A green and efficient device and method for extracting valuable metals from silver-cadmium materials.

Abstract

This invention relates to a green and efficient apparatus and method for extracting valuable metals from silver-cadmium materials, belonging to the field of non-ferrous metal pyrometallurgical technology. The apparatus includes a support platform, a furnace body on the support platform, and a detachable furnace cover with a sealing ring at the top of the furnace body. It also includes a vacuum pump interface, a negative electrode interface, a silver condensation zone, a cadmium condensation zone, a cadmium oxide condensation zone, a condensation plate cover, a heating element, a positive electrode interface, and a volatilization zone. This invention uses fractional distillation to process the silver-cadmium material. Low-boiling-point cadmium and cadmium oxide volatilize in gaseous form and enter the collection zone, while high-boiling-point silver remains in the volatilization zone. To remove as much cadmium as possible from the silver-cadmium material, a small portion of the silver is mechanically entrained into the collection zone by cadmium vapor.

Description

Technical Field

[0001] This invention relates to a device and method for the green and efficient extraction of valuable metals from silver-cadmium materials, belonging to the field of pyrometallurgical technology for non-ferrous metals. Background Technology

[0002] In daily life, silver-cadmium materials are mainly used to manufacture high-end low-voltage relays, contacts of light and medium load AC contactors, and braking circuit breakers. The silver and cadmium recovered from these raw materials can bring high economic value.

[0003] Currently, there are two main methods for treating silver-cadmium materials: ash blowing and wet processing. Ash blowing involves placing the silver-cadmium material in a smelting furnace and smelting it under oxygen. Cadmium has a much stronger affinity for oxygen than silver, so cadmium first combines with oxygen to form cadmium oxide, which volatilizes into the flue gas, thus separating the silver and cadmium elements. However, this method generates a large amount of cadmium oxide flue gas, resulting in low economic value and serious safety hazards during production. Wet processing involves placing the silver-cadmium material in sulfuric acid. Cadmium dissolves in sulfuric acid, while silver does not. After filtration, the filter residue is smelted to obtain metallic silver. Zinc is added to the supernatant for displacement to obtain sponge cadmium, which is then electrowinning to obtain metallic cadmium. This method generates a large amount of acidic wastewater, and the production process is lengthy and requires poor conditions. The environmental problems caused by these two methods severely restrict the recovery of silver-cadmium materials. Chinese Patent CN1015913B discloses a method for extracting silver-cadmium materials from silver cadmium oxide. This method uses silver cadmium oxide as a raw material, injects hydrogen, and heats it to form silver-cadmium materials. This method can recover all silver and cadmium from silver cadmium oxide materials. Chinese Patent Publication No. CN208857047U discloses a waste liquid treatment device containing silver and cadmium. This waste liquid treatment device includes a fixed support, a first reactor, and a second reactor. The device can effectively treat industrial waste liquid through reduction and neutralization measures, meet the COD determination standards, and recover useful substances.

[0004] In summary, existing methods for treating silver-cadmium materials generally suffer from significant environmental impact, the generation of large amounts of toxic substances during the production process, and low efficiency.

[0005] Therefore, there is an urgent need for a clean and efficient method for recycling silver-cadmium materials. Summary of the Invention

[0006] To address the problems and shortcomings of the existing technology, this invention provides a green and efficient apparatus and method for the extraction of valuable metals from silver-cadmium materials. This invention employs fractional distillation to process silver-cadmium materials. Low-boiling-point cadmium and cadmium oxide volatilize in gaseous form and enter the collection zone, while high-boiling-point silver remains in the volatilization zone. To remove as much cadmium as possible from the silver-cadmium materials, a small portion of silver is mechanically entrained into the collection zone by cadmium vapor. This invention is achieved through the following technical solution.

[0007] A device for the green and efficient extraction of valuable metals from silver-cadmium materials includes a support platform 2, a furnace body 1 on the support platform 2, and a detachable furnace cover 11 with a sealing ring at the top of the furnace body 1. It also includes a vacuum pump interface 3, a negative electrode interface 6, a silver condensation zone 7, a cadmium condensation zone 8, a cadmium oxide condensation zone 9, a condensation plate cover 10, a heating element 13, a positive electrode interface 14, and a volatilization zone 17. The furnace body 1 is equipped with a vacuum pump interface 3. From bottom to top, the volatilization zone 17, silver condensation zone 7, cadmium condensation zone 8, cadmium oxide condensation zone 9, and condensation plate cover 10 are arranged inside the furnace body 1. Each of the volatilization zone 17, silver condensation zone 7, cadmium condensation zone 8, and cadmium oxide condensation zone 9 is equipped with an independent heating element 13, and each heating element 13 has a negative electrode interface 6 and a positive electrode interface 14 at both ends.

[0008] The evaporation zone 17 is composed of a single crucible, and a vacuum port is provided on the evaporation zone 17;

[0009] Silver condensation zone 7 and cadmium condensation zone 8 are composed of multiple stacked collection trays;

[0010] Cadmium oxide condensation zone 9 consists of a separate cadmium oxide collector;

[0011] The volatile zone 17, silver condensation zone 7, cadmium condensation zone 8, and cadmium oxide condensation zone 9 have the same diameter and can be spliced ​​together into a whole.

[0012] The furnace body 1 and furnace cover 11 are equipped with a water cooling circulation system. The lower side of the furnace body 1 is provided with a water cooling inlet 5, and the upper side of the furnace body 1 is provided with a water cooling outlet 12. The top two sides of the furnace cover 11 are respectively provided with a water cooling inlet 5 and a water cooling outlet 12.

[0013] The bottom of the evaporation zone 17 is provided with a thermocouple 4, and the silver condensation zone 7, cadmium condensation zone 8 and cadmium oxide condensation zone 9 are all provided with thermocouple access windows 15 and equipped with thermocouples 4.

[0014] The silver condensation zone 7 is composed of five to seven stacked collection trays; the lower part of the silver condensation zone 7 is composed of two to three stacked inclined collection trays, and the upper part is composed of three to four stacked flat collection trays.

[0015] The bottom cross-section of the inclined plate collecting dish in the silver condensation zone 7 is a triangular-shaped inclined surface with a slope of 10% to 20%; the upper part of the flat plate collecting dish is open, and the lower part has a circular notch, the diameter of which is 1 / 4 of the diameter of the flat plate collecting dish.

[0016] The cadmium condensation zone 8 is composed of five stacked collection trays. The lower part of the cadmium condensation zone 8 is composed of two stacked inclined collection trays, and the upper part is composed of three stacked flat collection trays.

[0017] The upper part of the flat plate collecting dish of the cadmium condensation zone 8 and the collector of the cadmium oxide condensation zone 9 are open, and the lower part has a circular notch with a diameter of 1 / 4 of the diameter of the flat plate collecting dish. There is a cylindrical baffle around the notch to prevent the condensed liquid cadmium from flowing back. The inner diameter of the baffle is the same as the diameter of the notch of the flat plate collecting dish, and the height is 1 / 3 of the height of the flat plate collecting dish.

[0018] A method for applying a device for the green and efficient extraction of valuable metals from silver-cadmium materials includes the following steps: placing the silver-cadmium material in the volatilization zone 17 and evacuating it to a vacuum of 5-20 Pa; heating it to a temperature ≥1000℃ at a heating rate of less than 20℃ / min; holding it at this temperature for 60-240 min; when the temperature drops to 50℃, turning off the vacuum pump; removing the volatilization zone and the condensation zone; and collecting the products from the volatilization zone, the silver condensation zone 7, the cadmium condensation zone 8, and the cadmium oxide condensation zone 9.

[0019] The Cd content in the silver-cadmium material is ≤40wt%.

[0020] The silver condensation zone 7 has a temperature gradient of 1000–800°C from bottom to top, the cadmium condensation zone 8 has a temperature gradient of 800–500°C from bottom to top, and the cadmium oxide condensation zone 9 has a temperature gradient of 200–500°C.

[0021] The beneficial effects of this invention are:

[0022] (1) The raw materials of the present invention are highly adaptable and have a wide processing range. It can process various materials of AgCd (Cd≤40%).

[0023] (2) After vacuum volatilization treatment, the silver-cadmium material of the present invention can reduce the cadmium content in silver to below 0.001% and the silver content in cadmium to below 0.01%, while obtaining cadmium oxide.

[0024] (3) The purity of cadmium oxide in this invention is ≥95%. The direct recovery rate and recovery rate of silver and cadmium are both above 99%; the recovery rate of silver and cadmium is high and the separation effect is good.

[0025] (4) This invention is green and efficient, with no "three wastes" generated during the production process, making it environmentally friendly. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the device structure of the present invention;

[0027] Figure 2 This is a cross-sectional view of the inclined plate collection disk in the silver collection area of ​​the present invention;

[0028] Figure 3 This is a cross-sectional view of the silver collection area flat plate of the present invention;

[0029] Figure 4 This is a cross-sectional view of the cadmium collection area flat plate of the present invention;

[0030] Figure 5 This is a cross-sectional view of the cadmium oxide collection area flat plate of the present invention.

[0031] In the diagram: 1-furnace body, 2-support platform, 3-vacuum pump interface, 4-thermocouple, 5-water cooling inlet, 6-negative electrode interface, 7-silver condensation zone, 8-cadmium condensation zone, 9-cadmium oxide condensation zone, 10-condensation plate cover, 11-furnace cover, 12-water cooling outlet, 13-heating element, 14-positive electrode interface, 15-thermocouple connection window, 16-insulation felt, 17-volatile zone. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] like Figures 1 to 5 As shown, the device for the green and efficient extraction of valuable metals from silver-cadmium materials includes a support platform 2, a furnace body 1 on the support platform 2, and a detachable furnace cover 11 with a sealing ring on the top of the furnace body 1. It also includes a vacuum pump interface 3, a negative electrode interface 6, a silver condensation zone 7, a cadmium condensation zone 8, a cadmium oxide condensation zone 9, a condensation plate cover 10, a heating element 13, a positive electrode interface 14, and a volatilization zone 17. The furnace body 1 is equipped with a vacuum pump interface 3, which can be connected to an external vacuum pump. From bottom to top, the furnace body 1 contains the volatilization zone 17, the silver condensation zone 7, the cadmium condensation zone 8, the cadmium oxide condensation zone 9, and the condensation plate cover 10. Each of the volatilization zone 17, the silver condensation zone 7, the cadmium condensation zone 8, and the cadmium oxide condensation zone 9 has an independent heating element 13. Each heating element 13 has a negative electrode interface 6 and a positive electrode interface 14 at both ends. The negative electrode interface 6 is connected to the negative terminal of the power supply, and the positive electrode interface 14 is connected to the positive terminal of the power supply, allowing the graphite electrode material of the heating element 13 to be heated by electricity.

[0034] The evaporation zone 17 is composed of a single crucible, and a vacuum port is provided on the evaporation zone 17;

[0035] Silver condensation zone 7 and cadmium condensation zone 8 are composed of multiple stacked collection trays;

[0036] Cadmium oxide condensation zone 9 consists of a separate cadmium oxide collector;

[0037] The volatile zone 17, silver condensation zone 7, cadmium condensation zone 8, and cadmium oxide condensation zone 9 have the same diameter and can be spliced ​​together into a whole.

[0038] The furnace body 1 and the furnace cover 11 are equipped with a water cooling circulation system. The lower side of the furnace body 1 is provided with a water cooling inlet 5, and the upper side of the furnace body 1 is provided with a water cooling outlet 12. The top two sides of the furnace cover 11 are respectively provided with a water cooling inlet 5 and a water cooling outlet 12.

[0039] The bottom of the volatile zone 17 is equipped with a thermocouple 4, and the silver condensation zone 7, cadmium condensation zone 8, and cadmium oxide condensation zone 9 are all equipped with thermocouple access windows 15 and thermocouples 4 are installed.

[0040] The silver condensation zone 7 consists of five to seven stacked collection trays; the lower part of the silver condensation zone 7 consists of two to three stacked inclined collection trays, and the upper part consists of three to four stacked flat collection trays.

[0041] The bottom cross-section of the inclined plate collecting dish in silver condensation zone 7 is a triangular-shaped slope with a gradient of 10% to 20%. The upper part of the flat plate collecting dish is open, and the lower part has a circular notch. The diameter of the notch is 1 / 4 of the diameter of the flat plate collecting dish.

[0042] The cadmium condensation zone 8 is composed of five stacked collection trays. The lower part of the cadmium condensation zone 8 is composed of two stacked inclined collection trays, and the upper part is composed of three stacked flat collection trays.

[0043] The cadmium condensation zone 8 has an open upper part for the flat plate collecting dish and the cadmium oxide condensation zone 9 for the collector. The lower part has a circular notch with a diameter of 1 / 4 of the diameter of the flat plate collecting dish. There is a cylindrical baffle around the notch to prevent the condensed liquid cadmium from flowing back. The inner diameter of the baffle is the same as the diameter of the notch on the flat plate collecting dish, and the height is 1 / 3 of the height of the flat plate collecting dish.

[0044] Example 1

[0045] The application method of this device for the green and efficient extraction of valuable metals from silver-cadmium materials includes the following steps:

[0046] Step 1: Place 50g of silver-cadmium material (composition shown in Table 1) into the evaporation zone 17, and then cover it with the silver condensation zone 7, cadmium condensation zone 8, cadmium oxide condensation zone 9 and condensation plate cover 10 in sequence, and assemble them into a whole; open the furnace cover 11, place the whole into the furnace body 1, and close the furnace cover 11.

[0047] Table 1 Raw Material Composition

[0048]

[0049] Step 2: Connect an external vacuum pump to the vacuum pump interface 3 of the furnace body 1, and control the overall vacuum degree of the furnace body 1 and the volatilization zone 17 at 5-20 Pa. Heat the furnace body 1 and the volatilization zone 17 to 1000℃ at a heating rate of 10℃ / min, and hold the temperature for 60 min. During this process, control the temperature gradient of the silver condensation zone 7 from bottom to top to be 1000-800℃, the cadmium condensation zone 8 from bottom to top to be 800-500℃, and the cadmium oxide condensation zone 9 to be 200-500℃.

[0050] After the reaction was completed, the products in the volatile zone 17, silver condensation zone 7, cadmium condensation zone 8, and cadmium oxide condensation zone 9 were removed. The product composition is shown in Table 2.

[0051] Table 2 Product Composition

[0052]

[0053] Comparative Example 1

[0054] The application method of this device for the green and efficient extraction of valuable metals from silver-cadmium materials includes the following steps:

[0055] Step 1: Place 50g of silver-cadmium material (composition shown in Table 1) into the evaporation zone 17, and then cover it with the silver condensation zone 7, cadmium condensation zone 8, cadmium oxide condensation zone 9 and condensation plate cover 10 in sequence, and assemble them into a whole; open the furnace cover 11, place the whole into the furnace body 1, and close the furnace cover 11.

[0056] Step 2: Connect an external vacuum pump to the vacuum pump interface 3 of the furnace body 1, and control the overall vacuum degree of the furnace body 1 and the volatilization zone 17 at 5-20 Pa. Heat the furnace body 1 and the volatilization zone 17 to 600°C at a heating rate of 10°C / min, and hold the temperature for 60 min. During this process, control the temperature gradient of the silver condensation zone 7 from bottom to top to be 1000-800°C, the cadmium condensation zone 8 from bottom to top to be 800-500°C, and the cadmium oxide condensation zone 9 to be 200-500°C.

[0057] After the reaction was completed, the products in the volatile zone 17, silver condensation zone 7, cadmium condensation zone 8, and cadmium oxide condensation zone 9 were removed. The product composition is shown in Table 3.

[0058] Table 3 Product Composition

[0059]

[0060] Comparative Example 2

[0061] The application method of this device for the green and efficient extraction of valuable metals from silver-cadmium materials includes the following steps:

[0062] Step 1: Place 50g of silver-cadmium material (composition shown in Table 1) into the evaporation zone 17, and then cover it with the silver condensation zone 7, cadmium condensation zone 8, cadmium oxide condensation zone 9 and condensation plate cover 10 in sequence, and assemble them into a whole; open the furnace cover 11, place the whole into the furnace body 1, and close the furnace cover 11.

[0063] Step 2: Connect an external vacuum pump to vacuum pump interface 3 of furnace body 1, and control the overall vacuum degree of furnace body 1 and volatilization zone 17 at 5-20 Pa. Heat the furnace body 1 and volatilization zone 17 to 800℃ at a heating rate of 10℃ / min, and hold the temperature for 60 min. During this process, control the temperature gradient of silver condensation zone 7 from bottom to top to be 1000-800℃, control the temperature gradient of cadmium condensation zone 8 from bottom to top to be 800-500℃, and control the temperature gradient of cadmium oxide condensation zone 9 to be 200-500℃.

[0064] After the reaction was completed, the products in the volatile zone 17, silver condensation zone 7, cadmium condensation zone 8, and cadmium oxide condensation zone 9 were removed. The product composition is shown in Table 4.

[0065] Table 4 Product Composition

[0066]

[0067] As can be seen from Example 1 and Comparative Examples 1 to 2, the higher the temperature of the evaporation zone, the better the separation effect of the silver-cadmium material, the more efficiently cadmium can be removed from the silver-cadmium material, and the higher the silver content of the product obtained in the silver collection zone.

[0068] Example 2

[0069] The application method of this device for the green and efficient extraction of valuable metals from silver-cadmium materials includes the following steps:

[0070] Step 1: Place 50g of silver-cadmium material (composition shown in Table 1) into the evaporation zone 17, and then cover it with the silver condensation zone 7, cadmium condensation zone 8, cadmium oxide condensation zone 9 and condensation plate cover 10 in sequence, and assemble them into a whole; open the furnace cover 11, place the whole into the furnace body 1, and close the furnace cover 11.

[0071] Step 2: Connect an external vacuum pump to the vacuum pump interface 3 of the furnace body 1, and control the overall vacuum degree of the furnace body 1 and the volatilization zone 17 at 5-20 Pa. Heat the furnace body 1 and the volatilization zone 17 to 1000℃ at a heating rate of 10℃ / min, and hold the temperature for 120 min. During this process, control the temperature gradient of the silver condensation zone 7 from bottom to top to be 1000-800℃, the cadmium condensation zone 8 from bottom to top to be 800-500℃, and the cadmium oxide condensation zone 9 to be 200-500℃.

[0072] After the reaction was completed, the products in the volatile zone 17, silver condensation zone 7, cadmium condensation zone 8, and cadmium oxide condensation zone 9 were removed. The product composition is shown in Table 5.

[0073] Table 5 Product Composition

[0074]

[0075] Example 3

[0076] The application method of this device for the green and efficient extraction of valuable metals from silver-cadmium materials includes the following steps:

[0077] Step 1: Place 50g of silver-cadmium material (composition shown in Table 1) into the evaporation zone 17, and then cover it with the silver condensation zone 7, cadmium condensation zone 8, cadmium oxide condensation zone 9 and condensation plate cover 10 in sequence, and assemble them into a whole; open the furnace cover 11, place the whole into the furnace body 1, and close the furnace cover 11.

[0078] Step 2: Connect an external vacuum pump to the vacuum pump interface 3 of the furnace body 1, and control the overall vacuum degree of the furnace body 1 and the volatilization zone 17 at 5-20 Pa. Heat the furnace body 1 and the volatilization zone 17 to 1000℃ at a heating rate of 10℃ / min, and hold the temperature for 240 min. During this process, control the temperature gradient of the silver condensation zone 7 from bottom to top to be 1000-800℃, the cadmium condensation zone 8 from bottom to top to be 800-500℃, and the cadmium oxide condensation zone 9 to be 200-500℃.

[0079] After the reaction was completed, the products in the volatile zone 17, silver condensation zone 7, cadmium condensation zone 8, and cadmium oxide condensation zone 9 were removed. The product composition is shown in Table 6.

[0080] Table 6 Product Composition

[0081]

[0082] Example 4

[0083] The application method of this device for the green and efficient extraction of valuable metals from silver-cadmium materials includes the following steps:

[0084] Step 1: Place 50g of silver-cadmium material (composition shown in Table 7) into the evaporation zone 17, and then cover it with the silver condensation zone 7, cadmium condensation zone 8, cadmium oxide condensation zone 9 and condensation plate cover 10 in sequence, and assemble them into a whole; open the furnace cover 11, place the whole into the furnace body 1, and close the furnace cover 11.

[0085] Table 7 Raw Material Composition

[0086]

[0087] Step 2: Connect an external vacuum pump to the vacuum pump interface 3 of the furnace body 1, and control the overall vacuum degree of the furnace body 1 and the volatilization zone 17 at 5-20 Pa. Heat the furnace body 1 and the volatilization zone 17 to 1000℃ at a heating rate of 18℃ / min, and hold the temperature for 120 min. During this process, control the temperature gradient of the silver condensation zone 7 from bottom to top to be 1000-800℃, the cadmium condensation zone 8 from bottom to top to be 800-500℃, and the cadmium oxide condensation zone 9 to be 200-500℃.

[0088] After the reaction was completed, the products in the volatile zone 17, silver condensation zone 7, cadmium condensation zone 8, and cadmium oxide condensation zone 9 were removed. The product composition is shown in Table 8.

[0089] Table 8 Product Composition

[0090]

[0091] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. An application method for a device for the green and efficient extraction of valuable metals from silver-cadmium materials, characterized in that: The device includes a support platform (2), a furnace body (1) on the support platform (2), and a detachable furnace cover (11) with a sealing ring on the top of the furnace body (1). It is characterized by: a vacuum pump interface (3), a negative electrode interface (6), a silver condensation zone (7), a cadmium condensation zone (8), a cadmium oxide condensation zone (9), a condensation plate cover (10), a heating element (13), a positive electrode interface (14), and a volatilization zone (17). The furnace body (1) is provided with a vacuum pump interface (3). The volatilization zone (17), the silver condensation zone (7), the cadmium condensation zone (8), the cadmium oxide condensation zone (9), and the condensation plate cover (10) are arranged in sequence from bottom to top inside the furnace body (1). The volatilization zone (17), the silver condensation zone (7), the cadmium condensation zone (8), and the cadmium oxide condensation zone (9) are each provided with an independent heating element (13). Each heating element (13) in each zone is provided with a negative electrode interface (6) and a positive electrode interface (14) at both ends. The evaporation zone (17) is composed of a single crucible, and a vacuum port is provided on the evaporation zone (17); The silver condensation zone (7) and the cadmium condensation zone (8) are composed of multiple stacked collection trays; The cadmium oxide condensation zone (9) consists of a single cadmium oxide collector; The volatile zone (17), silver condensation zone (7), cadmium condensation zone (8), and cadmium oxide condensation zone (9) have the same diameter and can be spliced ​​together into a whole; Place the silver-cadmium material in the volatilization zone (17) and evacuate it to 5~20 Pa. Heat it to ≥1000℃ at a heating rate of less than 20℃ / min and keep it at that temperature for 60~240 min. When the temperature drops to 50℃, turn off the vacuum pump, remove the volatilization zone and the condensation zone, and collect the products from the volatilization zone, the silver condensation zone (7), the cadmium condensation zone (8), and the cadmium oxide condensation zone (9). The silver-cadmium material contains Cd ≤ 40 wt%.

2. The application method according to claim 1, characterized in that: The furnace body (1) and furnace cover (11) are equipped with a water cooling circulation system. The lower side of the furnace body (1) is equipped with a water cooling inlet (5) and the upper side of the furnace body (1) is equipped with a water cooling outlet (12). The top two sides of the furnace cover (11) are respectively equipped with a water cooling inlet (5) and a water cooling outlet (12).

3. The application method according to claim 1, characterized in that: The bottom of the evaporation zone (17) is provided with a thermocouple (4), and the silver condensation zone (7), cadmium condensation zone (8) and cadmium oxide condensation zone (9) are all provided with thermocouple access windows (15) and thermocouples (4) are installed.

4. The application method according to claim 1, characterized in that: The silver condensation zone (7) is composed of five to seven layers of stacked collection trays; the lower part of the silver condensation zone (7) is composed of two to three layers of stacked inclined collection trays, and the upper part is composed of three to four layers of flat collection trays.

5. The application method according to claim 4, characterized in that: The bottom cross section of the inclined plate collecting plate of the silver condensation zone (7) is similar to a triangular inclined surface with a slope of 10%~20%; the upper part of the flat plate collecting plate is open and the lower part has a circular notch, the diameter of the notch of the flat plate collecting plate is 1 / 4 of the diameter of the flat plate collecting plate.

6. The application method according to claim 1, characterized in that: The cadmium condensation zone (8) is composed of five stacked collection trays. The lower part of the cadmium condensation zone (8) is composed of two stacked inclined collection trays, and the upper part is composed of three stacked flat collection trays.

7. The application method according to claim 6, characterized in that: The upper part of the flat plate collecting dish of the cadmium condensation zone (8) and the collector of the cadmium oxide condensation zone (9) are open, and the lower part has a circular notch with a diameter of 1 / 4 of the diameter of the flat plate collecting dish. There is a cylindrical baffle around the notch to prevent the condensed liquid cadmium from flowing back. The inner diameter of the baffle is the same as the diameter of the notch of the flat plate collecting dish, and the height is 1 / 3 of the height of the flat plate collecting dish.

8. The application method according to claim 7, characterized in that: The silver condensation zone (7) has a temperature gradient of 1000~800℃ from bottom to top, the cadmium condensation zone (8) has a temperature gradient of 800~500℃ from bottom to top, and the cadmium oxide condensation zone (9) has a temperature gradient of 200~500℃.

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