Process for short-process purification of tellurium from crude tellurium

Abstract

The invention discloses a short-flow process for purifying tellurium from crude tellurium, which comprises the following steps: carrying out water washing treatment on crude tellurium to be treated, and carrying out liquid-solid separation to obtain washed crude tellurium; the obtained washed crude tellurium is subjected to pyrogenic oxidation treatment, and tellurium oxide slag is obtained; the obtained tellurium oxide slag is subjected to leaching treatment, and tellurium leaching liquid is obtained; and the obtained tellurium leachate is sequentially subjected to electrodeposition and casting treatment, and tellurium purification is completed. The method has the beneficial effects that the technological process is short, the yield is high, less chemical agents are used, the cost is low, the crude tellurium is converted into the 4N refined tellurium through the mode of combining the pyrogenic process and the wet process, the refined tellurium smelting process is effectively shortened, intermediate products are few, and the tellurium yield can be increased to 95% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of nonferrous metal metallurgy and is a process for purifying tellurium in a short process by taking crude tellurium as a raw material. Background Art

[0002] Tellurium is a rare metal with an abundance of about 1×10 -7 %, mostly associated with pyrite, chalcopyrite, sphalerite, and no independent industrial minerals of tellurium have been found. Tellurium is mainly extracted and prepared from anode mud of electrolytic copper, smoke from zinc smelting, and smelting tailings such as gold, silver, and lead. At present, the methods for separating and purifying tellurium include soda ash roasting, alkaline high-pressure leaching, sulfuric acid roasting, oxidative acid leaching, extraction, electrolytic refining, vacuum distillation, zone melting refining, etc.

[0003] In the prior art, tellurium powder to be purified is added into a vacuum sealed vertical flash furnace in a vacuum state, and then oxygen is introduced to form convection with the tellurium powder to be purified in the sealed vertical flash furnace to produce a gas-solid reaction, and the reaction temperature is controlled to be 320-420° C. This method requires oxygen to be introduced in a vacuum state, and has high safety requirements for the equipment itself.

[0004] In the prior art, crude tellurium is melted and then zone-smelted in a vertical direction, with a melting zone temperature of 460-500°C, a melting zone moving speed of ≤1.0 mm / min, a melting zone width of 0.5-2.0 cm, and a melting frequency of 10-20 times. During the repeated smelting process, impurities escape from the crystallized tellurium zone, so that the crystallized tellurium and the molten impurities are slowly and thoroughly separated, thereby improving the purity of the crystallized tellurium. This method is a zone smelting method, with high temperature and the need to use hydrogen, and has high requirements for the environment and control technology, and is difficult to be truly applied in production.

[0005] The prior art also includes mixing crude tellurium powder with water for rinsing; mixing the rinsing residue with alkaline liquid, charging oxidizing gas, and performing pressurized oxidation alkaline leaching; mixing the alkaline leaching residue with acidic liquid for normal pressure acid leaching, neutralizing the acid leaching liquid with alkali first, and then adding a reducing agent for reduction precipitation; mixing the neutralized residue with the reduction precipitation residue for calcination and impurity removal; mixing the calcined residue with alkaline liquid for alkaline leaching and liquid preparation; and electrolytically refining the alkaline leaching liquid to obtain high-purity tellurium. This process is easy to implement, and the later stage is the same as the electrolytic refining method, but the early stage impurity removal process is relatively long. Summary of the invention

[0006] The present invention discloses a process for purifying tellurium from crude tellurium in a short process, so as to solve any of the above and other potential problems in the prior art.

[0007] In order to solve the above technical problems, the technical solution of the present invention is: a process for purifying tellurium from crude tellurium in a short process, the process specifically comprising the following steps:

[0008] S1) firstly wash the crude tellurium to be treated with water, separate the liquid from the solid, and obtain washed crude tellurium;

[0009] S2) subjecting the washed crude tellurium obtained in S1) to pyro-oxidation treatment to obtain tellurium oxide slag;

[0010] S3) leaching the tellurium oxide slag obtained in S2) to obtain a tellurium leaching solution;

[0011] S4) The tellurium leaching solution obtained in S3) is subjected to electrowinning and casting treatments in sequence, thereby completing the purification of tellurium.

[0012] Further, the specific steps of S1) are:

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

[0014] Further, the specific steps of S2) are:

[0015] S2.1) mixing the washed crude tellurium obtained in S1) with an auxiliary agent in proportion to obtain a mixed material;

[0016] S2.2) The mixed material of S2.1) is placed in a pyrometallurgical equipment, and the air intake is controlled to heat it to a certain temperature, and tellurium oxide slag is obtained after the reaction.

[0017] Furthermore, the ratio of the washed crude tellurium to the 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, the amount of air introduced in S2.2) is 1 to 10 times the theoretical amount for reacting with tellurium, the temperature is 300 to 450° C., and the insulation time is 4 to 12 hours.

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

[0021] Further, the process parameters of S3) are:

[0022] The liquid-to-solid ratio of the total leached solution to the input tellurium oxide slag is (3-4):1, the free alkalinity is 20-100 g / L, the amount of sulfiding agent added is determined by the excess sulfide ion tested by lead acetate test paper as the addition end point, the reaction time is 1-4 hours, and the reaction temperature is 50-95°C.

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

[0024] A 4N tellurium is prepared by using the above process.

[0025] The beneficial effects of the present invention are:

[0026] 1. This process uses a combination of pyrolysis and hydrolysis to purify crude tellurium to more than 99.99%, with a tellurium direct recovery rate of more than 95%;

[0027] 2. The process is short, low in cost, has few intermediate products, is environmentally friendly, and is easily applicable to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention discloses a process flow for purifying tellurium from crude tellurium in a short process. DETAILED DESCRIPTION

[0029] The content of the present invention is further described below in conjunction with the process flow diagram and examples of the present invention.

[0030] The purpose of the present invention is to provide a short-process process for purifying tellurium, which converts crude tellurium into 99.99% refined tellurium through water washing - pyrooxidation - sulfide alkali leaching - electrodeposition - casting. Compared with other processes, this process uses crude tellurium as raw material to purify tellurium, which has a short process flow, low cost, less intermediate products, and is environmentally friendly, and is easy to industrialize.

[0031] The technical solution of the present invention mainly includes the following steps. The process flow chart of the present invention is shown in the attached Figure 1 .

[0032] Step 1. Crude tellurium washing process

[0033] The raw material crude tellurium mainly contains Te, Cu, Se, Pb and a small amount of acid and other impurities. In order to reduce the acid corrosion of the equipment in the later pyrooxidation process and remove some water-soluble impurities, the crude tellurium is first washed with water, the liquid-solid ratio is controlled to (3-6):1, a certain amount of alkali is added, the temperature is raised and stirred, the end point pH is controlled to be neutral, the temperature is (50-95)℃, and the stirring time is (1-4) hours. After the reaction is completed, the liquid and solid are separated to obtain washed crude tellurium.

[0034] Step 2. Fire oxidation process

[0035] The washed crude tellurium obtained in step 1 is added with a salt or alkali auxiliary agent in a certain proportion, mixed evenly, heated and introduced, the temperature is controlled at (300-450)°C, the amount of air introduced is (1-10) times the theoretical amount of tellurium reaction, and the reaction time is (4-12 hours) to obtain tellurium oxide slag;

[0036] Step 3. Tellurium leaching process

[0037] The tellurium oxide slag obtained in step 2 is subjected to sulfide alkali leaching with a controlled input amount and a liquid-to-solid ratio of (3-4) to the total solution, and the free alkalinity is controlled to be (20-100) g / L, the amount of sulfidation reagent added is controlled to be the end point of the addition when the lead acetate test paper tests the excess of sulfide ions, the reaction time is (1-4) h, and the reaction temperature is (50-95) ° C, to obtain a tellurium leaching solution with high tellurium content and low impurities;

[0038] Step 4. Electrodeposition process

[0039] The tellurium leaching solution obtained in step 3 is electrolytically processed to obtain high-purity tellurium.

[0040] Step 5. Casting process

[0041] The electrolytic tellurium obtained in step 4 is cast and impurities are removed to obtain a 99.99% refined tellurium product.

[0042] Embodiment 1:

[0043] Take 1kg of crude tellurium (dry weight), containing 78.88% tellurium, control the liquid-solid ratio to 3:1, add a certain amount of liquid alkali, adjust the pH to 6.5, heat and stir, control the temperature to 95°C, and stir for 1 hour. After the reaction is completed, separate the solid and liquid, and send the liquid to wastewater treatment to obtain washed crude tellurium. The washed crude tellurium and the alkaline auxiliary agent (soda ash) are mixed evenly at a ratio of 50:1, spread into an open container and transferred into a calcining furnace, the temperature is controlled at 450°C, the air intake (air) is introduced at 5 times the theoretical amount of tellurium reaction, the reaction time is 8 hours, and tellurium oxide slag is obtained; the tellurium oxide slag is subjected to leaching treatment, the liquid-solid ratio of the total solution to the added tellurium oxide slag is controlled to be 4:1, the free alkalinity is 40g / L, the amount of sulfiding agent added is the end point of the excess sulfide ion tested by lead acetate test paper, the reaction time is 1h, the reaction temperature is 95°C, and a tellurium leaching solution is obtained; the obtained tellurium leaching solution is subjected to electrolysis, and >99.99 electrolytic tellurium is obtained at the cathode, and then cast to produce 763.56g4N refined tellurium product.

[0044] Example 2

[0045] Take 1kg of crude tellurium (dry weight), containing 85.9% tellurium, control the liquid-solid ratio to 4.5:1, add a certain amount of liquid alkali, adjust the pH to 6, heat and stir, control the temperature to 80°C, and stir for 2 hours. After the reaction is completed, separate the solid and liquid, and send the liquid to wastewater treatment to obtain washed crude tellurium. The washed crude tellurium and the alkali auxiliary agent (sodium sulfide) are mixed evenly at a ratio of 30:1, spread into an open container and transferred into a calcining furnace, the temperature is controlled at 380°C, the air intake (oxygen) is introduced at 1 times the theoretical amount of the tellurium reaction, the reaction time is 4 hours, and tellurium oxide slag is obtained; the tellurium oxide slag is subjected to leaching treatment, the liquid-solid ratio of the total solution to the added tellurium oxide slag is controlled to be 3:1, the free alkalinity is 20g / L, the amount of sulfiding agent added is the end point of the excess sulfide ion tested by lead acetate test paper, the reaction time is 3h, the reaction temperature is 75°C, and a tellurium leaching solution is obtained; the obtained tellurium leaching solution is subjected to electrolysis, and >99.99 electrolytic tellurium is obtained at the cathode, and then cast to produce 817.51g4N refined tellurium product.

[0046] Example 3

[0047] Take 1kg of crude tellurium (dry weight), containing 90.7% tellurium, control the liquid-solid ratio to 6:1, add a certain amount of liquid alkali, adjust the pH to 7, heat and stir, control the temperature to 50°C, and stir for 4 hours. After the reaction is completed, separate the solid and liquid, and send the liquid to wastewater treatment to obtain washed crude tellurium. The washed crude tellurium and the salt auxiliary agent (baking soda) are mixed evenly in a ratio of 10:1, spread into an open container and transferred into a calcining furnace, the temperature is controlled at 300°C, the air intake (air) is introduced at 10 times the theoretical amount of the tellurium reaction, the reaction time is 12 hours, and tellurium oxide slag is obtained; the tellurium oxide slag is subjected to leaching treatment, the liquid-solid ratio of the total solution to the added tellurium oxide slag is controlled to be 4:1, the free alkalinity is 50g / L, the amount of sulfiding agent added is the end point of the excess sulfide ion tested by lead acetate test paper, the reaction time is 4h, and the reaction temperature is 50°C to obtain a tellurium leaching solution; the obtained tellurium leaching solution is subjected to electrolysis to obtain >99.99 electrolytic tellurium at the cathode, and then cast to produce 887.86g4N refined tellurium product.

[0048] The above is a detailed introduction to a short-process process for purifying tellurium from crude tellurium provided in the embodiment of the present application. The description of the above embodiment is only used to help understand the method and core idea of ​​the present application; at the same time, for those skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as limiting the present application.

[0049] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different nouns to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. As mentioned throughout the specification and claims, "including" and "comprising" are open-ended terms, so they should be interpreted as "including / including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. The subsequent description of the specification is a preferred embodiment of the present application, but the description is for the purpose of illustrating the general principles of the present application, and is not used to limit the scope of the present application. The scope of protection of the present application shall be subject to that defined in the attached claims.

[0050] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a product or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such a product or system. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the product or system including the elements.

[0051] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0052] The above description shows and describes several preferred embodiments of the present application, but as mentioned above, it should be understood that the present application is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present application, and should be included in the claims attached to the present application.

Claims

1. A process for purifying tellurium from crude tellurium in a short process, characterized in that: The process specifically comprises the following steps: S1) firstly wash the crude tellurium to be treated with water, separate the liquid from the solid, and obtain washed crude tellurium; S2) subjecting the washed crude tellurium obtained in S1) to pyro-oxidation treatment to obtain tellurium oxide slag; S3) leaching the tellurium oxide slag obtained in S2) to obtain a tellurium leaching solution; S4) The tellurium leaching solution obtained in S3) is subjected to electrowinning and casting treatments in sequence, thereby completing the purification of tellurium.

2. The process according to claim 1, characterized in that The specific steps of S1) are: First, the crude tellurium is washed with water according to a liquid-solid ratio of (3-6):1, heated and stirred, and alkali is added to control the end point pH to neutral, the temperature is raised to 50-95°C, and the stirring time is 1-4 hours. After the reaction is completed, the liquid and solid are separated to obtain washed crude tellurium.

3. The process according to claim 1, characterized in that The specific steps of S2) are: S2.1) mixing the washed crude tellurium obtained in S1) with an auxiliary agent in proportion to obtain a mixed material; S2.2) The mixed material of S2.1) is placed in a pyrometallurgical equipment, and the air intake is controlled to heat it to a certain temperature, and tellurium oxide slag is obtained after the reaction.

4. The process according to claim 3, characterized in that The ratio of the washed crude tellurium to the auxiliary agent in S2.1) is: (10-50):

1.

5. The process according to claim 3, characterized in that The auxiliary agent in S2.1) is soda ash, baking soda, sodium sulfide, potassium carbonate or sodium hydroxide.

6. The process according to claim 3, characterized in that The amount of air introduced in S2.2) is 1 to 10 times the theoretical amount for reacting with tellurium, the temperature is 300 to 450°C, and the insulation time is 4 to 12 hours.

7. The process according to claim 3, characterized in that The intake gas in S2.2) is air or oxygen.

8. The process according to claim 1, characterized in that The process parameters of S3) are: The liquid-to-solid ratio of the total leached solution to the input tellurium oxide slag is (3-4):1, the free alkalinity is 20-100 g / L, the amount of sulfiding agent added is determined by the excess sulfide ion tested by lead acetate test paper as the addition end point, the reaction time is 1-4 hours, and the reaction temperature is 50-95°C.

9. The process according to claim 1, characterized in that In the process, the selenium removal rate is not less than 95%; and the tellurium direct recovery rate is more than 95%.

10. A 4N tellurium, characterized in that: The 4N tellurium is prepared by the process described in any one of claims 1 to 9.

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