Method for extracting tellurium from desulfurization residue

Abstract

The application discloses a method for extracting tellurium from desulfurization residues, which comprises the steps of oxidizing roasting, acidizing leaching and neutralizing precipitation, and specifically comprises the following steps: placing the desulfurization residues in an atmosphere furnace with an oxygen concentration of 15-25%, and performing oxidizing roasting at a temperature of 650-850 DEG C for 0.5-2 hours to obtain roasting residues a; after adding acid into the roasting residues a, placing the roasting residues a in a constant-temperature water bath pot at 60-80 DEG C, and stirring and reacting for 1-2 hours, vacuum filtering to obtain noble metal enrichment residues b and filtrate c; adding sodium hydroxide into the filtrate c to perform neutralization reaction until the pH value is 7-8, and filtering to obtain filter residues d and neutralized liquid e, and the filter residues d are tellurium dioxide. The method has the advantages of short process flow, high removal rate and efficient enrichment, and the development of the technology can improve the utilization rate of resources. The application can further develop the profit growth point of smelting enterprises and improve the efficiency of enterprise innovation by adopting the "oxidizing roasting-acidizing leaching-neutralizing precipitation" process to treat the desulfurization residues.

Description

Technical Field

[0001] This invention belongs to the field of mining engineering technology, and specifically relates to a method for extracting tellurium from deselenized slag. Background Technology

[0002] Tellurium, as a rare and dispersed metal, is characterized by low abundance and scarce resources. It does not exist in independent deposits but rather occurs as a by-product within deposits of other elements, currently primarily recovered from anode slime containing copper, lead, and other metals. In recent years, most smelting enterprises process anode slime by extracting selenium, leaving tellurium and other precious metals in the deselection slag. This slag is mainly returned to the ISA furnace, repeatedly circulating within the process, resulting in dispersed rare and precious metals and low recovery rates. Direct sale of these slags leads to low economic efficiency. Therefore, developing a method to solve these technical problems is essential. Summary of the Invention

[0003] The purpose of this invention is to provide a method for extracting tellurium from deselenized residue.

[0004] This invention addresses the production and technical problems associated with deselementized slag by employing an "oxidative roasting-acidification leaching-neutralization precipitation" process. This approach can further expand profit growth points for smelting enterprises and enhance their innovation and efficiency. Tellurium mainly exists as elemental form or as intermetallic compounds with copper and lead, such as Cu₂Te and PbTe. When recovering tellurium, the recovery of copper, lead, selenium, and precious metals like gold and silver is often also considered.

[0005] The objective of this invention is achieved by including oxidative roasting, acid leaching, neutralization and precipitation steps, specifically including: A. Oxidative roasting: The selenium-depleted slag is placed in a furnace with an oxygen concentration of 15-25% and oxidatively roasted at a temperature of 650-850℃ for 0.5-2 hours to obtain roasted slag a; B. Acid leaching: Add acid to the roasted residue a and place it in a constant temperature water bath at 60~80℃ and stir for 1~2 hours. Vacuum filter to obtain precious metal enriched residue b and filtrate c. C. Neutralization and precipitation: Add sodium hydroxide to filtrate c to neutralize it until the pH value is 7-8. Filter to obtain filter residue d and neutralized liquid e. Filter residue d is tellurium dioxide.

[0006] The specific steps are as follows: A. Oxidative roasting: The deselenized residue with a tellurium content of 8-20% was placed in a ceramic crucible and put into a furnace with an oxygen concentration of 21%. The temperature was raised to 650-850℃ at a rate of 5-10℃ / min and held for 0.5-2h. After the reaction was completed, the temperature was lowered to room temperature and the roasted residue was taken out as the material for neutralization and precipitation. B. Acidification and leaching: Dissolve the oxidized roasted residue in 100-200 g / L acid, place it in a constant temperature water bath at 60-80℃, stir and react for 1-2 hours. After the reaction stops, take out the material and filter it. The filter residue is precious metal enrichment residue, and the filtrate is leachate, which enters the subsequent neutralization and precipitation. C. Neutralization and precipitation: Under stirring, slowly add sodium hydroxide to the acidified leachate until the pH reaches 7-8, then stop the reaction. After the reaction stops, remove the material and filter it. The filter residue is tellurium dioxide, and the filtrate is the neutralized liquid.

[0007] This invention can achieve a recovery rate of over 99% for precious metals and a leaching rate of over 90% for tellurium. It can be applied to industrial production and has a promising prospect for industrialization. Detailed Implementation

[0008] The present invention will be further described below with reference to embodiments, but this is not intended to limit the present invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0009] The method for extracting tellurium from selenium-depleted residue according to the present invention includes the steps of oxidative roasting, acid leaching, and neutralization precipitation, specifically including: A. Oxidative roasting: The selenium-depleted slag is placed in a furnace with an oxygen concentration of 15-25% and oxidatively roasted at a temperature of 650-850℃ for 0.5-2 hours to obtain roasted slag a; B. Acid leaching: Add acid to the roasted residue a and place it in a constant temperature water bath at 60~80℃ and stir for 1~2 hours. Vacuum filter to obtain precious metal enriched residue b and filtrate c. C. Neutralization and precipitation: Add sodium hydroxide to filtrate c to neutralize it until the pH value is 7-8. Filter to obtain filter residue d and neutralized liquid e. Filter residue d is tellurium dioxide.

[0010] In step A, the heating rate is controlled at 5~10℃ / min to reduce the temperature difference between the furnace temperature and the actual temperature.

[0011] The acid mentioned in step B is sulfuric acid, hydrochloric acid, or nitric acid.

[0012] The concentration of the acid is 100~200g / L.

[0013] In step B, the precious metal enrichment residue b is leached with thiourea to recover silver, while gold, platinum, and palladium are enriched in the leaching residue. Gold and platinum / palladium are then separated by acid leaching.

[0014] The concentration of sodium hydroxide mentioned in step C is 50~100g / L.

[0015] The deselenization residue is one or more of the following: selenium-distilled residue, high-purity selenium leaching residue, and 3N selenium leaching residue.

[0016] The tellurium content in the deselenized residue is 8-20% by mass.

[0017] The invention will be further illustrated below with specific implementation examples: Example 1 100g of deselenized material (Te: 13.88%, Ag: 8066g / t, Au: 219.22g / t, Pt: 77.67g / t, Pd: 111.69g / t) was taken into a ceramic crucible and placed in an oxygen atmosphere furnace. The temperature was raised to 700℃ and held for 1 hour. After the reaction was completed, the temperature was lowered to room temperature, and the calcined residue was removed. The calcined residue was dissolved in 150g / L acid, and the temperature was controlled at 70℃. The mixture was stirred and reacted for 1 hour. After the reaction was stopped, vacuum filtration was performed. The filter residue was... The precious metal enrichment slag, with a slag quantity of 22.72g (Te: 5.23%, Ag: 35146.74g / t, Au: 958.12g / t, Pt: 341.17g / t, Pd: 489.14g / t), and the filtrate was a leachate of Te. Sodium hydroxide was slowly added to the obtained leachate under stirring to adjust the pH to 7. After the reaction stopped, the material was removed and filtered. The filter residue was tellurium dioxide (14.76g), and the filtrate was the neutralized liquid.

[0018] Example 2 Take 100g of deselenized material (Te: 13.88%, Ag: 8066g / t, Au: 219.22g / t, Pt: 77.67g / t, Pd: 111.69g / t) in a ceramic crucible and place it in an oxygen atmosphere furnace. Heat to 650℃ and hold for 1 hour. After the reaction is complete, cool to room temperature and remove the calcined residue. Dissolve the calcined residue in 200g / L acid, control the temperature at 80℃, and stir for 1 hour. After the reaction stops, perform vacuum filtration. The filter residue is valuable. Metal enrichment slag, with a slag quantity of 25.58g (Te: 4.47%, Ag: 31311.72g / t, Au: 850.14g / t, Pt: 302.42g / t, Pd: 434.45g / t), and filtrate was a leaching solution of Te. Sodium hydroxide was slowly added to the obtained leaching solution under stirring to adjust the pH to 7.5. After the reaction stopped, the material was removed and filtered. The filter residue was tellurium dioxide (14.81g), and the filtrate was the neutralized liquid.

[0019] Example 3 100g of deselenized material (Te: 13.88%, Ag: 8066g / t, Au: 219.22g / t, Pt: 77.67g / t, Pd: 111.69g / t) was taken into a ceramic crucible and placed in an oxygen atmosphere furnace. The temperature was raised to 850℃ and held for 1.5h. After the reaction was completed, the temperature was lowered to room temperature, and the calcined residue was removed. The calcined residue was dissolved in 100g / L acid, and the temperature was controlled at 60℃. The mixture was stirred and reacted for 1.5h. After the reaction was stopped, vacuum filtration was performed. The filter residue was a precious metal enrichment residue with a quantity of 21.10 g (Te: 5.96%, Ag: 37959.89 g / t, Au: 1033.76 g / t, Pt: 365.53 g / t, Pd: 527.22 g / t). The filtrate was a leachate. Sodium hydroxide was slowly added to the obtained leachate under stirring to adjust the pH to 8. After the reaction stopped, the material was taken out for filtration. The filter residue was tellurium dioxide (14.36), and the filtrate was the neutralized liquid.

Claims

1. A method for extracting tellurium from deselenized residue, characterized in that, The process includes oxidative roasting, acid leaching, neutralization, and precipitation steps, specifically including: A. Oxidative roasting: The selenium-depleted slag is placed in a furnace with an oxygen concentration of 15-25% and oxidatively roasted at a temperature of 650-850℃ for 0.5-2 hours to obtain roasted slag a; B. Acid leaching: Add acid to the roasted residue a and place it in a constant temperature water bath at 60~80℃ and stir for 1~2 hours. Vacuum filter to obtain precious metal enriched residue b and filtrate c. C. Neutralization and precipitation: Add sodium hydroxide to filtrate c to neutralize it until the pH value is 7-8. Filter to obtain filter residue d and neutralized liquid e. Filter residue d is tellurium dioxide. In step A, the heating rate is controlled at 5~10℃ / min; The acid mentioned in step B is sulfuric acid, hydrochloric acid, or nitric acid; The concentration of the acid is 100~200 g / L; The concentration of sodium hydroxide mentioned in step C is 50~100g / L; The deselenic residue is one or more of the following: selenium-distilled residue, high-purity selenium leaching residue, and 3N selenium leaching residue; The tellurium content in the deselenized residue is 8-20% by mass.

2. The method for extracting tellurium from deselenized residue according to claim 1, characterized in that, In step B, the precious metal enrichment residue b is leached with thiourea to recover silver, while gold, platinum, and palladium are enriched in the leaching residue. Gold and platinum / palladium are then separated by acid leaching.