Method for non-aqueous phase leaching of neodymium iron boron waste and extraction separation of iron and neodymium

Abstract

The invention relates to a method for non-aqueous phase leaching of NdFeB waste and extraction separation of iron and neodymium. The method comprises the following steps: firstly, putting the NdFeB waste material into a leaching agent consisting of citric acid (CA) and ethylene glycol (EG) in a molar ratio of 1: 10, and then carrying out constant-temperature leaching at 80-180 DEG C for 15-720 minutes; and after leaching is completed, the obtained leachate is cooled to the room temperature, and the required CA-EG leachate rich in the iron ions and the rare earth neodymium ions can be obtained. In addition, neodymium and iron are separated from the leachate through a non-aqueous phase solvent extraction method. Under the optimal leaching condition, the leaching efficiency of iron and neodymium is as high as 98.52% and 95.81% respectively; under the optimal extraction condition, through three-stage cross-flow extraction, the extraction efficiency of iron can reach 99.9%, and the separation coefficient of iron and neodymium reaches up to 3387.15; meanwhile, the reverse extraction efficiency is larger than 90%, and efficient separation of iron and neodymium is achieved; therefore, the invention provides a new method and idea for efficient separation and recovery of iron and neodymium in the NdFeB waste material.

Description

Technical Field

[0001] The invention belongs to a leaching, extracting and separating technology of iron and neodymium in NdFeB secondary resources, and specifically relates to a method for non-aqueous phase leaching and extracting and separating iron and neodymium from NdFeB waste. Background Art

[0002] As a superior magnetic material, NdFeB magnetic material has been widely used in various fields due to its high-strength magnetism and relatively low cost. Its output and demand have also increased in recent years. my country is a major producer and consumer of NdFeB permanent magnet materials in the world. Due to production and use factors, the utilization rate of raw materials in NdFeB production is only about 75%, which means 25% of waste will be generated. Therefore, the total amount of NdFeB waste is increasing year by year. According to statistics, the total amount of NdFeB waste in my country has reached hundreds of thousands of tons, and it will face a rapid growth trend in the future. These wastes contain 20-30% rare earth, 1% to 1% boron, and the rest are iron. Rare earth and iron are non-renewable resources with high utilization value. In addition, my country's annual steel consumption is as high as hundreds of millions of tons, and the import volume of its raw material iron ore is immeasurable.

[0003] There are two main strategies for the comprehensive recovery of NdFeB waste, namely, pyrometallurgy and hydrometallurgy. The pyrometallurgy mainly includes molten metal refining, selective oxidation, chlorination, calcium reduction and phase separation. The molten metal refining method uses low melting point metal as an extractant to extract the neodymium element in the form of an alloy. Through this method, neodymium oxide and molten metallic silver are obtained, and the final neodymium can achieve a recovery rate of more than 90%. Although this method can obtain rare earth metal elements during recovery, the reaction process has extremely high requirements for temperature and equipment, high energy consumption, and the alloy product needs further treatment. The overall process is relatively complicated. The selective oxidation method is to selectively oxidize rare earth elements to recover rare earth oxides by controlling the reaction conditions. This method can effectively recover rare earth elements in NdFeB waste to a certain extent, but the recovered rare earth oxide products are not of high purity and often contain iron and boron, which cannot reach the industrial level. The chlorination method uses the stronger affinity of rare earth to chloride ions to convert them into chlorides for recovery. The calcium reduction method is to use reducing calcium to reduce slightly oxidized waste NdFeB and then further sinter it to prepare new NdFeB magnets. Each of the above methods has certain advantages, but due to the high reaction temperature (far greater than 200°C), it consumes a lot of energy and increases costs. In addition, the purity of the product is not high.

[0004] As for the wet process, the first is the full dissolution method, which is to convert all the valuable elements into ions or other soluble complexes, and then separate the valuable elements through extraction and other processes. Although this method is simple to operate, the consumption of hydrochloric acid is large in the process of dissolving the waste. At the same time, a large amount of impurity ions will be dissolved during the dissolution process, which will affect the purity of the rare earth products. The optimal dissolution method uses the different solubility and time of different elements in acid, and rare earth elements are dissolved preferentially. Although the optimal dissolution method can greatly reduce the consumption of acid and alkali, there is a certain contradiction between the selectivity and efficiency of leaching, which will make the oxidative roasting conditions difficult to control and the kinetics of rare earth leaching reactions slow, which greatly limits the deep separation of rare earths and iron. At the same time, NdFeO will be produced during the roasting process. 3 , which is very stable and difficult to be leached. The precipitation method is divided into double salt precipitation, oxalic acid precipitation, coprecipitation, and sulfide precipitation. Although the valuable metals can be recovered to a certain extent, the purity of the product is low and it cannot achieve the deep separation of rare earth and iron.

[0005] Although many important research results have been achieved, there are still problems such as low leaching efficiency, serious environmental pollution, and incomplete separation of iron and neodymium. Therefore, it is urgent to develop a leaching system with excellent performance and an extraction system for efficient separation of iron and neodymium.

[0006] Based on the above reasons, this application is filed. Summary of the invention

[0007] The purpose of the present invention is to overcome the deficiencies of the prior art, and to provide a highly efficient leaching agent and a highly efficient and highly selective non-aqueous solvent extractant for the leachate, thereby achieving efficient separation of iron and neodymium.

[0008] In order to achieve the above first object, the present invention adopts the following technical solution:

[0009] A CA-EG leaching agent for non-aqueous phase leaching of NdFeB waste comprises a hydrogen bond acceptor citric acid (CA) and a hydrogen bond donor ethylene glycol (EG).

[0010] Furthermore, in the above technical solution, the molar ratio of citric acid to ethylene glycol in the leaching agent is in the range of 1 / 5 to 1 / 20; the preferred molar ratio is 1 / 10.

[0011] The second object of the present invention is to provide a non-aqueous phase leaching method for NdFeB waste, the method steps are as follows:

[0012] Mix the NdFeB waste and CA-EG leaching agent according to the proportion, and place the obtained mixed solution 1 at 80-180°C for constant temperature leaching for 15-720 minutes; after the leaching is completed, cool the obtained leaching solution to room temperature.

[0013] Furthermore, in the above technical solution, the liquid-to-solid ratio in the mixed solution 1 is maintained in the range of 5 to 25 g / L, preferably 10 g / L.

[0014] Furthermore, in the above technical solution, the leaching temperature is preferably 160° C., and the leaching time is preferably 120 min.

[0015] The third object of the present invention is to provide a method for extracting and separating iron and neodymium in the above-mentioned leachate using a non-aqueous solvent, the method comprising the following steps:

[0016] (1) diluting the leaching solution and then adding hydrogen peroxide (H 2 O 2 ), stirring fully until the color of the leaching solution does not change, to obtain a leaching dilution; then mixing the leaching dilution with n-heptane containing an extractant according to a ratio, and extracting the obtained mixed solution 2 at 25° C. to 55° C. under shaking conditions for 1 to 40 minutes;

[0017] (2) After the extraction is completed, the lower liquid is separated, and a stripping agent is added to the lower liquid, followed by stripping for 5 to 180 minutes at 25° C. to 55° C. and under shaking conditions; after the stripping is completed, the obtained two phases are separated to achieve separation of iron and neodymium.

[0018] Furthermore, in the above technical solution, in a preferred embodiment of the present invention, the dilution in step (1) refers to diluting it using a CA-EG leaching agent.

[0019] Furthermore, in the above technical scheme, the iron concentration in the leaching dilution solution of step (1) is maintained in the range of 126.79 mg / L to 2014.78 mg / L, preferably 469.37 mg / L; the neodymium concentration is maintained in the range of 37.41 mg / L to 712.83 mg / L, preferably 160.25 mg / L.

[0020] Further, in the above technical solution, the extractant in step (1) is at least one of N235 (tri-n-octylamine) and P350 (dimethylheptyl methylphosphonate). The extractant is preferably a combination of N235 and P350.

[0021] Preferably, in the above technical solution, when the extractant is a combination of N235 and P350, the volume ratio of N235 to P350 is 5:1, 3:1, 1:1, 1:3, 1:5; the preferred volume ratio is 1:1.

[0022] Further, in the above technical solution, the H added to the leaching solution in step (1) 2 O 2 The volume ratio is maintained in the range of 10% to 30%, preferably 30%.

[0023] Specifically, in the above technical solution, the role of adding hydrogen peroxide in step (1) is: after the NdFeB waste is leached, the iron in it is Fe 2+ exists in the solution, adding hydrogen peroxide will make Fe 2+ Transformed into Fe 3+ , which is convenient for subsequent extraction and separation.

[0024] Furthermore, in the above technical solution, the mass fraction of the extractant in the mixed solution 2 in step (1) is maintained in the range of 2% vol% to 20 vol%, preferably 10 vol%.

[0025] Furthermore, in the above technical solution, the extraction time in step (1) is preferably 10 minutes, and the extraction temperature is preferably room temperature.

[0026] Further, in the above technical scheme, in a preferred embodiment of the present invention, the stripping agent in step (2) is a disodium ethylenediaminetetraacetic acid solution, and the concentration of the disodium ethylenediaminetetraacetic acid solution is in the range of 0.02mol / L to 0.4mol / L, preferably 0.02mol / L. The disodium ethylenediaminetetraacetic acid solution is prepared as follows: according to different concentrations (0.02mol / L, 0.04mol / L, 0.06mol / L, 0.08mol / L, 0.1mol / L, 0.2mol / L, 0.3mol / L, 0.4mol / L) and required volumes (for example, 20mL), 0.134g, 0.268g, 0.402g, 0.536g, 0.67g, 1.34g, 2.01g, 2.68g of disodium ethylenediaminetetraacetic acid are respectively added to 20mL of deionized water, stirred to dissolve, and the required solutions of different concentrations are obtained.

[0027] Furthermore, in the above technical solution, the stripping temperature in step (2) is preferably room temperature, i.e., 25° C.; and the stripping time is preferably 60 min.

[0028] The present invention first places NdFeB waste in a leaching agent containing CAEG (citric acid-ethylene glycol), leaches at a certain temperature and time, and then dilutes the leaching solution and directly uses it for non-aqueous phase solvent extraction to separate iron and neodymium. The present invention can efficiently leach iron and neodymium in NdFeB waste, and can efficiently separate iron and neodymium therein by non-aqueous phase solvent extraction, thereby providing a cheap and efficient method for separating and recovering iron and neodymium in NdFeB secondary resources.

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] (1) The leaching agent of the present invention can be used in a wide range because ethylene glycol is used as a solvent with a high boiling point and a low melting point. Citric acid is used as the main reactant for leaching and has good biodegradability. Experiments show that the leaching efficiency for iron can reach 98.52%, and the leaching efficiency for neodymium can reach 95.81%.

[0031] (2) The non-aqueous solvent extraction system used in the present invention uses the leaching dilution as one phase of the extraction, and does not require complicated treatment. In addition, N235-P350 is used as the extractant, and the strong selectivity of N235 and the high efficiency of P350 are combined, so that iron can be efficiently extracted from the mixed solution, thereby achieving efficient separation of iron and neodymium. Under the optimal experimental conditions, the extraction efficiency in the leaching solution is as high as 99.9%, and the stripping efficiency is higher than 90%. After stripping, no neodymium can be detected in the stripping phase, achieving deep separation of iron and neodymium.

[0032] (3) In the present invention, the NdFeB waste can be directly used for non-aqueous solvent extraction after leaching, realizing the integrated operation of non-aqueous phase leaching and extraction, greatly shortening the process flow, and providing a new method and idea for the efficient separation and recovery of iron and neodymium in NdFeB waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 This is a graph showing the effect of different CA / EG molar ratios on the leaching efficiency of two metal ions in Example 2 of the present invention;

[0035] Figure 2 This is a diagram showing the effect of different liquid-to-solid ratios on the leaching efficiency of two metal ions in Example 3 of the present invention;

[0036] Figure 3 This is a diagram showing the effect of different leaching temperatures on the leaching efficiency of two metal ions in Example 4 of the present invention;

[0037] Figure 4 This is a graph showing the effect of different leaching times on the leaching efficiency of two metal ions in Example 5 of the present invention;

[0038] Figure 5 This is a graph showing the effect of the type of extractant on the extraction efficiency of iron and neodymium in Example 7 of the present invention;

[0039] Figure 6H in Example 8 of the present invention 2 O 2 Effect of addition amount on extraction efficiency of iron and neodymium;

[0040] Figure 7 Graph showing the effect of the amount of extractant on the extraction efficiency of iron and neodymium in Example 9 of the present invention;

[0041] Figure 8 Graph showing the effect of the concentrations of iron and neodymium in the stock solution on the extraction efficiency of iron and neodymium in Example 10 of the present invention;

[0042] Fig. 9 Graph showing the effect of the extraction system temperature on the extraction efficiency of iron and neodymium in Example 11 of the present invention;

[0043] Fig.10 Graph showing the effect of extraction time on the extraction efficiency of iron and neodymium in Example 12 of the present invention;

[0044] Fig.11 Graph showing the effect of the two-phase volume ratio on the extraction efficiency of iron and neodymium in Example 13 of the present invention;

[0045] Fig.12 is the stripping agent (Na 2 The effect of EDTA concentration on the stripping efficiency of iron;

[0046] Fig.13 Graph showing the effect of stripping temperature (left) and stripping time (right) on the stripping efficiency of iron in Example 15 of the present invention. DETAILED DESCRIPTION

[0047] The present invention relates to a method for non-aqueous phase leaching and extraction separation of iron and neodymium from NdFeB waste. The present invention first places NdFeB waste in a leaching agent composed of citric acid (CA) and ethylene glycol (EG) in a molar ratio of 1:10, and then leaches at a constant temperature of 80 to 180°C for 15 to 720 minutes; after the leaching is completed, the obtained leaching solution is cooled to room temperature to obtain the required CAEG leaching solution rich in iron ions and rare earth neodymium ions. In addition, the present invention also separates neodymium iron from the above-mentioned leaching solution by a non-aqueous phase solvent extraction method, and the extractant is a mixture of N235 and P350 extractants in a volume ratio of 1:1, stirred at room temperature (heat will be released during the stirring process), and when the entire system tends to room temperature, the N235-P350 extractant is obtained.

[0048] The non-aqueous phase leaching system prepared by the present invention has an excellent leaching effect on NdFeB waste, and the leaching solution can be directly used for non-aqueous phase solvent extraction to separate iron and neodymium therein, thereby realizing the integrated operation of leaching and extraction. Under the optimal leaching conditions, the leaching efficiency of iron and neodymium can reach 98.52% and 95.81% respectively; under the optimal extraction conditions, after three-stage cross-current extraction, the extraction efficiency of iron can reach 99.9%, and the separation coefficient of iron and neodymium is as high as 3387.15; at the same time, the stripping efficiency is greater than 90%, achieving efficient separation of iron and neodymium; therefore, the present invention provides a new method and idea for efficient separation and recovery of iron and neodymium in NdFeB waste.

[0049] The following is a detailed description of the implementation case of the present invention in conjunction with the accompanying drawings. This implementation case is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and specific operation process are given, but the protection scope of the present invention is not limited to the following implementation case.

[0050] Based on the information contained in this application, it is easy for those skilled in the art to make various changes to the precise description of the present invention without departing from the spirit and scope of the appended claims. It should be understood that the scope of the present invention is not limited to the defined process, property or component, because these embodiments and other descriptions are only for illustrating specific aspects of the present invention. In fact, various changes that the technicians in this field or related fields can obviously make to the embodiments of the present invention are all covered within the scope of the appended claims.

[0051] In order to better understand the present invention but not to limit the scope of the present invention, all the numbers used in this application to express the amount, percentage, and other numerical values ​​should be understood as modified by the word "about" in all cases. Therefore, unless otherwise specified, the numerical parameters listed in the specification and the appended claims are approximate values, which may be changed according to the different ideal properties attempted to be obtained. Each numerical parameter should at least be regarded as obtained based on the reported significant figures and by conventional rounding methods.

[0052] The starting materials used in the following examples, unless otherwise specified, can be considered to be purchased from commercial sources.

[0053] Example 1

[0054] The preparation method of the CA-EG leaching agent of this embodiment comprises the following steps:

[0055] Citric acid and ethylene glycol were mixed in a molar ratio of 1:10, and the specific volume was quantitatively weighed according to the experimental needs. Then, it was placed at 70°C and magnetically stirred until it became a clear and transparent solution, and then cooled to room temperature to obtain the desired CA-EG leachate.

[0056] The molar ratio of the leaching agent CA-EG is maintained at 1:10 because when the molar ratio is maintained at 1:5, the viscosity of the solution is too large, which is not conducive to the leaching of NdFeB; when the molar ratio is maintained at 1:15 or 1:20, the leaching efficiency of metal ions will be reduced.

[0057] The leaching agents used in the leaching methods of NdFeB waste materials involved in the following Examples 3 to 5 are all prepared by the method of Example 1.

[0058] The NdFeB scrap used in the following examples was purchased from Magnequench (Tianjin) Co., Ltd., item number: MQFP-B-20076-089.

[0059] Example 2

[0060] A leaching method for NdFeB waste, the method comprising the following steps:

[0061] (1) Take four 100 mL beakers, prepare 30 mL of leaching solution with n(CA:EG)=1:5, 1:10, 1:15, and 1:20, respectively, and transfer them to the beakers;

[0062] (2) Take 300 mg of the purchased NdFeB waste and add it to the beaker in (1), stir it evenly with a glass rod, and use ultrasonic dispersion if necessary, and then react at 160°C for 60 minutes;

[0063] (3) After leaching, the leaching solution is cooled naturally, and a small amount is taken and diluted with 3-5% nitric acid solution.

[0064] Take a certain amount of the dilution obtained in step (3) above, use the ICP-OES of this laboratory to detect the concentration of iron and neodymium in the dilution, and calculate the leaching efficiency of iron and neodymium. The results are as follows: Figure 1 shown.

[0065] from Figure 1 It can be seen that the leaching efficiency of iron and neodymium decreases with the decrease of the molar ratio of CA to EG. When the molar ratio changes from 1:5 to 1:20, the leaching efficiency of iron decreases from 98.28% to 40.57%, and the leaching efficiency of neodymium decreases from 97.95% to 41.42%.

[0066] Example 3

[0067] A leaching method for NdFeB waste, the method comprising the following steps:

[0068] (1) Take five 100 mL beakers and pour 30 mL of the leaching agent prepared in Example 1 into each beaker;

[0069] (2) 150 mg, 300 mg, 450 mg, 600 mg, and 750 mg of the purchased NdFeB waste were added to the beaker in (1), stirred evenly with a glass rod, and ultrasonic dispersion was used if necessary, and then reacted at 160°C for 60 min;

[0070] (3) After leaching, the leaching solution is cooled naturally, and a small amount is taken and diluted with 3-5% nitric acid solution.

[0071] Take a certain amount of the dilution obtained in step (3) above, use the ICP-OES of this laboratory to detect the concentration of iron and neodymium in the dilution, and calculate the leaching efficiency of iron and neodymium. The results are as follows: Figure 2 shown.

[0072] from Figure 2 It can be seen that the leaching efficiency of iron and neodymium decreases with the increase of liquid-solid ratio. When the liquid-solid ratio changes from 5g / L to 25g / L, the leaching efficiency of iron decreases from 87.36% to 72.78%, and the leaching efficiency of neodymium decreases from 85.73% to 75.65%.

[0073] The liquid-to-solid ratio during leaching is maintained at 10 g / L because when the liquid-to-solid ratio is maintained at 5 g / L, the metal leaching efficiency is not much different from that of 10 g / L, which is not conducive to the rational use of resources; when the liquid-to-solid ratio is greater than 10 g / L, the leaching efficiency of metal ions is significantly reduced.

[0074] Example 4

[0075] A leaching method for NdFeB waste, the method comprising the following steps:

[0076] (1) Take 6 100 mL beakers and pour 30 mL of the leaching agent prepared in Example 1 into each beaker;

[0077] (2) Add 300 mg of purchased NdFeB waste to each beaker in (1), stir evenly with a glass rod, and use ultrasonic dispersion if necessary, and then react at 80°C, 100°C, 120°C, 140°C, 160°C, and 180°C for 60 min respectively;

[0078] (3) After leaching, the leaching solution is cooled naturally, and a small amount is taken and diluted with 3-5% nitric acid solution.

[0079] Take a certain amount of the dilution obtained in step (3) above, use the ICP-OES of this laboratory to detect the concentration of iron and neodymium in the dilution, and calculate the leaching efficiency of iron and neodymium. The results are as follows: Figure 3 shown.

[0080] from Figure 3It can be seen that the leaching efficiency of iron and neodymium gradually increases with the increase of temperature. When the temperature changes from 80°C to 160°C, the leaching efficiency of iron increases from 62.75% to 98.11%, and the leaching efficiency of neodymium decreases from 59.17% to 88.39%. When the temperature is greater than 160°C, the leaching efficiency basically does not change.

[0081] Example 5

[0082] A leaching method for NdFeB waste, the method comprising the following steps:

[0083] (1) Take multiple 100 mL beakers and pour 30 mL of the leaching agent in Example 1 into each beaker;

[0084] (2) Add 300 mg of purchased NdFeB waste to each beaker in (1), stir evenly with a glass rod, and use ultrasonic dispersion if necessary, and then react at 160°C for 15 min, 30 min, 45 min, 60 min, 90 min, 120 min, 180 min, 240 min, 300 min, and 720 min respectively;

[0085] (3) After leaching, the leaching solution is cooled naturally, and a small amount is taken and diluted with 3-5% nitric acid solution.

[0086] Take a certain amount of the dilution obtained in step (3) above, use the ICP-OES of this laboratory to detect the concentration of iron and neodymium in the dilution, and calculate the leaching efficiency of iron and neodymium. The results are as follows: Figure 4 shown.

[0087] from Figure 4 It can be seen that the leaching efficiency of iron and neodymium gradually increases with the increase of time. When the time increases from 15min to 120min, the leaching efficiency of iron increases from 84.76% to 98.84%, and the leaching efficiency of neodymium decreases from 77.22% to 95.81%. When the time is greater than 120min, the leaching efficiency basically does not change.

[0088] Example 6

[0089] The preparation method of the N235-P350 extractant of this embodiment comprises the following steps:

[0090] N235 and P350 extractants are mixed in a volume ratio of 1:1. The specific volume is quantitatively weighed according to experimental needs, and stirred at room temperature (heat will be released during the stirring process). When the entire system approaches room temperature, the N235-P350 extractant is obtained.

[0091] The methods for solvent extraction of iron in the leachate involved in the following Examples 8 to 15 all used extractants prepared by the method of Example 6.

[0092] Example 7

[0093] A method for solvent extraction of iron in a leachate, the method comprising the following steps:

[0094] (1) N235 and P350 were mixed in volume ratios of 5:1, 3:1, 1:1, 1:3, and 1:5, respectively, and binary extractants with different volume ratios were prepared according to the steps of Example 6, and were named 5-NP, 3-NP, NP, NP-3, and NP-5, respectively.

[0095] (2) taking a certain amount of the leachate obtained in Example 5 after reacting for 120 min, the specific volume is as required by the experiment, diluting it 5 times using the CA-EG leachate prepared in Example 1 (citric acid and ethylene glycol in a molar ratio of 1:10), then adding 10 vol% hydrogen peroxide (here 10 vol% means that the hydrogen peroxide accounts for 10% of the volume of the leachate), and stirring thoroughly until the color of the solution does not change, to obtain a leachate dilution;

[0096] (3) Take 7 30 mL plastic centrifuge tubes, add 5 mL of the leaching dilution solution and 5 mL of the diluent n-heptane, and use different proportions of the binary extractant, N235, and P350 in (1) as experimental extractants;

[0097] (4) Then, the mixture was reacted at room temperature in a water bath shaker at 300 rpm for 30 min;

[0098] (5) After extraction, pour into a separatory funnel, release the lower layer of liquid, take a small amount and dilute it with 3-5% nitric acid solution.

[0099] Take a certain amount of the dilution obtained in step (5) above, use the ICP-OES of this laboratory to detect the concentration of iron and neodymium in the dilution, and calculate the extraction efficiency of iron and neodymium. The results are as follows: Figure 5 shown.

[0100] from Figure 5 It can be seen that the extraction efficiency of iron and neodymium is closely related to the type of extractant. When N235 or P350 is used alone as the extractant, the extraction efficiency of iron is low, while the extraction efficiency of neodymium is relatively high, and the separation coefficient between the two is low; when a binary extractant is used as the extractant, the extraction efficiency of iron is high, and the separation coefficient between the two is high, especially when NP is used as the extractant, the extraction efficiency and separation coefficient reach the maximum.

[0101] Example 8

[0102] A method for solvent extraction of iron in a leachate, the method comprising the following steps:

[0103] (1) Take multiple portions of the same volume of the leachate obtained in Example 5 after 120 min of reaction, and dilute them 5 times with the CA-EG leachate prepared in Example 1 (citric acid and ethylene glycol in a molar ratio of 1:10), and then add 0%, 10%, 20%, 30%, 40%, 50%, 60% H 2 O 2 , stir thoroughly until the color of the solution does not change, to obtain a leaching dilution;

[0104] (2) Take 7 30 mL plastic centrifuge tubes, add 5 mL of diluent n-heptane, 0.5 mL of the extractant (N235-P350, NP) in Example 6, and 5 mL of the leaching diluent in step (1) respectively;

[0105] (3) The mixture was then reacted in a water bath shaker at 300 rpm for 30 min at room temperature;

[0106] (4) After extraction, pour into a separatory funnel, release the lower layer of liquid, take a small amount and dilute it with 3-5% nitric acid solution.

[0107] Take a certain amount of the dilution obtained in step (4) above, use the ICP-OES of this laboratory to detect the concentration of iron and neodymium in the dilution, and calculate the extraction efficiency of iron and neodymium. The results are as follows: Figure 6 shown.

[0108] from Figure 6 It can be seen that the extraction efficiency of iron is related to H 2 O 2 The addition ratio is closely related. When H 2 O 2 When the addition amount increased from 0 to 30%, the extraction efficiency of iron increased from 16.18% to 99.23%, while the extraction efficiency of neodymium remained almost unchanged; 2 O 2 When the addition amount is greater than 30%, the extraction efficiency has no significant change.

[0109] Example 9

[0110] A method for solvent extraction of iron in a leachate, the method comprising the following steps:

[0111] (1) Taking a certain amount of the leachate obtained in Example 5 after reacting for 120 min, the specific volume is required by the experiment, and diluting it 5 times with the CA-EG leachate prepared in Example 1 (citric acid and ethylene glycol in a molar ratio of 1:10), then adding 30 vol% hydrogen peroxide, and stirring until the color of the solution does not change, to obtain a leachate dilution;

[0112] (2) Take a plurality of 30 mL plastic centrifuge tubes, add 5 mL of the diluent n-heptane, 5 mL of the leaching diluent described in step (1), and several volumes (0.1 mL, 0.2 mL, 0.3 mL, 0.4 mL, 0.5 mL, 0.6 mL, 0.7 mL, 0.8 mL, 0.9 mL, 1.0 mL) of the extractant (N235-P350, NP) in Example 6, respectively;

[0113] (3) The mixture was then reacted in a water bath shaker at 300 rpm for 30 min at room temperature;

[0114] (4) After extraction, pour into a separatory funnel, release the lower layer of liquid, take a small amount and dilute it with 3-5% nitric acid solution.

[0115] Take a certain amount of the dilution obtained in step (4) above, use the ICP-OES of this laboratory to detect the concentration of iron and neodymium in the dilution, and calculate the extraction efficiency of iron and neodymium. The results are as follows: Figure 7 shown.

[0116] from Figure 7 It can be seen that when the extractant concentration is low (0.1mL-0.5mL), the extraction efficiency of iron is highly correlated with it (from 92.44% to 99.68%); when it is greater than 0.5mL, the extraction efficiency is higher than 99%; for neodymium, there is no obvious change within the concentration range.

[0117] Example 10

[0118] A method for solvent extraction of iron in a leachate, the method comprising the following steps:

[0119] (1) The leachate obtained in Example 5 after 120 min of reaction was diluted to different times and then heated to room temperature using 30% H 2 O 2 Oxidation, to obtain different concentrations of dilute leachate; after leaching, the concentration of iron in the leachate is about 2014.78mg / L, and the concentration of neodymium is about 712.83mg / L. After dilution of different times, the concentration of iron dropped to 1473.87mg / L, 1087.88mg / L, 926.00mg / L, 755.41mg / L, 469.37mg / L, 365.57mg / L, 126.79mg / L, while the concentration of neodymium dropped to 501.78mg / L, 344.19mg / L, 300.65mg / L, 250.97mg / L, 160.25mg / L, 120.54mg / L, 37.41mg / L.

[0120] (2) Take a plurality of 30 mL plastic centrifuge tubes, add 5 mL of diluent n-heptane, 0.5 mL of the extractant (N235-P350, NP) in Example 6, and the diluted leachate in step (1) respectively;

[0121] (3) The mixture was then reacted in a water bath shaker at 300 rpm for 30 min at room temperature;

[0122] (4) After extraction, pour into a separatory funnel, release the lower layer of liquid, take a small amount and dilute it with 3-5% nitric acid solution.

[0123] Take a certain amount of the dilution obtained in step (4) above, use the ICP-OES of this laboratory to detect the concentration of iron and neodymium in the dilution, and calculate the extraction efficiency of iron and neodymium. The results are as follows: Figure 8 shown.

[0124] from Figure 8 It can be seen that within the experimental concentration range, the extraction efficiency of iron decreases with the increase of iron concentration, and the extraction efficiency of neodymium has hardly changed; as can be seen from the figure, when the concentration of iron is greater than 469.37 mg / L and the concentration of neodymium is greater than 160.25 mg / L, the extraction efficiency shows a downward trend, and the suboptimal concentrations are iron: 469.37 mg / L, neodymium: 160.25 mg / L.

[0125] Embodiment 11

[0126] A method for solvent extraction of iron in a leachate, the method comprising the following steps:

[0127] (1) Take a plurality of 30 mL plastic centrifuge tubes, add 5 mL of diluent n-heptane, 0.5 mL of the extractant (N235-P350, NP) in Example 6, and the diluted leaching solution of the optimal concentration in Example 10 respectively;

[0128] (2) then reacting at room temperature, 35°C, 40°C, 45°C, 50°C, and 55°C in a water bath shaker at 300 rpm for 30 min;

[0129] (3) After extraction, pour into a separatory funnel, release the lower layer of liquid, take a small amount and dilute it with 3-5% nitric acid solution.

[0130] Take a certain amount of the dilution obtained in step (3) above, use the ICP-OES of this laboratory to detect the concentration of iron and neodymium in the dilution, and calculate the extraction efficiency of iron and neodymium. The results are as follows: Fig. 9 shown.

[0131] from Fig. 9It can be seen that within the experimental temperature range, temperature has almost no effect on the extraction efficiency of iron and neodymium; at room temperature, the extraction efficiency of iron has reached 97.18%, and the extraction efficiency of neodymium is 22.45%.

[0132] Example 12

[0133] A method for solvent extraction of iron in a leachate, the method comprising the following steps:

[0134] (1) Take a plurality of 30 mL plastic centrifuge tubes, add 5 mL of diluent n-heptane, 0.5 mL of the extractant (N235-P350, NP) in Example 6, and the diluted leaching solution of the optimal concentration in Example 10 respectively;

[0135] (2) then reacting in a water bath shaker at 300 rpm at room temperature for 1 min, 3 min, 5 min, 7 min, 10 min, 20 min, 30 min, and 40 min;

[0136] (3) After extraction, pour into a separatory funnel, release the lower layer of liquid, take a small amount and dilute it with 3-5% nitric acid solution.

[0137] Take a certain amount of the dilution obtained in step (3) above, use the ICP-OES of this laboratory to detect the concentration of iron and neodymium in the dilution, and calculate the extraction efficiency of iron and neodymium. The results are as follows: Fig.10 shown.

[0138] from Fig.10 It can be seen that when the reaction time increases from 1 min to 10 min, the extraction efficiency of iron increases from 82.26% to 98.42%, and the extraction efficiency of neodymium increases from 4.29% to 12.92%; when the reaction time is greater than 10 min, there is no obvious change.

[0139] Example 13

[0140] A method for solvent extraction of iron in a leachate, the method comprising the following steps:

[0141] (1) Take a plurality of 30 mL plastic centrifuge tubes, add the diluent n-heptane (25 mL, 15 mL, 5 mL, 5 mL), and the dilute extract of the optimal concentration in Example 10 (5 mL, 5 mL, 5 mL, 15 mL, 25 mL), respectively. Since the volume of the organic phase n-heptane increases, the corresponding extractant also needs to be added in proportion, i.e., 10 vol%;

[0142] (2) then reacting at room temperature in a water bath shaker at 300 rpm for 10 min;

[0143] (3) After extraction, pour into a separatory funnel, release the lower layer of liquid, take a small amount and dilute it with 3-5% nitric acid solution.

[0144] Take a certain amount of the dilution obtained in step (3) above, use the ICP-OES of this laboratory to detect the concentration of iron and neodymium in the dilution, and calculate the extraction efficiency of iron and neodymium. The results are as follows: Fig.11 shown.

[0145] from Fig.11 It can be seen that within different ratio ranges, the extraction efficiency of iron hardly changes, and the extraction efficiency of neodymium is the smallest when the volume ratio is 1; at this time, the extraction efficiency of iron is 98.02%, and the extraction efficiency of neodymium is 11.66%, and the separation coefficient of the two reaches the maximum (375.55).

[0146] Embodiment 14

[0147] A method for stripping iron in an organic phase, the method comprising the steps of:

[0148] (1) Take a plurality of 30 mL plastic centrifuge tubes, add 4 mL of n-heptane phase loaded with iron and neodymium (from the upper liquid after the reaction in step (2) of implementation 16), 4 mL of Na 2 EDTA solution (0.02mol / L, 0.04mol / L, 0.06mol / L, 0.08mol / L, 0.1mol / L, 0.2mol / L, 0.3mol / L, 0.4mol / L) 4mL;

[0149] (2) then reacting at room temperature in a water bath shaker at 300 rpm for 60 min;

[0150] (3) After stripping is completed, pour into a separatory funnel, release the lower layer of liquid, take a small amount and dilute it with 3-5% nitric acid solution.

[0151] Take a certain amount of the dilution obtained in step (3) above, use the ICP-OES of this laboratory to detect the concentration of iron and neodymium in the dilution, and calculate the extraction efficiency of iron and neodymium. The results are as follows: Fig.12 shown.

[0152] from Fig.12 It can be seen that within different concentration ranges, the stripping efficiency of iron hardly changes (maintains at about 77%), while neodymium can no longer be detected in the stripping solution.

[0153] Embodiment 15

[0154] A method for stripping iron in an organic phase, the method comprising the steps of:

[0155] (1) Take a plurality of 30 mL plastic centrifuge tubes and add 4 mL of n-heptane phase loaded with iron and neodymium (from the upper liquid after the reaction in step (2) of implementation 16), 0.02 mol / L of Na 2 EDTA solution 4 mL;

[0156] (2) then reacting at room temperature, 30°C, 40°C, 50°C, and 60°C in a water bath shaker at 300 rpm for 60 min;

[0157] (3) Take a number of samples from (1) and shake them at room temperature for 5 min, 10 min, 20 min, 30 min, 40 min, 60 min, 120 min, and 180 min;

[0158] (4) After the stripping of (2) and (3) above is completed, pour into a separatory funnel, release the lower layer of liquid, take a small amount and dilute it with 3-5% nitric acid solution.

[0159] Take a certain amount of the dilution obtained in step (4) above, use the ICP-OES of this laboratory to detect the concentration of iron and neodymium in the dilution, and calculate the extraction efficiency of iron and neodymium. The results are as follows: Fig.13 shown.

[0160] from Fig.13 As can be seen from the figure above, when the stripping time reaches 60 minutes, the stripping efficiency of iron is higher than 90%; Fig.13 In the figure below, as the temperature increases, the stripping efficiency also gradually increases, which shows that stripping is an endothermic reaction.

[0161] The binary extractant used in the present invention is N235 and P350 in a volume ratio of 1:1, and H 2 O 2 The volume ratio is maintained at 30%; the amount of extractant is maintained at 10vol%; after dilution, the iron concentration in the leachate is maintained at about 469.37mg / L, and the neodymium concentration is maintained at about 160.25mg / L. The reason is that experimental research has found that at this time, the extraction efficiency of iron reaches the maximum, while the extraction efficiency of neodymium is much lower than that of iron, so the iron and neodymium in the leachate can be efficiently separated.

[0162] The present invention keeps the system temperature at room temperature during extraction; keeps the extraction time at 10 minutes; and keeps the volume ratio of the two phases at 1:1 during extraction. The reason is that experimental research has found that the increase in temperature does not have a great influence on the extraction efficiency of the two metals; after a 10-minute extraction process, extraction equilibrium is reached; and at the same time, the volume ratio of the two phases is kept at 1:1, the extraction efficiency of iron reaches the maximum, while the extraction efficiency of neodymium is much lower than that of iron, so that the iron and neodymium in the leaching solution can be efficiently separated.

[0163] The concentration of the stripping agent used in the present invention is 0.02 mol / L disodium ethylenediaminetetraacetate, and the stripping is carried out for 1 hour at room temperature. The reason is that experimental research has found that the stripping efficiency of iron is relatively high (>90%) at this time, and neodymium can no longer be detected in the stripping phase.

[0164] Example 16

[0165] The extraction method of the leaching dilution under the optimal conditions comprises the following steps:

[0166] (1) Take a number of 30 mL plastic centrifuge tubes, add 5 mL of leaching dilution solution, 5 mL of n-heptane phase, and 0.5 mL of extractant into each of the centrifuge tubes;

[0167] (2) then reacting at room temperature in a water bath shaker at 300 rpm for 10 min;

[0168] (3) Take 4 mL of the lower layer of liquid and add it to a new centrifuge tube, then add 4 mL of n-heptane phase and 0.2 mL of the extractant;

[0169] (4) Then, the mixture was reacted at 300 rpm in a water bath shaker at room temperature for 10 min;

[0170] (5) Take 3 mL of the lower layer of liquid and add it to a new centrifuge tube, then add 3 mL of n-heptane phase and 0.1 mL of the extractant;

[0171] (6) Then, the mixture was reacted at room temperature in a water bath shaker at 300 rpm for 10 min;

[0172] (7) The above-mentioned lower layer liquid is extracted three times, that is, three-stage cross-current extraction. After the extraction is completed, pour it into a separatory funnel, release the lower layer liquid, take a small amount and dilute it with 3-5% nitric acid solution, and use ICP-OES to determine the concentration of iron and neodymium in it, and calculate the extraction efficiency.

[0173] The optimal conditions refer to the dilution and oxidation (30 vol% H 2 O 2 ), wherein the concentration of iron is about 469.37 mg / L, the concentration of neodymium is about 160.25 mg / L, the extractant is prepared by N235 and P350 in a volume ratio of 1:1, the extraction time is 10 min, and the extraction temperature is room temperature.

[0174] After the above three-stage extraction, the extraction efficiency of the extractant for iron in the leaching dilution solution can reach 99.9%, while the extraction efficiency of neodymium is only 7.07%, and the separation coefficient between the two is as high as 3387.15.

Claims

1. A CA-EG leaching agent for non-aqueous phase leaching of NdFeB waste, characterized in that: It includes a hydrogen bond acceptor citric acid (CA) and a hydrogen bond donor ethylene glycol (EG).

2. The CA-EG leaching agent according to claim 1, characterized in that: The molar ratio of citric acid to ethylene glycol in the leaching agent is in the range of 1 / 5 to 1 / 20.

3. A non-aqueous phase leaching method for NdFeB waste, characterized in that: The method steps are as follows: Mix the NdFeB waste and CA-EG leaching agent according to the proportion, and place the obtained mixed solution 1 at 80-180°C for constant temperature leaching for 15-720 minutes; after the leaching is completed, cool the obtained leaching solution to room temperature.

4. The non-aqueous phase leaching method according to claim 3, characterized in that: The liquid-to-solid ratio in the mixed solution 1 is maintained in the range of 5 to 25 g / L.

5. The non-aqueous phase leaching method according to claim 3, characterized in that: The leaching temperature is preferably 160° C., and the leaching time is preferably 120 min.

6. A method for separating iron and neodymium from the above-mentioned leachate by extraction using a non-aqueous solvent, characterized in that: The method comprises the following steps: (1) diluting the leaching solution, then adding hydrogen peroxide (H2O2), and stirring thoroughly until the color of the leaching solution does not change, thereby obtaining a leaching dilution solution; then mixing the leaching dilution solution with n-heptane containing an extractant according to a ratio, and extracting the obtained mixed solution 2 at 25° C. to 55° C. under shaking conditions for 1 to 40 minutes; (2) After the extraction is completed, the lower liquid is separated, and a stripping agent is added to the lower liquid, followed by stripping for 5 to 180 minutes at 25° C. to 55° C. and under shaking conditions; after the stripping is completed, the obtained two phases are separated to achieve separation of iron and neodymium.

7. The method according to claim 6, characterized in that: The extractant in step (1) is a combination of N235 and P350.

8. The method according to claim 6, characterized in that: The volume ratio of H2O2 added to the leaching solution in step (1) is maintained in the range of 10% to 30%.

9. The method according to claim 6, characterized in that: The mass fraction of the extractant in the mixed solution 2 in step (1) is maintained in the range of 2% vol% to 20 vol%.

10. The method according to claim 6, characterized in that: The stripping agent in step (2) is disodium ethylenediaminetetraacetic acid solution.

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