Preparation method of lime sulfur crystal
Through catalyst reaction and gradient crystallization technology, the problems of low crystal yield and low effective components of lithosulfide mixture are solved, and efficient production of high-purity lithosulfide mixture crystallization is achieved.
Patent Information
- Application Number
- CN202510576863.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-06
- Publication Date
- 2025-07-04
AI Technical Summary
There are problems in the production of existing lithosulfur mixtures with low yield and low active ingredients, and long production cycle and high energy consumption.
The catalyst is used to react under high temperature and high pressure and filter, and then crystallize under different temperature gradients, including the first cooling to 35~40℃ and the first insulation of 18~20 hours, and then cooling to 10~20℃ and insulated for 3 hours. Combined with the catalyst composition and ball milling process optimization, the crystallization rate and time are controlled.
It significantly improves the purity and yield of lithosulfur mixture crystallization, shortens the production cycle, and reduces energy consumption.
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of lime sulfur, and specifically, to a preparation method of lime sulfur crystal. Background Art
[0002] Lime sulfur crystal is a solid dosage form synthesized by sulfur, lime and water under the action of a metal catalyst through high temperature and high pressure processing. It is convenient to use and transport, and its performance is the same as that of lime sulfur.
[0003] The active ingredient of lime sulfur crystal is calcium polysulfide, which has strong ability to penetrate and erode the cell walls of germs and the body walls of pests, and can directly kill germs and pests. After its liquid medicine is sprayed on the plant surface, it undergoes a chemical change under the action of oxygen, carbon dioxide and water, forming fine sulfur precipitates and releasing a small amount of hydrogen sulfide, which has the functions of sterilization, insecticidal and protecting plants. And while preventing diseases, it is safe for plants, has no residue, does not pollute the environment, and pests are not easy to develop resistance.
[0004] At present, although there are studies on the production process of crystalline lime sulfur, due to the traditional lime sulfur crystal process being prone to impurities in the lime sulfur crystal, the yield and active ingredient of the lime sulfur crystal are relatively low. In addition, the production process of crystalline lime sulfur also has problems such as long production cycle and high energy consumption. Summary of the Invention
[0005] The present invention provides a preparation method of lime sulfur crystal, which solves the problems of low yield and low active ingredient of lime sulfur crystal in the related art.
[0006] The technical solution of the present invention is as follows: The present invention provides a preparation method of lime sulfur crystal, including the following steps: S1. React water, quicklime and sulfur under the catalysis of a catalyst, and filter to obtain liquid lime sulfur; S2. First cool the liquid lime sulfur to 35 - 40 °C for the first crystallization, and then cool it to 10 - 20 °C for the second crystallization to obtain lime sulfur crystal.
[0007] In the present invention, filtering after the reaction in step S1 can remove unreacted impurities and avoid mixing into the crystals during the crystallization process, thereby improving the purity of the final product, lime sulfur crystal.
[0008] As a further technical solution, the mass ratio of the quicklime, sulfur and water is 1:2:6.
[0009] As a further technical solution, the addition amount of the catalyst is 0.4% - 0.5% of the mass of the sulfur.
[0010] As a further technical solution, in step S1, the temperature of the reaction is 120~130°C, and the reaction time is 20~30 min.
[0011] As a further technical solution, the pressure of the reaction is 0.3~0.4 MPa.
[0012] As a further technical solution, in step S1, the catalyst is composed of magnesium oxide, zinc oxide, and sodium dithiocarbamate.
[0013] The composition of magnesium oxide, zinc oxide, and sodium dithiocarbamate in the catalyst can synergistically improve the reaction effect, inhibit the generation of impurities, and improve the utilization rate of sulfur. However, there is a risk of agglomeration of magnesium oxide and zinc oxide during use, which will lead to a reduction in the active sites of magnesium oxide and zinc oxide after agglomeration, affecting the use effect of the catalyst.
[0014] As a further technical solution, the mass ratio of magnesium oxide, zinc oxide, and sodium dithiocarbamate is 1:1:2~3.
[0015] As a further technical solution, the preparation method of the catalyst includes the following steps: adding magnesium oxide and zinc oxide to a solvent and ball-milling at a rotation speed of 200~300 rmp for 30~40 min, adding sodium dithiocarbamate, and then continuing to ball-mill for 20~30 min, and drying to obtain the catalyst.
[0016] In order to improve the catalytic performance of magnesium oxide, zinc oxide, and sodium dithiocarbamate, during the preparation process of the catalyst, first ball-mill magnesium oxide and zinc oxide in the catalyst to improve the synergistic catalytic effect of the two, and then add sodium dithiocarbamate and continue to ball-mill, which can improve the combination of sodium dithiocarbamate with magnesium oxide and zinc oxide, further improve the catalytic effect of sodium dithiocarbamate and the overall catalytic effect of the three; and the rotation speed during the ball-milling process is limited to 200~300 rmp. The applicant found in the experiment that when the rotation speed of the ball-milling is lower or higher than this speed, the role of the ball-milling cannot be well exerted, which will affect the final product, resulting in a decrease in the crystallization yield and effective content of the lime sulfur mixture.
[0017] As a further technical solution, the solvent is absolute ethanol.
[0018] As a further technical solution, the ball-milling is carried out in an intermittent ball-milling manner, and the machine stops to cool to room temperature every 10 min of ball-milling.
[0019] In the present invention, the intermittent ball-milling method and the limitation of the rotation speed for ball-milling can better control the temperature during the ball-milling process, will not cause the decomposition of sodium dithiocarbamate and the excessive volatilization of the solvent, and can better improve the catalytic performance of the catalyst after ball-milling.
[0020] As a further technical solution, the ball milling medium is zirconia balls.
[0021] As a further technical solution, the average diameter of the zirconia balls is 0.8 mm.
[0022] As a further technical solution, the drying is vacuum drying. As a further technical solution, the rate of the first temperature drop is 30 - 40 °C / h, and the rate of the second temperature drop is 60 °C / h.
[0023] When the crystallization rate is higher than the limit defined in the present invention, rapid crystallization will quickly form a large number of crystal nuclei, wrapping impurities inside the crystals, resulting in a decrease in the crystallization purity of the lime sulfur mixture. When the crystallization rate is lower than the limit defined in the present invention, it will not only increase the production cycle, reduce production efficiency, and increase production costs, but also cause the crystals to grow too large, easily form a coating on the mother liquor, resulting in mother liquor loss, thus affecting the yield and effective substance content of the lime sulfur mixture crystallization.
[0024] As a further technical solution, the time for the first crystallization is 18 - 20 h, and the time for the second crystallization is 3 - 5 h.
[0025] The present invention also provides a lime sulfur mixture crystallization, which is prepared by the preparation method of the lime sulfur mixture crystallization described above.
[0026] The working principle and beneficial effects of the present invention are as follows: In the preparation process of the present invention, a catalyst is also added. The addition of the catalyst can accelerate the reaction of sulfur and quicklime, promote the formation of calcium polysulfide, reduce the residue of unreacted sulfur or lime, reduce the impurities in the liquid lime sulfur agent, and provide a purer liquid lime sulfur agent for subsequent crystallization. During the crystallization process, primary crystallization is first carried out at a relatively high temperature of 35 - 40 °C, and the crystal growth rate is moderate, which can reduce the formation of fine crystal nuclei. Then, the temperature is lowered to 10 - 20 °C for secondary crystallization, which can enable the remaining solute to precipitate fully, significantly improve the purity and yield of the lime sulfur mixture crystallization, and shorten the production cycle. Specific Embodiments
[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of the present invention.
[0028] In the following examples and comparative examples: Quicklime: CaO content ≥ 95%; Sulfur: S content ≥ 99.5%; Magnesium oxide: MgO ≥ 95%, average particle size; 200 mesh; Zinc oxide: ZnO ≥ 99%, average particle size; 200 mesh; During ball milling, the ball milling medium is zirconia balls with an average diameter of 0.8 mm; intermittent ball milling is adopted, and after each 10 min of ball milling, it is stopped and cooled to room temperature.
[0029] Example 1 A preparation method of lime sulfur mixture crystals, comprising the following steps: S1. After heating 200 g of water to 50 °C, adding 35 g of quicklime and mixing evenly, then adding 65 g of sulfur and 0.26 g of catalyst, reacting at 120 °C for 30 min under 0.3 MPa, and filtering to obtain liquid lime sulfur mixture; the catalyst is composed of magnesium oxide, zinc oxide, and sodium dithiocarbamate with a mass ratio of 1:1:2; S2. First, cool the liquid lime sulfur mixture at a cooling rate of 30 °C / h to 40 °C and keep it warm for 20 h, then cool it at a cooling rate of 60 °C / h to 10 °C and keep it warm for 3 h to obtain 76.4 g of lime sulfur mixture crystals; polysulfide calcium (calculated as CaS4) is 45.4%.
[0030] Example 2 A preparation method of lime sulfur mixture crystals, comprising the following steps: S1. After heating 200 g of water to 50 °C, adding 35 g of quicklime and mixing evenly, then adding 65 g of sulfur and 0.33 g of catalyst, reacting at 130 °C for 20 min under 0.4 MPa, and filtering to obtain liquid lime sulfur mixture; the catalyst is composed of magnesium oxide, zinc oxide, and sodium dithiocarbamate with a mass ratio of 1:1:3; S2. First, cool the liquid lime sulfur mixture at a cooling rate of 50 °C / h to 35 °C and keep it warm for 18 h, then cool it at a cooling rate of 120 °C / h to 20 °C and keep it warm for 3 h to obtain 79.1 g of lime sulfur mixture crystals, and polysulfide calcium (calculated as CaS4) is 45.7%.
[0031] Example 3 Compared with Example 1, the difference in this example is only in step S2, and step S3 in this example is as follows: S2. First, cool the liquid lime sulfur mixture at a cooling rate of 50 °C / h to 40 °C and keep it warm for 20 h, then cool it at a cooling rate of 60 °C / h to 10 °C and keep it warm for 3 h to obtain 84.4 g of lime sulfur mixture crystals, and polysulfide calcium (calculated as CaS4) is 46.2%.
[0032] Example 4 Compared with Embodiment 1, the difference of this embodiment is only in step S2. Step S2 of this embodiment is: S2. The liquid lime sulfur mixture was first cooled to 40°C at a cooling rate of 40°C / h and kept warm for 20 hours, and then cooled to 10°C at a cooling rate of 60°C / h and kept warm for 3 hours to obtain 91.1 g of lime sulfur mixture crystals with a calcium polysulfide (calculated as CaS4) content of 46.8%.
[0033] Example 5 Compared with Embodiment 4, the difference of this embodiment is only in step S2. Step S2 of this embodiment is: S2. The liquid lime sulfur mixture was first cooled to 40°C at a cooling rate of 40°C / h and kept warm for 20 hours, and then cooled to 10°C at a cooling rate of 120°C / h and kept warm for 3 hours to obtain 95.14g of lime sulfur mixture crystals with a calcium polysulfide (calculated as CaS4) content of 47.0%.
[0034] Example 6 Compared with Embodiment 4, the difference of this embodiment is only in step S2. Step S2 of this embodiment is: S2. The liquid lime sulfur mixture was first cooled to 40°C at a cooling rate of 40°C / h and kept warm for 20 hours, and then cooled to 10°C at a cooling rate of 90°C / h and kept warm for 3 hours to obtain 100.5g of lime sulfur mixture crystals with a calcium polysulfide (calculated as CaS4) content of 47.4%.
[0035] Example 7 Compared with Embodiment 6, the difference of this embodiment is only in step S2. Step S2 of this embodiment is: S2. The liquid lime sulfur mixture was first cooled to 40°C at a cooling rate of 40°C / h and kept warm for 20 hours, and then cooled to 10°C at a cooling rate of 90°C / h and kept warm for 5 hours to obtain 104.52g of lime sulfur mixture crystals with a calcium polysulfide (calculated as CaS4) content of 47.6%.
[0036] Example 8 Compared with Embodiment 6, the difference of this embodiment is only in step S2. Step S2 of this embodiment is: S2. The liquid lime sulfur mixture was first cooled to 40°C at a cooling rate of 40°C / h and kept warm for 20 hours, and then cooled to 10°C at a cooling rate of 90°C / h and kept warm for 4 hours to obtain 111.22 g of lime sulfur mixture crystals with a calcium polysulfide (calculated as CaS4) content of 48%.
[0037] Example 9 Compared with Example 8, the only difference in this example lies in the catalyst, which is prepared by the following method: Add magnesium oxide and zinc oxide to absolute ethanol and ball-mill at a rotation speed of 200 rmp for 40 min. After adding sodium dithiocarbamate, continue to ball-mill at a rotation speed of 200 rmp for 30 min, and then perform vacuum drying to obtain the catalyst; S2 obtains 115.2 g of lime sulfur crystal, and the polysulfide calcium (calculated as CaS4) is 48.4%.
[0038] Example 10 Compared with Example 9, the only difference in this example is that the catalyst in this example is prepared by the following method: Add magnesium oxide and zinc oxide to absolute ethanol and ball-mill at a rotation speed of 300 rmp for 30 min. After adding sodium dithiocarbamate, continue to ball-mill at a rotation speed of 300 rmp for 20 min, and then perform vacuum drying to obtain the catalyst; S2 obtains 121.94 g of lime sulfur crystal, and the polysulfide calcium (calculated as CaS4) is 48.6%.
[0039] Example 11 Compared with Example 9, the only difference in this example is that the catalyst in this example is prepared by the following method: Add magnesium oxide and zinc oxide to absolute ethanol and ball-mill at a rotation speed of 250 rmp for 40 min. After adding sodium dithiocarbamate, continue to ball-mill at a rotation speed of 250 rmp for 30 min, and then perform vacuum drying to obtain the catalyst; S2 obtains 125.96 g of lime sulfur crystal, and the polysulfide calcium (calculated as CaS4) is 48.9%.
[0040] Comparative Example 1 A preparation method of lime sulfur crystal, comprising the following steps: S1. Heat 100 g of water to 50 °C, add 70 g of quicklime and mix evenly, then add 90 g of sulfur and 0.36 g of catalyst, react at 120 °C for 30 min under 0.3 MPa, and then filter to obtain liquid lime sulfur; the catalyst is composed of magnesium oxide, zinc oxide, and sodium dithiocarbamate with a mass ratio of 1:1:2; S2. Cool the liquid lime sulfur at a cooling rate of 60 °C / h to 40 °C and keep it warm for 21 h to obtain 42.9 g of lime sulfur crystal, and the polysulfide calcium (calculated as CaS4) is 44.9%.
[0041] Comparative Example 2 Compared with Comparative Example 1, the only difference in this comparative example lies in step S2, and step S2 in this comparative example is: S2. Cool the liquid lime sulfur at a cooling rate of 40 °C / h to 40 °C and keep it warm for 24 h to obtain 50.9 g of lime sulfur crystal, and the polysulfide calcium (calculated as CaS4) is 45.2%.
[0042] From the data in Examples 1-11 and Comparative Examples 1-2, it can be seen that the content of calcium polysulfide in Examples 1-11 is higher than that in Comparative Examples 1-2, and the content of calcium polysulfide is > 45%, and the highest content of calcium polysulfide can reach 48.9%.
[0043] Moreover, it is detected that the content of water-insoluble substances in the crystal of lime sulfur in Examples 1-11 is < 1.0%, the pH is 11.4-11.8, and the water content is < 4.0%.
[0044] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A preparation method of lime sulfur crystal, characterized in that, It includes the following preparation method: S1. React water, quicklime and sulfur under the catalysis of a catalyst, and then filter to obtain liquid lime sulfur mixture; S2. First cool the liquid lime sulfur mixture to 35 - 40 °C for the first crystallization, and then cool it to 10 - 20 °C for the second crystallization to obtain lime sulfur mixture crystals.
2. The preparation method of a lime sulfur crystal according to claim 1, characterized in that, The addition amount of the catalyst is 0.4% - 0.5% of the mass of the sulfur.
3. The preparation method of lime sulfur crystal according to claim 1, characterized in that, In step S1, the temperature of the reaction is 120 - 130 °C, and the reaction time is 20 - 30 min.
4. A preparation method of lime sulfur crystal according to claim 1, characterized in that, In step S1, the pressure of the reaction is 0.3 - 0.4 MPa.
5. The preparation method of a lime sulfur crystal according to claim 1, characterized in that, In step S1, the catalyst is composed of magnesium oxide, zinc oxide and sodium diethyldithiocarbamate.
6. The preparation method of lime sulfur crystal according to claim 5, characterized in that, The mass ratio of the magnesium oxide, zinc oxide and sodium diethyldithiocarbamate is 1:1:2 - 3.
7. A preparation method of lime sulfur crystal according to claim 5, characterized in that, The preparation method of the catalyst includes the following steps: Add magnesium oxide and zinc oxide into a solvent and ball mill at a rotation speed of 200 - 300 rmp for 30 - 40 min. After adding sodium diethyldithiocarbamate, continue to ball mill at a rotation speed of 200 - 300 rmp for 20 - 30 min, and then dry to obtain the catalyst.
8. A preparation method of lime sulfur crystal according to claim 7, characterized in that, The rate of the first cooling is 30 - 50 °C / h, and the rate of the second cooling is 60 - 120 °C / h.
9. A preparation method of lime sulfur crystal according to claim 7, characterized in that, The time of the first crystallization is 18 - 20 h, and the time of the second crystallization is 3 - 5 h.
10. A lime sulfur crystal, characterized in that, The lime sulfur mixture crystals are prepared by the preparation method of the lime sulfur mixture crystals according to any one of claims 1 - 9.