Preparation method of high-rare-earth iron-based alloy powder containing copper and aluminum

Abstract

The invention discloses a preparation method of high-rare-earth iron-based alloy powder containing copper and aluminum, and belongs to the technical field of alloy powder preparation. Comprising the following steps that copper and iron in weighed raw materials are loaded into a vacuum rapid hardening furnace according to the charging principle, and vacuumizing smelting is conducted in the vacuum rapid hardening furnace; after the pure iron and copper are molten to reach the target high temperature, secondary charging is carried out, rare earth metal and aluminum which are accurately proportioned are added into molten steel, heat preservation and refining are carried out, after the pouring temperature is reached, the molten steel is evenly poured to a rotating copper roller with a certain rotating speed and a certain cooling water temperature, rapid hardening and cooling are carried out, and alloy sheets are obtained; and the prepared alloy sheet is subjected to impact grinding to prepare alloy powder. By adding copper and aluminum metals, the physical properties of the alloy are improved, and the prepared alloy powder is smaller in particle size, high in catalytic activity and long in service life and meets the market requirements; the one-time powder yield is high, the production cost is greatly reduced, and the method can be applied to the production of rare earth catalyst products on a large scale.

Description

Technical Field

[0001] The invention relates to the technical field of alloy powder preparation, in particular to a method for preparing copper-aluminum-containing high-rare-earth iron-based alloy powder. Background Art

[0002] The content of cerium in the earth's crust is about 0.0046%, which is the most abundant element among rare earth elements. Due to the large accumulation of cerium and other metals extracted from associated mining, the utilization of rare earth elements is seriously unbalanced, which is not conducive to the healthy and sustainable development of rare earth resource utilization. In order to promote the balanced utilization of high-abundance rare earth resources and alleviate the current imbalance in the utilization of rare earth resources, the present invention develops a high-rare earth iron-based alloy powder, which is mainly used as a front-end raw material for the production of rare earth catalysts. At present, petroleum refining and chemical industry is an important field of rare earth application, and it is also one of the major users and consumers of rare earths. In the petrochemical industry, catalytic technology occupies an extremely important position; because rare earth elements have a special electronic structure, the outermost electron arrangement 4f and 5d that determine the properties of rare earth elements form a conduction band, and the localization and incomplete filling of 4f electrons give rare earths unique optical and magnetic properties. These properties make rare earths widely used in the field of catalysis.

[0003] In the current market, rare earth iron alloys are conventionally ingot alloys, and their coarse crushing process is dangerous and cumbersome, and because of the high rare earth content, it is difficult to make fine powder with a particle size of ≤120μm.

[0004] Chinese invention patent CN117415323A discloses a rare earth iron alloy powder and its preparation method and use. After the alloy powder is crushed and screened, the product size is relatively large, about 3 mm, which cannot reach the 120μm required for the production of rare earth catalysts. It has a small specific surface area and poor catalytic activity, and is not suitable for the preparation of rare earth catalysts. It does not contain copper and aluminum elements and has poor physical properties.

[0005] Chinese invention patent CN111952032A discloses a method for preparing a low-boron, low-heavy rare earth, high-coercivity sintered NdFeB permanent magnet. The invention is a method for preparing NdFeB magnets, which have a rare earth content of 30-35wt% and contain B element, resulting in poor catalytic activity of the alloy, making it unsuitable for the preparation of rare earth catalysts. In addition, the preparation requires a hydrogen cracking process, resulting in a high production cost.

[0006] Chinese invention patent CN103361543A discloses a ferrocerium alloy and its preparation and use method, which is smelted in a vacuum induction furnace, using metal cerium with a purity greater than 99.0% and pure iron with a purity greater than 99.0% as raw materials, and after the cerium content is 0.1-15wt% and the balance is Fe, it is melted in a vacuum induction furnace and cast into an ingot of qualified size under the condition of argon protective atmosphere. The invention mainly discloses a ferrocerium ingot alloy added in steelmaking, but it requires a coarse crushing process such as jaw crushing, and cannot be made into an alloy powder with a particle size of ≤120μm. Summary of the invention

[0007] The purpose of the present invention is to provide a method for preparing copper-aluminum high-rare earth iron-based alloy powder. The total amount of rare earth in the produced high-rare earth iron-based alloy powder reaches more than 45%. As the front-end raw material of the rare earth catalyst, the particle size and activity of the product are highly required. The present invention optimizes the process, preliminarily makes the alloy into thin sheets, changes the physical brittleness of the alloy by adding elements, simplifies the powder making process, and allows the alloy to be granulated into fine powder with a particle size of ≤120μm at one time without coarse crushing, greatly reduces the production cost, obtains a finer powder particle size, improves the activity of the alloy powder, and meets customer needs.

[0008] The technical solution adopted by the present invention is as follows:

[0009] A method for preparing copper-aluminum high rare earth iron-based alloy powder, wherein the alloy powder is composed of the following components by mass percentage: rare earth content is 44-46wt%, aluminum is 1.2-1.8wt%, copper is 0.8-1.2wt%, and the rest is iron; the preparation method comprises the following steps:

[0010] Step 1: accurately weigh the raw materials according to the mass ratio requirements of the alloy powder; and load the copper and iron in the weighed raw materials into the vacuum rapid solidification furnace according to the furnace loading principle, and perform vacuum smelting in the vacuum rapid solidification furnace;

[0011] Step 2: After pure iron and copper are melted to the target high temperature, a secondary feed is performed to add accurate proportions of rare earth metals and aluminum to the molten steel, and the steel is kept warm and refined. After the pouring temperature is reached, the molten steel is uniformly poured onto a rotating copper roller at a certain speed and a certain cooling water temperature for rapid solidification and cooling to obtain an alloy sheet with an average sheet thickness of 0.21±0.01mm;

[0012] Step 3: The alloy flakes obtained in step 2 are passed through an impact mill to obtain alloy powder with a particle size of ≤120 μm.

[0013] The rare earth element in the alloy powder is one or two of neodymium and cerium.

[0014] The principle of loading the furnace in step one is that the pure iron is at the bottom and the copper is placed in the gap between the iron rods.

[0015] In step 2, the target high temperature is 1475±20°C; the pouring temperature is 1420-1450°C.

[0016] In step 2, the rotation speed of the copper roller is controlled at 1.2 m / s to 1.64 m / s; and the cooling water temperature is 10° C. to 12° C.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0018] The total amount of rare earth in the iron-based alloy powder with high rare earth content produced by the present invention reaches more than 45%, and can be used as the front-end raw material of rare earth catalysts with high requirements on the particle size and activity of the product. The present invention optimizes the process, the alloy is initially made into thin sheets, and the physical brittleness of the alloy is changed by adding copper and aluminum metal elements, and the powder making process is simplified, so that it can be powdered into fine powder with a particle size of ≤120μm at one time without coarse crushing, which greatly reduces the production cost, obtains a finer powder particle size, improves the activity of the alloy powder, and meets customer needs.

[0019] In summary, the alloy powder prepared by the present invention has good catalytic activity, small particle size, and has the characteristics of high activity, high selectivity, long life, low pollution, etc., and has a simple preparation process and low production cost, and can be widely used in the production of high rare earth catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a process flow chart of the present invention;

[0021] Figure 2 This is the XRD diffraction pattern of this type of alloy powder;

[0022] Figure 3 This is the alloy powder particle size detection table of comparative example 3 of the present invention;

[0023] Figure 4 This is the alloy powder particle size detection table of Example 2 of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, 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 in combination with the drawings and specific data in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0025] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] Example

[0027] like Figure 1 This embodiment provides a method for preparing copper-aluminum high rare earth iron-based alloy powder, comprising the following specific steps:

[0028] Step 1: The contents of the elements in the alloy powder are: 1.2-1.8wt% aluminum, 0.8-1.2wt% copper, 50-56wt% iron, 3-9wt% neodymium, and 33-39wt% cerium. According to the above mass ratio, the powder is accurately weighed, and a small amount of excess is allowed for a certain burn-off rate. The purity of the metals Nd, Ce, Al, Cu, and Fe used is greater than 99%.

[0029] The higher total amount of rare earth in step 1 ensures the high catalytic activity of the product, and a small amount of alloy powder can meet the required total amount of rare earth, reducing the use cost. The addition of aluminum improves the physical properties of the alloy on the one hand, and secondly improves the catalytic activity of the alloy, prolongs the service life of the catalytic alloy, and preferably selects an aluminum content of 1.8wt%. The addition of can optimize the organizational structure of the alloy, refine the alloy grains, and reduce organizational segregation. Copper, as a solid solution strengthening element, can improve the strength and hardness of the iron-based alloy, reduce toughness and ductility, and is beneficial to the brittleness of the high rare earth alloy and to improve the one-time powder production rate. Preferably, the aluminum content is 1.2wt%.

[0030] Step 2: The copper and iron weighed in step 1 are all loaded into a rapid-setting furnace for vacuum smelting according to the charging principle of pure iron at the bottom and copper placed in the gap between iron bars. After the pure iron and copper are melted to reach the target high temperature, a secondary feeding is performed to add accurately proportioned rare earth metals and aluminum to the molten steel, and the steel is kept warm and refined. After the pouring temperature is reached, the molten steel is uniformly poured onto a rotating copper roller and rapidly solidified and cooled to obtain an alloy sheet with an average sheet thickness of 0.21±0.01㎜; the smelting temperature is 1475±20℃, the pouring temperature selection range is 1420~1460℃, the copper roller speed is designed to be adjusted to 1.2m / s~1.64m / s, and the water temperature is adjusted to 10~12℃.

[0031] In step 2, copper particles are placed in the gap between the iron rods to quickly form a solid solution alloy, which can accelerate the melting of high-melting-point metal iron, shorten the melting time, and reduce production costs. After pure iron and copper are melted and the molten steel reaches the target high temperature, rare earth metals and aluminum are added to the molten steel to reduce the loss of rare earth metals and aluminum. The target high temperature ensures the thorough melting of the iron rod, while reducing the loss and volatilization of rare earths, preventing overmelting, and ensuring sufficient rare earths in the product. The preferred target high temperature is 1485°C. The pouring temperature is 1420-1450°C. If the pouring temperature is too high, it will affect the physical properties of the alloy, causing the alloy to harden and making powder difficult. Too low a temperature will cause the thickness of the sheet to be too thick, increasing the cost of powder making. The preferred pouring temperature is 1450°C. The copper roller speed is controlled at 1.2m / s-1.64m / s. Selecting a suitable copper roller speed ensures that the thickness of the alloy sheet is qualified. The copper rod speed is preferably 1.64m / s. The cooling water temperature is 10°C to 12°C. A lower cooling water temperature provides a greater cooling rate, ensures uniform composition of the alloy, eliminates the generation of α-Fe, and improves the physical properties of the alloy. The preferred cooling water temperature is 10°C.

[0032] Step 3: The alloy flakes with an average thickness of 0.21±0.01 mm prepared in step 2 are made into alloy powder by impact milling equipment, and the one-time powder making yield is greater than 97%, and the obtained powder particle size is ≤120 μm.

[0033] Alloy powder was prepared according to the above steps, and the sheet thickness, particle size and XRD tests were performed. The formula and process of Comparative Examples 1-3 and the embodiment of the present invention are different, as shown in the following table:

[0034]

[0035] As shown in the table above, the formula and production process of the comparative example and the embodiment of the present invention are different. Figure 3 , 4 , Comparative Examples 1 and 2 are produced by ingot casting process, which is very difficult to make powder, the production particle size is coarse, and it is easy to burn, there are safety hazards, and the difficulty of powder making has not been solved. Comparative Example 3 is an alloy flake produced by ordinary belt throwing process, which is easy to make powder, but it needs to be repeatedly ground during powder making, the one-time yield is low, and the powder particle size is coarse; in Comparative Example 2, the cerium content in the alloy powder has met the customer's needs. After the production process is adjusted, in Examples 1, 2, and 3, the alloy powder components and activity meet the customer's use requirements, and the average thickness of the alloy flakes is reduced to 0.210mm, 0.208mm, and 0.216mm. With the adjustment of production process and trace elements, the brittleness of the flakes is greatly improved, and the one-time yield during powder making reaches more than 97%; without the embrittlement and crushing process, the alloy powder particle size D50 can be controlled at about 50μm, the particle size is finer, which meets the use requirements, and this high rare earth alloy is not easy to burn during powder making, and can be safely produced in large quantities.

[0036] from Figure 2 It can be seen that the crystal structure of the alloy is a typical face-centered cubic phase structure. The main diffraction peaks in the XRD spectrum are very strong and the peaks are relatively sharp, indicating that the crystal structure of the alloy is relatively complete and has no inclusions. 14 The rare earth permanent magnet alloy with B compound as the base phase belongs to the hexagonal closest packing structure. Its rare earth atoms are located in the A layer of the hexagonal closest packing, the iron atoms are located in the C layer of the hexagonal closest packing, and the boron atoms are located in the B layer of the hexagonal closest packing, which is completely different from the alloy crystal structure obtained by the invention.

Claims

1. A method for preparing copper-aluminum high rare earth iron-based alloy powder, characterized in that: The alloy powder is composed of the following components by mass percentage: rare earth content is 44-46wt%, aluminum is 1.2-1.8wt%, copper is 0.8-1.2wt%, and the rest is iron; the preparation method comprises the following steps: Step 1: accurately weigh the raw materials according to the mass ratio requirements of the alloy powder; and load the copper and iron in the weighed raw materials into the vacuum rapid solidification furnace according to the furnace loading principle, and perform vacuum smelting in the vacuum rapid solidification furnace; Step 2: After pure iron and copper are melted to the target high temperature, a secondary feed is performed to add accurate proportions of rare earth metals and aluminum to the molten steel, and the steel is kept warm and refined. After the pouring temperature is reached, the molten steel is uniformly poured onto a rotating copper roller at a certain speed and a certain cooling water temperature for rapid solidification and cooling to obtain an alloy sheet with an average sheet thickness of 0.21±0.01mm; Step 3: The alloy flakes obtained in step 2 are passed through an impact mill to obtain alloy powder with a particle size of ≤120 μm.

2. The method for preparing a copper-aluminum high rare earth iron-based alloy powder according to claim 1, characterized in that: The rare earth element in the alloy powder is one or two of neodymium and cerium.

3. The method for preparing a copper-aluminum high rare earth iron-based alloy powder according to claim 1, characterized in that: The principle of loading the furnace in step one is that the pure iron is at the bottom and the copper is placed in the gap between the iron rods.

4. The method for preparing a copper-aluminum high rare earth iron-based alloy powder according to claim 1, characterized in that: In step 2, the target high temperature is 1475±20°C; the pouring temperature is 1420-1450°C.

5. The method for preparing a copper-aluminum high rare earth iron-based alloy powder according to claim 1, characterized in that: In step 2, the rotation speed of the copper roller is controlled at 1.2 m / s to 1.64 m / s; and the cooling water temperature is 10° C. to 12° C.

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