Method for removing impurity selenium in crude tellurium

Abstract

The invention discloses a method for removing impurity selenium in crude tellurium, and belongs to the technical field of scattered metal refining. The removal method comprises the following steps: placing crude tellurium in a distillation container, and placing an adsorption layer on the upper part of the distillation container. And then placing the distillation container and the adsorption layer in a vacuum furnace for vacuum distillation. Selenium is enriched in the adsorption layer, separation is achieved, and refined and purified fine tellurium is obtained. According to the method, under the vacuum condition, selenium steam easily reacts with a mixture of aluminum oxide and a carbon reducing agent to generate an aluminum selenide solid, tellurium steam does not react and penetrates through an adsorption layer to be condensed in a condensation area, and the purpose of removing impurity selenium in crude tellurium is achieved. According to the method, the removal efficiency of the impurity selenium in the process of vacuum distillation and purification of the crude tellurium is effectively improved, the process is short, cleanliness and high efficiency are achieved, the problems that a chemical method is long in process, high in reagent consumption and repeated in tellurium valence change are solved, and the selenium content in refined tellurium obtained through refining and purification is smaller than or equal to 1 ppm.

Description

Technical Field

[0001] The invention belongs to the technical field of rare metal refining, and in particular relates to a method for removing impurity selenium in crude tellurium. Background Art

[0002] Rare metal tellurium is an indispensable key metal for the development of modern high-tech. With the increasing demand for high-purity tellurium in emerging fields, tellurium has become a key material to support the development of high-tech. Copper anode mud is the main source of selenium and tellurium, which leads to selenium being the most common impurity in crude tellurium and is difficult to remove. Breaking through the separation of selenium and tellurium is the core and key to achieving crude tellurium purification. Chemical separation of selenium and tellurium has problems such as long process flow, high reagent consumption, and high environmental pressure. Vacuum distillation is one of the most commonly used methods for preparing high-purity tellurium. Since selenium and tellurium belong to the same group of elements and have similar physical properties, the existing vacuum distillation purification method is difficult to achieve efficient removal of impurity selenium and has low adaptability to raw materials. Crude tellurium materials with high selenium content still need to be further treated by chemical methods, with repeated oxidation-reduction of components, long process flow, and high environmental pressure. How to achieve efficient removal of impurity selenium in the vacuum distillation process of crude tellurium has become a common demand of rare metal smelting enterprises, and it is urgent to develop new technologies for crude tellurium purification that are clean, efficient, and widely adaptable. Summary of the invention

[0003] The object of the present invention is to provide a method for removing selenium as an impurity in crude tellurium.

[0004] The object of the present invention is achieved in this way: the method for removing selenium impurities in crude tellurium comprises the following steps: The crude tellurium is placed in a distillation container, and an adsorption layer is placed on the top of the distillation container; the distillation container and the adsorption layer are placed in a vacuum furnace for vacuum distillation; selenium is enriched in the adsorption layer, and separation is achieved to obtain refined and purified tellurium.

[0005] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: The technical solution utilizes the fact that under vacuum conditions, selenium vapor easily reacts with a mixture of aluminum oxide and a carbon reducing agent to generate aluminum selenide solid, while tellurium vapor does not react, passes through the adsorption layer and condenses in the condensation zone, thereby achieving the purpose of removing the impurity selenium in the crude tellurium.

[0006] Compared with the traditional process that only relies on the difference in condensation temperature of selenium and tellurium to achieve separation, the present invention adopts a method of enhanced separation of selenium by chemical adsorption under vacuum, which effectively improves the removal efficiency of impurity selenium in the process of vacuum distillation purification of crude tellurium. The process is short, clean and efficient, avoiding the problems of long chemical process, high reagent consumption and repeated tellurium price changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a schematic diagram of the principle of the technical solution of the present invention; In the figure; 1- condenser, 2- vacuum furnace heating zone, 3- adsorption layer, 4- distillation container. DETAILED DESCRIPTION

[0008] The present invention is further described below, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention belong to the protection scope of the present invention.

[0009] The method for removing selenium impurities from crude tellurium comprises the following steps: The crude tellurium is placed in a distillation container, and an adsorption layer is placed on the top of the distillation container; the distillation container and the adsorption layer are placed in a vacuum furnace for vacuum distillation; selenium is enriched in the adsorption layer, and separation is achieved to obtain refined and purified tellurium.

[0010] The selenium content in the crude tellurium is ≥20ppm.

[0011] The distillation container is a crucible, preferably a high-purity quartz crucible or a high-purity graphite crucible.

[0012] The adsorption layer uses an aluminum mesh as a framework, on which is laid a mixture of aluminum oxide and a carbon reducing agent in a mass ratio of 1: (1-10).

[0013] The carbon reducing agent is any one or more of charcoal, activated carbon, petroleum coke and flour.

[0014] The height of the heating zone of the vacuum furnace needs to exceed the height of the distillation container plus the upper adsorption layer.

[0015] The vacuum distillation temperature is 500-700°C, the pressure is 2-10 Pa, and the time is 0.5-5 h. Furthermore, the preferred temperature is 450-650°C, the pressure is 5-7 Pa, and the time is 1-2 h.

[0016] The selenium content in the refined tellurium is ≤1ppm.

[0017] Example 1 The selenium content in the crude tellurium described in this embodiment is 20 ppm.

[0018] The crude tellurium is placed in a high-purity quartz crucible, an aluminum mesh is placed on the top of the crucible, and a mixture of aluminum oxide and charcoal in a mass ratio of 1:1 is laid on it as an adsorption layer. The crucible containing the crude tellurium and the adsorption layer on it are placed in a vacuum furnace and distilled for 1 to 2 hours at a temperature of 450~650℃ and a pressure of 5~7Pa. Selenium is enriched in the adsorption layer and separated. The selenium content in the obtained refined tellurium is 0.1ppm.

[0019] Example 2 The selenium content in the crude tellurium described in this embodiment is 20 ppm.

[0020] The crude tellurium is placed in a high-purity graphite crucible, an aluminum mesh is placed on the top of the crucible, and a mixture of aluminum oxide and activated carbon in a mass ratio of 1:0.5 is laid on it as an adsorption layer. The crucible containing the crude tellurium and the adsorption layer on it are placed in a vacuum furnace and distilled for 1 to 2 hours at a temperature of 450 to 650°C and a pressure of 5 to 7 Pa. Selenium is enriched in the adsorption layer and separated. The selenium content in the obtained refined tellurium is 0.2ppm.

[0021] Example 3 The selenium content in the crude tellurium described in this embodiment is 30 ppm.

[0022] The crude tellurium is placed in a high-purity quartz crucible, an aluminum mesh is placed on the top of the crucible, and a mixture of aluminum oxide and petroleum coke in a mass ratio of 1:2 is laid on it as an adsorption layer. The crucible containing the crude tellurium and the adsorption layer on it are placed in a vacuum furnace and distilled for 1 to 2 hours at a temperature of 450 to 650°C and a pressure of 5 to 7 Pa. Selenium is enriched in the adsorption layer and separated. The selenium content in the obtained refined tellurium is 0.1ppm.

Claims

1. A method for removing selenium impurities from crude tellurium, characterized in that Including the following processes: The crude tellurium is placed in a distillation container, and an adsorption layer is placed on the top of the distillation container; the distillation container and the adsorption layer are placed in a vacuum furnace for vacuum distillation; selenium is enriched in the adsorption layer, and separation is achieved to obtain refined and purified tellurium.

2. The removal method according to claim 1, characterized in that The selenium content in the crude tellurium is ≥20ppm.

3. The removal method according to claim 1, characterized in that The distillation container is a high-purity quartz crucible or a high-purity graphite crucible.

4. The removal method according to claim 1, characterized in that The adsorption layer uses an aluminum mesh as a framework, on which is laid a mixture of aluminum oxide and a carbon reducing agent in a mass ratio of 1: (1-10).

5. The removal method according to claim 4, characterized in that The carbon reducing agent is any one or more of charcoal, activated carbon, petroleum coke and flour.

6. The removal method according to claim 1, characterized in that The height of the heating zone of the vacuum furnace needs to exceed the height of the distillation container plus the upper adsorption layer.

7. The removal method according to claim 1, characterized in that The vacuum distillation temperature is 500-700° C., the pressure is 2-10 Pa, and the time is 0.5-5 h.

8. The removal method according to claim 7, characterized in that The vacuum distillation temperature is 450-650° C., the pressure is 5-7 Pa, and the time is 1-2 h.

9. The removal method according to claim 1, characterized in that The selenium content in the refined tellurium is ≤1ppm.

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