A precise temperature control metal refining device and purification process

Abstract

This invention discloses a precision temperature-controlled metal refining apparatus and purification process, belonging to the field of vacuum distillation metal purification technology. The apparatus utilizes a high-insulation structure and heating system to collaboratively construct a steady-state temperature field. Under this temperature field, the molten metal system spontaneously forms a natural stratified structure: a bottom layer of heavy impurities, a middle layer of high-purity gas phase, and an upper layer of light impurities. The central collection channel of the partitioned extraction mechanism corresponds to the middle high-purity gas phase zone, used for directional collection of gaseous products within this zone. This invention reduces reliance on a precision temperature control system and can be used as a standalone device for vacuum distillation purification of various metals, or as an upgrade module added to existing vacuum distillation equipment to achieve energy savings and improved purity. It is suitable for temperature fields of 500℃ to 1500℃ and can prepare metals with purities of 4N to 7N and higher.

Description

Technical Field

[0001] This invention relates to the field of vacuum distillation metal purification technology, specifically to a metal refining apparatus and purification process that constructs a steady-state temperature field through a high-insulation structure and utilizes natural stratification to achieve directional mid-layer collection. Background Technology

[0002] Taking high-purity indium (7N) as an example, existing technologies can stably produce 7N-grade products through multi-step combined processes (such as electrolysis → vacuum distillation → zone melting or staged vacuum distillation → hydrogenation degassing → zone melting). For example, CN119956130A discloses a combined process of staged vacuum distillation with zone melting and hydrogenation degassing; JP4538663B2 discloses a vacuum distillation device that uses medium-frequency induction heating and a two-stage distillation combined with directional solidification; CN119733441B discloses a device and method for bidirectional stepped condensation, which actively controls the temperature gradient by arranging multiple heaters side by side along the length of the condensation zone; CN117180775B discloses a dual-furnace two-stage heating vacuum distillation furnace, which achieves regional collection of metal through temperature gradient changes in the two furnace chambers. All of the above technical solutions have been proven to be industrially feasible and represent the advanced level in the field of vacuum distillation metal purification.

[0003] However, the common feature of the aforementioned existing technologies is that their core logic remains "strong heating + active temperature control"—whether it's multi-stage programmed heating, multi-stage condensation, or multi-furnace temperature gradients, all rely on an external precision temperature control system (PID, multi-sensor feedback regulation, programmed heating rate, etc.) to maintain the target temperature and temperature gradient. This mode has inherent defects: large furnace heat loss and high energy consumption; temperature field stability is highly dependent on temperature control accuracy; temperature field disturbances make it difficult for the liquid phase to form clear and stable convection stratification, limiting the purification efficiency of the distillation process.

[0004] It is worth noting that although some solutions in the aforementioned prior art (such as JP4538663B2) incorporate heat-insulating structures such as graphite carbon felt inside the furnace body, their purpose is merely conventional furnace body insulation. These are basic auxiliary components of the furnace structure and do not utilize "high-insulation heat-insulating structures" as a core technical means to construct a steady-state temperature field and reduce dependence on external active temperature control accuracy. In other words, in the aforementioned prior art, the insulation structure is an auxiliary component that passively receives the results of active temperature control, rather than a dominant factor in actively constructing a steady-state temperature field. No systematic technical solution has yet emerged in this field with "high insulation to construct a steady-state temperature field and reduce dependence on temperature control" as its core concept. This invention addresses this technological gap by providing a universal solution that can operate independently or be embedded in existing processes. Summary of the Invention

[0005] Purpose of the invention The purpose of this invention is to provide a precision temperature-controlled metal refining device and purification process. It constructs a steady-state temperature field through a high-insulation structure and utilizes the principle of natural stratification to achieve directional collection of the middle layer of high-purity gas phase, reducing dependence on the accuracy of external temperature control systems. At the same time, the device can be used as an independent system or as an upgrade module added to existing vacuum distillation equipment to achieve energy-saving purification over a wide purity range (4N to 7N and higher).

[0006] Technical solution A precision temperature-controlled metal refining apparatus, characterized in that it comprises: - Vacuum-sealed cavity (such as Figure 1 (as shown) - High thermal insulation structure (such as Figure 1 As shown in 2a and 2b), at least two layers of gradient composite are used, which contain at least one high-quality thermal insulation material that meets the following thermal conductivity thresholds: thermal conductivity λ≤0.030W / (m·K) when the working temperature is ≤650℃, and thermal conductivity λ≤0.120 W / (m·K) when the working temperature is >650℃. - Heating system (such as Figure 1 As shown in 3a and 3b), it is used to form a working temperature field inside the vacuum-sealed cavity; - Partition extraction mechanism (such as) Figure 1 As shown in 4 and 5), they are arranged along the axial direction and include at least one central acquisition channel; The high-insulation structure works in conjunction with the heating system to maintain a steady temperature field throughout the distillation cycle. Under this steady temperature field, the molten metal system spontaneously forms a natural stratified structure consisting of a bottom layer of heavy impurities, a middle layer of high-purity gas phase, and an upper layer of light impurities. The central collection channel is located in the middle region of the vacuum-sealed cavity and is used to collect the gaseous products in the middle layer of high-purity gas phase after the natural stratified structure is formed.

[0007] The working vacuum of this invention is typically controlled between 1 and 50 Pa, and the axial temperature difference inside the steady-state temperature field is ≤20℃. By relying on a high-insulation structure to suppress forced convection inside the cavity, a low-disturbance environment dominated by molecular diffusion is created, ensuring long-term stability of the stratification.

[0008] The device can be used as an independent system for metal purification, or it can be used to upgrade existing processes by replacing or adding the high-insulation structure to existing vacuum distillation equipment.

[0009] In this invention, the high thermal insulation structure, steady-state temperature field, natural stratification mechanism, and directional mid-layer acquisition strategy are functionally mutually supportive, forming an inseparable technical whole. Specifically: the thermal resistance design of the high thermal insulation structure (λ≤0.030 / 0.120, R≥3.0 m²·K / W) is the physical basis for the formation of the steady-state temperature field, which is a necessary condition for the clear and stable natural stratification. The stable existence of the natural stratification structure, in turn, provides the operational prerequisite for directional mid-layer acquisition through the central acquisition channel.

[0010] Beneficial effects 1. By setting a thermal conductivity threshold (λ≤0.030 / 0.120), the total thermal resistance of the insulation structure reaches above the critical value, significantly improving the system temperature field stability, and making natural stratification a stable phenomenon that can be engineered and relied upon.

[0011] 2. This invention transforms the principle of natural stratification into a directional mid-layer harvesting strategy, enabling the direct acquisition of higher-purity gaseous products (such as 5N-6N) from low-purity raw materials (such as 4N). With the addition of more precise temperature control equipment, metals of 7N and higher purity can be further prepared. Alternatively, the distillation process can be optimized in a multi-step combined process to reduce the burden on subsequent zone melting and other steps, achieving overall energy savings.

[0012] 3. This invention constructs a steady-state temperature field through a high-insulation structure, reducing reliance on active precision temperature control and thus effectively lowering equipment costs and energy consumption. Theoretical estimates show that, compared to traditional vacuum distillation furnaces using conventional insulation layers (thermal conductivity λ≈0.040~0.048 W / (m·K), total thermal resistance R≈2.0~2.5 m²·K / W, outer shell temperature approximately 250℃~350℃), this invention uses threshold-level insulation materials (λ≤0.030 / 0.120) to increase the total thermal resistance to R≥3.0 m²·K / W, reducing the outer shell temperature to 100℃~180℃, and significantly reducing heat loss (theoretically estimated to be over 30%).

[0013] 4. This invention has wide applicability: it can be built as a complete device independently or added to existing vacuum distillation equipment as a modular insulation structure; it is suitable for temperature fields of 500℃~1500℃ and can meet the purification needs of metals with purity levels of 4N~7N and higher (including indium, tin, magnesium, zinc, copper, silver, tungsten, etc.).

[0014] Public literature and theoretical basis The physical parameters and material data involved in the technical solution of this invention are all derived from publicly available literature, national standards, and industry-standard theories, specifically based on the following: 1. Thermal Conductivity Data and Threshold Basis for Insulation Materials: The thermal conductivity thresholds set in this invention (λ≤0.030 at ≤650℃, λ≤0.120 at >650℃) are supported by multiple national standards. GB / T 4272-2008 "General Technical Specifications for Thermal Insulation of Equipment and Pipelines" stipulates that the thermal conductivity of insulation materials shall not exceed 0.12 W / (m·K) at an average temperature of 623K (350℃), and this standard covers insulation projects from -196℃ to 650℃. GB / T 10699-2015 "Calcium Silicate Insulation Products" classifies insulation materials into Type I (650℃) and Type II (1000℃) according to their maximum service temperature, which completely corresponds to the 650℃ temperature boundary of this invention. Furthermore, based on the relevant discussion on the classification of thermal conductivity of insulation materials in "Insulation Technology" (edited by Xu Lie et al., National Defense Industry Press, 1990), and the measured data from recently published academic papers (0.018 W / (m·K) for anisotropic aerogel, 0.025 W / (m·K) for nanofiber ceramic aerogel, and 0.027 W / (m·K) for ceramic-based aerogel), the thermal conductivity of ordinary ceramic fibers at ≤650℃ is approximately 0.040~0.048 W / (m·K). The above data and standards collectively indicate that the thermal conductivity threshold set in this invention is the critical dividing line for upgrading the performance of insulation materials from "conventional level" to "high-level level," and its dividing temperature of 650℃ is consistent with the maximum service temperature of Type I products in GB / T 10699-2015. The thermal conductivity test method is based on GB / T 10297-2015 "Determination of thermal conductivity of non-metallic solid materials by hot wire method", and the classification and naming of thermal insulation materials are based on GB / T3003-2017 "Refractory fibers and products".

[0015] 2. Calculation of Thermal Resistance and Thermal Time Constant: Based on the formulas for calculating the total thermal resistance of multi-layer insulation structures, R_total = ∑(d_i / λ_i) and the thermal time constant formula τ = R × C, found in *Heat Transfer* (edited by Tao Wenquan, Higher Education Press, 6th edition, 2024, ISBN 978-7-04-062027-6), under typical insulation thicknesses (100mm-300mm), the total thermal resistance is approximately 2.0-2.5 m²·K / W when using conventional insulation materials (λ≈0.040-0.048); when using the threshold-level insulation material of this invention (λ≤0.030), the total thermal resistance can be increased to over 3.0 m²·K / W. According to τ = R × C, the increase in thermal resistance leads to a significant increase in the thermal time constant, extending the system's response time to temperature fluctuations and improving temperature field stability. The above-mentioned thermal resistance calculation principle is also recorded in *Insulation Technology* (1990).

[0016] 3. Vacuum Distillation and Natural Stratification Theory: Based on the theories of vacuum distillation metal separation, the influence of vapor pressure differences and temperature field stability on fractionation effects in *Vacuum Metallurgy of Nonferrous Metals* (edited by Dai Yongnian and Yang Bin, Metallurgical Industry Press, 2nd edition, 2009, ISBN 978-7-5024-4806-6) and *Vacuum Metallurgy of Nonferrous Metal Materials* (edited by Dai Yongnian and Yang Bin, Metallurgical Industry Press, 2000, ISBN 7-5024-2464-4), and the latest research progress on vacuum distillation of alloys and crude metals, and purification of rare and precious metals in *Fundamentals of Vacuum Metallurgy of Nonferrous Metals* (by Yang Bin, Xu Baoqiang, Kong Lingxin, and Jiang Wenlong, Metallurgical Industry Press, December 2023, ISBN 978-7-5024-9348-6), vacuum distillation technology can achieve axial stratification and separation of components under low-disturbance conditions based on differences in boiling point, vapor pressure, and density.

[0017] 4. Low-disturbance environment and convection suppression mechanism: Public literature indicates that vacuum insulation panels are designed based on the principle of "vacuuming to suppress natural convection heat transfer, making the gas in a purely thermally conductive state." Research has confirmed that by removing air to make the mean free path of air greater than the pore size of the porous material, heat conduction of the gas can be effectively suppressed. The above mechanism is also recorded in "Insulation Technology" (1990). This invention applies the above principle to the high-insulation structure of a metal vacuum distillation device, relying on the high-insulation structure to suppress forced convection within the cavity, creating a low-disturbance environment dominated by molecular diffusion, and ensuring long-term stability of stratification.

[0018] 5. Energy-saving effect of high-efficiency insulation materials: According to published literature (such as the research results of new vacuum insulation panels from Nanjing University of Technology), the energy-saving effect of high-efficiency insulation materials can be 10-20 times higher than that of traditional insulation materials; industrial application data shows that using high-efficiency insulation materials can reduce the outer wall temperature of industrial furnaces by 20-50℃, and the energy saving rate can reach 10%-40%. The heat loss estimated in this invention is significantly reduced and falls within the reasonable range of the above-mentioned published data.

[0019] It should be noted that the core characteristic of the high-quality thermal insulation material described in this invention is that it meets the threshold requirements of thermal conductivity λ≤0.030 W / (m·K) when the working temperature is ≤650℃ and thermal conductivity λ≤0.120 W / (m·K) when the working temperature is >650℃. These thresholds are based on engineering calculations of the multi-layer gradient composite insulation structure used in this invention at typical insulation thicknesses, and comply with the basic requirements of GB / T 4272-2008 for the thermal conductivity of insulation materials. Within the insulation thickness range set by this invention, only when the thermal conductivity of the insulation material drops below this threshold can the total thermal resistance R of the system reach R≥3.0m²·K / W, thereby enabling the system to transition from "passive temperature field fluctuations" to "active steady state," and natural stratification becoming a stable phenomenon that can be relied upon in engineering. Therefore, this threshold is the critical condition for achieving the core technical effect of this invention.

[0020] As long as the thermal conductivity of a material reaches this threshold, regardless of its specific composition, trade name, or manufacturing process, it falls within the protection scope of the high-quality thermal insulation materials described in this invention. The aerogel composite insulation materials, high-performance ceramic fibers, high-performance glass fibers, vacuum insulation panels, etc., listed in the embodiments are merely illustrative examples and not exhaustive. Any thermal insulation material that meets the above-mentioned thermal conductivity threshold—including but not limited to novel nanocomposite insulation materials, novel aerogel variants, novel microporous insulation materials, etc.—can be used in this invention and falls within the protection scope of the claims. Attached Figure Description

[0021] Figure 1 Overall structural diagram Figure 1 The complete device structure of the present invention is shown, highlighting: the layering and material matching of the multi-layer gradient insulation structure (2a, 2b); the arrangement of the bottom heating zone (3a) and the side wall heating zone (3b) of the heating system; the middle collection channel (4) and the upper collection channel (5) of the gas phase collection system, and the corresponding middle condenser (6) and upper light impurity collector (7), both of which can be connected to multiple furnaces for centralized condensation and collection; industrial expansion configuration—feeding device (8), slag collection device (9) and reserved interface (10) for connecting multiple furnaces; the top of the cavity is equipped with control devices such as vacuum / pressure control / sensing / heating / temperature control; the cavity is an integrated furnace structure, and its bottom is a raw material holding area for storing thin layers of raw materials. The feeding device (8) is located in the bottom area of ​​the integrated furnace body, which can realize the sealed feeding operation of various forms of raw materials such as block solids, powders and liquids.

[0022] The numbers in the diagram mean: - 1: Vacuum-sealed cavity - 2a: Inner high-temperature resistant lining (ceramic fiber / refractory brick) - 2b: Outer high-performance thermal insulation layer (aerogel / high-performance thermal insulation felt) - 3a: Bottom heating zone - 3b: Side wall heating zone - 4: Central collection channel (can be connected to multiple furnaces for centralized condensation collection) - 5: Upper collection channel (can be connected to multiple furnaces for centralized condensation collection) - 6: Central condenser (the central collection tank connected to it is not separately numbered) - 7: Upper light impurity collector - 8: Feeding device (optional, suitable for continuous feeding; the figure shows bottom feeding method, which is particularly suitable for sealed injection of liquid or low melting point metal raw materials, which can avoid splashing and disturbance to the layered structure caused by top feeding, and can also be used for block solid and powder raw materials through different feeding structures) - 9: Slag collection device (optional, adapted for slag discharge operation) - 10: Reserved interface for multi-furnace connection (optional, adaptable to series / parallel connection)

[0023] Figure 2 Schematic diagram of steady-state temperature field and natural stratification principle like Figure 2 As shown, under steady-state temperature field, a three-layered structure naturally forms within the cavity—the bottom layer is the heavy impurity region (A), the middle layer is the high-purity gas phase region (B), and the top layer is the light impurity region (C). The middle collection channel (4) and the upper collection channel (5) correspond to the collection positions of regions B and C, respectively. The figure divides the three regions into three areas with horizontal dashed lines. Only the thin-layer raw material region (raw material holding area + thin-layer raw material) is drawn at the bottom, with most of the space being the gas phase region, to reflect the actual physical state of vacuum distillation. The figure marks features such as minimal axial temperature difference, heat transfer direction from bottom to top, and molecular diffusion dominance (indicated by short arrows). Detailed Implementation

[0024] It should be noted that the accompanying drawings are illustrative examples of specific embodiments, and the actual structure can be flexibly adjusted according to the application scenario. The present invention is not limited to the specific implementation shown in the drawings. The present invention will be further described below with reference to embodiments, but the present invention is not limited to these embodiments.

[0025] Example 1 (Standalone device: Tin purification) This embodiment uses the vacuum distillation purification of metallic tin as an example. The vacuum-sealed cavity is cylindrical, with an inner diameter of approximately 300 mm and a height of approximately 500 mm. The high-insulation structure adopts a three-layer gradient structure: the inner layer is ceramic fiber (λ≤0.030@650℃), the middle layer is mullite fiber, and the outer layer is aerogel composite insulation material (λ≤0.120@>650℃). The inner layer insulation thickness is 80-120 mm, and the outer layer insulation thickness is 100-180 mm. The heating system uses resistance heating and is located at the bottom and side walls. The zoned extraction mechanism includes a central collection channel and an upper collection channel, which are respectively connected to an external condensation collection device.

[0026] After the tin raw material (4N) to be purified is added to the chamber, a vacuum of 5–20 Pa is applied, and the heating system is activated to bring the interior of the chamber to the operating temperature (approximately 1000℃–1100℃). The constant-temperature distillation process lasts 2–4 hours. Under the influence of the high-insulation structure, a steady-state temperature field is formed inside the chamber, with an axial temperature difference ≤20℃, suppressing natural convection. The molten metal system spontaneously forms a three-layer structure: the bottom layer is a high-boiling-point impurity (e.g., iron, copper) enrichment zone, the middle layer is a high-purity tin vapor phase zone, and the top layer is a low-boiling-point impurity (e.g., arsenic, antimony) enrichment zone. The central collection channel collects gas from the middle high-purity vapor phase zone, which is then externally condensed to obtain a high-purity tin product with a purity ≥5N. Energy consumption is reduced by approximately 35% compared to traditional equipment.

[0027] Example 2 (Standalone device: Magnesium metal purification) The operating temperature is approximately 700℃-800℃. The high-insulation structure adopts a double-layer gradient structure: the inner layer is alumina fiber, and the outer layer is a high-performance thermal insulation felt. The remaining structure is the same as in Example 1. Under a steady-state temperature field, natural stratification occurs, with the central acquisition channel directionally acquiring high-purity magnesium gas phase (purity increased from 3N to 5N), and the outer shell temperature controlled below 120℃.

[0028] Example 3 (Modular Upgrade: Applied to the Distillation Stage of the Existing 7N Indium Process) An existing high-purity indium production process (such as 7N grade) adopts a combined route of "stage vacuum distillation → hydrogenation degassing → zone melting". Its distillation equipment uses a conventional insulation layer (λ≈0.045@650℃) and requires multiple stages of programmed heating (heating rate 1℃ / min, holding time 2h, etc.) to maintain the temperature gradient, which requires high temperature control accuracy.

[0029] The original equipment's insulation layer is replaced by the high-insulation structure (three-layer gradient, total thermal resistance R≥3.0 m²·K / W) of this invention, while the rest of the heating system, vacuum system, and subsequent processes remain unchanged. After the modification, the distillation chamber enters a steady-state temperature field with clear natural stratification. The central acquisition channel can directly obtain indium vapor with higher purity (e.g., from 5N in the original process to 6N, and further to 7N if combined with higher-precision temperature control equipment). This reduces the burden on subsequent hydrogenation and zone melting, lowers overall energy consumption by approximately 25%, and significantly reduces the requirements for active temperature control accuracy while still maintaining stable operation.

[0030] Example 4 (Universality of different metals) The high thermal insulation structure of this invention allows for adjustment of materials and thickness according to operating conditions: For low-temperature conditions (500℃~800℃, such as indium, magnesium, and zinc), double-layer insulation can be used, with a target thermal resistance R≥2.5 m²·K / W; for medium-temperature conditions (800℃~1100℃, such as copper, aluminum, and nickel), a three-layer gradient structure is used, with R≥3.5 m²·K / W; for high-temperature conditions (1200℃~1500℃, such as tungsten and molybdenum), a four-layer gradient structure is used, with R≥4.5 m²·K / W. The heating method, vacuum system, and condensation collection device all employ conventional techniques known in the art and are not intended to limit the scope of the invention.

[0031] Example 5 (Industrialization Expansion: Continuous Feeding, Slag Removal, and Multi-Furnace Co-operation) The apparatus of this invention can be configured with known auxiliary systems according to production scale requirements to achieve continuous and automated operation. It should be noted that the specific structures of these auxiliary systems (such as continuous feeding, slag discharge, multi-furnace connection, etc.) already have publicly available mature solutions (for example, CN105506300A discloses a precious lead vacuum distillation furnace using a continuous feeding method), and the aforementioned auxiliary systems do not constitute essential technical features of this invention, nor do they limit the scope of protection of this invention. Specific details are as follows, but this invention is not limited thereto:

[0032] (1) Continuous or semi-continuous feeding system The feeding device is located in the bottom area of ​​the integrated furnace body (see Figure 1 (No. 8) This device enables sealed feeding of various raw materials, including lumpy solids, powders, and liquids. A vacuum valve or rotary feeder (such as a star-shaped feeder) is installed between the feeding device and the cavity. When the raw material level in the cavity drops or when additional raw materials are needed, the feeding valve can be opened, and new raw materials can be directly fed into the bottom cavity of the integrated furnace body by gravity or screw conveyor. The feeding process maintains the vacuum environment inside the furnace, making it suitable for continuous raw material replenishment operations.

[0033] (2) Slag removal system A slag discharge port is located at the lowest point of the integrated furnace body. The slag discharge port is connected to a slag discharge pipe with a valve and a slag collection tank (see [reference]). Figure 1 (No. 9). When high-boiling-point impurities and heavy impurities in the raw materials accumulate to a certain level, heating can be paused, the temperature lowered, and the slag discharge valve opened to allow gravity to discharge the liquid or solid slag from the chamber. The slag discharge operation can be performed periodically to maintain the effective activity of the raw materials in the chamber. The slag discharge system can adopt the existing "bottom-mounted slag discharge device" or "side-mounted slag scraping mechanism" used in vacuum furnaces. The device of this invention only needs to be pre-installed with a slag discharge interface for adaptation.

[0034] (3) Multi-furnace combined system (parallel / series) To achieve large-scale continuous production, multiple refining devices described in this invention can be connected in parallel or in series (see [link]). Figure 1 (Middle number 10 indicates connection to reserved interface) - Parallel mode: Multiple distillation units share a set of raw material pretreatment system and a set of product collection system, each operating independently to increase total capacity; - Series mode: The product collected in the middle of the first-stage distillation unit is directly used as the raw material for the second-stage distillation unit (or is added again after intermediate condensation) to achieve multi-stage gradient purification and further improve the purity of the final product.

[0035] When multiple furnaces are connected in series, the temperature gradient and insulation layer thickness of each distillation unit can be optimized according to the boiling point distribution of the target metal, so as to achieve the best balance between energy consumption and product purity of the entire production line. Material transportation between distillation units can be achieved using existing technologies such as vacuum pipelines, gas transportation, or melt pumps.

[0036] The aforementioned feeding, slag removal, and multi-furnace systems are all well-known auxiliary technologies in the field of metal vacuum distillation. The inventive contribution of this invention lies in providing a core distillation unit with a high-insulation structure, capable of constructing a steady-state temperature field and achieving natural stratified directional collection. Any production system constructed by combining the core distillation unit described in this invention with the aforementioned well-known auxiliary systems is an extension of the technical solution of this invention and falls within the protection scope of this invention.

Claims

1. A precision temperature-controlled metal refining apparatus, characterized in that, include: Vacuum-sealed cavity; The high thermal insulation structure adopts at least two layers of gradient composite form, and contains at least one high-quality thermal insulation material that meets the following thermal conductivity thresholds: thermal conductivity λ≤0.030 W / (m·K) when the working temperature is ≤650℃, and thermal conductivity λ≤0.120 W / (m·K) when the working temperature is >650℃. A heating system is used to create a working temperature field inside the vacuum-sealed cavity; A partitioned extraction mechanism is arranged along the axial direction, including at least one central acquisition channel; The high-insulation structure works in conjunction with the heating system to maintain a steady temperature field throughout the distillation cycle and suppress forced convection within the cavity, forming a low-disturbance environment dominated by molecular diffusion to ensure the stability of natural stratification. Under this steady temperature field, the molten metal system spontaneously forms a natural stratified structure consisting of a bottom layer of heavy impurities, a middle layer of high-purity gas phase, and an upper layer of light impurities. The central collection channel is located in the middle region of the vacuum-sealed cavity and is used to collect the gaseous products in the middle layer of high-purity gas phase after the natural stratification structure is formed.

2. The apparatus according to claim 1, characterized in that, The high thermal insulation structure has a total thermal resistance R≥3.0m²·K / W.

3. The apparatus according to claim 1, characterized in that, The high-quality thermal insulation material is a thermal insulation material that meets the thermal conductivity threshold requirement, including but not limited to one or more of aerogel composite thermal insulation materials, high-performance ceramic fibers, high-performance glass fibers, and vacuum insulation panels.

4. The apparatus according to claim 1, characterized in that, The partitioned extraction mechanism also includes an upper collection channel located in the upper region of the cavity, used to collect gaseous products in the upper light impurity region.

5. The apparatus according to claim 1, characterized in that, The central acquisition channel is located within 30% to 70% of the total axial height of the vacuum-sealed cavity.

6. The apparatus according to claim 1, characterized in that, The high thermal insulation structure adopts a three-layer gradient composite form, including an inner high-temperature resistant lining, a middle layer of mullite fiber, and an outer layer of aerogel composite insulation material.

7. The apparatus according to claim 1, characterized in that, The heating system includes a bottom heating zone and a side wall heating zone.

8. A precision temperature-controlled metal refining and purification process, characterized in that, Includes the following steps: (1) After loading the metal raw material to be purified into the vacuum-sealed cavity, the cavity is sealed and a vacuum is drawn. (2) Start the heating system to raise the temperature to the target distillation temperature and maintain the temperature constant; (3) Maintain a steady temperature field inside the cavity by means of a high thermal insulation structure, and allow the gas phase components to be stably separated by static placement; (4) High-purity gaseous products in the middle layer are extracted directionally through the central acquisition channel; (5) The gaseous products are sent to a condenser for condensation and collection to obtain high-purity metal.

9. The process according to claim 8, characterized in that, The high thermal insulation structure has a total thermal resistance R≥3.0m²·K / W.

10. The process according to claim 8, characterized in that, The high-quality thermal insulation material is a thermal insulation material that meets the thermal conductivity threshold requirement, including but not limited to one or more of aerogel composite thermal insulation materials, high-performance ceramic fibers, high-performance glass fibers, and vacuum insulation panels.

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