A method for regulating the morphology of phosphogypsum-based calcium sulfate dihydrate crystals

Abstract

The invention discloses a method for regulating the crystal morphology of phosphogypsum-based calcium sulfate dihydrate. The method achieves regulation of the crystal morphology of phosphogypsum-based calcium sulfate dihydrate by adjusting the type of anti-solvent and the reaction temperature, thereby increasing the added value of the product, having significant economic benefits, and broadening the use of phosphogypsum.

Description

Technical Field

[0001] The invention relates to a method for regulating the morphology of phosphogypsum-based calcium sulfate dihydrate crystals, and belongs to the technical field of chemical raw material preparation. Background Art

[0002] Phosphorus chemical industry is one of the pillar industries in my country. While bringing economic benefits, it also produces solid waste - phosphogypsum. Due to the huge output of phosphogypsum and low comprehensive utilization rate, it is mainly stored in piles. The large-scale storage of phosphogypsum not only occupies a large amount of land and wastes a lot of money, but also causes a series of environmental problems, causing the acid-base imbalance of the soil around the storage yard and polluting the surrounding farmland; the filtrate seeps into the groundwater, causing water resource pollution; due to the huge output, the dam of the storage yard is getting higher and higher, and there is a risk of dam collapse at any time, threatening the lives of surrounding residents; currently, phosphogypsum is used in building materials, roadbed, soil conditioner, chemical raw materials and polymer filling, and the structure of phosphogypsum is an important factor affecting its application. Therefore, regulating the structure of phosphogypsum and improving its added value are of great practical significance for the resource utilization of phosphogypsum.

[0003] In the regulation of phosphogypsum structure, the atmospheric pressure acidification method is usually used to adjust the structure of calcium sulfate dihydrate, and the crystal form regulator (crystallization aid) is used to change the way the crystal grows. To this end, we proposed to use the anti-solvent method to regulate the structure of phosphogypsum, and to achieve the regulation of the morphology of calcium sulfate dihydrate in phosphogypsum by adjusting the type of anti-solvent and the reaction temperature. Summary of the invention

[0004] The present invention proposes a new method for adjusting phosphogypsum-based calcium sulfate dihydrate to prepare phosphogypsum crystals with various controllable morphologies, thereby solving the problem in the prior art that the application field of phosphogypsum is limited by its morphology and expanding its application field. In addition, the method is simple to operate, the solvent is environmentally friendly, and the effect is obvious.

[0005] The technical solution of the present invention is a method for regulating the morphology of phosphogypsum-based calcium sulfate dihydrate crystals, comprising the following steps:

[0006] (1) Preparation of phosphogypsum solution: first, dry the phosphogypsum at 60°C, crush the phosphogypsum and pass it through a 100-mesh sieve, dissolve the phosphogypsum in deionized water at a solid-liquid ratio of 1:100-500, stir at room temperature for a certain period of time, filter out insoluble matter, and obtain a phosphogypsum solution.

[0007] (2) Structural regulation: A certain amount of phosphogypsum solution is placed in a stirring and heating device at a heating temperature of 1 to 75°C and a stirring rate of 100 to 500 r / min. Then, aliphatic alcohol at the same temperature is added to the phosphogypsum solution in an amount of 20 to 100% of the phosphogypsum solution. The solution is stirred and heated for 3 to 10 minutes, and filtered while hot to obtain a filter cake.

[0008] (3) Drying: Dry the filter cake obtained above at 50-80°C for 2-8 hours to obtain the product.

[0009] Beneficial effects of the present invention:

[0010] The method of the application is simple to operate, the solvent is environmentally friendly, the effect is obvious, and it has a larger specific surface area. The obtained phosphogypsum-based calcium sulfate dihydrate crystals have good adsorption performance for metal ions in water. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 To control the flow chart;

[0012] Figure 2 This is the product morphology of methanol at 55°C;

[0013] Figure 3 This is the product morphology of ethanol at 55°C;

[0014] Figure 4 This is the product morphology of n-propanol at 55°C;

[0015] Figure 5 This is the product morphology of isopropanol at 55°C;

[0016] Figure 6 This is the product morphology of isopropanol at 15°C.

[0017] Figure 7 Specific surface area and adsorption properties of phosphogypsum-based calcium sulfate dihydrate crystals prepared with different anti-solvents. DETAILED DESCRIPTION

[0018] Example 1

[0019] A method for regulating the morphology of phosphogypsum-based calcium sulfate dihydrate crystals, comprising the following steps:

[0020] (1) Preparation of phosphogypsum solution: The phosphogypsum was first dried at 60°C, crushed and passed through a 100-mesh sieve, dissolved in deionized water at a solid-liquid ratio of 1:200, stirred at room temperature for 4 hours, and the insoluble matter was filtered out to obtain a phosphogypsum solution.

[0021] (2) Structural regulation: A certain amount of phosphogypsum solution was placed in a stirring and heating device at a heating temperature of 55°C and a stirring rate of 200 r / min. Methanol at the same temperature was then added to the phosphogypsum solution in an amount of 30% of the phosphogypsum solution. The solution was stirred and heated for 5 min and filtered while hot to obtain a filter cake.

[0022] (3) Drying: The filter cake obtained above was dried at 60°C for 4 hours to obtain the product.

[0023] The obtained product is in the form of white powder, and its microscopic appearance is butterfly-shaped thin crystals, with a crystal length of 30 to 100 μm, a width of 20 to 30 μm, and a thickness of 1 to 10 μm; its composition is calcium sulfate dihydrate, and its whiteness is 90.60%. Figure 2

[0024] (4) Specific surface area and adsorption performance of the obtained phosphogypsum-based calcium sulfate dihydrate crystals Figure 7 shown.

[0025] Example 2

[0026] A method for regulating the morphology of phosphogypsum-based calcium sulfate dihydrate crystals, comprising the following steps:

[0027] (1) Preparation of phosphogypsum solution: The phosphogypsum was first dried at 60°C, crushed and passed through a 100-mesh sieve, dissolved in deionized water at a solid-liquid ratio of 1:200, stirred at room temperature for 4 hours, and the insoluble matter was filtered out to obtain a phosphogypsum solution.

[0028] (2) Structural regulation: A certain amount of phosphogypsum solution was placed in a stirring and heating device at a heating temperature of 55°C and a stirring rate of 200 r / min. Ethanol at the same temperature was then added to the phosphogypsum solution in an amount of 30% of the phosphogypsum solution. The solution was stirred and heated for 5 min and filtered while hot to obtain a filter cake.

[0029] (3) Drying: The filter cake obtained above was dried at 60°C for 4 hours to obtain the product.

[0030] The obtained product is a white powder, and its microscopic morphology is the coexistence of butterfly-shaped thin flake crystals and columnar crystals. The white butterfly-shaped thin flake crystals are 30 to 150 μm in length, 20 to 30 μm in width, and 1 to 10 μm in thickness; the columnar crystals are 30 to 150 μm in length and 3 to μm in diameter; the product component is calcium sulfate dihydrate, and the whiteness is 91.86%.

[0031] (4) Specific surface area and adsorption performance of the obtained phosphogypsum-based calcium sulfate dihydrate crystals Figure 7 shown.

[0032] Example 3

[0033] A method for regulating the morphology of phosphogypsum-based calcium sulfate dihydrate crystals, comprising the following steps:

[0034] (1) Preparation of phosphogypsum solution: The phosphogypsum was first dried at 60°C, crushed and passed through a 100-mesh sieve, dissolved in deionized water at a solid-liquid ratio of 1:200, stirred at room temperature for 4 hours, and the insoluble matter was filtered out to obtain a phosphogypsum solution.

[0035] (2) Structural regulation: A certain amount of phosphogypsum solution was placed in a stirring and heating device at a heating temperature of 55°C and a stirring rate of 200 r / min. Then, n-propanol at the same temperature was added to the phosphogypsum solution in an amount of 30% of the phosphogypsum solution. The solution was stirred and heated for 5 minutes and filtered while hot to obtain a filter cake.

[0036] (3) Drying: The filter cake obtained above was dried at 60°C for 4 hours to obtain the product.

[0037] The obtained product is white powder, and its microscopic morphology is hexagonal crystals, with a length of 5 to 50 μm and a diameter of 1 to 2 μm. The product component is calcium sulfate dihydrate, and its whiteness is 96.26%.

[0038] Example 4

[0039] A method for regulating the morphology of phosphogypsum-based calcium sulfate dihydrate crystals, comprising the following steps:

[0040] (1) Preparation of phosphogypsum solution: The phosphogypsum was first dried at 60°C, crushed and passed through a 100-mesh sieve, dissolved in deionized water at a solid-liquid ratio of 1:200, stirred at room temperature for 4 hours, and the insoluble matter was filtered out to obtain a phosphogypsum solution.

[0041] (2) Structural regulation: A certain amount of phosphogypsum solution was placed in a stirring and heating device at a heating temperature of 55°C and a stirring rate of 200 r / min. Then, isopropanol at the same temperature was added to the phosphogypsum solution in an amount of 30% of the phosphogypsum solution. The solution was stirred and heated for 5 minutes and filtered while hot to obtain a filter cake.

[0042] (3) Drying: The filter cake obtained above was dried at 60°C for 4 hours to obtain the product.

[0043] The obtained product is white powder, and its microscopic morphology is hexagonal crystals, with a length of 10-70 μm and a diameter of 1-2 μm. The product component is calcium sulfate dihydrate, and the whiteness is 95.93%.

[0044] (4) Specific surface area and adsorption performance of the obtained phosphogypsum-based calcium sulfate dihydrate crystals Figure 7 shown.

[0045] Example 5

[0046] A method for regulating the morphology of phosphogypsum-based calcium sulfate dihydrate crystals, comprising the following steps:

[0047] (1) Preparation of phosphogypsum solution: The phosphogypsum was first dried at 60°C, crushed and passed through a 100-mesh sieve, dissolved in deionized water at a solid-liquid ratio of 1:200, stirred at room temperature for 4 hours, and the insoluble matter was filtered out to obtain a phosphogypsum solution.

[0048] (2) Structural regulation: A certain amount of phosphogypsum solution was placed in a stirring and heating device at a heating temperature of 15°C and a stirring rate of 200 r / min. Then, n-propanol at the same temperature was added to the phosphogypsum solution in an amount of 30% of the phosphogypsum solution. The solution was stirred and heated for 5 min, and filtered to obtain a filter cake.

[0049] (3) Drying: The filter cake obtained above was dried at 60°C for 4 hours to obtain the product.

[0050] The obtained product is white powder, and its microscopic morphology is hexagonal crystals, with a length of 1 to 5 μm and a diameter of 0.1 to 0.3 μm. The product component is calcium sulfate dihydrate, and its whiteness is 95.74%.

Claims

1. A method for regulating the crystal structure of phosphogypsum-based calcium sulfate dihydrate, characterized in that: Using phosphogypsum as a source of calcium sulfate dihydrate, using water as a phosphogypsum solvent, and aliphatic alcohol as an anti-solvent, mixing, stirring, and heating to obtain the product; comprising the following steps: (1) Preparation of phosphogypsum solution: dissolving the dried phosphogypsum in deionized water at a solid-liquid ratio of 1:200, stirring at room temperature, and filtering out insoluble matter to obtain a phosphogypsum solution; (2) Structural regulation: Place the phosphogypsum solution in a stirring and heating device at a heating temperature of 15-55°C and a stirring rate of 100-500 r / min. Then, add aliphatic alcohol at the same temperature to the phosphogypsum solution in an amount of 30% of the phosphogypsum solution. Stir and heat for 3-10 minutes, and filter while hot to obtain a filter cake. (3) Drying: Drying the filter cake obtained above at 50-80°C for 2-8 hours to obtain the product; The aliphatic alcohol is n-propanol, isopropanol, ethanol or methanol.

2. The method for controlling the morphology of phosphogypsum-based calcium sulfate dihydrate crystals according to claim 1, characterized in that: In the step (1), the stirring time at room temperature is 4 hours.

3. The method for controlling the morphology of phosphogypsum-based calcium sulfate dihydrate crystals according to claim 1, characterized in that: In the step (2), the heating temperature is 55°C.

4. The method for controlling the morphology of phosphogypsum-based calcium sulfate dihydrate crystals according to claim 1, characterized in that: In the step (2), the stirring rate is 200 r / min.

5. The method for controlling the morphology of phosphogypsum-based calcium sulfate dihydrate crystals according to claim 1, characterized in that: In the step (2), the stirring and heating time is 5 minutes.

6. The method for controlling the morphology of phosphogypsum-based calcium sulfate dihydrate crystals according to claim 1, characterized in that: In the step (3), the drying time is 4 hours.

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