of gallium arsenide waste; (4) vacuum thermal decomposition of gallium arsenide waste to recover gallium and arsenic. Processes (1), (2), and (3) are wet treatment processes, which have problems such as long process flow, poor operating environment, and generation of a large amount of arsenic-containing wastewater, alkali / acid-containing wastewater, and organic-containing wastewater. Process (4) is a pyrometallurgical treatment process, which has the characteristics of short process and high efficiency, but the required temperature reaches above 1000°C.

[0003] The patent with the publication number CN 108707927 A discloses a process in which a waste material containing gallium arsenide is used as the anode and electrolyzed in a gallium-containing alkaline electrolyte to obtain metallic gallium and an electrolysis residue containing arsenate. The key point of this invention is to treat gallium arsenide waste by electrochemical means. The patent with the publication number CN 108728641 A adopts an acid leaching-extraction-direct electrowinning process of gallium organic phase to solve problems such as low electrowinning efficiency in the recovery process of gallium arsenide waste. The patent with the publication number CN106399696 A proposes a method for preparing sulfides of arsenic from gallium arsenide chip production waste. The key lies in uniformly mixing the waste material with sublimed sulfur and heating and reacting in a nitrogen atmosphere to obtain the corresponding sulfide. The patent with the publication number CN 106498168 A provides a method for recovering gallium from oil-containing gallium arsenide slurry. This method obtains metallic gallium through vacuum distillation to remove oil, controlled potential oxidation leaching, extraction to remove arsenic, and solution preparation and electrolysis. Summary of the Invention

[0004] The present invention provides a method for melt extraction and separation of gallium arsenide waste, aiming to solve the technical problems of low efficiency, poor effect, environmental unfriendliness, low added value of products or the need for further treatment in the current treatment and separation of gallium arsenide.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for melt extraction and separation of gallium arsenide waste, in which elemental aluminum and the gallium arsenide waste are jointly heated to a set temperature for melt extraction to obtain a molten system. After the extraction is completed, the molten system is cooled in stages and condensed step by step to obtain aluminum arsenide, aluminum, and gallium-aluminum alloy in sequence.

[0007] The design idea of the above technical solution is that the inventor found that the aluminum melt has excellent selectivity for arsenic in the gallium arsenide waste and has a good extraction effect on arsenic. Therefore, the present invention utilizes this characteristic to achieve the selective extraction and separation of gallium and arsenic, and then by taking advantage of the different freezing points of substances such as aluminum arsenide, aluminum, and gallium, the separation of the melts of aluminum arsenide, aluminum, and gallium-aluminum alloy is realized through step-by-step condensation to obtain aluminum arsenide, aluminum, and gallium-aluminum alloy. Among the above products, aluminum arsenide has a high added value and can be directly reused without further treatment. Metallic aluminum can be returned for melt extraction of gallium arsenide in the previous step. No waste residue or waste water is generated during the overall separation process. The process flow is short and the operation is simple, having good industrial application prospects.

[0008] As a further preference of the above technical solution, the method for melt extraction and separation of gallium arsenide waste includes the following steps:

[0009] (1) Put elemental aluminum and the gallium arsenide waste into a heating device, and introduce a protective gas for heating. After heating to the set temperature, perform heat preservation treatment to obtain melt A; the mass ratio of the elemental aluminum to the gallium arsenide waste is greater than 3:1;

[0010] (2) Cool melt A to precipitate aluminum arsenide solid, and separate to obtain gallium-aluminum alloy and melt B;

[0011] (3) Cool melt B to precipitate aluminum solid, and separate to obtain elemental aluminum and melt C;

[0012] (4) Cool and stir melt C to obtain gallium-aluminum alloy.

[0013] As a further preference of the above technical solution, the set temperature in step (1) is 700 - 900 °C, and the heat preservation time is 5 - 10 h.

[0014] As a further preference of the above technical solution, in step (2), melt A is cooled to 650 - 800 °C and heat-preserved for 4 - 10 h to precipitate aluminum arsenide solid.

[0015] As a further preference of the above technical solution, in step (3), the melt B is cooled to 300 - 650 °C and kept warm for 3 - 10 h to precipitate aluminum solids from the melt B.

[0016] As a further preference of the above technical solution, in step (4), the melt C is cooled to 20 - 300 °C, and the stirring speed is 10 - 200 r / min.

[0017] As a further preference of the above technical solution, after obtaining the gallium-aluminum alloy in step (4), the gallium-aluminum alloy is hydrolyzed to produce hydrogen and metallic gallium.

[0018] As a further preference of the above technical solution, the hydrolysis operation includes the following steps: The gallium-aluminum alloy is crushed and put into water, and the hydrolysis reaction is carried out at a controlled temperature of 60 - 90 °C. Hydrogen and the reaction solution are collected. After the reaction solution is filtered, it is cooled to 10 °C to obtain solid metallic gallium.

[0019] As a further preference of the above technical solution, the protective gas in step (1) is argon or nitrogen.

[0020] Compared with the prior art, the advantages of the present invention are as follows:

[0021] The present invention uses aluminum melt extraction to decompose gallium arsenide. At the same time, taking advantage of the different freezing points of substances such as aluminum arsenide, aluminum, and gallium, stepwise condensation is adopted to separate the aluminum arsenide, aluminum, and gallium-aluminum alloy melts, obtaining aluminum arsenide, aluminum, and gallium-aluminum alloy. Finally, the gallium-aluminum alloy is hydrolyzed to produce hydrogen, and at the same time, metallic gallium is produced. Using the process provided by the present invention to treat gallium arsenide waste can achieve efficient separation of arsenic and aluminum in gallium arsenide. At the same time, high-value products such as aluminum arsenide, aluminum, hydrogen, and pure gallium products are obtained, and no waste arsenic-containing wastewater is generated. Except for the consumption in the formation of arsenic-aluminum alloy and the hydrolysis of gallium-aluminum alloy to produce hydrogen, there is no other consumption of the auxiliary material aluminum used in the process. The remaining aluminum can continue to be returned to the aluminum melt extraction process, realizing reagent recycling and low consumption. Description of the Drawings

[0022] Figure 1 It is a process flow chart of the gallium arsenide waste melt extraction and separation method for each embodiment of the present invention. Detailed Embodiments

[0023] The following further elaborates the present invention in detail with specific embodiments. In the following embodiments, "gallium arsenide waste" refers to waste gallium arsenide and the scraps and defective products generated in production links such as epitaxial wafer growth, electrode production, thinning, scribing, and testing. Its chemical composition is shown in Table 1 below:

[0024] Table 1 Chemical Composition of Gallium Arsenide Waste in Each Embodiment (% by mass, ωt)

[0025]

[0026] The aluminum used in the following examples was purchased as analytically pure reagent.

[0027] Embodiment 1:

[0028] like Figure 1 As shown, the gallium arsenide waste melt extraction and separation method of this embodiment includes the following steps:

[0029] (1) 500 g of gallium arsenide waste #1 was ground into 200 mesh and added into a furnace together with 2000 g of aluminum (the mass ratio of elemental aluminum to gallium arsenide waste was 4:1). Nitrogen was introduced until the air in the furnace was completely replaced. The heating program was started, the temperature was raised to 900 °C and kept at this temperature for 8 h to obtain melt A.

[0030] (2) The melt A was cooled to 700°C and kept at this temperature for 4 hours before slag-liquid separation to obtain 315 g of aluminum arsenide slag (94.89% of the arsenic was converted into aluminum arsenide slag) and melt B;

[0031] (3) The temperature of melt B was cooled to 300 °C and kept at this temperature for 4 h, and 1728 g of aluminum slag and melt C were obtained;

[0032] (4) The melt C was cooled and stirred at 20 r / min until the temperature reached 20°C, thereby obtaining 452 g of solidified aluminum-gallium alloy. The aluminum-gallium alloy was ground into 200 mesh and reacted with water at 60°C to obtain 22 g of hydrogen. After filtering, the filtrate was cooled to 10°C and 220.5 g of gallium was obtained from the bottom of the solution (gallium recovery rate 93.8%).

[0033] Embodiment 2:

[0034] like Figure 1 As shown, the gallium arsenide waste melt extraction and separation method of this embodiment includes the following steps:

[0035] (1) 500 g of gallium arsenide waste #1 was ground into 200 mesh and added into a furnace together with 3000 g of aluminum (the mass ratio of elemental aluminum to gallium arsenide waste was 6:1). Nitrogen was introduced until the air in the furnace was completely replaced. The heating program was started, the temperature was raised to 850°C and kept at this temperature for 10 hours to obtain melt A.

[0036] (2) The melt A was cooled to 700°C and kept at this temperature for 6 hours before slag-liquid separation to obtain 435 g of aluminum arsenide slag (93.62% of the arsenic entered the aluminum arsenide slag) and melt B;

[0037] (3) The temperature of melt B was cooled to 650°C and kept at this temperature for 10 h, and 2434 g of aluminum slag and melt C were obtained;

[0038] (4) Cool down the melt C, and stir it at 200 r / min while cooling. Cool it down to 300 °C to obtain 926 g of solidified aluminum-gallium alloy; grind the aluminum-gallium alloy to 200 mesh, react it with water at 90 °C, collect 70 g of hydrogen gas, cool the filtrate to 10 °C after filtration, and collect 211.9 g of gallium from the bottom of the solution (gallium recovery rate: 90.2%).

[0039] Example 3:

[0040] As Figure 1 shown, the method for extracting and separating gallium arsenide waste melt in this example includes the following steps:

[0041] (1) Take 500 g of gallium arsenide waste #1, grind it to 200 mesh, and then add it to a furnace together with 2000 g of aluminum (the mass ratio of elemental aluminum to gallium arsenide waste is 4:1). Introduce nitrogen until the air in the furnace is completely replaced; start the heating program, heat it to 850 °C and keep it warm for 10 h to obtain melt A;

[0042] (2) Start the cooling program for melt A, cool it to 680 °C and keep it warm for 6 h, then perform slag-liquid separation to obtain 335 g of aluminum arsenide slag (95.74% of arsenic enters the aluminum arsenide slag) and melt B;

[0043] (3) Start the cooling program for melt B, cool it to 400 °C and keep it warm for 4 h to obtain 1667 g of aluminum slag and melt C;

[0044] (4) Cool down the melt C, and stir it at 100 r / min while cooling. Cool it down to 100 °C to obtain 493 g of solidified aluminum-gallium alloy; grind the aluminum-gallium alloy to 200 mesh, react it with water at 80 °C, collect 27 g of hydrogen gas, cool the filtrate to 10 °C after filtration, and collect 208.5 g of gallium from the bottom of the solution (gallium recovery rate: 88.7%).

[0045] Example 4:

[0046] As Figure 1 shown, the method for extracting and separating gallium arsenide waste melt in this example includes the following steps:

[0047] (1) Take 500 g of gallium arsenide waste #1, grind it to 200 mesh, and then add it to a furnace together with 3000 g of aluminum (the mass ratio of elemental aluminum to gallium arsenide waste is 6:1). Introduce nitrogen until the air in the furnace is completely replaced; start the heating program, heat it to 900 °C and keep it warm for 7 h to obtain melt A;

[0048] (2) Start the cooling program for melt A, cool it to 700 °C and keep it warm for 5 h, then perform slag-liquid separation to obtain 385 g of aluminum arsenide slag (99.14% of arsenic enters the aluminum arsenide slag) and melt B;

[0049] (3) Start the cooling process for Melt B, cool it down to 500 °C and hold for 3 h to obtain 2579 g of aluminum slag and Melt C;

[0050] (4) Conduct a cooling treatment on Melt C. While cooling, stir at 200 r / min until it cools down to 250 °C to obtain 531 g of solidified aluminum-gallium alloy; Grind the aluminum-gallium alloy to 200 mesh, react with water at 80 °C, collect 29 g of hydrogen gas, and after filtration, cool the filtrate to 10 °C and collect 223.7 g of gallium from the bottom of the solution (gallium recovery rate: 95.2%).

[0051] Example 5:

[0052] As Figure 1 shown, the method for extracting and separating gallium arsenide waste melt in this example includes the following steps:

[0053] (1) Take 500 g of gallium arsenide waste #1, grind it to 200 mesh, add it to a furnace together with 3000 g of aluminum, and introduce nitrogen until the air in the furnace is completely replaced; Start the heating process, heat it up to 700 °C and hold for 10 h to obtain Melt A;

[0054] (2) Start the cooling process for Melt A, cool it down to 650 °C and hold for 10 h, then separate the slag and liquid to obtain 432 g of aluminum arsenide slag (97.87% of arsenic enters the aluminum arsenide slag) and Melt B;

[0055] (3) Start the cooling process for Melt B, cool it down to 500 °C and hold for 3 h to obtain 2528 g of aluminum slag and Melt C;

[0056] (4) Conduct a cooling treatment on Melt C. While cooling, stir at 150 r / min until it cools down to 200 °C to obtain 535 g of solidified aluminum-gallium alloy; Grind the aluminum-gallium alloy to 200 mesh, react with water at 60 °C, collect 27 g of hydrogen gas, and after filtration, cool the filtrate to 10 °C and collect 221.3 g of gallium from the bottom of the solution (gallium recovery rate: 94.2%).

[0057] The above is only the preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. For those skilled in the art of this technology, the improvements and transformations obtained without departing from the technical concept of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for melt extraction and separation of gallium arsenide waste, characterized in that, The elemental aluminum and the gallium arsenide waste are heated together to a set temperature for melt extraction to obtain a molten system. After the extraction is completed, the molten system is cooled in stages and condensed step by step to obtain aluminum arsenide, aluminum, and gallium-aluminum alloy in sequence.

2. The method for extracting and separating gallium arsenide waste melt according to claim 1, characterized in that, It includes the following steps: (1) Put the elemental aluminum and the gallium arsenide waste into a heating device, and introduce a protective gas for heating. After heating to the set temperature, keep it warm to obtain melt A; the mass ratio of the elemental aluminum to the gallium arsenide waste is greater than 3:1; (2) Cool melt A to cause the precipitation of aluminum arsenide solid, and separate to obtain an aluminum arsenide alloy and melt B; (3) Cool melt B to cause the precipitation of aluminum solid, and separate to obtain elemental aluminum and melt C; (4) Cool and stir melt C to obtain a gallium-aluminum alloy.

3. The method for extracting and separating gallium arsenide waste melt according to claim 2, characterized in that, In step (1), the set temperature is 700 - 900 °C, and the holding time is 5 - 10 h.

4. The method for extracting and separating gallium arsenide waste melt according to claim 2, characterized in that, In step (2), melt A is cooled to 650 - 800 °C and kept warm for 4 - 10 h to cause the precipitation of aluminum arsenide solid from melt A.

5. The method for extracting and separating gallium arsenide waste melt according to claim 2, wherein In step (3), melt B is cooled to 300 - 650 °C and kept warm for 3 - 10 h to cause the precipitation of aluminum solid from melt B.

6. The method for melt extraction and separation of gallium arsenide waste according to claim 2, characterized in that, In step (4), melt C is cooled to 20 - 300 °C, and the stirring speed is 10 - 200 r / min.

7. The method for melt extraction and separation of gallium arsenide waste according to any one of claims 2-6, characterized in that, After obtaining the gallium-aluminum alloy in step (4), hydrolyze the gallium-aluminum alloy to produce hydrogen and metallic gallium.

8. The method for melt extraction and separation of gallium arsenide waste according to claim 7, characterized in that, The hydrolysis operation includes the following steps: crush the gallium-aluminum alloy and put it into water, control the temperature at 60 - 90 °C for hydrolysis reaction, collect hydrogen and the reaction solution, filter the reaction solution and cool it to 10 °C to obtain solid metallic gallium.

9. The method for melt extraction and separation of gallium arsenide waste according to any one of claims 2-6, characterized in that, In step (1), the protective gas is argon or nitrogen.

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