Method for extracting gallium and iron from neodymium iron boron waste pickle liquor step by step based on solvent extraction method

Abstract

The invention provides a method for extracting gallium and iron from neodymium iron boron waste, which is a method for efficiently extracting gallium and recovering iron from hydrochloric acid leachate of the neodymium iron boron waste based on a solvent extraction method. The method is short in technological process and good in separation effect, compared with the prior art, the dosage of reagents such as alkali liquor is obviously reduced, generation of waste residues is reduced, additional reagents such as an iron masking agent and a reducing agent do not need to be used, the follow-up recovery process is prevented from being complicated, and the recovery rate and purity of gallium and iron are greatly improved. The method can be directly and effectively combined with an existing process for recycling rare earth elements from waste neodymium iron boron, is stable in process and low in cost, and is a gallium extraction process with a very promising prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of extracting gallium and iron from NdFeB waste, and relates to a method for extracting gallium and iron from NdFeB waste, in particular to a method for stepwise extracting gallium and iron from the acid leaching solution of NdFeB waste based on solvent extraction method. Background Art

[0002] Gallium is a rare and dispersed metal indispensable for the development of modern high-tech. It has wide applications in semiconductor devices, solar cells and infrared optics fields. With the rapid development of these fields, the market demand for gallium is growing continuously. Gallium has no independent ore deposit in nature. Its main source is the by-products of aluminum, zinc and copper smelting, but its output is small. If the gallium resources cannot be stably supplied in the long term, there will be a serious shortage in the next 20 - 30 years. NdFeB magnets are widely used in fields such as electronic information, wind turbines, energy-saving household appliances and automotive industries due to their high coercivity, large magnetic energy product and other advantages. The global NdFeB magnet industry is growing at a rate of 20% per year. China ranks leading in both global production and consumption rankings. NdFeB magnets contain about 25 - 30% rare earth elements and about 70% iron elements. At the same time, a small amount of elements such as gallium are added to improve magnetic properties. A large number of waste NdFeB magnets and NdFeB processing chips generated during the production of NdFeB have become the main secondary resources for rare earth recycling in industry. Most of the existing industrial processes for recycling NdFeB waste directly precipitate iron ions in the acid leaching solution and then only recycle rare earth elements. Therefore, if gallium and iron elements in the waste are recycled while recycling rare earth elements, the utilization efficiency of NdFeB waste will be greatly improved, and the shortage problem of gallium resources will also be effectively alleviated.

[0003] Some corresponding technical solutions have also been disclosed in the prior art. For example, in a method for separating neodymium, iron and gallium from gallium-containing NdFeB production waste disclosed in patent CN 116144954, by adjusting the pH, Ga and Fe in the leaching solution of NdFeB waste precipitate in the form of hydroxides. However, during the precipitation process, some rare earth ions will co-precipitate with Ga and Fe, resulting in the loss of some rare earth ions and low rare earth recovery rate; the content of impurity ions in the gallium-containing solution obtained by re-leaching the pH callback slag is high, and the purity of the recovered gallium is low; moreover, this method requires all Fe 3+ to precipitate, with a high alkali consumption. Another example is a method for separating and recovering gallium, rare earth and cobalt from gallium-containing NdFeB waste disclosed in patent CN 118581324. By adding an iron reducing agent to the acid leaching solution to reduce Fe 3+ , and then separating and recovering Ga by solvent extraction method 3+, but reducing ferric ions with iron powder will increase the iron content in the solution to twice, increasing the difficulty of subsequent solution treatment. Moreover, after ferric chloride in the solution is reduced to ferrous chloride, ferrous ions are easily oxidized to ferric ions in the air, resulting in low gallium purity in the stripping solution obtained during the subsequent solvent extraction process.

[0004] Therefore, how to find a more suitable method for recovering gallium and iron from neodymium-iron-boron waste, solving the above deficiencies of the existing recovery methods, and meeting the development of industrial production has become one of the urgent problems to be solved by many front-line researchers in the industry. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a method for extracting gallium and iron from neodymium-iron-boron waste, especially a method for stepwise extracting gallium and iron from the acid leaching solution of neodymium-iron-boron waste based on solvent extraction. The present invention realizes the separation of Ga 3+ , Fe 3+ , RE 3+ (rare earth ions) among the three, can be better combined with the existing industrial application of recovering rare earths from the acid leaching solution of waste neodymium-iron-boron, and is a method for extracting gallium from neodymium-iron-boron waste with low cost, high efficiency and better stability. Moreover, the extraction method is simple and easy to operate, with mild conditions, strong controllability and good stability, and is more conducive to the popularization and application of industrial production.

[0006] The present invention provides a method for extracting gallium and iron from neodymium-iron-boron waste, comprising the following steps:

[0007] 1) After roasting the neodymium-iron-boron waste, it is placed in an acid solution for acid leaching to obtain an acid leaching solution of neodymium-iron-boron waste;

[0008] 2) Using a mixed solvent composed of an amine extractant, an alcohol phase modifier and a diluent, the acid leaching solution obtained in the above step is subjected to the first countercurrent extraction, and after phase separation, a first raffinate and a gallium-containing organic phase are obtained;

[0009] 3) Mix the gallium-containing organic phase obtained in the above step with water for the first stripping to obtain a first stripping solution, then add an alkali solution to the first stripping solution to adjust the pH value for precipitation, obtaining a solution containing GaO2 - , and then add an acid solution to the solution containing GaO2 - to adjust the pH value again for re-precipitation to obtain a precipitate. Finally, the precipitate is roasted to obtain gallium oxide;

[0010] Using a mixed solvent composed of an amine extractant, an alcohol phase modifier, and a diluent, the first raffinate obtained in the above step is subjected to a second countercurrent extraction, and after phase separation, a second raffinate and an iron-containing organic phase are obtained; the iron-containing organic phase and an oxalic acid solution are mixed and then subjected to a second stripping to obtain a second stripping solution, and then the second stripping solution is evaporated and crystallized to obtain iron oxalate crystals, and finally the iron oxalate crystals are calcined again to obtain iron oxide red.

[0011] Preferably, the calcination time is 3 to 3.5 hours;

[0012] The calcination temperature is 800 to 850 °C;

[0013] In the step 1), the acid solution includes a hydrochloric acid solution;

[0014] In the step 1), the concentration of the acid solution is 2 to 4 mol / L;

[0015] The acid leaching time is 12 to 13 hours;

[0016] The concentration of the neodymium iron boron waste acid leaching solution is 2 to 2.5 mol / L.

[0017] Preferably, the neodymium iron boron waste acid leaching solution, calculated by elemental concentration, includes:

[0018] Fe: 50 to 200 g / L;

[0019] Nd: 30 to 40 g / L;

[0020] Pr: 9 to 12 g / L;

[0021] Dy: 1 to 2 g / L;

[0022] Co: 0.8 to 2 g / L;

[0023] Al: 1 to 3 g / L;

[0024] Ca: 0.9 to 2 g / L;

[0025] Ga: 0.3 to 0.5 g / L;

[0026] Cu: 0.3 to 0.5 g / L;

[0027] B: 1.9 to 3 g / L.

[0028] Preferably, the amine extractant includes one or more of trioctyldecyl tertiary amine, N,N-bis(1-methylheptyl)acetamide, and methyltrioctylammonium chloride;

[0029] The alcohol phase modifier includes isodecanol and / or isooctanol;

[0030] The diluent includes an alkane diluent and / or an aromatic diluent;

[0031] In the mixed solvent, the volume concentration of the amine extractant is 2% to 5%;

[0032] In the mixed solvent, the volume concentration of the alcohol phase modifier is 10% to 15%.

[0033] Preferably, the first countercurrent extraction method includes multi-stage countercurrent extraction;

[0034] In the first countercurrent extraction, the volume ratio of the organic phase to the aqueous phase is (2 to 1):(1 to 2);

[0035] The temperature of the first countercurrent extraction is 25 to 35 °C;

[0036] The time of the first countercurrent extraction is 5 to 10 min;

[0037] The number of extraction stages of the first countercurrent extraction is 8 to 12 stages.

[0038] Preferably, the first stripping method includes multi-stage countercurrent extraction;

[0039] In the first stripping, the volume ratio of the organic phase to the aqueous phase is (20 to 30):1;

[0040] The temperature of the first stripping is 25 to 35 °C;

[0041] The time of the first stripping is 5 to 10 min;

[0042] The number of extraction stages of the first stripping is 3 to 6 stages;

[0043] The lye includes a sodium hydroxide solution;

[0044] The concentration of the lye is 2 to 4 mol / L.

[0045] Preferably, the adjusted pH value is specifically 13 to 14;

[0046] The acid solution includes a hydrochloric acid solution;

[0047] The concentration of the acid solution is 1 to 3 mol / L;

[0048] The re-adjusted pH value is specifically 6 to 7;

[0049] The temperature of the precipitation and the re-precipitation are each independently selected from 50 to 70 °C;

[0050] The roasting time is 30 to 90 min;

[0051] The roasting temperature is 800 to 900 °C.

[0052] Preferably, in step 3), the amine extractant includes one or more of trioctyldecyl tertiary amine, N,N-bis(1-methylheptyl)acetamide, and methyltrioctylammonium chloride;

[0053] In step 3), the alcohol phase modifier includes isodecanol and / or isooctanol;

[0054] In step 3), the diluent includes an alkane diluent and / or an aromatic diluent;

[0055] In the mixed solvent of step 3), the volume concentration of the amine extractant is 30% - 40%;

[0056] In the mixed solvent of step 3), the volume concentration of the alcohol phase modifier is 25% - 30%;

[0057] The second raffinate is fed into the subsequent rare earth recovery process.

[0058] Preferably, the mode of the second countercurrent extraction includes multi-stage countercurrent extraction;

[0059] In the second countercurrent extraction, the volume ratio of the organic phase to the aqueous phase is (1 - 2):1;

[0060] The temperature of the second countercurrent extraction is 25 - 35°C;

[0061] The time of the second countercurrent extraction is 10 - 15 min;

[0062] The extraction stage number of the second countercurrent extraction is 6 - 10 stages;

[0063] The concentration of the oxalic acid solution is 0.8 - 1.2 mol / L.

[0064] Preferably, the mode of the second stripping includes multi-stage countercurrent extraction;

[0065] In the second stripping, the volume ratio of the organic phase to the aqueous phase is (1 - 2):1;

[0066] The temperature of the second stripping is 25 - 35°C;

[0067] The time of the second stripping is 10 - 15 min;

[0068] The extraction stage number of the second stripping is 3 - 6 stages;

[0069] The evaporation and crystallization are specifically evaporation concentration and cooling crystallization;

[0070] The time of the re-roasting is 90 - 120 min;

[0071] The temperature of the second roasting is 450-500 °C.

[0072] The present invention provides a method for extracting gallium and iron from neodymium-iron-boron waste, comprising the following steps: First, the neodymium-iron-boron waste is roasted and then placed in an acid solution for acid leaching to obtain an acid leaching solution of neodymium-iron-boron waste; Then, a mixed solvent composed of an amine extractant, an alcohol phase modifier, and a diluent is used to perform a first countercurrent extraction on the acid leaching solution obtained in the above step, and after phase separation, a first raffinate and a gallium-containing organic phase are obtained; Finally, the gallium-containing organic phase obtained in the above step is mixed with water for a first stripping to obtain a first stripping solution, and then an alkali solution is added to the first stripping solution to adjust the pH value for precipitation to obtain a solution containing GaO2 - of the solution, and then an acid solution is added to the solution containing GaO2 - of the solution to adjust the pH value again for re-precipitation to obtain a precipitate. Finally, the precipitate is roasted to obtain gallium oxide; A mixed solvent composed of an amine extractant, an alcohol phase modifier, and a diluent is used to perform a second countercurrent extraction on the first raffinate obtained in the above step, and after phase separation, a second raffinate and an iron-containing organic phase are obtained; The iron-containing organic phase is mixed with an oxalic acid solution for a second stripping to obtain a second stripping solution, and then the second stripping solution is evaporated and crystallized to obtain iron oxalate crystals. Finally, the iron oxalate crystals are roasted again to obtain iron oxide red. Compared with the prior art, the present invention aims at the problems in the prior art that gallium elements are not effectively extracted, a large amount of iron resources are not effectively recovered, gallium-iron separation is difficult, and a large amount of waste residue is generated during the recovery process of neodymium-iron-boron waste. A method for efficiently extracting gallium and recovering iron from the hydrochloric acid leaching solution of neodymium-iron-boron waste based on solvent extraction is creatively designed. High-purity gallium oxide and iron oxide products are obtained through steps such as solvent extraction and precipitation separation, and the metal recovery rate is high. The method not only has a short process flow and good separation effect, but also significantly reduces the dosage of reagents such as alkali solution compared with the existing process, reduces the generation of waste residue, does not require external reagents such as iron masking agents and reducing agents, avoids the complication of the subsequent recovery process, and the recovery rate and purity of gallium and iron are also greatly improved. The present invention can be directly and effectively combined with the existing process for recovering rare earth elements from waste neodymium-iron-boron. The process is stable and the cost is low, which is a very promising gallium extraction process.

[0073] The method for efficiently extracting gallium and recovering iron from the acid leaching solution of waste neodymium-iron-boron provided by the present invention is a method for extracting gallium from neodymium-iron-boron waste with low cost, high efficiency and better stability. The present invention uses a mixed organic solvent of an amine extractant and an alcohol to perform multi-stage countercurrent extraction on the acid leaching solution of neodymium-iron-boron waste to separate Ga 3+ / Fe 3+ , and the separation coefficient between the two reaches about 25, which proves that the extraction system has a good separation effect on Ga 3+ / Fe 3+The separation effect is good. Moreover, by directly subjecting the acid leaching solution of neodymium-iron-boron waste to extraction and stripping, the Fe 3+ / Ga 3+ ratio can be reduced to about 12 without the need to add iron masking agents, reducing agents, etc. The process is simple and has high industrialization prospects. The present invention separates and recovers Ga 3+ and Fe 3+ from the acid leaching solution of neodymium-iron-boron waste, which can be directly connected to the existing industrialized process for recovering rare earth elements from the leaching solution of neodymium-iron-boron waste without significantly changing the overall process flow. It improves the recovery rate of neodymium-iron-boron waste, avoids the generation of a large amount of waste residue and waste water, and significantly reduces the alkali consumption, which is economical and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 It is a schematic diagram of the process flow for extracting gallium and iron from neodymium-iron-boron waste provided by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0075] To further understand the present invention, the preferred embodiments of the present invention will be described below in conjunction with examples. However, it should be understood that these descriptions are only for further explaining the features and advantages of the present invention rather than limiting the claims of the present invention.

[0076] For all raw materials of the present invention, there is no special limitation on their sources, and they can be purchased on the market or prepared according to the conventional methods well-known to those skilled in the art.

[0077] For all raw materials of the present invention, there is no special limitation on their purity. The present invention preferably uses industrial purity or the purity conventional in the field of extracting neodymium-iron-boron waste.

[0078] The present invention provides a method for extracting gallium and iron from neodymium-iron-boron waste, comprising the following steps:

[0079] 1) After roasting the neodymium-iron-boron waste and then subjecting it to acid leaching in an acid solution, an acid leaching solution of neodymium-iron-boron waste is obtained;

[0080] 2) Using a mixed solvent composed of an amine extractant, an alcohol phase modifier, and a diluent, subjecting the acid leaching solution obtained in the above step to the first countercurrent extraction, and separating phases to obtain a first raffinate and a gallium-containing organic phase;

[0081] 3) Mixing the gallium-containing organic phase obtained in the above step with water for the first stripping to obtain a first stripping solution, then adding an alkali solution to the first stripping solution to adjust the pH value for precipitation to obtain a solution containing GaO2 - , then adding an acid solution to the solution containing GaO2 - to adjust the pH value again for re-precipitation to obtain a precipitate, and finally roasting the precipitate to obtain gallium oxide;

[0082] Using a mixed solvent composed of an amine extractant, an alcohol phase modifier, and a diluent, the first raffinate obtained in the above step is subjected to a second countercurrent extraction, and then phase separation is carried out to obtain a second raffinate and an iron-containing organic phase; the iron-containing organic phase and an oxalic acid solution are mixed and then subjected to a second stripping to obtain a second stripping solution, and then the second stripping solution is evaporated and crystallized to obtain iron oxalate crystals, and finally the iron oxalate crystals are calcined again to obtain iron oxide red.

[0083] In the present invention, first, the neodymium-iron-boron waste is calcined and then placed in an acid solution for acid leaching to obtain a neodymium-iron-boron waste acid leaching solution.

[0084] In the present invention, the calcination time is preferably 3 to 3.5 hours, more preferably 3.1 to 3.4 hours, and even more preferably 3.2 to 3.3 hours.

[0085] In the present invention, the calcination temperature is preferably 800 to 850 °C, more preferably 810 to 840 °C, and even more preferably 820 to 830 °C.

[0086] In the present invention, in step 1), the acid solution preferably includes a hydrochloric acid solution.

[0087] In the present invention, in step 1), the concentration of the acid solution is preferably 2 to 4 mol / L, more preferably 2.4 to 3.6 mol / L, and even more preferably 2.8 to 3.2 mol / L.

[0088] In the present invention, the acid leaching time is preferably 12 to 13 hours, more preferably 12.2 to 12.8 hours, and even more preferably 12.4 to 12.6 hours.

[0089] In the present invention, the concentration of the neodymium-iron-boron waste acid leaching solution is preferably 2 to 2.5 mol / L, more preferably 2.1 to 2.4 mol / L, and even more preferably 2.2 to 2.3 mol / L.

[0090] In the present invention, the neodymium-iron-boron waste acid leaching solution, calculated by elemental concentration, includes:

[0091] Fe: 50 to 200 g / L;

[0092] Nd: 30 to 40 g / L;

[0093] Pr: 9 to 12 g / L;

[0094] Dy: 1 to 2 g / L;

[0095] Co: 0.8 to 2 g / L;

[0096] Al: 1 to 3 g / L;

[0097] Ca: 0.9 - 2 g / L;

[0098] Ga: 0.3 - 0.5 g / L;

[0099] Cu: 0.3 - 0.5 g / L;

[0100] B: 1.9 - 3 g / L.

[0101] Specifically, the addition amount of Fe is preferably 50 - 200 g / L, more preferably 55 - 150 g / L, and even more preferably 60 - 100 g / L.

[0102] Specifically, the addition amount of Nd is preferably 30 - 40 g / L, more preferably 32 - 38 g / L, and even more preferably 34 - 36 g / L.

[0103] Specifically, the addition amount of Pr is preferably 9 - 12 g / L, more preferably 9.5 - 11.5 g / L, and even more preferably 10 - 11 g / L.

[0104] Specifically, the addition amount of Dy is preferably 1 - 2 g / L, more preferably 1.2 - 1.8 g / L, and even more preferably 1.4 - 1.6 g / L.

[0105] Specifically, the addition amount of Co is preferably 0.8 - 2 g / L, more preferably 1 - 1.8 g / L, and even more preferably 1.2 - 1.6 g / L.

[0106] Specifically, the addition amount of Al is preferably 1 - 3 g / L, more preferably 1.4 - 2.6 g / L, and even more preferably 1.8 - 2.2 g / L.

[0107] Specifically, the addition amount of Ca is preferably 0.9 - 2 g / L, more preferably 1.1 - 1.8 g / L, and even more preferably 1.3 - 1.6 g / L.

[0108] Specifically, the addition amount of Ga is preferably 0.3 - 0.5 g / L, more preferably 0.34 - 0.46 g / L, and even more preferably 0.38 - 0.42 g / L.

[0109] Specifically, the addition amount of Cu is preferably 0.3 - 0.5 g / L, more preferably 0.34 - 0.46 g / L, and even more preferably 0.38 - 0.42 g / L.

[0110] Specifically, the addition amount of B is preferably 1.9 - 3 g / L, more preferably 2.1 - 2.8 g / L, and even more preferably 2.3 - 2.6 g / L.

[0111] In the present invention, a mixed solvent composed of an amine extractant, an alcohol phase modifier, and a diluent is used to perform a first countercurrent extraction on the acid leaching solution obtained in the above step, and after phase separation, a first raffinate and a gallium-containing organic phase are obtained.

[0112] In the present invention, the amine extractant preferably includes one or more of trioctyldecyl tertiary amine, N,N-di(1-methylheptyl)acetamide, and methyltrioctylammonium chloride, and more preferably trioctyldecyl tertiary amine or N,N-di(1-methylheptyl)acetamide.

[0113] In the present invention, the alcohol phase modifier preferably includes isodecanol and / or isooctanol, and more preferably isodecanol or isooctanol.

[0114] In the present invention, the diluent preferably includes an alkane diluent and / or an aromatic diluent, and more preferably an alkane diluent or an aromatic diluent.

[0115] In the present invention, in the mixed solvent, the volume concentration of the amine extractant is preferably 2% to 5%, more preferably 2.5% to 4.5%, and even more preferably 3% to 4%.

[0116] In the present invention, in the mixed solvent, the volume concentration of the alcohol phase modifier is preferably 10% to 15%, more preferably 11% to 14%, and even more preferably 12% to 13%.

[0117] In the present invention, the manner of the first countercurrent extraction preferably includes multi-stage countercurrent extraction.

[0118] In the present invention, in the first countercurrent extraction, the volume ratio of the organic phase to the aqueous phase is preferably (2 to 1):(1 to 2), more preferably (1.8 to 1.2):(1.2 to 1.8), and even more preferably (1.6 to 1.4):(1.4 to 1.6).

[0119] In the present invention, the temperature of the first countercurrent extraction is preferably 25 to 35 °C, more preferably 27 to 33 °C, and even more preferably 29 to 31 °C.

[0120] In the present invention, the time of the first countercurrent extraction is preferably 5 to 10 min, more preferably 6 to 9 min, and even more preferably 7 to 8 min.

[0121] In the present invention, the number of extraction stages of the first countercurrent extraction is preferably 8 to 12 stages, more preferably 9 to 12 stages, even more preferably 10 to 12 stages, and even more preferably 11 to 12 stages.

[0122] Finally, in the present invention, the gallium-containing organic phase obtained in the above step is mixed with water and then subjected to a first stripping to obtain a first stripping solution, and then an alkali solution is added to the first stripping solution to adjust the pH value for precipitation to obtain a precipitate containing GaO2- solution, and then add an acid solution to the solution containing GaO2 - to adjust the pH value again for secondary precipitation to obtain a precipitate. Finally, after roasting the precipitate, gallium oxide is obtained;

[0123] Using a mixed solvent composed of an amine extractant, an alcohol phase modifier, and a diluent, perform a second countercurrent extraction on the first raffinate obtained in the above step, and separate phases to obtain a second raffinate and an iron-containing organic phase; mix the iron-containing organic phase with an oxalic acid solution for a second stripping to obtain a second stripping solution, and then after evaporating and crystallizing the second stripping solution, obtain iron oxalate crystals. Finally, after roasting the iron oxalate crystals again, iron oxide red is obtained.

[0124] In the present invention, the method of the first stripping preferably includes multi-stage countercurrent extraction.

[0125] In the present invention, in the first stripping, the volume ratio of the organic phase to the aqueous phase is preferably (20-30):1, more preferably (22-28):1, and even more preferably (24-26):1.

[0126] In the present invention, the temperature of the first stripping is preferably 25-35°C, more preferably 27-33°C, and even more preferably 29-31°C.

[0127] In the present invention, the time of the first stripping is preferably 5-10 min, more preferably 6-9 min, and even more preferably 7-8 min.

[0128] In the present invention, the number of extraction stages of the first stripping is preferably 3-6 stages, more preferably 4-5 stages, and even more preferably 5-6 stages.

[0129] In the present invention, the alkali solution preferably includes a sodium hydroxide solution.

[0130] In the present invention, the concentration of the alkali solution is preferably 2-4 mol / L, more preferably 2.4-3.6 mol / L, and even more preferably 2.8-3.2 mol / L.

[0131] In the present invention, the adjustment of the pH value is specifically preferably 13-14, more preferably 13.2-13.8, and even more preferably 13.4-13.6.

[0132] In the present invention, the acid solution preferably includes a hydrochloric acid solution.

[0133] In the present invention, the concentration of the acid solution is preferably 1-3 mol / L, more preferably 1.4-2.6 mol / L, and even more preferably 1.8-2.2 mol / L.

[0134] In the present invention, the re-adjustment of the pH value is preferably 6-7, more preferably 6.2-6.8, and even more preferably 6.4-6.6.

[0135] In the present invention, the temperatures of the precipitation and the re-precipitation are each independently preferably selected from 50-70 °C, more preferably 54-66 °C, and even more preferably 58-62 °C.

[0136] In the present invention, the calcination time is preferably 30-90 min, more preferably 40-90 min, and even more preferably 70-90 min.

[0137] In the present invention, the calcination temperature is preferably 800-900 °C, more preferably 830-900 °C, and even more preferably 850-900 °C.

[0138] In the present invention, in step 3), the amine extractant preferably includes one or more of trioctyldecyl tertiary amine, N,N-bis(1-methylheptyl)acetamide, and methyltrioctylammonium chloride, and is more preferably trioctyldecyl tertiary amine, N,N-bis(1-methylheptyl)acetamide, or methyltrioctylammonium chloride.

[0139] In the present invention, in step 3), the alcohol phase modifier preferably includes isodecanol and / or isooctanol, and is more preferably isodecanol or isooctanol.

[0140] In the present invention, in step 3), the diluent preferably includes an alkane diluent and / or an aromatic diluent, and is more preferably an alkane diluent or an aromatic diluent.

[0141] In the present invention, in the mixed solvent of step 3), the volume concentration of the amine extractant is preferably 30%-40%, more preferably 32%-38%, and even more preferably 34%-36%.

[0142] In the present invention, in the mixed solvent of step 3), the volume concentration of the alcohol phase modifier is preferably 25%-30%, more preferably 26%-29%, and even more preferably 27%-28%.

[0143] In the present invention, the second raffinate is fed into a subsequent preferred rare earth recovery process.

[0144] In the present invention, the method of the second countercurrent extraction preferably includes multi-stage countercurrent extraction.

[0145] In the present invention, in the second countercurrent extraction, the volume ratio of the organic phase to the aqueous phase is preferably (1-2):1, more preferably (1.2-1.8):1, and even more preferably (1.4-1.6):1.

[0146] In the present invention, the temperature of the second countercurrent extraction is preferably 25 to 35 °C, more preferably 27 to 33 °C, and even more preferably 29 to 31 °C.

[0147] In the present invention, the time of the second countercurrent extraction is preferably 10 to 15 min, more preferably 11 to 14 min, and even more preferably 12 to 13 min.

[0148] In the present invention, the number of extraction stages of the second countercurrent extraction is preferably 6 to 10 stages, more preferably 6 to 9 stages, even more preferably 6 to 8 stages, and even more preferably 7 to 8 stages.

[0149] In the present invention, the concentration of the oxalic acid solution is preferably 0.8 to 1.2 mol / L, more preferably 0.85 to 1.15 mol / L, even more preferably 0.9 to 1.1 mol / L, and even more preferably 0.95 to 1.05 mol / L.

[0150] In the present invention, the second stripping method preferably includes multi-stage countercurrent extraction.

[0151] In the present invention, in the second stripping, the volume ratio of the organic phase to the aqueous phase is preferably (1 to 2):1, more preferably (1.2 to 1.8):1, and even more preferably (1.4 to 1.6):1.

[0152] In the present invention, the temperature of the second stripping is preferably 25 to 35 °C, more preferably 27 to 33 °C, and even more preferably 29 to 31 °C.

[0153] In the present invention, the time of the second stripping is preferably 10 to 15 min, more preferably 11 to 14 min, and even more preferably 12 to 13 min.

[0154] In the present invention, the number of extraction stages of the second stripping is preferably 3 to 6 stages, more preferably 4 to 6 stages, and even more preferably 5 to 6 stages.

[0155] In the present invention, the evaporation and crystallization can specifically be evaporation concentration and cooling crystallization.

[0156] In the present invention, the time of the second roasting is preferably 90 to 120 min, more preferably 100 to 120 min, and even more preferably 110 to 120 min.

[0157] In the present invention, the temperature of the second roasting is preferably 450 to 500 °C, more preferably 460 to 500 °C, and even more preferably 480 to 500 °C.

[0158] In order to complete and refine the overall technical solution, better ensure the stable operation of the extraction process from neodymium-iron-boron waste, and further improve the separation effect, the method for extracting gallium and iron from neodymium-iron-boron waste may specifically include the following steps:

[0159] Specific implementation process of this solution:

[0160] 1. Extract and separate gallium. Using the leaching solution obtained by acid leaching the roasted neodymium-iron-boron waste with hydrochloric acid as the raw material, adjusting the hydrochloric acid concentration in the acid leaching solution, and performing multi-stage countercurrent extraction on the acid leaching solution with a mixed solvent of an amine extractant and an alcohol, and separating phases to obtain a first raffinate and a gallium-containing organic phase.

[0161] Specifically, the hydrochloric acid leaching solution includes leaching solutions obtained under various leaching conditions, such as a hydrochloric acid excellent solution (a solution obtained by controlling the leaching conditions to completely leach the rare earth elements in the waste and slightly leach the iron elements), a hydrochloric acid full solution (a solution obtained by controlling the leaching conditions to completely leach all elements in the waste), etc.

[0162] Specifically, the adjustment range of the hydrochloric acid concentration in the acid leaching solution is 2 - 2.5 mol / L (the concentration of the leaching solution obtained after acid leaching of the neodymium-iron-boron waste, that is, the adjusted concentration).

[0163] Specifically, the amine extractant includes one or more of trioctyldecyl tertiary amine, N,N-bis(1-methylheptyl)acetamide, and methyltrioctylammonium chloride, and its concentration is 2 - 5%.

[0164] Specifically, the function of adding alcohol is to eliminate the third phase as a phase modifier. The types of alcohol include isodecanol, isooctanol, etc., and its concentration is 10 - 15%. The mixed organic phase uses an alkane or an aromatic hydrocarbon as a diluent to form an extraction system.

[0165] Specifically, the extraction organic phase has different binding abilities with Ga 3+ , Fe 3+ , RE 3+ (rare earth ions), has a stronger binding ability to Ga 3+ than to Fe 3+ , hardly extracts RE 3+ (rare earth ions) and other impurity ions such as Cu 2+ , Al 3+ in the acid leaching solution, and the Ga 3+ / Fe 3+ separation factor reaches 20 - 25.

[0166] Specifically, the extraction conditions are: the phase ratio range is organic phase:aqueous phase = 2:1 - 1:2; the extraction temperature range is 25 - 35 °C; the extraction time range is 5 - 10 min; the extraction stage number range is 8 - 12 stages.

[0167] 2. Gallium-containing organic phase back-extraction. Deionized water is used as the back-extraction agent for the gallium-containing organic phase in the present invention, which is economical and environmentally friendly. The deionized water and the gallium-containing organic phase are subjected to back-extraction under certain back-extraction conditions to obtain the first back-extraction solution and the blank organic phase. By controlling the back-extraction phase ratio, Ga in the back-extraction solution 3+ is concentrated, so the effect of enriching gallium can be achieved.

[0168] Specifically, in the leaching solution of neodymium iron boron waste raw materials, the Fe 3+ / Ga 3+ ratio can reach 190. After extraction-back-extraction, in some examples, the Fe 3+ / Ga 3+ ratio in the back-extraction solution can be reduced to about 12. The back-extraction solution contains almost only Ga 3+ , Fe 3+ , realizing the complete separation of Ga 3 + from the impurity ions (RE 3+ , Co 2+ , Cu 2+ , Al 3+ etc.) in other acid leaching solutions. At the same time, the Fe 3+ / Ga 3+ is greatly reduced, which can reduce the difficulty of subsequent process treatment.

[0169] Specifically, the back-extraction conditions are as follows: the phase ratio range is organic phase: aqueous phase = 30:1 - 20:1; the extraction temperature range is 25 - 35 °C; the extraction time range is 5 - 10 min; the back-extraction stage number range is 3 - 6 stages.

[0170] 3. Further separation of Ga 3+ / Fe 3+ . An alkali solution is added to the obtained first back-extraction solution to adjust its pH value to 13 - 14, so that Fe 3+ is converted into Fe(OH)3 precipitate and filtered out to obtain a solution containing GaO2 - . Then, an acid solution is added to the solution containing GaO2 - to adjust the pH value to 6 - 7, so that GaO2 - is converted into Ga(OH)3 precipitate and filtered out. The obtained Ga(OH)3 precipitate is washed with water multiple times, then dried, and placed in a muffle furnace for oxidative roasting to obtain Ga2O3 with a purity of about 99%.

[0171] Specifically, the added alkali solution is a sodium hydroxide solution with a concentration of 2 - 4 mol / L. During the precipitation process, the precipitation temperature range is 50 - 70 °C.

[0172] Specifically, the added acid solution is a hydrochloric acid solution with a concentration of 1 - 3 mol / L. During the precipitation process, the precipitation temperature range is 50 - 70 °C.

[0173] Specifically, the oxidation roasting temperature range of Ga(OH)3 in the muffle furnace is: 800 - 900 °C, and the time range is: 30 min - 90 min.

[0174] 4. Extract and separate iron. The first raffinate obtained in the above step 1 is subjected to multi-stage countercurrent extraction using a mixed solvent of an amine extractant and an alcohol to obtain a second raffinate and an iron-containing organic phase by phase separation.

[0175] Specifically, the types of the amine extractant, the alcohol, and the diluent are the same as those described in step 1.

[0176] Specifically, the concentration range of the amine extractant is 30 - 40%, and the concentration range of the alcohol is 25 - 30%. During the extraction and separation of iron, Fe 3+ is completely separated from other ions (RE 3+ , Co 2+ , Cu 2+ , Al 3+ , etc.) in the first raffinate.

[0177] Specifically, the second raffinate can continue to be connected with the extraction process for recovering rare earth ions from the acid leaching solution of neodymium-iron-boron waste in existing enterprises. This rare earth recovery process is relatively mature and will not be elaborated here.

[0178] Specifically, the extraction conditions are: the phase ratio range is organic phase: aqueous phase = 2:1 - 1:1; the extraction temperature range is 25 - 35 °C; the extraction time range is 10 - 15 min; the extraction stage number range is 6 - 10 stages.

[0179] 5. Back-extraction of the iron-containing organic phase. The Fe in the iron-containing organic phase 3+ needs to be stripped by back-extraction. A certain concentration of oxalic acid solution is used for back-extraction to obtain a second back-extraction solution and a blank organic phase because oxalate ions can form iron oxalate complexes with Fe 3+ to promote the entry of iron from the organic phase into the back-extraction solution.

[0180] The obtained second back-extraction solution is concentrated by evaporation, cooled and crystallized to obtain iron oxalate crystals, and then the crystals are oxidized and roasted at an appropriate temperature and time to form iron oxide red products with a purity of about 99%.

[0181] Specifically, the concentration range of the back-extraction agent oxalic acid is 0.8 - 1.2 mol / L. The back-extraction conditions are: the phase ratio range is organic phase: aqueous phase = 2:1 - 1:1; the extraction temperature range is 25 - 35 °C; the extraction time range is 10 - 15 min; the back-extraction stage number range is 3 - 6 stages.

[0182] Specifically, the oxidation roasting temperature range is: 450 - 500 °C, and the time range is: 90 min - 120 min.

[0183] See Figure 1 , Figure 1 which is a schematic diagram of the process flow for extracting gallium and iron from neodymium-iron-boron waste provided by the present invention.

[0184] The above content of the present invention provides a method for stepwise extracting gallium and iron from the acid leaching solution of neodymium-iron-boron waste based on solvent extraction. The present invention obtains relatively high-purity gallium oxide and iron oxide products through steps such as solvent extraction and precipitation separation, and has a high metal recovery rate. This method not only has a short process flow and good separation effect, but also significantly reduces the usage of reagents such as lye compared to the existing process, reduces the generation of waste residue, does not require the use of external reagents such as iron masking agents and reducing agents, avoids the complication of subsequent recovery processes, and greatly improves the recovery rate and purity of gallium and iron. The present invention can be directly and effectively combined with the existing process for recycling rare earth elements from waste neodymium-iron-boron, has a stable process and low cost, and is a very promising gallium extraction process.

[0185] The method for efficiently extracting gallium and recovering iron from the acid leaching solution of waste neodymium-iron-boron provided by the present invention is a method for extracting gallium from neodymium-iron-boron waste with low cost, high efficiency and better stability. The present invention uses a mixed organic solvent of an amine extractant and an alcohol for multi-stage countercurrent extraction of the acid leaching solution of neodymium-iron-boron waste to separate Ga 3+ / Fe 3+ , and the separation factor between the two reaches about 25, proving that this extraction system has a good separation effect on Ga 3+ / Fe 3+ . Moreover, by directly performing extraction and back-extraction on the acid leaching solution of neodymium-iron-boron waste, the Fe 3+ / Ga 3+ ratio can be reduced to about 12, without the need to add iron masking agents, reducing agents, etc. The process is simple and has high industrialization prospects. The present invention separates and recovers Ga 3+ and Fe 3+ in the acid leaching solution of neodymium-iron-boron waste, and can be directly connected with the existing industrial process for recovering rare earth elements from the leaching solution of neodymium-iron-boron waste without significantly changing the overall process flow. It improves the recycling rate of neodymium-iron-boron waste, avoids the generation of a large amount of waste residue and waste water, greatly reduces the alkali consumption, and is economical and environmentally friendly.

[0186] In order to further illustrate the present invention, a method for extracting gallium and iron from NdFeB waste provided by the present invention is described in detail below in combination with examples. However, it should be understood that these examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating processes are given only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention, and the protection scope of the present invention is not limited to the following examples.

[0187] Example 1

[0188] Source of raw materials: The acid leaching solution of the raw material NdFeB waste is provided by a hydrochloric acid solution provided by a company related to NdFeB waste recycling (referring to the leaching solution obtained by leaching NdFeB waste through hydrochloric acid under certain conditions after oxidation roasting, so that all rare earth elements are dissolved and iron and gallium elements are partially dissolved). The element composition of the acid leaching solution is shown in Table 1. Table 1 shows the element composition of the acid leaching solution in Example 1 of the present invention.

[0189] Table 1

[0190] Element Fe Nd Pr Dy Co Al Ca Ga Cu B Concentration (g / L) 71 41 10 1.4 0.9 1.6 0.9 0.34 0.4 1.9

[0191] 1. Extract and separate gallium.

[0192] Adjust the hydrochloric acid concentration of the acid leaching solution to about 2 mol / L. 3+ The content is 54g / L, Ga 3+ The content is 0.28g / L. The acid leaching liquid is subjected to 8-stage extraction and phase separation using a mixed solvent of 2% trioctyldecyl tertiary amine, 10% isodecyl alcohol and diluent sulfonated kerosene to obtain a gallium-containing organic phase and a first raffinate. 3+ The content was only 0.005 g / L, and the gallium extraction rate reached 98.2%. The extraction conditions were: organic phase: aqueous phase = 1:1; extraction temperature was 25°C; extraction time was 5 min.

[0193] 2. Phase extraction of gallium-containing organic phase.

[0194] Ga in gallium-containing organic phase 3+ The content is 0.275g / L, Fe 3+ The content is 3.4 g / L. After deionized water stripping, three-stage stripping is performed to obtain the first stripping solution and the blank organic phase. The Ga in the stripping solution 3+ The content is 5.5g / L, Fe 3+ The content is 68g / L, other impurity ions (Co 2+ , Cu 2+ 、Al 3+ The content of Ga is less than 1mg / L. 3+ The enrichment factor is about 20, Fe 3+ / Ga 3+The ratio decreases to about 12, and the stripping phase ratio is: organic phase: aqueous phase = 20:1; the stripping temperature range is 25°C; the stripping time is 5 min.

[0195] 3. Ga 3+ / Fe 3+ For further separation.

[0196] Slowly add 2 mol / L sodium hydroxide solution to the first stripping solution, and at the same time stir the solution uniformly at a temperature of 50°C until the pH of the solution is adjusted to about 13. After aging for 12 h, filter out the Fe(OH)3 precipitate to obtain a solution containing GaO2 - solution. Add 1 mol / L hydrochloric acid solution to the solution containing GaO2 - to adjust its pH to 6.5. After aging, filter to obtain Ga(OH)3 precipitate. After washing with water and drying, put it into a muffle furnace and calcine it at 850°C for 60 min to obtain the product gallium oxide. After determination, its purity is 99.1%, and the gallium recovery rate reaches 85%.

[0197] 4. Extract and separate iron.

[0198] Use a mixed solvent of 40% trioctyl decyl tertiary amine and 30% isodecanol to carry out 6-stage countercurrent extraction on the first raffinate to obtain a second raffinate and an iron-containing organic phase. The extraction conditions are: phase ratio is organic phase: aqueous phase = 2:1; extraction temperature is 25°C; extraction time is 10 min.

[0199] 5. Strip the iron-containing organic phase.

[0200] Use 1 mol / L oxalic acid solution to strip the iron-containing organic phase for 3 stages to obtain a second stripping solution and a blank organic phase. The Fe 3+ content in the stripping solution is about 25 g / L, and the contents of other impurity ions are all lower than 3 mg / L. The stripping phase ratio is: organic phase: aqueous phase = 1:1; the stripping temperature range is 25°C; the stripping time is 10 min. Evaporate and concentrate the second stripping solution, and cool and crystallize to obtain iron oxalate crystals. The iron oxalate crystals are oxidized and calcined at 500°C for 2 h to obtain iron oxide red products. After determination, its purity is 99.5%, and the iron recovery rate reaches 92%.

[0201] Example 2

[0202] Source of the raw material acid leaching solution: The raw material neodymium iron boron waste acid leaching solution is prepared in the laboratory. Under the leaching conditions (hydrochloric acid concentration 4 mol / L, leaching temperature 90°C, liquid-solid ratio 3:1, leaching time 3 h), leach the oxidized and roasted neodymium iron boron waste to obtain the acid leaching solution, in which all rare earth elements and gallium elements are dissolved, and part of the iron elements are dissolved. The elemental composition of the acid leaching solution is shown in Table 2. Table 2 shows the elemental composition of the acid leaching solution in Example 2 of the present invention.

[0203] Table 2

[0204] Element Fe Nd Pr Dy Co Al Ca Ga Cu B Concentration (g / L) 140 41 10 1.4 1.2 2 1 0.48 0.4 2.3

[0205] 1. Extract and separate gallium.

[0206] Use a mixed solvent of 4% trioctyl decyl tertiary amine, 10% isodecanol and diluent n - heptane to perform 9 - stage extraction and phase separation on the acid leaching solution to obtain a gallium - containing organic phase and a first raffinate. The Ga content in the raffinate is only 0.01 g / L, and the gallium extraction rate reaches 97.9%. The extraction conditions are: the phase ratio of organic phase to aqueous phase is 1:1; the extraction temperature is 25°C; the extraction time is 5 min. 3+ The content is only 0.01 g / L, and the gallium extraction rate reaches 97.9%. The extraction conditions are: the phase ratio of organic phase to aqueous phase is 1:1; the extraction temperature is 25°C; the extraction time is 5 min.

[0207] 2. Back - extract the gallium - containing organic phase.

[0208] The Ga content in the gallium - containing organic phase is 0.47 g / L, and the Fe content is 5 g / L. After 3 - stage back - extraction with deionized water, a first back - extract and a blank organic phase are obtained. The Ga content in the back - extract is 9.4 g / L, and the Fe content is 100 g / L. The contents of other impurity ions (Co, Cu, Al, etc.) are less than 1 mg / L. The enrichment multiple of Ga is about 20, and the Fe / Ga ratio drops to about 11. The back - extraction phase ratio is: organic phase to aqueous phase = 20:1; the back - extraction temperature range is 25°C; the back - extraction time is 5 min. 3+ The content is 0.47 g / L, and the Fe content is 5 g / L. After 3 - stage back - extraction with deionized water, a first back - extract and a blank organic phase are obtained. The Ga content in the back - extract is 9.4 g / L, and the Fe content is 100 g / L. The contents of other impurity ions (Co, Cu, Al, etc.) are less than 1 mg / L. The enrichment multiple of Ga is about 20, and the Fe / Ga ratio drops to about 11. The back - extraction phase ratio is: organic phase to aqueous phase = 20:1; the back - extraction temperature range is 25°C; the back - extraction time is 5 min. 3+ The Ga content in the back - extract is 9.4 g / L, and the Fe content is 100 g / L. The contents of other impurity ions (Co, Cu, Al, etc.) are less than 1 mg / L. The enrichment multiple of Ga is about 20, and the Fe / Ga ratio drops to about 11. The back - extraction phase ratio is: organic phase to aqueous phase = 20:1; the back - extraction temperature range is 25°C; the back - extraction time is 5 min. 3+ The Ga content in the back - extract is 9.4 g / L, and the Fe content is 100 g / L. The contents of other impurity ions (Co, Cu, Al, etc.) are less than 1 mg / L. The enrichment multiple of Ga is about 20, and the Fe / Ga ratio drops to about 11. The back - extraction phase ratio is: organic phase to aqueous phase = 20:1; the back - extraction temperature range is 25°C; the back - extraction time is 5 min. 3+ The Ga content in the back - extract is 9.4 g / L, and the Fe content is 100 g / L. The contents of other impurity ions (Co, Cu, Al, etc.) are less than 1 mg / L. The enrichment multiple of Ga is about 20, and the Fe / Ga ratio drops to about 11. The back - extraction phase ratio is: organic phase to aqueous phase = 20:1; the back - extraction temperature range is 25°C; the back - extraction time is 5 min. 2+ Co 2+ Cu 3+ Al 3+ The enrichment multiple of Ga is about 20, and the Fe / Ga ratio drops to about 11. The back - extraction phase ratio is: organic phase to aqueous phase = 20:1; the back - extraction temperature range is 25°C; the back - extraction time is 5 min. 3+ Fe 3+ / Ga

[0209] 3. Further separate Ga / Fe. 3+ / Fe 3+ Further separate Ga / Fe.

[0210] The purity of the gallium oxide product is measured to be 98.5%, and the gallium recovery rate reaches 80%. Others are the same as in Example 1.

[0211] 4. Extract and separate iron.

[0212] Use a mixed solvent of 40% trioctyl decyl tertiary amine and 30% isodecanol to perform 10 - stage counter - current extraction on the first raffinate, and phase separation to obtain a second raffinate and an iron - containing organic phase. The extraction conditions are: the phase ratio of organic phase to aqueous phase is 4:1; the extraction temperature is 25°C; the extraction time is 15 min.

[0213] 5. Back - extract the iron - containing organic phase.

[0214] Use 1.2 mol / L oxalic acid solution to perform 5 - stage back - extraction on the iron - containing organic phase to obtain a second back - extract and a blank organic phase. The Fe content in the back - extract3+ The content is about 33 g / L, and the content of other impurity ions is lower than 10 mg / L. The stripping phase ratio is: organic phase: aqueous phase = 1:1; the stripping temperature range is 25 °C; the stripping time is 10 min. The second stripping solution is evaporated and concentrated, and then cooled and crystallized to obtain iron oxalate crystals. The iron oxalate crystals are oxidized and roasted at 500 °C for 2 h to obtain iron oxide red products. After measurement, its purity is 98.9%, and the iron recovery rate reaches 90%.

[0215] Example 3

[0216] Source of raw material acid leaching solution: The raw material neodymium iron boron waste acid leaching solution is prepared in the laboratory. Under the leaching conditions (hydrochloric acid concentration 6 mol / L, leaching temperature 90 °C, liquid-solid ratio 3:1, leaching time 4 h), the roasted neodymium iron boron waste is leached to obtain the acid leaching solution, in which rare earth elements, gallium elements and iron elements are all dissolved. The elemental composition of the acid leaching solution is shown in Table 3. Table 3 is the elemental composition of the acid leaching solution in Example 1 of the present invention.

[0217] Table 3

[0218] Element Fe Nd Pr Dy Co Al Ca Ga Cu B Concentration (g / L) 200 41 10 1.4 1.2 2.5 1 0.48 0.45 2.3

[0219] 1. Extract and separate gallium.

[0220] The acid leaching solution is subjected to 9-stage extraction and phase separation using a mixed solvent of 4% trioctyl decyl tertiary amine, 10% isodecanol and diluent sulfonated kerosene to obtain a gallium-containing organic phase and a first raffinate. The content of Ga in the raffinate 3+ is only 0.02 g / L left, and the gallium extraction rate reaches 95.8%. The extraction conditions are: phase ratio is organic phase: aqueous phase = 1:1; extraction temperature is 25 °C; extraction time is 5 min.

[0221] 2. Strip the gallium-containing organic phase.

[0222] The content of Ga in the gallium-containing organic phase 3+ is 0.46 g / L, and the content of Fe 3+ is 7 g / L. After 4-stage stripping with deionized water, a first stripping solution and a blank organic phase are obtained. The content of Ga in the stripping solution 3+ is 9.2 g / L, and the content of Fe 3+ is 140 g / L. The content of other impurity ions (Co 2+ , Cu 2+ , Al 3+ , etc.) is lower than 10 mg / L. The enrichment multiple of Ga 3+ is about 20, and the Fe 3+ / Ga 3+ ratio drops to about 15. The stripping phase ratio is: organic phase: aqueous phase = 20:1; the stripping temperature range is 25 °C; the stripping time is 5 min.

[0223] 3. Ga 3+ / Fe 3+ Further separation.

[0224] The purity of the gallium oxide product was determined to be 98.2%, and the gallium recovery rate reached 86%. Others are the same as in Example 1.

[0225] 4. Extract and separate iron.

[0226] Use a mixed solvent of 40% trioctyl decyl tertiary amine and 30% isooctanol to perform 10-stage countercurrent extraction on the first raffinate, and separate the phases to obtain the second raffinate and the iron-containing organic phase. The extraction conditions are: the phase ratio is organic phase: aqueous phase = 6:1; the extraction temperature is 25°C; the extraction time is 10 min.

[0227] 5. Back-extraction of the iron-containing organic phase.

[0228] Use 1.2 mol / L oxalic acid solution to perform 5-stage back-extraction on the iron-containing organic phase to obtain the second back-extraction solution and the blank organic phase. The Fe 3+ content in the back-extraction solution is about 32 g / L, and the contents of other impurity ions are all lower than 10 mg / L. The back-extraction phase ratio is: organic phase: aqueous phase = 1:1; the back-extraction temperature range is 25°C; the back-extraction time is 10 min. Evaporate and concentrate the second back-extraction solution, and cool and crystallize to obtain iron oxalate crystals. The iron oxalate crystals are oxidized and calcined at 500°C for 2 h to obtain iron oxide red products. The purity is determined to be 97.8%, and the iron recovery rate reaches 91%.

[0229] Example 4

[0230] The difference from Example 1 is that the amine extractant is N,N-bis(1-methylheptyl)acetamide. The gallium-containing organic phase is back-extracted, and the Fe 3+ / Ga 3+ ratio drops to about 13. The purity of the gallium oxide is determined to be 98.5%, and the gallium recovery rate reaches 86%. The purity of the iron oxide is determined to be 98.4%, and the iron recovery rate reaches 92%.

[0231] Example 5

[0232] The difference from Example 2 is that the amine extractant is N,N-bis(1-methylheptyl)acetamide. The gallium-containing organic phase is back-extracted, and the Fe 3+ / Ga 3+ ratio drops to about 12. The purity of the gallium oxide product is determined to be 97.8%, and the gallium recovery rate reaches 80%. The purity of the iron oxide is determined to be 98.2%, and the iron recovery rate reaches 90%.

[0233] Example 6

[0234] The difference from Example 3 is that the amine extractant is N,N - bis(1 - methylheptyl)acetamide. The gallium - containing organic phase is subjected to back - extraction. In the back - extraction liquid, the Fe 3+ / Ga 3+ ratio drops to about 16. The purity of the gallium oxide product is measured to be 97.6%, and the gallium recovery rate reaches 86%. The purity of the iron oxide is measured to be 97.2%, and the iron recovery rate reaches 91%.

[0235] Example 7

[0236] The difference from Example 1 is that the amine extractant is methyltrioctylammonium chloride. The gallium - containing organic phase is subjected to back - extraction. In the back - extraction liquid, the Fe 3+ / Ga 3+ ratio drops to about 16. The purity of the gallium oxide is 97.9%, and the gallium recovery rate reaches 85%. The purity of the iron oxide is measured to be 98%, and the iron recovery rate reaches 92%.

[0237] Example 8

[0238] The difference from Example 2 is that the amine extractant is methyltrioctylammonium chloride. The gallium - containing organic phase is subjected to back - extraction. In the back - extraction liquid, the Fe 3+ / Ga 3+ ratio drops to about 15. The purity of the gallium oxide product is measured to be 97.1%, and the gallium recovery rate reaches 80%. The purity of the iron oxide is measured to be 97.9%, and the iron recovery rate reaches 90%.

[0239] Example 9

[0240] The difference from Example 3 is that the amine extractant is methyltrioctylammonium chloride. The gallium - containing organic phase is subjected to back - extraction. In the back - extraction liquid, the Fe 3+ / Ga 3+ ratio drops to about 18. The purity of the gallium oxide product is measured to be 97.5%, and the gallium recovery rate reaches 85%. The purity of the iron oxide is measured to be 97%, and the iron recovery rate reaches 91%.

[0241] The above has introduced in detail a method for stepwise extracting gallium and iron from the acid leaching solution of neodymium iron boron waste by solvent extraction. In this article, specific examples are used to elaborate on the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention, including the best mode, and also enables any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The protection scope of the present invention patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to the literal description of the claims, or if they include equivalent structural elements that have no substantial difference from the literal description of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A method for extracting gallium and iron from neodymium-iron-boron waste, characterized in that, It includes the following steps: 1) After roasting the neodymium-iron-boron waste, it is placed in an acid solution for acid leaching to obtain an acid leaching solution of neodymium-iron-boron waste; 2) Using a mixed solvent composed of an amine extractant, an alcohol phase modifier, and a diluent, the acid leaching solution obtained in the above step is subjected to the first countercurrent extraction, and after phase separation, a first raffinate and a gallium-containing organic phase are obtained; 3) Mix the gallium-containing organic phase obtained in the above steps with water for the first back extraction to obtain a first back extraction solution, then add an alkali solution to the first back extraction solution to adjust the pH value for precipitation to obtain a solution containing GaO₂ - and then add an acid solution to the solution containing GaO₂ - to adjust the pH value again for re-precipitation to obtain a precipitate. Finally, calcine the precipitate to obtain gallium oxide; Using a mixed solvent composed of an amine extractant, an alcohol phase modifier, and a diluent, the first raffinate obtained in the above step is subjected to the second countercurrent extraction, and after phase separation, a second raffinate and an iron-containing organic phase are obtained; The iron-containing organic phase and an oxalic acid solution are mixed and then subjected to the second stripping to obtain a second stripping solution, and then the second stripping solution is evaporated and crystallized to obtain iron oxalate crystals, and finally the iron oxalate crystals are roasted again to obtain iron oxide red.

2. The method according to claim 1, characterized in that The roasting time is 3 to 3.5 hours; The roasting temperature is 800 to 850 °C; In the above step 1), the acid solution includes a hydrochloric acid solution; In the above step 1), the concentration of the acid solution is 2 to 4 mol / L; The acid leaching time is 12 to 13 hours; The concentration of the acid leaching solution of neodymium-iron-boron waste is 2 to 2.5 mol / L.

3. The method according to claim 1, characterized in that, The acid leaching solution of neodymium-iron-boron waste, calculated by element concentration, includes: Fe: 50 to 200 g / L; Nd: 30 to 40 g / L; Pr: 9 to 12 g / L; Dy: 1 to 2 g / L; Co: 0.8 to 2 g / L; Al: 1 to 3 g / L; Ca: 0.9 to 2 g / L; Ga: 0.3 to 0.5 g / L; Cu: 0.3 to 0.5 g / L; B: 1.9 to 3 g / L.

4. The method according to claim 1, wherein The amine extractant includes one or more of trioctyldecyl tertiary amine, N,N-bis(1-methylheptyl)acetamide, and methyltrioctylammonium chloride; The alcohol phase modifier includes isodecanol and / or isooctanol; The diluent includes an alkane diluent and / or an aromatic diluent; In the mixed solvent, the volume concentration of the amine extractant is 2% to 5%; In the mixed solvent, the volume concentration of the alcohol phase modifier is 10% to 15%.

5. The method according to claim 1, wherein The first countercurrent extraction method includes multi-stage countercurrent extraction; In the first countercurrent extraction, the volume ratio of the organic phase to the aqueous phase is (2 to 1):(1 to 2); The temperature of the first countercurrent extraction is 25 to 35 °C; The time of the first countercurrent extraction is 5 to 10 min; The extraction stage number of the first countercurrent extraction is 8 to 12 stages.

6. The method according to claim 1, characterized in that, The first stripping method includes multi-stage countercurrent extraction; In the first stripping, the volume ratio of the organic phase to the aqueous phase is (20 to 30):1; The temperature of the first stripping is 25 to 35 °C; The time of the first stripping is 5 to 10 min; The extraction stage number of the first stripping is 3 to 6 stages; The alkali solution includes a sodium hydroxide solution; The concentration of the alkali solution is 2 to 4 mol / L.

7. The method according to claim 1, wherein The specific pH value adjustment is 13 to 14; The acid solution includes a hydrochloric acid solution; The concentration of the acid solution is 1 to 3 mol / L; The specific re-adjustment of the pH value is 6 to 7; The temperatures of the precipitation and the re-precipitation are each independently selected from 50 to 70 °C; The roasting time is 30 to 90 min; The roasting temperature is 800 to 900 °C.

8. The method according to claim 1, characterized in that In the step 3), the amine extractant includes one or more of trioctyldecyl tertiary amine, N,N-bis(1-methylheptyl)acetamide, and methyltrioctylammonium chloride; In the step 3), the alcohol phase modifier includes isodecanol and / or isooctanol; In the step 3), the diluent includes an alkane diluent and / or an aromatic diluent; In the mixed solvent of the step 3), the volume concentration of the amine extractant is 30% to 40%; In the mixed solvent of the step 3), the volume concentration of the alcohol phase modifier is 25% to 30%; The second raffinate is fed into the subsequent rare earth recovery process.

9. The method according to claim 1, characterized in that, The second countercurrent extraction method includes multi-stage countercurrent extraction; In the second countercurrent extraction, the volume ratio of the organic phase to the aqueous phase is (1 to 2):1; The temperature of the second countercurrent extraction is 25 to 35 °C; The time of the second countercurrent extraction is 10 to 15 min; The extraction stage number of the second countercurrent extraction is 6 to 10 stages; The concentration of the oxalic acid solution is 0.8 to 1.2 mol / L.

10. The method according to claim 1, wherein The second stripping method includes multi-stage countercurrent extraction; In the second stripping, the volume ratio of the organic phase to the aqueous phase is (1 to 2):1; The temperature of the second stripping is 25 to 35 °C; The time of the second stripping is 10 to 15 min; The extraction stage number of the second stripping is 3 to 6 stages; The evaporation and crystallization are specifically evaporation concentration and cooling crystallization; The time of the re-roasting is 90 to 120 min; The temperature of the re-roasting is 450 to 500 °C.

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