Preparation method of 5N high-purity antimony

Abstract

A preparation method of 5N high-purity antimony comprises the following steps: (1) hydrolysis: taking ethylene glycol antimony as a raw material, and carrying out pyrohydrolysis pretreatment to obtain antimony trioxide; (2) biological reduction: uniformly mixing antimony trioxide with an organic catalytic reduction covering agent, and carrying out reduction smelting to prepare 4N antimony; and (3) vacuum distillation: the 4N antimony is subjected to two-stage vacuum distillation, namely first-stage high-temperature vacuum distillation and second-stage low-temperature vacuum distillation, and the 5N high-purity antimony is obtained. According to the method, an ethylene glycol antimony product is adopted as a raw material and subjected to hydrolysis-biological reduction and multi-field synergistic enhanced vacuum distillation to obtain 5N high-purity antimony, the total amount of impurity elements of the product is controlled to be 10 ppm or below, the content of key impurity elements As is controlled to be 1 ppm or below, the content of Pb is controlled to be 0.2 ppm or below, the content of Bi is controlled to be 0.2 ppm or below, the content of Cu is controlled to be 0.05 ppm or below, and the content of Fe is controlled to be 0.5 ppm or below.

Description

Technical Field

[0001] The present invention relates to a method for preparing high-purity antimony, in particular to a method for preparing 5N high-purity antimony. Background Art

[0002] High-purity antimony refers to antimony metal with a purity exceeding 99.99%. Its excellent physical and chemical properties make it widely used in semiconductors, electronics, photovoltaics, and other fields, primarily in the semiconductor industry. In recent years, my country's electronic information industry has experienced rapid growth. High-purity antimony (5N and 6N) is a promising semiconductor material, primarily used as a dopant for silicon single crystals, antimony compound semiconductor materials, and high-purity antimony alloys. It can also be used as a dopant for other semiconductor materials. Annual demand in my country currently exceeds 20 tons and continues to grow year by year. It plays a particularly important role in national defense, the electronics industry, and advanced science and technology.

[0003] The United States and Japan were among the first countries to produce high-purity antimony abroad. Their rapid technological development and the high concentration of high-purity antimony used in semiconductors spurred their early research and development of high-purity antimony products. The high-purity antimony industry (4N, 5N, 6N, and 7N) has established a significant production scale abroad, with numerous well-known manufacturers and research institutions. Production capacity is primarily distributed in Asia, Europe, and the Americas. Key institutions engaged in high-purity antimony production and research include DOWA Corporation of Japan, Seiko Co., Ltd., and Langelsheim, Germany. Japan has established large-scale high-purity antimony production lines, using crude or refined antimony as raw materials. These products, including 4N, 5N, and 6N antimony, are produced for domestic use and exported to other countries, generating significant profits. According to estimates by the Sichuan Nonferrous Metals Import and Export Company, Japan's current high-purity antimony consumption exceeds 60 tons / year, Germany's exceeds 50 tons / year, and the United States's exceeds 36 tons / year. The demand for 4N antimony is the largest, at 300-330 tons, 5N antimony is about 100 tons, and 6N and 7N antimony are about 25-30 tons. However, with the rapid development of new technologies, the demand for high-purity antimony materials is also increasing.

[0004] China's research and production of high-purity antimony began later than overseas. Sichuan Emei Semiconductor Factory has completed the production of high-purity antimony, as well as the development of ultra-pure antimony and high-purity antimony balls, and is now capable of producing small quantities of 5N and 6N high-purity antimony products. Yunnan Tonghai Dafang Technology Co., Ltd., in collaboration with Kunming University of Science and Technology, also completed the development of 5N and 6N high-purity antimony in 2005. Several companies specialize in high-purity antimony, including Wuhan Tuocai Technology Co., Ltd. and Chengdu Zhongjiancai Optoelectronic Materials Co., Ltd. Currently, my country's demand for high-purity antimony has reached over 20 tons per year. With technological advancements and the rapid development of high-tech, especially in recent years with the application of InSb in far-infrared detection and GaSb in fourth-generation semiconductor materials, my country's demand for high-purity antimony is increasing, and its usage is expected to continue to grow. As a major producer and consumer of high-purity antimony, China boasts advantages such as abundant resources and a well-developed industrial chain. However, it still struggles in technological innovation and brand building, and the high-purity antimony required for production in my country's optoelectronics and information technology industries continues to be imported. Therefore, further optimization of purification processes is necessary to improve product purity and yield, while reducing production costs to secure a competitive advantage in the global market. Research is also underway to apply high-purity antimony to new energy applications such as solar cells and fuel cells to enhance energy conversion efficiency. Research is also underway to apply high-purity antimony to high-end manufacturing fields such as aerospace and precision instruments to improve product performance and quality. Furthermore, we are strengthening exchanges and collaboration with leading international companies, actively participating in the development of international standards and trade rules, and enhancing our international voice. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for preparing 5N high-purity antimony.

[0006] The technical solution adopted by the present invention to solve the technical problem is:

[0007] A method for preparing 5N high-purity antimony comprises the following steps:

[0008] (1) Hydrolysis: Using ethylene glycol antimony as raw material, thermal hydrolysis pretreatment is performed to obtain antimony trioxide;

[0009] Studies have shown that hydrolysis can remove water-soluble impurities such as sodium sulfate and sodium arsenate from most raw materials, producing purified hydrolyzed antimony trioxide.

[0010] (2) Bioreduction: The antimony trioxide obtained in step (1) is mixed with an organic catalytic reduction covering agent, and reduced and smelted at a certain temperature, and then kept warm and clarified for a certain period of time to obtain 4N antimony;

[0011] (3) Vacuum distillation: The 4N antimony obtained in step (2) is subjected to two stages of vacuum distillation: a first stage of high-temperature vacuum distillation, with a controlled vacuum degree of 10-20 Pa, a vacuum melting temperature of 650-700°C, and an evaporation rate of 15-20 g / min (to perform preliminary separation of antimony from impurity elements, mainly removing low-boiling impurities in the form of low-boiling antimony); a second stage of low-temperature vacuum distillation, using the crystalline antimony obtained in the first stage of high-temperature vacuum distillation as raw material, and performing low-temperature vacuum distillation, with a controlled vacuum degree of 5-10 Pa, a vacuum melting temperature of 580-600°C, and an evaporation rate of 5-10 g / min, to achieve secondary separation of impurity elements (mainly removing high-boiling impurities in the form of bottom antimony); and 5N high-purity antimony is obtained. The total amount of impurity elements in the product is controlled to be below 10 ppm.

[0012] Furthermore, in step (1), the specific conditions for hydrolysis are as follows: liquid-to-solid mass ratio of 15-25:1 (preferably 20:1). Hydrolysis temperature of 55-65°C. Stirring time of 1-2 hours. After stirring, the mixture is allowed to stand for more than 0.3 hours (preferably 0.5-1 hour) to clarify. After the hydrolysis precipitate is clarified, it is filtered and the filter residue is dried at 100-150°C (preferably microwave drying) to obtain the product antimony trioxide. The product is a white loose powder.

[0013] Research has shown that a liquid-to-solid ratio of 15-25:1 ensures adequate dispersion of the raw materials, avoiding localized concentrations that can lead to uneven hydrolysis. Temperatures should be controlled between 55-65°C. Temperatures below 55°C slow the reaction rate, while temperatures above 65°C increase energy consumption and may trigger side reactions (such as ethylene glycol oxidation). A holding time of 0.5-1 hour effectively separates fine suspended particles, reducing the difficulty of subsequent filtration.

[0014] Furthermore, in step (2), the organic catalytic reduction covering agent is a biomass carbon source that can provide starch, preferably wheat flour.

[0015] Furthermore, in step (2), the mass ratio of antimony trioxide to the organic catalytic reduction covering agent is 1:0.015-0.2 (preferably 1:0.02-0.03).

[0016] Furthermore, in step (2), reduction smelting is carried out at a temperature of 1000-1100°C, the smelting and holding time is more than 2 hours (preferably 2-4 hours), and the holding and clarification is more than 1 hour (preferably 1-2 hours), and 4N antimony is successfully produced.

[0017] The present invention adopts ethylene glycol antimony product as raw material, carries out hydrolysis-bioreduction, and obtains 5N high-purity antimony through multi-field synergistic enhanced vacuum distillation. The total amount of impurity elements in the product is controlled below 10 ppm, the content of key impurity element As is controlled below 1 ppm, the content of Pb is controlled below 0.2 ppm, the content of Bi is controlled below 0.2 ppm, the content of Cu is controlled below 0.05 ppm, and the content of Fe is controlled below 0.5 ppm.

[0018] The impurity separation process primarily focuses on the removal of trace and ultra-trace associated impurities. Separation of trace elements like arsenic and lead presents some challenges, while bismuth is even more challenging. S and Na are removed during the hydrolysis process. Currently, 20 impurity elements have been successfully separated, enabling the production of 5N high-purity antimony. The total amount of impurity elements in the product is controlled below 10 ppm. GD-MAS analysis has achieved a significant 5N6 level, representing a breakthrough in the key production technology of 5N high-purity antimony. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below with reference to specific embodiments.

[0020] Example 1

[0021] This example studies the influence of hydrolysis parameters.

[0022] 1. Purpose

[0023] A pure water hydrolysis pretreatment process was used to remove water-soluble impurities from the ethylene glycol antimony raw material to produce high-purity antimony trioxide. Hydrolysis conditions (liquid-to-solid ratio, temperature, time, etc.) were optimized to verify process feasibility.

[0024] 2. Principle

[0025] Antimony glycolate (C6H 12 O6Sb2) undergoes hydrolysis reaction in high-temperature aqueous solution to generate antimony trioxide precipitate, while water-soluble impurities (such as unreacted ethylene glycol, inorganic salts, etc.) dissolve in the liquid phase and are pre-purified by solid-liquid separation.

[0026] Reaction equation:

[0027] C6H 12 O6Sb2+3H2O→Sb2O3↓+6CH2CH2OH+H2O (simplified formula)

[0028] 3. Materials and Equipment

[0029] Raw materials: antimony glycolate (industrial grade, purity ≥95%), the content of each component is shown in Table 1.

[0030] Table 1 Content of each component of ethylene glycol antimony

[0031]

[0032] Reagent: distilled water.

[0033] Equipment: magnetic heating stirrer; vacuum filtration device; electric blast drying oven; analytical balance, etc.

[0034] 4. Steps

[0035] Weigh a certain amount of ethylene glycol antimony solid, add an appropriate amount of distilled water according to the liquid-to-solid ratio, and mix thoroughly. Transfer the mixture to a magnetic stirrer, heat it to a desired temperature, and maintain it. Continue the reaction with magnetic stirring for a desired period of time to ensure uniform hydrolysis. After the reaction is complete, stop stirring and let it settle for a period of time. After separation, remove the supernatant. Filter the lower precipitate using a vacuum filtration device, and wash the filter cake three times with distilled water. Transfer the filter cake to a drying oven and dry it at 105°C for 4 hours to obtain antimony trioxide as a white powder.

[0036] 5. Results and Analysis

[0037] (1) Effect of liquid-solid ratio on hydrolysis

[0038] 1000 g of antimony ethylene glycol was placed in a beaker, and deionized water was added at liquid-to-solid ratios of 4:1, 8:1, 12:1, 16:1, and 20:1, respectively. The mixture was then placed on a magnetic heating stirrer and stirred for hydrolysis at 55°C for 1-2 hours. After the reaction was completed, the mixture was allowed to stand for a certain period of time to allow natural sedimentation, and then the supernatant was poured out. The slurry at the bottom was filtered using a vacuum filtration device to obtain hydrolyzed antimony trioxide. The results are shown in Table 2.

[0039] Table 2 Effect of liquid-solid ratio on hydrolysis

[0040]

[0041] At liquid-to-solid ratios of 4:1 and 8:1, the beaker contained a milky white, turbid liquid that remained undisturbed for 24 hours. During filtration, very fine particles clogged the filter paper, making solid-liquid separation difficult. At a liquid-to-solid ratio of 12:1, stratification was observed in the beaker. Removing the beaker and allowing it to stand for a short period of time made stratification difficult, but after 24 hours, stratification became apparent. After filtration, the hydrolyzed antimony white was tested for its various impurity contents. As shown in Table 2, the hydrolyzed antimony white contained only 60.2%, indicating that while the glycolized antimony was partially hydrolyzed, the reaction was incomplete. Increasing the liquid-to-solid ratio to 16:1 resulted in distinct stratification in the beaker. Removing the beaker and allowing it to stand for 3 hours clarified the slurry. Further increasing the liquid-to-solid ratio to 20:1, which became significantly clearer after removing the beaker and allowing it to stand for 0.5 hours. As can be seen from Table 2, when the liquid-solid ratio is greater than 16:1, the hydrolysis reaction has been fully carried out, but with the increase of the liquid-solid ratio, the clarification time is significantly shortened. Taking all factors into consideration, a liquid-solid ratio of 15-25 is more appropriate, and 20:1 is more preferred.

[0042] (2) Effect of temperature on hydrolysis

[0043] 1000 g of ethylene glycol antimony was placed in a beaker, deionized water was added at a liquid-to-solid ratio of 20:1, and the mixture was placed on a magnetic heating stirrer. The hydrolysis reaction was carried out at different temperatures. After the reaction was completed, the mixture was allowed to stand for a certain period of time to allow natural sedimentation. The supernatant was then poured out, and the slurry at the bottom was filtered using a vacuum filtration device to obtain hydrolyzed antimony trioxide. The results are shown in Table 3.

[0044] Table 3 Effect of temperature on hydrolysis

[0045]

[0046]

[0047] As shown in Table 3, when the temperature is below 35°C, the hydrolysis reaction essentially does not occur. This is because the hydrolysis of ethylene glycol antimony is an endothermic reaction and must proceed at a certain temperature. Further raising the temperature to 45°C, the hydrolysis reaction begins, but the reaction is incomplete. When the temperature rises above 55°C, the hydrolysis reaction proceeds fully. Further increases in temperature thereafter show little change in the product impurity content, and the S and Na contents also tend to stabilize. Excessively high temperatures increase energy consumption, making them unsuitable for industrial production. Furthermore, excessively high temperatures may be accompanied by side reactions, affecting product purity. Therefore, the hydrolysis reaction temperature is preferably between 55°C and 65°C.

[0048] (3) Summary

[0049] Using an organic antimony compound (ethylene glycol antimony) as the raw material, thermal hydrolysis pretreatment removes most of the water-soluble impurities in the raw material, such as sodium sulfate and sodium arsenate, producing purified hydrolyzed antimony trioxide. The preferred hydrolysis conditions are: a liquid-to-solid ratio of 20:1, a hydrolysis temperature of 55-65°C, a stirring time of 1-2 hours, and then a 0.5-1 hour standstill to settle. After the hydrolysis precipitate settles, it is filtered and microwave-dried at 100-150°C to obtain the product, antimony trioxide, as a loose white powder.

[0050] A liquid-to-solid ratio of 20:1 ensures that the raw materials are fully dispersed and avoids uneven hydrolysis caused by excessive local concentration.

[0051] The temperature is controlled at 55-65°C. Below 55°C, the reaction rate is low, while above 65°C, energy consumption will increase and side reactions (such as ethylene glycol oxidation) may be triggered.

[0052] Controlling the standing time to 0.5 to 1 hour can effectively separate fine suspended particles and reduce the difficulty of subsequent filtration.

[0053] Example 2

[0054] This example studies the effect of bioreduction.

[0055] 1. Purpose

[0056] Based on the product antimony trioxide produced by pure water hydrolysis in Example 1, a biological reducing agent with less impurity components was added. Through optimization experiments on the amount of reducing agent added, reaction time, reaction temperature, etc., 4N high-purity antimony was produced, providing the raw material basis for the subsequent preparation of 5N high-purity antimony.

[0057] 2. Principle

[0058] At a certain temperature, Sb2O3 is easily reduced by carbonaceous reducing agents.

[0059] Sb2O3+3C=2Sb+3CO

[0060] Sb2O3+3C=2Sb+3CO2

[0061] The scum on the surface is removed after cooling and crystallization.

[0062] 3. Instruments and Reagents

[0063] Instruments include muffle furnace, corundum crucible and other conventional instruments. Reagents include wheat flour, etc.

[0064] 4. Materials

[0065] The material was hydrolyzed with pure water in Example 1 to produce antimony trioxide, the content of each component of which is shown in Table 4.

[0066] Table 4 Content of each component of hydrolyzed antimony trioxide

[0067]

[0068] 5. Methods

[0069] A certain amount of antimony trioxide, produced by the hydrolysis of pure water in Example 1, was placed in a corundum crucible. An appropriate amount of analytical wheat flour was added and mixed thoroughly. The crucible was then placed in a muffle furnace. After heating to the set temperature, the crucible was kept at a constant temperature for a predetermined period of time, then maintained at this temperature for a predetermined period of time for clarification. The residue was then removed and heating was stopped. After the crucible cooled to room temperature, a sample was collected for inspection.

[0070] 6. Results and Discussion

[0071] (1) Influence of wheat flour dosage

[0072] 1000 g of hydrolyzed antimony trioxide (i.e., the antimony trioxide produced by pure water hydrolysis in Example 1) was placed in a corundum crucible, and 5 g, 10 g, 20 g, 30 g, and 40 g of wheat flour were added, respectively. The crucible was placed in a muffle furnace and heated to 1200 ° C. The reaction was carried out at a constant temperature for 4 hours, and then the mixture was kept warm and clarified for 2 hours. The effect of the amount of wheat flour on the preparation of high-purity antimony was investigated. The results are shown in Table 5.

[0073] Table 5 Content of each component of high-purity antimony at different wheat flour dosages

[0074]

[0075] Table 5 shows that the reaction approaches completion when the wheat flour dosage reaches 15g, resulting in a total impurity content of 39ppm in the 4N high-purity antimony. Further increases in the wheat flour dosage do not significantly change the impurity content. When the wheat flour dosage is less than 10g, the high-purity antimony impurity content is high, exceeding 100ppm, and still falls short of the 4N antimony standard. This is because the added wheat flour is insufficient to fully reduce the antimony oxide. Therefore, a wheat flour dosage of 2% of the hydrolyzed antimony trioxide is more appropriate.

[0076] Reducing agent selection tests were conducted using three different reducing agents. 1000g of hydrolyzed antimony trioxide was placed in a corundum crucible. 15g of each reducing agent was added to the crucible. The crucible was then heated to 1200°C in a muffle furnace, where it was kept at this temperature for 4 hours. The reaction was then maintained at this temperature for 2 hours to clarify the solution. The reduction effects of the different reducing agents were examined. The results are shown in Table 6.

[0077] Table 6 Reducing agent selection test record

[0078]

[0079] Table 6 shows that wheat flour significantly outperforms reduced coal and graphite. At 1200°C, the reduction of high-purity antimony using reduced coal and graphite revealed similar impurity levels. Graphite, however, showed superior arsenic removal. However, using graphite as the reducing agent significantly reduced impurity removal, reducing arsenic, lead, and bismuth levels to below 10 ppm. Considering both reducing agent cost and reduction performance, wheat flour is the preferred reducing agent.

[0080] (2) Influence of temperature

[0081] 1000 g of hydrolyzed antimony trioxide was taken in a corundum crucible, 20 g of wheat flour was added, and the crucible was placed in a muffle furnace and heated to 1000°C, 1100°C, 1200°C, and 1300°C, respectively. The reaction was carried out at a constant temperature for 4 hours, and then the solution was kept warm and clarified for 2 hours (the purpose of keeping warm and clarifying here is to extend the time to ensure that the reaction can proceed fully, and the impurity slag has enough time to float to the upper layer of the antimony liquid for easy removal). The effect of temperature on the preparation of high-purity antimony was investigated. The results are shown in Table 7.

[0082] Table 7 Contents of various components of high-purity antimony at different temperatures

[0083]

[0084] As shown in Table 7, when the temperature reaches 1000°C, the total impurity content in high-purity antimony is 36 ppm, meeting the 4N antimony standard. When the temperature is above 1000°C, the impurity content in high-purity antimony tends to stabilize. When the temperature is below 1000°C, the total impurity content in high-purity antimony is 97 ppm. Although this also meets the 4N antimony total impurity content requirement, the impurity removal effect is significantly different from that at 1000°C. Higher temperatures improve the post-reaction melt fluidity and more pronounced separation of the impurity slag phase from the antimony liquid, further facilitating slag phase removal. Therefore, based on comprehensive considerations, 1000°C was selected as the optimal reaction temperature.

[0085] (3) Influence of reaction time

[0086] 1000 g of hydrolyzed antimony trioxide was taken into a corundum crucible, 20 g of wheat flour was added, and the crucible was placed in a muffle furnace for heating. After heating to 1000 ° C, the reaction was carried out at a constant temperature for a certain time, and then the temperature was kept constant for clarification for a certain time. The effect of reaction time on the preparation of high-purity antimony was investigated. The results are shown in Table 8.

[0087] Table 8 Content of each component of high-purity antimony at different times

[0088]

[0089] As can be seen from Table 8, the impurity content in high-purity antimony is lowest and the best results are achieved when the reaction time is constant for 3 hours and the clarification time is 1 hour. The total impurity content in high-purity antimony can be reduced to 27 ppm. When the reaction time is less than 2 hours, the impurity content increases significantly, and with a reaction time of 0.5 hours, the total impurity content can reach 98 ppm. When the reaction time is insufficient, the wheat flour and antimony trioxide do not react completely, resulting in an increase in the impurity content in the test results. The table also shows that the clarification time has a certain impact on the impurity content of high-purity antimony. When the clarification time is less than 1 hour, the impurity content in high-purity antimony is high. This is because the clarification time is too short, the impurities are not completely separated from the high-purity antimony, and some impurity slag phases have not yet completely and stably floated on the antimony liquid phase, which affects impurity removal. Therefore, a reaction time of 2-3 hours and a clarification time of 1 hour are more appropriate.

[0090] (4) Summary

[0091] 4N antimony was prepared by bioreduction using hydrolyzed antimony trioxide obtained through thermal hydrolysis pretreatment as the raw material. The hydrolyzed antimony trioxide was mixed with an organic catalytic reduction coating agent (wheat flour) at a ratio of 1:0.02 and then reduced and smelted at 1000-1100°C for 2-3 hours to successfully produce 4N antimony.

[0092] Example 3

[0093] This example studies the effect of vacuum distillation.

[0094] 1. Purpose

[0095] Verify the feasibility of multi-field coordinated vacuum distillation process for purifying 4N antimony to 5N, and explore the effects of temperature, vacuum degree and evaporation rate on impurity separation efficiency.

[0096] 2. Principle

[0097] Thermodynamic analysis shows that low-boiling-point and high-boiling-point impurity elements in the main metal antimony can be removed and purified through vacuum distillation. The theoretical evaporation rate of Sb under different temperature and pressure conditions is shown in Table 9, and the critical pressure of Sb volatilization at different temperatures is shown in Table 10.

[0098] Table 9 Evaporation rate of Sb under different temperature and pressure conditions (g·cm -2 ·s -2 )

[0099]

[0100] Table 10 Critical pressure of Sb volatilization at different temperatures

[0101]

[0102] 3. Materials and instruments

[0103] Materials: 4N antimony prepared by bioreduction in Example 2.

[0104] Instruments and equipment: Multi-field collaborative vacuum distillation furnace.

[0105] 4. Methods

[0106] Using the 4N antimony prepared in Example 2 as the raw material, high- and low-temperature multi-field coordinated vacuum distillation was performed to remove impurities. The vacuum distillation was divided into two stages. The first stage was a high-temperature vacuum distillation. Under the condition of controlling a certain vacuum degree, adjusting the vacuum melting temperature and controlling the evaporation rate, the antimony and impurity elements were initially separated, and low-boiling-point impurities were mainly removed in the form of low-boiling-point antimony. Then, using the crystalline antimony obtained by high-temperature vacuum distillation as the raw material, a second stage of low-temperature vacuum distillation was performed. Under the condition of controlling a certain vacuum degree, adjusting the melting temperature and controlling the evaporation rate, the impurity elements were separated again, and high-boiling-point impurities were mainly removed in the form of bottom antimony.

[0107] 5. Results and Analysis

[0108] The vacuum level, melting temperature, and distillation time were controlled to perform a high-temperature distillation. The resulting crystalline antimony was then used as the raw material for a second low-temperature distillation, also controlling the vacuum level, melting temperature, and distillation time. The resulting crystalline antimony represents high-purity antimony. Eleven distillation experiments were conducted under varying vacuum levels, temperatures, and distillation times. The test data are shown in Table 11. The high-purity antimony was sent to the Inorganic Materials Analysis and Testing Center of the Shanghai Institute of Ceramics, Chinese Academy of Sciences, for testing. The test results are shown in Table 12.

[0109] Table 11 Vacuum fractional distillation test data record

[0110]

[0111] Table 12 Result data of impurity content of high purity antimony

[0112]

[0113]

[0114] From the analysis of Table 11 and Table 12, it can be seen that during the first distillation, if the melting temperature is lower than 650℃, the contents of S and Na elements generally exceed the standard, and low-boiling point elements such as arsenic also occasionally exceed the standard.

[0115] When smelting at 650°C, the best effect is achieved when the vacuum degree is controlled at 10-20 Pa, because low vacuum is more conducive to the distillation process. The best evaporation rate is controlled at 15-20 g / min. Too fast a rate will result in no antimony remaining at the bottom of the kettle, and too slow a rate will result in too much residual antimony at the bottom of the kettle, reducing the yield of crystalline antimony. After one distillation, most of the low-boiling point elements enter the low-boiling antimony. At this time, most of the low-boiling point impurity elements in the crystalline antimony have been removed. The temperature of the second low-temperature distillation is best at 580°C. At this time, high-boiling point impurity elements such as Cu, Fe, Ni, Pb, and Bi are mainly stripped out in the form of antimony at the bottom of the kettle. Similarly, the best effect is achieved when the vacuum degree is controlled at 5-10 Pa, and the most appropriate evaporation rate is controlled at 5-10 g / min.

[0116] The test results show that the high-purity antimony obtained by the present invention has the following impurity elements: B < 0.1, Na < 0.5, Mg < 0.2, Al < 0.5, Si < 1, S < 0.5, Ca < 0.5, Mn < 0.05, Fe < 0.5, Ni < 0.2, Cu < 0.05, Zn < 0.5, Ga < 0.1, As < 1, Ag < 0.05, Cd < 0.5, Sn < 0.5, Au < 0.05, Pb < 0.05, Bi < 0.2, reaching the 5N antimony standard. The product has reached a level of total impurities < 4 ppm, that is, 5N6 high-purity antimony (greater than 99.9996%), which is close to the 6N standard.

[0117] 6. Summary

[0118] Multi-field collaborative vacuum distillation consists of two stages: the first stage, high-temperature distillation, with a controlled vacuum of 10-20 Pa, a vacuum melting temperature of 650°C, and an evaporation rate of 15-20 g / min, performs a preliminary separation of antimony from impurity elements, primarily removing low-boiling-point impurities as low-boiling antimony. The second stage, low-temperature distillation, uses the crystalline antimony obtained from high-temperature vacuum distillation as raw material. Low-temperature vacuum distillation is performed at a controlled vacuum of 5-10 Pa, a vacuum melting temperature of 580°C, and an evaporation rate of 5-10 g / min, achieving a secondary separation of impurity elements and primarily removing high-boiling-point impurities as bottom-of-reactor antimony. This process can successfully produce 5N high-purity antimony, with the total amount of impurity elements in the product controlled below 10 ppm.

Claims

1. A method for preparing 5N high-purity antimony, characterized in that: The following steps are involved: (1) Hydrolysis: Using ethylene glycol antimony as raw material, thermal hydrolysis pretreatment is performed to obtain antimony trioxide; (2) Bioreduction: The antimony trioxide obtained in step (1) is mixed with an organic catalytic reduction covering agent, and reduced and smelted at a certain temperature, and then kept warm and clarified for a certain period of time to obtain 4N antimony; (3) Vacuum distillation: The 4N antimony obtained in step (2) is subjected to two stages of vacuum distillation: a first stage of high-temperature vacuum distillation, wherein the vacuum degree is controlled at 10-20 Pa, the vacuum melting temperature is 650-700° C., and the evaporation rate is 15-20 g / min; and a second stage of low-temperature vacuum distillation is carried out, using the crystalline antimony obtained by the first stage of high-temperature vacuum distillation as raw material, and low-temperature vacuum distillation is carried out, wherein the vacuum degree is controlled at 5-10 Pa, the vacuum melting temperature is 580-600° C., and the evaporation rate is 5-10 g / min, thereby achieving secondary separation of impurity elements; and 5N high-purity antimony is obtained.

2. The method for preparing 5N high-purity antimony according to claim 1, characterized in that: In step (1), the specific conditions of the hydrolysis are: a liquid-solid mass ratio of 15-25:1; and / or a hydrolysis temperature of 55-65° C.; and / or a stirring time of 1-2 hours; and / or standing for clarification for more than 0.3 hours after stirring; and / or filtering after the hydrolysis precipitate is clarified, and drying the filter residue at 100-150° C. to obtain the product antimony trioxide.

3. The method for preparing 5N high-purity antimony according to claim 2, characterized in that: In step (1), the specific conditions of the hydrolysis are: a liquid-solid mass ratio of 20:1; and / or, after stirring, the mixture is allowed to stand for 0.5-1 hour to clarify; and / or, after the hydrolysis precipitate is clarified, it is filtered and the filter residue is microwave-dried to obtain the product antimony trioxide.

4. The method for preparing 5N high-purity antimony according to claim 1 or 2, characterized in that: In step (2), the organic catalytic reduction covering agent is a biomass carbon source that can provide starch.

5. The method for preparing 5N high-purity antimony according to claim 4, characterized in that: In step (2), the organic catalytic reduction covering agent is wheat flour.

6. The method for preparing 5N high-purity antimony according to claim 1 or 2, characterized in that: In step (2), the mass ratio of antimony trioxide to the organic catalytic reduction covering agent is 1:0.015-0.

2.

7. The method for preparing 5N high-purity antimony according to claim 6, characterized in that: In step (2), the mass ratio of antimony trioxide to the organic catalytic reduction covering agent is 1:0.02-0.

03.

8. The method for preparing 5N high-purity antimony according to claim 1 or 2, characterized in that: In step (2), reduction smelting is carried out at a temperature of 1000-1100° C., the smelting and holding time is more than 2 hours, and the holding and clarification is more than 1 hour, and 4N antimony is successfully produced.

9. The method for preparing 5N high-purity antimony according to claim 8, characterized in that: In step (2), reduction smelting is carried out at a temperature of 1000-1100° C., the smelting and holding time is 2-4 hours, and the holding and clarification is carried out for 1-2 hours, thereby successfully producing 4N antimony.

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