Preparation method and application of anhydrite-celestite solid solution
The aneplasma-sacrificial solid solution was prepared by co-precipitation, and the reaction of sulfate with calcium nitrate and strontium nitrate was solved, and the problem of difficult to remove or recover strontium in the solution in the prior art was achieved, efficient removal and recovery of strontium was reduced, and the risk of excessive strontium content in the environment was reduced.
Patent Information
- Application Number
- CN202411754574.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-02
- Publication Date
- 2025-03-11
AI Technical Summary
The prior art is difficult to effectively remove or recover heavy metal strontium in solution, and radioactive strontium poses a threat to the environment and human health.
Aphroplaster-sacrificial solid solution was prepared by co-precipitation, and a solid solution that can effectively remove or recover strontium in the solution was prepared by reacting sulfate with calcium nitrate and strontium nitrate.
Efficient removal or recovery of strontium is achieved, and the leaching concentration of strontium is low in water environments under neutral and acidic conditions, reducing the risk of excessive strontium content in the environment.
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Figure CN119591141A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of environmental safety and technology, and relates to a preparation method and application of anhydrite-celestite solid solution. The method utilizes sulfate to react with calcium nitrate and strontium nitrate, and obtains anhydrite-celestite series solid solution after high-temperature calcination, which is used to remove or recover heavy metal strontium in the solution. Background Art
[0002] Strontium is a silvery white alkaline earth metal with a yellow luster. It is the least abundant element among alkaline earth metals. Strontium is an indispensable trace element in the human body. It is contained in all tissues of the human body. Studies have found that when the strontium content in drinking water is 5.0-10.0 mg / L, the mortality rate of cardiovascular disease in the population is the lowest. However, excessive Sr can affect the body's bone mineral metabolism, resulting in abnormal bone growth and development; radioactivity can also cause the body to be damaged. 90 Sr can also cause a series of negative effects on human skin and tissues and organs, such as skin ulcers, nausea, mental distraction, dizziness and fatigue, etc. It can cause serious damage to the human hematopoietic system and affect the human nerve regulation function. Since strontium easily reacts chemically with air and water, there is no natural single strontium. It appears in the form of compounds. Its main mineral is celestite (SrSO4). Celestite is the most important strontium ore raw material for the production of various compounds, mainly used to produce strontium carbonate. Strontium compounds can be used to produce cathode ray tubes and fluorescent screens for color televisions, and can also be used in the manufacture of ceramic ferrite magnets. It is also the main raw material for the production of other strontium salts.
[0003] Sulfate is composed of sulfate ions (SO4 2- Sulfate minerals are salts formed by the combination of metal cations (including ammonium ions) and sulfate ions. Sulfur is a variable valence element. In nature, it can form different minerals in different valence states. When it is in the highest valence state, S 6+ With four O 2- Combined into SO4 2-, and then react with metal cations to form sulfate. There are many metal ions in the environment that can combine with sulfate to form stable sulfate minerals. Sulfate minerals undergo various mineral-water reactions with water containing high concentrations of dissolved solids, and reliable predictions of the solubility of sulfate mineral components in water are necessary for many geological, hydrological, industrial and meteorological applications. The precipitation of pure sulfate minerals or sulfate-containing solid solutions can limit the concentrations of dissolved metals, radionuclides and other cations in waste disposal sites, oceans and other naturally occurring salt water, industrial water and smoke. The formation of these metal-containing sulfate solids can control the geochemical behavior of cations in water, thereby affecting their trace components in the environment. Utilizing this mechanism, sodium sulfate is used to react with calcium salts and strontium salts to form strontium-containing gypsum, thereby removing or recovering strontium ions dissolved in aqueous solution. The present invention provides a method for preparing anhydrite-celestite solid solution for removing or recovering heavy metal strontium. Summary of the invention
[0004] The purpose of the present invention is to provide a preparation method and application of anhydrite-celestite solid solution. First, strontium-containing gypsum is prepared by coprecipitation, and anhydrite-celestite series solid solutions are obtained after high-temperature calcination, and then the solid solutions are characterized and analyzed; secondly, the cation leaching concentration of the solid solution under nitrogen degassing, pH=3 and pH=9 ultrapure water conditions is tested; finally, the stability of strontium is experimentally analyzed in detail to provide a theoretical basis for exploring its distribution effect in solid solution-water solution.
[0005] A method for preparing anhydrite-celestite series solid solution, the specific steps of which are:
[0006] First, prepare fresh ultrapure water, and prepare 1.0 mol / L sodium sulfate solution, 1.0 mol / L calcium nitrate solution, and 1.0 mol / L strontium nitrate solution respectively for use.
[0007] Secondly, different volumes of 1.0 mol / L calcium nitrate solution and 1.0 mol / L strontium nitrate solution were measured to prepare 50 mL of a mixed solution with a molar ratio of Sr / (Ca+Sr) (as in 'Specific Implementation Method').
[0008] Finally, at room temperature (about 25°C), 500 mL of 1.0 mol / L sodium sulfate solution was slowly added to the polyethylene bottle containing the mixed solution using a separatory funnel, and the stirring speed of the stirrer was 500 r / min. After the sodium sulfate solution was added, the reaction was continued for 15 min. The polyethylene bottle was removed and the lid was screwed on. After aging for 1 day, the pH value of the supernatant was measured and filtered.
[0009] The anhydrite-celestite series solid solution obtained by the present invention is applied to the recovery of strontium in the solution and the long-term stacking of waste residue containing strontium or radioactive strontium in the environment, and the specific steps are:
[0010] Solid-liquid separation is carried out at room temperature, and the obtained solid precipitate is washed multiple times with ultrapure water. The washed solid precipitate is placed in a 90°C forced air drying oven and dried for 24 hours. After high-temperature calcination at 830°C, the preparation of anhydrite-celestite series solid solutions is completed, thereby realizing the recovery and long-term stacking of strontium-containing or radioactive strontium element waste residues in the environment.
[0011] Leaching test: Weigh 20g of the synthetic anhydrite-solid solution series solid solution samples and place them in 3 groups of 5L polyethylene terephthalate (PET) bottles. Add 5L of nitrogen-degassed ultrapure water with pH=3 and pH=9 to each group of bottles, seal the PET bottles, shake them gently, and dissolve them at room temperature (air conditioning 25℃). During the dissolution process, take a certain volume of supernatant sample at 1h, 3h, 6h, 12h, 1d, 2d, 3d, 5d, 10d, 15d, 20d, 30d, 40d, 50d, 60d, 70d, 80d, 90d, 120d and 150d (h means hours, d means days) to determine Sr 2+ , Ca 2+ The concentration of calcium and strontium is obtained by measuring the leaching concentration of anhydrite-celestite series solid solution. After 80 days of leaching, the leaching concentration of strontium in nitrogen degassed ultrapure water and pH=3 is low, while the leaching concentration under pH=9 is higher than the former two. It can be seen that when anhydrite-celestite series solid solution is piled up in the environment, it cannot be in contact with alkaline substances or piled together to avoid accidents of excessive strontium content in water or soil.
[0012] The present invention utilizes sulfate to react with calcium nitrate and strontium nitrate, and obtains anhydrite-celestite series solid solutions after high-temperature calcination, which are used to remove or recover heavy metal strontium in the solution. The celestite solid solution obtained by the method can well remove or recover the heavy metal element strontium in the solution, and has a low leaching concentration in a water environment under neutral and acidic conditions. After a long period of dissolution, the leaching concentration of strontium ions slowly decreases, and reaches equilibrium after decreasing to a low level. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 The XRD diagrams of the anhydrite-celestite series solid solutions prepared in Examples 1 to 5 of the present invention, wherein the anhydrite reference card is PDF#01-086-2270, the celestite reference card is PDF#01-089-0953, and the strontium sulfate reference card is PDF#01-083-1719.
[0014] Figure 2 This is a scanning electron microscope image (SEM) of the anhydrite solid solution prepared in Example 1 of the present invention.
[0015] Figure 3 This is a scanning electron microscope image (SEM) of the celestite solid solution obtained in Example 5 of the present invention. DETAILED DESCRIPTION
[0016] Example 1
[0017] At room temperature, 50 mL of 1.0 mol / L calcium nitrate solution was measured in a 1000 mL polyethylene bottle, and the polyethylene bottle was placed on an intelligent magnetic stirrer, the stirrer speed was set to 500 r / min, and stirring was started; about 5 minutes later, 500 mL of 1.0 mol / L sodium sulfate solution was added to the polyethylene bottle containing calcium nitrate, and the reaction was carried out for 15 minutes; after the reaction was completed, the bottle was sealed with plastic wrap and aged for 1 day; the pH value of the supernatant was measured with a desktop pH meter and filtered. During the filtration process, the beaker was washed with ultrapure water 3 times and anhydrous ethanol once. The obtained solid sample was dried in a 90℃ forced air drying oven for 24 hours, and anhydrite solid solution was obtained after high-temperature calcination at 830℃.
[0018] Example 2
[0019] At room temperature, 43 mL of 1.0 mol / L calcium nitrate solution and 7 mL of 1.0 mol / L strontium nitrate solution were placed in a 1000 mL polyethylene bottle, and the polyethylene bottle was placed in an intelligent magnetic stirrer, and the stirrer speed was set to 500 r / min, and stirring was started; after about 5 minutes, 500 mL of 1.0 mol / L sodium sulfate solution was added to the polyethylene bottle containing the calcium and strontium mixture, and the reaction was carried out for 15 minutes; after the reaction was completed, the bottle was sealed with plastic wrap and aged for 1 day; the pH value of the supernatant was measured with a desktop pH meter and filtered. During the filtration process, the beaker was washed with ultrapure water 3 times and anhydrous ethanol once. The obtained solid sample was dried in a 90℃ forced air drying oven for 24 hours, and after high-temperature calcination at 830℃, an anhydrite-celestite solid solution with a Sr / (Ca+Sr) molar ratio of 0.14 was obtained.
[0020] Leaching test:
[0021] Nitrogen degassed ultrapure water, dissolved at 25°C for 80 days, strontium leaching concentration 0.1680 mmol / L;
[0022] Ultrapure water with pH=3, dissolved at 25°C for 80 days, strontium leaching concentration is 0.1739 mmol / L;
[0023] Ultrapure water with pH=9, dissolved at 25°C for 80 days, the strontium leaching concentration is 0.1913 mmol / L.
[0024] Example 3
[0025] At room temperature, 35 mL of 1.0 mol / L calcium nitrate solution and 15 mL of 1.0 mol / L strontium nitrate solution were measured in a 1000 mL polyethylene bottle, and the polyethylene bottle was placed in an intelligent magnetic stirrer with a stirrer speed of 500 r / min. After about 5 minutes, 500 mL of 1.0 mol / L sodium sulfate solution was added to the polyethylene bottle containing the calcium and strontium mixture, and the reaction was carried out for 15 minutes. After the reaction was completed, the bottle was sealed with plastic wrap and aged for 1 day. The pH value of the supernatant was measured with a benchtop pH meter and filtered. During the filtration process, the beaker was washed with ultrapure water 3 times and anhydrous ethanol once. The obtained solid sample was dried in a 90℃ forced air drying oven for 24 hours, and after high-temperature calcination at 830℃, an anhydrite-celestite solid solution with a Sr / (Ca+Sr) molar ratio of 0.30 was obtained.
[0026] Leaching test:
[0027] Nitrogen degassed ultrapure water, dissolved at 25°C for 80 days, strontium leaching concentration 0.1529 mmol / L;
[0028] Ultrapure water with pH=3, dissolved at 25°C for 80 days, strontium leaching concentration is 0.1593 mmol / L;
[0029] Ultrapure water with pH=9, dissolved at 25°C for 80 days, the strontium leaching concentration is 0.1732 mmol / L.
[0030] Example 4
[0031] At room temperature, 14 mL of 1.0 mol / L calcium nitrate solution and 36 mL of 1.0 mol / L strontium nitrate solution were measured in a 1000 mL polyethylene bottle, and the polyethylene bottle was placed in an intelligent magnetic stirrer with a stirrer speed of 500 r / min. After about 5 minutes, 500 mL of 1.0 mol / L sodium sulfate solution was added to the polyethylene bottle containing the calcium and strontium mixture, and the reaction was carried out for 15 minutes. After the reaction was completed, the bottle was sealed with plastic wrap and aged for 1 day. The pH value of the supernatant was measured with a benchtop pH meter and filtered. During the filtration process, the beaker was washed with ultrapure water 3 times and anhydrous ethanol once. The obtained solid sample was dried in a 90℃ forced air drying oven for 24 hours, and after high-temperature calcination at 830℃, an anhydrite-celestite solid solution with a Sr / (Ca+Sr) molar ratio of 0.72 was obtained.
[0032] Leaching test:
[0033] Nitrogen degassed ultrapure water, dissolved at 25°C for 80 days, strontium leaching concentration 0.2808 mmol / L;
[0034] Ultrapure water with pH=3, dissolved at 25°C for 80 days, strontium leaching concentration is 0.2440 mmol / L;
[0035] Ultrapure water with pH=9, dissolved at 25°C for 80 days, the strontium leaching concentration is 0.2789 mmol / L.
[0036] Example 5
[0037] At room temperature, 50 mL of 1.0 mol / L strontium nitrate solution was measured in a 1000 mL polyethylene bottle, and the polyethylene bottle was placed in an intelligent magnetic stirrer with the stirrer speed set to 500 r / min; about 5 minutes later, 500 mL of 1.0 mol / L sodium sulfate solution was added to the polyethylene bottle containing strontium nitrate and reacted for 15 minutes; after the reaction was completed, the bottle was sealed with plastic wrap and aged for 1 day; the pH value of the supernatant was measured with a benchtop pH meter and filtered. During the filtration process, the beaker was washed with ultrapure water 3 times and anhydrous ethanol once. The obtained solid sample was dried in a 90℃ forced air drying oven for 24 hours, and the celestite solid solution was obtained after high-temperature calcination at 830℃. According to the mass of the solid obtained after calcination, the removal rate or recovery rate of strontium was calculated to be close to 100%.
[0038] Leaching test:
[0039] Nitrogen degassed ultrapure water, dissolved at 25°C for 80 days, strontium leaching concentration 0.3709 mmol / L;
[0040] Ultrapure water with pH=3, dissolved at 25°C for 80 days, strontium leaching concentration is 0.4022 mmol / L;
[0041] Ultrapure water with pH=9, dissolved at 25°C for 80 days, the strontium leaching concentration is 0.3752 mmol / L.
Claims
1. A method for preparing anhydrite-celestite series solid solution, characterized in that: The specific steps are: (1) Prepare fresh ultrapure water, weigh an appropriate amount of sodium sulfate solid, and prepare a 1.0 mol / L sodium sulfate solution for later use; weigh an appropriate amount of calcium nitrate solid, and prepare a 1.0 mol / L calcium nitrate solution for later use; weigh an appropriate amount of strontium nitrate solid, and prepare a 1.0 mol / L strontium nitrate solution for later use; (2) In a clean polyethylene bottle, prepare 50 mL of mixed solutions with Sr / (Ca+Sr) molar ratios of 0.00, 0.10, 0.12, 0.14, 0.16, 0.18, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.72, 0.74, 0.76, 0.78, 0.80, 0.90 and 1.00, respectively; (3) At room temperature (about 25°C), place the polyethylene bottle in step (2) on top of a stirrer, set the stirring speed to 500 r / min, and start stirring; (4) Add 500 mL of the sodium sulfate solution from step (1) to the mixed solution; (5) After the sodium sulfate solution is added, the reaction is continued for 15 minutes; the polyethylene bottle is removed, sealed with plastic wrap, and after aging for 1 day, the pH value of the supernatant is measured and filtered; during the filtration process, the beaker is washed with ultrapure water 3 times and with anhydrous ethanol once; the obtained solid phase precipitate is dried in a 90°C forced air drying oven for 24 hours, and then calcined at 830°C to complete the preparation of the anhydrite-celestite series solid solution, thereby realizing the removal, recovery and long-term stacking of strontium or radioactive strontium element waste residues in the environment.
2. An application of anhydrite-celestite series solid solution prepared by the method according to claim 1, characterized in that It is used for the recovery of strontium in solution and the sealing of waste residue containing strontium or radioactive strontium in the environment, and has the following characteristics: 20g of anhydrite-solid solution series solid solution samples were weighed and placed in ultrapure water at 25°C, degassed with nitrogen, pH=3 and pH=9 for dissolution testing. The results showed that after 80 days of dissolution under these three aqueous solution conditions, the leaching concentrations of strontium were 0.1529 mmol / L, 0.1593 mmol / L and 0.1732 mmol / L, respectively.