A method for removing selenium from a material containing selenium and tellurium to produce high-purity tellurium dioxide

Abstract

The application provides a method for removing selenium from a selenium-tellurium-containing material to prepare high-purity tellurium dioxide, and specific steps are as follows: S1, crushing tellurium residue containing Na2TeO3 produced by lead anode slime, and adding sodium sulfide to remove impurities lead after alkali leaching, pressure filtration, and neutralizing the filtrate to obtain crude tellurium dioxide; S2, putting the crude tellurium dioxide into an acid leaching tank, adding deionized water and hydrochloric acid in sequence to perform acid dissolution reaction, and obtaining a mixed solution; S3, adding sodium chlorate to the mixed solution to adjust the potential to 600-900 mV, adding sodium sulfite to react until the Se in the mixed solution is lower than 50 mg / L, and performing pressure filtration to obtain a filtrate; and S4, adding the filtrate into flake alkali to obtain tellurium dioxide. The method is beneficial to improving the Se removal efficiency of subsequent sodium sulfite, avoiding the loss of tellurium, providing a basis for subsequent electrodeposition of large current, greatly improving the electrodeposition efficiency, shortening the production cycle, significantly improving the yield and quality of tellurium ingot products, reducing the production cost, and being good in process stability.

Description

TECHNICAL FIELD

[0001] The present application relates to tellurium electro-deposition refining technical field, and particularly relates to a method for removing selenium from selenium-containing tellurium material to prepare high-purity tellurium dioxide. BACKGROUND

[0002] The production process of national standard tellurium ingot is to obtain crude tellurium by electro-deposition with sodium tellurite solution and to obtain national standard tellurium ingot by refining, and the sodium tellurite solution is prepared by reacting tellurium dioxide with sodium hydroxide solution. In order to obtain qualified sodium tellurite solution, qualified tellurium dioxide is needed.

[0003] Tellurium is a rare metal and is widely used in the industrial field. Tellurium is generally recovered from copper smelting anode slime, and the recovery process mainly includes alkali leaching, purification, neutralization, preparation of electrolyte and insoluble anode electro-deposition. In the process of tellurium electro-deposition refining, part of impurities such as selenium in the tellurium-containing material enters the alkali leaching solution with the chemical dissolution of alkali leaching. With the production, the selenium in the alkali leaching solution is continuously enriched, and it is difficult to separate from tellurium dioxide in the hydrolysis process, thereby entering the electro-deposition solution, which brings high selenium impurities to the production of tellurium and affects the quality of tellurium.

[0004] In order to make the impurity content of tellurium product less than the lower limit, it is necessary to remove selenium and impurities from the alkali leaching solution to ensure the normal operation of the electro-deposition process. In the prior art, the traditional process flow for preparing tellurium dioxide by alkali leaching and removing selenium from selenium-containing tellurium material is: selenium-containing tellurium material→alkali leaching and tellurium separation→hydrolysis and tellurium precipitation→calcination and selenium removal→tellurium dioxide. That is, by using the principle of low boiling point of selenium dioxide, selenium dioxide is volatilized by calcination in a calcination furnace to purify tellurium dioxide. However, this process not only causes loss of tellurium in the calcination process, but also has low selenium removal efficiency, resulting in high processing cost and affecting the competitiveness of enterprises. SUMMARY

[0005] Therefore, the present application provides a method for removing selenium from selenium-containing tellurium material to prepare high-purity tellurium dioxide.

[0006] The technical scheme of the present application is as follows:

[0007] A method for removing selenium from selenium-containing tellurium material to prepare high-purity tellurium dioxide, the specific steps comprising:

[0008] S1, crushing the tellurium residue containing Na2TeO3 produced by lead anode slime, and the filtrate after alkali leaching enters the purification process, sodium sulfide is added to remove impurities lead, pressure filtration, and the filtrate is neutralized to obtain crude tellurium dioxide;

[0009] S2, putting the crude tellurium dioxide into an acid leaching tank, adding deionized water and hydrochloric acid in sequence to carry out acid dissolution reaction, and obtaining a mixed solution;

[0010] The mass ratio of the crude tellurium dioxide to deionized water and hydrochloric acid is 1:1-3:3-5.

[0011] S3, adding sodium chlorate to the mixed solution to adjust the potential to 600-900 mV, then adding sodium sulfite to react, pressure filtration, to obtain a filtrate;

[0012] S4, adding the filtrate of S3 to flake caustic to obtain a target tellurium dioxide product.

[0013] Further, in step S1, the added amount of sodium sulfide is 0.5-5 times of the lead content in the filtrate.

[0014] Further, in step S2, the concentration of the hydrochloric acid is 1-10 mol / L.

[0015] Further, in step S2, the temperature of the acid dissolution reaction is 60-80℃, and the time is 0.5-5h.

[0016] Further, in step S3, the added amount of sodium sulfite is 3-5 times of the selenium content in the mixed solution.

[0017] Further, in step S3, the reaction is ended until the Se in the mixed solution is less than 50 mg / L.

[0018] Further, in step S4, the flake caustic is added to adjust the pH of the system to 5.0-6.5.

[0019] Further, the obtained tellurium dioxide product is used for subsequent preparation of high-quality tellurium ingot.

[0020] Compared with the prior art, the beneficial effects of the present application are:

[0021] 1. The present application processes the crude tellurium dioxide by limiting the added amount of acid dissolution and adjusting the potential of the chemical reaction method, which is beneficial to improve the subsequent sodium sulfite removal Se efficiency, avoids the loss of tellurium in the traditional calcination selenium removal process, provides a basis for subsequent electrodeposition of large current, greatly improves the electrodeposition efficiency, shortens the production cycle, significantly improves the yield and quality of tellurium ingot product, reduces the production cost, and has good process stability.

[0022] 2. The tellurium recovery rate of the tellurium dioxide product obtained by the method of the present application is as high as 99%, the content of impurity selenium is less than 0.01%, and the purity of the tellurium ingot prepared by subsequent solution making, electrodeposition and casting reaches more than 99.99%. DETAILED DESCRIPTION

[0023] In order to better understand the technical content of the present application, the following specific examples are provided to further illustrate the present application.

[0024] The experimental methods used in the embodiments of the present application are conventional methods unless otherwise specified.

[0025] The materials, reagents and the like used in the embodiments of the present application can be obtained from commercial channels unless otherwise specified.

[0026] A method for removing selenium from a selenium-tellurium-containing material to prepare high-purity tellurium dioxide, the main components of the selenium-tellurium-containing material are Na2TeO3 and soluble selenium and other impurities, and the content of Na2TeO3 in the selenium-tellurium-containing material is generally 15-25%, and the content of selenium is 1-5%.

[0027] Example 1

[0028] S1, 600g of tellurium slag was crushed, and the specific components were shown in Table 1. The crushed tellurium slag and 1200mL of alkali solution were mixed to form a filtrate. Sodium sulfide was added to the filtrate, and the amount of sodium sulfide added was 0.5 times the content of lead in the filtrate. Impurity lead was removed, pressure filtration was performed, and the filtrate was neutralized to obtain crude tellurium dioxide;

[0029] Table 1

[0030] Composition Te Bi Cu Sb Pb Se Content 22.56％ 9.72％ 1.12％ 6.06％ 10.55％ 2.90％

[0031] S2, the crude tellurium dioxide was put into an acid leaching tank, deionized water and hydrochloric acid with a concentration of 10mol / L were added in sequence, and the mass ratio of the crude tellurium dioxide to the deionized water and the hydrochloric acid was 1:2:4. Acid dissolution reaction was carried out at 70℃ for 1h to obtain a mixed solution;

[0032] S3, sodium chlorate was added to the mixed solution to adjust the potential to 800mV, and then sodium sulfite was added. The amount of sodium sulfite added was 4 times the content of selenium in the mixed solution. Reaction was carried out until the Se in the mixed solution was lower than 50mg / L. Pressure filtration was performed to obtain a filtrate;

[0033] S4, the filtrate of S3 was added to flake alkali, and the pH of the system was adjusted to 5.5±0.1 to obtain a target tellurium dioxide product. The components were shown in Table 2.

[0034] Table 2

[0035] Composition Te Bi Cu Sb Pb Se Content 72.5200％ 0.0011％ 0.0070％ 0.0010％ 0.0120％ 0.0094％

[0036] Example 2

[0037] S1, 600g of tellurium slag was crushed, and the specific components were shown in Table 3. The crushed tellurium slag and 900mL of alkali solution were mixed to form a filtrate. Sodium sulfide was added to the filtrate, and the amount of sodium sulfide added was 1.5 times the content of lead in the filtrate. Impurity lead was removed, pressure filtration was performed, and the filtrate was neutralized to obtain crude tellurium dioxide;

[0038] Table 3

[0039] Composition Te Bi Cu Sb Pb Se Content 18.65％ 10.48％ 1.94％ 4.95％ 11.85％ 3.60％

[0040] S2, the crude tellurium dioxide is put into an acid leaching tank, deionized water and hydrochloric acid with a concentration of 5 mol / L are sequentially added, the mass ratio of the crude tellurium dioxide, the deionized water and the hydrochloric acid is 1:1:3, acid dissolution reaction is carried out at 60 DEG C for 2h, and a mixed solution is obtained;

[0041] S3, sodium chlorate is added to the mixed solution to adjust the potential to 600 mV, then sodium sulfite is added, the addition amount of the sodium sulfite is 3 times of the selenium content in the mixed solution, reaction is carried out until the Se in the mixed solution is lower than 50 mg / L, pressure filtration is carried out, and a filtrate is obtained;

[0042] S4, the filtrate of S3 is added into sheet alkali, the pH of the system is adjusted to 5.1+ / -0.1, and a target tellurium dioxide product is obtained, and the composition is shown in Table 4.

[0043] Table 4

[0044] Composition Te Bi Cu Sb Pb Se Content 71.9900％ 0.0025％ 0.0033％ 0.0005％ 0.0130％ 0.0082％

[0045] Example 3

[0046] S1, 600g of tellurium slag is crushed, the specific composition is shown in Table 5, the crushed tellurium slag and 1800mL of alkali solution are mixed to form a filtrate, sodium sulfide is added to the filtrate, the addition amount of the sodium sulfide is 2.5 times of the lead content in the filtrate, impurity lead is removed, pressure filtration is carried out, the filtrate is neutralized, and crude tellurium dioxide is obtained;

[0047] Table 5

[0048] Composition Te Bi Cu Sb Pb Se Content 21.31％ 12.72％ 2.32％ 3.86％ 7.79％ 4.70％

[0049] S2, the crude tellurium dioxide is put into an acid leaching tank, deionized water and hydrochloric acid with a concentration of 5 mol / L are sequentially added, the mass ratio of the crude tellurium dioxide, the deionized water and the hydrochloric acid is 1:1:3, acid dissolution reaction is carried out at 60 DEG C for 2h, and a mixed solution is obtained;

[0050] S3, sodium chlorate is added to the mixed solution to adjust the potential to 600 mV, then sodium sulfite is added, the addition amount of the sodium sulfite is 3 times of the selenium content in the mixed solution, reaction is carried out until the Se in the mixed solution is lower than 50 mg / L, pressure filtration is carried out, and a filtrate is obtained;

[0051] S4, the filtrate of S3 is added into sheet alkali, the pH of the system is adjusted to 5.1+ / -0.1, and a target tellurium dioxide product is obtained, and the composition is shown in Table 4.

[0052] Table 6

[0053] Composition Te Bi Cu Sb Pb Se Content 75.0100％ 0.0036％ 0.0054％ 0.0008％ 0.0090％ 0.0081％

[0054] As can be seen from Examples 1-3, the prepared tellurium dioxide has a selenium impurity content of less than 0.01%. The tellurium recovery rate can reach 99% from the crude tellurium dioxide to the pure tellurium dioxide.

[0055] Example 4

[0056] The prepared tellurium dioxide in Examples 1-3 is subjected to sheet lye dissolution, sodium sulfide purification solution making, and then is punched into an electrodeposition tank. The electrodeposited tellurium sheet is subjected to washing, drying, melting, and casting to obtain high-quality tellurium ingots. The purity results are shown in Table 7.

[0057] Table 7

[0058] Sample Teller ingot purity Example 1 99.9947％ Example 2 99.9933％ Example 3 99.9959％

[0059] As can be seen from Table 7, the high-purity tellurium dioxide prepared by removing selenium from the selenium-containing tellurium material according to the present application has a purity of more than 99.99% after the subsequent preparation of tellurium ingots.

[0060] Comparative Example 1

[0061] The traditional process for preparing tellurium dioxide by removing selenium from selenium-containing tellurium material by alkali leaching is as follows: selenium-containing tellurium material→alkali leaching and tellurium separation→hydrolysis and tellurium precipitation→calcination and selenium removal→tellurium dioxide.

[0062] Comparative Example 2

[0063] The difference from Example 1 is that the potential is not adjusted, and the other conditions are the same as those in Example 1.

[0064] S1, 600g of tellurium residue is crushed, the crushed tellurium residue is mixed with 1200mL of lye to form a filtrate, sodium sulfide is added to the filtrate, the amount of sodium sulfide added is 0.5 times the lead content in the filtrate, impurities such as lead are removed, pressure filtration is performed, and the filtrate is neutralized to obtain crude tellurium dioxide;

[0065] S2, the crude tellurium dioxide is put into an acid leaching tank, deionized water and hydrochloric acid with a concentration of 10mol / L are sequentially added, the mass ratio of the crude tellurium dioxide to the deionized water and the hydrochloric acid is 1:2:4, and the acid dissolution reaction is performed at 70℃ for 1h to obtain a mixed solution;

[0066] S3, sodium sulfite is added to the mixed solution, the amount of sodium sulfite added is 4 times the selenium content in the mixed solution, and the reaction is performed until the Se in the mixed solution is less than 50mg / L, and pressure filtration is performed to obtain a filtrate;

[0067] S4, the filtrate of S3 is added to sheet lye, the pH of the system is adjusted to 5.5±0.1, and a tellurium dioxide product is obtained.

[0068] Comparative Example 3

[0069] The method of CN109775670A is used to prepare tellurium dioxide.

[0070] That is, a method for removing selenium from a material containing selenium and tellurium to prepare high-purity tellurium dioxide, and the specific steps include:

[0071] S1, pretreatment: 600g of tellurium residue is crushed, 1800mL of deionized water is added, and the slurry is stirred, sodium sulfite is added, the amount of sodium sulfite added is 4 times the selenium content in the slurry, and the reaction is carried out;

[0072] S2, acidification and selenium precipitation: after the reaction is completed, a catalyst composed of sodium chloride and sulfuric acid with a mass ratio of 1:2 is added, and catalytic tellurium precipitation is carried out, the amount of chloride ion added is 1% of the mass of the tellurium residue, sulfuric acid is added to adjust the pH of the solution to 1.5, and the reaction is carried out at 75°C for 1h to obtain a selenium precipitation slurry.

[0073] S3, tellurium separation by alkali leaching: sodium hydroxide is added according to 1.3 times the tellurium content in the selenium precipitation slurry, the temperature is controlled to 55°C when adding the alkali, the temperature rises to 90°C after adding the alkali, and the reaction is carried out for 1h, filtration is carried out, and high-selenium residue and alkali leaching solution are obtained.

[0074] S4, selenium removal by hydrolysis: sulfuric acid is added to the alkali leaching solution for hydrolysis, the concentration of the acid is controlled to 50%, the hydrolysis temperature is 75°C, the pH value is measured intermittently until it stabilizes to 4, and filtration is carried out to obtain tellurium dioxide product.

[0075] The tellurium dioxide products obtained by the methods of Example 1 and Comparative Example 1 are analyzed, and the results are shown in Table 8.

[0076] Table 8

[0077] Teller recovery Selenium content Teller ingot purity Example 1 99％ 0.0094％ 99.9947％ Comparative Example 1 96％ 0.2077％ 99.0165％ Comparative Example 2 97％ 0.1214％ 99.4747％ Comparative Example 3 98％ 0.0958％ 99.1654％

[0078] As can be seen from Table 8, the tellurium dioxide obtained by the method of the present application has high tellurium recovery rate and high selenium removal efficiency, and the prepared tellurium ingot has a purity of 99.9947%.

[0079] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for producing high purity tellurium dioxide by removing selenium from a material containing selenium and tellurium, characterized by, The specific steps include: S1, crushing the tellurium residue containing Na2TeO3 produced by lead anode slime, and adding sodium sulfide to remove impurities lead in the filtrate after alkali leaching, and then performing pressure filtration and neutralizing the filtrate to obtain coarse tellurium dioxide; S2, putting the coarse tellurium dioxide into an acid leaching tank, adding deionized water and hydrochloric acid in sequence to perform acid dissolution reaction, and obtaining a mixed solution; The mass ratio of the coarse tellurium dioxide to the deionized water and the hydrochloric acid is 1:1-3:3-5; S3, adding sodium chlorate to the mixed solution to adjust the potential to 600-900 mV, and then adding sodium sulfite to react until the Se in the mixed solution is lower than 50 mg / L, and then performing pressure filtration to obtain a filtrate; S4, adding flake caustic soda to the filtrate of S3 to obtain a target tellurium dioxide product.

2. A method of removing selenium from a material containing selenium and tellurium to produce high purity tellurium dioxide according to claim 1, characterized in that, In step S1, the adding amount of sodium sulfide is 0.5-5 times of the lead content in the filtrate.

3. The method of claim 1, wherein the selenium is removed from the selenium-tellurium containing material to produce high purity tellurium dioxide, and wherein the method further comprises the step of: In step S2, the concentration of hydrochloric acid is 1-10 mol / L. ​ 4. The method of claim 1, wherein the selenium is removed from the selenium-tellurium containing material to produce high purity tellurium dioxide, and wherein the method further comprises the step of: In step S2, the temperature of the acid dissolution reaction is 60-80℃, and the time is 0.5-5 h. ​ 5. The method of claim 1, wherein the selenium is removed from the selenium-tellurium containing material to produce high purity tellurium dioxide, and wherein the method further comprises the step of: In step S3, the adding amount of sodium sulfite is 3-5 times of the selenium content in the mixed solution. ​ 6. The method of claim 1, wherein the selenium is removed from the selenium-tellurium containing material to produce high purity tellurium dioxide, and wherein the method further comprises the step of: In step S4, the pH of the system is adjusted to 5.0-6.5 by adding flake caustic soda. ​ 7. The method of claim 1, wherein the selenium is removed from the selenium-tellurium containing material to produce high purity tellurium dioxide, and wherein the method further comprises the step of: The obtained tellurium dioxide product is used for subsequent preparation of high-quality tellurium ingot. ​