A method of hydrothermally preparing an apatite-based molten salt waste form

Abstract

The application discloses a method for hydrothermally preparing an apatite-based molten salt waste solidification body, which comprises the following steps: S1, uniformly mixing molten salt waste and hydroxyapatite powder to obtain a mixture; and S2, placing the mixture into a heating device to perform a hydrothermal reaction, and synthesizing the molten salt waste solidification body. The hydroxyapatite has good adsorption capacity, acid-base adjustability, ion exchange capacity and thermal stability. Since the hydroxyl and calcium ions can be replaced by chlorides and various metal ions respectively, the hydroxyapatite is used to fix the molten salt waste, the waste ions are introduced into the crystal lattice through a substitution reaction, and thus the hydroxyapatite can effectively solidify the molten salt waste. The obtained molten salt waste solidification body has the advantages of large capacity, good chemical stability and the like, and can effectively inhibit the pollution of the molten salt waste to the ecological environment. The method has high use value and development potential.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of molten salt waste treatment, and particularly relates to a method for hydrothermally preparing an apatite-based molten salt waste solidification body. BACKGROUND

[0002] With the continuous development of nuclear technology, molten salt reactors have attracted widespread attention due to their good neutron performance, inherent safety, online reprocessing, sustainable development, and nuclear proliferation prevention. During the operation of the reactor, a large amount of radioactive waste produced by fission will accumulate in the lithium chloride-potassium chloride molten medium, forming molten salt waste. In addition, a large amount of molten salt waste will also be produced in the process of electrolytic refining of traditional reactor spent fuel to recover fuel and precious metals. Molten salt waste has the characteristics of strong radioactivity, long half-life, strong diffusion ability, and great toxicity, which poses a potential threat to human health and the living environment.

[0003] There are two ways to deal with molten salt waste. One is to choose a suitable matrix for containment treatment. Since conventional silicate glass has low compatibility with chlorides, it cannot be directly used to solidify waste molten salt. The second is to convert chlorides into other forms of compounds, such as phosphate, oxide, etc., and then perform solidification treatment. The use of the conversion method undoubtedly produces more procedures, making it difficult to meet the long-term disposal needs of molten salt waste. SUMMARY

[0004] The present application proposes a method for hydrothermally preparing an apatite-based molten salt waste solidification body to solve the above problems.

[0005] The technical solutions adopted by the present application are as follows:

[0006] A method for hydrothermally preparing an apatite-based molten salt waste solidification body, comprising the following steps:

[0007] S1, uniformly mixing molten salt waste and hydroxyapatite powder to obtain a mixture;

[0008] S2, placing the mixture into a heating device for hydrothermal reaction to synthesize a molten salt waste solidification body.

[0009] Apatite is a kind of calcium phosphate mineral, and its chemical composition is Ca5 (PO4) 3 (F, Cl, OH). Hydroxyapatite Ca5 (PO4) 3 (OH) 2 has good adsorption capacity, acid-base adjustment, ion exchange capacity and thermal stability. Because hydroxyl and calcium ions can be replaced by chloride and various metal ions respectively, the hydroxyapatite can be used to fix the molten salt waste, and through the substitution reaction, the waste ions are introduced into the crystal lattice, that is, the hydroxyapatite can realize the effective solidification of the molten salt waste. The obtained molten salt waste solidification body has the advantages of large capacity and good chemical stability, and can effectively inhibit the pollution of molten salt waste to the ecological environment. The method has high use value and development potential.

[0010] In one embodiment of the present application, in step S1, the molten salt waste and hydroxyapatite powder are stirred in a liquid environment, using water as the medium, and stirred on a magnetic stirrer for a set time.

[0011] In one embodiment of the present application, the set time is 30 min.

[0012] In one embodiment of the present application, it further comprises step S3: naturally cooling the molten salt waste solidification body.

[0013] In one embodiment of the present application, the mass ratio of the molten salt waste to the hydroxyapatite powder is 1: (10-15).

[0014] In one embodiment of the present application, in step S2, the temperature of the heating device is 100-200 DEG C.

[0015] In one embodiment of the present application, in step S2, the heating device is kept for 3-96 h.

[0016] In one embodiment of the present application, the magnetic stirrer comprises:

[0017] A rotating base capable of generating a continuously rotating magnetic field;

[0018] A container for placing on the rotating base;

[0019] A magnetic rotating part for placing at the bottom of the container, which can drive the magnetic rotating part to rotate when the rotating base works, and stir the mixture in the container;

[0020] A first telescopic element located directly above the container, which has a first telescopic rod, and the end of the first telescopic rod has a magnet;

[0021] The isolation cover is sleeved at the end of the first telescopic rod, and has a conical body with a small lower end and a large upper end. A tapered groove is formed on the lower end surface of the isolation cover, and the magnetic rotating part can be at least partially embedded in the tapered groove.

[0022] The second telescopic element is fixed on the first telescopic rod and has a second telescopic rod connected with the upper end of the isolation cover. The second telescopic element can drive the isolation cover to move up and down relative to the first telescopic rod, so that the bottom surface of the isolation cover approaches or is away from the magnet at the end of the first telescopic rod.

[0023] The lower end of the body is small, and the upper end is large, and the design of the tapered groove is combined. When the isolation cover is away from the mixture, a large amount of mixture will quickly fall into the container.

[0024] Compared with the traditional stirring paddle, the magnetic stirrer can effectively reduce the contact between the stirring device and the mixture. However, after the mixing is completed, the mixture needs to be transferred. At this time, the magnetic rotating part needs to be taken out of the container first. The first telescopic element, the second telescopic element, the isolation cover and the magnet can be used to automatically take out and put the magnetic part into the container.

[0025] One working process of the magnetic stirring device for putting the magnetic rotating part into the container:

[0026] In the initial state, the second telescopic element is retracted, and the bottom surface of the isolation cover approaches the magnet at the end of the first telescopic rod. Although the magnet is separated by the isolation cover, the magnet can firmly attract the magnetic rotating part in the tapered groove;

[0027] The first telescopic element works to drive the isolation cover and the second telescopic element to synchronously move downward by a set distance.

[0028] After the first telescopic element moves downward, the second telescopic element works to drive the isolation cover to move downward relative to the first telescopic rod, so that the bottom surface of the isolation cover is away from the magnet at the end of the first telescopic rod. At this time, the magnetic rotating part can automatically fall into the container from the tapered groove.

[0029] This putting method is not easy to make the mixture come out, and because of the existence of the isolation cover, the mixture will not enter the inside of the isolation cover.

[0030] One working process of the magnetic stirring device for taking the magnetic rotating part out of the container:

[0031] The first telescopic element works to drive the isolation cover and the second telescopic element to synchronously move downward to the bottom of the container.

[0032] Under the action of the magnet (preferably a strong magnet), the magnetic rotating part can be attracted and held in the tapered groove. As the first telescopic element moves upward, the magnetic rotating part moves upward together.

[0033] The mixture cannot enter the inside of the isolation cover due to the presence of the isolation cover.

[0034] In one embodiment of the present application, the first telescopic element is an electric push rod, and the second telescopic element is a pneumatic cylinder or an electric push rod.

[0035] The present application has the advantages that: apatite is a general term of calcium-containing phosphate minerals, and its chemical composition is Ca5(PO4)3(F, Cl, OH). Hydroxyapatite Ca5(PO4)3(OH)2 has good adsorption capacity, acid-base adjustability, ion exchange capacity and thermal stability. Because hydroxyl and calcium ions can be replaced by chloride and various metal ions respectively, the hydroxyapatite can be used to fix molten salt waste, and through the substitution reaction, the waste ions are introduced into the crystal lattice, that is, the hydroxyapatite can realize the effective solidification of the molten salt waste. The obtained molten salt waste solidification body has the advantages of large capacity and good chemical stability, and can effectively inhibit the pollution of molten salt waste to the ecological environment. The method has high use value and development potential. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a schematic view of a magnetic stirrer;

[0037] Figure 2 is an exploded view of a magnetic stirrer;

[0038] Figure 3 is a sectional view of an isolation cover.

[0039] The reference signs in the drawings are as follows:

[0040] 1, rotating base; 2, container; 3, magnetic rotating part; 4, first telescopic element; 41, first telescopic rod; 5, isolation cover; 51, body; 511, conical groove; 6, second telescopic element; 61, second telescopic rod. DETAILED DESCRIPTION

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0042] In the description of the present application, it should be noted that the terms "in", "out" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly used when the product of the application is used, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0043] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "set", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, it can be directly connected, or indirectly connected through an intermediate medium, it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0044] The present application will be described in detail below in conjunction with the drawings.

[0045] A method for hydrothermally preparing an apatite-based molten salt waste solidification body, comprising the following steps:

[0046] S1, weighing LiCl-KCl-NdCl simulated molten salt waste with a mass ratio of 1:1:1;

[0047] Mixing the molten salt waste and hydroxyapatite powder uniformly to obtain a mixture; the mass ratio of the molten salt waste and hydroxyapatite powder is 1:10.

[0048] S2, placing the mixture into a heating device for hydrothermal reaction, the temperature of the heating device is 180 DEG C, the heating time is 24h, and a molten salt waste solidification body is synthesized;

[0049] S3: naturally cooling the molten salt waste solidification body.

[0050] Apatite is a general term for a class of calcium-containing phosphate minerals, and its chemical composition is Ca5(PO4)3(F, Cl, OH). Among them, hydroxyapatite Ca5(PO4)3(OH)2 has good adsorption capacity, acid-base adjustment, ion exchange capacity and thermal stability. Because hydroxyl and calcium ions can be replaced by chloride and various metal ions respectively, the hydroxyapatite can be used to fix the molten salt waste, and through the substitution reaction, the waste ions are introduced into the crystal lattice, that is, the hydroxyapatite can realize the effective solidification of the molten salt waste. The obtained molten salt waste solidification body has the advantages of large inclusion capacity and good chemical stability, and can effectively inhibit the pollution of molten salt waste to the ecological environment. The method of the present application has high use value and development potential.

[0051] In this embodiment, in step S1, the molten salt waste and the hydroxyapatite powder are mixed in a liquid environment, using water as the medium, and stirred on a magnetic stirrer for 30 minutes.

[0052] As shown in FIGS. Figure 1 , 2 and 3, in this embodiment, the magnetic stirrer comprises:

[0053] a rotating base 1 capable of generating a constantly rotating magnetic field;

[0054] a container 2 for placement on the rotating base 1;

[0055] a magnetic rotating member 3 for placement at the bottom of the container 2, capable of being driven to rotate by the rotating base 1 when in operation, to stir the mixture in the container 2;

[0056] a first telescopic element 4 located directly above the container 2, having a first telescopic rod 41, the end of the first telescopic rod 41 having a magnet;

[0057] a shielding cover 5, the shielding cover 5 slidingly sheathed on the end of the first telescopic rod 41, the shielding cover 5 having a conical body 51, the lower end of the conical body 51 being smaller and the upper end being larger, the lower end face of the shielding cover 5 being formed with a conical groove 511, the magnetic rotating member being at least partially capable of being embedded in the conical groove 511;

[0058] a second telescopic element 6 fixed on the first telescopic rod 41, the second telescopic element 6 having a second telescopic rod 61, the second telescopic rod 61 being connected with the upper end of the shielding cover 5, the second telescopic element 6 being capable of driving the shielding cover 5 to move up and down relative to the first telescopic rod 41, so that the bottom face of the shielding cover 5 approaches or moves away from the magnet at the end of the first telescopic rod 41.

[0059] The lower end of the conical body 51 being smaller and the upper end being larger, in combination with the design of the conical groove 511, a large amount of mixture will quickly fall into the container 2 when the shielding cover 5 is away from the mixture.

[0060] Compared with the conventional stirring paddle, the magnetic stirrer can effectively reduce the contact between the stirring member and the mixture, but after the mixing is completed, the mixture needs to be transferred, at which time the magnetic rotating member 3 needs to be removed from the container 2. The first telescopic element 4, the second telescopic element 6, the shielding cover 5 and the magnet can be used to automatically remove and place the magnetic member into the container 2.

[0061] One working process of the magnetic stirring device for placing the magnetic rotating member 3:

[0062] In the initial state, the second telescopic element 6 is retracted, and the bottom surface of the isolation cover 5 is close to the magnet at the end of the first telescopic rod 41, and the magnet can firmly attract the magnetic rotating part 3 in the tapered groove 511, although through the isolation cover 5;

[0063] The first telescopic element 4 works to drive the isolation cover 5 and the second telescopic element 6 to synchronously move downward by a set distance;

[0064] After the first telescopic element 4 is moved downward, the second telescopic element 6 works to drive the isolation cover 5 to move downward relative to the first telescopic rod 41, so that the bottom surface of the isolation cover 5 is away from the magnet at the end of the first telescopic rod 41, and at this time the magnetic rotating part 3 can automatically fall from the tapered groove 511 to the container 2.

[0065] This putting-in mode is not easy to make the mixture come out, and because of the existence of the isolation cover 5, the mixture cannot enter the inside of the isolation cover 5.

[0066] A working process of the magnetic stirring device to take out the magnetic rotating part 3 from the container 2:

[0067] The first telescopic element 4 works to drive the isolation cover 5 and the second telescopic element 6 to synchronously move downward to the bottom of the container 2;

[0068] Under the action of the magnet (preferably a strong magnet), the magnetic rotating part 3 can be attracted in the tapered groove 511, and as the first telescopic element 4 moves upward, the magnetic rotating part 3 moves upward together.

[0069] This taking-out mode is not easy to make the mixture come out, and because of the existence of the isolation cover 5, the mixture cannot enter the inside of the isolation cover 5.

[0070] In the embodiment, the first telescopic element 4 is an electric push rod, and the second telescopic element 6 is a gas cylinder or an electric push rod.

[0071] The above only describes the preferred embodiments of the present application, and does not limit the patent protection range of the present application, and any equivalent structural transformation, direct or indirect application in other related technical fields, is also included in the protection range of the present application.

Claims

1. A magnetic stirrer, characterized in that, include: The rotating base can generate a continuously rotating magnetic field; Containers for placement on a rotating base; A magnetic rotating component is placed at the bottom of a container. When the rotating base is working, it can drive the magnetic rotating component to rotate, thereby stirring the mixture inside the container. A first telescopic element, located directly above the container, has a first telescopic rod, the end of which has a magnet; An isolation cover, wherein the isolation cover is slidably fitted over the end of the first telescopic rod, the isolation cover has a conical body, the lower end of the body is small and the upper end is large, and a conical groove is formed on the lower end surface of the isolation cover, and the magnetic rotating component can at least partially be embedded in the conical groove; The second telescopic element is fixed on the first telescopic rod. The second telescopic element has a second telescopic rod, which is connected to the upper end of the isolation cover. The second telescopic element can drive the isolation cover to move up and down relative to the first telescopic rod, so that the bottom surface of the isolation cover approaches or moves away from the magnet at the end of the first telescopic rod. The magnetic stirrer is used in a method for hydrothermal preparation of apatite-based molten salt waste solids, the method comprising the following steps: Step S1: Mix the molten salt waste and hydroxyapatite powder evenly to obtain a mixture. The mixing of molten salt waste and hydroxyapatite powder is carried out in a liquid environment with water as the medium and the mixture is stirred on a magnetic stirrer for a set time. Step S2: Place the mixture into a heating device for hydrothermal reaction to synthesize molten salt waste solidification.

2. The magnetic stirrer as described in claim 1, characterized in that, The set time is 30 minutes.

3. The magnetic stirrer as described in claim 1, characterized in that, The method further includes step S3: naturally cooling down the solidified molten salt waste.

4. The magnetic stirrer as described in claim 1, characterized in that, The mass ratio of the molten salt waste to the hydroxyapatite powder is 1:(10~15).

5. The magnetic stirrer as described in claim 1, characterized in that, In step S2, the temperature of the heating device is 100℃~200℃.

6. The magnetic stirrer as described in claim 1, characterized in that, In step S2, the heating device is maintained for 3 hours to 96 hours.

7. The magnetic stirrer as described in claim 1, characterized in that, The first telescopic element is an electric push rod, and the second telescopic element is a cylinder or an electric push rod.

Images