A process for producing refined selenium
By controlling the oxidation, melting separation, alkaline leaching, and acidification reduction processes, the problems of flue gas pollution and impurity introduction in existing selenium purification methods have been solved, achieving the preparation of refined selenium with high purity and high recovery rate.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIYUAN WANYANG SMELTING GROUP
- Filing Date
- 2025-07-08
- Publication Date
- 2026-07-31
AI Technical Summary
Existing selenium purification methods suffer from problems such as high flue gas pollution, introduction of many impurities, and low extraction rate, resulting in low utilization of selenium resources.
High-purity selenium is prepared by employing controlled oxidation, melting separation, alkaline leaching, and acidification reduction processes. Impurities are selectively oxidized and separated by utilizing differences in the melting points of substances. Combined with filtration and precipitation processes, high-purity selenium is produced.
It has achieved the preparation of high-purity (99.99%) refined selenium and a high recovery rate (over 92%), which significantly improves the utilization rate of selenium resources.
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Figure CN120681729B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for producing refined selenium, belonging to the field of crude selenium purification technology. Background Technology
[0002] Selenium is a rare metal, and with the rapid development of industries such as ceramics, dyes, solar cells, semiconductors, thermoelectric materials, and selenium-rich agricultural products, the demand for selenium is increasing daily. Selenium has become a key material driving high-tech development and innovation in new materials. However, due to its extremely low abundance (only 0.05 ppm) in the Earth's crust, selenium has always been a severely scarce metal resource. Selenium is mainly recovered from copper anode mud; therefore, separating and recovering selenium from crude selenium materials is of paramount importance for the comprehensive utilization of this resource.
[0003] Currently, the main methods for purifying crude selenium include pyrometallurgical selenium extraction, wet selenium extraction, semi-wet selenium extraction, and physical purification. Pyrometallurgical selenium extraction has long held a dominant position due to its advantages of strong adaptability to raw materials, simple operation, and ease of industrialization. However, this process suffers from drawbacks such as large flue gas volume and the easy generation of toxic gases like SeO2, severely restricting its further promotion. In contrast, wet selenium extraction has advantages such as low energy consumption, cleanliness, environmental friendliness, and low production costs, showing promising application prospects. However, wet processes, due to the wide variety of solvents, are prone to introducing impurities, leading to a decrease in selenium extraction rate. Semi-wet selenium extraction processes, by replacing the reduction smelting and oxidative refining processes of pyrometallurgical methods with wet processing, combine the advantages of both methods, but still fail to solve the problem of sintering of raw materials during the initial roasting process, thus limiting selenium extraction efficiency. Physical purification methods mainly utilize the vapor pressure difference between selenium and impurity components for separation. Chinese patent CN116161629A proposes a method for purifying selenium by changing the occurrence state of impurity components through oxidation reactions, followed by separation using vacuum distillation. However, this method cannot effectively extract selenium in the CuSeO3 and PbSeO3 forms, resulting in a selenium recovery rate of less than 80%, causing resource waste. These limitations of existing selenium extraction methods highlight the urgent need to develop new and efficient selenium extraction processes.
[0004] Therefore, this invention is proposed to solve the above-mentioned technical problems. Summary of the Invention
[0005] To address the aforementioned technical problems in the existing technology, this invention provides a refined selenium production process that can produce 99.99% refined selenium while achieving a high recovery rate, significantly improving the utilization rate of selenium resources. The process specifically includes the following steps:
[0006] Controlled oxidation: The slurry after mixing crude selenium powder and water is mixed with hydrogen peroxide solution at room temperature and selectively oxidized, followed by solid-liquid separation. The filter residue is washed with water to obtain primary selenium.
[0007] Melting and separation: The obtained primary selenium is heated and melted at 130-150℃ and then filtered to obtain selenium melt 1. The filter residue is heated and melted at 230-300℃ and then filtered to obtain selenium melt 2. The filter residue is heated and melted at 520-540℃ and then filtered to obtain selenium melt 3. The selenium melts are combined and cooled to obtain selenium-containing powder.
[0008] Alkaline leaching: The selenium-containing powder is leached in a mixed solution of sodium sulfite and sodium hydroxide at a reaction temperature of 92-98°C with stirring. After leaching for 3 hours, the solid and liquid are separated to obtain a selenium-containing leachate.
[0009] Acidification and reduction: The pH of the obtained selenium-containing leachate is adjusted to 5-6 with sulfuric acid to precipitate the precipitate. The precipitate is then separated into solid and liquid, washed, and dried to obtain refined selenium.
[0010] Preferably, the mass ratio of crude selenium powder to water in the slurry is 1:1, the hydrogen peroxide solution is mixed with the slurry at a mass ratio of 0.15:1 and selectively oxidized, the selective oxidation time is 0.5 to 1 hour, and the mass concentration of the hydrogen peroxide solution is 30%.
[0011] The equipment used for heating and melting in this invention has no special requirements; any well-known melting furnace or resistance furnace in the art can be used. The preferred timing for adding the primary selenium powder to the furnace body is before or after the furnace body reaches the heating and melting temperature. More preferably, the primary selenium powder is added after the furnace body reaches the heating and melting temperature to prevent elemental selenium from being oxidized to selenium dioxide.
[0012] The heating and melting process described in this invention is preferably carried out under sealed conditions to avoid oxidation of selenium.
[0013] The present invention preferably involves evacuating the sealed space, filling it with a protective gas, or sealing it directly without any treatment, and then heating and melting it.
[0014] Preferably, the heating and melting time is 10 to 30 minutes.
[0015] The present invention filters the selenium melt. The filtration device used for filtration has a pore size of 100-200 mesh. There are no special requirements for the filtration device. Any device with filtration function known in the art can be used, specifically, but not limited to, a screen or filter. There are no special requirements for the material of the filtration device. It should be able to withstand the high temperature of the melt and be chemically stable without introducing other impurities. Specifically, it can be, but not limited to, stainless steel or ceramic.
[0016] Preferably, the particle size of the selenium-containing powder is 100 mesh.
[0017] Preferably, the selenium-containing powder is leached with a mixed solution of sodium sulfite and sodium hydroxide at a solid-liquid ratio of 1.1 to 1.2:10 (g / ml), wherein the concentration of sodium sulfite is 0.23 to 0.25 g / ml and the concentration of sodium hydroxide is 0.012 to 0.014 g / ml.
[0018] Preferably, the reaction temperature is 95°C.
[0019] Preferably, the crude selenium powder comprises the following components by mass percentage: Se 85-92%, Te 1.5-2.5%, Cu 3-5%, Pb 2-4%, with the balance being water.
[0020] The beneficial effects of this invention are:
[0021] This invention provides a process for producing refined selenium. First, an oxidant is used at room temperature to oxidize impurities in crude selenium powder (such as elemental tellurium, PbTe, Cu2Se, and PbSe) into oxides with larger particle sizes (TeO2, PbSeO3, and CuSeO3), while the elemental selenium phase remains unchanged, thus obtaining primary selenium. Utilizing the differences in melting points among the various substances in primary selenium, the oxidized crude selenium is controlled and, through precise temperature control and simple separation operations, the selenium-containing substances are melted into a molten mass for enrichment. TeO2 particles with a melting point of 732℃ are attached to the slag, and filtration achieves effective separation of tellurium and selenium. This method not only reduces the interference of tellurium on subsequent selenium purification processes and improves selenium purity, but also increases the selenium yield. Attached Figure Description
[0022] Figure 1 A process flow diagram of a method for producing refined selenium provided in an embodiment of the present invention. Detailed Implementation
[0023] 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.
[0024] A process for producing refined selenium involves controlling the oxidation, melting and separation, alkaline leaching, and acidification and reduction of crude selenium to obtain a high-yield refined selenium product.
[0025] Example 1
[0026] Controlled oxidation: 200g of crude selenium material (main components: Se 85.1%, Te 1.6%, Cu 2.9%, Pb 1.9%, balance water) was placed in a reactor and mixed with deionized water at a 1:1 ratio. Then, 60g of 30% hydrogen peroxide solution was added dropwise at a stirring rate of 300r / min and reacted for 30min. After filtration and washing with water, primary selenium was obtained.
[0027] Melting and Separation: Wrap the primary selenium in a 100-mesh stainless steel sieve and place it in a crucible with small holes at the bottom. Place a receiving basin under the crucible. Turn on the power switch of the resistance furnace and allow it to heat normally. When the furnace temperature reaches 130°C, place the receiving basin and the crucible together in a sealed melting furnace for heating and melting. After holding at this temperature for 10 minutes, remove the furnace and you will get selenium melt 1 in the receiving basin. Heat the furnace to 230°C to melt the filter residue. After holding at this temperature for 10 minutes, remove the furnace and you will get selenium melt 2 in the receiving basin. Heat the furnace to 520°C to melt the filter residue. After holding at this temperature for 10 minutes, remove the furnace and you will get selenium melt 3 in the receiving basin. Combine the selenium melts, cool and pulverize them to obtain 167.9g of selenium-containing powder.
[0028] Alkaline leaching: The selenium-containing powder was completely dissolved in a mixed solution of 1530g sodium sulfite with a concentration of 0.23g / ml and sodium hydroxide with a concentration of 0.012g / ml. The solution was leached at a stirring rate of 300r / min at a reaction temperature of 92℃ for 3 hours. After leaching, the solution was filtered to obtain a selenium-containing leachate.
[0029] Acidification and reduction: The pH of the obtained selenium-containing leachate is adjusted to 5-6 with sulfuric acid to precipitate the precipitate. The precipitate is then filtered, washed, and dried to obtain refined selenium.
[0030] Example 2
[0031] Controlled oxidation: 200g of crude selenium material (main components: Se 92.1%, Te 2.5%, Cu 5.1%, Pb 3.9%, balance water) was placed in a reactor and mixed with deionized water at a 1:1 ratio. Then, 60g of 30% hydrogen peroxide solution was added dropwise at a stirring rate of 300r / min and reacted for 30min. After filtration and washing with water, primary selenium was obtained.
[0032] Melting and Separation: Wrap the primary selenium in a 200-mesh stainless steel sieve and place it in a crucible with small holes at the bottom. Place a receiving basin under the crucible. Turn on the power switch of the resistance furnace and allow it to heat normally. When the furnace temperature reaches 150°C, place the receiving basin and the crucible together in a sealed melting furnace for heating and melting. After holding at this temperature for 30 minutes, remove the furnace and you will get selenium melt 1 in the receiving basin. Heat the furnace to 300°C to melt the filter residue. After holding at this temperature for 30 minutes, remove the furnace and you will get selenium melt 2 in the receiving basin. Heat the furnace to 540°C to melt the filter residue. After holding at this temperature for 30 minutes, remove the furnace and you will get selenium melt 3 in the receiving basin. Combine the selenium melts, cool and pulverize them to obtain 185.1g of selenium-containing powder.
[0033] Alkaline leaching: The selenium-containing powder was completely dissolved in a mixed solution of 1540g sodium sulfite with a concentration of 0.25g / ml and sodium hydroxide with a concentration of 0.014g / ml. The solution was leached at a stirring rate of 300r / min at a reaction temperature of 98℃ for 3 hours. After leaching, the solution was filtered to obtain a selenium-containing leachate.
[0034] Acidification and reduction: The pH of the obtained selenium-containing leachate is adjusted to 5-6 with sulfuric acid to precipitate the precipitate. The precipitate is then filtered, washed, and dried to obtain refined selenium.
[0035] Example 3
[0036] Controlled oxidation: 200g of crude selenium material (main components: Se 88.3%, Te 1.9%, Cu 3.8%, Pb 3.2%, balance water) was placed in a reactor and mixed with deionized water at a 1:1 ratio. Then, 60g of 30% hydrogen peroxide solution was added dropwise at a stirring rate of 300r / min and reacted for 30min. After filtration and washing with water, primary selenium was obtained.
[0037] Melting and Separation: Wrap the primary selenium in a 150-mesh stainless steel sieve and place it in a crucible with small holes at the bottom. Place a receiving basin under the crucible. Turn on the power switch of the resistance furnace and allow it to heat normally. When the furnace temperature reaches 135°C, place the receiving basin and the crucible together in a sealed melting furnace for heating and melting. After holding at this temperature for 20 minutes, remove the furnace and you will get selenium melt 1 in the receiving basin. Heat the furnace to 270°C to melt the filter residue. After holding at this temperature for 20 minutes, remove the furnace and you will get selenium melt 2 in the receiving basin. Heat the furnace to 530°C to melt the filter residue. After holding at this temperature for 20 minutes, remove the furnace and you will get selenium melt 3 in the receiving basin. Combine the selenium melts, cool and pulverize them to obtain 175.2g of selenium-containing powder.
[0038] Alkaline leaching: The selenium-containing powder was completely dissolved in a mixed solution of 1520g sodium sulfite with a concentration of 0.24g / ml and sodium hydroxide with a concentration of 0.013g / ml. The solution was leached at a stirring rate of 300r / min at a reaction temperature of 95℃ for 3 hours. After leaching, the solution was filtered to obtain a selenium-containing leachate.
[0039] Acidification and reduction: The pH of the obtained selenium-containing leachate is adjusted to 5-6 with sulfuric acid to precipitate the precipitate. The precipitate is then filtered, washed, and dried to obtain refined selenium.
[0040] Comparative Example 1
[0041] Controlled oxidation: 200g of crude selenium material (main components: Se 92.1%, Te 2.5%, Cu 5.1%, Pb 3.9%, balance water) was placed in a reactor and mixed with deionized water at a 1:1 ratio. Then, 60g of 30% hydrogen peroxide solution was added dropwise at a stirring rate of 300r / min and reacted for 30min. After filtration, washing with water, and drying, primary selenium was obtained.
[0042] Alkaline leaching: The primary selenium was completely dissolved in a mixed solution of 1540g sodium sulfite with a concentration of 0.25g / ml and sodium hydroxide with a concentration of 0.014g / ml. The solution was leached at a stirring rate of 300r / min at a reaction temperature of 98℃. After leaching for 3 hours, the solution was filtered to obtain a selenium-containing leachate.
[0043] Acidification and reduction: The pH of the obtained selenium-containing leachate is adjusted to 5-6 with sulfuric acid to precipitate the precipitate. The precipitate is then filtered, washed, and dried to obtain refined selenium.
[0044] Comparative Example 2
[0045] Melting and Separation: 200g of crude selenium material (main components: Se 88.3%, Te 1.9%, Cu 3.8%, Pb 3.2%, balance water) was wrapped in a 150-mesh stainless steel sieve and placed inside a crucible with small holes at the bottom. A receiving basin was placed under the crucible. The power switch of the electric resistance furnace was turned on and allowed to heat normally. When the furnace temperature reached 135℃, the receiving basin and crucible were placed together in a sealed melting furnace for heating and melting. After holding at this temperature for 20 minutes, the material was removed, and selenium melt 1 was obtained in the receiving basin. The furnace temperature was raised to 270℃ to melt the filter residue. After holding at this temperature for 20 minutes, the material was removed, and selenium melt 2 was obtained in the receiving basin. The furnace temperature was raised to 530℃ to melt the filter residue. After holding at this temperature for 20 minutes, the material was removed, and selenium melt 3 was obtained in the receiving basin. The selenium melts were combined, cooled, and pulverized to obtain 156.4g of selenium-containing powder.
[0046] Alkaline leaching: The selenium-containing powder was completely dissolved in a mixed solution of 1400g sodium sulfite with a concentration of 0.24g / ml and sodium hydroxide with a concentration of 0.013g / ml. The solution was leached at a stirring rate of 300r / min at a reaction temperature of 95℃ for 3 hours. After leaching, the solution was filtered to obtain a selenium-containing leachate.
[0047] Acidification and reduction: The pH of the obtained selenium-containing leachate is adjusted to 5-6 with sulfuric acid to precipitate the precipitate. The precipitate is then filtered, washed, and dried to obtain refined selenium.
[0048] According to the Chinese nonferrous metals industry standard YS / T223-2007, the chemical composition of impurity elements in the refined selenium products obtained by the examples and comparative examples was quantitatively analyzed by ICP-AES. The selenium recovery rate was calculated by dividing the total selenium content in the product by the total selenium content in the raw material. The specific results are shown in Table 1.
[0049] Table 1. Data results of Examples 1-3 and Comparative Examples 1-2
[0050]
[0051]
[0052] According to the data in Table 1, the selenium content in the purified selenium products of Examples 1-3 of this invention is as high as 99.99% or more, fully meeting the requirements for Se9999 grade in the "Nonferrous Metals Industry Standard of the People's Republic of China" (YS / T 223-2007). In Examples 1-3, the Te content in the purified selenium products is only 3-5 ppm, significantly lower than the Te impurity content in Control Example 1. This indicates that the oxidized Te impurities can be effectively removed by precisely controlling the temperature and using simple separation steps. Furthermore, the selenium recovery rate in Examples 1-3 is much higher than that in Control Example 2, proving that alkaline leaching has a good extraction effect on selenium in the CuSeO3 and PbSeO3 forms. Moreover, the selenium recovery rate in the purified selenium products obtained in the examples of this invention reaches over 92%, which shows that while improving the purity of the purified selenium products, a high recovery rate can also be ensured.
[0053] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A process for the production of refined selenium, characterized in that, Includes the following steps: Controlled oxidation: The slurry after mixing crude selenium powder and water is mixed with hydrogen peroxide solution at room temperature and selectively oxidized, followed by solid-liquid separation. The filter residue is washed with water to obtain primary selenium. Melting and separation: The obtained primary selenium is heated and melted at 130~150℃ and then filtered to obtain selenium melt 1. The filter residue is heated and melted at 230~300℃ and then filtered to obtain selenium melt 2. The filter residue is heated and melted at 520~540℃ and then filtered to obtain selenium melt 3. The selenium melts are combined and cooled to obtain selenium-containing powder with a particle size of 100 mesh. The heating and melting are carried out under closed conditions for 10~30 minutes. Alkaline leaching: The selenium-containing powder is leached in a mixed solution of sodium sulfite and sodium hydroxide at a reaction temperature of 92-98℃ with a solid-liquid ratio of 1.1-1.2 g: 10 ml. After leaching, the solid and liquid are separated to obtain a selenium-containing leachate. The concentration of sodium sulfite is 0.23-0.25 g / ml and the concentration of sodium hydroxide is 0.012-0.014 g / ml. Acidification and reduction: The pH of the obtained selenium-containing leachate is adjusted to 5-6 with sulfuric acid to precipitate the precipitate. The precipitate is then separated into solid and liquid, washed, and dried to obtain refined selenium.
2. A process for producing refined selenium as claimed in claim 1 wherein, The crude selenium powder and water in the slurry are in a mass ratio of 1:
1. The hydrogen peroxide solution is mixed with the slurry in a mass ratio of 0.15:1 and selectively oxidized for 0.5 to 1 hour. The mass concentration of the hydrogen peroxide solution is 30%.
3. The process for producing pure selenium according to claim 1, wherein The reaction temperature is 95°C.
4. The process for producing pure selenium according to claim 1, wherein The crude selenium powder comprises the following components by mass percentage: Se 85~92%, Te 1.5~2.5%, Cu 3~5%, Pb 2~4%, with the balance being water.