Method for purifying germanium and high-purity germanium

Abstract

The application 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: germanium mud is smelted at a smelting temperature of 950-1500 DEG C in a reducing gas atmosphere, and after smelting, the temperature is lowered to 600-800 DEG C to obtain spherical germanium; step 2: the spherical germanium is heat-insulated and crystallized at a temperature of 600-800 DEG C in a reducing gas atmosphere for 60-180 min to obtain high-purity germanium; step 3: the high-purity germanium is sequentially subjected to surface corrosion, cleaning and drying, and then remelted and cast into ingots to obtain germanium ingots; and step 4: the germanium ingots are sequentially subjected to surface corrosion, cleaning and drying, and then subjected to zone smelting to obtain high-purity germanium ingots. The application provides a germanium purification method, in which the germanium mud is first smelted into spherical germanium, and in the smelting process, the large specific surface area and surface tension of the spherical germanium are utilized to promote the discharge of impurities from the surface of the spherical germanium, so that the purity of the spherical germanium is improved, and then the spherical germanium is further subjected to heat-insulating purification treatment, thereby greatly improving the purity of the recovered germanium.

Description

Technical Field

[0001] This invention relates to the field of metal purification technology, specifically to a method for purifying germanium and high-purity germanium. Background Technology

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

[0003] In the process of processing germanium single crystal rods into germanium lenses, germanium windows, and other germanium products, a large amount of germanium sludge is generated during wire cutting. The traditional method is to use chemical methods to reprocess the germanium sludge into germanium dioxide powder. For example, the background section of Chinese patent application 202211088324.6 states: "Traditionally, germanium-containing materials such as germanium scraps, waste, and germanium sludge are pretreated, ball-milled into powder, and then distilled in a hydrochloric acid system to produce crude germanium tetrachloride. This is then further purified by distillation and hydrolyzed to produce germanium dioxide." This process is not only complex, but also involves transportation, purification, and procurement, resulting in a relatively long cycle. During periods of rising germanium prices and scarcity of germanium materials, this is not conducive to increasing germanium production capacity.

[0004] Based on this, prior art 2: Chinese patent application 202410977334.8 discloses a method for recovering germanium from high-grade germanium-containing materials, including the following steps: (1) vacuuming and purging with argon gas; (2) maintaining a certain vacuum degree in the single crystal furnace and filling the single crystal furnace with a certain amount of argon gas 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 above the single crystal furnace, and growing a crystal block by crystallization and shoulder formation; after the crystal block grows to a certain size, raising the seed crystal position to a certain height above the liquid surface for cooling and cooling down, after cooling down 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 raising the crystal block to a certain height above the liquid surface; repeating the above operations several times to complete the removal of impurities and purification; (5) cooling down and casting ingots.

[0005] Existing technology 2 uses a pyrometallurgical process, which is short, produces no waste liquid, and has a high germanium recovery rate of over 98%, with good impurity removal effect. However, the impurity removal operation of this method is relatively complex, and the research focus is on the germanium recovery rate, without further in-depth research on impurity removal. Therefore, the germanium purity obtained is at the 2N level, which requires further purification through a more complex purification process. Summary of the Invention

[0006] One of the objectives of this invention is to provide a method for purifying germanium, which uses germanium mud as raw material. First, spherical germanium particles are prepared. Then, taking advantage of the large specific surface area and surface tension of the spheres, the germanium mud can be purified and impurities removed more effectively. Further purification is carried out by heat preservation, melting into ingots, and zone melting purification, which effectively improves the purity of germanium and is simple to operate.

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

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

[0009] Step 1: Melt the germanium mud in a reducing gas atmosphere at a melting temperature of 950-1500℃. After melting, cool it down to 600-800℃ to obtain spherical germanium.

[0010] Step 2: Crystallize spherical germanium at a temperature of 600-800℃ for 60-180 min in a reducing gas atmosphere to obtain high-purity germanium;

[0011] Step 3: The high-purity germanium is subjected to surface etching, cleaning and drying in sequence, and then remelted and cast into ingots to obtain germanium ingots;

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

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

[0014] In this invention, spherical germanium is prepared in step 1. At this time, the spherical germanium is polycrystalline germanium. Since the spherical shape has a large specific surface area, the surface tension it forms can better remove impurities from the surface of the spherical germanium. Therefore, step 2 further purifies the spherical germanium by heat preservation. Heat preservation can realize the recrystallization and grain growth of polycrystalline germanium. During this process, grain growth can reduce the number of grain boundaries. Impurities at the grain boundaries will be discharged through the spherical surface of the spherical germanium, thus further driving away impurities inside the spherical germanium.

[0015] To avoid impurities adhering to the surface of high-purity germanium and to obtain high-purity germanium, surface etching, cleaning, and drying operations can further remove impurities. In this technical field, surface etching, cleaning, and drying are commonly used techniques for germanium purification and preparation, and belong to the prior art. Those skilled in the art can perform surface etching, cleaning, and drying on the high-purity germanium prepared by this invention as needed.

[0016] More preferably, the specific operation of surface etching in this invention is as follows: high-purity germanium is cleaned with acetone, and then surface etching is performed using an acidic solution such as hydrofluoric acid and / or nitric acid, or an alkaline solution such as sodium hydroxide and / or hydrogen peroxide solution.

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

[0018] Furthermore, the specific operation of step 1 is as follows: Germanium mud is placed in a mold and then placed in a reduction furnace for melting at a melting temperature of 950-1500℃. After melting, it is cooled to obtain spherical germanium. During the process, hydrogen gas is continuously introduced at a flow rate of 8-15L / min.

[0019] Furthermore, the specific operation of step 2 is as follows: the spherical germanium is cooled to 600-800℃ and then kept at that temperature for 60-180 minutes to obtain high-purity germanium. During the process, hydrogen gas is continuously introduced at a flow rate of 8-15 L / min.

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

[0021] Beneficial effects

[0022] Compared with the prior art, the present invention provides a method for purifying germanium. First, germanium mud is melted into spherical germanium. During the melting process, the large specific surface area and surface tension of spherical germanium can promote the discharge of impurities from the surface of the spherical germanium, thereby improving the purity of the spherical germanium. Then, the spherical germanium is further purified by heat preservation. Finally, it is prepared into long strip-shaped germanium ingots for zone melting, which greatly improves the purity of the recovered germanium. Detailed Implementation

[0023] 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.

[0024] To illustrate the technical content of the present invention in detail, the following description is provided in conjunction with the embodiments.

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

[0026] In the technical solution of this 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: Place germanium clay into a mold, then place it in a reduction furnace and heat it to a melting temperature of 950°C at a heating rate of 5°C. After melting, cool it down to 700°C to obtain spherical germanium. During the process, hydrogen gas is continuously introduced at a flow rate of 8L / min.

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

[0031] Step 3: The high-purity germanium is subjected to surface etching, cleaning and drying in sequence, and then remelted and cast into ingots to obtain germanium ingots;

[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℃ in a reducing gas atmosphere to obtain high-purity germanium ingot.

[0033] Example 2

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

[0035] Step 1: Place germanium clay into a mold, then place it in a reduction furnace and heat it to a melting temperature of 1500℃ at a heating rate of 5℃. After melting, cool it to obtain spherical germanium. During the process, hydrogen gas is continuously introduced at a flow rate of 8L / min.

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

[0037] Step 3: The high-purity germanium is subjected to surface etching, cleaning and drying in sequence, and then remelted and cast into ingots to obtain germanium ingots;

[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℃ in a reducing gas atmosphere to obtain high-purity germanium ingot.

[0039] Example 3

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

[0041] Step 1: Place germanium clay into a mold, then place it in a reduction furnace and heat it to a melting temperature of 1100℃ at a heating rate of 5℃. After melting, cool it to obtain spherical germanium. During the process, hydrogen gas is continuously introduced at a flow rate of 8L / min.

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

[0043] Step 3: The high-purity germanium is subjected to surface etching, cleaning and drying in sequence, and then remelted and cast into ingots to obtain germanium ingots;

[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℃ in a reducing gas atmosphere to obtain high-purity germanium ingot.

[0045] Example 4

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

[0047] Step 1: Place germanium clay into a mold, then place it in a reduction furnace and heat it to a melting temperature of 1100℃ at a heating rate of 5℃. After melting, cool it to obtain spherical germanium. During the process, hydrogen gas is continuously introduced at a flow rate of 8L / min.

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

[0049] Step 3: The high-purity germanium is subjected to surface etching, cleaning and drying in sequence, and then remelted and cast into ingots to obtain germanium ingots;

[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℃ in a reducing gas atmosphere to obtain high-purity germanium ingot.

[0051] Comparative Example 1

[0052] It is largely the same as Example 3, except that in step 1, a long strip mold is used to melt the germanium mud into long strips of germanium.

[0053] Comparative Example 2

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

[0055] Purity testing

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

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

[0058] Table 1. Results of germanium purity testing in 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:

[0061] According to the data from Examples 1-4, the present invention can effectively improve the removal of impurities by preparing germanium mud into spherical shapes and then performing heat preservation treatment. Furthermore, high-purity germanium can be effectively obtained by casting it into ingots and zone melting.

[0062] According to the data comparison between Example 1 and Comparative Example 1, when germanium mud is prepared into long strips, its impurity removal effect is significantly reduced, and the purity of the product drops from 4N level to 1N level. The reason is that the present invention can increase the specific surface area by preparing germanium mud into a spherical shape. When it shrinks into a curved surface during the cooling process, the surface tension of the sphere promotes the discharge of impurities. In addition, in Comparative Example 1, some impurities were still wrapped inside the germanium segments or in the cracks when germanium mud was directly fired into long strips. The effect of corroding and cleaning small pieces of germanium segments was not significant. It is not as easy as the spherical shape of Example 1 to expose impurities on the material surface, making them easier to clean and corrode away.

[0063] According to the data comparison between Example 1 and Comparative Example 2, the heat preservation operation in step 2 of the present invention has a significant impact on the impurity removal effect of spherical germanium. The purity of the product dropped from the 4N level to 3N. The heat preservation treatment of the present invention helps spherical germanium to further remove impurities that are more difficult to remove. In this technical field, the difficulty increases geometrically with each increase in purity level. Impurities remaining after the 3N level are extremely difficult to remove by conventional technical means.

[0064] 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 purifying germanium, characterized in that, Includes the following steps: Step 1: Melt the germanium mud in a reducing gas atmosphere at a melting temperature of 950-1500℃ for 60-90 minutes. After melting, cool it down to 600-800℃ to obtain spherical germanium, which is polycrystalline germanium. Step 2: Crystallize spherical germanium at a temperature of 600-800℃ for 60-180 min in a reducing gas atmosphere to obtain high-purity germanium; Step 3: The high-purity germanium is subjected to surface etching, cleaning and drying in sequence, and then remelted and cast into ingots to obtain germanium ingots; Step 4: The germanium ingot is subjected to surface etching, cleaning and drying in sequence, and then zone melting is carried out to obtain high-purity germanium ingot.

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

3. The method for purifying germanium according to claim 1, characterized in that, The specific operation of step 1 is as follows: Germanium mud is placed in a mold and then placed in a reduction furnace for melting at a melting temperature of 950-1500℃. After melting, it is cooled to obtain spherical germanium, and hydrogen gas is continuously introduced during the process.

4. The method for purifying germanium according to claim 1, characterized in that, The specific operation of surface etching is as follows: high-purity germanium is cleaned with acetone, and then surface etching is performed using an acidic solution or an alkaline solution; the acidic solution is hydrofluoric acid and / or nitric acid, and the alkaline solution is sodium hydroxide and / or hydrogen peroxide solution.

5. A high-purity germanium, characterized in that, It was prepared using the germanium purification method described in any one of claims 1-3.