Method for deeply removing arsenic from high-purity antimony

Abstract

The invention relates to a method for deeply removing arsenic from high-purity antimony, and belongs to the technical field of metallurgical engineering. According to the method, tin serves as a trapping agent under the vacuum condition, tin and arsenic preferentially form a stable tin arsenide compound, and high-selectivity separation of antimony and arsenic is achieved; the method specifically comprises the following steps: (1) preparing and mixing raw materials; (2) vacuum distillation reaction: placing the high-temperature-resistant container in a vacuum furnace, and starting a vacuum system to reduce the pressure in the furnace to 10 Pa or below; heating the furnace to a reaction temperature of 580-630 DEG C at a heating rate of 8-15 DEG C / min, and keeping the temperature for 30-120 minutes at the temperature; and (3) separating the product to obtain an antimony product subjected to deep arsenic removal. According to the method, traditional physical separation (vacuum distillation) and chemical reaction (alloying) are successfully combined, and the dynamic bottleneck existing in a single physical method is overcome. By forming volatile tin arsenide, the migration path and the existence form of arsenic are ingeniously changed, so that high-selectivity and high-efficiency removal of low-content arsenic is realized.

Description

Technical Field

[0001] This application relates to the field of metallurgical engineering technology, and in particular to a method for deep removal of arsenic from high-purity antimony. Background Technology

[0002] In the regeneration and smelting process of high-purity antimony (purity >99.99%), the removal of arsenic has always been a key technical bottleneck restricting the improvement of the purity of the final product. This is mainly due to the high similarity between arsenic and antimony in their physicochemical properties. As adjacent elements belonging to Group VA in the periodic table, arsenic and antimony not only have very similar atomic radii, but their outer electron configurations are also basically the same, resulting in significant commonalities in their chemical reaction behavior, bonding characteristics, and distribution tendencies in different phases.

[0003] This structural similarity directly translates into significant challenges in metallurgical separation: First, during zone smelting, the segregation coefficients of arsenic and antimony almost overlap, making effective separation difficult using the segregation effect during solidification. Second, in vacuum distillation, the vapor pressure curves of arsenic and antimony are highly similar at conventional distillation temperatures, exhibiting similar volatilization trends, resulting in low separation coefficients and hindering efficient removal of arsenic through conventional vacuum distillation. While existing oxidation methods for arsenic removal have some effectiveness, they easily introduce new impurities such as oxygen and may cause antimony loss.

[0004] Therefore, developing a novel separation method that is specifically designed for the antimony-arsenic system, does not introduce new impurities, and has high selectivity has become a core challenge to further advance high-purity antimony preparation technology. Summary of the Invention

[0005] To address or partially address the problems existing in related technologies, this application provides a method for deep removal of arsenic from high-purity antimony, successfully combining traditional physical separation (vacuum distillation) with chemical reaction (alloying), overcoming the kinetic bottleneck of single physical methods. By forming volatile tin arsenide, the migration path and existence form of arsenic are cleverly altered, thereby achieving highly selective and efficient removal of low-content arsenic.

[0006] This application discloses a method for deep removal of arsenic from high-purity antimony. Under vacuum conditions, using tin as a collector, the method achieves highly selective separation of antimony and arsenic by preferentially forming stable tin arsenide compounds with tin. The method specifically includes the following steps: (1) Raw material preparation and mixing: After uniformly mixing the high-purity antimony powder containing arsenic and the metallic tin powder, place them in a high-temperature resistant container; wherein, the Sb content in the high-purity antimony powder is >99.99%, the Sn content in the metallic tin powder is >99.999%, and the mass ratio of the high-purity antimony powder to the metallic tin powder is 9:1~19:1; (2) Vacuum distillation reaction: Place the high-temperature resistant container in a vacuum furnace, start the vacuum system, and reduce the pressure inside the furnace to below 10 Pa; then raise the furnace temperature to the reaction temperature of 580~630℃ at a heating rate of 8-15℃ / min, and keep it at this temperature for 30~120 min. (3) Product separation: After the reaction is completed, the furnace is cooled to room temperature and the volatiles and residues are removed. The volatiles are arsenic-tin alloys enriched with arsenic. The residues are antimony with arsenic removed after deep arsenic removal. The volatiles and residues are separated by physical separation methods to obtain antimony products with deep arsenic removal.

[0007] Furthermore, in step (1), the mass ratio of the added high-purity antimony powder to the mass of the metallic tin powder is 12:1.

[0008] Furthermore, in step (1), the high-temperature resistant container is a high-purity graphite crucible.

[0009] Furthermore, in step (2), the vacuum furnace is a vertical vacuum resistance furnace.

[0010] Furthermore, the particle size of the high-purity antimony powder and metallic tin powder is 200-300 mesh.

[0011] The mechanism of this application is as follows: Without tin, arsenic removal relies solely on the selective volatilization inherent in vacuum distillation. This is based on the difference in vapor pressure between arsenic and antimony at the same temperature. At experimental temperatures (580-630°C), arsenic, due to its lower sublimation point, has a much higher vapor pressure than antimony, meaning it is more readily volatilized.

[0012] However, this process is constrained by kinetic limitations and solid solution limitations: specifically, arsenic in high-purity antimony is not mechanically mixed in elemental form, but rather dissolved in the antimony lattice. For arsenic to be removed, it must first diffuse from the interior of the lattice to the surface before it can volatilize. Without a trapping agent, this process is very slow and incomplete. Only a small amount of arsenic at or near the surface successfully escapes, while most remains firmly "locked" in the antimony melt. Therefore, relying solely on vacuum distillation presents a kinetic bottleneck for arsenic removal efficiency, resulting in an extremely low removal rate (approximately 5%).

[0013] The removal rate of arsenic significantly improved after the addition of tin, mainly because: 1. Chemical trapping mechanism: Tin is liquid at the experimental temperature (tin's melting point is 232°C). Due to its strong chemical affinity for arsenic, tin preferentially reacts with arsenic to form stable intermetallic compounds, such as Sn3As2 and SnAs. This reaction is thermodynamically very favorable.

[0014] 2. Altering the activity and form of arsenic: In antimony, arsenic has a high "activity" (which can be understood as effective concentration or escape tendency), but it is bound by the crystal lattice. When arsenic reacts with tin to form tin arsenide, the activity of arsenic decreases sharply. According to the principle of chemical equilibrium (Le Chatelier's principle), to compensate for this decrease in activity, more arsenic will continuously diffuse from the interior of the antimony lattice to the antimony-tin interface to replenish the reacted arsenic. This greatly accelerates the migration and removal process of arsenic.

[0015] 3. The nature of the volatiles: The volatiles are "arsenic-enriched tin-arsenic alloys." Although pure tin has an extremely high boiling point, the volatility of the resulting tin-arsenic alloy is much higher than that of pure tin, and may even be higher than that of the arsenic bound in antimony. Therefore, tin not only acts as a "collector" to extract arsenic from antimony, but also as a "carrier," forming volatile compounds with arsenic and co-evaporating the arsenic as tin-arsenic onto the condenser plate, thus achieving efficient separation from the main antimony component.

[0016] The beneficial effects of this application are: 1. This application utilizes the stronger chemical affinity between tin and arsenic to successfully combine traditional physical separation (vacuum distillation) with chemical reaction (alloying), overcoming the kinetic bottleneck of single physical methods. By forming volatile tin arsenide, the migration path and existence form of arsenic are cleverly altered, thereby achieving highly selective and efficient removal of low-content arsenic.

[0017] 2. The entire deep arsenic removal process in this application is completed in a single vacuum furnace, without the need for complex multi-stage processes and complex equipment. Moreover, the entire process only requires the addition of tin agent, without introducing secondary pollution or adding expensive reagents. Metallic tin is low in cost and readily available, thus providing a reliable technical path for industrial applications.

[0018] 3. In the vacuum distillation reaction, the furnace temperature is raised to a reaction temperature of 580~630℃ at a heating rate of 8-15℃ / min. By controlling the heating rate, the sublimation of antimony can be effectively controlled. The gentle heating allows sufficient time for heat to be evenly transferred to the entire material, so that it can reach the boiling point steadily, thereby ensuring that arsenic is fully removed. Attached Figure Description

[0019] The above and other objects, features and advantages of this application will become more apparent from the more detailed description of exemplary embodiments thereof in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments thereof.

[0020] Figure 1 This is a schematic diagram of the process flow in this application. Detailed Implementation

[0021] The embodiments of this application will now be described in more detail with reference to the examples. While embodiments of this application are shown in the examples, it should be understood that this application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art. Example 1

[0022] like Figure 1 As shown, 9g of 4N high-purity antimony (with arsenic and tin contents of 13.02ppm and 1.91ppm respectively) and 1g of tin were mixed and ground to a fineness of 200-300 mesh, then placed in a graphite crucible. The graphite crucible, condenser, and condenser lid were then placed in a vertical vacuum furnace. The furnace lid was closed, and the vacuum pump was started to remove air from the furnace, ensuring the experiment was conducted under vacuum. When the Maxwell vacuum gauge reading was less than 10Pa, the main furnace temperature control system was activated, and the heating rate was set at 8℃ / min. The reaction was carried out at 580℃ under vacuum for 30 minutes. After the reaction, the furnace was cooled to room temperature.

[0023] Analysis revealed that the arsenic content in the volatile antimony product obtained after the reaction was 2.91 ppm, and the Sb content in the volatiles was >99.99%. Based on these results, the arsenic removal rate was 77.65%. Example 2

[0024] 9g of 4N high-purity antimony (with arsenic and tin contents of 13.02ppm and 1.91ppm respectively) and 0.474g of tin were mixed and ground to a fineness of 200-300 mesh, then placed in a graphite crucible. The graphite crucible, condenser, and condenser lid were then placed in a vertical vacuum furnace. The furnace lid was closed, and the vacuum pump was started to remove air from the furnace, ensuring the experiment was conducted under vacuum. When the Maxwell vacuum gauge reading was less than 10 Pa, the main furnace temperature control system was activated, and the heating rate was set at 15℃ / min. The reaction was carried out at 600℃ under vacuum for 60 min. After the reaction, the furnace was cooled to room temperature.

[0025] Analysis revealed that the arsenic content in the volatile antimony product obtained after the reaction was 2.94 ppm, and the Sb content in the volatiles was >99.99%. Based on these results, the arsenic removal rate was 77.42%. Example 3

[0026] 9g of 4N high-purity antimony (with arsenic and tin contents of 20.15ppm and 0.85ppm respectively) and 0.750g of tin were mixed and ground to a fineness of 200-300 mesh, then placed in a graphite crucible. The graphite crucible, condenser, and condenser lid were then placed in a vertical vacuum furnace. The furnace lid was closed, and the vacuum pump was started to remove air from the furnace, ensuring the experiment was conducted under vacuum. When the Maxwell vacuum gauge reading was less than 10 Pa, the main furnace temperature control system was activated, and the heating rate was set at 10℃ / min. The reaction was carried out at 630℃ under vacuum for 90 minutes. After the reaction, the furnace was cooled to room temperature.

[0027] Analysis revealed that the arsenic content in the volatile antimony product obtained after the reaction was 3.44 ppm, and the Sb content in the volatiles was >99.99%. Based on these results, the arsenic removal rate was 82.93%. Example 4

[0028] 9g of 4N high-purity antimony (with arsenic and tin contents of 15.67ppm and 1.23ppm respectively) and 0.600g of tin were mixed and ground to a fineness of 200-300 mesh, then placed in a graphite crucible. The graphite crucible, condenser, and condenser lid were then placed in a vertical vacuum furnace. The furnace lid was closed, and the vacuum pump was started to remove air from the furnace, ensuring the experiment was conducted under vacuum. When the Maxwell vacuum gauge reading was less than 10 Pa, the main furnace temperature control system was activated, and the heating rate was set at 10℃ / min. The reaction was carried out at 630℃ under vacuum for 90 minutes. After the reaction, the furnace was cooled to room temperature.

[0029] Analysis revealed that the arsenic content in the volatile antimony product obtained after the reaction was 2.85 ppm, and the arsenic content in the residual tin was 10.48 ppm. Based on these results, the arsenic removal rate was 81.81%.

[0030] Comparative Example 1 Except for not adding tin, the operation is the same as in Example 1.

[0031] Analysis revealed that the arsenic content in the volatile antimony product obtained after the reaction was 12.49 ppm. Based on these results, the arsenic removal rate was 4.07%.

[0032] Comparative Example 2 Except for not adding tin, the operation is the same as in Example 2.

[0033] Analysis revealed that the arsenic content in the volatile antimony product obtained after the reaction was 12.45 ppm. Based on these results, the arsenic removal rate was 4.38%.

[0034] Comparative Example 3 Except for the absence of tin, the operation is the same as in Example 3.

[0035] Analysis revealed that the arsenic content in the volatile antimony product obtained after the reaction was 19.22 ppm. Based on these results, the arsenic removal rate was 4.57%.

[0036] Comparative Example 4 Except for not adding tin, the operation is the same as in Example 4.

[0037] Analysis revealed that the arsenic content in the volatile antimony product obtained after the reaction was 14.97 ppm. Based on these results, the arsenic removal rate was 4.46%.

[0038] In summary, this application provides an innovative method for the deep removal of arsenic from high-purity antimony. By introducing tin as a trapping agent and utilizing its property of forming volatile compounds with arsenic, highly efficient separation of arsenic from antimony is achieved. In all comparative examples, without the addition of tin, the arsenic removal rate remained consistently low at approximately 4.5%. This demonstrates that relying solely on the physical volatilization effect of vacuum distillation has very limited efficiency in removing arsenic and cannot achieve deep removal. However, in all embodiments, the arsenic removal rate steadily increased to over 77% after the addition of tin. This directly and powerfully proves that tin, as a trapping agent, is the key and necessary means for achieving deep removal in this technical solution.

[0039] This method successfully combines traditional physical separation (vacuum distillation) with chemical reaction (alloying), overcoming the kinetic bottleneck of single physical methods. By forming volatile tin arsenide, the migration path and form of arsenic are cleverly altered, thereby achieving highly selective and efficient removal of low-content arsenic.

[0040] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A process for the deep removal of arsenic from high purity antimony, characterized in that, Under vacuum condition, tin is used as trapping agent, tin and arsenic preferentially form stable tin arsenide compound, realizing high selective separation of antimony and arsenic; Specifically comprising the following steps: (1) raw material preparation and mixing: the high purity antimony powder containing arsenic and tin powder are uniformly mixed, and then placed in a high temperature resistant container; wherein, the Sb content in the high purity antimony powder is > 99.99%, the Sn content in the tin powder is > 99.999%, and the mass ratio of the high purity antimony powder to the tin powder is 9:1~19:1; (2) vacuum distillation reaction: the high temperature resistant container is placed in a vacuum furnace, the vacuum system is started, and the pressure in the furnace is reduced to below 10 Pa; then the temperature of the furnace is raised to a reaction temperature of 580~630℃ at a heating rate of 8-15℃ / min, and kept at this temperature for 30~120 min; (3) product separation: after the reaction is completed, the furnace is cooled to room temperature, and the volatile matter and the residue are taken out; the volatile matter is arsenic tin alloy enriched with arsenic; the residue is antimony after deep arsenic removal; the volatile matter and the residue are separated by physical separation method, and the antimony product after deep arsenic removal is obtained.

2. The method for deeply removing arsenic from high-purity antimony according to claim 1, characterized in that: In step (1), the mass ratio of the addition amount of the high purity antimony powder to the tin powder is 12:

1.

3. The method for deeply removing arsenic from high-purity antimony according to claim 1, characterized in that: In step (1), the high temperature resistant container is a high purity graphite crucible.

4. The method for deeply removing arsenic from high-purity antimony according to claim 1, characterized in that: In step (2), the vacuum furnace is a vertical vacuum resistance furnace.

5. The method for deeply removing arsenic from high-purity antimony according to claim 1, characterized in that: The particle size of the high purity antimony powder and the tin powder is 200~300 mesh.

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