Preparation method of low-silicon-content high-purity indium

Abstract

This invention belongs to the field of metal purification technology and discloses a method for preparing high-purity indium with low silicon content, comprising the following steps: Step 1: Place the indium raw material into a hydrogenation furnace and evacuate to a vacuum degree of 5*10 ‑3 Pa-8*10 ‑3 Step 2: Purge with inert gas to atmospheric pressure and maintain the pressure for 30 minutes; Step 3: Replace the inert gas with hydrogen gas, turn on the heater to raise the temperature to 400-600℃, and maintain the temperature for 1-2 hours to obtain the low-silicon content high-purity indium. This invention discloses a method for preparing low-silicon content high-purity indium, which can reduce the silicon content in high-purity indium to <10 ppbw, effectively improving the performance of high-purity indium.

Description

Technical Field

[0001] This invention relates to the field of metal purification technology, specifically to a method for preparing high-purity indium with low silicon content. Background Technology

[0002] Indium is a silvery-white metal with a slight bluish tint, and it is very soft. Indium is highly malleable and ductile, and can be pressed into sheets. It has a melting point of 156.61℃ and a boiling point of 2060℃. Metallic indium is mainly used in the manufacture of low-melting-point alloys, bearing alloys, semiconductors, and electric light sources. High-purity indium (5N and above) is primarily used in the preparation of compound semiconductor materials, CIGS thin-film solar cells, and ITO sputtering targets. ITO (used in the production of liquid crystal displays and flat panel screens) is the main consumer of indium ingots, accounting for 70% of global indium consumption; the electronic semiconductor sector accounts for 12% of global consumption; solder and alloys account for 12%; and research accounts for 6%.

[0003] Prior art 1: Chinese patent application 201310485991.2 discloses a method for preparing high-purity indium, which includes the following steps: 1) crushing and grinding waste ITO target material to obtain target fragments; 2) placing the target fragments in a reduction furnace for redox reaction to obtain indium-tin alloy; 3) placing the indium-tin alloy in a molten electrolyte for molten salt electrolytic separation, and depositing indium metal at the cathode; 4) using the indium metal obtained in step 3) as the anode for secondary electrolytic purification to obtain high-purity indium.

[0004] The technical solution of this invention application yields a product with a purity of over 99.995%, high yield, low production cost, and a material recovery rate of over 95%; however, the indium purity produced by the above technical solution can no longer meet the needs of today's technological development.

[0005] High-purity indium is a key raw material for preparing semiconductor crystals such as indium phosphide. Indium phosphide crystals have important applications in infrared detection, opto-magnetic devices, magnetoresistive devices, and solar energy converters. The electronics and semiconductor industries have extremely high requirements for crystals, and the introduction of trace impurities in the raw materials can seriously affect the performance of the crystal materials themselves. The purity of the raw materials must reach 6N or even 7N or higher to meet the requirements.

[0006] The main methods for preparing high-purity indium include electrolysis, vacuum distillation, zone melting, organometallic compound methods, and low-halogen compound methods. These processes mainly remove metallic impurities from indium through chemical or physical purification. Si, as a difficult-to-remove impurity in high-purity indium ingots, directly affects the performance of high-purity indium and is closely related to the electrical properties of indium during use. Currently, the Si content of directly cast high-purity indium ingots ranges from 20 to 100 ppbw. Removing the Si content from high-purity indium ingots is a difficult problem that modern technology urgently needs to solve. Summary of the Invention

[0007] One objective of this invention is to provide a method for preparing high-purity indium with low silicon content, thereby addressing the problems of insufficient indium purity and difficulty in removing silicon in existing technologies. This method reduces the silicon removal rate in high-purity indium to single digits, effectively improving the performance of high-purity indium.

[0008] To achieve the above objectives, the present invention provides a method for preparing high-purity indium with low silicon content, comprising the following steps:

[0009] Step 1: Place the indium raw material into the hydrogenation furnace and evacuate to a vacuum level of 5*10. -3 Pa-8*10 -3 Pa;

[0010] Step 2: Purge with inert gas to atmospheric pressure and maintain the pressure for 30 minutes;

[0011] Step 3: Replace the inert gas with hydrogen, turn on the heater to raise the temperature to 400-600℃, and keep it at that temperature for 1-2 hours to obtain the low silicon content high purity indium.

[0012] Preferably, the indium raw material is an indium raw material with a purity of 6N or higher.

[0013] Preferably, the heating temperature in step 3 can be selected as 400℃, 450℃, 500℃, 550℃, or 600℃.

[0014] Preferably, the heat preservation time in step 3 is 1 hour, 1.5 hours, or 2 hours.

[0015] Furthermore, the indium raw material is prepared by the following steps: indium with a purity of 5.5N is loaded into a graphite boat, and the graphite boat is placed into a zone melting furnace for zone melting to obtain indium raw material with a purity of 6N or higher.

[0016] Furthermore, the melting temperature of the zone melting is 180°C, and the melting is performed 5 times.

[0017] Furthermore, the specific operation of step 1 is as follows: the indium raw material is loaded into a quartz tube with sealing flanges at both ends, the quartz tube is placed in a hydrogenation furnace, and the quartz tube is evacuated until the vacuum degree inside the tube is 5*10. -3 Pa-8*10 -3 Pa.

[0018] Furthermore, during the heating and heat preservation process in step 3, hydrogen gas is continuously introduced at a flow rate of 4-8 L / min.

[0019] Preferably, the preparation method of the low silicon content high purity indium further includes step 4: after the heat preservation in step 3 is completed, wait for the low silicon content high purity indium to cool to complete solidification, then introduce inert gas to replace it into an inert gas atmosphere, and maintain the pressure at normal pressure for 30 minutes.

[0020] Preferably, the inert gas can be either nitrogen or argon.

[0021] Furthermore, the reaction principle of the above method is: Si + 2H₂ = SiH₄.

[0022] Beneficial effects

[0023] Compared with the prior art, the present invention has at least the following advantages:

[0024] (1) After vacuuming, the present invention needs to fill in inert gas to restore the pressure inside the quartz tube to normal pressure, so that the remaining gas in the environment can be fully mixed with the inert gas, so that the remaining other gases and inert gas can be discharged during the subsequent replacement of hydrogen, further optimizing the purity of hydrogen in the environment, reducing the oxygen content in the environment to the minimum, and avoiding safety problems caused by the subsequent generation of flammable silicon tetrahydrogen.

[0025] (2) The present invention controls the reaction rate by controlling the hydrogen flow rate, thereby significantly improving the silicon removal rate;

[0026] (3) This invention discloses a method for preparing high-purity indium with low silicon content, which can reduce the silicon content in high-purity indium to <10ppbw, effectively improving the performance of high-purity indium. Detailed Implementation

[0027] The present invention will be further described below with reference to embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0028] To illustrate the technical content of the present invention in detail, the following description is provided in conjunction with the embodiments.

[0029] In the following embodiments, the indium raw material is prepared by the following steps: indium with a purity of 5.5N is loaded into a graphite boat, and the graphite boat is loaded into a zone melting furnace and melted five times at a melting temperature zone of 180°C to obtain indium raw material with a purity of 6N.

[0030] The method for detecting silicon content is as follows: glow discharge mass spectrometry. The sample is used as the cathode for glow discharge. Under an argon atmosphere, the atoms on the sample surface are sputtered and detached from the sample into the glow discharge plasma. After being ionized in the plasma, they are introduced into the mass spectrometer.

[0031] Example 1

[0032] A high-purity indium with low silicon content is prepared by the following steps:

[0033] Step 1: Load indium raw material with a silicon content of 34 ppbw into a quartz tube with sealing flanges at both ends. Place the quartz tube into the hydrogenation furnace and evacuate the quartz tube until the vacuum level inside the tube reaches 8*10. -3 Pa;

[0034] Step 2: Pass inert gas into the quartz tube until atmospheric pressure is reached, and maintain the pressure for 30 minutes;

[0035] Step 3: Replace the inert gas with hydrogen, turn on the hydrogenation furnace and heat it to 400℃, keep it at that temperature for 2 hours, and continuously introduce hydrogen during the process at a flow rate of 8L / min.

[0036] Step 4: After the heat preservation in Step 3 is completed, wait for the low silicon content high purity indium to cool to complete solidification, then introduce inert gas to replace it to an inert gas atmosphere, maintain pressure at normal pressure for 30 minutes to obtain low silicon content high purity indium, and the silicon content is found to be 5.7 ppbw when sampled and tested.

[0037] Example 2

[0038] A high-purity indium with low silicon content is prepared by the following steps:

[0039] Step 1: Load indium raw material with a silicon content of 28 ppbw into a quartz tube with sealing flanges at both ends. Place the quartz tube into the hydrogenation furnace and evacuate the quartz tube until the vacuum level inside the tube reaches 6*10. -3 Pa;

[0040] Step 2: Pass inert gas into the quartz tube until atmospheric pressure is reached, and maintain the pressure for 30 minutes;

[0041] Step 3: Replace the inert gas with hydrogen, turn on the hydrogenation furnace and heat it to 500℃, keep it at that temperature for 1.5h, and continuously introduce hydrogen during the process at a flow rate of 6L / min.

[0042] Step 4: After the heat preservation in Step 3 is completed, wait for the low silicon content high purity indium to cool to complete solidification, then introduce inert gas to replace it to an inert gas atmosphere, maintain the pressure at normal pressure for 30 minutes to obtain low silicon content high purity indium, and the silicon content is found to be 3.8 ppbw when sampled and tested.

[0043] Example 3

[0044] A high-purity indium with low silicon content is prepared by the following steps:

[0045] Step 1: Load indium raw material with a silicon content of 25 ppbw into a quartz tube with sealing flanges at both ends. Place the quartz tube into the hydrogenation furnace and evacuate the quartz tube until the vacuum level inside the tube is 5*10. -3 Pa;

[0046] Step 2: Pass inert gas into the quartz tube until atmospheric pressure is reached, and maintain the pressure for 30 minutes;

[0047] Step 3: Replace the inert gas with hydrogen, turn on the hydrogenation furnace and heat it to 600℃, keep it at that temperature for 1 hour, and continuously introduce hydrogen during the process at a flow rate of 8L / min.

[0048] Step 4: After the heat preservation in Step 3 is completed, wait for the low silicon content high purity indium to cool to complete solidification, then introduce inert gas to replace it to an inert gas atmosphere, maintain pressure at normal pressure for 30 minutes to obtain low silicon content high purity indium, and the silicon content is found to be 2.2 ppbw when sampled and tested.

[0049] Example 4

[0050] A high-purity indium with low silicon content is prepared by the following steps:

[0051] Step 1: Load indium raw material with a silicon content of 35 ppbw into a quartz tube with sealing flanges at both ends. Place the quartz tube into the hydrogenation furnace and evacuate the quartz tube until the vacuum level inside the tube is 5*10. -3 Pa;

[0052] Step 2: Pass inert gas into the quartz tube until atmospheric pressure is reached, and maintain the pressure for 30 minutes;

[0053] Step 3: Replace the inert gas with hydrogen, turn on the hydrogenation furnace and heat it to 480℃, keep it at that temperature for 2 hours, and continuously introduce hydrogen during the process at a flow rate of 5L / min.

[0054] Step 4: After the heat preservation in Step 3 is completed, wait for the low silicon content high purity indium to cool to complete solidification, then introduce inert gas to replace it and create an inert gas atmosphere. Maintain pressure at normal pressure for 30 minutes to obtain low silicon content high purity indium. The silicon content was found to be 4.5 ppbw when sampled and tested.

[0055] The embodiments presented herein are merely selected implementations based on combinations of all possible embodiments. The appended claims should not be limited to the embodiments described herein. Some numerical ranges used in the claims include sub-ranges within them, and variations within these ranges should also be covered by the appended claims.

Claims

1. A method for preparing high-purity indium with low silicon content, characterized in that, Includes the following steps: Step 1: Place the indium raw material into the hydrogenation furnace and evacuate to a vacuum level of 5*10. -3 Pa-8*10 -3 Pa; Step 2: Purge with inert gas to atmospheric pressure and maintain the pressure for 30 minutes; Step 3: Replace the inert gas with hydrogen, turn on the heater to raise the temperature to 400-600℃, and keep it at that temperature for 1-2 hours to obtain the low silicon content high purity indium.

2. The method for preparing high-purity indium with low silicon content according to claim 1, characterized in that, The indium raw material is an indium raw material with a purity of 6N or higher.

3. The method for preparing high-purity indium with low silicon content according to claim 2, characterized in that, Indium raw materials are prepared by the following steps: Indium with a purity of 5.5N is loaded into a graphite boat, and the graphite boat is loaded into a zone melting furnace for zone melting to obtain indium raw materials with a purity of 6N or higher.

4. The method for preparing high-purity indium with low silicon content according to claim 3, characterized in that, The melting temperature in the area is 180°C, and the melting process is repeated 5 times.

5. The method for preparing high-purity indium with low silicon content according to claim 1, characterized in that, The specific operation of step 1 is as follows: Indium raw material is loaded into a quartz tube with sealing flanges at both ends, the quartz tube is placed in a hydrogenation furnace, and the quartz tube is evacuated until the vacuum degree inside the tube is 5*10. -3 Pa-8*10 -3 Pa.

6. The method for preparing high-purity indium with low silicon content according to claim 1, characterized in that, During the heating and heat preservation process in step 3, hydrogen gas is continuously introduced at a flow rate of 4-8 L / min.

7. The method for preparing high-purity indium with low silicon content according to claim 1, characterized in that, It also includes step 4: After the heat preservation in step 3 is completed, wait for the low silicon content high purity indium to cool to complete solidification, then introduce inert gas to replace it with an inert gas atmosphere, and maintain the pressure at normal pressure for 30 minutes.