Method for efficiently removing impurity tellurium from crude selenium

Abstract

The application provides a method for efficiently removing impurity tellurium in crude selenium, and relates to the field of dispersed metal purification technology.The method comprises the following steps: adding SeO2 into crude selenium raw material which is soluble with tellurium, and melting, so as to selectively oxidize elemental tellurium in the crude selenium melt; and then, by virtue of the difference between the saturated vapor pressures of oxidized tellurium and selenium, the impurity tellurium in the crude selenium can be efficiently removed through vacuum distillation treatment, the tellurium is enriched in the form of oxidized tellurium in the distillation residue, and selenium products with a certain purity are obtained in the volatile matter. By using the method, the recovery rate of selenium can reach more than 90%, the added SeO2 in the crude selenium is reduced to elemental selenium by tellurium, the residual SeO2 in the reaction is volatilized in the melting process, and no other impurities are introduced, so that an innovative method for the purification of selenium is provided. The method is simple, efficient, energy-saving and environment-friendly, and low in cost, and has a milestone significance in the field of selenium-tellurium separation.

Description

Technical Field

[0001] This invention relates to the field of rare and dispersed metal purification technology, and in particular to a method for efficiently removing tellurium impurities from crude selenium. Background Technology

[0002] Selenium is a rare and dispersed metal widely used in materials, metallurgy, chemicals, agriculture, and medicine, and has become a key material supporting high-tech development and new material development. Selenium is mainly extracted and recovered from copper anode slime. During the oxidative roasting of copper anode slime, SeO2 flue gas forms a selenite solution in an absorption tower, which is reduced and precipitated by SO2 in the flue gas to form crude selenium powder. This crude selenium powder requires preliminary purification to obtain industrial-grade selenium products. For some crude selenium raw materials, tellurium impurities mainly exist in elemental form and are infinitely miscible with selenium, making it difficult to achieve ideal removal results through ordinary oxidation and vacuum distillation.

[0003] CN106946233 discloses a method for vacuum refining and purifying crude selenium. After melting, degassing, and vacuum distillation, crude selenium material can produce 99.9% industrial-grade selenium. The melting, degassing, and distillation temperatures in this method are 230–350℃, 250–400℃, and 500–1000℃, respectively; the vacuum degree is 1–20 Pa; and the distillation time is 3–4 hours. Experiments using this method on crude selenium material that is miscible with tellurium showed almost no change in the tellurium content of the resulting selenium product.

[0004] CN110745789 discloses a method for purifying crude selenium. This method involves adding a regulator to the crude selenium slag to induce oxidation of impurity elements, thereby altering their state. Then, utilizing the difference in properties between the impurity elements and selenium under vacuum conditions, vacuum distillation is used to separate selenium from the impurities. However, experiments using this method on crude selenium materials that are miscible with tellurium show that the resulting selenium product still contains a high level of tellurium impurities. Furthermore, the method involves a complex crushing process for lumpy crude selenium raw materials, resulting in a large amount of dust. Summary of the Invention

[0005] The purpose of this invention is to provide a method for efficiently removing tellurium impurities from crude selenium. The method of this invention can efficiently remove tellurium impurities from crude selenium, and the method is simple.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for efficiently removing tellurium impurities from crude selenium, comprising the following steps:

[0008] The crude selenium raw material is heated and melted, and SeO2 particles are added to the resulting melt for oxidative smelting. The tellurium in the crude selenium raw material is oxidized to tellurium oxide to obtain intermediate selenium.

[0009] The intermediate selenium was subjected to vacuum distillation.

[0010] Preferably, the crude selenium raw material comprises 95-99% Se and 1-5% Te by mass percentage.

[0011] Preferably, the heating and melting temperature is 300–500°C.

[0012] Preferably, the molar ratio of the SeO2 particles to the tellurium in the crude selenium raw material is (1-5):1.

[0013] Preferably, the temperature of the oxidative smelting is 300–500°C.

[0014] Preferably, the oxidative melting time is 0.5 to 3 hours.

[0015] Preferably, the vacuum distillation temperature is 260–300°C and the pressure is 5–10 Pa.

[0016] Preferably, the oxidative smelting is carried out under stirring conditions.

[0017] Preferably, the stirring speed is 50 to 300 r / min.

[0018] This invention provides a method for efficiently removing tellurium impurities from crude selenium, comprising the following steps: heating and melting the crude selenium raw material, adding SeO2 particles to the resulting melt for oxidative smelting, wherein the tellurium in the crude selenium raw material is oxidized to tellurium oxide to obtain intermediate selenium; and performing vacuum distillation on the intermediate selenium.

[0019] This invention involves adding SeO2 to crude selenium raw material that is miscible with selenium and smelting it to selectively oxidize elemental tellurium in the crude selenium melt. Then, by utilizing the difference in saturated vapor pressure between tellurium oxide and selenium, vacuum distillation can efficiently remove the impurity tellurium from the crude selenium. Tellurium is enriched in the distillation residue in the form of tellurium oxide, and a selenium product of a certain purity is obtained in the volatiles.

[0020] The method of this invention achieves a selenium recovery rate of over 90% when processing crude selenium raw materials. The SeO2 added to the crude selenium is reduced to elemental selenium by tellurium, and the remaining SeO2 volatilizes during the smelting process, without introducing other impurities. This provides an innovative method for selenium purification. The method is simple, efficient, energy-saving, environmentally friendly, and low-cost, representing a milestone in the field of selenium-tellurium separation. Attached Figure Description

[0021] Figures 1-3 These are the test reports for Examples 1 to 3;

[0022] Figure 4 This is the analysis report for Comparative Example 1. Detailed Implementation

[0023] This invention provides a method for efficiently removing tellurium impurities from crude selenium, comprising the following steps:

[0024] The crude selenium raw material is heated and melted, and SeO2 particles are added to the resulting melt for oxidative smelting. The tellurium in the crude selenium raw material is oxidized to tellurium oxide to obtain intermediate selenium.

[0025] The intermediate selenium was subjected to vacuum distillation.

[0026] This invention involves heating and melting a crude selenium raw material. In this invention, the crude selenium raw material preferably comprises 95-99% Se and 1-5% Te by mass percentage. In this invention, tellurium in the crude selenium raw material exists in elemental form and is infinitely miscible with selenium. In this invention, the heating and melting temperature is preferably 300-500°C, more preferably 350-450°C, and even more preferably 380-420°C. In this invention, the heating and melting is preferably carried out in a resistance furnace.

[0027] After reaching the heating and melting temperature, the present invention adds SeO2 particles to the obtained melt for oxidation smelting, and the tellurium in the crude selenium raw material is oxidized to tellurium oxide to obtain intermediate selenium.

[0028] In this invention, crude selenium raw material is first heated and melted before SeO2 particles are added, which facilitates sufficient contact between the SeO2 particles and tellurium impurities in the crude selenium raw material. This invention does not have special requirements for the particle size of the SeO2 particles; any SeO2 particles well-known in the art are acceptable. In this invention, the molar ratio of the SeO2 particles to tellurium in the crude selenium raw material is preferably (1-5):1, more preferably (2-4):1, and even more preferably (2.5-3.5):1. In this invention, the oxidation melting temperature is preferably 300-500°C, more preferably the same as the heating and melting temperature; the oxidation melting time is preferably 0.5-3 hours, more preferably 1-2.5 hours, and even more preferably 1.5-2 hours. This invention preferably performs the oxidation melting in an air atmosphere. In this invention, the oxidation melting is preferably performed under stirring conditions, and the stirring speed is preferably 50-300 r / min, more preferably 100-250 r / min, and even more preferably 150-200 r / min. In the oxidative smelting process described in this invention, tellurium in the crude selenium raw material is oxidized to tellurium oxide by SeO2, and SeO2 is reduced to elemental selenium by tellurium. The remaining SeO2 volatilizes during the smelting process and does not introduce other impurities.

[0029] After obtaining intermediate selenium, the present invention performs vacuum distillation on the intermediate selenium. In the present invention, the temperature of the vacuum distillation is preferably 260–300°C, more preferably 265–295°C, and even more preferably 270–290°C; the pressure of the vacuum distillation is preferably 5–10 Pa, more preferably 6–9 Pa, and even more preferably 7–8 Pa. The present invention does not specifically limit the time of the vacuum distillation; the appropriate vacuum distillation time can be determined according to the mass of the intermediate selenium. In the present invention, for kilogram-scale experiments, the vacuum distillation time is preferably 3–5 hours. The present invention utilizes the difference in saturated vapor pressure between tellurium oxide and selenium. Through vacuum distillation, the impurity tellurium in crude selenium can be efficiently removed. Tellurium is enriched in the distillation residue in the form of tellurium oxide, and a selenium product of a certain purity is obtained in the volatiles.

[0030] The following detailed description of the efficient method for removing tellurium impurities from crude selenium provided by the present invention, in conjunction with embodiments, should not be construed as limiting the scope of protection of the present invention.

[0031] Example 1

[0032] 100g of crude selenium raw material containing 3.37% Te (with tellurium impurity existing in elemental form) was weighed into a crucible and heated in a resistance furnace to melt. When the melt temperature reached 320℃, 5.86g of SeO2 particles (the molar ratio of SeO2 particles to tellurium was 2:1) were added for oxidative melting. The melting time was 1.5h, and the stirring speed was 150r / min, yielding an intermediate selenium melt. The obtained selenium melt was then placed in a vacuum furnace for vacuum distillation at a vacuum degree of 10Pa and a temperature of 260℃ for 2h. Finally, a refined selenium product of a certain purity was obtained from the volatiles, and tellurium oxide enrichment was obtained from the residue. The content of tellurium impurity in the volatiles was quantitatively analyzed by ICP-AES and found to be 46.97ppm (see [reference]). Figure 2 The test report (sample number KYHX20231454) showed a tellurium removal rate of 99.86%.

[0033] Example 2

[0034] 100g of crude selenium raw material containing 3.37% Te (with tellurium impurity existing in elemental form) was weighed into a crucible and heated in a resistance furnace to melt. When the melt temperature reached 320℃, 4.40g of SeO2 particles (the molar ratio of SeO2 particles to tellurium was 1.5:1) were added for oxidative melting. The melting time was 1.5h, and the stirring speed was 150r / min, yielding an intermediate selenium melt. The obtained selenium melt was then placed in a vacuum furnace for vacuum distillation at a vacuum degree of 10Pa and a temperature of 260℃ for 2h. Finally, a refined selenium product of a certain purity was obtained from the volatiles, and tellurium oxide enrichment was obtained from the residue. The content of tellurium impurity in the volatiles was quantitatively analyzed by ICP-AES and found to be 83.99ppm (see [reference]). Figure 2 The test report (sample number KYHX20231398) showed a tellurium removal rate of 99.75%.

[0035] Example 3

[0036] 100g of crude selenium raw material containing 3.37% Te (with tellurium impurity existing in elemental form) was weighed into a crucible and heated to melt in a resistance furnace. When the melt temperature reached 320℃, 2.93g of SeO2 particles (the molar ratio of SeO2 particles to tellurium was 1:1) were added for oxidative melting. The melting time was 1.5h, and the stirring speed was 150r / min, yielding an intermediate selenium melt. The obtained selenium melt was then placed in a vacuum furnace for vacuum distillation at a vacuum degree of 10Pa and a temperature of 260℃ for 2h. Finally, a refined selenium product of a certain purity was obtained from the volatiles, and a tellurium oxide enrichment was obtained from the residue. The content of tellurium impurity in the volatiles was quantitatively analyzed by ICP-AES and found to be 0.51% (see [link to relevant documentation]). Figure 3 The test report (sample number KYHX20231459) showed a tellurium removal rate of 86.40%.

[0037] Comparative Example 1

[0038] 100g of crude selenium raw material containing 3.37% Te (with tellurium impurity existing in elemental form) was weighed into a crucible and heated to melt in a resistance furnace at 320℃ for 1.5h with a stirring speed of 150r / min to obtain an intermediate selenium melt. The obtained selenium melt was then vacuum distilled in a vacuum furnace at a vacuum degree of 10Pa and a temperature of 260℃ for 2h. Finally, a refined selenium product of a certain purity was obtained from the volatiles, and tellurium oxide was enriched in the residue. ICP-AES quantitative analysis showed that the tellurium impurity content in the volatiles was 3.43% (see [reference]). Figure 4 (Analysis report, sample number 2#).

[0039] As can be seen from the results of the examples and Comparative Example 1, the present invention selectively oxidizes the elemental tellurium in the crude selenium melt by adding SeO2 to the crude selenium raw material that is miscible with selenium and smelting it, and then using the difference in saturated vapor pressure between tellurium oxide and selenium, the impurity tellurium in the crude selenium can be efficiently removed by vacuum distillation.

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for efficiently removing impurity tellurium from crude selenium, characterized in that, Includes the following steps: The crude selenium raw material is heated and melted, and SeO2 particles are added to the resulting melt for oxidative smelting. The tellurium in the crude selenium raw material is oxidized to tellurium oxide to obtain intermediate selenium. The oxidative smelting temperature is 300~500℃. The molar ratio of the SeO2 particles to the tellurium in the crude selenium raw material is (1~5):

1. The oxidative smelting time is 0.5~3h. The oxidative smelting is carried out under stirring conditions. The stirring speed is 50~300r / min. The intermediate selenium was subjected to vacuum distillation.

2. The method of claim 1, wherein, The crude selenium raw material comprises 95-99% Se and 1-5% Te by mass percentage.

3. The method according to claim 1 or 2, characterized in that, The heating and melting temperature is 300~500℃.

4. The method of claim 1, wherein, The vacuum distillation temperature is 260~300℃ and the pressure is 5~10Pa.

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