A method for comprehensive utilization of laterite nickel ore leaching residue

Abstract

The present invention provides a method for comprehensive utilization of laterite nickel ore leaching residue, and belongs to the technical field of comprehensive utilization of industrial solid waste. The method comprises the following steps: S1: acid leaching the laterite nickel ore leaching residue to be treated with acid 1, and obtaining leaching residue and leaching solution after solid-liquid separation; S2: adding nano Fe3O4 crystal seeds and additive 1 to the leaching solution obtained in step S1, adding acid 2 to adjust the pH of the mixed solution to 0-2, and performing hydrothermal reaction. After the reaction is completed, the obtained product is simultaneously subjected to ultrasonic and magnetic separation, and the obtained non-magnetic solution is subjected to solid-liquid separation to obtain filter residue 1 and filtrate 1; S3: after concentrating the filtrate 1 obtained in step S2, adding alkali to adjust the pH of the concentrated solution to 7-12, and separating to obtain nickel salt. By using nano Fe3O4 crystal seeds for crystallization, Fe and Ni in the laterite nickel ore leaching residue can be selectively separated, and the utilization value of the laterite nickel ore can be fully utilized.

Description

Technical Field

[0001] The invention relates to the technical field of comprehensive utilization of industrial solid waste, and in particular to a method for comprehensive utilization of laterite nickel ore leaching residue. Background Art

[0002] Laterite nickel ore contains a large amount of valuable metal elements such as nickel and iron. In order to improve resource utilization, it is necessary to maximize the extraction of these elements from laterite nickel ore and obtain corresponding high value-added products. The mainstream method for extracting elements from laterite nickel ore at home and abroad is acid leaching, that is, leaching the nickel element therein through sulfuric acid and the like. However, the main treatment method for laterite nickel ore leaching residue is landfill, which greatly wastes these valuable resources. In the current context where there is still a huge demand for resources such as Ni\Co\Fe in the field of lithium-ion batteries, it is very necessary to maximize the efficiency of utilizing these valuable elements from laterite nickel ore leaching residue.

[0003] Products such as iron phosphate and nickel hydroxide are usually used as precursors for the positive electrode of lithium-ion batteries. Obtaining products such as iron phosphate with qualified purity from laterite nickel ore leaching residue will greatly alleviate the resource pressure in the field of lithium-ion batteries. For laterite nickel ore acid leaching residue, the iron and nickel have similar chemical properties, and the difficulty lies in the selective separation of iron and nickel. However, there is currently no systematic method for obtaining valuable elements from laterite nickel ore leaching residue, and the problems usually faced are low product purity and low element recovery rate. If there is a way to highly selectively separate elements such as Fe and Ni in laterite nickel ore leaching residue, then this will give full play to the utilization value of laterite nickel ore. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for comprehensive utilization of laterite nickel ore leaching residue, which can selectively separate Fe and Ni in the laterite nickel ore leaching residue and give full play to the utilization value of the laterite nickel ore.

[0005] To achieve the above object, the technical solution adopted by the present invention is: to provide a method for comprehensive utilization of laterite nickel ore leaching residue, comprising the following steps:

[0006] S1: acid leaching the laterite nickel ore leaching residue to be treated with acid 1, and obtaining leaching residue and leaching liquid after solid-liquid separation;

[0007] S2: Add nano-Fe3O4 seeds and additive 1 to the leaching solution obtained in step S1, add acid 2 to adjust the pH of the mixed solution to 0-2, and perform hydrothermal reaction. After the reaction, the obtained products are simultaneously subjected to ultrasonic and magnetic separation, and the obtained non-magnetic solution is subjected to solid-liquid separation to obtain filter residue 1 and filtrate 1;

[0008] S3: After concentrating the filtrate 1 obtained in step S2, alkali is added to adjust the pH of the concentrate to 8-12, and the nickel salt is separated.

[0009] The present invention obtains nickel-iron leaching solution by acid leaching, and then adds nano Fe3O4 crystal seeds and additive 1 to the nickel-iron leaching solution. The nano Fe3O4 crystal seeds can selectively induce iron ions in the nickel-iron leaching solution. The iron ions grow in the form of Fe3O4 on the surface of the crystal seeds, and the pH value of the mixed solution is adjusted to inhibit the hydrolysis of nickel, thereby realizing the separation of nickel and iron. In the hydrothermal reaction, the additive 1 can activate the surface of the crystal seeds and promote the growth of the crystal seeds. The surface of the Fe3O4 particles obtained by the hydrothermal reaction is adsorbed with non-magnetic components. Through simultaneous treatment with ultrasound and magnetic separation, the non-magnetic components on the surface of the Fe3O4 particles can be stripped to improve the purity of the Fe3O4 particles. The purity of the Fe3O4 particles is greater than 99.5%, and can be directly used without subsequent treatment. The obtained filtrate does not need to perform an additional iron ion impurity removal process in the subsequent treatment process, which reduces the nickel recovery cost, shortens the reuse process of laterite nickel ore leaching slag, and greatly improves the utilization rate of laterite nickel ore leaching slag.

[0010] Preferably, in step S2, the pH is 1-2.

[0011] Preferably, in step S3, the pH is 8.5-10.5.

[0012] The purpose of adjusting the pH in step S3 is to precipitate the nickel ions in the filtrate as Ni(OH)2. When the pH is less than 8, the nickel ions will not precipitate. When the pH is greater than 12, it does not conform to the principles of economy and environmental protection. Therefore, the inventors prefer a pH of 8.5-10.5, which is more conducive to nickel ion precipitation and further improves the nickel recovery rate.

[0013] Preferably, the preparation method of the nano Fe3O4 seed crystal is: adding the iron complex and the additive 2 to an organic solvent for hydrothermal reaction, separating the solid and the liquid after the reaction, and annealing the obtained filter residue 2 to obtain the nano Fe3O4 seed crystal, wherein the molar ratio of the additive 2 to the iron complex is 0.1-2:1.

[0014] Under the strong reducing effect of additive 2, the iron complex generates Fe3O4. The molar ratio of additive 2 to the iron complex affects the size and dispersibility of the Fe3O4 seeds. When the molar ratio of additive 2 to the iron complex is 0.1-2:1, within this range, as the molar ratio of additive 2 to the iron complex increases, the size of the Fe3O4 seeds becomes smaller and the dispersibility becomes better. Further increasing the molar ratio of additive 2 to the iron complex does not significantly change the size of the Fe3O4 seeds, but its dispersibility becomes worse.

[0015] Preferably, at least one of the following (a)-(h):

[0016] (a) the iron complex is at least one of iron oleate, iron acetylacetonate, and ferrocene; more preferably, the iron complex is at least one of iron oleate and iron acetylacetonate;

[0017] (b) the additive 2 is at least one of oleylamine, hydrazine and vinyl pyrrolidone; more preferably, the additive 2 is oleylamine;

[0018] (c) the organic solvent is at least one of ethanol, ethylene glycol, polyethylene glycol, oleic acid, anisole and benzyl ether; more preferably, the organic solvent is at least one of anisole and benzyl ether.

[0019] In the present invention, the iron complex, under the action of the additive, first generates FeO(OH), then generates Fe3O4 nanoparticles, and finally obtains nano Fe3O4 seeds through aging. Due to the different polarities of the organic solvent and the additive, during the hydrothermal reaction, the additive can act as a surfactant and adhere to the surface of the Fe3O4 nanoparticles, inducing the directional self-assembly of the Fe3O4 nanoparticles to obtain monodisperse nano Fe3O4 seeds.

[0020] The raw materials of nano-Fe3O4 seeds have a certain influence on the performance of nano-Fe3O4 seeds. When the iron complex is at least one of iron oleate and iron acetylacetonate, the additive 2 is oleylamine, and the organic solvent is at least one of anisole and benzyl ether, the obtained nano-Fe3O4 seeds have better dispersibility.

[0021] (d) the ratio of the total volume of the additive 2 and the organic solvent to the mass of the iron complex is 1-100 mL / g;

[0022] (e) the hydrothermal reaction time is 3-24 hours; more preferably, the hydrothermal reaction time is 6-18 hours;

[0023] (f) the temperature of the hydrothermal reaction is 120-280° C.; more preferably, the temperature of the hydrothermal reaction is 150-230° C.;

[0024] The liquid-to-solid ratio (i.e., the ratio of the total volume of additive 2 and organic solvent to the mass of the iron complex), time and temperature of the hydrothermal reaction will affect the performance of the nano-Fe3O4 seed crystals; when the liquid-to-solid ratio of the hydrothermal reaction is lower than 1 mL / g, the time is less than 3 h or the temperature is lower than 120°C, the solid-liquid two phases cannot fully react, and the obtained nano-Fe3O4 seed crystals are large in size and low in dispersibility, which is not conducive to subsequent use; when the liquid-to-solid ratio of the hydrothermal reaction is higher than 100 mL / g, the time is greater than 24 h or the temperature is higher than 280°C, the performance of the nano-Fe3O4 seed crystals cannot be further improved, and energy consumption and production costs will also increase.

[0025] (g) the annealing temperature is 300-700° C.; more preferably, the annealing temperature is 400-600° C.;

[0026] (h) The annealing time is 1-24 hours; more preferably, the annealing time is 6-18 hours.

[0027] The present invention further improves the crystallinity of the nano Fe3O4 seed crystals by annealing. When the annealing temperature is less than 300°C, the nano Fe3O4 seed crystals will not be fully aged and the resulting crystallinity is poor. When the annealing temperature is higher than 700°C, the physical phase of Fe3O4 will be transformed into other phases. When the annealing temperature is 400-600°C and the annealing time is 6-18h, the crystallinity of the nano Fe3O4 seed crystals is better.

[0028] Preferably, in step S1, at least one of the following (a)-(e) is performed:

[0029] (a) the concentration of the acid 1 is 0.1-6M; more preferably, the concentration of the acid 1 is 1-3M;

[0030] (b) the acid 1 is at least one of hydrochloric acid, phosphoric acid, sulfuric acid and nitric acid; more preferably, the acid 1 is at least one of sulfuric acid and phosphoric acid;

[0031] (c) the molar ratio of the acid 1 to the iron in the laterite nickel ore leaching residue is 0.1-3:1; more preferably, the molar ratio of the acid 1 to the iron in the laterite nickel ore leaching residue is 0.5-1:1;

[0032] (d) the liquid-to-solid ratio of the acid 1 to the laterite nickel ore leaching residue is 1-30 mL / g; more preferably, the liquid-to-solid ratio of the acid 1 to the laterite nickel ore leaching residue is 3-10 mL / g;

[0033] (e) The acid leaching time is 1-12 hours; more preferably, the acid leaching time is 3-9 hours.

[0034] The present invention selectively leaches nickel and iron elements in laterite nickel ore leaching residue by controlling the conditions of acid leaching. When the concentration of acid 1 is less than 0.1M, the molar ratio of iron in acid 1 and laterite nickel ore leaching residue is less than 0.1, the liquid-solid ratio of acid 1 and laterite nickel ore leaching residue is less than 1mL / g, or the time of acid leaching is less than 1h, the laterite nickel ore slag cannot be fully dissolved, resulting in a reduced recovery rate of iron and nickel; when the concentration of acid 1 is greater than 6M, the molar ratio of iron in acid 1 and laterite nickel ore leaching residue is greater than 0.13, or the liquid-solid ratio of acid 1 and laterite nickel ore leaching residue is greater than 30mL / g, the consumption of acid 1 is high, resulting in increased costs and reduced processing efficiency; further increasing the time of acid leaching cannot improve the leaching rate of iron and nickel.

[0035] Preferably, in step S2, the molar ratio of the nano Fe3O4 seed to the iron in the leachate is 0.1-1:1; the molar ratio of the additive 1 to the iron in the leachate is 0.01-1:1. More preferably, the molar ratio of the nano Fe3O4 seed to the iron in the leachate is 0.2-0.5:1; the molar ratio of the additive 1 to the iron in the leachate is 0.1-0.3:1.

[0036] The molar ratio of nano iron oxide seeds and iron in the leachate, and the molar ratio of additive 1 and iron in the leachate affect the recovery rate of iron in the leachate. Within the above range, the recovery rate of iron is high. When the molar ratio of nano iron oxide seeds and iron in the leachate is less than 0.1 or the molar ratio of additive 1 and iron in the leachate is less than 0.01, the iron in the leachate cannot be converted into Fe3O4 and cannot be separated from nickel. When the molar ratio of nano Fe3O4 seeds and iron in the leachate is greater than 1 or the molar ratio of additive 1 and iron in the leachate is greater than 1, the treatment efficiency is reduced.

[0037] Preferably, in step S2, the additive 1 is at least one of oleylamine, hydrazine, and vinyl pyrrolidone; the acid 2 is at least one of formic acid, phosphoric acid, boric acid, sulfurous acid, oxalic acid, acetic acid, citric acid, and ascorbic acid. More preferably, the additive 1 is oleylamine.

[0038] Preferably, in step S2, the temperature of the hydrothermal reaction is 120-280°C, and the time of the hydrothermal reaction is 1-24 hours. More preferably, the temperature of the hydrothermal reaction is 150-230°C, and the time of the hydrothermal reaction is 3-9 hours.

[0039] Preferably, in step S2, the ultrasonic time is 0.1-6 hours, and the magnetic field strength of the magnetic separation is 10-1200 G. More preferably, the ultrasonic time is 0.5-3 hours, and the magnetic field strength of the magnetic separation is 10-600 G.

[0040] Within the above-mentioned magnetic field strength range, Fe3O4 can be selectively separated. When the magnetic field strength is lower than 10G, Fe3O4 cannot be separated. When the magnetic field strength is higher than 1200G, the separation effect of Fe3O4 cannot be improved and the processing cost is increased.

[0041] Preferably, in step S3, the base is at least one of ammonia water, sodium hydroxide, potassium hydroxide, and calcium hydroxide. More preferably, the base is sodium hydroxide.

[0042] Preferably, in step S3, the mass concentration of nickel in the concentrated solution is greater than 30 g / L.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The method of the present invention can obtain high-purity ferrosoferric oxide and nickel compounds, the recovery rate of iron is greater than 98.5%, the recovery rate of nickel is greater than 98%, and the purity of ferrosoferric oxide is greater than 99.5%. It can be directly used without post-treatment, which significantly improves the utilization rate of laterite nickel ore leaching residue.

[0045] (2) The present invention separates iron and nickel in the laterite nickel ore leaching residue by crystallization, and the obtained nickel-containing filtrate contains almost no iron ions, thereby avoiding the step of further iron removal and greatly reducing the treatment process of the laterite nickel ore leaching residue. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a scanning electron microscope image of the nano-Fe3O4 seed crystal obtained in Example 1;

[0047] Figure 2 This is a scanning electron microscope image of the filter residue 1 obtained in Example 1. DETAILED DESCRIPTION

[0048] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments and drawings.

[0049] The contents of main elements in the laterite nickel ore leaching residue used in the present invention are shown in Table 1.

[0050] Table 1 Main element contents in laterite nickel ore leaching residue

[0051] Main Elements Fe Ni Ca Mg Si Content (wt.%) 58.37 0.052 0.086 0.021 0.374

[0052] Example 1

[0053] This embodiment provides a method for comprehensive utilization of laterite nickel ore leaching residue, comprising the following steps:

[0054] S1: 10 g of laterite nickel ore leaching residue was acid-leached with 100 mL of 1.5 M sulfuric acid for 6 h, and solid-liquid separation was performed to obtain leaching residue 1 and leachate 1;

[0055] S2:

[0056] Preparation of nano-Fe3O4 seed crystals: 1M ferric oleate was added to 100mL anisole, and then 0.2M oleylamine was added, and the resulting mixture was hydrothermally reacted at 160°C for 6h; after the reaction, the solid-liquid separation was performed, and the resulting filter residue 2 was annealed at 500°C for 12h to obtain monodisperse nano-Fe3O4 seed crystals;

[0057] Selective separation of iron: 7.3 g of monodisperse nano Fe3O4 seeds and 0.011 mol of oleylamine were added to the leaching solution 1 obtained in step S1, and then formic acid was added to adjust the pH of the mixture to 1.2, and then hydrothermally reacted at 180°C for 12 hours; after the reaction, the obtained product was ultrasonicated for 1 hour, and a 180G magnetic field was applied at the same time to obtain nano Fe3O4 particles and a non-magnetic solution; the obtained non-magnetic solution was subjected to solid-liquid separation to obtain a filter residue 1 and a filtrate 1; wherein the filter residue 1 is impurities, and the filtrate 1 is a nickel-containing solution;

[0058] S3: After the filtrate 1 obtained in step S2 is concentrated to a nickel concentration of 35 g / L in the concentrated solution, a sodium hydroxide aqueous solution is added to adjust the pH of the concentrated solution to 8.5, and the resulting precipitate is a nickel salt.

[0059] Example 2

[0060] This embodiment provides a method for comprehensive utilization of laterite nickel ore leaching residue, comprising the following steps:

[0061] S1: 20 g of laterite nickel ore leaching residue was acid-leached with 160 mL of 2M hydrochloric acid for 3 h, and solid-liquid separation was performed to obtain leaching residue 1 and leachate 1;

[0062] S2:

[0063] Preparation of nano-Fe3O4 seed crystals: 1M ferric acetylacetonate was added to 50mL anisole, and then 0.6M oleylamine was added, and the resulting mixture was hydrothermally reacted at 180°C for 10h; after the reaction, the solid-liquid separation was performed, and the resulting filter residue 2 was annealed at 420°C for 6h to obtain monodisperse nano-Fe3O4 seed crystals;

[0064] Selective separation of iron: 24 g of monodisperse nano Fe3O4 seeds and 0.04 mol of hydrazine were added to the leaching solution 1 obtained in step S1, and then phosphoric acid was added to adjust the pH of the mixture to 1.5, and then hydrothermally reacted at 200°C for 18 hours; after the reaction, the obtained product was subjected to ultrasonic treatment for 2 hours, and a 100G magnetic field was applied to obtain nano Fe3O4 particles and a non-magnetic solution; the obtained non-magnetic solution was subjected to solid-liquid separation to obtain a filter residue 1 and a filtrate 1; wherein the filter residue 1 is impurities and the filtrate 1 is a nickel-containing solution;

[0065] S3: After the filtrate 1 obtained in step S2 is concentrated to a nickel concentration of 30 g / L in the concentrated solution, a sodium hydroxide aqueous solution is added to adjust the pH of the concentrated solution to 10.5, and the resulting precipitate is a nickel salt.

[0066] Example 3

[0067] This embodiment provides a method for comprehensive utilization of laterite nickel ore leaching residue, comprising the following steps:

[0068] S1: 5 g of laterite nickel ore leaching residue was acid-leached with 15 mL of 3 M phosphoric acid for 5 h, and solid-liquid separation was performed to obtain leaching residue 1 and leachate 1;

[0069] S2:

[0070] Preparation of nano-Fe3O4 seed crystals: 1M ferrocene was added to 80mL ethanol, and then 0.3M vinyl pyrrolidone was added, and the resulting mixture was hydrothermally reacted at 200°C for 18h; after the reaction, the solid-liquid separation was performed, and the resulting filter residue 2 was annealed at 600°C for 18h to obtain monodisperse nano-Fe3O4 seed crystals;

[0071] Selective separation of iron: 2.4 g of monodisperse nano Fe3O4 seeds and 0.01 mol of vinyl pyrrolidone were added to the leaching solution 1 obtained in step S1, and then oxalic acid was added to adjust the pH of the mixture to 1.8, and then hydrothermally reacted at 220° C. for 9 h; after the reaction, the obtained product was subjected to ultrasonic treatment for 3 h, and a 300 G magnetic field was applied at the same time to obtain nano Fe3O4 particles and a non-magnetic solution; the obtained non-magnetic solution was subjected to solid-liquid separation to obtain a filter residue 1 and a filtrate 1; wherein the filter residue 1 is impurities, and the filtrate 1 is a nickel-containing solution;

[0072] S3: After the filtrate 1 obtained in step S2 is concentrated to a nickel concentration of 40 g / L in the concentrated solution, a sodium hydroxide aqueous solution is added to adjust the pH of the concentrated solution to 9, and the resulting precipitate is a nickel salt.

[0073] Example 4

[0074] This embodiment provides a method for comprehensive utilization of laterite nickel ore leaching residue, comprising the following steps:

[0075] S1: 10 g of laterite nickel ore leaching residue was acid-leached with 50 mL of 1 M nitric acid for 8 h, and solid-liquid separation was performed to obtain leaching residue 1 and leachate 1;

[0076] S2:

[0077] Preparation of nano-Fe3O4 seeds: 1M iron oleate was added to 30mL oleic acid, and then 0.4M oleylamine was added, and the resulting mixture was hydrothermally reacted at 230°C for 12h; after the reaction, the solid-liquid separation was performed, and the resulting filter residue 2 was annealed at 560°C for 9h to obtain monodisperse nano-Fe3O4 seeds;

[0078] Selective separation of iron: add 6.1g of monodisperse nano Fe3O4 seeds and 0.03mol of oleylamine to the leaching solution 1 obtained in step S1, then add acetic acid to adjust the pH of the mixture to 1, and then hydrothermally react at 160°C for 6h; after the reaction, ultrasonicate the product for 0.5h, and apply a 450G magnetic field to obtain nano Fe3O4 particles and a non-magnetic solution; perform solid-liquid separation on the obtained non-magnetic solution to obtain a filter residue 1 and a filtrate 1; wherein the filter residue 1 is impurities and the filtrate 1 is a nickel-containing solution;

[0079] S3: After the filtrate 1 obtained in step S2 is concentrated to a nickel concentration of 36 g / L in the concentrated solution, a sodium hydroxide aqueous solution is added to adjust the pH of the concentrated solution to 9.5, and the resulting precipitate is a nickel salt.

[0080] Example 5

[0081] This embodiment provides a method for comprehensive utilization of laterite nickel ore leaching residue, comprising the following steps:

[0082] S1: 15 g of laterite nickel ore leaching residue was acid-leached with 90 mL of 1.2 M hydrochloric acid for 9 h, and solid-liquid separation was performed to obtain leaching residue 1 and leachate 1;

[0083] S2:

[0084] Preparation of nano-Fe3O4 seed crystals: 1M ferric acetylacetonate was added to 40mL benzyl methyl ether, and then 0.5M oleylamine was added, and the resulting mixture was hydrothermally reacted at 160°C for 6h; after the reaction, the solid-liquid separation was performed, and the resulting filter residue 2 was annealed at 500°C for 12h to obtain monodisperse nano-Fe3O4 seed crystals;

[0085] Selective separation of iron: 14.5 g of monodisperse nano Fe3O4 seeds and 0.04 mol of oleylamine were added to the leaching solution 1 obtained in step S1, and then boric acid was added to adjust the pH of the mixed solution to 2, and then hydrothermally reacted at 230° C. for 15 h; after the reaction, the obtained product was subjected to ultrasonic treatment for 1.5 h, and a 600 G magnetic field was applied at the same time to obtain nano Fe3O4 particles and a non-magnetic solution; the obtained non-magnetic solution was subjected to solid-liquid separation to obtain a filter residue 1 and a filtrate 1; wherein the filter residue 1 is an impurity, and the filtrate 1 is a nickel-containing solution;

[0086] S3: After the filtrate 1 obtained in step S2 is concentrated to a nickel concentration of 40 g / L in the concentrated solution, a sodium hydroxide aqueous solution is added to adjust the pH of the concentrated solution to 10, and the resulting precipitate is a nickel salt.

[0087] Comparative Example 1

[0088] This comparative example provides a method for comprehensive utilization of laterite nickel ore leaching residue. The only difference between this comparative example and Example 1 is that additive 2 is not added during the preparation of nano Fe3O4 seeds.

[0089] Comparative Example 2

[0090] This comparative example provides a method for comprehensive utilization of laterite nickel ore leaching residue. The only difference between this comparative example and Example 1 is that additive 1 is not added during the selective separation of iron.

[0091] Comparative Example 3

[0092] This comparative example provides a method for comprehensive utilization of laterite nickel ore leaching residue. The only difference between this comparative example and Example 1 is that commercial magnetite powder is used instead of monodisperse nano Fe3O4 seeds in the process of selectively separating iron.

[0093] Comparative Example 4

[0094] This comparative example provides a method for comprehensive utilization of laterite nickel ore leaching residue. The only difference between this comparative example and Example 1 is that the additive 2 in the process of selectively separating iron is sodium dodecylbenzene sulfonate.

[0095] Effect example

[0096] The recovery rate of nickel iron element was calculated based on the nickel iron element content of the laterite nickel ore leaching residue, and the results are shown in Table 2; the purity of nano Fe3O4 particles and nickel salt was calculated based on the nickel iron element content of the laterite nickel ore leaching residue, and the results are shown in Table 3.

[0097] Table 2 Recovery of iron and nickel in each embodiment and comparative example

[0098]

[0099] Table 3 Purity of recovered products obtained in each embodiment and comparative example

[0100]

[0101] As can be seen from Table 2 and Table 3, the method of the present invention is used to recycle the laterite nickel ore leaching residue, and the recovery rate of iron can reach 99.5%, the recovery rate of nickel can reach 98.5%, and the purity of the obtained recovered product (ferroferric oxide and nickel salt) is high and can be directly used. In the process of preparing nano Fe3O4 crystal seeds or selectively separating iron, without adding additives, the recovery rates of iron and nickel are significantly reduced, and the purity of the obtained recovered product is also reduced. Compared with commercial magnet powder, the nano Fe3O4 crystal seeds prepared by the present invention can effectively selectively separate iron from the leaching solution, thereby improving the recovery rate of iron. Compared with other additives, in the process of selectively separating iron, selecting at least one of oleylamine, hydrazine, and vinyl pyrrolidone as an additive can significantly improve the recovery rate of iron and nickel, and also improve the purity of the recovered product.

[0102] Finally, it should be noted that the above embodiments are used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for comprehensive utilization of laterite nickel ore leaching residue, characterized in that: The following steps are involved: S1: acid leaching the laterite nickel ore leaching residue to be treated with acid 1, and obtaining leaching residue and leaching liquid after solid-liquid separation; S2: Add nano-Fe3O4 seeds and additive 1 to the leaching solution obtained in step S1, add acid 2 to adjust the pH of the mixed solution to 0-2, and perform hydrothermal reaction. After the reaction, the obtained products are simultaneously subjected to ultrasonic and magnetic separation, and the obtained non-magnetic solution is subjected to solid-liquid separation to obtain filter residue 1 and filtrate 1; S3: After concentrating the filtrate 1 obtained in step S2, adding alkali to adjust the pH of the concentrate to 7-12, and separating and obtaining nickel salt; The preparation method of the nano Fe3O4 seed crystal is as follows: adding the iron complex and the additive 2 to an organic solvent for hydrothermal reaction, separating the solid and the liquid after the reaction, and annealing the obtained filter residue 2 to obtain the nano Fe3O4 seed crystal, wherein the molar ratio of the additive 2 to the iron complex is 0.1-2:1; The iron complex is at least one of iron oleate, iron acetylacetonate, and ferrocene; The additive 2 is at least one of oleylamine, hydrazine and vinyl pyrrolidone; The organic solvent is at least one of ethanol, ethylene glycol, polyethylene glycol, oleic acid, anisole, and benzyl ether; The additive 1 is at least one of oleylamine, hydrazine and vinyl pyrrolidone.

2. The method according to claim 1, characterized in that At least one of the following (a)-(e): (a) the temperature of the hydrothermal reaction is 120-280° C.; (b) the hydrothermal reaction time is 3-24h; (c) the ratio of the total volume of the additive 2 and the organic solvent to the mass of the iron complex is 1-100 mL / g; (d) the annealing temperature is 300-700° C.; (e) The annealing time is 1-24h.

3. The method according to claim 1, characterized in that In step S1, at least one of the following (a)-(e): (a) the concentration of the acid 1 is 0.1-6M; (b) the acid 1 is at least one of hydrochloric acid, phosphoric acid, sulfuric acid and nitric acid; (c) the molar ratio of the acid 1 to the iron in the laterite nickel ore leaching residue is 0.1-3:1; (d) the liquid-to-solid ratio of the acid 1 to the laterite nickel ore leaching residue is 1-30 mL / g; (e) The acid leaching time is 1-12 hours.

4. The method according to claim 1, wherein: In step S2, the molar ratio of the nano Fe3O4 seed crystals to the iron in the leaching solution is 0.1-1:1; the molar ratio of the additive 1 to the iron in the leaching solution is 0.01-1:

1.

5. The method according to claim 1, characterized in that: In step S2, the acid 2 is at least one of formic acid, phosphoric acid, boric acid, sulfurous acid, oxalic acid, acetic acid, citric acid, and ascorbic acid.

6. The method according to claim 1, characterized in that: In step S2, the temperature of the hydrothermal reaction is 120 to 280° C., and the time of the hydrothermal reaction is 1 to 24 hours.

7. The method of claim 1, wherein: In step S2, the ultrasonic time is 0.5-3h; the magnetic field strength of the magnetic separation is 10-1200G.

8. The method of claim 1, wherein: In step S3, the alkali is at least one of ammonia water, sodium hydroxide, potassium hydroxide and calcium hydroxide.

9. The method of claim 1, wherein: In step S3, the mass concentration of nickel in the concentrated solution is greater than 30 g / L.

Images