Device and method for producing refined tellurium

Abstract

The invention discloses a device and a method for producing refined tellurium. The device comprises an electrodeposition tank, a low-position circulating liquid tank, a circulating liquid pump, a precision filter, a high-position circulating liquid tank and a rectifier which are communicated according to a connection relation. The method comprises the following steps: carrying out wet ball milling on tellurium slag and water, pumping obtained slurry into a leaching kettle, adding water for dilution, then adding industrial-grade sodium sulfide for reaction, and filtering to obtain a purified solution; raising the temperature of the purified liquid, adding dilute sulphuric acid for neutralization reaction, and filtering to obtain wet tellurium dioxide; returning the wet tellurium dioxide into the neutralization kettle, adding hot water for repeated washing, and calcining the washed wet tellurium dioxide into dry tellurium dioxide; taking analytically pure sodium sulfide, caustic soda flakes, dry tellurium dioxide and water to react, standing and precipitating after the reaction, and extracting supernatant to obtain electrodeposition liquid; filling the electrodeposition liquid into an electrodeposition cell, starting a rectifier, a liquid circulating pump and a precision filter, setting current and voltage, and starting electrodeposition; tellurium powder, waste electrodeposition liquid and bottom impurities are produced. The problems of low tellurium electrodeposition efficiency, poor tellurium powder quality, low electrodeposition direct recovery rate and the like can be effectively solved.

Description

1. Technical field:

[0001] The present invention relates to the technical field of rare and precious metal recovery, and in particular to a device and method for producing refined tellurium. 2. Background technology:

[0002] At present, the following process methods are mainly used to produce refined tellurium with the grade Te9999 in the YST 222-2010 tellurium ingot standard from tellurium slag raw materials with sodium tellurite as the main component:

[0003] 1. Wet purification to produce electrolytic solution: wet ball milling of tellurium slag - water immersion - industrial sodium sulfide purification - dilute sulfuric acid neutralization - wet tellurium oxide calcination - dry tellurium dioxide solution making - analytical pure sodium sulfide purification to obtain new electrolytic solution. The principles of each step are as follows:

[0004] Wet ball milling-water immersion: Using the property of sodium tellurite being soluble in water, tellurium is filtered into the liquid and separated from other impurities;

[0005] Industrial sodium sulfide purification: using negative divalent sulfide ions to react with lead, copper, and bismuth cations in the leachate to generate sulfides with lower solubility, and then separating impurities from the solution through filtration to obtain a purified solution with higher purity;

[0006] Neutralization with dilute sulfuric acid: Using the property of sodium tellurite to be easily hydrolyzed to generate tellurium dioxide, tellurium is separated from the liquid;

[0007] Wet tellurium oxide calcination: Selenium and tellurium are separated to produce high-purity tellurium dioxide by utilizing the volatile nature of selenium dioxide;

[0008] Dry tellurium dioxide solution making: Tellurium dioxide is easily soluble in caustic soda solution, so it can be re-entered into the solution;

[0009] Purification of analytical pure sodium sulfide: The principle is the same as that of industrial sodium sulfide purification.

[0010] The existing wet purification process for producing electrolytic solution has the following disadvantages:

[0011] When purifying the leaching solution, an excess of sodium sulfide needs to be added for impurity removal, resulting in the presence of sodium sulfide in the purified solution. When neutralizing and producing wet tellurium dioxide, tellurium dioxide contains 20-40% water. Therefore, there must be residual sodium sulfide in the wet tellurium dioxide. In addition, since the purification and impurity removal is not thorough, sodium sulfide needs to be added again when the new solution is made to remove impurities, which will further increase the concentration of sodium sulfide in the electrolytic solution. The presence of sodium sulfide in the electrolytic solution has the following hazards:

[0012] a. When adding analytically pure sodium sulfide to the newly produced electrolyte, the lead, copper and bismuth sulfide particles generated are small and suspended in the newly produced electrolyte. During the filter press, it will cause the phenomenon of filter penetration, resulting in a high level of impurities in the newly produced electrolyte. In industrial production, the newly produced electrolyte is often left to stand for about 72 hours, and the supernatant is pumped into the electrolyte tank. At this time, the impurity content in the electrolyte is generally (5-20) mg / L, resulting in a long time for the electrolyte preparation.

[0013] b. According to the discharge sequence of anions in tellurium electrowinning, the negative divalent sulfur ions are greater than the negative monovalent hydroxide ions. Therefore, in the traditional tellurium electrowinning process, sulfur will precipitate at the anode, resulting in a large amount of yellow matter being generated, floating or precipitated during the electrowinning process, causing the tellurium electrowinning cell to be dirty.

[0014] 2. Electrolytic production of tellurium powder, washing and drying, and casting to produce tellurium ingots: The tellurium electrolytic production process mainly includes traditional electrolytic process and cyclone electrolytic process. The traditional electrolytic process adopts a non-circulating liquid process, while the cyclone electrolytic process adopts an electrolytic liquid circulation process. They are introduced below:

[0015] 1) Traditional electrolytic process: In the traditional electrolytic process of tellurium, the electrolytic solution is not circulated during the electrolytic process, and the electrolytic solution is in a slow flow state during the electrolytic process. The main reasons are: ① Oxygen is released during the tellurium electrolytic process, and the newly generated oxygen will react with sodium tellurite to generate high-valent sodium tellurite, and sodium tellurite is slightly soluble in water, resulting in a lower direct yield of tellurium; if the current density of the electrolytic process is controlled to be small, the oxygen generation rate will be small, the oxygen will stay in the solution for a long time, and the amount of sodium tellurite oxidized will further increase; if the electrolytic process is strengthened by circulating liquid, the flow of oxygen inside the electrolytic process will be strengthened, thereby accelerating the reaction. ② During the electrolytic process, the sulfides of lead, copper, and bismuth will continue to precipitate. If the electrolytic process adopts a circulating liquid method, the precipitation of sulfides will be further prevented, resulting in an increase in the impurity content in the tellurium powder. Therefore, the circulating liquid method cannot be used for tellurium electrolytic process.

[0016] Therefore, tellurium electrolysis is different from silver electrolysis and copper electrolysis, which adopt the circulating liquid mode. Tellurium electrolysis is carried out in a non-circulating liquid mode.

[0017] This process has the following disadvantages:

[0018] a. Low production efficiency: Because the electrolytic solution does not circulate, the tellurium ion concentration in the cathode plate area is low and the electrolytic efficiency is low.

[0019] b. Poor quality of tellurium powder: During the electrolytic process, the electrolytic solution does not circulate, and the tellurium ions in the electrolytic solution mainly move to the cathode through the action of the electric field. As the electrolytic time increases, the concentration polarization in the electrolytic solution becomes larger. When the tellurium ion concentration in the cathode area is low, the quality of the produced tellurium powder is poor.

[0020] c. Low direct yield of electrolysis: The tellurium electrolysis process will generate oxygen, tellurium powder and sodium hydroxide. The generation of sodium hydroxide will increase the alkali concentration in the electrolysis solution. When the concentration of flake caustic soda in the solution reaches a certain amount, part of the newly generated tellurium powder will be converted into soluble sodium tellurite and sodium telluride, thereby causing the tellurium powder to dissolve back.

[0021] d. In the initial stage of electrolysis (1 day), impurities will be precipitated, causing the surface of the anode plate to become rough, and the anode plate needs to be replaced first.

[0022] e. In the middle stage of electrolysis, due to the combined effects of sulfur, sodium sulfide and sodium hydroxide, tellurium begins to dissolve.

[0023] 2) Cyclone electrowinning process: Cyclone electrowinning technology is a new type of multi-metal purification and separation technology developed on the basis of traditional electrowinning technology. Currently, it is rarely used in tellurium electrowinning. In 2019, technicians from the smelter of Daye Nonferrous Metals Company published an article entitled "Experimental Study on the Application of Cyclone Electrowinning Technology in Tellurium Electrowinning Process". The article briefly introduced the tellurium cyclone electrowinning technology. Its main equipment includes circulation tank, electrolytic cell, flow meter, centrifugal pump, DC voltage and current stabilized power supply. Its electrowinning tank structure is quite different from the traditional one. This process can solve the influence of concentration polarization.

[0024] Therefore, how to solve the problems of low tellurium electrowinning efficiency, poor tellurium powder quality, and low direct yield of electrowinning has become a technical problem that tellurium refining technicians urgently need to solve. 3. Summary of the invention:

[0025] The technical problem to be solved by the present invention is: based on the shortcomings of the current tellurium electrowinning technology (for example, low tellurium electrowinning efficiency, poor tellurium powder quality, low electrowinning direct yield, etc.), the present invention provides a device and method for producing refined tellurium. The technical solution of the present invention can effectively solve the problems of low tellurium electrowinning efficiency, poor tellurium powder quality, and low electrowinning direct yield in the prior art.

[0026] In order to solve the above problems, the technical solution adopted by the present invention is:

[0027] The present invention provides a device for producing refined tellurium, the device comprising an electrolytic cell (1), a low-level circulating liquid cell (2), a circulating liquid pump (3), a precision filter (4), a high-level circulating liquid cell (5) and a rectifier (6), characterized in that: the electrolytic cell (1) is provided with a liquid inlet pipe (1A) and a liquid outlet pipe (1B), the liquid inlet pipe (1A) is provided above the surface of the electrolytic liquid in the electrolytic cell (1), the liquid outlet pipe (1B) is provided at the bottom of the electrolytic liquid in the electrolytic cell (1), the low-level circulating liquid cell (2) is provided below the electrolytic cell (1), and the high-level circulating liquid cell (5) is provided above the electrolytic cell; the liquid inlet pipe (1A) provided in the electrolytic cell (1) is connected to the high-level circulating liquid cell (5), the liquid outlet pipe (1B) provided in the electrolytic cell (1) is provided at the bottom of the electrolytic liquid in the electrolytic cell (1), the low-level circulating liquid cell (2) is provided below the electrolytic cell (1), and the high-level circulating liquid cell (5) is provided above the electrolytic cell; 1B) is connected to a low-level circulation tank (2) (the electrolytic liquid flows in and out of the electrolytic tank by its own weight, and its flow rate is controlled by a valve on the leachate pipeline); one end of the low-level circulation tank (2) is connected to the electrolytic tank (1), and the other end is connected to the circulation pump (3); one end of the circulation pump (3) is connected to the low-level circulation tank (2), and the other end is connected to the precision filter (4); one end of the precision filter (4) is connected to the circulation pump (3), and the other end is connected to the high-level circulation tank (5); one end of the high-level circulation tank (5) is connected to the electrolytic tank (1), and the other end is connected to the precision filter (4); one end of the rectifier (6) is connected to the anode of the electrolytic tank, and the other end is connected to the cathode of the electrolytic tank.

[0028] In addition, a method for producing refined tellurium using the above device is provided, the method comprising the following steps:

[0029] a. Add tellurium slag and water into a ball mill for ball milling. The slurry obtained after ball milling is poured into a leaching kettle and diluted with 2 to 3 times of water; after dilution, heat to 90 to 95°C, then add industrial grade sodium sulfide, and react at a constant temperature of 90 to 95°C for 2 hours; filter after reaction, return the filter residue to the smelting system, and the filtrate is the purified liquid;

[0030] b. The obtained purified solution is heated to 80-90°C again, and then dilute sulfuric acid is added to adjust the pH of the solution to 5-6. The solution is reacted for 1 hour under this condition to obtain wet tellurium dioxide and a neutralized solution, which is then discharged;

[0031] c. The obtained wet tellurium dioxide is returned to the neutralization kettle, and hot water is added for washing. After washing, the slurry is placed in a suction filtration tank and allowed to settle for 2 to 5 minutes. The black floating matter on the surface is then removed and suction filtered until cracks appear in the tellurium dioxide.

[0032] Then, the same amount of hot water at the same temperature is added to the suction filtration tank again, and the wet tellurium dioxide is stirred (with a rake) for 2 to 5 minutes. After stirring, it is allowed to settle for 2 to 5 minutes, and the black floating matter on the surface is removed. The tellurium dioxide is filtered until cracks appear, and the second washing is completed. The tellurium dioxide is washed again according to the second washing method, and the wet tellurium dioxide obtained after washing is placed in a calcining furnace, and the temperature is raised to 490 to 510° C. and calcined at a constant temperature for 8 hours to obtain dry tellurium dioxide.

[0033] d. Take analytically pure sodium sulfide, flake caustic soda, dry tellurium dioxide and water, and react them in a mass ratio of 0.003-0.009:0.12:0.3:1 to produce tellurium electrodeposition solution; after the reaction, let it stand for 48 hours, and then extract the supernatant to obtain the electrodeposition solution;

[0034] e. According to the above device, the electrolytic solution is loaded into the electrolytic tank and other equipment is connected to load the tank. After the tank is loaded, the rectifier, circulating pump and precision filter are turned on, and the current is set to 50-200A and the voltage is set to 2-3V. After the setting, electrolytic deposition is started; after electrolytic deposition, tellurium powder, waste electrolytic solution and bottom impurities are produced.

[0035] According to the above method for producing refined tellurium, in step a, the mass ratio of tellurium slag to water is 1:1; and the amount of industrial-grade sodium sulfide added accounts for 4-8% of the mass of the tellurium slag.

[0036] According to the above method for producing refined tellurium, the mass percentage concentration of the dilute sulfuric acid in step b is 30-40%, and the amount of the dilute sulfuric acid added is 0.5-0.7 times the amount of tellurium precipitated.

[0037] According to the above method for producing refined tellurium, the temperature of the hot water in step c is 50-90°C; the amount of the hot water added accounts for 1 / 3-1 / 2 of the mass of wet tellurium dioxide.

[0038] According to the above method for producing refined tellurium, the reaction temperature when making tellurium electrodeposition in step d is 90-95°C and the constant temperature reaction time is 4 hours.

[0039] According to the above method for producing refined tellurium, the diameter of the particles filtered by the precision filter in step e is ≤1um.

[0040] According to the above method for producing refined tellurium, in step e, the circulating liquid is closed regularly during the electrowinning process, and the time for regularly closing the circulating liquid is: once every 3 to 5 days, and the circulating liquid is closed for 2 hours each time.

[0041] According to the above method for producing refined tellurium, the amount of waste electrolytic solution generated after electrolytic deposition in step e accounts for 1 / 5 to 1 / 3 of the total amount of liquid in the electrolytic deposition tank.

[0042] According to the above method for producing refined tellurium, during the electrolytic deposition process in step e, the electrolytic solution with high impurity content at the bottom is regularly extracted and transported to the low-level circulation tank through the electrolytic deposition tank outlet pipe, and dilute sulfuric acid is added to adjust the free alkali content of the electrolytic solution to less than 60g / l; and a precision filter is used to filter out the suspended impurities therein.

[0043] The positive beneficial effects of the present invention are:

[0044] 1. High direct yield of electrolysis: Since the electrolysis method has solved the technical bottleneck of tellurium electrolysis liquid circulation, it has alleviated the problem of large concentration polarization caused by excessive electrolysis. The tail liquid index can be controlled to be lower, there is no back-dissolution problem in the electrolysis process, and the direct yield of the electrolysis process is improved.

[0045] 2. High electrolytic efficiency: Since this electrolytic method strengthens the mass transfer process inside the electrolytic solution, the tellurium ion concentration near the cathode plate is relatively high and the electrolytic efficiency is high.

[0046] 3. Stable voltage index: During the electrolytic process, the concentration inside the solution is uniform.

[0047] 4. The alkalinity of the electrolytic solution is low and there is no re-dissolution problem: During the electrolytic process, part of the liquid is continuously extracted to adjust the alkalinity and reduce the re-dissolution of tellurium.

[0048] In summary, the production of refined tellurium using the technical solution of the present invention has high direct electrolytic recovery rate, high electrolytic efficiency, stable voltage index, low electrolytic solution alkalinity, and no re-dissolution problem. Therefore, the technical solution of the present invention can effectively solve the problems of low tellurium electrolytic efficiency, poor tellurium powder quality, low direct electrolytic recovery rate, etc. in the prior art. 4. Description of the drawings:

[0049] Figure 1 A schematic diagram of the structure of the device for producing refined tellurium according to the present invention;

[0050] Figure 1 In the figure, 1 is an electrolytic cell, 2 is a low-level circulating liquid cell, 3 is a circulating liquid pump, 4 is a precision filter, 5 is a high-level circulating liquid cell, 6 is a rectifier, 1A is an electrolytic cell liquid inlet pipe, and 1B is an electrolytic cell liquid outlet pipe. V. Specific implementation methods:

[0051] The present invention is further described below in conjunction with embodiments, but the protection scope of the technical solution of the present invention is not limited thereto.

[0052] Embodiment 1:

[0053] The device for producing refined tellurium of the present invention comprises an electrolytic cell (1), a low-level circulating liquid cell (2), a circulating liquid pump (3), a precision filter (4), a high-level circulating liquid cell (5) and a rectifier (6). The electrolytic cell (1) is provided with a liquid inlet pipe (1A) and a liquid outlet pipe (1B). The liquid inlet pipe (1A) is provided above the surface of the electrolytic liquid in the electrolytic cell (1), and the liquid outlet pipe (1B) is provided at the bottom of the electrolytic liquid in the electrolytic cell (1). The low-level circulating liquid cell (2) is provided below the electrolytic cell (1), and the high-level circulating liquid cell (5) is provided above the electrolytic cell. The liquid inlet pipe (1A) provided in the electrolytic cell (1) is connected to the high-level circulating liquid cell (5), and the liquid outlet pipe (1B) provided in the electrolytic cell (1) and the low-level circulating liquid cell (2) are provided to the electrolytic cell (1). The low-level circulating liquid tank (2) is connected to the electrolytic tank (1) (the electrolytic liquid flows in and out of the electrolytic tank by its own weight, and its flow rate is controlled by a valve on the leaching liquid pipeline); one end of the low-level circulating liquid tank (2) is connected to the electrolytic tank (1), and the other end is connected to the circulating liquid pump (3); one end of the circulating liquid pump (3) is connected to the low-level circulating liquid tank (2), and the other end is connected to the precision filter (4); one end of the precision filter (4) is connected to the circulating liquid pump (3), and the other end is connected to the high-level circulating liquid tank (5); one end of the high-level circulating liquid tank (5) is connected to the electrolytic tank (1), and the other end is connected to the precision filter (4); one end of the rectifier (6) is connected to the anode of the electrolytic tank, and the other end is connected to the cathode of the electrolytic tank.

[0054] Embodiment 2:

[0055] The method for producing refined tellurium using the device described in Example 1 of the present invention has the following detailed steps:

[0056] a. Add 600 kg of tellurium slag to 600 L of water and use a ball mill for wet ball milling. The slurry obtained after ball milling is poured into a leaching kettle, and then water is added to dilute it to a total liquid volume of 3600 L; at the same time, steam is turned on to raise the temperature to 93°C, and then 37.5 kg of industrial-grade sodium sulfide is added, and the reaction is carried out at a constant temperature of 93°C for 2 hours; after the reaction, the filter is filtered, and the obtained filter residue is returned to the smelting system, and the filtrate is the purified liquid;

[0057] b. The purified liquid was heated to 90°C again, and then 35% by mass percent dilute sulfuric acid was added to adjust the pH value of the solution to 6. The neutralization reaction was carried out at 90°C for 1 hour. After the reaction, the solution was filtered to obtain 180 kg of wet tellurium dioxide and neutralized solution, and the neutralized solution was discharged;

[0058] c. Return the obtained 180 kg of wet tellurium dioxide to the neutralization kettle, add 60 L of hot water at 90°C and stir for 10 minutes for washing. After washing, place the slurry in a suction filtration tank and let it settle for 4 minutes. Then remove the black floating matter on the surface of the liquid and start suction filtration until cracks appear in the tellurium dioxide.

[0059] Then, the same amount of hot water at the same temperature is added to the suction filtration tank again, and the wet tellurium dioxide is stirred (with a rake) for 5 minutes. After stirring, it is allowed to settle for 4 minutes, and the black floating matter on the surface of the liquid is removed. The tellurium dioxide is filtered until cracks appear, and the second washing is completed. The second washing method can be used for washing again. The obtained wet tellurium dioxide is placed in a kang tray and placed in a calcining furnace. The temperature is raised to 510° C. and calcined at a constant temperature for 8 hours to obtain 110 kg of dry tellurium dioxide.

[0060] d. Take 275kg of caustic soda flakes, 700kg of dry tellurium dioxide and 2.3m 3 Water was added to the electrolytic solution reactor, steam was turned on for heating, and when the temperature reached 92°C, 8 kg of analytically pure sodium sulfide was added and the reaction was carried out at a constant temperature for 4 hours; after the reaction, the solution was allowed to settle for 48 hours, and then the supernatant was extracted to obtain new electrolytic solution (the residue was returned to the ball mill); the new electrolytic solution obtained was 2.5 m 3 It contains 109g / L sodium hydroxide, 218g / L tellurium, 0.2mg copper, 3mg / L lead, 5mg / L bismuth, and the new electrolyte contains 546kg tellurium;

[0061] e. According to the device described in Example 1, 42 cleaned cathode plates and 36 anode plates were evenly placed in the electrolytic cell, and then 0.5 m 3 The electrolytic solution is pumped to the low level circulation tank, 0.5m 3 The electrolytic solution is pumped into the high-level circulation tank, 1.5m 3 The electrolytic solution is pumped into the tellurium electrolytic solution tank and allowed to settle for 24 hours before preparing for electrolytic solution; the rectifier, circulating pump and precision filter (the diameter of the particles filtered by the precision filter is ≤1um) are turned on, the current is set to 200A and the voltage to 3V, and then electrolytic solution is started;

[0062] During the electrowinning process, the circulating liquid was closed for 2 hours on the 5th and 10th days respectively. All the electrowinning liquid in the low-level circulating liquid tank was pumped into the high-level circulating liquid tank, and then 0.4m 3 The electrolytic solution with high impurity content is transferred to the low-level circulating liquid tank, and the electrolytic solution in the high-level circulating liquid tank is allowed to flow to the electrolytic tank by gravity. After being allowed to settle for 2 hours, the rectifier is turned on for electrolytic deposition. 40L of dilute sulfuric acid with a concentration of 35% is added to the low-level circulating liquid tank. The suspended impurities are filtered out with a precision filter, and the filtrate is transferred to the high-level circulating liquid tank after filtration. After 15 days of electrolytic deposition, the tail liquid is tested to contain 37.5g / L of tellurium, and the electrolytic deposition is stopped. The total amount of tail liquid is 1.7m 3 The tail liquid contained 64 kg of tellurium, 464 kg of tellurium powder was produced, and the direct recovery rate of tellurium by electrowinning was about 84.9%.

[0063] Embodiment 3:

[0064] The method for producing refined tellurium using the device described in Example 1 of the present invention has the following detailed steps:

[0065] a. Add 600 kg of tellurium slag to 600 L of water and use a ball mill for wet ball milling. The slurry obtained after ball milling is poured into a leaching kettle, and then water is added to dilute it to a total liquid volume of 3600 L; at the same time, steam is turned on to raise the temperature to 95°C, and then 37.5 kg of industrial-grade sodium sulfide is added, and the reaction is carried out at a constant temperature of 95°C for 2 hours; after the reaction, the filter is filtered, and the obtained filter residue is returned to the smelting system, and the filtrate is the purified liquid;

[0066] b. The purified liquid was heated to 88°C again, and then 36% by mass percent dilute sulfuric acid was added to adjust the pH value of the solution to 6. The neutralization reaction was carried out at 88°C for 1 hour. After the reaction, the solution was filtered to obtain 170 kg of wet tellurium dioxide and neutralized solution, which was discharged;

[0067] c. Return the obtained 170 kg of wet tellurium dioxide to the neutralization kettle, add 60 L of hot water at 90°C and stir for 10 minutes for washing. After washing, place the slurry in a suction filtration tank and let it settle for 5 minutes. Then remove the black floating matter on the surface of the liquid and start suction filtration until cracks appear in the tellurium dioxide.

[0068] Then, the same amount of hot water at the same temperature is added to the suction filtration tank again, and the wet tellurium dioxide is stirred (with a rake) for 5 minutes. After stirring, it is allowed to settle for 4 minutes, and the black floating matter on the surface of the liquid is removed. The tellurium dioxide is filtered until cracks appear, and the second washing is completed. The second washing method is used to wash it again, and the obtained wet tellurium dioxide is placed in a kang tray and placed in a calcining furnace. The temperature is raised to 490° C. and calcined at a constant temperature for 8 hours to obtain 115 kg of dry tellurium dioxide.

[0069] d. Take 275kg of caustic soda flakes, 700kg of dry tellurium dioxide and 2.3m 3 Water was added to the electrolytic solution reactor, steam was turned on for heating, and when the temperature rose to 93°C, 9 kg of analytically pure sodium sulfide was added and the reaction was carried out at a constant temperature for 4 hours; after the reaction, the solution was allowed to settle for 48 hours, and then the supernatant was extracted to obtain new electrolytic solution (the obtained filter residue was returned to the ball mill); the obtained new electrolytic solution 2.5 m 3 It contains 110g / L of sodium hydroxide, 221.2g / L of tellurium, 0.1mg of copper, 2.5mg / L of lead, 4.3mg / L of bismuth, and the new electrolyte contains 553kg of tellurium;

[0070] e. According to the device described in Example 1, 42 cleaned cathode plates and 36 anode plates were evenly placed in the electrolytic cell, and then 0.5 m 3 The electrolytic solution is pumped to the low level circulation tank, 0.5m 3 The electrolytic solution is pumped into the high-level circulation tank, 1.5m 3The electrolytic solution is pumped into the tellurium electrolytic solution tank and allowed to settle for 24 hours before preparing for electrolytic solution; the rectifier, circulating pump and precision filter (the diameter of the particles filtered by the precision filter is ≤1um) are turned on, the current is set to 200A and the voltage to 2.7V, and then electrolytic solution is started;

[0071] During the electrowinning process, the circulating liquid was closed for 2 hours on the 5th and 10th days respectively. All the electrowinning liquid in the low-level circulating liquid tank was pumped into the high-level circulating liquid tank, and then 0.4m 3 The electrolytic solution with high impurity content is transferred to the low-level circulating liquid tank, and the electrolytic solution in the high-level circulating liquid tank is allowed to flow to the electrolytic tank by gravity. After being allowed to settle for 2 hours, the rectifier is turned on for electrolytic deposition. 43L of dilute sulfuric acid with a concentration of 36% is added to the low-level circulating liquid tank. The suspended impurities are filtered out with a precision filter, and the filtrate is transferred to the high-level circulating liquid tank after filtration. After 15 days of electrolytic deposition, the tail liquid is tested to contain 32.5g / L of tellurium, and the electrolytic deposition is stopped. The total amount of tail liquid is 1.7m 3 The tail liquid contained 55.3 kg of tellurium, 480 kg of tellurium powder was produced, and the direct recovery rate of tellurium by electrowinning was about 86.7%.

Claims

1. A device for producing refined tellurium, characterized in that: The device comprises an electrolysis tank (1), a low-level circulating liquid tank (2), a circulating liquid pump (3), a precision filter (4), a high-level circulating liquid tank (5) and a rectifier (6), and is characterized in that: the electrolysis tank (1) is provided with a liquid inlet pipe (1A) and a liquid outlet pipe (1B), the liquid inlet pipe (1A) is arranged above the electrolysis liquid surface in the electrolysis tank (1), the liquid outlet pipe (1B) is arranged at the bottom of the electrolysis liquid in the electrolysis tank (1), the low-level circulating liquid tank (2) is arranged below the electrolysis tank (1), and the high-level circulating liquid tank (5) is arranged above the electrolysis tank; the liquid inlet pipe (1A) provided in the electrolysis tank (1) is connected to the high-level circulating liquid tank (5), and the electrolysis tank (1) is connected to the high-level circulating liquid tank (5). The liquid outlet pipe (1B) provided in the accumulation tank (1) is connected to the low-level circulation tank (2); one end of the low-level circulation tank (2) is connected to the electrolytic tank (1), and the other end is connected to the circulation pump (3); one end of the circulation pump (3) is connected to the low-level circulation tank (2), and the other end is connected to the precision filter (4); one end of the precision filter (4) is connected to the circulation pump (3), and the other end is connected to the high-level circulation tank (5); one end of the high-level circulation tank (5) is connected to the electrolytic tank (1), and the other end is connected to the precision filter (4); one end of the rectifier (6) is connected to the anode of the electrolytic tank, and the other end is connected to the cathode of the electrolytic tank.

2. A method for producing refined tellurium using the device according to claim 1, characterized in that: The method comprises the following steps: a. Add tellurium slag and water into a ball mill for ball milling. The slurry obtained after ball milling is poured into a leaching kettle and diluted with 2 to 3 times of water; after dilution, heat to 90 to 95°C, then add industrial grade sodium sulfide, and react at a constant temperature of 90 to 95°C for 2 hours; filter after reaction, return the filter residue to the smelting system, and the filtrate is the purified liquid; b. The obtained purified solution is heated to 80-90°C again, and then dilute sulfuric acid is added to adjust the pH of the solution to 5-6. The solution is reacted for 1 hour under this condition to obtain wet tellurium dioxide and a neutralized solution, which is then discharged; c. The obtained wet tellurium dioxide is returned to the neutralization kettle, and hot water is added for washing. After washing, the slurry is placed in a suction filtration tank and allowed to settle for 2 to 5 minutes. The black floating matter on the surface is then removed and suction filtered until cracks appear in the tellurium dioxide. Then, the same amount of hot water at the same temperature is added to the suction filtration tank again, and the wet tellurium dioxide is stirred for 2 to 5 minutes. After stirring, it is allowed to settle for 2 to 5 minutes, and the black floating matter on the surface is removed. The tellurium dioxide is filtered until cracks appear, and the second washing is completed. The tellurium dioxide is washed again according to the second washing method, and the wet tellurium dioxide obtained after washing is placed in a calcining furnace, and the temperature is raised to 490 to 510° C. and calcined at a constant temperature for 8 hours to obtain dry tellurium dioxide. d. Take analytically pure sodium sulfide, flake caustic soda, dry tellurium dioxide and water, and react them in a mass ratio of 0.003-0.009:0.12:0.3:1 to produce tellurium electrodeposition solution; after the reaction, let it stand for 48 hours, and then extract the supernatant to obtain the electrodeposition solution; e. The device according to claim 1 is used to load the electrolytic solution into the electrolytic tank and connect other equipment to load the tank. After loading, the rectifier, circulating pump and precision filter are turned on, and the current is set to 50-200A and the voltage is set to 2-3V. After the setting, electrolytic solution is started; after electrolytic solution, tellurium powder, waste electrolytic solution and bottom impurities are produced.

3. The method for producing refined tellurium according to claim 2, characterized in that: In step a, the mass ratio of tellurium slag to water is 1:1; the amount of industrial-grade sodium sulfide added accounts for 4-8% of the mass of the tellurium slag.

4. The method for producing refined tellurium according to claim 2, characterized in that: The mass percentage concentration of the dilute sulfuric acid in step b is 30-40%, and the amount of the dilute sulfuric acid added is 0.5-0.7 times the amount of tellurium precipitated.

5. The method for producing refined tellurium according to claim 2, characterized in that: The temperature of the hot water in step c is 50-90° C.; the amount of the hot water added accounts for 1 / 3-1 / 2 of the mass of the wet tellurium dioxide.

6. The method for producing refined tellurium according to claim 2, characterized in that: In step d, the reaction temperature for preparing tellurium electrodeposition is 90-95° C. and the constant temperature reaction time is 4 hours.

7. The method for producing refined tellurium according to claim 2, characterized in that: In step e, the diameter of the particles filtered by the precision filter is ≤1um.

8. The method for producing refined tellurium according to claim 2, characterized in that: In step e, the circulating fluid is closed periodically during the electrolytic deposition process. The period of periodic closing of the circulating fluid is: once every 3 to 5 days, and each time the circulating fluid is closed for 2 hours.

9. The method for producing refined tellurium according to claim 2, characterized in that: The amount of waste electrolytic liquid generated after electrolysis in step e accounts for 1 / 5 to 1 / 3 of the total amount of liquid in the electrolytic cell.

10. The method for producing refined tellurium according to claim 2, characterized in that: During the electrolytic process in step e, the electrolytic solution with high impurity content at the bottom is regularly extracted and transported to the low-level circulation tank through the electrolytic tank outlet pipe, and dilute sulfuric acid is added to adjust the free alkali content of the electrolytic solution to less than 60g / l; and a precision filter is used to filter the suspended impurities therein.

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