Preparation method of lime-sulfur mixture

Abstract

The invention discloses a preparation method of a lime-sulfur mixture, and relates to the technical field of preparation of lime-sulfur mixers.The preparation method comprises the steps that S1, high-purity calcium hydroxide, sulfur powder and a compound additive composed of sea salt, loess and phyllite are prepared; s2, mixing the high-purity calcium hydroxide, sulfur powder and a compound additive in water, carrying out catalytic reaction, and stirring to react for 2.5-4 hours under the conditions that the temperature is 115-125 DEG C and the pressure is not greater than 1.5 atmospheric pressure; and S3, after the reaction is finished, cooling and filtering the reaction liquid to obtain the lime-sulfur mixture, the calcium-sulfur-mineral ternary reaction system is constructed by adopting the synergistic effect of high-purity calcium hydroxide and a composite additive with specific composition, and efficient and stable catalytic reaction is realized under mild temperature and pressure conditions, so that the generation of toxic gas is effectively inhibited, the generation of solid residues (sludge) is greatly reduced, and the environmental pollution is reduced. The problems of environmental pollution, potential safety hazards, incomplete reaction and the like in the traditional process are solved.

Description

Technical Field

[0001] This invention relates to the field of lime-sulfur mixture preparation technology, and in particular to a method for preparing lime-sulfur mixture. Background Technology

[0002] Lime-sulfur mixture is a long-established broad-spectrum bactericide and insecticide, whose main active ingredients are calcium polysulfide and calcium thiosulfate.

[0003] Traditional preparation methods typically involve reacting quicklime with sulfur powder under high temperature and pressure. Using quicklime as a raw material, the reaction process generates toxic gases such as hydrogen sulfide and sulfur dioxide. Furthermore, the system produces large amounts of calcium thiosulfate sludge and alkaline wastewater after the reaction, resulting in high treatment costs. Solid sulfur powder has a high melting point, and if it does not contact calcium hydroxide evenly, localized water absorption can cause a rapid increase in temperature and pressure, posing a risk of reactor explosion. Additionally, quicklime is prone to absorbing moisture and pulverizing during storage and feeding, affecting reaction efficiency, and the operating environment is harsh. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a method for preparing lime-sulfur mixture, which solves the problems of traditional preparation methods that typically involve reacting quicklime and sulfur powder under high temperature and pressure. Using quicklime as raw material, the reaction process generates toxic gases such as hydrogen sulfide and sulfur dioxide. Furthermore, the system produces a large amount of calcium thiosulfate sludge and alkaline wastewater after the reaction, resulting in high treatment costs. Additionally, solid sulfur powder has a high melting point, and if it does not contact calcium hydroxide evenly, localized water absorption can cause a rapid increase in temperature and pressure, posing a risk of reactor explosion. Moreover, quicklime is prone to absorbing moisture and pulverizing during storage and feeding, affecting reaction efficiency, and the operating environment is harsh.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for preparing a lime-sulfur mixture, comprising: S1. Prepare high-purity calcium hydroxide, sulfur powder, and a composite additive composed of sea salt, loess, and phyllite. S2. Mix the high-purity calcium hydroxide, sulfur powder and composite additive in water, and stir the mixture for 2.5 to 4 hours at a temperature of 115°C to 125°C and a pressure of no more than 1.5 atmospheres. S3. After the reaction is complete, the reaction solution is cooled and filtered to obtain the lime-sulfur mixture. In a preferred embodiment of the method for preparing the lime-sulfur mixture of the present invention, the mass ratio of sea salt, loess and phyllite in the composite additive is (3-5):(2-3):1.

[0007] In a preferred embodiment of the method for preparing lime-sulfur mixture according to the present invention, the amount of the composite additive added is 1% to 5% of the total mass of the reaction system.

[0008] In a preferred embodiment of the method for preparing lime-sulfur mixture according to the present invention, the amount of the composite additive added is 1% to 2% of the total mass of the reaction system.

[0009] In a preferred embodiment of the lime-sulfur mixture preparation method of the present invention, the purity of the high-purity calcium hydroxide is not less than 98%.

[0010] In a preferred embodiment of the lime-sulfur mixture preparation method of the present invention, the pressure condition of the catalytic reaction is atmospheric pressure.

[0011] In a preferred embodiment of the method for preparing lime-sulfur mixture according to the present invention, the temperature of the catalytic reaction is 115°C to 120°C.

[0012] In a preferred embodiment of the method for preparing lime-sulfur mixture according to the present invention, the catalytic reaction time is 2.5 to 3.5 hours.

[0013] In a preferred embodiment of the lime-sulfur mixture preparation method of the present invention, in step S3, the cooling temperature is reduced to below 80°C before filtration.

[0014] In a preferred embodiment of the lime-sulfur mixture preparation method of the present invention, the amount of solid residue obtained by filtration of the lime-sulfur mixture is less than 1.5% of the total mass of the feed.

[0015] The beneficial effects of this invention are as follows: by using high-purity calcium hydroxide and a composite additive with a specific composition to synergistically construct a calcium-sulfur-mineral ternary reaction system, a highly efficient and stable catalytic reaction is achieved under mild temperature and pressure conditions, effectively inhibiting the generation of toxic gases and significantly reducing the production of solid residues (sludge). This solves the problems of environmental pollution, safety hazards, and incomplete reaction that exist in traditional processes. At the same time, the preparation method is simple to operate and the conditions are controllable. The resulting lime-sulfur mixture product has good stability and high yield, realizing clean, safe, and efficient industrial production. Detailed Implementation

[0016] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below.

[0017] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0018] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0019] Example 1, the first embodiment of the present invention, provides a method for preparing a lime-sulfur mixture, comprising the following steps: S1. Prepare high-purity calcium hydroxide, sulfur powder, and a composite additive composed of sea salt, loess, and phyllite. Furthermore, in the composite additive, the mass ratio of sea salt, loess, and phyllite is (3-5):(2-3):1; the amount of composite additive added is 1% to 5% of the total mass of the reaction system; the amount of composite additive added is 1% to 2% of the total mass of the reaction system; and the purity of high-purity calcium hydroxide is not less than 98%. It should be noted that the high-purity calcium hydroxide used in this invention avoids the problems of moisture absorption, heat release and impurity introduction caused by the use of quicklime in traditional processes. The composite additives in a specific ratio are not inert fillers, but rather construct a reaction microenvironment with catalytic activity and interface promotion effect through the synergistic effect between sea salt, loess and phyllite, laying the foundation for subsequent low-temperature, low-pressure and high-efficiency reactions.

[0020] S2. Mix high-purity calcium hydroxide, sulfur powder and composite additives in water to carry out a catalytic reaction. Stir the reaction for 2.5 to 4 hours at a temperature of 115℃ to 125℃ and a pressure of no more than 1.5 atmospheres. Furthermore, the catalytic reaction is carried out under atmospheric pressure; the catalytic reaction temperature is 115°C to 120°C; and the catalytic reaction time is 2.5 to 3.5 hours. It should be noted that although no homogeneous catalyst in the traditional sense was added to the catalytic reaction, the composite additive effectively reduced the activation energy of calcium polysulfide formation by providing active sites, enhancing mass transfer efficiency and regulating the reaction pathway in the reaction system. This enabled a stable and controllable reaction at near-normal pressure and low temperature, effectively avoiding the safety risks and side reactions caused by high temperature and high pressure.

[0021] S3. After the reaction is complete, the reaction solution is cooled and filtered to obtain lime-sulfur mixture; Furthermore, the cooling temperature is reduced to below 80℃ before filtration; the amount of solid residue obtained from filtration of the lime-sulfur mixture is less than 1.5% of the total feed mass. It should be noted that cooling the reaction solution to below 80°C before filtration not only improves operational safety but also reduces the decomposition or oxidation of calcium polysulfide at high temperatures, ensuring product stability. The extremely low amount of solid residue indicates a complete reaction and very few byproducts, demonstrating the advantages of this method in terms of atom economy and clean production.

[0022] In summary, this invention utilizes the synergistic effect of high-purity calcium hydroxide and a composite additive of a specific composition to construct a calcium-sulfur-mineral ternary reaction system. Under mild temperature and pressure conditions, it achieves a highly efficient and stable catalytic reaction, effectively inhibiting the generation of toxic gases and significantly reducing the production of solid residues (sludge). This solves the problems of environmental pollution, safety hazards, and incomplete reaction associated with traditional processes. Furthermore, the preparation method is simple to operate, with controllable conditions, and the resulting lime-sulfur mixture product exhibits good stability and high yield, achieving clean, safe, and efficient industrial production.

[0023] Example 2, referring to Table 1, is the second embodiment of the present invention. This embodiment provides a specific implementation of a method for preparing a lime-sulfur mixture, including: Pretreatment: Mix and grind 3000kg sea salt, 2000kg loess and 1000kg phyllite into a composite additive.

[0024] Catalytic reaction: Liquid sulfur, calcium hydroxide slurry, and all composite additives were added to the reactor. The reaction was carried out under normal pressure and at 118-122℃ with stirring for 3.5 hours. The entire reaction process was stable, with no pressure buildup.

[0025] Post-processing: The reaction solution was cooled to 70°C and filtered to obtain approximately 200,000 kg of product, with a yield of 95.5%.

[0026] Comparison of effects: The product has an effective sulfur content of 23.0%.

[0027] Most importantly, the headspace gas detectors in the reactor showed that the concentrations of H2S and SO2 were below the instrument detection limits; the amount of solid residue (sludge) obtained from filtration was only 0.5% of the total feed mass.

[0028] Table 1: Comparison of Process Performance and Environmental Indicators between the Invention and Comparative Examples

[0029] As shown in Table 1, the method of the present invention (Example 2) is significantly superior to traditional methods and improved methods without additives in terms of environmental and safety indicators such as reaction pressure, reaction temperature, toxic gas emission, and sludge yield. In particular, the present invention achieves a breakthrough in atmospheric pressure reaction and near-zero sludge discharge (0.5%), particularly in terms of reaction pressure and sludge yield. Furthermore, the present invention achieves a higher product yield (95.5%) and effective sulfur content (23.0%) under milder conditions, demonstrating its absolute advantage not only in environmental safety but also in reaction efficiency and product quality.

[0030] In summary, this invention provides a clean, safe, and efficient method for preparing lime-sulfur mixture, successfully overcoming the inherent defects of traditional processes.

[0031] Example 3, the third embodiment of the present invention, provides an optimized process condition for the preparation of a lime-sulfur mixture, including: The steps are the same as in Example 1, but the amount of composite additive is adjusted to 2%, and the reaction temperature is controlled at 115°C.

[0032] Results: Even with a reaction time extended to 4 hours, the yield still reached 94%, the sludge production rate was <0.8%, and no toxic gases were detected.

[0033] This demonstrates that even at temperatures as low as 115°C, the process of this invention can still complete the reaction efficiently and cleanly, which is something that traditional processes cannot achieve.

[0034] Example 4, referring to Table 2, is the fourth embodiment of the present invention. This embodiment provides a method for preparing lime-sulfur mixture with high efficiency of reaction at low additive dosage, including: Pretreatment: Mix and grind 750kg sea salt, 500kg loess and 250kg phyllite into a composite additive (total amount is 1% of the reactants).

[0035] Catalytic reaction: 50,000 kg of sulfur powder, 40,000 kg of high-purity calcium hydroxide, and the above-mentioned composite additives were added to a reaction vessel, along with water. The mixture was stirred and reacted for 4 hours at atmospheric pressure and 120-125°C.

[0036] Post-processing: After the reaction is complete, the mixture is cooled and filtered to obtain the product.

[0037] Results: The yield was 94.2%, and the effective sulfur content was 22.8%. The reaction process was stable and under normal pressure. No toxic gases were detected, and the amount of sludge was 1.2% of the total feed mass.

[0038] Conclusion: Even with only 1% of the composite additive, the process of this invention can still achieve near-normal pressure reaction, no toxic gas emission, and extremely low sludge production, proving the robustness and economy of the process.

[0039] Example 5, referring to Table 2, is the fifth embodiment of the present invention. This embodiment provides a short-time and efficient reaction process for preparing a lime-sulfur mixture, including: Pretreatment: Mix and grind 2000kg sea salt, 1500kg loess and 500kg phyllite into a composite additive (total usage is 2%).

[0040] Catalytic reaction: 50,000 kg of sulfur powder, 40,000 kg of high-purity calcium hydroxide, and composite additives were added to the reactor, along with water. The reaction was carried out under slight positive pressure (approximately 1.2 atmospheres) and at 125-128°C with stirring for 2.5 hours.

[0041] Post-processing: After the reaction, the product was cooled and filtered to obtain the final product. Results: Yield 94.8%, available sulfur content 23.1%. The reaction process was controllable, no toxic gases were detected, and the sludge yield was 0.7%.

[0042] Conclusion: The process of this invention can significantly shorten the reaction time while ensuring high yield, high product quality and clean production, and has outstanding advantages of high efficiency and energy saving.

[0043] Table 2: Comparison of Process Parameters and Performance Indicators of Different Embodiments of the Invention

[0044] As can be seen from Table 2, the preparation process of the present invention exhibits excellent operational flexibility and robustness.

[0045] In terms of economics (Example 3): Even when the amount of the key component compound additive is reduced to a low level of 1%, the process can still operate stably, achieving a high yield of 94.2% under near-normal pressure conditions, and the sludge yield (1.2%) and the environmental advantages of non-toxic gases are still maintained, proving that the present invention has great potential in reducing costs.

[0046] In terms of efficiency (Example 4): By appropriately adjusting the process intensity, the present invention can be completed in a relatively short reaction time of 2.5 hours, with a yield of up to 94.8%, and excellent environmental protection indicators.

[0047] This demonstrates that the present invention can significantly improve production efficiency while ensuring clean production, thus meeting the pursuit of efficiency in industrial production.

[0048] In summary, this invention is not a fixed or rigid process, but a technical solution that can be flexibly adjusted according to different objectives such as cost control or production efficiency, and has a wide range of application flexibility. Its core advantages can be stably demonstrated under different operating conditions.

[0049] Comparative Example 1 (Traditional Method) Mix 1000 kg of quicklime with 1500 kg of sulfur powder, add 3800 kg of water, and react for 2 hours at 3 atmospheres and 120-130℃. The process generates a large amount of H2S and about 20% sludge, with a yield of 76%.

[0050] Comparative Example 2 (only raw materials were replaced, no additives were used) 40,000 kg of 20% high-purity calcium hydroxide slurry was mixed with 50,000 kg of molten liquid sulfur and reacted at 125°C and 2 atmospheres for 4 hours without the addition of composite additives.

[0051] Results: The yield increased to 90%, the sludge volume decreased to about 5%, but there was still a trace of H2S odor, and the reaction pressure indicated that the reaction was still quite vigorous.

[0052] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a lime-sulfur mixture, characterized in that: include: S1. Prepare high-purity calcium hydroxide, sulfur powder, and a composite additive composed of sea salt, loess, and phyllite. S2. The high-purity calcium hydroxide, sulfur powder and composite additives are mixed in water to carry out a catalytic reaction. The reaction is carried out by stirring for 2.5 to 4 hours at a temperature of 115°C to 125°C and a pressure of no more than 1.5 atmospheres. S3. After the reaction is complete, the reaction solution is cooled and filtered to obtain the lime-sulfur mixture.

2. The method for preparing lime-sulfur mixture as described in claim 1, characterized in that: In the composite additive, the mass ratio of sea salt, loess and phyllite is (3-5):(2-3):

1.

3. The method for preparing lime-sulfur mixture as described in claim 2, characterized in that: The amount of the composite additive added is 1% to 5% of the total mass of the reaction system.

4. The method for preparing lime-sulfur mixture as described in claim 3, characterized in that: The amount of the composite additive added is 1% to 2% of the total mass of the reaction system.

5. The method for preparing lime-sulfur mixture as described in claim 1, characterized in that: The purity of the high-purity calcium hydroxide is not less than 98%.

6. The method for preparing lime-sulfur mixture as described in claim 1, characterized in that: The catalytic reaction is performed under normal pressure.

7. The method for preparing lime-sulfur mixture as described in claim 1, characterized in that: The temperature of the catalytic reaction is 115°C to 120°C.

8. The method for preparing lime-sulfur mixture as described in claim 1, characterized in that: The catalytic reaction takes 2.5 to 3.5 hours.

9. The method for preparing lime-sulfur mixture as described in claim 1, characterized in that: In step S3, the cooling temperature is reduced to below 80°C before filtration.

10. The method for preparing lime-sulfur mixture as described in claim 1, characterized in that: The amount of solid residue obtained from filtration of the lime-sulfur mixture is less than 1.5% of the total mass of the feed.

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