A method for jointly treating laterite nickel ore and nickel-iron alloy and recovering nickel and iron

Abstract

The present invention provides a method for jointly treating laterite nickel ore and nickel-iron alloy and recovering nickel and iron, comprising: (1) slurrying the laterite nickel ore and then performing acid leaching treatment, and obtaining a first leachate after solid-liquid separation; (2) mixing the nickel-iron alloy and the first leachate obtained in step (1) for reaction, and obtaining a second leachate after solid-liquid separation; (3) mixing a phosphorus source, an oxidant, a precipitant and the second leachate obtained in step (2) for reaction, and obtaining an iron phosphate product and a nickel-containing solution after solid-liquid separation; (4) sequentially removing impurities, concentrating and crystallizing the nickel-containing solution obtained in step (3) to obtain battery-grade nickel sulfate. The method utilizes the laterite nickel ore atmospheric pressure leachate, which is high in acid and rich in Fe 3+ The nickel-iron alloy is treated by using the nickel-iron to neutralize the residual acid in the leaching solution and to utilize the residual acid and Fe in the leaching solution. 3+ The strong oxidizing property promotes the dissolution of nickel-iron, achieving efficient recovery of nickel and iron, and ultimately obtaining iron phosphate and battery-grade nickel sulfate.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy and relates to a method for recovering nickel and iron, and in particular to a method for jointly treating laterite nickel ore and nickel-iron alloy and recovering nickel and iron. Background Art

[0002] At present, the new energy vehicle power batteries used in large-scale commercial applications on the market are mainly divided into two categories: ternary batteries and lithium iron phosphate batteries. The main difference between these two types of batteries is that the positive electrode material of the ternary battery is mainly oxides containing three metal elements: cobalt, nickel, and manganese, while the positive electrode material of the lithium iron phosphate battery is lithium iron phosphate. In order to obtain sufficient raw materials, many power battery raw material manufacturers are actively deploying upstream ore mining and waste recycling businesses, and strive to expand the types of raw materials.

[0003] Laterite nickel ore has been a hot topic of investment for power battery raw material companies in recent years, mainly to extract the nickel, while the higher iron content is often directly discarded as tailings, which undoubtedly causes a large waste of resources. The commonly used nickel extraction processes for laterite nickel ore are mainly divided into wet high-pressure acid leaching process and pyrometallurgical high-matte nickel process. Both processes can obtain intermediates with a high nickel content, and after further refining, battery-grade nickel sulfate is obtained. However, both of the above processes lack full utilization of iron in practical applications. Although there are also studies on atmospheric pressure acid leaching of laterite nickel ore, because its temperature is relatively low and involves the co-leaching of impurity iron, a very high acidity is required to achieve the ideal nickel leaching effect. The high acid and high iron content of the solution will undoubtedly bring huge costs for subsequent neutralization and impurity removal.

[0004] Nickel-iron alloys such as nickel pig iron produced by pyrometallurgy from laterite nickel ore are usually used in alloy fields such as stainless steel. Due to the demand of the new energy industry, nickel-iron alloys have also become one of the raw materials considered by battery raw material manufacturers. However, due to the high hardness and ductility of metals, it is extremely difficult to pre-process and crush nickel-iron alloys when used as leaching raw materials, and the leaching efficiency is low and the rate is slow.

[0005] It can be seen that how to provide a method for jointly processing laterite nickel ore and nickel-iron alloy and recovering nickel and iron, while improving recovery efficiency and product purity and reducing recovery costs as much as possible, has become an urgent problem that technical personnel in this field need to solve. 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 jointly treating laterite nickel ore and nickel-iron alloy and recovering nickel and iron, which improves the recovery efficiency and product purity while reducing the recovery cost as much as possible, and ultimately obtains iron phosphate and battery-grade nickel sulfate products.

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

[0008] The present invention provides a method for jointly treating laterite nickel ore and nickel-iron alloy and recovering nickel and iron, the method comprising the following steps:

[0009] (1) slurrying the laterite nickel ore and performing acid leaching treatment, and obtaining a first leachate after solid-liquid separation;

[0010] (2) mixing the nickel-iron alloy and the first leachate obtained in step (1) to react, and obtaining a second leachate after solid-liquid separation;

[0011] (3) mixing a phosphorus source, an oxidant, a precipitant and the second leaching solution obtained in step (2) to react, and obtaining an iron phosphate product and a nickel-containing solution after solid-liquid separation;

[0012] (4) The nickel-containing solution obtained in step (3) is sequentially subjected to impurity removal, concentration and crystallization to obtain battery-grade nickel sulfate.

[0013] Among them, the chemical formula involved in the reaction in step (2) mainly includes:

[0014] 2H + +Fe=Fe 2+ +H2

[0015] 2H + +Ni=Ni 2+ +H2

[0016] 2Fe 3+ +Fe=3Fe 2+

[0017] 2Fe 3+ +Ni=Ni 2+ +2Fe 2+

[0018] In the above reaction, the dissolution reaction of metallic iron and nickel is a reduction reaction. 3+ It has strong oxidizing properties and its participation in the reaction can significantly increase the dissolution rate of nickel and iron and accelerate the reaction.

[0019] The method provided by the present invention fully considers the reaction characteristics of laterite nickel ore and nickel-iron alloy, and utilizes the high acid and Fe-rich laterite nickel ore leaching solution to obtain a 3+ The nickel-iron alloy is treated by using the nickel-iron alloy to neutralize the residual acid in the leachate and to utilize the residual acid and Fe in the leachate. 3+ The strong oxidizing property of nickel promotes the dissolution of nickel-iron alloy, thereby achieving efficient recovery of nickel and iron in nickel-iron alloy, and finally obtaining iron phosphate and battery-grade nickel sulfate products.

[0020] Preferably, the liquid-to-solid mass ratio of the slurry adjustment in step (1) is (3-5):1, for example, it can be 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1 or 5:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] In the present invention, the slurry preparation in step (1) is performed by adding water, and the liquid-solid mass ratio specifically refers to the ratio of the amount of water added to the mass of the laterite nickel ore.

[0022] Preferably, the pressure of the acid leaching treatment in step (1) is 0.8-1.2 bar, for example, it can be 0.8 bar, 0.85 bar, 0.9 bar, 0.95 bar, 1 bar, 1.05 bar, 1.1 bar, 1.15 bar or 1.2 bar, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] Preferably, the temperature of the acid leaching treatment in step (1) is 60-100°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0024] Preferably, the acid leaching time in step (1) is 2-6 h, for example, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h or 6 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0025] Preferably, the acid solution used in the acid leaching treatment in step (1) comprises sulfuric acid.

[0026] Preferably, the concentration of sulfuric acid is 70-98wt%, for example, it can be 70wt%, 72wt%, 74wt%, 76wt%, 78wt%, 80wt%, 82wt%, 84wt%, 86wt%, 88wt%, 90wt%, 92wt%, 94wt%, 96wt% or 98wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] Preferably, the mass ratio of sulfuric acid to laterite nickel ore is (1-2):1, for example, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] In the present invention, the mass ratio of sulfuric acid to laterite nickel ore needs to be maintained within a reasonable range. When the mass ratio is lower than 1:1, that is, too little sulfuric acid, nickel and iron in the laterite nickel ore cannot be fully leached, and the recovery rate is low; when the mass ratio is higher than 2:1, that is, too much sulfuric acid, it will cause unnecessary increase in recovery cost and reduce economic benefits.

[0029] Preferably, the mixed solid-liquid ratio of the nickel-iron alloy and the first leachate in step (2) is (0.05-0.5) kg / L, for example, it can be 0.05 kg / L, 0.1 kg / L, 0.15 kg / L, 0.2 kg / L, 0.25 kg / L, 0.3 kg / L, 0.35 kg / L, 0.4 kg / L, 0.45 kg / L or 0.5 kg / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0030] Preferably, the reaction temperature in step (2) is 60-100°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] Preferably, the endpoint determination indicator of the reaction in step (2) is the pH value, and the pH at the reaction endpoint is 1.0-2.0, for example, it can be 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2.0, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] Preferably, the phosphorus source in step (3) comprises any one of phosphoric acid, sodium dihydrogen phosphate or disodium hydrogen phosphate, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of phosphoric acid and sodium dihydrogen phosphate, a combination of sodium dihydrogen phosphate and disodium hydrogen phosphate, a combination of phosphoric acid and disodium hydrogen phosphate, or a combination of phosphoric acid, sodium dihydrogen phosphate and disodium hydrogen phosphate.

[0033] Preferably, the mixing amount of the phosphorus source in step (2) is based on the molar amount of Fe in the second leachate, and P / Fe is 1.0-1.1, for example, it can be 1.0, 1.02, 1.04, 1.06, 1.08 or 1.1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] The present invention uses the molar amount of Fe in the second leaching solution as a reference mixed phosphorus source and controls P / Fe to be 1.0-1.1, thereby achieving complete conversion of the Fe element in the leaching solution into an iron phosphate product and improving the recovery efficiency.

[0035] Preferably, the oxidant in step (3) comprises any one of hydrogen peroxide, sodium hypochlorite, sodium chlorate or compressed air, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of hydrogen peroxide and sodium hypochlorite, a combination of sodium hypochlorite and sodium chlorate, a combination of sodium chlorate and compressed air, a combination of hydrogen peroxide, sodium hypochlorite and sodium chlorate, a combination of sodium hypochlorite, sodium chlorate and compressed air, or a combination of hydrogen peroxide, sodium hypochlorite, sodium chlorate and compressed air.

[0036] Preferably, the mixing amount of the oxidant in step (3) is based on the Fe 2+ All oxidized to Fe 3+ shall prevail.

[0037] Preferably, the precipitant in step (3) comprises sodium hydroxide.

[0038] Preferably, the mixing amount of the precipitant in step (3) is based on the pH of the second leachate reaching 1.5-2.0, for example, it can be 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95 or 2.0, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] Preferably, the reaction temperature in step (3) is 50-100°C, for example, it can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] Preferably, the reaction time of step (3) is 0.5-4 h, for example, 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h or 4 h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] Preferably, the ferric phosphate product obtained after the solid-liquid separation in step (3) is further washed and dried.

[0042] Preferably, the impurity removal in step (4) comprises chemical precipitation or extraction.

[0043] In the present invention, the chemical precipitation or extraction, concentration and crystallization are all conventional treatment methods in the art, as long as battery-grade nickel sulfate can be obtained from the nickel-containing solution, so the specific conditions of the above treatment are not particularly limited here.

[0044] As a preferred technical solution of the present invention, the method comprises the following steps:

[0045] (1) adding water to the laterite nickel ore at a liquid-solid mass ratio of (3-5):1 to prepare a slurry, and then adding sulfuric acid with a concentration of 70-98wt% at a pressure of 0.8-1.2 bar and a temperature of 60-100°C to carry out acid leaching for 2-6 hours, wherein the mass ratio of the sulfuric acid to the laterite nickel ore is (1-2):1, and obtaining a first leachate after solid-liquid separation;

[0046] (2) mixing the nickel-iron alloy and the first leachate obtained in step (1) at a solid-liquid ratio of (0.05-0.5) kg / L, reacting at 60-100° C. until the pH value of the solution is 1.0-2.0, and obtaining a second leachate after solid-liquid separation;

[0047] (3) mixing a phosphorus source, an oxidant, a precipitant and the second leachate obtained in step (2), reacting at 50-100° C. for 0.5-4 h, and obtaining an iron phosphate product and a nickel-containing solution after solid-liquid separation, wherein the iron phosphate product is further washed and dried; the phosphorus source comprises any one of phosphoric acid, sodium dihydrogen phosphate or disodium hydrogen phosphate, or a combination of at least two thereof, and the mixing amount of the phosphorus source is based on the molar amount of Fe in the second leachate, and P / Fe is 1.0-1.1; the oxidant comprises any one of hydrogen peroxide, sodium hypochlorite, sodium chlorate or compressed air, or a combination of at least two thereof, and the mixing amount of the oxidant is based on the molar amount of Fe in the second leachate. 2+ All oxidized to Fe 3+ The precipitant includes sodium hydroxide, and the mixing amount of the precipitant is based on the pH of the second leachate reaching 1.5-2.0;

[0048] (4) The nickel-containing solution obtained in step (3) is subjected to impurity removal, concentration and crystallization in sequence to obtain battery-grade nickel sulfate; the impurity removal includes chemical precipitation or extraction.

[0049] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) The method provided by the present invention fully considers the reaction characteristics of laterite nickel ore and nickel-iron alloy, and utilizes the high acidity and Fe-rich laterite nickel ore leachate to obtain a nickel-iron alloy. 3+ The nickel-iron alloy is treated by using the nickel-iron alloy to neutralize the residual acid in the leachate and to utilize the residual acid and Fe in the leachate. 3+ The strong oxidizing property of the ferronickel promotes the dissolution of the ferronickel alloy, thereby achieving efficient recovery of nickel and iron in the ferronickel alloy, and finally obtaining iron phosphate and battery-grade nickel sulfate products;

[0052] (2) Compared with the traditional method of treating two raw materials separately, the combined treatment method provided by the present invention greatly saves treatment costs and improves treatment efficiency. The recovered products, iron phosphate and nickel sulfate, can be used as raw materials for synthesizing battery materials, and the economic benefits are significantly improved. DETAILED DESCRIPTION

[0053] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0054] Example 1

[0055] The present embodiment provides a method for jointly processing laterite nickel ore and nickel-iron alloy and recovering nickel and iron, the method comprising the following steps:

[0056] (1) adding water to the laterite nickel ore at a liquid-solid mass ratio of 4:1 to prepare a slurry, and then adding sulfuric acid with a concentration of 90 wt % to carry out acid leaching for 4 h at a pressure of 1 bar and a temperature of 80° C., wherein the mass ratio of the sulfuric acid to the laterite nickel ore is 1.5:1, and a first leachate is obtained after solid-liquid separation;

[0057] (2) mixing the nickel-iron alloy and the first leachate obtained in step (1) at a solid-liquid ratio of 0.2 kg / L, reacting at 80° C. until the pH value of the solution is 1.5, and obtaining a second leachate after solid-liquid separation;

[0058] (3) mixing phosphoric acid, hydrogen peroxide, sodium hydroxide and the second leachate obtained in step (2), reacting at 80° C. for 2 h, and obtaining an iron phosphate product and a nickel-containing solution after solid-liquid separation, wherein the iron phosphate product is further washed and dried; the mixing amount of the phosphoric acid is based on the molar amount of Fe in the second leachate, and P / Fe is 1.05; the mixing amount of the hydrogen peroxide is based on the molar amount of Fe in the second leachate. 2+ All oxidized to Fe 3+ The mixing amount of the sodium hydroxide is based on the pH of the second leachate reaching 1.8;

[0059] (4) The nickel-containing solution obtained in step (3) is purified, decontaminated, concentrated and crystallized in sequence to obtain battery-grade nickel sulfate.

[0060] Example 2

[0061] The present embodiment provides a method for jointly processing laterite nickel ore and nickel-iron alloy and recovering nickel and iron, the method comprising the following steps:

[0062] (1) adding water to the laterite nickel ore at a liquid-solid mass ratio of 3:1 to prepare a slurry, and then adding sulfuric acid with a concentration of 70 wt % to carry out acid leaching for 6 hours at a pressure of 0.8 bar and a temperature of 60° C., wherein the mass ratio of the sulfuric acid to the laterite nickel ore is 2:1, and a first leachate is obtained after solid-liquid separation;

[0063] (2) mixing the nickel-iron alloy and the first leachate obtained in step (1) at a solid-liquid ratio of 0.05 kg / L, reacting at 60° C. until the pH value of the solution is 2.0, and obtaining a second leachate after solid-liquid separation;

[0064] (3) mixing sodium dihydrogen phosphate, sodium hypochlorite, sodium hydroxide and the second leachate obtained in step (2), reacting at 50° C. for 4 hours, and obtaining an iron phosphate product and a nickel-containing solution after solid-liquid separation, wherein the iron phosphate product is further washed and dried; the mixing amount of the sodium dihydrogen phosphate is based on the molar amount of Fe in the second leachate, and P / Fe is 1.0; the mixing amount of the sodium hypochlorite is based on the molar amount of Fe in the second leachate 2+ All oxidized to Fe 3+ The mixing amount of the sodium hydroxide is based on the pH of the second leachate reaching 1.5;

[0065] (4) The nickel-containing solution obtained in step (3) is purified, decontaminated, concentrated and crystallized in sequence to obtain battery-grade nickel sulfate.

[0066] Example 3

[0067] The present embodiment provides a method for jointly processing laterite nickel ore and nickel-iron alloy and recovering nickel and iron, the method comprising the following steps:

[0068] (1) adding water to the laterite nickel ore at a liquid-solid mass ratio of 5:1 to prepare a slurry, and then adding sulfuric acid with a concentration of 98 wt % to carry out acid leaching for 2 h at a pressure of 1.2 bar and a temperature of 100° C., wherein the mass ratio of the sulfuric acid to the laterite nickel ore is 1:1, and a first leachate is obtained after solid-liquid separation;

[0069] (2) mixing the nickel-iron alloy and the first leachate obtained in step (1) at a solid-liquid ratio of 0.5 kg / L, reacting at 100° C. until the pH value of the solution is 1.0, and obtaining a second leachate after solid-liquid separation;

[0070] (3) mixing disodium hydrogen phosphate, sodium chlorate, sodium hydroxide and the second leachate obtained in step (2), reacting at 100° C. for 0.5 h, and obtaining an iron phosphate product and a nickel-containing solution after solid-liquid separation, wherein the iron phosphate product is further washed and dried; the mixing amount of the disodium hydrogen phosphate is based on the molar amount of Fe in the second leachate, and P / Fe is 1.1; the mixing amount of the sodium chlorate is based on the molar amount of Fe in the second leachate. 2+ All oxidized to Fe 3+ The mixing amount of the sodium hydroxide is based on the pH of the second leachate reaching 2.0;

[0071] (4) The nickel-containing solution obtained in step (3) is purified, decontaminated, concentrated and crystallized in sequence to obtain battery-grade nickel sulfate.

[0072] Example 4

[0073] This embodiment provides a method for jointly treating laterite nickel ore and nickel-iron alloy and recovering nickel and iron. In the method, except that the temperature of the acid leaching treatment in step (1) is changed to 50° C., the remaining steps and conditions are the same as those in Example 1, and therefore are not described in detail here.

[0074] Compared with Example 1, since the temperature of the acid leaching treatment in this embodiment is too low, the nickel and iron in the laterite nickel ore cannot be fully leached, resulting in the final output of the iron phosphate product and battery-grade nickel sulfate being significantly lower than that in Example 1.

[0075] Example 5

[0076] The present embodiment provides a method for jointly treating laterite nickel ore and nickel-iron alloy and recovering nickel and iron. In the method, except that the mass ratio of sulfuric acid to laterite nickel ore in step (1) is changed to 0.8:1, the remaining steps and conditions are the same as those in Example 1, and thus are not described in detail here.

[0077] Compared with Example 1, since the amount of sulfuric acid used in the acid leaching treatment in this example is too little, the nickel and iron in the laterite nickel ore cannot be fully leached, resulting in the final output of the iron phosphate product and battery-grade nickel sulfate being significantly lower than that in Example 1.

[0078] Example 6

[0079] The present embodiment provides a method for jointly treating laterite nickel ore and nickel-iron alloy and recovering nickel and iron. In the method, except that the mass ratio of sulfuric acid to laterite nickel ore in step (1) is changed to 2.2:1, the remaining steps and conditions are the same as those in Example 1, and thus are not described in detail here.

[0080] Compared with Example 1, due to the excessive amount of sulfuric acid used in the acid leaching treatment in this embodiment, the output of the final iron phosphate product and battery-grade nickel sulfate was not significantly improved, resulting in an unnecessary increase in the recovery cost, and the economic benefit was not as good as that of Example 1.

[0081] Example 7

[0082] This embodiment provides a method for jointly treating laterite nickel ore and nickel-iron alloy and recovering nickel and iron. Except for changing the reaction temperature in step (2) to 50° C., the remaining steps and conditions are the same as those in Example 1, so they are not described in detail here.

[0083] Compared with Example 1, since the reaction temperature of the nickel-iron alloy and the first leachate in this embodiment is too low and the reaction rate is slow, the nickel and iron in the nickel-iron alloy cannot be fully dissolved, resulting in the final output of the iron phosphate product and battery-grade nickel sulfate being significantly lower than that in Example 1.

[0084] Example 8

[0085] This embodiment provides a method for jointly treating laterite nickel ore and nickel-iron alloy and recovering nickel and iron. Except for changing the reaction temperature in step (3) to 40° C., the remaining steps and conditions are the same as those in Example 1, so they are not described here.

[0086] Compared with Example 1, since the reaction temperature of the phosphorus source, oxidant, precipitant and second leachate in this embodiment is too low, the iron element in the leachate cannot be fully precipitated to form iron phosphate precipitate, resulting in the final yield and quality of the iron phosphate product being significantly lower than that in Example 1.

[0087] Comparative Example 1

[0088] This comparative example provides a method for treating laterite nickel ore to recover nickel and iron, the method comprising the following steps:

[0089] (1) adding water to the laterite nickel ore at a liquid-solid mass ratio of 4:1 to prepare a slurry, and then adding sulfuric acid with a concentration of 90 wt % to carry out acid leaching for 4 h at a pressure of 1 bar and a temperature of 80° C., wherein the mass ratio of the sulfuric acid to the laterite nickel ore is 1.5:1, and obtaining a leachate after solid-liquid separation;

[0090] (2) mixing phosphoric acid, hydrogen peroxide, sodium hydroxide and the leachate obtained in step (1), reacting at 80° C. for 2 h, and obtaining an iron phosphate product and a nickel-containing solution after solid-liquid separation, wherein the iron phosphate product is further washed and dried; the mixing amount of the phosphoric acid is based on the molar amount of Fe in the leachate, and P / Fe is 1.05; the mixing amount of the hydrogen peroxide is based on the molar amount of Fe in the leachate 2+ All oxidized to Fe 3+ The mixing amount of the sodium hydroxide is based on the pH of the leachate reaching 1.8;

[0091] (3) The nickel-containing solution obtained in step (2) is purified, concentrated and crystallized in sequence to obtain battery-grade nickel sulfate.

[0092] Compared with Example 1, this comparative example can only process laterite nickel ore to recover nickel and iron, and the amount of auxiliary materials consumed in the subsequent process to neutralize the residual acid is huge, and the cost is high; at the same time, the recovery and treatment of nickel-iron alloy cannot be achieved, and the application scenario is single.

[0093] Comparative Example 2

[0094] This comparative example provides a method for treating nickel-iron alloy to recover nickel and iron, the method comprising the following steps:

[0095] (1) mixing a nickel-iron alloy and sulfuric acid with a concentration of 20 wt % at a solid-liquid ratio of 0.2 kg / L, reacting at 80° C. until the pH value of the solution is 1.5, and obtaining a leachate after solid-liquid separation;

[0096] (2) mixing phosphoric acid, hydrogen peroxide, sodium hydroxide and the leachate obtained in step (1), reacting at 80° C. for 2 h, and obtaining an iron phosphate product and a nickel-containing solution after solid-liquid separation, wherein the iron phosphate product is further washed and dried; the mixing amount of the phosphoric acid is based on the molar amount of Fe in the leachate, and P / Fe is 1.05; the mixing amount of the hydrogen peroxide is based on the molar amount of Fe in the leachate 2+ All oxidized to Fe 3+ The mixing amount of the sodium hydroxide is based on the pH of the leachate reaching 1.8;

[0097] (3) The nickel-containing solution obtained in step (2) is purified, concentrated and crystallized in sequence to obtain battery-grade nickel sulfate.

[0098] Compared with Example 1, this comparative example can only process nickel-iron alloy to recover nickel and iron, and the nickel-iron alloy dissolves slowly, and the processing efficiency is low; at the same time, it cannot realize the element extraction of laterite nickel ore, and the application scenario is single.

[0099] It can be seen that the method provided by the present invention fully considers the reaction characteristics of laterite nickel ore and nickel-iron alloy, and utilizes the high acid and Fe-rich laterite nickel ore leachate to obtain the nickel-iron alloy. 3+ The nickel-iron alloy is treated by using the nickel-iron alloy to neutralize the residual acid in the leachate and to utilize the residual acid and Fe in the leachate. 3+ The strong oxidizing property of nickel promotes the dissolution of nickel-iron alloy, thereby achieving efficient recovery of nickel and iron in nickel-iron alloy, and finally obtaining iron phosphate and battery-grade nickel sulfate products.

[0100] In addition, compared with the traditional separate processing of two raw materials, the combined processing method provided by the present invention greatly saves processing costs and improves processing efficiency. The recovered products, iron phosphate and nickel sulfate, can be used as raw materials for synthesizing battery materials, and the economic benefits are significantly improved.

[0101] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for jointly treating laterite nickel ore and nickel-iron alloy and recovering nickel and iron, characterized in that: The method comprises the following steps: (1) slurrying the laterite nickel ore and performing acid leaching treatment, and obtaining a first leachate after solid-liquid separation; The acid solution used in the acid leaching treatment in step (1) comprises sulfuric acid; the mass ratio of the sulfuric acid to the laterite nickel ore is (1-2):1; (2) mixing the nickel-iron alloy and the first leachate obtained in step (1) to react, and obtaining a second leachate after solid-liquid separation; (3) mixing a phosphorus source, an oxidant, sodium hydroxide and the second leaching solution obtained in step (2) to react, and obtaining an iron phosphate product and a nickel-containing solution after solid-liquid separation; The mixing amount of the sodium hydroxide is based on the pH of the second leachate reaching 1.5-2.0; (4) The nickel-containing solution obtained in step (3) is sequentially subjected to impurity removal, concentration and crystallization to obtain battery-grade nickel sulfate.

2. The method according to claim 1, characterized in that The liquid-to-solid mass ratio of the slurry preparation in step (1) is (3-5):

1.

3. The method according to claim 1, characterized in that The pressure of the acid leaching treatment in step (1) is 0.8-1.2 bar.

4. The method according to claim 1, characterized in that: The temperature of the acid leaching treatment in step (1) is 60-100°C.

5. The method according to claim 1, characterized in that: The acid leaching treatment time in step (1) is 2-6 hours.

6. The method according to claim 1, characterized in that The concentration of the sulfuric acid is 70-98 wt %.

7. The method according to claim 1, characterized in that The mixed solid-liquid ratio of the nickel-iron alloy and the first leaching solution in step (2) is (0.05-0.5) kg / L.

8. The method according to claim 1, characterized in that The reaction temperature in step (2) is 60-100°C.

9. The method according to claim 1, characterized in that: The endpoint determination index of the reaction in step (2) is the pH value, and the pH at the reaction endpoint is 1.0-2.

0.

10. The method according to claim 1, characterized in that The phosphorus source in step (3) includes any one of phosphoric acid, sodium dihydrogen phosphate or disodium hydrogen phosphate, or a combination of at least two thereof.

11. The method according to claim 1, characterized in that: The mixing amount of the phosphorus source in step (3) is based on the molar amount of Fe in the second leaching solution, and P / Fe is 1.0-1.

1.

12. The method according to claim 1, characterized in that The oxidant in step (3) includes any one of hydrogen peroxide, sodium hypochlorite, sodium chlorate or compressed air, or a combination of at least two of them.

13. The method according to claim 1, characterized in that The mixing amount of the oxidant in step (3) is based on the Fe content in the second leaching solution. 2+ All oxidized to Fe 3+ shall prevail.

14. The method according to claim 1, characterized in that The reaction temperature in step (3) is 50-100°C.

15. The method according to claim 1, characterized in that The reaction time of step (3) is 0.5-4h.

16. The method according to claim 1, characterized in that The ferric phosphate product obtained after the solid-liquid separation in step (3) is further washed and dried.

17. The method according to claim 1, characterized in that The impurity removal in step (4) includes chemical precipitation or extraction.

18. The method according to claim 1, characterized in that The method comprises the following steps: (1) adding water to the laterite nickel ore at a liquid-solid mass ratio of (3-5):1 to prepare a slurry, and then adding sulfuric acid with a concentration of 70-98wt% at a pressure of 0.8-1.2 bar and a temperature of 60-100°C to carry out acid leaching for 2-6 hours, wherein the mass ratio of the sulfuric acid to the laterite nickel ore is (1-2):1, and obtaining a first leachate after solid-liquid separation; (2) mixing the nickel-iron alloy and the first leachate obtained in step (1) at a solid-liquid ratio of (0.05-0.5) kg / L, reacting at 60-100° C. until the pH value of the solution is 1.0-2.0, and obtaining a second leachate after solid-liquid separation; (3) mixing a phosphorus source, an oxidant, sodium hydroxide and the second leachate obtained in step (2), reacting at 50-100° C. for 0.5-4 h, and obtaining an iron phosphate product and a nickel-containing solution after solid-liquid separation, wherein the iron phosphate product is further washed and dried; the phosphorus source comprises any one of phosphoric acid, sodium dihydrogen phosphate or disodium hydrogen phosphate, or a combination of at least two thereof, and the mixing amount of the phosphorus source is based on the molar amount of Fe in the second leachate, and P / Fe is 1.0-1.1; the oxidant comprises any one of hydrogen peroxide, sodium hypochlorite, sodium chlorate or compressed air, or a combination of at least two thereof, and the mixing amount of the oxidant is based on the molar amount of Fe in the second leachate. 2+ All oxidized to Fe 3+ The mixing amount of the sodium hydroxide is based on the pH of the second leachate reaching 1.5-2.0; (4) The nickel-containing solution obtained in step (3) is subjected to impurity removal, concentration and crystallization in sequence to obtain battery-grade nickel sulfate; the impurity removal includes chemical precipitation or extraction.