Preparation process of high-purity lead-free zinc powder

Abstract

The invention provides a preparation process of high-purity lead-free zinc powder. A smelting furnace, a zinc flowing pipe, an evaporation tower tray, a gas guide pipe, a condensing device and a grader are included. The condensing device comprises a condensing tower body, a condensing coil pipe and a nitrogen coil pipe, the condensing coil pipe is arranged in the condensing tower body, the nitrogen coil pipe is arranged in a pipe cavity of the condensing coil pipe, the tail end of the nitrogen coil pipe is closed, a plurality of air holes are formed in the nitrogen coil pipe, and the front end of the nitrogen coil pipe penetrates out of the condensing coil pipe and is communicated with a nitrogen device; the invention further provides a preparation method, the lead and iron impurities in the liquid zinc are separated, it is ensured that the lead-free zinc powder is prepared, the purity of the prepared zinc powder is high, the particle size of the prepared zinc powder is small, the system is not prone to being affected by fluctuation of the working condition of zinc steam, and the prepared zinc powder is stable and uniform in particle size and good in condensation effect.

Description

Technical Field

[0001] The invention relates to the technical field of zinc powder preparation, and in particular to a process for preparing high-purity lead-free zinc powder. Background Art

[0002] Zinc powder is a gray powder with strong reducing ability, so it is a very important reducing agent. It is mainly used in zinc-rich coatings and other high-performance coatings such as anti-corrosion and environmental protection. It is also widely used in metallurgy, chemical industry, agriculture and forestry, medicine, dyes, batteries and other industries.

[0003] At present, zinc powder is prepared by evaporation in the industry. The zinc ingot is heated to the melting point in the melting pool and melted into liquid; the liquid zinc flows into the evaporation pool and is isolated from the air, and continues to be heated to the boiling point. The zinc liquid evaporates into a gaseous state and enters the condenser to cool into zinc powder. The generated zinc powder is sorted by a classifier. However, in the industrial production process, the air in the evaporation pool is emptied by filling with nitrogen, and then the liquid zinc liquid is introduced for evaporation. The zinc vapor is condensed to form zinc powder. However, in the long-term collection process of zinc powder, a small amount of air will be mixed into the evaporation pool. Therefore, nitrogen will be introduced into the evaporation pool every 8 hours. There is no way to control when the air enters the evaporation pool in the industry. When there is air mixed into the evaporation pool, oxidation and other reactions occur, resulting in poor purity of the final zinc powder. The existing condensing device often uses jacket cooling, which has a slow cooling speed and is difficult to cool evenly, resulting in uneven zinc powder particles and large particle size. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings in the prior art.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A high-purity lead-free zinc powder preparation process, comprising a melting furnace, a zinc flow pipe, an evaporation tray, an air guide pipe, a condensing device and a classifier; The bottom of the melting furnace is connected to the evaporation tower tray through a zinc flow pipe; The evaporation trays are stacked in multiple layers, each layer of the evaporation trays has a connection port connected to the upper and lower evaporation chambers, the connection ports are staggered left and right, the upper layer of the evaporation trays is provided with a zinc liquid inlet and a steam outlet, and the bottom of the evaporation trays is provided with a waste liquid outlet; the zinc liquid inlet is connected to the melting furnace through a zinc flow pipe; The steam outlet is connected to the condensing device through an air guide pipe, and a discharge port is arranged below the condensing device. The discharge port collects zinc powder through a collecting device and then transfers it to a classifier to classify the particle size of the zinc powder. The condensing device comprises a condensing tower body, a condensing coil and a nitrogen coil. The condensing coil is arranged in the condensing tower body, the nitrogen coil is arranged in the tube cavity of the condensing coil, the end of the nitrogen coil is closed, a plurality of air holes are arranged on the nitrogen coil, and the front end of the nitrogen coil passes through the condensing coil and is connected to the nitrogen device; the air inlet of the condensing coil is connected to the evaporation tower plate through the air guide pipe, and the air outlet of the condensing coil is connected to the discharge port.

[0006] Furthermore, it also includes a first condenser, which is arranged inside the condenser tower body. The first condenser is a coil. The inlet end of the first condenser passes through the outside of the condenser tower body and is connected to a nitrogen device, and the outlet end of the first condenser is connected to the front end of the nitrogen coil.

[0007] Furthermore, the condensing tower body is provided with a liquid inlet and a liquid outlet, the liquid inlet is arranged at the lower part of the condensing tower body, and the liquid outlet is arranged at the upper part of the condensing tower body.

[0008] Furthermore, the lower end of the condensing tower body also includes a conical cavity, the discharge port is arranged at the lower end of the conical cavity, a partition is arranged at the upper end of the conical cavity, and the air outlet of the condensing coil passes through the partition and is connected to the conical cavity.

[0009] Furthermore, the partition is an arc-shaped plate.

[0010] Furthermore, the first condenser tube is arranged concentrically with the condenser coil.

[0011] Furthermore, the nitrogen coil is a hose.

[0012] Furthermore, a spring is sleeved on the outer side of the nitrogen coil, a bayonet is fixed on the outer wall of the nitrogen coil, the spring is arranged between two adjacent bayonet pins, the outer diameter of the spring is smaller than the inner diameter of the condensing coil, and the inner diameter of the spring is larger than the outer diameter of the nitrogen coil.

[0013] The high-purity lead-free zinc powder preparation process also includes the following steps: S1: Smelting of zinc ingots: heating the furnace to 320℃-350℃, putting in the zinc ingots, keeping them warm for 5-10min, then heating and melting at a rate of 1-2℃ / s, raising the furnace temperature to 500-550℃ to melt the zinc ingots until the zinc ingots are melted into liquid.

[0014] S2: Exhaust: introduce nitrogen into the evaporation tray to exhaust the air in the evaporation tray; S3: Evaporating liquid zinc; an opening is provided on the inner side of the bottom of the furnace, the height of the opening is 5-15 cm, and the zinc flow pipe is connected to the bottom of the opening. Liquid zinc enters the zinc flow pipe from the opening, and is transported to the evaporation tray through the zinc flow pipe. The temperature in the evaporation tray is controlled to be 907°C-960°C. The liquid zinc flows through each layer of the evaporation tray to evaporate the liquid zinc into zinc vapor. The high boiling point impurities lead and iron are separated and discharged from the waste liquid outlet at the bottom of the evaporation tray. S4: The condensation device condenses the zinc vapor; the condensate is stored in the condensation device, and the zinc vapor enters the condensation coil of the condensation device through the air guide pipe, and is connected to nitrogen. The zinc vapor enters the condensation coil and mixes with the nitrogen to generate turbulence, and is fully cooled. The zinc vapor turns into zinc powder and falls into the bottom of the condensation tower; S5: The collecting device collects the zinc powder and transfers it to the classifier; the discharge port of the condensing tower collects the zinc powder through the collecting device and transfers it to the classifier; S6: The classifier classifies the zinc powder; the collected zinc powder is placed in a corresponding powder storage bin, and a feeder is provided in the storage bin, and the feeder is used to evenly feed the zinc powder to the classifier, and the classifier classifies the coarse particles and fine powder in the zinc powder; S7: Finished products are put into storage; zinc powder particle size and purity are sampled and tested; after passing the inspection, the zinc powder that meets the requirements is packaged and stored.

[0015] Furthermore, the classifier includes a vibrating screen, an airflow classifier and a cyclone separator. First, the vibrating screen is evenly fed with materials through a feeder, and the vibrating screen performs primary screening, and the coarse particles and fine powder in the zinc powder are classified. The screened materials are zinc distillate and coarse zinc particles, which are collected and processed and returned to the melting furnace for remelting; then, the screened materials are classified by the airflow classifier, and the airflow classifier uses a rotating airflow to separate zinc powders of different particle sizes. The rear end of the airflow classifier is also connected to a cyclone separator, and the airflow is discharged after being processed by the cyclone separator. The classified zinc powder is packaged and stored as a finished product after passing the inspection.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention uses a multi-layer stacked evaporation tray to evaporate liquid zinc, and the zinc liquid can be fully evaporated into a gaseous state in the evaporation tray. The zinc vapor rises and is discharged through the steam outlet above. The waste liquid containing high-boiling impurities such as lead and iron is discharged from the waste liquid outlet below the evaporation tray, and the lead and iron impurities in the liquid zinc are separated, ensuring the preparation of lead-free zinc powder and the purity of the prepared zinc powder. 2. The present invention arranges a nitrogen coil in the condensation coil to fully mix the nitrogen with the zinc vapor in the condensation coil, and blows the zinc vapor in different directions through the arranged pores, which promotes the collision between gases, reduces the agglomeration phenomenon of particles, ensures that the prepared zinc powder has a smaller particle size, reduces the phenomenon of by-product remelting, and introduces nitrogen through the nitrogen coil to avoid the mixing of air, ensuring that the prepared zinc powder has a higher purity. In addition, by introducing nitrogen, the stability of the fluid flow is enhanced, so that the system is not easily affected by the fluctuation of the zinc vapor working condition, and ensures that when the zinc vapor working condition changes, the particle size of the prepared zinc powder is stable and uniform. 3. The lower end of the condensation tower body also includes a conical cavity to ensure that the bottom of the condensation tower body can accommodate the falling zinc powder, and under the pressure of nitrogen, the air pressure in the conical cavity is large, which prevents external air from mixing into the condensation device during material collection, avoids the occurrence of oxidation reactions, avoids the mixing of impurities, and ensures that the purity of the produced zinc powder is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of a system for preparing a high-purity lead-free zinc powder according to the present invention; Figure 2 It is a structural schematic diagram of a condensing device of the process for preparing high-purity lead-free zinc powder of the present invention; Figure 3 A top view of a condensing coil and a first condensing tube in the process for preparing high-purity lead-free zinc powder of the present invention; Figure 4 It is a structural schematic diagram of the first condenser of the process for preparing high-purity lead-free zinc powder of the present invention; Figure 5 It is a schematic diagram of the structure of the nitrogen coil in the process for preparing high-purity lead-free zinc powder of the present invention; Figure 6 It is a schematic structural diagram of the spring assembly of the high-purity lead-free zinc powder preparation process of the present invention; Figure 7 It is a schematic cross-sectional view of a condensing coil in the process for preparing high-purity lead-free zinc powder of the present invention. DETAILED DESCRIPTION

[0018] In order to provide a further understanding of the purpose, structure, features, and functions of the present invention, the following detailed description is given in conjunction with the embodiments.

[0019] like Figure 1As shown, a process for preparing high-purity lead-free zinc powder includes a melting furnace 1, a zinc flow pipe 2, an evaporation tray 3, an air guide pipe 4, a condensing device and a classifier 5; The bottom of the melting furnace 1 is connected to the evaporation tray 3 through the zinc flow pipe 2, ensuring that the liquid zinc can be transported from the bottom of the melting furnace 1 to the evaporation tray 3 through the zinc flow pipe 2 for evaporation, isolating the air, and preventing air from mixing in, causing the liquid zinc to oxidize and affect the purity of the prepared zinc powder.

[0020] The evaporation tray 3 is stacked in multiple layers, and each layer of the evaporation tray 3 is provided with a connection port 31 connecting the upper and lower evaporation chambers. The connection ports 31 are staggered left and right to ensure that the path through which the zinc liquid flows is longer, and sufficient heating and evaporation can be performed in the evaporation tray 3. The upper layer of the evaporation tray 3 is provided with a zinc liquid inlet 32 ​​and a steam outlet 33, and the bottom of the evaporation tray 3 is provided with a waste liquid outlet 34; the zinc liquid inlet 32 ​​is connected to the melting furnace 1 through a zinc flow pipe 2; it is ensured that the zinc liquid can be fully evaporated into a gaseous state in the evaporation tray 3, the zinc vapor rises and is discharged through the steam outlet above, and the waste liquid containing high-boiling impurities such as lead and iron is discharged from the waste liquid outlet 34 below the evaporation tray 3, so as to separate the lead and iron impurities in the liquid zinc, ensure the preparation of lead-free zinc powder, and ensure the purity of the prepared zinc powder.

[0021] The steam outlet 33 is connected to the condensing device through the air duct 4, and a discharge port 110 is arranged below the condensing device. The discharge port 110 collects the zinc powder through the collecting device and then transfers it to the classifier to sort the particle size of the zinc powder. The zinc steam is condensed by the condensing device to prepare zinc powder, which is beneficial to the industrial production of zinc powder and avoids the contamination of impurities. High-purity zinc powder can be obtained, and the production scale can be flexibly adjusted according to market demand to adapt to different production needs.

[0022] like Figure 2 , Figure 5 and Figure 7The condensing device includes a condensing tower body 100, a condensing coil 200 and a nitrogen coil 300. The condensing coil 200 is arranged in the condensing tower body 100, and the nitrogen coil 300 is arranged in the tube cavity of the condensing coil 200. The end of the nitrogen coil 300 is closed, and a plurality of air holes 310 are arranged on the nitrogen coil 300. The front end of the nitrogen coil 300 passes through the condensing coil 200 and is connected to the nitrogen device; the air inlet 210 of the condensing coil 200 is connected to the evaporation tower plate through the air guide pipe, and the air outlet 220 of the condensing coil is connected to the discharge port 110. By setting a nitrogen coil 300 in the condensing coil 200, the nitrogen is fully mixed with the zinc vapor in the condensing coil 200, and the zinc vapor is blown in different directions through the air holes 310, which promotes the collision between gases, reduces the agglomeration of particles, ensures that the prepared zinc powder has a smaller particle size, reduces the remelting of byproducts, and introduces nitrogen through the nitrogen coil to avoid the mixing of air, ensuring that the purity of the prepared zinc powder is high. In addition, by introducing nitrogen, the stability of fluid flow is enhanced, making the system less susceptible to the fluctuation of zinc vapor working conditions, ensuring that the prepared zinc powder has a stable and uniform particle size when the zinc vapor working conditions change.

[0023] Combination Figure 3 and Figure 4 , further comprising a first condenser 400, the first condenser 400 being arranged in the condenser body 100, the first condenser 400 being a coil, the inlet end 410 of the first condenser 400 passing through the condenser body 100 and connected to a nitrogen device, and the outlet end 420 of the first condenser 400 being connected to the front end of the nitrogen coil. The nitrogen is cooled by the first condenser 400 to ensure that the temperature of the nitrogen entering the condenser coil is below 10-25°C, the cold nitrogen can quickly and effectively reduce the temperature of the zinc vapor, promote the condensation of zinc, and thus improve the recovery efficiency of zinc. During the cooling process, the cold nitrogen can form an inert environment to prevent the zinc vapor from reacting with oxygen in the air, reduce the oxidation and volatilization loss of zinc, and maintain the purity of zinc. The zinc powder particles after condensation are more uniform and regular in shape. The zinc vapor and nitrogen are cooled by the same coolant, which makes full use of energy, saves energy consumption, and has a low cost. The temperature is kept the same as the coolant to avoid overcooling or overheating, ensuring a smooth cooling process and uniform and regular zinc powder particle size. The formation of pores is reduced, the service life of the condensation equipment is extended, and the maintenance cost is reduced.

[0024] like Figure 2The condensation tower body 100 is provided with a liquid inlet 120 and a liquid outlet 130. The liquid inlet 120 is arranged at the lower part of the condensation tower body 100, and the liquid outlet 130 is arranged at the upper part of the condensation tower body 130. By conveying the condensate from bottom to top, it is ensured that the condensation tower body 100 can be filled with the condensate. The condensate can be water, which can be connected to a water circulation cooling system to circulate the condensate, reduce the waste of water resources, and ensure the condensation effect. The liquid inlet 120 is arranged at the bottom, and when cooling is performed, the temperature at the bottom of the cooling tower body can be kept low, and when the zinc vapor is cooled from top to bottom, the temperature will gradually decrease, forming a temperature gradient, improving the overall heat exchange efficiency, and ensuring the condensation effect.

[0025] The lower end of the condensing tower body 100 further includes a conical cavity 140, the lower end of the conical cavity 140 is provided with the discharge port 110, the upper end of the conical cavity 140 is provided with a partition 141, and the air outlet of the condensing coil penetrates the partition 141 and connects to the conical cavity 140. It is ensured that the bottom of the condensing tower body 100 can accommodate the falling zinc powder, and under the pressure of nitrogen, the air pressure of the conical cavity is high, so as to prevent the external air from mixing into the condensing device during the material collection, avoid the generation of oxidation reaction, avoid the mixing of impurities, and ensure the high purity of the produced zinc powder.

[0026] The partition 141 is an arc-shaped plate. The supporting strength is high, which ensures the service life of the condensation tower body 100. The design of the arc-shaped plate 141 can impact the arc-shaped plate when the condensate enters the liquid or the liquid flows, causing the arc-shaped plate 141 to vibrate, reducing the zinc powder attached to the partition, avoiding the accumulation of zinc powder on the partition, reducing residue, ensuring the high cleanliness of the condensation tower body, and reducing maintenance costs.

[0027] The first condenser tube 400 is arranged concentrically with the condenser coil 200. To ensure high space utilization, multiple first condenser tubes 400 and condenser coils 200 can be arranged in the tower body during use to perform multiple groups of independent cooling, thereby improving cooling efficiency and achieving high energy utilization.

[0028] The nitrogen coil 300 is a hose. The hose design ensures that the nitrogen coil 300 can be conveniently arranged inside the condensing coil 200, reduces the difficulty of matching the condensing coil 200 with the nitrogen coil 300, reduces the production cost of the condensing device, and facilitates industrial use.

[0029] like Figure 6 and Figure 7The outer side of the nitrogen coil 300 is sleeved with a spring 500, the outer side wall of the nitrogen coil 300 is fixed with a bayonet 320, the spring 500 is arranged between two adjacent bayonet 320, the outer diameter of the spring 500 is smaller than the inner diameter of the condensing coil 200, and the inner diameter of the spring 500 is larger than the outer diameter of the nitrogen coil 300. The design of the spring 500 ensures that the air holes 310 of the nitrogen coil 300 can pass nitrogen smoothly, and avoids the contact between the nitrogen coil 300 and the inner wall of the condensing coil 200, blocking the air holes 310, ensuring good condensation effect and high condensation efficiency, and also improving the strength of the nitrogen coil 300, avoiding the hose from being "broken" at the bend, causing the bend to be blocked and nitrogen cannot pass smoothly.

[0030] The high-purity lead-free zinc powder preparation process also includes the following steps: S1: Smelting of zinc ingots; heat the furnace 1 to 320℃-350℃, put in the zinc ingots, keep them warm for 5-10 minutes, then heat and melt them at 1-2℃ / s, raise the furnace temperature to 500-550℃ to melt the zinc ingots until they are melted into liquid. Preheating in the early stage reduces the time the zinc ingots are in contact with the air, reduces the oxidation process, reduces the oxidation loss of zinc, improves the purity of the zinc liquid, makes the zinc ingots evenly heated as a whole, avoids local overheating during the smelting process, helps to improve the quality and stability of the zinc liquid, and ensures the production of high-purity zinc powder.

[0031] S2: exhaust; nitrogen is introduced into the evaporation tray 3 to evacuate the air in the evaporation tray 3; the air is sentenced to isolate the air in the system to prevent oxidation of the zinc powder in the system to ensure the purity of the zinc powder.

[0032] S3: Evaporating liquid zinc; an enclosure 11 is provided on the inner side of the bottom of the melting furnace 1, and the height of the enclosure 11 is 5-15cm. The zinc flow pipe 2 is connected to the bottom of the enclosure 11. The liquid zinc enters the zinc flow pipe 2 from the enclosure 11, and is transported to the evaporation tray 3 through the zinc flow pipe 2. The zinc liquid at 5-15cm from the bottom of the melting furnace 1 is taken to reduce the inclusions in the zinc liquid. The purity of the zinc liquid is high. At the same time, the bottom zinc liquid is relatively closed, which can reduce oxidation, reduce the formation of zinc oxide, and improve the purity of zinc powder. The bottom zinc liquid is relatively stable and safer to operate. The temperature in the evaporation tray 3 is controlled to be 907℃-960℃, and the liquid zinc flows through each layer of the evaporation tray to evaporate the liquid zinc into zinc vapor. The high boiling point impurities lead and iron are separated and discharged from the waste liquid outlet at the bottom of the evaporation tray; S4: The condensing device condenses the zinc vapor; the condensate is stored in the condensing device, and the zinc vapor enters the condensing coil 200 of the condensing device through the air guide pipe 4, and is connected to nitrogen. The zinc vapor enters the condensing coil 200 and mixes with the nitrogen to generate turbulence, and is fully cooled. The zinc vapor is converted into zinc powder and falls into the bottom of the condensing tower body 100; the nitrogen is directed into the condensing coil 200 to cool the zinc vapor, improve the condensation effect, and reduce the mixing of air or impurities. The obtained zinc powder has high purity and fine and uniform particles.

[0033] S5: the collecting device collects the zinc powder and transfers it to the classifier 5; the discharge port 110 of the condensing tower body 100 collects the zinc powder through the collecting device and transfers it to the classifier.

[0034] S6: The classifier classifies the zinc powder; the collected zinc powder is placed in a corresponding powder storage bin, a feeder is provided in the storage bin, and the classifier 5 is fed evenly through the feeder, and the classifier 5 classifies the coarse particles and fine powder in the zinc powder; the feeder is used to feed evenly to improve the sorting efficiency, and the zinc powder is provided in various specifications by screening into different grades to meet the needs of specific industries and meet the needs of customers.

[0035] Furthermore, the classifier 5 includes a vibrating screen, an airflow classifier, and a cyclone separator. First, the vibrating screen is evenly fed through a feeder, and the vibrating screen performs primary screening, and the coarse particles and fine powder in the zinc powder are classified. The screened material is zinc distillate and coarse zinc particles, which are collected and processed and returned to the melting furnace for remelting; the particle size is ensured to be uniform, and large particles of coarse zinc are removed through primary screening. By remelting the coarse zinc particles, the purity of zinc can be effectively improved, the physical properties can be optimized, and the metal recovery rate can be increased. After the primary screening, the particle size difference is small, which is also conducive to the subsequent classification and sorting, and the sorting efficiency is improved.

[0036] Next, the screened material is graded by an airflow classifier, which uses a rotating airflow to separate zinc powders of different particle sizes. The rear end of the airflow classifier is also connected to a cyclone separator, and the airflow is discharged after being processed by the cyclone separator to ensure that the discharged air is clean and avoid polluting the environment. The graded zinc powder is packaged and stored as a finished product after passing the inspection. The airflow classifier can effectively grade the particles according to their size, density, shape and other characteristics, and can remove fine impurities or different materials in the zinc particles to improve the purity of the zinc particles. Accurately control the airflow velocity and grading area to ensure that the zinc particles are evenly graded according to the particle size, thereby improving the uniformity and consistency of the zinc powder. The grading parameters can be adjusted according to different industrial needs to provide zinc particles suitable for various applications to meet the needs of different customers.

[0037] S7: Finished products are put into storage; sampling is performed to test the particle size and purity of zinc powder; after passing the inspection, the zinc powder that meets the requirements is packaged and put into storage. This ensures the quality of the finished products and improves the consistency of the products.

[0038] The present invention has been described by the above-mentioned relevant embodiments, however, the above-mentioned embodiments are only examples for implementing the present invention. It must be pointed out that the disclosed embodiments do not limit the scope of the present invention. On the contrary, changes and modifications made without departing from the spirit and scope of the present invention are all within the scope of patent protection of the present invention.

Claims

1. A process for preparing high-purity lead-free zinc powder, characterized in that: It includes furnace, zinc flow pipe, evaporation tray, air guide pipe, condensing device and classifier; The bottom of the melting furnace is connected to the evaporation tower tray through a zinc flow pipe; The evaporation trays are stacked in multiple layers, each layer of the evaporation trays has a connection port connected to the upper and lower evaporation chambers, the connection ports are staggered left and right, the upper layer of the evaporation trays is provided with a zinc liquid inlet and a steam outlet, and the bottom of the evaporation trays is provided with a waste liquid outlet; the zinc liquid inlet is connected to the melting furnace through a zinc flow pipe; The steam outlet is connected to the condensing device through an air guide pipe, and a discharge port is arranged below the condensing device. The discharge port collects zinc powder through a collecting device and then transfers it to a classifier to classify the particle size of the zinc powder. The condensing device comprises a condensing tower body, a condensing coil and a nitrogen coil. The condensing coil is arranged in the condensing tower body, the nitrogen coil is arranged in the tube cavity of the condensing coil, the end of the nitrogen coil is closed, a plurality of air holes are arranged on the nitrogen coil, and the front end of the nitrogen coil passes through the condensing coil and is connected to the nitrogen device; the air inlet of the condensing coil is connected to the evaporation tower plate through the air guide pipe, and the air outlet of the condensing coil is connected to the discharge port.

2. The process for preparing high-purity lead-free zinc powder according to claim 1, characterized in that: It also includes a first condenser, which is arranged in the condenser tower body. The first condenser is a coil. The inlet end of the first condenser passes through the condenser tower body and is connected to a nitrogen device. The outlet end of the first condenser is connected to the front end of the nitrogen coil.

3. The process for preparing high-purity lead-free zinc powder according to claim 1, characterized in that: The condensing tower body is provided with a liquid inlet and a liquid outlet. The liquid inlet is arranged at the lower part of the condensing tower body, and the liquid outlet is arranged at the upper part of the condensing tower body.

4. The process for preparing high-purity lead-free zinc powder according to claim 1, characterized in that: The lower end of the condensing tower body also includes a conical cavity, the lower end of the conical cavity is provided with the discharge port, the upper end of the conical cavity is provided with a partition, and the air outlet of the condensing coil passes through the partition and is connected to the conical cavity.

5. The process for preparing high-purity lead-free zinc powder according to claim 4, characterized in that: The partition is an arc-shaped plate.

6. The process for preparing high-purity lead-free zinc powder according to claim 2, characterized in that: The first condenser tube is arranged concentrically with the condenser coil.

7. The process for preparing high-purity lead-free zinc powder according to claim 1, characterized in that: The nitrogen coil is a hose.

8. The process for preparing high-purity lead-free zinc powder according to claim 7, characterized in that: The outer side of the nitrogen coil is sleeved with a spring, the outer side wall of the nitrogen coil is fixed with a bayonet, the spring is arranged between two adjacent bayonet pins, the outer diameter of the spring is smaller than the inner diameter of the condensing coil, and the inner diameter of the spring is larger than the outer diameter of the nitrogen coil.

9. The process for preparing high-purity lead-free zinc powder according to claim 2, characterized in that: The following steps are also included: S1: Smelting of zinc ingots: heating the furnace to 320-350°C, putting in the zinc ingots, keeping the temperature for 5-10 minutes, then heating and melting at a rate of 1-2°C / s, raising the furnace temperature to 500-550°C to melt the zinc ingots until the zinc ingots are melted into liquid; S2: Exhaust: introduce nitrogen into the evaporation tray to exhaust the air in the evaporation tray; S3: Evaporating liquid zinc; an opening is provided on the inner side of the bottom of the furnace, the height of the opening is 5-15 cm, and the zinc flow pipe is connected to the bottom of the opening. Liquid zinc enters the zinc flow pipe from the opening, and is transported to the evaporation tray through the zinc flow pipe. The temperature in the evaporation tray is controlled to be 907°C-960°C. The liquid zinc flows through each layer of the evaporation tray to evaporate the liquid zinc into zinc vapor. The high boiling point impurities lead and iron are separated and discharged from the waste liquid outlet at the bottom of the evaporation tray. S4: The condensation device condenses the zinc vapor; the condensate is stored in the condensation device, and the zinc vapor enters the condensation coil of the condensation device through the air guide pipe, and is connected to nitrogen. The zinc vapor enters the condensation coil and mixes with the nitrogen to generate turbulence, and is fully cooled. The zinc vapor turns into zinc powder and falls into the bottom of the condensation tower; S5: The collecting device collects the zinc powder and transfers it to the classifier; the discharge port of the condensing tower collects the zinc powder through the collecting device and transfers it to the classifier; S6: The classifier classifies the zinc powder; the collected zinc powder is placed in a corresponding powder storage bin, and a feeder is provided in the storage bin, and the feeder is used to evenly feed the zinc powder to the classifier, and the classifier classifies the coarse particles and fine powder in the zinc powder; S7: Finished products are put into storage; The zinc powder particle size and purity are sampled and tested; after passing the inspection, the zinc powder that meets the requirements will be packaged and stored.

10. The process for preparing high-purity lead-free zinc powder according to claim 9, characterized in that: The classifier includes a vibrating screen, an airflow classifier and a cyclone separator. First, the vibrating screen is evenly fed with materials through a feeder, and the vibrating screen performs primary screening, and the coarse particles and fine powder in the zinc powder are classified. The screened materials are zinc distillate and coarse zinc particles, which are collected and processed and returned to the melting furnace for remelting; then, the screened materials are classified by the airflow classifier, and the airflow classifier uses a rotating airflow to separate zinc powders of different particle sizes. The rear end of the airflow classifier is also connected to a cyclone separator, and the airflow is discharged after being processed by the cyclone separator. The classified zinc powder is packaged and stored as a finished product after passing the inspection.

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