A refining and purifying process for preparing flaky sulfur from coking plant sulfur cake

Abstract

The application relates to a refining and purifying process for preparing flaky sulfur from coking plant sulfur paste, and belongs to the technical field of hazardous waste resource utilization and inorganic chemical purification processes.The refining and purifying process for preparing flaky sulfur comprises the following steps: S1, coking sulfur paste is heated and melted under normal pressure to obtain crude liquid sulfur; S2, the crude liquid sulfur is subjected to closed pressure filtration treatment to obtain clean liquid sulfur; S3, the clean liquid sulfur is sequentially sent into a 1# purification tower, a 2# purification tower, a 3# purification tower and a 4# purification tower for gradient temperature rising distillation treatment to obtain high-temperature sulfur vapor; S4, the high-temperature sulfur vapor from the top of the 2#, 3# and 4# purification towers is subjected to condensation treatment to obtain liquid industrial-grade sulfur; and S5, the liquid industrial-grade sulfur is subjected to heat preservation transportation and slicing to form flaky industrial sulfur.The ash content, acidity and organic impurity content of the prepared flaky sulfur are extremely low, the purity of the sulfur is higher than 99.9%, and the flaky sulfur meets the superior product standard of industrial sulfur.

Description

Technical Field

[0001] This application relates to the fields of hazardous waste resource utilization and inorganic chemical purification technology. More specifically, it relates to a refining and purification process for preparing flaky sulfur using sulfur paste from a coking plant. Background Technology

[0002] Sulfur paste, a byproduct of wet desulfurization of coking coal gas, is a high-impurity hazardous solid waste containing large amounts of tar, heavy metals, free hydrogen sulfide, and colloidal dust. Improper disposal can easily release toxic and odorous gases, and environmental disposal costs are high. Therefore, the purification of sulfur paste to produce industrial sulfur is the mainstream resource utilization path in the industry. Current mainstream processes are divided into three categories: solvent extraction, single-stage melt filtration, and two-stage vacuum distillation, all of which have significant shortcomings. Solvent extraction relies on organic solvents, generating secondary hazardous waste liquid, and the finished product contains solvent, leading to excessive acidity. Single-stage melt filtration only removes coarse particulate impurities, lacking deep distillation for further impurity removal, resulting in a sulfur content of less than 93%, failing to meet the GB / T2449.1-2021 Grade B sulfur standard. Two-stage vacuum distillation uses a single heat transfer oil for heating, resulting in high maintenance costs for vacuum equipment, inability to match the differentiated distillation temperatures across multiple stages, and inability to recover low-temperature waste heat, leading to high energy consumption.

[0003] Existing multi-stage distillation processes generally use a single heat transfer oil for heating. The heat transfer oil can only withstand temperatures up to about 400℃, which is insufficient for deep removal of heavy metals at temperatures up to 450℃. Forcing a temperature increase will cause the heat transfer oil to crack and coke. Although full-tower electromagnetic heating provides precise temperature control, it significantly increases overall energy consumption and is not economically viable. At the same time, traditional processes lack a pretreatment stage to remove free hydrogen sulfide from the raw materials, resulting in a large amount of H2S escaping without organization during the melting stage. The sulfur vapor at the top of the tower is simply condensed in a single stage, failing to separate tar and trace amounts of sulfur mist in stages. Light hydrocarbon non-condensable gases are directly burned, wasting combustible resources and causing trace amounts of sulfur to be emitted with the flue gas, resulting in severe sulfur resource depletion. Most processes only perform one pressure filtration during the melting stage, and there is no secondary deep impurity removal after distillation and condensation, making it difficult to consistently meet the standards for heavy metal and ash content in the finished product. Currently, the industry lacks a fully enclosed, purely physical, continuous process that integrates negative pressure pre-desulfurization treatment, regenerative thermal oil-electromagnetic bidirectional coupling heating, three-stage catalytic phase separation condensation, closed-loop recovery of non-condensable gas dry desulfurization, secondary fine filtration of liquid sulfur, and tail gas sulfur mist film recovery. It is difficult to simultaneously achieve multiple goals such as low energy consumption, ultra-high purity, complete closed-loop sulfur element, no secondary hazardous waste, and tail gas resource utilization. This is a technical bottleneck that existing technologies have been unable to solve for a long time. Summary of the Invention

[0004] In order to solve the technical problems mentioned in the background art, this application provides a refining and purification process for preparing flaky sulfur using sulfur paste from a coking plant.

[0005] A refining and purification process for preparing flaky sulfur from sulfur paste from a coking plant includes the following steps: S1. The coking sulfur paste is fed into the melting tank through a closed feeding method and heated and melted under normal pressure to obtain crude liquid sulfur; S2. The crude liquid sulfur is subjected to closed pressure filtration to obtain clean liquid sulfur; S3. The clean liquid sulfur is sequentially fed into purification tower 1, purification tower 2, purification tower 3 and purification tower 4 for gradient heating distillation to obtain high temperature sulfur vapor. S4. All the high-temperature sulfur vapor from the top of purification towers #2, #3, and #4 is collected and sent to a three-stage air cooler for condensation treatment to obtain liquid industrial-grade sulfur. S5. Liquid industrial-grade sulfur is transported under heat preservation and slicing to obtain flaky industrial sulfur.

[0006] Furthermore, in step S1, the melting tank is heated indirectly by heat transfer oil in a closed system, the melting temperature is controlled at 130-150℃, and the melting holding time is 30-60min.

[0007] Furthermore, in step S2, the closed-loop filtration adopts a fully automatic plate-type closed-loop filter press, the filtration operation pressure is controlled at 0.35-0.55MPa, the filtration accuracy is 200-300 mesh, and the filtration temperature is maintained at 130-150℃.

[0008] Further, the gradient temperature distillation process in step S3 is specifically as follows: the distillation temperature of purification tower #1 is 240-260℃, the distillation temperature of purification tower #2 is 340-360℃, the distillation temperature of purification tower #3 is 390-410℃, and the distillation temperature of purification tower #4 is 440-450℃.

[0009] Furthermore, in step S3, the low-boiling-point impurity waste gas from the top of the No. 1 purification tower is separately drawn off and sent to the high-temperature incineration unit in the coking workshop for oxidation and decomposition. The incineration flue gas is then connected to the original desulfurization system of the coking plant for purification before being discharged.

[0010] Furthermore, in step S4, the three-stage air cooler is divided into a first-stage high-temperature pre-cooling stage, a second-stage medium-temperature condensing stage, and a third-stage low-temperature fine cooling stage.

[0011] Furthermore, the temperature of the first-stage high-temperature precooling section is controlled at 240-260℃.

[0012] Furthermore, the temperature of the secondary medium-temperature condensation section is controlled at 200-220℃.

[0013] Furthermore, the cooling temperature of the three-stage low-temperature fine cooling section is controlled at 145-155℃.

[0014] Furthermore, in step S5, the liquid industrial-grade sulfur is transported in a closed system using a heat-traced and insulated pipeline, with the pipeline's heat tracing temperature remaining constant at 145-155℃.

[0015] Furthermore, the slicing process employs a drum-type sulfur slicer, with the drum cooling water temperature controlled at 25-35℃.

[0016] Furthermore, in step S5, the flake industrial sulfur has a sulfur content ≥99.5%, ash content ≤0.10%, acidity ≤0.005%, and arsenic content ≤0.011%.

[0017] In summary, this application has the following beneficial effects: This application incorporates a closed-plate filter press pretreatment process to pre-intercept solid ash and mechanical impurities generated after sulfur paste melting, preventing solid impurities from directly entering the distillation system and becoming difficult to separate. This significantly reduces the ash content of the finished sulfur, minimizing blockage and wear on the distillation tower and condensation equipment caused by solid impurities at the source. Furthermore, by setting up a four-stage gradient heating distillation device with progressively increasing distillation temperatures, it achieves the step-by-step removal of low-boiling-point acidic impurities, medium-boiling-point organic impurities, and high-boiling-point heavy impurities. This overcomes the deficiency of two-stage distillation in completely separating multiple impurities, allowing for the removal of impurities of different boiling points within the sulfur paste system. Impurities within the specified temperature range can be removed directionally, effectively reducing product acidity and residual organic matter. A three-stage gradient air-cooling condensation process replaces single-stage direct cooling and simple two-stage condensation structures, progressively controlling the sulfur vapor cooling rate to prevent liquid sulfur flow imbalance and slice adhesion / caking caused by sudden sulfur vapor cooling, ensuring subsequent slice forming quality and product appearance. By limiting the precise gradient temperature range of the four-stage distillation tower, the problem of high-boiling-point impurities failing to vaporize and separate due to excessively low overall distillation temperature is avoided, ensuring the distillation and purification reaction remains under optimal conditions and maximizing sulfur purification efficiency. Furthermore, this application employs a closed-loop feeding, closed-loop pressure filtration, and closed-loop conveying process, coupled with centralized incineration desulfurization of low-boiling-point waste gas, ensuring no material leakage and no fugitive hydrogen sulfide emissions throughout the production process, meeting the environmental protection requirements of coking workshops. Each process and parameter in this application works in synergy and is indispensable, ultimately resulting in a stable purity of over 99.9% for the obtained flake sulfur, meeting the requirements of the national standard for superior grade products. The overall product yield is high, taking into account product quality, production yield, and environmental benefits, and is more suitable for the resource-based, industrialized, and continuous production of sulfur paste in coking plants. Detailed Implementation

[0018] The present application will be further described in detail below with reference to the embodiments.

[0019] Examples 1-3 provide a refining and purification process for preparing flaky sulfur using sulfur paste from a coking plant.

[0020] Example 1 A refining and purification process for preparing flaky sulfur from sulfur paste from a coking plant includes the following steps: S1. The coking sulfur paste is fed into the melting tank through a closed feeding method. It is melted by closed indirect heating with heat transfer oil under normal pressure. The melting temperature is controlled at 130℃ and the melting holding time is 30min to obtain crude liquid sulfur. S2. The crude liquid sulfur is subjected to closed-loop filtration using a fully automatic plate-type closed filter press. The filtration operation pressure is controlled at 0.35MPa, the filtration accuracy is 200 mesh, and the filtration temperature is maintained at 130℃ to obtain clean liquid sulfur. S3. The clean liquid sulfur is sequentially fed into purification tower 1, purification tower 2, purification tower 3, and purification tower 4 for gradient temperature distillation to obtain high-temperature sulfur vapor. Specifically, the gradient temperature distillation process is as follows: the distillation temperature of purification tower 1 is 240℃, the distillation temperature of purification tower 2 is 340℃, the distillation temperature of purification tower 3 is 390℃, and the distillation temperature of purification tower 4 is 440℃. S4. The low-boiling-point impurity waste gas from the top of the No. 1 purification tower is separately drawn out and sent to the high-temperature incineration unit in the coking workshop for oxidation and decomposition. The incineration flue gas is then purified by the existing desulfurization system of the coking plant before being discharged. All the high-temperature sulfur vapors from the top of the No. 2, No. 3, and No. 4 purification towers are collected and sent to a three-stage air cooler consisting of a primary high-temperature precooling section, a secondary medium-temperature condensing section, and a tertiary low-temperature fine cooling section for condensation treatment. The temperature of the primary high-temperature precooling section is controlled at 240℃, the temperature of the secondary medium-temperature condensing section is controlled at 200℃, and the cooling temperature of the tertiary low-temperature fine cooling section is controlled at 145℃ to obtain liquid industrial-grade sulfur. S5. Liquid industrial-grade sulfur is transported in a closed system using a heat-traced and insulated pipeline. The pipeline heating temperature is kept constant at 145℃. The sulfur is then sliced ​​using a roller-type sulfur slicer. The cooling water temperature of the roller is controlled at 25℃ to obtain flaky industrial sulfur.

[0021] Example 2 S1. The coking sulfur paste is fed into the melting tank through a closed feeding method. It is melted by closed indirect heating with heat transfer oil under normal pressure. The melting temperature is controlled at 140℃ and the melting holding time is 45min to obtain crude liquid sulfur. S2. The crude liquid sulfur is subjected to closed-loop filtration using a fully automatic plate-type closed filter press. The filtration operation pressure is controlled at 0.45MPa, the filtration accuracy is 250 mesh, and the filtration temperature is maintained at 140℃ to obtain clean liquid sulfur. S3. The clean liquid sulfur is sequentially fed into purification tower 1, purification tower 2, purification tower 3, and purification tower 4 for gradient temperature distillation to obtain high-temperature sulfur vapor. Specifically, the gradient temperature distillation process is as follows: the distillation temperature of purification tower 1 is 250℃, the distillation temperature of purification tower 2 is 350℃, the distillation temperature of purification tower 3 is 400℃, and the distillation temperature of purification tower 4 is 445℃. S4. The low-boiling-point impurity waste gas from the top of the No. 1 purification tower is separately drawn out and sent to the high-temperature incineration unit in the coking workshop for oxidation and decomposition. The incineration flue gas is then purified by the existing desulfurization system of the coking plant before being discharged. All the high-temperature sulfur vapors from the top of the No. 2, No. 3, and No. 4 purification towers are collected and sent to a three-stage air cooler consisting of a primary high-temperature precooling section, a secondary medium-temperature condensing section, and a tertiary low-temperature fine cooling section for condensation treatment. The temperature of the primary high-temperature precooling section is controlled at 250℃, the temperature of the secondary medium-temperature condensing section is controlled at 210℃, and the cooling temperature of the tertiary low-temperature fine cooling section is controlled at 150℃ to obtain liquid industrial-grade sulfur. S5. Liquid industrial-grade sulfur is transported in a closed system using a heat-traced and insulated pipeline. The pipeline heating temperature is kept constant at 150°C. The sulfur is then sliced ​​using a roller-type sulfur slicer. The cooling water temperature of the roller is controlled at 30°C to obtain flaky industrial sulfur.

[0022] Example 3 S1. The coking sulfur paste is fed into the melting tank through a closed feeding method. It is melted by closed indirect heating with heat transfer oil under normal pressure. The melting temperature is controlled at 150℃ and the melting holding time is 60min to obtain crude liquid sulfur. S2. The crude liquid sulfur is subjected to closed-loop filtration using a fully automatic plate-type closed filter press. The filtration operation pressure is controlled at 0.55 MPa, the filtration accuracy is 300 mesh, and the filtration temperature is maintained at 150℃ to obtain clean liquid sulfur. S3. The clean liquid sulfur is sequentially fed into purification tower 1, purification tower 2, purification tower 3, and purification tower 4 for gradient temperature distillation to obtain high-temperature sulfur vapor. Specifically, the gradient temperature distillation process is as follows: the distillation temperature of purification tower 1 is 260℃, the distillation temperature of purification tower 2 is 360℃, the distillation temperature of purification tower 3 is 410℃, and the distillation temperature of purification tower 4 is 450℃. S4. The low-boiling-point impurity waste gas from the top of the No. 1 purification tower is separately drawn out and sent to the high-temperature incineration unit in the coking workshop for oxidation and decomposition. The incineration flue gas is then purified by the existing desulfurization system of the coking plant before being discharged. All the high-temperature sulfur vapors from the top of the No. 2, No. 3, and No. 4 purification towers are collected and sent to a three-stage air cooler consisting of a primary high-temperature precooling section, a secondary medium-temperature condensing section, and a tertiary low-temperature fine cooling section for condensation treatment. The temperature of the primary high-temperature precooling section is controlled at 260℃, the temperature of the secondary medium-temperature condensing section is controlled at 220℃, and the cooling temperature of the tertiary low-temperature fine cooling section is controlled at 155℃ to obtain liquid industrial-grade sulfur. S5. Liquid industrial-grade sulfur is transported in a closed system using a heat-traced and insulated pipeline. The pipeline heating temperature is kept constant at 155℃. The sulfur is then sliced ​​using a roller-type sulfur slicer. The cooling water temperature of the roller is controlled at 35℃ to obtain flaky industrial sulfur.

[0023] Comparative Example 1 A refining and purification process for preparing flaky sulfur from sulfur paste from a coking plant includes the following steps: S1. The coking sulfur paste is fed into the melting tank through a closed feeding method. It is melted by closed indirect heating with heat transfer oil under normal pressure. The melting temperature is controlled at 130℃ and the melting holding time is 30min to obtain crude liquid sulfur. S2. The crude sulfur liquid is sequentially fed into purification towers 1, 2, 3, and 4 for gradient temperature distillation to obtain high-temperature sulfur vapor. Specifically, the gradient temperature distillation process is as follows: the distillation temperature of purification tower 1 is 240℃, the distillation temperature of purification tower 2 is 340℃, the distillation temperature of purification tower 3 is 390℃, and the distillation temperature of purification tower 4 is 440℃. S3. The low-boiling-point impurity waste gas from the top of the No. 1 purification tower is separately drawn out and sent to the high-temperature incineration unit in the coking workshop for oxidation and decomposition. The incineration flue gas is then purified by the existing desulfurization system of the coking plant before being discharged. All the high-temperature sulfur vapors from the top of the No. 2, No. 3, and No. 4 purification towers are collected and sent to a three-stage air cooler consisting of a primary high-temperature precooling section, a secondary medium-temperature condensing section, and a tertiary low-temperature fine cooling section for condensation treatment. The temperature of the primary high-temperature precooling section is controlled at 240℃, the temperature of the secondary medium-temperature condensing section is controlled at 200℃, and the cooling temperature of the tertiary low-temperature fine cooling section is controlled at 145℃ to obtain liquid industrial-grade sulfur. S4. Liquid industrial-grade sulfur is transported in a closed system using a heat-traced and insulated pipeline. The pipeline heating temperature is kept constant at 145℃. The sulfur is then sliced ​​using a drum-type sulfur slicer. The cooling water temperature of the drum is controlled at 25℃ to obtain flaky industrial sulfur.

[0024] Comparative Example 2 A refining and purification process for preparing flaky sulfur from sulfur paste from a coking plant includes the following steps: S1. The coking sulfur paste is fed into the melting tank through a closed feeding method. It is melted by closed indirect heating with heat transfer oil under normal pressure. The melting temperature is controlled at 130℃ and the melting holding time is 30min to obtain crude liquid sulfur. S2. The crude liquid sulfur is subjected to closed-loop filtration using a fully automatic plate-type closed filter press. The filtration operation pressure is controlled at 0.35MPa, the filtration accuracy is 200 mesh, and the filtration temperature is maintained at 130℃ to obtain clean liquid sulfur. S3. The clean liquid sulfur is sequentially fed into purification tower 1 and purification tower 2 for gradient temperature distillation to obtain high-temperature sulfur vapor. Specifically, the gradient temperature distillation is performed at a distillation temperature of 240℃ in purification tower 1 and 440℃ in purification tower 2. S4. The low-boiling-point impurity waste gas from the top of the No. 1 purification tower is separately drawn out and sent to the high-temperature incineration unit in the coking workshop for oxidation and decomposition. The incineration flue gas is then purified by the existing desulfurization system of the coking plant before being discharged. All the high-temperature sulfur vapor from the top of the No. 2 purification tower is collected and sent to a three-stage air cooler consisting of a primary high-temperature precooling section, a secondary medium-temperature condensing section, and a tertiary low-temperature fine cooling section for condensation treatment. The temperature of the primary high-temperature precooling section is controlled at 240℃, the temperature of the secondary medium-temperature condensing section is controlled at 200℃, and the cooling temperature of the tertiary low-temperature fine cooling section is controlled at 145℃ to obtain liquid industrial-grade sulfur. S5. Liquid industrial-grade sulfur is transported in a closed system using a heat-traced and insulated pipeline. The pipeline heating temperature is kept constant at 145℃. The sulfur is then sliced ​​using a roller-type sulfur slicer. The cooling water temperature of the roller is controlled at 25℃ to obtain flaky industrial sulfur.

[0025] Comparative Example 3 A refining and purification process for preparing flaky sulfur from sulfur paste from a coking plant includes the following steps: S1. The coking sulfur paste is fed into the melting tank through a closed feeding method. It is melted by closed indirect heating with heat transfer oil under normal pressure. The melting temperature is controlled at 130℃ and the melting holding time is 30min to obtain crude liquid sulfur. S2. The crude liquid sulfur is subjected to closed-loop filtration using a fully automatic plate-type closed filter press. The filtration operation pressure is controlled at 0.35MPa, the filtration accuracy is 200 mesh, and the filtration temperature is maintained at 130℃ to obtain clean liquid sulfur. S3. The clean liquid sulfur is sequentially fed into purification tower 1, purification tower 2, purification tower 3, and purification tower 4 for gradient temperature distillation to obtain high-temperature sulfur vapor. Specifically, the gradient temperature distillation process is as follows: the distillation temperature of purification tower 1 is 240℃, the distillation temperature of purification tower 2 is 340℃, the distillation temperature of purification tower 3 is 390℃, and the distillation temperature of purification tower 4 is 440℃. S4. The low-boiling-point impurity waste gas from the top of the No. 1 purification tower is separately drawn out and sent to the high-temperature incineration unit in the coking workshop for oxidation and decomposition. The incineration flue gas is then purified by the existing desulfurization system of the coking plant before being discharged. All the high-temperature sulfur vapors from the top of the No. 2, No. 3, and No. 4 purification towers are collected and sent to the air cooler for condensation treatment. The cooling temperature of the air cooler is controlled at 145℃ to obtain liquid industrial-grade sulfur. S5. Liquid industrial-grade sulfur is transported in a closed system using a heat-traced and insulated pipeline. The pipeline heating temperature is kept constant at 145℃. The sulfur is then sliced ​​using a roller-type sulfur slicer. The cooling water temperature of the roller is controlled at 25℃ to obtain flaky industrial sulfur.

[0026] Comparative Example 4 A refining and purification process for preparing flaky sulfur from sulfur paste from a coking plant includes the following steps: S1. The coking sulfur paste is fed into the melting tank through a closed feeding method. It is melted by closed indirect heating with heat transfer oil under normal pressure. The melting temperature is controlled at 130℃ and the melting holding time is 30min to obtain crude liquid sulfur. S2. The crude liquid sulfur is subjected to closed-loop filtration using a fully automatic plate-type closed filter press. The filtration operation pressure is controlled at 0.35MPa, the filtration accuracy is 200 mesh, and the filtration temperature is maintained at 130℃ to obtain clean liquid sulfur. S3. The clean liquid sulfur is sequentially fed into purification tower 1, purification tower 2, purification tower 3, and purification tower 4 for gradient temperature distillation to obtain high-temperature sulfur vapor. Specifically, the gradient temperature distillation process is as follows: the distillation temperature of purification tower 1 is 240℃, the distillation temperature of purification tower 2 is 340℃, the distillation temperature of purification tower 3 is 390℃, and the distillation temperature of purification tower 4 is 440℃. S4. The low-boiling-point impurity waste gas from the top of the No. 1 purification tower is separately drawn out and sent to the high-temperature incineration unit in the coking workshop for oxidation and decomposition. The incineration flue gas is then purified by the existing desulfurization system of the coking plant before being discharged. All the high-temperature sulfur vapor from the top of the No. 2, No. 3, and No. 4 purification towers is collected and sent to a two-stage air cooler, which is divided into a primary high-temperature pre-cooling section and a secondary low-temperature fine cooling section, for condensation treatment. The temperature of the primary high-temperature pre-cooling section is controlled at 240℃, and the cooling temperature of the secondary low-temperature fine cooling section is controlled at 145℃, to obtain liquid industrial-grade sulfur. S5. Liquid industrial-grade sulfur is transported in a closed system using a heat-traced and insulated pipeline. The pipeline heating temperature is kept constant at 145℃. The sulfur is then sliced ​​using a roller-type sulfur slicer. The cooling water temperature of the roller is controlled at 25℃ to obtain flaky industrial sulfur.

[0027] Comparative Example 5 A refining and purification process for preparing flaky sulfur from sulfur paste from a coking plant includes the following steps: S1. The coking sulfur paste is fed into the melting tank through a closed feeding method. It is melted by closed indirect heating with heat transfer oil under normal pressure. The melting temperature is controlled at 130℃ and the melting holding time is 30min to obtain crude liquid sulfur. S2. The crude liquid sulfur is subjected to closed-loop filtration using a fully automatic plate-type closed filter press. The filtration operation pressure is controlled at 0.35MPa, the filtration accuracy is 200 mesh, and the filtration temperature is maintained at 130℃ to obtain clean liquid sulfur. S3. The clean liquid sulfur is sequentially fed into purification tower 1, purification tower 2, purification tower 3, and purification tower 4 for gradient temperature distillation to obtain high-temperature sulfur vapor. Specifically, the gradient temperature distillation is as follows: the distillation temperature of purification tower 1 is 200℃, the distillation temperature of purification tower 2 is 300℃, the distillation temperature of purification tower 3 is 350℃, and the distillation temperature of purification tower 4 is 400℃. S4. The low-boiling-point impurity waste gas from the top of the No. 1 purification tower is separately drawn out and sent to the high-temperature incineration unit in the coking workshop for oxidation and decomposition. The incineration flue gas is then purified by the existing desulfurization system of the coking plant before being discharged. All the high-temperature sulfur vapors from the top of the No. 2, No. 3, and No. 4 purification towers are collected and sent to a three-stage air cooler consisting of a primary high-temperature precooling section, a secondary medium-temperature condensing section, and a tertiary low-temperature fine cooling section for condensation treatment. The temperature of the primary high-temperature precooling section is controlled at 240℃, the temperature of the secondary medium-temperature condensing section is controlled at 200℃, and the cooling temperature of the tertiary low-temperature fine cooling section is controlled at 145℃ to obtain liquid industrial-grade sulfur. S5. Liquid industrial-grade sulfur is transported in a closed system using a heat-traced and insulated pipeline. The pipeline heating temperature is kept constant at 145℃. The sulfur is then sliced ​​using a roller-type sulfur slicer. The cooling water temperature of the roller is controlled at 25℃ to obtain flaky industrial sulfur.

[0028] Performance testing The performance of the flake industrial sulfur prepared in Examples 1-3 and Comparative Examples 1-5 of this application was tested, and the specific test contents are as follows: Ash content: Referring to the national standard GB / T 2449.1-2021 "Industrial Sulfur Part 1: Solid Products", the high-temperature ignition method was used for testing. A porcelain crucible was first placed in a muffle furnace at 800℃ and ignited for 30 minutes. After drying and cooling, it was weighed to constant weight. A 5.000g sulfur sample was accurately weighed and placed in the constant-weight crucible. It was first slowly carbonized at a low temperature to avoid sulfur splashing, then heated to 800℃ and ignited for 90 minutes. Afterward, it was removed, placed in a desiccator, cooled to room temperature, and weighed. This process of ignition, cooling, and weighing was repeated until constant weight was achieved. The ash content percentage was calculated based on the difference in mass of the residue before and after ignition, expressed as a percentage (%). Acidity: The national standard acid-base potentiometric titration method was used for determination. 25.0 g of sulfur sample was weighed and placed in an Erlenmeyer flask. 100 mL of carbon dioxide-free distilled water was added, and the flask was sealed, shaken, and soaked for 30 min. After standing and separation, the upper clear leachate was collected. Using bromothymol blue as an indicator, titration was performed with a 0.01 mol / L sodium hydroxide standard titration solution. A blank control experiment was also performed. The acidic impurity content in the sample, expressed as sulfuric acid, was calculated based on the sodium hydroxide consumption, in percentages (%). Organic matter content: The Soxhlet extraction method with carbon tetrachloride was used for determination. 10.0 g of uniformly ground sulfur sample was weighed and placed in the filter paper thimble of the Soxhlet extractor. Analytical grade carbon tetrachloride was used as the extraction solvent, and the mixture was continuously refluxed in a water bath at 75°C for 4 hours to fully dissolve the organic impurities inside the sample. After extraction, the solvent was recovered, and the residual organic matter was dried in an oven at 105°C until constant weight. The mass of the organic residue was weighed, and the mass fraction of organic impurities was calculated (in %). Sulfur purity: Referring to the national standard GB / T 2449.1-2021 "Industrial Sulfur Part 1: Solid Products", 2.000g of dried flake sulfur sample was accurately weighed using the difference method. The total mass of four impurities—moisture, ash, acidic substances, and organic impurities—was measured and subtracted sequentially. The calculation formula is: Sulfur purity = 100% - Moisture mass fraction - Ash mass fraction - Acidity converted mass fraction - Organic matter mass fraction. Two parallel determinations were performed, and the arithmetic mean was taken as the final result. The unit is %. Sulfur yield: Based on the initial dry basis sulfur content of coking sulfur paste, the percentage of qualified flake sulfur product produced is calculated, in % (%). The specific test results are shown in Table 1.

[0029] Table 1. Performance parameters of the flake-shaped industrial sulfur prepared in Examples 1-3 and Comparative Examples 1-5 ; As shown in Table 1, the flaky industrial sulfur prepared in this application has extremely low ash content, acidity, and organic impurity content, with a sulfur purity exceeding 99.9%, meeting the standards for superior-grade industrial sulfur. Furthermore, the product yield reaches over 92.6%, demonstrating significantly better purification and production effects than the comparative examples. Comparative examples 1-5, by omitting the pressure filtration process, reducing the number of distillation columns, simplifying the condensation section structure, and lowering the distillation temperature, all resulted in incomplete impurity removal, leading to a significant decrease in product purity and yield. This application, through the synergistic combination of closed-loop pressure filtration, four-stage gradient distillation, and three-stage gradient condensation, can efficiently remove various impurities from sulfur paste, significantly improving sulfur product purity and yield. The fully closed process also avoids material leakage and waste gas pollution, making it suitable for continuous industrial production in coking plants.

[0030] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A refining and purification process for preparing flaky sulfur using sulfur paste from a coking plant, characterized in that, Includes the following steps: S1. The coking sulfur paste is fed into the melting tank through a closed feeding method and heated and melted under normal pressure to obtain crude liquid sulfur; S2. The crude liquid sulfur is subjected to closed pressure filtration to obtain clean liquid sulfur; S3. The clean liquid sulfur is sequentially fed into purification tower 1, purification tower 2, purification tower 3 and purification tower 4 for gradient heating distillation to obtain high temperature sulfur vapor. S4. All the high-temperature sulfur vapor from the top of purification towers #2, #3, and #4 is collected and sent to a three-stage air cooler for condensation treatment to obtain liquid industrial-grade sulfur. S5. Liquid industrial-grade sulfur is transported under heat preservation and slicing to obtain flaky industrial sulfur.

2. The refining and purification process for preparing flaky sulfur using sulfur paste from a coking plant according to claim 1, characterized in that, In step S1, the melting tank is heated indirectly by heat transfer oil in a closed system. The melting temperature is controlled at 130-150℃ and the melting holding time is 30-60 minutes.

3. The refining and purification process for preparing flaky sulfur using sulfur paste from a coking plant according to claim 1, characterized in that, In step S2, the closed filtration adopts a fully automatic plate-type closed filter press, the filtration operation pressure is controlled at 0.35-0.55MPa, the filtration accuracy is 200-300 mesh, and the filtration temperature is maintained at 130-150℃.

4. The refining and purification process for preparing flaky sulfur using sulfur paste from a coking plant according to claim 1, characterized in that, The gradient temperature distillation process in step S3 is as follows: the distillation temperature of purification tower #1 is 240-260℃, the distillation temperature of purification tower #2 is 340-360℃, the distillation temperature of purification tower #3 is 390-410℃, and the distillation temperature of purification tower #4 is 440-450℃.

5. The refining and purification process for preparing flaky sulfur using sulfur paste from a coking plant according to claim 1, characterized in that, In step S3, the low-boiling-point impurity waste gas from the top of the No. 1 purification tower is separately drawn off and sent to the high-temperature incineration unit in the coking workshop for oxidation and decomposition. The incineration flue gas is then connected to the original desulfurization system of the coking plant for purification before being discharged.

6. The refining and purification process for preparing flaky sulfur using sulfur paste from a coking plant according to claim 1, characterized in that, In step S4, the three-stage air cooler is divided into a first-stage high-temperature pre-cooling stage, a second-stage medium-temperature condensing stage, and a third-stage low-temperature fine cooling stage.

7. The refining and purification process for preparing flaky sulfur using sulfur paste from a coking plant according to claim 6, characterized in that, The temperature of the first-stage high-temperature precooling section is controlled at 240-260℃; the temperature of the second-stage medium-temperature condensing section is controlled at 200-220℃; and the cooling temperature of the third-stage low-temperature fine cooling section is controlled at 145-155℃.

8. The refining and purification process for preparing flaky sulfur using sulfur paste from a coking plant according to claim 1, characterized in that, In step S5, liquid industrial-grade sulfur is transported in a closed system using a heated and insulated pipeline, with the pipeline heating temperature maintained at a constant 145-155℃; the slicing process uses a drum-type sulfur slicer, with the drum cooling water temperature controlled at 25-35℃.

9. The refining and purification process for preparing flaky sulfur using sulfur paste from a coking plant according to claim 1, characterized in that, In step S5, the flaky industrial sulfur has a sulfur purity of ≥99.5%, ash content of ≤0.10%, acidity of ≤0.005%, and arsenic content of ≤0.011%.