Method and equipment for purifying metal antimony
By using a multi-stage condensation tower and temperature gradient control method, the problem of efficiently separating impurities such as arsenic in metallic antimony in existing technologies has been solved, achieving efficient purification of high-purity antimony with a product purity of 99.999%.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHENGDU MAIHE SEMICONDUCTOR MATERIALS CO LTD
- Filing Date
- 2026-03-24
- Publication Date
- 2026-05-12
AI Technical Summary
Existing technologies are insufficient for efficiently separating and removing impurities such as arsenic from metallic antimony. In particular, since arsenic and antimony are elements in the same group and have similar physicochemical properties, single-stage distillation is insufficient to remove arsenic to a depth of less than 1 ppm, which affects product purity.
A multi-stage condenser is adopted, which is set up in the vertical direction with a lower high-temperature reflux section, a middle medium-temperature transition section and an upper low-temperature collection section. Combined with precise temperature gradient control, selective condensation is achieved by utilizing the difference between the saturated vapor pressure and condensation temperature of different elements. The inverted conical reflux structure of the middle medium-temperature transition section allows some antimony vapor containing intermediate impurities to flow back to the evaporation zone to participate in evaporation and condensation again, so as to achieve multiple gas-liquid balances.
It significantly improves separation efficiency, effectively removing impurities such as arsenic to below 1 ppm, and controlling the content of lead and bismuth to below 0.5 ppm, achieving a product purity of 99.999%, with a separation effect far superior to single-stage distillation.
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Figure CN122012950A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of antimony purification technology, and more specifically, to a method and apparatus for purifying metallic antimony. Background Technology
[0002] Antimony, as an important strategic rare metal, is widely used in semiconductors, infrared detectors, battery alloys, flame retardants, and other fields. With the rapid development of high-tech industries such as aerospace, remote sensing, and infrared detection, the demand for high-purity antimony (purity ≥99.999%, i.e., 5N grade) and even ultra-pure antimony (purity ≥99.9999%, i.e., 6N grade) is becoming increasingly urgent. Trace amounts of impurities in high-purity antimony, especially arsenic (As), lead (Pb), bismuth (Bi), and iron (Fe), can significantly affect its photoelectric properties and the quality of compound semiconductor materials.
[0003] Currently, the main methods for preparing high-purity antimony include electrolytic refining, zone melting, vacuum distillation, and combinations thereof. Existing methods for preparing antimony compounds from antimony ore or antimony white have limitations in product purity, making it difficult to achieve purity levels above 5N. While some existing methods can effectively improve product purity to meet the 5N requirement, they suffer from long process flows, numerous equipment requirements, and low efficiency.
[0004] For the purification of antimony, vacuum distillation can be used. The principle of vacuum distillation for metal purification is that different elements have different saturated vapor pressures under vacuum conditions. Existing vacuum distillation technology usually adopts a single-stage evaporation to condensation method, that is, antimony is evaporated at a certain temperature and then condensed and collected on a condenser plate. However, since arsenic and antimony are elements in the same group and have similar physicochemical properties, single-stage distillation is difficult to remove arsenic to a depth of less than 1 ppm. At the same time, for intermediate impurities with saturated vapor pressures between antimony and arsenic (such as sulfur, selenium, etc.), single-stage distillation often causes them to volatilize and condense along with antimony, affecting the purity of the product.
[0005] Therefore, there is a market demand for a high-purity antimony purification method that has high separation efficiency and can effectively remove impurities such as arsenic at the same time. Summary of the Invention
[0006] The purpose of this invention is to provide a method for purifying metallic antimony, which can improve separation efficiency and effectively remove impurities such as arsenic at the same time, thereby improving the purification effect.
[0007] Another object of the present invention is to provide an apparatus for implementing the above-described method for purifying metallic antimony.
[0008] The embodiments of the present invention are implemented as follows: This application provides a method for purifying metallic antimony, comprising the following steps: S101. Place the crude antimony raw material in the evaporation zone of a sealed vacuum furnace; S102. Evacuate the furnace body to bring the internal pressure to 0.1Pa~1.0Pa; S103. Heat the evaporation zone to 700℃~800℃ to melt and evaporate the crude antimony, producing a mixed vapor of antimony and impurity elements; S104. The mixed vapor moves upward and passes sequentially through a multi-stage condenser tower arranged vertically. The condenser tower is divided into three temperature zones from bottom to top vertically: The temperature in the lower high-temperature reflux section is controlled between 580℃ and 620℃. In the middle-temperature transition zone, the temperature is controlled between 450℃ and 550℃. The upper low-temperature collection section has a temperature controlled between 120℃ and 400℃. S105, high-purity antimony vapor crystallizes and precipitates on the selective condenser plate in the lower high-temperature reflux section to form the main product; S106. Some of the antimony vapor containing intermediate impurities condenses in the middle medium-temperature transition section and flows back to the evaporation zone to participate in the evaporation to condensation process again. S107. Volatile impurity vapors are condensed and captured in the upper low-temperature collection section; S108. After distillation, high-purity antimony main product is obtained from the lower high-temperature reflux section, intermediate product containing intermediate impurities is obtained from the middle medium-temperature transition section, and impurity enrichment is obtained from the upper low-temperature collection section.
[0009] In some embodiments of the present invention, the crude antimony raw material mentioned in step S101 is industrial crude antimony with a purity of ≥99.99%, which is crushed to a particle size of 20-40 mm before use.
[0010] In some embodiments of the present invention, the heating rate of the heating evaporation zone in step S103 is 5-10°C / min, and it is kept at 300°C and 500°C for 20-40 minutes respectively.
[0011] In some embodiments of the present invention, the temperature control accuracy of the three temperature zones described in step S104 above is ±10℃.
[0012] In some embodiments of the present invention, the reflux to the evaporation zone mentioned in step S106 is specifically an inverted conical reflux structure provided on the inner wall of the condenser tower in the middle medium-temperature transition section, which is used to allow some antimony vapor containing intermediate impurities to condense and adhere to the surface of the inverted conical reflux structure. The cone angle of the inverted conical reflux structure is 30° to 60°.
[0013] In some embodiments of the present invention, the distillation time is 12 to 18 hours.
[0014] In some embodiments of the present invention, the purity of the above-mentioned high-purity antimony main product is ≥99.999%, wherein the arsenic content is ≤1ppm, the lead content is ≤0.5ppm, and the bismuth content is ≤0.5ppm.
[0015] Secondly, embodiments of this application provide an apparatus for implementing the above-described method for purifying metallic antimony, comprising: Vertical vacuum furnace body; A vacuum system connected to the furnace body is used to achieve and maintain the required vacuum level inside the furnace; An evaporation zone is located at the bottom of the furnace body, and the evaporation zone is equipped with a crucible for holding raw materials and a heating device. A multi-stage condensing tower is installed above the evaporation zone, and the condensing tower is arranged vertically from bottom to top as follows: The lower high-temperature reflux section is equipped with a first temperature control unit and a first condenser plate. The middle temperature transition section contains a second temperature control unit and an inverted conical reflux structure. The upper low-temperature collection section is equipped with a third temperature control unit and a second condenser plate. The product collection unit, intermediate product collection unit, and impurity collection unit are respectively connected to the lower high-temperature reflux section, the middle medium-temperature transition section, and the upper low-temperature collection section; A multi-point thermocouple temperature monitoring system, and PID controllers connected to the first temperature control unit, the second temperature control unit, and the third temperature control unit respectively.
[0016] In some embodiments of the present invention, the above-mentioned inverted conical reflux structure is a multi-layered inverted conical guide plate disposed on the inner wall of the condenser tower, and an airflow channel and a reflux channel are formed between adjacent guide plates.
[0017] In some embodiments of the present invention, the vacuum system described above includes a vacuum pump in communication with the furnace body.
[0018] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects: This invention provides a method for purifying metallic antimony. By vertically configuring a condenser tower with a lower high-temperature reflux section, a middle medium-temperature transition section, and an upper low-temperature collection section, and by controlling the temperature steps, a precise temperature gradient is established. Utilizing the differences in saturated vapor pressure and condensation temperature between different elements, antimony and impurities with different volatility characteristics are selectively condensed in each temperature zone, achieving stepped separation. The separation speed is significantly higher than single-stage distillation, significantly improving separation efficiency. Specifically, some antimony vapor containing intermediate impurities in the middle medium-temperature transition section is refluxed back to the evaporation zone after condensation, allowing the condensate containing intermediate impurities to participate in the evaporation and condensation cycle again. In this process, some antimony vapor containing intermediate impurities is allowed to participate in the reaction again in the evaporation zone through reflux, thus achieving multiple purification effects of evaporation, fractional condensation, reflux, and re-evaporation in a single distillation process. This step is equivalent to achieving multiple gas-liquid equilibrations in a single distillation process, significantly increasing the theoretical plate number and significantly improving the separation effect, especially for the removal of intermediate impurities such as sulfur and selenium.
[0019] Furthermore, this invention also provides an apparatus for purifying metallic antimony. Within a condensation tower, a lower high-temperature reflux section, a middle medium-temperature transition section, and an upper low-temperature collection section are sequentially arranged from bottom to top. Utilizing the principle of natural hot air rising, a stable temperature gradient field is formed, enabling zoned condensation of substances with different volatility characteristics. The temperature control units corresponding to the lower high-temperature reflux section, the middle medium-temperature transition section, and the upper low-temperature collection section can flexibly adjust the temperature of each zone according to the impurity profile of the raw material, improving the separation effect and efficiency. For example, when processing high-arsenic raw materials, the temperature of the upper low-temperature section can be appropriately lowered to enhance arsenic collection capacity; when processing high-sulfur raw materials, the temperature of the middle transition section can be adjusted to optimize the reflux effect. Specifically, the inverted conical reflux structure located in the middle medium-temperature transition section uses a cone angle of 30°-60°, allowing some antimony vapor containing intermediate impurities to flow naturally towards the edge along the conical surface of the inverted conical reflux structure after condensation, and then flow back to the evaporation zone through the edge gap. Guided by the inverted conical reflux structure, the condensate containing intermediate impurities is refluxed to the evaporation zone for re-evaporation, which is equivalent to achieving multiple gas-liquid balances in a single unit. The theoretical plate number is much higher than that of single-stage distillation, and the separation effect is significantly improved. Attached Figure Description
[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 This is a schematic diagram of the cross-sectional structure of an embodiment of the present invention; Figure 2 This is a three-dimensional contour diagram of an embodiment of the present invention.
[0022] Icons: 1-Furnace body; 2-Vacuum pump; 3-Crucible; 4-Condensation tower; 5-First condensing plate; 6-Inverted conical guide plate; 7-Second condensing plate; 8-Collection pipeline; 9-Impurity collection pipe. Detailed Implementation
[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0024] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.
[0025] In the first embodiment, this embodiment provides a method for purifying metallic antimony, including the following steps: S101. Place the crude antimony raw material in the evaporation zone of a sealed vacuum furnace; S102. Evacuate the furnace body to bring the internal pressure to 0.1Pa~1.0Pa; S103. Heat the evaporation zone to 700℃~800℃ to melt and evaporate the crude antimony, producing a mixed vapor of antimony and impurity elements; S104. The mixed vapor moves upward and passes sequentially through a multi-stage condenser tower arranged vertically. The condenser tower is divided into three temperature zones from bottom to top vertically: The temperature in the lower high-temperature reflux section is controlled between 580℃ and 620℃. In the middle-temperature transition zone, the temperature is controlled between 450℃ and 550℃. The upper low-temperature collection section has a temperature controlled between 120℃ and 400℃. S105, high-purity antimony vapor crystallizes and precipitates on the selective condenser plate in the lower high-temperature reflux section to form the main product; S106. Some of the antimony vapor containing intermediate impurities condenses in the middle medium-temperature transition section and flows back to the evaporation zone to participate in the evaporation to condensation process again. S107. Volatile impurity vapors are condensed and captured in the upper low-temperature collection section; S108. After distillation, high-purity antimony main product is obtained from the lower high-temperature reflux section, intermediate product containing intermediate impurities is obtained from the middle medium-temperature transition section, and impurity enrichment is obtained from the upper low-temperature collection section.
[0026] The principle of this embodiment is based on the fact that different elements have different saturated vapor pressures and condensation temperatures under vacuum conditions. Volatile impurities such as arsenic (As) tend to condense in lower temperature regions, while non-volatile impurities such as bismuth (Bi) and lead (Pb) remain in the evaporation zone or higher temperature regions. In this embodiment, by precisely controlling multiple temperature zones at different heights of the distillation column (lower high-temperature reflux section, controlled at 580℃~620℃; middle medium-temperature transition section, controlled at 450℃~550℃; upper low-temperature collection section, controlled at 120℃~400℃), not only is the high-purity antimony vapor selectively crystallized and precipitated in the lower high-temperature reflux section, but impurity vapors that have not yet condensed also continue to migrate upwards to the cooler upper low-temperature collection section for collection. More importantly, in the middle medium-temperature transition section, some of the condensed intermediate products (containing certain impurities) are allowed to reflux back to the evaporation zone to participate in the reaction again, thus achieving multiple purification effects of evaporation, condensation, reflux, and re-evaporation in a single distillation process, greatly improving separation efficiency.
[0027] Specifically, in the above steps, under vacuum conditions, antimony is melted and evaporated in the heating evaporation zone, producing a mixed vapor of antimony and impurity elements. This mixed vapor first enters the lower high-temperature reflux section, where the antimony vapor condenses and crystallizes to obtain the highest purity, silvery-white, dense antimony crystals. Subsequently, the remaining mixed vapor enters the middle medium-temperature transition section and is further condensed. Some of the intermediate impurities, such as sulfur and selenium, in the condensate flows back along the conical surface to the lower evaporation zone, achieving re-evaporation and condensation. The remaining intermediate impurities, such as sulfur and selenium, in the middle medium-temperature transition section are recovered after the entire separation process is completed. Finally, the mixed vapor after passing through the middle medium-temperature transition section enters the upper low-temperature collection section and is condensed again, yielding a grayish-black arsenic-rich condensate. In the above process, a precise temperature gradient is established through temperature step control. By utilizing the difference between the saturated vapor pressure and condensation temperature of different elements, antimony and impurities with different volatility characteristics are selectively condensed in each temperature zone, achieving stepwise separation. This separation rate is much higher than single-stage distillation, significantly improving separation efficiency. In the intermediate temperature transition section, some antimony vapor containing intermediate impurities is condensed and then refluxed back to the evaporation zone, allowing the condensate containing intermediate impurities to participate in the evaporation and condensation cycle again. In this process, some antimony vapor containing intermediate impurities can be returned to the evaporation zone via reflux to participate in the reaction again, thus achieving multiple purification effects of "evaporation, condensation, reflux, and re-evaporation" in a single distillation process. This step is equivalent to completing multiple gas-liquid equilibrations in a single distillation process, significantly increasing the theoretical plate number and greatly improving the separation effect, especially for the removal of intermediate impurities such as sulfur and selenium.
[0028] Preferably, the crude antimony raw material mentioned in step S101 is industrial crude antimony with a purity ≥99.99%, crushed to a particle size of 20-40 mm before use. This specific purity and particle size of the crude antimony raw material provides a good foundation for the subsequent purification process. Higher purity industrial crude antimony can reduce the content of impurities and reduce the difficulty of purification. Crushing it to a particle size of 20-40 mm can increase the specific surface area of the raw material, making the exchange of substances more complete and efficient in the subsequent evaporation and condensation processes. Limiting the purity of the crude antimony raw material to ≥99.99% (4N grade) means that the total impurity content in the raw material does not exceed 100 ppm. This initial impurity load is within the range that can be effectively handled in this embodiment. If the purity of the raw material is lower than this limit (such as 98%-99% industrial crude antimony), the total amount of impurities is too high, and it is difficult to remove all impurities to the 5N grade requirement (total impurities <10 ppm) simultaneously by a single vacuum distillation step. This may require extending the processing time or reducing the yield, affecting the economic efficiency of the process. Therefore, limiting the purity of crude antimony raw materials to ≥99.99% can ensure processing efficiency and yield.
[0029] Preferably, the heating rate of the heating evaporation zone in step S103 is 5–10 °C / min, and the temperature is maintained at 300 °C and 500 °C for 20–40 minutes respectively. Because the crude antimony raw material contains adsorbed gases (air, water vapor) and volatile impurities such as sulfur and selenium, if the heating rate is too fast, these gases and volatile substances will be released rapidly, causing a sudden drop in the vacuum level inside the furnace, and even triggering a vacuum protection shutdown. Therefore, a heating rate of 5–10 °C / min allows for a smooth release of gases, timely exhaust of the vacuum system, and maintenance of a stable pressure within the operating range of 0.1 Pa to 1.0 Pa.
[0030] Furthermore, holding the temperature at 300℃ allows for the complete desorption and release of moisture adsorbed on the surface of the antimony raw material and dissolved hydrogen and nitrogen gases, preventing them from reacting with antimony at high temperatures to form oxides or hydrides that would affect product purity. It also removes trace organic contaminants and cleans the surface of the raw material. Holding the temperature at 500℃ pre-vaporizes low-melting-point impurities. 500℃ is close to or exceeds the volatilization temperature of volatile impurities such as sulfur and selenium, but is far below the main evaporation temperature of antimony (700-800℃). Holding at this temperature allows impurities such as sulfur and selenium to volatilize preferentially and be carried by the rising airflow to the upper low-temperature collection section for condensation. This "pre-vaporization" treatment significantly reduces the content of these impurities in the raw material, alleviates the separation load of the main distillation stage, and improves the purity of the final product.
[0031] Preferably, the temperature control accuracy of the three temperature zones in step S104 is ±10℃. If the temperature fluctuation of each zone exceeds ±10℃, the gradient may be disrupted, or even temperature reversal may occur (such as the lower temperature being lower than the middle temperature), causing the vapor to fail to condense in the expected order, resulting in a significant decrease in the separation effect.
[0032] Preferably, the reflux to the evaporation zone mentioned in step S106 is specifically achieved by setting an inverted conical reflux structure on the inner wall of the condenser tower in the middle intermediate temperature transition section. This structure allows some antimony vapor containing intermediate impurities to condense and adhere to the surface of the inverted conical reflux structure. The cone angle of the inverted conical reflux structure is 30° to 60°. The 30° to 60° cone angle allows the liquid or semi-solid metal adhering to the surface after condensation to flow naturally along the cone surface to the edge under gravity, then drip or flow down through the edge gaps, ultimately refluxing back to the evaporation zone. The 30° to 60° cone angle ensures that the condensate can flow down smoothly without stagnation. If the cone angle is too small (<30°), the cone surface is too gentle, and the condensate may not adhere due to surface tension, failing to reflux in time. If the cone angle is too large (>60°), the cone surface is too steep, and the condensate flow rate is too fast, potentially dripping directly and losing contact with the rising vapor. The cone angle range of 30° to 60° is an ideal range that, after optimization, can ensure smooth flow while maintaining an appropriate dwell time.
[0033] Preferably, the distillation time is 12–18 hours. This 2–18 hour duration ensures sufficient time for arsenic to diffuse and volatilize from the melt, undergoing multiple gas-liquid equilibration cycles before being carried to the upper low-temperature collection section, allowing the arsenic content in the product to be stably controlled at ≤1 ppm. Sufficient time also allows intermediate impurities such as sulfur and selenium to undergo multiple cycles of condensation, reflux, and re-evaporation in the reflux structure, effectively enriching them in the gas phase and separating them, allowing the sulfur and selenium content in the product to be controlled below 0.1–0.3 ppm. Furthermore, the long distillation time ensures that non-volatile impurities such as lead and bismuth are fully enriched in the residue of the evaporation zone, preventing their volatilization into the product.
[0034] Preferably, the purity of the above-mentioned high-purity antimony main product is ≥99.999%, wherein the arsenic content is ≤1ppm, the lead content is ≤0.5ppm, and the bismuth content is ≤0.5ppm.
[0035] In the second embodiment, please refer to Figure 1 and Figure 2 This embodiment provides an apparatus for implementing the above-described method for purifying metallic antimony, comprising: Vertical vacuum furnace body 1; A vacuum system connected to the furnace body 1 is used to achieve and maintain the required vacuum level inside the furnace; An evaporation zone is located at the bottom of the furnace body 1, and a crucible 3 for holding raw materials and a heating device are provided in the evaporation zone. A multi-stage condensing tower 4 is installed above the evaporation zone, and the condensing tower 4 is arranged vertically from bottom to top as follows: The lower high-temperature reflux section is equipped with a first temperature control unit and a first condenser plate 5. The middle temperature transition section contains a second temperature control unit and an inverted conical reflux structure. The upper low-temperature collection section is equipped with a third temperature control unit and a second condenser plate 7. The product collection unit, intermediate product collection unit, and impurity collection unit are respectively connected to the lower high-temperature reflux section, the middle medium-temperature transition section, and the upper low-temperature collection section; A multi-point thermocouple temperature monitoring system, and PID controllers connected to the first temperature control unit, the second temperature control unit, and the third temperature control unit respectively.
[0036] Within the condenser tower 4, a lower high-temperature reflux section, a middle medium-temperature transition section, and an upper low-temperature collection section are sequentially arranged from bottom to top. Utilizing the principle of natural hot air rising, a stable temperature gradient field is formed, enabling zoned condensation of substances with different volatility characteristics. Temperature control units corresponding to each section can flexibly adjust the temperature of each zone according to the impurity profile of the raw material, improving both separation effect and efficiency. For example, when processing high-arsenic raw materials, the temperature of the upper low-temperature section can be appropriately lowered to enhance arsenic collection capacity; when processing high-sulfur raw materials, the temperature of the middle transition section can be adjusted to optimize the reflux effect. The middle medium-temperature transition section features an inverted conical reflux structure with a cone angle of 30°–60°, allowing some antimony vapor containing intermediate impurities to flow naturally along the cone surface to the edge after condensation, and then reflux back to the evaporation zone through the edge gap. Guided by this structure, the condensate containing intermediate impurities refluxes back to the evaporation zone for re-evaporation, equivalent to achieving multiple gas-liquid equilibrations within a single unit. The theoretical plate number is far higher than in single-stage distillation, resulting in a significantly improved separation effect.
[0037] In some embodiments of the present invention, the aforementioned inverted conical reflux structure is a multi-layered inverted conical guide plate 6 disposed on the inner wall of the condenser tower 4, with airflow channels and reflux channels formed between adjacent guide plates. The multi-layered guide plates are arranged vertically, which is equivalent to setting up multiple gas-liquid contact stages. When the rising vapor passes through each layer of guide plates, it undergoes mass and heat transfer with the condensate attached to the plate surface, achieving a single gas-liquid equilibrium. The more layers there are, the higher the theoretical plate number, and the better the separation effect. Optionally, the inverted conical guide plate 6 in this embodiment can achieve 5 to 8 stages of stratification within a limited height. During the rising process of the vapor, each time it passes through a guide plate, some of the intermediate impurities are transferred to the liquid phase, and when the liquid phase refluxes back to the evaporation zone for re-evaporation, the impurities are further enriched. After multi-layered stepwise purification, the vapor finally reaching the lower high-temperature reflux section has extremely high purity, ensuring the quality of the main product.
[0038] In some embodiments of the present invention, the vacuum system includes a vacuum pump 2 connected to the furnace body. The vacuum pump 2 is used to perform vacuuming of the furnace body.
[0039] It should be noted that in this embodiment, both the first condensing plate 5 and the second condensing plate 7 are folded channel structures, which can increase the condensation area.
[0040] Specifically, in this embodiment, the first condensing plate 5 is an annular inclined plate structure. The condensed antimony crystals are directly attached to the first condensing plate 5. The product collection unit is set at the bottom of the first condensing plate 5, forming a discharge gap between the bottom of the first condensing plate 5 and the inner wall of the condensation tower 4. The product collection unit is specifically a collection pipe 8, which is connected to the discharge gap at the bottom of the first condensing plate 5.
[0041] The aforementioned intermediate product collection unit actually has collection grooves on the inverted conical guide plate 6. Some of the condensed intermediate products will directly adhere to these collection grooves. After the purification work is completed, the inverted conical guide plate 6 is disassembled and the intermediate products are scraped off directly.
[0042] The aforementioned impurity collection unit includes an impurity collection pipe 9, which is connected to the condensate collection side of the second condensing plate 7 for collecting condensate.
[0043] The following are preferred embodiments of the present invention. Unless otherwise specified, the raw materials and reagents involved are all commercially available standards, and the experimental or testing methods are all known methods commonly used by those skilled in the art: Example 1 A method for purifying metallic antimony includes the following steps: S101. Place the crude antimony raw material in the evaporation zone of a sealed vacuum furnace; S102. Evacuate the furnace body to bring the internal pressure to 0.1 Pa; S103. Heat the evaporation zone to 700℃ to melt and evaporate the crude antimony, producing a mixed vapor of antimony and impurity elements; S104. The mixed vapor moves upward and passes sequentially through a multi-stage condenser tower arranged vertically. The condenser tower is divided into three temperature zones from bottom to top vertically: The temperature in the lower high-temperature reflux section is controlled at 580℃; The temperature in the central, medium-temperature transition zone is controlled at 450℃. The upper low-temperature collection section is controlled at 120℃; S105, high-purity antimony vapor crystallizes and precipitates on the selective condenser plate in the lower high-temperature reflux section to form the main product; S106. Some of the antimony vapor containing intermediate impurities condenses in the middle medium-temperature transition section and flows back to the evaporation zone to participate in the evaporation to condensation process again. S107. Volatile impurity vapors are condensed and captured in the upper low-temperature collection section; S108. After distillation, high-purity antimony main product is obtained from the lower high-temperature reflux section, intermediate product containing intermediate impurities is obtained from the middle medium-temperature transition section, and impurity enrichment is obtained from the upper low-temperature collection section.
[0044] In some embodiments of the present invention, the crude antimony raw material mentioned in step S101 is industrial crude antimony with a purity of ≥99.99%, which is crushed to a particle size of 20mm before use.
[0045] In some embodiments of the present invention, the heating rate of the heating evaporation zone in step S103 is 5°C / min, and it is kept at 300°C and 500°C for 20 minutes each.
[0046] In some embodiments of the present invention, the temperature control accuracy of the three temperature zones described in step S104 above is ±10℃.
[0047] In some embodiments of the present invention, the reflux to the evaporation zone mentioned in step S106 is specifically an inverted conical reflux structure provided on the inner wall of the condenser tower in the middle medium-temperature transition section, which is used to allow some antimony vapor containing intermediate impurities to condense and adhere to the surface of the inverted conical reflux structure. The cone angle of the inverted conical reflux structure is 30°.
[0048] In some embodiments of the present invention, the distillation time is 12 hours.
[0049] In some embodiments of the present invention, the purity of the above-mentioned high-purity antimony main product is ≥99.999%, wherein the arsenic content is ≤1ppm, the lead content is ≤0.5ppm, and the bismuth content is ≤0.5ppm.
[0050] Example 2 A method for purifying metallic antimony includes the following steps: S101. Place the crude antimony raw material in the evaporation zone of a sealed vacuum furnace; S102. Evacuate the furnace body to bring the internal pressure to 0.5Pa; S103. Heat the evaporation zone to 750℃ to melt and evaporate the crude antimony, producing a mixed vapor of antimony and impurity elements; S104. The mixed vapor moves upward and passes sequentially through a multi-stage condenser tower arranged vertically. The condenser tower is divided into three temperature zones from bottom to top vertically: The temperature in the lower high-temperature reflux section is controlled at 600℃; In the central, medium-temperature transition zone, the temperature is controlled at 500℃; The upper low-temperature collection section is controlled at 260℃; S105, high-purity antimony vapor crystallizes and precipitates on the selective condenser plate in the lower high-temperature reflux section to form the main product; S106. Some of the antimony vapor containing intermediate impurities condenses in the middle medium-temperature transition section and flows back to the evaporation zone to participate in the evaporation to condensation process again. S107. Volatile impurity vapors are condensed and captured in the upper low-temperature collection section; S108. After distillation, high-purity antimony main product is obtained from the lower high-temperature reflux section, intermediate product containing intermediate impurities is obtained from the middle medium-temperature transition section, and impurity enrichment is obtained from the upper low-temperature collection section.
[0051] In some embodiments of the present invention, the crude antimony raw material mentioned in step S101 is industrial crude antimony with a purity of ≥99.99%, which is crushed to a particle size of 30mm before use.
[0052] In some embodiments of the present invention, the heating rate of the heating evaporation zone in step S103 is 7.5°C / min, and it is kept at 300°C and 500°C for 30 minutes each.
[0053] In some embodiments of the present invention, the temperature control accuracy of the three temperature zones described in step S104 above is ±10℃.
[0054] In some embodiments of the present invention, the reflux to the evaporation zone mentioned in step S106 is specifically achieved by setting an inverted conical reflux structure on the inner wall of the condenser tower in the middle medium-temperature transition section, so that some antimony vapor containing intermediate impurities condenses and adheres to the surface of the inverted conical reflux structure, wherein the cone angle of the inverted conical reflux structure is 45°.
[0055] In some embodiments of the present invention, the distillation time is 15 hours.
[0056] In some embodiments of the present invention, the purity of the above-mentioned high-purity antimony main product is ≥99.999%, wherein the arsenic content is ≤1ppm, the lead content is ≤0.5ppm, and the bismuth content is ≤0.5ppm.
[0057] Example 3 A method for purifying metallic antimony includes the following steps: S101. Place the crude antimony raw material in the evaporation zone of a sealed vacuum furnace; S102. Evacuate the furnace body to bring the internal pressure to 1.0 Pa; S103. Heat the evaporation zone to 800℃ to melt and evaporate the crude antimony, producing a mixed vapor of antimony and impurity elements; S104. The mixed vapor moves upward and passes sequentially through a multi-stage condenser tower arranged vertically. The condenser tower is divided into three temperature zones from bottom to top vertically: The temperature in the lower high-temperature reflux section is controlled at 620℃; In the central, medium-temperature transition zone, the temperature is controlled at 550℃; The upper low-temperature collection section is controlled at 400℃; S105, high-purity antimony vapor crystallizes and precipitates on the selective condenser plate in the lower high-temperature reflux section to form the main product; S106. Some of the antimony vapor containing intermediate impurities condenses in the middle medium-temperature transition section and flows back to the evaporation zone to participate in the evaporation to condensation process again. S107. Volatile impurity vapors are condensed and captured in the upper low-temperature collection section; S108. After distillation, high-purity antimony main product is obtained from the lower high-temperature reflux section, intermediate product containing intermediate impurities is obtained from the middle medium-temperature transition section, and impurity enrichment is obtained from the upper low-temperature collection section.
[0058] In some embodiments of the present invention, the crude antimony raw material mentioned in step S101 is industrial crude antimony with a purity of ≥99.99%, which is crushed to a particle size of 40mm before use.
[0059] In some embodiments of the present invention, the heating rate of the heating evaporation zone in step S103 is 10°C / min, and it is kept at 300°C and 500°C for 40 minutes each.
[0060] In some embodiments of the present invention, the temperature control accuracy of the three temperature zones described in step S104 above is ±10℃.
[0061] In some embodiments of the present invention, the reflux to the evaporation zone mentioned in step S106 is specifically an inverted conical reflux structure provided on the inner wall of the condenser tower in the middle medium-temperature transition section, which is used to allow some antimony vapor containing intermediate impurities to condense and adhere to the surface of the inverted conical reflux structure. The cone angle of the inverted conical reflux structure is 60°.
[0062] In some embodiments of the present invention, the distillation time is 18 hours.
[0063] In some embodiments of the present invention, the purity of the above-mentioned high-purity antimony main product is ≥99.999%, wherein the arsenic content is ≤1ppm, the lead content is ≤0.5ppm, and the bismuth content is ≤0.5ppm.
[0064] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for purifying metallic antimony, characterized in that, Includes the following steps: S101. Place the crude antimony raw material in the evaporation zone of a sealed vacuum furnace; S102. Evacuate the furnace body to bring the internal pressure to 0.1Pa~1.0Pa; S103. Heat the evaporation zone to 700℃~800℃ to melt and evaporate the crude antimony, producing a mixed vapor of antimony and impurity elements; S104. The mixed vapor moves upward and passes sequentially through a multi-stage condenser tower arranged vertically. The condenser tower is divided into three temperature zones from bottom to top vertically: The temperature in the lower high-temperature reflux section is controlled between 580℃ and 620℃. In the middle-temperature transition zone, the temperature is controlled between 450℃ and 550℃. The upper low-temperature collection section has a temperature controlled between 120℃ and 400℃. S105, high-purity antimony vapor crystallizes and precipitates on the selective condenser plate in the lower high-temperature reflux section to form the main product; S106. Some of the antimony vapor containing intermediate impurities condenses in the middle medium-temperature transition section and flows back to the evaporation zone to participate in the evaporation to condensation process again. S107. Volatile impurity vapors are condensed and captured in the upper low-temperature collection section; S108. After distillation, high-purity antimony main product is obtained from the lower high-temperature reflux section, intermediate product containing intermediate impurities is obtained from the middle medium-temperature transition section, and impurity enrichment is obtained from the upper low-temperature collection section.
2. The method for purifying metallic antimony according to claim 1, characterized in that, The crude antimony raw material mentioned in step S101 is industrial crude antimony with a purity of ≥99.99%, which is crushed to a particle size of 20-40mm before use.
3. The method for purifying metallic antimony according to claim 1, characterized in that, The heating rate of the heating evaporation zone in step S103 is 5-10℃ / min, and it is kept at 300℃ and 500℃ for 20-40 minutes respectively.
4. The method for purifying metallic antimony according to claim 1, characterized in that, The temperature control accuracy of the three temperature zones mentioned in step S104 is ±10℃.
5. The method for purifying metallic antimony according to claim 1, characterized in that, The reflux to the evaporation zone mentioned in step S106 specifically involves setting an inverted conical reflux structure on the inner wall of the condenser tower in the middle medium-temperature transition section. This structure is used to allow some antimony vapor containing intermediate impurities to condense and adhere to the surface of the inverted conical reflux structure. The cone angle of the inverted conical reflux structure is 30° to 60°.
6. The method for purifying metallic antimony according to claim 1, characterized in that, The distillation time is 12 to 18 hours.
7. The method for purifying metallic antimony according to claim 1, characterized in that, The purity of the high-purity antimony main product is ≥99.999%, with arsenic content ≤1ppm, lead content ≤0.5ppm, and bismuth content ≤0.5ppm.
8. An apparatus for implementing the method for purifying metallic antimony according to any one of claims 1-7, characterized in that, include: Vertical vacuum furnace body; A vacuum system connected to the furnace body is used to achieve and maintain the required vacuum level inside the furnace; An evaporation zone is located at the bottom of the furnace body, and the evaporation zone is equipped with a crucible for holding raw materials and a heating device. A multi-stage condensing tower is installed above the evaporation zone, and the condensing tower is arranged vertically from bottom to top as follows: The lower high-temperature reflux section is equipped with a first temperature control unit and a first condenser plate. The middle temperature transition section contains a second temperature control unit and an inverted conical reflux structure. The upper low-temperature collection section is equipped with a third temperature control unit and a second condenser plate. The product collection unit, intermediate product collection unit, and impurity collection unit are respectively connected to the lower high-temperature reflux section, the middle medium-temperature transition section, and the upper low-temperature collection section; A multi-point thermocouple temperature monitoring system, and PID controllers connected to the first temperature control unit, the second temperature control unit, and the third temperature control unit respectively.
9. The device according to claim 8, characterized in that, The inverted conical reflux structure consists of multiple layers of inverted conical guide plates installed on the inner wall of the condenser tower, with airflow channels and reflux channels formed between adjacent guide plates.
10. The device according to claim 8, characterized in that, The vacuum system includes a vacuum pump that is connected to the furnace body.