A process for the one-step production of cobalt products from cobalt-containing ammoniacal solutions

Abstract

The application provides a method for one-step preparation of a cobalt product from an ammonia solution containing cobalt, comprising: directly pressurizing ammonia evaporation of the ammonia solution containing cobalt in a closed container at a certain temperature, and after evaporation for a certain time, solid-liquid separation is performed to obtain a cobalt tetraoxide product; and / or, after adding an appropriate amount of a reducing agent into the ammonia solution containing cobalt, directly pressurizing ammonia evaporation of the ammonia solution containing cobalt in a closed container at a certain temperature, and after evaporation for a certain time, solid-liquid separation is performed to obtain a cobalt carbonate product. The process is simple, short, easy to operate, and has a high cobalt recovery rate.

Description

Technical Field

[0001] This invention relates to the field of resource recycling technology, and in particular to a method for preparing cobalt products from a cobalt-containing ammoniacal solution in one step. Background Technology

[0002] Cobalt is an important strategic resource, widely used in alloys, batteries, catalysis, and other technological fields. Due to the selective complexation of cobalt with ammonia, typical wet recycling processes for cobalt-containing resources currently include acid leaching and ammonia leaching. During acid leaching, most impurity metals in the raw material are also leached out, especially for cobalt-containing resources with complex compositions such as spent lithium-ion batteries or laterite ore. The complex composition of the leaching solution leads to a long subsequent purification and impurity removal process, and the waste liquid treatment consumes a large amount of alkali, resulting in high costs. However, when using ammonia leaching, only transition metals such as nickel and cobalt form complexes with ammonia and enter the solution, while most impurities such as iron, magnesium, calcium, and silicon do not react with ammonia and enter the slag, significantly reducing the subsequent purification process. Therefore, compared to acid leaching, ammonia leaching has irreplaceable advantages for recovering cobalt-containing resources.

[0003] The recovery of cobalt from ammonia leaching solutions and the preparation of cobalt products, as the final step in the recovery process, is crucial for product preparation and the overall water balance. Currently, the main methods for recovering cobalt from cobalt-containing ammonia solutions and preparing cobalt products are sulfide precipitation and reduction precipitation. Sulfide precipitation involves adding a sulfiding agent, such as H₂S, (NH₄)₂S, or Na₂S, to the cobalt-containing ammonia solution, causing cobalt to precipitate as CoS. While this method is simple to operate and has a high cobalt recovery rate, the obtained CoS precipitate requires further processing to recover the cobalt, and hydrogen sulfide gas is generated during the precipitation process. Reduction precipitation mainly involves adding a reducing agent to disrupt the stability of the cobalt-ammonia complex, followed by the addition of a precipitant to obtain the corresponding cobalt precipitate.

[0004] Chinese patent document CN108396156A discloses a method for preparing cobalt products from cobalt-ammonia complexes. This method primarily involves introducing one of hydrazine hydrate, sodium borohydride, paraformaldehyde, or ethylene glycol as a reducing agent, and then adding sodium hydroxide or oxalate solution to the reduced solution to obtain cobalt hydroxide or cobalt oxalate products. While this method achieves a high cobalt recovery rate, it requires expensive reducing agents and generates saline wastewater. Therefore, developing a convenient, efficient, and sustainable method for preparing cobalt products from cobalt-containing ammoniacal solutions would not only shorten the wet cobalt recovery process but also effectively promote the development of ammonia leaching technology. Summary of the Invention

[0005] To address the problems of harmful gas generation, reducing agent dependence, and lack of ammonia recycling in existing methods for preparing cobalt products from ammoniacal solutions, this invention provides a one-step method for preparing cobalt products from cobalt-containing ammoniacal solutions. This method not only cleanly and efficiently recovers cobalt from ammoniacal solutions but also directly prepares cobalt tetroxide or cobalt carbonate products in one step, with high purity and uniform morphology. This invention simplifies the cobalt recovery steps from ammoniacal solutions, and the evaporated ammonia can be recycled, providing a new approach for ammonia-based cobalt resource recovery.

[0006] A method for preparing a cobalt product from a cobalt-containing ammoniacal solution in one step, comprising:

[0007] A cobalt-containing ammonia solution is directly pressurized and evaporated in a closed container at a certain temperature. After evaporation for a certain period of time, the solid and liquid are separated to obtain cobalt tetroxide product.

[0008] And / or, after adding an appropriate amount of reducing agent to an ammoniacal solution containing cobalt, the ammonia is directly steamed under pressure in a sealed container at a certain temperature. After evaporation for a certain period of time, the solid and liquid are separated to obtain the cobalt carbonate product.

[0009] Optionally, the cobalt-containing ammonia solution refers to a cobalt-ammonia complex solution generated by reacting metallic cobalt, cobalt salts, cobalt-containing waste or cobalt-containing minerals with a mixed solution of ammonia water and ammonium salt; the mixed solution of ammonia water and ammonium salt is selected from at least one of ammonia water-ammonium carbonate and ammonia water-ammonium bicarbonate.

[0010] Optionally, the cobalt-containing ammoniacal solution is selected from at least one of divalent cobalt-ammonia complexes or trivalent cobalt-ammonia complexes.

[0011] Optionally, air is introduced when preparing an ammoniacal solution containing cobalt. The purpose of introducing air is to oxidize some of the divalent cobalt in the solution into trivalent cobalt. Introducing a small amount of air is considered to mean that some of the cobalt in the solution exists in the trivalent form, while introducing an excess of air is considered to mean that all the cobalt in the solution exists in the trivalent form. Introducing air is to better oxidize the divalent cobalt in the solution.

[0012] When the solution contains a divalent cobalt-ammonia complex, the main reactions occurring in the process of obtaining Co3O4 are:

[0013] Co(NH)6 2+ →Co 2+ +6NH3

[0014] 4Co 2+ +O2 + 2H2O → 4Co 3+ +4OH -

[0015] Co 2+ +nOH - =Co(OH) n 2-n

[0016] Co 3+ +mOH - =Co(OH) m 3-m

[0017] Co(OH)n 2-n +Co(OH) m 3-m →Co3O4+H2O;

[0018] When the solution contains a trivalent cobalt-ammonia complex, the main reactions occurring in the process of obtaining Co3O4 are:

[0019] Co(NH3)6 3+ →Co 3+ +6NH3

[0020] 4Co(NH3)6 3+ +4OH - →4Co 2+ +24NH3+O2+2H2O

[0021] Co 2+ +nOH - =Co(OH) n 2-n

[0022] Co 3+ +mOH - =Co(OH) m 3-m

[0023] Co(OH) n 2-n +Co(OH) m 3-m →Co3O4+H2O;

[0024] The above reactions can occur when both divalent and trivalent cobalt-ammonia complexes are present in the solution.

[0025] Optionally, the cobalt concentration in the ammoniacal solution containing cobalt is ≥0.5 g / L. The cobalt content in the solution will affect the cobalt recovery rate; when the cobalt concentration in the solution is below 0.5 g / L, the cobalt recovery rate may be less than 90%.

[0026] Optionally, the pressure distillation temperature for preparing the two products is 120℃~210℃, and the reaction time is 0.5h~6h.

[0027] Optionally, the reducing agent is citric acid or tartaric acid, and the amount of reducing agent added is 0.8 to 2 times the reaction equivalent. When other reducing agents are used, complete reduction of cobalt cannot be achieved, and only a mixture can be obtained.

[0028] When citric acid is used as a reducing agent, the reaction process is as follows:

[0029] 2Co(NH3)6 3+ +C6H8O7=C5H6O5+2Co 2+ +CO2 + 12NH3 + 2H+ +

[0030] Co 2+ +CO3 2- =CoCO3

[0031] When tartaric acid is used as a reducing agent, the reaction process is as follows:

[0032] 2Co(NH3)6 3+ +C4H6O6=C3H4O4+2Co 2+ +CO2 + 12NH3 + 2H+ +

[0033] Co 2+ +CO3 2- =CoCO3

[0034] Optionally, when the reducing agent is tartaric acid, spherical cobalt carbonate is obtained; when the reducing agent is citric acid, rock-like cobalt carbonate is obtained.

[0035] Furthermore, the present invention also provides a cobalt tetroxide and / or cobalt carbonate product.

[0036] Furthermore, the present invention also provides the application of a method for preparing cobalt products in one step from a cobalt-containing ammoniacal solution in the preparation of cobalt products.

[0037] The beneficial effects of the technical solution provided by this invention include at least the following:

[0038] This invention involves pressurizing and distilling ammonia from a cobalt-containing ammonia solution. During this process, the structure of the cobalt-ammonia complex is destroyed, and divalent and trivalent cobalt interconvert in the solution, resulting in the release of large amounts of ammonia and water vapor. After evaporation to a certain volume, solid-liquid separation occurs, directly producing microspherical cobalt tetroxide while efficiently recovering cobalt. If tartaric acid or citric acid is added as a reducing agent during the pressurized ammonia distillation process, uniform spherical or rock-like cobalt carbonate products can be directly obtained. This invention features a simple process, short flow, easy operation, high cobalt recovery rate, wide applicability to raw materials, and the ability to recycle the ammonia residue and ammonia after treatment. The cobalt tetroxide or cobalt carbonate products obtained by this invention have high purity and can be used to prepare lithium cobalt oxide, magnetic materials, catalytic materials, etc., providing a new approach to ammonia-based recovery technology for cobalt-containing resources. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a phase analysis diagram of the pressurized ammonia stripping product obtained in Example 1 of the present invention;

[0041] Figure 2 This is a morphology diagram of the pressurized ammonia stripping product obtained in Example 1 of the present invention;

[0042] Figure 3 This is a phase analysis diagram of the pressurized ammonia stripping product obtained in Example 4 of the present invention;

[0043] Figure 4 This is a morphology diagram of the pressurized ammonia stripping product obtained in Example 4 of the present invention;

[0044] Figure 5 This is a phase analysis diagram of the pressurized ammonia stripping product obtained in Example 5 of the present invention;

[0045] Figure 6 This is a morphology diagram of the pressurized ammonia stripping product obtained in Example 5 of the present invention. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] Example 1

[0048] A cobalt-containing ammoniacal solution was prepared by dissolving basic cobalt carbonate in an ammonia-ammonium carbonate solution. The cobalt concentration in the solution was 9.14 g / L, and the cobalt existed in the form of a divalent cobalt-ammonium complex. 300 mL of the solution was placed in a sealed pressure vessel, heated to 120 °C, and held at that temperature for 4 hours. After the process, solid-liquid separation was performed. The cobalt recovery rate was 98%, and cobalt tetroxide (C3O4) was directly obtained. This product had a particle size of 0.5-2 μm, a cobalt content of 73.5%, and nitrogen and carbon contents of less than 0.01%. Phase analysis is shown below. Figure 1 After ammonia stripping, a single-component cobalt tetroxide product was obtained; morphology is shown below. Figure 2 The resulting cobalt tetroxide product is in the form of microspheres.

[0049] Example 2

[0050] Waste nickel-cobalt-manganese ternary battery cathode material obtained from a domestic factory was oxidized and leached in an ammonia-ammonium carbonate system to recover lithium and nickel, resulting in a cobalt-containing ammonia solution. The cobalt concentration in the solution was 15.2 g / L, and it existed in the form of trivalent cobalt-ammonia complex. 300 mL of the solution was placed in a 1 L sealed pressure vessel, heated to 180 °C and held for 2 h. After the process, solid and liquid were separated. The cobalt recovery rate was 99%, and microspherical cobalt tetroxide product could be directly obtained. The product had a particle size of 1-2.5 μm and a cobalt content of 73.2%, nickel content of 0.01%, copper content of 0.01%, iron content of 0.003%, and manganese content of 0.001%.

[0051] Example 3

[0052] A cobalt-containing ammoniacal solution was prepared by dissolving cobalt in an ammonia-ammonium carbonate system. A small amount of air was introduced during the preparation process. The cobalt concentration in the solution was 3.07 g / L, and the cobalt was in the form of divalent and trivalent cobalt-ammonia complexes. 300 mL of the solution was placed in a 1 L sealed pressure vessel, heated to 140 °C and held at that temperature for 0.5 h. After the process, the solid and liquid were separated. The cobalt recovery rate was 95%, and microspherical cobalt tetroxide products could be obtained directly. The particle size of the product was 1-2.5 μm, the cobalt content was 73.4%, and the nitrogen and carbon contents were both less than 0.01%.

[0053] Example 4

[0054] Cobalt-containing ammonia solution was obtained from a domestic copper-cobalt sulfide ore after oxidative ammonia leaching and copper recovery in an ammonia-ammonium bicarbonate system. The cobalt concentration in the solution was 0.5 g / L, mainly in the form of trivalent cobalt-ammonia complex. 300 mL of the solution was placed in a 1 L sealed pressure vessel, and 0.8 times the reaction equivalent of tartaric acid was added. The temperature was raised to 140 °C and maintained for 2 hours. After the process, solid-liquid separation was performed. The cobalt recovery rate was 99.12%, and cobalt carbonate product was directly obtained. This product has a particle size of 8-15 μm, a cobalt content of 47.5%, a copper content of 0.0001%, an iron content of 0.0003%, and a sulfur content of 0.0011%. Phase analysis is shown below. Figure 3 After ammonia stripping, a cobalt carbonate product with a single composition was obtained; its morphology is shown in [reference needed]. Figure 4 The resulting cobalt carbonate product is spherical.

[0055] Example 5

[0056] A cobalt-containing ammoniacal solution was prepared by dissolving cobalt sulfate in an ammonia-ammonium carbonate system, with a small amount of air introduced during the preparation process. The cobalt concentration in the solution was 8.69 g / L, mainly existing as a mixture of divalent and trivalent cobalt-ammonia complexes. 300 mL of the solution was placed in a 1 L sealed pressure vessel, and 2 times the reaction equivalent of citric acid was added. The temperature was raised to 210 °C and maintained for 0.5 h with a stirring speed of 100 rpm. After the reaction, solid-liquid separation was performed. The cobalt recovery rate was 99%, and cobalt carbonate was directly obtained. This product had a particle size of 9-20 μm, a cobalt content of 47.2%, a sulfur content of 0.0013%, and nitrogen and carbon contents of less than 0.01%. Phase analysis is shown below. Figure 5 After ammonia stripping, a cobalt carbonate product with a single composition was obtained; its morphology is shown in [reference needed]. Figure 6 The resulting cobalt carbonate product is in the form of rock.

[0057] Comparative Example 1

[0058] A cobalt-containing ammonia solution was obtained from a domestic copper-cobalt sulfide ore after oxidation and copper recovery in an ammonia-ammonium bicarbonate system. The cobalt concentration in the solution was 0.25 g / L, mainly in the form of trivalent cobalt-ammonia complex. 300 mL of the solution was placed in a 1 L sealed pressure vessel, heated to 140 °C and held for 2 h. After the process, solid-liquid separation was performed. The cobalt recovery rate was 70.2%, and spherical cobalt tetroxide products could be directly prepared. The product had a particle size of 1-2.5 μm, a cobalt content of 72.9%, a copper content of 0.0006%, an iron content of 0.0009%, a sulfur content of 0.0014%, and nitrogen and carbon contents of less than 0.01%.

[0059] Comparative Example 2

[0060] A cobalt-containing ammoniacal solution was prepared by dissolving basic cobalt carbonate in an ammonia-ammonium carbonate solution. The cobalt concentration in the solution was 9.14 g / L, and it existed in the form of a divalent cobalt-ammonia complex. 300 mL of the solution was placed in a sealed pressure vessel, heated to 110 °C, and held at that temperature for 2 h. After the reaction was complete, the solid and liquid phases were separated. The cobalt recovery rate was 30.28%, and only a small amount of amorphous cobalt-containing product was obtained. This product had a particle size of 2-5 μm, a cobalt content of 62.3%, a nitrogen content of 0.87%, and a carbon content of less than 0.01%.

[0061] Comparative Example 3

[0062] A cobalt-containing ammoniacal solution was prepared by dissolving cobalt sulfate in an ammonia-ammonium carbonate system, with a small amount of air introduced during the preparation process. The cobalt concentration in the solution was 8.69 g / L, mainly existing as a mixture of divalent and trivalent cobalt-ammonia complexes. 300 mL of the solution was placed in a 1 L sealed pressure vessel, heated to 140 °C and held for 10 min. After the reaction, the solid and liquid phases were separated. The cobalt recovery rate was 50.47%, yielding only a small amount of cobalt tetroxide. This product had a particle size of 0.8-2.5 μm, a cobalt content of 73.4%, a sulfur content of 0.0004%, and nitrogen and carbon contents of less than 0.01%.

[0063] Comparative Example 4

[0064] A cobalt-containing ammoniacal solution was prepared by dissolving cobalt in an ammonia-ammonium carbonate system. Excess air was introduced during the preparation process, resulting in a cobalt concentration of 5.26 g / L in the form of a trivalent cobalt-ammonia complex. 300 mL of the solution was placed in a 1 L sealed pressure vessel, and one reaction equivalent of ascorbic acid was added as a reducing agent. The mixture was heated to 160 °C and held at this temperature for 0.5 h. Solid-liquid separation was then performed, with a cobalt recovery rate of 99.08%. The resulting solid was a mixture of cobalt tetroxide and cobalt carbonate, with a particle size of 1-2.5 μm, a cobalt content of 60.19%, a carbon content of 3.31%, and a nitrogen content of less than 0.01%.

[0065] Examples 1-5 demonstrate that the method of this invention can efficiently recover cobalt from ammoniacal solutions while directly preparing high-value-added cobalt tetroxide and / or cobalt carbonate products. A cobalt-containing ammoniacal solution with a cobalt concentration ≥0.5 g / L is placed in a closed pressure vessel, with the temperature controlled at 120℃-210℃ and the reaction time at 0.5 h-6 h to produce cobalt tetroxide. Adding citric acid or tartaric acid during this process can produce cobalt carbonate, with the cobalt recovery rate consistently above 95%. In contrast, in Comparative Examples 1-3, when the cobalt concentration is below 0.5 g / L or the reaction time is outside the specified range, although a small amount of cobalt tetroxide can be obtained, the overall cobalt recovery rate is low. When the reaction temperature is below 120℃, not only is the cobalt recovery rate low, but cobalt tetroxide cannot be produced. In Comparative Example 4, using ascorbic acid as a reducing agent results in insignificant reduction, yielding a mixed product of cobalt tetroxide and cobalt carbonate, but failing to produce a single-component cobalt carbonate product.

[0066] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A process for the one-step production of a cobalt product from an ammonia- containing solution containing cobalt, characterized in that, The application relates to a method for preparing cobalt products, comprising the following steps: evaporating ammonia in a cobalt-containing ammonia solution in a closed container at a certain temperature under direct pressure, and then separating solid and liquid after evaporating for a certain time to obtain a cobalt tetraoxide product, wherein the cobalt-containing ammonia solution is selected from at least one of a divalent cobalt ammonia complex or a trivalent cobalt ammonia complex; and / or adding a proper amount of a reducing agent into the cobalt-containing ammonia solution, and then evaporating ammonia in the closed container at a certain temperature under direct pressure, and then separating solid and liquid after evaporating for a certain time to obtain a cobalt carbonate product, wherein the cobalt-containing ammonia solution is selected from a mixture of a divalent cobalt ammonia complex and a trivalent cobalt ammonia complex or a trivalent cobalt ammonia complex; air is introduced when the cobalt-containing ammonia solution is prepared; the cobalt concentration in the cobalt-containing ammonia solution is greater than or equal to 0.5 g / L; the pressure evaporation temperature for preparing the two products is 120 DEG C to 210 DEG C, and the reaction time is 0.5 h to 6 h; the cobalt-containing ammonia solution refers to a cobalt ammonia complex solution generated by reacting metal cobalt, a cobalt salt, cobalt-containing waste or cobalt-containing minerals with an ammonia-ammonium salt mixed solution; the ammonia-ammonium salt mixed solution is selected from at least one of ammonia water-ammonium carbonate or ammonia water-bicarbonate ammonium; the reducing agent is citric acid or tartaric acid, and the adding amount of the reducing agent is 0.8 times to 2 times of the reaction equivalent; when the reducing agent is tartaric acid, spherical cobalt carbonate is obtained; and when the reducing agent is citric acid, rock-like cobalt carbonate is obtained. ​ ​ ​ ​ ​ ​ 2. The method of claim 1, wherein, ​ 3. The method of claim 2, wherein, ​

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