Directional solidification purification and crystal growth method for trace germanium in hydrometallurgy tailings

Abstract

The invention relates to the technical field of single crystal growth, and discloses a directional solidification purification and crystal growth method for trace germanium in hydrometallurgy tailings, which comprises the following steps: forming a suspended liquid germanium melting zone; while the tailing powder raw material is supplied, a controlled trace oxidizing atmosphere is introduced to convert conductive impurities into non-conductive oxides; non-conductive impurities and non-conductive oxides are separated by using electromagnetic mechanical difference of induction heating; according to the method disclosed by the invention, through a synergistic mechanism of a physical barrier and chemical conversion, the problem of form incompatibility of powder which cannot be directly fed in a suspension zone melting technology is solved, secondary pollution caused by traditional ingot casting is avoided, and the method is suitable for large-scale production. According to the method, the principle limitation that the segregation coefficient is larger than that of impurities due to directional solidification is avoided, and growth from tailings to high-purity crystals is achieved.

Description

Technical Field

[0001] This invention relates to a method for directional solidification purification and crystal growth of trace germanium in hydrometallurgical tailings, belonging to the field of single crystal growth technology. Background Technology

[0002] Currently, suspension zone melting is a core process for obtaining the highest purity crystalline materials. Its main advantage lies in the fact that the entire melting and crystal growth process does not use a crucible for support. The molten zone is suspended by its own surface tension and electromagnetic force, thus avoiding contact between the molten material and the inner wall of the crucible, which would introduce contaminants. However, this non-contact crucible characteristic of suspension zone melting also brings a process limitation. The start-up and stable operation of the process strictly depend on a pre-formed rod with good conductivity, mechanical stability, and self-support as the starting material. This characteristic makes suspension zone melting suitable for processing pre-formed polycrystalline rods, but when the starting material is powder, granules, or non-conductive glassy material, the technology suffers from direct physical incompatibility. To adapt powdered raw materials to the suspension zone melting process, the existing conventional practice in the field is to add an intermediate step. This process first involves melting the powdered raw material at high temperature in a crucible and casting it into a rough rod. Then, this rod is sent to a levitation zone melting device for purification and crystal growth. The main problem with this method of casting the ingot first and then levitation zone melting is that the previous crucible casting step introduces contamination through the crucible wall, i.e., secondary contamination. This secondary contamination weakens the high-purity process characteristics of the subsequent levitation zone melting process, which does not come into contact with the crucible, at the source.

[0003] Existing technologies face a technical contradiction when processing powdered raw materials: the pollution-free nature of suspension zone melting technology is limited by the requirement to use pre-formed rods. The conventional method for preparing these rods, crucible casting, introduces pollution. Within the existing technological framework, the following technical problems need to be addressed: 1. Process segmentation and pollution introduction: The existing multi-step process of crucible casting followed by zone melting purification is lengthy and costly. Furthermore, secondary pollution introduced in the preceding steps limits the final purity of the subsequent zone melting purification. 2. Incompatibility of raw material forms: Suspension zone melting equipment is physically designed to not directly process powdered raw materials, limiting its application in high-purity preparation. 3. Risks to crystal growth quality: Even when using ingot casting to prepare coarse rods, casting defects and uneven impurity segregation within the rods can easily lead to instability in the melting zone during subsequent zone melting, affecting the final crystal quality. In addition to the limitations on raw material form processing mentioned above, existing technologies also have fundamental flaws in their purification mechanisms for specific chemical impurities. Directional solidification, as an important purification method, has a purification effect limited by the segregation coefficient of impurities. For most For metallic elements, directional solidification can effectively remove them by pushing them into the liquid phase; however, for elements such as boron (… ),phosphorus( ) or silicon ( Impurities such as those with segregation coefficients close to or greater than 1 in germanium or silicon are almost impossible to remove effectively by conventional solidification processes.

[0004] Therefore, the technical problem to be solved by this invention is how to provide a process method that can get rid of the dependence on pre-made rods, so that the suspension zone melting technology can directly process raw materials in powder form, thereby avoiding the crucible casting process and the secondary pollution problems it brings, and realizing one-step growth from powder raw materials to high-purity crystals. Summary of the Invention

[0005] This invention provides a method for directional solidification purification and crystal growth of trace germanium in hydrometallurgical tailings. Its main purpose is to solve the problem that the existing technology requires the introduction of a crucible casting process to adapt to the suspension zone melting technology, which leads to secondary pollution and makes it impossible to prepare high-purity crystals from powdered raw materials in one step.

[0006] To achieve the above objectives, this invention provides a method for directional solidification purification and crystal growth of trace germanium in hydrometallurgical tailings. The method is performed within a process chamber containing an induction heating coil and a process atmosphere control system, based on a germanium seed crystal. The method includes: S1, the upper end of the germanium seed crystal is melted by the induction heating coil to form a suspended liquid germanium molten zone; S2, a controlled trace oxidation atmosphere is introduced into the process chamber. The oxidation potential of the trace oxidation atmosphere is set to be higher than the oxidation potential required for conductive impurities with a segregation coefficient greater than one dissolved in the oxidized molten zone, and lower than the oxidation potential required for germanium in the oxidized liquid germanium molten zone. S3, feeding the powdered raw material of hydrometallurgical tailings to the surface of the liquid germanium molten zone; S4 utilizes the Lorentz force applied to the conductive liquid germanium molten zone by induction heating, and the mechanical difference applied to the non-conductive impurity components in the powder raw material, causing the non-conductive impurity components to separate from the liquid germanium molten zone. In addition, the trace amount of oxidizing atmosphere in S2 converts the conductive impurities with a segregation coefficient greater than one into non-conductive oxides in situ, and the non-conductive oxides also separate from the liquid germanium molten zone. S5, monitor the accumulation state of non-conductive impurity components and non-conductive oxides on the surface of the liquid germanium molten zone, and when the accumulation state reaches the preset condition, intermittently supply a flux powder. The flux powder reacts with the non-conductive impurity components and non-conductive oxides and reduces their viscosity, causing them to separate from the surface of the liquid germanium molten zone. S6 causes the solid-liquid interface between the germanium seed crystal and the liquid germanium molten zone to move relative to each other, and germanium crystals are grown under the synergistic effect of S1 to S5.

[0007] Preferably, in step S4, separating the non-conductive impurity components and non-conductive oxides from the liquid germanium molten zone further includes: utilizing the skin effect of induction heating to concentrate a high-frequency current on the surface of the liquid germanium molten zone and generate high temperature on the surface, so that the volatile impurity components in the powder raw material flash or sublimate and vaporize and separate when they come into contact with the surface of the liquid germanium molten zone.

[0008] Preferably, the controlled trace oxidation atmosphere in S2 is a mixture of high-purity inert gas and active oxidizing gas; the high-purity inert gas is argon, and the active oxidizing gas is water vapor; the method further includes: controlling the flow rate of the active oxidizing gas through a mass flow controller to keep the oxidation potential stable within a preset window, the preset window being determined based on the Ellingham chart data of conductive impurities with a segregation coefficient greater than one and germanium.

[0009] Preferably, in S5, the flux powder is a metallurgical flux; the step of monitoring the accumulation state in S5 includes: using an induction heating coil to monitor the radio frequency power load signal of the induction heating coil, and judging whether the accumulation state has reached the preset condition based on the drift of the radio frequency power load signal.

[0010] Preferably, the method further includes: step 501, monitoring the radio frequency power supply load signal of the induction heating coil in real time; step 502, performing transient analysis on the radio frequency power supply load signal to extract high-frequency disturbance signals characterizing transient thermal shock in the liquid germanium molten zone; step 503, based on the high-frequency disturbance signals, using proportional-integral control logic closed-loop to adjust the supply rate of powder raw materials in S3 in real time. Supply rate follow: ,in, As the benchmark supply rate, The amplitude of the high-frequency disturbance signal. and These are the control coefficients for proportional-integral control logic.

[0011] Preferably, the stage of introducing a controlled trace oxidizing atmosphere in S2 and the stage of intermittently supplying flux powder in S5 are performed alternately in time; and before switching from the stage of introducing a controlled trace oxidizing atmosphere to the stage of supplying flux powder, the method further includes: step 601, stopping the introduction of the controlled trace oxidizing atmosphere; step 602, introducing a large flow rate of high-purity inert gas into the process chamber to physically replace and purge the atmosphere above the liquid germanium melting zone to remove residual controlled trace oxidizing atmosphere.

[0012] Preferably, the process chamber has an inner wall, and the method is performed in an environment in which an inert gas is introduced; and the inert gas is introduced in such a way that a sheath flow adhering to the inner wall of the process chamber is formed, the sheath flow constituting a gas dynamic barrier; the gas dynamic barrier aerodynamically captures and guides the non-conductive impurity components and non-conductive oxides separated in S4 and S5 to a predetermined collection area before they come into contact with and condense on the inner wall.

[0013] Preferably, the method further includes: step 801, continuously monitoring the exhaust atmosphere of the process chamber and detecting the characteristic byproduct gas generated by the reaction of the controlled trace oxidizing atmosphere of S2 with reducing impurities in the powder raw material of S3; step 802, adjusting the flow rate of the controlled trace oxidizing atmosphere introduced into S2 in a feedforward manner based on the concentration of the monitored characteristic byproduct gas, the adjustment compensating for the consumption of the controlled trace oxidizing atmosphere by the reducing impurities.

[0014] Preferably, in S3, the powdered raw material is supplied to the edge of the liquid germanium molten zone via a side feeder.

[0015] Preferably, in S6, while the solid-liquid interface between the germanium seed crystal and the liquid germanium molten zone moves relative to each other, soluble impurities in the liquid germanium molten zone are pushed away from the solid-liquid interface by the segregation effect.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. The method provided by this invention is based on the reconstruction of the physical role of the induction heating field in the single crystal growth process. It does not only use the heating coil as a heat source, but also utilizes the accompanying skin heat effect and electromagnetic force effect to construct a dynamic and selective physical barrier on the surface of the suspended liquid molten zone. Before the powder raw material comes into contact with the main body of the molten zone, the barrier realizes the physical repulsion of non-conductive impurities and the flash separation of volatile components in real time and in situ, allowing only the target element to melt and enter the molten zone. This mechanism makes it possible to grow high-purity crystals directly from powder, avoids the composition supercooling that will inevitably be caused by the influx of a large number of physical impurities, and also makes the pre-ingot casting step, which is necessary to adapt to the zone melting technology in traditional processes and would bring secondary pollution, no longer a necessary step in the entire crystal growth process.

[0017] 2. Based on the physical barrier mechanism, this method further addresses the fundamental limitations of directional solidification technology when dealing with specific chemical impurities. For dissolved impurities (such as silicon) with a segregation coefficient greater than one that cannot be removed by conventional solidification processes, this method introduces controlled trace amounts of oxide components into the process atmosphere. Based on thermodynamic differences, this method selectively and in-situ chemically transforms such dissolved impurities (silicon) into their corresponding oxides (silicon dioxide). Since the transformed oxide is a non-conductive slag form, it becomes the ideal target for the aforementioned physical barrier mechanism (based on electromagnetic repulsion), and is thus actively separated and removed from the surface of the molten zone. This synergistic effect of chemical transformation and physical repulsion allows the crystal growth process to break free from the inherent constraints of the segregation coefficient of specific impurities.

[0018] 3. This invention also utilizes the induction heating coil itself to construct a multi-timescale process feedback control system. By decoupling the same radio frequency power supply load signal, its slowly drifting low-frequency component is used as the basis for judging the slag accumulation state on the surface of the molten zone, and intermittent flux supply is triggered to reduce the viscosity of the slag chemically and restore the cleanliness of the molten zone surface. At the same time, its high-frequency transient component is used as a signal to characterize the thermal shock caused by uneven powder supply, and the supply rate of the powder feeder is controlled in a closed loop in real time. This control logic, which multiplexes a single physical source (radio frequency signal) into a dual information source (slow-state chemistry and fast-state physics) and drives two different modes of response, chemical purification and physical stability, respectively, ensures that the crystal growth interface can maintain the dynamic stability of its thermodynamic and physical morphology under complex and fluctuating feeding conditions. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process flow and collaborative control logic of the present invention; Figure 2 This is a comparison chart of process stability under different feeding methods of the present invention; Figure 3 This is a schematic diagram of the synergistic purification and gas protection structure within the process chamber of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] This invention provides a method for the directional solidification purification and crystal growth of trace germanium in hydrometallurgical tailings. The core of this method lies in the novel application of the physical role of induction heating in single crystal growth. Within a process chamber containing an induction heating coil and a process atmosphere control system, based on a single germanium seed crystal, a process environment with synergistic effects of physical barrier and chemical transformation is constructed. This method, while providing heat, additionally performs online, in-situ, and selective physical purification of the powdered raw material, and combines this with the thermodynamic selectivity of a specific chemical atmosphere to achieve the chemical transformation and removal of specific impurities. The method mainly includes: first, melting the upper part of the germanium seed crystal through induction heating to form a suspended liquid germanium molten zone, which serves as the base for subsequent processes; then, while supplying hydrometallurgical tailings powdered raw material to this molten zone, introducing a controlled trace oxidizing atmosphere into the process chamber. The purpose of introducing this trace oxidizing atmosphere is to overcome the limitation of removing impurities with a segregation coefficient greater than one in the directional solidification principle. It utilizes thermodynamic differences to remove such conductive impurities dissolved in the molten zone, such as trace silicon. In-situ chemical transformation into non-conductive oxides, such as silicon dioxide. Meanwhile, the electromagnetic mechanical effect associated with the induction heating field, namely the Lorentz force, strongly supports and constrains the conductive liquid germanium molten zone, but exerts almost no force on the non-conductive impurities in the powder raw material and the newly transformed non-conductive oxides from the previous step. This mechanical difference causes them to be actively repelled from the molten zone. In addition, the skin effect of induction heating keeps the surface of the molten zone at a high temperature, which can vaporize and separate the volatile impurities in the raw material at the moment of contact. During the purification process, the accumulated scum is reduced in viscosity and promoted to separate by intermittently supplying flux powder.

[0022] In a specific implementation, the method first establishes an inert atmosphere environment in the process chamber, which can be a sealed quartz tube, for example by introducing high-purity argon gas, and fixes a germanium seed crystal. Then, an induction heating coil is activated, and its high-frequency current induces eddy currents on the conductive germanium seed crystal, generating Joule heating to melt it and form a suspended liquid germanium molten zone. This molten zone remains suspended by the electromagnetic force (Lorentz force) generated by induction heating and its own surface tension, avoiding contact with any crucible. After the molten zone stabilizes, the process switches to a synergistic purification dynamic equilibrium stage. The core of this stage is to remove conductive impurities with a segregation coefficient greater than one, such as trace amounts of silicon. Processing is required; these impurities are due to their The properties of this substance cannot be removed by conventional solidification and segregation effects; instead, it tends to accumulate in the grown crystals. To address this issue, this method introduces S2, which involves introducing a controlled trace amount of oxidizing atmosphere into the process chamber. The oxidation potential of this atmosphere is precisely set within a specific thermodynamic window, higher than the oxidation potential dissolved in the molten zone. The required oxidation potential is lower than that of the host material. The required oxidation potential; the determination of this oxidation potential window is based on... , The standard Gibbs free energy of formation for its corresponding oxides, also known as the Ellingham Diagram data; in engineering implementation, this atmosphere can be achieved by mixing a highly pure inert gas, such as argon, with an active oxidizing gas, such as water vapor, precisely controlled by a mass flow controller (MFC). To achieve this, by adjusting The partial pressure can stabilize the oxidation potential of the system within a preset window; under this atmosphere, the dissolved oxygen in the molten zone... When atoms diffuse to the surface of the molten zone, they are preferentially oxidized. ,and To ensure stability, and to guarantee that the oxidation potential of the controlled trace oxidation atmosphere in S2 is set within a preset window (i.e., below the oxidation potential required to oxidize liquid germanium), a calibration procedure for determining the upper limit of the flow rate of an active oxidizing gas such as water vapor (H2O) can be included before the actual process execution. This procedure is performed within the process chamber based on the stable suspended liquid germanium molten zone formed in S1, and under conditions where the powdered raw material for S3 is not supplied. The procedure includes setting an initial H2O inflow rate using a mass flow controller. Furthermore, a waste gas atmosphere monitoring system, such as a process mass spectrometer at the chamber outlet, is used to monitor the signal intensity of characteristic byproducts such as GeO produced by germanium oxidation in real time. Then, gradually increase the value by a preset step size, such as 0.1 sccm. and continue to monitor The response when detected When the signal strength begins to exceed its background noise baseline in a purely inert atmosphere, for example, when the signal amplitude exceeds three standard deviations of the baseline, record the H2O inflow rate at this point. ,Should This flow rate was determined to be the upper limit that would cause oxidation loss of the main material, germanium. Therefore, in the subsequent synergistic purification process, the baseline working flow rate for introducing H2O into S2 was set below this limit. A safety margin, if set as to Meanwhile, it ensures that the operating flow rate is higher than the lower limit of the flow rate required to convert conductive impurities such as Si with a segregation coefficient greater than one, as verified by the data from the embodiment, thereby anchoring the actual engineering operation window within the theoretical thermodynamic window determined by Ellinghamtow.

[0023] Simultaneously with the introduction of an oxidizing atmosphere, S3 is initiated, supplying the powdered raw material from the hydrometallurgical tailings to the surface of the liquid germanium molten zone. To minimize disturbance to the stability of the molten zone, it is preferable to supply the powdered raw material to the edge region of the molten zone via a lateral feeding device. At this point, the synergistic purification mechanism of S4 is activated. On one hand, the Lorentz force exerted by induction heating on the conductive liquid germanium molten zone, and the mechanical difference exerted on the non-conductive impurities in the powdered raw material, such as the silicates and oxides originally present in the tailings, cause these non-conductive impurities to be physically repelled and separated upon contact with the molten zone. On the other hand, the products of the in-situ transformation in S2 mentioned above... Since it is also a non-conductive oxide, it is similarly affected by this electromagnetic mechanical difference and is actively separated from the liquid germanium molten zone. Furthermore, the skin effect of induction heating concentrates the high-frequency current on the molten zone surface, resulting in extremely high surface temperatures. When the powdered raw material comes into contact with this high-temperature surface, the volatile impurities it contains, such as sulfides or other low-boiling-point metal oxides, will immediately flash or sublimate, and be carried away in gaseous form by the chamber's vacuum system, achieving vaporization separation. In S4, the Lorentz force applied to the conductive liquid germanium molten zone by induction heating creates a mechanical difference between it and the non-conductive impurities. The physical separation effect depends on the operating frequency of the induction heating coil. This operating frequency It needs to be set within a high-frequency operating window to ensure the skin depth produced in the conductive liquid germanium molten region. Feature dimensions much smaller than the molten zone, such as the molten zone radius. Specifically, operating frequency The setting should make the skin depth With the radius of the melting zone ratio Less than 0.1, a preferred operating frequency The operating frequency ranges from 1 MHz to 5 MHz. Under these high-frequency operating conditions, the high-frequency current is concentrated on the surface layer of the liquid germanium molten region, and the resulting Lorentz force is also concentrated on the surface, forming a strong electromagnetic pressure gradient pointing towards the interior of the molten region. This pressure gradient is sufficient to confine the conductive liquid germanium and maintain its suspension, while the non-conductive impurity components (and the transformed non-conductive oxides) are not coupled with the high-frequency electromagnetic field and are therefore not affected by this force. Thus, under the repulsion of this pressure gradient, they are actively separated from the surface of the molten region. If the operating frequency... If the setting is too low, such as below 100kHz, the skin depth will be affected. If the electromagnetic force is too large, it will primarily act within the molten zone, generating a stirring effect, rather than forming sufficient repulsive force on the surface, leading to a decrease in the physical separation effect of S4. As the purification process continues, the separated non-conductive impurities and non-conductive oxides, collectively referred to as scum in the following text, will accumulate on the surface of the molten zone. If left untreated, this will form a high-viscosity scum layer, hindering subsequent raw material supply and disrupting thermal stability. Therefore, S5 provides a scum management solution. This solution first requires monitoring the accumulation state of the scum. A preferred non-invasive monitoring method is to utilize the induction heating coil itself to monitor the load signal of its RF power supply in real time. When the accumulation of scum (non-conductive) increases, it will alter the overall electromagnetic coupling characteristics and thermal conditions of the molten zone, affecting the RF power supply load signal, such as power or impedance. A detectable slow drift occurs; when the drift reaches a preset condition, the system triggers an action, intermittently supplying a flux powder, such as a metallurgical flux; the function of this flux powder is to react with the high-viscosity slag, reducing its viscosity and transforming it into a more flowable liquid slag, which is then separated and removed from the surface of the molten zone under the action of melt agitation or gravity; under the synergistic effect of the purification system composed of S1 to S5, the main body of the liquid germanium molten zone is kept at high purity. At this time, S6 is activated, causing the relative movement of the solid-liquid interface between the germanium seed crystal and the liquid germanium molten zone, for example by slowly lowering the seed crystal rod or moving the coil as a whole. The pure germanium liquid at the bottom of the molten zone begins to solidify directionally under the guidance of the seed crystal, growing high-purity germanium crystals; during this process, soluble impurities with a segregation coefficient of less than one remaining in the molten zone, such as and Due to the classic segregation effect, the crystals are repelled by the solid-liquid interface and continuously pushed away from the solid-liquid interface, accumulating at the top of the molten zone, thus further ensuring the purity of the grown crystal body.

[0024] To ensure the long-term stable operation of the entire process, this invention may also include a series of optimized process control strategies. For example, to address the transient thermal shock problem that may be caused by uneven powder raw material supply, powder agglomeration, or collapse, a closed-loop feedback control is provided. This method also utilizes the RF power supply load signal of the induction heating coil, but performs transient analysis. When cold powder agglomerates hit the molten zone, causing thermal shock, the load signal will generate instantaneous high-frequency disturbances. The system extracts these high-frequency disturbance signals in real time. This data is then input into a proportional-integral (PI) control logic to adjust the powder raw material supply rate in real time using a closed-loop system. This adjustment follows a specific control equation: ;in, As the benchmark supply rate, and These are the control coefficients for the proportional-integral (PI) control logic; once a disturbance signal is detected... As the amplitude increases, the controller immediately... Item and Term decrease This immediately suppresses the feed, allowing time for the molten zone to recover thermal equilibrium, thus greatly suppressing the damage of thermal shock to the crystal growth interface; addressing the potential chemical incompatibility between the oxidizing atmosphere of S2 and the flux powder of S5, for example... It can react with fluoride flux at high temperatures to form Corrosive gases provide a temporal logic decoupling scheme; this scheme stipulates that these two steps must be performed alternately in time and are strictly prohibited from existing simultaneously; and before switching from the stage of introducing the oxidizing atmosphere to the stage of supplying flux powder, a strict atmosphere purging step must be performed, first stopping the introduction of a controlled trace amount of oxidizing atmosphere; then, in step 602, a large flow rate of high-purity inert gas, such as argon, is introduced into the process chamber to forcibly physically replace and purge the atmosphere above the molten zone, ensuring that any residual oxidizing atmosphere, such as argon, is eliminated before the supply of flux powder. The impurities have been completely removed, thus avoiding harmful side reactions. For example, regarding the issue of scum separated during the purification process—non-conductive impurities and oxides—splashing and contaminating the inner walls of the process chamber, such as quartz tubes, this contamination can cause optical window de-penetration and malfunction of sensors like pyrometers. A gas dynamics protection scheme is provided. This scheme restructures the inert gas introduction method, changing it from a diffused filling to a high-speed, wall-adhering sheath flow formed on the inner wall of the process chamber through specific spray components, such as an annular spray ring. This sheath flow constitutes... A gas dynamic barrier is created; when high-temperature slag droplets splash onto the tube wall, they are aerodynamically captured by this high-speed airflow before contacting the tube wall and condensing, and are guided by its momentum to a predetermined collection area, such as the cold trap at the bottom of the cavity, thus maintaining the long-term cleanliness of the optical window area of ​​the quartz tube; finally, to address the problem of fluctuations in raw material composition, such as the occasional mixing of reducing impurities such as coke powder in the tailings, which may disrupt the stability of the oxidizing atmosphere in S2, a feedforward compensation control is provided; this method continuously monitors characteristic by-product gases at the exhaust gas outlet of the process chamber, for example, when the carbon in the raw material ( ) consumed the oxidizing atmosphere ( When ), it will produce and byproducts ( The system monitors or By monitoring the concentration, the extent to which the oxidizing atmosphere is consumed can be determined in real time. Based on this concentration monitoring, the system (Feed-forward) adjusts the amount of active oxidizing gas introduced into S2. The flow rate dynamically compensates for the consumption of the controlled trace oxidation atmosphere by reducing impurities, ensuring that the effective oxidation potential on the molten zone surface is always maintained within a preset window, thus guaranteeing the... Impurities, such as Its continuous conversion capability.

[0025] Example 1: This example demonstrates an operational instance in a specific process scenario where the supplied hydrometallurgical tailings powder raw material not only contains the target product germanium and conventional non-conductive impurities, but also contains high levels of conductive impurities with a segregation coefficient greater than one, such as trace amounts of silicon. And impurities with strong reducing properties, such as carbon. Powder; After the process starts, the system forms a suspended liquid germanium molten zone according to S1, and according to S2, water vapor at a reference flow rate as an active oxidizing gas is introduced through the mass flow controller. This is to establish a pre-defined, controlled, trace oxidation atmosphere with an oxidation potential set at an oxidizable level. But not enough to oxidize. Within the window; simultaneously, S3 is activated, and the side feeding device begins to supply the above-mentioned material containing... and The tailings powder raw material; when the powder comes into contact with the melting zone, the reducing impurities contained therein... Immediately Atmospheric reaction, producing by and The characteristic byproduct gas produced by this reaction initially consumes the gas in the process chamber. Threatening the use of oxidation The preset oxidation potential is then determined; at this point, the feedforward compensation control mechanism is activated, and the process gas analyzer located at the exhaust gas outlet detects... and As the concentration increased, this monitoring value was used to adjust S2 in a feedforward manner. The incoming flow rate; the control system increases it in real time. The increased flow rate dynamically compensates for the consumption of the controlled trace oxidation atmosphere by reducing impurities, thus maintaining the effective oxidation potential of the molten zone surface within a preset thermodynamic window. As a result, the dissolved conductive impurities with a segregation coefficient greater than one within the molten zone are reduced. When it diffuses to the surface of the molten zone, it can still be converted into a non-conductive oxide in situ by this stable atmosphere. .

[0026] While the aforementioned chemical transformation is taking place, the physical separation mechanism of S4 is also continuously operating. The electromagnetic mechanical difference caused by induction heating separates the original non-conductive impurities in the powder raw material from those that are... Newly transformed non-conductive oxides Together, they separate from the conductive liquid germanium molten zone and are repelled to the edge of the molten zone; moreover, the supply of raw material powder is not uniform, and its uneven physical morphology causes intermittent powder agglomeration collapse, triggering transient thermal shock; in the specific embodiment, the closed-loop feedback control mechanism responds to this condition, and the radio frequency power supply load signal is subjected to transient analysis to extract the high-frequency disturbance signal characterizing the thermal shock. The signal The proportional-integral control logic is immediately input, and based on... The relationship, in a closed loop, reduced the supply rate of powder raw materials in real time. This suppresses the disturbance of the solid-liquid interface by thermal shock; after a period of time, the continuously separated solids... Other non-conductive impurities accumulate on the surface of the molten zone, causing a slow drift in the low-frequency component of the monitoring system's RF power load signal (i.e., the induction heating coil's RF power supply load signal). When this drift reaches a preset condition, the system determines that the slag accumulation has affected process stability and immediately executes the slag removal process in step S5. According to the timing logic decoupling scheme, the system first executes step 601 to stop the introduction of the controlled trace oxidation atmosphere and then executes step 602 to introduce a large flow rate of high-purity inert gas into the process chamber for physical replacement and purging. After confirming that the atmosphere has returned to inertness, the system intermittently supplies a flux powder, which reacts with high viscosity... The slag reacts and reduces its viscosity, causing it to separate from the molten zone surface. During slag separation, some low-viscosity molten slag droplets splash onto the inner wall of the process chamber. At this point, the gas dynamics protection scheme is activated. The sheath flow, which moves at high speed along the inner wall, forms a gas dynamic barrier, aerodynamically capturing the slag droplets before they contact the quartz tube wall and guiding them to the pre-set collection area. After slag removal and purging, the system resumes the introduction of an oxidizing atmosphere and the supply of powdered raw materials, returning to the synergistic purification state. Throughout the process, the relative movement of the solid-liquid interface in S6 continues, even though the raw material contains... conductive impurities With strong reducing agents Furthermore, the method involves physical thermal shock during the supply process. Through the synergy of chemical transformation and physical repulsion, as well as the parallel operation of feedforward and feedback control systems, it ultimately grows unaffected germanium seed crystals. Contaminated germanium crystals.

[0027] Example 2: To objectively verify the synergistic effect of the controlled trace oxidation atmosphere (S2) and the mechanical difference of Lorentz force (S4) in removing conductive impurities with a segregation coefficient greater than one, and to determine the process window of the oxidation potential, the following comparative experiment was conducted; the experiment used a simulated hydrometallurgical tailings powder raw material. Analysis of the initial state of this raw material revealed that it contained reducible impurities. (converted) Content 5%) and a large amount of non-conductive impurities ( In addition to oxides, 1.0% by mass of elemental silicon with a particle size of less than 10 micrometers was additionally incorporated. The powder was used to simulate conductive impurities with a segregation coefficient greater than 1; the experimental equipment was a high-frequency suspension zone furnace with an induction heating coil operating at a frequency of 3MHz, and the process chamber was equipped with equipment for precise control. A mass flow controller (MFC) system for vapor partial pressure was used; four groups were set up in the experiment, all using the same simulated powder raw material, under the same induction heating power and powder supply rate. The system operates under the conditions of crystal growth rate (S6); the only variable for each group is the parameter of the controlled trace oxidation atmosphere in S2, i.e., the amount of argon incorporated into the main carrier gas (high-purity argon (Ar)). Vapor partial pressure; after crystal growth, samples were taken from the ends of each group of crystals, i.e., the solidification endpoints, and the vapor partial pressure was analyzed using glow discharge mass spectrometry (GDMS). Impurity concentration, and calculate the process flow using material balance algorithm. The oxidation loss rate and experimental data are summarized in Table 1.

[0028] Table 1: Effects of different oxidation atmosphere parameters on Impurity removal and Table of the impact of losses Referring to Table 1, control group A was operated under a pure Ar atmosphere, i.e., S2 was off, at which time the element As a conductive impurity, S4 dissolves in the molten region of liquid germanium. The Lorentz force repulsion effect of S4 has no effect on it, ultimately... Because of The characteristic of this substance is that it continuously accumulates in the solid phase during directional solidification, leading to crystal tip... With a concentration as high as 29.2 ppma, this data indicates that physical separation steps alone cannot remove it. Conductive impurities; Sample 1 of the present invention will The voltage divider is controlled at... atm, crystal end The concentration decreased to 1.5 ppma, but remained above the background level, indicating that the oxidation potential was lower than that of 1.0%. The thermodynamic or kinetic requirements for the complete conversion, coupled with an excessively low oxidation potential setting, lead to incomplete chemical conversion; sample group 2 of this invention will... The partial pressure is increased to atm, this oxidation potential is within a preset window determined based on Ellingham data, at the end of the crystal. The concentration decreased to 0.12 ppma, while The oxidation loss rate remained at a low level of 0.5%, and the data indicates that under these conditions, It is fully converted in situ into a non-conductive oxide. The difference in Lorentz force between S2 and S4 was then effectively separated, confirming the synergistic effect of S2 and S4; control group B will... The partial pressure was further increased to atm, at this point the oxidation potential has exceeded the upper limit of the preset window, and its oxidizing power is no longer lower than the oxidation potential required for germanium in the molten liquid germanium zone, although The concentration was controlled at 0.09 ppma, but The oxidation loss rate surged to 8.5%, indicating that the excessively strong oxidizing atmosphere had caused damage to the host material. It is largely oxidized into volatile substances. This set of data determines the upper limit of the oxidation potential.

[0029] Example 3: In this example, sample group 2 from Example 2 is used as the sample group of the present invention, and control group 1 and control group 2 are set up for comparison; all groups use the same initial state as in Example 2 to simulate powder raw materials, i.e., containing (equivalent to 5%), non-conductive impurities ( (etc.) and an additional 1.0% was added. The raw material of the powder; control group 1 simulates the background technology of ingot casting followed by zone melting; firstly, the above simulated powder raw material is placed in a high-purity graphite crucible and heated at 1100... The material is melted and cast to produce a rough bar with a diameter of 10 mm; in this high-temperature graphite crucible environment, the raw material... Reduced by carbon (C), it undergoes The reaction causes the initial state of the prepared bar stock to be affected. Contamination was detected in the bar stock after sampling and analysis. The impurity concentration was 55.8 ppma; subsequently, this already treated... The contaminated crude bar stock is loaded into a suspension zone furnace and purified by standard suspension zone melting under a pure Ar atmosphere (i.e., without the S2 oxidizing atmosphere); the final crystal has a [missing information - likely referring to a specific crystal structure or process]. The concentration, as determined by GDMS, was 61.5 ppma. This result indicates that the bar stock prepared via this route was purified before zone melting and thus subjected to [a specific process / treatment]. The contamination cannot be removed by subsequent standard zone melting processes. Impurities; Control group 2 uses the exact same process parameters as the sample group of this invention, including atm Pressure division, but the only difference is that S5 is disabled, meaning no flux powder is supplied throughout the entire operation; the process runs normally during the initial startup phase (approximately 1 hour), and S2 will... Transform into The physical separation mechanism of S4 will also function normally. Non-conductive impurities in the raw materials were repelled to the surface of the molten zone; however, after approximately 1.5 hours of operation, a high-viscosity scum layer was observed to accumulate on the surface of the molten zone along with non-conductive oxides. This scum layer disrupted the thermal equilibrium of the molten zone and caused drastic fluctuations in its physical morphology. Ultimately, the scum came into contact with the solid-liquid growth interface, resulting in crystal growth failure. Crystal growth ceased after 1.5 hours. Analysis of the grown crystals revealed that in the initial stage (within 1 hour)... The concentration can be controlled at around 0.15 ppma, but the failure area (at 1.5 hours) contains a large number of physical scum inclusions. See Table 2 for a summary of the test data for each group.

[0030] Table 2: Performance Comparison Table of Sample Group and Control Group of the Invention The data in Table 2 show that control group 1 (conventional route) introduces substances that standard FZ cannot remove, starting from the crucible casting stage. Pollution prevented the production of high-purity crystals; control group 2 (lacking S5) solved the problem. The chemical transformation problem was solved, but the transformation products could not be resolved. The physical accumulation of scum prevents the process from operating stably for extended periods; only when S2 (chemical conversion), S4 (physical separation), and S5 (flux removal) work synergistically (as shown in the sample of this invention) can the process be stabilized. Starting from the tailings powder containing impurities, high-purity germanium crystals are continuously and stably grown.

[0031] Example 4: This example combines Figures 1 to 3 This paper describes a method for the directional solidification purification and crystal growth of trace germanium in hydrometallurgical tailings, as follows: Figure 1As shown, the process begins with a germanium seed crystal, forming a suspended liquid germanium molten zone through S1. This molten zone is maintained by an induction heating coil, which simultaneously monitors the RF power supply load signal. This signal is decoupled into two paths: one path performs high-frequency disturbance transient analysis to characterize transient thermal shock and adjusts the supply rate of hydrometallurgical tailings powder raw material in real time through a closed loop; the other path performs low-frequency drift analysis to determine the slag accumulation state and triggers slag management in S5. On the main process line, the powder raw material and the controlled trace oxidation atmosphere introduced in S2 enter the co-purification treatment stage in S4. This stage separates the material into pure liquid germanium and non-conductive impurities and oxide slag. The pure liquid germanium enters S6 for directional solidification and crystal growth, ultimately obtaining high-purity germanium crystals. The non-conductive impurities and oxide slag enter the slag management stage in S5, where slag separation and removal are achieved by intermittently supplying flux powder. In addition, the process atmosphere forms a feedforward loop through exhaust gas atmosphere monitoring and characteristic by-product gas detection to adjust the oxidation atmosphere flow rate in S2.

[0032] like Figure 2 As shown in the figure, the horizontal axis represents the running time in hours (h), and the vertical axis represents the process stability index in percentage (%). The solid curve representing the lateral feeding method of this invention shows that the process stability index remained above 88% throughout the 12-hour running period. In contrast, the dashed curve representing the conventional method (vertical axial feeding) shows that its process stability index rapidly decreased from 100% to approximately 70% after 2 hours of operation, and then approached 0% after 12 hours. Figure 3 As shown, the bottom is provided with an oxidizing atmosphere / inert gas inlet for introducing gas to form a wall-attached sheath flow that flows upward along the inner wall of the chamber. The gas is finally discharged from the exhaust outlet at the top, and a scum collection area is provided at the top. An induction heating coil is set in the middle of the chamber, and the inside of the coil is an electromagnetic field zone. A grown germanium crystal passes through this zone from bottom to top. The upper end of the crystal is a solid-liquid interface, and above the solid-liquid interface is a liquid germanium melting zone. On one side of the chamber, powdered raw materials are supplied to the edge of the melting zone through a feeding device, and the generated non-conductive impurities are repelled along the separation direction. On the other side of the chamber, flux powder is supplied to the melting zone through a feeding device, and the generated oxide scum is removed along the separation direction.

[0033] Example 5: This example discloses a calibration procedure for determining the parameters of two key control loops in the method of the present invention. This procedure is performed before the actual growth process to ensure the preset conditions for scum monitoring in S5 and the supply rate in step 503. Control logic and The coefficients have engineering basis; calibration is carried out in the same process chamber as in Example 1. The initial state is as follows: S1 is started, and a stable and clean suspended liquid germanium molten zone is formed on the upper end of the germanium seed crystal under a pure argon atmosphere, while maintaining a constant RF power supply of the induction heating coil. At this time, the RF power supply load signal of the induction heating coil is monitored in real time and recorded as a reference signal. To calibrate the preset conditions of S5, namely the trigger threshold for scum accumulation, while maintaining... Based on a stable condition, high-purity germanium is supplied to the surface of the liquid germanium molten zone at a constant rate of 0.1 g / min via a calibrated feeder. The powder serves as a simulated non-conductive impurity component; during the supply process, the RF power load signal is continuously monitored. The low-frequency components are calculated, and their relative frequency to the reference signal is determined. drift amount Simultaneously, the accumulation state on the surface of the liquid germanium molten zone was monitored using an optical pyrometer and video camera system; the experiment observed that when Powder continues to accumulate, The drift amount reached 5.2%. At that time, the video image showed that the slag coverage area exceeded 30% of the surface of the molten zone, and the pyrometer reading began to fluctuate slightly, indicating that the thermal coupling state had changed; then this 5.2% drift amount was set as the trigger threshold in S5 to determine that the cumulative state has reached the preset condition, which is used to automatically trigger the supply of flux powder in the actual process.

[0034] To calibrate the PI control coefficient in step 503, the supply is stopped. Powder and remove slag, allowing the molten zone to return to a clean state. After stabilization, a transient thermal shock test was performed. The test simulated transient thermal shock caused by uneven supply of powdered raw materials in S3 by pulsedly adding a 50mg solid germanium particle to the edge of the liquid germanium molten zone. The system performed transient analysis on the RF power supply load signal to extract high-frequency disturbance signals characterizing the transient thermal shock in the liquid germanium molten zone. Initially and All were set to 0, and observations were made. The signal exhibited a large-amplitude oscillation lasting approximately 1.5 seconds; subsequently, using conventional controller parameter tuning methods in this field, the amplitude was gradually increased. Value, observation The response curve is observed until it exhibits constant amplitude oscillations, and this point is recorded. value and oscillation period Based on this and Value, based on and The standard PI parameter tuning formula is used to calculate and set a set of initial parameters. and Value; 50mg of solid germanium particles were added again for verification, at this time... in accordance with The relationship was adjusted in a closed loop, and observations were made. The signal amplitude was suppressed, the duration was shortened to approximately 0.3 seconds, and there was no overshoot oscillation, indicating that this group and The value can be used for closed-loop real-time adjustment of the supply rate. To effectively suppress transient thermal shock, after this calibration procedure was completed, the determined scum accumulation threshold (5.2%) and PI control coefficient ( The data are stored as process parameters for subsequent continuous purification and crystal growth of hydrometallurgical tailings.

[0035] Example 6: This example is used to verify the impact of the powder raw material supply method in S3 on process stability. The experiment uses the same enabling environment and simulated powder raw material (containing 1.0%) as in Example 2. ), and adopted the process parameters of sample group 2 of the present invention in Example 2 ( ), partial pressure (atm); Two experimental groups were set up, with the only variable being the supply method of the powder raw material in S3; Experimental group 1 (the method of this invention): a side feeding device was used to supply the powder raw material to the edge area of ​​the suspended liquid germanium molten zone; Control group 3 (conventional method): a vertical axial feeding device was used to supply the powder raw material vertically from the top of the induction heating coil to the center area of ​​the suspended liquid germanium molten zone; Operating phenomena of experimental group 1 (the method of this invention): when the powder raw material comes into contact with the high temperature edge of the molten zone, such as in S4, the non-conductive impurities are effectively repelled by the mechanical difference of the Lorentz force, and the volatile impurities are flashed due to the high temperature brought about by the skin effect; the thermal shock of the powder to the center of the molten zone is small, the molten zone morphology remains stable, and the process can run continuously for more than 10 hours.

[0036] The operating phenomena of control group 3 (conventional method): The powder raw material falls vertically and directly impacts the center of the molten zone (the area with a relatively lower temperature and weaker Lorentz force support compared to the edge); a large amount of cold powder and non-conductive impurities rush into the main body of the molten zone, causing a violent transient thermal shock and disrupting the electromagnetic force balance of the molten zone; although the calibrated closed-loop feedback control (step 503) has been activated, the intensity of the impact exceeds the adjustment capability, causing the molten zone to physically collapse after 2.2 hours of operation, and crystal growth fails; the experimental results show that by using S3 to supply the liquid germanium molten zone to the edge of the molten zone through the side feeding device, the high temperature skin effect and strong electromagnetic repulsion effect at the edge of the molten zone can be used to pre-treat and separate the powder raw material, avoiding direct thermal and physical impact on the center of the molten zone.

[0037] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for directional solidification purification and crystal growth of trace germanium in hydrometallurgical tailings, characterized by, In a process chamber comprising an induction heating coil and a process atmosphere control system, a method is performed based on a germanium seed crystal, the method comprising: S1, melting the upper end of the germanium seed crystal by the induction heating coil to form a suspended liquid germanium melt zone; S2, introducing a controlled trace oxidizing atmosphere into the process chamber, the oxidation potential of the trace oxidizing atmosphere being set to be higher than the oxidation potential required by the electrically conductive impurities with a segregation coefficient greater than one dissolved in the melt zone, and lower than the oxidation potential required by germanium in the liquid germanium melt zone; S3, supplying a powder raw material of hydrometallurgical tailings to the surface of the liquid germanium melt zone; S4, using the Lorentz force exerted on the electrically conductive liquid germanium melt zone by the induction heating and the mechanical difference exerted on the non-conductive impurity components in the powder raw material, the non-conductive impurity components are separated from the liquid germanium melt zone, and the trace oxidizing atmosphere in S2 converts the electrically conductive impurities with a segregation coefficient greater than one into non-conductive oxides in situ, and the non-conductive oxides are also separated from the liquid germanium melt zone; S5, monitoring the accumulation state of the non-conductive impurity components and the non-conductive oxides on the surface of the liquid germanium melt zone, and intermittently supplying a flux powder when the accumulation state reaches a preset condition, the flux powder reacts with the non-conductive impurity components and the non-conductive oxides and reduces their viscosity, so that they are separated from the surface of the liquid germanium melt zone; S6, moving the germanium seed crystal relative to the solid-liquid interface of the liquid germanium melt zone to grow a germanium crystal under the synergistic effect of S1 to S5.

2. A method of directional solidification purification and crystal growth of trace germanium in hydrometallurgical tailings according to claim 1, characterized in that, In S4, the non-conductive impurity components and the non-conductive oxides are separated from the liquid germanium melt zone, which also includes: using the skin effect of induction heating to concentrate high-frequency current on the surface of the liquid germanium melt zone and generate high temperature on the surface, and the high temperature makes the volatile impurity components in the powder raw material vaporize and separate when they contact the surface of the liquid germanium melt zone.

3. A method of directional solidification purification and crystal growth of trace germanium in hydrometallurgical tailings according to claim 1, characterized in that, In S2, the controlled trace oxidizing atmosphere is a mixed atmosphere of high-purity inert gas and active oxidizing gas; the high-purity inert gas is argon, and the active oxidizing gas is water vapor; the method further comprises: controlling the flow rate of the active oxidizing gas through a mass flow controller to stabilize the oxidation potential within a preset window, and the preset window is determined according to the Ellingham diagram data of the electrically conductive impurities with a segregation coefficient greater than one and germanium.

4. A method of directional solidification purification and crystal growth of trace germanium in hydrometallurgical tailings according to claim 1, characterized in that, In S5, the flux powder is a metallurgical fluxing agent; and the step of monitoring the accumulation state in S5 includes: using the induction heating coil to monitor the radio frequency power supply load signal of the induction heating coil, and determining whether the accumulation state reaches the preset condition based on the drift of the radio frequency power supply load signal.

5. A method of directional solidification purification and crystal growth of trace germanium in hydrometallurgical tailings according to claim 1, characterized in that, The method further comprises: step 501, monitoring a radio frequency power supply load signal of the induction heating coil in real time; step 502, performing transient analysis on the radio frequency power supply load signal to extract a high-frequency disturbance signal representing a transient thermal shock of the liquid germanium melting zone; and step 503, based on the high-frequency disturbance signal, adopting proportional-integral control logic to close loop and adjust the feeding rate of the powder raw material in S3 in real time , the feeding rate follows: , wherein, is a reference feeding rate, is an amplitude of the high-frequency disturbance signal, and is a control coefficient of the proportional-integral control logic.

6. A method of directional solidification purification and crystal growth of trace germanium in hydrometallurgical tailings according to claim 1, characterized in that, In S2, the stage of introducing the controlled trace oxidizing atmosphere and the stage of intermittently supplying the flux powder in S5 are alternately performed in time; and before switching from the stage of introducing the controlled trace oxidizing atmosphere to the stage of supplying the flux powder, the method further comprises: step 601, stopping the introduction of the controlled trace oxidizing atmosphere; and step 602, introducing a large flow of high-purity inert gas into the process chamber to physically displace and purge the atmosphere above the liquid germanium melt zone, and remove the residual controlled trace oxidizing atmosphere.

7. A method of directional solidification purification and crystal growth of trace germanium in hydrometallurgical tailings according to claim 1, characterized in that, The process chamber has inner walls, the method is performed in an environment with inert gas being fed; and the inert gas is fed in a manner to form a wall-attached sheath flow on the inner walls of the process chamber, the sheath flow constitutes a gas-dynamic barrier; the gas-dynamic barrier contacts and aerodynamically captures and directs the separated non-conductive impurity components and non-conductive oxides to a preset collection area before they condense on the inner walls in S4 and S5.

8. A method of directional solidification purification and crystal growth of trace germanium in hydrometallurgical tailings according to claim 1, characterized in that, The method further comprises: step 801, continuously monitoring the exhaust gas atmosphere of the process chamber to detect a characteristic byproduct gas generated by the reaction of the controlled trace oxidizing atmosphere in S2 with the reducing impurities in the powder feedstock in S3; step 802, based on the concentration of the monitored characteristic byproduct gas, feedforwardly adjusting the flow of the controlled trace oxidizing atmosphere in S2 to adjust and compensate for the consumption of the controlled trace oxidizing atmosphere by the reducing impurities.

9. A method of directional solidification purification and crystal growth of trace germanium in hydrometallurgical tailings according to claim 1, characterized in that, In S3, the powder feedstock is supplied to the edge of the liquid germanium melt zone through a lateral feeding device.

10. A method of directional solidification purification and crystal growth of trace germanium in hydrometallurgical tailings according to claim 1, characterized in that, In S6, while the germanium seed crystal is moved relative to the solid-liquid interface of the liquid germanium melt zone, the soluble impurities in the liquid germanium melt zone are pushed away from the solid-liquid interface by the segregation effect. The process chamber has inner walls, the method is performed in an environment with inert gas being fed; and the inert gas is fed in a manner to form a wall-attached sheath flow on the inner walls of the process chamber, the sheath flow constitutes a gas-dynamic barrier; the gas-dynamic barrier contacts and aerodynamically captures and directs the separated non-conductive impurity components and non-conductive oxides to a preset collection area before they condense on the inner walls in S4 and S5. The method further comprises: step 801, continuously monitoring the exhaust gas atmosphere of the process chamber to detect a characteristic byproduct gas generated by the reaction of the controlled trace oxidizing atmosphere in S2 with the reducing impurities in the powder feedstock in S3; step 802, based on the concentration of the monitored characteristic byproduct gas, feedforwardly adjusting the flow of the controlled trace oxidizing atmosphere in S2 to adjust and compensate for the consumption of the controlled trace oxidizing atmosphere by the reducing impurities. In S3, the powder feedstock is supplied to the edge of the liquid germanium melt zone through a lateral feeding device. In S6, while the germanium seed crystal is moved relative to the solid-liquid interface of the liquid germanium melt zone, the soluble impurities in the liquid germanium melt zone are pushed away from the solid-liquid interface by the segregation effect.

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