A method of smelting a nickel-iron alloy

Abstract

This invention relates to a method for smelting nickel-iron alloys, comprising the following steps: the nickel-iron alloy is subjected to oxidative acid leaching to obtain a leaching solution and leaching residue; the obtained leaching solution is subjected to chromium removal to obtain chromium-removed residue and chromium-removed filtrate; a first oxidant, phosphoric acid, and the obtained chromium-removed filtrate are mixed to remove iron to obtain ferric phosphate and an iron-removing solution; a trivalent iron salt is mixed with the obtained iron-removing solution to remove phosphorus to obtain a phosphorus-removing solution and ferric phosphate residue; the obtained phosphorus-removing solution is subjected to impurity removal, and the obtained impurity-removed solution is used to prepare a ternary precursor. The method provided by this invention eliminates the need for extraction, reducing the processing cost of nickel-iron alloys, and also enables the iron in the nickel-iron alloy to be made into battery-grade ferric phosphate, while the nickel can be used to prepare precursors, resulting in high overall benefits.

Description

Technical Field

[0001] This invention belongs to the field of valuable metal recycling technology, and relates to a method for alloy smelting, particularly a method for smelting nickel-iron alloys. Background Technology

[0002] Nickel is a key material for new energy power batteries and is crucial for the development of new energy vehicles. According to statistics, global nickel production in 2023 was approximately 3.6 million tons. Global nickel resources exceed 350 million tons, of which 54% are laterite nickel ore, 35% are magmatic sulfide ore, 10% are massive sulfide ore, and 1% are tailings.

[0003] Nickel-iron alloy is an intermediate product in the smelting of nickel sulfide ore. Due to its high iron content and low iron value, nickel-iron alloy requires further smelting to enrich its nickel content into nickel briquettes or powder with a nickel content of over 90%. However, the process of converting nickel-iron alloy into nickel briquettes or powder is energy-intensive, and the resulting iron is disposed of as waste and landfilled, hindering the effective utilization of iron in nickel-iron alloys. With the increasing demand for lithium iron phosphate batteries, the demand for iron resources is also gradually increasing. Therefore, it is necessary to develop a resource utilization method for nickel-iron alloys to achieve the comprehensive utilization of both nickel and iron resources. Summary of the Invention

[0004] The purpose of this invention is to provide a method for smelting nickel-iron alloys. This method can achieve deep impurity removal without extraction, and can not only turn the iron in the nickel-iron alloy into battery-grade iron phosphate, but also turn the nickel into a precursor, resulting in high overall benefits.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] This invention provides a method for smelting nickel-iron alloys, the method comprising the following steps:

[0007] (1) Nickel-iron alloy is subjected to oxidative acid leaching to obtain leaching solution and leaching residue;

[0008] (2) The leachate obtained in step (1) is subjected to chromium removal to obtain chromium removal slag and chromium removal filtrate;

[0009] (3) Mix the first oxidant, phosphoric acid and the chromium removal filtrate obtained in step (2) to remove iron, and obtain iron phosphate and iron removal solution;

[0010] (4) The ferric salt is mixed with the iron removal liquid obtained in step (3) to remove phosphorus, resulting in a phosphorus removal solution and ferric phosphate residue;

[0011] (5) The phosphorus removal solution obtained in step (4) is used to remove impurities, and the resulting impurity-removed solution is used to prepare the precursor.

[0012] The method provided by this invention can achieve deep impurity removal without extraction, with low processing cost. It can turn iron in nickel-iron alloys into battery-grade iron phosphate and nickel into precursors, thus achieving high overall benefits.

[0013] Preferably, the oxidative acid leaching in step (1) includes: first, mixing the nickel-iron alloy with acid for acid leaching, and then adding hydrogen peroxide to a pH value of 1 to 2, for example, 1, 1.2, 1.5, 1.8 or 2, but not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1.5 to 2.

[0014] Preferably, the concentration of hydrogen peroxide used in the oxidative acid leaching process is 27.5 wt% to 50 wt%, for example, it can be 27.5 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt% or 50 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0015] Preferably, the acid includes any one or a combination of at least two of sulfuric acid, hydrochloric acid, or nitric acid. Typical but non-limiting combinations include combinations of sulfuric acid and hydrochloric acid, hydrochloric acid and nitric acid, sulfuric acid and nitric acid, or combinations of sulfuric acid, hydrochloric acid, and nitric acid, with sulfuric acid being the most preferred.

[0016] The concentration of sulfuric acid described in this invention is 70 wt% or higher, for example, it can be 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, or 98 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] Preferably, the amount of acid used is at least 0.8 times the theoretical amount, for example, 0.8 times, 0.85 times, 0.9 times, 0.95 times, or 1 times, but not limited to the listed values; other unlisted values ​​within the range are also applicable. If less acid is used in the oxidative acid leaching process, the Ni and Fe content in the leachate will be low, affecting the quality of subsequent products.

[0018] Preferably, the acid leaching temperature is 70°C to 90°C, for example, 70°C, 75°C, 80°C, 85°C or 90°C, but not limited to the listed values. Other unlisted values ​​within the range are also applicable, with 80°C to 90°C being the preferred temperature.

[0019] Preferably, the acid leaching time is 2.5h to 5h, for example, it can be 2.5h, 3h, 3.5h, 4h, 4.5h or 5h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, with 2.5h to 4h being the preferred time.

[0020] Preferably, the chromium removal in step (2) includes: first, mixing the second oxidant with the leachate obtained in step (1), then adding phosphate to carry out the chromium removal reaction, and after standing, performing solid-liquid separation to obtain chromium-removed slag and chromium-removed filtrate.

[0021] The method provided by this invention addresses the difficulty in removing chromium from acid leaching solutions. It utilizes the ionization of phosphate into phosphate and hydroxide ions in the solution and controls the conditions of the chromium removal reaction to allow the phosphate and hydroxide ions to combine with iron ions in the acid leaching solution to form amorphous ferric phosphate and ferric hydroxide. The amorphous ferric phosphate can induce the formation of chromium phosphate, and the ferric hydroxide can adsorb some of the chromium ions. By combining induction and adsorption, the method achieves the goal of deep chromium removal.

[0022] For example, the phosphate is prepared into a solution with a concentration of 10 wt% to 30 wt% before being added, for example, it can be 10 wt%, 15 wt%, 20 wt%, 25 wt% or 30 wt%, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0023] Preferably, the second oxidant includes any one or a combination of at least two of hydrogen peroxide, sodium persulfate, or manganese dioxide. Typical but non-limiting combinations include a combination of hydrogen peroxide and sodium persulfate, a combination of sodium persulfate and manganese dioxide, a combination of hydrogen peroxide and manganese dioxide, or a combination of hydrogen peroxide, sodium persulfate, and manganese dioxide.

[0024] Preferably, the amount of the second oxidant added is such that the content of ferric ions in the system is 0.5 g / L to 2 g / L, for example, it can be 0.5 g / L, 1 g / L, 1.5 g / L or 2 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, the phosphate includes any one or a combination of at least two of trisodium phosphate (Na3PO4), sodium dihydrogen phosphate (NaH2PO4), or sodium monohydrogen phosphate (Na2HPO4). Typical but non-limiting combinations include combinations of trisodium phosphate and sodium dihydrogen phosphate, combinations of sodium dihydrogen phosphate and sodium monohydrogen phosphate, combinations of trisodium phosphate and sodium monohydrogen phosphate, or combinations of trisodium phosphate, sodium dihydrogen phosphate, and sodium monohydrogen phosphate.

[0026] Preferably, the amount of phosphate added is 1.1 to 3 times the theoretical amount of chromium required for the reaction in the system, for example, it can be 1.1 times, 1.5 times, 2 times, 2.5 times or 3 times, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1.8 to 2.5 times.

[0027] Preferably, the temperature of the chromium removal reaction is 25°C to 50°C, for example, 25°C, 30°C, 35°C, 40°C, 45°C or 50°C, but not limited to the listed values. Other unlisted values ​​within the range are also applicable, with 40°C to 50°C being the preferred temperature.

[0028] Preferably, the pH value of the chromium removal reaction is 3 to 5, for example, it can be 3, 3.5, 4, 4.5 or 5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 3.5 to 4.

[0029] For example, the pH value of the chromium removal reaction described in this invention is adjusted by adding nickel hydroxide and / or nickel carbonate.

[0030] Preferably, the chromium removal reaction time is 1 to 3 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours, but not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1.5 hours to 2 hours.

[0031] Preferably, the settling time is 5h to 12h, for example, it can be 5h, 6h, 8h, 10h or 12h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 6h to 10h.

[0032] Preferably, in step (3), the first oxidant includes any one or a combination of at least two of hydrogen peroxide, oxygen, ozone, or sodium persulfate. Typical but non-limiting combinations include a combination of hydrogen peroxide and oxygen, a combination of oxygen and ozone, a combination of ozone and sodium persulfate, a combination of hydrogen peroxide, oxygen, and ozone, a combination of oxygen, ozone, and sodium persulfate, or a combination of hydrogen peroxide, ozone, oxygen, and sodium persulfate, preferably hydrogen peroxide.

[0033] Preferably, the concentration of the first oxidant is from 27.5 wt% to 50 wt%, for example, it can be 27.5 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt% or 50 wt%, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0034] Preferably, the amount of the first oxidant added is 1 to 1.5 times the theoretical amount of ferrous ions in the system, for example, it can be 1, 1.2, 1.3, 1.4 or 1.5 times, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1.2 to 1.5 times.

[0035] Preferably, the amount of phosphoric acid added is 1 to 1.2 times the theoretical amount of iron required for the reaction in the system, for example, it can be 1, 1.1 or 1.2 times, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1.1 to 1.2 times.

[0036] Preferably, the iron removal in step (3) is carried out under conditions of pH 1 to 2, for example, 1, 1.2, 1.5, 1.8 or 2, but not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1.5 to 2.

[0037] For example, the pH value for iron removal in step (3) of the present invention is adjusted using a sodium hydroxide solution with a concentration of 20wt% to 50wt%, for example, it can be 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, or 50wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] Preferably, the iron removal temperature in step (3) is 80°C to 95°C, for example, it can be 80°C, 82°C, 85°C, 90°C or 95°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] Preferably, the trivalent iron salt in step (4) includes ferric sulfate.

[0040] Preferably, the amount of ferric salt added in step (4) is 1 to 2 times the theoretical amount required for the reaction with phosphorus, for example, it can be 1, 1.2, 1.5, 1.8 or 2 times, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] Preferably, the impurity removal in step (5) includes: first concentrating the phosphorus removal solution, then mixing it with silicate and alkaline solution, reacting and then allowing it to stand, and separating the solid and liquid to obtain impurity removal residue and impurity removal solution.

[0042] The phosphorus removal solution contains silicon, zinc, and iron. By adding silicates as an inducer, the silicates are ionized in the solution into silicic acid and hydroxide ions. The silicic acid can induce the silicic acid ions in the solution to become silicic acid, while the hydroxide ions combine with iron and nickel to form ferric hydroxide and nickel hydroxide. Ferric hydroxide and nickel hydroxide can adsorb silicon. By combining induction and adsorption, the purpose of deep silicon removal is achieved.

[0043] Preferably, the concentration is such that the Ni concentration in the solution is 100 g / L to 120 g / L, for example, 100 g / L, 105 g / L, 110 g / L, 115 g / L or 120 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 110 g / L to 120 g / L.

[0044] Preferably, the amount of silicate added is from 0.1 g / L to 1.5 g / L, for example, it can be 0.1 g / L, 0.3 g / L, 0.5 g / L, 0.8 g / L, 1 g / L or 1.5 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] Preferably, the amount of alkali added is sufficient to react with nickel in the system to generate nickel hydroxide at a concentration of 3 g / L to 10 g / L, for example, 3 g / L, 5 g / L, 6 g / L, 8 g / L or 10 g / L, but not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 5 g / L to 8 g / L.

[0046] For example, the alkaline solution comprises a sodium hydroxide solution with a concentration of 20 wt% to 32 wt%, such as 20 wt%, 24 wt%, 25 wt%, 28 wt%, 30 wt%, or 32 wt%, but not limited to the listed values; other unlisted values ​​within the range are also applicable.

[0047] Preferably, the reaction temperature is between 50°C and 80°C, for example, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0048] Preferably, the reaction time is 1 hour to 3 hours, for example, it can be 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1 hour to 2 hours.

[0049] Preferably, the settling time is 12h to 24h, for example, it can be 12h, 15h, 16h, 18h, 20h or 24h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0050] As a preferred embodiment of the method for smelting nickel-iron alloys provided by the present invention, the method includes the following steps:

[0051] (1) Nickel-iron alloy is mixed with sulfuric acid and acid-leached at 70°C to 90°C for 2.5 to 5 hours. Then hydrogen peroxide is added until the pH value is 1 to 2. Solid-liquid separation is performed to obtain leachate and leachate residue.

[0052] The amount of sulfuric acid used is more than 0.8 times the theoretical amount required for acid leaching;

[0053] (2) First, mix the second oxidant with the leachate obtained in step (1), then add phosphate, and carry out the chromium removal reaction for 1 to 3 hours at 25°C to 50°C and pH 3 to 5. After standing for 5 to 12 hours, perform solid-liquid separation to obtain chromium removal slag and chromium removal filtrate.

[0054] The second oxidant includes any one or a combination of at least two of hydrogen peroxide, sodium persulfate, or manganese dioxide, and the amount of the second oxidant added is such that the content of ferric ions in the system is 0.5 g / L to 2 g / L.

[0055] The phosphate includes any one or a combination of at least two of trisodium phosphate, sodium dihydrogen phosphate, or sodium monohydrogen phosphate, and the amount of phosphate added is 1.1 to 3 times the theoretical amount of chromium required for the reaction in the system.

[0056] (3) Mix the first oxidant, phosphoric acid and the chromium removal filtrate obtained in step (2), adjust the pH to 1 to 2 with 20 wt% to 50 wt% sodium hydroxide, and remove iron at 80°C to 95°C to obtain ferric phosphate and iron removal solution.

[0057] The amount of the first oxidant added is 1 to 1.5 times the theoretical amount required for the reaction of ferrous ions in the system; the amount of phosphoric acid added is 1 to 1.2 times the theoretical amount required for the reaction of iron in the system.

[0058] (4) The ferric salt is mixed with the iron removal liquid obtained in step (3) to remove phosphorus, resulting in a phosphorus removal solution and ferric phosphate residue;

[0059] The amount of the trivalent iron salt added is 1 to 2 times the theoretical amount required for the reaction with phosphorus;

[0060] (5) The phosphorus removal solution is first concentrated to a Ni concentration of 100 g / L to 120 g / L, then mixed with silicate and alkaline solution, reacted at 50°C to 80°C for 1 h to 3 h, and allowed to stand for 12 h to 24 h. Solid-liquid separation is performed to obtain impurity residue and impurity removal solution; the obtained impurity removal solution is used to prepare precursors.

[0061] The amount of silicate added is from 0.1 g / L to 1.5 g / L; the amount of alkali added is sufficient to react with nickel in the system to generate nickel hydroxide at a concentration of 3 g / L to 10 g / L.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] The method provided by this invention can achieve deep impurity removal without extraction, with low processing cost. It can turn iron in nickel-iron alloys into battery-grade iron phosphate and nickel into precursors, thus achieving high overall benefits. Attached Figure Description

[0064] Figure 1 A process flow diagram of the method is provided for Example 1. Detailed Implementation

[0065] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0066] Example 1

[0067] This embodiment provides a method for smelting nickel-iron alloy. The main components of the nickel-iron alloy, by mass percentage, include 25.6 wt% Ni, 0.25 wt% Co, 0.12 wt% Mn, 72.5 wt% Fe, 0.09 wt% Cr, 0.23 wt% Si, 0.012 wt% Zn, 0.002 wt% Ca, and 0.001 wt% Mg. The process flow diagram is shown below. Figure 1 As shown, it includes the following steps:

[0068] (1) Nickel-iron alloy with an average particle size of 5 mm was mixed with water at a solid-liquid ratio of 1:5 (g / mL) to make a slurry. After stirring, it was mixed with sulfuric acid with a concentration of 98 wt% and acid-leached at 80℃ for 4 h. Then, hydrogen peroxide with a concentration of 27.5 wt% was added until the pH value was 1.5. Solid-liquid separation was performed to obtain leachate and leachate residue.

[0069] The amount of sulfuric acid used is 0.8 times the theoretical amount required for acid leaching;

[0070] (2) First, mix the second oxidant with the leachate obtained in step (1) for 0.5 h, then add trisodium phosphate, and carry out the chromium removal reaction for 2 h at 40 °C and pH 3.5 (adjusted with nickel hydroxide). After standing for 6 h, perform solid-liquid separation to obtain chromium removal slag and chromium removal filtrate.

[0071] The second oxidant is hydrogen peroxide with a concentration of 27.5 wt%, and the amount of the second oxidant added is such that the content of ferric ions in the system is 0.5 g / L;

[0072] Trisodium phosphate was added in the form of a 20 wt% solution, and the amount added was 1.8 times the theoretical amount of chromium required for the reaction in the system.

[0073] (3) Mix the first oxidant, phosphoric acid and the chromium removal filtrate obtained in step (2), control the pH value to 2 with 32wt% sodium hydroxide, and remove iron at 95℃ for 4h to obtain ferric phosphate and iron removal solution.

[0074] The first oxidant is hydrogen peroxide with a concentration of 27.5 wt%, and the amount of the first oxidant added is 1.2 times the theoretical amount required to react with ferrous ions in the system; the amount of phosphoric acid added is 1.1 times the theoretical amount required to react with iron in the system.

[0075] (4) Ferric sulfate is mixed with the iron removal solution obtained in step (3) to remove phosphorus, resulting in a phosphorus removal solution and ferric phosphate residue;

[0076] The amount of ferric sulfate added is 1.2 times the theoretical amount needed for its reaction with phosphorus;

[0077] (5) The phosphorus removal solution is first concentrated to a Ni concentration of 120 g / L. After stirring, it is mixed with sodium silicate and a 32 wt% sodium hydroxide solution. The mixture is reacted at 70°C for 1 h and then allowed to stand for 12 h. Solid-liquid separation is performed to obtain the impurity removal residue and the impurity removal solution.

[0078] The amount of sodium silicate added is 0.2 g / L; the amount of sodium hydroxide solution added is sufficient to react with nickel in the system to generate 5 g / L of nickel hydroxide.

[0079] Cobalt sulfate and manganese sulfate were added to the obtained purified solution for preparation, and a ternary precursor was obtained through co-precipitation reaction.

[0080] In this embodiment, the composition of the leachate, chromium removal filtrate, concentrate, and impurity removal solution is shown in Table 1.

[0081] Table 1

[0082]

[0083] Example 2

[0084] This embodiment provides a method for smelting a nickel-iron alloy. The main components of the nickel-iron alloy, by mass percentage, include 32.1 wt% Ni, 0.32 wt% Co, 0.15 wt% Mn, 65.6 wt% Fe, 0.07 wt% Cr, 0.18 wt% Si, 0.02 wt% Zn, 0.002 wt% Ca, and 0.001 wt% Mg. The method includes the following steps:

[0085] (1) Nickel-iron alloy with an average particle size of 5 mm was mixed with water at a solid-liquid ratio of 1:2 (g / mL) to make a slurry. After stirring, it was mixed with sulfuric acid with a concentration of 98 wt% and acid-leached at 85℃ for 3 hours. Then, hydrogen peroxide with a concentration of 27.5 wt% was added until the pH value was 2. The solid and liquid were separated to obtain leachate and leach residue.

[0086] The amount of sulfuric acid used is 0.9 times the theoretical amount required for acid leaching;

[0087] (2) First, mix the second oxidant with the leachate obtained in step (1) for 0.5 h, then add sodium dihydrogen phosphate, and carry out the chromium removal reaction for 1.5 h at 50 °C and pH 4 (adjusted with nickel hydroxide). After standing for 10 h, perform solid-liquid separation to obtain chromium removal slag and chromium removal filtrate.

[0088] The second oxidant is hydrogen peroxide with a concentration of 27.5 wt%, and the amount of the second oxidant added is such that the content of ferric ions in the system is 1 g / L.

[0089] Sodium dihydrogen phosphate was added in the form of a 20 wt% solution, and the amount added was 2.5 times the theoretical amount of chromium required for the reaction in the system.

[0090] (3) Mix the first oxidant, phosphoric acid and the chromium removal filtrate obtained in step (2), control the pH value to 1.5 with 32wt% sodium hydroxide, and remove iron at 95℃ for 3h to obtain ferric phosphate and iron removal solution;

[0091] The first oxidant is hydrogen peroxide with a concentration of 27.5 wt%, and the amount of the first oxidant added is 1.5 times the theoretical amount required to react with ferrous ions in the system; the amount of phosphoric acid added is 1.2 times the theoretical amount required to react with iron in the system.

[0092] (4) Ferric sulfate is mixed with the iron removal solution obtained in step (3) to remove phosphorus, resulting in a phosphorus removal solution and ferric phosphate residue;

[0093] The amount of ferric sulfate added is 1.1 times the theoretical amount needed for the reaction with phosphorus;

[0094] (5) The phosphorus removal solution is first concentrated to a Ni concentration of 110 g / L. After stirring, it is mixed with sodium silicate and a 32 wt% sodium hydroxide solution. The mixture is reacted at 70°C for 2 h and then allowed to stand for 24 h. Solid-liquid separation is performed to obtain the impurity removal residue and the impurity removal solution.

[0095] The amount of sodium silicate added is 1 g / L; the amount of sodium hydroxide solution added is sufficient to react with nickel in the system to generate 8 g / L of nickel hydroxide.

[0096] Cobalt sulfate and manganese sulfate were added to the obtained purified solution for preparation, and a ternary precursor was obtained through co-precipitation reaction.

[0097] In this embodiment, the composition of the leachate, chromium removal filtrate, concentrate, and impurity removal solution is shown in Table 2.

[0098] Table 2

[0099]

[0100] Example 3

[0101] This embodiment provides a method for smelting a nickel-iron alloy. The main components of the nickel-iron alloy, by mass percentage, include 30.1 wt% Ni, 0.45 wt% Co, 0.21 wt% Mn, 68.3 wt% Fe, 0.06 wt% Cr, 0.27 wt% Si, 0.018 wt% Zn, 0.002 wt% Ca, and 0.001 wt% Mg. The method includes the following steps:

[0102] (1) Nickel-iron alloy with an average particle size of 5 mm was mixed with water at a solid-liquid ratio of 1:3 (g / mL) to make a slurry. After stirring, it was mixed with sulfuric acid with a concentration of 98 wt% and acid-leached at 90℃ for 2.5 h. Then, hydrogen peroxide with a concentration of 27.5 wt% was added until the pH value was 2. The solid and liquid were separated to obtain leachate and leach residue.

[0103] The amount of sulfuric acid used is 0.8 times the theoretical amount required for acid leaching;

[0104] (2) First, mix the second oxidant with the leachate obtained in step (1) for 1 hour, then add trisodium phosphate, and carry out the chromium removal reaction for 2 hours at 45°C and pH 4 (adjusted with nickel carbonate). After standing for 10 hours, perform solid-liquid separation to obtain chromium removal slag and chromium removal filtrate.

[0105] The second oxidant is manganese dioxide, and the amount of the second oxidant added is such that the content of ferric ions in the system is 2 g / L;

[0106] Trisodium phosphate was added in the form of a 20 wt% solution, and the amount added was twice the theoretical amount of chromium required for the reaction in the system.

[0107] (3) Mix the first oxidant, phosphoric acid and the chromium removal filtrate obtained in step (2), control the pH value to 2 with 32wt% sodium hydroxide, and remove iron at 90℃ for 5h to obtain ferric phosphate and iron removal solution.

[0108] The first oxidant is hydrogen peroxide with a concentration of 27.5 wt%, and the amount of the first oxidant added is 1.5 times the theoretical amount required to react with ferrous ions in the system; the amount of phosphoric acid added is 1.1 times the theoretical amount required to react with iron in the system.

[0109] (4) Ferric sulfate is mixed with the iron removal solution obtained in step (3) to remove phosphorus, resulting in a phosphorus removal solution and ferric phosphate residue;

[0110] The amount of ferric sulfate added is 1.1 times the theoretical amount needed for the reaction with phosphorus;

[0111] (5) The phosphorus removal solution is first concentrated to a Ni concentration of 115 g / L. After stirring, it is mixed with sodium silicate and a 32 wt% sodium hydroxide solution. The mixture is reacted at 70°C for 2 h and then allowed to stand for 16 h. Solid-liquid separation is performed to obtain the impurity removal residue and the impurity removal solution.

[0112] The amount of sodium silicate added is 1.5 g / L; the amount of sodium hydroxide solution added is sufficient to react with nickel in the system to generate 6 g / L of nickel hydroxide.

[0113] Cobalt sulfate and manganese sulfate were added to the obtained purified solution for preparation, and a ternary precursor was obtained through co-precipitation reaction.

[0114] In this embodiment, the composition of the leachate, chromium removal filtrate, concentrate, and impurity removal solution is shown in Table 3.

[0115] Table 3

[0116]

[0117]

[0118] Example 4

[0119] This embodiment provides a method for smelting a nickel-iron alloy. The main components of the nickel-iron alloy, by mass percentage, include 25.6 wt% Ni, 0.25 wt% Co, 0.12 wt% Mn, 72.5 wt% Fe, 0.09 wt% Cr, 0.23 wt% Si, 0.012 wt% Zn, 0.002 wt% Ca, and 0.001 wt% Mg. The method includes the following steps:

[0120] (1) Nickel-iron alloy with an average particle size of 5 mm was mixed with water at a solid-liquid ratio of 1:5 (g / mL) to make a slurry. After stirring, it was mixed with sulfuric acid with a concentration of 98 wt% and acid-leached at 70℃ for 5 h. Then, hydrogen peroxide with a concentration of 27.5 wt% was added until the pH value was 1. Solid-liquid separation was performed to obtain leachate and leachate residue.

[0121] The amount of sulfuric acid used is 0.8 times the theoretical amount required for acid leaching;

[0122] (2) First, mix the second oxidant with the leachate obtained in step (1) for 0.5 h, then add trisodium phosphate, and carry out the chromium removal reaction for 1 h at 25 °C and pH 5 (adjusted with nickel hydroxide). After standing for 5 h, perform solid-liquid separation to obtain chromium removal slag and chromium removal filtrate.

[0123] The second oxidant is hydrogen peroxide with a concentration of 27.5 wt%, and the amount of the second oxidant added is such that the content of ferric ions in the system is 0.5 g / L;

[0124] Trisodium phosphate was added in the form of a 20 wt% solution, and the amount added was 1.1 times the theoretical amount of chromium required for the reaction in the system.

[0125] (3) Mix the first oxidant, phosphoric acid and the chromium removal filtrate obtained in step (2), control the pH value to 2 with 32wt% sodium hydroxide, and remove iron at 80℃ for 4h to obtain ferric phosphate and iron removal solution.

[0126] The first oxidant is hydrogen peroxide with a concentration of 27.5 wt%, and the amount of the first oxidant added is 1 times the theoretical amount required to react with ferrous ions in the system; the amount of phosphoric acid added is 1 times the theoretical amount required to react with iron in the system.

[0127] (4) Ferric sulfate is mixed with the iron removal solution obtained in step (3) to remove phosphorus, resulting in a phosphorus removal solution and ferric phosphate residue;

[0128] The amount of ferric sulfate added is 1.2 times the theoretical amount needed for its reaction with phosphorus;

[0129] (5) The phosphorus removal solution is first concentrated to a Ni concentration of 100 g / L. After stirring, it is mixed with sodium silicate and a 32 wt% sodium hydroxide solution. The mixture is reacted at 50°C for 3 h and then allowed to stand for 12 h. Solid-liquid separation is performed to obtain the impurity removal residue and the impurity removal solution.

[0130] The amount of sodium silicate added is 0.1 g / L; the amount of sodium hydroxide solution added is sufficient to react with nickel in the system to generate 3 g / L of nickel hydroxide.

[0131] Cobalt sulfate and manganese sulfate were added to the obtained purified solution for preparation, and a ternary precursor was obtained through co-precipitation reaction.

[0132] In this embodiment, the composition of the leachate, chromium removal filtrate, concentrate, and impurity removal solution is shown in Table 4.

[0133] Table 4

[0134]

[0135] Example 5

[0136] This embodiment provides a method for smelting a nickel-iron alloy. The main components of the nickel-iron alloy, by mass percentage, include 25.6 wt% Ni, 0.25 wt% Co, 0.12 wt% Mn, 72.5 wt% Fe, 0.09 wt% Cr, 0.23 wt% Si, 0.012 wt% Zn, 0.002 wt% Ca, and 0.001 wt% Mg. The method includes the following steps:

[0137] (1) Nickel-iron alloy with an average particle size of 5 mm was mixed with water at a solid-liquid ratio of 1:5 (g / mL) to make a slurry. After stirring, it was mixed with sulfuric acid with a concentration of 98 wt% and acid-leached at 80℃ for 4 h. Then, hydrogen peroxide with a concentration of 27.5 wt% was added until the pH value was 1.5. Solid-liquid separation was performed to obtain leachate and leachate residue.

[0138] The amount of sulfuric acid used is 0.8 times the theoretical amount required for acid leaching;

[0139] (2) First, mix the second oxidant with the leachate obtained in step (1) for 0.5 h, then add trisodium phosphate, and carry out the chromium removal reaction for 3 h at 40 °C and pH 3 (adjusted with nickel hydroxide). After standing for 12 h, perform solid-liquid separation to obtain chromium removal slag and chromium removal filtrate.

[0140] The second oxidant is hydrogen peroxide with a concentration of 27.5 wt%, and the amount of the second oxidant added is such that the content of ferric ions in the system is 0.5 g / L;

[0141] Trisodium phosphate was added in the form of a 20 wt% solution, and the amount added was three times the theoretical amount of chromium required for the reaction in the system.

[0142] (3) Mix the first oxidant, phosphoric acid and the chromium removal filtrate obtained in step (2), control the pH value to 2 with 32wt% sodium hydroxide, and remove iron at 95℃ for 4h to obtain ferric phosphate and iron removal solution.

[0143] The first oxidant is hydrogen peroxide with a concentration of 27.5 wt%, and the amount of the first oxidant added is 1.2 times the theoretical amount required to react with ferrous ions in the system; the amount of phosphoric acid added is 1.1 times the theoretical amount required to react with iron in the system.

[0144] (4) Ferric sulfate is mixed with the iron removal solution obtained in step (3) to remove phosphorus, resulting in a phosphorus removal solution and ferric phosphate residue;

[0145] The amount of ferric sulfate added is 1.2 times the theoretical amount needed for its reaction with phosphorus;

[0146] (5) The phosphorus removal solution is first concentrated to a Ni concentration of 120 g / L. After stirring, it is mixed with sodium silicate and a 32 wt% sodium hydroxide solution. The mixture is reacted at 80°C for 1 h and then allowed to stand for 12 h. Solid-liquid separation is performed to obtain the impurity removal residue and the impurity removal solution.

[0147] The amount of sodium silicate added is 0.2 g / L; the amount of sodium hydroxide solution added is sufficient to react with nickel in the system to generate 10 g / L of nickel hydroxide.

[0148] Cobalt sulfate and manganese sulfate were added to the obtained purified solution for preparation, and a ternary precursor was obtained through co-precipitation reaction.

[0149] In this embodiment, the composition of the leachate, chromium removal filtrate, concentrate, and impurity removal solution is shown in Table 5.

[0150] Table 5

[0151]

[0152] Example 6

[0153] This embodiment provides a method for smelting a nickel-iron alloy. The main components of the nickel-iron alloy, by mass percentage, include 25.6 wt% Ni, 0.25 wt% Co, 0.12 wt% Mn, 72.5 wt% Fe, 0.09 wt% Cr, 0.23 wt% Si, 0.012 wt% Zn, 0.002 wt% Ca, and 0.001 wt% Mg. The method includes the following steps:

[0154] (1) Nickel-iron alloy with an average particle size of 5 mm was mixed with water at a solid-liquid ratio of 1:5 (g / mL) to make a slurry. After stirring, it was mixed with sulfuric acid with a concentration of 98 wt% and acid-leached at 80℃ for 4 h. Then, hydrogen peroxide with a concentration of 27.5 wt% was added until the pH value was 1.5. Solid-liquid separation was performed to obtain leachate and leachate residue.

[0155] The amount of sulfuric acid used is 0.8 times the theoretical amount required for acid leaching;

[0156] (2) Mix the leachate obtained in step (1) with trisodium phosphate and carry out a chromium removal reaction at 40°C for 2 hours. After standing for 6 hours, perform solid-liquid separation to obtain chromium removal slag and chromium removal filtrate.

[0157] During the chromium removal reaction, a 32 wt% sodium hydroxide solution is introduced to maintain the pH value at 5;

[0158] Trisodium phosphate was added in the form of a 20 wt% solution, and the amount added was 1.8 times the theoretical amount of chromium required for the reaction in the system.

[0159] (3) Mix the first oxidant, phosphoric acid and the chromium removal filtrate obtained in step (2), control the pH value to 2 with 32wt% sodium hydroxide, and remove iron at 95℃ for 4h to obtain ferric phosphate and iron removal solution.

[0160] The first oxidant is hydrogen peroxide with a concentration of 27.5 wt%, and the amount of the first oxidant added is 1.2 times the theoretical amount required to react with ferrous ions in the system; the amount of phosphoric acid added is 1.1 times the theoretical amount required to react with iron in the system.

[0161] (4) Ferric sulfate is mixed with the iron removal solution obtained in step (3) to remove phosphorus, resulting in a phosphorus removal solution and ferric phosphate residue;

[0162] The amount of ferric sulfate added is 1.2 times the theoretical amount needed for its reaction with phosphorus;

[0163] (5) The phosphorus removal solution is first concentrated to a Ni concentration of 120 g / L. After stirring, it is mixed with a 32 wt% sodium hydroxide solution and reacted at 70°C for 1 h. After standing for 12 h, the solid and liquid are separated to obtain the impurity removal residue and the impurity removal solution.

[0164] The amount of sodium hydroxide solution added is sufficient to react with nickel in the system to generate 5 g / L of nickel hydroxide.

[0165] In this embodiment, the composition of the leachate, chromium removal filtrate, concentrate, and impurity removal solution is shown in Table 6.

[0166] Table 6

[0167]

[0168]

[0169] Example 7

[0170] This embodiment provides a method for smelting a nickel-iron alloy. The main components of the nickel-iron alloy, by mass percentage, include 25.6 wt% Ni, 0.25 wt% Co, 0.12 wt% Mn, 72.5 wt% Fe, 0.09 wt% Cr, 0.23 wt% Si, 0.012 wt% Zn, 0.002 wt% Ca, and 0.001 wt% Mg. The method includes the following steps:

[0171] (1) Nickel-iron alloy with an average particle size of 5 mm was mixed with water at a solid-liquid ratio of 1:5 (g / mL) to make a slurry. After stirring, it was mixed with sulfuric acid with a concentration of 98 wt% and acid-leached at 80℃ for 4 h. Then, hydrogen peroxide with a concentration of 27.5 wt% was added until the pH value was 1.5. Solid-liquid separation was performed to obtain leachate and leachate residue.

[0172] The amount of sulfuric acid used is 0.8 times the theoretical amount required for acid leaching;

[0173] (2) Mix the leachate obtained in step (1) with sodium carbonate, and carry out a chromium removal reaction at 40°C for 2 hours. After standing for 6 hours, perform solid-liquid separation to obtain chromium removal slag and chromium removal filtrate.

[0174] During the chromium removal reaction, a 32 wt% sodium hydroxide solution is introduced to maintain the pH value at 5;

[0175] Sodium carbonate was added in the form of a 15 wt% solution, and the amount added was 1.8 times the theoretical amount of chromium required for the reaction in the system.

[0176] (3) Mix the first oxidant, phosphoric acid and the chromium removal filtrate obtained in step (2), control the pH value to 2 with 32wt% sodium hydroxide, and remove iron at 95℃ for 4h to obtain ferric phosphate and iron removal solution.

[0177] The first oxidant is hydrogen peroxide with a concentration of 27.5 wt%, and the amount of the first oxidant added is 1.2 times the theoretical amount required to react with ferrous ions in the system; the amount of phosphoric acid added is 1.1 times the theoretical amount required to react with iron in the system.

[0178] (4) Ferric sulfate is mixed with the iron removal solution obtained in step (3) to remove phosphorus, resulting in a phosphorus removal solution and ferric phosphate residue;

[0179] The amount of ferric sulfate added is 1.2 times the theoretical amount needed for its reaction with phosphorus;

[0180] (5) The phosphorus removal solution is first concentrated to a Ni concentration of 120 g / L. After stirring, nickel hydroxide is added (based on a concentration of 5 g / L). The reaction is carried out at 70°C for 1 h, and then allowed to stand for 12 h. Solid-liquid separation is performed to obtain the impurity-removed residue and the impurity-removed solution.

[0181] In this embodiment, the composition of the leachate, chromium removal filtrate, concentrate, and impurity removal solution is shown in Table 7.

[0182] Table 7

[0183]

[0184] Example 8

[0185] This embodiment provides a method for smelting a nickel-iron alloy. The main components of the nickel-iron alloy, by mass percentage, include 25.6 wt% Ni, 0.25 wt% Co, 0.12 wt% Mn, 72.5 wt% Fe, 0.09 wt% Cr, 0.23 wt% Si, 0.012 wt% Zn, 0.002 wt% Ca, and 0.001 wt% Mg. The method includes the following steps:

[0186] (1) Nickel-iron alloy with an average particle size of 5 mm was mixed with water at a solid-liquid ratio of 1:5 (g / mL) to make a slurry. After stirring, it was mixed with sulfuric acid with a concentration of 98 wt% and acid-leached at 80℃ for 4 h. Then, hydrogen peroxide with a concentration of 27.5 wt% was added until the pH value was 1.5. Solid-liquid separation was performed to obtain leachate and leachate residue.

[0187] The amount of sulfuric acid used is 0.8 times the theoretical amount required for acid leaching;

[0188] (2) First, mix the second oxidant with the leachate obtained in step (1) for 0.5 h, then add trisodium phosphate, and carry out the chromium removal reaction for 2 h at 40 °C and pH 3.5 (adjusted with nickel hydroxide). After standing for 6 h, perform solid-liquid separation to obtain chromium removal slag and chromium removal filtrate.

[0189] The second oxidant is hydrogen peroxide with a concentration of 27.5 wt%, and the amount of the second oxidant added is such that the content of ferric ions in the system is 0.5 g / L;

[0190] Trisodium phosphate was added in the form of a 20 wt% solution, and the amount added was 1.8 times the theoretical amount of chromium required for the reaction in the system.

[0191] (3) Mix the first oxidant, phosphoric acid and the chromium removal filtrate obtained in step (2), control the pH value to 2 with 32wt% sodium hydroxide, and remove iron at 95℃ for 4h to obtain ferric phosphate and iron removal solution.

[0192] The first oxidant is hydrogen peroxide with a concentration of 27.5 wt%, and the amount of the first oxidant added is 1.2 times the theoretical amount required to react with ferrous ions in the system; the amount of phosphoric acid added is 1.1 times the theoretical amount required to react with iron in the system.

[0193] (4) Ferric sulfate is mixed with the iron removal solution obtained in step (3) to remove phosphorus, resulting in a phosphorus removal solution and ferric phosphate residue;

[0194] The amount of ferric sulfate added is 1.2 times the theoretical amount needed for its reaction with phosphorus;

[0195] (5) The phosphorus removal solution is first concentrated to a Ni concentration of 120 g / L. After stirring, it is mixed with aluminum sulfate octadecyl water and sodium hydroxide solution with a concentration of 32 wt%. The mixture is reacted at 70°C for 1 h and then allowed to stand for 12 h. Solid-liquid separation is performed to obtain the impurity removal residue and the impurity removal solution.

[0196] The amount of sodium hydroxide solution added is sufficient to make the pH of the system 5.5;

[0197] Cobalt sulfate and manganese sulfate were added to the obtained purified solution for preparation, and a ternary precursor was obtained through co-precipitation reaction.

[0198] In this embodiment, the composition of the leachate, chromium removal filtrate, concentrate, and impurity removal solution is shown in Table 8.

[0199] Table 8

[0200]

[0201] As can be seen from Examples 1 to 5 above, the preferred technical solution of the present invention can achieve the purpose of deep impurity removal, that is, it can reduce the Cr in the chromium removal filtrate to below 5 ppm and the Si in the impurity removal solution to below 10 ppm. The methods in Examples 6 to 8 employ chemical precipitation, which can reduce the Cr in the chromium removal filtrate to 10 ppm to 20 ppm and the Si to 10 ppm to 30 ppm.

[0202] In summary, the method provided by this invention achieves deep impurity removal without extraction, has low processing costs, and can convert iron in nickel-iron alloys into battery-grade ferric phosphate, while nickel can be used as a precursor, thus resulting in high overall benefits. Addressing the difficulty in removing chromium from acid leaching solutions, this method ionizes phosphates in solution into phosphate and hydroxide ions, and controls the chromium removal reaction conditions to allow phosphate and hydroxide ions to combine with iron ions in the acid leaching solution to form amorphous ferric phosphate and ferric hydroxide. Amorphous ferric phosphate induces the formation of chromium phosphate, and ferric hydroxide adsorbs some chromium ions, achieving deep chromium removal through a combination of induction and adsorption. The dephosphorization solution contains silicon, zinc, and iron. By adding silicates as an inducer, silicates ionize in solution into silicic acid and hydroxide ions. Silicic acid induces silicate ions in solution to become silicic acid, and hydroxide ions combine with iron and nickel to form ferric hydroxide and nickel hydroxide. Ferric hydroxide and nickel hydroxide adsorb silicon, achieving deep silicon removal through a combination of induction and adsorption.

[0203] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for smelting nickel-iron alloy, characterized in that, The method includes the following steps: (1) First, the nickel-iron alloy is mixed with acid for acid leaching, and then hydrogen peroxide is added to make the pH value 1 to 2 to obtain leaching solution and leaching residue; (2) First, mix the second oxidant with the leachate obtained in step (1), then add phosphate to carry out the chromium removal reaction, and after standing, perform solid-liquid separation to obtain chromium removal slag and chromium removal filtrate. (3) Mix the first oxidant, phosphoric acid and the chromium removal filtrate obtained in step (2) to remove iron, and obtain ferric phosphate and iron removal solution; (4) The ferric salt is mixed with the iron removal solution obtained in step (3) to remove phosphorus, resulting in a phosphorus removal solution and ferric phosphate residue; (5) The phosphorus removal solution obtained in step (4) is first concentrated, then mixed with silicate and alkaline solution, and after the reaction is allowed to stand. Solid-liquid separation is performed to obtain impurity residue and impurity removal solution. The obtained impurity removal solution is used to prepare precursor.

2. The method according to claim 1, characterized in that, The acid includes any one or a combination of at least two of sulfuric acid, hydrochloric acid, or nitric acid.

3. The method according to claim 2, characterized in that, The acid is sulfuric acid.

4. The method according to claim 1, characterized in that, The amount of acid used is more than 0.8 times the theoretical amount.

5. The method according to claim 1, characterized in that, The acid leaching temperature is 70°C to 90°C.

6. The method according to claim 1, characterized in that, The acid leaching time is 2.5 hours to 5 hours.

7. The method according to claim 1, characterized in that, The second oxidant includes any one or a combination of at least two of hydrogen peroxide, sodium persulfate, or manganese dioxide.

8. The method according to claim 1, characterized in that, The amount of the second oxidant added is such that the content of ferric ions in the system is 0.5 g / L to 2 g / L.

9. The method according to claim 1, characterized in that, The phosphate includes any one or a combination of at least two of trisodium phosphate, sodium dihydrogen phosphate, or sodium monohydrogen phosphate.

10. The method according to claim 1, characterized in that, The amount of phosphate added is 1.1 to 3 times the theoretical amount of chromium required for the reaction in the system.

11. The method according to claim 1, characterized in that, The temperature for the chromium removal reaction is 25°C to 50°C.

12. The method according to claim 1, characterized in that, The pH value of the chromium removal reaction is 3 to 5.

13. The method according to claim 1, characterized in that, The chromium removal reaction takes 1 to 3 hours.

14. The method according to claim 1, characterized in that, The settling time in step (2) is 5 to 12 hours.

15. The method according to claim 1, characterized in that, Step (3) The first oxidant includes any one or a combination of at least two of hydrogen peroxide, oxygen, ozone or sodium persulfate.

16. The method according to claim 15, characterized in that, The first oxidant is hydrogen peroxide.

17. The method according to claim 1, characterized in that, The amount of the first oxidant added is 1 to 1.5 times the theoretical amount required for the reaction of ferrous ions in the system.

18. The method according to claim 1, characterized in that, The amount of phosphoric acid added is 1 to 1.2 times the theoretical amount of iron required for the reaction in the system.

19. The method according to claim 1, characterized in that, The iron removal in step (3) is carried out under conditions of pH 1 to 2.

20. The method according to claim 1, characterized in that, The iron removal temperature in step (3) is 80°C to 95°C.

21. The method according to claim 1, characterized in that, The ferric salt mentioned in step (4) includes ferric sulfate.

22. The method according to claim 1, characterized in that, The amount of ferric salt added in step (4) is 1 to 2 times the theoretical amount required for the reaction with phosphorus.

23. The method according to claim 1, characterized in that, The concentration is achieved by concentrating the Ni concentration in the solution to a value of 100 g / L to 120 g / L.

24. The method according to claim 1, characterized in that, The amount of silicate added is from 0.1 g / L to 1.5 g / L.

25. The method according to claim 1, characterized in that, The amount of alkali solution added is sufficient to react with nickel in the system to generate nickel hydroxide at a concentration of 3 g / L to 10 g / L.

26. The method according to claim 1, characterized in that, The reaction temperature in step (5) is 50°C to 80°C.

27. The method according to claim 1, characterized in that, The reaction time in step (5) is 1 to 3 hours.

28. The method according to claim 1, characterized in that, The settling time in step (5) is 12 to 24 hours.

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