Method for enhancing leaching of rare earth elements from NdFeB waste by sulphate roasting and surfactant

Abstract

The present application discloses a method for strengthening the leaching of rare earth elements from NdFeB waste by sulphate roasting and surfactant, and belongs to the field of rare earth recovery technology. The method comprises the following steps: mixing NdFeB waste with concentrated sulfuric acid to obtain a roasting raw material; then roasting the roasting raw material to obtain a roasting product; mixing the roasting product with a leaching agent and leaching, filtering, and obtaining a filter residue and a filtrate, and the filtrate is directly used for leaching rare earth elements from NdFeB waste; the leaching agent comprises at least two surfactants. The method provided in the present application can effectively improve the rare earth leaching rate by compounding a plurality of surfactants and coordinating the sulphate roasting process, and can reduce acid consumption to achieve the purpose of improving the purity of rare earth element recovery; and the compounded surfactant described in the present application has a simple preparation method, is easy to use, and greatly reduces the cost of recycling NdFeB waste.

Description

Technical Field

[0001] The present application relates to the field of rare earth recovery technology, and in particular to a method for enhancing the leaching of rare earth elements from NdFeB waste materials by synergistically combining sulfuric acid roasting with a surfactant. Background Art

[0002] NdFeB magnets are widely used in small electronic devices. With the rapid iteration of electronic products, the amount of waste has increased. In addition, about 20% to 30% of waste is generated during the production process, making the recovery of valuable metals in NdFeB magnet waste particularly important. This not only helps to improve the utilization rate of rare earth resources, but also has significant economic benefits. Currently, rare earth elements are mainly recovered through technologies such as hydrochloric acid optimal dissolution, full dissolution or sulfuric acid double salt method, especially sulfuric acid roasting method. This method uses supersulfate roasting combined with water leaching process to treat NdFeB waste. By adjusting the acidity and roasting temperature, iron is converted into Fe2O3, while rare earth is converted into rare earth sulfate. Subsequently, rare earth and iron are effectively separated through water leaching step. However, the current sulfate roasting process faces many challenges, including large sulfuric acid consumption, great pollution to the environment, long processing flow, low rare earth recovery rate and high cost. In addition, there is also the problem that iron slag is difficult to reuse. Summary of the invention

[0003] In order to solve at least one of the above technical problems, the present application develops a method for enhancing the leaching of rare earth elements from NdFeB waste by sulphate roasting and surfactant synergistically, which is simple to operate, low in cost, environmentally friendly and has a high rare earth recovery rate.

[0004] On the one hand, the present application provides a method for leaching rare earth elements from NdFeB waste by sulphate roasting and surfactant synergistically strengthening the leaching of rare earth elements, the method comprising the following steps:

[0005] S1, mixing NdFeB waste and concentrated sulfuric acid to obtain a roasting raw material;

[0006] S2, calcining the calcined raw material described in step S1 to obtain a calcined product;

[0007] S3, mixing the roasted product in step S2 with a leaching agent, leaching, filtering, and obtaining a filter residue and a filtrate, wherein the filtrate is directly used for leaching rare earth elements from NdFeB waste;

[0008] Wherein, the leaching agent in step S3 includes a compound surfactant;

[0009] The compound surfactant comprises at least two surfactants.

[0010] By adopting the above technical scheme, in order to solve the problems existing in the prior art, the present application proposes a method for leaching rare earth elements in NdFeB waste by sulphate roasting and surfactant synergistically strengthening the leaching of rare earth elements, which is simple to operate, low in cost, environmentally friendly and can improve the recovery rate of rare earths. The method first mixes the NdFeB waste with concentrated sulfuric acid to prepare a roasting raw material, then roasts the roasting raw material to form a roasting product that is easy to subsequently process, and then uses a composite leaching agent containing at least two surfactants to mix with the roasting product and leach, and separates the filter residue and the filtrate rich in rare earth elements by filtering, and the filtrate can be directly used for further separation and extraction of rare earth elements. This technical scheme enhances the leaching efficiency of rare earth elements by introducing a composite surfactant, simplifies the operation process, reduces the processing cost, and reduces the impact on the environment, while improving the recovery rate of rare earth elements.

[0011] Optionally, the compound surfactant in step S3 includes at least two of the following surfactants;

[0012] Sodium dodecyl sulfate, linear alkylbenzene sulfonic acid, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, dodecyldimethylbetaine, laurylamidopropylbetaine, fatty alcohol polyoxyethylene ether, fatty acid glyceride, Tween 80, fatty acid sorbitan and perfluorooctanoate.

[0013] By adopting the above technical scheme, the present application provides a method for improving the leaching rate of rare earth elements in NdFeB waste, wherein the composite surfactant used in step S3 at least includes sodium dodecyl sulfate, linear alkylbenzene sulfonic acid, hexadecyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl dimethyl betaine, lauryl amide propyl betaine, fatty alcohol polyoxyethylene ether, fatty acid glyceride, Tween 80, fatty acid sorbitan and any two of perfluorooctanoate. This method effectively enhances the leaching performance of rare earth elements by utilizing the synergistic effect between different types of surfactants, not only improves the recovery rate of rare earth elements, but also simplifies the process, reduces the processing cost, reduces the amount of chemical reagents used, thereby reducing the burden on the environment. Such technical improvements are of great significance for realizing the efficient recovery of valuable metals in NdFeB waste, and also contribute to environmental protection.

[0014] Optionally, the compound surfactant in step S3 includes at least three surfactants.

[0015] Optionally, the compound surfactant in step S3 includes at least three of the following surfactants;

[0016] Sodium lauryl sulfate, linear alkylbenzene sulfonic acid, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, dodecyldimethylbetaine, laurylamidopropylbetaine, fatty alcohol polyoxyethylene ether, fatty acid glyceride, Tween 80 and fatty acid sorbitan.

[0017] By adopting the above technical scheme, the present application can more effectively promote the leaching of rare earth elements in NdFeB waste by selecting a combination of multiple surfactants, and enhance the leaching effect. This method can not only improve the recovery rate of rare earth elements, but also reduce the use of single chemicals due to the possible synergy between surfactants, thereby reducing processing costs and environmental impact. In addition, the multi-component surfactant system also helps to improve the selectivity of the leaching process, making it easier to separate rare earth elements from other components such as iron, thereby simplifying the subsequent treatment process and improving the economy and environmental protection of the entire recovery process.

[0018] Optionally, the compound surfactant in step S3 includes at least four surfactants.

[0019] Optionally, the compounded surfactant in step S3 is selected from one of the following conditions:

[0020] The composite surfactant includes four of sodium dodecyl sulfate, linear alkylbenzene sulfonic acid, hexadecyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl dimethyl betaine, lauryl amide propyl betaine, fatty alcohol polyoxyethylene ether, fatty acid glyceride and Tween 80;

[0021] or,

[0022] The composite surfactant includes four of sodium dodecyl sulfate, linear alkylbenzene sulfonic acid, hexadecyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl dimethyl betaine, lauryl amide propyl betaine, fatty alcohol polyoxyethylene ether and fatty acid glyceride;

[0023] or,

[0024] The composite surfactant includes four of sodium dodecyl sulfate, linear alkylbenzene sulfonic acid, hexadecyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl dimethyl betaine, lauryl amide propyl betaine and fatty alcohol polyoxyethylene ether;

[0025] or,

[0026] The compound surfactant comprises four of sodium dodecyl sulfate, linear alkylbenzene sulfonic acid, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, dodecyldimethylbetaine and laurylamidopropylbetaine.

[0027] By adopting the above technical scheme and selecting a suitable surfactant combination, the leaching efficiency of rare earth elements can be effectively enhanced and the recovery rate can be improved, while the use of chemicals can be reduced, the processing cost can be reduced, and the impact on the environment can be mitigated, thereby achieving a more economical and environmentally friendly NdFeB waste treatment method.

[0028] Optionally, the four surfactants in step S3 are selected from the following surfactants in parts by weight:

[0029] 1-3 parts of sodium lauryl sulfate;

[0030] 0.5-1.5 parts of linear alkylbenzene sulfonic acid;

[0031] 0.5-1.5 parts of hexadecyltrimethylammonium bromide;

[0032] 1-1.5 parts of dodecyltrimethylammonium bromide;

[0033] 0.5-1.5 parts of dodecyl dimethyl betaine;

[0034] 1-3 parts of lauramidopropyl betaine.

[0035] By adopting the above technical scheme, the present application provides a method for optimizing the leaching rate of rare earth elements in NdFeB waste, especially by selecting a combination of four surfactants in step S3, the leaching efficiency of rare earth elements can be significantly improved. This method utilizes the common effect between different surfactants, not only enhances the solubility of rare earth elements, but also improves the leaching selectivity, making the separation of rare earth elements from other metal components such as iron more effective. Thus, the technical scheme not only improves the recovery rate of rare earth elements, simplifies the processing flow, reduces the overall processing cost, but also reduces the use of chemicals, thereby reducing the potential harm to the environment, and overall achieves a more economical and environmentally friendly NdFeB waste treatment effect.

[0036] Optionally, the dosage of the concentrated sulfuric acid and the compound surfactant is as follows:

[0037] The mass ratio of concentrated sulfuric acid to NdFeB waste is 1:(10-15);

[0038] The mass ratio of the compound surfactant to the NdFeB waste is 1:(100000-200000).

[0039] By adopting the above technical scheme, the present application provides an optimized leaching method of rare earth elements in NdFeB waste, and the leaching efficiency of rare earth elements is significantly improved by rationally configuring the ratio of concentrated sulfuric acid to NdFeB waste and the ratio of compound surfactant to NdFeB waste. This method ensures sufficient reaction activity to promote the dissolution of rare earth elements in NdFeB waste by controlling the amount of sulfuric acid, while avoiding environmental problems and additional costs caused by excessive sulfuric acid. The application of compound surfactant further enhances the leaching effect of rare earth elements, and its unique chemical properties help to destroy the adsorption force on the surface of NdFeB waste, thereby promoting the desorption and migration of rare earth ions. This method not only effectively improves the recovery rate of rare earth elements, but also simplifies the processing flow, reduces the processing cost, and reduces the impact on the environment by reducing the excessive use of chemical reagents, making the entire NdFeB waste treatment process more economical and environmentally friendly.

[0040] Optionally, the NdFeB waste includes oil sludge, water abrasive, material heads, ultrafine powder and chamfering mud.

[0041] Optionally, the NdFeB waste material has the following contents, by mass percentage, of each component: 8-12% oil sludge, 30-40% water abrasive, 25-30% material heads, 10-15% ultrafine powder, and 5-10% chamfering mud.

[0042] In summary, the present invention includes at least one of the following beneficial technical effects.

[0043] In order to solve the problems existing in the prior art, the present application proposes a method for strengthening the leaching of rare earth elements in NdFeB waste by sulphate roasting and surfactant, which is simple to operate, low in cost, environmentally friendly and can improve the recovery rate of rare earths. The method first mixes the NdFeB waste with concentrated sulfuric acid to prepare a roasting raw material, then roasts the roasting raw material to form a roasting product that is easy to subsequently process, and then uses a composite leaching agent containing at least two surfactants to mix with the roasting product and leach, and separates the filter residue and the filtrate rich in rare earth elements by filtering, and the filtrate can be directly used for further separation and extraction of rare earth elements. This technical solution enhances the leaching efficiency of rare earth elements by introducing a composite surfactant, simplifies the operation process, reduces the processing cost, and reduces the impact on the environment, while improving the recovery rate of rare earth elements. DETAILED DESCRIPTION

[0044] The present application is further described in detail below with reference to the embodiments.

[0045] In order to make the purpose, technical solution and advantages of the present application more clear, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

[0046] The selection of comparative examples recorded here generally selects the closest prior art or the currently commercially available product provided by the applicant.

[0047] Sodium lauryl sulfate (151-21-3);

[0048] Linear alkylbenzene sulfonic acid (68584-22-5);

[0049] Hexadecyltrimethylammonium bromide (57-09-0);

[0050] Dodecyltrimethylammonium bromide (10182-91-9);

[0051] Dodecyl dimethyl betaine (66455-29-6);

[0052] Lauramidopropyl betaine (4292-10-8);

[0053] Fatty alcohol polyoxyethylene ether (37335-03-8);

[0054] Fatty acid glycerides (2190-20-7);

[0055] Twain 80 (9005-65-6);

[0056] Fatty acid sorbitan (1338-43-8);

[0057] Potassium perfluorooctanoate (2395-00-8);

[0058] Sodium perfluorooctanoate (335-95-5).

[0059] The present application provides a method for enhancing the leaching of rare earth elements from NdFeB waste by sulphate roasting and surfactant, comprising the following steps:

[0060] S1, mixing NdFeB waste and concentrated sulfuric acid to obtain a roasting raw material;

[0061] S2, calcining the calcined raw material in step S1 to obtain a calcined product;

[0062] S3, mixing the roasted product in step S2 with a leaching agent, leaching, filtering, and obtaining a filter residue and a filtrate, wherein the filtrate is directly used for leaching rare earth elements from NdFeB waste;

[0063] Wherein, the leaching agent in step S3 includes a compound surfactant;

[0064] The compound surfactant includes at least two surfactants.

[0065] In order to solve the problems existing in the prior art, the present application proposes a method for strengthening the leaching of rare earth elements in NdFeB waste by sulphate roasting and surfactant, which is simple to operate, low in cost, environmentally friendly and can improve the recovery rate of rare earths. The method first mixes the NdFeB waste with concentrated sulfuric acid to prepare a roasting raw material, then roasts the roasting raw material to form a roasting product that is easy to subsequently process, and then uses a composite leaching agent containing at least two surfactants to mix with the roasting product and leach, and separates the filter residue and the filtrate rich in rare earth elements by filtering, and the filtrate can be directly used for further separation and extraction of rare earth elements. This technical solution enhances the leaching efficiency of rare earth elements by introducing a composite surfactant, simplifies the operation process, reduces the processing cost, and reduces the impact on the environment, while improving the recovery rate of rare earth elements.

[0066] In an embodiment of the present application, the leaching agent in step S3 includes water and a compound surfactant, wherein the mass ratio of the compound surfactant to water is (8-10):1000.

[0067] Illustratively, the mass ratio of the compound surfactant to water is 8:1000, 9:1000, 10:1000 or a range consisting of any two of the above values.

[0068] In an embodiment of the present application, the compounded surfactant in step S3 includes at least two of the following surfactants;

[0069] Sodium dodecyl sulfate, linear alkylbenzene sulfonic acid, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, dodecyldimethylbetaine, laurylamidopropylbetaine, fatty alcohol polyoxyethylene ether, fatty acid glyceride, Tween 80, fatty acid sorbitan and perfluorooctanoate.

[0070] In an embodiment of the present application, the compounded surfactant in step S3 includes at least three surfactants.

[0071] In an embodiment of the present application, the compounded surfactant in step S3 includes at least three of the following surfactants;

[0072] Sodium lauryl sulfate, linear alkylbenzene sulfonic acid, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, dodecyldimethylbetaine, laurylamidopropylbetaine, fatty alcohol polyoxyethylene ether, fatty acid glyceride, Tween 80 and fatty acid sorbitan.

[0073] In an embodiment of the present application, the compounded surfactant in step S3 includes at least four surfactants.

[0074] In an embodiment of the present application, the compounded surfactant in step S3 is selected from one of the following conditions:

[0075] The compound surfactant includes four of sodium dodecyl sulfate, linear alkylbenzene sulfonic acid, hexadecyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl dimethyl betaine, lauryl amide propyl betaine, fatty alcohol polyoxyethylene ether, fatty acid glyceride and Tween 80;

[0076] or,

[0077] The compound surfactant includes four of sodium dodecyl sulfate, linear alkylbenzene sulfonic acid, hexadecyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl dimethyl betaine, lauryl amide propyl betaine, fatty alcohol polyoxyethylene ether and fatty acid glyceride;

[0078] or,

[0079] The compound surfactant includes four of sodium dodecyl sulfate, linear alkylbenzene sulfonic acid, hexadecyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl dimethyl betaine, lauryl amide propyl betaine and fatty alcohol polyoxyethylene ether;

[0080] or,

[0081] The compound surfactant includes four of sodium dodecyl sulfate, linear alkylbenzene sulfonic acid, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, dodecyldimethylbetaine and laurylamidopropylbetaine.

[0082] In an embodiment of the present application, the four surfactants in step S3 are selected from the following surfactants in parts by weight:

[0083] 1-3 parts of sodium lauryl sulfate;

[0084] 0.5-1.5 parts of linear alkylbenzene sulfonic acid;

[0085] 0.5-1.5 parts of hexadecyltrimethylammonium bromide;

[0086] 1-1.5 parts of dodecyltrimethylammonium bromide;

[0087] 0.5-1.5 parts of dodecyl dimethyl betaine;

[0088] 1-3 parts of lauramidopropyl betaine.

[0089] Illustratively, the weight parts of sodium lauryl sulfate are 1.0 parts, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts or a range consisting of any two of the above values.

[0090] Illustratively, the weight proportion of the linear alkylbenzene sulfonic acid is 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 or a range consisting of any two of the above values.

[0091] Exemplarily, the weight proportion of hexadecyltrimethylammonium bromide is 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 or a range consisting of any two of the above values.

[0092] Illustratively, the weight proportion of dodecyltrimethylammonium bromide is 1.0 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts or a range consisting of any two of the above values.

[0093] Illustratively, the weight proportion of dodecyl dimethyl betaine is 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, or a range consisting of any two of the above values.

[0094] Illustratively, the weight parts of lauramidopropyl betaine are 1.0 parts, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts or a range consisting of any two of the above values.

[0095] In some embodiments, the amounts of concentrated sulfuric acid and the compound surfactant are as follows:

[0096] The mass ratio of concentrated sulfuric acid to NdFeB waste is 1:(10-15);

[0097] The mass ratio of the compound surfactant to the NdFeB waste is 100,000-200,000.

[0098] For example, the mass ratio of concentrated sulfuric acid to NdFeB waste is 1:10, 1:11, 1:12,

[0099] 1:13, 1:14, 1:15, or a range of any two of these values.

[0100] In some embodiments, the mass ratio of the compound surfactant to the NdFeB waste is 1:100000, 1:120000, 1:130000, 1:140000, 1:150000, 1:160000, 1:170000, 1:180000, 1:190000, 1:200000 or a range value consisting of any two of the above values.

[0101] In some embodiments, the NdFeB waste includes oil sludge, water-abrasive material, material heads, ultrafine powder, and chamfering mud.

[0102] In some embodiments, the content of each component of the NdFeB waste is calculated by mass percentage: oil sludge 8-12%, water abrasive 30-40%, material head 25-30%, ultrafine powder 10-15%, and chamfering mud 5-10%. Specific embodiments

[0104] The following examples more specifically describe the disclosure of the present application, which are intended for illustrative purposes only, as it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the disclosure of the present application. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0105] Preparation Example 1-23, preparation of compound surfactant;

[0106] Preparation Example 1

[0107] This preparation example provides 0.1 g of a compound surfactant, which is prepared by mixing two different surfactants (respectively a first surfactant and a second surfactant).

[0108] The two different surfactants are 0.05 g of sodium dodecyl sulfate (called the first surfactant) and 0.05 g of linear alkylbenzene sulfonic acid (called the second surfactant); the weight ratio is 1:1.

[0109] Preparation Example 2-7

[0110] In Preparation Example 2-7, the total weight of the compounded surfactant is 0.1 g. The difference from Preparation Example 1 is that the type or weight ratio of the surfactant is different. The difference is shown in Table 1.

[0111] Table 1 - Differences between Preparation Example 2-7 and Preparation Example 1

[0112]

[0113] Preparation Example 8

[0114] In this preparation example, the total weight of the compound surfactant is 0.1 g. The difference between this preparation example and Preparation Example 1 is that the compound surfactant in this preparation example is prepared by mixing three different surfactants (respectively, the first surfactant, the second surfactant and the third surfactant).

[0115] The three different surfactants are sodium dodecyl sulfate (called the first surfactant), linear alkylbenzene sulfonic acid (called the second surfactant), and hexadecyltrimethylammonium bromide (called the third surfactant); the weight ratio is 1:1:1.

[0116] Preparation Examples 9-13

[0117] In Preparation Examples 9-13, the total weight of the compounded surfactant is 0.1 g. The difference between Preparation Examples 9-13 and Preparation Example 8 is that the types or weight ratios of the surfactants in the compounded surfactants are different. See Table 2 for the differences.

[0118] Table 2 - Differences between Preparation Examples 9-13 and Preparation Example 8

[0119]

[0120] Preparation Example 14

[0121] In this preparation example, the total weight of the compounded surfactant is 0.1 g.

[0122] The difference between this preparation example and preparation example 8 is that the compound surfactant in this preparation example is prepared by mixing four different surfactants.

[0123] 0.025 g of sodium dodecyl sulfate (SDS), 0.025 g of linear alkylbenzene sulfonic acid (LABSA), 0.025 g of hexadecyltrimethylammonium bromide (CTAB), and 0.025 g of dodecyltrimethylammonium bromide (DTAB) were compounded to prepare a compound surfactant.

[0124] Preparation Example 15

[0125] The difference between this preparation example and preparation example 14 is that the compound surfactant in this preparation example is prepared by compounding the following weights of surfactants.

[0126] The total weight of the compound surfactant in this preparation example is 0.1 g.

[0127] 0.04 g of sodium dodecyl sulfate (SDS), 0.01 g of linear alkylbenzene sulfonic acid (LABSA), 0.02 g of hexadecyltrimethylammonium bromide (CTAB), and 0.03 g of dodecyltrimethylammonium bromide (DTAB) were compounded to prepare a compound surfactant.

[0128] Preparation Example 16

[0129] The difference between this preparation example and preparation example 14 is that the compound surfactant in this preparation example is prepared by compounding the following weights of surfactants.

[0130] The total weight of the compound surfactant in this preparation example is 0.15 g.

[0131] 0.045 g of sodium dodecyl sulfate (SDS), 0.02 g of linear alkylbenzene sulfonic acid (LABSA), 0.02 g of hexadecyltrimethylammonium bromide (CTAB), and 0.03 g of dodecyl dimethyl betaine (BS-12) were compounded to prepare a compound surfactant.

[0132] Preparation Example 17

[0133] The difference between this preparation example and preparation example 14 is that the compound surfactant in this preparation example is prepared by compounding the following weights of surfactants.

[0134] The total weight of the compound surfactant in this preparation example is 0.1 g.

[0135] 0.05 g of sodium dodecyl sulfate (SDS), 0.006 g of linear alkylbenzene sulfonic acid (LABSA), 0.014 g of hexadecyltrimethylammonium bromide (CTAB), and 0.03 g of lauryl amide propyl betaine (CAB-35) were compounded to prepare a compound surfactant.

[0136] Preparation Example 18

[0137] The difference between this preparation example and preparation example 14 is that the compound surfactant in this preparation example is prepared by compounding the following weights of surfactants.

[0138] 0.03 g / kg linear alkylbenzene sulfonic acid (LABSA), 0.02 g / kg hexadecyltrimethylammonium bromide (CTAB), 0.035 g / kg dodecyltrimethylammonium bromide (DTAB), and 0.015 g / kg dodecyldimethylbetaine (BS-12) were compounded to prepare a compound surfactant.

[0139] Preparation Example 19

[0140] The difference between this preparation example and preparation example 14 is that the compound surfactant in this preparation example is prepared by compounding the following weights of surfactants.

[0141] 0.035 g / kg linear alkylbenzene sulfonic acid (LABSA), 0.01 g / kg hexadecyltrimethylammonium bromide (CTAB), 0.03 g / kg dodecyltrimethylammonium bromide (DTAB), and 0.025 g / kg laurylamidopropyl betaine (CAB-35) were compounded to prepare a compound surfactant.

[0142] Preparation Example 20

[0143] The difference between this preparation example and preparation example 14 is that the compound surfactant in this preparation example is prepared by compounding the following weights of surfactants.

[0144] 0.015 g / kg hexadecyltrimethylammonium bromide (CTAB), 0.03 g / kg dodecyltrimethylammonium bromide (DTAB), 0.025 g / kg dodecyldimethyl betaine (BS-12), and 0.03 g / kg laurylamidopropyl betaine (CAB-35) were compounded to prepare a compound surfactant.

[0145] Preparation Example 21

[0146] The difference between this preparation example and preparation example 14 is that the compound surfactant in this preparation example is prepared by compounding the following weights of surfactants.

[0147] The total weight of the compound surfactant in this preparation example is 0.1 g.

[0148] 0.025 g of sodium dodecyl sulfate (SDS), 0.025 g of linear alkylbenzene sulfonic acid (LABSA), 0.025 g of hexadecyltrimethylammonium bromide (CTAB), and 0.025 g of Tween 80 were compounded to prepare a compound surfactant.

[0149] Preparation Example 22

[0150] The difference between this preparation example and preparation example 14 is that the compound surfactant in this preparation example is prepared by compounding the following weights of surfactants.

[0151] The total weight of the compound surfactant in this preparation example is 0.1 g.

[0152] 0.025 g of sodium dodecyl sulfate (SDS), 0.025 g of linear alkylbenzene sulfonic acid (LABSA), 0.025 g of hexadecyltrimethylammonium bromide (CTAB), and 0.025 g of fatty acid glyceride were compounded to prepare a compound surfactant.

[0153] Preparation Example 23

[0154] The difference between this preparation example and preparation example 14 is that the compound surfactant in this preparation example is prepared by compounding the following weights of surfactants.

[0155] The total weight of the compound surfactant in this preparation example is 0.1 g.

[0156] 0.025 g of sodium dodecyl sulfate (SDS), 0.025 g of linear alkylbenzene sulfonic acid (LABSA), 0.025 g of hexadecyltrimethylammonium bromide (CTAB), and 0.025 g of fatty alcohol polyoxyethylene ether were compounded to prepare a compound surfactant.

[0157] Example 1

[0158] This embodiment provides a method for enhancing the leaching of rare earth elements from NdFeB waste by sulphate roasting and surfactant, comprising the following steps:

[0159] S1, mixing concentrated sulfuric acid and NdFeB waste material at a mass ratio of 100 g / kg (represented by T1 in Table 3) to obtain a roasting raw material;

[0160] S2, calcining the calcined raw material in step S1 at 750° C. for 1.5 h (denoted by T2 in Table 3) to obtain a calcined product;

[0161] S3. Mix the roasted product in step S2 with a leaching agent, then leach and filter to obtain a filter residue and a filtrate. The leaching rate of rare earth elements in the filtrate is 83.1%.

[0162] The leaching agent in step S3 is prepared by mixing water and the compound surfactant prepared in Preparation Example 1 (represented by T3 in Table 3).

[0163] The mass ratio of the compound surfactant to water is 9:1000.

[0164] In this embodiment, the mass ratio of the compound surfactant to the NdFeB waste is 1:150000.

[0165] The NdFeB waste in this embodiment has the following contents by mass percentage: 12% oil sludge, 35% water-abrasive, 30% material heads, 15% ultrafine powder, and 8% chamfering mud.

[0166] The compound surfactant used in this example was prepared from Preparation Example 1.

[0167] The difference between Example 2-53 and Example 1 lies in the selection of surfactants and some parameters. The differences are shown in Table 3.

[0168] Table 3 - Differences between Example 2-53 and Example 1

[0169]

[0170] Comparative Experiments 1-9

[0171] Comparative Example 1

[0172] In this comparative example, only the NdFeB waste was roasted in a rotary kiln at 750°C for 1.5 h, and the roasted sand was leached in water, and the leaching rate of rare earth elements was 69.7%. The weight of the NdFeB waste in this comparative example was consistent with that in Example 1.

[0173] Comparative Example 2

[0174] In this comparative example, only the NdFeB waste was poured into a rotary kiln, calcined at 750°C for 2 h, and the obtained calcined sand was leached with water, and the leaching rate of rare earth elements was 73.6%. The weight of the NdFeB waste in this comparative example was consistent with that in Example 1.

[0175] Comparative Example 3

[0176] In this comparative example, only the NdFeB waste was poured into a rotary kiln, calcined at 750°C for 2.5 h, and the obtained calcined sand was leached with water, and the leaching rate of rare earth elements was 72.5%. The weight of the NdFeB waste in this comparative example was consistent with that in Example 1.

[0177] Comparative Example 4

[0178] According to the ratio of concentrated sulfuric acid to NdFeB waste material of 150g / kg, the NdFeB waste material was stirred at room temperature and then roasted at 750°C for 2 h. The roasted sand was leached in water to obtain a rare earth element leaching rate of 82.3%. The weight of the NdFeB waste material in this comparative example is consistent with that in Example 1.

[0179] Comparative Example 5

[0180] According to the ratio of concentrated sulfuric acid to NdFeB waste material of 200g / kg, the NdFeB waste material was stirred at room temperature and then roasted at 750°C for 2 h. The roasted sand was leached in water to obtain a rare earth element leaching rate of 85.4%. The weight of NdFeB waste material in this comparative example is consistent with that in Example 1.

[0181] Comparative Example 6

[0182] According to the ratio of concentrated sulfuric acid to NdFeB waste material of 250g / kg, the NdFeB waste material was stirred at room temperature and then roasted at 750°C for 2 h. The roasted sand was leached in water to obtain a rare earth element leaching rate of 85.2%. The weight of NdFeB waste material in this comparative example is consistent with that in Example 1.

[0183] Comparative Example 7

[0184] The difference between this comparative example and Example 1 is that this comparative example uses an equal amount of hexadecyltrimethylammonium bromide (CTAB) to replace the compound surfactant. The rest is consistent with Example 1. In this comparative example, the leaching rate of rare earth elements is 76.2%.

[0185] Comparative Example 8

[0186] The difference between this comparative example and Example 1 is that this comparative example uses an equal amount of fatty acid sorbitan to replace the compound surfactant. The rest is consistent with Example 1. In this comparative example, the leaching rate of rare earth elements is 72.4%.

[0187] Comparative Example 9

[0188] The difference between this comparative example and Example 1 is that this comparative example uses an equal amount of dodecyltrimethylammonium bromide (DTAB) to replace the compound surfactant. The rest is consistent with Example 1. In this comparative example, the leaching rate of rare earth elements is 75.8%.

[0189] Result analysis: According to the data provided in Examples 1-53, this study proposes a method for enhancing the leaching rate of rare earth elements in NdFeB waste by sulphate roasting and the synergistic effect of surfactants. In this series of embodiments, compound surfactants composed of two, three and four surfactants were used for experiments. The results show that when the types of surfactants contained in the compound surfactants increase from two to three and then to four, the leaching effect of rare earth elements in NdFeB waste is successively enhanced. Specifically, the compound surfactants prepared by compounding two surfactants in Examples 1-7 are not as good as the compound surfactants prepared by compounding three surfactants in Examples 8-13; while the compound surfactants prepared by compounding four surfactants in Example 14 show the best leaching effect. Therefore, it can be concluded that the increase in the types of surfactants in the compound surfactants is conducive to improving the leaching rate of rare earth elements in NdFeB waste, and provides a valuable reference for optimizing rare earth resource recovery technology.

[0190] The experimental test data provided in Examples 15 to 53 show that the mass ratio of concentrated sulfuric acid to NdFeB waste, roasting time and the selection of surfactant can all affect the leaching rate. When the mass ratio of concentrated sulfuric acid to NdFeB waste is 200g / kg and the roasting time is 2h, the leaching rate is better.

[0191] Comparative Examples 1-3 only use roasting method to treat NdFeB waste, and its leaching effect on rare earth elements is significantly lower than the method using sulphation roasting and compound surfactant synergistic effect. Although Comparative Examples 4-6 use concentrated sulfuric acid roasting method, due to the lack of compound surfactant, its leaching effect is not as good as Example 1. Comparative Examples 7-9 only use a single surfactant, and its leaching effect is also poor. In summary, the method of synergistic effect of compound surfactants formed by sulphation roasting and compounding of multiple surfactants can significantly improve the leaching rate of rare earth elements in NdFeB waste, and provides a feasible technical path for the efficient recovery of rare earth resources. In addition, optimizing the mass ratio of concentrated sulfuric acid to NdFeB waste and the appropriate roasting time are also key factors to improve leaching efficiency. These findings are of great significance for promoting the sustainable utilization of rare earth resources.

[0192] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for enhancing the leaching of rare earth elements from NdFeB waste by sulphate roasting and surfactant, characterized in that: The method comprises the following steps: S1, mixing NdFeB waste and concentrated sulfuric acid to obtain a roasting raw material; S2, calcining the calcined raw material described in step S1 to obtain a calcined product; S3, mixing the roasted product in step S2 with a leaching agent, leaching, filtering, and obtaining a filter residue and a filtrate, wherein the filtrate is directly used for leaching rare earth elements from NdFeB waste; Wherein, the leaching agent in step S3 includes a compound surfactant; The compounded surfactant in step S3 includes at least three of the following surfactants; Sodium lauryl sulfate, linear alkylbenzene sulfonic acid, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, dodecyldimethylbetaine, laurylamidopropylbetaine, fatty alcohol polyoxyethylene ether, fatty acid glyceride, Tween 80 and fatty acid sorbitan.

2. The method according to claim 1, characterized in that The compound surfactant in step S3 includes at least four surfactants.

3. The method according to claim 2, characterized in that The compounded surfactant in step S3 is selected from one of the following conditions: The composite surfactant includes four of sodium dodecyl sulfate, linear alkylbenzene sulfonic acid, hexadecyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl dimethyl betaine, lauryl amide propyl betaine, fatty alcohol polyoxyethylene ether, fatty acid glyceride and Tween 80; or, The composite surfactant includes four of sodium dodecyl sulfate, linear alkylbenzene sulfonic acid, hexadecyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl dimethyl betaine, lauryl amide propyl betaine, fatty alcohol polyoxyethylene ether and fatty acid glyceride; or, The composite surfactant includes four of sodium dodecyl sulfate, linear alkylbenzene sulfonic acid, hexadecyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl dimethyl betaine, lauryl amide propyl betaine and fatty alcohol polyoxyethylene ether; or, The compound surfactant comprises four of sodium dodecyl sulfate, linear alkylbenzene sulfonic acid, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, dodecyldimethylbetaine and laurylamidopropylbetaine.

4. The method according to claim 3, characterized in that The four surfactants in step S3 are selected from the following surfactants in parts by weight: 1-3 parts of sodium lauryl sulfate; 0.5-1.5 parts of linear alkylbenzene sulfonic acid; 0.5-1.5 parts of hexadecyltrimethylammonium bromide; 1-1.5 parts of dodecyltrimethylammonium bromide; 0.5-1.5 parts of dodecyl dimethyl betaine; 1-3 parts of lauramidopropyl betaine.

5. The method according to claim 1, characterized in that The dosage of the concentrated sulfuric acid and the composite surfactant is as follows: The mass ratio of concentrated sulfuric acid to NdFeB waste is 1:(10-15); The mass ratio of the compound surfactant to the NdFeB waste is 1:(100000-200000).

6. The method according to claim 1, characterized in that The NdFeB waste materials include oil sludge, water abrasive, material heads, ultrafine powder and chamfering mud.

7. The method according to claim 6, characterized in that The NdFeB waste material has the following contents by mass percentage: 8-12% oil sludge, 30-40% water abrasive, 25-30% material head, 10-15% ultrafine powder and 5-10% chamfering mud.

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