A rare earth ferrosilicon alloy prepared based on NdFeB oil sludge and cutting waste silicon powder and a preparation method thereof

Abstract

The present invention provides a rare earth ferrosilicon alloy prepared based on NdFeB oil sludge and waste silicon powder from cutting and a preparation method thereof, the preparation method comprising the following steps: (1) pre-treating the NdFeB oil sludge to obtain a solid powder; (2) fully mixing dried waste silicon powder from cutting, metal calcium particles, anhydrous chloride and the solid powder obtained in step (1) in a certain proportion, and heating for a certain period of time under protective atmosphere conditions to obtain a rare earth ferrosilicon alloy and a slag phase. The method provided by the present invention is simple to operate, has a short reaction time, and has a high purity of the recycled alloy, thereby realizing the synergistic high-value utilization of NdFeB oil sludge and waste silicon powder from cutting.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial waste recycling and reuse, and relates to a recycled alloy, in particular to a recycled alloy prepared based on NdFeB oil sludge and cutting waste silicon powder, and a preparation method thereof. Background Art

[0002] On the one hand, NdFeB magnetic materials are widely used in defense and military industry, electronic information, medical equipment, clean energy and other fields due to their advantages such as high coercivity, high remanence and high magnetic energy product. In the production process of NdFeB, from raw material pretreatment to final product testing, waste is inevitably generated in each process. Among them, 20-30% of sludge is produced in the machining process, which is the largest category of NdFeB waste. According to different production processes, it can be divided into wire cutting sludge, coreless grinding sludge, double-sided grinding sludge, drilling sludge, etc., all of which are composed of NdFeB particles oxidized to varying degrees, cutting fluid (mainly organic matter and water), containing 20-25% of rare earth elements (Nd, Pr, Ce, etc.), which are valuable secondary resources. At the same time, the long-term disorderly mining of rare earth mineral resources has led to a sharp decline in reserves and serious ecological damage. Therefore, strengthening the recycling of rare earth secondary resources will not only help alleviate the current shortage of rare earth resources, but also help protect the ecological environment and promote the sustainable development of my country's rare earth industry.

[0003] On the other hand, the concept of reducing carbon emissions and advocating the use of new energy has gradually become a consensus among countries around the world. Crystalline silicon solar photovoltaic power generation has the advantages of being pollution-free and highly economical, and has great development potential. Crystalline silicon wafers are the most important basic material for preparing solar cells. However, in the process of producing crystalline silicon wafers, more than 40% of silicon enters the cutting waste slurry in the form of powder. The annual output of crystalline silicon cutting waste is more than 100,000 tons, and its main components are high-purity silicon and silicon oxide. If these cutting wastes can be recycled, it can not only reduce pollution to the environment, but also create economic benefits, while also indirectly reducing the production cost of solar cells, which is conducive to the development of the photovoltaic industry.

[0004] Rare earth ferrosilicon is an intermediate alloy composed of rare earths and elements such as silicon and iron. It is widely used in the fields of metallurgy and magnetic refrigeration materials. Traditional methods for producing rare earth ferrosilicon include electric arc furnace silicon thermal reduction and ore-fired furnace carbon thermal reduction, but both have problems such as high energy consumption and serious environmental pollution. The conventional treatment idea of ​​NdFeB sludge is based on the difference in the properties of rare earths and other elements. Only rare earth elements are recovered through pyrometallurgical or hydrometallurgical processes; the conventional treatment idea of ​​cutting waste silicon powder is to recover the metallic silicon through slag smelting. However, up to now, there has been no technical application for the production of rare earth ferrosilicon based on NdFeB sludge and cutting waste silicon powder. Summary of the invention

[0005] The purpose of the present invention is to provide a recycled alloy prepared based on NdFeB sludge and cutting waste silicon powder and a new preparation method thereof. The preparation method is simple to operate, has a short reaction time, and the recycled alloy has high purity, thereby achieving synergistic high-value utilization of the two waste materials.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a recycled alloy based on NdFeB oil sludge and cutting waste silicon powder, the method comprising the following steps:

[0008] (1) pre-treating the NdFeB oil sludge material to obtain a solid powder;

[0009] (2) The solid powder obtained in step (1) is fully mixed with dried waste silicon powder from cutting, metallic calcium particles, and anhydrous chloride in a certain proportion, and then heated for a certain period of time under protective atmosphere conditions to obtain rare earth ferrosilicon alloy and slag phase.

[0010] Preferably, the NdFeB sludge in step (1) comprises any one of wire cutting sludge, punching sludge, double-sided grinding sludge, coreless grinding sludge or oil-based slicing sludge, or a combination of at least two of them. Typical but non-limiting combinations include a combination of wire cutting sludge and punching sludge, a combination of punching sludge and double-sided grinding sludge, a combination of double-sided grinding sludge and coreless grinding sludge, a combination of coreless grinding sludge and oil-based slicing sludge, a combination of cutting sludge, punching sludge and double-sided grinding sludge, a combination of punching sludge, double-sided grinding sludge and coreless grinding sludge, or a combination of double-sided grinding sludge, coreless grinding sludge and oil-based slicing sludge.

[0011] In the present invention, the product CaO produced by the reaction of calcium and NdFeB oil sludge can react with the oxide SiO2 on the surface of waste silicon powder to generate a more stable calcium silicate phase, thereby achieving the synergistic removal of oxides in the two wastes; at the same time, calcium reacts with silicon in the waste silicon powder to generate a relatively low-volatile silicon-calcium alloy, and the reaction temperature is significantly higher than that of traditional calcium thermal reduction, which accelerates the reaction efficiency. The generated rare earth silicon-iron alloy NdFeSi can be used as a raw material for magnetic refrigeration materials, thereby achieving high-value utilization of waste materials.

[0012] Preferably, the pretreatment in step (1) comprises washing and drying performed sequentially.

[0013] Preferably, the washing liquid used for washing comprises any one of ethanol, acetic acid or acetone or a combination of at least two of them. Typical but non-limiting combinations include a combination of ethanol and acetic acid, a combination of acetic acid and acetone, a combination of ethanol and acetone, or a combination of ethanol, acetic acid and acetone, and acetone is further preferred.

[0014] Preferably, the solid-to-liquid volume ratio of the washing is 1:(4-6), for example, it can be 1:4, 1:4.2, 1:4.4, 1:4.6, 1:4.8, 1:5, 1:5.2, 1:5.4, 1:5.6, 1:5.8 or 1:6, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] In the present invention, the washing process utilizes washing liquid to be fully mixed with the oil sludge material to clean the organic impurities on the surface of the oil sludge material, thereby improving the purity of the solid powder.

[0016] In the present invention, the washing is accompanied by stirring.

[0017] Preferably, the stirring is performed using an electric stirrer.

[0018] Preferably, the stirring rate is 400-500 rpm, for example, 400 rpm, 410 rpm, 420 rpm, 430 rpm, 440 rpm, 450 rpm, 460 rpm, 470 rpm, 480 rpm, 490 rpm or 500 rpm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] Preferably, the stirring time is 40-80 min, for example, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min or 80 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0020] In the present invention, the stirring is followed by standing and stratification.

[0021] Preferably, the standing stratification time is 8-12 min, for example, 8 min, 8.5 min, 9 min, 9.5 min, 10 min, 10.5 min, 11 min, 11.5 min or 12 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] In the present invention, suction filtration is further performed after the static stratification.

[0023] Preferably, the filtration is carried out in a vacuum filter.

[0024] Preferably, the drying temperature is 300-500°C, for example, 300°C, 320°C, 340°C, 360°C, 380°C, 400°C, 420°C, 440°C, 460°C, 480°C or 500°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] Preferably, the drying time is 3-5 h, for example, 3 h, 3.2 h, 3.4 h, 3.6 h, 3.8 h, 4 h, 4.2 h, 4.4 h, 4.6 h, 4.8 h or 5 h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the shielding gas comprises any one of nitrogen, helium or argon, or a combination of at least two of them. Typical but non-limiting combinations include a combination of nitrogen and helium, a combination of helium and argon, a combination of nitrogen and argon, or a combination of nitrogen, helium and argon, and argon is further preferred.

[0027] Preferably, the dried NdFeB sludge material has the following components: Fe 60-70wt%, rare earth not less than 20wt%, oxygen not more than 10wt%, and other elements not more than 5wt%.

[0028] Preferably, the specific process of the thermal reduction treatment in step (2) is: mixing the waste silicon powder, anhydrous chloride powder, metallic calcium particles and the solid powder obtained in step (1), and performing a thermal reduction reaction in a protective atmosphere to obtain a rare earth ferrosilicon alloy.

[0029] In the present invention, the thermal reduction treatment is carried out in a molybdenum crucible, and the molybdenum crucible is placed in a vacuum induction furnace.

[0030] Preferably, the anhydrous chloride powder comprises any one of anhydrous calcium chloride powder, anhydrous sodium chloride powder or anhydrous potassium chloride powder, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of anhydrous calcium chloride powder and anhydrous sodium chloride powder, a combination of anhydrous sodium chloride powder and anhydrous potassium chloride powder, a combination of anhydrous calcium chloride powder and anhydrous potassium chloride powder, or a combination of anhydrous calcium chloride powder, anhydrous sodium chloride powder and anhydrous potassium chloride powder, and anhydrous calcium chloride powder is further preferred.

[0031] Preferably, the mass ratio of the cut waste silicon powder, anhydrous chloride powder, metallic calcium particles and the solid powder obtained in step (1) is (4-8):(10-30):(6-10):10, for example, it can be 4:15:7:10, 5:20:8:10 or 6:25:9:10, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] In the present invention, the mass ratio of the four materials has a certain degree of promoting effect on improving the purity of the recycled alloy and shortening the reaction time.

[0033] Preferably, the temperature of the thermal reduction reaction is 1200-1400° C., for example, 1200° C., 1250° C., 1300° C., 1350° C. or 1400° C., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0034] Preferably, the protective atmosphere gas in step (2) comprises any one of nitrogen, helium or argon, or a combination of at least two of them. Typical but non-limiting combinations include a combination of nitrogen and helium, a combination of helium and argon, a combination of nitrogen and argon, or a combination of nitrogen, helium and argon, and argon is further preferred.

[0035] As a preferred technical solution of the first aspect of the present invention, the method comprises the following steps:

[0036] (1) washing and drying the NdFeB sludge material in sequence to obtain a solid powder; the washing liquid used for the washing is acetone, and the solid-liquid volume ratio is 1:(4-6); the drying temperature is 300-500°C, the time is 3-5 hours, and it is carried out under argon protection; the NdFeB sludge material includes any one of wire cutting sludge material, punching sludge material, double-sided grinding sludge material, coreless grinding sludge material or oil-based slicing sludge material, or a combination of at least two thereof;

[0037] (2) The solid powder obtained in step (1) is fully mixed with dried waste silicon powder from cutting, metal calcium particles, and anhydrous calcium chloride in a certain proportion, and then heated to 1200-1400° C. under argon atmosphere, and kept warm for 40-80 minutes to obtain rare earth ferrosilicon alloy and slag phase. The mass ratio of the waste silicon powder from cutting, anhydrous chloride powder, metal calcium particles to the solid powder obtained in step (1) is (4-8):(10-30):(6-10):10.

[0038] In a second aspect, the present invention provides a rare earth ferrosilicon alloy prepared by the method described in the first aspect, wherein the silicon content and oxygen content of the recycled alloy are ≤0.1wt%, for example, it can be 0.01wt%, 0.02wt%, 0.03wt%, 0.04wt%, 0.05wt%, 0.06wt%, 0.07wt%, 0.08wt%, 0.09wt% or 0.1wt%, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] There is no prior art similar to the present invention, and the beneficial effects of the present invention are:

[0040] (1) The present invention provides a new method for preparing rare earth ferrosilicon alloy, and at the same time realizes the high-value utilization of two typical solid wastes, namely, NdFeB oil sludge and waste silicon powder from cutting;

[0041] (2) The rare earth ferrosilicon alloy prepared by the method provided by the present invention has high purity: the strong reducing ability of calcium ensures deep deoxidation of the waste; and the higher reaction temperature ensures rapid deoxidation of the waste.

[0042] (3) The method provided by the present invention has high applicability, low cost, and little pollution to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The flow chart of preparing rare earth ferrosilicon alloy based on NdFeB oil sludge and cutting waste silicon powder provided in the specific embodiment 1 of the present invention is

[0044] Figure 2 This is the scan result of the rare earth ferrosilicon alloy surface provided in the specific embodiment 1 of the present invention.

[0045] Figure 3 The slag phase XRD spectrum provided in the specific embodiment 1 of the present invention is DETAILED DESCRIPTION

[0046] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0047] Example 1

[0048] This embodiment provides a rare earth ferrosilicon alloy prepared based on NdFeB oil sludge and waste silicon powder from cutting and a preparation method thereof. The specific process is as follows: Figure 1 As shown, the preparation method comprises the following steps:

[0049] (1) The NdFeB wire cutting oil sludge material is washed and stirred in sequence, allowed to stand for 10 minutes for stratification, filtered, dried, and cooled to room temperature to obtain a solid powder; the washing liquid used for the washing is acetone, and the solid-liquid volume ratio is 1:5; the stirring is carried out using an electric stirrer at a stirring rate of 450 rpm for 60 minutes; the filtration is carried out in a vacuum filter; the drying temperature is 400°C for 4 hours and is carried out under argon protection; the solid powder has an oxygen content of 9.2wt%, an iron content of 63wt%, a rare earth content of 27.2wt%, and the remainder is other trace elements;

[0050] (2) 50 g of cut waste silicon powder, 100 g of calcium chloride, 60 g of metallic calcium particles, and 70 g of the solid powder obtained in step (1) were mixed uniformly in a molybdenum crucible, and then placed in a vacuum induction furnace. The temperature was raised to 1200° C. in an argon protective atmosphere, and the mixture was kept at this temperature for 50 min and then cooled with the furnace.

[0051] The rare earth ferrosilicon alloy obtained in this embodiment has a silicon content of 15.2wt%, an iron content of 60.02wt%, a rare earth content of 23.3wt%, and an oxygen content of 0.07wt%. The surface scanning results are as follows: Figure 1The XRD pattern of the obtained slag phase is shown in Figure 2 shown.

[0052] Example 2

[0053] This embodiment provides a recycled alloy prepared based on NdFeB oil sludge and waste silicon powder from cutting and a preparation method thereof, the preparation method comprising the following steps:

[0054] (1) The NdFeB drilling oil sludge material is washed and stirred in sequence, allowed to stand for 8 minutes for stratification, filtered, dried, and cooled to room temperature to obtain a solid powder; the washing liquid used for the washing is ethanol, and the solid-liquid volume ratio is 1:4; the stirring is carried out using an electric stirrer at a stirring rate of 400 rpm for 80 minutes; the filtration is carried out in a vacuum filter; the drying temperature is 300°C for 5 hours and is carried out under nitrogen protection; the solid powder has an oxygen content of 6.4wt%, an iron content of 63.3wt%, a rare earth content of 26.0wt%, and the remainder is other trace elements;

[0055] (2) 60 g of waste silicon powder, 120 g of calcium chloride, 70 g of metallic calcium particles and 70 g of the solid powder obtained in step (1) were mixed uniformly in a molybdenum crucible, and then placed in a vacuum induction furnace. The temperature was raised to 1300° C. in an argon protective atmosphere, and the mixture was kept at this temperature for 50 min and then cooled with the furnace.

[0056] The rare earth ferrosilicon alloy obtained in this embodiment has a silicon content of 17.4 wt %, an iron content of 58.42 wt %, a rare earth content of 20.3 wt %, and an oxygen content of 0.05 wt %.

[0057] Example 3

[0058] This embodiment provides a recycled alloy prepared based on NdFeB oil sludge and waste silicon powder from cutting and a preparation method thereof, the preparation method comprising the following steps:

[0059] (1) The NdFeB double-sided grinding oil sludge is washed and stirred in sequence, allowed to stand for 11 minutes for stratification, filtered, dried, and cooled to room temperature to obtain a solid powder; the washing liquid used for the washing is acetic acid, and the solid-liquid volume ratio is 1:6; the stirring is carried out using an electric stirrer at a rate of 500 rpm for 40 minutes; the filtration is carried out in a vacuum filter; the drying temperature is 500° C. for 3 hours, and is carried out under helium protection; the oxygen content of the solid powder is 6.82wt%, the iron content is 65.5wt%, the rare earth content is 25.4wt%, and the remainder is other trace elements;

[0060] (2) 80 g of waste silicon powder, 150 g of calcium chloride, 80 g of metallic calcium particles, and 70 g of the solid powder obtained in step (1) were mixed uniformly in a molybdenum crucible, and then placed in a vacuum induction furnace. The temperature was raised to 1400° C. in an argon protective atmosphere, and the mixture was kept at this temperature for 60 min and then cooled with the furnace.

[0061] The rare earth ferrosilicon alloy obtained in this example has a silicon content of 19.0 wt %, an iron content of 55.42 wt %, a rare earth content of 15.3 wt %, and an oxygen content of 0.04 wt %.

[0062] Example 4

[0063] This embodiment provides a recycled alloy prepared based on NdFeB oil sludge and waste silicon powder from cutting and a preparation method thereof, the preparation method comprising the following steps:

[0064] (1) The NdFeB double-sided grinding oil sludge is washed and stirred in sequence, allowed to stand for 11 minutes for stratification, filtered, dried, and cooled to room temperature to obtain a solid powder; the washing liquid used for the washing is acetic acid, and the solid-liquid volume ratio is 1:6; the stirring is carried out using an electric stirrer at a rate of 500 rpm for 40 minutes; the filtration is carried out in a vacuum filter; the drying temperature is 500° C. for 3 hours, and is carried out under helium protection; the oxygen content of the solid powder is 6.82wt%, the iron content is 65.5wt%, the rare earth content is 25.4wt%, and the remainder is other trace elements;

[0065] (2) 90 g of cut silicon waste powder, 200 g of calcium chloride, 90 g of metallic calcium particles, and 70 g of the solid powder obtained in step (1) were mixed uniformly in a molybdenum crucible, and then placed in a vacuum induction furnace. The temperature was raised to 1500° C. in an argon protective atmosphere, and the mixture was kept at this temperature for 70 min and then cooled with the furnace.

[0066] The rare earth ferrosilicon alloy obtained in this example has a silicon content of 21.3 wt %, an iron content of 54.42 wt %, a rare earth content of 14.2 wt %, and an oxygen content of 0.03 wt %.

[0067] Comparative Example 1

[0068] This embodiment provides a rare earth ferrosilicon alloy prepared based on NdFeB oil sludge and waste silicon powder from cutting and a preparation method thereof. Step (1) is the same as that of embodiment (1) and is not repeated here. Step (2) is changed to: (2) 60 g of waste silicon powder from cutting, 60 g of calcium chloride, 70 g of metal calcium particles, and 70 g of the solid powder obtained in step (1) are mixed evenly in a molybdenum crucible, and then placed in a vacuum induction furnace, and the temperature is raised to 1300°C in an argon protective atmosphere throughout the process, and the mixture is kept warm for 50 minutes and then cooled with the furnace.

[0069] The rare earth ferrosilicon alloy obtained in this example has a silicon content of 16.2 wt %, an iron content of 61.02 wt %, a rare earth content of 22.4 wt %, and an oxygen content of 0.17 wt %.

[0070] Compared with Example 1, the amount of calcium chloride added in step (2) of this embodiment is reduced to 60 g, which is not conducive to the removal of oxides in the NdFeB sludge and cutting waste silicon powder, and the purity of the recycled alloy is not ideal.

[0071] Comparative Example 2

[0072] This embodiment provides a rare earth ferrosilicon alloy prepared based on NdFeB sludge and waste silicon powder from cutting and a preparation method thereof. The reaction temperature in step (2) is 1100° C., and the rest is the same as in Embodiment 1 and will not be repeated herein.

[0073] The rare earth ferrosilicon alloy obtained in this example has a silicon content of 16.5 wt %, an iron content of 62.02 wt %, a rare earth content of 23.2 wt %, and an oxygen content of 0.20 wt %.

[0074] Compared with Example 1, the temperature in step (2) of this embodiment is reduced to 1100° C., which is not conducive to the removal of oxides in the NdFeB sludge and the waste silicon powder from cutting, and the purity of the recycled alloy is not ideal.

[0075] The above contents are further detailed descriptions of the present invention in combination with specific implementation methods, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention.

Claims

1. A method for preparing rare earth ferrosilicon alloy based on NdFeB sludge and waste silicon powder from cutting, characterized in that: The method consists of the following steps: (1) pre-treating the NdFeB oil sludge material to obtain a solid powder; (2) the solid powder obtained in step (1) is fully mixed with dried waste silicon powder from cutting, metallic calcium particles, and anhydrous chloride in a certain proportion, and heated for 50 to 60 minutes under protective atmosphere conditions to obtain rare earth ferrosilicon alloy and slag phase; The heating temperature is 1250-1400°C; The mass ratio of the cutting waste silicon powder, the anhydrous chloride powder, the metal calcium particles and the solid powder obtained in step (1) is (4-8):(10-30):(6-10):10; The oxygen content of the rare earth ferrosilicon alloy is ≤0.1wt%.

2. The method according to claim 1, characterized in that The NdFeB sludge material in step (1) includes any one of wire cutting sludge material, punching sludge material, double-sided grinding sludge material, coreless grinding sludge material or oil-based slicing sludge material, or a combination of at least two of them.

3. The method according to claim 1, characterized in that The pretreatment in step (1) includes washing and drying performed sequentially.

4. The method according to claim 3, characterized in that The washing liquid used for the washing includes any one of ethanol, acetic acid or acetone, or a combination of at least two of them.

5. The method according to claim 4, characterized in that The washing liquid used in the washing is acetone.

6. The method according to claim 3, characterized in that The solid-liquid volume ratio of the washing is 1:(4-6).

7. The method according to claim 3, characterized in that The drying temperature is 300-500°C.

8. The method according to claim 3, characterized in that The drying time is 3-5h.

9. The method according to claim 3, characterized in that: The drying is performed in either nitrogen or argon.

10. The method according to claim 9, characterized in that The drying was carried out under argon.

11. The method according to claim 3, characterized in that The chemical composition of the dried NdFeB sludge material meets the following requirements: Fe content is 60-70wt%, rare earth content is not less than 20wt%, oxygen content is not more than 10wt%, and other elements are not more than 5wt%.

12. The method according to claim 1, characterized in that The anhydrous chloride powder includes any one of anhydrous calcium chloride powder, anhydrous sodium chloride powder or anhydrous potassium chloride powder, or a combination of at least two of them.

13. The method according to claim 12, characterized in that The anhydrous chloride powder is anhydrous calcium chloride powder.

14. The method according to claim 1, characterized in that The chemical composition of the waste silicon powder from cutting meets the following requirements: single substance Si is not less than 90wt%, SiO2 is not more than 10wt%, and other elements are not more than 2wt%.

15. The method according to claim 1, characterized in that The protective atmosphere is any one of nitrogen, helium or argon, or a combination of at least two of them.

16. The method according to claim 15, characterized in that The protective atmosphere is argon.

17. The method according to claim 1, characterized in that The method comprises the following steps: (1) washing and drying the NdFeB sludge material in sequence to obtain a solid powder; the washing liquid used for the washing is acetone, and the solid-liquid volume ratio is 1:(4-6); the drying temperature is 300-500°C, the time is 3-5 hours, and it is carried out under argon protection; the NdFeB sludge material includes any one of wire cutting sludge material, punching sludge material, double-sided grinding sludge material, coreless grinding sludge material or oil-based slicing sludge material, or a combination of at least two thereof; (2) After fully mixing the dried waste silicon powder from cutting, metallic calcium particles, anhydrous calcium chloride and the solid powder obtained in step (1) in a certain proportion, heating to 1250-1400° C. under argon atmosphere, and keeping the temperature for 50-60 min to obtain rare earth ferrosilicon alloy and slag phase; the mass ratio of the waste silicon powder from cutting, anhydrous chloride powder, metallic calcium particles and the solid powder obtained in step (1) is (4-8):(10-30):(6-10):

10.

18. A rare earth ferrosilicon alloy prepared by the method according to any one of claims 1 to 17, characterized in that: The oxygen content of the rare earth ferrosilicon alloy is ≤0.1wt%.

Images