Device and method for continuous condensation of arsenic vapor and separation of elemental arsenic

Abstract

The present invention discloses an apparatus and method for continuously condensing arsenic vapor and separating elemental arsenic. The apparatus comprises a cooling tower, with a plurality of atomizing nozzles or atomizing nozzles disposed at the top of the cooling tower. Several arsenic vapor input pipes are provided on the central sidewalls of the cooling tower. The ports of the arsenic vapor input pipes are sealed, and micropores or microcracks are evenly distributed on the pipe walls. The apparatus has a simple structural design, is easy to operate, and has low cost. It can rapidly condense and separate arsenic vapor, producing uniformly sized, micro-nanoscale, and high-purity metallic arsenic particles. It also reduces diffusion and dispersion during the condensation process, improving the collection efficiency of metallic arsenic and enabling continuous production. Furthermore, the metallic arsenic collection process is efficient, safe, and environmentally friendly, making it suitable for widespread use.

Description

Technical Field

[0001] The present invention relates to a device and method for continuously condensing arsenic vapor and collecting elemental arsenic, and specifically to a method for continuously and rapidly condensing arsenic vapor and collecting elemental arsenic by utilizing an integrated microbubble atomization-spray condensation-filter pressure separation device, belonging to the technical field of arsenic resource development. Background Art

[0002] Arsenic exists naturally as an ore and is widely distributed throughout the Earth's crust. It is commonly produced as a byproduct of non-ferrous metal smelting, primarily in the form of arsenic compounds such as arsenic trioxide, arsenates, and arsenic sulfide. Despite its harmful properties, arsenic plays a vital role in national economic production. Currently, metallic arsenic is widely used in the manufacture of non-ferrous metal alloys and the semiconductor material gallium arsenide because it increases the hardness, strength, and corrosion resistance of alloys. In recent years, the demand for metallic arsenic has shown a sustained growth trend, placing stricter demands on the technology used to produce elemental arsenic. Currently, the main methods for producing elemental arsenic are pyrometallurgical and hydrometallurgical methods. However, due to the low recovery rate, high cost, and severe environmental pollution associated with the hydrometallurgical method, existing processes primarily focus on the pyrometallurgical method for producing elemental arsenic. Using arsenic compounds such as arsenic trioxide, arsenates, and arsenic sulfide as raw materials, arsenic is produced through vacuum distillation, pyrometallurgical carbon reduction, and oxygen reduction methods. The arsenic is then collected through condensation and crystallization. Taking the preparation of metallic arsenic from white arsenic as an example, white arsenic is thoroughly mixed with a reducing agent and heated, reduced, and roasted in a sealed, electrically heated vertical tank. The generated metallic arsenic vapor is cooled and crystallized on a condensation hood within the vertical furnace. However, it is worth noting that while using a condensation hood to collect arsenic can achieve good arsenic recovery indicators, it suffers from poor sealing and the risk of arsenic vapor leakage at high temperatures. Furthermore, it imposes higher standards on condensation efficiency, cooling medium, and cooling rate, hindering the continuous and stable operation of the metallic arsenic collection operation. Therefore, proposing new technical ideas for recovering metallic arsenic and developing new metallic arsenic recovery equipment are important foundations for achieving stable metallic arsenic production. Summary of the Invention

[0003] In view of the problems of weak sealing, poor crystallization effect, and difficulty in continuous operation in the technology of recovering arsenic by condensation in a crystallizer during the preparation of metallic arsenic in the prior art, the first object of the present invention is to provide a device for continuously condensing arsenic vapor and separating elemental arsenic. The device has a simple structural design, is easy to operate, and has low cost. The device can achieve rapid condensation and separation of arsenic vapor, and obtain metallic arsenic particles with uniform size, micro-nano level, and high purity. It can also reduce the diffusion and drift of the arsenic vapor during the condensation process, improve the collection efficiency of metallic arsenic, and realize continuous production. At the same time, the metallic arsenic collection process is efficient, safe, and environmentally friendly, which is conducive to popularization and use.

[0004] The second object of the present invention is to provide a method for continuously condensing arsenic vapor and separating elemental arsenic. This method uses a special device, takes advantage of the immiscible properties of metallic arsenic and aqueous media, and adopts spraying and atomization technology to quickly condense and crystallize the metallic arsenic vapor to form metallic arsenic particles with uniform size, micro-nano size, and high purity. At the same time, it can reduce the diffusion and dispersion of the arsenic vapor during the condensation process, improve the collection efficiency of the metallic arsenic, and the metallic arsenic collection process is efficient, safe, and environmentally friendly, can be carried out continuously, and is conducive to industrial production.

[0005] In order to achieve the above technical objectives, the present invention provides a device for continuously condensing arsenic vapor and separating elemental arsenic, the device comprising a cooling tower; a plurality of atomizing nozzles or atomizing nozzles are provided at the top of the cooling tower; a plurality of arsenic vapor input pipes are provided on the middle side wall of the cooling tower, the ports of the arsenic vapor input pipes are closed, and micropores or microcracks are evenly distributed on the pipe wall; the lower part of the cooling tower is a collection area, and the bottom of the collection area is connected to a filter press via an output pipe.

[0006] The device of the present invention has relatively good sealing performance, which can prevent the leakage of arsenic vapor and the entry of external pollutants, and solves the technical problem of weak sealing of traditional crystallizers. A liquid atomizing nozzle or nozzle device and a gas atomizing device are provided inside the device, which can atomize water to form tiny droplets that come into contact with arsenic vapor to achieve rapid cooling and solidification of the arsenic vapor, achieve efficient crystallization, and ensure that the arsenic vapor is condensed into micro-nano arsenic particles of uniform size, solving the technical problem of poor crystallization effect of existing arsenic vapor. The device can use water as a cooling medium to directly contact and condense with arsenic-containing vapor, which has better heat transfer efficiency than traditional air medium condensation and increases the cooling rate. In addition, the device also takes into account the needs of continuous operation. By designing a suitable feeding and discharging system, the ability to continuously collect and process metallic arsenic is achieved. Cooling water and arsenic vapor can be continuously injected, and the slurry containing elemental arsenic particles can be continuously output and separated, thereby solving the technical problem that the arsenic crystallization and separation process is difficult to operate continuously.

[0007] The device of the present invention can realize the efficient and continuous conversion of arsenic vapor into elemental arsenic particles, and is easy to continuously separate and recover elemental arsenic particles. The main part of the device provided by the present invention is a cooling tower, which is significantly different from the existing crystallizer. The conventional crystallizer uses the low temperature environment inside to realize the cooling and crystallization of arsenic vapor, while the arsenic vapor mainly crystallizes and grows on the inner wall of the crystallizer to form a block, which has technical problems such as discontinuous production and difficulty in unloading. At the same time, the impurities in the arsenic vapor cannot be well removed, and the impurities will also be co-deposited in the metal arsenic block, resulting in increased difficulty in subsequent separation. The cooling tower of the present invention uses water as the cooling medium, and by providing an atomizing nozzle or atomizing nozzle device and a gas atomizing device, it can quickly crystallize and convert arsenic vapor into ultrafine metal arsenic particles, and the ultrafine metal arsenic particles are dispersed in water to form a slurry, which can then be separated by a simple filter press device. Moreover, the small amount of impurities contained in the ultrafine metal arsenic particles can also be easily separated by utilizing the difference in water solubility or hydrophobicity between elemental arsenic and impurities, thereby obtaining crude arsenic with higher purity and reducing the difficulty of subsequent impurity separation.

[0008] The arsenic vapor input conduit of the present invention has micropores or cracks evenly distributed on its wall, and an atomizing nozzle or atomizing nozzle is provided on the top. When high-temperature arsenic vapor passes through these micropores and cracks, the arsenic vapor is released in a spray or atomized manner due to factors such as its motion properties and surface tension. Simultaneously, a water medium is dispersed and ejected at high speed through the atomizing nozzle or atomizing nozzle. These atomizing nozzles or atomizing nozzles can produce mist droplets, increasing the contact area between the water and the arsenic vapor to promote the condensation process, enabling rapid cooling and crystallization of the atomized arsenic vapor, and preventing the metal arsenic particles from agglomerating or growing into large particles. This facilitates the production of small, uniform metal arsenic particles. Furthermore, the contact area between the water medium and the arsenic vapor is increased, promoting heat exchange and increasing the collection rate of the metal arsenic.

[0009] As a preferred solution, a power pump is provided on the output pipeline, through which the slurry in the collection area of ​​the cooling tower can be transported to the filter press for separation.

[0010] As a preferred solution, the water spraying volume of a single atomizing nozzle or atomizing nozzle is 0.4 to 0.6 m 3 / h. The atomizing nozzle or atomizing nozzle can be adjusted by angle and flow rate to increase the contact area between water and arsenic vapor, promoting the condensation process. The specific adjustment process can be achieved through an automatic control system, which automatically adjusts the nozzle based on real-time monitoring data to achieve the best condensation effect.

[0011] As a preferred solution, the gas flow rate of a single arsenic vapor input pipeline is 0.5-1.0 Nm 3 / h.

[0012] As a preferred solution, the ratio of the number of the atomizing nozzles or atomizing nozzles to the number of the arsenic vapor input pipes is 8 to 12:1.

[0013] The quantitative ratio of the arsenic vapor input pipe and the atomizing nozzle or the atomizing nozzle of the present invention, as well as the gas flow rate of the arsenic vapor input pipe and the water spraying amount of the atomizing nozzle or the atomizing nozzle need to be coordinated and controlled, so that the water medium flow rate, the arsenic vapor flow rate and the contact rate can reach an optimal state. This not only increases the contact area and probability between water and arsenic vapor to achieve the best condensation effect, but also controls the particle size of the arsenic element particles, which is conducive to obtaining small and uniform metallic arsenic particles.

[0014] As a preferred solution, the diameter of the cooling tower is not less than 3m and the height is 5m to 10m. Generally speaking, the diameter of the cooling tower is not greater than its height.

[0015] As a preferred solution, the diameter of the micropores on the pipe wall is no larger than 0.2 mm, and the width of the microcracks is no larger than 0.1 mm. By controlling the size of the micropores or the width of the microcracks on the pipe wall, the injection state of the arsenic vapor can be controlled.

[0016] The present invention also provides a method for continuously condensing arsenic vapor and separating elemental arsenic. The method is implemented based on the above-mentioned device. The gas containing arsenic vapor is continuously atomized or sprayed into a cooling tower through an arsenic vapor input pipe, and reacts with water droplets sprayed from an atomizing nozzle or an atomizing nozzle to form a slurry containing elemental arsenic particles, which enters a collection area. The obtained slurry is pumped into a filter press for solid-liquid separation to obtain elemental arsenic particles.

[0017] As a preferred solution, the spray pressure of the atomizing nozzle or atomizing nozzle is 120-150 bar. The size of the water droplets can be adjusted by controlling the pressure.

[0018] As a preferred solution, the temperature of the arsenic-containing vapor is 500-600°C.

[0019] After the slurry of the present invention is pumped into the filter press for solid-liquid separation, the liquid is returned and reused as cooling water.

[0020] The present invention considers using an aqueous medium to directly cool arsenic vapor. This is primarily based on the fact that arsenic vapor crystallizes below 100°C to form gamma-state elemental arsenic (black powder), while aqueous medium has a boiling point below 100°C and is immiscible with gamma-state elemental arsenic. This unique method utilizes aqueous medium to directly cool and crystallize arsenic vapor into ultrafine metallic arsenic particles. These metallic arsenic particles are dispersed in the aqueous medium, allowing for the wet removal of some impurities and making it easier to obtain metallic arsenic particles through conventional solid-liquid separation.

[0021] The existing method for collecting arsenic vapor is to condense and recover α-state elemental arsenic in a crystallizer. However, the elemental arsenic condenses in the crystallizer, forming lumps, resulting in discontinuous production and difficult unloading. Furthermore, impurities in the arsenic vapor cannot be effectively removed, and the recovered metallic arsenic has a relatively low purity. The present invention, however, cleverly condenses and crystallizes the arsenic vapor directly using atomized water droplets, recovering the γ-state elemental arsenic through a wet process. This allows for a continuous arsenic vapor recovery process and produces powdered γ-state arsenic particles. This not only improves production efficiency but also allows for the easy separation of small amounts of impurities contained in the powdered granular γ-arsenic through a wet process.

[0022] Compared with the prior art, the technical solution of the present invention brings the following beneficial technical effects:

[0023] 1) Compared with the traditional method of collecting metallic arsenic using a condensation crystallizer, the present invention uses an aqueous medium to collect metallic arsenic, which has the technical characteristics of high efficiency, environmental protection, and strong continuity.

[0024] 2) The device of the present invention can increase the contact area and time of condensation by designing an atomizing nozzle or atomizing nozzle for liquid atomization and an arsenic vapor input pipe with an atomizing function, thereby improving the condensation effect. At the same time, the arsenic vapor can be directly condensed into ultrafine granular metallic arsenic, which is beneficial to the recovery of metallic arsenic and the removal of impurities.

[0025] 3) The device of the present invention can flexibly control the energy consumption and condensation effect during the condensation process by easily adjusting the water flow rate and spray intensity of the atomizing nozzle or the atomizing nozzle.

[0026] 4) The device of the present invention directly condenses arsenic vapor into ultrafine particles through water and forms a slurry. After simple dehydration, the arsenic element can be quickly recovered, and continuous operation is easy to achieve.

[0027] 5) The present invention can achieve continuous condensation and separation of arsenic vapor, and obtain metallic arsenic particles with uniform size, micro-nano level, and high purity. It can also reduce the diffusion and dispersion of arsenic vapor during the condensation process, thereby improving the collection efficiency of metallic arsenic. At the same time, the metallic arsenic collection process is efficient, safe, and environmentally friendly, which is conducive to its promotion and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of the cooling tower structure.

[0029] Figure 2 A schematic diagram of the overall structure of the device.

[0030] Figure 3 This is the form of elemental arsenic prepared in Example 1.

[0031] Figure 4 This is the elemental analysis result of the elemental arsenic prepared in Example 1. DETAILED DESCRIPTION

[0032] The following specific embodiments are intended to illustrate the present invention in detail in conjunction with the accompanying drawings, rather than to limit the scope of protection of the claims.

[0033] The device for continuously condensing arsenic vapor and separating elemental arsenic of the present invention has a specific structure as follows: Figure 1 and Figure 2As shown. Its main structure is a cooling tower (1); a plurality of atomizing nozzles or atomizing nozzles (2) are provided at the top of the cooling tower; a plurality of arsenic vapor input pipes (3) are provided on the side wall of the middle part of the cooling tower, the ports of the arsenic vapor input pipes are closed, and micropores or cracks are evenly distributed on the pipe wall (the micropore diameter does not exceed 0.2mm, and the microcrack width does not exceed 0.1mm); the lower part of the cooling tower is a collection area, and the bottom of the collection area is connected to a filter press (6) through an output pipe (4). A pressure pump (5) is provided on the output pipe. The top of the cooling tower is connected to a water source, which can be the water outlet of the filter press. More specifically, the exterior of the cooling tower is cylindrical, with a diameter of not less than 3m and a height of 5m to 10m. Atomizing nozzles or atomizing nozzles (which are conventional spray components in the prior art) are evenly designed and arranged throughout the entire top area of ​​the cooling tower to condense the high-temperature arsenic vapor volatilized by roasting, thereby promoting the transformation of metallic arsenic from a gas phase to a solid phase and precipitation. This design effectively condenses metallic arsenic from high-temperature gas into a solid state, causing it to drip downward into a collection area through gravity. The collection area is located at the bottom of the cooling tower. By controlling the flow rate of the cooling medium, the number of atomizing nozzles, and their arrangement, the condensation rate and solidification effect can be adjusted to obtain the desired metallic arsenic particle product. This device design helps improve the collection efficiency and purity of metallic arsenic and reduces its waste in the gas. When applied to the metallic arsenic production process, it provides an efficient and reliable condensation method, thereby achieving high-quality metallic arsenic production. An arsenic vapor inlet pipe is located in the middle of the cooling tower. It is made of high-temperature and corrosion-resistant materials (such as stainless steel, including grades 304 and 316, which have excellent corrosion resistance). The pipe has numerous micropores (or microcracks) evenly distributed on the pipe surface. These micropores (or microcracks) can be tiny holes or elongated micro-slits. The micropore diameter is no greater than 0.2 mm, and the microcrack width is no greater than 0.1 mm, which facilitates the release of arsenic vapor-containing gas. When high-temperature gas passes through these micropores, it flows out at high speed. Due to the motion properties of gas molecules and factors such as surface tension, the gas is released as a jet or atomization, forming a tiny jet or atomization state. By releasing the gas, the device disperses the high-temperature gas into many small particles, thereby increasing the contact area between the gas and the condensation medium (such as coolant or water), promoting the transformation of metallic arsenic from the gas phase to the solid phase and precipitation, improving the purity and collection rate of the metallic arsenic. At the same time, the arsenic vapor is directly condensed into uniform ultrafine particles. These gas particles can contact and exchange heat with the condensation medium, thereby promoting the condensation process. The output pipeline is responsible for transporting the slurry to the subsequent processing unit. The pressure pump pushes the slurry into the plate and frame filter press, which achieves solid-liquid separation. The solid elemental arsenic is retained in the plate and frame for further processing or recycling.

[0034] Example 1

[0035] The above method was applied to a system for treating metallic arsenic in the production process of a smelter. The volume of arsenic flue gas generated during the crude arsenic preparation process was 2 bar. Previously, the traditional crystallization method was used to collect the metallic arsenic. The crystallization process was completed in a crystallization tank. Although the purity of the metallic arsenic was greater than 90%, only 60% to 80% of the arsenic vapor in the system could be converted into solid metallic arsenic for recovery. There are disadvantages such as poor continuity and low recovery efficiency, which cause great troubles to the environment and industrial production. According to the arsenic vapor treatment method provided by the present invention, a directional and uniformly arranged atomizing nozzle is arranged on the upper part of a cooling tower with a diameter of 5.2m and a height of 8m. A total of 10 atomizing nozzles are set, and a gas delivery pipeline is set in the middle of the cooling tower. Each pore of the gas delivery pipeline is 0.1mm. According to the generation effect of microbubble gas, pipeline and flow index requirements, 1000 pores are evenly distributed on the pipeline. According to the output of arsenic vapor and the required microbubble density, 500℃ arsenic-containing vapor is transported to the cooling tower, and fine particles are formed through the fine pores of the arsenic vapor delivery pipeline, thereby realizing rapid atomization of arsenic vapor. Under the action of atomized water droplets, it condenses to form metallic elemental arsenic. The flow rate of each atomizing nozzle is 0.4m 3 / h, the total water spraying volume is 4m 3 / h, the injection rate is 0.8m / s, and the ejection pressure is about 130bar. The atomization rate of arsenic vapor is 0.2m / s, and the amount of arsenic vapor is 0.6Nm 3 / h. After sufficient cooling and spraying, it is transported to the plate and frame filter press through the liquid medium to achieve continuous and efficient recovery of metallic arsenic. Figure 3 and Figure 4 The microscopic morphology and purity analysis diagram of metallic arsenic collected by the process of the present invention show that the purity of metallic arsenic collected by the process of the present invention is as high as 99.85%, and the recovery rate is more than 90%. At the same time, the obtained metallic arsenic is spherical, with a relatively uniform particle size and fine particles distributed on the surface.

[0036] Example 2

[0037] A large amount of arsenic vapor is generated during the production process of a certain smelter, and the metallic arsenic in it needs to be efficiently recovered. In the past, the traditional crystallization method was used to collect metallic arsenic. The crystallization process was completed in the crystallization tank, with a recovery rate of only 60% and a purity of more than 90%. In order to solve this problem, the smelter decided to introduce the arsenic vapor treatment method proposed in the present invention and implement it. First, according to the specifications and requirements of the cooling tower, a directional and uniform atomizing nozzle was installed on the top of the cooling tower with a diameter of 6m and a height of 10m. A total of 12 atomizing nozzles are set in the cooling tower, and the flow rate of each atomizing nozzle is set to 0.5m 3 / h, the total water spraying volume is 6m 3 / h, and the injection rate is 0.8m / s. This ensures that the arsenic vapor is fully condensed during the atomization process and forms fine water droplets. At the same time, an arsenic vapor input pipe is set in the middle of the cooling tower, and 1500 micro-pores with a diameter of 0.2mm are arranged on the arsenic vapor input pipe. These micro-pores can quickly atomize the high-temperature arsenic vapor into fine particles, increase its surface area, and facilitate the condensation reaction. The atomization rate of the arsenic vapor is set to 0.3m / s, and the total arsenic vapor volume is 0.8Nm 3 / h. After treatment by the spray system, the arsenic vapor is rapidly condensed into metallic arsenic and, along with the mixed liquid formed by the sprayed water, is piped to a plate and frame filter press. The plate and frame filter press utilizes advanced solid-liquid separation technology, efficiently separating elemental metallic arsenic from the liquid, enabling its recovery. This new technology significantly increases the smelter's metallic arsenic recovery rate to over 95%, and significantly improves arsenic purity to over 98%. Compared to traditional crystallization methods, this solution offers advantages such as improved continuity and high recovery efficiency, significantly improving environmental protection and resource utilization in the smelter.

Claims

1. A method for continuously condensing arsenic vapor and separating elemental arsenic, characterized in that: The method for continuously condensing arsenic vapor and separating elemental arsenic is implemented based on the following apparatus: the apparatus includes a cooling tower; a plurality of atomizing nozzles are provided at the top of the cooling tower; a plurality of arsenic vapor input pipes are provided on the central sidewall of the cooling tower; the ports of the arsenic vapor input pipes are closed, and micropores or microcracks are evenly distributed on the pipe walls; the lower portion of the cooling tower is a collection area, the bottom of which is connected to a filter press via an output pipe; the micropores on the pipe walls have a diameter of no greater than 0.2 mm, and the microcracks have a width of no greater than 0.1 mm; The process of continuous condensation of arsenic vapor and separation of elemental arsenic is as follows: the gas containing arsenic vapor is continuously atomized or sprayed into the cooling tower through the arsenic vapor input pipeline, and reacts with water droplets sprayed from the atomizing nozzle to form a slurry containing elemental arsenic particles, which enters the collection area. The resulting slurry is pumped into a filter press for solid-liquid separation to obtain elemental arsenic particles; the temperature of the arsenic vapor-containing gas is 500-600°C.

2. The method for continuous condensation of arsenic vapor and separation of elemental arsenic according to claim 1, characterized in that: A power pump is provided on the output pipeline.

3. The method for continuous condensation of arsenic vapor and separation of elemental arsenic according to claim 1, characterized in that: The water spray volume of a single atomizing nozzle is 0.4~0.6 m 3 / h.

4. The method for continuous condensation of arsenic vapor and separation of elemental arsenic according to claim 1, characterized in that: The gas flow rate of a single arsenic vapor input pipeline is 0.5~1.0Nm 3 / h.

5. The method for continuous condensation of arsenic vapor and separation of elemental arsenic according to claim 1, characterized in that: The ratio of the number of the atomizing nozzles to the number of the arsenic vapor input pipes is 8-12:

1.

6. The method for continuous condensation of arsenic vapor and separation of elemental arsenic according to claim 1, characterized in that: The cooling tower has a diameter of not less than 3m and a height of 5m to 10m.

7. The method for continuous condensation of arsenic vapor and separation of elemental arsenic according to claim 1, characterized in that: The spray pressure of the atomizing nozzle is 120~150bar.

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