Process for preparing sulfur by purifying sulfur paste

Abstract

The invention provides a process for preparing sulfur by purifying sulfur paste, and relates to the technical field of sulfur preparation, and the process comprises the following steps: raw material pretreatment: crushing the sulfur paste until the particle size is 1-5mm, putting the crushed sulfur paste into a stirring container, adding water, and stirring at the stirring speed of 100-200r / min for 10-20min, acid washing: a sulfuric acid solution with the mass fraction of 5%-15% is added into the pretreated sulfur paste, the solid-to-liquid ratio of the sulfuric acid solution to the sulfur paste is (1: 2)-(1: 5), stirring reaction is conducted at the temperature of 40-60 DEG C, the stirring speed is 200-300 r / min, the reaction time is 30-60 min, sulfuric acid reacts with metal impurities such as iron, calcium and magnesium metal compounds in the sulfur paste to generate soluble metal salt, and the soluble metal salt is washed with water to obtain the sulfur paste. According to the method disclosed by the invention, most impurities such as organic impurities, heavy metal salts and metal sulfides in the sulfur paste can be effectively removed through acid-alkali washing, and further purification is carried out in combination with a sublimation method, so that the purity of the prepared sulfur can reach 99% or above, and the application requirements of high-quality sulfur are met.

Description

Technical Field

[0001] The invention relates to the technical field of a process for purifying sulfur paste to prepare sulfur, and in particular to a process for purifying sulfur paste to prepare sulfur. Background Art

[0002] Sulfur paste is a by-product produced during the desulfurization process in industries such as coal gas purification and petrochemicals. Its main component is elemental sulfur, but it also contains a large amount of impurities such as coal tar, heavy metal salts, mud and ferrous sulfide. The presence of these impurities not only affects the purity and quality of sulfur, but also limits the resource utilization of sulfur paste. At present, the treatment methods for sulfur paste mainly include sulfur melting method, hot filtration method and chemical oxidation method.

[0003] The sulfur melting method is to melt the sulfur in the sulfur paste by heating and then separate it from impurities. However, this method has the problems of high energy consumption and low processing efficiency, and it is easy to generate a large amount of waste gas, such as hydrogen sulfide, during the heating process, causing serious pollution to the environment. Although the hot filtration method can improve the separation efficiency to a certain extent, due to the complexity of the impurities in the sulfur paste, it is easy to cause the filtration equipment to be blocked, increase the equipment maintenance cost, and make it difficult to achieve deep purification. The chemical oxidation method uses an oxidant to oxidize the sulfide in the sulfur paste into soluble substances such as sulfates, thereby realizing the separation of sulfur, but this method requires a large amount of chemical reagents and has high processing costs. At the same time, it will produce a large amount of wastewater, which is difficult to subsequently treat.

[0004] With the continuous improvement of sulfur quality requirements and the increasingly stringent environmental protection regulations, the development of an efficient, environmentally friendly and low-cost process for purifying sulfur paste and preparing sulfur has important practical significance. The acid-base washing + sublimation process proposed in the present invention aims to overcome the shortcomings of the existing technology and achieve efficient purification of sulfur paste and high-quality preparation of sulfur. Summary of the Invention

[0005] To achieve the above object, the present invention proposes a process for purifying sulfur paste to prepare sulfur, comprising the following steps:

[0006] Raw material pretreatment: crush the sulfur paste to a particle size of 1-5mm, put the crushed sulfur paste into a mixing container, add water and stir, control the stirring speed at 100-200r / min, and the stirring time is 10-20min.

[0007] Acid washing: add 5%-15% sulfuric acid solution to the pretreated sulfur paste, with a solid-liquid ratio of sulfuric acid solution to sulfur paste of 1:2-1:5, and stir the reaction at a temperature of 40-60°C, a stirring speed of 200-300r / min, and a reaction time of 30-60min. The sulfuric acid reacts with the metal impurities iron, calcium, and magnesium metal compounds in the sulfur paste to generate soluble metal salts.

[0008] Alkali washing: transfer the acid-washed sulfur paste filter cake to another stirring container, add 5%-10% sodium hydroxide solution by mass, the solid-liquid ratio of sodium hydroxide solution to sulfur paste filter cake is 1:2-1:4, stir and react at a temperature of 30-50°C, a stirring speed of 150-250r / min, and a reaction time of 20-40min.

[0009] Washing: Use deionized water to wash the sulfur paste filter cake after alkali washing for multiple times. During washing, the solid-liquid ratio of deionized water to sulfur paste filter cake is 1:1-1:3, the stirring speed is 100-150r / min, the stirring time is 5-10min, and the solid-liquid separation is carried out by filtration.

[0010] Drying: Place the washed sulfur paste filter cake into the drying equipment and dry it at a temperature of 80-100°C and a vacuum degree of -0.08 to -0.06MPa.

[0011] Sublimation: Place the dry sulfur paste into a sublimation device with a temperature of 180-220°C and a pressure of 0.01-0.05MPa to allow the sulfur to sublime.

[0012] In one example, the sulfur paste is crushed to a particle size of 1-5 mm, which facilitates subsequent treatment and full contact with acid and alkali solutions. The sulfur paste is placed in a stirring container to initially disperse the sulfur paste and remove impurities and dust attached to the surface of the sulfur paste.

[0013] In one example, the sulfuric acid reacts with the metal in the sulfur paste to remove metal impurities from the sulfur paste. After the reaction is completed, the filtration device performs solid-liquid separation to obtain the sulfur paste filter cake after acid washing and acid washing wastewater. The acid washing wastewater is centrally treated to recover the useful components of the metal salts therein, thereby realizing the recycling of resources.

[0014] In one example, the sodium hydroxide solution reacts with the acidic impurities and organic impurities remaining in the sulfur paste to generate soluble substances, further removing the impurities. After the reaction is completed, the filtration device performs solid-liquid separation to obtain the sulfur paste filter cake after alkaline washing and alkaline washing wastewater. The alkaline washing wastewater is also centrally treated to avoid polluting the environment.

[0015] In one example, the deionized water is used to wash the sulfur paste filter cake after alkaline washing, and the pH value of the water after washing is close to 7, thereby removing the acid and alkali solution remaining on the surface of the sulfur paste and the soluble impurities generated by the reaction.

[0016] In one example, the washed sulfur paste filter cake is placed in a drying device for 2-4 hours to remove moisture from the sulfur paste and obtain dried sulfur paste.

[0017] In one example, during the sublimation of the dried sulfur paste, the sulfur is directly converted from a solid state to a gaseous state, and the residual impurities remain at the bottom of the sublimation device. The sublimated sulfur gas is condensed through a condenser with the temperature controlled at 40-60°C, so that the sulfur gas is re-condensed into solid sulfur, and a high-purity sulfur product is collected.

[0018] In one example, between the acid washing step and the alkaline washing step, there is a step of preliminary water washing of the sulfur paste filter cake after acid washing. During the preliminary water washing, the solid-liquid ratio of deionized water to the sulfur paste filter cake is 1:1-1:2, the stirring speed is 100-150r / min, and the stirring time is 3-5min. Solid-liquid separation is performed by filtration to reduce the residual sulfuric acid solution in the sulfur paste filter cake after acid washing and reduce the consumption of alkali solution in the alkaline washing step.

[0019] In one example, the process for purifying sulfur paste to prepare sulfur according to claim 1 is characterized in that: the process is applicable to various sulfur pastes produced by coal gas purification and petrochemical industries, and for sulfur pastes from different sources, by adjusting the solution concentration, solid-liquid ratio, reaction temperature, and reaction time parameters in each step, the purity of the prepared sulfur can reach above 99%.

[0020] The process for preparing sulfur by purifying sulfur paste proposed by the present invention can bring the following beneficial effects:

[0021] 1. The present invention can effectively remove most impurities such as organic impurities, heavy metal salts and metal sulfides in the sulfur paste through acid and alkali washing, and further purify it by sublimation. The purity of the prepared sulfur can reach more than 99%, meeting the application requirements of high-quality sulfur.

[0022] 2. Compared with the traditional sulfur melting method and chemical oxidation method, the present invention reduces the generation of waste gas and waste water. The waste gas generated during the acid and alkali washing process can be treated by an absorption device, and the waste water can meet the emission standards after neutralization, precipitation and other treatments; the sublimation method is carried out under vacuum conditions, with relatively low energy consumption, thereby reducing production costs.

[0023] 3. The present invention fully utilizes the by-product sulfur paste and converts it into a high-value sulfur product, thereby realizing the recycling of resources, having good economic and social benefits, and the process is simple and easy to operate. The operation steps of the process are relatively simple, the equipment requirements are not complicated, and it is easy to promote and apply in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0025] Figure 1 The present invention is a schematic flow chart of a process for purifying sulfur paste to prepare sulfur. DETAILED DESCRIPTION

[0026] In order to more clearly and completely illustrate the technical solution of the present invention, the present invention will be further described below with reference to the accompanying drawings.

[0027] Please refer to Figure 1 The present invention proposes a process for purifying sulfur paste to prepare sulfur. This process uses sulfur paste as raw material and realizes the conversion of sulfur paste into high-purity sulfur through five core steps: crushing pretreatment → acid and alkali washing to remove impurities → water washing and desalination → vacuum drying → sublimation purification. The following is a detailed description from the aspects of process parameters, equipment selection, operation points and quality control: jaw crusher is used for crushing, equipped with a vibration screening device to ensure that the discharge particle size is uniformly controlled at 1-5mm. A PE-250×400 jaw crusher can be used for a production line with a processing capacity of 500kg / h, with a crushing ratio of 4-6 times, which meets the requirements of industrial-grade crushing. Obvious impurities must be removed before sulfur paste is fed to avoid clogging the equipment. After crushing, it is screened through a vibrating screen with a mesh size of 5mm. The coarse particles that do not meet the standards are returned to the crusher for reprocessing; the volume of the stirring and washing equipment is 2-5m 3 The mechanical stirring container is equipped with an anchor-type stirring paddle, and the stirring speed can be adjusted to 100-200r / min by a frequency converter; the solid-liquid ratio is 1:1-1:2, tap water is added, and the stirring time is 15 minutes. The sulfur paste is initially dispersed by mechanical stirring, and physical impurities such as coal powder and mud attached to the surface are removed by hydraulic flushing. After washing, the wastewater is recycled in a sedimentation tank to recover solid impurities, and the clear liquid can be recycled for pretreatment.

[0028] Acid washing removes metal impurities. Sulfuric acid reacts with the metal compounds FeS, CaS, and MgS in the sulfur paste to produce soluble sulfates. The reaction vessel is an acid-resistant enamel reactor or a polypropylene stirring tank equipped with a thermometer, pH meter, and tail gas absorption device. Stirring and heating to 50°C, the reaction time is 45 minutes, and the stirring speed is 250r / min to ensure full contact between the solid and the liquid. The solid-liquid separation uses a plate and frame filter press. The filter cloth is made of polypropylene, the filtration accuracy is 5-10μm, and the filtration pressure is 0.3-0.5MPa. Acid washing filter cake and acid washing liquid are obtained. The acid washing liquid contains Fe 2+ , Ca 2+After neutralization and precipitation, the supernatant can be reused in the acid washing process, the precipitate metal hydroxide is recovered centrally, the organic impurities and residual acid are removed by alkali washing, the residual sulfuric acid is neutralized by sodium hydroxide, and saponification reaction occurs with organic impurities such as coal tar and phenols or soluble sodium salts are formed, the phenolic compounds react with NaOH to form sodium phenolate, which is dissolved in the water phase to achieve separation; the stirring tank of the same material as the acid washing is equipped with a heating jacket to control the temperature at 30-50 ° C, the NaOH concentration is 8%, the solid-liquid ratio is 1:3, the NaOH solution: acid washing filter cake is stirred and heated to 40 ° C, the reaction time is 30 min, and the stirring speed is 200r / min to fully dissolve the organic impurities.

[0029] The plate and frame filter press is used to filter again to obtain an alkaline washing filter cake with the sulfur content increased to 85%-90%. The alkaline washing liquid is acidified, and dilute sulfuric acid is added to adjust the pH to 6-7. After flotation to remove oil, it is combined with the acid washing liquid for treatment to achieve the synergistic removal of heavy metals and organic matter; to remove residual acid, alkali and salts, the equipment is equipped with a stirring washing tank with a volume matching the filter cake processing capacity, a solid-liquid weight ratio of 1:2, a stirring speed of 120r / min, a washing time of 8min, and repeated washing 2-3 times. The pH value of the filtrate after washing is close to 7, and the conductivity is <100μS / cm, ensure that there is no residual acid, alkali and soluble salt such as Na2SO4, use a horizontal spiral sedimentation centrifuge with a speed of 2000-3000r / min. After dehydration, the moisture content of the filter cake is reduced to 10%-15%, which is convenient for subsequent drying. A vacuum rake dryer or a double-cone rotary vacuum dryer is selected. The volume is determined according to the production capacity, the temperature is 90℃, the jacket is heated by thermal oil or steam, the vacuum degree is -0.07MPa, and it is equipped with a water ring vacuum pump or a rotary vane vacuum pump. The drying time is 3h. After drying, the moisture content of the sulfur paste is less than 1% and it is in the form of loose particles.

[0030] Before drying, the filter cake must be broken into chunks with a particle size of less than 20mm to prevent excessive accumulation that would affect heat transfer. During the drying process, a rake-type agitator or rotary motion is used to ensure uniform evaporation of water. Under low pressure of 0.01-0.05MPa and high temperature of 180-220°C, sulfur sublimates directly from solid to gas, with a sublimation point of approximately 182°C. Impurities such as carbon powder and metal oxides, due to their extremely high boiling points, remain at the bottom of the sublimation device. The sublimation furnace is constructed of stainless steel and equipped with electric heating elements, with a temperature control accuracy of ±2°C. The condensation system uses a shell-and-tube condenser, with circulating water as the cooling medium, and a temperature controlled at 40-60°C, condensing the sulfur vapor into a solid. The vacuum system uses a Roots vacuum pump unit, which can reduce the system pressure to below 0.01MPa. The sublimation temperature is 200°C, the pressure is 0.02MPa, the sublimation time is 4 hours, and the sulfur sublimation rate is >95%.

[0031] Adding a preliminary water wash between acid washing and alkaline washing, with a solid-liquid ratio of 1:1.5, a stirring speed of 150r / min, and a time of 5min, can reduce the residual sulfuric acid concentration in the acid washing filter cake by more than 50% and reduce the alkali solution consumption by about 20%-30%. After neutralization, precipitation, and filtration of the acid and alkaline wastewater, the clear liquid is reused in the pretreatment water washing link, with a reuse rate of more than 70%, reducing the consumption of new water. Waste gas treatment: The H2S gas generated by acid washing is absorbed by NaOH solution with an absorption rate of >99%. The generated Na2S solution can be recovered as a by-product.

[0032] The process has the advantages that the particle size of the sulfur paste after crushing treatment is 1 to 5 mm, which is convenient for full contact with acid and alkali solutions during subsequent treatment. The sulfur paste is placed in a stirring container to initially disperse the sulfur paste and remove impurities and dust attached to the surface of the sulfur paste. Sulfuric acid reacts with the metal in the sulfur paste to remove metal impurities from the sulfur paste. After the reaction is completed, solid-liquid separation is performed through a filtration device to obtain an acid-washed sulfur paste filter cake and acid-washing wastewater. The acid-washing wastewater is centrally treated to recover useful metal salt components therein, thereby realizing resource recycling. Sodium hydroxide solution reacts with residual acidic impurities and organic impurities in the sulfur paste to generate soluble substances to further remove impurities. After the reaction is completed, solid-liquid separation is performed through a filtration device to obtain an alkali-washed sulfur paste filter cake and alkali-washing wastewater. The alkali-washing wastewater is also centrally treated to avoid environmental pollution. The alkali-washed sulfur paste filter cake is washed with deionized water. The pH value of the washed water is close to 7, which can remove the acid-alkali solution remaining on the surface of the sulfur paste and the soluble impurities generated by the reaction. The washed sulfur paste filter cake is placed in a drying device. The drying time is 2 to 4 hours, and the moisture in the sulfur paste is removed to obtain a dried sulfur paste. During the sublimation process of the dried sulfur paste, the sulfur is directly converted from a solid state to a gaseous state, and the residual impurities remain at the bottom of the sublimation device. The sublimated sulfur gas is condensed through a condenser, and the temperature is controlled at 40 to 60°C, so that the sulfur gas is re-condensed into solid sulfur, and a high-purity sulfur product is collected. Between the acid washing step and the alkaline washing step, a preliminary water washing step is included for the sulfur paste filter cake after acid washing. During the preliminary water washing, deionized water is used. The solid-liquid ratio of the sulfur paste filter cake is 1:1 to 1:2, the stirring speed is 100 to 150 r / min, and the stirring time is 3 to 5 minutes. Solid-liquid separation is performed by filtration, which can reduce the sulfuric acid solution remaining in the sulfur paste filter cake after acid washing and reduce the consumption of alkali solution in the alkali washing step. The process is applicable to various sulfur pastes produced by coal gas purification and petrochemical industries. For sulfur pastes from different sources, the purity of the prepared sulfur can reach more than 99% by adjusting the solution concentration, solid-liquid ratio, reaction temperature, and reaction time parameters in each step.

[0033] Example 1

[0034] Pretreatment: Take 100 kg of sulfur paste and crush it into a particle size of 3 mm using a crusher.

[0035] Acid washing: The crushed sulfur paste was mixed with a 10% by mass sulfuric acid solution at a solid-liquid ratio of 1:3, placed in a stirred reactor, and stirred for 30 minutes at a stirring speed of 200 r / min and a temperature of 50°C. After the reaction, it was filtered through a plate and frame filter press and the solid was washed several times with deionized water until the pH value of the washing liquid was neutral.

[0036] Alkali washing: The solid after acid washing was mixed with 8% sodium hydroxide solution at a solid-liquid ratio of 1:3, and placed in a stirred reactor again. The mixture was stirred at a stirring speed of 200 r / min and a temperature of 40°C for 20 minutes. After the reaction was completed, the solid was separated from the liquid by filtration, and the solid was washed with deionized water until the pH value of the washing liquid was neutral.

[0037] Secondary drying: Place the solid after acid and alkali washing in a drying oven and perform secondary drying at 80°C for 2 hours to completely remove residual moisture and washing liquid.

[0038] Sublimation treatment: The solid after secondary drying was placed in a sublimation device and sublimated under the conditions of a vacuum degree of 0.02 MPa and a temperature of 200°C for 5 hours.

[0039] Cooling and collection: The sublimated sulfur gas is cooled by a cooling device to condense it into solid sulfur, which is then collected and packaged. After testing, the purity of the obtained sulfur is 99.5%.

[0040] Example 2

[0041] Pretreatment: Take 100kg of sulfur paste and crush it to a particle size of 4mm.

[0042] Acid washing: The crushed sulfur paste was mixed with a 12% by mass sulfuric acid solution at a solid-liquid ratio of 1:4, and stirred at a stirring speed of 250 r / min and a temperature of 55°C for 40 minutes. After the reaction, the solid was filtered and washed to a neutral pH value.

[0043] Alkaline washing: The solid after acid washing was mixed with 10% sodium hydroxide solution at a solid-liquid ratio of 1:3, and stirred at a stirring speed of 220 r / min and a temperature of 45°C for 30 minutes. After the reaction, the solid was filtered and washed to a neutral pH value.

[0044] Secondary drying: The solid after acid and alkali washing was secondary dried at 90°C for 3 hours.

[0045] Sublimation treatment: The secondary dried solid was sublimated under the conditions of a vacuum degree of 0.03 MPa and a temperature of 210° C. for 4 hours.

[0046] Cooling and collection: The sublimated sulfur is cooled and collected. After testing, the sulfur purity is 99.6%.

[0047] Example 3

[0048] Pretreatment: Take 100kg of sulfur paste and crush it to a particle size of 5mm.

[0049] Acid washing: The crushed sulfur paste was mixed with a 15% by mass sulfuric acid solution at a solid-liquid ratio of 1:5, and stirred at a stirring speed of 300 r / min and a temperature of 60°C for 60 minutes. After the reaction, the solid was filtered and washed until neutral.

[0050] Alkali washing: The solid after acid washing was mixed with 10% sodium hydroxide solution at a solid-liquid ratio of 1:4, and stirred at a stirring speed of 250 r / min and a temperature of 50°C for 40 minutes. After the reaction, the solid was filtered and washed until neutral.

[0051] Secondary drying: The secondary drying temperature was set at 100°C and the time was 3 hours.

[0052] Sublimation treatment: sublimation treatment was carried out at a vacuum degree of 0.04 MPa and a temperature of 220°C for 6 hours.

[0053] Cooling and collection: The sulfur is collected by cooling. After testing, its purity reaches 99.7%.

[0054] In this embodiment, the process includes raw material pretreatment, acid washing, alkaline washing, water washing, drying and sublimation, achieving efficient conversion from sulfur paste containing a large amount of impurities to high-purity sulfur. This process can not only effectively remove organic impurities, heavy metal salts and metal sulfides in the sulfur paste, but also further purify it through sublimation, ultimately achieving a sulfur purity of more than 99.5%, meeting the application requirements of high-quality sulfur.

[0055] First, in the raw material pretreatment stage, the sulfur paste is crushed to a particle size of 1-5mm. The selection of this particle size range is based on the requirement for sufficient contact between the sulfur paste and the acid and alkali solution during the subsequent processing process. The crushed sulfur paste is placed in a stirring container and water is added for stirring. The stirring speed is controlled at 100-200r / min and the stirring time is 10-20min. This process not only allows the sulfur paste to be initially dispersed, but also removes impurities and dust attached to its surface, laying the foundation for the subsequent washing steps.

[0056] In the acid washing stage, a sulfuric acid solution with a mass fraction of 5%-15% is added to the pretreated sulfur paste, and the solid-liquid ratio of the sulfuric acid solution to the sulfur paste is 1:2-1:5. The stirring reaction is carried out at a temperature of 40-60°C, a stirring speed of 200-300r / min, and a reaction time of 30-60min. The sulfuric acid reacts with the metal impurities such as iron, calcium, and magnesium metal compounds in the sulfur paste to generate soluble metal salts. After solid-liquid separation through a filtration device, a sulfur paste filter cake and acid washing wastewater after acid washing are obtained. The acid washing wastewater is centrally treated to recover the useful components of the metal salts therein, thereby realizing the recycling of resources. This process not only effectively removes metal impurities in the sulfur paste, but also reduces potential pollution to the environment.

[0057] Next is the alkaline washing stage, in which the sulfur paste filter cake after acid washing is transferred to another stirring container, and a sodium hydroxide solution with a mass fraction of 5%-10% is added. The solid-liquid ratio of the sodium hydroxide solution to the sulfur paste filter cake is 1:2-1:4. The stirring reaction is carried out at a temperature of 30-50°C, a stirring speed of 150-250r / min, and a reaction time of 20-40min. The sodium hydroxide solution reacts with the acidic impurities and organic impurities remaining in the sulfur paste to generate soluble substances, further removing impurities. After the reaction is completed, solid-liquid separation is also carried out through a filtration device to obtain the sulfur paste filter cake after alkaline washing and alkaline washing wastewater. The alkaline washing wastewater is also centrally treated to avoid pollution to the environment.

[0058] In the water washing stage, the sulfur paste filter cake after alkali washing is washed multiple times with deionized water. During washing, the solid-liquid ratio of deionized water to sulfur paste filter cake is 1:1-1:3, the stirring speed is 100-150r / min, and the stirring time is 5-10min. After solid-liquid separation by filtration, the pH value of the washed water is close to 7. This step effectively removes the acid and alkali solution remaining on the surface of the sulfur paste and the soluble impurities generated by the reaction, ensuring the smooth progress of the subsequent drying and sublimation steps; the drying stage is to put the washed sulfur paste filter cake into the drying equipment and carry out drying at a temperature of 80-100℃ and a vacuum degree of -0.08 to -0.06MPa. The drying process is carried out for 2-4 hours. This process effectively removes moisture from the sulfur paste and obtains dried sulfur paste, which is ready for the sublimation step. The sublimation stage is one of the key links in this process. The dried sulfur paste is placed in a sublimation device. The temperature of the sublimation device is controlled at 180-220℃ and the pressure is 0.01-0.05MPa. Under these conditions, sulfur is directly converted from solid to gas, while residual impurities remain at the bottom of the sublimation device. The sublimated sulfur gas is condensed through a condensing device with the temperature controlled at 40-60℃, so that the sulfur gas is re-condensed into solid sulfur, and finally a high-purity sulfur product is collected.

[0059] It can be seen from the above examples that the present process can stably produce high-purity sulfur products under different parameter conditions. The stability and reliability of this process give it broad application prospects in industrial production. At the same time, the equipment requirements of this process are relatively simple, the operating steps are clear and easy to understand, and it is easy to implement in production environments of different scales. Whether it is small-scale laboratory production or large-scale industrial production, this process can effectively meet the needs and demonstrate its strong adaptability and practicality.

[0060] Of course, the present invention may have many other implementations. Based on this implementation, other implementations obtained by ordinary technicians in this field without any creative work are all within the scope of protection of the present invention.

Claims

1. A process for purifying sulfur paste to prepare sulfur, characterized in that: The following steps are involved: Raw material pretreatment: crush the sulfur paste to a particle size of 1-5mm, put the crushed sulfur paste into a mixing container, add water and stir at a speed of 100-200r / min and a stirring time of 10-20min. Acid washing: add 5%-15% sulfuric acid solution by mass to the pretreated sulfur paste, with the solid-liquid ratio of sulfuric acid solution to sulfur paste being 1:2-1:5, and stir the reaction at a temperature of 40-60°C, a stirring speed of 200-300r / min, and a reaction time of 30-60min. The sulfuric acid reacts with the metal impurities such as iron, calcium, and magnesium metal compounds in the sulfur paste to generate soluble metal salts. Alkali washing: transfer the acid-washed sulfur paste filter cake to another stirring container, add 5%-10% sodium hydroxide solution by mass, the solid-liquid ratio of sodium hydroxide solution to sulfur paste filter cake is 1:2-1:4, stir at a temperature of 30-50°C, a stirring speed of 150-250r / min, and a reaction time of 20-40min. Washing: Use deionized water to wash the sulfur paste filter cake after alkali washing. The solid-liquid ratio of deionized water to sulfur paste filter cake is 1:1-1:

3. Stirring speed is 100-150r / min, stirring time is 5-10min, and solid-liquid separation is performed by filtration. Drying: The washed sulfur paste filter cake is placed in a drying device and dried at a temperature of 80-100°C and a vacuum degree of -0.08 to -0.06 MPa. Sublimation: The dried sulfur paste is placed in a sublimation device with a temperature of 180-220°C and a pressure of 0.01-0.05 MPa, where the sulfur sublimates.

2. The process for preparing sulfur by purifying sulfur paste according to claim 1, wherein: The sulfur paste is crushed to a particle size of 1-5 mm, which is convenient for subsequent treatment and full contact with acid and alkali solutions. The sulfur paste is placed in a stirring container to initially disperse the sulfur paste and remove impurities and dust attached to the surface of the sulfur paste.

3. The process for preparing sulfur by purifying sulfur paste according to claim 1, characterized in that: The sulfuric acid reacts with the metal in the sulfur paste to remove metal impurities from the sulfur paste. After the reaction is completed, the filtration device performs solid-liquid separation to obtain the sulfur paste filter cake after acid washing and acid washing wastewater. The acid washing wastewater is centrally treated to recover the useful components of the metal salt therein.

4. The process for preparing sulfur by purifying sulfur paste according to claim 1, characterized in that: The sodium hydroxide solution reacts with the acidic impurities and organic impurities remaining in the sulfur paste to generate soluble substances, further removing impurities. After the reaction is completed, the filtration device performs solid-liquid separation to obtain the sulfur paste filter cake after alkali washing and alkali washing wastewater.

5. The process for preparing sulfur by purifying sulfur paste according to claim 1, characterized in that: The deionized water is used to wash the sulfur paste filter cake after alkali washing. The pH value of the water after washing is close to 7, and the acid and alkali solution remaining on the surface of the sulfur paste and the soluble impurities generated by the reaction are removed.

6. The process for preparing sulfur by purifying sulfur paste according to claim 1, characterized in that: The sulfur paste filter cake is placed in a drying device for 2-4 hours to remove moisture from the sulfur paste to obtain dried sulfur paste.

7. The process for preparing sulfur by purifying sulfur paste according to claim 1, characterized in that: During the sublimation process of the sulfur paste, sulfur is directly converted from solid to gaseous, and residual impurities remain at the bottom of the sublimation device. The sublimated sulfur gas is condensed through a condensing device with a temperature controlled at 40-60°C, so that the sulfur gas is re-condensed into solid sulfur, and a high-purity sulfur product is collected.

8. The process for preparing sulfur by purifying sulfur paste according to claim 1, characterized in that: Between the acid washing step and the alkali washing step, a step of performing preliminary water washing on the sulfur paste filter cake after acid washing is included. During the preliminary water washing, the solid-liquid ratio of deionized water to the sulfur paste filter cake is 1:1-1:2, the stirring speed is 100-150 r / min, the stirring time is 3-5 minutes, and filtration is performed to separate the solid and liquid, thereby reducing the residual sulfuric acid solution in the sulfur paste filter cake after acid washing and reducing the consumption of alkali solution in the alkali washing step.

9. The process for preparing sulfur by purifying sulfur paste according to claim 1, characterized in that: The process is applicable to various sulfur pastes produced in the coal gas purification and petrochemical industries. For sulfur pastes from different sources, the purity of the prepared sulfur can reach above 99% by adjusting the solution concentration, solid-liquid ratio, reaction temperature, and reaction time parameters in each step.

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