A ferronickel powder, a preparation method and application thereof

Abstract

The application discloses a nickel-iron powder and a preparation method and application thereof, and relates to the technical field of atomized nickel-iron powder. The nickel-iron powder provided by the application satisfies the variance S of the mass ratio of iron to nickel 2 The nickel-iron elements are in a non-uniform state, the content of nickel in a solution can be quickly increased during subsequent wet acid leaching, and downstream hydrometallurgy is facilitated.

Description

Technical Field

[0001] This invention relates to the field of atomized nickel-iron powder technology, and more specifically, to a nickel-iron powder, its preparation method, and its application. Background Technology

[0002] Nickel-iron alloy powder has crucial applications in the production of stainless steel, special alloy steel, soft magnetic devices, 3D printing (additive manufacturing), and cemented carbide binder phases. In these applications, the negative impact of uneven nickel-iron element composition is amplified; slight unevenness can lead to performance fluctuations, while severe unevenness can directly cause product scrap. Therefore, the uniformity of nickel-iron element distribution is extremely critical in these fields, and higher uniformity is more beneficial for performance improvement.

[0003] However, in the preparation of solutions containing nickel and iron elements using hydrometallurgy, a more uniform element distribution actually leads to a lower leaching rate. Furthermore, because hydrometallurgy is a continuous acid leaching process, the nickel and iron powder does not completely dissolve; a more uniform distribution of nickel and iron elements actually reduces the leaching rate of high-value nickel. This is mainly due to the following reasons: (1) The nickel-iron powder with uniform elements has no Ni / Fe phase inside, which makes it impossible to fully construct the galvanic cell reaction, resulting in a low dissolution rate.

[0004] (2) Iron is more reactive than nickel. The more uniform the elemental distribution, the more effectively iron can inhibit the dissolution of nickel. If uneven distribution forms a Ni-rich phase, nickel will react directly with acid and dissolve, thereby increasing the nickel content in the wet leaching solution. This is beneficial for the collection of high-value nickel. The lower the nickel content in the remaining nickel-iron powder after incomplete reaction in wet acid leaching, the better. Since the remaining nickel-iron powder after incomplete reaction generally cannot meet the requirements for re-wet leaching, the lower its nickel content, the higher the nickel content in the solution, and the higher the value generated.

[0005] Therefore, there is an urgent need to develop nickel-iron powder with a nickel and iron element distribution that can improve the leaching efficiency of nickel-iron powder during wet leaching.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a nickel-iron powder, its preparation method, and its application, aiming to provide a nickel-iron powder with an appropriate distribution of nickel and iron elements, which can be rapidly leached during wet leaching.

[0008] This invention is implemented as follows: In a first aspect, the present invention provides a nickel-iron powder. By testing the nickel-iron powder using an energy-dispersive X-ray spectroscopy (EDS) instrument, eight points are randomly selected from 3-5 particles. The iron-nickel mass ratios at these eight points are P1 to P8, and the iron-nickel mass ratio at any point from P1 to P8 is P... i The expression is: P i=Y i / X i ; Among them, X i Y represents the mass fraction of nickel at that point; i This indicates the mass fraction of iron at that point; The average iron-nickel mass ratio P0 = (P1 + P2 + P3 + P4 + P5 + P6 + P7 + P8) / 8; The variance S of the iron-nickel mass ratio 2 =[(P1-P0) 2 +(P2-P0) 2 +(P3-P0) 2 +(P4-P0) 2 +(P5-P0) 2 +(P6-P0) 2 +(P7-P0) 2 +(P8-P0) 2 ] / 8; S 2 ≥0.1.

[0009] In an optional implementation, the step size L = (P max -P min ) / 8, P max P represents the maximum value among P1 to P8. min This represents the minimum value among P1 to P8; Dispersion K=S 2 / L 2 K ranges from 6 to 10.

[0010] And / or, the mass fraction of nickel is 5%-90%, and the mass fraction of iron is 10%-95%; And / or, the particle size of the nickel-iron powder is 70μm-180μm.

[0011] In a second aspect, the present invention provides a method for preparing nickel-iron powder according to any of the foregoing embodiments, comprising: subjecting the molten nickel-iron to static treatment to obtain a chromatographic melt; The chromatographic melt and surfactant solution enter the atomization system and are sprayed out using a coaxial annular slit nozzle. The high-pressure fluid formed by the surfactant solution is sprayed out through the annular slit, and the chromatographic melt is sprayed out through the inner hole to obtain a slurry. The pressure of the high-pressure fluid is 1MPa-5MPa and the temperature is 40℃-60℃. Nickel-iron powder is obtained by post-processing the slurry.

[0012] In an optional embodiment, the settling process includes: pouring molten nickel-iron into an intermediate ladle, controlling the temperature of the intermediate ladle at 1600℃-1800℃, and settling for 20min-30min.

[0013] In an optional embodiment, the surfactant in the surfactant solution is selected from at least one of hexadecyltrimethylammonium chloride, dodecyldimethylbenzylammonium chloride, AEO-9, and AEO-10; And / or, the surfactant solution is an aqueous solution with a mass fraction of 0.05%-0.20%.

[0014] In an optional embodiment, the diameter of the inner hole is 1.0mm-1.5mm, and the width of the annular slit is 0.2mm-0.5mm; And / or, the high-pressure fluid forms an impact angle of 40°-50° with the melt flow; And / or, the flow rate of the chromatographic melt is 0.5 kg / s-1.0 kg / s, and the flow rate of the high-pressure fluid is 80 m / s-150 m / s.

[0015] In an optional embodiment, the preparation process of molten nickel includes: adding raw materials that meet the target nickel-iron ratio into a furnace and smelting them at a temperature of 1600℃-1800℃.

[0016] In an optional implementation, the post-processing includes: sequentially subjecting the slurry to a first magnetic separation, washing, a second magnetic separation, dehydration, and drying.

[0017] Thirdly, the present invention provides the application of any of the nickel-iron powders in the foregoing embodiments or the nickel-iron powders prepared by any of the preparation methods in the foregoing embodiments in hydrometallurgy. One application is acid leaching of nickel-iron powder.

[0018] The present invention has the following beneficial effects: the variance S of the iron-nickel mass ratio in the nickel-iron powder provided by the present invention 2 ≥0.1 indicates a heterogeneous distribution of nickel and iron elements, which can rapidly increase the nickel content in the solution during subsequent wet acid leaching, thus benefiting downstream hydrometallurgical applications. If the variance S of the iron-nickel mass ratio... 2 If the value is too small, the leaching rate of nickel will decrease significantly. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The image shows the SEM image of the nickel-iron powder provided in Example 3. Three different points are marked in the image, corresponding to spectrum 94, spectrum 95 and spectrum 96 respectively. Figure 2 for Figure 1 EDS spectrum of one point (spectral graph 94); Figure 3 for Figure 1 EDS spectrum of one point (spectral graph 95); Figure 4 for Figure 1 EDS spectrum of one point (spectral graph 96); Figure 5 The image shows the SEM image of the nickel-iron powder provided in Example 3. Two different points are marked in the image, corresponding to spectrum 97 and spectrum 98, respectively. Figure 6 for Figure 5 EDS spectrum of one point (spectral graph 97); Figure 7 for Figure 5 EDS spectrum of one point (spectral graph 98); Figure 8 The image shows the SEM images of the nickel-iron powder provided in Example 3. Three different points are marked in the image, corresponding to spectrum 100, spectrum 101 and spectrum 102 respectively. Figure 9 for Figure 8 EDS spectrum of one point (spectral 100). Figure 10 for Figure 8 EDS spectrum of one point (spectral diagram 101). Figure 11 for Figure 8 EDS spectrum of one point (spectral diagram 102). Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0022] This invention provides a nickel-iron powder with a non-uniform distribution of nickel and iron elements. The nickel-iron powder is tested using energy-dispersive X-ray spectroscopy (EDS) in the field of microbeam analysis. Eight points are randomly selected from 3-5 particles, and the iron-nickel mass ratios at these eight points are P1 to P8, respectively. The iron-nickel mass ratio at any point from P1 to P8 is P... i The expression is: P i =Y i / X i ; where X iY represents the mass fraction of nickel at that point; i This indicates the mass fraction of iron at that point.

[0023] That is, P1 = Y1 / X1, P2 = Y2 / X2, P3 = Y3 / X3, P4 = Y4 / X4, P5 = Y5 / X5, P6 = Y6 / X6, P7 = Y7 / X7, and P8 = Y8 / X8.

[0024] The average iron-nickel mass ratio P0 represents the average value of the iron-nickel mass ratio at 8 points, and its calculation formula is as follows: Average iron-nickel mass ratio P0 = (P1 + P2 + P3 + P4 + P5 + P6 + P7 + P8) / 8.

[0025] The variance S of the iron-nickel mass ratio 2 =[(P1-P0) 2 +(P2-P0) 2 +(P3-P0) 2 +(P4-P0) 2 +(P5-P0) 2 +(P6-P0) 2 +(P7-P0) 2 +(P8-P0) 2 ] / 8;S 2 ≥0.1, such as 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.60, 0.70, 0.80, 0.90, etc., S 2 A larger value indicates a more uneven distribution of nickel and iron elements. It should be noted that the variance S of the iron-nickel mass ratio of the nickel-iron powder provided in this embodiment of the invention... 2 If the ratio of nickel to iron is greater than or equal to 0.1, the nickel-iron element exhibits a heterogeneous state, which can rapidly increase the nickel content in the solution during subsequent wet acid leaching, thus benefiting downstream hydrometallurgical applications. If the variance S of the iron-nickel mass ratio... 2 If the value is too small (e.g., less than 0.1), the nickel leaching rate decreases significantly. In some embodiments, 0.1 ≤ S 2 ≤0.5.

[0026] Step size L = (P max -P min ) / 8, P max P represents the maximum value among P1 to P8. min This represents the minimum value among P1 to P8; the degree of dispersion K=S 2 / L 2 The range of K is 6-10, such as 6, 7, 8, 9, 10, etc. The larger the K value, the more uneven the distribution of nickel and iron elements. Nickel-iron powder with a nickel and iron element distribution that meets the above range is conducive to nickel leaching, and will lead to a significant increase in the nickel content in the supernatant after leaching.

[0027] In some embodiments, the mass fraction of nickel is 5%-90%, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc.; the mass fraction of iron is 10%-95%, such as 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, etc. The particle size of the nickel-iron powder is 70μm-180μm, such as 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, etc. The particle size of nickel-iron powder refers to the median particle size D50 of its mass (or volume, particle density) distribution, which is tested by conventional sieving methods.

[0028] This invention also provides a method for preparing nickel-iron powder, the steps of which are as follows: S1, Smelting According to the target nickel-iron element mass ratio, one or both of nickel-containing metals or iron-containing metals are added to the furnace and heated to melt, thus obtaining molten nickel-iron.

[0029] In some embodiments, the melting temperature is controlled at 1600℃-1800℃ to allow the raw materials to melt rapidly. Specifically, the melting temperature can be 1600℃, 1650℃, 1700℃, 1750℃, 1800℃, etc.

[0030] S2, Let stand The nickel-iron liquid obtained in step S1 is allowed to stand. Taking advantage of the density difference between nickel and iron, the nickel and iron elements undergo preliminary chromatography to obtain a chromatographic melt.

[0031] In some embodiments, the settling process is as follows: molten nickel-iron is poured into an intermediate ladle, and the temperature of the intermediate ladle is controlled at 1600℃-1800℃, such as 1600℃, 1630℃, 1650℃, 1680℃, 1700℃, 1730℃, 1750℃, 1780℃, 1800℃, etc.; the settling time is 20min-30min, such as 20min, 23min, 25min, 28min, 30min, etc.

[0032] S3, Solution preparation Prepare a surfactant solution for use in the atomization system.

[0033] In some embodiments, the surfactant in the surfactant solution is selected from at least one of hexadecyltrimethylammonium chloride, dodecyldimethylbenzylammonium chloride, AEO-9 (fatty alcohol polyoxyethylene ether (9EO)) and AEO-10 ​​(fatty alcohol polyoxyethylene ether (10EO)), and the surfactant can be any one or more of the above. Specifically, AEO-9 and AEO-10 ​​are both commercially available nonionic surfactants. AEO represents fatty alcohol polyoxyethylene ether, and 9 or 10 represents the average number of additions of ethylene oxide (EO) in the molecule. AEO-9 represents fatty alcohol polyoxyethylene (9) ether, and AEO-10 ​​represents fatty alcohol polyoxyethylene (10) ether.

[0034] In some embodiments, the surfactant solution is obtained by mixing a surfactant and a solvent, and the type of solvent is not limited, such as water. The mass fraction of the surfactant solution can be 0.05%-0.20%, such as 0.05%, 0.08%, 0.10%, 0.13%, 0.15%, 0.18%, 0.20%, etc.

[0035] It should be noted that by adding the above-mentioned type of surfactant to the water, which is heat-resistant, difficult to decompose, and non-volatile, the viscosity of the water can be increased and an oily hydrophobic film can be formed on the surface of the melt, "sticking and sealing" the vapor film, thereby strengthening the vapor film and making it easier to form the Leiden-Frost effect, thus reducing the heat exchange efficiency. At the same time, taking advantage of the different freezing points of nickel and iron, the slow solidification will lead to uneven precipitation of nickel and iron, resulting in elemental segregation and uneven element distribution.

[0036] S4, Atomization Chromatographic melt and surfactant solution enter the atomization system, using a coaxial annular slit nozzle. The annular slit ejects a high-pressure fluid formed by the surfactant solution, while the inner hole ejects the chromatographic melt, resulting in a slurry. The essence of the atomization process is the conversion of kinetic energy to surface energy: high-speed water transfers kinetic energy to the molten metal, overcoming its surface tension and breaking it into droplets. Under the action of surface tension, the droplets tend to become spherical and rapidly solidify into powder particles.

[0037] The pressure (water pressure) of the high-pressure fluid formed by the surfactant solution ranges from 1 MPa to 5 MPa, such as 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, etc. By controlling the pressure of the high-pressure fluid, a high flow velocity is achieved, forming a high-speed water curtain to realize strong shearing and fragmentation. The temperature (water temperature) of the high-pressure fluid formed by the surfactant solution ranges from 40℃ to 60℃, such as 40℃, 43℃, 45℃, 48℃, 50℃, 53℃, 55℃, 58℃, 60℃, etc. The higher fluid temperature serves two purposes: firstly, it prevents the surfactant from crystallizing and precipitating in the pipeline; secondly, it reduces heat exchange efficiency and is more conducive to the formation of a vapor film.

[0038] A coaxial annular slit nozzle (coaxial ring slit nozzle) is a two-fluid / single-fluid nozzle with a central channel and a concentric annular slit, capable of forming a coaxial, symmetrical, high-speed annular jet. The orifice diameter of the coaxial annular slit nozzle is 1.0mm-1.5mm, such as 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, etc.; the width of the annular slit is 0.2mm-0.5mm, such as 0.2mm, 0.3mm, 0.4mm, 0.5mm, etc.

[0039] Furthermore, the high-pressure fluid and the melt flow form an impact angle of 40°-50° to achieve stronger shearing and fragmentation. Specifically, the annular slit tilts inward to form the impact angle. The resulting impact angle can be 40°, 43°, 45°, 48°, 50°, etc. After atomization is started, the melt flow velocity of the atomization system is controlled at 0.5 kg / s-1.0 kg / s, such as 0.5 kg / s, 0.6 kg / s, 0.7 kg / s, 0.8 kg / s, 0.9 kg / s, 1.0 kg / s, etc.; the flow velocity of the high-pressure fluid (high-pressure water flow) is 80 m / s-150 m / s, such as 80 m / s, 90 m / s, 100 m / s, 110 m / s, 120 m / s, 130 m / s, 140 m / s, 150 m / s, etc.

[0040] S5, Post-processing The high-moisture slurry obtained in step S4 is post-processed, purified, and dried to prepare nickel-iron powder.

[0041] In some embodiments, the post-processing steps are as follows: the slurry is subjected to primary magnetic separation, washing, secondary magnetic separation, dewatering, and drying in sequence. The slurry is initially separated by primary magnetic separation, then washed to remove impurities such as surfactants, then separated again by secondary magnetic separation to remove non-magnetic impurities, then dewatered to remove a portion of the water, and finally dried to obtain the nickel-iron powder product.

[0042] Furthermore, a wet magnetic separator can be used to perform a single magnetic separation on the slurry to obtain wet nickel-iron powder with a moisture content of 25wt%-30wt% (by mass fraction). The washing method is not limited; for example, water washing can be used, with pure water added to prepare the slurry at a solid content of 500g / L-800g / L.

[0043] Furthermore, the dehydration method is not limited. For example, a filter press can be used to dehydrate the wet nickel-iron powder obtained from the secondary magnetic separation to obtain wet nickel-iron powder with a moisture content of 10wt%-15wt% (by mass fraction). The drying method is not limited. For example, an oven-drying method can be used, with the drying temperature controlled at 100℃-120℃, such as 100℃, 103℃, 105℃, 108℃, 110℃, 113℃, 115℃, 118℃, 120℃, etc.

[0044] When the nickel-iron powder provided in this embodiment of the invention is applied to hydrometallurgy, continuous acid leaching of the nickel-iron powder can rapidly increase the nickel content in the solution during wet acid leaching due to the heterogeneous state of the nickel-iron elements, which is beneficial for downstream hydrometallurgical applications.

[0045] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0046] The nickel-iron powder provided in the examples and comparative examples was tested using the following methods: ① The nickel and iron contents were determined by using the standards GB / T 30072-2025 Determination of Nickel Content in Iron by EDTA Titration and GB / T 32786-2016 Determination of Iron Content in Nickel-Containing Pig Iron by Potassium Dichromate Titration, respectively. ② Tested using energy-dispersive X-ray spectroscopy: Three particles were randomly selected, and eight points were tested to obtain the iron-nickel mass ratio at the eight points.

[0047] Wet leaching test: Take 5.0g of nickel-iron powder and place it in a beaker. Add 30mL of 1.0mol / L sulfuric acid and react in a water bath at 25℃ for 20min. Take the supernatant and test the nickel content using the method specified in GB / T 30902-2014 Determination of Impurity Elements in Inorganic Chemical Products by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES).

[0048] The test results of the nickel-iron powder provided in the examples and comparative examples are shown in Tables 1-10: Table 1 Test results of the nickel-iron powder provided in Example 1

[0049] Table 2 shows the test results of the nickel-iron powder provided in Example 2.

[0050] Table 3 shows the test results of the nickel-iron powder provided in Example 3.

[0051] Table 4 shows the test results of the nickel-iron powder provided in Example 4.

[0052] Table 5 shows the test results of the nickel-iron powder provided in Example 5.

[0053] Table 6 shows the test results of the nickel-iron powder provided in Example 6.

[0054] Table 7 shows the test results of the nickel-iron powder provided in Comparative Example 1.

[0055] Table 8 shows the test results of the nickel-iron powder provided in Comparative Example 2.

[0056] Table 9 shows the test results of the nickel-iron powder provided in Comparative Example 3.

[0057] Table 10 shows the test results of the nickel-iron powder provided in Comparative Example 4.

[0058] A comparison of Examples 1-6 and Comparative Examples 1-4 shows that if the variance S of the iron-nickel mass ratio... 2 If the K value exceeds the specified range, the nickel content in the supernatant after leaching will decrease significantly.

[0059] The preparation methods of nickel-iron powder provided in the various embodiments and comparative examples are described below: Example 1 This embodiment provides a method for preparing nickel-iron powder, including the following steps: (1) Smelting: Add the nickel-iron alloy to the furnace and melt it into nickel-iron liquid at 1600℃; the nickel mass fraction in the nickel-iron alloy is 20.00% and the iron mass fraction is 66.00%.

[0060] (2) Standing: Pour the molten nickel into the intermediate ladle, control the temperature of the intermediate ladle to 1600℃, and let it stand for 20 minutes; (3) Solution preparation: Prepare an aqueous solution of surfactant with a mass percentage concentration of 0.05%, using cetyltrimethylammonium chloride as the surfactant; (4) Atomization: The nickel-iron liquid enters the atomization system from the tundish. In the atomization system, a coaxial annular slit nozzle is used. The annular slit is the high-pressure water outlet (outputting the surfactant aqueous solution), and the inner hole is the melt outlet. The melt outlet diameter is 1.0 mm, and the high-pressure water outlet slit (width, the same below) is 0.2 mm. The water and the melt flow form an impact angle of 40°. Start the atomization and control the melt flow rate of the atomization system to be 0.5 kg / s, the water pressure to be 1 MPa, the water temperature to be 40°C, and the water outlet flow rate to be 80 m / s to obtain a slurry. (5) Magnetic separation: The slurry is initially separated by a wet magnetic separator to obtain wet nickel-iron powder with a water content of 25wt%; (6) Washing: Add pure water to make pulp and wash according to a solid content of 500g / L, and perform secondary magnetic separation (wet magnetic separator treatment, the same below); (7) Dehydration: The wet nickel-iron powder obtained by magnetic separation is dehydrated by a vacuum filter to obtain wet nickel-iron powder with a water content of 10wt%; (8) Drying: Dry at 100℃ to constant weight to obtain atomized nickel-iron powder with non-uniform elemental composition.

[0061] Example 2 This embodiment provides a method for preparing nickel-iron powder, including the following steps: (1) Smelting: Add the nickel-iron alloy to the furnace and melt it into nickel-iron liquid at 1650℃; the nickel mass fraction in the nickel-iron alloy is 20.00% and the iron mass fraction is 67.00%.

[0062] (2) Standing: Pour the molten nickel into the intermediate ladle, control the temperature of the intermediate ladle to 1650℃, and let it stand for 22 minutes; (3) Solution preparation: Prepare an aqueous solution of surfactant with a mass percentage concentration of 0.08%, using dodecyl dimethyl benzyl ammonium chloride as the surfactant; (4) Atomization: The nickel-iron liquid enters the atomization system from the tundish. In the atomization system, a coaxial annular slit nozzle is used. The annular slit is the outlet of the high-pressure water flow, and the inner hole is the outlet of the melt flow. The outlet diameter of the melt flow is 1.1 mm, and the slit of the high-pressure water flow outlet is 0.25 mm. The water and the melt flow form an impact angle of 42°. Start the atomization and control the melt flow velocity of the atomization system to be 0.6 kg / s, the water pressure to be 2 MPa, the water temperature to be 45 ℃, and the water flow velocity at the outlet to be 90 m / s to obtain the slurry. (5) Magnetic separation: The slurry is initially separated by a wet magnetic separator to obtain wet nickel-iron powder with a water content of 28wt%; (6) Washing: Add pure water to make pulp and wash according to a solid content of 600g / L, and perform secondary magnetic separation; (7) Dehydration: The wet nickel-iron powder obtained by magnetic separation is dehydrated by a vacuum filter to obtain wet nickel-iron powder with a water content of 15wt%; (8) Drying: Dry at 110°C to constant weight to obtain atomized nickel-iron powder with non-uniform elemental composition.

[0063] Example 3 This embodiment provides a method for preparing nickel-iron powder, including the following steps: (1) Smelting: Add the nickel-iron alloy to the furnace and melt it into nickel-iron liquid at 1700℃; the nickel mass fraction in the nickel-iron alloy is 21.00% and the iron mass fraction is 67.50%.

[0064] (2) Standing: Pour the molten nickel into the intermediate ladle, control the temperature of the intermediate ladle to 1700℃, and let it stand for 25 minutes; (3) Solution preparation: Prepare an aqueous solution of surfactant with a mass percentage concentration of 0.1%, using AEO-9 surfactant; (4) Atomization: The nickel-iron liquid enters the atomization system from the tundish. In the atomization system, a coaxial annular slit nozzle is used. The annular slit is the outlet of the high-pressure water flow, and the inner hole is the outlet of the melt flow. The outlet diameter of the melt flow is 1.2 mm, and the slit of the high-pressure water flow is 0.3 mm. The water and the melt flow form an impact angle of 45°. Start the atomization and control the melt flow rate of the atomization system to be 0.7 kg / s, the water pressure to be 3 MPa, the water temperature to be 50 ℃, and the water flow outlet velocity to be 100 m / s to obtain the slurry. (5) Magnetic separation: The slurry is initially separated by a wet magnetic separator to obtain wet nickel-iron powder with a water content of 26wt%; (6) Washing: Add pure water to make pulp and wash according to a solid content of 700g / L, and perform secondary magnetic separation; (7) Dehydration: The wet nickel-iron powder obtained by magnetic separation is dehydrated by a vacuum filter to obtain wet nickel-iron powder with a water content of 13wt%; (8) Drying: Dry at 110°C to constant weight to obtain atomized nickel-iron powder with non-uniform elemental composition.

[0065] The SEM and EDS images of the atomized nickel-iron powder prepared in this embodiment are as follows: Figures 1-11 As shown, Figure 1 The three points marked are different and correspond to spectral graph 94. Figure 2 ), Spectrum 95 ( Figure 3 ) and spectrum 96 ( Figure 4 ); Figure 5 The two points marked are different, corresponding to spectrum 97 ( Figure 6 ) and spectrum 98 ( Figure 7 ); Figure 8 The three points marked are different and correspond to spectral 100. Figure 9 ), Spectrum 101 ( Figure 10 ) and spectrum 102 ( Figure 11 ).

[0066] Example 4 This embodiment provides a method for preparing nickel-iron powder, including the following steps: (1) Smelting: Add the nickel-iron alloy to the furnace and melt it into nickel-iron liquid at 1750℃; the nickel mass fraction in the nickel-iron alloy is 20.00% and the iron mass fraction is 67.00%.

[0067] (2) Standing: Pour the molten nickel into the intermediate ladle, control the temperature of the intermediate ladle to 1750℃, and let it stand for 27 minutes; (3) Solution preparation: Prepare an aqueous solution of surfactant with a mass percentage concentration of 0.15%, using AEO-10 ​​surfactant; (4) Atomization: The nickel-iron liquid enters the atomization system from the tundish. In the atomization system, a coaxial annular slit nozzle is used. The annular slit is the outlet of the high-pressure water flow, and the inner hole is the outlet of the melt flow. The outlet diameter of the melt flow is 1.4 mm, and the slit of the high-pressure water flow outlet is 0.4 mm. The water and the melt flow form an impact angle of 45°. Start the atomization and control the melt flow rate of the atomization system to be 0.8 kg / s, the water pressure to be 4 MPa, the water temperature to be 55 ℃, and the water flow outlet velocity to be 110 m / s to obtain the slurry. (5) Magnetic separation: The slurry is initially separated by a wet magnetic separator to obtain wet nickel-iron powder with a water content of 27wt%; (6) Washing: Add pure water to make pulp and wash according to a solid content of 800g / L, and perform secondary magnetic separation; (7) Dehydration: The wet nickel-iron powder obtained by magnetic separation is dehydrated by a vacuum filter to obtain wet nickel-iron powder with a water content of 14wt%; (8) Drying: Dry at 120°C to constant weight to obtain atomized nickel-iron powder with non-uniform elemental composition.

[0068] Example 5 This embodiment provides a method for preparing nickel-iron powder, including the following steps: (1) Smelting: The nickel-iron alloy is added to the furnace and melted into nickel-iron liquid at 1700℃; the nickel mass fraction in the nickel-iron alloy is 20.00% and the iron mass fraction is 68.00%; (2) Standing: Pour the molten nickel into the intermediate ladle, control the temperature of the intermediate ladle to 1700℃, and let it stand for 30 minutes; (3) Solution preparation: Prepare an aqueous solution of surfactant with a mass percentage concentration of 0.18%, using AEO-10 ​​surfactant; (4) Atomization: The nickel-iron liquid enters the atomization system from the tundish. In the atomization system, a coaxial annular slit nozzle is used. The annular slit is the outlet of the high-pressure water flow, and the inner hole is the outlet of the melt flow. The diameter of the melt flow outlet is 1.5 mm, and the slit of the high-pressure water flow outlet is 0.5 mm. The water and the melt flow form an impact angle of 50°. Start the atomization and control the melt flow rate of the atomization system to be 1.0 kg / s, the water pressure to be 5 MPa, the water temperature to be 60 ℃, and the water flow outlet velocity to be 120 m / s to obtain the slurry. (5) Magnetic separation: The slurry is initially separated by a wet magnetic separator to obtain wet nickel-iron powder with a water content of 28wt%; (6) Washing: Add pure water to make pulp and wash according to a solid content of 800g / L, and perform secondary magnetic separation; (7) Dehydration: The wet nickel-iron powder obtained by magnetic separation is dehydrated by a vacuum filter to obtain wet nickel-iron powder with a water content of 15wt%; (8) Drying: Dry at 110°C to constant weight to obtain atomized nickel-iron powder with non-uniform elemental composition.

[0069] Example 6 This embodiment provides a method for preparing nickel-iron powder, including the following steps: (1) Smelting: The nickel-iron alloy is added to the furnace and melted into nickel-iron liquid at 1800℃; the nickel mass fraction in the nickel-iron alloy is 20.00% and the iron mass fraction is 67.00%; (2) Standing: Pour the molten nickel into the intermediate ladle, control the temperature of the intermediate ladle to 1800℃, and let it stand for 30 minutes; (3) Solution preparation: Prepare an aqueous solution of surfactant with a mass percentage concentration of 0.2%, using cetyltrimethylammonium chloride as the surfactant; (4) Atomization: The nickel-iron liquid enters the atomization system from the tundish. In the atomization system, a coaxial annular slit nozzle is used. The annular slit is the outlet of the high-pressure water flow, and the inner hole is the outlet of the melt flow. The diameter of the melt flow outlet is 1.5 mm, and the slit of the high-pressure water flow outlet is 0.5 mm. The water and the melt flow form an impact angle of 50°. Start the atomization and control the melt flow rate of the atomization system to be 1.0 kg / s, the water pressure to be 5 MPa, the water temperature to be 60 ℃, and the water flow outlet velocity to be 150 m / s to obtain the slurry. (5) Magnetic separation: The slurry is initially separated by a wet magnetic separator to obtain wet nickel-iron powder with a water content of 28wt%; (6) Washing: Add pure water to make pulp and wash according to a solid content of 800g / L, and perform secondary magnetic separation; (7) Dehydration: The wet nickel-iron powder obtained by magnetic separation is dehydrated by a vacuum filter to obtain wet nickel-iron powder with a water content of 15wt%; (8) Drying: Dry at 120°C to constant weight to obtain atomized nickel-iron powder with non-uniform elemental composition.

[0070] Comparative Example 1 The only difference from Example 3 is that step (2) involves using a rotary electromagnetic stirrer in the intermediate batch, controlling the magnetic induction intensity to be 0.14T, the stirring frequency to be 15Hz, and the stirring time to be 25min. This results in the uniform dispersion of nickel and iron elements in the intermediate batch, and a more uniform elemental distribution in the atomized powder.

[0071] Comparative Example 2 The only difference from Example 3 is that no surfactant was added in step (3). This can quickly break down the Leidenfrost vapor film to reduce interfacial thermal resistance, resulting in more uniform nickel-iron precipitation and no elemental segregation.

[0072] Comparative Example 3 The only difference from Example 3 is that the water pressure in step (4) is 15 MPa. The high water pressure results in faster heat exchange and more uniform nickel-iron precipitation during atomization.

[0073] Comparative Example 4 The only difference from Example 3 is that the water temperature in step (4) is 10°C. The lower water temperature results in faster heat exchange and more uniform nickel-iron precipitation during atomization.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A nickel-iron powder, characterized in that, Nickel-iron powder was tested using energy-dispersive X-ray spectroscopy. Eight sites were randomly selected from 3-5 particles, and the iron-nickel mass ratios at these eight sites were P1 to P8. The iron-nickel mass ratio at any site from P1 to P8 was P... i The expression is: P i =Y i / X i ; Among them, X i Y represents the mass fraction of nickel at that point; i This indicates the mass fraction of iron at that point; The average iron-nickel mass ratio P0 = (P1 + P2 + P3 + P4 + P5 + P6 + P7 + P8) / 8; The variance S of the iron-nickel mass ratio 2 =[(P1-P0) 2 +(P2-P0) 2 +(P3-P0) 2 +(P4-P0) 2 +(P5-P0) 2 +(P6-P0) 2 +(P7-P0) 2 +(P8-P0) 2 ] / 8; S 2 ≥0.1。 2. The nickel-iron powder according to claim 1, characterized in that, Step size L = (P max -P min ) / 8, P max P represents the maximum value among P1 to P8. min This represents the minimum value among P1 to P8; Dispersion K=S 2 / L 2 K ranges from 6 to 10.

3. The nickel-iron powder according to claim 1, characterized in that, The mass fraction of nickel is 5%-90%, and the mass fraction of iron is 10%-95%.

4. The nickel-iron powder according to claim 1, characterized in that, The particle size of nickel-iron powder is 70μm-180μm.

5. A method for preparing nickel-iron powder according to any one of claims 1-4, characterized in that, include: The molten nickel-iron alloy obtained from smelting is allowed to stand for a period of time to obtain a chromatographic melt. The chromatographic melt and surfactant solution enter the atomization system and are sprayed out using a coaxial annular slit nozzle. The high-pressure fluid formed by the surfactant solution is sprayed out through the annular slit, and the chromatographic melt is sprayed out through the inner hole to obtain a slurry. The pressure of the high-pressure fluid is 1MPa-5MPa and the temperature is 40℃-60℃. Nickel-iron powder is obtained by post-processing the slurry.

6. The preparation method according to claim 5, characterized in that, The settling process includes: pouring the molten nickel into an intermediate ladle, controlling the temperature of the intermediate ladle at 1600℃-1800℃, and settling for 20min-30min. And / or, the surfactant in the surfactant solution is selected from at least one of hexadecyltrimethylammonium chloride, dodecyldimethylbenzylammonium chloride, AEO-9, and AEO-10; And / or, the surfactant solution is an aqueous solution with a mass fraction of 0.05%-0.20%.

7. The preparation method according to claim 5, characterized in that, The diameter of the inner hole is 1.0mm-1.5mm, and the width of the annular slit is 0.2mm-0.5mm; And / or, the high-pressure fluid forms an impact angle of 40°-50° with the melt flow; And / or, the flow rate of the chromatographic melt is 0.5 kg / s-1.0 kg / s, and the flow rate of the high-pressure fluid is 80 m / s-150 m / s.

8. The preparation method according to claim 5, characterized in that, The preparation process of the nickel-iron liquid includes: adding raw materials that meet the target nickel-iron ratio into the furnace and smelting them at a temperature of 1600℃-1800℃.

9. The preparation method according to claim 5, characterized in that, The post-processing includes: subjecting the slurry to a first magnetic separation, washing, a second magnetic separation, dehydration, and drying in sequence.

10. The application of the nickel-iron powder according to any one of claims 1-4 or the nickel-iron powder prepared by the preparation method according to any one of claims 5-9 in hydrometallurgy; in, The application includes acid leaching of the nickel-iron powder.

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