Potassium magnesium sulphate fertilizer and preparation process thereof

Abstract

The invention relates to the technical field of potash magnesium sulphate fertilizer production, and discloses a potash magnesium sulphate fertilizer and a preparation process thereof, and the preparation process comprises the following steps: under a stirring condition, placing potassium mixed salt ore in decomposition mother liquor and fresh water for a conversion reaction; after conversion is completed, a collecting agent is added for flotation, and flotation foam is obtained; carrying out belt machine filtration on the flotation froth, spraying potassium sulfate mother liquor in the belt machine filtration process to obtain a wet-based potash magnesium sulphate fertilizer, and drying and packaging to obtain the potash magnesium sulphate fertilizer. The flotation froth and the potassium sulfate mother liquor both comprise potassium ions, sodium ions and chloride ions, the content of the potassium ions in the potassium sulfate mother liquor is lower than that of the flotation froth, and the content of the chloride ions and the sodium ions is higher than that of the flotation froth. By selecting the specific decomposition mother liquor, the recovery rate of potassium in the potassium mixed salt ore is increased, then by spraying the potassium sulfate mother liquor, the content of potassium ions in the potash magnesium sulphate fertilizer is increased, the content of chloride ions and sodium ions is reduced, and meanwhile, the yield of the potash magnesium sulphate fertilizer is increased.

Description

[0001] This invention is a divisional application based on the application filed on September 12, 2023, with application number 202311173515.7 and invention title "A preparation process of potassium magnesium sulfate fertilizer". Technical Field

[0002] This invention relates to the field of potassium magnesium sulfate fertilizer production technology, specifically to a potassium magnesium sulfate fertilizer and its preparation process. Background Technology

[0003] Potassium magnesium sulfate fertilizer, chemically known as soft potassium magnesium vanadium, has the chemical formula MgSO4K2SO46H2O. It is a multi-element potassium fertilizer containing potassium, sulfur, magnesium, calcium, silicon, boron, iron, zinc, and other elements. It is weakly alkaline, making it particularly suitable for acidic soils. It is generally used as a base fertilizer but can also be used as a top dressing. It is suitable for crops such as rice, corn, sugarcane, peanuts, tobacco, potatoes, sugar beets, fruits, vegetables, and alfalfa. Compared to potassium chloride and potassium sulfate, which are single-element potassium fertilizers with the same potassium content (K2O), agricultural potassium magnesium sulfate is more effective than potassium chloride and slightly more effective than potassium sulfate.

[0004] Currently, potassium magnesium sulfate fertilizer is generally produced using the conversion flotation method from potassium mixed salt ore in salt fields. The process mainly adopts a conversion-flotation-washing-drying process, which involves adding fresh water, decomposing the mother liquor, and heating the potassium mixed salt ore to 25°C to convert KCl and MgSO4·7H2O in the raw ore into soft potassium magnesium vanadium. Sodium hexadecyl sulfonate is added as a collector for flotation. The resulting crystalline potassium foam is filtered by a belt filter and washed with fresh water to obtain potassium magnesium sulfate fertilizer. This process is widely used in salt lake potash fertilizer production plants. However, the potassium recovery rate in this process is low, and the potassium ion content in the product is low, while the chloride and sodium ion content is high, which reduces the product quality. Summary of the Invention

[0005] The purpose of this invention is to provide a potassium magnesium sulfate fertilizer and its preparation process. The potassium magnesium sulfate fertilizer preparation process significantly improves the potassium recovery rate in potassium mixed salt ore by selecting specific decomposition mother liquor and spraying potassium sulfate mother liquor, while increasing the potassium ion content and reducing the chloride and sodium ion content in the potassium magnesium sulfate fertilizer, thereby improving the quality of the potassium magnesium sulfate fertilizer.

[0006] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: On the one hand, the present invention provides a preparation process for potassium magnesium sulfate fertilizer, comprising the following steps: (a) Under stirring conditions, potassium mixed salt ore is placed in decomposition mother liquor and fresh water for conversion reaction; (b) After the conversion is complete, a collector is added for flotation to obtain flotation foam; (c) The flotation foam is filtered by a belt filter and potassium sulfate mother liquor is sprayed during the belt filter process to obtain wet-based potassium magnesium sulfate fertilizer, which is then dried and packaged to obtain potassium magnesium sulfate fertilizer. Both the flotation foam and the potassium sulfate mother liquor contain potassium ions, sodium ions, and chloride ions. The potassium ion content in the potassium sulfate mother liquor is lower than that in the flotation foam, while the chloride and sodium ion content in the potassium sulfate mother liquor is higher than that in the flotation foam.

[0007] Preferably, the ion mass concentrations in the decomposition mother liquor are as follows: potassium ions 2%–2.5%, sodium ions 2.1%–2.6%, magnesium ions 5.2%–5.6%, sulfate ions 7.5%–8.5%, and chloride ions 15%–16%.

[0008] Preferably, the mass ratio of the potassium mixed salt ore, the decomposition mother liquor, and the fresh water is 1:(0.3-0.7):(0.1-0.3).

[0009] Preferably, the reaction temperature of the conversion reaction is 24-26°C and the reaction time is 1.5-2.0 h.

[0010] Preferably, the collector is sodium hexadecyl sulfonate.

[0011] Preferably, the amount of collector added is 0.01% to 0.02% of the mass of potassium mixed salt ore.

[0012] Preferably, the ion concentrations in the potassium sulfate mother liquor are as follows: potassium ions 7%–8%, sodium ions 1.2%–1.8%, magnesium ions 2%–2.6%, sulfate ions 3%–3.6%, and chloride ions 12%–13%.

[0013] Preferably, the spray volume of the potassium sulfate mother liquor is 5% to 8% of the mass of the flotation foam.

[0014] Preferably, step (b) further includes refining the flotation foam.

[0015] On the other hand, the present invention provides a potassium magnesium sulfate fertilizer prepared by any of the above-described processes.

[0016] Compared with the prior art, the beneficial effects of the present invention include at least the following: The potassium magnesium sulfate fertilizer preparation process of this invention can improve the potassium recovery rate in potassium mixed salt ore by selecting specific decomposition mother liquor. Then, by spraying the potassium sulfate mother liquor, the yield of potassium magnesium sulfate fertilizer is improved, while the potassium ion content in the potassium magnesium sulfate fertilizer is increased and the chloride ion and sodium ion content is reduced, thereby significantly improving the quality of potassium magnesium sulfate fertilizer. Detailed Implementation

[0017] The embodiments of the technical solution of the present invention will be described in detail below with reference to the examples. The following embodiments are only used to illustrate the technical solution of the present invention more clearly, and are therefore only examples, and should not be used to limit the scope of protection of the present invention.

[0018] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0019] In the early stages of the development of this invention, since the potassium ion content in the potassium sulfate mother liquor was lower than that in flotation foam, while the chloride and sodium ion content was higher, the inventors and their colleagues initially did not agree that using the potassium sulfate mother liquor, which has a higher chloride ion content and a lower potassium ion content than flotation foam, for spraying could achieve the purpose of increasing the potassium ion content. However, through experimental verification, this method not only increased the potassium ion content, but also reduced the chloride and sodium ion content, and the actual effect was very good.

[0020] This invention provides a process for preparing potassium magnesium sulfate fertilizer, which includes the following steps: (a) Under stirring conditions, potassium mixed salt ore is placed in decomposition mother liquor and fresh water for conversion; (b) After the conversion is complete, a collector is added for flotation to obtain flotation foam; (c) The flotation foam is filtered by a belt filter and potassium sulfate mother liquor is sprayed during the belt filter process to obtain wet-based potassium magnesium sulfate fertilizer, which is then dried and packaged to obtain potassium magnesium sulfate fertilizer.

[0021] In the potassium magnesium sulfate fertilizer preparation process of this invention, by selecting a specific decomposition mother liquor, the recovery rate of potassium in potassium mixed salt ore can be improved. Then, by spraying the potassium sulfate mother liquor, the yield of potassium magnesium sulfate fertilizer is improved, while the potassium ion content in the potassium magnesium sulfate fertilizer is increased and the chloride ion and sodium ion content is reduced, thereby significantly improving the quality of the prepared potassium magnesium sulfate fertilizer.

[0022] In one embodiment, the ion mass concentrations in the decomposition mother liquor are as follows: potassium ions 2%–2.5%, sodium ions 2.1%–2.6%, magnesium ions 5.2%–5.6%, sulfate ions 7.5%–8.5%, and chloride ions 15%–16%.

[0023] In one embodiment, the mass ratio of potassium mixed salt ore, decomposition mother liquor, and fresh water is 1:(0.3-0.7):(0.1-0.3).

[0024] To improve the conversion efficiency of potassium mixed salt ore, in one embodiment, the conversion reaction temperature is 24–26°C and the time is 1.5–2.0 h.

[0025] The present invention does not strictly limit the specific type of collector. Those skilled in the art can select conventional collectors in the art. Preferably, in one embodiment, the collector can be sodium hexadecyl sulfonate.

[0026] In order to improve the flotation effect and increase the recovery rate of potassium ions in potassium mixed salt ore, in one embodiment, the amount of collector added can be 0.01% to 0.02% of the mass of potassium mixed salt ore.

[0027] In this invention, spraying potassium sulfate mother liquor can improve the content of various components in the preparation of potassium magnesium sulfate fertilizer. Specifically, it can increase the potassium ion content and decrease the chloride and sodium ion content. In one embodiment, the ion concentrations in the potassium sulfate mother liquor are as follows: potassium ions 7%–8%, sodium ions 1.2%–1.8%, magnesium ions 2%–2.6%, sulfate ions 3%–3.6%, and chloride ions 12%–13%.

[0028] Furthermore, the spray volume of potassium sulfate mother liquor is 5% to 8% of the mass of the flotation foam.

[0029] In other embodiments, step (b) further includes refining the flotation foam.

[0030] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0031] Example 1 This embodiment describes a preparation process for potassium magnesium sulfate fertilizer, which includes the following steps: (a) Under stirring conditions, potassium mixed salt ore was placed in decomposition mother liquor and fresh water for conversion. The ion mass concentrations in the decomposition mother liquor were as follows: potassium ions 2.2%, sodium ions 2.36%, magnesium ions 5.42%, sulfate ions 7.82%, and chloride ions 15.66%. The mass ratio of potassium mixed salt ore, decomposition mother liquor, and fresh water was 1:0.5:0.2. The conversion reaction temperature was 24°C, and the time was 2.0 h. (b) After the conversion is complete, a collector is added for flotation and cleaning to obtain flotation froth, wherein the collector is sodium hexadecyl sulfonate; the amount of collector added is 0.01% of the mass of potassium mixed salt ore; (c) The flotation foam is filtered by a belt filter and potassium sulfate mother liquor is sprayed during the belt filter process to obtain wet-based potassium magnesium sulfate fertilizer, which is then dried and packaged to obtain potassium magnesium sulfate fertilizer; wherein, the ion concentrations in the potassium sulfate mother liquor are as follows: potassium ions 7%, sodium ions 1.8%, magnesium ions 2%, sulfate ions 3.6%, chloride ions 12%; the spraying amount of potassium sulfate mother liquor is 8% of the mass of the flotation foam.

[0032] Example 2 This embodiment describes a preparation process for potassium magnesium sulfate fertilizer, which includes the following steps: (a) Under stirring conditions, potassium mixed salt ore was placed in decomposition mother liquor and fresh water for conversion. The ion mass concentrations in the decomposition mother liquor were as follows: potassium ions 2.29%, sodium ions 2.38%, magnesium ions 5.44%, sulfate ions 7.79%, and chloride ions 15.88%. The mass ratio of potassium mixed salt ore, decomposition mother liquor, and fresh water was 1:0.7:0.3. The conversion reaction temperature was 26°C, and the time was 1.5 h. (b) After the conversion is complete, a collector is added for flotation and cleaning to obtain flotation froth, wherein the collector is sodium hexadecyl sulfonate; the amount of collector added is 0.02% of the mass of potassium mixed salt ore; (c) The flotation foam is filtered by a belt filter and potassium sulfate mother liquor is sprayed during the belt filter process to obtain wet-based potassium magnesium sulfate fertilizer, which is then dried and packaged to obtain potassium magnesium sulfate fertilizer; wherein, the ion concentrations in the potassium sulfate mother liquor are as follows: potassium ions 8%, sodium ions 1.2%, magnesium ions 2.6%, sulfate ions 3%, chloride ions 13%; the spraying amount of potassium sulfate mother liquor is 5% of the mass of the flotation foam.

[0033] Example 3 This embodiment describes a preparation process for potassium magnesium sulfate fertilizer, which includes the following steps: (a) Under stirring conditions, potassium mixed salt ore was placed in decomposition mother liquor and fresh water for conversion. The ion mass concentrations in the decomposition mother liquor were as follows: potassium ions 2.29%, sodium ions 2.38%, magnesium ions 5.44%, sulfate ions 7.79%, and chloride ions 15.88%. The mass ratio of potassium mixed salt ore, decomposition mother liquor, and fresh water was 1:0.5:0.2. The conversion reaction temperature was 25°C, and the time was 2 hours. (b) After the conversion is complete, a collector is added for flotation and cleaning to obtain flotation froth, wherein the collector is sodium hexadecyl sulfonate; the amount of collector added is 0.02% of the mass of potassium mixed salt ore; (c) The flotation foam is filtered by a belt filter and potassium sulfate mother liquor is sprayed during the belt filter process to obtain wet-based potassium magnesium sulfate fertilizer, which is then dried and packaged to obtain potassium magnesium sulfate fertilizer; wherein, the ion concentrations in the potassium sulfate mother liquor are as follows: potassium ions 7.0755%, sodium ions 1.4478%, magnesium ions 2.2788%, sulfate ions 3.3071%, chloride ions 12.8556%; the spraying amount of potassium sulfate mother liquor is 5.88% of the mass of the flotation foam.

[0034] Experimental Example Potassium magnesium sulfate fertilizer was prepared using the method described in Example 3; In step (c), K in the flotation foam, wet-based potassium magnesium sulfate fertilizer, and washing liquid+ Na + Mg 2+ SO4 2- Cl - The content was tested, and the results are shown in Table 1: Table 1

[0035] As shown in Table 1, the potassium ion content in the potassium sulfate mother liquor was 7.0755%, while the potassium ion content in the washed liquid was 2.6018%, indicating that some potassium ions in the potassium sulfate mother liquor entered the solid phase. In addition, the potassium ion content in the flotation foam before washing was 16.0521%, while the potassium ion content in the wet-based potassium magnesium sulfate fertilizer after washing became 17.1325%, thus increasing the potassium ion content in the potassium magnesium sulfate fertilizer. Furthermore, the chloride ion content in the flotation foam before washing was 3.3125%, while the chloride ion content in the wet-based potassium magnesium sulfate fertilizer after washing decreased to 1.4227%. Moreover, the sodium ion content was also significantly reduced. It is evident that the technical solution of this application improves the quality of the prepared potassium magnesium sulfate fertilizer through specific process limitations.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A preparation process for potassium magnesium sulfate fertilizer, characterized in that, Includes the following steps: (a) Under stirring conditions, potassium mixed salt ore is placed in decomposition mother liquor and fresh water for conversion reaction; (b) After the conversion is complete, a collector is added for flotation to obtain flotation foam; (c) The flotation foam is filtered by a belt filter and potassium sulfate mother liquor is sprayed during the belt filter process to obtain wet-based potassium magnesium sulfate fertilizer, which is then dried and packaged to obtain potassium magnesium sulfate fertilizer. Both the flotation foam and the potassium sulfate mother liquor contain potassium ions, sodium ions, and chloride ions. The potassium ion content in the potassium sulfate mother liquor is lower than that in the flotation foam, while the chloride and sodium ion content in the potassium sulfate mother liquor is higher than that in the flotation foam.

2. The preparation process of potassium magnesium sulfate fertilizer according to claim 1, characterized in that, The ion concentrations in the mother liquor are as follows: potassium ions 2%–2.5%, sodium ions 2.1%–2.6%, magnesium ions 5.2%–5.6%, sulfate ions 7.5%–8.5%, and chloride ions 15%–16%.

3. The preparation process of potassium magnesium sulfate fertilizer according to claim 1, characterized in that, The mass ratio of the potassium mixed salt ore, decomposition mother liquor, and fresh water is 1:(0.3-0.7):(0.1-0.3).

4. The preparation process of potassium magnesium sulfate fertilizer according to claim 1, characterized in that, The conversion reaction is carried out at a temperature of 24–26°C for 1.5–2.0 h.

5. The preparation process of potassium magnesium sulfate fertilizer according to claim 1, characterized in that, The collector is sodium hexadecyl sulfonate.

6. The preparation process of potassium magnesium sulfate fertilizer according to claim 1 or 5, characterized in that, The amount of collector added is 0.01% to 0.02% of the mass of potassium mixed salt ore.

7. The preparation process of potassium magnesium sulfate fertilizer according to claim 1, characterized in that, The ion concentrations in the potassium sulfate mother liquor are as follows: potassium ions 7%–8%, sodium ions 1.2%–1.8%, magnesium ions 2%–2.6%, sulfate ions 3%–3.6%, and chloride ions 12%–13%.

8. The preparation process of potassium magnesium sulfate fertilizer according to claim 1, characterized in that, The spray volume of the potassium sulfate mother liquor is 5% to 8% of the mass of the flotation foam.

9. The preparation process of potassium magnesium sulfate fertilizer according to any one of claims 1-8, characterized in that, Step (b) also includes refining the flotation foam.

10. A potassium magnesium sulfate fertilizer prepared by the process according to any one of claims 1-9.

Images