Process for the oxidative leaching of nickel and / or cobalt with ferric iron

Abstract

The present invention provides a process for the preparation of a nickel and / or cobalt salt solution by oxidative leaching of nickel and / or cobalt with ferric iron. The process comprises the following steps: i. contacting metal particles containing nickel(0) and / or cobalt(0) with an aqueous solution of an iron salt in a leaching reactor (R L ), thereby obtaining an aqueous nickel and / or cobalt salt solution containing ferrous salt, respectively; and ii. contacting the aqueous nickel and / or cobalt salt solution containing ferrous salt with an oxidizing agent in the presence of a mineral acid in an oxidation reactor (R O ), thereby obtaining an aqueous nickel and / or cobalt salt solution containing ferric salt, respectively.

Description

Technical Field

[0001] This invention relates to a method for manufacturing battery-grade nickel or cobalt salts. Background Technology

[0002] Reusable lithium-ion batteries (LIBs) have been found to have wide applications in portable devices, electric vehicles, and specialized fields such as aerospace. Key characteristics of reusable batteries include charge / discharge efficiency, cycle durability, energy density, and safety. Much progress has focused on improving the performance of LIB cathodes.

[0003] Following lithium cobalt oxide, lithium manganese oxide, and lithium iron phosphate, lithium nickel manganese cobalt oxide (“NMC”, LiNi) x Mn y Co z O2) and lithium nickel cobalt aluminum oxide (“NCA”, LiNi x Co y Al z O2 has attracted much attention due to its superior properties. It can be readily obtained by mixing a suitable mixed metal precursor with a suitable lithium compound and then heat-treating the mixture. Additional processing steps, such as doping with other elements, providing surface coatings, and improving crystallite size, have been widely reported.

[0004] The growing demand for electric vehicles (EVs) has led to an increased need for high-purity nickel and cobalt, particularly high-purity nickel or cobalt salts. In fact, refineries for producing high-purity nickel and / or cobalt are considered crucial for the supply of battery materials in the next decade. Such nickel and cobalt refineries will need to achieve high-capacity and high-efficiency methods to produce the required quantities and high purity of the desired nickel and cobalt salts. Therefore, the development and optimization of novel methods are necessary. Among other methods, the oxidative leaching of Ni or Co from high-purity nickel or cobalt metal is considered one of the more promising pathways.

[0005] Bilczuk D. et al. (“Kinetic study of the dissolution of metallic nickel in sulfuric acid solutions in the presence of different oxidants”, *Canadian Journal of Chemical Engineering*, Vol. 94, No. 10, August 5, 2016 (2016-08-05), pp. 1872-1879) investigated the dissolution of metallic nickel particles (< 50 µm) in sulfuric acid solution in a single stirred reactor during a batch process. Specifically, the effects of temperature, sulfuric acid concentration, and oxidant type (H₂O₂, O₂, or ferric sulfate) were investigated. The amount of ferric sulfate added corresponded to the stoichiometric amount required to dissolve the nickel (1 g / L Ni, 1.9 g / L Fe). The dissolution of Ni in ferric sulfate solution was observed to be pH-sensitive, and the dissolution was rapid only when the sulfuric acid concentration increased to 1 mol / L.

[0006] WO2022 / 053448 A1 describes battery-grade metal sulfate solutions that can be prepared directly from solid metal objects (such as nickel cathode plates) produced by electrolysis, said solid metal objects being treated in a continuous process at high temperature and under vigorous mixing with an aqueous leaching solution comprising at least one acid leaching agent and a liquid oxidant. The oxidant is selected from hydrogen peroxide, halogens, halogen compounds (such as chlorates and perchlorates), citric acid, and oxalic acid.

[0007] WO2023 / 166118 A1 discloses a method for preparing a nickel sulfate solution in a column reactor, wherein nickel-containing metal particles are reacted in water with an oxidative leaching solution containing sulfuric acid and hydrogen peroxide, and wherein the acid in the oxidative leaching solution is substantially depleted. Nickel metal can be added as a Ni metal cutting cathode.

[0008] WO2021 / 105365 A1 describes a method for producing nickel sulfate by leaching nickel-containing metal particles into an aqueous sulfuric acid solution. The method includes introducing the metal particles into the aqueous sulfuric acid solution and introducing an aqueous hydrogen peroxide solution into the sulfuric acid solution containing the metal particles. The nickel particles may be nickel powder or nickel lumps.

[0009] WO2023 / 187107 A1 discloses a method and apparatus for the continuous dissolution of a substance in a solvent, wherein the substance to be dissolved may be Ni prepared by electroplating (electrolytic Ni), and the solvent contains sulfuric acid and hydrogen peroxide.

[0010] However, all of the above-mentioned methods may involve high-cost hydrogen peroxide, excessive amounts of other suggested chemicals used as oxidants, and their limited availability on a large scale. On the other hand, if O2 gas is used as an inexpensive reagent to be injected directly into a packed bed reactor with large metal blocks (such as Ni metal-cut cathodes), the reaction between gaseous oxygen and the solid metal surface is extremely inefficient, and such a leaching method is not economically feasible.

[0011] Using stoichiometric amounts of ferric iron relative to the nickel to be dissolved is not feasible for industrial applications due to the introduction of a large amount of iron (which must subsequently be removed from the product stream). Similarly, using a significant excess of sulfuric acid (H₂SO₄) as a leaching agent is not feasible because the excess acid must be neutralized to meet the specifications for standard nickel and / or cobalt salt products. Summary of the Invention

[0012] The present invention provides an alternative method that further addresses at least one of the above-mentioned problems by providing the method for oxidative leaching of metal particles according to claim 1.

[0013] In step i of this method, the leaching of metal particles using ferric iron as an oxidant exhibits rapid kinetics; and the ferric iron and other iron-containing compounds used herein are easy and safe to handle, and are available at low cost. This method improves safety by suppressing H2 formation.

[0014] In step ii. of the method, ferrous iron is re-oxidized to ferric iron with an inexpensive oxidant, such that, in general, there is a net consumption of inexpensive oxidant, preferably oxygen-containing gas.

[0015] Preferably, the method is performed in a setup having a buffer tank in fluid connection with a leaching reactor and an oxidation reactor, wherein the leaching reactor is a packed bed reactor. Attached Figure Description

[0016] For further guidance, figures are included to better understand the teachings of the invention. The figures are intended to aid in the description of the invention and are not intended to limit the presently disclosed invention. The figures and symbols contained herein have the meaning commonly understood by one of ordinary skill in the art to which this invention pertains.

[0017] Figure 1A An exemplary configuration of a continuous method consistent with some embodiments of this disclosure is described.

[0018] Figure 1B An exemplary configuration of a continuous method consistent with some embodiments of this disclosure is described.

[0019] Figure 2 Exemplary configurations of (semi-)batch or sequential methods consistent with some embodiments of this disclosure are depicted.

[0020] Figure 3 A preferred configuration of the continuous method consistent with some embodiments of this disclosure is described. Detailed Implementation

[0021] Unless otherwise defined, all terms (including technical and scientific terms) used in disclosing this invention have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains. Further guidance includes terminology definitions to better understand the teachings of this invention. As used herein, the following terms have the following meanings:

[0022] Unless the context clearly specifies otherwise, as used herein, “a”, “an”, and “the” refer to both singular and plural meanings, respectively. For example, “compartment” refers to one or more compartments.

[0023] When referring to measurable values ​​(such as parameters, quantities, time intervals, etc.), as used herein, "about" is intended to cover variations of + / - 20% or less, preferably + / - 10% or less, more preferably + / - 5% or less, even more preferably + / - 1% or less, and still more preferably + / - 0.1% or less, provided such variations are suitable for implementation in the disclosed invention. However, it should be understood that the value referred to by the modifier "about" is itself specifically disclosed.

[0024] As used herein, “comprise,” “comprising,” and “comprises” and “comprised of” are synonymous with “include,” “including,” “includes,” or “contain,” and are inclusive or open-ended terms used to specify the presence of, for example, components, without excluding or precluding the presence of additional, unlisted components, features, elements, elements, components, or steps known in the art or disclosed herein.

[0025] The enumeration of a range of numbers by endpoints includes all numbers and fractions that fall into the range, as well as the enumerated endpoints. Unless otherwise defined or unless it is obvious to a person skilled in the art from its use and the context in which it is used, all percentages shall be understood as weight percentages, abbreviated as “wt.%”, or as volume percentages, abbreviated as “vol.%”.

[0026] As used in this article, “pressure” or “partial pressure” refers to absolute pressure, and in this context, the units “bar” or “bara” are equivalent to each other.

[0027] As used herein, “metal particles” refers to fragments of matter composed of pure metallic elements or metal alloys, which may have different sizes, shapes and structures, including, for example, powders or large metal fragments.

[0028] As used herein, the terms "trivalent iron" or "trivalent iron ion" or "Fe" are used interchangeably. 3+ "" refers to iron, which is in its +3 oxidation state.

[0029] As used herein, the terms "ferrous" or "ferrous ion" or "Fe" are used interchangeably. 2+ "" refers to iron, which is in its +2 oxidation state.

[0030] As used in this article, "oxidizing agent" refers to the agent that oxidizes Ni(0) and Co(0) to Ni, respectively. 2+ and Co 2+ The reagent refers to the reagent that oxidizes ferrous iron to ferric iron.

[0031] As used herein, “mineral acid” should be considered equivalent to the term “inorganic acid” and refers to mineral acids that are highly soluble in water and form hydrogen ions and conjugate bases when dissolved in water.

[0032] Any water used in the method can be high-purity water, such as demineralized water or RO water.

[0033] In the context of this invention, the term "continuous method" should be considered as a method in which the resulting solution has a substantially constant composition. Specifically, a continuous method is a method in which the resulting solution has a constant composition within a range considered normal method variation. Moreover, it is envisioned that the liquid reagent fed into the reactor has a fixed composition under normal method conditions. More specifically, the resulting solution has a composition in which the concentration of each component is within a range of + / - 20% or less, preferably + / - 10% or less, more preferably + / - 5% or less, and even more preferably + / - 3% or less of its average concentration. In a preferred embodiment, the invention provides a continuous method operating under steady-state conditions.

[0034] Preferably, the mineral acid, iron source, oxidant for ferrous iron, and water are fed into the method according to the invention at substantially constant concentrations and flow rates. Ni and / or cobalt metal particles may be fed into the method intermittently or gradually. Preferably, the invention provides a method, preferably a continuous method, wherein the bed volume of nickel-containing metal particles is controlled in a column reactor within a range of + / - 20% or less, preferably + / - 10% or less, more preferably + / - 5% or less, and even more preferably + / - 3% or less of its average bed volume.

[0035] In one embodiment, the method is a discontinuous method, wherein the term "discontinuous" means that the method is interrupted when the produced solution is drained.

[0036] In the context of this invention, the terms "batch method," "semi-batch method," or "(semi)batch method" must be considered as discontinuous methods. Specifically, in the context of this invention, the terms "batch method," "semi-batch method," or "(semi)batch method" refer to a method in which the method is interrupted to drain the resulting salt solution ( 1), wherein solid, liquid, liquefied or gaseous reagents may be pre-fed into the method, or may be introduced intermittently or periodically during the method.

[0037] In one embodiment of the invention, the method is performed as a batch or semi-batch method, wherein the bed volume of the metal particles containing nickel or cobalt decreases over the reaction time in the reaction zone of the batch reactor.

[0038] In one embodiment, the batch or semi-batch method is stopped, and the nickel and / or cobalt salt solution is drained when the particles containing nickel and / or cobalt have completely reacted with and thus completely dissolved in the leaching solution. 1).

[0039] In one embodiment, the batch or semi-batch method is interrupted, and the nickel and / or cobalt salt solution is drained before the particles containing nickel or cobalt are completely dissolved. 1) Preferably, when the method is interrupted and the nickel or cobalt salt solution is drained, at least 1 wt.%, more preferably at least 2 wt.%, at least 5 wt.%, at least 10 wt.%, or at least 15 wt.%, and even more preferably at least 20 wt.%, of the initial amount of nickel or cobalt-containing particles introduced into the leaching reactor are undissolved. More preferably, when the method is interrupted and the nickel or cobalt salt solution is drained, at least 25 wt.%, of the initial amount of nickel and / or cobalt-containing particles introduced into the leaching reactor are undissolved.

[0040] In one embodiment, when the leaching rate of the metal particles is low, the reaction is stopped and the solution is withdrawn from the method.

[0041] In a preferred embodiment of the invention, the method is performed as a batch or semi-batch method, wherein the method is interrupted, and when the solution has the desired target specifications, i.e., a predetermined nickel and / or cobalt content and residual acid content, the nickel and / or cobalt salt solution ( 1) Empty.

[0042] As used herein, a “leaching reactor” refers to a reactor in which metal particles are leached with an oxidant to dissolve Ni and / or Co and form an aqueous solution of Ni and / or Co salts.

[0043] The leaching reactor of the method of the present invention is preferably a packed bed reactor. In the context of the present invention, the term "packed bed reactor" should be considered equivalent to the terms "packed bed," "column" or "column reactor," "tower" or "tower reactor," and refers to a packed bed reactor having a generally cylindrical form with an inner diameter D and a height H.

[0044] As used in this article, an “oxidation reactor” refers to a reactor in which ferrous iron is oxidized to ferrous iron.

[0045] As used herein, the term "buffering tank" is equivalent to "buffertank," "storage tank," "mixing tank," "canister," or "container," and refers herein to a container suitable for holding a relatively large volume of fluid compared to a reactor in which leaching and oxidation steps take place. The tank can be constructed of any suitable material and can be open or closed to the environment for operation under pressure. The buffer tanks described herein are further configured to include one or more inlets and outlets for receiving and / or releasing fluids according to the method of the invention.

[0046] As used herein, the term "product salt solution" ( "1)" refers to any nickel and / or cobalt salt solution emptied from the method at any point in the system, and therefore refers to, for example, the solutions depicted in Figures 1 to 3. 1A , 1B or 1C .

[0047] As used herein, the term “nickel and / or cobalt” includes the terms “nickel and cobalt”, “nickel”, and “cobalt”. The appropriate names will be clear to those skilled in the art based on the context in which they are used. For example, leaching of metal particles containing nickel (0) results in the formation of nickel salts; leaching of metal particles containing cobalt (0) results in the formation of cobalt salts; and leaching of metal particles containing both nickel (0) and cobalt (0) results in the formation of mixed nickel-cobalt salts.

[0048] In a first aspect, the present invention provides a method comprising the following steps:

[0049] i. Allow metal particles containing nickel (0) and / or cobalt (0) to leach into a leaching reactor (R... L Contacting the ferrous salt solution with an aqueous solution of nickel and / or cobalt salts respectively yields aqueous solutions containing ferrous salts; and

[0050] ii. In the oxidation reactor (R O In the presence of mineral acids, an aqueous solution of nickel and / or cobalt salts containing ferrous salts is contacted with an oxidizing agent to obtain an aqueous solution of nickel and / or cobalt salts containing ferric salts.

[0051] In one embodiment, the invention provides a method according to a first aspect of the invention, wherein at least a portion of the ferrous salt formed in step i. is reacted in an oxidation reactor (R... O In step ii., the iron salt is oxidized to an iron salt, and at least a portion of the iron salt formed in step ii. is leached in the leaching reactor (R). L It is used as an oxidizing agent in step i.

[0052] In step i. of this method, the leaching of metal particles using ferric iron as the oxidant exhibits rapid kinetics. Ferric salts and other iron-containing compounds used in this step are easy and safe to handle, and they are also cost-effective. Furthermore, the leaching step with ferric iron enhances safety by reducing hydrogen formation. In step ii., an inexpensive oxidant, preferably an oxygen-containing gas, is used to re-oxidize ferrous iron to ferric iron. This ensures that the entire method consumes only low-cost, readily available oxidants to leach the metal particles. Another benefit of this invention is that it provides an alternative to the existing single-step leaching methods using hydrogen peroxide as the oxidant, which require specific safety measures and have limited availability for large-scale use.

[0053] In one embodiment, the present invention provides a method according to a first aspect of the invention, wherein the aqueous solution of iron salt flows through the metal particles.

[0054] In a preferred embodiment, the iron salt aqueous solution flows through the leaching reactor (R). L The iron salt aqueous solution may be an aqueous solution of nickel and / or cobalt salts containing iron salts. The leaching reactor (R) L The reactor can be configured with an inlet and an outlet to circulate the aqueous iron salt solution through an external circulation loop using a circulation pump. The solution can be fed at the bottom of the leaching reactor and withdrawn at the top, or fed at the top of the reactor and withdrawn at the bottom.

[0055] Surprisingly, the inventors found that when using ferric iron as the leaching agent, leaching kinetics significantly improved with increasing flow of the leaching solution through the leaching reactor. Furthermore, compared to ferric iron, when using, for example, hydrogen peroxide as the oxidant, the inventors did not observe a similar improvement in leaching kinetics with increasing flow of the leaching solution through the leaching reactor.

[0056] Preferably, the regeneration of ferric iron in step ii. occurs in a different reactor vessel than the one used in step i. for leaching the metal particles. This allows for the use of iron oxidation (R... O The reactor vessel has the same characteristics as the leaching vessel (R) L Different types of reactions are carried out under different conditions, such as varying temperature, pressure, and flow rate. Because each reaction requires significantly different optimal conditions, it is industrially impractical to simultaneously conduct two reactions in a single vessel. More specifically, metal particles containing nickel (0) and / or cobalt (0) are introduced into the leaching reactor (R... L The solution is contacted with an aqueous solution of ferrous salts to produce aqueous solutions of nickel and / or cobalt salts containing ferrous salts, respectively. This resulting solution of nickel and / or cobalt salts containing said ferrous salts is then at least partially transferred to an oxidation reactor (R). O In the oxidation reactor (R) O In the process, ferrous salts are oxidized to ferric salts. The resulting ferric salt solutions, which also contain nickel and / or cobalt salts, are then at least partially transferred to a leaching reaction, whereby the ferric salt acts as a leaching agent to leach metal particles containing nickel (0) and / or cobalt (0). Thus, a loop system is formed in which mineral acids and inexpensive oxidants (such as oxygen) are consumed to produce nickel and / or cobalt salt solutions. The target nickel and / or cobalt salt solution with a sufficiently high nickel and / or cobalt concentration is also referred to herein as the product salt solution. 1) It can be emptied from the system at any point in the loop system, such as after the leaching reactor or after the oxidation reactor.

[0057] In a preferred embodiment, the first and second reaction vessels (R) O and R L ) are fluidly connected to each other, wherein at least a portion of the ferrous salt formed in step i. is in the oxidation reactor (R O In step ii., the iron salt is oxidized to an iron salt, and at least a portion of the iron salt formed in step ii. is leached in the leaching reactor (R). L It is used as an oxidizing agent in step i.

[0058] In a preferred embodiment, the leaching reactor (R) L ) and the oxidation reactor (R O ) and buffer tank (TB Fluid connection.

[0059] Preferably, at least a portion of the aqueous solution of the nickel and / or cobalt salt containing the ferrous salt formed in step i. is fed into a buffer tank (T). B ), and / or from the buffer tank (T B Obtain at least a portion of the aqueous solution of the nickel and / or cobalt salts containing iron salts for leaching in step i.

[0060] Preferably, at least a portion of the aqueous solution of the nickel and / or cobalt salt containing the iron salt formed in step ii. is fed into a buffer tank (T). B ), and / or from which the buffer tank (T B (ii) Obtain at least a portion of the aqueous solution of the nickel and / or cobalt salt containing ferrous salt oxidized in step ii.

[0061] Even more preferably, the leaching reactor (R L ) and oxidation reactor (R O ) and a single buffer tank (T B Fluid connection. This setup allows the flow rate through the oxidation reactor to be decoupled from the flow rate through the leaching reactor. Decoupling these flow rates improves method control. Furthermore, it enables larger system volumes without requiring more expensive reactor capacity. Larger system volumes are particularly advantageous for batch operation of the method.

[0062] In a preferred embodiment, the leaching reactor may be a packed bed or column reactor, or it may be a stirred reactor that does not suspend the metal particles.

[0063] In one or more embodiments, the leaching reactor is a stirred reactor in which particles settle at the bottom or are collected in a structure that is permeable to the solution, the stirred reactor holding the particles in place, for example by using a mesh structure or a barrel, and the stirred reactor is agitated by an impeller or a circulating flow.

[0064] Preferably, the leaching reactor is a packed bed reactor. During the leaching process, bed aging occurs, in which the median particle size of the metal particles containing nickel (0) and / or cobalt (0) decreases, and thereby the leaching rate increases.

[0065] The method according to the first aspect of the invention can be carried out in batch, semi-batch, or continuous manner. Product salt solution ( 1) It can be used in the leaching reactor ( 1A After that, the oxidation reactor ( 1B After or from the buffer tank ( 1C(Collected intermittently or continuously.)

[0066] Preferably, the method is a continuous method.

[0067] In one embodiment, at least a portion of the aqueous solution of nickel and / or cobalt salts containing the iron salt formed in step ii. 1B ) In step ii. ( 4) It is continuously collected with a substantially constant composition. Given the additional iron removal step, in the oxidation reactor (R) O After that, collect the product salt solution. 1B It can be advantageous for the step to begin with a high Fe content. 3+ The content is beneficial.

[0068] Preferably, it includes step i. ( 2) At least a portion of the aqueous solution of nickel and / or cobalt salts of ferrous salts formed in the process ( 1A The leaching reactor (R) is continuously collected with a substantially constant composition. Given optimal chemical efficiency, the leaching reactor (R) is used... L After that, collect the product salt solution. 1A It is advantageous because all the Fe produced is... 3+ Both can be used in leaching reactions.

[0069] In a preferred embodiment of the continuous method, such as Figure 1A , 2 As shown in Figure 3, the product stream is collected continuously ( 1A / 1C ) and the total flow after leaching reactor ( 2) volume ratio ( 1A / 1C / 2) Between 0.66% and 33.5%, preferably between 0.8% and 20%, more preferably between 1% and 10%, even more preferably between 1.2% and 5%, and more preferably about 1.5%, 2% or 2.5%.

[0070] In a preferred embodiment of the continuous method, such as Figure 1B As shown, the product stream is collected continuously ( 1B ) and the total flow after the oxidation reactor ( 4) volume ratio ( 1B / 4) Between 0.66% and 33.5%, preferably between 0.8% and 20%, more preferably between 1% and 10%, even more preferably between 1.2% and 5%, and more preferably about 1.5%, 2% or 2.5%.

[0071] In a first embodiment, the present invention provides a continuous method according to a first aspect of the invention, wherein an aqueous solution of nickel and / or cobalt salts containing iron salts is passed through the leaching reactor (R... L The bottom section of the feed is fed into the column reactor to enter the reaction section, and the aqueous solution of the nickel and / or cobalt salts containing ferrous salts is passed through the leaching reactor (R). L The top section of the reaction section is emptied from the reaction section. It will then pass through R... L At least a portion of the solution recovered from the top section 3. Transfer to a separate oxidation reactor (R O (Another part) 1A It is a continuously collected product salt solution. In R O In the process of reintroducing the column reactor (R) L Before that, at least a portion of the ferrous iron is oxidized to ferric iron. Such methods are described in... Figure 1A In. Figure 1B In the described alternative configuration, R will be used. o At least a portion of the recovered solution 5. Transfer to a separate leaching reactor (R) L (Another part) 1B It is a continuously collected product salt solution.

[0072] Figure 1A and 1B The configuration has the advantage of high chemical efficiency because in R O All Fe produced in 3+ Loop directly to R L And similarly, in R L All Fe produced in 2+ Loop to R O .

[0073] In a second embodiment, the present invention provides a semi-batch or continuous method according to the first aspect of the invention, wherein an aqueous solution of nickel and / or cobalt salts containing iron salts is passed through the leaching reactor (R... L The bottom section of the feed is fed into the column reactor to enter the reaction section, and the aqueous solution of the nickel and / or cobalt salts containing ferrous salts is passed through the leaching reactor (R). L The top section of the reaction section is emptied from the reaction section. It will then pass through R... LThe solution recovered from the top section is transferred to a buffer tank (T). B Product salt solution 1C Through the buffer tank (T) B (Collected intermittently or continuously.)

[0074] Oxidation reactor (R) O From the buffer tank (T) B ) to obtain ferrous salts ( 3) An aqueous solution of nickel and / or cobalt salts, and the feed of the aqueous solution of nickel and / or cobalt salts containing iron salts back to T. B And T B To the leaching reactor (R L Feeding. This configuration has the advantage of enabling larger system volumes and allowing for different flow rates for leaching reactions relative to oxidation reactions. This type of method is described in... Figure 2 Furthermore, this configuration allows for flexible methodological control and is suitable for both (semi-)batch and continuous operation.

[0075] In a third embodiment, the present invention provides a continuous method according to a first aspect of the invention, wherein an aqueous solution of nickel and / or cobalt salts containing iron salts is passed through the leaching reactor (R). L The bottom section of the feed is fed into the column reactor to enter the reaction section, and the aqueous solution of the nickel and / or cobalt salts containing ferrous salts is passed through the leaching reactor (R). L The top section of the reaction section is emptied from the reaction section. It will then pass through R... L The solution recovered from the top section is transferred to a buffer tank (T). B Product salt solution 1C Through the buffer tank (T) B ) Collect continuously.

[0076] Oxidation reactor (R) O From the buffer tank (T) B To obtain an aqueous solution of nickel and / or cobalt salts containing ferrous salts ( 3), and after oxidation, the solution is directly fed back to the leaching reactor (R). L This configuration offers the following advantages: it allows for a larger system volume while maintaining a high concentration of ferric iron for the leaching reaction, and it also allows for different flow rates for the leaching reaction relative to the oxidation reaction. This type of method is described in... Figure 3 middle.

[0077] The flow rate through the leaching reactor is defined as the volume of iron salt aqueous solution entering the leaching reactor per unit time per unit weight of metal particles, expressed in L.kg. -1 .h -1The iron salt aqueous solution entering the leaching reactor can be an aqueous solution of nickel and / or cobalt salts containing iron salts. 5). Preferably, during the (semi-)batch or continuous process, the flow rate through the leaching reactor remains substantially constant. The feed into the leaching reactor (R... L The flow rate of the iron salt aqueous solution can be higher than 0.05 L·kg⁻¹. -1 .h -1 or higher than 0.10 L·kg -1 .h -1 or higher than 0.20 L.kg -1 .h -1 or higher than 0.30 L.kg -1 .h -1 or higher than 0.50 L.kg -1 .h -1 or higher than 1.0 L.kg -1 .h -1 or higher than 1.5 L.kg -1 .h -1 or higher than 5 L.kg -1 .h -1 or higher than 7.5 L.kg -1 .h -1 Compared to hydrogen peroxide, in the leaching reactor (R... L ) leachate ( 5) As the flow rate increases, ferric iron exhibits a strong influence on the leaching kinetics in the leaching reactor. The inventors observed that when ferric iron is used as the solvent for leaching Ni-containing compounds... 0 and / or Co 0 When using an oxidizing agent to leach metal particles, setting a high flow rate through the leaching reactor to increase the leaching rate is advantageous. The leaching rate is typically expressed as g of metal leached per kilogram of metal per hour in the leaching reactor. At all tested flow rates, it was observed that the leaching solution (…) passing through the leaching reactor… 5) At higher flow rates, leaching kinetics are improved. No upper limit was observed for this phenomenon. However, for practical reasons, the flow rate can be limited to no more than 100 L·kg⁻¹. -1 .h -1 or not exceeding 50 L.kg -1 .h -1 or not exceeding 20 L.kg -1 .h -1 or not exceeding 10 L.kg -1 .h -1 In reality, the upper limit of traffic can be determined by settings or equipment availability.

[0078] The method according to a first aspect of the invention allows for the efficient leaching of large metal particles by contacting them with an aqueous solution of iron salts. Such large metal particles exhibit low reactivity with mineral acids (such as aqueous sulfuric acid). Furthermore, these large metal particles may not be suspended and therefore cannot react directly and efficiently with gaseous reagents (such as oxygen).

[0079] In a preferred embodiment according to the first aspect of the invention, it is introduced into the leaching reactor (R L The median particle size of the metal particles containing nickel (0) and / or cobalt (0) is at least 100 µm, preferably at least 250 µm, even more preferably at least 500 µm, or most preferably greater than 1 mm. Preferably, the median particle size of the metal particles is at most 2 m, and preferably less than 1 m, more preferably less than 200 mm, and most preferably less than 100 mm.

[0080] A suitable method for measuring metal particles with a diameter of up to 100 mm is the dry sieving method, where the median particle size is determined as the aperture size at which 50% of the metal particles are retained on a sieve with a larger aperture and 50% on a sieve with a smaller aperture. Particle size determination, particularly for larger particles (>100 mm), can be accomplished by directly measuring the diameter of individual pieces, optionally with the aid of microscopy and / or automated image analysis.

[0081] In a preferred embodiment, the metal particles are generated by electrolysis and fed in the form of shredded or cut full-plate cathode metal obtained according to the electrolytic deposition method.

[0082] In a preferred embodiment, the metal particles are generated by electrolysis and fed into the reactor in the form of electrolytic spherical objects or granules, or spheres with a diameter of about 0.5 cm.

[0083] In a preferred embodiment, the metal particles are generated by electrolysis and fed into the reactor in the form of cut Ni or Co cathode metal typically 1'' × 1'', 2'' × 2'', or 4'' × 4'' in size.

[0084] In some embodiments, the metal particles are generated by electrolysis and fed into the reactor in the form of a full-plate Ni or Co cathode metal, typically 1200 mm × 1200 mm in size.

[0085] In a preferred embodiment, the metal particles are granules, clumps, metal pellets, granules, or balls.

[0086] Metal particles can be a combination of the different types of metal particles mentioned above.

[0087] In some embodiments, the metal particles containing nickel (0) and / or cobalt (0) comprise elemental Ni particles or elemental Co particles or a combination thereof.

[0088] In some embodiments, the metal particles containing nickel (0) and / or cobalt (0) comprise an alloy containing nickel and / or cobalt, the alloy being obtained from battery smelting, ferronickel processing, or superalloy recycling, or a combination thereof.

[0089] In a preferred embodiment, the metal particles containing nickel (0) and / or cobalt (0) contain at least 96 wt.% of nickel and cobalt relative to the total weight of the metal particles, preferably 97 wt.%, preferably at least 98 wt.%, and more preferably at least 99 wt.% relative to the total weight of the metal particles.

[0090] More preferably, the metal particles containing nickel (0) and / or cobalt (0) contain at least 99.5 wt.% of Ni and / or cobalt.

[0091] Most preferably, the metal feed contains high-purity Ni metal or high-purity Co metal, with a purity typically of 99.97+, 99.98+, or even 99.99+.

[0092] Even more preferably, the metal feed preferably contains high-purity Ni metal, typically with a purity of 99.97+, 99.98+, or even 99.99+.

[0093] In some embodiments, the metal particles containing nickel (0) and / or cobalt (0) may contain less than 1 wt.%, or less than 0.5 wt.%, or less than 0.1 wt.%, of Cu, or the metal particles containing nickel (0) and / or cobalt (0) may not contain Cu. The inventors have observed that the presence of Cu may reduce the metal leaching reaction rate.

[0094] To achieve rapid reaction kinetics in the oxidative leaching reaction with ferric iron, an increased temperature relative to room temperature is required.

[0095] In a preferred embodiment, the present invention provides a method according to a first aspect, wherein the aqueous solution of iron salt is heated at the following inlet temperature (T). 入口 The feed is fed into the leaching reactor (R) in step i. L ): A temperature between 50°C and 98°C, preferably above 70°C, and more preferably above 75°C, preferably below 95°C, and most preferably at about 80°C, 85°C, 90°C or any temperature in between.

[0096] Under steady-state conditions, the leaching reactor (R) in step i. LAt least at the inlet temperature (T) of the feed solution 入口 ) temperature (T) RL The following operation is performed. In a preferred embodiment, the invention provides a method according to the first aspect, wherein the leaching reactor (R) in step i. L At least T 入口 And below the boiling point of aqueous solutions of nickel and / or cobalt salts (T RL The operation is preferably performed at a temperature above 60°C and more preferably above 75°C, preferably at a temperature of 95°C or lower, and most preferably at a temperature of about 80°C, 85°C, 90°C, 95°C or any temperature in between.

[0097] Aqueous solutions of nickel and / or cobalt salts in R L The outlet temperature is higher than the inlet temperature (T). 入口 This is because the temperature increases with the column. Preferably, the nickel and / or cobalt salt solution is vented from the reactor at a temperature below the boiling point of the solution, more preferably between 85°C and the boiling point, and even more preferably between 93°C and 100°C.

[0098] The rate of ferrous oxidation to ferric oxidation is also significantly increased relative to room temperature.

[0099] The desired operating temperature for the oxidation reactor to oxidize ferrous iron to ferric iron (i.e., an exothermic reaction) is between the inlet temperature of the leaching reactor and 150°C, in order to avoid the need for extensive cooling and / or solution evaporation between the two reactors.

[0100] In a preferred embodiment, the present invention provides a method according to a first aspect, wherein the oxidation reactor (R) in step ii. o It operates at the following temperatures: between 50°C and 150°C, preferably above 80°C, preferably below 120°C, more preferably below 100°C, and most preferably at about 85°C, 90°C, 95°C, 98°C or any temperature in between.

[0101] In a preferred embodiment, the oxidation reactor is a pressure reactor that operates at a pressure higher than atmospheric pressure.

[0102] In a preferred embodiment, an aqueous solution of nickel and / or cobalt salts containing trivalent iron is cooled between the oxidation reactor and the leaching reactor. Cooling can be performed in a heat exchanger such as a plate heat exchanger or a shell-and-tube heat exchanger, or in a reactor equipped with cooling components.

[0103] In a preferred embodiment, the present invention provides a method in which heat recovered from a cooling step is used at least in part to heat the reagents and / or the contents of the reactor.

[0104] In the leaching reactor, ferric iron undergoes a stoichiometric reaction with metal particles, meaning that two Fe atoms react... 3+ Atoms and a Ni 0 or Co 0 Atomic reactions to form Ni 2+ or Co 2+ .

[0105] In one embodiment, in the leaching reactor (R) L In sulfuric acid, the leaching of Ni metal particles occurs through the following chemical reaction:

[0106]

[0107] In particular, when leaching Ni metal cutting cathodes, the following leaching reactions with sulfuric acid are minimized:

[0108]

[0109] This means that the formation of H2 is negligible.

[0110] In addition, the presence of ferric ions as an oxidant further suppresses any H2 formation during the leaching of Ni(0) and / or Co(0) metal particles in mineral acids.

[0111] In another embodiment, when the Ni and / or Co metal cutting cathode is leached in an aqueous H2SO4 solution, the degree of chemical reaction with any dissolved O2 is minimal compared to the dissolution via ferric iron.

[0112] Preferably, the leaching of the metal particles in step i. is carried out using ferric iron (Fe3+) as the primary oxidant. Preferably, ferric iron constitutes at least 70 mol% of the total oxidant present, more preferably greater than 90 mol%, and most preferably greater than 95 mol%. This means that ferric iron is the most abundant oxidant for Ni and / or Co, and other oxidants (such as dissolved O2 or H2O2) are present in significantly lower amounts than ferric iron. In the context of this invention, mineral acids themselves are not considered oxidants.

[0113] In step i., all forms of ferric iron can act as an oxidizing agent. In one or more embodiments, ferric iron exists as a precipitated solid or as an Fe-containing... 3+ It exists in solution or as a mixture of the two forms. Preferably, in the leaching step, i.e., step i, trivalent iron mainly exists as a Fe-containing solution. 3+ The solution exists. More preferably, it contains Fe. 3+ The solution contains at least 70 mol% of the total trivalent iron present in step i, more preferably more than 90 mol%.

[0114] When the method is started, iron may be introduced in any form of iron oxide, iron hydroxide, iron oxyhydroxylate, iron chloride, iron sulfate, or metallic iron, or any combination thereof.

[0115] Iron can be supplied to the process to compensate for the loss through the product salt solution ( 1) Iron loss. In some embodiments, iron is introduced into the method continuously or intermittently in the form of iron oxide, iron hydroxide, iron oxyhydroxylide, iron chloride, iron sulfate, metallic iron, or any combination thereof. In a preferred embodiment, iron is introduced from the product salt solution ( 1) After separating from the method, it loops back into the method.

[0116] Iron may also be contained in the metal particles, in which case less iron should be introduced and / or recycled into the process.

[0117] In one embodiment, the total iron concentration in the solution during both steps i and ii is between 2 g / L and 30 g / L, preferably between 5 g / L and 20 g / L, and most preferably between 5 g / L and 15 g / L. Total iron concentration refers to the total amount of iron present in the solution sampled at any point in the method, including Fe. 2+ and Fe 3+ .

[0118] In a preferred embodiment, in both steps i and ii, the total iron concentration in the solution at the start of the method is between 2 g / L and 30 g / L, preferably between 5 g / L and 20 g / L, and most preferably between 5 g / L and 15 g / L.

[0119] In a preferred embodiment, the total iron concentration in the solution during both steps i and ii remains substantially constant throughout the method.

[0120] The inventors noted a positive correlation between the leaching rate and the total iron concentration in the solution. However, it is necessary to analyze the product stream ( 1) The added iron needs to be removed, so a balance needs to be struck between optimal reaction kinetics and minimum iron removal effort.

[0121] In one embodiment, the iron pre-product salt solution ( The amount of iron in (1) is substoichiometric relative to the total amount of nickel and cobalt. In other words, the product salt solution ( 1) The molar ratio of iron to the total molar ratio of nickel and cobalt is less than 2. Product salt solution ( 1) The molar ratio of iron to the total amount of nickel and cobalt can be lower than 1.0, or lower than 0.5, or lower than 0.25, or lower than 0.15. Product salt solution ( 1) The molar ratio of iron to the total amount of nickel and cobalt can be higher than 0.01, or higher than 0.02 or higher than 0.05.

[0122] In one embodiment, at least a portion of the aqueous solution of the nickel and / or cobalt salt obtained in step i. and / or at least a portion of the aqueous solution of the nickel and / or cobalt salt obtained in step ii. is drained from the method, and the drained solution (as shown in Figures 1 to 3) 1A , 1B , 1C The molar ratio of iron to total nickel and cobalt is less than 2, or less than 1.0, or less than 0.5, or less than 0.25 or less than 0.15.

[0123] In one embodiment, at least a portion of the aqueous solution of the nickel and / or cobalt salt obtained in step i. and / or at least a portion of the aqueous solution of the nickel and / or cobalt salt obtained in step ii. is drained from the method, and the drained solution (as shown in Figures 1 to 3) 1A , 1B , 1C The molar ratio of iron to total nickel and cobalt in the product is greater than 0.01, or greater than 0.02, or greater than 0.05.

[0124] The ratio of ferrous iron to the total content of ferrous and trivalent iron in the aqueous solution of nickel and / or cobalt salts containing ferrous salts obtained in step i. is at least 0.05, preferably at least 0.1, more preferably at least 0.15, and most preferably at least 0.25.

[0125] The ratio of ferrous iron to the total content of ferrous and trivalent iron in the aqueous solution of nickel and / or cobalt salts containing ferrous salts obtained in step i. is at most equal to 1.

[0126] The ratio of ferric iron to the total content of ferrous and ferric iron in the aqueous solution of nickel and / or cobalt salts containing iron salts obtained in step ii. is at least 0.05, preferably at least 0.1, more preferably at least 0.5, and most preferably at least 0.7.

[0127] The ratio of ferric iron to the total content of ferrous and ferric iron in the aqueous solution of nickel and / or cobalt salts containing ferrous salts obtained in step ii. is at most equal to 1. It is advantageous to produce a solution with a higher concentration of ferric iron in step ii. in order to maximize the leaching capacity in the leaching reactor. However, this ratio may not be set too high, as this could improve the performance of the leaching reactor (e.g., by adding more metal particles) to establish a more balanced operation, thus becoming more economically attractive.

[0128] The ratio of ferrous or ferric iron to the total amount of ferrous and ferric iron in the solution can be considered as a molar ratio or a weight ratio, since the two units are equivalent for this ratio.

[0129] The leaching reaction can be initiated by adding Ni salts, Co salts, or Cl anions to the matrix. Preferably, the leaching reaction is initiated by adding Ni sulfate, Co sulfate, nickel chloride, or cobalt chloride to the matrix.

[0130] In some embodiments, a catalytic element may be added to accelerate leaching kinetics and / or iron oxidation kinetics. In some embodiments, chloride anions, copper cations, or mixtures thereof are added.

[0131] The oxidation in step ii. is carried out using a ferrous oxidant, selected from the group consisting of ozone, hydrogen peroxide, Cl2, and oxygen-containing gases such as oxygen, oxygen-enriched air, or air. Preferably, the oxidant is an oxygen-containing gas. In a preferred embodiment, the oxidant is oxygen with a purity level between 85 vol% and 99 vol%.

[0132] Pressure has a significant direct impact on the iron oxidation kinetics in oxidation reactors. The effect of pressure on kinetics is greater than that of temperature or the effect of mineral acid concentration on increasing the oxidation rate.

[0133] In a preferred embodiment, the oxidation reactor is a stirred reactor, which is an autoclave capable of withstanding high pressure. In some embodiments, the oxidation reactor is made of stainless steel or lined with enamel.

[0134] In one embodiment, the absolute pressure of the atmosphere above the nickel and / or cobalt aqueous solution in the oxidation reactor is between 1 bar and 100 bar, preferably higher than 2 bar, higher than 5 bar, higher than 10 bar, higher than 15 bar, or even higher than 20 bar.

[0135] Increasing the absolute pressure of the oxygen-containing gas used as an oxidant increases the partial pressure of oxygen and improves oxidation kinetics.

[0136] In one embodiment, the method of the invention according to the first aspect of the invention uses an oxidation reactor (R) O The oxidation reactor (R) is used in the process of carrying out the oxidation process. O The atmosphere above the nickel and / or cobalt salt solution contains a gaseous oxidant with a partial pressure between 1 bar and 100 bar, or the partial pressure may be higher than 2 bar, higher than 5 bar, higher than 10 bar, higher than 15 bar, or even higher than 20 bar. The gaseous oxidant may be oxygen, chlorine, and / or ozone. In one specific embodiment, the gaseous oxidant comprises oxygen.

[0137] In one embodiment, the oxidation reactor (R) O The partial pressure of oxygen in the atmosphere above the aqueous nickel and / or cobalt solution is between 1 bar and 100 bar, preferably higher than 2 bar, higher than 5 bar, higher than 10 bar, higher than 15 bar, or even higher than 20 bar.

[0138] In practice, the upper pressure limit is determined by auxiliary equipment to deliver back pressure to the reactor.

[0139] For example, the oxidation of ferrous sulfate with oxygen is described by the following reaction:

[0140]

[0141] This oxidation reaction is exothermic, which must be taken into account during method design.

[0142] According to a first aspect of the invention, the oxidation of ferrous iron to ferric iron in step ii. requires high-shear mixing of the oxidant and aqueous solution under high pressure. In some embodiments, the high-shear mixing of the oxidant and aqueous solution under high pressure occurs in an oxidation reactor, which is a stirred reactor, a static mixer, or a radial pump. In a stirred reactor, the reactor shape, the type of stirrer, and / or the high stirring speed can prevent the reaction from being limited by the mass transfer of oxygen from the gas phase to the liquid phase.

[0143] The operating volume of the oxidation reactor is defined as the volume of solution in the oxidation reactor during the method. In one embodiment, the volume of solution in the oxidation reactor remains substantially constant during the method.

[0144] In one embodiment, the flow rate through the oxidation reactor is between 1 and 40 reactor operating volumes per hour. Preferably, the flow rate through the oxidation reactor is between 2 and 30 reactor operating volumes per hour, and more preferably between 2 and 10 reactor operating volumes per hour.

[0145] In one embodiment, at least a portion of the aqueous solution of nickel and / or cobalt salts containing the ferrous salt formed in step i. is subjected to an iron removal process.

[0146] In one embodiment, at least a portion of the aqueous solution of the nickel and / or cobalt salt obtained in step i. and / or at least a portion of the aqueous solution of the nickel and / or cobalt salt obtained in step ii. is drained from the method, and the drained solution (as shown in Figures 1 to 3) is... 1A 1B、 1C Iron removal process is carried out.

[0147] Preferably, iron removal and recovery are carried out without introducing any sodium or ammonium cations.

[0148] In one embodiment, the product salt solution is obtained by ion exchange with an extractant. 1. Fe removal is performed using a phosphorus-containing extractant, such as di(2-ethylhexyl)phosphoric acid (D2EHPA), bis(2,4,4-trimethylpentyl)phosphonic acid, or a carboxylic acid, such as neodecanoic acid. Preferably, the extractant is D2EHPA. The ion exchange can be carried out by solvent extraction or fixed-bed extraction.

[0149] In a preferred embodiment, the product salt solution is obtained by hydrolysis with alkali. 1. Removal of Fe. The alkali is selected from the group consisting of: potassium hydroxide, potassium carbonate, nickel hydroxide, nickel carbonate, cobalt hydroxide, cobalt carbonate, manganese hydroxide, manganese carbonate, calcium hydroxide, calcium carbonate, lithium hydroxide, lithium carbonate, magnesium oxide, magnesium hydroxide, magnesium carbonate, sodium hydroxide, sodium carbonate, ammonium hydroxide, or a combination of two or more of the above. Preferably, the alkali is calcium hydroxide or calcium carbonate, nickel hydroxide, nickel carbonate, cobalt hydroxide, or cobalt carbonate.

[0150] Preferably, the base is added until the pH of the product solution is between 1 and 5, preferably between 1 and 4.5, and more preferably between 3.0 and 4.0.

[0151] In one embodiment, the removal of Fe by hydrolysis with alkali is carried out in a stirred reactor by a batch or continuous method.

[0152] In one embodiment, the product is first reduced by a metallic reagent (such as Ni, Co, or Mn metal) to a salt solution. The iron in 1 makes Fe mainly act as Fe. 2+ It exists, and is then oxidized and precipitated as Fe using the alkali. 3+ This makes it easier to filter out the discus.

[0153] In a preferred embodiment, the product salt solution is obtained by hydrolysis. 1. Fe removal is accomplished using Co or Ni powder or Co or Ni agglomerates (which react with residual acid in excess under oxidizing conditions). In one embodiment, Fe removal by hydrolysis with Co or Ni powder is carried out in a stirred reactor via a batch or continuous method. In another embodiment, Fe removal by hydrolysis with Co or Ni agglomerates is carried out in a packed bed reactor.

[0154] In one embodiment, the product salt solution 1. Further purification steps are performed after iron removal, such as to separate Co from Ni, or to reduce the concentration of one or more impurities, said impurities comprising one or more selected from the list including: Cu, Cr, Pb, Zn, Mn, Al, F, C, Ca, Si, P, As, Cd, Sb, Ni, Co and Mg, or even to further reduce the iron content.

[0155] In some embodiments, the nickel and / or cobalt salt solution in steps i and ii comprises nickel chloride and / or cobalt chloride, or nitrate, or phosphate or sulfate, or a combination thereof. Preferably, the nickel and / or cobalt salt solution comprises sulfate and / or chloride salt.

[0156] In a preferred embodiment, the nickel and / or cobalt salt solution is nickel sulfate and / or cobalt sulfate, and has battery-grade purity after the purification step.

[0157] In one embodiment, the nickel and / or cobalt salt solution is a mixture of nickel sulfate and / or cobalt and nickel chloride and / or cobalt salt, which is further processed and converted into nickel carbonate and / or cobalt salt.

[0158] Product salt solution The target concentration of nickel and / or cobalt salts in 1 is at least 60 g / L Ni and / or Co, and optionally includes additional components such as sulfuric acid or hydrochloric acid.

[0159] In a preferred embodiment, the product salt solution The nickel content of 1 is at least 60 g Ni / L, and preferably at least 80 g Ni / L. The nickel salt solution preferably has a nickel salt content below the nickel saturation point at the processing temperature (i.e., at about 90°C or about 95°C). Preferably, the Ni content of the nickel salt solution is between 80 g Ni / L and 200 g Ni / L.

[0160] In one or more preferred embodiments, the nickel salt solution is a nickel sulfate solution, and the Ni content is between 90 g Ni / L and 175 g Ni / L, and more preferably between 100 g Ni / L and 150 g Ni / L. Even more preferably, the nickel sulfate solution obtained by the oxidative leaching reaction is a nickel sulfate solution with a nickel content between 110 g / L and 140 g / L, more preferably between 120 g / L and 140 g / L, and most preferably the nickel content of the nickel sulfate solution is about 130 g / L.

[0161] In one or more embodiments, the nickel salt solution is a nickel chloride solution, and the Ni content is between 150 g Ni / L and 200 g Ni / L. Most preferably, the nickel content of the nickel chloride solution is about 175 g / L.

[0162] In a preferred embodiment, the solution The cobalt content of solution 1 is at least 60 g Co / L, and preferably at least 80 g Co / L. The cobalt salt solution preferably has a cobalt salt content below the cobalt saturation point at the processing temperature (i.e., at about 90°C or about 95°C). Preferably, the Co content of the cobalt salt solution is between 80 g Co / L and 200 g Co / L.

[0163] In one or more preferred embodiments, the cobalt salt solution is a cobalt sulfate solution, and the Co content is between 90 g Co / L and 175 g Co / L, and more preferably between 100 g Co / L and 150 g Co / L. Even more preferably, the cobalt sulfate solution obtained by the oxidative leaching reaction is a cobalt sulfate solution with a cobalt content between 110 g / L and 140 g / L, more preferably between 120 g / L and 140 g / L, and most preferably the cobalt content of the cobalt sulfate solution is about 130 g / L.

[0164] In one or more embodiments, the cobalt salt solution is a cobalt chloride solution, and the Co content is between 150 g Ni / L and 200 g Ni / L. Most preferably, the cobalt content of the cobalt chloride solution is about 175 g / L.

[0165] The residual acid content in aqueous solutions of nickel and / or cobalt salts is substantially constant across different process steps and remains within a certain range, with the upper limit determined by the specifications of the final nickel and / or cobalt product, and where a minimum amount of acid is required to avoid Fe precipitation. The minimum residual acid content can be more easily obtained using batch methods. It is undesirable to require neutralization of excess residual acid in the product stream.

[0166] In a preferred embodiment, the residual acid content of the aqueous solution of nickel and / or cobalt salt containing the ferrous salt formed in step i. is between 1 g / L and 20 g / L. Preferably, the residual acid is hydrochloric acid, and the hydrochloric acid content is between 1 g / L and 10 g / L; and more preferably, the residual amount of hydrochloric acid is about 1 g / L, 2 g / L, 6 g / L, 8 g / L, or 10 g / L, or any value between these values.

[0167] More preferably, the residual acid is sulfuric acid, and the sulfuric acid content is between 2 g / L and 10 g / L, and most preferably the residual amount of sulfuric acid is about 2 g / L, 4 g / L, 6 g / L, 8 g / L or 10 g / L or any value between them.

[0168] In one embodiment, up to about 15 g / L of iron was used at a sulfuric acid concentration of about 10 g / L without significant iron precipitation.

[0169] Several reagents need to be replenished throughout the circuit: mineral acids are consumed during the iron oxidation step, and iron and acids can be obtained through the product salt solution ( 1) Removal, and water may evaporate due to increased temperature.

[0170] In one embodiment of the invention, no acid is consumed during the leaching step (step i.), and the acid content of the solution entering the leaching reactor is equal to the acid content of the solution leaving the leaching reactor.

[0171] In one embodiment of the invention, the mineral acid is consumed during the oxidation step (step ii.) of ferrous oxidation to ferric oxidation, and can be added in stoichiometric amounts to compensate for the amount consumed by iron oxidation and to compensate for the amount carried by the product stream. 1. Amount discharged. The effect of acidity in the reactor on the iron oxidation rate was assessed to be limited.

[0172] In one embodiment, the mineral acid is introduced into the leaching reactor, just before the solution enters the oxidation reactor, in the oxidation reactor, or into the buffer tank (T). B The feed is introduced into the process. In a preferred embodiment, the mineral acid is fed into the oxidation reactor to avoid or minimize iron precipitation.

[0173] The mineral acid can be sulfuric acid, hydrochloric acid, nitric acid, or phosphoric acid, or a mixture thereof. In a preferred embodiment, the mineral acid is sulfuric acid or hydrochloric acid. The maximum concentration of hydrochloric acid in water is 38 wt.%. The concentration of sulfuric acid in water is from 78 wt.% to 98 wt.%, preferably 98 wt.%.

[0174] Even more preferably, sulfuric acid and / or hydrochloric acid are fed into the oxidation reactor (R). O ).

[0175] In a preferred embodiment, the oxidation reactor is operated under acidic conditions at a concentration of less than 300 g / L H2SO4. The inventors have observed that a minimum concentration of H2SO4, not exceeding 10 g / L, is required to initiate the reaction. On average, the oxidation rate has been observed to increase approximately twofold when the sulfuric acid concentration is reduced from 130 g / L to 10 g / L.

[0176] In one embodiment, an iron-containing mineral acid solution is reintroduced into the process. The iron-containing acid solution can be prepared by dissolving an iron cake in a diluted acid solution, the iron cake being hydrolyzed from a product salt solution using an alkali. It is obtained by removing iron from 1.

[0177] In an alternative embodiment, the iron-containing mineral acid solution comprises an iron-rich aqueous acidic eluent, which is obtained by ion exchange with an extractant from the product salt solution. 1. Iron is removed to produce it.

[0178] The acid solution containing iron can be reintroduced into the leaching reactor, introduced into the oxidation reactor, introduced just before the inlet of the leaching reactor or oxidation reactor, or introduced into a buffer tank (T). B ).

[0179] In a preferred embodiment, in the product salt solution 1. Immediately after evacuation, the mineral acid solution or the mineral acid solution containing iron is reintroduced into the process, so that the product salt solution... The residual acid concentration is the lowest in 1.

[0180] Preferably, the leaching reactor is a packed bed reactor. In the packed bed reactor, fluid can flow from the bottom to the top of the column, or fluid can flow from the top to the bottom of the column. The column reactor consists of vertically arranged cylindrical columns and is arranged to operate without mechanical agitation, preferably in an upflow mode (i.e., fluid flows from the bottom to the top of the column).

[0181] The flow rate of the solution through the packed bed leaching reactor is expressed as the bed volume of solution entering the packed bed reactor per hour, where one bed volume is equal to the volume of the empty reactor reaching the bed height of the metal particles. In a preferred embodiment, the flow rate is at least one bed volume per hour, such that the residence time is at most one hour. More preferably, the flow rate is between 2 and 40 bed volumes per hour. Most preferably, the flow rate is between 10 and 30 bed volumes per hour. The inventors have surprisingly discovered that, across this entire flow rate range, increasing the flow rate further increases the leaching rate, i.e., the amount of metal leached per unit time per unit of total metal in the column. Therefore, high flow rates can be used to increase the leaching rate and total throughput of the method of the present invention.

[0182] The column reactor is further characterized by: (i) a feed section at the bottom of the cylindrical reactor for feeding a liquid reagent, such as an aqueous solution of nickel and / or cobalt salts containing ferrous salts; (ii) a top section or overflow section at the upper portion or top of the column reactor, on the opposite side of the feed section, characterized by having an effluent for collecting the overflow of an aqueous solution of nickel and / or cobalt salts containing ferrous salts; and (iii) an intermediate section or reaction section in the middle of the cylindrical reactor, in which the leaching reaction takes place. Metal particles are preferably fed at the top of the reactor and can be fed gradually or intermittently to form a metal particle bed on a support in the column reactor. The column reactor preferably includes a support above the feed section for supporting a solid reagent, such as Ni or Co metal. The support consists of a mesh for supporting the metal. Further, the column reactor is preferably equipped with a component for feeding the solid reagent (such as Ni or Co metal) into the reaction zone of the column reactor. Furthermore, the column reactor is preferably also equipped with components for radially and uniformly distributing the oxidative leaching solution in the feed section of the column reactor. Solid reagents can be fed onto the support by introducing Ni or Co metal at the top of the reactor or at any location above the support. An overflow zone is provided with an outlet to receive a nickel or cobalt salt solution via an overflow mechanism.

[0183] In a preferred embodiment, the present invention provides a method according to a first aspect of the invention, wherein the diameter of the liquid volume comprising the oxidative leaching solution in the column reactor is D. L And the height is H L The ratio H of the height to the diameter L :D L The value is between 1.0 and 10.0, preferably between 1.5 and 8.0, more preferably between 2.0 and 5.0, and most preferably about 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 or any value between them. The appropriate geometry of the liquid volume in the column reactor, especially a sufficiently high ratio H... L :D L To ensure that a one-dimensional flow can be obtained throughout the column, and that small metal particles generated by the reacted metal feed particles do not carry upwards the metal salt solution produced by the oxidative leaching reaction, thereby entraining unreacted metal particles and contaminating the obtained product solution, and reducing the efficiency of the method.

[0184] In a preferred embodiment, the present invention provides a method wherein the diameter of the bed volume composed of the metal particles in a column reactor is D. b And the height is H b The ratio H of the height to the diameter b :Db The value is between 0.8 and 5, more preferably between 1 and 5. Preferably, the height and diameter of the bed volume remain substantially constant throughout the method.

[0185] In a preferred embodiment, the present invention provides a method according to a first aspect, wherein a 1D flow profile is maintained throughout the column on a macroscopic scale.

[0186] In a preferred embodiment, the column reactor is cylindrical and has an inner diameter D and a height H, wherein the ratio of the height H to the diameter D is significantly greater than 1, such as between 1.0 and 10.0, preferably between 1.5 and 8.0, more preferably between 2.0 and 5.0, and most preferably about 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 or any value between them. A suitable geometry of the column reactor, especially a sufficiently high ratio H:D, ensures that one-dimensional flow can be obtained throughout the column.

[0187] In a preferred embodiment, the present invention provides a method in which the leaching solution is contacted with the metal particles at atmospheric pressure (i.e., 1 bar) or at a low pressure of less than 0.5 bar, preferably less than 0.2 bar, and more preferably less than 0.1 bar. Preferably, the leaching solution is contacted with the metal particles in an atmosphere of oxygen, air, or oxygen-enriched air. In another preferred embodiment, the gaseous atmosphere in the overflow section is flushed with an inert gas, such as N2. This allows for the direct removal of hydrogen in the event of hydrogen formation in the column reactor.

[0188] In a preferred embodiment, the present invention provides a method in which the gaseous atmosphere in the overflow section of the column reactor is circulated through a scrubber. Preferably, the scrubber is cooled. Preferably, the scrubber and the circulating reactor are integrated into a single unit. Preferably, the circulating reactor is maintained at a temperature between 60°C and 95°C, more preferably between about 75°C and 95°C, and even more preferably at about 75°C, 80°C, or 85°C, or any temperature in between. Lower temperatures are beneficial to the efficiency of the scrubbing operation.

[0189] In another preferred embodiment, the invention provides a method according to a first aspect, wherein a gaseous atmosphere in an overflow section of a scrubber is treated to remove any water and hydrogen that may have formed.

[0190] According to a first aspect of the invention, steps i. and ii. can occur simultaneously or sequentially, and can occur in the same reactor or in separate reactors where they can be fluidly connected. The solution to be treated in step ii. can be the solution obtained in step i., a portion of the solution obtained in step i., or any other solution. Similarly, the solution to be treated in step i. can be the solution obtained in step ii., a portion of the solution obtained in step ii., or any other solution.

[0191] The method according to the invention can use a single pressurized packed bed reactor. The method according to the invention can use a first reaction vessel for metal particles (R... L The leaching of iron (R) was performed, and a second separate reaction vessel was used for the leaching of iron (R). O The oxidation of ). Preferably, steps i. and ii. of the method are carried out in separate reactors.

[0192] Example

[0193] The following examples are intended to further illustrate the invention and are not intended to limit the scope of the invention.

[0194] Example 1

[0195] Figure 1A The method according to the invention is illustrated schematically, wherein metallic nickel is oxidized by ferric iron in a column reactor, and wherein the ferrous iron formed is oxidized in a separate oxidation reactor.

[0196] Column reactor R L It has an inner diameter D and a height H, where the ratio H:D is approximately 2.35. Column reactor R L The reaction zone is equipped with a Ni metal-cut cathode measuring approximately 50 mm (or 2'') × 50 mm (or 2'') and containing 99.97% nickel. Nickel-containing metal particles are intermittently fed onto a support plate above the reactor feed section. Figure 1A The feeding of metal particles is omitted. Ni metal is disposed in a bed having a bed volume characterized by height and diameter, wherein the ratio of height to diameter is approximately 3.

[0197] An aqueous solution of ferric sulfate containing approximately 15 g / L of iron, approximately 10 g / L of sulfuric acid, and also containing nickel sulfate is fed into a column reactor through the bottom section at a temperature of approximately 89°C, and brought into contact with metallic nickel particles to produce Ni. 0 To Ni 2+Oxidation. An aqueous solution of ferric sulfate is fed into a column reactor at a flow rate of approximately 6 times the bed volume per hour, where the bed volume (BV) is defined as the volume of the reactor reaching the bed height. At the top of the column reactor, due to the exothermic nature of the oxidation reaction, a nickel sulfate solution with a nickel content of approximately 120 g / L is drawn off at a temperature of approximately 91°C. This nickel sulfate solution further comprises ferrous sulfate and ferric sulfate. The ferrous content is approximately 54% relative to the total iron content in the nickel sulfate solution.

[0198] Gas that may accumulate at the top of the column reactor is treated in the scrubbing unit.

[0199] Adding nickel hydroxide to fractions of nickel sulfate aqueous solution 1A In this process, the fraction is drawn off at the top of the column reactor to form a filtered ferric hydroxide precipitate. Alternatively, the ferric iron in the nickel sulfate solution is first reduced to ferrous iron before adding nickel hydroxide. This ensures the formation of ferric hydroxide, which is easier to filter out. The precipitate is resuspended in an aqueous medium and reintroduced into the loop.

[0200] Fractions of nickel sulfate aqueous solution 3. Enters the iron oxidation reactor (R) O The iron oxidation reactor is operated at 10 bar in an autoclave equipped with a mechanical stirrer. In this study, ferrous iron is oxidized by introducing sulfuric acid and oxygen through an aqueous medium, raising the temperature to 93°C. The resulting ferric iron solution is eventually drawn off and, after cooling to 89°C, introduced into a nickel leaching reactor R. L middle.

[0201] Example 2

[0202] The semi-batch method according to Example 1 is implemented in the case of an additional buffer tank fluidly connected to the leaching reactor and the oxidation reactor, such as... Figure 2 As depicted. In this configuration, the effluent from the leaching reactor is directed to the buffer tank T. B The nickel sulfate solution from the leaching reactor and the solution from the iron oxidation reactor R O The ferric iron solution is mixed. This is advantageous because the leaching reactor and oxidation reactor in Example 1 can be smaller in size. The sulfuric acid aqueous solution is periodically introduced into the buffer tank. Further, the nickel sulfate aqueous solution is fractionated... 3. The mixture is directed to the oxidation reactor to oxidize ferrous iron to ferric iron by vigorous stirring under a pressurized air atmosphere.

[0203] Both the flow to the leaching reactor and the flow to the oxidation reactor originate from the buffer tank. This has the advantage that separate flow rates can be set for each loop, yet both loops operate with the same average iron content.

[0204] Once a nickel sulfate concentration of 120 g / L with a residual sulfuric acid content of 5 g / L is obtained in the buffer tank, the method is stopped and the product solution is collected. 1. And undergoes an iron removal process.

[0205] Example 3

[0206] The continuous method described in Example 1 is implemented in the case of an additional buffer tank that is fluidly connected to both the leaching reactor and the oxidation reactor, such as... Figure 3 As depicted. In this configuration, the effluent from the leaching reactor is directed to the buffer tank T. B The nickel sulfate solution from the leaching reactor and the solution from the iron oxidation reactor R O The ferric iron solution is mixed. This is advantageous because the leaching reactor and oxidation reactor in Example 1 can be smaller in size. An aqueous nickel sulfate solution is continuously drawn from a buffer tank as the nickel sulfate solution. 1.

[0207] Furthermore, the fractionation of the nickel sulfate aqueous solution... 3. The solution is directed to the oxidation reactor to oxidize ferrous iron to ferric iron by vigorous stirring under pressurized air atmosphere. An aqueous sulfuric acid solution is then introduced into the oxidation reactor. From there, an aqueous nickel sulfate solution containing ferric iron is now directly directed to the leaching reactor. This has the advantage of allowing leaching to proceed at a high concentration of ferric iron.

[0208] Example 4

[0209] The leaching column was loaded with 1-inch × 1-inch Ni-cut cathodes until the bed height reached 100 cm. The amount of Ni corresponded to 32.5 kg, and the bed volume was 7.85 L, where bed volume was defined as the volume of the column reaching the bed height. [The text then abruptly shifts to a seemingly unrelated topic:] ...using as... Figure 2 The described setup. A starting solution containing 30 g / L H₂SO₄ with 30 g / L Ni as nickel sulfate and 15 g / L Fe as ferrous sulfate was prepared. 60 L of this solution was loaded into an autoclave (R... O ), load 15 L into the buffer tank (T) B ), and 10 L was loaded into the leaching column (R) L The reactor operating volume of the autoclave is defined as the volume of solution in the autoclave, which is 60 L in this paper. The autoclave is stirred at 278 rpm.

[0210] The solution was heated to 98°C in an autoclave, to 85°C in a buffer tank, and to 85°C in the leaching column. The autoclave was then pressurized to 7 bar with O2 gas. Solution circulation was then initiated. The column pump was started at a flow rate of 25 bed volumes / hour, and the autoclave pump at 2.33 reactor volumes / hour. A constant volume of 60 L was maintained in the autoclave, leaching column, and buffer tank by adding water. H2SO4 was added to the buffer tank to maintain a constant pH. Ni cathodes were added to the leaching column to maintain the cathode bed height. After reaching steady state, a product stream with a nickel concentration of 120 g / L was collected from the buffer tank. The leaching rate was 6.4 g Ni / kg Ni / hour in the column.

Claims

1. A method comprising the following steps: i. Allow metal particles containing nickel (0) and / or cobalt (0) to leach into a leaching reactor (R... L Contacting the ferrous salt with an aqueous solution of iron salt, thereby obtaining aqueous solutions of nickel salt and / or cobalt salt containing ferrous salt; and ii. In the oxidation reactor (R O In the presence of mineral acids, aqueous solutions of nickel salts and / or cobalt salts containing ferrous salts are contacted with an oxidizing agent to obtain aqueous solutions of nickel salts and / or cobalt salts containing ferrous salts, respectively. At least a portion of the ferrous salt formed in step i. is oxidized to an iron salt in step ii., and at least a portion of the iron salt formed in step ii. is used as an oxidizing agent in step i.

2. The method according to claim 1, wherein at least a portion of the aqueous solution of the nickel salt and / or cobalt salt obtained in step i. and / or at least a portion of the aqueous solution of the nickel salt and / or cobalt salt obtained in step ii. is drained from the method, and wherein the drained solution ( 1A , 1B , 1C The molar ratio of iron to total nickel and cobalt in the product is less than 2 and greater than 0.

01.

3. The method according to claim 1 or 2, wherein the aqueous iron salt solution flows through the leaching reactor (R) L ).

4. The method according to any one of claims 1 to 3, wherein the aqueous iron salt solution is added to the leaching reactor (R) at a rate of [per hour]. L The metal particles are fed into the leaching reactor (R) at a flow rate between 0.10 L and 20 L per kilogram of metal particles. L ).

5. The method according to any one of claims 1 to 4, wherein at least a portion of the aqueous solution containing ferrous salt, nickel salt, and / or cobalt salt formed in step i. is fed into a buffer tank (T). B ), and / or from which the buffer tank (T B To obtain at least a portion of an aqueous solution containing iron salts, nickel salts, and / or cobalt salts.

6. The method according to any one of claims 1 to 5, wherein at least a portion of the aqueous solution containing iron salts, nickel salts, and / or cobalt salts formed in step ii. is fed into a buffer tank (T). B ), and / or from which the buffer tank (T B To obtain at least a portion of an aqueous solution containing ferrous salts of nickel salts and / or cobalt salts.

7. The method according to any one of claims 1 to 6, wherein the total iron concentration in the aqueous solution of the nickel salt and / or cobalt salt in steps i and ii is between 2 g / L and 30 g / L.

8. The method according to any one of claims 1 to 7, wherein the oxidant in step ii. is selected from the group consisting of oxygen-containing gas, ozone, hydrogen peroxide and Cl2.

9. The method according to any one of claims 1 to 8, wherein in the oxidation reactor (R) O The atmosphere above the solution of nickel salts and / or cobalt salts contains a gaseous oxidant with a partial pressure between 1 bar and 100 bar.

10. The method according to any one of claims 1 to 9, wherein the leaching reactor (R) L ( ) is a packed bed reactor.

11. The method according to any one of claims 1 to 10, wherein the median particle size of the metal particles containing nickel (0) and / or cobalt (0) is greater than 1 mm.

12. The method according to any one of claims 1 to 11, wherein the aqueous iron salt solution is at an inlet temperature (T) between 50°C and 98°C. 入口 Feed into the leaching reactor (R) in step i. L ).

13. The method according to any one of claims 1 to 12, wherein step ii. is performed at a temperature between 50°C and 150°C.

14. The method according to any one of claims 1 to 13, wherein the leaching in step i. is carried out with ferric iron as an oxidant, said oxidant constituting at least 70 mol of the total oxidant present.

15. The method according to any one of claims 1 to 14, wherein the ratio of ferrous iron to the total content of ferrous and ferric iron in the aqueous solution containing ferrous salts of nickel salts and / or cobalt salts obtained in step i. is at least 0.

05.

16. The method according to any one of claims 1 to 15, wherein the ratio of ferric iron to the total content of ferrous and ferric iron in the aqueous solution containing nickel salt and / or cobalt salt obtained in step ii. is at least 0.

05.

17. The method according to any one of claims 1 to 16, wherein at least a portion of the aqueous solution containing the nickel salt and / or cobalt salt formed in step i. is subjected to an iron removal process.

18. The method according to any one of claims 1 to 17, wherein at least a portion of the aqueous solution containing ferrous salt, nickel salt, and / or cobalt salt formed in step i. is collected continuously.

19. The method according to any one of claims 1 to 18, wherein the solution of nickel salt and / or cobalt salt comprises sulfate salt and / or chloride salt.

20. The method according to any one of claims 1 to 19, wherein sulfuric acid and / or hydrochloric acid are fed into the oxidation reactor (R). O ).

21. The method according to any one of claims 1 to 20, wherein the residual acid content of the aqueous solution containing ferrous salt, nickel salt and / or cobalt salt formed in step i. is between 1 g / L and 20 g / L.

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