CN116177505A - A method for efficiently recovering indium and phosphorus in indium phosphide waste in a molten salt system - Google Patents

Abstract

The invention belongs to the technical field of non-ferrous metal metallurgy, and specifically relates to a method for efficiently recovering indium and phosphorus in indium phosphide waste in a molten salt system. The method is to generate heat in a molten indium phosphide waste under normal pressure conditions. Decomposition, the simultaneous recovery of metal indium and elemental phosphorus can be realized through a one-step reaction. The technical scheme of the present invention has the characteristics of short process, high efficiency, low requirements for equipment, low cost, etc., and can realize the comprehensive recovery of indium phosphide waste with high efficiency and short process; the molten salt system does not participate in chemical reactions, but only serves as a reaction medium The inorganic salt recovered after the reaction can be recycled after simple grinding and drying treatment. The whole reaction process does not consume any chemical reagents in theory, the production cost is low, and the economic benefit is good; the production process does not produce waste gas, waste water, and waste residue. Environment friendly.

Description

A method for efficiently recovering indium and phosphorus in indium phosphide waste in a molten salt system

technical field

The invention belongs to the technical field of nonferrous metal metallurgy, and in particular relates to a method for efficiently recovering indium and phosphorus in indium phosphide waste in a molten salt system.

Background technique

Indium has excellent physical and chemical properties and is widely used in semiconductors, electrical components, optoelectronics, communications and other fields. With the progress of science and technology and the development of society, the demand for indium in the field of high-tech industries is increasing rapidly year by year. However, indium is a sparse metal with an average abundance in the earth's crust of only 50-200 ppb. Indium has no independent deposits in nature, and is mainly associated with zinc sulfide ore, so it is often obtained as a by-product of zinc smelting, but the content of indium in zinc sulfide ore is only 1-100ppm. Therefore, the natural resources of indium are very limited, and it is difficult to meet the industry's growing demand for indium. Recovering indium from secondary resources will be an important supplement to the limited indium primary resources.

Indium phosphide (InP) is an important III-V compound semiconductor material. It has excellent characteristics such as wide band gap, direct transition energy band structure, strong radiation resistance, and high electron mobility. It is widely used in High-tech fields such as optical fiber communication, solar cells, integrated circuits, and high-speed high-frequency devices. However, indium phosphide is brittle and has low hardness, and the scrap rate is as high as about 70% in the process of producing InP devices. On the other hand, with the rapid development of the semiconductor industry, a large number of indium phosphide semiconductor devices will be updated and iterated, resulting in a large amount of indium phosphide waste. Therefore, indium phosphide waste is an important secondary resource of indium, and its efficient and comprehensive recovery is of great significance to the sustainable development of related industries.

Currently, research on the recycling of indium phosphide scrap is relatively limited. Searched:

The Chinese patent document with the publication number CN106586988B discloses a method for comprehensively recovering indium and phosphorus from indium phosphide waste. The indium phosphide waste powder is placed in a vacuum tube furnace to decompose indium phosphide under high temperature and vacuum conditions. Indium and phosphorus vapors are further recovered separately. Although this method can realize the short-process comprehensive recovery of indium phosphide waste, the production process needs to be realized under high temperature and vacuum conditions, which not only consumes high energy, but also requires the use of vacuum smelting equipment with high investment costs, resulting in high production costs.

The Chinese patent literature with the publication number CN106319224B discloses a method for recovering indium from indium phosphide waste. Concentrated hydrochloric acid and sodium chlorate are used as leaching agents to fully dissolve the indium phosphide waste, and zinc powder is further added to the leaching solution to replace it to obtain a sponge. indium. Although this process can effectively recover metal indium from indium phosphide waste, the chlorine ion leaching system under high acidity conditions not only severely corrodes the equipment, but also pollutes the production environment with volatile hydrogen chloride gas; in addition, the thermodynamic promotion of replacing indium with zinc powder The strength is limited, and the addition of excessive zinc powder will reduce the purity of the sponge indium product, and the zinc powder is a controlled reagent that is prone to explosives, and the production safety risk is high.

The Chinese patent document with the publication number CN114380323A discloses a method for recovering indium in indium phosphide. After mixing indium phosphide powder and iron powder evenly, a solid phase reaction is carried out at high temperature, and hydrogen chloride gas is further introduced to make indium selective. Chlorination produces volatile indium chloride, and finally condenses in the gas phase to recover InCl ₃ . The indium chloride recovered by this method has a high purity, but the whole recovery process is long, the operation is complicated, and the requirements for equipment are high, and the indium is recovered in the form of indium chloride, which requires further processing to obtain metal indium products.

In summary, the existing indium phosphide waste recycling process still has a lot of room for optimization and improvement, and it is necessary to further develop comprehensive recycling of indium phosphide waste with simple operation, short process, high efficiency, low cost, and environmental friendliness Process technology supports the sustainable development of related industries.

Contents of the invention

The purpose of the present invention is to overcome the existing problems of long comprehensive recycling process of indium phosphide waste, high requirements on equipment, low efficiency, high production cost, etc., and provide a method for efficiently recycling indium and phosphorus in indium phosphide waste in a molten salt system . The process technology of the present invention has the characteristics of short flow, high efficiency, low requirements on equipment, low cost, etc., and can realize comprehensive recovery of indium phosphide waste with high efficiency and short flow.

In order to achieve the above-mentioned technical purpose and achieve the above-mentioned technical effect, the present invention is realized through the following technical solutions:

A method for efficiently recovering indium and phosphorus in indium phosphide waste in a molten salt system. Under normal pressure, the indium phosphide waste is thermally decomposed in the molten salt system, and the simultaneous recovery of metal indium and elemental phosphorus is realized through a one-step reaction .

Further, the specific operation includes the following steps:

1) mixing the indium phosphide waste powder and the inorganic salt system in proportion;

2) Put the mixture in a tube furnace, raise the temperature to a predetermined temperature and react at a constant temperature for a period of time. The whole process is carried out under the protection of a flowing inert atmosphere. The liquid metal indium produced exists in the molten salt, and the elemental phosphorus is with the protection. The gas enters the condensation zone to recover elemental phosphorus;

3) After the reaction is completed, cool with the furnace, and separate the solidified inorganic salt from the metal indium. After the metal indium is washed and dried, a metal indium product is obtained; the separated inorganic salt can be recycled.

Further, in step 1), the indium phosphide waste is pre-ball milled to a particle size of ≤300 μm.

Further, in step 1), the inorganic salt system is MCl _x -NCl _y binary eutectic salt, wherein M and N are any two of Li, Na, K, and Ca, and the values of x and y are 1 or 2.

Further, in step 1), the mass ratio of the inorganic salt system to the indium phosphide waste is controlled at 5-50:1.

Further, in step 2), the predetermined temperature is 50-100°C above the eutectic point of MCl _{x -NCly} binary eutectic salt, and the heating rate is 5-30°C/min; The reaction time is 1-10h.

Further, in step 2), the inert protective gas is one of argon, nitrogen, and helium, and the gas flow rate is 1-5 L/min.

Further, in step 2), the temperature of recovering elemental phosphorus in the condensation zone is controlled at 50-90°C.

Further, in step 3), the recovered metal indium is washed 4-8 times with deionized water.

Further, in step 3), the washed metal indium is dried at 60-100° C. for 24-72 hours to obtain a metal indium product.

The beneficial effects of the present invention are:

1. A method for efficiently recovering indium and phosphorus in indium phosphide waste in a molten salt system of the present invention, in which the indium phosphide waste is thermally decomposed in the molten salt system, and the synchronization of metal indium and elemental phosphorus can be realized through a one-step reaction Recycling, short production process and high efficiency, can realize comprehensive recycling of indium phosphide waste with high efficiency and short process.

2. A method for efficiently recovering indium and phosphorus in indium phosphide waste in a molten salt system of the present invention. The molten salt medium can provide a vacuum-like oxygen-free environment for the reaction process, so that indium phosphide waste can be thermally decomposed to recover metal indium and elemental substances The process of phosphorus can be realized under normal pressure conditions, and the expected effect can be achieved by using ordinary tube furnaces commonly used in the metallurgical industry. There is no need to use vacuum metallurgical equipment necessary in traditional methods, and the requirements for equipment are low, which can greatly reduce the reaction requirements. Energy consumption and equipment investment cost; in addition, the molten salt medium can provide a microgravity field environment for the reaction process, so that the indium phosphide waste powder can be fully and uniformly dispersed in the molten salt system, which is conducive to improving the reaction rate and conversion rate. The recovery rate of phosphorus is high.

3. A method for efficiently reclaiming indium and phosphorus in indium phosphide waste in a molten salt system of the present invention. The molten salt system does not participate in chemical reactions, but only serves as a reaction medium. After the reaction, the recovered inorganic salt undergoes simple It can be recycled after grinding and drying. The whole reaction process theoretically does not consume any chemical reagents, with low production cost and good economic benefits. The production process does not produce waste gas, waste water, and waste residue, which is environmentally friendly.

Of course, implementing any product of the present invention does not necessarily need to achieve all the above advantages at the same time.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Relevant specific embodiments of the present invention are as follows:

The invention provides a method for efficiently recovering indium and phosphorus in indium phosphide waste in a molten salt system. Under normal pressure, the indium phosphide waste is thermally decomposed in the molten salt system, and metal indium can be realized through one-step reaction. and simultaneous recovery of elemental phosphorus. The technical scheme of the invention has the characteristics of short process, high efficiency, low requirements on equipment, low cost, etc., and can realize comprehensive recovery of indium phosphide waste materials in an efficient short process. Production technology of the present invention specifically comprises the following steps:

1) Mix the indium phosphide waste powder that has been ball-milled to be below 300 μm in proportion with the inorganic salt system, and the inorganic salt system is composed of MCl _x -NCl _y (M, N = Li, Na, K, Ca; x, y = 1 or 2) Binary eutectic salt, controlling the mass ratio of the inorganic salt system to the indium phosphide waste between 5:1 and 50:1.

2) Put the mixture in a tube furnace, raise the temperature to 50-100°C above the eutectic point of the MCl _x -NCl _y binary mixed system at a rate of 5-30°C/min, and react at a constant temperature for 1-10h. The whole process is at It is carried out under the protection condition of flowing inert atmosphere. The inert protection gas is one of argon, nitrogen and helium. The gas flow rate is 1-5L/min. The liquid metal indium generated exists in the molten salt, and the elemental phosphorus is The protective gas enters the condensation zone with a temperature of 50-90°C to recover elemental phosphorus.

3) Cool in the furnace after the reaction, separate the solidified inorganic salt from the metal indium, wash the metal indium 4-8 times with deionized water, and dry at 60-100°C for 24-72h to obtain the metal indium product.

The present invention will be further described below in conjunction with specific embodiments.

Example 1

This embodiment provides a method for efficiently recycling indium and phosphorus in indium phosphide waste in a molten salt system, which specifically includes the following steps:

1) Mix the indium phosphide waste powder pre-milled to be below 300 μm with the LiCl-NaCl binary eutectic salt, and control the mass ratio of the inorganic salt system to the indium phosphide waste to be 5:1.

2) Put the mixture in a tube furnace, raise the temperature to 620°C at a rate of 30°C/min, and react at a constant temperature for 1h. The liquid metal indium exists in the molten salt, while the elemental phosphorus enters the condensation zone with a temperature of 50°C along with the protective gas to recover the elemental phosphorus.

3) Cool in the furnace after the reaction, separate the solidified inorganic salt from the metal indium, wash the metal indium four times with deionized water, and dry at 60°C for 72 hours to obtain the metal indium product.

Using the method of this embodiment, the recovery rate and purity of metal indium and elemental phosphorus were analyzed by aqua regia dissolution combined with inductively coupled plasma mass spectrometer (ICP-MS) and X-ray fluorescence spectrometer (XRF), and the result was metal indium and elemental phosphorus The recoveries are 98.5% and 97.8%, respectively, and the purity of metal indium and elemental phosphorus are 99.95% and 99.23%, respectively.

Example 2

This embodiment provides a method for efficiently recycling indium and phosphorus in indium phosphide waste in a molten salt system, which specifically includes the following steps:

1) Mix the indium phosphide waste powder pre-milled to be below 300 μm with the LiCl-KCl binary eutectic salt, and control the mass ratio of the inorganic salt system to the indium phosphide waste to 50:1.

2) Put the mixture in a tube furnace, heat up to 450°C at a rate of 5°C/min, and react at a constant temperature for 10 hours. The whole process is carried out under the protection of a flowing nitrogen atmosphere, and the gas flow rate is 5L/min. The resulting liquid Metal indium exists in molten salt, while elemental phosphorus enters the condensation zone with a temperature of 90°C along with the protective gas to recover elemental phosphorus.

3) Cool in the furnace after the reaction, separate the solidified inorganic salt from the metal indium, wash the metal indium 8 times with deionized water, and dry at 100° C. for 24 hours to obtain the metal indium product.

Using the method of this embodiment, the recovery rate and purity of metal indium and elemental phosphorus were analyzed by aqua regia dissolution combined with inductively coupled plasma mass spectrometer (ICP-MS) and X-ray fluorescence spectrometer (XRF), and the result was metal indium and elemental phosphorus The recoveries were 97.6% and 97.2%, respectively, and the purity of metal indium and elemental phosphorus were 99.93% and 99.18%, respectively.

Example 3

This embodiment provides a method for efficiently recycling indium and phosphorus in indium phosphide waste in a molten salt system, which specifically includes the following steps:

1) Mix the indium phosphide waste powder pre-milled to be below 300 μm with the LiCl-CaCl ₂ binary eutectic salt, and control the mass ratio of the inorganic salt system to the indium phosphide waste to be 15:1.

2) Put the mixture in a tube furnace, raise the temperature to 550°C at a rate of 10°C/min, and react at a constant temperature for 3 hours. The whole process is carried out under the protection condition of a flowing helium atmosphere, and the gas flow rate is 2L/min. Liquid metal indium exists in molten salt, while elemental phosphorus enters the condensation zone with a temperature of 60°C along with the protective gas to recover elemental phosphorus.

3) Cool in the furnace after the reaction, separate the solidified inorganic salt from the metal indium, wash the metal indium five times with deionized water, and dry at 70°C for 60 hours to obtain the metal indium product.

Using the method of this embodiment, the recovery rate and purity of metal indium and elemental phosphorus were analyzed by aqua regia dissolution combined with inductively coupled plasma mass spectrometer (ICP-MS) and X-ray fluorescence spectrometer (XRF), and the result was metal indium and elemental phosphorus The recoveries are 98.8% and 98.2%, respectively, and the purity of metal indium and elemental phosphorus are 99.97% and 99.36%, respectively.

Example 4

This embodiment provides a method for efficiently recycling indium and phosphorus in indium phosphide waste in a molten salt system, which specifically includes the following steps:

1) Mix the indium phosphide waste powder pre-milled to be below 300 μm with the NaCl-KCl binary eutectic salt, and control the mass ratio of the inorganic salt system to the indium phosphide waste to be 30:1.

2) Put the mixture in a tube furnace, heat up to 700°C at a rate of 15°C/min, and react at a constant temperature for 6 hours. The whole process is carried out under the protection condition of a flowing helium atmosphere, and the gas flow rate is 3L/min. The generated Liquid metal indium exists in molten salt, while elemental phosphorus enters the condensation zone with a temperature of 70°C along with the protective gas to recover elemental phosphorus.

3) Cool in the furnace after the reaction, separate the solidified inorganic salt from the metal indium, wash the metal indium 6 times with deionized water, and dry at 80° C. for 48 hours to obtain the metal indium product.

Using the method of this embodiment, the recovery rate and purity of metal indium and elemental phosphorus were analyzed by aqua regia dissolution combined with inductively coupled plasma mass spectrometer (ICP-MS) and X-ray fluorescence spectrometer (XRF), and the result was metal indium and elemental phosphorus The recoveries were 97.6% and 96.8%, respectively, and the purity of metal indium and elemental phosphorus were 99.94% and 99.46%, respectively.

Example 5

This embodiment provides a method for efficiently recycling indium and phosphorus in indium phosphide waste in a molten salt system, which specifically includes the following steps:

1) Mix the indium phosphide waste powder pre-milled to be below 300 μm with the NaCl-CaCl ₂ binary eutectic salt, and control the mass ratio of the inorganic salt system to the indium phosphide waste to 40:1.

2) Put the mixture in a tube furnace, raise the temperature to 550°C at a rate of 20°C/min, and react at a constant temperature for 8 hours. The whole process is carried out under the protection condition of a flowing argon atmosphere, and the gas flow rate is 4L/min. The liquid metal indium exists in the molten salt, while the elemental phosphorus enters the condensation zone with a temperature of 80°C along with the protective gas to recover the elemental phosphorus.

3) Cool in the furnace after the reaction, separate the solidified inorganic salt from the metal indium, wash the metal indium 7 times with deionized water, and dry at 90° C. for 36 hours to obtain the metal indium product.

Using the method of this embodiment, the recovery rate and purity of metal indium and elemental phosphorus were analyzed by aqua regia dissolution combined with inductively coupled plasma mass spectrometer (ICP-MS) and X-ray fluorescence spectrometer (XRF), and the result was metal indium and elemental phosphorus The recoveries are 99.2% and 98.7%, respectively, and the purity of metal indium and elemental phosphorus are 99.98% and 99.38%, respectively.

The preferred embodiments of the invention disclosed above are only to help illustrate the invention. The preferred embodiments do not exhaust all details nor limit the invention to specific implementations. Obviously, many modifications and variations can be made based on the contents of this specification. This description selects and specifically describes these embodiments in order to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The invention is to be limited only by the claims, along with their full scope and equivalents.

Claims (10)

1. A method for efficiently reclaiming indium and phosphorus in indium phosphide waste in a molten salt system, characterized in that, under normal pressure conditions, the indium phosphide waste is thermally decomposed in the molten salt system, and metal indium is realized by one-step reaction and simultaneous recovery of elemental phosphorus. 2. the method for efficiently reclaiming indium and phosphorus in a kind of molten salt system according to claim 1 in the indium phosphide waste material, is characterized in that, concrete operation comprises the steps: 1) mixing the indium phosphide waste powder and the inorganic salt system in proportion; 2) Put the mixture in a tube furnace, raise the temperature to a predetermined temperature and react at a constant temperature for a period of time. The whole process is carried out under the protection of a flowing inert atmosphere. The liquid metal indium produced exists in the molten salt, and the elemental phosphorus is with the protection. The gas enters the condensation zone to recover elemental phosphorus; 3) After the reaction is completed, cool with the furnace, and separate the solidified inorganic salt from the metal indium. After the metal indium is washed and dried, a metal indium product is obtained; the separated inorganic salt can be recycled. 3. A method for efficiently recovering indium and phosphorus in indium phosphide waste in a molten salt system according to claim 2, characterized in that in step 1), the indium phosphide waste is pre-ball milled to a particle size ≤ 300 μm. 4. the method for efficiently reclaiming indium and phosphorus in a kind of molten salt system according to claim 2, is characterized in that: in step 1), described inorganic salt system is MCl _x -NCl _y binary total A crystal salt, wherein M and N are any two of Li, Na, K, and Ca, and the values of x and y are 1 or 2. 5. the method for efficiently reclaiming indium and phosphorus in a kind of molten salt system according to claim 4, is characterized in that: in step 1), the mass ratio control of described inorganic salt system and indium phosphide waste material In 5-50:1. 6. The method for efficiently reclaiming indium and phosphorus in indium phosphide waste in a kind of molten salt system according to claim 4, characterized in that: in step 2), the predetermined temperature is MCl _x -NCl _y binary eutectic 50-100°C above the eutectic point of the salt, the heating rate is 5-30°C/min; after the temperature is raised to the predetermined temperature, the constant temperature reaction time is 1-10h. 7. The method for efficiently reclaiming indium and phosphorus in indium phosphide waste in a kind of molten salt system according to claim 2, characterized in that: in step 2), the inert protective gas is argon, nitrogen, helium One, the gas flow rate is 1-5L/min. 8. A method for efficiently recycling indium and phosphorus in indium phosphide waste in a molten salt system according to claim 2, characterized in that: in step 2), the temperature for recovering elemental phosphorus in the condensation zone is controlled at 50-90 ℃. 9. The method for efficiently reclaiming indium and phosphorus in indium phosphide waste in a molten salt system according to claim 2, characterized in that: in step 3), the recovered metal indium is washed with deionized water for 4-8 Second-rate. 10. A method for efficiently reclaiming indium and phosphorus in indium phosphide waste in a molten salt system according to claim 2, characterized in that: in step 3), the washed metal indium is dried at 60-100°C for 24- 72h, the indium metal product was obtained.