A short-process purification technology for tellurium from crude tellurium.

Abstract

This invention discloses a short-process purification method for tellurium from crude tellurium. The process first involves washing the crude tellurium with water to achieve liquid-solid separation, yielding washed crude tellurium. The washed crude tellurium is then subjected to pyrometallurgical oxidation to obtain tellurium oxide slag. This tellurium oxide slag is then leached to obtain a tellurium leachate. The tellurium leachate is subsequently subjected to electrowinning and casting processes to complete the tellurium purification. The advantages of this invention are: a short process flow, high yield, low chemical usage, and low cost. By combining pyrometallurgical and hydrometallurgical methods, crude tellurium is converted into 4N refined tellurium, effectively shortening the refined tellurium smelting process, reducing intermediate products, and increasing the tellurium yield to over 95%.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal metallurgy technology and is a short-process purification technology for tellurium using crude tellurium as raw material. Background Technology

[0002] Tellurium is a rare dispersed metal with an abundance of approximately 1 × 10⁻⁶ in the Earth's crust. -7 Tellurium is mostly found as an associated mineral in pyrite, chalcopyrite, and sphalerite; no independent industrial mineral of tellurium has yet been discovered. Tellurium is primarily extracted from anode mud from copper electrolysis, flue dust from zinc smelting, and tailings from gold, silver, and lead smelting processes. Current methods for separating and purifying tellurium include soda roasting, alkaline high-pressure leaching, sulfation roasting, oxidative acid leaching, extraction, electrolytic refining, vacuum distillation, and zone refining.

[0003] Existing technology involves adding tellurium powder to be purified into a vacuum-sealed vertical flash furnace, then introducing oxygen. The oxygen reacts with the tellurium powder in the furnace, forming a gas-solid reaction under convection, with the reaction temperature controlled at 320–420°C. This method requires oxygen to be introduced under vacuum, placing high demands on the safety of the equipment itself.

[0004] Existing technologies involve melting crude tellurium and then performing vertical zone melting. The melting zone temperature is 460–500℃, the melting zone movement speed is ≤1.0 mm / min, the melting zone width is 0.5–2.0 cm, and the melting process is repeated 10–20 times. During this repeated melting process, impurities are removed from the crystalline tellurium zone, allowing for a slow and complete separation of crystalline tellurium from molten impurities, thus improving the purity of the crystalline tellurium. This method is a zone melting method, which involves high temperatures and requires the use of hydrogen gas. It places high demands on environmental conditions and control technology, making its practical application in production quite difficult.

[0005] Existing technologies also involve mixing crude tellurium powder with water for rinsing; mixing the rinse residue with an alkaline solution, introducing an oxidizing gas, and performing pressurized oxidative leaching; mixing the leaching residue with an acidic solution for atmospheric pressure acid leaching; neutralizing the acidic leaching solution with alkali before adding a reducing agent for reduction precipitation; mixing the neutralized residue and the reduced precipitate residue for calcination to remove impurities; mixing the calcined residue with an alkaline solution for alkali leaching to produce a new leaching solution; and electrolytically refining the resulting alkali leaching solution to obtain high-purity tellurium. This process is easy to implement, and the later stages are also electrolytic refining methods, but the initial impurity removal process is relatively long. Summary of the Invention

[0006] This invention discloses a short-process purification method for tellurium from crude tellurium, in order to solve any of the above-mentioned and other potential problems of the prior art.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is: a process for purifying tellurium from crude tellurium using a short process, the process specifically including the following steps:

[0008] S1) First, the coarse tellurium to be treated is washed with water to separate the liquid and solid, and then the washed coarse tellurium is obtained.

[0009] S2) The water-washed crude tellurium obtained in S1) is subjected to pyrometallurgical oxidation treatment to obtain oxidized tellurium slag;

[0010] S3) The oxidized tellurium slag obtained in S2) is subjected to leaching treatment to obtain tellurium leachate;

[0011] S4) The tellurium leachate obtained in S3) is subjected to electrowinning and casting processes in sequence to complete the purification of tellurium.

[0012] Furthermore, the specific steps of S1 are as follows:

[0013] First, the crude tellurium is washed with water at a liquid-to-solid ratio of (3-6):1, heated and stirred, while alkali is added to control the final pH to neutral, the temperature is raised to 50-95℃, and the stirring time is 1-4 hours. After the reaction is completed, the liquid and solid are separated to obtain the washed crude tellurium.

[0014] Furthermore, the specific steps of S2 are as follows:

[0015] S2.1) The water-washed crude tellurium obtained in S1) is mixed with the auxiliary agent in a certain proportion to obtain a mixture;

[0016] S2.2) The mixture of S2.1) is placed in a pyrometallurgical apparatus, and the gas flow is controlled to heat it to a certain temperature. After the reaction, oxidized tellurium slag is obtained.

[0017] Furthermore, the ratio of water-washed crude tellurium to auxiliary agent in S2.1) is (10-50):1.

[0018] Furthermore, the auxiliary agent in S2.1) is soda ash, baking soda, sodium sulfide, potassium carbonate or sodium hydroxide.

[0019] Furthermore, in step S2.2), the intake air volume is introduced at a rate of (1 to 10) times the theoretical amount for the reaction with tellurium, the temperature is 300 to 450°C, and the holding time is 4 to 12 hours.

[0020] Furthermore, the intake air in S2.2) is air or oxygen.

[0021] Furthermore, the process parameters for S3) are as follows:

[0022] The liquid-solid ratio of the total leached solution to the added tellurium oxide slag is (3-4):1, the free alkalinity is 20-100 g / L, the amount of sulfiding agent added is based on the excess of sulfur ions as tested by lead acetate test paper, the reaction time is 1-4 h, and the reaction temperature is 50-95 ℃.

[0023] Furthermore, the selenium removal rate in the process is not less than 95%; the tellurium direct recovery rate is above 95%.

[0024] A 4N tellurium, which is prepared using the above-described process.

[0025] The beneficial effects of this invention are:

[0026] 1. This process utilizes a combination of pyrometallurgical and hydrometallurgical purification methods to purify crude tellurium to over 99.99%, with a direct tellurium recovery rate of over 95%.

[0027] 2. This process has a short flow, low cost, few intermediate products, and a friendly working environment, making it easy to apply to industrial production. Attached Figure Description

[0028] Figure 1 This invention provides a process flow for a short-process purification of tellurium from crude tellurium. Detailed Implementation

[0029] The content of the present invention will be further described below with reference to the accompanying drawings and examples.

[0030] The purpose of this invention is to provide a short-process purification process for tellurium, which involves water washing, pyrometallurgical oxidation, sulfide leaching, electrowinning, and casting to convert crude tellurium into 99.99% refined tellurium. Compared with other processes, this process uses crude tellurium as raw material, has a short process flow, low cost, fewer intermediate products, is environmentally friendly, and is easy to industrialize.

[0031] The technical solution of this invention mainly includes the following steps, and the process flow diagram of this invention is attached. Figure 1 .

[0032] Step 1. Coarse tellurium washing process

[0033] The raw crude tellurium mainly contains impurities such as Te, Cu, Se, Pb, and small amounts of acid. To reduce the corrosion of the equipment by acid during the subsequent pyrometallurgical oxidation process and to remove some water-soluble impurities, the crude tellurium is first washed with water. The liquid-to-solid ratio is controlled at (3-6):1. A certain amount of alkali is added, and the mixture is heated and stirred. The final pH is controlled to be neutral, the temperature is controlled at (50-95)℃, and the stirring time is controlled at (1-4) hours. After the reaction is completed, the liquid and solid are separated to obtain water-washed crude tellurium.

[0034] Step 2. Pyrometallurgical oxidation process

[0035] Add salt or alkali additives to the water-washed crude tellurium obtained in step one in a certain proportion, mix evenly, raise the temperature and introduce air, control the temperature (300-450)℃, introduce air at a rate of (1-10) times the theoretical amount of tellurium to react, and react for (4-12) hours to obtain oxidized tellurium slag.

[0036] Step 3. Tellurium leaching process

[0037] The amount of tellurium oxide slag obtained in step 2 was controlled and the liquid-solid ratio of the total solution was (3-4):1. Sulfide leaching was carried out, with the free alkalinity controlled at (20-100) g / L and the amount of sulfide reagent added determined by the excess of sulfur ions as the endpoint of the addition. The reaction time was (1-4) h and the reaction temperature was (50-95) ℃, resulting in a tellurium leachate with high tellurium content and low impurities.

[0038] Step 4. Electrowinning process

[0039] Electrowinning of the tellurium leachate obtained in step three yields high-purity tellurium.

[0040] Step 5. Casting process

[0041] The electrolytic tellurium obtained in step four is cast to remove impurities, resulting in a 99.99% pure tellurium product.

[0042] Example 1:

[0043] Take 1 kg of crude tellurium (dry weight), containing 78.88% tellurium, control the liquid-to-solid ratio at 3:1, add a certain amount of liquid alkali, adjust the pH to 6.5, raise the temperature and stir, controlling the temperature at 95℃ and the stirring time at 1 hour. After the reaction is complete, separate the solid and liquid, and send the liquid to wastewater treatment to obtain washed crude tellurium. Washed crude tellurium and alkaline auxiliary agent (soda ash) were mixed evenly at a ratio of 50:1, spread evenly in an open container, and transferred to a calcining furnace. The temperature was controlled at 450℃, the air intake was 5 times the theoretical amount for reaction with tellurium, and the reaction time was 8 hours to obtain oxidized tellurium slag. The oxidized tellurium slag was then leached, with the total solution to the added tellurium slag liquid-solid ratio controlled at 4:1, the free alkalinity at 40 g / L, the amount of sulfiding reagent added based on the excess of sulfur ions as the endpoint, the reaction time at 1 hour, and the reaction temperature at 95℃ to obtain tellurium leachate. The obtained tellurium leachate was electrodeposited, and electrodeposited tellurium with a purity >99.99% was obtained at the cathode. After casting, 763.56 g of 4N refined tellurium product was produced.

[0044] Example 2

[0045] Take 1 kg of crude tellurium (dry weight), containing 85.9% tellurium, control the liquid-to-solid ratio at 4.5:1, add a certain amount of liquid alkali, adjust the pH to 6, raise the temperature and stir, controlling the temperature at 80℃ and the stirring time at 2 hours. After the reaction is complete, separate the solid and liquid, and send the liquid to wastewater treatment to obtain washed crude tellurium. Washed crude tellurium was mixed evenly with an alkaline auxiliary agent (sodium sulfide) at a ratio of 30:1, spread evenly in an open container, and then transferred to a calcining furnace. The temperature was controlled at 380℃, the oxygen intake was 1 times the theoretical amount for the reaction with tellurium, and the reaction time was 4 hours to obtain tellurium oxide slag. The tellurium oxide slag was then leached, with the total solution to tellurium oxide slag liquid-solid ratio controlled at 3:1, free alkalinity at 20 g / L, the amount of sulfiding reagent added determined by the excess of sulfur ions as the endpoint, the reaction time at 3 hours, and the reaction temperature at 75℃ to obtain tellurium leachate. The obtained tellurium leachate was then electrodeposited, and electrodeposited tellurium with a purity >99.99% was obtained at the cathode. After casting, 817.51 ​​g of 4N refined tellurium product was produced.

[0046] Example 3

[0047] Take 1 kg of crude tellurium (dry weight), containing 90.7% tellurium, control the liquid-to-solid ratio at 6:1, add a certain amount of liquid alkali, adjust the pH to 7, raise the temperature and stir, controlling the temperature at 50℃ and the stirring time at 4 hours. After the reaction is complete, separate the solid and liquid, and send the liquid to wastewater treatment to obtain washed crude tellurium. Washed crude tellurium was mixed with a salt additive (baking soda) at a ratio of 10:1, spread evenly in an open container, and then transferred to a calcining furnace. The temperature was controlled at 300℃, the air intake was 10 times the theoretical amount for the reaction with tellurium, and the reaction time was 12 hours to obtain oxidized tellurium slag. The oxidized tellurium slag was then leached, with the total solution to the added tellurium slag liquid-solid ratio controlled at 4:1, the free alkalinity at 50 g / L, the amount of sulfiding reagent added based on the excess of sulfur ions as the endpoint, the reaction time at 4 hours, and the reaction temperature at 50℃ to obtain tellurium leachate. The obtained tellurium leachate was then electrodeposited, and electrodeposited tellurium with a purity >99.99% was obtained at the cathode. After casting, 887.86 g of 4N refined tellurium product was produced.

[0048] The foregoing has provided a detailed description of a short-process purification technology for crude tellurium from crude tellurium, as provided in the embodiments of this application. The descriptions of the embodiments above are merely illustrative of the methods and core concepts of this application; furthermore, those skilled in the art will recognize that variations in specific implementation methods and application scope may occur based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

[0049] Certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The terms "comprising" and "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising / including but not limited to". "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error. The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of illustrating the general principles of this application and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0050] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0051] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0052] The foregoing description illustrates and describes several preferred embodiments of this application. However, as previously stated, it should be understood that this application is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the application concept described herein through the foregoing teachings or the technology or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this application should be considered in accordance with the appended claims.

Claims

1. A process for purifying tellurium from crude tellurium using a short-process method, characterized in that, The process specifically includes the following steps: S1) First, the coarse tellurium to be treated is washed with water to separate the liquid and solid, resulting in washed coarse tellurium; the specific steps are as follows: First, the crude tellurium is washed with water at a liquid-to-solid ratio of (3-6):1, heated and stirred, while adding alkali to control the final pH to neutral, heated to 50-95℃, and stirred for 1-4 hours. After the reaction is completed, the liquid and solid are separated to obtain the washed crude tellurium. S2) The water-washed crude tellurium obtained in S1) is subjected to pyrometallurgical oxidation treatment to obtain oxidized tellurium slag; The specific steps are as follows: S2.1) The water-washed crude tellurium obtained in S1) is mixed with the auxiliary agent in a certain proportion to obtain a mixture; The auxiliary agent is soda ash, baking soda, sodium sulfide, potassium carbonate or sodium hydroxide; S2.2) The mixture of S2.1) is placed in a pyrometallurgical apparatus, and the gas flow is controlled to heat it to a certain temperature. After the reaction, oxidized tellurium slag is obtained. S3) The oxidized tellurium slag obtained in S2) is subjected to leaching treatment to obtain tellurium leachate; The process parameters are: The liquid-solid ratio of the total leached solution to the added tellurium oxide slag is (3-4):1, the free alkalinity is 20-100 g / L, the amount of sulfiding agent added is based on the excess of sulfur ions as tested by lead acetate test paper, the reaction time is 1-4 h, and the reaction temperature is 50-95 ℃. S4) The tellurium leachate obtained in S3) is subjected to electrowinning and casting processes in sequence to complete the purification of tellurium.

2. The process according to claim 1, characterized in that, The ratio of water-washed crude tellurium to auxiliary agent in S2.1) is (10-50):

1.

3. The process according to claim 1, characterized in that, In step S2.2), the intake air volume is 1 to 10 times the theoretical amount for the reaction with tellurium, the temperature is 300 to 450°C, and the holding time is 4 to 12 hours.

4. The process according to claim 1, characterized in that, The intake air in S2.2) is either air or oxygen.

5. A 4N tellurium, characterized in that, The 4N tellurium is prepared using the process described in any one of claims 1-4.

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