Tellurium purification method

Abstract

The invention provides a tellurium purification method, and belongs to the technical field of metal metallurgy. The potassium sulfide is added, so that the vulcanizing agent and the metal impurities in the tellurium raw material form a stable compound, the dross on the surface of the melt is removed according to different specific gravities of the resultant and the tellurium liquid, the effect of removing the metal impurities is realized, and the purity of the tellurium product is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal metallurgy, and particularly relates to a method for purifying tellurium. Background Art

[0002] With the increasing demand for rare and dispersed metals in fields such as aerospace, nuclear industry, metallurgical industry, and electronic industry, tellurium has become a supporting material for new materials required in many industries. Independent deposits of tellurium are rare, and tellurium is mainly extracted and prepared from anode slime of electrolytic copper, fumes from zinc smelting, and smelting tailings of gold, silver, lead, etc. Currently, methods for separating and purifying tellurium include soda powder roasting method, alkaline high-pressure leaching method, sulfation roasting method, oxidative acid leaching method, extraction method, electrolytic refining method, vacuum distillation method, zone melting refining method, etc. However, it is difficult to remove lead and bismuth in tellurium raw materials by the above separation and purification methods, and when tellurium products are applied in the semiconductor industry, for example, it will seriously affect the optoelectronic properties and thermoelectric properties of the applied products. Summary of the Invention

[0003] The purpose of the present disclosure is to overcome the deficiencies of the prior art and provide a method for purifying tellurium, which is simple in operation, low in cost, and can effectively remove lead and bismuth in tellurium raw materials.

[0004] To achieve the above purpose, the technical solution adopted by the present disclosure is: a method for purifying tellurium, comprising the following steps: melting tellurium raw materials and potassium sulfide to obtain a melt, removing the scum on the surface of the melt, and then cooling to obtain tellurium products.

[0005] In some embodiments, the mass of potassium sulfide is 0.3 - 0.45% of the mass of tellurium raw materials.

[0006] In some embodiments, the end temperature of the cooling is 450 - 480 °C.

[0007] In some embodiments, casting treatment is further included after cooling.

[0008] In some embodiments, the steps of the casting treatment are: casting the cooled melt into ingots and cooling to room temperature to obtain tellurium products.

[0009] In some embodiments, the temperature of the melting is 640 - 680 °C.

[0010] In some embodiments, the number of times of removing the scum on the surface of the melt is at least 5 times.

[0011] In a second aspect, a tellurium product is provided, and the tellurium product is prepared by using the method for purifying tellurium.

[0012] In some embodiments, the Pb content of the tellurium product is less than 1 ppm, and the Bi content is less than 1 ppm.

[0013] Compared with the prior art, the beneficial effects of the present disclosure are as follows: By adding potassium sulfide, the present invention enables the sulfurizing agent to form stable compounds with metal impurities in the tellurium raw material, and according to the different specific gravities of the product and the tellurium liquid, the scum on the surface of the melt is removed, achieving the effect of removing metal impurities, thereby improving the purity of the tellurium product. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a process flow diagram of the purification method of tellurium of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] To facilitate the understanding of the present disclosure, the present disclosure will be described more comprehensively below. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided so that the understanding of the disclosure content of the present disclosure is more thorough and comprehensive.

[0016] As used herein, the terms:

[0017] "Prepared from..." is synonymous with "comprising". As used herein, the terms "comprising", "including", "having", "containing" or any other variation thereof are intended to cover non-exclusive inclusion. For example, a composition, step, method, article or device containing the listed elements is not necessarily limited to those elements, but may include other elements not explicitly listed or elements inherent to such composition, step, method, article or device.

[0018] The connecting word "consisting of" excludes any unstated element, step or component. If used in a claim, this phrase will make the claim closed, excluding materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the claim body rather than immediately following the subject, it only limits the elements described in that clause; other elements are not excluded from the claim as a whole.

[0019] When an equivalent, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, this should be understood to specifically disclose all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when the range "1-5" is disclosed, the described range should be interpreted to include the ranges "1-4", "1-3", "1-2", "1-2 and 4-5", "1-3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range.

[0020] In these embodiments, unless otherwise specified, the parts and percentages are by mass.

[0021] "Parts by mass" refers to the basic measurement unit representing the mass ratio relationship of multiple components. 1 part can represent any unit mass, such as 1 g or 2.689 g, etc. If we say that the mass of component A is a parts by mass and the mass of component B is b parts by mass, it means the mass ratio of component A to component B is a:b. Or, it means the mass of component A is aK and the mass of component B is bK (K is any number representing a multiple factor). It should not be misunderstood that, different from the number of parts by mass, the sum of the parts by mass of all components is not limited to 100 parts.

[0022] "And / or" is used to indicate that either one or both of the described situations may occur. For example, A and / or B includes (A and B) and (A or B).

[0023] In the present invention, for the purification method of tellurium, by adding potassium sulfide, the sulfiding agent forms a stable compound with the metal impurities in the tellurium raw material, and according to the different specific gravities of the product and the tellurium liquid, the scum on the surface of the melt is removed, achieving the effect of removing metal impurities, thereby improving the purity of the tellurium product.

[0024] As Figure 1 shown, the purification method of tellurium of the present invention includes the following steps:

[0025] S1: Melting the tellurium raw material and potassium sulfide to obtain a melt, and then removing the scum on the surface of the melt;

[0026] Specifically, the mass of the potassium sulfide is 0.3 - 0.45% of the mass of the tellurium raw material, for example, it can be but not limited to 0.3%, 0.32%, 0.34%, 0.36%, 0.38%, 0.4%, 0.42%, 0.45%.

[0027] When the mass of the potassium sulfide is 0.3 - 0.45% of the mass of the tellurium raw material, the metal impurities in the tellurium raw material can be removed more effectively, and the purity of the tellurium product can be improved.

[0028] Specifically, the melting temperature is 640 - 680 °C, for example, it can be but not limited to 640 °C, 645 °C, 650 °C, 655 °C, 660 °C, 665 °C, 670 °C, 675 °C, 680 °C. Within the above temperature range, the tellurium raw material can be completely melted, facilitating the full reaction of the metal impurities and potassium sulfide.

[0029] In order to increase the contact area between the tellurium raw material and potassium sulfide, before melting, the tellurium raw material needs to be crushed to obtain tellurium block raw materials, and the mass of the tellurium block raw materials is less than 5 kg.

[0030] In order to increase the reaction rate between the metal impurities in the tellurium raw material and potassium sulfide, the tellurium raw material in the smelting furnace has a certain height; for example, when calculating based on the maximum volume of the smelting furnace being 30 L, the height of the tellurium raw material is greater than 5 cm.

[0031] In the present invention, there are no special requirements for the addition sequence of potassium sulfide. It can be added simultaneously with the tellurium raw material, can be added during the smelting process of the tellurium raw material, or can be added after melting. Preferably, potassium sulfide is added simultaneously with the tellurium raw material. Adding potassium sulfide simultaneously with the tellurium raw material can effectively improve the purity of the tellurium product.

[0032] Specifically, after 1 / 3 of the materials in the smelting furnace are melted, in order to enable the metal impurities in the tellurium raw material to fully react with potassium sulfide, every 8 - 12 min, a graphite rod is used to stir the melt, and the stirring time is 1 - 2 min; a total of 5 times of stirring are performed.

[0033] Specifically, after the materials in the smelting furnace are completely melted, use a graphite rod to stir for 30 - 60 s and then let it stand, and then scoop up the scum on the surface of the melt with a graphite spoon until no scum is produced on the surface of the melt.

[0034] Specifically, the number of times of removing the scum on the surface of the melt is at least 5 times. For example, it can be but is not limited to 5 times, 7 times, 9 times.

[0035] S2: Cool the melt after removing the scum to 450 - 480 °C, pour it into a mold, and then cool it to room temperature to obtain a tellurium product.

[0036] Specifically, the end temperature of the cooling can be but is not limited to 450 °C, 455 °C, 460 °C, 465 °C, 470 °C, 475 °C, 480 °C.

[0037] In order to facilitate the demolding of the tellurium product, after cooling to room temperature, it is also necessary to continue cooling for at least 15 min.

[0038] In order to facilitate the storage of the tellurium product, after cooling to room temperature, it is also necessary to continue cooling for at least 1 h.

[0039] In the second aspect, a tellurium product is provided, and the tellurium product is prepared by using the tellurium purification method.

[0040] In some embodiments, the Pb content of the tellurium product is less than 1 ppm, and the Bi content is less than 1 ppm.

[0041] In the following examples and comparative examples, the mass percentage content of tellurium in the tellurium raw material used is 99.95%, the Pb content is 289 ppm; the Bi content is 331 ppm.

[0042] Example 1

[0043] This embodiment provides a method for purifying tellurium, which includes the following steps:

[0044] Add tellurium raw materials into a smelting furnace, then sprinkle potassium sulfide on the tellurium raw materials, and carry out smelting at a temperature of 660 °C. When 1 / 3 of the materials in the smelting furnace are melted, stir with a graphite rod for 1 minute every 10 minutes. After the materials in the smelting furnace are completely melted, stir with a graphite rod for 1 minute and then let it stand. Then, scoop up the scum on the surface of the melt with a graphite spoon until no scum is produced on the surface of the melt; wherein, the mass of potassium sulfide is 0.36% of the mass of the tellurium raw materials;

[0045] Cool the melt after removing the scum to 450 °C, then pour it into a mold, and scrape off the oxides on the surface of the melt with a graphite sheet, and cool it to room temperature to obtain tellurium products.

[0046] Example 2

[0047] This embodiment provides a method for purifying tellurium, which includes the following steps:

[0048] Add tellurium raw materials into a smelting furnace, then sprinkle potassium sulfide on the tellurium raw materials, and carry out smelting at a temperature of 640 °C. When 1 / 3 of the materials in the smelting furnace are melted, stir with a graphite rod for 1 minute every 8 minutes. After the materials in the smelting furnace are completely melted, stir with a graphite rod for 1 minute and then let it stand. Then, scoop up the scum on the surface of the melt with a graphite spoon until no scum is produced on the surface of the melt; wherein, the mass of potassium sulfide is 0.36% of the mass of the tellurium raw materials;

[0049] Cool the melt after removing the scum to 470 °C, then pour it into a mold, and scrape off the oxides on the surface of the melt with a graphite sheet, and cool it to room temperature to obtain tellurium products.

[0050] Example 3

[0051] This embodiment provides a method for purifying tellurium, which includes the following steps:

[0052] Add tellurium raw materials into a smelting furnace, then sprinkle potassium sulfide on the tellurium raw materials, and carry out smelting at a temperature of 680 °C. When 1 / 3 of the materials in the smelting furnace are melted, stir with a graphite rod for 1 minute every 12 minutes. After the materials in the smelting furnace are completely melted, stir with a graphite rod for 1 minute and then let it stand. Then, scoop up the scum on the surface of the melt with a graphite spoon until no scum is produced on the surface of the melt; wherein, the mass of potassium sulfide is 0.36% of the mass of the tellurium raw materials;

[0053] Cool the melt after removing the scum to 480 °C, then pour it into a mold, and scrape off the oxides on the surface of the melt with a graphite sheet, and cool it to room temperature to obtain tellurium products.

[0054] Example 4

[0055] This embodiment provides a method for purifying tellurium, which is only different from Embodiment 1 in that: the mass of potassium sulfide is 0.3% of the mass of the tellurium raw material; the remaining steps and parameters are exactly the same as those in Embodiment 1.

[0056] Embodiment 5

[0057] This embodiment provides a method for purifying tellurium, which is only different from Embodiment 1 in that: the mass of potassium sulfide is 0.45% of the mass of the tellurium raw material; the remaining steps and parameters are exactly the same as those in Embodiment 1.

[0058] Embodiment 6

[0059] This embodiment provides a method for purifying tellurium, which is only different from Embodiment 1 in that: the addition sequence of potassium sulfide is different. The addition sequence of potassium sulfide in this embodiment is as follows: Add the tellurium raw material into the melting furnace and carry out melting at a temperature of 660 °C. When 1 / 3 of the materials in the melting furnace are melted, and stir with a graphite rod for 1 minute every 10 minutes. After the materials in the melting furnace are completely melted, add potassium sulfide while stirring, and stir for a total of 20 minutes; let it stand, and then scoop up the scum on the surface of the melt with a graphite spoon until no scum is generated on the surface of the melt; among them, the mass of potassium sulfide is 0.36% of the mass of the tellurium raw material.

[0060] Comparative Example 1

[0061] This comparative example provides a method for purifying tellurium, which is only different from Embodiment 1 in that: sodium sulfide is used to replace potassium sulfide.

[0062] Comparative Example 2

[0063] This comparative example provides a method for purifying tellurium, which is only different from Embodiment 1 in that: the mass of potassium sulfide is 0.2% of the mass of the tellurium raw material.

[0064] Comparative Example 3

[0065] This comparative example provides a method for purifying tellurium, which is only different from Embodiment 1 in that: the mass of potassium sulfide is 0.5% of the mass of the tellurium raw material.

[0066] Performance Test

[0067] Impurity detection was carried out on the tellurium products and scum obtained in the examples and comparative examples, and the detection results are shown in Table 1.

[0068] Table 1

[0069]

[0070]

[0071] From the experimental data in Table 1, it can be seen that the purification method of tellurium in this application can effectively remove lead and bismuth in the tellurium raw material, and the contents of lead and bismuth in the tellurium product are both lower than 1 ppm.

[0072] From the experimental data of the examples and comparative examples, it can be seen that replacing potassium sulfide with sodium sulfide, or the addition amount of potassium sulfide being too low or too high, will result in high contents of lead and bismuth in the tellurium product, which is not conducive to the subsequent application of the tellurium product.

[0073] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of the present disclosure rather than to limit the protection scope of the present disclosure. Although the present disclosure has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present disclosure can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present disclosure.

Claims

1. A method for purifying tellurium, characterized in that, It includes the following steps: Melting tellurium raw materials and potassium sulfide to obtain a melt, removing the scum on the surface of the melt, and then cooling to obtain tellurium products.

2. The purification method of tellurium according to claim 1, characterized in that, The mass of the potassium sulfide is 0.3-0.45% of the mass of the tellurium raw materials.

3. The purification method of tellurium according to claim 1, characterized in that, The end temperature of the cooling is 450-480 °C.

4. The purification method of tellurium according to claim 1, wherein, After the cooling, it further includes a casting treatment.

5. The purification method of tellurium according to claim 4, characterized in that The steps of the casting treatment are: casting the cooled melt into an ingot and cooling it to room temperature to obtain tellurium products.

6. The purification method of tellurium according to claim 1, characterized in that, The temperature of the melting is 640-680 °C.

7. The purification method of tellurium according to claim 1, wherein The number of times of removing the scum on the surface of the melt is at least 5 times.

8. A tellurium product, characterized in that, The tellurium products are prepared by using the tellurium purification method described in any one of claims 1-7.

9. The tellurium product according to claim 8, wherein, The Pb content of the tellurium products is less than 1 ppm, and the Bi content is less than 1 ppm.

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