Method for removing nonmetallic impurities carbon oxygen in high-purity selenium

Abstract

This invention relates to a method for removing non-metallic impurities of carbon and oxygen from high-purity selenium, belonging to the field of high-purity selenium purification technology. The invention provides a method for removing non-metallic impurities of carbon and oxygen using high-purity selenium. The method involves vacuum distilling 99.999% high-purity selenium with a metal (or metal mixture) reducing agent under argon atmosphere while maintaining the temperature at 400℃ for 120 minutes. The carbon content in the resulting selenium volatiles is reduced from 0.0024% to <0.0001%, and the oxygen content is reduced from 0.011% to 0.0066%. The method described in this invention is simple, safe, controllable, and easy to operate.

Description

Technical Field

[0001] This invention relates to a method for removing non-metallic impurities such as carbon and oxygen from high-purity selenium, belonging to the field of rare and dispersed metal purification and deimpurification technology. Background Technology

[0002] Selenium is an important semiconductor material with wide applications in electronics, photovoltaics, chemicals, and medicine. With continuous technological advancements, the demand for high-purity selenium is increasing, especially in high-end fields such as semiconductor chip manufacturing and high-performance photovoltaic cells, where the purity requirements for high-purity selenium are becoming increasingly stringent. However, research on the removal of non-metallic impurities from high-purity selenium is scarce. Non-metallic impurities are the core source of harm to high-purity selenium; some, such as oxygen, sulfur, carbon, and nitrogen, can comprehensively degrade material properties in terms of electrical, optical, structural, chemical, and processing aspects, directly affecting its suitability for high-end applications such as semiconductors and infrared devices. Therefore, removing non-metallic impurities from high-purity selenium has become an urgent issue. Summary of the Invention

[0003] The purpose of this invention is to provide a method for removing non-metallic impurities such as carbon and oxygen from high-purity selenium. This method is simple, safe and controllable, and easy to operate. The final selenium product has an oxygen content of 0.0066% and a carbon content of <0.0001%.

[0004] The technical solution of the present invention is as follows: A method for removing non-metallic impurities such as carbon and oxygen from high-purity selenium, specifically including the following steps: (1) Place 5N high-purity selenium and 0.5% by mass of metal reducing agent (aluminum, magnesium, calcium and their mixtures) into a vacuum distillation furnace, evacuate to 10 Pa or below and introduce argon gas.

[0005] (2) Distillation was carried out at 400℃ for 120 min to finally obtain high-purity selenium with an oxygen content of 0.0066% and a carbon content of <0.0001%.

[0006] Preferably, the selenium of the present invention has a purity of 99.999%, and it can be used directly when the purity of the selenium is within the above range; when the purity of the selenium does not meet the above range, the selenium is purified.

[0007] Preferably, aluminum is added at 0.5% by mass in block form, wherein the purity of aluminum is 99.99%.

[0008] Preferably, in the vacuum distillation stage of this invention, the heating rate is 10℃ / min, the reaction time is 120min, the temperature is 400℃, and the vacuum degree is below 10Pa.

[0009] The high-purity selenium of this invention contains 0.0024% carbon and 0.011% oxygen by mass. The carbon and oxygen in the selenium may be present in the form of elemental selenium dioxide or carbon selenide, which are interspersed in the gaps between the particles. The mass fraction of selenium is 99.999%. In this invention, the product of vacuum distillation is selenium. After vacuum distillation, selenium yields residue and volatiles. The residue is a concentration of impurities, and the volatiles are obtained by condensing selenium as it escapes upwards onto the condenser plate in the vacuum furnace.

[0010] The principle of this invention: Since carbon and oxygen in selenium mainly exist in the form of elemental selenium or selenium dioxide and carbon selenide, and the saturated vapor pressure of selenium is greater than that of aluminum, vacuum distillation can be used to combine the carbon and oxygen in selenium with a metal reducing agent to achieve the purpose of removing carbon and oxygen. The beneficial effects of this invention are as follows: 4N aluminum scraps and 5N selenium are added to a crucible, evacuated to below 10 Pa, and argon is introduced as a protective gas for vacuum distillation. The mixture is then kept at 400°C for 120 minutes to obtain residues and volatiles. The volatiles are collected, and the final selenium product has a carbon content of less than 0.0001% and an oxygen content of 0.0066%. The direct selenium recovery rate is greater than 95%, the carbon removal rate is greater than 95.8%, and the oxygen removal rate is 0.4%. The method described in this invention is simple, safe, controllable, and easy to operate. Detailed Implementation

[0011] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Implementation

[0012] This invention provides a method for removing non-metallic impurities such as carbon and oxygen from high-purity selenium. The technical solution of this invention will be clearly and completely described below with reference to embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them; all other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Example 1

[0013] A method for removing non-metallic impurities such as carbon and oxygen from high-purity selenium specifically includes the following steps: 20.01g of selenium and 0.99g of aluminum were added to a crucible, and argon was added as a protective gas under vacuum. The temperature was maintained at 250℃ for 120 minutes. The volatiles were collected and tested, and the results showed that the carbon content in the volatiles was 0.014% and the oxygen content was 0.012%. Example 2

[0014] A method for removing non-metallic impurities such as carbon and oxygen from high-purity selenium specifically includes the following steps: 19.98g of selenium and 1.02g of aluminum were added to the crucible, and argon was added as a protective gas under vacuum. The temperature was maintained at 300℃ for 120 minutes. The volatiles were collected and tested. The results showed that the carbon content in the volatiles was 0.023% and the oxygen content was 0.036%. Example 3

[0015] A method for removing non-metallic impurities such as carbon and oxygen from high-purity selenium specifically includes the following steps: 20.04g of selenium and 1.00g of aluminum were added to a crucible, and argon was added as a protective gas under vacuum. The temperature was maintained at 350℃ for 120 minutes. The volatiles were collected and tested. The results showed that the carbon content in the volatiles was 0.0078% and the oxygen content was 0.014%. Example 4

[0016] A method for removing non-metallic impurities such as carbon and oxygen from high-purity selenium specifically includes the following steps: 20.06g of selenium and 1.00g of aluminum were added to a crucible, and argon was added as a protective gas under vacuum. The temperature was maintained at 450℃ for 120 minutes. The volatiles were collected and tested. The results showed that the carbon content in the volatiles was 0.067% and the oxygen content was 0.0066%.

[0017] Comparative Example 1 A method for removing non-metallic impurities such as carbon and oxygen from selenium-sulfur slag specifically includes the following steps: 20.05g of selenium and 1.03g of aluminum were added to a crucible, and argon was added as a protective gas under vacuum. The temperature was maintained at 400℃ for 120 minutes. The volatiles were collected and tested, and the results showed that the carbon content in the volatiles was 0.006% and the oxygen content was 0.012%.

[0018] The comparison shows that this method is relatively efficient in removing carbon and oxygen, and yields high-quality products. The final selenium product contains 0.006% carbon and 0.012% oxygen. The process is simple, safe, controllable, and easy to operate, making it highly likely to be applied industrially.

[0019] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for removing non-metallic impurities such as carbon and oxygen from high-purity selenium, characterized in that, Specifically, the following steps are included: (1) Place 5N high-purity selenium and 0.5% by mass of metal reducing agent into a vacuum distillation furnace, evacuate to 10 Pa or below and introduce argon gas; (2) Distillation was carried out at 400℃ for 120 min to finally obtain high-purity selenium with an oxygen content of 0.0066% and a carbon content of <0.0001%.

2. The method for removing non-metallic impurities such as carbon and oxygen from high-purity selenium according to claim 1, characterized in that: The metal reducing agent is aluminum, magnesium, calcium, or a mixture thereof, and the amount added is less than 0.4%.

3. The method for removing non-metallic impurities such as carbon and oxygen from high-purity selenium according to claim 1, characterized in that: The metal reducing agent has a purity of 4N and is in the form of fragments.

4. The method for removing non-metallic impurities such as carbon and oxygen from high-purity selenium according to claim 1, characterized in that: The conditions for vacuum distillation in step (2) are: heating rate of 5~10℃ / min, temperature of 400℃, time of 120min, and pressure of 1~10Pa.