Preparation method of chlorine-free high-purity germanium dioxide
Through the high-pressure oxidation process of metal germanium ozone, positive pressure oxidation and high-pressure segmented oxidation are used for autoclaves, which solves the problem of preparing high-purity chlorine-free germanium dioxide in the prior art, and achieves efficient and low-cost production, and environmentally friendly process.
Patent Information
- Application Number
- CN202411970575.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-03-21
AI Technical Summary
The prior art is difficult to effectively prepare high-purity chlorine-free germanium dioxide, resulting in high production costs, low output rates and inability to produce chlorine-free high-purity germanium dioxide.
The high-pressure oxidation process of metal germanium ozone is adopted, and the positive pressure oxidation and high-pressure segmented oxidation are carried out through an autoclave, and ozone and nitrogen are used for oxidation and exhaust gas to prepare high-purity chlorine-free germanium dioxide.
A high output rate of high purity, chlorine-free germanium dioxide (greater than 99%) is achieved, which reduces production costs, is simple in process and environmentally friendly, and is free of wastewater and waste slag generation.
Smart Images
Figure CN119660782A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of germanium dioxide preparation, and in particular to a method for preparing chlorine-free high-purity germanium dioxide. Background Art
[0002] High-purity germanium dioxide is widely used in the production of high-purity metallic germanium, germanium compounds, chemical catalysts, pharmaceutical industry, PET resin, electronic devices, etc. High-purity germanium dioxide is a major product in the germanium industry chain, and the annual production of high-purity germanium dioxide accounts for about 70% of the metal content of the entire industry chain. Among them, the metal content of conventional high-purity germanium dioxide accounts for about 50~55% of the metal content of the entire industry chain; and special high-value high-purity germanium dioxide has special index requirements such as chlorine-free, low rate and water solubility, and has higher product added value, such as about 10~15% for the production of catalysts; about 3~5% for the production of bismuth germanate crystals; about 2% for the production of medical organic germanium, etc.
[0003] Chlorine-free and low-chlorine high-purity germanium dioxide can be used in catalytic applications, with an annual consumption of about 30 to 40 tons. The price is 10 to 15% higher than that of ordinary high-purity germanium dioxide, that is, the added value of the product can be increased by 10 to 15%; a typical indicator of high-purity germanium dioxide for polymerization catalytic grade is water solubility requirements; some companies also require chloride ions to be less than 100ppm, which may be related to catalytic effects and food safety requirements. In addition, in the field of crystal applications, high-purity materials are usually used to melt and grow crystals in platinum crucibles. For example, platinum crucibles are used to grow crystals in the process of preparing BGO scintillation crystals using germanium dioxide and bismuth trioxide. The annual consumption is 10 to 15 tons. If the chloride ions in germanium dioxide are too high, when high-purity germanium dioxide is melted at high temperature, the chlorine in germanium dioxide will be released to corrode the platinum crucible and the crystal preparation equipment. Therefore, the preparation of low-chlorine high-purity germanium dioxide is a very critical link, which can reduce the corrosion of platinum crucibles, increase the life of crystal preparation equipment, and better improve the quality of products. In summary, there is a strong demand for chlorine-free and low-chlorine high-purity germanium dioxide, and the products have higher added value.
[0004] At present, there are three main preparation technologies for low-chlorine or chlorine-free high-purity germanium dioxide at home and abroad: Enhanced hydrolysis and washing method: During the conventional hydrolysis preparation of germanium tetrachloride, the conditions are controlled and the number of washing times is enhanced to prepare low-chlorine, high-purity germanium dioxide with a chloride ion content of less than 100 ppm; the advantage is that it can be produced using conventional production lines for the preparation of germanium dioxide; the disadvantages are that the direct recovery rate of germanium and the output rate of germanium dioxide are too low, resulting in a significant increase in production costs, and secondly, it is impossible to produce chlorine-free high-purity germanium dioxide.
[0005] Hydrogen peroxide oxidation method: prepare chlorine-free high-purity germanium dioxide by reacting pure germanium powder with hydrogen peroxide; the advantage is the simple process flow, but the disadvantage is that incomplete oxidation may occur, resulting in substandard product quality.
[0006] Roasting method: Conventional high-purity germanium dioxide is roasted at high temperature to volatilize the chloride ions in germanium dioxide to produce low-chlorine high-purity germanium dioxide. The advantage is that the process is simple; the disadvantages are that the hexagonal germanium dioxide partially changes to tetragonal at high temperature, and its water solubility becomes worse; the second is high energy consumption; and the third is that it is impossible to produce chlorine-free high-purity germanium dioxide. Summary of the invention
[0007] The purpose of the present invention is to solve the shortcomings of the prior art and to propose an environmentally friendly, simple, fast and efficient new method for preparing high-quality chlorine-free high-purity germanium dioxide. The output rate of high-purity germanium dioxide in this method is as high as over 99%.
[0008] To achieve the above object, the present invention adopts the following technical solutions: A method for preparing chlorine-free high-purity germanium dioxide comprises an autoclave, wherein the autoclave comprises a body, an agitator, an air inlet and an air outlet, wherein the body is provided with an interlayer, and heat transfer oil is arranged in the interlayer; a discharge port is arranged at the bottom of the body, and the discharge port is connected to the inner cavity of the body; the agitator is installed in the inner cavity of the body; the air inlet and the air outlet are arranged on the body, and are respectively connected to the inner cavity of the body; the air inlet is provided with an air inlet valve, and the air outlet is provided with an air outlet valve; the body is also provided with a temperature sensor and a pressure sensor for monitoring the temperature and pressure in the inner cavity of the body; The following steps are involved: S1: Ball milling: crush the reduced germanium ingot, reduced germanium powder or zone melting germanium ingot and ball mill it to obtain high purity germanium powder; S2: charging: adding the high purity germanium powder and high purity water obtained in step S1 into the autoclave; S3: Positive pressure oxidation: Turn on the agitator to heat the autoclave by heating the heat transfer oil in the autoclave interlayer. After the temperature in the autoclave reaches the target temperature, the temperature is kept constant. At the same time, ozone is continuously introduced into the solution in the autoclave for positive pressure oxidation. After the positive pressure oxidation is completed, stop heating, and after the temperature drops to the limit value, close the agitator and exhaust valve of the autoclave. S4: High-pressure staged oxidation: ozone is introduced into the autoclave through the air inlet until the pressure in the autoclave reaches a certain limit, then ozone is stopped, the agitator is turned on to start stirring, and the autoclave is heated up in steps; in the first stage, the autoclave is heated up to the first stage target temperature and then kept at a constant temperature; in the second stage, the autoclave is heated up to the second stage target temperature and then kept at a constant temperature; in the third stage, heating is stopped and the temperature is lowered; S5: Nitrogen exhaust: stop stirring, open the exhaust valve, and introduce nitrogen through the air inlet to exhaust the gas in the kettle; S6: Stop the kettle and discharge the materials: Turn on the agitator to stir, and after the temperature in the kettle continues to drop to a certain value, discharge the materials in the kettle; S7: solid-liquid separation and drying: the material obtained in step S6 is subjected to solid-liquid separation, and the solid is dried to obtain a chlorine-free high-purity germanium dioxide product, and the liquid is high-purity water containing germanium, which is returned to step S2 for use as high-purity water.
[0009] Furthermore, it also includes: In step S1, the high-purity germanium powder after crushing and ball milling is sieved with 100-325 mesh; In step S2, the weight ratio of the high-purity germanium powder to the high-purity water is 1:3-10; the total volume of the input materials does not exceed 30% of the effective volume of the inner cavity of the autoclave; In step S3, during positive pressure oxidation, the pressure in the autoclave is controlled to be no more than 0.2 MPa, the target temperature in the autoclave is 95-105° C., and the temperature is kept constant for 2-6 hours; after the oxidation is completed, when the temperature in the autoclave drops to no more than 75° C., the agitator and exhaust valve of the autoclave are closed; In step S4, during the high-pressure staged oxidation process, ozone is introduced into the autoclave until the pressure in the autoclave reaches 0.2-0.8 MPa, the ozone is stopped, the agitator is turned on, and the autoclave is heated to 120-180° C. and kept at a constant temperature for 2-4 hours in the first stage; the autoclave is heated to 180-230° C. and kept at a constant temperature for 3-6 hours in the second stage; the heating is stopped in the third stage, and the temperature in the autoclave is reduced to no more than 70° C.; In step S5, the nitrogen is introduced for 10 to 30 minutes; In step S6, the material is discharged when the temperature in the kettle drops to no more than 40°C; In step S7, the solid is dried at a constant temperature of 100-220° C. for 6-12 hours to obtain chlorine-free high-purity germanium dioxide.
[0010] Furthermore, in step S1, the germanium powder after crushing and ball milling is sieved with 140-230 mesh.
[0011] Furthermore, in step S2, the weight ratio of the high-purity germanium powder and the high-purity water added is 1:3-6; and the total volume of the input materials accounts for 20-30% of the effective volume of the autoclave.
[0012] Furthermore, in step S3, the positive pressure oxidation controls the pressure in the autoclave to 0.12-0.18 MPa, the temperature in the autoclave to 95-105°C, and the temperature is kept constant for 2-6 hours; when the oxidation is completed and the temperature in the autoclave is 65-75°C, the stirring and exhaust valves of the autoclave are closed.
[0013] Furthermore, in step S4, during the high-pressure staged oxidation process, ozone is introduced into the autoclave until the pressure in the autoclave reaches 0.2-0.8 MPa, the ozone is stopped, the agitator is turned on, and the autoclave is heated to 120-180°C in the first stage and kept at a constant temperature for 2-4 hours; in the second stage, the autoclave is heated to 180-230°C and kept at a constant temperature for 3-6 hours; in the third stage, heating is stopped and the temperature in the autoclave is reduced to 65-70°C.
[0014] Furthermore, in step S5, the nitrogen is introduced for 10 to 20 minutes.
[0015] Furthermore, in step S6, the material is discharged when the temperature in the kettle drops to 25-40°C.
[0016] Furthermore, in step S7, the solid-liquid separation includes filtering, suction filtration or centrifugation; the solid is dried at 150-200° C. for 6-12 hours to obtain chlorine-free high-purity germanium dioxide.
[0017] Furthermore, in step S4, the temperature in the second stage autoclave is greater than the temperature in the first stage autoclave, and the pressure in the second stage autoclave is greater than the pressure in the first stage autoclave.
[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention adopts the metal germanium ozone high-pressure oxidation process to produce high-value chlorine-free high-purity germanium dioxide, the production process is simple, the production is efficient and low-cost; and the germanium metal conversion rate is high, and the output rate of high-purity germanium dioxide is greater than 99%. At the same time, the present invention has obvious clean characteristics: only ozone, nitrogen, etc. are used in auxiliary materials, and no wastewater and waste residue are generated in the entire process, and the environmental benefits are significant. (2) The present invention directly prepares chlorine-free high-purity germanium dioxide from metal germanium; and has the advantages of high product output rate, simple process operation, and environmental friendliness. The preparation can be completed using only an autoclave, which is convenient for industrial preparation, easy to use, simple and fast to operate, and highly safe. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is a schematic structural diagram of an autoclave for the method for preparing chlorine-free high-purity germanium dioxide according to Example 1 of the present invention; Figure 2 The present invention is a flow chart of the steps of the method for preparing chlorine-free high-purity germanium dioxide. DETAILED DESCRIPTION
[0020] In order to provide a further understanding of the purpose, structure, features, and functions of the present invention, the following detailed description is given in conjunction with the embodiments.
[0021] like Figure 1As shown, a method for preparing chlorine-free high-purity germanium dioxide includes an autoclave, the autoclave includes a body 1, an agitator 2, an air inlet 3 and an exhaust port 4, the body 1 is provided with an interlayer 11, a heat transfer oil is arranged in the interlayer 11, and a heater 12 is also arranged in the interlayer 11; a discharge port 13 is arranged at the bottom of the body 1, the discharge port 13 is connected to the inner cavity of the body, the agitator 2 is installed in the inner cavity of the body 1, the motor of the agitator 2 is installed on the top of the body 1, and the stirring blade extends into the inner cavity. The air inlet 3 and the exhaust port 4 are arranged on the body 1, respectively connected to the inner cavity of the body 1, the air inlet 3 is provided with an air inlet valve, and the exhaust port 4 is provided with an exhaust valve; there are at least two air inlets 3, one is connected to ozone, and the other is connected to nitrogen, and the air inlet valve controls the on-off to create reaction conditions. The air intake and exhaust are controlled to achieve the high-pressure requirement of the reaction, and the reaction gas can be introduced to react and prepare high-purity germanium dioxide. The body 1 is also provided with a temperature sensor 14 and a pressure sensor 15 for monitoring the temperature and pressure in the inner cavity of the body 1; a control system is also provided, and the control system is electrically connected with the heater 12, the air inlet valve, the air exhaust valve, the temperature sensor 14 and the pressure sensor 15, etc., for setting and controlling the temperature and pressure of the autoclave to ensure that the environment in the autoclave meets the preparation requirements and obtains a high-purity product. The high-temperature and pressurized environment accelerates the reaction rate and improves production efficiency.
[0022] like Figure 2 , including the following steps: S1: Ball milling: crush the reduced germanium ingot, reduced germanium powder or zone melting germanium ingot and ball mill it to obtain high purity germanium powder.
[0023] S2: Charging: Add the high-purity germanium powder and high-purity water obtained in step S1 into the autoclave.
[0024] S3: Positive pressure oxidation: Start stirring and heat the autoclave by heating the heat transfer oil in the autoclave interlayer. The contact area between the hot oil and the autoclave body is large, and the temperature distribution is more uniform, which prevents local overheating or cooling and ensures the stability of the process. After the temperature in the autoclave reaches the set temperature, the temperature is kept constant, and ozone is continuously introduced into the solution in the autoclave for positive pressure oxidation; after the positive pressure oxidation is completed, stop heating, and after the temperature drops to the limit value, close the stirring and exhaust valve of the autoclave.
[0025] S4: High-pressure staged oxidation: ozone is introduced into the autoclave until the pressure inside the autoclave reaches a certain limit, then the introduction of ozone into the autoclave is stopped, stirring is started, and the temperature of the autoclave is increased; in the first stage, the temperature of the autoclave is increased to the lower temperature set in the first stage and then the temperature is maintained constant; in the second stage, the temperature of the autoclave is increased to the higher temperature set in the second stage and then the temperature is maintained constant; in the third stage, heating is stopped and the temperature is lowered.
[0026] S5: Exhaust with nitrogen: Stop stirring, open the exhaust valve, and introduce nitrogen to exhaust the gas in the kettle.
[0027] S6: Stop the kettle and discharge the materials: Turn on the agitator to stir, and after the temperature in the kettle continues to drop to a certain value, discharge the materials in the kettle.
[0028] S7: solid-liquid separation and drying: the material obtained in step S6 is subjected to solid-liquid separation, and the solid is dried to obtain a chlorine-free high-purity germanium dioxide product, and the liquid is high-purity water containing germanium, which can be returned to step S2 for use as high-purity water.
[0029] Preferably, in step S1, the germanium powder after crushing and ball milling is sieved with 140-230 meshes, which not only ensures that the germanium powder has a suitable particle size, but also avoids clogging of the sieve holes, improves the sieving rate, and ensures the efficiency of industrial production.
[0030] Preferably, in step S2, the weight ratio of the high-purity germanium powder to the high-purity water is 1:3-6; the total volume of the input materials accounts for 20-30% of the effective volume of the autoclave. It is ensured that the high-purity water can dissolve the germanium dioxide generated by surface oxidation, so that the exposed germanium powder can be fully oxidized. And the processing volume is controlled to ensure the yield.
[0031] Preferably, in step S3, the positive pressure oxidation controls the pressure in the autoclave to 0.12-0.18 MPa, the temperature in the autoclave to 95-105°C, and the temperature is kept constant for 2-6 hours; when the oxidation is completed and the temperature in the autoclave is 65-75°C, the stirring and exhaust valves of the autoclave are closed.
[0032] Preferably, in step S4, ozone is introduced into the kettle during the high-pressure segmented oxidation process until the pressure in the kettle reaches 0.2-0.8Mpa, the ozone is stopped, stirring is started, the autoclave is heated to 120-180°C in the first stage, and the temperature is kept constant for 2-4 hours; the autoclave is heated to 180-230°C in the second stage, and the temperature is kept constant for 3-6 hours; the heating is stopped in the third stage, and the temperature in the kettle is reduced to 65-70°C. The oxidation to generate germanium dioxide is performed by oxidizing in a staged gradient heating manner to ensure a more complete oxidation process, improve the purity and uniformity of the product, and optimize the reaction rate through high pressure, promote crystal growth, promote crystal agglomeration or merging, thereby forming larger particles or a tighter structure, improving the crystal quality, and ensuring a high yield.
[0033] Preferably, in step S5, the nitrogen is introduced for 10 to 20 minutes, which is a short time to ensure production efficiency and reduce the waste of time and nitrogen. The residual ozone in the kettle is discharged to avoid affecting the health of the heating and prevent potential safety hazards. Nitrogen is an inert gas and is not easy to react chemically with other substances, so the stability of the reaction is maintained, impurities are avoided, and the purity of germanium dioxide is ensured.
[0034] Preferably, in step S6, the material is discharged when the temperature in the kettle drops to 25-40° C. This ensures that the temperature in the kettle is relatively low, does not cause the risk of scalding, and improves the safety of the preparation.
[0035] Preferably, in step S7, solid-liquid separation can be performed by filtering, suction filtration or centrifugation; the solid is dried at 150-200° C. and constant temperature for 6-12 hours to obtain the product chlorine-free high-purity germanium dioxide.
[0036] The present invention increases the surface area of the metal germanium through step S1 to improve the speed and efficiency of the subsequent ozone oxidation reaction on the material.
[0037] The present invention uses an autoclave as a reaction container in step S2 to meet the high temperature and high pressure requirements of the high-pressure segmented oxidation in step S4 to ensure the adequacy of the oxidation of metallic germanium; high-purity water is used as a reaction medium, firstly, water can dissolve the germanium dioxide that has been oxidized on the surface of the germanium powder, thereby exposing the germanium element and preventing the germanium dioxide from wrapping the germanium metal so as to make the reaction sufficient; secondly, high-purity water will not bring in impurities and contamination; controlling the ratio of feed to water and the total input volume of the material is to ensure the maximization of production capacity while ensuring the thoroughness of the oxidation.
[0038] In the present invention, in step S3, under the condition of positive pressure and temperature of 95-105° C. in the kettle, ozone oxidizes germanium metal into germanium dioxide, and the reaction equations are shown in (1) and (2).
[0039] 3Ge+2O3=3GeO2 (1) Ge +2O3=GeO2+ 2O2 (2) The present invention accelerates the oxidation of germanium powder by ozone at a temperature of 120-180° C. in the first stage through step S4; further accelerates the oxidation of germanium powder by ozone at a higher temperature of 180-230° C. and pressure in the kettle in the second stage; and adopts a gradient heating method, the pressure in the kettle also increases gradually, the oxidation speed and oxidation degree of germanium are gradually improved, and energy consumption is saved while ensuring full oxidation of germanium powder.
[0040] The present invention uses nitrogen to discharge other substances remaining in the kettle through step S5 to eliminate potential safety hazards when opening the kettle.
[0041] The present invention discharges the material when the kettle temperature drops to no more than 40° C. in step S6 to eliminate the risk of scalding during operation.
[0042] The chlorine-free high-purity germanium dioxide obtained in step S7 of the present invention can be sold directly, and the product meets the requirements of the national standard GB / T11069 "High-purity germanium dioxide" and does not contain chloride ions; the water separated from the solid and liquid is returned to step S2 to achieve the recycling of water resources. Example
[0043] S1: Ball milling: crush the reduced germanium powder and ball mill it to obtain high-purity germanium powder; sieve it through 230 mesh.
[0044] S2: Loading: Add the high-purity germanium powder and high-purity water obtained in step S1 into the autoclave, wherein the weight ratio of the high-purity germanium powder to the high-purity water is 1:3; and the total volume of the input materials is 30% of the effective volume of the autoclave.
[0045] S3: Positive pressure oxidation: Start stirring and heat the autoclave by heating the heat transfer oil in the autoclave interlayer. After the temperature in the autoclave reaches 105°C, keep the temperature constant for 6 hours. At the same time, continuously introduce ozone into the solution in the autoclave for positive pressure oxidation, and keep the pressure in the autoclave at 0.16-0.18Mpa. Stop heating after the positive pressure oxidation, and close the stirring and exhaust valve of the autoclave when the temperature drops to 75°C.
[0046] S4: High-pressure staged oxidation: ozone is introduced into the autoclave until the pressure inside the autoclave reaches 0.7Mpa, then the introduction of ozone into the autoclave is stopped, stirring is started, and the temperature of the autoclave is increased; in the first stage, the temperature of the autoclave is increased to 180°C and kept at a constant temperature for 4 hours; in the second stage, the temperature of the autoclave is increased to 230°C and kept at a constant temperature for 6 hours; in the third stage, heating is stopped and the autoclave temperature is reduced to 70°C.
[0047] S5: Exhaust with nitrogen: Stop stirring, open the exhaust valve, and introduce nitrogen for 20 minutes to exhaust the gas in the kettle.
[0048] S6: Stop the kettle and discharge the materials: Start stirring, and after the temperature in the kettle continues to drop to 30°C, discharge the materials in the kettle.
[0049] S7: Solid-liquid separation and drying: Solid-liquid separation and drying: The material obtained in step S6 is subjected to solid-liquid separation by suction filtration, and the solid is dried at 200°C and a constant temperature for 8 hours to obtain the product of chlorine-free high-purity germanium dioxide; the liquid is high-purity water containing germanium, which is returned to step S2 for use as high-purity water.
[0050] Chlorine-free high-purity germanium dioxide was obtained by the method of this embodiment, and its purity was tested. Finally, the yield of chlorine-free high-purity germanium dioxide was 99.7%. Example
[0051] S1: Ball milling: crush the reduced germanium ingot and ball mill it to obtain high-purity germanium powder; sieve it through 140 mesh; S2: Loading: Add the high-purity germanium powder and high-purity water obtained in step S1 into the autoclave, wherein the weight ratio of the high-purity germanium powder to the high-purity water is 1:6; and the total volume of the input materials is 20% of the effective volume of the autoclave.
[0052] S3: Positive pressure oxidation: Start stirring and heat the autoclave by heating the heat transfer oil in the autoclave interlayer. After the temperature in the autoclave reaches 98°C, keep the temperature constant for 4 hours. At the same time, continuously introduce ozone into the solution in the autoclave for positive pressure oxidation, and keep the pressure in the autoclave at 0.12-0.14Mpa. Stop heating after the positive pressure oxidation, and close the stirring and exhaust valve of the autoclave when the temperature drops to 65°C.
[0053] S4: High-pressure staged oxidation: ozone is introduced into the autoclave until the pressure inside the autoclave reaches 0.5Mpa, then the introduction of ozone into the autoclave is stopped, stirring is started, and the temperature of the autoclave is increased; in the first stage, the temperature of the autoclave is increased to 140°C and kept at a constant temperature for 3 hours; in the second stage, the temperature of the autoclave is increased to 210°C and kept at a constant temperature for 4 hours; in the third stage, heating is stopped and the autoclave temperature is reduced to 65°C.
[0054] S5: Exhaust with nitrogen: Stop stirring, open the exhaust valve, and introduce nitrogen for 10 minutes to exhaust the gas in the kettle.
[0055] S6: Stop the kettle and discharge the materials: Start stirring, and after the temperature in the kettle continues to drop to 40°C, discharge the materials in the kettle.
[0056] S7: solid-liquid separation and drying: the material obtained in step S6 is subjected to solid-liquid separation by centrifugation, and the solid is dried at 150°C for 12 hours to obtain the product of chlorine-free high-purity germanium dioxide; the liquid is high-purity water containing germanium, which is returned to step S2 for use as high-purity water.
[0057] Chlorine-free high-purity germanium dioxide was obtained by the method of this embodiment, and its purity was tested. Finally, the yield of chlorine-free high-purity germanium dioxide was 99.2%. Example
[0058] S1: Ball milling: crush the reduced germanium powder and ball mill it to obtain high-purity germanium powder; sieve it through 200 mesh.
[0059] S2: Loading: Add the high-purity germanium powder and high-purity water obtained in step S1 into the autoclave, wherein the weight ratio of the high-purity germanium powder to the high-purity water is 1:4; and the total volume of the input materials is 25% of the effective volume of the autoclave.
[0060] S3: Positive pressure oxidation: Start stirring and heat the autoclave by heating the heat transfer oil in the autoclave interlayer. After the temperature in the autoclave reaches 100°C, keep the temperature constant for 5 hours. At the same time, continuously introduce ozone into the solution in the autoclave for positive pressure oxidation, and keep the pressure in the autoclave at 0.13-0.16Mpa. Stop heating after the positive pressure oxidation, and close the stirring and exhaust valve of the autoclave when the temperature drops to 70°C.
[0061] S4: High-pressure staged oxidation: ozone is introduced into the autoclave until the pressure inside the autoclave reaches 0.6Mpa, then the introduction of ozone into the autoclave is stopped, stirring is started, and the temperature of the autoclave is increased; in the first stage, the temperature of the autoclave is increased to 170°C and kept at a constant temperature for 4 hours; in the second stage, the temperature of the autoclave is increased to 220°C and kept at a constant temperature for 5 hours; in the third stage, heating is stopped and the autoclave temperature is reduced to 65°C.
[0062] S5: Exhaust gas by nitrogen: Stop stirring, open the exhaust valve, and introduce nitrogen for 15 minutes to exhaust the gas in the kettle.
[0063] S6: Stop the kettle and discharge the materials: Start stirring, and after the temperature in the kettle continues to drop to 35°C, discharge the materials in the kettle.
[0064] S7: solid-liquid separation and drying: the material obtained in step S6 is filtered to separate the solid from the liquid, and the solid is dried at 190°C for 12 hours to obtain the product of chlorine-free high-purity germanium dioxide; the liquid is high-purity water containing germanium, which is returned to step S2 for use as high-purity water.
[0065] Chlorine-free high-purity germanium dioxide was obtained by the method of this embodiment, and its purity was tested. Finally, the yield of chlorine-free high-purity germanium dioxide was 99.6%.
[0066] In summary, the present invention adopts the metal germanium ozone high-pressure oxidation process to produce high-value chlorine-free high-purity germanium dioxide, the production process is simple, the production is efficient and low-cost; and the germanium metal conversion rate is high, and the output rate of high-purity germanium dioxide is greater than 99%. At the same time, the present invention has obvious cleaning characteristics: only ozone, nitrogen, etc. are used in the auxiliary materials, and no wastewater and waste residue are generated in the entire process, and the environmental benefits are significant.
[0067] The present invention has been described by the above-mentioned relevant embodiments, however, the above-mentioned embodiments are only examples for implementing the present invention. It must be pointed out that the disclosed embodiments do not limit the scope of the present invention. On the contrary, changes and modifications made without departing from the spirit and scope of the present invention are all within the scope of patent protection of the present invention.
Claims
1. A method for preparing chlorine-free high-purity germanium dioxide, characterized in that: The invention comprises a high pressure autoclave, wherein the high pressure autoclave comprises a body, an agitator, an air inlet and an air outlet, wherein the body is provided with an interlayer, and heat transfer oil is arranged in the interlayer; a discharge port is arranged at the bottom of the body, and the discharge port is connected to the inner cavity of the body; the agitator is installed in the inner cavity of the body; the air inlet and the air outlet are arranged on the body, and are respectively connected to the inner cavity of the body; the air inlet is provided with an air inlet valve, and the air outlet is provided with an air outlet valve; The body is also provided with a temperature sensor and a pressure sensor for monitoring the temperature and pressure in the inner cavity of the body; The following steps are involved: S1: Ball milling: crush the reduced germanium ingot, reduced germanium powder or zone melting germanium ingot and ball mill it to obtain high purity germanium powder; S2: charging: adding the high purity germanium powder and high purity water obtained in step S1 into the autoclave; S3: Positive pressure oxidation: Turn on the agitator to heat the autoclave by heating the heat transfer oil in the autoclave interlayer. After the temperature in the autoclave reaches the target temperature, the temperature is kept constant. At the same time, ozone is continuously introduced into the solution in the autoclave for positive pressure oxidation. After the positive pressure oxidation is completed, stop heating, and after the temperature drops to the limit value, close the agitator and exhaust valve of the autoclave. S4: High-pressure staged oxidation: ozone is introduced into the autoclave through the air inlet until the pressure in the autoclave reaches a certain limit, then the introduction of ozone into the autoclave is stopped, the agitator is turned on to start stirring, and the autoclave is heated stepwise; in the first stage, the autoclave is heated to the first stage target temperature and then kept at a constant temperature; In the second stage, the autoclave is heated to the target temperature of the second stage and then kept at a constant temperature; in the third stage, heating is stopped and the temperature is lowered; S5: Nitrogen exhaust: stop stirring, open the exhaust valve, and introduce nitrogen through the air inlet to exhaust the gas in the kettle; S6: Stop the kettle and discharge the materials: Turn on the agitator to stir, and after the temperature in the kettle continues to drop to a certain value, discharge the materials in the kettle; S7: solid-liquid separation and drying: the material obtained in step S6 is subjected to solid-liquid separation, and the solid is dried to obtain a chlorine-free high-purity germanium dioxide product, and the liquid is high-purity water containing germanium, which is returned to step S2 for use as high-purity water.
2. The method for preparing chlorine-free high-purity germanium dioxide as claimed in claim 1, characterized in that: Also includes: In step S1, the high-purity germanium powder after crushing and ball milling is sieved with 100-325 mesh; In step S2, the weight ratio of the high-purity germanium powder to the high-purity water is 1:3-10; the total volume of the input materials does not exceed 30% of the effective volume of the inner cavity of the autoclave; In step S3, during positive pressure oxidation, the pressure in the autoclave is controlled to be no more than 0.2 MPa, the target temperature in the autoclave is 95-105° C., and the temperature is kept constant for 2-6 hours; after the oxidation is completed, when the temperature in the autoclave drops to no more than 75° C., the agitator and exhaust valve of the autoclave are closed; In step S4, during the high-pressure staged oxidation process, ozone is introduced into the autoclave until the pressure in the autoclave reaches 0.2-0.8 MPa, the ozone is stopped, the agitator is turned on, and the autoclave is heated to 120-180° C. and kept at a constant temperature for 2-4 hours in the first stage; the autoclave is heated to 180-230° C. and kept at a constant temperature for 3-6 hours in the second stage; the heating is stopped in the third stage, and the temperature in the autoclave is reduced to no more than 70° C.; In step S5, the nitrogen is introduced for 10 to 30 minutes; In step S6, the material is discharged when the temperature in the kettle drops to no more than 40°C; In step S7, the solid is dried at a constant temperature of 100-220° C. for 6-12 hours to obtain chlorine-free high-purity germanium dioxide.
3. The method for preparing chlorine-free high-purity germanium dioxide as claimed in claim 1, characterized in that: In step S1, the germanium powder after crushing and ball milling is sieved with 140-230 mesh.
4. The method for preparing chlorine-free high-purity germanium dioxide as claimed in claim 1, characterized in that: In step S2, the weight ratio of the added amount of high-purity germanium powder and high-purity water is 1:3-6; the total volume of the input materials accounts for 20-30% of the effective volume of the autoclave.
5. The method for preparing chlorine-free high-purity germanium dioxide as claimed in claim 1, characterized in that: In step S3, the positive pressure oxidation controls the pressure in the autoclave to 0.12-0.18 MPa and the temperature in the autoclave to 95-105°C for 2-6 hours; when the oxidation is completed and the temperature in the autoclave is 65-75°C, the stirring and exhaust valves of the autoclave are closed.
6. The method for preparing chlorine-free high-purity germanium dioxide according to claim 1, characterized in that: In step S4, during the high-pressure staged oxidation process, ozone is introduced into the autoclave until the pressure in the autoclave reaches 0.2-0.8 MPa, the ozone is stopped, the agitator is turned on, and the autoclave is heated to 120-180° C. and kept at a constant temperature for 2-4 hours in the first stage; the autoclave is heated to 180-230° C. and kept at a constant temperature for 3-6 hours in the second stage; and the heating is stopped in the third stage, and the temperature in the autoclave is reduced to 65-70° C.
7. The method for preparing chlorine-free high-purity germanium dioxide according to claim 1, characterized in that: In step S5, the nitrogen gas is introduced for 10 to 20 minutes.
8. The method for preparing chlorine-free high-purity germanium dioxide as claimed in claim 1, characterized in that: In step S6, the material is discharged when the temperature in the kettle drops to 25-40°C.
9. The method for preparing chlorine-free high-purity germanium dioxide according to claim 1, characterized in that: In step S7, the solid-liquid separation includes filtering, suction filtration or centrifugation; the solid is dried at 150-200° C. for 6-12 hours to obtain chlorine-free high-purity germanium dioxide.
10. The method for preparing chlorine-free high-purity germanium dioxide according to claim 1, characterized in that: In step S4, the temperature in the second stage autoclave is higher than the temperature in the first stage autoclave, and the pressure in the second stage autoclave is higher than the pressure in the first stage autoclave.