A method for preparing a crude cobalt intermediate product from a cobalt-containing copper raffinate

Abstract

This invention relates to a method for preparing crude cobalt intermediate from cobalt-containing copper raffinate. The method includes the following steps: (1) adding a first precipitant to the cobalt-containing copper raffinate for neutralization and impurity removal, and obtaining a first precipitated liquid and a first precipitated residue after solid-liquid separation; (2) adding a second precipitant to the first precipitated liquid for cobalt precipitation, and obtaining a cobalt-precipitated liquid and a mixed precipitate after solid-liquid separation; (3) adding a leaching agent to the mixed precipitate for leaching, and obtaining a leachate and a leaching residue after solid-liquid separation; (4) adding a reducing agent to the leachate for reductive distillation, and obtaining crude cobalt intermediate and a reductive distillate after solid-liquid separation. This invention achieves efficient separation of cobalt from impurities such as copper, significantly improves the purity of crude cobalt intermediate and cobalt recovery rate, has a simple process flow, low reagent consumption, and is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of metallurgical separation technology, and in particular to a method for preparing crude cobalt intermediate from cobalt-containing copper raffinate. Background Technology

[0002] Cobalt, as an important strategic metal, is widely used in key areas such as power batteries for new energy vehicles, and market demand remains strong. Due to resource constraints, the domestic supply of cobalt raw materials is relatively insufficient, making a stable supply crucial for the industry's sustainable development. With the continuous development of the cobalt resource processing industry, higher requirements are being placed on the efficiency, low cost, and greening of the preparation processes for crude cobalt intermediates. Developing simple and controllable new cobalt recycling processes has significant engineering application value.

[0003] Currently, the main source of cobalt in the industry is the cobalt-containing copper raffinate obtained after copper extraction from copper-cobalt oxide ore through acid leaching and extraction. The mainstream processing technology adopts "wet leaching-extraction to remove copper-neutralization to remove iron, aluminum and manganese-magnesium oxide precipitation of cobalt-calcium oxide to remove magnesium". However, this process still has many shortcomings in actual industrial applications: limited impurity removal efficiency, relatively serious cobalt loss, difficulty in accurately controlling the amount of magnesium oxide added, high consumption of acid and alkali auxiliary materials, and the cobalt grade of the crude cobalt hydroxide intermediate product is generally low (usually 20-40%), with high contents of impurities such as Fe, Mn and Mg, which increases the difficulty of subsequent purification processing.

[0004] CN112626337A discloses a method of co-precipitating copper, zinc, cobalt, iron, and manganese ions using sulfides, followed by stepwise leaching of manganese, iron, and cobalt from the precipitate using sulfuric acid. The resulting cobalt-rich leaching solution is used to prepare crude cobalt hydroxide, which can increase the cobalt hydroxide grade to over 50%. However, the sulfidation method suffers from problems such as high reagent costs, the generation of harmful gases, the need for separate treatment of residual ions in the precipitate, and high acid consumption during secondary leaching, making it difficult to achieve large-scale industrial application. CN114959299A discloses a strategy of pre-removing impurities such as iron, aluminum, and zinc using phosphoric acid extractants, followed by cobalt extraction using hydroxyoxime extractants. However, the organic reagents used in the extraction method are expensive, resulting in large wastewater treatment volumes. Furthermore, considering the copper removal process in the front-end extractant, the process involves multiple different organic phase systems, which may cause mutual interference.

[0005] Existing technologies suffer from drawbacks such as complex processes, high cobalt loss, insufficient product grade and purity, high consumption of auxiliary materials, significant environmental pressure, and difficulty in stable industrial application. Therefore, how to efficiently, cost-effectively, and greenly prepare high-grade crude cobalt intermediates from cobalt-containing copper extraction residues and achieve process water recycling has become an urgent problem to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for preparing crude cobalt intermediates from cobalt-containing copper extraction residue. This method effectively overcomes the shortcomings of existing processes, such as high cobalt loss, low product grade, high impurity content, high auxiliary material consumption, complex process flow, and difficulty in recycling wastewater. By coupling neutralization and impurity removal, cobalt precipitation, deep impurity removal through ammonia leaching, and stepwise heating distillation, efficient separation of impurities is achieved, significantly improving the grade and purity of the crude cobalt intermediate. Simultaneously, the process water and intermediate materials are recycled. The process is simple, easy to operate and control, has low production costs, is environmentally friendly, and is suitable for industrial production.

[0007] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing crude cobalt intermediate from cobalt-containing copper extraction residue, the method comprising the following steps: (1) Add the first precipitant to the cobalt-containing copper raffinate for neutralization and impurity removal, and after solid-liquid separation, obtain the first precipitate liquid and the first precipitate residue; (2) Add a second precipitant to the first precipitate solution to precipitate cobalt, and after solid-liquid separation, obtain the cobalt precipitate solution and the mixed precipitate; (3) The mixed precipitate is added to the leaching agent for leaching, and after solid-liquid separation, leaching solution and leaching residue are obtained; (4) Add a reducing agent to the leachate for reduction distillation, and after solid-liquid separation, obtain crude cobalt intermediate and reduction distillation liquid.

[0008] This invention utilizes the synergistic effects of stepwise neutralization and impurity removal, cobalt precipitation, selective leaching, reductive distillation for cobalt enrichment, and oxidative distillation for copper enrichment. First, neutralization and impurity removal removes most of the iron, aluminum, and other impurities from the cobalt-containing copper raffinate, significantly reducing the amount of slag during the cobalt precipitation leaching process. Then, cobalt precipitation achieves efficient cobalt enrichment. Subsequently, selective leaching transfers cobalt into the liquid phase in ionic form, allowing impurities such as calcium, magnesium, and manganese to remain stably in the slag, achieving deep separation of cobalt from impurities. Finally, a reducing agent reduces trivalent cobalt, causing cobalt to precipitate and copper ions to remain in the reductive distillation solution. The resulting crude cobalt intermediate has a high grade, low impurity content, high cobalt recovery rate, low reagent consumption, a simple process flow, and stable and controllable operation.

[0009] The present invention does not limit the solid-liquid separation described herein, and any method known to those skilled in the art for solid-liquid separation may be used, such as filtration, sedimentation or centrifugation.

[0010] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0011] As a preferred technical solution of the present invention, the cobalt-containing copper raffinate in step (1) contains, in addition to cobalt ions, any one or at least two of the following: calcium ions, magnesium ions, iron ions, aluminum ions, copper ions, zinc ions, manganese ions, and silicon ions.

[0012] Preferably, the first precipitant comprises any one or a combination of at least two of calcium carbonate, magnesium carbonate, calcium oxide, and magnesium oxide.

[0013] Preferably, the proportion of the first precipitant with a particle size of -0.074 mm is 50-70%, for example, it can be 50%, 55%, 60%, 65% or 70%.

[0014] Preferably, the first precipitant is pre-mixed with a dispersing solvent to form a slurry with a mass concentration of 10-30%, for example, it can be 10%, 15%, 20%, 25% or 30%, etc.

[0015] This invention achieves acid neutralization and selective removal of iron and aluminum impurities under mild conditions, effectively avoiding co-precipitation loss of cobalt ions; controlling the particle size of the first precipitant increases the reaction contact area, improving the neutralization and impurity removal rate and reaction sufficiency; pre-mixing the first precipitant into a slurry achieves uniform dispersion and precise addition of the reagent, avoiding local over-alkaliness leading to cobalt entrainment and loss, making the reaction process more stable and controllable.

[0016] Preferably, the neutralization and impurity removal temperature is 25~50℃, for example, it can be 25℃, 30℃, 35℃, 40℃, 45℃ or 50℃, etc.

[0017] Preferably, stirring is performed during the neutralization and impurity removal process for 0.5 to 4 hours, for example, 0.5 hours, 1 hour, 2 hours, 3 hours, or 4 hours.

[0018] Preferably, the endpoint pH of the neutralization and impurity removal is 3 to 4, such as 3.0, 3.2, 3.5, 3.8 or 4.0, which can efficiently remove impurities while avoiding hydrolysis and co-precipitation of cobalt ions, reducing the loss of cobalt in the impurity removal stage and improving the overall recovery rate of cobalt.

[0019] As a preferred technical solution of the present invention, the second precipitant in step (2) includes sodium carbonate or sodium bicarbonate.

[0020] Preferably, the reaction temperature for cobalt deposition is 25~100℃, for example, it can be 25℃, 40℃, 60℃, 80℃ or 100℃.

[0021] Preferably, the cobalt precipitation process involves stirring for 0.5 to 4 hours, for example, 0.5 hours, 1 hour, 2 hours, 3 hours, or 4 hours.

[0022] Preferably, the final pH of the cobalt precipitation is 8 to 9, for example, it can be 8, 8.2, 8.5, 8.8 or 9.

[0023] As a preferred technical solution of the present invention, a third precipitant is added to the cobalt-precipitated liquid in step (2) for purification, and the solid-liquid separation yields the third precipitate residue and the purified liquid.

[0024] Preferably, the third precipitant comprises calcium oxide.

[0025] Preferably, the proportion of the third precipitant with a particle size of -0.045mm is 60-90%, for example, it can be 60%, 70%, 80%, 85% or 90%.

[0026] Preferably, the endpoint pH of the purification is 10-11, such as 10.0, 10.2, 10.5, 10.8 or 11.0.

[0027] Preferably, the third precipitant is pre-mixed with a dispersing solvent to form a slurry with a mass concentration of 10-30%, for example, it can be 10%, 15%, 20%, 25% or 30%, etc.

[0028] As a preferred technical solution of the present invention, the third precipitate is returned to step (1) to assist in the neutralization and impurity removal. Since the third precipitate contains calcium carbonate generated by removing carbonate ions from calcium oxide, its alkalinity can be fully utilized to replace part of the fresh neutralizing agent, reduce the consumption of auxiliary materials, realize the resource utilization of solid waste and the closed-loop circulation of materials, and improve the economic efficiency and environmental protection level of the process.

[0029] Preferably, the purified liquid is returned to the copper-cobalt ore leaching process or used as a dispersion solvent for the slurry.

[0030] As a preferred technical solution of the present invention, the leaching agent in step (3) is a mixed solution of ammonia water and ammonium carbonate solution and / or ammonium bicarbonate solution.

[0031] Preferably, the solid-liquid ratio of the leaching is 1:(1~10)g / mL, for example, it can be 1:1, 1:3, 1:5, 1:8 or 1:10, etc.

[0032] Preferably, the free NH3 concentration of the leaching agent is 100~150g / L, and the CO2 concentration is 25~50g / L. For example, the free NH3 concentration can be 100g / L, 120g / L, or 150g / L, etc.; the CO2 concentration can be 25g / L, 30g / L, 35g / L, 40g / L, or 50g / L, etc.

[0033] In this invention, the CO2 concentration in the leaching agent refers to the total concentration expressed as CO2 when the sum of carbonate and bicarbonate ions in the solution is converted into CO2.

[0034] Preferably, the leaching temperature is 25~60℃, for example, it can be 25℃, 35℃, 45℃, 55℃ or 60℃, etc., and the leaching process is stirred for 0.5~4h, for example, it can be 0.5h, 1h, 2h, 3h or 4h.

[0035] As a preferred technical solution of the present invention, the reducing agent in step (4) includes copper powder.

[0036] Preferably, the reducing agent has a particle size of -0.074 mm accounting for 60-80%, for example, it can be 60%, 65%, 70%, 75% or 80%, etc.

[0037] Preferably, the amount of reducing agent added is 1 to 10% of the molar amount of cobalt ions in the leachate, for example, it can be 1%, 3%, 5%, 8% or 10%, etc.

[0038] Preferably, the temperature of the reductive distillation is 50~100℃, for example, it can be 50℃, 65℃, 80℃, 90℃ or 100℃.

[0039] Preferably, the reductive distillation process is stirred for 0.5 to 4 hours, for example, 0.5 hours, 1 hour, 2 hours, 3 hours or 4 hours.

[0040] Preferably, the concentration of free NH3 at the end of the reducing distillation process is 5~10 g / L, for example, it can be 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L or 10 g / L, etc.

[0041] This invention uses copper powder as a reducing agent, which can selectively reduce [Co(NH3)6] in an ammoniacal system. 3+ The addition of trivalent cobalt ions enables the separation of cobalt from impurities such as copper. The added copper powder is in the form of [Cu(NH3)2]. 2+ and [Cu(NH3)2] + The form remains in the reducing distillate, without introducing new impurities, further improving cobalt recovery and product purity.

[0042] As a preferred technical solution of the present invention, the reducing distillation liquid in step (4) is added to an oxidant for oxidative distillation, and after solid-liquid separation, copper-enriched slag and oxidative distillation liquid are obtained.

[0043] This invention utilizes oxidative distillation by adding an oxidant to the reducing distillate, thereby removing [Cu(NH3)2] from the solution. + Full oxidation and precipitation yield copper-enriched slag, enabling copper recycling and further improving resource recovery rate.

[0044] Preferably, the copper enrichment slag is returned to the copper-cobalt ore leaching process.

[0045] Preferably, the oxidative distillate is returned to step (3) as an extractant.

[0046] The present invention returns the liquid after oxidative distillation to step (3) as a leaching agent, which can reuse the effective components such as ammonium ions in the solution, reduce the amount of fresh leaching agent added, and reduce production costs.

[0047] Preferably, the gas produced by the reduction distillation and oxidative distillation is introduced into the leaching system in step (3).

[0048] This invention introduces the gas generated during reduction distillation and oxidative distillation into the leaching system, which can recover the ammonia component in the gas, realize the recycling of ammonia resources, reduce tail gas emissions, and balance process economy and environmental protection, further improving the material recycling system.

[0049] Preferably, the concentration of free NH3 at the end of the oxidative distillation process is 1~2 g / L, for example, it can be 1.0 g / L, 1.2 g / L, 1.4 g / L, 1.6 g / L, 1.8 g / L or 2.0 g / L.

[0050] As a preferred embodiment of the present invention, the oxidant includes any one of air, oxygen, hydrogen peroxide, or ammonium persulfate.

[0051] Preferably, the amount of oxidant added is 0.1% to 5% of the molar amount of copper in the reduced distillate, for example, it can be 0.1%, 0.5%, 1%, 3% or 5%.

[0052] As a preferred technical solution of the present invention, when the oxidant is a gaseous oxidant, the effective oxygen meter flow rate is 0.1~1.0L / min, for example, it can be 0.1L / min, 0.2L / min, 0.5L / min, 0.8L / min or 1.0L / min, etc.

[0053] Compared with the prior art, the present invention has at least the following beneficial effects: (1) This invention avoids the problems of severe cobalt loss and high impurity content in traditional processes by using stepwise neutralization and impurity removal, selective cobalt precipitation and reducing distillation processes. It greatly improves the purity of crude cobalt products, reduces impurity content, solves the problems of low product grade and high loss in existing processes, effectively improves product quality and recovery rate, and can achieve a cobalt recovery rate of over 95%. The content of impurities such as manganese, iron, aluminum, calcium, magnesium, silicon and copper is controlled below 0.5wt%, and the cobalt content of crude cobalt intermediate is over 41%. (2) Through process integration design, the present invention enables the step-by-step recycling of sediment and wastewater, reduces the consumption of fresh reagents and water resources, avoids the generation of harmful gases, and realizes the resource recovery of solid waste and waste gas, which reduces the cost of auxiliary materials and reduces pollutant emissions, meeting the requirements of green production. (3) The process of the present invention is simple and easy to control, suitable for industrial production, without the need for a complex extraction and separation system, with simple operation process, easy parameter control, and strong equipment adaptability. It solves the problems of complex operation and difficulty in control of existing processes, facilitates large-scale production, and improves process stability and production efficiency. Attached Figure Description

[0054] Figure 1 This is a flowchart of a method for preparing crude cobalt intermediates from cobalt-containing copper raffinate according to a specific embodiment of the present invention. Detailed Implementation

[0055] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0056] This invention provides a method for preparing crude cobalt intermediates from cobalt-containing copper extraction residue, such as... Figure 1 As shown, it includes the following steps: (1) The first precipitant is slowly added to the cobalt-containing copper raffinate to neutralize and remove impurities, and the raffinate is filtered to obtain the first precipitate liquid and the first precipitate residue; (2) Add the second precipitant to the first precipitate solution to precipitate cobalt, and filter to obtain the cobalt-precipitated solution and the mixed precipitate; (3) The third precipitant is slowly added to the obtained cobalt precipitate solution for purification. The third precipitate residue and the purified solution are obtained by filtration. The purified solution can be returned to the copper-cobalt ore leaching process, and the third precipitate residue is returned to step (1) to neutralize excess acid. (4) The resulting mixed precipitate is leached with a leaching agent, and filtered to obtain leaching solution and leaching residue. Steps (3) and (4) are not distinguished by their order. (5) The obtained leachate is added to a reducing agent for reduction distillation, filtered to obtain crude cobalt intermediate and reduction distillate, and the gas is collected and returned to the leaching process in step (4); (6) The obtained reduced distillation liquid is added to the oxidant for oxidative distillation, filtered and separated to obtain copper enrichment slag and oxidative distillation liquid. The copper enrichment slag is returned to the copper-cobalt ore leaching process to recover copper, and the oxidative distillation liquid is returned to the leaching process of step (4) as a leaching agent. The gas is collected and returned to the leaching process of step (4).

[0057] The composition of the cobalt-containing copper raffinate used in the following examples and comparative examples is shown in Table 1.

[0058] Table 1 Example 1 This embodiment provides a method for preparing crude cobalt intermediate from cobalt-containing copper extraction residue, the method comprising the following steps: (1) Slowly add calcium carbonate slurry with a mass concentration of 28% to the cobalt-containing copper raffinate, with -0.074mm accounting for 70%, stir at 25℃ for 4h, control the final pH to 3.8, filter to obtain the first precipitate liquid and the first precipitate residue, with a cobalt loss rate of <0.02% in the solution; (2) Sodium carbonate was added to the first precipitate solution and stirred at 50°C for 2 hours. The pH was controlled to be 8.5 at the end point to precipitate cobalt ions. The cobalt precipitate solution and mixed precipitate were obtained by filtration. The cobalt precipitation rate reached 99.95%. (3) Slowly add calcium oxide slurry to the cobalt precipitate solution with a mass concentration of 18% and -0.045mm accounting for 85%. Stir at 30℃ for 4 hours. The final pH is controlled at 11.0. Filter to obtain the third precipitate residue and the purified solution. The purified solution can be returned to the copper-cobalt ore leaching process. The third precipitate residue is returned to step (1) to neutralize excess acid. (4) The obtained mixed precipitate was added to the ammonium carbonate-ammonia mixed solution (NH3 concentration of 100g / L and CO2 concentration of 45g / L) at a solid-liquid ratio of 1:5 g / mL, and leached at 60℃ for 1h. The leachate and leaching residue were obtained by filtration. The cobalt leaching rate was 99.52%. The order of steps (3) and (4) is not important. (5) Copper powder was added to the obtained leachate at 1% of the molar amount of cobalt ions, and -0.074mm accounted for 70%. The mixture was stirred and distilled at 80℃ for 3 hours. The final NH3 concentration was 7.2g / L. Then, the crude cobalt intermediate and the reduced distillate were separated by filtration. The main dry basis components of the crude cobalt intermediate are shown in Table 2. The cobalt recovery rate was 95.82%. The gas was collected and returned to the leaching process in step (4). (6) The obtained reduced distillate was stirred and distilled for 3 hours at 60°C until the final NH3 concentration was 1.2 g / L. During this period, oxygen-enriched air was introduced at a flow rate of 500 mL / min. The copper enrichment slag and the oxidized distillate were separated by filtration. The copper enrichment slag was returned to the copper-cobalt ore leaching process to recover copper, and the oxidized distillate was returned to the leaching process in step (4). The gas was collected and returned to the leaching process in step (4).

[0059] Table 2 Example 2 This embodiment provides a method for preparing crude cobalt intermediate from cobalt-containing copper extraction residue, the method comprising the following steps: (1) Slowly add calcium carbonate slurry with a mass concentration of 25% to the cobalt-containing copper raffinate, with -0.074mm accounting for 70%, stir at 35℃ for 2 hours, control the final pH to 3.5, filter to obtain the first precipitate liquid and the first precipitate residue, with a cobalt loss rate of <0.01% in the solution; (2) Sodium carbonate was added to the first precipitate solution and stirred at 60°C for 2 hours. The pH was controlled to be 8.9 at the end point to precipitate cobalt ions. The cobalt precipitate solution and mixed precipitate were obtained by filtration. The cobalt precipitation rate reached 99.98%. (3) Slowly add calcium oxide slurry to the cobalt precipitate solution with a mass concentration of 25% and -0.045mm accounting for 80%. Stir at 45℃ for 3 hours. The final pH is controlled at 10.9. Filter to obtain the third precipitate residue and the purified solution. The purified solution can be returned to the copper-cobalt ore leaching process. The third precipitate residue is returned to step (1) to neutralize excess acid. (4) The obtained mixed precipitate was added to an ammonium carbonate-ammonia mixed solution (NH3 concentration of 120 g / L and CO2 concentration of 35 g / L) at a solid-liquid ratio of 1:4 g / mL, and leached at 50°C for 1 h. The leachate and leaching residue were obtained by filtration. The cobalt leaching rate was 99.65%. The order of steps (3) and (4) is not important. (5) Copper powder was added to the obtained leachate at 5% of the molar amount of cobalt ions, and -0.074mm accounted for 65%. The mixture was stirred and distilled at 90℃ for 2 hours. The final NH3 concentration was 8.5g / L. The crude cobalt intermediate and the reduced distillate were then separated by filtration. The main dry basis components of the crude cobalt intermediate are shown in Table 3. The cobalt recovery rate was 96.56%. The gas was collected and returned to the leaching process in step (4). (6) The obtained reduced distillate was stirred and distilled at 80°C for 2 hours. During this period, oxygen-enriched air was introduced at a flow rate of 600 mL / min. The final NH3 concentration was 1.0 g / L. The copper enrichment slag and the oxidized distillate were separated by filtration. The copper enrichment slag was returned to the copper-cobalt ore leaching process to recover copper. The oxidized distillate was returned to the leaching process in step (4). The gas was collected and returned to the leaching process in step (4).

[0060] Table 3 Example 3 This embodiment provides a method for preparing crude cobalt intermediate from cobalt-containing copper extraction residue, the method comprising the following steps: (1) Slowly add calcium oxide slurry with a mass concentration of 30% to the cobalt-containing copper raffinate, with -0.074mm accounting for 60%, stir at 30℃ for 2h, control the final pH to 4.0, filter to obtain the first precipitate liquid and the first precipitate residue, with a cobalt loss rate of <0.01% in the solution; (2) Sodium carbonate was added to the first precipitate solution and stirred at 100℃ for 2 hours. The pH was controlled to be 8.0 at the end point to precipitate cobalt ions. The cobalt precipitate solution and mixed precipitate were obtained by filtration. The cobalt precipitation rate reached 99.88%. (3) Slowly add calcium oxide slurry to the cobalt precipitate solution with a mass concentration of 15% and -0.045mm accounting for 90%. Stir at 55℃ for 3 hours. The final pH is controlled at 11.0. Filter to obtain the third precipitate residue and the purified solution. The purified solution can be returned to the copper-cobalt ore leaching process. The third precipitate residue is returned to step (1) to neutralize excess acid. (4) The obtained mixed precipitate was added to the ammonium carbonate-ammonia mixed solution (NH3 concentration of 125 g / L and CO2 concentration of 50 g / L) at a solid-liquid ratio of 1:6 g / mL, and stirred and leached at 45°C for 1 h. The leachate and leaching residue were obtained by filtration. The cobalt leaching rate was 99.28%. The order of steps (3) and (4) is not important. (5) Copper powder was added to the obtained leachate at 10% of the molar amount of cobalt ions, and -0.074mm accounted for 60%. The mixture was stirred and distilled at 100℃ for 3 hours. The final NH3 concentration was 5.3g / L. The crude cobalt intermediate and the reduced distillate were then separated by filtration. The main dry components of the crude cobalt intermediate are shown in Table 4. The cobalt recovery rate was 97.21%. The gas was collected and returned to the leaching process in step (4). (6) The obtained reduced distillate was stirred and distilled at 85°C for 2 hours. During this period, oxygen-enriched air was introduced at a flow rate of 650 mL / min. The final NH3 concentration was 1.8 g / L. The copper enrichment slag and the oxidized distillate were separated by filtration. The copper enrichment slag was returned to the copper-cobalt ore leaching process to recover copper. The oxidized distillate was returned to the leaching process in step (4). The gas was collected and returned to the leaching process in step (4).

[0061] Table 4 Example 4 This embodiment provides a method for preparing crude cobalt intermediate from cobalt-containing copper raffinate. Except for step (5), where the amount of copper powder added is 12% of the molar amount of cobalt ions, the rest is the same as in Example 1. In this embodiment, the copper content of the crude cobalt intermediate increases from 0.21 wt% in Example 1 to 0.79 wt%, and the cobalt recovery rate is 97.36%.

[0062] Comparative Example 1 This comparative example provides a method for preparing crude cobalt intermediate from cobalt-containing copper leaching residue. Except for step (5) where copper powder is not added, the rest is the same as in Example 1. In this comparative example, some cobalt ions in the leaching solution are oxidized to trivalent and exist in the leaching solution in a stable complex state. The cobalt recovery rate is 90.54%.

[0063] Comparative Example 2 This comparative example uses the mainstream processing technology: neutralization to remove iron, aluminum, and manganese - magnesium oxide precipitation of cobalt - calcium oxide removal of magnesium to prepare crude cobalt hydroxide intermediate, including the following steps. (1) Iron removal: Add seed crystals and limestone slurry, CaCO3 mass concentration is 28%, -0.074mm accounts for 70%; introduce compressed air and sulfur dioxide mixed gas, SO2 volume concentration is 2.5%, pressure is 0.5MPa; reaction temperature: 25~35℃; reaction time: 6h; control the endpoint pH to 4.2, filter to remove all iron and aluminum impurity ions and most manganese ions; (2) Copper removal: Lime slurry was added to the filtrate from step (1): CaO mass concentration was 14%, -0.045mm accounted for 85%; reaction temperature: 30℃; reaction time: 4h; endpoint pH was 5.2, and copper was removed by filtration after the reaction; (3) Cobalt precipitation: Magnesium oxide slurry was added to the filtrate from step (2): MgO mass concentration was 10%, -0.045mm accounted for 85%; the endpoint pH was 8.2; the reaction temperature was 30℃; the reaction time was 5h. The dry basis of the crude cobalt intermediate obtained by filtration is shown in Table 5. The cobalt recovery rate was 94.68%. (4) Magnesium removal: Add calcium oxide slurry to the filtrate from step (3): CaO mass concentration is 14%, -0.045mm accounts for 85%; endpoint pH is 11; reaction temperature: 30℃; reaction time: 2.5h.

[0064] Table 5 (1) As can be seen from Examples 1 to 3, the present invention first uses calcium carbonate or calcium oxide to pre-neutralize the cobalt-containing copper raffinate, removes impurities such as iron and aluminum under the premise of low cobalt loss, then uses sodium carbonate to achieve efficient precipitation of cobalt, and then uses ammonium carbonate to selectively leach cobalt with ammonia complexation, thereby separating cobalt from most impurities. During the distillation process, copper powder is used to reduce and inhibit the formation of trivalent cobalt complexes and to synergistically evaporate ammonia to precipitate cobalt. At the same time, oxygen-enriched oxidation is used to recover copper and realize system circulation. This invention can achieve the technical effects of cobalt recovery rate greater than 95%, low cobalt loss, high cobalt grade of crude cobalt intermediate product, low impurity content, and closed-loop process circulation.

[0065] (2) As can be seen from Examples 1 and 4, by controlling the amount of copper powder added within a reasonable range, the present invention can both inhibit the oxidation of cobalt ions into stable and difficult-to-decompose trivalent cobalt ammonia complex, ensuring sufficient cobalt precipitation, and avoid excessive introduction of copper impurities into the product; while when the amount of copper powder added is excessive, the copper content of crude cobalt intermediate product will increase significantly.

[0066] (3) As can be seen from Example 1 and Comparative Examples 1 and 2, the present invention, by adding a reducing agent in the distillation step and combining selective leaching of ammonium carbonate with stepwise impurity removal process design, can both inhibit cobalt ion oxidation and ensure cobalt full precipitation to improve yield, and achieve deep separation of cobalt from various impurities to improve product grade; when no reducing agent is added, some cobalt remains in the solution in the form of stable trivalent complex, and cobalt cannot be efficiently recovered, and the cobalt recovery rate drops to 90.54%; when the traditional neutralization precipitation process is used, impurities and cobalt coprecipitate severely, cobalt grade is low and impurity content is high, and cobalt cannot be efficiently recovered and deeply removed.

[0067] In summary, this invention achieves efficient separation of cobalt from impurities through a comprehensive technical solution involving pre-neutralization and impurity removal, sodium carbonate precipitation of cobalt, selective leaching of ammonium carbonate, copper powder reduction and synergistic distillation precipitation of cobalt, oxygen-enriched oxidation recovery of copper, and closed-loop system circulation. This results in high cobalt recovery rate, low cobalt loss rate, high grade of crude cobalt intermediate, and low impurity content.

[0068] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing crude cobalt intermediate from cobalt-containing copper raffinate, characterized in that, The method includes the following steps: (1) Add the first precipitant to the cobalt-containing copper raffinate for neutralization and impurity removal, and after solid-liquid separation, obtain the first precipitate liquid and the first precipitate residue; (2) Add a second precipitant to the first precipitate solution to precipitate cobalt, and after solid-liquid separation, obtain the cobalt precipitate solution and the mixed precipitate; (3) The mixed precipitate is added to the leaching agent for leaching, and after solid-liquid separation, leaching solution and leaching residue are obtained; (4) Add a reducing agent to the leachate for reduction distillation, and after solid-liquid separation, crude cobalt intermediate and reduction distillation liquid are obtained.

2. The method according to claim 1, characterized in that, In step (1), the cobalt-containing copper raffinate contains, in addition to cobalt ions, any one or at least two of the following: calcium ions, magnesium ions, iron ions, aluminum ions, copper ions, zinc ions, manganese ions, and silicon ions. Preferably, the first precipitant comprises any one or a combination of at least two of calcium carbonate, magnesium carbonate, calcium oxide, and magnesium oxide; Preferably, the proportion of particles with a size of -0.074 mm in the first precipitant is 50-70%; Preferably, the first precipitant is pre-mixed with a dispersing solvent to form a slurry with a mass concentration of 10-30%; Preferably, the temperature for neutralization and impurity removal is 25~50℃; Preferably, the endpoint pH for neutralization and impurity removal is 3-4.

3. The method according to claim 1 or 2, characterized in that, Step (2) The second precipitant includes sodium carbonate or sodium bicarbonate; Preferably, the reaction temperature for cobalt deposition is 25~100℃; Preferably, the final pH of the cobalt precipitation is 8-9.

4. The method according to any one of claims 1 to 3, characterized in that, In step (2), a third precipitant is added to the cobalt-precipitated liquid for purification, and the solid and liquid are separated to obtain the third precipitate residue and the purified liquid. Preferably, the third precipitant comprises calcium oxide; Preferably, the proportion of the third precipitant with a particle size of -0.045 mm is 60-90%; Preferably, the endpoint pH of the purification is 10-11; Preferably, the third precipitant is pre-mixed with a dispersing solvent to form a slurry with a mass concentration of 10-30%.

5. The method according to claim 4, characterized in that, The third precipitate is returned to step (1) to assist in the neutralization and impurity removal; Preferably, the purified liquid is returned to the copper-cobalt ore leaching process or used as a dispersion solvent for the slurry.

6. The method according to any one of claims 1 to 5, characterized in that, The leaching agent in step (3) is a mixed solution of ammonia water and ammonium carbonate solution and / or ammonium bicarbonate solution; Preferably, the solid-liquid ratio of the leaching is 1:(1~10)g / mL; Preferably, the free NH3 concentration of the leachate is 100~150 g / L, and the CO2 concentration is 25~50 g / L; Preferably, the leaching temperature is 25~60℃, and the leaching process is stirred for 0.5~4h.

7. The method according to any one of claims 1 to 6, characterized in that, The reducing agent in step (4) includes copper powder; Preferably, the reducing agent has a particle size of -0.074 mm accounting for 60-80%; Preferably, the amount of reducing agent added is 1-10% of the molar amount of cobalt ions in the leachate; Preferably, the temperature of the reductive distillation is 50~100℃, and the final free NH3 concentration is 5~10g / L.

8. The method according to any one of claims 1 to 7, characterized in that, In step (4), the reduced distillation liquid is added to an oxidant for oxidative distillation. After solid-liquid separation, copper-enriched residue and oxidative distillation liquid are obtained. Preferably, the copper enrichment slag is returned to the copper-cobalt ore leaching process; Preferably, the oxidative distillate is returned to step (3) as an extractant; Preferably, the gas produced by the reduction distillation and oxidative distillation is introduced into the leaching system in step (3).

9. The method according to claim 8, characterized in that, The oxidant includes any one of air, oxygen, hydrogen peroxide, or ammonium persulfate; Preferably, the amount of oxidant added is 0.1-5% of the molar amount of copper in the reduced distillate; Preferably, the concentration of free NH3 at the end of the oxidative distillation process is 1~2 g / L.

10. The method according to claim 9, characterized in that, When the oxidant is a gaseous oxidant, the effective oxygen meter flow rate is 0.1~1.0L / min.

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