A pretreatment method for NdFeB oil sludge waste

Abstract

The present invention discloses a pretreatment method for NdFeB oil sludge waste, the method comprising: performing solid-liquid separation on the NdFeB oil sludge waste to obtain liquid and solid NdFeB oil sludge; adding an organic solvent to the solid NdFeB oil sludge for leaching under stirring conditions, and then filtering and / or suction filtering to obtain an extract and NdFeB waste; vacuum drying the NdFeB waste, and then sieving to remove impurities to obtain NdFeB powder. The present invention abandons the commonly used water-based cleaning liquid in the prior art, creatively utilizes a recyclable organic solvent to leaching the NdFeB oil sludge waste, and obtains clean NdFeB powder through simple centrifugation, leaching, drying and sieving. The reagent cost used in the method is low, the impact on the environment and the waste itself is small, and the treated NdFeB waste has low carbon, hydrogen, oxygen and other impurity contents, so as to achieve the purpose of purification, and the product purity is high, the process flow is short, and the operation is simple.

Description

Technical Field

[0001] The invention relates to the technical field of recycling and reusing rare earth permanent magnet waste, and in particular to a pretreatment method for NdFeB oil sludge waste. Background Art

[0002] my country's production of sintered NdFeB magnets accounts for more than 90% of the world's total production of NdFeB magnets. In the production and processing of sintered NdFeB, 40-45wt.% of the raw materials become block scraps and sludge and other waste materials due to cutting, grinding and other processes; and about 30wt.% of the waste is sludge waste. NdFeB sludge waste contains about 30% rare earth elements (of which Nd accounts for about 90%, and the rest are Pr, Dy and Tb), which is a high-value potential rare earth secondary resource. NdFeB sludge waste contains impurities such as oil, water, emulsified waste liquid, and adhesives. Stacking and treatment are easy to pollute soil and groundwater; and when exposed to air, there is a risk of spontaneous combustion. Therefore, appropriate pretreatment must be carried out to facilitate subsequent recycling and reuse.

[0003] The pretreatment process of NdFeB oil sludge waste in the prior art inevitably uses a water-based cleaning solution, which not only leads to the oxidation of rare earth alloys in the NdFeB waste, resulting in low purity of the recovered NdFeB powder, but also produces a large amount of wastewater, which is not environmentally friendly.

[0004] Therefore, it is necessary to develop an environmentally friendly pretreatment method for NdFeB oil sludge waste with low content of impurities such as C, O, and H. Summary of the invention

[0005] The present invention aims to provide a pretreatment method for NdFeB oil sludge waste, which can efficiently remove impurities such as oil and water in the NdFeB oil sludge waste, has a low content of impurity elements such as C, O, and H, and is environmentally friendly.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The present invention provides a method for pretreating NdFeB oil sludge waste, the method comprising:

[0008] The NdFeB oil sludge waste is subjected to solid-liquid separation to obtain liquid and solid NdFeB oil sludge;

[0009] Adding an organic solvent to the solid NdFeB oil sludge to carry out leaching under stirring conditions, followed by post-filtration and / or suction filtration to obtain a leaching solution and NdFeB waste;

[0010] The NdFeB waste is vacuum dried and then sieved to remove impurities to obtain NdFeB powder.

[0011] Furthermore, the organic solvent includes at least one of n-hexane, cyclohexane, n-heptane, acetone, gasoline, ether and petroleum ether.

[0012] Furthermore, the ratio of the volume of the organic solvent to the mass of the solid NdFeB sludge is (2-8): 1 L / g.

[0013] Furthermore, the extraction temperature satisfies: 20°C ≤ extraction temperature < boiling point of the organic solvent.

[0014] Furthermore, the stirring condition includes mechanical stirring, and the rate of the mechanical stirring is 50 to 120 r / min.

[0015] Furthermore, the extract is heated and evaporated to separate the organic solvent for recycling.

[0016] Furthermore, the extraction is performed 1 to 6 times.

[0017] Furthermore, the solid-liquid separation includes: centrifugation at 6000-8000 r / min for 10-60 min.

[0018] Furthermore, the vacuum drying temperature is 40-80° C., and the vacuum drying temperature is lower than the boiling point of the organic solvent.

[0019] Furthermore, the sieving uses a sieve with a mesh size of 100 to 400.

[0020] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0021] The present invention provides a pretreatment method for NdFeB oil sludge waste, the method comprising: performing solid-liquid separation on the NdFeB oil sludge waste to obtain liquid and solid NdFeB oil sludge; adding an organic solvent to the solid NdFeB oil sludge for leaching under stirring conditions, followed by filtering and / or suction filtration to obtain an extract and NdFeB waste; vacuum drying the NdFeB waste, followed by sieving to remove impurities, to obtain NdFeB powder. The present invention abandons the commonly used water-based cleaning solution in the prior art, creatively utilizes recyclable organic solvents to leaching the NdFeB oil sludge waste, and obtains clean NdFeB powder through simple centrifugation, leaching, drying and sieving. The reagent cost used in the method of the present invention is low, the impact on the environment and the waste itself is small, and the treated NdFeB waste has low carbon, hydrogen, oxygen and other impurity contents, thereby achieving the purpose of purification. This method has a short process flow, simple operation, high product purity, recyclable solvent, is environmentally friendly, has considerable economic, social and environmental protection benefits, and meets the needs of large-scale commercial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 The present invention provides a flow chart of a method for pretreating NdFeB oil sludge waste. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below in conjunction with specific implementations and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific implementations and examples are used to illustrate the present invention, rather than to limit the present invention.

[0025] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

[0026] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or obtained by existing methods.

[0027] The embodiment of the present invention provides a method for pretreating NdFeB oil sludge waste, and the overall idea is as follows:

[0028] According to a typical embodiment of the present invention, a method for pretreating NdFeB oil sludge waste is provided, such as Figure 1 As shown, the method includes:

[0029] S1, performing solid-liquid separation on the NdFeB oil sludge waste to obtain liquid and solid NdFeB oil sludge;

[0030] In the step S1,

[0031] As a specific implementation, the solid-liquid separation includes: centrifuging at 6000-8000 r / min for 10-60 minutes. Under this condition, the liquid and solid NdFeB sludge can be simply separated. If the centrifugal rate is too low and the centrifugal time is too short, it is not conducive to separating the liquid. If the centrifugal rate is too high and the centrifugal time is too long, it will have the adverse effect of high energy consumption.

[0032] No additional distilled water needs to be added during the centrifugation step. Since the NdFeB oil sludge waste has a low moisture content and no new phase is generated, the original NdFeB alloy phase can be well retained.

[0033] In other embodiments, the solid-liquid separation may also be performed in other ways.

[0034] S2, adding an organic solvent to the solid NdFeB oil sludge to perform leaching under stirring conditions, and then filtering and / or suction filtering to obtain a leaching solution and NdFeB waste;

[0035] In the step S2,

[0036] The organic solvent comprises at least one of n-hexane, cyclohexane, n-heptane, acetone, gasoline, ether and petroleum ether. If two or more of the above organic solvents are selected at the same time, the volume ratio between the multiple organic solvents can be any ratio.

[0037] The ratio of the volume of the organic solvent to the mass of the solid NdFeB sludge is (2-8): 1 L / g. The purpose of the leaching is to dissolve and remove oily impurities in the sludge waste, and at the same time separate the water impurities in the sludge waste to facilitate their removal;

[0038] If the amount of organic solvent added is too little, the number of repeated extractions of the NdFeB sludge will increase. If the amount of organic solvent added is too much, high energy consumption will result during its recovery.

[0039] The leaching temperature satisfies: 20°C ≤ leaching temperature < boiling point of the organic solvent. As a specific implementation, the leaching can be carried out at room temperature.

[0040] The stirring condition includes mechanical stirring, and the mechanical stirring rate is 50-300 r / min. The mechanical stirring rate is conducive to sufficient leaching;

[0041] The organic solvent is separated from the extract by heating and evaporation for recycling.

[0042] The number of times of leaching and filtering is 1 to 6 times.

[0043] S3, vacuum drying the NdFeB waste, and then sieving to remove impurities to obtain NdFeB powder.

[0044] The vacuum drying temperature is 40-80°C, and the vacuum drying temperature is lower than the boiling point of the organic solvent. The drying temperature depends on the organic solvent used. Generally, the drying temperature is lower than or close to the boiling point of the organic solvent used, which is conducive to reducing energy consumption;

[0045] The sieving adopts a sieve with a mesh number of 100 to 400 meshes; the reason for adopting a mesh number of 100 to 400 meshes is that the particle size of the purified waste is mainly distributed in 150 to 400 meshes, and a mesh number that is too small loses the screening effect on non-NdFeB waste, and a mesh number that is too large will intercept part of the NdFeB waste, resulting in waste loss;

[0046] The present invention abandons the commonly used water-based cleaning liquid in the prior art, and creatively uses recyclable organic solvents to leaching NdFeB oil sludge waste, and obtains clean NdFeB powder through simple centrifugation, leaching, drying and screening. The reagents used in the method of the present invention are low in cost, have little impact on the environment and the waste itself, and the treated NdFeB waste has low carbon, hydrogen, oxygen and other impurity contents, achieving the purpose of purification. The method has a short process flow, simple operation, high product purity, and recyclable solvents, is environmentally friendly, has considerable economic, social, and environmental protection benefits, and meets the needs of large-scale commercial applications.

[0047] The following is a detailed description of a method for pretreating NdFeB oil sludge waste of the present application in combination with embodiments, comparative examples and experimental data.

[0048] Example 1

[0049] (1) Centrifugation: Place the NdFeB oil sludge waste in a plate centrifuge and centrifuge at 6000 r / min for 20 min to obtain simply separated liquid and solid NdFeB oil sludge;

[0050] (2) Extraction: adding n-hexane to the solid NdFeB sludge obtained in step (1) of Example 1 at a ratio of solid NdFeB sludge (mass): n-hexane (volume) of 1:2, stirring thoroughly, and extracting sludge impurities in the NdFeB sludge;

[0051] (3) Filtration and / or suction filtration: By filtering, a leaching solution and NdFeB waste are obtained; this "leaching-filtration" step is repeated 6 times, and the leaching solution is heated and evaporated to separate the n-hexane, which is recycled;

[0052] (4) Drying: The NdFeB waste obtained in step (3) of Example 1 is vacuum dried at 40° C. and sieved through a 100-mesh sieve to obtain NdFeB powder.

[0053] Example 2

[0054] (1) Centrifugation: Place the NdFeB oil sludge waste in a plate centrifuge and centrifuge at 6000 r / min for 20 min to obtain simply separated liquid and solid NdFeB oil sludge;

[0055] (2) Extraction: adding n-hexane to the solid NdFeB sludge obtained in step (1) of Example 2 at a ratio of solid NdFeB sludge (mass): n-hexane (volume) of 1:4, stirring thoroughly, and extracting the sludge impurities in the NdFeB sludge;

[0056] (3) Filtration and / or suction filtration: obtain a leaching solution and NdFeB waste by suction filtration; repeat this "leaching-suction filtration" step 4 times, separate the n-hexane from the leaching solution by heating and evaporation, and recycle it;

[0057] (4) Drying: The NdFeB waste obtained in step (3) of Example 2 is vacuum dried at 60° C. and sieved through a 200-mesh sieve to obtain NdFeB powder.

[0058] Example 3

[0059] (1) Centrifugation: Place the NdFeB oil sludge waste in a plate centrifuge and centrifuge at 6000 r / min for 20 min to obtain simply separated liquid and solid NdFeB oil sludge;

[0060] (2) Extraction: adding petroleum ether to the solid NdFeB sludge obtained in step (1) of Example 3 at a ratio of solid NdFeB sludge (mass): petroleum ether (volume) of 1:8, stirring thoroughly, and extracting the sludge impurities in the NdFeB sludge;

[0061] (3) Filtration and / or suction filtration: obtain the leaching solution and NdFeB waste by suction filtration; repeat this "leaching-suction filtration" step twice, separate the petroleum ether from the leaching solution by heating and evaporation, and recycle it;

[0062] (3) Drying: The NdFeB waste obtained in step (3) of Example 3 was vacuum dried at 80° C. and sieved through a 400-mesh sieve to obtain NdFeB powder.

[0063] Example 4

[0064] (1) Centrifugation: Place the NdFeB oil sludge waste in a plate centrifuge and centrifuge at 6000 r / min for 20 min to obtain simply separated liquid and solid NdFeB oil sludge;

[0065] (2) Extraction: Add a mixed solvent of acetone and n-hexane to the solid NdFeB sludge obtained in step (1) of Example 4 in a ratio of 1:4: acetone 50% + n-hexane 50% (volume), stir thoroughly, and extract the sludge impurities in the NdFeB sludge;

[0066] (3) Filtration and / or suction filtration: Obtain a leaching solution and NdFeB waste by suction filtration; repeat this "leaching-suction filtration" step 3 times, separate acetone and n-hexane from the leaching solution by heating and evaporation, and recycle them;

[0067] (3) Drying: The NdFeB waste obtained in step (3) of Example 4 was vacuum dried at 80° C. and sieved through a 400-mesh sieve to obtain NdFeB powder.

[0068] Comparative Example 1

[0069] In this comparative example, except that the ratio of the solid NdFeB sludge (mass): n-hexane (volume) is changed to 1:1, other steps are the same as those in Example 1.

[0070] Comparative Example 2

[0071] In this comparative example, except that the n-hexane is replaced by anhydrous ethanol, the other steps are the same as those of Example 1.

[0072] Experimental Example 1

[0073] The NdFeB powder finally obtained in each example was tested for carbon (C), hydrogen (H) and oxygen (O) contents, and the statistics are shown in Table 1.

[0074] Table 1

[0075]

[0076] From the data in Table 1, we can see that

[0077] In Comparative Example 1, the ratio of solid NdFeB sludge (mass): n-hexane (volume) is less than that in Example 1 of the present invention: (2 to 8), and there is a disadvantage that the pretreated NdFeB powder has a high content of carbon (C), hydrogen (H) and oxygen (O);

[0078] In Comparative Example 2, the organic solvent selected is not suitable and cannot effectively remove the oily impurities in the solid NdFeB sludge, resulting in a high content of carbon (C), hydrogen (H) and oxygen (O) in the pretreated NdFeB powder;

[0079] In Examples 1-4 of the present invention, the carbon (C), hydrogen (H) and oxygen (O) contents in the pretreated NdFeB powder are relatively low, which meets the conditions for the subsequent recycling of the NdFeB powder.

[0080] In summary, the pretreatment method of NdFeB oil sludge waste provided by the present invention can efficiently remove impurities such as oil and water in NdFeB oil sludge waste, and the process flow is short, the solvent can be recycled, and it has significant industrial advantages.

[0081] Finally, it should be noted that the terms "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.

[0082] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0083] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for pretreating NdFeB oil sludge waste, characterized in that: The method comprises: The NdFeB oil sludge waste is subjected to solid-liquid separation to obtain liquid and solid NdFeB oil sludge; An organic solvent is added to the solid NdFeB sludge to carry out leaching under stirring conditions, followed by filtering and / or suction filtration to obtain a leaching solution and NdFeB waste; wherein the organic solvent comprises at least one of n-hexane, cyclohexane, n-heptane, acetone, gasoline, ether and petroleum ether; the ratio of the volume of the organic solvent to the mass of the solid NdFeB sludge is (2-8): 1 L / g; the leaching temperature satisfies: 20°C≤leaching temperature<boiling point of the organic solvent; The NdFeB waste is vacuum dried and then sieved to remove impurities to obtain NdFeB powder.

2. The method for pretreating NdFeB oil sludge waste according to claim 1, characterized in that: The stirring condition includes mechanical stirring, and the rate of the mechanical stirring is 50-300 r / min.

3. The pretreatment method of NdFeB oil sludge waste according to claim 1, characterized in that: The organic solvent is separated from the extract by heating and evaporation for recycling.

4. The method for pretreating NdFeB oil sludge waste according to claim 1, characterized in that: The number of leaching is 1 to 6 times, which is adjusted according to the ratio of the volume of the added organic solvent to the mass of the solid NdFeB sludge.

5. The method for pretreating NdFeB oil sludge waste according to claim 1, characterized in that: The solid-liquid separation comprises: centrifuging at 6000-8000 r / min for 10-60 min.

6. The method for pretreating NdFeB oil sludge waste according to claim 1, characterized in that: The vacuum drying temperature is 40-80° C., and the vacuum drying temperature is lower than the boiling point of the organic solvent.

7. The method for pretreating NdFeB oil sludge waste according to claim 1, characterized in that: The sieving is performed using a sieve with a mesh number of 100 to 400.

Images