Molten salt medium for recovering and reducing metal zinc and preparation method and metallurgical method thereof

Abstract

The invention discloses a molten salt medium for recovering and reducing metal zinc as well as a preparation method and application of the molten salt medium. The molten salt medium disclosed by the invention comprises the following components in percentage by mass: 50%-83% of ZnCl2, 15%-48% of fluxing chlorine salt, 0.5%-5% of a viscosity modifier and 1%-3% of a volatile inhibitor, the preparation method comprises the steps of segmented dehydration, inert atmosphere mixing and melting, shock cooling forming and the like. The fused salt medium can be applied to condensation, liquefaction and trapping of zinc steam in Zn + CO mixed gas generated by carbon thermal reduction, zinc oxidation can be prevented, pipeline blockage is avoided, the purity of collected zinc reaches 99.5% or above, energy consumption is reduced by 12%-15%, and the fused salt medium is suitable for efficient recovery of zinc in zinc-containing dust.

Description

Technical Field

[0001] This invention relates to the field of functional molten salt materials technology, specifically to a molten salt medium for recovering and reducing metallic zinc, and its preparation method and metallurgical method. Background Technology

[0002] In the fields of zinc smelting and zinc-containing waste recycling, carbothermal reduction has become the most widely used mainstream technology due to its significant advantages of simple process and low cost. This technology uses carbonaceous materials such as coke as a reducing agent, which reacts chemically with zinc-containing materials under high-temperature conditions, ultimately generating a mixed gas containing carbon monoxide and zinc vapor. In this process, the efficiency of zinc vapor collection not only directly determines the overall efficiency of the production process and affects the metal output per unit time, but also plays a crucial role in the quality of the final solid metal product. If zinc vapor cannot be collected efficiently, it will not only waste zinc resources, but may also lead to a decrease in product purity due to impurities, thus affecting the subsequent application results.

[0003] Traditional zinc vapor collection methods in the industry commonly employ splash-type zinc rain condensation and lead rain condensation technologies. Splash-type zinc rain condensation involves high-speed splashing of liquid zinc into "zinc rain," allowing zinc vapor to condense into liquid zinc upon contact and be collected. Lead rain condensation uses liquid lead sprayed into "lead rain," causing the zinc vapor to separate from the lead due to their density difference after condensation. These two technologies have long supported industry production. However, due to the reactive chemical properties of zinc, zinc vapor readily reacts with oxygen upon contact with air, reducing the purity of the zinc product and potentially clogging equipment, increasing maintenance costs. Furthermore, zinc vapor is volatile, and traditional collection processes often suffer from poor sealing and airflow control, leading to zinc mist escape. These problems hinder the development of this technology, necessitating the development of new collection technologies to improve the quality and efficiency of zinc recovery. Summary of the Invention

[0004] To overcome the shortcomings or defects in the prior art, the purpose of this invention is to provide a molten salt medium for recovering and reducing metallic zinc, as well as its preparation method and metallurgical method. The molten salt medium provided by this invention condenses zinc vapor, improves the condensation and recovery method of zinc vapor, increases the recovery rate and purity of zinc, and thus reduces energy consumption.

[0005] The present invention provides a molten salt medium for recovering and reducing metallic zinc, comprising, by mass percentage: 50% to 83% zinc chloride, 15% to 48% fluxing chloride, 0.5% to 5% viscosity modifier and 1% to 3% volatility inhibitor.

[0006] The fluxing chloride salt includes sodium chloride and potassium chloride, with a mass ratio of sodium chloride to potassium chloride of (0.5~2):1.

[0007] The viscosity modifier includes one or both of AlCl3 and FeCl3.

[0008] The volatile inhibitors include one or both of CaCl2 and MgCl2.

[0009] This invention provides a method for preparing the above-mentioned molten salt medium for recovering and reducing metallic zinc, comprising: Zinc chloride and fluxing chloride salts were dehydrated separately in a vacuum environment; In an inert atmosphere, dehydrated zinc chloride and fluxing chloride salt are mixed and heated to obtain a molten mixture. A viscosity modifier and a volatility inhibitor are added to the molten mixture and mixed evenly. The mixture is then aged at a constant temperature to obtain a molten salt medium. Molten salt medium is obtained by cooling the molten salt medium with liquid nitrogen.

[0010] The dehydration process is carried out in stages. The first stage is held at 100~150℃ for 4~5 hours; the second stage is held at 200~250℃ for 2~3 hours.

[0011] The heating temperature is 400~500℃, and the aging time is 1~2 hours.

[0012] Molten salt medium is obtained by cooling the molten salt medium to -40~-50℃ with liquid nitrogen.

[0013] The present invention also provides a method for metallurgical zinc recovery, wherein the molten salt medium used for recovering reduced zinc is heated to a molten state, and the mixed gas of reduced metal generated during the process of treating zinc-containing waste by carbothermal reduction is passed into the molten salt medium, and the zinc vapor is condensed to obtain reduced zinc.

[0014] The temperature of the molten state is 400~500℃.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The molten salt medium for recovering and reducing metallic zinc provided by this invention is composed of chlorides. The melting point of the compounded chloride molten salt medium is generally lower than that of a single chloride, and the low melting point of the compounded chloride molten salt medium can meet the temperature required for the condensation of zinc vapor. Simultaneously, a viscosity modifier is added to optimize the flowability of the molten salt medium and ensure heat transfer efficiency; a volatility inhibitor is added to suppress the volatilization of the molten salt medium components and maintain the stability of the molten salt medium's performance. When used for recovering and reducing metallic zinc, the molten salt medium has excellent oxygen-isolating ability. Its molten state can form a dense covering layer, encapsulating the condensed zinc liquid, preventing zinc vapor from contacting oxygen in the air and undergoing an oxidation reaction, thus improving the stability of zinc purity to above 99.5%. The molten salt medium has good heat storage performance, and can recover and utilize the sensible heat of the gas, reducing system energy consumption by approximately 12%-15%.

[0016] The preparation method of this molten salt medium first involves vacuum drying the raw materials to remove moisture, avoid hydrolysis reactions that generate impurities, and prevent the raw materials from clumping and decomposing. Then, the materials are mixed in an inert atmosphere to prevent the formation of oxidation and carbonate impurities, ensuring the purity and performance stability of the molten salt medium. Finally, liquid nitrogen is used for rapid cooling, which can ensure the performance of the molten salt medium and form fine solid particles, thereby improving cooling efficiency.

[0017] The metallurgical zinc recovery method provided by this invention uses the aforementioned molten salt medium heated to a molten state. The high density and low permeability of the molten salt medium can isolate oxygen, effectively preventing zinc oxidation, improving the purity and recovery rate of zinc products, and protecting equipment from corrosion. Moreover, zinc vapor is directly liquefied in the molten salt medium, eliminating the need for long-distance pipeline transportation, which can alleviate pipeline crystallization and blockage problems. The equipment can operate continuously for more than 30 days. By precisely controlling the molten salt temperature and gas flow rate, the zinc vapor absorption efficiency can be dynamically adjusted to adapt to different raw material compositions and production capacity requirements, ensuring process stability. In addition, the molten salt can adsorb and encapsulate zinc vapor to liquefy it, reducing zinc diffusion and loss, while CO gas can be centrally recovered and reused, meeting clean production requirements and reducing environmental pressure and compliance costs. Detailed Implementation

[0018] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0019] In this invention, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0020] In this invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0021] It should be understood that in various embodiments of the present invention, the order of the above-mentioned processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0022] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0023] The weights of the relevant components mentioned in the embodiments of this invention can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this invention is within the scope disclosed in the embodiments of this invention. Specifically, the mass described in the embodiments of this invention can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0024] The molten salt medium for recovering and reducing metallic zinc provided by the present invention comprises, by mass percentage: 50% to 83% zinc chloride, 15% to 48% fluxing chloride, 0.5% to 5% viscosity modifier and 1% to 3% volatility inhibitor.

[0025] In some embodiments, the fluxing chloride salt comprises sodium chloride and potassium chloride, with a mass ratio of sodium chloride to potassium chloride of (0.5~2):1. By adjusting the ratio of the two, the melting point and viscosity of the molten salt medium are synergistically optimized.

[0026] In some embodiments, the viscosity modifier is one or more of AlCl3 or FeCl3; the volatility inhibitor is one or more of CaCl2 or MgCl2.

[0027] The method for preparing a molten salt medium for recovering and reducing metallic zinc provided by the present invention includes: Zinc chloride and fluxing chloride salts were dehydrated separately in a vacuum environment; In an inert atmosphere, dehydrated zinc chloride and fluxing chloride salt are mixed and heated to obtain a molten mixture. A viscosity modifier and a volatility inhibitor are added to the molten mixture and mixed evenly. After aging, a molten salt medium is obtained.

[0028] Molten salt medium is poured into a stainless steel mold and cooled with liquid nitrogen to obtain molten salt medium. The molten salt medium is an amorphous solid particle and is vacuum-sealed in an aluminum-plastic composite bag for later use to prevent the molten salt medium from deteriorating.

[0029] In some embodiments, the dehydration process is carried out in stages, with the first stage being kept at 100~150℃ for 4~5 hours and the second stage being kept at 200~250℃ for 2~3 hours.

[0030] In some embodiments, the heating temperature is 400~500℃, and the aging time is 1~2h.

[0031] In some embodiments, the molten salt medium is obtained by cooling the molten salt medium to -40 to -50°C using liquid nitrogen.

[0032] The method for recovering zinc by metallurgy provided by the present invention involves heating the molten salt medium for recovering reduced zinc metal prepared by the above preparation method to a molten state, and then passing the mixed gas of reduced metal generated during the treatment of zinc-containing waste by carbothermal reduction into the molten salt medium, and the zinc vapor condenses to obtain reduced zinc metal.

[0033] In some embodiments, the temperature of the molten state is 400~500°C, preferably 430~480°C. Within this temperature range, the liquefaction efficiency of zinc vapor in the molten salt medium can be improved.

[0034] In the following embodiments, unless otherwise specified, all materials used can be obtained through ordinary channels; the testing methods used are conventional methods in the art.

[0035] Example 1 By mass percentage, the molten salt medium in this embodiment comprises: 65% ZnCl2, 30% KCl + NaCl (mass ratio of 1:1), 3% AlCl3, and 2% CaCl2.

[0036] Preparation process: ZnCl2, KCl, and NaCl were dehydrated in stages in a vacuum drying oven, first at 100℃ for 4 hours, then at 200℃ for 2 hours. In a nitrogen-filled glove box (H2O < 1 ppm, O2 < 1 ppm), the dehydrated ZnCl2, KCl, and NaCl were mixed in the above proportions, then heated to 500℃ and stirred for 2 hours to obtain a molten mixture. AlCl3 and CaCl2 were added to the molten mixture, and the mixture was aged at a constant temperature for 1 hour to obtain a molten salt medium. The molten salt medium was poured into a stainless steel mold and quenched to -50℃ with liquid nitrogen to obtain the molten salt medium.

[0037] Application: The molten salt medium prepared in this embodiment is added to the molten salt pool and heated to 450°C. The reducing metal mixed gas (Zn+CO) generated during the process of treating zinc-containing waste by carbothermal reduction is then introduced into the molten salt medium. The zinc vapor is condensed to obtain zinc liquid deposition. After testing, the purity of zinc reaches 99.6%, the system energy consumption is reduced by 14%, and the equipment runs continuously for 30 days without any abnormalities.

[0038] Example 2 By mass percentage, the molten salt medium in this embodiment comprises: 50% ZnCl2, 45% KCl + NaCl (mass ratio of the two is 2:1), 3% FeCl3, and 2% MgCl2.

[0039] Preparation process: ZnCl2, KCl, and NaCl were dehydrated in stages in a vacuum drying oven, first at 120℃ for 4 hours, then at 220℃ for 2 hours. In a nitrogen-filled glove box (H2O < 1 ppm, O2 < 1 ppm), the dehydrated ZnCl2, KCl, and NaCl were mixed in the above proportions, then heated to 500℃ and stirred for 2 hours to obtain a molten mixture. FeCl3 and MgCl2 were added to the molten mixture, and the mixture was aged at a constant temperature for 1 hour to obtain a molten salt medium. The molten salt medium was poured into a stainless steel mold and quenched to -40℃ with liquid nitrogen to obtain the molten salt medium.

[0040] Application: The molten salt medium prepared in this embodiment is added to the molten salt pool and heated to 430°C. The reducing metal mixed gas (Zn+CO) generated during the process of treating zinc-containing waste by carbothermal reduction is passed into the molten salt medium. The zinc vapor is condensed to obtain zinc liquid deposition, and the purity of zinc reaches 99.5%. The system energy consumption is reduced by 13% compared with the traditional process.

[0041] Example 3 By mass percentage, the molten salt medium in this embodiment comprises: 83% ZnCl2, 15% KCl + NaCl (mass ratio of the two is 1:2), 1% AlCl3, and 1% CaCl2.

[0042] Preparation process: ZnCl2, KCl, and NaCl were dehydrated in stages in a vacuum drying oven, first at 150℃ for 4 hours, then at 220℃ for 2 hours. In a nitrogen-filled glove box (H2O < 1 ppm, O2 < 1 ppm), the dehydrated ZnCl2, KCl, and NaCl were mixed in the above proportions, then heated to 400℃ and stirred for 2 hours to obtain a molten mixture. AlCl3 and CaCl2 were added to the molten mixture, and the mixture was aged at a constant temperature for 1 hour to obtain a molten salt medium. The molten salt medium was poured into a stainless steel mold and quenched to -45℃ with liquid nitrogen to obtain the molten salt medium.

[0043] Application: The molten salt medium prepared in this embodiment is added to the molten salt pool and heated to 480°C. The reducing metal mixed gas (Zn+CO) generated during the process of treating zinc-containing waste by carbothermal reduction is then introduced into the molten salt medium. The zinc vapor is condensed to obtain zinc liquid deposition. After testing, the purity of zinc reaches 99.7%, the system energy consumption is reduced by 15%, and the equipment has been running continuously for 32 days with stable condition.

[0044] Example 4 By mass percentage, the molten salt medium in this embodiment comprises: 70% ZnCl2, 25% KCl + NaCl (mass ratio of 1:1), 4% FeCl3, and 1% MgCl2.

[0045] Preparation process: ZnCl2, KCl, and NaCl were dehydrated in stages in a vacuum drying oven, first at 120℃ for 4 hours, then at 220℃ for 2 hours. In a nitrogen-filled glove box (H2O < 1 ppm, O2 < 1 ppm), the dehydrated ZnCl2, KCl, and NaCl were mixed in the above proportions, then heated to 500℃ and stirred for 2 hours to obtain a molten mixture. FeCl3 and MgCl2 were added to the molten mixture, and the mixture was aged at a constant temperature for 1 hour to obtain a molten salt medium. The molten salt medium was poured into a stainless steel mold and quenched to -40℃ with liquid nitrogen to obtain the molten salt medium.

[0046] Application: The molten salt medium prepared in this embodiment is added to the molten salt pool and heated to 500°C. The reducing metal mixed gas (Zn+CO) generated during the process of treating zinc-containing waste by carbothermal reduction is passed into the molten salt medium. The zinc vapor is condensed to obtain zinc liquid deposition. The purity of zinc reaches 99.6%, the system energy consumption is reduced by 14%, and the equipment runs continuously for 31 days without any abnormalities.

[0047] Example 5 By mass percentage, the molten salt medium in this embodiment comprises: 60% ZnCl2, 35% KCl + NaCl (mass ratio of the two is 1:2), 3.5% FeCl3, and 1.5% MgCl2.

[0048] Preparation process: ZnCl2, KCl, and NaCl were dehydrated in stages in a vacuum drying oven, first at 150℃ for 4 hours, then at 250℃ for 2 hours. In a nitrogen-filled glove box (H2O < 1 ppm, O2 < 1 ppm), the dehydrated ZnCl2, KCl, and NaCl were mixed in the above proportions, then heated to 400℃ and stirred for 2 hours to obtain a molten mixture. FeCl3 and MgCl2 were added to the molten mixture, and the mixture was aged at a constant temperature for 1 hour to obtain a molten salt medium. The molten salt medium was poured into a stainless steel mold and quenched to -45℃ with liquid nitrogen to obtain the molten salt medium.

[0049] Application: The molten salt medium prepared in this embodiment is added to the molten salt pool and heated to 400°C. The reducing metal mixed gas (Zn+CO) generated during the process of treating zinc-containing waste by carbothermal reduction is passed into the molten salt medium. The zinc vapor is condensed to obtain zinc liquid deposition, and the purity of zinc reaches 99.5%.

[0050] Example 6 By mass percentage, the molten salt medium in this embodiment comprises: 50% ZnCl2, 48% KCl + NaCl (mass ratio of 1:1), 0.5% FeCl3, and 1.5% MgCl2.

[0051] Preparation process: ZnCl2, KCl, and NaCl were dehydrated in stages in a vacuum drying oven, first at 100℃ for 4 hours, then at 250℃ for 2 hours. In a nitrogen-filled glove box (H2O < 1 ppm, O2 < 1 ppm), the dehydrated ZnCl2, KCl, and NaCl were mixed in the above proportions, then heated to 500℃ and stirred for 2 hours to obtain a molten mixture. FeCl3 and MgCl2 were added to the molten mixture, and the mixture was aged at a constant temperature for 2 hours to obtain a molten salt medium. The molten salt medium was poured into a stainless steel mold and quenched to -50℃ with liquid nitrogen to obtain the molten salt medium.

[0052] Application: The molten salt medium prepared in this embodiment is added to the molten salt pool and heated to 450°C. The reducing metal mixed gas (Zn+CO) generated during the process of treating zinc-containing waste by carbothermal reduction is passed into the molten salt medium. The zinc vapor is condensed to obtain zinc liquid deposition. The purity of zinc reaches 99.6%, the system energy consumption is reduced by 12%, and the equipment runs continuously for 32 days without abnormalities.

[0053] Example 7 By mass percentage, the molten salt medium of this embodiment comprises: 55% ZnCl2, 38% KCl + NaCl (mass ratio of 1:1), 5% FeCl3 and AlCl3 (mass ratio of 1:1), and 2% MgCl2.

[0054] Preparation process: ZnCl2, KCl, and NaCl were dehydrated in stages in a vacuum drying oven, first at 150℃ for 4 hours, then at 200℃ for 2 hours. In a nitrogen-filled glove box (H2O < 1 ppm, O2 < 1 ppm), the dehydrated ZnCl2, KCl, and NaCl were mixed in the above proportions, then heated to 450℃ and stirred for 2 hours to obtain a molten mixture. FeCl3 and MgCl2 were added to the molten mixture, and the mixture was aged at a constant temperature for 1.5 hours to obtain a molten salt medium. The molten salt medium was poured into a stainless steel mold and quenched to -50℃ with liquid nitrogen to obtain the molten salt medium.

[0055] Application: The molten salt medium prepared in this embodiment is added to the molten salt pool and heated to 500°C. The reducing metal mixed gas (Zn+CO) generated during the process of treating zinc-containing waste by carbothermal reduction is then introduced into the molten salt medium. The zinc vapor is condensed to obtain zinc liquid deposition, and the purity of zinc reaches 99.5%. The equipment has been running continuously for 35 days without any abnormalities.

[0056] Example 8 By mass percentage, the composition of the molten salt medium in this embodiment includes: 60% ZnCl2, 34% KCl + NaCl (mass ratio of the two is 2:1), 3% FeCl3, 3% CaCl2 and MgCl2 (mass ratio of the two is 1:1).

[0057] Preparation process: ZnCl2, KCl, and NaCl were dehydrated in stages in a vacuum drying oven, first at 120℃ for 4 hours, then at 250℃ for 2 hours. In a nitrogen-filled glove box (H2O < 1 ppm, O2 < 1 ppm), the dehydrated ZnCl2, KCl, and NaCl were mixed in the above proportions, then heated to 450℃ and stirred for 2 hours to obtain a molten mixture. FeCl3 and MgCl2 were added to the molten mixture, and the mixture was aged at a constant temperature for 1 hour to obtain a molten salt medium. The molten salt medium was poured into a stainless steel mold and quenched to -50℃ with liquid nitrogen to obtain the molten salt medium.

[0058] Application: The molten salt medium prepared in this embodiment is added to the molten salt pool and heated to 400°C. The reducing metal mixed gas (Zn+CO) generated during the process of treating zinc-containing waste by carbothermal reduction is passed into the molten salt medium. The zinc vapor is condensed to obtain zinc liquid deposition, and the purity of zinc reaches 99.7%. The system energy consumption is reduced by 13.2%.

[0059] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still make modifications or equivalent substitutions to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention pending approval.

Claims

1. A molten salt medium for recovering and reducing metallic zinc, characterized in that, By weight percentage, it contains the following components: 50% to 83% zinc chloride, 15% to 48% fluxing chloride salt, 0.5% to 5% viscosity modifier and 1% to 3% volatility inhibitor.

2. The molten salt medium for recovering and reducing metallic zinc according to claim 1, characterized in that, The fluxing chloride salt includes sodium chloride and potassium chloride, with a mass ratio of sodium chloride to potassium chloride of (0.5~2):

1.

3. The molten salt medium for recovering and reducing metallic zinc according to claim 1, characterized in that, The viscosity modifier includes one or both of AlCl3 and FeCl3.

4. The molten salt medium for recovering and reducing metallic zinc according to claim 1, characterized in that, The volatile inhibitors include one or both of CaCl2 and MgCl2.

5. A method for preparing the molten salt medium for recovering and reducing metallic zinc as described in any one of claims 1-4, characterized in that, include: Zinc chloride and fluxing chloride salts were dehydrated separately in a vacuum environment; In an inert atmosphere, dehydrated zinc chloride and fluxing chloride salt are mixed and heated to obtain a molten mixture. A viscosity modifier and a volatility inhibitor are added to the molten mixture and mixed evenly. The mixture is then aged at a constant temperature to obtain a molten salt medium. Molten salt medium is obtained by cooling the molten salt medium with liquid nitrogen.

6. The method for preparing the molten salt medium for recovering and reducing metallic zinc according to claim 5, characterized in that, The dehydration process is carried out in stages. The first stage is held at 100~150℃ for 4~5 hours; the second stage is held at 200~250℃ for 2~3 hours.

7. The method for preparing the molten salt medium for recovering and reducing metallic zinc according to claim 5, characterized in that, The heating temperature is 400~500℃, and the aging time is 1~2 hours.

8. The method for preparing the molten salt medium for recovering and reducing metallic zinc according to claim 5, characterized in that, Molten salt medium is obtained by cooling the molten salt medium to -40~-50℃ using liquid nitrogen.

9. A method for metallurgically recovering zinc, characterized in that, After heating the molten salt medium for recovering reduced zinc as described in any one of claims 1-4 to a molten state, the mixed gas of reduced metals generated during the process of treating zinc-containing waste by carbothermal reduction is passed into the molten salt medium, and the zinc vapor is condensed to obtain reduced zinc.

10. The method for metallurgically recovering zinc according to claim 9, characterized in that, The temperature of the molten state is 400~500℃.