Recycling method of laterite-nickel ore hydrometallurgy wastewater

Abstract

The invention provides a cyclic utilization method of laterite-nickel ore hydrometallurgy wastewater, which comprises the following steps: laterite-nickel ore is sequentially subjected to high-pressure acid leaching, cyclic leaching, CCD (Charge Coupled Device) washing, iron and aluminum removal treatment, MHP (Methyl Hydroxypropyl Phosphate) precipitation treatment and manganese precipitation treatment to obtain manganese-precipitated wastewater; carrying out ion exchange on the manganese-deposited wastewater to obtain an ion-exchanged solution and a nickel-cobalt-enriched solution; the enriched nickel and cobalt solution is circulated to CCD washing; carrying out magnesium separation on the solution after ion exchange to obtain a magnesium-rich solution and a magnesium-poor solution; the magnesium-rich liquid is circulated to the MHP precipitation treatment, and / or the magnesium-rich liquid is crystallized to obtain a magnesium sulfate product; performing bipolar membrane electrolysis on the magnesium-poor solution to obtain a sodium hydroxide solution and a sulfuric acid solution; the sodium hydroxide solution is circulated to the iron and aluminum removal treatment, and the sulfuric acid solution is circulated to the circulating leaching treatment. Wastewater resources can be fully utilized, and the method is environmentally friendly, economical and wide in application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a method for recycling laterite nickel ore hydrometallurgical wastewater. Background Art

[0002] In the process of refining nickel, cobalt and other valuable metals in the laterite nickel ore hydrometallurgical process, wastewater containing complex metal ions, such as Ni, Co, Mn, Mg, Fe, Zn, Al, etc., is inevitably produced. These wastewaters not only contain potential resources, but also may become the source of environmental pollution. Therefore, their effective recycling is not only a consideration of economic benefits, but also an urgent need for environmental protection.

[0003] In the process of preparing MHP (nickel cobalt hydroxide) intermediates by hydrometallurgy of laterite nickel ore, commonly used precipitants include sodium hydroxide and magnesium oxide. However, the use of sodium hydroxide in industrial production will cause the reaction system to become partially over-alkaline, which will not only increase the manganese content in MHP, but also reduce the nickel and cobalt content accordingly. The increase in manganese content will increase the cost of subsequent refining steps. In addition, the over-alkaline environment also leads to an accelerated nucleation rate of MHP, resulting in particles with smaller particle size and uneven distribution, which makes it difficult for MHP to be effectively precipitated and filtered, resulting in a high moisture content of the filter cake, thereby increasing the transportation cost of MHP. In addition, in the existing process, when nickel and cobalt are completely precipitated and separated, the filtrate of this process section mainly contains Mn and Mg elements. In the wastewater treatment process, a specific precipitant is usually used to precipitate manganese, and then the generated manganese slag is filtered and landfilled. The filtrate after manganese slag filtration mainly contains Mg. Since the filtrate is alkaline, it is generally neutralized with sulfuric acid and discharged into the ocean.

[0004] It can be seen that the existing laterite nickel ore hydrometallurgical wastewater treatment technology still has shortcomings, and new pollutants are often generated during the wastewater treatment process, which has an adverse impact on the environment. Although a variety of technologies and methods have been applied to the treatment and recycling of such wastewater, there are still some challenges, such as high treatment costs, compatibility issues between technologies, and the risk of secondary pollution.

[0005] Therefore, how to improve the recycling rate of laterite nickel ore hydrometallurgical wastewater and reduce its impact on the environment is a difficult problem that needs to be solved urgently. Summary of the invention

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for recycling laterite-nickel ore hydrometallurgical wastewater, which can solve the problems of low treatment efficiency and secondary pollution of laterite-nickel ore hydrometallurgical wastewater in the prior art.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for recycling laterite nickel ore hydrometallurgical wastewater, the recycling method comprising the following steps:

[0009] (1) The laterite nickel ore is sequentially subjected to high pressure acid leaching, circulating leaching, CCD washing, iron and aluminum removal treatment, MHP precipitation treatment and manganese precipitation treatment to obtain wastewater after manganese precipitation;

[0010] (2) the wastewater after manganese precipitation is subjected to ion exchange to obtain an ion exchange liquid and a nickel-cobalt enriched solution; the nickel-cobalt enriched solution is circulated to the CCD washing in step (1);

[0011] (3) the ion exchanged liquid is subjected to magnesium separation to obtain a magnesium-rich liquid and a magnesium-poor liquid; the magnesium-rich liquid is circulated to the MHP precipitation treatment in step (1), and / or the magnesium-rich liquid is crystallized to obtain a magnesium sulfate product;

[0012] (4) The magnesium-depleted solution is subjected to bipolar membrane electrolysis to obtain a sodium hydroxide solution and a sulfuric acid solution; the sodium hydroxide solution is circulated to the iron and aluminum removal treatment in step (1), and the sulfuric acid solution is circulated to the high-pressure leaching in step (1).

[0013] The wastewater targeted by the method for recycling laterite nickel ore hydrometallurgical wastewater provided by the present invention is mainly wastewater after manganese precipitation. By combining subsequent ion exchange, magnesium separation and bipolar membrane electrolysis processes, the comprehensive recovery and recycling of magnesium, nickel, cobalt, sodium hydroxide and sulfate in the wastewater after manganese precipitation can be achieved without generating additional waste liquid, and the application prospect is broad.

[0014] Specifically, the present invention recovers nickel and cobalt in the wastewater after manganese precipitation through ion exchange, which can not only reduce the nickel and cobalt content in the wastewater and better meet environmental protection requirements, but also return the nickel and cobalt recovered after ion exchange to CCD washing, which can also improve the utilization rate of nickel and cobalt. Magnesium salts and sodium salts are separated by extraction or ion selective membrane technology. The sodium salt is converted into sodium hydroxide solution and sulfuric acid solution by bipolar membrane electrolysis. Part of the former is reused in the iron and aluminum removal process (as a neutralizing agent), and part of it is used in the manganese precipitation process (as a precipitant) together with magnesium salt; the latter is reused in the acid leaching process, and the remaining magnesium salt can be recovered as magnesium sulfate by evaporation and crystallization. The intermediate product recovered by the recycling method of the present invention can be further purified or extracted to obtain the corresponding product, or directly reused in the pre-process of hydrometallurgy to make SO4 2- 、Na + Mg 2+ OH - 、Ni 2+ 、Co 2+ In addition, the present invention recycles OH in wastewater by adopting the above method. - 、Na+ Mg 2+ It is also used in the MHP precipitation process. The final MHP product has the same or even better performance as the product prepared with industrial-grade sodium hydroxide and magnesium oxide, and significantly reduces the production cost, so it has broad application prospects.

[0015] In the present invention, CCD washing refers to a continuous counter-current washing process, the purpose of which is to wash away dissolved substances (such as metal ions) in solid substances by continuously using solvents, thereby improving the extraction efficiency. Precipitation MHP treatment refers to precipitation of metal hydroxide treatment, which refers to converting metal ions in a metal-containing solution into metal hydroxides through a chemical precipitation reaction.

[0016] Preferably, the pH value of the iron and aluminum removal treatment in step (1) is set to 3.8-5.5, for example, it can be 3.8, 4, 4.2, 4.4, 4.6, 4.8, 5, 5.2, 5.4 or 5.5, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0017] Preferably, the pH value of the MHP precipitation treatment in step (1) is set to 6.3-8.5, for example, it can be 6.3, 6.6, 6.8, 7.1, 7.3, 7.6, 7.8, 8.1, 8.3 or 8.5, but is not limited to the listed values, and other values ​​not listed in the range are also applicable.

[0018] Preferably, the temperature of the MHP treatment in step (1) is 55-70°C, for example, it can be 55°C, 57°C, 59°C, 60°C, 62°C, 64°C, 65°C, 67°C, 69°C or 70°C, but it is not limited to the listed values, and other values ​​not listed in this range are also applicable. Preferably, the time of the MHP treatment in step (1) is 2-10h, for example, it can be 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h or 10h, but it is not limited to the listed values, and other values ​​not listed in this range are also applicable.

[0019] Preferably, the manganese precipitation treatment in step (1) comprises adding alkali to the liquid after MHP precipitation treatment to remove manganese.

[0020] Preferably, the pH value of the solution after adding alkali in the manganese precipitation treatment is 9.5-11, for example, it can be 9.5, 9.7, 9.9, 10, 10.2, 10.4, 10.5, 10.7, 10.9 or 11, but is not limited to the listed values, and other values ​​not listed in this range are also applicable.

[0021] The present invention has no special requirements on the specific processes and techniques of the above-mentioned cyclic leaching, CCD washing, iron and aluminum removal treatment, MHP precipitation treatment and manganese precipitation treatment, and can be carried out using process parameters well known to those skilled in the art, which will not be described in detail here.

[0022] Preferably, the solution after the MHP precipitation treatment contains nickel ions: 3-4 g / L, for example, 3 g / L, 3.2 g / L, 3.3 g / L, 3.4 g / L, 3.5 g / L, 3.6 g / L, 3.7 g / L, 3.8 g / L, 3.9 g / L or 4 g / L; cobalt ions are 0.1-0.6 g / L, for example, 0.1 g / L, 0.16 g / L, 0.22 g / L, 0.27 g / L, 0.33 g / L, 0.38 g / L, 0.44 g / L, 0.49 g / L, 0.55 g / L or 0.6 g / L; manganese ions are 2.0-3.0 g / L, for example, 2.0 g / L, 2.2 g / L, 0.1-1.0 g / L, for example, 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L or 1.0 g / L; and 0.0-10 g / L, for example, 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L or 1.0 g / L.

[0023] Preferably, the wastewater after manganese precipitation contains magnesium: 5.8-8.6 g / L, for example, 5.8 g / L, 6.2 g / L, 6.5 g / L, 6.8 g / L, 7.1 g / L, 7.4 g / L, 7.7 g / L, 8 g / L, 8.3 g / L or 8.6 g / L, but is not limited to the listed values, and other values ​​not listed in the range are also applicable; Nickel:

[0024] 2.8-4.0 g / L, for example, 2.8 g / L, 3 g / L, 3.1 g / L, 3.2 g / L, 3.4 g / L, 3.5 g / L, 3.6 g / L, 3.8 g / L, 3.9 g / L or 4.0 g / L, but not limited to the values ​​listed, other values ​​not listed in the range are also applicable; Cobalt: 0.1-0.6 g / L, for example, 0.1 g / L, 0.16 g / L, 0.22 g / L, 0.27 g / L, 0.33 g / L, 0.36 g / L .38g / L, 0.44g / L, 0.49g / L, 0.55g / L or 0.6g / L, etc., but not limited to the listed values, other values ​​not listed within the range are equally applicable; Sodium: 0.5-5g / L, for example, 0.5g / L, 1g / L, 1.5g / L, 2g / L, 2.5g / L, 3g / L, 3.5g / L, 4g / L, 4.5g / L or 5g / L, etc., but not limited to the listed values, other values ​​not listed within the range are equally applicable.

[0025] Preferably, the ion exchange in step (2) comprises: sending the wastewater after manganese precipitation to a resin adsorption column for ion exchange to obtain a nickel-cobalt adsorption resin and an ion-exchanged liquid, and using a desorbent to desorb the nickel-cobalt adsorption resin to obtain an enriched nickel-cobalt solution.

[0026] Preferably, the resin adsorption column comprises a cationic resin or a chelating resin.

[0027] Preferably, the cationic resin is a strongly acidic cation exchange resin.

[0028] Preferably, the chelating resin is M4195 chelating ion exchange resin and / or IRC-748 chelating ion exchange resin.

[0029] The present invention preferably uses the above resin for adsorption separation, which can separate nickel, cobalt, magnesium and sodium with high separation efficiency.

[0030] Preferably, the ion exchange temperature is 20-40°C, for example, it can be 20°C, 23°C, 25°C, 27°C, 29°C, 32°C, 34°C, 36°C, 38°C or 40°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0031] Preferably, the flow rate of the wastewater after manganese precipitation in the ion exchange is 1 to 4 BV / h, for example, it can be 1 BV / h, 1.4 BV / h, 1.7 BV / h, 2 BV / h, 2.4 BV / h, 2.7 BV / h, 3 BV / h, 3.4 BV / h, 3.7 BV / h or 4 BV / h, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0032] The present invention preferably uses the above flow rate for separation, which has a better separation effect.

[0033] Preferably, the desorbent comprises an inorganic acid.

[0034] Preferably, the concentration of hydrogen ions in the desorbed inorganic acid is ≥0.01 mol / L, for example, it can be 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L, 0.1 mol / L, 0.12 mol / L, 0.13 mol / L, 0.14 mol / L or 0.15 mol / L, etc.

[0035] Preferably, the desorbed inorganic acid comprises any one of sulfuric acid, hydrochloric acid or nitric acid or a combination of at least two thereof, wherein typical but non-limiting combinations are a combination of sulfuric acid and hydrochloric acid, a combination of nitric acid and hydrochloric acid, and a combination of sulfuric acid and nitric acid.

[0036] Preferably, the flow rate of the desorbent is 0.1 to 1 BV / h, for example, it can be 0.1 BV / h, 0.2 BV / h, 0.3 BV / h, 0.4 BV / h, 0.5 BV / h, 0.6 BV / h, 0.7 BV / h, 0.8 BV / h, 0.9 BV / h or 1 BV / h, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0037] Preferably, the desorption temperature is 20-40°C, for example, it can be 20°C, 23°C, 25°C, 27°C, 29°C, 32°C, 34°C, 36°C, 38°C or 40°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0038] Preferably, the ion exchange liquid contains magnesium: 5.5-8.6 g / L, for example, 5.5 g / L, 5.9 g / L, 6.2 g / L, 6.6 g / L, 6.9 g / L, 7.3 g / L, 7.6 g / L, 8 g / L, 8.3 g / L or 8.6 g / L, but not limited to the listed values, other values ​​not listed in this range are also applicable; nickel: 0.01-0.05 g / L, for example, 0.01 g / L, 0.015 g / L, 0.019 g / L, 0.024 g / L, 0.028 g / L, 0.033 g / L, 0.037 g / L, 0.042 g / L, 0.046 g / L or 0.05 g / L, but not limited to the listed values, in this range Other unlisted values ​​are equally applicable; Cobalt: 0.01-0.02 g / L, for example, 0.01 g / L, 0.012 g / L, 0.013 g / L, 0.014 g / L, 0.015 g / L, 0.016 g / L, 0.017 g / L, 0.018 g / L, 0.019 g / L or 0.02 g / L, but are not limited to the listed values, and other unlisted values ​​within the range are equally applicable; Sodium: 0.5-5 g / L, for example, 0.5 g / L, 1 g / L, 1.5 g / L, 2 g / L, 2.5 g / L, 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L or 5 g / L, but are not limited to the listed values, and other unlisted values ​​within the range are equally applicable.

[0039] Preferably, the magnesium separation in step (3) comprises extraction separation and / or membrane separation.

[0040] Preferably, the extraction separation comprises: extracting the ion exchange liquid with an extraction system to separate an organic phase and a raffinate, then acid-washing the organic phase, and then stripping with a stripping agent to obtain a magnesium-rich solution and a raffinate to obtain a magnesium-poor solution.

[0041] Preferably, the extraction system comprises an extractant and a diluent.

[0042] Preferably, the extractant comprises BC196.

[0043] The ion exchange liquid of the present invention mainly contains magnesium and sodium. BC196 is preferably used as the extractant, and kerosene is preferably used as the diluent, which can significantly improve the separation effect of magnesium and sodium.

[0044] More preferably, a synergist is added during the extraction.

[0045] Preferably, the synergistic extractant is L-aspartic acid.

[0046] The present invention preferably adopts the above-mentioned synergistic extractant, which can better achieve the separation of magnesium and sodium and improve the separation efficiency of the two.

[0047] Preferably, the mass ratio of the co-extraction agent to the extractant is 0.1 to 0.2:1, for example, it can be 0.1:1, 0.12:1, 0.13:1, 0.14:1, 0.15:1, 0.16:1, 0.17:1, 0.18:1, 0.19:1 or 0.2:1, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0048] Preferably, the mass ratio of the extractant to the diluent is 0.1 to 0.5:1, for example, it can be 0.1:1, 0.15:1, 0.19:1, 0.24:1, 0.28:1, 0.33:1, 0.37:1, 0.42:1, 0.46:1 or 0.5:1, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0049] Preferably, the diluent comprises kerosene.

[0050] Preferably, the extraction system is a saponified extraction system.

[0051] Preferably, the saponification rate of the extraction system is 25-40%, for example, it can be 25%, 27%, 29%, 30%, 32%, 34%, 35%, 37%, 39% or 40%, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0052] Preferably, the O / A ratio during the extraction process is (1-3):1, for example, it can be 1:1, 1.3:1, 1.5:1, 1.7:1, 1.9:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1 or 3:1, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0053] Preferably, the extraction stages are 3 to 8, for example, 3, 4, 5, 6, 7 or 8 stages.

[0054] Preferably, the acid concentration of the pickling is 0.1-0.8 mol / L, for example, it can be 0.1 mol / L, 0.18 mol / L, 0.26 mol / L, 0.34 mol / L, 0.42 mol / L, 0.49 mol / L, 0.57 mol / L, 0.65 mol / L, 0.73 mol / L or 0.8 mol / L, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0055] Preferably, the pickling washing stages are 6 to 10, for example, 6, 7, 8, 9 or 10 stages.

[0056] Preferably, the pickling acid comprises hydrochloric acid and / or sulfuric acid.

[0057] Preferably, the stripping agent for the stripping comprises an inorganic acid.

[0058] Preferably, the inorganic acid for stripping is sulfuric acid.

[0059] Preferably, the acid concentration of the stripping is 3.0 to 6.5 mol / L, for example, 3.0 mol / L, 3.39 mol / L, 3.78 mol / L, 4.17 mol / L, 4.56 mol / L, 4.95 mol / L, 5.34 mol / L, 5.73 mol / L, 6.12 mol / L or 6.5 mol / L, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0060] Preferably, the number of stripping stages is 4 to 8, for example, it can be 4, 5, 6, 7 or 8 stages.

[0061] Preferably, the membrane separation comprises: using an ion selective membrane to perform membrane separation on monovalent metal ions and divalent metal ions in the liquid after ion exchange.

[0062] Specifically, the ion selective membranes available may be the CIMS series products sold by the Chinese manufacturer Hangzhou Lanran Technology Co., Ltd.

[0063] Preferably, the temperature of the membrane separation is 25-45°C, for example, it can be 25°C, 28°C, 30°C, 32°C, 34°C, 37°C, 39°C, 41°C, 43°C or 45°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0064] Preferably, the pressure of the membrane separation is 0.5-1.5 MPa, for example, it can be 0.5 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa or 1.5 MPa, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0065] Preferably, the current density of the bipolar membrane electrolysis is 15 to 20 A / m 2 , for example, it can be 15A / m 2 , 15.6A / m 2 , 16.2A / m 2 , 16.7A / m 2 、17.3A / m2 、17.8A / m 2 、18.4A / m 2 、18.9A / m 2 、19.5A / m 2 or 20A / m 2 The above values ​​are not limited to the above values, and other values ​​not listed in the above values ​​are also applicable.

[0066] Preferably, the membrane material of the bipolar membrane electrolysis includes any one of polystyrene sulfonic acid, polytetrafluoroethylene, polyether sulfone, polyurethane or polyvinyl alcohol, or a combination of at least two thereof.

[0067] Preferably, the temperature of the bipolar membrane electrolysis is 20-45°C, for example, it can be 20°C, 23°C, 26°C, 29°C, 32°C, 34°C, 37°C, 40°C, 43°C or 45°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0068] Preferably, the sodium hydroxide solution in step (4) is mixed with the magnesium-rich solution in step (3) and then reused in the MHP precipitation process.

[0069] In the MHP precipitation process, the present invention premixes sodium hydroxide with part of the magnesium-rich liquid to generate magnesium hydroxide. Magnesium hydroxide, as a weakly alkaline substance, can avoid or reduce the influence of "local over-alkalinity" generated when sodium hydroxide is used alone, so that the nucleation rate of MHP is moderate, and then particles with appropriate particle size and uniform distribution are generated. This not only effectively reduces the moisture content of the filter cake, but also helps to reduce the transportation cost of MHP.

[0070] Preferably, when the sodium hydroxide solution in step (4) is mixed with the magnesium-rich solution in step (3), the Na + With Mg in some magnesium-rich solution 2+ The amount ratio of the substance is 1:(1-9), for example, it can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:5, 1:6, 1:7, 1:7.5, 1:8, 1:8.5 or 1:9, etc.

[0071] In the present invention, magnesium-rich liquid is mixed with sodium hydroxide to generate magnesium hydroxide, which is a weakly alkaline substance. Relying solely on magnesium hydroxide as a precipitant will result in a high magnesium content and a low nickel content in the prepared MHP, thereby increasing the transportation cost of MHP and the cost of using a P507 extractant to remove magnesium in the subsequent refining process. Therefore, the present invention achieves the coexistence of sodium hydroxide and magnesium hydroxide by controlling the molar ratio of Na+ in the sodium hydroxide solution to Mg2+ in the magnesium-rich liquid to 1:1-9, and uses it as a mixed precipitant to participate in the precipitation process of MHP, thereby improving the effect of MHP co-precipitation.

[0072] Preferably, after the sodium hydroxide solution in step (4) is mixed with the magnesium-rich solution in step (3), the ratio of the sum of the molar amounts of sodium and magnesium elements in the mixed system to the sum of the molar amounts of nickel and cobalt elements in the laterite nickel ore after iron and aluminum removal satisfies: (Na×2+Mg) / (Ni+Co)=1.

[0073] The present invention has no special restrictions on the implicit solid-liquid separation in the above process. Any device and method for solid-liquid separation known to those skilled in the art can be used, and can also be adjusted according to the actual process, such as filtration, centrifugation or sedimentation separation, or a combination of different methods.

[0074] The present invention has no special restrictions on the implicit drying steps in the above process. Any device and method known to those skilled in the art for drying can be used, and can also be adjusted according to the actual process. For example, it can be air drying, vacuum drying, oven drying or freeze drying, or a combination of different methods.

[0075] It is worth noting that the key of the present invention is to sequentially perform manganese precipitation treatment on the wastewater after MHP treatment to remove manganese, then perform ion exchange to recover nickel and cobalt, then perform magnesium separation to recover magnesium, and finally perform bipolar membrane electrolysis to recover sodium hydroxide and sulfuric acid solution. The order and chronological relationship between each step The core inventive concept of the present invention is to develop a technical route for sequentially recovering manganese, nickel and cobalt, magnesium, sodium hydroxide and sulfuric acid, so as to efficiently recover valuable substances, reduce the discharge of wastewater, and improve the economic value of the whole process. When the order is changed or a certain step is not performed, it will cause the overall process flow to be difficult to stably circulate. These valuable substances returned to step (1) can also improve the nickel and cobalt recovery rate and the product quality of the hydroxide in the MHP treatment step.

[0076] Compared with the prior art, the present invention has at least the following beneficial effects:

[0077] (1) The method for recycling laterite nickel ore hydrometallurgical wastewater provided by the present invention can realize the comprehensive circulation and reuse of nickel, cobalt, magnesium, sodium hydroxide and sulfate in the wastewater after manganese precipitation, reduce the discharge and post-treatment burden of wastewater, and improve economic benefits;

[0078] (2) The method for recycling laterite nickel ore hydrometallurgical wastewater provided by the present invention improves the quality of the hydroxide product obtained by precipitation by recycling the magnesium-rich liquid and the sodium hydroxide solution obtained in step (4) to the MHP precipitation treatment. Specifically, the water content of the hydroxide product is reduced to less than 50%, and the particle size D50 of the hydroxide is above 15.5 μm;

[0079] (3) The method for recycling laterite nickel ore hydrometallurgical wastewater provided by the present invention improves the recovery rate of nickel and cobalt in the overall process, with the nickel precipitation rate being above 99.5% and the cobalt precipitation rate being above 99.0%;

[0080] (4) The magnesium sulfate product prepared by the recycling method of laterite nickel ore hydrometallurgical wastewater provided by the present invention meets the external sales standards and has a purity of more than 98wt%;

[0081] (5) In the preferred embodiment of the method for recycling laterite nickel ore hydrometallurgical wastewater provided by the present invention, the recycling rate of nickel and cobalt reaches more than 99.5%, the recovery rate of magnesium ions reaches more than 98%, the recovery rate of sodium hydroxide resources reaches more than 96%, and the recovery rate of sulfate ions reaches more than 98%, and the application prospect is broad. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 It is a flow chart of a method for recycling laterite nickel ore hydrometallurgical wastewater provided in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0083] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0084] As a specific embodiment of the present invention, a method for recycling laterite nickel ore hydrometallurgical wastewater is provided, see Figure 1 , the recycling method comprises the following steps:

[0085] (1) the laterite nickel ore is sequentially subjected to high pressure acid leaching, circulating leaching, CCD washing, iron and aluminum removal treatment, and MHP precipitation treatment to obtain wastewater after MHP precipitation, and the wastewater after MHP precipitation is subjected to manganese precipitation treatment to obtain wastewater after manganese precipitation;

[0086] (2) the wastewater after manganese precipitation is subjected to ion exchange to obtain an ion exchange liquid and a nickel-cobalt enriched solution; the nickel-cobalt enriched solution is circulated to the CCD washing in step (1);

[0087] (3) the ion exchanged liquid is subjected to magnesium separation to obtain a magnesium-rich liquid and a magnesium-poor liquid; the magnesium-rich liquid is circulated to the MHP precipitation treatment in step (1), and / or the magnesium-rich liquid is crystallized to obtain a magnesium sulfate product;

[0088] (4) The magnesium-depleted solution is subjected to bipolar membrane electrolysis to obtain a sodium hydroxide solution and a sulfuric acid solution; the sodium hydroxide solution is circulated to the iron and aluminum removal treatment in step (1), and the sulfuric acid solution is circulated to the high-pressure leaching in step (1).

[0089] Example 1

[0090] This embodiment provides a method for recycling laterite nickel ore hydrometallurgical wastewater, the recycling method comprising the following steps:

[0091] (1) The laterite nickel ore is sequentially subjected to high-pressure acid leaching, circulating leaching, CCD washing, iron and aluminum removal treatment under pH=4.0, MHP precipitation treatment at pH=6.5 and 60°C for 5 hours, and filtered to obtain wastewater after MHP precipitation; alkali is added to the wastewater after MHP precipitation to adjust the pH to 10.0 to remove manganese, and filtered to obtain wastewater after manganese precipitation;

[0092] (2) The wastewater after manganese precipitation was fed into an M4195 chelating ion exchange resin adsorption column at 2.5 BV / h for ion exchange at 35°C to obtain nickel-cobalt adsorption resin and ion exchange liquid. + Using 0.02 mol / L hydrochloric acid as a desorbent to desorb the nickel-cobalt adsorption resin, the flow rate of the desorbent is 0.5 BV / h, the temperature is 30° C., to obtain an enriched nickel-cobalt solution, which is circulated to the CCD washing in step (1);

[0093] (3) extracting the ion exchange liquid using an extraction system (10 wt% BC196 as an extractant, 1 wt% L-aspartic acid as a co-extractant, 89 wt% kerosene as a diluent, and a saponification rate of 30%), with an O / A ratio of 3:1 and an extraction stage of 8; separating to obtain an organic phase and a raffinate, then washing the organic phase with a 0.1 mol / L sulfuric acid solution, with the washing stage of 8, and finally stripping with a 3.0 mol / L sulfuric acid solution, with the stripping stage of 6, the stripping liquid obtained is a magnesium-rich liquid, and the raffinate is a magnesium-poor liquid; part of the magnesium-rich liquid is reused in the MHP precipitation process, and the remaining magnesium-rich liquid is evaporated and crystallized to obtain magnesium sulfate;

[0094] (4) The magnesium-poor solution is electrolyzed by bipolar membrane at a current density of 18 A / m 2 , the temperature is 30°C, and a sodium hydroxide solution and a sulfuric acid solution are obtained; a part of the sodium hydroxide solution is circulated to the iron and aluminum removal treatment in step (1), and a part of it is mixed with the magnesium-rich solution in step (3) and then recycled to the MHP precipitation treatment, and the Na in the sodium hydroxide solution is controlled. + With Mg in some magnesium-rich solution 2+ The molar ratio of the substance is 1:1, and the ratio of the sum of the molar amounts of sodium and magnesium elements to the sum of the molar amounts of nickel and cobalt elements in the laterite nickel ore after iron and aluminum removal satisfies: (Na×2+Mg) / (Ni+Co)=1; the sulfuric acid solution is circulated to the high-pressure leaching in step (1).

[0095] Example 2

[0096] This embodiment provides a method for recycling laterite nickel ore hydrometallurgical wastewater, the recycling method comprising the following steps:

[0097] (1) The laterite nickel ore is sequentially subjected to high-pressure acid leaching, circulating leaching, CCD washing, iron and aluminum removal treatment under pH=5.5, MHP precipitation treatment at pH=6.3 and 70°C for 2h, and filtered to obtain wastewater after MHP precipitation; alkali is added to the wastewater after MHP precipitation to adjust the pH to 11 to remove manganese, and filtered to obtain wastewater after manganese precipitation;

[0098] (2) The wastewater after manganese precipitation was fed into an M4195 chelating ion exchange resin adsorption column at 4.0 BV / h for ion exchange at 20°C to obtain nickel-cobalt adsorption resin and ion exchange liquid. + Using 0.03 mol / L hydrochloric acid as a desorbent to desorb the nickel-cobalt adsorption resin, the flow rate of the desorbent is 0.1 BV / h, the temperature is 20° C., to obtain an enriched nickel-cobalt solution, which is circulated to the CCD washing in step (1);

[0099] (3) extracting the ion exchange liquid using an extraction system (20 wt% BC196 as an extractant, 4 wt% L-aspartic acid as a co-extractant, 76 wt% kerosene as a diluent, and a saponification rate of 40%), with an O / A ratio of 1:1 and three extraction stages; separating to obtain an organic phase and a raffinate, then washing the organic phase with a 0.8 mol / L sulfuric acid solution, with 10 stages of washing, and finally stripping with a 6.5 mol / L sulfuric acid solution, with eight stages of stripping, the stripping liquid obtained is a magnesium-rich liquid, and the raffinate is a magnesium-poor liquid; part of the magnesium-rich liquid is reused in the MHP precipitation process, and the remaining magnesium-rich liquid is evaporated and crystallized to obtain magnesium sulfate;

[0100] (4) The magnesium-poor solution is electrolyzed by bipolar membrane at a current density of 20 A / m 2 , the temperature is 45°C, and a sodium hydroxide solution and a sulfuric acid solution are obtained; a part of the sodium hydroxide solution is circulated to the iron and aluminum removal treatment in step (1), and a part of it is mixed with the magnesium-rich solution in step (3) and then recycled to the MHP precipitation treatment, and the Na in the part of the sodium hydroxide solution is controlled. + With Mg in some magnesium-rich solution 2+ The molar ratio of the substance is 1:7, and the ratio of the sum of the molar amounts of sodium and magnesium elements to the sum of the molar amounts of nickel and cobalt elements in the laterite nickel ore after iron and aluminum removal satisfies: (Na×2+Mg) / (Ni+Co)=1; the sulfuric acid solution is circulated to the high-pressure leaching in step (1).

[0101] Example 3

[0102] This embodiment provides a method for recycling laterite nickel ore hydrometallurgical wastewater, the recycling method comprising the following steps:

[0103] (1) The laterite nickel ore is sequentially subjected to high-pressure acid leaching, circulating leaching, CCD washing, iron and aluminum removal treatment under pH=3.8, MHP precipitation treatment at pH=8.5 and 55°C for 10 hours, and filtered to obtain wastewater after MHP precipitation; alkali is added to the wastewater after MHP precipitation to adjust the pH to 9.5 to remove manganese, and filtered to obtain wastewater after manganese precipitation;

[0104] (2) The wastewater after manganese precipitation was fed into an M4195 chelating ion exchange resin adsorption column at 1.0 BV / h for ion exchange at 40°C to obtain nickel-cobalt adsorption resin and ion exchange liquid. + Using 0.01 mol / L hydrochloric acid as a desorbent to desorb the nickel-cobalt adsorption resin, the flow rate of the desorbent is 1.0 BV / h, the temperature is 40° C., to obtain an enriched nickel-cobalt solution, which is circulated to the CCD washing in step (1);

[0105] (3) extracting the ion exchange liquid using an extraction system (30 wt% BC196 as an extractant, 3 wt% L-aspartic acid as a co-extractant, 67 wt% kerosene as a diluent, and a saponification rate of 25%), with an O / A ratio of 3:1 and a number of extraction stages of 6; separating to obtain an organic phase and a raffinate, then washing the organic phase with a 0.1 mol / L sulfuric acid solution, with a number of washing stages of 6, and finally stripping with a 3.0 mol / L sulfuric acid solution, with a number of stripping stages of 4, the stripping liquid obtained is a magnesium-rich liquid, and the raffinate is a magnesium-poor liquid; part of the magnesium-rich liquid is reused in the MHP precipitation process, and the remaining magnesium-rich liquid is evaporated and crystallized to obtain magnesium sulfate;

[0106] (4) The magnesium-poor solution is electrolyzed by bipolar membrane at a current density of 15 A / m 2 , the temperature is 20°C, and a sodium hydroxide solution and a sulfuric acid solution are obtained; a part of the sodium hydroxide solution is circulated to the iron and aluminum removal treatment in step (1), and a part of it is mixed with the magnesium-rich solution in step (3) and then recycled to the MHP precipitation treatment, and the Na in this part of the sodium hydroxide solution is controlled. + With Mg in some magnesium-rich solution 2+ The molar ratio of the substance is 1:9, and the ratio of the sum of the molar amounts of sodium and magnesium elements to the sum of the molar amounts of nickel and cobalt elements in the laterite nickel ore after iron and aluminum removal satisfies: (Na×2+Mg) / (Ni+Co)=1; the sulfuric acid solution is circulated to the high-pressure leaching in step (1).

[0107] Example 4

[0108] This embodiment provides a method for recycling laterite nickel ore hydrometallurgical wastewater, wherein the recycling method includes the following steps: + With Mg in some magnesium-rich solution 2+ Except that the molar ratio of the substances is 1:0.5, the rest is the same as that in Example 1 and will not be repeated here.

[0109] Example 5

[0110] This embodiment provides a method for recycling laterite nickel ore hydrometallurgical wastewater, wherein the recycling method includes the following steps: + With Mg in some magnesium-rich solution 2+ Except that the molar ratio of the substances is 1:10, the rest is the same as that in Example 1 and will not be repeated here.

[0111] Example 6

[0112] This embodiment provides a method for recycling laterite nickel ore hydrometallurgical wastewater. The recycling method is the same as that of Example 1 except that L-aspartic acid is not added as a co-extractant in step (3), and will not be described in detail here.

[0113] Example 7

[0114] The present embodiment provides a method for recycling laterite nickel ore hydrometallurgical wastewater. The recycling method is the same as that of Example 1, except that the amount of L-aspartic acid added in step (3) is as high as 5wt%, and the amount of kerosene is simultaneously reduced to 85wt%. The details are not repeated here.

[0115] Example 8

[0116] This embodiment provides a method for recycling laterite nickel ore hydrometallurgical wastewater. The recycling method is the same as that of Example 1, except that L-aspartic acid in step (3) is replaced by an equal amount of tributyl phosphate, and the details are not repeated here.

[0117] Example 9

[0118] This embodiment provides a method for recycling laterite nickel ore hydrometallurgical wastewater. The recycling method is the same as Example 1 except that the M4195 chelating ion exchange resin adsorption column is replaced by an IRC-748 chelating ion exchange resin adsorption column, and the details are not repeated here.

[0119] Comparative Example 1

[0120] This comparative example provides a method for recycling laterite nickel ore hydrometallurgical wastewater. In the recycling method, the wastewater is directly reused in MHP precipitation treatment after MHP precipitation and manganese precipitation. The rest is the same as Example 1 and will not be repeated here.

[0121] Comparative Example 2

[0122] This comparative example provides a method for recycling laterite nickel ore hydrometallurgical wastewater. The recycling method does not perform step (3) and step (4), and uses industrial-grade sodium hydroxide and magnesium oxide to replace the sodium hydroxide solution obtained by bipolar membrane electrolysis and the magnesium-rich solution obtained by extraction, respectively, and is added to the precipitated MHP. The rest is the same as Example 1 and will not be repeated here.

[0123] Comparative Example 3

[0124] This comparative example provides a method for recycling laterite nickel ore hydrometallurgical wastewater. The recycling method is the same as Example 1 except that the manganese precipitation treatment is not performed and the MHP precipitation wastewater is directly subjected to ion exchange in step (2). The details are not repeated here.

[0125] Since manganese is not removed first in this comparative example, it is difficult to carry out the subsequent ion exchange and extraction process, and it is impossible to achieve efficient recovery of valuable resources.

[0126] The above embodiments and comparative examples are basically stable after 10 cycles. At this time, the theoretical nickel hydroxide content is expected to be 40%, the cobalt hydroxide content is 4%, and the manganese hydroxide content is 7% when MHP is precipitated. The component content, particle size and moisture content of the MHP filter cake obtained by the MHP precipitation process after the 10th cycle are tested. Examples 1 to 5 and comparative examples 1 to 2 are used as examples for detection. The test results are shown in Table 1.

[0127] Table 1

[0128]

[0129]

[0130] The results in Table 1 show the following:

[0131] (1) It can be seen from Examples 1 to 3 that the MHP filter cake prepared by recycling the laterite nickel ore hydrometallurgical wastewater by the method of the present invention has good performance, wherein the mass proportion of nickel hydroxide, cobalt hydroxide and manganese hydroxide obtained by precipitation is closer to the theoretical design, and the water content in the filter cake is as low as less than 47.3%, and can even reach 45.07%. The particle size D50 is above 15.8 μm, which is easier to filter in industrial production and can effectively avoid the problem of filter cake clogging the filter device.

[0132] (2) Combining Examples 1 and 4-5, it can be seen that the Na in the sodium hydroxide solution recycled to the MHP treatment in Examples 4-5 + With Mg in some magnesium-rich solution 2+ The ratio of the amount of substances is not within the preferred range, resulting in a smaller value of the particle size D50 in the filter cake in Example 4, a high water content, and a filtering performance that is not as good as that in Example 1. Although the particle size D50 in Example 5 is large, the mass ratio of nickel hydroxide, cobalt hydroxide, and manganese hydroxide deviates far from the theoretical design, which shows that the Na in the sodium hydroxide solution recycled to the MHP precipitation treatment in step (4) is + With Mg in some magnesium-rich solution 2+ The amount ratio of substances is controlled within a reasonable range, which can better reduce the water content in the hydroxide product obtained by MHP precipitation treatment, and the mass ratio of nickel hydroxide, cobalt hydroxide and manganese hydroxide is closer to the theoretical design, which is more conducive to industrial production.

[0133] (3) It can be seen from Example 1 and Comparative Examples 1 to 2 that in Comparative Example 1, the wastewater after manganese removal from the MHP precipitate is directly reused in the MHP precipitate treatment, resulting in the accumulation of sodium element, and the filter cake has a high moisture content and a small particle size, and the filtration performance is relatively poor; even if the purchased sodium hydroxide and magnesium oxide are additionally added in Comparative Example 2, it is difficult to achieve the effect of reducing the moisture content and increasing the particle size in Example 1. This shows that the present invention uses ion exchange resin, extraction and bipolar membrane electrolysis to recycle the sodium hydroxide and magnesium-rich solution recovered to the MHP precipitate, which can not only improve the resource utilization rate, but also improve the filter cake performance of the original MHP precipitate treatment, which is more conducive to industrial production.

[0134] The recovery rate of sulfate is obtained by dividing the sum of sulfate in the sulfuric acid solution produced by bipolar membrane electrolysis and sulfate in the magnesium sulfate product by the sum of sulfate in the waste water after manganese precipitation and sulfate added in step (3); the recovery rate of sodium hydroxide is obtained by dividing the hydroxide ions produced by bipolar membrane electrolysis by the hydroxide ions in the waste water after manganese precipitation; the amount of nickel and cobalt in the filter cake obtained by MHP precipitation treatment is divided by the amount of nickel and cobalt in the iron and aluminum removal treatment solution, which are respectively recorded as the nickel precipitation rate and the cobalt precipitation rate; the recovery rate of magnesium is obtained by dividing the sum of magnesium ions in the magnesium sulfate obtained and the magnesium content in the filter cake obtained by MHP precipitation treatment by the amount of magnesium in the iron and aluminum removal treatment solution.

[0135] The data of the recovery rate and precipitation rate of the above embodiments and comparative examples are shown in Table 2.

[0136] Table 2

[0137]

[0138]

[0139] In Table 2, “ / ” indicates that there is no relevant data.

[0140] From Table 2, we can see the following points:

[0141] (1) It can be seen from Examples 1 to 3 that the present invention can achieve a magnesium ion recovery rate of more than 98%, a sodium hydroxide resource recovery rate of more than 96%, a sulfate recovery rate of more than 98%, a nickel precipitation rate of more than 99.5%, and a cobalt precipitation rate of more than 99.0% by recycling laterite nickel ore hydrometallurgical wastewater. The recovery rate of each resource is excellent and the application prospect is broad.

[0142] (2) Combining Examples 1 and 4-5, it can be seen that the Na in the sodium hydroxide solution recycled to the MHP treatment in Examples 4-5 + With Mg in some magnesium-rich solution 2+ The ratio of the amount of substances is not within the preferred range, resulting in the Co precipitation rate in Example 4 being reduced to 98.2%, and the Co precipitation rate and Mg recovery rate in Example 5 being reduced compared with Example 1, which shows that the present invention preferably uses the NaOH solution recycled to the MHP precipitation process. + With Mg in some magnesium-rich solution 2+ The amount ratio of substances is controlled within a reasonable range, which can better improve the Co precipitation rate and Mg recovery rate.

[0143] (3) It can be seen from Example 1 and Examples 6 to 8 that L-aspartic acid is not added as a co-extractant in Example 6, and L-aspartic acid is replaced by an equal amount of tributyl phosphate in Example 8, resulting in insufficient Mg extraction rate during the extraction process, and the Mg recovery rate is only 95.2% and 95.9%, resulting in a high magnesium content in the magnesium-depleted solution, affecting the subsequent bipolar membrane electrolysis, and it is difficult to achieve the recovery of sodium hydroxide and sulfuric acid solution; in Example 7, the amount of L-aspartic acid added is relatively high, but the Mg recovery rate is reduced compared with Example 1, and there is a waste of the co-extractant. This shows that the present invention preferably uses L-aspartic acid as a co-extractant and controls its content within a reasonable range, which can better improve the Mg extraction rate and is conducive to the subsequent electrolytic preparation of sodium hydroxide and sulfuric acid solutions.

[0144] (4) It can be seen from Example 1 and Comparative Examples 1 to 2 that in Comparative Example 1, the wastewater after manganese removal from MHP precipitation is directly reused in MHP precipitation treatment, and the recovery of Mg, sodium hydroxide and sulfuric acid resources cannot be achieved; in Comparative Example 2, industrial-grade sodium hydroxide and magnesium oxide are used to replace the sodium hydroxide solution obtained by bipolar membrane electrolysis and the magnesium-rich solution obtained by extraction, respectively, and are added to the MHP precipitation. The final precipitation rates of nickel and cobalt are lower than those of Example 1, and it is difficult to achieve the recovery of Mg, sodium hydroxide and sulfuric acid resources. This shows that the present invention can not only achieve the recovery cycle of multiple resources through a series of ion exchange, extraction and bipolar membrane electrolysis process, but also improve the precipitation rates of nickel and cobalt.

[0145] The present invention illustrates the detailed features of the present invention through the above embodiments, but the present invention is not limited to the above detailed features, that is, it does not mean that the present invention must rely on the above detailed features to be implemented. Those skilled in the art should understand that any improvement to the present invention, equivalent replacement of the technical features selected by the present invention, addition of auxiliary technical features, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for recycling laterite nickel ore hydrometallurgical wastewater, characterized in that: The recycling method comprises the following steps: (1) The laterite nickel ore is sequentially subjected to high pressure acid leaching, circulating leaching, CCD washing, iron and aluminum removal treatment, MHP precipitation treatment and manganese precipitation treatment to obtain wastewater after manganese precipitation; (2) the wastewater after manganese precipitation is subjected to ion exchange to obtain an ion exchange liquid and a nickel-cobalt enriched solution; the nickel-cobalt enriched solution is circulated to the CCD washing in step (1); (3) the ion exchanged liquid is subjected to magnesium separation to obtain a magnesium-rich liquid and a magnesium-poor liquid; the magnesium-rich liquid is circulated to the MHP precipitation treatment in step (1), and / or the magnesium-rich liquid is crystallized to obtain a magnesium sulfate product; (4) The magnesium-depleted solution is subjected to bipolar membrane electrolysis to obtain a sodium hydroxide solution and a sulfuric acid solution; the sodium hydroxide solution is circulated to the iron and aluminum removal treatment in step (1), and the sulfuric acid solution is circulated to the high-pressure leaching in step (1).

2. The recycling method according to claim 1, characterized in that: The ion exchange in step (2) comprises: sending the wastewater after manganese precipitation to a resin adsorption column for ion exchange to obtain nickel-cobalt adsorption resin and ion exchange liquid, and using a desorbent to desorb the nickel-cobalt adsorption resin to obtain an enriched nickel-cobalt solution.

3. The recycling method according to claim 2, characterized in that: The resin adsorption column includes a cationic resin or a chelating resin; Preferably, the cationic resin is a strongly acidic cation exchange resin; Preferably, the chelating resin is M4195 chelating ion exchange resin and / or IRC-748 chelating ion exchange resin.

4. The recycling method according to claim 2 or 3, characterized in that: The temperature of the ion exchange is 20 to 40°C; Preferably, the flow rate of the wastewater after manganese precipitation in the ion exchange is 1 to 4 BV / h.

5. The recycling method according to any one of claims 1 to 4, characterized in that: The desorbent includes an inorganic acid; Preferably, the concentration of hydrogen ions in the desorbed inorganic acid is ≥ 0.01 mol / L; Preferably, the desorbed inorganic acid comprises any one of sulfuric acid, hydrochloric acid or nitric acid, or a combination of at least two thereof; Preferably, the flow rate of the desorbent is 0.1 to 1 BV / h; Preferably, the desorption temperature is 20-40°C.

6. The recycling method according to any one of claims 1 to 5, characterized in that: The magnesium separation in step (3) includes extraction separation and / or membrane separation.

7. The recycling method according to claim 5, characterized in that: The extraction separation comprises: extracting the ion exchange liquid with an extraction system to separate an organic phase and a raffinate, then acid-washing the organic phase, and then stripping with a stripping agent to obtain a stripping liquid that is a magnesium-rich liquid, and a raffinate that is a magnesium-poor liquid; Preferably, the extraction system comprises an extractant and a diluent; Preferably, the extractant comprises BC196; Preferably, a synergist is also added during the extraction; Preferably, the synergistic extractant is L-aspartic acid; Preferably, the mass ratio of the co-extraction agent to the extraction agent is 0.1 to 0.2:1; Preferably, the diluent comprises kerosene; Preferably, the extraction system is a saponified extraction system; Preferably, the saponification rate of the extraction system is 25-40%; Preferably, the O / A ratio during the extraction process is (1-3):1; Preferably, the extraction stages are 3 to 8; Preferably, the acid concentration of the pickling is 0.1 to 0.8 mol / L; Preferably, the number of washing stages of the pickling is 6 to 10; Preferably, the pickling acid comprises hydrochloric acid and / or sulfuric acid; Preferably, the stripping agent of the stripping comprises an inorganic acid; Preferably, the inorganic acid for stripping is sulfuric acid; Preferably, the acid concentration of the stripping is 3.0 to 6.5 mol / L; Preferably, the number of stripping stages is 4 to 8.

8. The recycling method according to claim 5 or 6, characterized in that: The membrane separation comprises: using an ion selective membrane to perform membrane separation on monovalent metal ions and divalent metal ions in the ion exchange liquid; Preferably, the temperature of the membrane separation is 25 to 45°C; Preferably, the pressure of the membrane separation is 0.5-1.5 MPa.

9. The recycling method according to any one of claims 1 to 8, characterized in that: The current density of the bipolar membrane electrolysis is 15-20A / m 2 ; Preferably, the temperature of the bipolar membrane electrolysis is 20-45°C.

10. The recycling method according to any one of claims 1 to 9, characterized in that: The sodium hydroxide solution in step (4) is mixed with the magnesium-rich solution in step (3) and then reused in the MHP precipitation process; Preferably, when the sodium hydroxide solution in step (4) is mixed with the magnesium-rich solution in step (3), the Na + With Mg in some magnesium-rich solution 2+ The molar ratio of substances is 1:(1~9).

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