Purification method of germanium and high-purity germanium

Abstract

The invention belongs to the technical field of metal purification, and discloses a germanium purification method and high-purity germanium, the germanium purification method comprises the following steps: step 1, smelting germanium mud in a reducing gas atmosphere at a smelting temperature of 950-1500 DEG C, and cooling to 600-800 DEG C after smelting to obtain spherical germanium; 2, the spherical germanium is subjected to heat preservation crystallization for 60-180 min at the temperature of 600-800 DEG C in the reducing gas atmosphere, and high-purity germanium is obtained; 3, the high-purity germanium is subjected to surface corrosion, cleaning and drying in sequence, then melting ingot casting is conducted again, and a germanium ingot is obtained; and 4, the germanium ingot is subjected to surface corrosion, cleaning and drying in sequence, then zone melting is conducted, and the high-purity germanium ingot is obtained. The invention provides a germanium purification method which comprises the following steps: firstly, smelting germanium mud into spherical germanium, improving the purity of the spherical germanium by utilizing the advantages that the spherical germanium is large in specific surface area and surface tension can promote impurities to be discharged from the surface of the spherical germanium in the smelting process, and then further carrying out heat preservation purification treatment on the spherical germanium. And the purity of the recovered germanium is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal purification, and in particular to a germanium purification method and high-purity germanium. Background Art

[0002] Germanium is widely used in electronics, optics, chemicals, biomedicine, energy and other high-tech fields. As an import and export controlled material, the price of germanium has been increasing recently; therefore, it is necessary to make full use of germanium in the production process.

[0003] In the process of processing germanium single crystal rods into various forms of germanium products such as germanium lenses and germanium windows, a large amount of germanium mud will be generated through wire cutting. The traditional treatment method is to use chemical methods to re-prepare the germanium mud into germanium dioxide powder. For example, the background technology part of prior art 1: Chinese patent application 202211088324.6 records: "The traditional classic germanium deep processing scraps, waste materials, germanium mud and other germanium-containing materials are ball-milled into powders after pre-treatment, and chlorinated distillation in a hydrochloric acid system produces crude germanium tetrachloride, which is then further distilled and purified, and hydrolyzed into germanium dioxide. This not only has a complicated process, but also goes through transportation, purification, procurement and other processes again, and the cycle is relatively long. At a stage when germanium prices are rising and germanium materials are scarce, it is not conducive to increasing the production capacity of germanium products.

[0004] Based on this, prior art 2: Chinese patent application 202410977334.8 discloses a method for recovering germanium from high-grade germanium-containing materials, comprising the following steps: (1) evacuating and replacing with argon; (2) maintaining a certain vacuum degree in the single crystal furnace, and filling a certain amount of argon into the single crystal furnace to maintain the argon atmosphere in the furnace; (3) melting the material; (4) removing impurities and purifying; turning on the crucible to rotate, lowering a heavy hammer with a seed crystal from the top of the single crystal furnace, and growing a crystal block by seeding and shouldering; after the crystal block grows to a certain size, lifting the seed crystal position to a certain height above the liquid surface for cooling and cooling. After cooling and cooling for a period of time, reducing the crucible rotation speed, and lowering the seed crystal position so that the bottom surface of the crystal block contacts the scum gathered on the liquid surface, and the scum adheres to the crystal block, and then lifting the crystal block to a certain height above the liquid surface; repeating the above operations several times to complete impurity removal and purification; (5) cooling and cooling the ingot.

[0005] Existing technology 2 adopts a pyrometallurgical method for treatment, which has a short process and does not produce any waste liquid during the treatment process. At the same time, the recovery rate of germanium is as high as over 98%, and the impurity removal effect is good; however, the impurity removal operation of this method is relatively complicated, and the focus of the research and development direction is on the recovery rate of germanium, and there is no further in-depth research on impurity removal. Therefore, the purity of the obtained germanium is 2N level, and it needs to be purified again using a more complicated purification process. Summary of the invention

[0006] One of the purposes of the present invention is to provide a method for purifying germanium, which uses germanium mud as a raw material, first prepares spherical germanium particles, and then utilizes the advantages of the spherical shape's large specific surface area and surface tension to better achieve the purification and impurity removal of the germanium mud, further heat-insulating purification, smelting into ingots, and zone melting purification, thereby effectively improving the purity of germanium, and the operation is simple.

[0007] Another object of the present invention is to provide high-purity germanium, which is prepared by the germanium purification method of the present invention, and the obtained high-purity germanium can reach the level of 4-5N.

[0008] To achieve the above object, the present invention provides a method for purifying germanium, comprising the following steps:

[0009] Step 1: Smelting the germanium mud at a melting temperature of 950-1500°C in a reducing gas atmosphere, and cooling it to 600-800°C after the melting to obtain spherical germanium;

[0010] Step 2: Crystallize the spherical germanium at 600-800° C. in a reducing gas atmosphere for 60-180 min to obtain high-purity germanium;

[0011] Step 3: etching, cleaning and drying the high-purity germanium in sequence, and then remelting the ingot to obtain a germanium ingot;

[0012] Step 4: The germanium ingot is subjected to surface etching, cleaning and drying in sequence, and then regional melting is performed to obtain a high-purity germanium ingot.

[0013] Preferably, the germanium ingot is a long strip-shaped germanium ingot.

[0014] The present invention prepares spherical germanium through step 1. At this time, the spherical germanium is polycrystalline germanium. Since the specific surface area of ​​the sphere is large, the surface tension formed by the sphere can also better discharge impurities from the surface of the spherical germanium. Therefore, step 2 further performs heat preservation and purification on the spherical germanium. The heat preservation can realize the recrystallization and grain growth of the polycrystalline germanium. In this process, the grain growth can reduce the number of grain boundaries. The impurities at the grain boundaries can be discharged through the spherical surface of the spherical germanium, thereby realizing the further expulsion of impurities inside the spherical germanium.

[0015] In order to prevent impurities from adhering to the surface of high-purity germanium and obtain high-purity germanium, impurities can be further removed through surface corrosion, cleaning and drying operations. In the technical field of this invention, surface corrosion, cleaning and drying are commonly used technical means for purifying and preparing germanium, and belong to the prior art. Those skilled in the art can perform surface corrosion, cleaning and drying on the high-purity germanium prepared by the present invention as needed.

[0016] More preferably, the specific operation of the surface etching of the present invention is: using acetone to clean the high-purity germanium, and then using an acidic solution such as hydrofluoric acid and / or nitric acid, or using an alkaline solution such as sodium hydroxide and / or hydrogen peroxide solution to perform surface etching.

[0017] Furthermore, the gas atmosphere for zone melting in step 4 is hydrogen, and the zone melting temperature is 950-1100°C.

[0018] Furthermore, the specific operation of step 1 is: putting the germanium mud into a mold, and then putting it into a reduction furnace for smelting at a smelting temperature of 950-1500° C., cooling after smelting to obtain spherical germanium, and continuously introducing hydrogen during the process, with a hydrogen flow rate of 8-15L / min.

[0019] Furthermore, the specific operation of step 2 is: cooling the spherical germanium to 600-800° C. and then keeping the temperature for 60-180 minutes, cooling to obtain high-purity germanium, and continuously introducing hydrogen during the process, with a hydrogen flow rate of 8-15 L / min.

[0020] The invention also discloses high-purity germanium, which is prepared by adopting the above germanium purification method.

[0021] Beneficial Effects

[0022] Compared with the prior art, the present invention provides a method for purifying germanium, which firstly melts germanium mud into spherical germanium, and during the smelting process, utilizes the advantages of spherical germanium having a large specific surface area and surface tension that can promote the discharge of impurities from the surface of spherical germanium, thereby improving the purity of the spherical germanium, and then further subjecting the spherical germanium to heat preservation and purification treatment, and then prepares long strips of germanium ingots for regional smelting, thereby greatly improving the purity of the recovered germanium. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the embodiments, but it does not constitute any limitation to the present invention. Any limited number of modifications made within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0024] In order to explain the technical content of the present invention in detail, further description is given below in conjunction with the implementation modes.

[0025] In the following examples and comparative examples, the specific operation of surface etching is: high-purity germanium is cleaned with acetone, and then surface etching is performed with hydrofluoric acid; and deionized water is used for cleaning.

[0026] In the technical solution of the present invention, the mold used is the mold in Chinese Patent 202110825994.0.

[0027] Example 1

[0028] A high purity germanium is prepared by the following steps:

[0029] Step 1: Put the germanium mud into a mold, and then put it into a reduction furnace and heat it to 950°C at a heating rate of 5°C for smelting. After smelting, cool it to 700°C to obtain spherical germanium. During the process, hydrogen is continuously introduced at a hydrogen flow rate of 8L / min.

[0030] Step 2: Continue to heat and crystallize the spherical germanium at 700°C for 120 minutes to obtain high-purity germanium. During the process, hydrogen is continuously introduced at a hydrogen flow rate of 8 L / min.

[0031] Step 3: etching, cleaning and drying the high-purity germanium in sequence, and then remelting the ingot to obtain a germanium ingot;

[0032] Step 4: The germanium ingot is subjected to surface etching, cleaning and drying in sequence, and then zone melting is carried out at a zone melting temperature of 1000° C. in a reducing gas atmosphere to obtain a high-purity germanium ingot.

[0033] Example 2

[0034] A high purity germanium is prepared by the following steps:

[0035] Step 1: Put the germanium mud into a mold, and then put it into a reduction furnace and heat it to a melting temperature of 1500°C at a heating rate of 5°C for melting. After the melting is completed, cool it to obtain spherical germanium. During the process, hydrogen is continuously introduced at a hydrogen flow rate of 8L / min.

[0036] Step 2: Continue to heat and crystallize the spherical germanium at 800°C for 60 minutes to obtain high-purity germanium. During the process, hydrogen is continuously introduced at a hydrogen flow rate of 8 L / min.

[0037] Step 3: etching, cleaning and drying the high-purity germanium in sequence, and then remelting the ingot to obtain a germanium ingot;

[0038] Step 4: The germanium ingot is subjected to surface etching, cleaning and drying in sequence, and then zone melting is carried out at a zone melting temperature of 950° C. in a reducing gas atmosphere to obtain a high-purity germanium ingot.

[0039] Example 3

[0040] A high purity germanium is prepared by the following steps:

[0041] Step 1: Put the germanium mud into a mold, and then put it into a reduction furnace and heat it to a melting temperature of 1100°C at a heating rate of 5°C for melting. After the melting is completed, cool it to obtain spherical germanium. During the process, hydrogen is continuously introduced at a hydrogen flow rate of 8L / min.

[0042] Step 2: Continue to heat and crystallize the spherical germanium at 600°C for 180 minutes to obtain high-purity germanium. During the process, hydrogen is continuously introduced at a hydrogen flow rate of 8 L / min.

[0043] Step 3: etching, cleaning and drying the high-purity germanium in sequence, and then remelting the ingot to obtain a germanium ingot;

[0044] Step 4: The germanium ingot is subjected to surface etching, cleaning and drying in sequence, and then zone melting is carried out at a zone melting temperature of 1050° C. in a reducing gas atmosphere to obtain a high-purity germanium ingot.

[0045] Example 4

[0046] A high purity germanium is prepared by the following steps:

[0047] Step 1: Put the germanium mud into a mold, and then put it into a reduction furnace and heat it to a melting temperature of 1100°C at a heating rate of 5°C for melting. After the melting is completed, cool it to obtain spherical germanium. During the process, hydrogen is continuously introduced at a hydrogen flow rate of 8L / min.

[0048] Step 2: Continue to heat and crystallize the spherical germanium at 700°C for 120 minutes to obtain high-purity germanium. During the process, hydrogen is continuously introduced at a hydrogen flow rate of 8 L / min.

[0049] Step 3: etching, cleaning and drying the high-purity germanium in sequence, and then remelting the ingot to obtain a germanium ingot;

[0050] Step 4: The germanium ingot is subjected to surface etching, cleaning and drying in sequence, and then zone melting is carried out at a zone melting temperature of 980° C. in a reducing gas atmosphere to obtain a high-purity germanium ingot.

[0051] Comparative Example 1

[0052] It is generally the same as Example 3, except that, in step 1, a long strip mold is used to melt the germanium mud into long strip-shaped germanium segments.

[0053] Comparative Example 2

[0054] The method is generally the same as Example 3, except that step 2 is omitted, and step 3 is performed after step 1 is directly cooled to room temperature.

[0055] Purity testing

[0056] Detection method: glow discharge mass spectrometry (GDMS).

[0057] The finished products obtained in Examples 1-4 and Comparative Examples 1-2 were tested for germanium purity, and the results are shown in Table 1.

[0058] Table 1 Germanium purity test results of Examples 1-4 and Comparative Examples 1-2

[0059] Germanium purity % Example 1 99.991％ Example 2 99.995％ Example 3 99.993％ Example 4 99.995％ Comparative Example 1 98.791％ Comparative Example 2 99.958％

[0060] According to the results in Table 1, we can see that:

[0061] According to the data of Examples 1-4, the present invention can effectively improve the discharge effect of impurities by preparing the germanium mud into a spherical shape and then performing a heat preservation treatment, and further, high-purity germanium can be effectively obtained by means of melting into ingots and regional smelting.

[0062] According to the data comparison between Example 1 and Comparative Example 1, it can be seen that after the germanium mud is prepared into long strips, its impurity removal effect is significantly reduced, and the purity of the product is reduced from 4N level to 1N level. The reason is that the present invention prepares the germanium mud into a sphere to increase the specific surface area. When it shrinks into a curved surface during the cooling process, the surface tension of the sphere promotes the discharge of impurities; and in Comparative Example 1, some impurities are still wrapped in the germanium segments or in the cracks of the germanium segments when the germanium mud is directly burned into long strips. The effect of corroding and cleaning the small pieces of germanium segments is not significant, which is not as good as the sphere in Example 1. It is easier to expose impurities on the surface of the material, which is easy to clean and corrode.

[0063] According to the data comparison between Example 1 and Comparative Example 2, it can be seen that the heat preservation operation in step 2 of the present invention has a great influence on the impurity removal effect of spherical germanium, and the purity of the product is reduced from 4N level to 3N. The heat preservation treatment of the present invention is beneficial to the spherical germanium to further remove impurities that are more difficult to remove. In the technical field of this invention, the difficulty increases geometrically with each level of purity improvement. The impurities remaining after the 3N level are extremely difficult to remove by conventional technical means.

[0064] The embodiments presented herein are only embodiments selected according to the combination of all possible embodiments. The appended claims should not be limited by the embodiments describing the present invention. Some numerical ranges used in the claims include sub-ranges therein, and the changes in these ranges should also be covered by the appended claims.

Claims

1. A method for purifying germanium, characterized in that: The steps include: Step 1: Smelt the germanium mud in a reducing gas atmosphere at a melting temperature of 950-1500°C for 60-90 minutes, and after the melting is completed, cool it to 600-800°C to obtain spherical germanium; Step 2: Crystallize the spherical germanium at 600-800° C. in a reducing gas atmosphere for 60-180 min to obtain high-purity germanium; Step 3: etching, cleaning and drying the high-purity germanium in sequence, and then remelting the ingot to obtain a germanium ingot; Step 4: The germanium ingot is subjected to surface etching, cleaning and drying in sequence, and then regional melting is performed to obtain a high-purity germanium ingot.

2. The method for purifying germanium according to claim 1, characterized in that: The gas atmosphere for zone melting in step 4 is hydrogen, and the zone melting temperature is 950-1100°C.

3. The method for purifying germanium according to claim 1, characterized in that: The specific operation of step 1 is: putting the germanium mud into a mold, and then putting it into a reduction furnace for smelting at a smelting temperature of 950-1500° C. After the smelting is completed, cooling is performed to obtain spherical germanium, and hydrogen is continuously introduced during the process.

4. The method for purifying germanium according to claim 1, characterized in that: The specific operation of step 2 is: cooling the spherical germanium after cooling to room temperature to 600-800° C. and then keeping the temperature for 60-180 minutes, cooling to obtain high-purity germanium, and continuously introducing hydrogen during the process.

5. The method for purifying germanium according to claim 1, characterized in that: The specific operation of surface etching is: using acetone to clean the high purity germanium, and then using an acidic solution such as hydrofluoric acid and / or nitric acid, or using an alkaline solution such as sodium hydroxide and / or hydrogen peroxide solution to perform surface etching.

6. A high purity germanium, characterized in that: The germanium is prepared by the germanium purification method described in any one of claims 1 to 4.