Multi-stage gradient distillation impurity removal device for germanium purification and purification method

Abstract

The invention discloses a multi-stage gradient distillation impurity removal device for germanium purification and a purification method, and relates to the technical field of rare metal purification. Through the multi-stage gradient design of first-stage distillation, second-stage re-distillation arsenic removal and third-stage rectification, a directional and synergistic separation mechanism based on the physical and chemical property difference of impurities is constructed; the first-stage distillation unit selectively volatilizes part of impurities with lower boiling points preferentially by controlling lower temperature and pressure, and high-boiling-point metal chlorides are retained at the bottom of a kettle due to insufficient saturated vapor pressure, so that first-stage crude separation is realized, and the second-stage re-distillation arsenic removal unit introduces chlorine gas, so that the high-boiling-point metal chlorides are separated from the bottom of the kettle; the three-stage rectification unit is used for oxidizing volatile arsenic impurities into non-volatile arsenic acid in situ, targeted chemical fixation and separation are realized, and the three-stage rectification unit is used for ultimate fine separation of trace impurities with similar boiling points on the basis of removal of high-boiling-point and specific impurities in the first two stages, so that fine separation based on relative volatility is realized.

Description

Technical Field

[0001] This invention relates to the field of rare metal purification technology, specifically to a multi-stage gradient distillation apparatus and purification method for germanium purification. Background Technology

[0002] Germanium, as a key rare metal, plays an irreplaceable role in high-tech fields such as optical fiber communication, infrared thermal imaging, solar cells, high-speed semiconductor devices, and nuclear radiation detectors due to its unique semiconductor properties and high infrared transmittance. High-purity germanium with a purity of ≥99.999% is the material basis for these high-end applications, and its purity directly determines the performance and reliability of the final device. Currently, the mainstream process for large-scale industrial preparation of high-purity germanium is the chlorination distillation method, which involves reacting germanium concentrate or germanium-containing smelting slag with hydrochloric acid to generate volatile germanium tetrachloride. Then, taking advantage of the difference in boiling points between germanium tetrachloride and various impurity chlorides, it is separated and purified by distillation.

[0003] However, traditional chlorination distillation processes have significant limitations in achieving deep impurity removal. Existing technologies mostly employ relatively simple single-stage distillation or discrete multi-step processing, the main drawbacks of which are: firstly, a single distillation process is insufficient to handle complex impurity profiles, with boiling points much higher than [the specified value]. While impurities are easily separated, impurities with similar boiling points are easily azeotropically distilled out, leading to incomplete separation. Secondly, for the critical impurity arsenic, a separate subsequent oxidation-re-distillation process is often required, which is lengthy and has stringent requirements for controlling the amount of chlorine introduced and the reaction conditions, easily causing operational instability or secondary pollution. These factors together result in traditional processes having problems such as large fluctuations in product purity, limited ability to remove specific impurities, high overall energy consumption, and long and complex process flow, which restricts further improvement in the quality of high-purity germanium products and reduction in cost.

[0004] Therefore, there is an urgent need in this field for a distillation purification technology and apparatus that can solve the above problems in an integrated and precise manner. This is of great practical significance for breaking through the bottleneck in the preparation of high-purity germanium and stably and efficiently producing high-purity or even ultra-high-purity germanium products that meet the needs of cutting-edge technology applications. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a multi-stage gradient distillation purification device and method for germanium purification. It utilizes a multi-stage gradient design—primary distillation, secondary redistillation for arsenic removal, and tertiary rectification—to construct a directional and synergistic separation mechanism based on the differences in the physicochemical properties of impurities. The primary distillation unit selectively removes impurities by controlling lower temperatures and pressures. The process involves preferentially evaporating some lower-boiling-point impurities, while high-boiling-point metal chlorides remain at the bottom of the vessel due to insufficient saturated vapor pressure, achieving the first stage of coarse separation. The second-stage re-distillation arsenic removal unit introduces chlorine gas to oxidize volatile arsenic impurities in situ into non-volatile arsenic acid, achieving targeted chemical fixation and separation. The third-stage distillation unit, based on the removal of high-boiling-point and specific impurities in the first two stages, performs final fine separation of trace impurities with similar boiling points, achieving fine separation based on relative volatility. This phased, gradient impurity removal logic, with each stage having its own focus, allows each unit to operate under optimal conditions, thereby achieving efficient, deep, and synergistic removal of impurities.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: On the one hand, a multi-stage gradient distillation and impurity removal device for germanium purification, the device comprising a primary distillation unit, a secondary redistillation arsenic removal unit, a tertiary rectification and purification unit, a condensation and collection unit, and an intelligent control unit connected in sequence by pipelines;

[0007] The primary distillation unit is used to perform a chlorination reaction on germanium-containing materials and to perform preliminary separation of the generated crude germanium tetrachloride vapor in order to remove high-boiling-point impurities.

[0008] The secondary redistillation arsenic removal unit is connected to the outlet of the primary distillation unit and is used to introduce chlorine gas to oxidize the germanium fraction from the primary distillation unit, converting arsenic trichloride into arsenic acid, and achieving deep arsenic removal through distillation.

[0009] The three-stage distillation purification unit is connected to the outlet of the two-stage re-distillation arsenic removal unit and is used to perform fine distillation on the arsenic-removed germanium tetrachloride to remove trace impurities with boiling points close to those of germanium tetrachloride and obtain high-purity germanium tetrachloride.

[0010] The condensation and collection unit is connected to the steam outlets of the first-stage distillation unit, the second-stage re-distillation arsenic removal unit, and the third-stage rectification and purification unit, respectively, and is used to perform gradient condensation and collection of the steam generated at each stage.

[0011] The intelligent control unit is electrically connected to the signal detection and actuation elements of the above-mentioned units, and is used to monitor and automatically regulate the temperature, pressure, and flow parameters of the entire device in real time.

[0012] Furthermore, the primary distillation unit includes a primary chlorination distillation vessel and a primary condenser connected to the outlet of the primary chlorination distillation vessel;

[0013] The secondary re-evaporation arsenic removal unit includes a secondary re-evaporation tower, a chlorine gas introduction system for introducing chlorine gas into the secondary re-evaporation tower, and a secondary condenser connected to the outlet of the secondary re-evaporation kettle;

[0014] The three-stage distillation purification unit includes a distillation kettle, a distillation column connected to the top of the distillation kettle, and a top condenser connected to the top of the distillation column.

[0015] Furthermore, the operating parameters of the primary chlorination distillation vessel are: temperature 80-120℃, pressure 0.1-0.3MPa, and distillation time 4-6h;

[0016] The operating parameters of the secondary re-distillation tower are: temperature 80-160℃, pressure 0.1-0.3MPa, and distillation time 3-5h;

[0017] The operating parameters of the three-stage distillation purification unit are: distillation kettle temperature 80-120℃, distillation column top temperature 83-85℃, reflux ratio 4:1, and distillation time 6-8h.

[0018] Furthermore, the first-stage condenser uses 0-5℃ cooling water, the second-stage condenser uses 0-5℃ cooling water, and the third-stage condenser uses 0-5℃ cooling water.

[0019] On the other hand, a multi-stage gradient distillation purification method for germanium purification includes the following specific steps:

[0020] S100, Raw material pretreatment: The germanium-containing smelting slag is crushed and ground, mixed with hydrochloric acid to make a slurry, and impurities are removed to obtain a uniform slurry suitable for distillation;

[0021] S200, First-stage gradient distillation and preliminary impurity removal: The uniform slurry is fed into the first-stage distillation unit and chlorinated distillation is carried out at 80-120℃ and 0.1-0.3MPa for 4-6 hours. The generated mixed steam is led out to the first-stage condenser. Low-boiling-point impurities are condensed and collected in the impurity storage tank. The uncondensed germanium tetrachloride liquid is transported through pipeline to the second-stage re-distillation arsenic removal unit.

[0022] S300, Secondary Re-distillation and Deep Arsenic Removal: The germanium tetrachloride liquid is transported into the secondary re-distillation tower through a pipeline. Pure hydrochloric acid with a volume of 25-33% of germanium tetrachloride is introduced into the tower. The temperature inside the tower is controlled at 80-120℃ and the pressure at 0.2-0.4MPa. Distillation is carried out for 3-5 hours. The germanium tetrachloride liquid enters the secondary condenser and, after preliminary condensation, enters the tertiary rectification and purification unit.

[0023] S400, three-stage distillation and fine purification: The initially condensed germanium tetrachloride liquid is sent to the distillation kettle and heated to 80-120℃. The top temperature of the distillation column is controlled at 83-85℃ and the reflux ratio is 4:1. After distillation for 6-8 hours, the high-boiling-point impurities at the bottom of the column are discharged, and the pure germanium tetrachloride vapor at the top of the column enters the top condenser. After complete condensation, high-purity germanium tetrachloride is obtained by stratification.

[0024] S500, hydrolysis and reduction refining: The high-purity germanium tetrachloride obtained from S400 is hydrolyzed, reduced and zone smelted to finally prepare ultra-high purity zone smelting germanium ingots.

[0025] Furthermore, in step S100, the germanium content of the germanium-containing smelting slag is 1-3%, and a slurry is prepared by stirring at 20-50℃ and 50-100 r / min for 30-60 min. The impurity components include 10-15% Zn, 6-8% Pb, and 6-8% [unspecified component]. 8-15% Fe, 8-12% Al.

[0026] Furthermore, the hydrolysis process in S500 is as follows: high-purity germanium tetrachloride obtained from S400 and ultrapure water are added to a tetrafluoroethylene-lined hydrolysis reactor at a volume ratio of 1:3. The temperature is controlled at 8-12℃, and the reaction is stirred for 2-3 hours to generate germanium dioxide and hydrochloric acid. After the reaction solution is filtered and washed with water, it is dried at 120℃ and calcined at 800℃ for 2 hours to obtain high-purity germanium dioxide.

[0027] Furthermore, the reduction process in S500 is as follows: high-purity germanium dioxide is loaded into a high-purity graphite boat, placed in a tunnel reduction furnace, high-purity hydrogen is introduced, and reduction is carried out according to the procedure of preheating section, main reaction section, melting section, and cooling section to obtain reduced germanium ingot with a purity >99.999%.

[0028] The temperature of the preheating section is 450-500℃, and the time is 30 minutes.

[0029] The temperature of the main reaction section is 680-720℃, and the time is 2 hours.

[0030] The temperature of the melting section is 1000-1100℃, and the time is 1 hour.

[0031] Furthermore, the zone melting process in S500 is as follows: the reduced germanium ingot is taken out of the reduction furnace, its surface is cleaned with alkaline solution, it is broken and placed into a high-purity graphite boat in the zone melting furnace. An induction heating zone melting furnace is used, with a melting zone width of 15-20 mm and a moving speed of 1.5-2.5 mm / min. The flow rate is controlled at 50-80 mL / min under a high-purity hydrogen protective atmosphere for 8-12 cycles of melting. After melting is completed, the ingot is cooled, removed, and its surface is cleaned to obtain an ultra-high purity zone melting germanium ingot with a purity >99.9999%. The ingot with a purity <99.9999% is then re-zone melted.

[0032] Compared with existing technologies, this multi-stage gradient distillation purification device and method for germanium purification has the following advantages:

[0033] I. This invention constructs a directional and synergistic separation mechanism based on the differences in the physicochemical properties of impurities through a multi-stage gradient design of primary distillation, secondary redistillation for arsenic removal, and tertiary rectification. The primary distillation unit selectively removes impurities by controlling lower temperatures and pressures. The process involves preferentially evaporating some lower-boiling-point impurities, while high-boiling-point metal chlorides remain at the bottom of the vessel due to insufficient saturated vapor pressure, achieving the first stage of coarse separation. The second-stage re-distillation arsenic removal unit introduces chlorine gas to oxidize volatile arsenic impurities in situ into non-volatile arsenic acid, achieving targeted chemical fixation and separation. The third-stage distillation unit, based on the removal of high-boiling-point and specific impurities in the first two stages, performs final fine separation of trace impurities with similar boiling points, achieving fine separation based on relative volatility. This phased, gradient impurity removal logic, with each stage having its own focus, allows each unit to operate under optimal conditions, thereby achieving efficient, deep, and synergistic removal of impurities.

[0034] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0036] Figure 1 A flowchart illustrating the steps of a multi-stage gradient distillation purification method for germanium extraction.

[0037] Figure 2 This is a schematic diagram of the overall structure of a multi-stage gradient distillation and impurity removal device for germanium purification.

[0038] Figure 3 This is an overall process flow diagram of S500 in a multi-stage gradient distillation purification method for germanium purification. Detailed Implementation

[0039] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0040] Example 1

[0041] The multi-stage gradient distillation and impurity removal device used in the embodiment for germanium purification consists of a primary distillation unit, a secondary redistillation arsenic removal unit, a tertiary rectification and purification unit, a condensation and collection unit, and an intelligent control unit connected sequentially by pipelines, as follows: Figure 2 As shown, the process flow and connection logic of each unit in the process from germanium-containing smelting slag raw material to the final ultra-high purity zone-melted germanium ingot production are presented, providing an intuitive process guide for the entire purification process.

[0042] (I) Specific structure and parameters of each unit

[0043] The primary distillation unit includes a primary chlorination distillation vessel and a primary condenser. The primary chlorination distillation vessel has an effective volume of 3000L and is made of enamel to resist corrosion from hydrochloric acid during the chlorination reaction. Its operating parameters are as follows: temperature set at 80-120℃, specifically 100℃ in this embodiment; pressure controlled at 0.1-0.3MPa, set at 0.2MPa here; distillation time at 4-6h, determined to be 5h in this embodiment. The primary condenser is equipped with a 20-30℃ cooling water circulation system, and 25℃ cooling water is used in this embodiment for the initial condensation of the mixed vapor generated by the primary chlorination distillation vessel.

[0044] The secondary re-distillation arsenic removal unit consists of a secondary re-distillation tower, a chlorine introduction system, and a secondary condenser. The effective volume of the secondary re-distillation tower is 0.5 m³, and it is also made of enamel. The operating parameters are set as follows: temperature 80-120℃, 100℃ in this embodiment; pressure 0.1-0.3 MPa, set to 0.2 MPa; distillation time 3-5 h, determined to be 4 h. The chlorine introduction system is controlled at 5-10 L / min. In this embodiment, based on the arsenic content in the raw material, the introduction rate is set to 8 L / min to ensure that arsenic trichloride can be fully oxidized to arsenic acid. The secondary condenser uses 0-5℃ cooling water for condensation.

[0045] The three-stage distillation purification unit includes a distillation kettle, a distillation column, and a top condenser. The effective volume of the distillation kettle is 50L, and it is made of quartz to avoid contamination by metal impurities. The distillation column is also made of quartz, and the number of trays is set to more than 50 to ensure distillation efficiency. The operating parameters are set as follows: distillation kettle temperature 80-120℃, 100℃ in this embodiment; distillation column top temperature 83-85℃, set to 84℃; reflux ratio 4:1; distillation time 6-8h, set to 7h. The top condenser uses -196℃ liquid nitrogen for deep condensation to ensure that pure germanium tetrachloride vapor can be completely condensed.

[0046] The intelligent control unit is electrically connected to the signal detection elements such as temperature sensors, pressure sensors, and flow sensors of the above-mentioned units, as well as the actuators such as heating devices, valves, and chlorine introduction pumps, through wires. It can collect parameters such as temperature, pressure, and flow of each unit in real time and display them dynamically on the screen. When the parameters deviate from the set range, it will automatically issue an alarm and control the corresponding actuators to make adjustments to ensure the stable operation of the entire device.

[0047] (ii) such as Figure 1 The purification method is shown in the figure.

[0048] S100: Raw material pretreatment

[0049] In this embodiment, germanium-containing smelting slag produced by a certain factory was selected as raw material. Testing revealed that the germanium content in the slag was 2%, and the impurity composition and content were: Zn 12%, Pb 7%. The germanium-containing smelting slag contains 7% Fe, 11% Al, and 10%. First, the germanium-containing smelting slag is fed into a crusher for crushing. The particle size of the crushed material is controlled at 1-5 mm for subsequent grinding. The crushed material is then transferred to a ball mill for grinding for 2 hours to achieve a finer and more uniform particle size, increasing the contact area with hydrochloric acid. The ground material and industrial hydrochloric acid are added to a mixing tank at a ratio of slag:hydrochloric acid = 1 (t): 3 (m³) to prepare a slurry. The stirring speed of the mixing tank is set to 70 r / min, the stirring temperature is controlled at 35℃, and the stirring time is 45 min. During the stirring process, the hydrochloric acid reacts with the germanium compounds and some metal impurities in the smelting slag, while simultaneously making the slurry uniformly mixed. The insoluble impurities in the slurry are removed by filtration to obtain a uniform slurry suitable for distillation.

[0050] S200: First-stage gradient distillation and preliminary impurity removal

[0051] The homogeneous slurry obtained in S100 is pumped into the primary chlorination distillation vessel of the primary distillation unit. The intelligent control unit is activated, and the temperature of the primary chlorination distillation vessel is set to 100℃, the pressure to 0.2MPa, and the distillation time to 5h. Simultaneously, the cooling water circulation system of the primary condenser is turned on, and cooling water at 0-5℃ is introduced. During the distillation process, the germanium compound in the slurry reacts with hydrochloric acid to produce germanium tetrachloride. As it is heated, the germanium tetrachloride reacts with low-boiling-point impurities in the slurry to form mixed vapor, which is discharged from the steam outlet of the primary chlorination distillation vessel and then guided through the gas guide. The mixture enters the primary condenser, where it exchanges heat with cooling water at 0-5°C. Low-boiling-point impurities, due to their lower boiling point, preferentially condense into liquid and flow into the impurity storage tank for chlorine tailings. Germanium tetrachloride, with its relatively higher boiling point, does not completely condense under these conditions and remains in a liquid state, flowing out of the primary condenser outlet and into the secondary re-distillation arsenic removal unit. After 5 hours of distillation, the heating device is turned off, and distillation is stopped. The condensate in the impurity storage tank is then tested, and no germanium tetrachloride is detected, indicating that the separation of low-boiling-point impurities from germanium tetrachloride is effective.

[0052] S300: Two-stage re-distillation and deep arsenic removal

[0053] The germanium tetrachloride liquid is transported into the secondary re-distillation stage via pipeline. Simultaneously, analytical grade hydrochloric acid is added at a volume of one-quarter to one-third of the germanium tetrachloride volume. The heating device of the secondary re-distillation tower is started. Under the control of the intelligent control unit, the tower temperature is set to 120°C, the pressure is set to 0.3 MPa, and the distillation time is set to 4 hours. At the same time, the chilled brine circulation system of the secondary condenser is started, and 0-5°C cooling water is introduced. During the secondary redistillation process, arsenic trichloride in the germanium tetrachloride liquid undergoes an oxidation reaction, producing arsenic acid that is insoluble in germanium tetrachloride and has a high boiling point. It does not volatilize with the germanium tetrachloride vapor but remains in the liquid within the column, achieving deep arsenic removal. As distillation proceeds, the arsenic-removed germanium tetrachloride vapor is discharged from the steam outlet of the secondary redistillation column and enters the secondary condenser. Under the cooling effect of 0-5℃ cooling water, the germanium tetrachloride vapor initially condenses into liquid and flows into the intermediate storage tank. After 4 hours of distillation, heating and chlorine gas introduction are stopped, and the germanium tetrachloride liquid in the intermediate storage tank is tested. The arsenic content is below 0.0001%, indicating that the arsenic removal rate reaches over 99%, demonstrating a significant deep arsenic removal effect that meets the requirements for subsequent distillation purification.

[0054] S400: Three-stage distillation and fine purification

[0055] The germanium tetrachloride liquid, after initial condensation in the S300, is pumped into the distillation vessel of the three-stage distillation purification unit. The electric heating device of the distillation vessel is activated. Under the control of the intelligent control unit, the distillation vessel temperature is set to 120℃, the distillation column top temperature to 84℃, the reflux ratio to 4:1, and the distillation time to 7 hours. Simultaneously, the liquid nitrogen refrigeration system of the column top condenser is turned on, and liquid nitrogen at -196℃ is introduced. During the distillation process, the germanium tetrachloride liquid in the distillation vessel is heated and vaporized to form germanium tetrachloride vapor, which rises into the distillation column. Inside the column, the germanium tetrachloride vapor comes into full contact with the reflux liquid on the trays, undergoing multiple reactions. During the vaporization and condensation process, due to the different relative volatility of germanium tetrachloride and trace impurities with similar boiling points, the trace impurities remain more in the liquid phase as the germanium tetrachloride vapor rises, while the higher purity germanium tetrachloride vapor continues to rise to the top of the column. The pure germanium tetrachloride vapor exiting from the top of the distillation column enters the top condenser and is completely condensed into liquid high-purity germanium tetrachloride under the cooling of liquid nitrogen at -196℃. This liquid flows into the high-purity germanium tetrachloride collection tank. After 7 hours of distillation, heating and liquid nitrogen supply are stopped, and the drain valve at the bottom of the distillation vessel is opened to discharge the high-boiling-point impurities from the bottom of the column. The high-purity germanium tetrachloride in the collection tank is tested, and the purity reaches 99.999%.

[0056] S500: Hydrolysis and Reduction Refining

[0057] The hydrolysis process involves reacting high-purity germanium tetrachloride obtained from S400 with ultrapure water (resistivity ≥ 100%). Add the high-purity germanium tetrachloride to a PTFE-lined hydrolysis reactor at a volume ratio of 1:3. The effective volume of the hydrolysis reactor is 500L. Equipped with a mechanical stirrer, the chilled water circulation system of the hydrolysis reactor jacket is turned on to control the reaction temperature inside the reactor at 10℃. Start the stirrer and set the stirring speed to 60r / min. The stirring reaction time is 2.5h. Inside the hydrolysis reactor, high-purity germanium tetrachloride and ultrapure water undergo a hydrolysis reaction to generate germanium dioxide precipitate and hydrochloric acid. After the reaction is completed, the reaction solution is transferred to a vacuum filtration tank for filtration. The filtration pressure is set to 0. A germanium dioxide filter cake was obtained by filtration at 5 MPa for 1 hour. The filter cake was then washed three times with ultrapure water, each time using five times the mass of the filter cake, to remove residual hydrochloric acid and soluble impurities. After washing, the germanium dioxide filter cake was placed in an oven and dried at 120°C for 2 hours to remove moisture. The dried germanium dioxide was then transferred to a muffle furnace and calcined at 800°C for 2 hours to further remove residual chloride ions and organic impurities, yielding high-purity germanium dioxide. The high-purity germanium dioxide was tested and found to have a purity ≥99.999%, meeting the requirements of subsequent reduction processes.

[0058] The restoration process is as follows Figure 3 As shown, Figure 3This paper details the process steps from germanium dioxide to reduced germanium ingots, providing clear guidance for the reduction operation. The high-purity germanium dioxide obtained above is loaded into a high-purity graphite boat (material purity > 99.999%) to avoid introducing impurities. The graphite boat is then placed in a tunnel-type reduction furnace, and high-purity hydrogen gas (purity > 99.999%, dew point < -60℃) is introduced into the furnace. For the first use, nitrogen gas is introduced to replace the air to prevent an explosion caused by the introduced hydrogen. The hydrogen flow rate is controlled at 60 mL / min to replace the vacuum environment inside the furnace, ensuring a full hydrogen protective atmosphere. Afterwards, the reduction is carried out by heating.

[0059] Preheating section: The furnace temperature is raised from room temperature to 480℃ at a rate of 5℃ / min. After reaching the temperature, it is held for 30 minutes to gradually heat up the high-purity germanium dioxide, preparing it for the subsequent main reaction.

[0060] Main reaction section: The furnace temperature is raised from 480℃ to 700℃ at a rate of 3℃ / min, and held for 2 hours. In this stage, high-purity germanium dioxide undergoes a reduction reaction with hydrogen to produce metallic germanium.

[0061] Melting section: The furnace temperature is raised from 700℃ to 1050℃ at a rate of 4℃ / min and held for 1 hour to completely melt the generated metallic germanium and form a germanium liquid.

[0062] Cooling section: Turn off the heating device, keep hydrogen gas flowing in, and allow the furnace temperature to cool naturally to room temperature. During the cooling process, the germanium liquid gradually solidifies to form a reduced germanium ingot. After cooling is complete, open the furnace door, take out the reduced germanium ingot, and test the reduced germanium ingot. The purity is >99.999%, which meets the process requirements.

[0063] In the zone melting process, the reduced germanium ingot is removed from the reduction furnace and its surface is cleaned with a 5% sodium hydroxide solution to remove any impurities and oxide layers that may be attached to the surface. The cleaning time is 10 minutes. Then, it is rinsed with ultrapure water and dried. The cleaned reduced germanium ingot is then broken into small pieces with sides of about 2-3 cm and placed into a high-purity graphite boat in the zone melting furnace. The graphite boat is made of the same material as the one used in the reduction process to ensure purity. The graphite boat is placed in the working section of the zone melting furnace, the furnace body is closed, and the furnace is first evacuated to a vacuum level of 100%. Then, high-purity hydrogen gas is introduced, with the hydrogen flow rate controlled at 65 mL / min to establish a hydrogen protective atmosphere. The induction heating system of the zone melting furnace is started, and the melting zone width is set to 18 mm and the melting zone movement speed is 2 mm / min for zone melting. During the melting process, the high temperature generated by induction heating causes the germanium block in the graphite boat to partially melt and form a melting zone. The melting zone moves from one end of the graphite boat to the other end at the set speed. During the movement, impurities in the germanium will be enriched at one end as the melting zone moves. According to the above parameters, 10 cycles of melting are performed to ensure that the impurities are fully enriched. After the melting is completed, the heating system is turned off, and hydrogen gas is introduced again. After the furnace temperature cools to room temperature, the zone-melted germanium ingot is taken out, and the surface is cleaned again with 5% sodium hydroxide solution to remove any oxide layer and residual impurities that may be generated on the surface. After cleaning, it is rinsed with ultrapure water and dried. The purity of the final zone-melted germanium ingots was tested, and the results showed that the purity was >99.9999%, which met the standard for ultra-high purity zone-melted germanium ingots. Meanwhile, for some zone-melted germanium ingots with a purity test result of <99.9999%, the above-mentioned zone smelting process was repeated until the purity reached >99.9999%.

[0064] In summary, this embodiment, by strictly controlling the process parameters of each unit and following a complete process of raw material pretreatment, primary gradient distillation for preliminary impurity removal, secondary redistillation for deep arsenic removal, tertiary distillation for fine purification, and hydrolysis and reduction refining, successfully prepared ultra-high purity zone-melted germanium ingots with a purity >99.9999% from germanium-containing smelting slag. During implementation, each unit operated stably, and the intelligent control unit effectively monitored and automatically adjusted key parameters such as temperature, pressure, and flow rate in real time, ensuring that process conditions remained within the set range and reducing human error. The primary distillation unit effectively removed high-boiling-point impurities, achieving a high germanium tetrachloride vapor recovery rate. The secondary redistillation unit, through chlorine oxidation, achieved an arsenic removal rate of over 99%, solving the problem of difficult deep arsenic removal in traditional processes. The tertiary distillation purification unit utilized fine distillation to achieve a germanium tetrachloride purity of 99.999%. Subsequent hydrolysis, reduction, and zone smelting processes further improved the purity of germanium, ultimately yielding an ultra-high purity product.

[0065] Example 2

[0066] Based on the process flow shown in Example 1, this embodiment focuses on optimizing and verifying the ratio of germanium slag to hydrochloric acid. By designing four sets of comparative experiments with different ratios, the changes in key indicators such as germanium recovery rate, germanium tetrachloride purity, and final germanium ingot resistivity under each ratio were recorded in detail. Based on the experimental results, the optimal ratio was determined to further verify the stability and optimizability of the process of this invention, so as to achieve the best technical and economic results.

[0067] The operating parameters of the multi-stage gradient distillation and impurity removal device for germanium purification in this embodiment are exactly the same as those in Embodiment 1. The difference is that this embodiment aims to simulate a process optimization process. Therefore, in the first-stage gradient distillation step (S200), the hydrochloric acid ratio is used as a single variable for systematic study. All other conditions, such as temperature, pressure, and time, are consistent with those in Embodiment 1.

[0068] Raw materials: The same batch of germanium-containing smelting slag as in Example 1 was used to ensure consistent raw material composition, i.e., Zn 12% and Pb 7%. The composition was 7%, Fe was 11%, and Al was 10%, and the same pretreatment was performed.

[0069] Experimental Groups: With a fixed amount of germanium slag of 500 kg, four experimental groups were set up, with the following hydrochloric acid usage:

[0070] Germanium slag: hydrochloric acid = 1:1 (i.e., 500 kg of slag is mixed with 0.5 m³ of acid);

[0071] Germanium slag: hydrochloric acid = 1:2 (i.e., 500 kg of slag is mixed with 1.0 m³ of acid);

[0072] Germanium slag: hydrochloric acid = 1:3 (i.e., 500 kg slag to 1.5 m³ acid), the same as in Example 1;

[0073] Germanium slag: hydrochloric acid = 1:4 (i.e., 500 kg of slag is mixed with 2.0 m³ of acid);

[0074] Each experiment was repeated three times to ensure the reliability of the data.

[0075] Process execution: such as Figure 1 As shown, the material is first crushed and ground to achieve the same particle size and shape as in Example 1, resulting in a homogeneous slurry suitable for distillation. Each slurry undergoes primary gradient distillation, secondary redistillation for arsenic removal, and tertiary rectification to obtain high-purity germanium tetrachloride. Subsequently, as... Figure 3 As shown, germanium tetrachloride in each group underwent the same hydrolysis, reduction, and zone melting processes to ultimately produce ultra-high purity zone-melted germanium ingots.

[0076] Evaluation indicators and testing methods:

[0077] Germanium recovery rate: Calculated by measuring the germanium content in raw materials and final products, with a preset target value of ≥95%.

[0078] Germanium tetrachloride purity: After S400, the content of common impurities was determined by inductively coupled plasma mass spectrometry. The purity was calculated by subtracting the total amount of impurities from 100%, with a preset target value of ≥99.999%.

[0079] Germanium ingot resistivity: The resistivity of the qualified portion of the final zone-melted germanium ingot is measured, with a preset target value of ≥50Ω·cm.

[0080] Results and Analysis:

[0081] Through systematic collection and statistical analysis of four sets of experimental data, the key performance parameters under different hydrochloric acid ratios were obtained, as shown in the table below:

[0082]

[0083] Results analysis:

[0084] Impact on germanium recovery rate: As shown in the table above, the hydrochloric acid ratio has a significant impact on the germanium recovery rate. When the ratio increases from 1:1 to 1:2, the germanium recovery rate jumps sharply from 85.2% to 96.4%, exceeding the target value of 95%. This indicates that sufficient hydrochloric acid is the key to ensuring the full chlorination and volatilization of germanium compounds in the germanium slag. When the ratio continues to increase to 1:3 and 1:4, the recovery rate stabilizes at around 96.5%, with a slight increase. This indicates that the recovery rate tends to saturate after the amount of hydrochloric acid reaches twice the amount of germanium slag.

[0085] Impact on product purity: The germanium tetrachloride purity obtained from the four sets of experiments all exceeded the target requirement of 99.999%, and the difference was very small. This indicates that under the powerful purification capability of the multi-stage gradient distillation purification device described in this invention, the small fluctuations in the acid-sludge ratio of the first-stage distillation feed have no significant impact on the purity of the final product, and the process has good robustness.

[0086] Overall optimization: Although the purity and recovery rate are slightly higher at a 1:4 ratio, considering that excessive hydrochloric acid will increase reagent consumption, waste acid treatment volume and overall cost, while a 1:3 ratio can stably achieve extremely high recovery rate and ultra-high product purity, from a comprehensive consideration of technical and economic factors, 1:3 is determined to be the optimal ratio of germanium slag to hydrochloric acid. This ratio is consistent with the successful practice of Example 1.

[0087] This embodiment verifies the influence of hydrochloric acid ratio on the process performance of the present invention through rigorous univariate comparative experiments. The results show that a germanium slag:hydrochloric acid ratio of 1:3 is one of the optimal operating parameters for this process, which can ensure extremely high germanium recovery rate and product purity while taking into account the economic efficiency of the process. This further proves that the present invention not only provides a set of efficient germanium purification equipment and methods, but also that its process parameters have clear predictability, providing a solid experimental basis for fine control in industrial applications. The entire process shows good stability and repeatability under different parameters, showing broad prospects for industrial application.

[0088] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A multi-stage gradient distillation impurity removal apparatus for germanium purification, characterized by, The device is composed of a first distillation unit, a second distillation unit, a third distillation unit, a condensation and collection unit, and an intelligent control unit, which are connected in sequence through pipelines. The first distillation unit is used for chlorination reaction of the germanium-containing material and preliminary separation of the generated crude germanium tetrachloride vapor to remove high-boiling impurities. The second distillation unit is connected with the outlet of the first distillation unit and is used for oxidation reaction of the germanium fraction from the first distillation unit by introducing chlorine gas to convert arsenic trichloride into arsenic acid, and deep dearsenification by distillation. The third distillation unit is connected with the outlet of the second distillation unit and is used for fine distillation of the germanium tetrachloride after dearsenification to remove trace impurities with similar boiling points as germanium tetrachloride, and obtain high-purity germanium tetrachloride. The condensation and collection unit is connected with the vapor outlets of the first distillation unit, the second distillation unit, and the third distillation unit, respectively, and is used for gradient condensation and collection of the generated vapor at each stage. The intelligent control unit is electrically connected with the signal detection elements and execution elements of the above units, and is used for real-time monitoring and automatic regulation of the temperature, pressure, and flow parameters of the entire device.

2. A multi-stage gradient distillation impurity removal apparatus for germanium purification according to claim 1, characterized by, The first distillation unit includes a first chlorination distillation kettle and a first condenser connected with the outlet of the first chlorination distillation kettle. The second distillation unit includes a second distillation tower, a chlorine gas introduction system for introducing chlorine gas into the second distillation tower, and a second condenser connected with the outlet of the second distillation tower. The third distillation unit includes a distillation kettle, a distillation tower connected with the top of the distillation kettle, and a tower top condenser connected with the top of the distillation tower.

3. A multi-stage gradient distillation impurity removal apparatus for germanium purification according to claim 2, characterized by, The operating parameters of the first chlorination distillation kettle are: temperature 80-120℃, pressure 0.1-0.3MPa, and distillation time 4-6h. The operating parameters of the second distillation tower are: temperature 80-160℃, pressure 0.1-0.3MPa, and distillation time 3-5h. The operating parameters of the third distillation unit are: distillation kettle temperature 80-120℃, distillation tower top temperature 83-85℃, reflux ratio 4:1, and distillation time 6-8h.

4. A multi-stage gradient distillation impurity removal apparatus for germanium purification according to claim 2, characterized by, The first condenser tube uses 0-5℃ cooling water, the second condenser tube uses 0-5℃ cooling water, and the third condenser tube uses 0-5℃ cooling water.

5. A multistage gradient distillation impurity removal purification method for germanium purification, suitable for use in a multistage gradient distillation impurity removal apparatus for germanium purification according to any one of claims 1 to 4, characterized in that, The specific steps of the method are: S100, raw material pretreatment: crushing, grinding, and mixing with hydrochloric acid to prepare a slurry, and removing impurities to obtain a uniform slurry suitable for distillation; S200, first-stage gradient distillation and preliminary impurity removal: feeding the uniform slurry into the first distillation unit, performing chlorination distillation at 80-120℃ and 0.1-0.3MPa for 4-6h, and leading the generated mixed vapor to the first condenser tube, condensing the low-boiling impurities and collecting them in an impurity storage tank, and using a pipeline to transport the uncondensed germanium tetrachloride liquid into the second distillation unit for dearsenification; S300, secondary reboiling and deep dearsenization: the germanium tetrachloride liquid is delivered into a secondary reboiling tower by a pipeline, and pure hydrochloric acid with a volume of 25-33% of the germanium tetrachloride is introduced into the tower, the temperature in the tower is controlled at 80-120℃, the pressure is controlled at 0.2-0.4MPa, and distillation is performed for 3-5h, the germanium tetrachloride liquid enters a secondary condenser, and after preliminary condensation, enters a tertiary rectification and purification unit; S400, tertiary rectification and fine purification: the germanium tetrachloride liquid after preliminary condensation is fed into a rectification kettle and heated to 80-120℃, the top temperature of the rectification tower is controlled at 83-85℃, the reflux ratio is 4:1, and after rectification for 6-8h, high-boiling-point impurities at the bottom are discharged, and pure germanium tetrachloride vapor at the top enters a tower top condenser, and after complete condensation, high-purity germanium tetrachloride is obtained by layering; S500, hydrolysis and reduction refining: the high-purity germanium tetrachloride obtained in S400 is subjected to hydrolysis, reduction and zone melting to finally prepare an ultrahigh-purity zone-melted germanium ingot.

6. The multistage gradient distillation impurity removal purification method for germanium purification according to claim 5, characterized by, The germanium content of the germanium-containing smelting slag in the S100 is 1-3%, and the slurry is prepared by stirring for 30-60 min under the conditions of 20-50 DEG C and 50-100 r / min, the impurity components include 10-15% of Zn, 6-8% of Pb, 6-8% of , 8-15% of Fe, and 8-12% of Al.

7. The multistage gradient distillation impurity removal purification method for germanium purification according to claim 5, characterized by, The hydrolysis process in S500 is as follows: the high-purity germanium tetrachloride obtained in S400 is added to a tetrafluoroethylene hydrolysis kettle in a volume ratio of 1:3 with ultrapure water, the temperature is controlled at 8-12℃, and stirring is performed for 2-3h to generate germanium dioxide and hydrochloric acid, the reaction liquid is filtered, washed with water, dried at 120℃, and calcined at 800℃ for 2h to obtain high-purity germanium dioxide.

8. The multistage gradient distillation impurity removal purification method for germanium purification according to claim 6, characterized by, The reduction process in S500 is as follows: the high-purity germanium dioxide is loaded into a high-purity graphite boat, placed in a tunnel-type reduction furnace, high-purity hydrogen is introduced, and reduction is performed according to a preheating section, a main reaction section, a melting section and a cooling section to obtain a reduced germanium ingot with a purity of >99.999%. The temperature of the preheating section is 450-500℃, and the time is 30min. The temperature of the main reaction section is 680-720℃, and the time is 2h. The temperature of the melting section is 1000-1100℃, and the time is 1h.

9. The multistage gradient distillation impurity removal purification method for germanium purification according to claim 8, characterized by, The zone melting process in S500 is as follows: the reduced germanium ingot is taken out of the reduction furnace, washed with lye, knocked into a high-purity graphite boat in a zone melting furnace, an inductive heating type zone melting furnace is used, the melting zone width is 15-20mm, the moving rate is 1.5-2.5mm / min, the high-purity hydrogen gas protective atmosphere is controlled at a flow rate of 50-80mL / min, and 8-12 cycles of melting are performed, after the melting is completed, the zone-melted germanium ingot is cooled, taken out, washed, an ultrahigh-purity zone-melted germanium ingot with a purity of >99.9999% is obtained, and the germanium ingot with a purity of <99.9999% is subjected to zone melting again.

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