Leaching method for recovering nickel and cobalt from nickel mat

Abstract

The purpose of an aspect of the present invention is to provide a leaching method for recovering nickel and cobalt from a nickel mat, in which the recovery rates of nickel and cobalt can be improved.

Description

Leaching method for recovering nickel and cobalt from nickel matte

[0001] The present invention relates to a leaching method for recovering nickel and cobalt from a nickel mat.

[0002] Processes for recovering valuable metals from waste resources can be divided into dry processes and wet processes. Conventional valuable metal recovery processes have predominantly used waste resources with a limited range of components as raw materials. In particular, when recovering valuable metals from waste resources using a wet process, the component range of the waste resource raw material is even more limited, which has resulted in a problem of reduced process flexibility.

[0003] Furthermore, in the case of low-grade waste resources, processes to concentrate target valuable metals or remove major impurities are often required upstream to reduce the load on the subsequent refining process; however, in such cases, these processes incurred excessive costs.

[0004] Therefore, there is a need for a method to recover valuable metals that can economically utilize waste resources while simultaneously efficiently processing large quantities of waste resources.

[0005] According to one embodiment of the present invention, a leaching method for recovering nickel and cobalt from a nickel mat can be provided, which can improve the recovery rate of nickel and cobalt.

[0006] The problems of the present invention are not limited to those described above. A person skilled in the art to which the present invention pertains will have no difficulty understanding additional problems of the present invention from the overall contents of this specification.

[0007] A leaching method according to one embodiment of the present invention may include: an atmospheric pressure leaching step of introducing a strong acid and oxygen into a nickel mat; a pressurized leaching step of introducing oxygen into the nickel mat such that the total atmospheric pressure is 4.5 bar or more and 10.0 bar or less, and pressurizing to obtain a leaching solution; and a neutralization step of introducing a neutralizing agent into the leaching solution to obtain a hydroxide.

[0008] The nickel mat described above may contain at least 30% by weight of nickel and at least 3% by weight of cobalt based on its total weight.

[0009] The above-described hydroxide may include nickel hydroxide (Ni(OH)2) and cobalt hydroxide (Co(OH)2).

[0010] The nickel mat described above can satisfy the following relationship 1.

[0011] [Equation 1] [Mg] + [Fe] + [Si] ≤ 20 wt%

[0012] In the above equation 1, [Mg], [Fe], and [Si] represent the content (weight%) of each component included in the nickel mat.

[0013] The above-mentioned strong acid may be an aqueous solution containing at least one of hydrochloric acid (HCl), sulfuric acid (H2SO4), and nitric acid (HNO₃).

[0014] The above-described atmospheric pressure leaching step can be carried out at a temperature of 50°C or higher and 130°C.

[0015] The above-described pressurized leaching step can be performed at a temperature of 150°C or higher and 180°C or lower.

[0016] The above-described neutralization step may include an impurity removal step for removing impurities from the leaching solution; and a precipitation step for obtaining the hydroxide by precipitating a precipitate from the leaching solution.

[0017] In the impurity removal step described above, the pH of the leaching solution may be 4.0 or higher and 5.5 or lower, and in the precipitation step described above, the pH of the leaching solution may be 7.0 or higher and 9.0 or lower.

[0018] The above-described neutralizing agent may include at least one of calcium carbonate (CaCO3), magnesium oxide (MgO), and sodium hydroxide (NaOH).

[0019] The above-described precipitate may contain 40 to 50 weight percent nickel and 2 to 3 weight percent cobalt.

[0020] As an example, the nickel matte described above can be obtained through a collection step of introducing a powder containing carbon and valuable metals, a flux, and a thickener into a molten master alloy Fe; and a concentration step of introducing a slag-forming agent and oxygen.

[0021] As another example, the nickel matte described above may be obtained through a collection step of introducing a powder containing carbon and valuable metals, a flux, and a thickener into a molten master alloy; a concentration step of introducing a slag-forming agent and oxygen to obtain an intermediate nickel matte and slag; and a step of introducing the slag back into at least one of the collection step or the concentration step, and then repeating at least one of the collection step or the concentration step.

[0022] The above-mentioned valuable metal may include at least one selected from the group consisting of nickel, cobalt, manganese, and lithium.

[0023] The hydroxide obtained by the leaching method described above can be used as a precursor for lithium-ion battery cathode materials.

[0024] The present invention can provide a leaching method for recovering nickel and cobalt from a nickel mat that can improve the recovery rate of nickel and cobalt.

[0025] According to a leaching method according to one aspect of the present invention, a precipitate containing nickel hydroxide and cobalt hydroxide in high concentrations can be obtained from a nickel mat. Furthermore, since the precipitate contains nickel hydroxide and cobalt hydroxide in high purity, it can be suitably used as a raw material for batteries.

[0026] In particular, according to the leaching method of another aspect of the present invention, since a nickel mat is manufactured through a dry process that captures waste resources as Fe, waste resources can be easily processed in large quantities.

[0027] Figure 1 is a graph showing the thermodynamic calculation results for (A) sulfide leaching reaction and (B) iron (Fe) precipitation reaction when sulfuric acid and oxygen are introduced into a nickel mat in a temperature range of 160 to 180°C.

[0028] Figure 2 is a graph showing the equilibrium phase of the solution for each process according to pH and oxidation-reduction potential (ORP).

[0029] FIG. 3 is a flowchart schematically illustrating an leaching method of an example of the present invention.

[0030] Figure 4 is a graph showing pH, reaction temperature (°C), and ORP (mV) according to reaction time during atmospheric pressure leaching.

[0031] Figure 5 is a graph showing the XRD analysis results of the residue obtained after pressurized leaching.

[0032] Figure 6 is a graph showing pH, reaction temperature (°C), and ORP (mV) according to reaction time during impurity removal.

[0033] Figure 7 is a graph showing the XRD analysis results of the residue obtained after removing impurities.

[0034] Figure 8 is a graph showing the XRD analysis results of the precipitate obtained after precipitation.

[0035] Preferred embodiments of the present invention will be described below with reference to the attached drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0036] In addition, embodiments of the present invention are provided to more fully explain the present invention to those with average knowledge in the relevant technical field.

[0037] In describing the embodiments of the present invention, if it is determined that a detailed description of known technology related to the present invention may unnecessarily obscure the essence of the present invention, such detailed description will be omitted. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intentions or conventions of the user or operator. Therefore, such definitions should be based on the content throughout this specification. The terms used in the detailed description are merely for describing the embodiments of the present invention and should not be limited in any way. Unless explicitly stated otherwise, expressions in the singular form include the meaning of the plural form.

[0038] In this description, expressions such as “include” or “equipped” are intended to refer to certain characteristics, numbers, steps, actions, elements, parts or combinations thereof, and should not be interpreted to exclude the existence or possibility of one or more other characteristics, numbers, steps, actions, elements, parts or combinations thereof other than those described.

[0039] Unless otherwise specifically defined in the specification of the present invention, % units mean weight %.

[0040] The present invention will be described in detail below through each embodiment or example of the invention. It should be noted that each embodiment or example described in this specification is not limited to a single embodiment or example, but may also be combined with other embodiments or examples. Accordingly, the citation of claims in the patent claims is merely an example of an embodiment, and the technical concept of the present invention should not be interpreted as being limited only to a combination with the cited claims; rather, combinations with various claims are also included within the scope of the technical concept of the present invention.

[0041] Figure 1 is a graph showing the thermodynamic calculation results for (A) sulfide leaching reaction and (B) iron (Fe) precipitation reaction when sulfuric acid and oxygen are introduced into a nickel mat in a temperature range of 160 to 180°C.

[0042] The inventors knew that when sulfuric acid and oxygen are introduced into a nickel mat as shown in Figure 1 below, a thermodynamic driving force for sulfide leaching reaction and iron (Fe) precipitation reaction appears, and they deeply studied the pressurized leaching process of the nickel mat.

[0043] Furthermore, the inventors found that the pressure of oxygen introduced during the pressurized leaching process is a major factor affecting not only the leaching of valuable metals but also the precipitation ability of impurity elements Fe and Si.

[0044] Figure 2 is a graph showing the equilibrium phase of the solution according to the process as a function of pH and oxidation-reduction potential (ORP). More specifically, Figure 2-(A) shows the equilibrium phase between Ni-Fe-H2O during pressurized leaching at 160–180°C as described above, and Figure 2-(B) shows the equilibrium phase between Ni-Na-H2O when nickel hydroxide is precipitated by adding a neutralizing agent at 25°C after pressurized leaching.

[0045] That is, through the thermodynamic data of Fig. 2 below and repeated experiments, the inventors discovered the total partial pressure during pressurized leaching that allows for the efficient recovery of valuable metals when nickel matte is leached with a strong acid and neutralized with a neutralizing agent to obtain a precipitate containing nickel hydroxide and additionally cobalt hydroxide, and derived the present invention.

[0046] A leaching method according to one embodiment of the present invention may include: an atmospheric pressure leaching step of introducing a strong acid and oxygen into a nickel mat; a pressurized leaching step of introducing oxygen into the nickel mat such that the total atmospheric pressure is 4.5 bar or more and 10.0 bar or less, and pressurizing to obtain a leaching solution; and a neutralization step of introducing a neutralizing agent into the leaching solution to obtain a hydroxide.

[0047] FIG. 1 is a flowchart schematically illustrating an leaching method of one example of the present invention.

[0048] Below, each step is explained in detail.

[0049] A leaching method according to one embodiment of the present invention may include an atmospheric pressure leaching step of introducing a strong acid and oxygen into a nickel mat.

[0050] That is, the present invention can effectively leach valuable metals from the nickel mat and precipitate and remove iron, which is an impurity, by introducing a strong acid and oxygen into the nickel mat.

[0051] The nickel mat may contain at least 30% by weight of nickel and at least 3% by weight of cobalt based on its total weight. In addition to the nickel and cobalt, the nickel mat may further contain magnesium (Mg), iron (Fe), cobalt (Co), manganese (Mn), and silicon (Si), etc.

[0052] In particular, as an example, the nickel matte may be manufactured using scrap generated from spent lithium-ion batteries. Such nickel matte is characterized by a high cobalt content compared to nickel sulfide ore and nickel matte derived from ore. Thus, the present invention aims to recover not only nickel but also cobalt from spent lithium-ion batteries by utilizing a pressurized leaching method.

[0053] However, the inventors have found that in order to produce a precipitate containing high-purity nickel hydroxide and cobalt hydroxide using the leaching method of the present invention, it is necessary to control the content of the component treated as an impurity in the nickel mat to a level below a certain threshold.

[0054] There are various components treated as impurities, such as magnesium (Mg), iron (Fe), manganese (Mn), and silicon (Si), but in particular, the present invention has discovered that the nickel recovery rate can be further increased when the content of magnesium (Mg), iron (Fe), and silicon (Si) in the nickel mat is controlled.

[0055] Accordingly, the nickel mat according to one example of the present invention can satisfy the following relationship 1.

[0056] [Equation 1] [Mg] + [Fe] + [Si] ≤ 20 wt%

[0057] In the above equation 1, [Mg], [Fe], and [Si] represent the content (weight%) of each component included in the nickel mat.

[0058] If the total weight of Mg, Fe, and Si derived by Equation 1 exceeds 20% by weight, it may be difficult to obtain the high-purity hydroxide intended in the present invention.

[0059] Meanwhile, the strong acid may be an aqueous solution containing at least one of hydrochloric acid (HCl), sulfuric acid (H2SO4), and nitric acid (HNO₃), and as a preferred example, the strong acid may be an aqueous solution of sulfuric acid (H2SO4).

[0060] In this way, when the strong acid used for leaching is an aqueous sulfuric acid (H2SO4) solution, the reaction equation in the above atmospheric pressure leaching step is as shown in reaction equations 1 and 2 below.

[0061] [Reaction Equation 1]

[0062] Ni (s) + H2SO4(aq) → NiSO4(aq) + H2(g)

[0063] [Reaction Equation 2]

[0064] 4FeSO4(s) + O2(g) + 4H2O (l) → 2Fe2O3(s) + 4H2SO4(aq)

[0065] In other words, the present invention can leach nickel from the nickel matte and precipitate iron in solid form through an atmospheric pressure leaching step, as shown in reaction schemes 1 and 2 above.

[0066] The above atmospheric pressure leaching step can be performed at a temperature of 50°C or higher and 130°C.

[0067] If the above atmospheric pressure leaching step is performed at a temperature of less than 50°C, valuable metals may not be sufficiently leached. On the other hand, if the temperature is excessively high, excessive costs may be invested in equipment to prevent damage to the leaching tank; therefore, the present invention may set the temperature in the above atmospheric pressure leaching step to 130°C or lower. As another example, the temperature in the above atmospheric pressure leaching step may be 60 to 120°C or 80 to 100°C.

[0068] In addition, the present invention can adjust the pH to 1.0 or higher and 1.6 or lower within the above-described temperature range. The above-described pH may refer to the pH measured after the leaching reaction is completed.

[0069] If the pH is less than 1.0, the material of the leaching tank may be damaged by strong acid. On the other hand, if the pH is greater than 1.6, a problem may occur where valuable metals in the nickel matte are not completely leached out. As another example, the pH may be 1.1 to 1.5 or 1.2 to 1.4.

[0070] The present invention can make the ORP in the above atmospheric pressure leaching step between -400mV and 200mV.

[0071] If the ORP is less than -400mV, a problem may occur in which valuable metals are reduced instead. However, if the ORP is greater than 200mV, peroxidation may occur or the reaction rate may slow down, so valuable metals may not be sufficiently leached; therefore, the present invention may set the ORP in the atmospheric pressure leaching step to be between -400mV and 200mV. As another example, the ORP may be between -350mV and 200mV or between -300mV and 200mV.

[0072] Then, a leaching method according to one embodiment of the present invention may include a pressurized leaching step of introducing oxygen into the nickel mat and pressurizing to obtain a leaching solution.

[0073] The present invention enables the leaching of nickel remaining in the nickel matte after atmospheric pressure leaching in the form of nickel sulfate (NiSO4) through the pressurized leaching step. By utilizing such a two-stage leaching process, the present invention can increase the dissolution rate of nickel and remove iron, which is an impurity. The reaction equation at this time is identical to reaction equations 1 and 2 described above. Additionally, the present invention, through the pressurized leaching step, silicon ions (Si 4+ ) can be removed by precipitating silicon oxide (SiO2), and the reaction equation at this time is as shown in Reaction Equation 3 below.

[0074] [Reaction Equation 3]

[0075] Si 4+(aq) + O2(g) → SiO2(s)

[0076] According to an embodiment of the present invention, in the pressurized leaching step, the total atmosphere pressure after oxygen introduction may be 4.5 bar or more and 10.0 bar or less.

[0077] If the total atmosphere pressure is less than 4.5 bar, the leaching of nickel and the precipitation of iron described above may not occur easily. On the other hand, if the total atmosphere pressure exceeds 10 bar, it may be difficult to obtain high-purity nickel and cobalt hydroxide as impurities containing iron are leached out along with nickel or cobalt.

[0078] The above pressurized leaching step may be performed at a temperature of 150°C or higher and 180°C or lower. If the above pressurized leaching step is performed at a temperature below 150°C, it may be difficult to additionally leach out residual sulfides (NiS, Ni3S2, CoS, Co3S4, FeS) remaining after the above atmospheric pressure leaching. On the other hand, if the temperature is excessively high, a problem of damage to the leaching tank may occur; therefore, the present invention may set the temperature in the above pressurized leaching step to 180°C or lower. As another example, the temperature in the above pressurized leaching step may be 155 to 175°C or 160 to 165°C.

[0079] The present invention can set the ORP in the pressurized leaching step to 200mV or more and 700mV or less.

[0080] If the ORP is less than 200mV, the leaching of residual sulfides or the precipitation of iron after the above-described atmospheric pressure leaching may be insufficient. Additionally, if the ORP is greater than 700mV, peroxidation of valuable metals may occur or the reaction rate may slow down, causing the above-described reactions to proceed inefficiently. As another example, the ORP may be 300mV to 600mV or 400mV to 550mV.

[0081] Next, a leaching method according to one embodiment of the present invention may include a neutralization step of adding a neutralizing agent to the leaching solution obtained according to the above to obtain a hydroxide.

[0082] Impurity elements such as Al, Mg, Si, Ca, and Na can be removed from the leaching solution by adding the aforementioned neutralizing agent. Additionally, nickel and cobalt can be recovered by precipitating them in the form of (Ni,Co)(OH)2 through the neutralization step.

[0083] That is, the neutralization step may include an impurity removal step for removing impurities from the leaching solution; and a precipitation step for obtaining the hydroxide by precipitating a precipitate from the leaching solution.

[0084] In the above impurity removal step, the pH of the leaching solution may be 4.0 or higher and 5.5 or lower.

[0085] If the pH is less than 4.0 in the above impurity removal step, impurities such as Al, Mg, Si, Ca, and Na may not be sufficiently precipitated. On the other hand, if the pH is greater than 5.5, the recovery rate may be lowered as the target valuable metal precipitates together with the impurities. As another example, the pH may be 4.5 to 6.3 or 5.0 to 6.0.

[0086] In addition, the pH of the leaching solution in the above precipitation step may be 7.0 or higher and 9.0 or lower.

[0087] If the pH is less than 7.0 in the above precipitation step, the target valuable metals such as nickel and cobalt may not be precipitated. On the other hand, if the pH is greater than 9.0, impurities may additionally co-precipitate together with the target valuable metals. Accordingly, the present invention may set the pH in the above precipitation step to 7.0 or higher and 9.0 or lower. As another example, the pH may be 7.2 to 8.5 or 7.5 to 8.2.

[0088] As an example, the precipitate obtained through the precipitation step described above may contain 40 to 50 weight percent nickel and 2 to 3 weight percent cobalt.

[0089] The pH in the above-described impurity removal step and the above-described precipitation step can be controlled within the aforementioned range by appropriately adjusting the concentration and amount of the neutralizing agent. Within the scope of achieving the objective of the present invention, the concentration and method of adding the neutralizing agent are not separately limited.

[0090] As an example, the neutralizing agent may be a basic solid or solution and may be at least one of calcium carbonate (CaCO3), magnesium oxide (MgO), and sodium hydroxide (NaOH). Preferably, the neutralizing agent may be sodium hydroxide (NaOH).

[0091] In this way, when sodium hydroxide (NaOH) is used as a neutralizing agent, the precipitation reaction equations for obtaining nickel hydroxide (Ni(OH)2) and cobalt hydroxide (Co(OH)2) are as follows.

[0092] [Reaction Equation 4]

[0093] NiSO4(aq) + 2NaOH (aq) → Ni(OH)2(s) + Na2SO4(aq)

[0094] [Reaction Equation 5]

[0095] CoSO4(aq) + 2NaOH (aq) → Co(OH)2(s) + Na2SO4(aq)

[0096] Nickel hydroxide and cobalt hydroxide obtained as described above have high purity, so they can be suitably used as raw materials for battery precursors.

[0097] Meanwhile, the leaching method of the present invention described above is a wet process, but generally, such a wet process has a limited range of raw material components to which it can be applied.

[0098] Accordingly, through repeated experiments, the inventors have discovered a method for manufacturing nickel mats, which are raw materials to which the wet process of the present invention can be usefully applied.

[0099] Below, a method for manufacturing a nickel mat in which the above-described wet process can be effectively applied is described according to a leaching method according to another embodiment of the present invention.

[0100] According to one example of the present invention, the nickel mat can be obtained through a collection step of introducing a powder containing carbon and a valuable metal, a flux, and a thickener into a molten master alloy; and a concentration step of introducing a slag-forming agent and oxygen.

[0101] First, a method for manufacturing the nickel mat according to one example of the present invention may include a collection step of introducing a powder containing carbon and a valuable metal, a flux, and a thickener into a molten master alloy.

[0102] Through this process, valuable metals, including nickel contained within the powder, can be captured as sulfides. At the same time, iron can be preferentially oxidized and separated as slag. This allows for an improvement in the recovery rate of valuable metals.

[0103] As a non-limiting example, the molten master alloy may be molten pig iron (Fe).

[0104] In addition, the powder introduced into the molten master alloy may include carbon and a valuable metal, and the valuable metal may include at least one selected from the group consisting of nickel, cobalt, manganese, and lithium.

[0105] As an example, the powder containing carbon and valuable metals may be waste lithium secondary battery powder. When a nickel mat is manufactured using waste lithium secondary battery powder as the powder, nickel hydroxide that can be used as a battery precursor can be obtained from waste resources, making it environmentally friendly and economical.

[0106] The powder containing carbon and valuable metals may contain 10 to 40 weight percent of nickel based on the total weight. Additionally or alternatively, the powder may contain 5 to 30 weight percent of cobalt based on the total weight. Additionally or alternatively, the powder may contain 5 to 30 weight percent of manganese based on the total weight. However, it is not limited thereto, and powders having various compositions may be used within a range that does not impair the effects of the present invention.

[0107] Meanwhile, by introducing the flux together with the powder into the molten master alloy, a slag that is easy to work with can be produced. Accordingly, the concentration efficiency of valuable metals can be improved, and productivity can be further enhanced.

[0108] To the extent that the above-mentioned purpose can be achieved, the type of flux is not specifically limited, but as an example, the flux may be at least one of CaO and SiO2.

[0109] Meanwhile, the thickener added to the molten master alloy along with the powder and flux described above may be at least one of sulfur, sodium sulfate, and calcium sulfate.

[0110] By adding sulfur raw materials in this way, valuable metals with a high affinity for sulfur can be captured in the molten metal as sulfides, and iron can be preferentially oxidized and separated as slag.

[0111] In particular, the aforementioned thickener may be more preferably sodium sulfate or calcium sulfate.

[0112] The reason is explained in detail below.

[0113] The following reaction schemes 6 and 7 are the sulfidation and deironization reactions that occur when sulfur is used as a thickener.

[0114] [Reaction Equation 6]

[0115] 3Ni (s) + 2S (s) → Ni3S2(s)

[0116] [Reaction Equation 7]

[0117] 2Fe (l) + O2 (g) → 2FeO (s)

[0118] As such, the nickel matte manufacturing process utilizing sulfur undergoes multiple iron removal stages, which leads to problems such as thermal material balance imbalance and refractory material damage during prolonged blowing operations, resulting in very poor operational control flexibility.

[0119] Meanwhile, the following reaction scheme 8 is a sulfidation / deirionization complex reaction that occurs when sodium sulfate is used as a thickener.

[0120] [Reaction Equation 8]

[0121] 6Fe (l) + 3Ni (s) + 2Na2SO4(aq) → 2Na2O (s) + 6FeO (s) + Ni3S2(s)

[0122] As can be seen from reaction schemes 6 to 8 above, the nickel mat manufacturing process using conventional sulfur involves only a sulfation reaction, whereas the nickel mat manufacturing process using sodium sulfate may simultaneously involve an oxidation reaction of iron during the sulfation reaction of nickel. Accordingly, the nickel mat manufacturing process of the present invention can increase process efficiency by reducing the burden of the iron removal reaction. For this reason, it may be more preferable for the thickener to be sodium sulfate or calcium sulfate, which undergoes a similar sulfation / iron removal complex reaction.

[0123] Meanwhile, the above-mentioned collection step can be performed at a temperature of 1300℃ to 1500℃.

[0124] If the temperature in the above collection step is less than 1300℃, the collected valuable metals and / or slag may solidify or the viscosity may become excessively high, which may reduce the reactivity for concentration. In addition, if the temperature of the above master alloy molten metal exceeds 1500℃, the durability may be reduced, such as by the erosion of the refractory due to the reaction between the refractory and the slag inside the reactor.

[0125] Then, the method for manufacturing the nickel mat according to one example of the present invention may optionally include a concentration step in which oxygen is introduced and a slag-forming agent obtained as described above is introduced. By performing the concentration process of the valuable metal secondarily in this way, the quality of the valuable metal can be further improved.

[0126] The above slag-forming agent can contribute to the more easily reducing of valuable metal oxides in the powder. As an example, the slag-forming agent may be silica (SiO2).

[0127] The above slag-forming agent is not limited to this, but, for example, may be included in an amount greater than 0 weight% and less than or equal to 20 weight% based on the content of the powder.

[0128] Meanwhile, the oxygen injection described above may be performed using at least one of a lance and a tuyere. However, it is not limited thereto, and oxygen may be injected using various methods known in the industry.

[0129] In this step, as oxygen is introduced, the iron in the molten master alloy undergoes preferential oxidation and separates to the top of the molten metal in the form of iron oxide to form slag. At this time, as the iron removal process is performed through the reaction between iron and oxygen, a nickel matte concentrated with valuable metals can be formed. Specifically, the reaction in the iron removal process is identical to the reaction equation 7 described above.

[0130] [Reaction Equation 7]

[0131] 2Fe (l) + O2 (g) → 2FeO (s)

[0132] According to the above-described method for manufacturing nickel mats, the recovery rate of valuable metals can be improved and waste resources can be processed in large quantities through a dry process that captures waste resources as Fe. More specifically, the above-described method for manufacturing nickel mats can recover more than 90% of the valuable metals contained in the powder used as raw material.

[0133] In addition, the nickel mat according to the above description has a much higher nickel content compared to nickel concentrate or other waste resources and contains less impurities such as Mg, Fe, and Si; therefore, there is an advantage in that it can provide nickel hydroxide of higher purity than when subjected to atmospheric pressure leaching, pressurized leaching, and neutralization of the present invention described above using the nickel mat.

[0134] Hereinafter, a method for manufacturing a nickel mat according to another embodiment of the present invention will be described.

[0135] According to another embodiment of the present invention, the nickel matte may be obtained through a collection step of introducing a powder containing carbon and a valuable metal, a flux, and a thickener into a molten master alloy; a concentration step of introducing a slag-forming agent and oxygen to obtain an intermediate nickel matte and slag; and a step of introducing the slag back into at least one of the collection step or the concentration step, and then repeating at least one of the collection step or the concentration step.

[0136] With respect to the above-mentioned capture step and concentration step, the aforementioned details may be applied as is.

[0137] However, according to a method for manufacturing a nickel mat according to another embodiment of the present invention, the slag obtained through the concentration step may be reintroduced into at least one of the collection step or the concentration step, and then at least one of the collection step or the concentration step may be repeated.

[0138] In other words, the present invention allows for the recovery of valuable metals within the slag by reintroducing the slag generated in a process of concentrating valuable metals to form an intermediate nickel matte into the collection step or the concentration step. This enables an increased recovery rate of valuable metals.

[0139] More specifically, an intermediate nickel matte and slag can be formed through the aforementioned concentration step. Then, the intermediate nickel matte is separated from the molten alloy, and the slag remaining in the molten alloy can be obtained. In this way, the slag obtained in this step may contain valuable metals such as nickel and cobalt, in addition to impurities such as iron oxide.

[0140] For example, the slag may contain at least one of 1 to 10 weight percent nickel and 1 to 10 weight percent cobalt. As such, since the slag contains a significant amount of valuable metals, utilizing it can be effective in terms of economic feasibility and efficiency.

[0141] Accordingly, the present invention allows for the recovery of valuable metals contained within the slag by reintroducing the slag obtained according to the above description into the aforementioned collection step or concentration step.

[0142] At this time, the timing of the slag input in the collection step and the concentration step is not particularly limited to the extent that it does not impair the effects of the present invention. For example, in the collection step, the slag may be input simultaneously with at least one of a powder containing carbon and valuable metals, a flux, and a thickener, or it may be input separately. The order in which the slag is input is also not significantly limited.

[0143] In addition, as an example, the amount of slag added may be 5 to 25 weight percent based on the total weight of the molten master alloy. If the amount of slag added is less than 5 weight percent based on the total weight of the molten master alloy, it may be difficult to sufficiently secure the above-described effect. In addition, if the amount of slag added exceeds 25 weight percent based on the total weight of the molten master alloy, a large amount of impurities in the slag may be added, which may lower the recovery rate of valuable metals.

[0144] As such, the method for manufacturing a nickel mat according to another embodiment of the present invention described above can maximize the effect of recovering valuable metals because it can also recover valuable metals within the slag by recirculating the slag generated in the nickel mat formation process.

[0145] The present invention will be described in detail below through examples. However, it should be noted that the examples described below are intended merely to illustrate and embody the present invention and are not intended to limit the scope of the present invention. This is because the scope of the present invention is determined by the matters described in the patent claims and matters reasonably inferred therefrom.

[0146] (Example)

[0147] First, 100g of nickel matte having the composition of Table 1 was prepared. Then, atmospheric leaching and pressurized leaching were carried out using sulfuric acid and oxygen as input raw materials according to the conditions of Table 2.

[0148] First, in the above atmospheric pressure leaching, the nickel matte was dissolved in a beaker with water and sulfuric acid, and then reacted for about 8 hours. The pH, reaction temperature (°C), and ORP (mV) according to the reaction time during the above atmospheric pressure leaching are shown in Figure 4 below. Looking at Figure 4 below, it can be seen that when sulfuric acid was added, the pH reached 0.4 and then rose to around pH 1.3 as the leaching reaction proceeded.

[0149] Oxygen was introduced into the leached slurry (solid and liquid mixture) using a pressurized leaching device, and the pressurized leaching conditions are as shown in Table 2 below. At this time, the total atmospheric pressure after oxygen introduction was 15 bar, 12 bar, and 10 bar, in the order of Comparative Example 1, Comparative Example 2, and Inventive Example, respectively. After leaching, a leaching solution and a residue were obtained, and the residue was washed with water. Next, for Comparative Example 1, Comparative Example 2, and Inventive Example, the composition of the leaching solution before pressurized leaching, the leaching solution after pressurized leaching, the solution obtained by washing the residue, and the residue are shown in Tables 3 to 5, respectively.

[0150] Wt%NiCoMnAlMgSiCaFe Circular Resource Capture Concentration Alloy 65.85.46 0.002 0.007 0.001 0.02 102.99

[0151] Temperature Atmosphere Sulfuric Acid Liquid / Solid Weight Ratio pHORP Reaction Time Atmospheric Leaching (AL) 90℃ Air + O2 60g / L 8:10.4 -> 1.3 -> 200mV Total 8h Pressurized Leaching (POX) 160℃ O2 8:11.3 -> 1.9 -> 500mV Total 7h

[0152] ICP Analysis Results of Comparative Example 1 NiCoMnAlMgSiCaFeNaPLi Solid (g) Leaching solution before pressurized leaching (mg / L) 23,690 2,8630 4210 43,448 200 - Leaching solution after pressurized leaching (mg / L) 83,810 4,6290 791 492 63400 - Residue wash solution after pressurized leaching (mg / L) 1,490 86000000100 - Residue after pressurized leaching (weight%) 6.62 0.20.01 0.41 0.01 47.57 0.01 41.8 0.01 0.01 70.01 4.75

[0153] ICP Analysis Results of Comparative Example 2 NiCoMnAlMgSiCaFeNa Solid (g) Leaching solution before pressurized leaching (mg / L) 294 90 280 813 11 113 314 7 - Leaching solution after pressurized leaching (mg / L) 90 17 75 150 93 313 22 23 4 - Residue wash solution after pressurized leaching (mg / L) 124 13 70 103 00 134 8 - Residue after pressurized leaching (weight%) 7.25 0.20 0.01 0 0.39 0.01 0 7.44 0.01 0 43.8 0.01 0 2.96

[0154] ICP Analysis Results of the Inventive Example NiCoMnAlMgSiCaFeNa Solid (g) Leaching solution before pressurized leaching (mg / L) 268 60 278 711 110 107 - Leaching solution after pressurized leaching (mg / L) 92 34 250 75 14 216 53 96 - Residue washing solution after pressurized leaching (mg / L) 20 65 130 0 11 10 94 - Residue after pressurized leaching (weight%) 8.44 0.68 0.01 00.32 20.01 07.15 0.01 04 3.10 0.01 04.58

[0155] Through all of the above Tables 3 to 5, it was confirmed that nickel and cobalt were leached as sulfides through the aforementioned atmospheric pressure leaching and pressurized leaching, while simultaneously, impurities Si and Fe were removed in the residue in the form of SiO2 and Fe2O3. However, looking at Table 5, it can be seen that the concentration of dissolved Fe in the solution before pressurized leaching is lower than that in the solution after pressurized leaching; this is presumed to be because Fe was not completely precipitated in solid form under pressurized leaching conditions. Meanwhile, Figure 5 below is a graph showing the XRD analysis results of the residue after pressurized leaching. Looking at this, Si and Fe in the residue were removed in the crystalline form of SiO2 and Fe2O3, and it can be confirmed that the amount of SiO2 is relatively large, as its peak is distinct compared to that of Fe2O3. Subsequently, NaOH was added to the leaching solutions of Comparative Example 1, Comparative Example 2, and the Inventive Example to remove impurities such as Al, Mg, Si, Ca, and Na in the form of residue. The conditions at this time are as shown in Table 6 below. In addition, the pH, reaction temperature (°C), and ORP (mV) according to the reaction time during impurity removal are shown in Figure 6 below. Furthermore, the residue was washed once with water, and the XRD analysis results of the residue are shown in Figure 7 below. Through Figure 7 below, it was confirmed that the impurities were removed as crystalline residues through the impurity removal process.

[0156] Next, the amount of NaOH added to the leaching solutions of Comparative Example 1, Comparative Example 2, and the Inventive Example was increased to form a precipitate of the (Ni,Co)(OH)2 form according to the conditions in Table 6 below. The precipitate was washed twice with water. The XRD analysis results of the precipitate are as shown in Figure 8 below. Through Figure 8, it can be seen that the (Ni,Co)(OH)2 formed well in a solid form with crystals.

[0157] In the aforementioned impurity removal and precipitation steps, the compositions of the pressurized leaching solution, the solution after impurity removal at pH 5.5, the solution obtained by washing the residue obtained after impurity removal at pH 5.5, the solution obtained after precipitation at pH 7.5, the solution obtained by washing the residue obtained after precipitation at pH 7.5 once, the solution obtained by washing the residue obtained after precipitation at pH 7.5 twice, and the precipitate obtained after precipitation at pH 7.5 are shown in Tables 7, 8, and 9, respectively, according to Comparative Example 1, Comparative Example 2, and Inventive Example.

[0158] Temperature Atmosphere Neutralizer Amount of Neutralizer p HORP Time Impurity Removal 25℃ - 1M NaOH relative to leaching solution 1.3% 1.8~5.5 496 -> 202 mV Total 3 h Precipitation 25℃ - 1M NaOH relative to neutralization filtrate 126% 5.5~7.7 202 -> 167 mV Total 3 h

[0159] ICP Analysis Results of Comparative Example 1 NiCoMnAlMgSiCaFeNaPLi Solid (g) Pressurized Leaching Solution (mg / L) 83,810 4,629 079 149 263400 -PH5.5 Neutralized Filtrate (mg / L) 81,460 451 702 91250 1,39600 -PH5.5 Washing Solution (mg / L) 1,422 780000002800 -PH7.5 Neutralized Filtrate (mg / L) 9,990 29400 3520 14,79200 -PH7.5 First Washing Solution (mg / L) 1,110 32000000 1,39100 -PH7.5 Secondary wash solution (mg / L) 340900000012700 - Precipitate (weight%) 473.28<0.01 0.037<0.01 0.25<0.01<0.01 0.038<0.01<0.0129.76

[0160] ICP Analysis Results of Comparative Example 2 NiCoMnAlMgSiCaFeNa Solid (g) Pressurized Leaching Solution (mg / L) 90, 1775, 1509331322234 -PH5.5 Neutralized Filthyr (mg / L) 89732514591412202015 -PH5.5 Washing Solution (mg / L) 12016501030035 -PH5.5 Neutralized Filthyr (mg / L) 89732514591412202015 -PH7.5 Neutralized Filthyr (mg / L) 1589146431152026844 -PH7.5 First Washing Solution (mg / L) 38611180103006323 -PH7.5 Secondary wash solution (mg / L) 1000 550 10200 6-Precipitate (weight%) 47.5 3.22 <0.01 <0.01 <0.01 0.06 1 <0.01 <0.01 0.30 33.63

[0161] ICP Analysis Results of Inventive Example NiCoMnAlMgSiCaFeNa Solid (g) Pressurized Leaching Solution (mg / L) 92,342 5,075 142 165 396 -PH5.5 Neutralized Filthyr Solution (mg / L) 897 325 1459 141 220 20 15 -PH5.5 Washing Solution (mg / L) 120 165 010 300 35 -PH5.5 Neutralized Filthyr Solution (mg / L) 897 325 1459 141 220 20 15 -PH7.5 Neutralized Filthyr Solution (mg / L) 158 91 464 31 152 02 68 44 -PH7.5 1st Washing Solution (mg / L) 386 111 8010 300 6323 -PH7.5 Secondary wash solution (mg / L) 1000 550 10200 6-Precipitate (weight%) 47.1 3.10<0.01<0.01<0.01 0.01 3<0.01 0.01 70.43 33.63

[0162] Tables 10 to 12 below show the leaching recovery rate, neutralization recovery rate, and precipitation recovery rate obtained according to the following formulas.

[0163]

[0164]

[0165]

[0166] Comparative Example 1 NiCoFe Leaching Recovery Rate (%) 99.5% 99.8% 34% Neutralization Recovery Rate (%) 99.2% 99.6% 0% Precipitation Recovery Rate (%) 56% 71% -

[0167] Comparative Example 2NiCoFe Leaching Recovery Rate (%) 99.5% 99.8% 34% Neutralization Recovery Rate (%) 99.8% 100% 0.0% Precipitation Recovery Rate (%) 64% 75% -

[0168] Invention Example NiCoFe Leaching Recovery Rate (%) 99.3% 99.3% 17.5% Neutralization Recovery Rate (%) 99.1% 100% 0.0% Precipitation Recovery Rate (%) 71% 85% -

[0169] As can be seen from Tables 10 to 12 above, Comparative Examples 1 and 2, in which the total atmospheric pressure after oxygen injection during the pressurized leaching step fell short of the range presented in the present invention, did not show a higher precipitation recovery rate (%) compared to the Inventive Example. On the other hand, the Inventive Example, which satisfies all the process conditions presented in the present invention, showed a leaching recovery rate and neutralization recovery rate close to 100%, and a precipitation recovery rate of nickel and cobalt of 70% or more.

[0170] Through this, in the case of the invention example, high-purity nickel hydroxide and cobalt hydroxide can be recovered, and it was confirmed that the recovery rate is also higher than that of other examples.

[0171] Therefore, the hydroxide containing nickel and cobalt obtained through the leaching method of the present invention is expected to be useful as a raw material for battery precursors.

[0172] The present invention is a technology developed through the following national research and development project:

[0173] [Private Information]

[0174] National R&D project that supported this invention

[0175] [Project ID] 1415186793

[0176] [Ministry Name] Ministry of Trade, Industry and Energy

[0177] [Specialized Research Management Agency] Korea Institute of Energy Technology Evaluation and Planning

[0178] [Project Title] Development of Source Technology for Rare Metal Concentration and Recovery (Throughput 200kg / day) to Establish an Open Resource Circulation Platform for Low-Grade Solid Composite Resources (DPx)

[0179] [Principal Research Institution] Pohang Institute of Industrial Science and Technology Foundation

[0180] [Research Period] 2024.01.01 ~ 2024.12.31

Claims

1. Atmospheric pressure leaching step of introducing strong acid and oxygen into the nickel mat; A pressurized leaching step of introducing oxygen into the nickel mat such that the total atmospheric pressure is 4.5 bar or more and 10.0 bar or less, and pressurizing to obtain a leaching solution; and A leaching method comprising a neutralization step of adding a neutralizing agent to the above leaching solution to obtain a hydroxide.

2. In Paragraph 1, A leaching method in which the nickel mat contains at least 30% by weight of nickel and at least 3% by weight of cobalt based on its total weight.

3. In Paragraph 1, A leaching method in which the above hydroxide includes nickel hydroxide (Ni(OH)2) and cobalt hydroxide (Co(OH)2).

4. In Paragraph 1, The above nickel mat is a leaching method satisfying the following relationship 1. [Equation 1] [Mg] + [Fe] + [Si] ≤ 20 wt% In the above equation 1, [Mg], [Fe], and [Si] represent the content (weight%) of each component included in the nickel mat.

5. In Paragraph 1, A leaching method in which the strong acid is an aqueous solution containing at least one of hydrochloric acid (HCl), sulfuric acid (H2SO4), and nitric acid (HNO₃).

6. In Paragraph 1, The above atmospheric pressure leaching step is a leaching method performed at a temperature of 50°C or higher and 130°C.

7. In Paragraph 1, The above pressurized leaching step is a leaching method performed at a temperature of 150°C or higher and 180°C or lower.

8. In Paragraph 1, The above neutralization step is an impurity removal step for removing impurities from the leaching solution; and A leaching method comprising a precipitation step of precipitating a precipitate from the above leaching solution to obtain the above hydroxide.

9. In Paragraph 8, A leaching method in which the pH of the leaching solution in the impurity removal step is 4.0 or higher and 5.5 or lower, and the pH of the leaching solution in the precipitation step is 7.0 or higher and 9.0 or lower.

10. In Paragraph 1, A leaching method comprising at least one of calcium carbonate (CaCO3), magnesium oxide (MgO), and sodium hydroxide (NaOH) as the neutralizing agent.

11. In Paragraph 8, A leaching method in which the above precipitate comprises 40 to 50 weight% nickel and 2 to 3 weight% cobalt.

12. In Paragraph 1, The above nickel mat A collection step of introducing a powder containing carbon and valuable metals, a flux, and a thickener into a molten Fe master alloy; and It is obtained through a concentration step in which a slag-forming agent and oxygen are introduced, and The above-mentioned thickener is at least one of sulfur, sodium sulfate, and calcium sulfate, and A leaching method in which the above powder contains 10 to 40 weight percent of nickel based on the total weight.

13. In Paragraph 1, The above nickel mat A collection step of introducing a powder containing carbon and valuable metals, a flux, and a thickener into a molten master alloy; A concentration step of obtaining an intermediate nickel matte and slag by introducing a slag-forming agent and oxygen; The above slag is obtained by reintroducing it into at least one of the collection step or the concentration step, and then repeating at least one of the collection step or the concentration step. The above-mentioned thickener is at least one of sulfur, sodium sulfate, and calcium sulfate, and A leaching method in which the above powder contains 10 to 40 weight percent of nickel based on the total weight.

14. In Paragraph 12 or 13, A leaching method wherein the above-mentioned valuable metal comprises at least one selected from the group consisting of nickel, cobalt, manganese, and lithium.

15. A hydroxide obtained by a leaching method according to any one of paragraphs 1 to 14, Hydroxide used as a precursor for lithium-ion battery cathode materials.

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