Method for synthesizing potassium sulfate calcium magnesium double salt

Abstract

The present invention relates to the technical field of potassium sulfate calcium magnesium double salt production, specifically a method for synthesizing potassium sulfate calcium magnesium double salt. The following steps are included: potassium sulfate and magnesium sulfate are dissolved in water, and the temperature is kept constant at 20-120°C after stirring to obtain a reaction bottom liquid; phosphogypsum is added to the bottom liquid, the temperature is kept constant at 20-120°C, and the constant temperature reaction time is controlled at 0.16-6h; after the constant temperature ends, heating is stopped, cooling is turned on, and the temperature is cooled to 20-40°C; the reaction product is subjected to solid-liquid separation, the solid product is directly dried, and potassium sulfate calcium magnesium double salt is obtained by drying at 50-120°C. After analysis and detection, the filtrate and washing water replace part of the deionized water and are recycled. The raw materials of the present invention are all common and easily available industrial and agricultural raw materials or by-products, minerals and extracts thereof, etc., with low prices; the production process is simple and convenient, and the production control cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of potassium sulfate calcium magnesium double salt production, in particular to a method for synthesizing potassium sulfate calcium magnesium double salt. Background Art

[0002] Industrial by-product gypsum is a by-product or waste residue with calcium sulfate as the main component generated by chemical reactions in industrial production. It is also called chemical gypsum or industrial waste gypsum, including desulfurized gypsum, phosphogypsum, fluorinated gypsum, titanium gypsum, salt (bite) gypsum, etc. If a large amount of waste gypsum is not disposed of and stored arbitrarily, it will not only occupy a large area of ​​land, but also pollute water and soil. The cumulative stockpile of industrial by-product gypsum in my country remains high, of which desulfurized gypsum and phosphogypsum account for more than 80% of the total amount of industrial by-product gypsum. As of now, the cumulative stockpile of phosphogypsum exceeds 900 million tons, and the cumulative stockpile of desulfurized gypsum exceeds 400 million tons.

[0003] Taking phosphogypsum, which has the largest stockpile volume, as an example, phosphogypsum is a solid waste generated in the process of phosphoric acid production. About 5 tons of phosphogypsum are discharged for every ton of phosphoric acid produced. At present, wet phosphoric acid production is the main way of phosphoric acid production in the world and the main source of phosphogypsum. Wet phosphoric acid production is to produce phosphoric acid by decomposing phosphate rock with sulfuric acid. In this process, calcium phosphate, the main component of phosphate rock, reacts with sulfuric acid to produce phosphoric acid and calcium sulfate. Calcium sulfate precipitates in the form of dihydrate, forming phosphogypsum. At present, the method for the final treatment and disposal of phosphogypsum waste residue by most domestic and foreign companies is to store it on the land, that is, to build a phosphogypsum slag yard using engineering principles. During the long-term open-air stacking of phosphogypsum, due to physical and chemical effects such as sun exposure, rain, weathering, and decomposition, the slag yard will form strongly acidic wastewater mainly containing phosphoric acid, which will carry various other dissociated harmful components and penetrate into the ground, causing leaching pollution of soil, surface water and shallow groundwater, thereby affecting the soil environment and water environment. In the process of stacking and treatment, dust will also be generated, affecting air quality and causing harm to human health. Although phosphogypsum can also be industrially transformed and used in the production of building materials, soil conditioners, and chemical raw materials, its utilization rate is not high. The storage of industrial by-product gypsum is not a long-term solution. The comprehensive utilization of resources, high value, industrialization, and capitalization is the only way to survive and develop. Summary of the invention

[0004] In view of the above deficiencies in the prior art, the purpose of the present invention is to provide a method for synthesizing potassium sulfate calcium magnesium double salt, which not only has low cost, but also solves the outlet of a large amount of domestic by-products such as phosphogypsum, magnesium sulfate and its double salt, mineral resources, etc.; and solves the threat of chemical by-product storage to the environment.

[0005] The present invention is achieved by adopting the following technical solutions:

[0006] The method for synthesizing potassium sulfate calcium magnesium double salt comprises the following steps:

[0007] (1) Dissolve potassium sulfate and magnesium sulfate or potassium magnesium sulfate in water, stir and keep the temperature at 20-95°C to obtain a reaction base solution;

[0008] (2) Add calcium sulfate and / or potassium calcium sulfate to the bottom liquid, keep the temperature at 90-120°C, and control the constant temperature reaction time at 0.16-6h;

[0009] (3) After the constant temperature is over, stop heating and start cooling to 20-40℃;

[0010] (4) The reaction product is subjected to solid-liquid separation, the solid phase is washed and filtered to obtain a solid phase product, which is then dried and dried at 50-120° C. to obtain potassium sulfate calcium magnesium double salt. After analysis and testing, the filtrate after solid-liquid separation and the washing water after washing are combined and returned to the reaction bottom liquid for recycling.

[0011] The three preferred solutions are as follows:

[0012] The first type, the weight parts of the raw materials are:

[0013] Potassium sulfate: 75-150 parts;

[0014] Magnesium sulfate: 60-160 parts;

[0015] Calcium sulfate: 105-220 parts;

[0016] Water: 500-1200 parts.

[0017] The second type, the weight parts of the raw materials are:

[0018] Potassium magnesium sulfate: 135-310 parts;

[0019] Calcium sulfate: 105-220 parts;

[0020] Water: 500-1200 parts.

[0021] The third type, the weight parts of the raw materials are:

[0022] Potassium sulfate: 37-75 parts;

[0023] Magnesium sulfate: 60-160 parts;

[0024] Calcium sulfate: 53-110 parts;

[0025] Potassium calcium sulfate: 52-110 parts;

[0026] Water: 500-1200 parts.

[0027] The stirring time in step (1) is 0.5-2h.

[0028] The source of the calcium sulfate is one of phosphogypsum, desulfurized gypsum, halogenated gypsum and natural gypsum.

[0029] In the step (2), stirring is continued.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The equipment required for the reaction is simple, which reduces the equipment investment cost; when using its double salt, the dosage is adjusted according to the content of each component and then added to the water for constant temperature reaction.

[0032] (2) The raw materials are all common and easily available industrial and agricultural raw materials or by-products, minerals and their extracts, etc., which are low in price and the resulting products can be used as fertilizers.

[0033] (3) The production process is simple and convenient, which reduces the production control cost.

[0034] (4) The product yield is high, and the filtrate and washing liquid are recycled (used for dissolving sulfate in the first step), achieving green and environmentally friendly production. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the XRD phase retrieval diagram of Example 1 of the present invention;

[0036] Figure 2 This is the XRD phase retrieval diagram of Example 2 of the present invention;

[0037] Figure 3 This is the XRD phase retrieval diagram of Example 3 of the present invention;

[0038] Figure 4 This is the XRD phase retrieval diagram of Example 4 of the present invention;

[0039] Figure 5 This is the XRD phase retrieval diagram of Example 5 of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose and technical solution of the present invention more clear, the present invention is further described in detail.

[0041] The following are the sources of some raw materials in the examples:

[0042] Potassium magnesium sulfate: Shandong Haihua Co., Ltd.;

[0043] Calcium sulfate of potassium: Shandong Hydro Fertilizer Import & Export Co., Ltd.

[0044] Example 1

[0045] The source of calcium sulfate is phosphogypsum.

[0046] The method for synthesizing potassium sulfate calcium magnesium double salt comprises the following steps:

[0047] (1) Dissolve potassium sulfate and magnesium sulfate in water, stir for 2 hours, and keep the temperature at 20°C to obtain a reaction base solution; magnesium sulfate, potassium sulfate, and deionized water are dissolved and added according to the following mass proportions: 110:140:700;

[0048] (2) Add 150 parts of phosphogypsum into the bottom liquid, stir continuously, keep the temperature at 90°C, and control the constant temperature reaction time at 0.16h;

[0049] (3) After the constant temperature is over, stop heating and start cooling to 20°C;

[0050] (4) The reaction product is subjected to solid-liquid separation, the solid phase is washed to obtain a solid phase product, the solid phase product is dried, and the solid phase product is dried at 120° C. to obtain potassium calcium magnesium sulfate complex salt. After analysis and detection, the filtrate after solid-liquid separation and the washing water after washing are combined and returned to the reaction bottom liquid as the recycled filtrate for recycling.

[0051] The obtained potassium calcium magnesium sulfate complex salt is 223 parts. Among them, the calcium sulfate content in the phosphogypsum is 70%, the theoretical output of potassium calcium magnesium sulfate is 232, and the yield is about 96%. The test results are shown in Figure 1 .

[0052] Example 2

[0053] The source of calcium sulfate is desulfurized gypsum.

[0054] The method for synthesizing potassium sulfate calcium magnesium double salt comprises the following steps:

[0055] (1) Dissolve potassium sulfate and magnesium sulfate in water (the reuse filtrate of Example 1), stir for 2 hours, and keep the temperature constant at 20° C. to obtain a reaction base liquid; magnesium sulfate, potassium sulfate, deionized water, and the reuse filtrate are dissolved and added according to the following mass fractions: 60:75:100:600;

[0056] (2) Add 150 parts of desulfurized gypsum into the bottom liquid, stir continuously, keep the temperature at 90°C, and control the constant temperature reaction time at 6 hours;

[0057] (3) After the constant temperature is over, stop heating and start cooling to 40°C;

[0058] (4) The reaction product is subjected to solid-liquid separation, the solid phase is washed to obtain a solid phase product, the solid phase product is dried, and the solid phase product is dried at 110° C. to obtain potassium sulfate calcium magnesium double salt. After analysis and detection, the filtrate after solid-liquid separation and the washing water after washing are combined and returned to the reaction bottom liquid for recycling.

[0059] The obtained potassium calcium magnesium sulfate complex salt is 207 parts. Among them, the calcium sulfate content in the desulfurized gypsum is 70%, the theoretical output of potassium calcium magnesium sulfate is 216, and the yield is about 95.8%. The test results are shown in Figure 2 .

[0060] Example 3

[0061] The source of calcium sulfate is halogen gypsum.

[0062] The method for synthesizing potassium sulfate calcium magnesium double salt comprises the following steps:

[0063] (1) Dissolve potassium and magnesium sulfate in water, stir for 0.5 h, and keep the temperature at 95° C. to obtain a reaction base solution; potassium and magnesium sulfate and deionized water are dissolved and added in the following mass fractions: 305:700;

[0064] (2) Add 150 parts of halogen gypsum into the bottom liquid, stir continuously, keep the temperature at 90°C, and control the constant temperature reaction time at 6 hours;

[0065] (3) After the constant temperature is over, stop heating and start cooling to 20°C;

[0066] (4) The reaction product is subjected to solid-liquid separation, the solid phase is washed to obtain a solid phase product, the solid phase product is dried, and the solid phase product is dried at 120° C. to obtain potassium sulfate calcium magnesium double salt. After analysis and detection, the filtrate after solid-liquid separation and the washing water after washing are combined and returned to the reaction bottom liquid for recycling.

[0067] The obtained potassium calcium magnesium sulfate complex salt is 224.8 parts. The calcium sulfate content in the halogen gypsum is 70%, the theoretical yield of potassium calcium magnesium sulfate is 232, and the yield is about 96.9%. The test results are shown in Figure 3 .

[0068] Example 4

[0069] The method for synthesizing potassium sulfate calcium magnesium double salt comprises the following steps:

[0070] (1) Dissolve potassium sulfate and magnesium sulfate in water, stir for 0.5 h, and keep the temperature at 20°C to obtain a reaction base solution; magnesium sulfate, potassium sulfate, and deionized water are dissolved and added according to the following mass proportions: 110:75:700;

[0071] (2) Add 110 parts of potassium calcium sulfate and 62 parts of calcium sulfate into the bottom liquid, continue stirring, keep the temperature at 90°C, and control the constant temperature reaction time at 0.16h;

[0072] (3) After the constant temperature is over, stop heating and start cooling to 20°C;

[0073] (4) The reaction product is subjected to solid-liquid separation, the solid phase is washed to obtain a solid phase product, which is then dried at 50°C to obtain potassium sulfate calcium magnesium double salt. After analysis and testing, the filtrate after solid-liquid separation and the washing water after washing are combined and returned to the reaction bottom liquid for recycling.

[0074] The obtained potassium calcium magnesium sulfate double salt is 235.5 parts. The calcium sulfate content in potassium calcium sulfate is about 43.8%, the theoretical yield of potassium calcium magnesium sulfate is 242, and the yield is about 97.3%. The test results are shown in Figure 4 .

[0075] Example 5

[0076] The source of calcium sulfate is phosphogypsum.

[0077] The method for synthesizing potassium sulfate calcium magnesium double salt comprises the following steps:

[0078] (1) Dissolve potassium and magnesium sulfate in water, stir for 2 hours, and keep the temperature at 95°C to obtain a reaction base solution; potassium and magnesium sulfate and deionized water are dissolved and added according to the following mass fractions: 200:760;

[0079] (2) Add 200 parts of phosphogypsum into the bottom liquid, stir continuously, keep the temperature at 120°C, and control the constant temperature reaction time at 6 hours;

[0080] (3) After the constant temperature is over, stop heating and start cooling to 40°C;

[0081] (4) The reaction product is subjected to solid-liquid separation, the solid phase is washed to obtain a solid phase product, which is then dried at 50°C to obtain potassium sulfate calcium magnesium double salt. After analysis and testing, the filtrate after solid-liquid separation and the washing water after washing are combined and returned to the reaction bottom liquid for recycling.

[0082] The obtained potassium calcium magnesium sulfate complex salt is 226 parts; the filtrate and washing liquid are collected and recycled. The calcium sulfate content in phosphogypsum is about 53%, the theoretical yield of potassium calcium magnesium sulfate is 234.5, and the yield is about 96.4%. The test results are shown in Figure 5 .

[0083] The X-ray fluorescence spectrometer test results of Example 1 and Example 2 are shown in Table 1.

[0084] Table 1: X-ray fluorescence spectrometer test results of Example 1 and Example 2

[0085]

Claims

1. A method for synthesizing potassium sulfate calcium magnesium double salt, characterized in that: The following steps are involved: (1) Dissolve potassium sulfate and magnesium sulfate or potassium magnesium sulfate in water, stir and keep the temperature at 20-95°C to obtain a reaction base solution; (2) Add calcium sulfate and / or potassium calcium sulfate to the bottom liquid, keep the temperature at 90-120°C, and control the constant temperature reaction time at 0.16-6h; (3) After the constant temperature is over, stop heating and start cooling to 20-40℃; (4) performing solid-liquid separation on the reaction product, washing and filtering the solid phase to obtain a solid phase product, drying the solid phase product, and drying the solid phase product at 50-120° C. to obtain potassium calcium magnesium sulfate complex salt. After analysis and testing, the filtrate after solid-liquid separation and the washing water after washing are combined and returned to the reaction bottom liquid for recycling; When potassium sulfate, magnesium sulfate, calcium sulfate and water are used to prepare potassium sulfate calcium magnesium double salt, the weight parts of each raw material are: Potassium sulfate: 75-150 parts; Magnesium sulfate: 60-160 parts; Calcium sulfate: 105-220 parts; Water: 500-1200 parts.

2. The method for synthesizing potassium calcium magnesium sulfate double salt according to claim 1, characterized in that: When potassium sulfate, magnesium sulfate, calcium sulfate and water are used to prepare potassium sulfate, calcium sulfate and magnesium double salt, the weight parts of each raw material are: Potassium magnesium sulfate: 135-310 parts; Calcium sulfate: 105-220 parts; Water: 500-1200 parts.

3. The method for synthesizing potassium calcium magnesium sulfate double salt according to claim 1, characterized in that: When potassium sulfate, magnesium sulfate, calcium sulfate, potassium calcium sulfate and water are used to prepare potassium calcium magnesium sulfate double salt, the weight parts of each raw material are: Potassium sulfate: 37-75 parts; Magnesium sulfate: 60-160 parts; Calcium sulfate: 53-110 parts; Potassium calcium sulfate: 52-110 parts; Water: 500-1200 parts.

4. The method for synthesizing potassium calcium magnesium sulfate double salt according to claim 1, characterized in that: The stirring time in step (1) is 0.5-2h.

5. The method for synthesizing potassium calcium magnesium sulfate double salt according to claim 1, characterized in that: The source of the calcium sulfate is one of phosphogypsum, desulfurized gypsum, halogenated gypsum and natural gypsum.

6. The method for synthesizing potassium calcium magnesium sulfate double salt according to claim 1, characterized in that: In the step (2), stirring is continued.

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