Thermal water chemical oxidation corrosion deposit precursor and its preparation method and use

Abstract

The present invention relates to the field of pressurized water reactor technology, and more specifically, to a thermal hydrochemical oxidation corrosion deposit precursor, its preparation method, and use. The thermal hydrochemical oxidation corrosion deposit precursor preparation method comprises: preparing an iron-nickel solution containing nickel and iron salts, wherein the molar ratio of nickel to iron is 1:(1.9-2.1); adding a TMAOH solution or aqueous ammonia to a flask, stirring, and heating to 80-100°C, wherein the molar ratio of TMAOH to NiCl₂ is greater than 30:1; stopping heating, and gradually adding the entire iron-nickel solution dropwise to the TMAOH solution while continuously stirring and neutralizing with concentrated hydrochloric acid to maintain the solution pH between 7 and 8; after standing for 5-10 hours, pouring off the clear liquid above the particles to preserve the iron-nickel hydroxide suspension. The resulting iron-nickel hydroxide suspension, as a precursor, meets the requirements of a deposition mechanism experiment for simulating thermal hydrochemical conditions to deposit oxidation corrosion products, and can be deposited to the thickness of real reactor fouling in a relatively short period of time.

Description

Technical Field

[0001] The present invention relates to the technical field of pressurized water reactors, and in particular to a thermal water chemical oxidation corrosion deposit precursor, a preparation method thereof, and uses thereof. Background Art

[0002] Pressurized water reactor (PWR) cores are subjected to the harsh environment of high temperature, high pressure, and high radioactivity for extended periods. The core's fuel performance is a key factor influencing reactor safety and economic viability. During nuclear reactor operation, the steam generator heat transfer tubes, which have the largest heat transfer area in the primary circuit, are continuously eroded and corroded by the high-pressure, subcooled coolant, resulting in accelerated corrosion and the formation of large quantities of oxidative corrosion products. Driven by subcooled boiling, metal ions and corrosion products in the primary circuit deposit on the surface of the fuel cladding above the core, forming a thin, loose, and porous scale layer. This oxidative corrosion deposit, known as CRUD (Chalk River Unidentified Deposit), forms on the fuel cladding surface.

[0003] The main component of the oxidation corrosion product deposition layer is nickel ferrite (NiFe2O4), and its porous morphology is composed of micron-scale "chimneys" and nanometer-scale "capillaries". The deposition of oxidation corrosion products will cause a series of safety problems. Generally speaking, there are two main hazards: on the one hand, when the oxidation corrosion product deposition layer reaches a certain thickness, it will reduce the heat transfer efficiency. The reduction in the heat transfer efficiency of the fuel rod surface will cause the fuel rod temperature to rise. In severe cases, it may cause local corrosion of the fuel rod or even local melting. On the other hand, the oxidation corrosion product deposition layer presents a loose porous structure, which has the effect of enhancing boiling. The enhancement of boiling in the deposition layer will cause the boron element to precipitate from the coolant and be adsorbed by the porous morphology of the deposition layer, resulting in an uneven distribution of boron on the axial surface of the fuel rod. 10 Boron has a significant neutron absorption capacity, so the boron adsorption phenomenon in the oxidation corrosion product deposition layer will cause the power distribution to be distorted toward the bottom of the reactor, triggering the core power drift phenomenon, namely scale-induced power drift. Studies have shown that the local power variation caused by scale-induced power drift can be as high as 15% or more. Scale-induced power drift will not only cause the nuclear reactor to reduce power or even emergency shutdown, reducing the neutron economy of the nuclear reactor, but also affect the residual reactivity and shutdown margin of the core, and even cause the cladding to fail, threatening the integrity of the nuclear reactor safety barrier.

[0004] Because the deposition of oxidative corrosion products on the fuel cladding surface is a lengthy solute migration process, requiring precise control of water chemistry conditions, including the concentrations of Fe, Ni, O, and H ions, as well as prolonged heat transfer, mass transfer, and deposition, assessing the impact of core oxidative corrosion product deposition on core safety requires significant time and effort. However, by modifying the coolant's iron- and nickel-containing precursors under laboratory conditions, the entire deposition process can be greatly accelerated. Therefore, the ability to conveniently and rapidly prepare water chemistry precursors to accelerate the deposition of oxidative corrosion products under simulated thermal water chemistry is crucial for analyzing their impact on flow heat transfer, core neutron physics, and reactor safety.

[0005] Currently, there are a variety of precursors used under laboratory conditions. Solid precursors mainly include dirt components nickel ferrite NiFe2O4 particles, iron oxide Fe2O3 particles, and nickel oxide NiO particles. Soluble precursors mainly include iron chloride FeCl3 and nickel chloride NiCl2. However, these precursors cannot represent the existence form of oxidative corrosion products in the reactor and are difficult to meet the requirements of deposition mechanism experiments. Summary of the Invention

[0006] The purpose of the present invention is to provide a thermal water chemical oxidation corrosion deposit precursor and its preparation method and use, so as to alleviate the technical problem that the precursor of the existing technology that simulates the thermal water chemical conditions oxidation corrosion deposit is difficult to meet the requirements of the deposition mechanism experiment.

[0007] The present invention provides a method for preparing a thermal water chemical oxidation corrosion deposit precursor, comprising:

[0008] Preparing an iron-nickel solution containing a nickel salt and an iron salt, wherein the nickel salt includes one or more of NiCl2, NiSO4, and Ni(NO3)2, the iron salt includes one or more of FeNH4(SO4)2, Fe2(SO4)3, Fe(NO3)3, and FeCl3, and the molar ratio of the nickel element in the nickel salt to the iron element in the iron salt is in the range of 1:(1.9-2.1), preferably 1:2;

[0009] Add TMAOH solution or ammonia solution to the flask, stir and heat to 80-100°C, wherein the molar ratio of TMAOH or ammonia solution to NiCl2 is greater than 30:1, preferably 50:1;

[0010] Stop heating, gradually add all the iron-nickel solution dropwise to the TMAOH solution or ammonia water, continue stirring and add concentrated hydrochloric acid to neutralize, so that the pH of the solution is maintained between 7 and 8;

[0011] After standing for 5 to 10 hours, pour out the clear liquid above the particles;

[0012] Deionized water was added and mixed, and after standing for 5 to 10 hours, the clear liquid above the particles was poured out again, and the process was repeated several times to save the iron-nickel hydroxide suspension.

[0013] Preferably, as an implementable embodiment, the preparation method further comprises:

[0014] Add EDTA and deionized water to a beaker, stir the solution and gradually add ammonia until all the EDTA is dissolved;

[0015] Add iron powder and wait until the iron powder is completely dissolved to prepare a soluble iron solution;

[0016] The mass ratio of the added iron powder to EDTA is 25:(135-160), preferably 25:150.

[0017] Preferably, as an implementable embodiment, the preparation method further comprises:

[0018] Add EDTA, deionized water and Ni(OH)2 to a beaker, wherein the mass ratio of Ni(OH)2 to EDTA is 41:(135-160), preferably 41:150;

[0019] Stir the solution for 10 to 14 hours;

[0020] Aqueous ammonia was gradually added until all the EDTA was dissolved, producing a soluble nickel solution.

[0021] Preferably, as an embodiment, in the step of stirring and heating to 80-100° C., the stirring rate is 800-1000 rpm.

[0022] Preferably, as an implementation method, in the iron-nickel solution, the concentration of NiCl2 is 0.01-0.1 mol / L, preferably 0.02 mol / L; the concentration of FeNH4(SO4)2 is 0.02-0.2 mol / L, preferably 0.04 mol / L.

[0023] Preferably, as an implementable embodiment, the volume ratio of the TMAOH solution to the iron-nickel solution is (180-1795):1000, preferably 359:1000.

[0024] Preferably, as an implementable embodiment, before the step of adding iron powder, the preparation method further comprises: heating the solution to 94-96°C.

[0025] Preferably, as an implementation method, before the step of stirring the solution for 10 to 14 hours, the preparation method further comprises: heating the solution to 95 to 100°C.

[0026] The thermal water chemical oxidation corrosion deposit precursor provided by the present invention is prepared by the above preparation method.

[0027] The present invention also provides a use of the thermal water chemical oxidation corrosion deposit precursor in a deposition mechanism experiment of depositing oxidation corrosion products under simulated thermal water chemical conditions.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] Because the molar ratio of the nickel element in the nickel salt to the iron element in the iron salt is in the range of 1: (1.9 to 2.1), and the molar ratio of TMAOH (or ammonia) to NiCl2 is greater than 30: 1, TMAOH itself is in excess. After the iron-nickel solution is completely added to the TMAOH solution, it is ensured that the nickel salt and the iron salt can react completely, so that the anions in the iron salt and the nickel salt can be completely dissolved in the solution. Due to the heat generated by the reaction of the iron-nickel solution with the TMAOH solution or ammonia, in the process of adding the iron-nickel solution dropwise to the TMAOH solution (or ammonia), a gradual dropwise addition method is selected and the solution is stirred. During the dropwise addition process, the solution can be naturally cooled to prevent the solution temperature from being too high, and the particle size of the suspended matter can be controlled, reducing the particles agglomerated and attached to the inner wall, reducing waste, and allowing the granular product to be present in the iron-nickel hydroxide suspension.

[0030] One or more of NiCl2, NiSO4 and Ni(NO3)2 are selected as nickel salts in the iron-nickel solution, and one or more of FeNH4(SO4)2, Fe2(SO4)3, Fe(NO3)3 and FeCl3 are selected as iron salts in the iron-nickel solution. After the reaction of the iron-nickel solution with TMAOH is completed, chloride ions, sulfate ions, nitrate ions and ammonia ions are all dissolved in water. After several sedimentation and separation, the chloride ions, sulfate ions, nitrate ions or ammonia ions originally present in the iron salt and the nickel salt can be poured out with the supernatant several times. Therefore, four ions of Ni, Fe, O and H are mainly present in the finally preserved iron-nickel oxide suspension. After the obtained iron-nickel hydroxide suspension is filtered, dehydrated and dried, XRD (x-rays, X-ray) detection shows that it has an amorphous structure, and XPS (X-ray photoelectron spectroscopy) shows that it has an amorphous structure. X-ray photoelectron spectroscopy (X-ray photoelectron spectroscopy) detection shows that its iron-nickel element ratio is close to the preset 2:1. Therefore, the iron-nickel hydroxide suspension can represent the existence form of oxidative corrosion products in the reactor. Using it as a precursor meets the requirements of the deposition mechanism experiment of oxidative corrosion products deposited under simulated thermal water chemical conditions, and can be deposited to the thickness of dirt in a real reactor in a relatively short time. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0032] An embodiment of the present invention provides a method for preparing a thermal water chemical oxidation corrosion deposit precursor, which includes:

[0033] An iron-nickel solution containing nickel salt and iron salt is prepared, wherein the nickel salt includes one or more of NiCl2, NiSO4 and Ni(NO3)2, the iron salt includes one or more of FeNH4(SO4)2, Fe2(SO4)3, Fe(NO3)3 and FeCl3, and the molar ratio of the nickel element in the nickel salt to the iron element in the iron salt is in the range of 1:(1.9-2.1), preferably 1:(1.95-2.05), and more preferably 1:2.

[0034] Add tetramethylammonium hydroxide (TMAOH) solution or ammonia water into the flask, stir and heat to 80-100° C., wherein the molar ratio of TMAOH or ammonia water to NiCl 2 is greater than 30:1, preferably greater than 40:1, and more preferably 50:1.

[0035] Stop heating and gradually add the entire iron-nickel solution dropwise to the TMAOH solution or ammonia solution while continuing to stir and neutralize with concentrated hydrochloric acid to maintain the solution pH between 7 and 8. The stirring rate is preferably 800 to 1000 rpm, which can limit the particle size in the suspension to an appropriate range.

[0036] After standing for 5 to 10 hours, pour out the clear liquid above the particles. During standing, the iron-nickel hydroxide may agglomerate and settle to form an upper clear liquid and a lower suspended liquid. Specifically, the clear appearance of the upper clear liquid and the lower suspended liquid can be used as the condition for the completion of standing.

[0037] Deionized water was added and mixed, and after standing for 5 to 10 hours, the clear liquid above the particles was poured out again, and the process was repeated several times to save the iron-nickel hydroxide suspension.

[0038] It should be noted that, because the molar ratio of the nickel element in the nickel salt to the iron element in the iron salt is in the range of 1: (1.9 to 2.1), the molar ratio of TMAOH (or ammonia) to NiCl2 is greater than 30: 1, so TMAOH itself is excessive. After the iron-nickel solution is all added to the TMAOH solution, it can be ensured that the nickel salt and the iron salt can react completely, so that the anions in the iron salt and the nickel salt can be completely dissolved in the solution. Due to the heat generated by the reaction of the iron-nickel solution with the TMAOH solution or ammonia, in the process of adding the iron-nickel solution dropwise to the TMAOH solution (or ammonia), a gradual dropwise addition method is selected and the solution is stirred. During the dropwise addition process, the solution can be naturally cooled to prevent the solution temperature from being too high, and the particle size of the suspended matter can be controlled, the particles attached to the inner wall are reduced, waste is reduced, and the particle product can be present in the iron-nickel hydroxide suspension.

[0039] One or more of NiCl2, NiSO4 and Ni(NO3)2 are selected as nickel salts in the iron-nickel solution, and one or more of FeNH4(SO4)2, Fe2(SO4)3, Fe(NO3)3 and FeCl3 are selected as iron salts in the iron-nickel solution. After the reaction of the iron-nickel solution with TMAOH is completed, chloride ions, sulfate ions, nitrate ions and ammonia ions are all dissolved in water. After several sedimentation and separation, the chloride ions, sulfate ions, nitrate ions or ammonia ions originally present in the iron salt and the nickel salt can be poured out with the supernatant several times. Therefore, four ions of Ni, Fe, O and H are mainly present in the finally preserved iron-nickel oxide suspension. After the obtained iron-nickel hydroxide suspension is filtered, dehydrated and dried, XRD (x-rays, X-ray) detection shows that it has an amorphous structure, and XPS (X-ray photoelectron spectroscopy) shows that it has an amorphous structure. X-ray photoelectron spectroscopy (X-ray photoelectron spectroscopy) detection shows that its iron-nickel element ratio is close to the preset 2:1. Therefore, the iron-nickel hydroxide suspension can represent the existence form of oxidative corrosion products in the reactor. Using it as a precursor meets the requirements of the deposition mechanism experiment of oxidative corrosion products deposited under simulated thermal water chemical conditions, and can be deposited to the thickness of dirt in a real reactor in a relatively short time.

[0040] The iron and nickel concentrations in the suspension can be measured by ICP (Inductively Coupled Plasma) to serve as a reference for the experimental injection volume.

[0041] In the iron-nickel solution, the concentration of NiCl2 is 0.01~0.1mol / L, preferably 0.012~0.08mol / L, more preferably 0.014~0.06mol / L, and further preferably 0.02mol / L; the concentration of FeNH4(SO4)2 is 0.02~0.2mol / L, preferably 0.024~0.16mol / L, more preferably 0.028~0.12mol / L, and further preferably 0.04mol / L.

[0042] Under these conditions, the volume ratio of the added TMAOH solution to the iron-nickel solution is set to (180-1795):1000, preferably (200-1600):1000, more preferably (300-1400):1000, and further preferably 359:1000. A TMAOH solution with a concentration of 25% can be used.

[0043] The above-mentioned iron-nickel solution can be prepared by using nickel chloride hexahydrate NiCl2·6H2O and ammonium iron sulfate dodecahydrate FeNH4(SO4)2·12H2O.

[0044] The above preparation method may also include a method for preparing a soluble iron solution: adding ethylenediaminetetraacetic acid (EDTA) and deionized water to a beaker, stirring the solution and gradually adding ammonia water until the EDTA is completely dissolved, and the pH of the resulting solution is close to 7; adding iron powder, and waiting for the iron powder to be completely dissolved to prepare a soluble iron solution; wherein the mass ratio of the added iron powder to EDTA is 25: (135-160), preferably 8: (46-50), and more preferably 25:150.

[0045] The above-described method for preparing a soluble iron solution can be used to prepare a soluble iron solution. When the iron content in the iron-nickel hydroxide suspension is low, the prepared soluble iron solution can be used to supplement the iron alone. Specifically, a mixture of the prepared soluble iron solution and the iron-nickel hydroxide suspension can be used as a precursor to better meet the requirements of deposition mechanism experiments for depositing oxidative corrosion products under simulated thermal hydrochemical conditions. The iron concentration in the soluble iron solution can be measured by ICP to serve as a reference for the experimental addition volume.

[0046] It should be noted that after the iron powder is added, the reaction continues for about 48 hours until the iron powder is substantially completely dissolved. At this time, it can be observed whether the iron powder is completely dissolved. The iron powder is preferably ultrafine iron powder.

[0047] In the above-mentioned method for preparing the soluble iron solution, the solution may be heated to 94-96° C. (close to boiling point) before adding the iron powder to accelerate the reaction and dissolution process and improve the preparation efficiency.

[0048] The above preparation method may also include a method for preparing a soluble nickel solution: adding EDTA, deionized water and Ni(OH)2 into a beaker, wherein the mass ratio of Ni(OH)2 to EDTA is 41:(135-160), preferably 14:(50-53), and further preferably 41:150; stirring the solution for 10-14 hours; gradually adding ammonia water until all the EDTA is dissolved and the pH of the obtained solution is close to 7, thereby obtaining a soluble nickel solution.

[0049] The above-described method for preparing a soluble nickel solution can be used to prepare a soluble nickel solution. When the nickel content in the iron-nickel hydroxide suspension is low, the prepared soluble nickel solution can be used to supplement the nickel content. Specifically, a mixture of the prepared soluble nickel solution and the iron-nickel hydroxide suspension can be used as a precursor to better meet the requirements of deposition mechanism experiments for depositing oxidative corrosion products under simulated thermal hydrochemical conditions. The nickel concentration in the soluble nickel solution can be measured by ICP to serve as a reference for the experimental addition volume.

[0050] Specifically, the filling amounts of the iron-nickel hydroxide suspension, the soluble iron solution and the soluble nickel solution can be calculated based on the experimental requirements, the iron concentration and the nickel concentration in the iron-nickel hydroxide suspension, the iron concentration in the soluble iron solution and the nickel concentration in the soluble nickel solution.

[0051] In the above-mentioned method for preparing a soluble nickel solution, before stirring the solution for 10 to 14 hours, the solution may be heated to 95 to 100° C. (close to boiling point) to accelerate the reaction and dissolution process and improve the preparation efficiency.

[0052] This embodiment also provides a thermal water chemical oxidation corrosion deposit precursor prepared by the above-mentioned thermal water chemical oxidation corrosion deposit precursor preparation method.

[0053] This embodiment also provides a use of a thermal water chemical oxidation corrosion deposit precursor in a deposition mechanism experiment of depositing oxidation corrosion products under simulated thermal water chemical conditions.

[0054] The thermal water chemical oxidation corrosion deposit precursor provided by the embodiments of the present invention and its preparation method and use have the following beneficial effects:

[0055] One or more of NiCl2, NiSO4 and Ni(NO3)2 are selected as nickel salts in the iron-nickel solution, and one or more of FeNH4(SO4)2, Fe2(SO4)3, Fe(NO3)3 and FeCl3 are selected as iron salts in the iron-nickel solution. After the reaction of the iron-nickel solution with TMAOH is completed, chloride ions, sulfate ions, nitrate ions and ammonia ions are all dissolved in water. After several sedimentation separations, the chloride ions, sulfate ions, nitrate ions or ammonia ions originally present in the iron salt and nickel salt can be poured out with the supernatant several times. Therefore, the final preserved iron-nickel oxide suspension mainly contains four ions: Ni, Fe, O and H, and the iron-nickel element ratio is close to the preset 2:1. Therefore, the iron-nickel hydroxide suspension can represent the existence form of oxidative corrosion products in the reactor. Using it as a precursor meets the requirements of the deposition mechanism experiment of simulating thermal water chemical conditions to deposit oxidative corrosion products, and can achieve the thickness of dirt deposited in a real reactor within 2 weeks.

[0056] To further illustrate the present invention, the thermal water chemical oxidation corrosion deposit precursor provided by the present invention, its preparation method and use are described in more detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the present invention.

[0057] Example 1:

[0058] The preparation method of iron nickel hydroxide suspension is as follows:

[0059] ① Prepare 1L of iron-nickel solution containing 0.02mol / L NiCl2 and 0.04mol / L FeNH4(SO4)2;

[0060] ② Add 359 mL of 25% TMAOH solution to a large flask, stir at high speed and heat to 80-100°C;

[0061] ③ Stop heating and add the prepared iron-nickel solution dropwise to the TMAOH solution to remove the salt in the solution. Stir the solution and neutralize it with concentrated hydrochloric acid to a pH between 7 and 8.

[0062] ④ Place the solution in a large beaker and allow it to aggregate and settle for 5 hours. Pour out the solution above the particles, add deionized water to the precipitate and mix thoroughly.

[0063] ⑤ Repeat the precipitation step several times and save the suspension without the supernatant.

[0064] The soluble iron solution is prepared as follows:

[0065] ① Add 150g solid EDTA and 700g deionized water to a beaker, stir the solution and gradually add ammonia until all the EDTA is dissolved and the pH of the solution is close to 7;

[0066] ② Add deionized water to the solution until the total mass of the solution is 1000g;

[0067] ③Heat the solution to 95℃, close to the boiling point;

[0068] ④ Add 25g of ultrafine iron powder and continue the reaction for 48 hours until the iron powder is completely dissolved.

[0069] The soluble nickel solution is prepared as follows:

[0070] ① Add 150g solid EDTA and 700g deionized water to a beaker, then add 41g Ni(OH)2 powder;

[0071] ②Heat the solution to a temperature close to the boiling point of 95-100°C;

[0072] ③ Stir the solution for 12 hours;

[0073] ④ Gradually add ammonia water until all the EDTA is dissolved and the pH of the resulting solution is close to 7;

[0074] ⑤ Add deionized water to the solution until the total mass of the solution is 1000g.

[0075] Test results:

[0076] After filtering, dehydrating, and drying the iron-nickel hydroxide, XRD analysis revealed an amorphous structure, and XPS analysis indicated a nickel-iron ratio of 1:2. Inductively coupled plasma (ICP) measurements revealed an iron concentration of 19.100 g / L and a nickel content of 10.030 g / L in the iron-nickel hydroxide suspension; the soluble iron solution concentration was 23.110 g / L; and the soluble nickel solution concentration was 24.330 g / L.

[0077] Example 2:

[0078] The process for preparing iron-nickel hydroxide suspension is as follows:

[0079] ① Prepare 1L of iron-nickel solution containing 0.01mol / L NiCl2 and 0.02mol / L FeNH4(SO4)2;

[0080] ② Add 180 mL of 25% TMAOH solution to a large flask, stir at high speed and heat to 80-100°C;

[0081] ③ Stop heating and add the prepared iron-nickel solution dropwise to the TMAOH solution to remove the salt in the solution. Stir the solution and neutralize it with concentrated hydrochloric acid to a pH between 7 and 8.

[0082] ④ Place the solution in a large beaker and allow it to aggregate and settle for 5 hours. Pour out the solution above the particles, add deionized water to the precipitate and mix thoroughly.

[0083] ⑤ Repeat the precipitation step several times and save the suspension without the supernatant.

[0084] The process for preparing soluble iron solution is as follows:

[0085] ① Add 50g solid EDTA and 900g deionized water to a beaker, stir the solution and gradually add ammonia until all the EDTA is dissolved and the pH of the solution is close to 7;

[0086] ② Add deionized water to the solution until the total mass of the solution is 1000g;

[0087] ③Heat the solution to 95℃, close to the boiling point;

[0088] ④ Add 8g of ultrafine iron powder and continue the reaction for 48 hours until the iron powder is completely dissolved.

[0089] The process for preparing soluble nickel solution is as follows:

[0090] ① Add 50g solid EDTA and 900g deionized water to a beaker, then add 14g Ni(OH)2 powder;

[0091] ②Heat the solution to a temperature close to the boiling point of 95-100°C;

[0092] ③ Stir the solution for 12 hours;

[0093] ④ Gradually add ammonia water until all the EDTA is dissolved and the pH of the resulting solution is close to 7;

[0094] ⑤ Add deionized water to the solution until the total mass of the solution is 1000g.

[0095] Test results:

[0096] After filtration, dehydration, and drying, XRD analysis revealed an amorphous structure, and XPS analysis revealed a nickel-iron ratio of 249:500. Inductively coupled plasma spectroscopy (ICP) measurements revealed an iron concentration of 19.08 g / L and a nickel content of 10.06 g / L in the suspension. The concentrations of the soluble iron solution were 7.710 g / L and 8.113 g / L, respectively.

[0097] Example 3:

[0098] The preparation method of iron nickel hydroxide suspension is as follows:

[0099] ① Prepare 1L of iron-nickel solution containing 0.02mol / L NiCl2 and 0.04mol / L FeNH4(SO4)2;

[0100] ② Add 359 mL of 25% TMAOH solution to a large flask, stir at high speed and heat to 80-100°C;

[0101] ③ Stop heating and add the prepared iron-nickel solution dropwise to the TMAOH solution to remove the salt in the solution. Stir the solution and neutralize it with concentrated hydrochloric acid to a pH between 7 and 8.

[0102] ④ Place the solution in a large beaker and allow it to aggregate and settle for 5 hours. Pour out the solution above the particles, add deionized water to the precipitate and mix thoroughly.

[0103] ⑤ Repeat the precipitation step several times and save the suspension without the supernatant.

[0104] The soluble iron solution is prepared as follows:

[0105] ① Add 300g solid EDTA and 350g deionized water to a beaker, stir the solution and gradually add ammonia until all the EDTA is dissolved and the pH of the solution is close to 7;

[0106] ② Add deionized water to the solution until the total mass of the solution is 1000g;

[0107] ③Heat the solution to 95℃, close to the boiling point;

[0108] ④ Add 50g of ultrafine iron powder and continue the reaction for 48 hours until the iron powder is completely dissolved.

[0109] The soluble nickel solution is prepared as follows:

[0110] ① Add 300g solid EDTA and 350g deionized water to a beaker, and then add 82g nickel hydroxide powder;

[0111] ②Heat the solution to a temperature close to the boiling point of 95-100°C;

[0112] ③ Stir the solution for 12 hours;

[0113] ④ Gradually add ammonia water until all the EDTA is dissolved and the pH of the resulting solution is close to 7;

[0114] ⑤ Add deionized water to the solution until the total mass of the solution is 1000g.

[0115] Test results:

[0116] After filtering, dehydrating, and drying the iron-nickel hydroxide, XRD analysis revealed an amorphous structure, and XPS analysis revealed a nickel-iron ratio of 1:2. ICP measurements revealed an iron concentration of 19.100 g / L and a nickel content of 10.030 g / L in the suspension; the concentration of the soluble iron solution was 46.253 g / L; and the concentration of the soluble nickel solution was 48.652 g / L.

[0117] It is recommended to use embodiment 1.

[0118] Finally, it should be noted that, in this document, terms such as "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article, or apparatus.

[0119] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to the embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a thermal water chemical oxidation corrosion deposit precursor, characterized in that: include: Preparing an iron-nickel solution containing a nickel salt and an iron salt, wherein the nickel salt includes NiCl2, the iron salt includes one or more of FeNH4(SO4)2, Fe2(SO4)3, Fe(NO3)3, and FeCl3, and the molar ratio of the nickel element in the nickel salt to the iron element in the iron salt is in the range of 1:(1.9-2.1); Add TMAOH solution or ammonia water to the flask, stir and heat to 80-100°C, wherein the molar ratio of TMAOH or ammonia water to NiCl2 is greater than 30:1; Stop heating, gradually add all the iron-nickel solution dropwise to the TMAOH solution or ammonia water, continue stirring and add concentrated hydrochloric acid to neutralize, so that the pH of the solution is maintained between 7 and 8; After standing for 5 to 10 hours, pour out the clear liquid above the particles; Deionized water was added and mixed, and after standing for 5 to 10 hours, the clear liquid above the particles was poured out again, and the process was repeated several times to save the iron-nickel hydroxide suspension.

2. The method for preparing a thermal water chemical oxidation corrosion deposit precursor according to claim 1, characterized in that: The preparation method further comprises: Add EDTA and deionized water to a beaker, stir the solution and gradually add ammonia until all the EDTA is dissolved; Add iron powder and wait until the iron powder is completely dissolved to prepare a soluble iron solution; The mass ratio of the added iron powder to EDTA is 25:(135-160); When the iron content in the iron-nickel hydroxide suspension is relatively low, the prepared soluble iron solution can be used to supplement the iron alone, that is, a mixture of the prepared soluble iron solution and the iron-nickel hydroxide suspension can be used as a precursor.

3. The method for preparing a thermal water chemical oxidation corrosion deposit precursor according to claim 1 or 2, characterized in that: The preparation method further comprises: Add EDTA, deionized water, and Ni(OH)2 into a beaker, where the mass ratio of Ni(OH)2 to EDTA is 41:(135-160); Stir the solution for 10 to 14 hours; Aqueous ammonia was gradually added until all the EDTA was dissolved to prepare a soluble nickel solution; When the nickel content in the iron-nickel hydroxide suspension is relatively low, the prepared soluble nickel solution can be used to supplement the nickel element alone, that is, a mixture of the prepared soluble nickel solution and the iron-nickel hydroxide suspension can be used as a precursor.

4. The method for preparing a thermal water chemical oxidation corrosion deposit precursor according to claim 1 or 2, characterized in that: In the step of stirring and heating to 80-100° C., the stirring rate is 800-1000 rpm.

5. The method for preparing a thermal water chemical oxidation corrosion deposit precursor according to claim 1 or 2, characterized in that: In the iron-nickel solution, the concentration of NiCl2 is 0.01-0.1 mol / L; the concentration of FeNH4(SO4)2 is 0.02-0.2 mol / L.

6. The method for preparing a thermal water chemical oxidation corrosion deposit precursor according to claim 1 or 2, characterized in that: The volume ratio of the TMAOH solution to the iron-nickel solution is (180-1795):1000.

7. The method for preparing a thermal water chemical oxidation corrosion deposit precursor according to claim 2, characterized in that: Before the step of adding iron powder, the preparation method further comprises: heating the solution to 94-96°C.

8. The method for preparing a thermal water chemical oxidation corrosion deposit precursor according to claim 3, characterized in that: Before the step of stirring the solution for 10 to 14 hours, the preparation method further comprises: heating the solution to 95 to 100°C.

9. A thermal water chemical oxidation corrosion deposit precursor, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the thermal water chemical oxidation corrosion deposit precursor according to claim 9 in a deposition mechanism experiment of depositing oxidation corrosion products under simulated thermal water chemical conditions.