Method for removing impurity tellurium from crude selenium

Abstract

The application provides a method for removing impurity tellurium from crude selenium, and relates to the field of dispersed metal purification technology. Crude selenium raw material is heated and melted, Na2CO3 is added into the obtained melt, an oxidizing gas containing oxygen is introduced, oxidizing slagging smelting is carried out, and a slag-containing selenium melt is obtained; the slag-containing selenium melt is filtered. In the oxidizing slagging smelting process, a small amount of Se is oxidized into SeO2 by O2, SeO2 has weak oxidizing property and can oxidize Te into TeO2, Na2CO3 reacts with TeO2 to generate Na2TeO4 slag, and the slag is removed through melt filtration.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of purification of dispersed metals, and particularly relates to a method for removing impurity tellurium from crude selenium. BACKGROUND

[0002] Selenium is a dispersed metal, which is widely used in metallurgy, materials, chemical industry, medical treatment and other fields, and is a key material supporting the development of high technology and the development of new materials. Selenium is mainly recovered from copper anode slime. In the process of copper anode slime oxidation roasting, SeO2smoke gas forms selenious acid solution in the absorption tower, and is reduced and precipitated as crude selenium powder by SO2 in the smoke gas. The crude selenium powder needs to be subjected to preliminary purification treatment to obtain industrial-grade selenium product. For some crude selenium raw materials, the impurity tellurium mainly exists in the form of elemental state and is infinitely soluble with selenium, and it is difficult to achieve ideal removal effect through ordinary oxidation and vacuum distillation.

[0003] CN106946233A discloses a method for vacuum refining and purifying crude selenium. The crude selenium material can produce 99.9% industrial-grade selenium after the processes of melting, degassing and vacuum distillation. In this method, the melting, degassing and distillation temperatures are 230-350℃, 250-400℃ and 500-1000℃ respectively, the vacuum degree is 1-20Pa, and the distillation time is 3-4h. The selenium product obtained by using this treatment method on the crude selenium material with selenium-tellurium mutual solubility has almost no change in the content of impurity tellurium.

[0004] CN112357893A discloses a method for purifying crude selenium by melting and filtering. The crude selenium raw material is heated and melted at 300-550℃, and then the obtained melt is filtered through a filter with a mesh size of 30-500 meshes. This method can obtain industrial-grade selenium with a purity of about 99%. The treatment method has almost no effect on the removal of impurity tellurium when used on the crude selenium material with selenium-tellurium mutual solubility. SUMMARY

[0005] The present application aims to provide a method for removing impurity tellurium from crude selenium, which can efficiently remove the impurity tellurium in the crude selenium and is simple.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0007] The present application provides a method for removing impurity tellurium from crude selenium, which comprises the following steps:

[0008] The crude selenium raw material is heated and melted, Na2CO3 is added to the obtained melt, an oxidizing gas containing oxygen is introduced, and oxidation slagging smelting is performed to obtain a slag-containing selenium melt. The slag-containing selenium melt is filtered.

[0009] Preferably, the content of Te in the crude selenium raw material is 0.5-10% by mass percentage.

[0010] Preferably, the heating melting temperature is 300-500℃.

[0011] Preferably, the oxidizing gas comprises air or oxygen.

[0012] Preferably, when the oxidizing gas is air, the air flow rate is 0.5-10 L / min; when the oxidizing gas is oxygen, the oxygen flow rate is 0.5-5 L / min; the aeration time of the oxidizing gas is 5-30 min.

[0013] Preferably, the molar ratio of Na2CO3 to Te in the raw selenium is (0.3-1.5):1.

[0014] Preferably, the oxidizing slagging smelting temperature is 250-400℃, and the time is 1-3 h.

[0015] Preferably, the filtering temperature is 300-400℃.

[0016] Preferably, the oxidizing slagging smelting is carried out under stirring.

[0017] Preferably, the stirring rate is 100-300 r / min.

[0018] The present application provides a method for removing impurity tellurium from raw selenium, comprising the following steps: heating and melting raw selenium, adding Na2CO3 to the obtained melt, introducing an oxidizing gas containing oxygen, carrying out oxidizing slagging smelting to obtain a slag-containing selenium melt, and filtering the slag-containing selenium melt. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The analysis report of examples and comparative examples is provided. DETAILED DESCRIPTION

[0020] The present application provides a method for removing impurity tellurium from raw selenium, comprising the following steps:

[0021] The present application provides a method for removing impurity tellurium from raw selenium, comprising the following steps:

[0022] In the present application, unless otherwise specified, the raw materials used are commercially available products well known in the art.

[0023] The crude selenium raw material is heated and melted in the present application.

[0024] In the present application, the content of Te in the crude selenium raw material is preferably 0.5-10% by mass, more preferably 1-8%, and further preferably 3-5%. In the present application, the tellurium in the crude selenium raw material exists in the form of simple substance and is infinitely soluble with selenium. In the present application, the temperature of the heating and melting is preferably 300-500°C, more preferably 350-450°C, and further preferably 380-420°C. In the present application, the heating and melting is preferably performed in an electric resistance furnace.

[0025] After the temperature of the heating and melting is reached, Na2CO3 is added to the obtained melt, an oxidizing gas containing oxygen is introduced, and oxidizing slagging smelting is performed to obtain a slag-containing selenium melt.

[0026] In the present application, the oxidizing gas preferably includes air or oxygen; when the oxidizing gas is air, the flow rate of the air is preferably 0.5-10 L / min, more preferably 1-8 L / min, and further preferably 3-6 L / min; and when the oxidizing gas is oxygen, the flow rate of the oxygen is preferably 0.5-5 L / min, more preferably 1-4 L / min, and further preferably 2-3 L / min. In the present application, the time for which the oxidizing gas is introduced is preferably 5-30 min, more preferably 10-25 min, and further preferably 15-20 min.

[0027] In the present application, the addition of Na2CO3 and the introduction of the oxidizing gas containing oxygen are preferably performed under stirring.

[0028] In the present application, the temperature of the oxidizing slagging smelting is preferably 250-400°C, and more preferably 300-350°C; and the time is preferably 1-3 h. In the present application, the time of the oxidizing slagging smelting refers to the time from the start of the introduction of the oxidizing gas. In the present application, the increase in the amount of slag is preferably observed within the above time range.

[0029] In the present application, the oxidizing slagging smelting is preferably performed under stirring, and the rate of the stirring is preferably 100-300 r / min. In the present application, a small amount of Se is oxidized to SeO2 by O2 during the oxidizing slagging smelting, and SeO2 has weak oxidizing property and can oxidize Te to TeO2, and Na2CO3 reacts with TeO2 to generate Na2TeO4 slag.

[0030] After obtaining the slag-containing selenium melt, the slag-containing selenium melt is filtered in the present application. The temperature of the filtering is preferably 300-400°C, more preferably 320-360°C in the present application. The present application does not have special requirements for the filtering, and a filtering process well known in the art can be used. In the embodiment of the present application, the filtering is specifically performed using a 100-mesh screen, and the filtering furnace temperature is 320°C.

[0031] The method for removing the impurity tellurium from the crude selenium provided by the present application is described in detail below in combination with the embodiments, but they should not be understood as limiting the protection scope of the present application.

[0032] Example 1

[0033] 100 g of crude selenium raw material containing 3.3% of Te (the impurity tellurium exists in the form of an element) is weighed in a crucible and placed in a resistance furnace for heating and melting. When the temperature of the melt reaches 300°C, 2.75 g of Na2CO3 is added to the melt, the molar ratio of Na2CO3 to Te in the crude selenium raw material is 1:1, air is then introduced into the melt (the flow rate is 0.6 L / min, and the introduction time is 20 min) to perform oxidation slagging smelting, the smelting temperature is 310°C, the smelting time is 1 h, and the stirring speed is 100 r / min, thereby obtaining a slag-containing selenium melt. The obtained slag-containing selenium melt is then filtered at 320°C under a 100-mesh screen, and finally a selenium product with a certain purity is obtained in the filtrate, and an enriched tellurium is obtained in the filter residue. The content of tellurium in the selenium product is 0.093% (see analysis report 2023.7.11#) by ICP-AES quantitative analysis, the content of tellurium in the slag is 9.92% (see analysis report 2#), and the removal rate of tellurium in the crude selenium is 97.18%.

[0034] Example 2

[0035] 100 g of crude selenium raw material containing 3.3% of Te (the impurity tellurium exists in the form of an element) is weighed in a crucible and placed in a resistance furnace for heating and melting. When the temperature of the melt reaches 300°C, 2.75 g of Na2CO3 is added to the melt, the molar ratio of Na2CO3 to Te in the crude selenium raw material is 1:1, air is then introduced into the melt (the flow rate is 1.0 L / min, and the introduction time is 12 min) to perform oxidation slagging smelting, the smelting temperature is 310°C, the smelting time is 2 h, and the stirring speed is 100 r / min, thereby obtaining a slag-containing selenium melt. The obtained slag-containing selenium melt is then filtered at 320°C under a 100-mesh screen, and finally a selenium product with a certain purity is obtained in the filtrate, and an enriched tellurium is obtained in the filter residue. The content of tellurium in the selenium product is 0.070% (see analysis report 2023.7.12#) by ICP-AES quantitative analysis, the content of tellurium in the slag is 10.32% (see analysis report 3#), and the removal rate of tellurium in the crude selenium is 97.88%.

[0036] Example 3

[0037] Take 100 g of crude selenium raw material containing Te 3.3% (impurity tellurium exists in the form of elemental) in a crucible, and place it in a resistance furnace for heating and melting. When the melt temperature reaches 300°C, add 2.75 g of Na2CO3 to it, with a molar ratio of Na2CO3 to Te in the crude selenium raw material of 1:1. Then introduce air into it (flow rate of 1.5 L / min, for 8 min) to perform oxidation and slagging smelting. The smelting temperature is 340°C, the smelting time is 1 h, and the stirring speed is 100 r / min. A selenium melt containing slag is obtained. Then the obtained selenium melt containing slag is filtered at 320°C under a 100 mesh screen. Finally, a selenium product with a certain purity is obtained in the filtrate, and a tellurium concentrate is obtained in the filter residue. The content of tellurium in the selenium product is 0.63% (see analysis report 2023.7.13#) by ICP-AES quantitative analysis, the content of tellurium in the slag is 8.37% (see analysis report 1#), and the removal rate of tellurium in the crude selenium is 80.91%.

[0038] Example 4

[0039] Take 100 g of crude selenium raw material containing Te 3.3% (impurity tellurium exists in the form of elemental) in a crucible, and place it in a resistance furnace for heating and melting. When the melt temperature reaches 300°C, add 2.75 g of Na2CO3 to it, with a molar ratio of Na2CO3 to Te in the crude selenium raw material of 1:1. Then introduce air into it (flow rate of 1.5 L / min, for 8 min) to perform oxidation and slagging smelting. The smelting temperature is 340°C, the smelting time is 1 h, and the stirring speed is 100 r / min. A selenium melt containing slag is obtained. Then the obtained selenium melt containing slag is filtered at 320°C under a 100 mesh screen. Finally, a selenium product with a certain purity is obtained in the filtrate, and a tellurium concentrate is obtained in the filter residue. The content of tellurium in the selenium product is 0.055% (see analysis report 2023.7.14#) by ICP-AES quantitative analysis, the content of tellurium in the slag is 11.10% (see analysis report 5#), and the removal rate of tellurium in the crude selenium is 98.33%.

[0040] Example 5

[0041] Take 100 g of crude selenium raw material containing 3.3% Te (impurity tellurium exists in the form of elemental substance) in a crucible, and place it in a resistance furnace for heating and melting. When the melt temperature reaches 300°C, add 1.375 g of Na2CO3 to it, and the molar ratio of Na2CO3 to Te in the crude selenium raw material is 0.5:1. Then, air is introduced into it (flow rate is 1.0 L / min, and the introduction time is 12 min) to perform oxidation and slagging smelting. The smelting temperature is 320°C, the smelting time is 1 h, the stirring speed is 100 r / min, and a selenium melt containing slag is obtained. Then, the obtained selenium melt containing slag is filtered at 320°C under a 100-mesh screen. Finally, a selenium product with a certain purity is obtained in the filtrate, and a tellurium concentrate is obtained in the filter residue. The content of tellurium element in the selenium product is 0.10% (see analysis report 2023.7.15#) by ICP-AES quantitative analysis, the content of tellurium in the slag is 9.12% (see analysis report 4#), and the removal rate of tellurium in the crude selenium is 96.97%.

[0042] Comparative Example 1

[0043] Take 100 g of crude selenium raw material containing 3.3% Te (impurity tellurium exists in the form of elemental substance) in a crucible, and place it in a resistance furnace for heating and melting. When the melt temperature reaches 320°C, the melt is filtered under a 100-mesh screen. The content of tellurium element in the selenium product (filtrate) is 3.64% (see analysis report 6#) by ICP-AES quantitative analysis.

[0044] The above only describes the preferred embodiments of the present application. It should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A method for removing tellurium impurities from crude selenium, characterized in that, Includes the following steps: The crude selenium raw material is heated and melted, Na2CO3 is added to the resulting melt, and an oxidizing gas containing oxygen is introduced to carry out oxidative slag-forming smelting to obtain a slag-containing selenium melt; the slag-containing selenium melt is then filtered. The heating and melting temperature is 300~500℃; The oxidation slag smelting temperature is 250~400℃, and the time is 1~3h; The filtration temperature is 300~400℃.

2. The method according to claim 1, characterized in that, The Te content in the crude selenium raw material is 0.5-10% by mass percentage.

3. The method according to claim 1, characterized in that, The oxidizing gas includes air or oxygen.

4. The method according to claim 3, characterized in that, When the oxidizing gas is air, the air flow rate is 0.5~10L / min; when the oxidizing gas is oxygen, the oxygen flow rate is 0.5~5L / min; and the oxidizing gas ventilation time is 5~30min.

5. The method according to claim 1, characterized in that, The molar ratio of Na2CO3 to Te in the crude selenium raw material is (0.3~1.5):

1.

6. The method according to claim 1, characterized in that, The oxidation slag smelting is carried out under stirring conditions.

7. The method according to claim 6, characterized in that, The stirring rate is 100~300 r / min.

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