Method for purifying sulfur by combining continuous solid-liquid separation and low-temperature sublimation

Abstract

This invention proposes a sulfur purification method combining continuous flow solid-liquid separation and low-temperature sublimation, comprising: S1, physically crushing sulfur raw materials into sulfur particles, placing the sulfur particles in a cleaning solution for ultrasonic cleaning to obtain cleaned sulfur particles; wherein, the cleaning solution is an aqueous solution including at least one cleaning agent selected from sodium carbonate, EDTA, citric acid, phosphate, and silicate; S2, continuously countercurrently immersing the cleaned sulfur particles with an immersion solution, followed by solid-liquid separation to obtain solid sulfur after solid-liquid separation; S3, sublimating the solid sulfur after solid-liquid separation into sulfur vapor at a temperature of 80–110°C and a vacuum of 0.01–10 Pa; S4, condensing the sulfur vapor to obtain solid sulfur. This sulfur purification method effectively reduces energy consumption during the purification process, reduces environmental pollution, and significantly improves the purity of sulfur products, greatly enhancing the energy utilization rate and environmental performance of the entire production process.

Description

Technical Field

[0001] This invention belongs to the field of sulfur purification technology, specifically relating to a sulfur purification method that combines continuous flow solid-liquid separation and low-temperature sublimation. Background Technology

[0002] Sulfur, as an important chemical raw material, is widely used in fertilizers, rubber products, pharmaceuticals, dyes, fireworks, and many other fields. However, naturally occurring sulfur resources usually contain various impurities, such as heavy metal ions, organic matter, inorganic salts, and other insoluble particles. The presence of these impurities seriously affects the purity and usability of sulfur. Therefore, sulfur purification technology plays a crucial role in industrial production.

[0003] Traditional sulfur purification methods mainly include high-temperature melting, distillation, and chemical conversion. High-temperature melting involves heating sulfur above its melting point for smelting, followed by cooling and crystallization to obtain a relatively pure product. However, this method is energy-intensive and prone to sulfur oxidation losses, while also generating high-temperature flue gas with high treatment costs and significant environmental impact. Distillation utilizes the boiling point difference between sulfur and impurities under high-temperature conditions to achieve separation. Although it can improve purity, it also faces problems such as high energy consumption and high equipment investment. Chemical conversion uses chemical reactions to convert impurities in sulfur into precipitable or soluble substances for separation. While effective in certain specific situations, this method often involves the use of complex chemical reagents and potential secondary pollution problems, and the process is complex with demanding operating conditions.

[0004] In recent years, improved sulfur purification processes have emerged, which can remove some impurities. However, they have limited effectiveness in removing impurities that are difficult to dissolve, and the solvents used in the leaching process may cause environmental pollution. Summary of the Invention

[0005] In view of this, the purpose of this invention is to address the technical problems existing in the prior art by providing a sulfur purification method that combines continuous flow solid-liquid separation and low-temperature sublimation. The sulfur purification method of this invention effectively reduces energy consumption in the purification process, reduces environmental pollution, and significantly improves the purity of sulfur products, thereby greatly improving the energy utilization rate and environmental performance of the entire production process.

[0006] The objective of this invention is mainly achieved through the following technical solutions.

[0007] This invention provides a method for sulfur purification using continuous flow solid-liquid separation and low-temperature sublimation, wherein the sulfur purification method includes the following steps:

[0008] S1. The sulfur raw material is physically crushed into sulfur particles, and the sulfur particles are placed in a cleaning solution for ultrasonic cleaning to obtain cleaned sulfur particles; wherein, the cleaning solution is an aqueous solution including at least one cleaning agent selected from sodium carbonate, EDTA, citric acid, phosphate, and silicate.

[0009] S2. The cleaned sulfur particles are continuously countercurrently washed with a washing solution, and then solid-liquid separation is performed to obtain solid sulfur after solid-liquid separation.

[0010] S3. At a temperature of 80–110℃ and a vacuum of 0.01–10Pa, the solid sulfur after solid-liquid separation is sublimated into sulfur vapor.

[0011] S4. Condense sulfur vapor to obtain solid sulfur.

[0012] In this invention, sulfur particles are first ultrasonically cleaned in the presence of a cleaning solution. The ultrasonic cavitation effect removes dirt and microparticle impurities adhering to the surface of the physically broken sulfur particles. It is believed that the cleaning solution can further penetrate (especially by removing the pores formed after removing microparticle impurities) the sulfur particles. Then, the cleaned sulfur particles are continuously countercurrently immersed in a washing solution, further dissolving soluble impurities contained in the ultrasonically cleaned sulfur particles. Next, solid-liquid separation is performed to separate the sulfur particles from the dissolved impurities, completing the initial purification of the sulfur particles. Under vacuum conditions, especially at a vacuum level of 0.01–10 Pa, solid sulfur can sublimate at temperatures below its melting point, achieving low-temperature sublimation. This not only avoids the use of high-temperature environments but also prevents some impurities from sublimating and entering the final condensed product.

[0013] Furthermore, in the sulfur purification method of the present invention, sublimation is carried out at a temperature below the melting point of sulfur, and at a vacuum degree of 0.01 to 10 Pa, which can effectively avoid oxidation loss and energy waste caused by high temperature.

[0014] According to the sulfur purification method provided by the present invention, the average particle size of the sulfur particles is 0.1–3 mm. It is believed that using such a particle size range helps to increase the contact area between the sulfur particles and the cleaning and / or immersion solutions, allowing the surface of the sulfur particles to be more uniformly exposed in the cleaning and / or immersion solutions, improving the cleaning and / or immersion effect, thereby increasing the impurity removal efficiency, and also facilitating subsequent solid-liquid separation and low-temperature sublimation steps.

[0015] For example, the average particle size of the sulfur particles can be 0.1 mm, 0.2 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, or a range thereof.

[0016] In some embodiments, the average particle size of the sulfur particles is 0.2 to 2 mm, preferably 0.5 to 1.5 mm.

[0017] According to the sulfur purification method provided by the present invention, step S1 further includes: sieving the sulfur particles to control the particle size of the sulfur particles to be less than 3 mm, preferably less than 2.5 mm, and more preferably less than 2 mm.

[0018] According to the sulfur purification method provided by the present invention, the sulfur raw material in step S1 can come from various sources, such as including but not limited to sulfur in complex iron desulfurization process, sulfur in biological desulfurization process, sulfur in Claus process, sulfur in natural gas desulfurization process, sulfur in sulfuric acid production process, sulfur by-product of coal gasification, and sulfur by-product of wet desulfurization.

[0019] According to the sulfur purification method provided by the present invention, the cleaning agent in the cleaning solution in step S1 can be selected according to the type and nature of impurities in the sulfur raw material.

[0020] In some embodiments, the cleaning solution in step S1 is an aqueous solution comprising sodium carbonate, EDTA, citric acid, or silicate.

[0021] In some embodiments, the concentration of the cleaning agent in the cleaning solution is 0.1–5 g / L. For example, the concentration of the cleaning agent in the cleaning solution is 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1 g / L, 1.5 g / L, 2 g / L, 2.5 g / L, 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L, 5 g / L, or a range thereof.

[0022] According to the sulfur purification method provided by the present invention, the conditions for ultrasonic cleaning in step S1 include: an ultrasonic power density of 50–500 W / cm². 2 ; and / or, the ultrasonic cleaning temperature is 10–30℃; and / or, the ultrasonic cleaning time is 5–30 minutes.

[0023] Generally, the smaller the particle size of the sulfur particles, the lower the ultrasonic power density, the lower the ultrasonic cleaning temperature, and / or the shorter the ultrasonic cleaning time can be.

[0024] For example, the ultrasonic power density can be 50 W / cm². 2 80W / cm 2 100W / cm 2 120W / cm 2 150W / cm 2180W / cm 2 200W / cm 2 220W / cm 2 250W / cm 2 280W / cm 2 300W / cm 2 350W / cm 2 400W / cm 2 450W / cm 2 500W / cm 2 Or the range of its components.

[0025] For example, the ultrasonic cleaning temperature can be 10℃, 15℃, 20℃, 25℃, 30℃ or a combination thereof.

[0026] For example, the ultrasonic cleaning time can be 5 minutes, 8 minutes, 10 minutes, 15 minutes, 18 minutes, 20 minutes, 25 minutes, 30 minutes or a range thereof.

[0027] According to the sulfur purification method provided by the present invention, the composition of the immersion solution in step S2 can be selected according to the type and properties of impurities in the sulfur. In some embodiments, the immersion solution in step S2 is water or an aqueous solution containing a cleaning agent. In the present invention, the immersion solution can be recycled.

[0028] According to the sulfur purification method provided by the present invention, the conditions for continuous countercurrent immersion in step S2 include: gauge pressure of 0 to 0.5 MPa; and / or temperature of 25 to 60°C; and / or immersion time of 10 to 90 minutes.

[0029] It is believed that immersion under pressure can improve the solubility of the immersion solution in impurities. For example, the gauge pressure can be in the range of 0.01 MPa, 0.02 MPa, 0.05 MPa, 0.08 MPa, 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.45 MPa, and 0.5 MPa. In some embodiments, the gauge pressure is 0.1–0.3 MPa.

[0030] In this invention, the temperature of the continuous countercurrent immersion in step S2 can be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, or a range thereof. In some embodiments, the temperature of the continuous countercurrent immersion in step S2 is 30–55°C.

[0031] In this invention, the continuous countercurrent immersion time in step S2 can be 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, or a range thereof. In some embodiments, the temperature of the cyclic countercurrent immersion in step S2 is 40 to 60 minutes.

[0032] According to the sulfur purification method provided by the present invention, the present invention does not impose any particular limitation on the solid-liquid separation method in step S2, and any method known in the art can be used. Examples suitable for the method (apparatus) of the present invention include, but are not limited to: vacuum belt filter, rotary drum solid-liquid separator, and centrifugal filter.

[0033] In some implementations, solid-liquid separation is performed in step S2 using a centrifugal filter, a vacuum belt filter, or a rotary drum solid-liquid separator. The filter cloth pore size for solid-liquid separation in the vacuum belt filter or rotary drum solid-liquid separator is 200 mesh or larger, for example, 200–300 mesh. Further, when using a vacuum belt filter for solid-liquid separation, the separation is carried out at a pressure of -0.08 MPa to -0.09 MPa.

[0034] According to the sulfur purification method provided by the present invention, in step S3, sublimation is performed at a temperature of 80-110°C, and the solid sulfur does not melt. The temperature in step S3 can be 80°C, 85°C, 88°C, 90°C, 95°C, 98°C, 100°C, 105°C, 110°C, or a range thereof.

[0035] According to the sulfur purification method provided by the present invention, the vacuum degree in step S3 can be within the range of 0.01 Pa, 0.02 Pa, 0.03 Pa, 0.04 Pa, 0.05 Pa, 0.06 Pa, 0.08 Pa, 0.1 Pa, 0.2 Pa, 0.3 Pa, 0.4 Pa, 0.5 Pa, 0.8 Pa, 1 Pa, 1.5 Pa, 2 Pa, 2.5 Pa, 3 Pa, 3.5 Pa, 4 Pa, 4.5 Pa, 5 Pa, 6 Pa, 7 Pa, 8 Pa, 9 Pa, 10 Pa, or a combination thereof. In some embodiments, the vacuum degree in step S3 is 0.1 to 10 Pa, preferably 0.2 to 5 Pa, and more preferably 0.5 to 5 Pa.

[0036] According to the sulfur purification method provided by the present invention, condensation is carried out in step S4 at a cooling temperature of -20 to -5°C. Using such a cooling temperature ensures sufficient condensation of sulfur vapor and a high conversion rate (reaching over 99%). For example, the cooling temperature in step S4 can be -20°C, -19°C, -18°C, -17°C, -16°C, -15°C, -14°C, -13°C, -12°C, -11°C, -10°C, -9°C, -8°C, -7°C, -6°C, -5°C, or a range thereof. In some embodiments, the cooling temperature in step S4 is -20°C to -10°C.

[0037] Unless otherwise specified, each step of the present invention can be performed using any suitable conventional device in the art.

[0038] Compared with the prior art, the sulfur purification method of the present invention has at least the following advantages:

[0039] (1) The sulfur purification method of the present invention combines continuous flow solid-liquid separation technology and low temperature sublimation technology, avoids sulfur oxidation loss and energy waste caused by high temperature, greatly improves the overall energy utilization efficiency, and solves the problems of high energy consumption, complex process and easy environmental pollution in the existing sulfur purification method.

[0040] (2) The efficient solid-liquid separation process significantly reduces the content of heavy metals and other impurities in sulfur products, resulting in high purity. This solves the problem of insufficient purity in sulfur purification methods based on solid-liquid separation and ensures the quality of the final product.

[0041] (3) The sulfur purification method of the present invention has a reasonable and compact process flow design, which is convenient for large-scale production and application. Detailed Implementation

[0042] The following detailed description of preferred embodiments of the present invention illustrates the principles of the invention and is not intended to limit the scope of the invention.

[0043] Example 1

[0044] This embodiment illustrates the purification of sulfur produced in the complexed iron desulfurization process.

[0045] (1) The crude sulfur raw material produced in the complexed iron desulfurization process was physically crushed to obtain sulfur particles with an average particle size of 1.5 mm. This was done at approximately 25°C and 200 W / cm². 2 At an ultrasonic power density of 0.5 g / L, the broken sulfur particles were ultrasonically cleaned for 15 minutes in a sodium carbonate aqueous solution.

[0046] (2) The cleaned sulfur particles are transferred to a continuous countercurrent washing device and washed in pure water for 60 minutes at a temperature of 45°C and a gauge pressure of 0.1 MPa. The resulting mixture is then centrifuged and filtered in a high-efficiency centrifugal filter.

[0047] (3) The solid sulfur after solid-liquid separation is transferred to a vacuum sublimation purification device, where it is sublimated into sulfur vapor at a temperature of 100°C and a vacuum of 0.5 Pa.

[0048] (4) Sulfur vapor is transported through pipelines to a high-efficiency condenser for cooling and condensation into solid sulfur, wherein the internal cooling temperature of the condenser is maintained at -15℃.

[0049] The obtained sulfur product, after analysis and testing, showed a conversion rate of 98.2% and a purity of 99.7%.

[0050] Example 2

[0051] This embodiment illustrates the purification of sulfur produced during the biological desulfurization process.

[0052] (1) The crude sulfur raw material produced in the biological desulfurization process is physically crushed to obtain sulfur particles with an average particle size of 0.5 mm. This is achieved at approximately 20°C and 400 W / cm². 2 At an ultrasonic power density of 1 g / L, the broken sulfur particles were ultrasonically cleaned for 15 minutes in a citric acid aqueous solution.

[0053] (2) The cleaned sulfur particles are transferred to a continuous countercurrent washing device and washed in pure water at a temperature of 30°C and a gauge pressure of 0.2MPa for 40 minutes. The resulting mixture is then separated into solid and liquid by a vacuum belt filter (filter cloth pore size controlled at 250 mesh) under a negative pressure of -0.08MPa.

[0054] (3) The solid sulfur after solid-liquid separation is transferred to a vacuum sublimation purification device. At a temperature of 95°C and a vacuum of 0.5 Pa, the solid sulfur is sublimated into sulfur vapor.

[0055] (4) Sulfur vapor is transported through pipelines to a high-efficiency condenser for cooling and condensation into solid sulfur, wherein the internal cooling temperature of the condenser is maintained at -10℃.

[0056] The obtained sulfur product, after analysis and testing, showed a conversion rate of 99% and a purity of 99.5%.

[0057] Example 3

[0058] This embodiment illustrates the purification of sulfur produced in the Claus process.

[0059] (1) The crude sulfur raw material produced in the Claus process is physically crushed to obtain sulfur particles with a particle size of less than 2 mm. This is done at 25°C and 300 W / cm². 2 At an ultrasonic power density of 1 g / L, the broken sulfur particles were ultrasonically cleaned for 10 minutes in a sodium carbonate aqueous solution.

[0060] (2) The cleaned sulfur particles are transferred to a continuous countercurrent washing device and washed in pure water for 50 minutes at a temperature of 50°C and a gauge pressure of 0.1 MPa. The resulting mixture is then centrifuged and filtered in a high-efficiency solid-liquid separator.

[0061] (3) The solid sulfur after solid-liquid separation is transferred to a vacuum sublimation purification device. At a temperature of 98°C and a vacuum of 1.0 Pa, the solid sulfur is sublimated into sulfur vapor.

[0062] (4) Sulfur vapor is transported through pipelines to a high-efficiency condenser for cooling and condensation into solid sulfur, wherein the internal cooling temperature of the condenser is maintained at -18℃.

[0063] The obtained sulfur product, after analysis and testing, showed a conversion rate of 98.8% and a purity of 99.6%.

[0064] Example 4

[0065] This embodiment illustrates the purification of sulfur, a byproduct of wet desulfurization.

[0066] (1) The sulfur byproduct of wet desulfurization was physically crushed to obtain sulfur particles with an average particle size of 0.5 mm. This was done at approximately 20°C and 50 W / cm². 2 At an ultrasonic power density of 3 g / L, the broken sulfur particles were ultrasonically cleaned for 20 minutes in a citric acid aqueous solution.

[0067] (2) The cleaned sulfur particles are transferred to a continuous countercurrent washing device and washed in pure water for 40 minutes at a temperature of 40°C and a gauge pressure of 0.3 MPa. The resulting mixture is then separated into solid and liquid by a rotary drum solid-liquid separator (the filter cloth pore size is controlled to be 220 mesh).

[0068] (3) The solid sulfur after solid-liquid separation is transferred to a vacuum sublimation purification device. At a temperature of 100°C and a vacuum of 1.0 Pa, the solid sulfur is sublimated into sulfur vapor.

[0069] (4) Sulfur vapor is transported through pipelines to a high-efficiency condenser for cooling and condensation into solid sulfur, wherein the internal cooling temperature of the condenser is maintained at -12℃.

[0070] The obtained sulfur product, after analysis and testing, showed a conversion rate of 98.5% and a purity of 99.4%.

[0071] Example 5

[0072] This embodiment illustrates the purification of sulfur produced in the natural gas desulfurization process.

[0073] (1) The crude sulfur raw material produced in the natural gas desulfurization process is physically crushed to obtain sulfur particles with an average particle size of 1 mm. At a temperature of 25℃ and a pressure of 300 W / cm², 2 At an ultrasonic power density of 1800, the broken sulfur particles were ultrasonically cleaned for 18 minutes in a sodium carbonate aqueous solution with a concentration of 2 g / L.

[0074] (2) The cleaned sulfur particles are transferred to a continuous countercurrent washing device and washed in pure water at a temperature of 55°C and a gauge pressure of 0.2MPa for 60 minutes. The resulting mixture is then separated into solid and liquid by a vacuum belt filter (filter cloth pore size controlled at 250 mesh) under a negative pressure of -0.08MPa.

[0075] (3) The solid sulfur after solid-liquid separation is transferred to a vacuum sublimation purification device. At a temperature of 88°C and a vacuum of 2.0 Pa, the solid sulfur is sublimated into sulfur vapor.

[0076] (4) Sulfur vapor is transported through pipelines to a high-efficiency condenser for cooling and condensation into solid sulfur, wherein the internal cooling temperature of the condenser is maintained at -17℃.

[0077] The obtained sulfur product, after analysis and testing, showed a conversion rate of 99% and a purity of 99.7%.

[0078] Example 6

[0079] This embodiment illustrates the purification of sulfur, a byproduct of coal gasification.

[0080] (1) The sulfur byproduct of coal gasification was physically crushed to obtain sulfur particles with a particle size of less than 2.5 mm. This was done at 20℃ and 500 W / cm². 2 At an ultrasonic power density of 1.5 g / L, the broken sulfur particles were ultrasonically cleaned for 15 minutes in a sodium carbonate aqueous solution.

[0081] (2) The cleaned sulfur particles are transferred to a continuous countercurrent washing device and washed for 50 minutes in pure water circulation countercurrent at a temperature of 50°C and a gauge pressure of 0.1 MPa. The resulting mixture is then effectively separated into solid and liquid by a rotary drum solid-liquid separator.

[0082] (3) The solid sulfur after solid-liquid separation is transferred to a vacuum sublimation purification device. At a temperature of 110°C and a vacuum of 2.0 Pa, the solid sulfur is sublimated into sulfur vapor.

[0083] (4) Sulfur vapor is transported through pipelines to a high-efficiency condenser for cooling and condensation into solid sulfur, wherein the internal cooling temperature of the condenser is maintained at -15℃.

[0084] The obtained sulfur product, after analysis and testing, showed a conversion rate of 99.2% and a purity of 99.3%.

[0085] Example 7

[0086] This example illustrates the purification of sulfur, a byproduct of sulfuric acid production.

[0087] (1) The by-product sulfur from the sulfuric acid production process is physically crushed to obtain sulfur particles with an average particle size of 1 mm. This is done at 25°C and 250 W / cm². 2 At an ultrasonic power density of 3 g / L, the broken sulfur particles were ultrasonically cleaned for 20 minutes in an EDTA aqueous solution.

[0088] (2) The cleaned sulfur particles are transferred to a continuous countercurrent washing device and washed in pure water at a temperature of 35°C and a gauge pressure of 0.2MPa for 60 minutes. The resulting mixture is then separated into solid and liquid by a vacuum belt filter (filter cloth pore size controlled at 250 mesh) under a negative pressure of -0.08MPa.

[0089] (3) The solid sulfur after solid-liquid separation is transferred to a vacuum sublimation purification device. At a temperature of 100°C and a vacuum of 2.5 Pa, the solid sulfur is sublimated into sulfur vapor.

[0090] (4) Sulfur vapor is transported through pipelines to a high-efficiency condenser for cooling and condensation into solid sulfur, wherein the internal cooling temperature of the condenser is maintained at -16℃.

[0091] The obtained sulfur product, after analysis and testing, showed a conversion rate of 99.1% and a purity of 99.3%.

[0092] Example 8

[0093] The sulfur produced in the desulfurization process of complexed iron was purified using the same method as in Example 1, except that the vacuum degree in step (3) was 5 Pa.

[0094] The obtained sulfur product, after analysis and testing, showed a conversion rate of 99.5% and a purity of 99.5%.

[0095] Example 9

[0096] The sulfur produced in the desulfurization process of complexed iron was purified using the same method as in Example 1, except that the gauge pressure in step (2) was 0.

[0097] The obtained sulfur product, after analysis and testing, showed a conversion rate of 85.8% and a purity of 97.3%.

[0098] Comparative Example 1

[0099] The sulfur produced in the desulfurization process of complexed iron was purified using the same method as in Example 1, except that step (2) was not performed.

[0100] The obtained sulfur product, after analysis and testing, showed a conversion rate of 93.5% and a purity of 94.5%.

[0101] Comparative Example 2

[0102] The sulfur produced in the desulfurization process of complexed iron was purified using the same method as in Example 1, except that ultrasound was not performed in step (1).

[0103] The obtained sulfur product, after analysis and testing, showed a conversion rate of 91.5% and a purity of 92.8%.

[0104] Comparative Example 3

[0105] The sulfur produced in the desulfurization process of complexed iron was purified using the same method as in Example 1, except that in step (1), the sodium carbonate aqueous solution was replaced with water.

[0106] The obtained sulfur product, after analysis and testing, showed a conversion rate of 95.5% and a purity of 98%.

[0107] Comparative Example 4

[0108] The sulfur produced in the desulfurization process of complexed iron was purified using the same method as in Example 1. The only difference was that in step (3), the temperature was 115°C and the vacuum degree was 100Pa.

[0109] The obtained sulfur product, after analysis and testing, showed a conversion rate of 96.3% and a purity of 95.8%.

[0110] Comparative Example 5

[0111] The sulfur produced in the desulfurization process of complexed iron was purified using the same method as in Example 1. The only difference was that the cooling temperature inside the condenser was kept at 0°C in step (4).

[0112] The obtained sulfur product, after analysis and testing, showed a conversion rate of 88.6% and a purity of 90.5%.

[0113] As can be seen from Examples 1-9 and Comparative Examples 1-5, the sulfur products prepared by the method of the present invention have high conversion rates and high purity.

[0114] As can be seen from Examples 1 and 9, Example 1 exhibits a relatively high conversion rate and purity compared to Example 9, which involves countercurrent rinsing with pure water circulation under normal pressure (gauge pressure of 0). It is believed that rinsing under pressure can improve the solvent's ability to dissolve impurities.

[0115] Further combining Comparative Examples 1 and 2, it can be seen that compared with Comparative Example 1 (which did not undergo countercurrent immersion) and Comparative Example 2 (which did not undergo ultrasonic cleaning), Examples 1 and 9 have significantly higher purity. This may be because, during the ultrasonic cleaning process, the cleaning solution can not only effectively remove dirt and small particulate impurities from the surface of the sulfur particles, but also penetrate into the sulfur particles. Subsequently, countercurrent immersion is performed to further remove impurities.

[0116] As can be seen from Example 1 and Comparative Example 3, Example 1 has higher purity compared to Comparative Example 3, which uses water as the cleaning solution. This may be because the sodium carbonate aqueous solution is more effective at removing contaminants and fine particulate impurities from the sulfur produced in the complexed iron desulfurization process.

[0117] As can be seen from Examples 1, 8, and Comparative Example 4, Examples 1 and 8 exhibit relatively high purity compared to Comparative Example 4, which underwent vacuum sublimation purification at 115°C and a vacuum of 100 Pa. This may be because a higher vacuum generally favors sublimation and requires a lower temperature. While sulfur can fully sublimate at a vacuum of 100 Pa and a temperature of 115°C, under these conditions, some impurities also sublimate into the final product, resulting in low purity and high energy consumption.

[0118] As can be seen from Example 1 and Comparative Example 5, Example 1 has a relatively high purity compared to Comparative Example 5, which uses a relatively high condensation temperature. This may be because Comparative Example 5 has a higher condensation temperature, allowing some impurities to condense and enter the final product.

[0119] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A process for the purification of sulfur by continuous solid-liquid separation and low-temperature sublimation, wherein, The sulfur purification method includes the following steps: S1. The sulfur raw material is physically crushed into sulfur particles, and the sulfur particles are placed in a cleaning solution for ultrasonic cleaning to obtain cleaned sulfur particles; wherein, the cleaning solution is an aqueous solution including at least one cleaning agent selected from sodium carbonate, EDTA, citric acid, phosphate, and silicate. S2. The cleaned sulfur particles are continuously countercurrently washed with a washing solution, and then solid-liquid separation is performed to obtain solid sulfur after solid-liquid separation. S3. At a temperature of 80–110℃ and a vacuum of 0.01–10Pa, the solid sulfur after solid-liquid separation is sublimated into sulfur vapor. S4. Condense sulfur vapor to obtain solid sulfur.

2. The sulfur purification process of claim 1 wherein, The average particle size of the sulfur particles is 0.1–3 mm, preferably 0.2–2 mm, and more preferably 0.5–1.5 mm.

3. The sulfur purification process of claim 1 or 2, wherein, Step S1 further includes: sieving the sulfur particles to control the particle size of the sulfur particles to be less than 3 mm, preferably less than 2.5 mm, and more preferably less than 2 mm.

4. The sulfur purification process of any one of claims 1 to 3, wherein, The sulfur raw material mentioned in step S1 is selected from sulfur in complex iron desulfurization process, sulfur in biological desulfurization process, sulfur in Claus process, sulfur in natural gas desulfurization process, sulfur in sulfuric acid production process, sulfur by-product of coal gasification and sulfur by-product of wet desulfurization.

5. The sulfur purification process of any one of claims 1 to 4, wherein, The cleaning solution mentioned in step S1 is an aqueous solution including sodium carbonate, EDTA, citric acid or silicate; And / or, the concentration of the cleaning agent in the cleaning solution is 0.1 to 5 g / L.

6. The sulfur purification process of any one of claims 1 to 5, wherein, The conditions of the ultrasonic cleaning in step S1 include: an ultrasonic power density of 50-500 W / cm 2 ; and / or, an ultrasonic cleaning temperature of 10-30℃; and / or, an ultrasonic cleaning time of 5-30 minutes.

7. The sulfur purification process of any one of claims 1 to 6, wherein, The conditions for continuous countercurrent rinsing in step S2 include: a gauge pressure of 0 to 0.5 MPa, preferably 0.1 to 0.3 MPa; and / or a temperature of 25 to 60°C, preferably 30 to 55°C; and / or a rinsing time of 10 to 90 minutes, preferably 40 to 60 minutes.

8. The sulfur purification process of any one of claims 1 to 7, wherein, In step S2, a centrifugal filter, a vacuum belt filter, or a rotary drum solid-liquid separator is used for solid-liquid separation.

9. The sulfur purification process of any one of claims 1 to 8, wherein, In step S3, the vacuum level is 0.1 to 10 Pa, preferably 0.2 to 5 Pa, and more preferably 0.5 to 5 Pa.

10. The sulfur purification process of any one of claims 1 to 9, wherein, The cooling temperature in step S4 is -20℃ to -10℃.