A method for recovering copper metal by atmospheric oxygen-enriched leaching

Abstract

This invention provides a method for recovering metallic copper by atmospheric pressure oxygen-enriched leaching, relating to the field of hydrometallurgy. The method includes: mixing copper sulfide concentrate with a sulfuric acid solution to obtain a mixed slurry; introducing an oxygen-rich gas under atmospheric pressure to carry out a leaching reaction; and after the reaction, separating the liquid and solid to obtain a copper-containing leachate. By using the synergistic leaching of sulfuric acid solution and oxygen-rich gas under atmospheric pressure, this method eliminates the reliance on expensive high-pressure equipment, removes the safety hazards of high-pressure explosions, and significantly reduces equipment corrosion and investment costs. Using oxygen as a highly efficient oxidant, this method significantly shortens the extraction cycle, overcomes the drawbacks of time-consuming bioleaching and the generation of waste, and achieves efficient, safe, and low-cost extraction of metallic copper from copper sulfide concentrate.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgy, and more specifically, to a method for recovering metallic copper by atmospheric pressure oxygen-enriched leaching. Background Technology

[0002] The smelting and extraction of copper concentrate typically includes pyrometallurgical processes and hydrometallurgical processes. Among them, hydrometallurgical processes are often used for low-grade copper concentrates. They can not only process complex ores under relatively mild conditions, but also avoid to some extent the waste gas emission problems generated in traditional high-temperature smelting processes. It is currently an important technical route for processing various complex or low-grade copper-bearing minerals.

[0003] As mining depth increases, copper-bearing ores gradually transform into mixed ores. Typically, copper sulfide concentrate needs to be separated through methods such as flotation, and after pretreatment such as roasting, it enters a hydrometallurgical system for copper leaching. Currently, hydrometallurgical processes for copper sulfide minerals mainly include pressure leaching, bioleaching, and high-temperature, high-pressure oxygen leaching. These methods aim to disrupt the structure of copper-bearing minerals through different chemical or biological reaction environments, thereby releasing metallic copper ions into the solution for subsequent extraction.

[0004] However, existing processing technologies have many limitations in practical applications. First, in conventional flotation and pretreatment stages, due to limitations in mineral distribution and reaction conversion rates, some copper sulfide minerals are still difficult to extract effectively using conventional processes, resulting in residual copper resources that are difficult to recover in the final leaching residue. Second, existing pressure leaching or oxygen pressure leaching processes often rely on extreme reaction conditions of high temperature and high pressure. This not only places stringent requirements on the corrosion resistance and pressure-bearing capacity of equipment such as reactors, but also the introduction of high concentrations of oxidizing gases in a closed pressurized environment can easily exacerbate equipment corrosion and even pose significant production safety risks. Furthermore, while bioleaching processes reduce the requirements for reaction conditions to some extent, their leaching reaction cycles are usually extremely long, resulting in low overall extraction efficiency, and often producing waste byproducts that are difficult to dispose of properly after the reaction.

[0005] In summary, existing hydrometallurgical processes for copper concentrates struggle to simultaneously achieve high processing rates and ideal metal extraction rates while ensuring production safety and equipment lifespan. The widespread application of conventional processes is severely limited by extreme pressurized operating conditions or inefficient reaction kinetics. Therefore, there is an urgent need in this field to find a new process that can be carried out under relatively mild atmospheric pressure, while also offering high operational safety, low equipment wear, and efficient and rapid leaching of metallic copper.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a method for atmospheric pressure oxygen-enriched leaching and recovery of metallic copper. This method utilizes the synergistic oxidation effect of sulfuric acid solution and oxygen-rich gas under atmospheric pressure to achieve efficient, low-cost, and extremely safe leaching and recovery of metallic copper from copper sulfide concentrate.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a method for recovering metallic copper by atmospheric pressure oxygen-enriched leaching, comprising: Copper sulfide concentrate is added to a sulfuric acid solution and mixed to obtain a mixed slurry; Under normal pressure, an oxygen-rich gas is introduced into the mixture slurry to carry out a leaching reaction; After the leaching reaction is completed, liquid-solid separation is performed to obtain a copper-containing leachate that can be used to recover metallic copper.

[0009] In an optional embodiment, the initial concentration of the sulfuric acid solution is 100 g / L to 400 g / L; and / or, The copper sulfide concentrate has a particle size of less than 0.074 mm; and / or, In the mixed slurry, the liquid-to-solid ratio is (3~10):1.

[0010] In an optional embodiment, the oxygen concentration in the oxygen-rich gas is 70% to 99.99%.

[0011] In an optional embodiment, the leaching reaction temperature is 70°C to 95°C; and / or, The leaching time for the leaching reaction is 6h to 12h.

[0012] In an optional embodiment, the oxygen-rich gas is introduced into the mixed slurry through a gas distribution pipe.

[0013] In an optional embodiment, the oxygen-rich gas is introduced at a flow rate of 0.7 L / min to 1.2 L / min; and / or, The leaching reaction is carried out under stirring conditions, with a stirring speed of 300 rpm to 600 rpm.

[0014] In an optional embodiment, the copper sulfide concentrate comprises a leaching residue flotation concentrate obtained by leaching and residue flotation of copper oxide concentrate.

[0015] In an optional embodiment, the step of using the copper-containing leachate to recover metallic copper includes: preparing electrowinning copper by passing the copper-containing leachate through an extraction-electrowinning process.

[0016] In an optional embodiment, the copper-containing compound in the copper sulfide concentrate includes at least one of CuFeS2, CuS, and Cu2S.

[0017] In an optional embodiment, the copper sulfide concentrate is a copper-cobalt sulfide concentrate; the copper-containing leachate also contains leached cobalt ions.

[0018] Compared to existing technologies, this invention, by conducting the leaching reaction under normal pressure, completely eliminates the heavy reliance on high-temperature and high-pressure specialized equipment required by traditional pressure leaching or oxygen pressure leaching processes. This change not only significantly reduces the initial investment and subsequent maintenance costs of equipment such as reaction vessels, but also effectively avoids the severe corrosion problems caused by the introduction of strong oxidizing gases into a high-pressure confined space. More importantly, normal pressure operation fundamentally eliminates the risk of explosion under extreme operating conditions, greatly improving the safety factor of the actual production process.

[0019] The synergistic effect of sulfuric acid solution and oxygen-rich gas provides a highly efficient reaction kinetic environment for processing difficult-to-dissolve copper sulfide concentrate. The oxygen-rich gas, acting as a powerful oxidant, continuously disrupts the stable crystal structure of copper sulfide minerals in an acidic medium, prompting the rapid release and dissolution of difficult-to-extract metallic copper in ionic form into the solution. Compared to traditional bioleaching processes, this method significantly shortens the leaching cycle, greatly improves production extraction efficiency, and avoids the generation of difficult-to-treat biological waste at the source.

[0020] By directly mixing copper sulfide concentrate into a pulp and operating under normal pressure with oxygen enrichment, the extraction bottleneck of conventional wet processes when processing low-grade or complex mixed ores is effectively overcome. The mild operating conditions and streamlined process enable deep extraction of copper minerals remaining after flotation or roasting pretreatment that are difficult to refine using conventional methods. This achieves maximum recovery of metal resources while ensuring low production costs, demonstrating excellent potential for large-scale industrial application. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic flowchart of the atmospheric pressure oxygen-enriched leaching recovery method for metallic copper in the embodiments of this application. Detailed Implementation

[0023] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0024] refer to Figure 1 This application provides a method for the atmospheric pressure oxygen-enriched leaching recovery of metallic copper, aiming to achieve efficient extraction of metallic copper from complex copper-bearing minerals (such as copper sulfide concentrates) by combining mild atmospheric pressure reaction conditions with an efficient oxidation system. The atmospheric pressure oxygen-enriched leaching recovery method for metallic copper includes: Step S1: Add copper sulfide concentrate to sulfuric acid solution and mix to obtain a mixed slurry.

[0025] First, the materials for the reaction system are prepared. Copper sulfide concentrate is added to a pre-prepared sulfuric acid solution and thoroughly mixed to obtain a uniformly distributed slurry. In this step, the sulfuric acid solution provides the necessary acidic environment for subsequent metal leaching. Since the copper-bearing minerals exist in solid particle form, mixing them with the sulfuric acid solution through physical means (such as stirring) to form a slurry maximizes the solid-liquid contact area, laying a good physical foundation for subsequent gas-liquid-solid three-phase mass transfer and chemical reactions. The copper sulfide concentrate can be a concentrate obtained from conventional flotation or a leaching residue flotation concentrate obtained from copper-bearing ore after pretreatment such as roasting.

[0026] Step S2: Under normal pressure, an oxygen-rich gas is introduced into the mixed slurry to carry out a leaching reaction.

[0027] Secondly, an atmospheric pressure oxygen-enriched leaching reaction is carried out. Under atmospheric pressure, an oxygen-rich gas is introduced into the prepared slurry mixture to initiate the leaching reaction. This step overcomes the limitation of existing technologies where copper sulfide minerals heavily rely on high temperature and high pressure (oxygen pressure leaching) to break down the mineral phase structure. From a thermodynamic perspective, under oxygen-enriched and acidic conditions, the standard Gibbs free energy of the oxidation of copper-containing compounds (such as CuFeS2, CuS, Cu2S, etc.) by oxygen is less than zero, and the reaction can proceed spontaneously.

[0028] In this embodiment, a high concentration of oxygen is introduced as a strong oxidant, compensating for the relatively low solubility of gases under normal pressure. Even in a mild, normal-pressure environment, it still provides a strong driving force for reaction kinetics, causing the mineral lattice to break down and allowing copper in the solid phase to rapidly dissolve into the acidic liquid phase in ionic form. This process effectively avoids the explosion hazards of a sealed, high-pressure reactor and the extreme corrosion problems caused by high oxygen concentrations, while significantly shortening the reaction cycle compared to bioleaching. In practical operation, the dispersion of bubbles and the efficiency of three-phase contact can be further enhanced by using microporous gas distribution, mechanical stirring, and providing suitable heating conditions.

[0029] Step S3: After the leaching reaction is completed, liquid-solid separation is performed to obtain a copper-containing leachate that can be used to recover metallic copper.

[0030] Finally, product separation and recovery are performed. After the above leaching reaction has fully proceeded and concluded, the reaction system undergoes liquid-solid separation treatment. Using conventional separation methods such as filtration or centrifugation, the solid residue carrying metal impurities is separated from the Cu-rich solid residue. 2+ The clarified liquid is physically stripped to obtain a copper-containing leachate that can be used for subsequent recovery of metallic copper. The obtained copper-containing leachate can be directly connected to the conventional extraction-electrowinning process in the field to prepare high-purity electrowinning copper products, thereby realizing a complete closed-loop recovery of copper resources.

[0031] From a chemical thermodynamic perspective, the ability of this invention to break the lattice constraints of copper sulfide minerals under normal pressure and mild temperatures is attributed to the synergistic effect of strong oxidation from high-concentration oxygen and an acidic medium. Specifically, the leaching reaction equations and their standard Gibbs free energies (ΔG°) for the main copper-containing compounds (chalcopyrite, covellite, chalcocite) in the system provided in this application are as follows: (1) CuFeS2+4H + +O2=Cu 2+ +Fe 2+ +2H2O+2S, ΔG6°=-160.6kJ / mol; (2) CuS + 2H + +0.5O2=Cu 2+ +H2O+S, ΔG7°=-118.0kJ / mol; (3) Cu2S + 4H + +O2=2Cu 2+ +2H2O+S, ΔG8°=-261.1kJ / mol.

[0032] The standard Gibbs free energy of the above reactions is less than zero, indicating that in an oxygen-rich sulfuric acid system, the oxidative dissociation process can proceed spontaneously thermodynamically for both primary and secondary copper sulfide minerals. This provides a solid theoretical basis for the efficient leaching of metallic copper under normal pressure in this invention.

[0033] In summary, by introducing sulfuric acid solution and oxygen-rich gas synergistically under normal pressure, copper sulfide concentrate slurry can be directly leached, completely eliminating the reliance on high-pressure specialized equipment used in traditional processes. This significantly reduces equipment investment and corrosion maintenance costs, and fundamentally eliminates the explosion hazards associated with high-pressure oxidation environments. Simultaneously, the oxygen-rich gas, acting as a highly efficient oxidant, significantly accelerates the destruction and dissolution rate of the copper sulfide mineral structure, greatly shortening the production cycle and avoiding waste pollution compared to bioleaching. This method is gentle to operate and has a simplified process, overcoming the bottleneck in the extraction of complex copper-bearing minerals and achieving efficient, safe, and low-cost recovery of metallic copper.

[0034] In a further embodiment, in order to optimize the kinetic conditions of the leaching reaction while taking into account production costs, the present invention has selected the core physicochemical parameters of the reaction system.

[0035] In some embodiments, the initial concentration of the sulfuric acid solution is 100 g / L to 400 g / L.

[0036] For the step of preparing the mixed slurry, the initial concentration of the sulfuric acid solution is further limited to 100 g / L to 400 g / L. The principle behind controlling this concentration is that sulfuric acid provides the necessary acidic medium for the leaching reaction to synergistically disrupt the crystal structure of copper sulfide with oxygen. Within this initial concentration range, sufficient hydrogen ions are provided to maintain a high leaching rate and to prevent hydrolysis of dissolved copper ions; simultaneously, it effectively avoids unnecessary reagent consumption and increased costs in subsequent neutralization processes due to excessively high acidity. As a specific implementation example, the initial concentration of the sulfuric acid solution can be, for example, 100 g / L, 150 g / L, 200 g / L, 250 g / L, 300 g / L, 350 g / L, 400 g / L, etc.

[0037] In some embodiments, the copper sulfide concentrate has a particle size of less than 0.074 mm.

[0038] By controlling the particle size of the solid raw material below this threshold through physical pulverization, the specific surface area of ​​the mineral particles in contact with the liquid phase (sulfuric acid) and the gas phase (oxygen) can be increased exponentially. The fine particle size not only eliminates the internal diffusion resistance of the reaction system, avoiding the problem of incomplete leaching caused by "unreacted nuclei" inside the particles, but also allows the solid material to be more uniformly suspended in the solution under stirring, thus ensuring an extremely high copper leaching rate under normal pressure. As a specific example, the particle size of the copper sulfide concentrate can be, for example, 0.074 mm, 0.070 mm, 0.065 mm, 0.060 mm, 0.050 mm, 0.040 mm, 0.030 mm, 0.020 mm, 0.010 mm, etc.

[0039] In some embodiments, the liquid-to-solid ratio of the mixed slurry is (3~10):1.

[0040] The liquid-to-solid ratio in the mixed slurry is further defined as (3~10):1. The liquid-to-solid ratio is a key parameter determining the slurry's hydrodynamic state and the gas-liquid-solid three-phase mass transfer efficiency. Controlling the liquid-to-solid ratio within the range of 3:1 to 10:1 ensures the slurry has suitable fluidity and viscosity. Under this condition, it prevents the slurry from being too thick, thus avoiding hindering the dispersion of oxygen bubbles and the homogenization of the solid-liquid system, while also avoiding problems such as low single-batch processing capacity and excessively dilute copper ion concentration in the final leachate due to an excessively high liquid-to-solid ratio. This achieves an excellent balance between process energy consumption and production efficiency. As a specific implementation example, the liquid-to-solid ratio of the mixed slurry can be, for example, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc.

[0041] In a further embodiment, in order to optimize the gas-liquid-solid three-phase reaction kinetics under normal pressure conditions and reduce energy and material consumption in the production process, the present invention has optimized and limited the gas composition and thermodynamic parameters involved in the reaction.

[0042] In some embodiments, the oxygen concentration in the oxygen-rich gas is 70% to 99.99%.

[0043] For the step of introducing gas into the mixed slurry, the oxygen concentration in the oxygen-rich gas is further defined as 70%~99.99%. In the atmospheric pressure leaching system, oxygen acts as the core oxidant, and its concentration directly determines the oxidation potential and gas-liquid mass transfer driving force of the reaction system. Using this high-concentration oxygen-rich gas can perfectly compensate for the shortcomings of insufficient total gas pressure under atmospheric pressure, ensuring that dissolved oxygen can rapidly penetrate and destroy the solid phase lattice of copper-containing minerals.

[0044] More importantly, if ordinary air is used directly for leaching, the gas flow rate must be greatly increased to meet the oxygen requirements of the reaction. A large amount of inert gases, such as nitrogen, which do not participate in the reaction, will carry away a significant amount of heat from the slurry and cause violent evaporation of moisture. Limiting the oxygen concentration to 70%~99.99% not only significantly improves the leaching rate but also effectively avoids heat loss and slurry concentration problems. As a specific implementation example, the oxygen concentration in the oxygen-rich gas can be, for example, 70%, 75%, 80%, 85%, 90%, 95%, 98%, 99%, 99.5%, 99.99%, etc.

[0045] In some embodiments, the leaching reaction is carried out at a temperature of 70°C to 95°C.

[0046] It should be noted that temperature is a key thermodynamic factor in overcoming the activation energy of the copper sulfide mineral reaction and accelerating the leaching rate. Controlling the leaching temperature within the range of 70°C to 95°C provides ample energy for the redox reaction, enabling rapid dissociation of metallic copper. Furthermore, since this invention operates at atmospheric pressure, the upper temperature limit (95°C) is strictly controlled below the boiling point of the aqueous solution, effectively avoiding the danger of acid mist overflow and the enormous heating energy consumption caused by boiling and vigorous evaporation under atmospheric pressure, thus achieving a balance between safety and efficiency. As a specific implementation example, the leaching reaction temperature can be, for example, 70°C, 72°C, 75°C, 78°C, 80°C, 85°C, 88°C, 90°C, 92°C, 95°C, etc.

[0047] In some embodiments, the leaching time of the leaching reaction is 6h to 12h.

[0048] This time range is based on the optimal reaction kinetic equilibrium point under the aforementioned temperature and oxygen-enriched conditions. Within this time range, the oxidant and acidic medium have sufficient time to diffuse into the interior of the mineral particles, achieving deep leaching of solid-phase copper. Compared to traditional bioleaching processes, this time range shortens the production cycle by several orders of magnitude, significantly improving industrial production efficiency. Simultaneously, it avoids the equipment depreciation and energy waste caused by uncontrolled extension of reaction time. As a specific implementation example, the leaching time of the leaching reaction can be, for example, 6h, 7h, 7.5h, 8h, 9h, 10h, 10.5h, 11h, 11.5h, 12h, etc.

[0049] In a further preferred embodiment, in order to maximize the three-phase mass transfer efficiency under normal pressure and ensure the smooth progress of the reaction, the gas introduction method and kinetic stirring conditions in this application embodiment have been specially designed and limited.

[0050] In some embodiments, the oxygen-rich gas is introduced into the mixed slurry through a gas distribution pipe.

[0051] For the aeration operation, the oxygen-rich gas is further defined as being introduced into the mixed slurry through a gas distribution pipe. In atmospheric pressure leaching systems, oxygen solubility is limited, therefore increasing the gas-liquid contact area is particularly important. By installing a gas distribution pipe in the reaction vessel, the continuous oxygen-rich flow can be dispersed into a large number of fine bubbles. This gas distribution method greatly increases the specific surface area between the gas and the acidic slurry, prolonging the residence time of the bubbles in the liquid phase, thereby effectively overcoming the slow oxygen dissolution rate under atmospheric pressure and ensuring sufficient oxidation potential within the system to disrupt the structure of copper sulfide minerals.

[0052] In some embodiments, the flow rate of the oxygen-rich gas is 0.7 L / min to 1.2 L / min.

[0053] For a specific reaction system, the flow rate of the oxygen-rich gas is further limited to 0.7 L / min to 1.2 L / min. For example, it can be 0.7 L / min, 0.75 L / min, 0.8 L / min, 0.9 L / min, 0.95 L / min, 1.0 L / min, 1.05 L / min, 1.1 L / min, 1.15 L / min, 1.2 L / min, etc. Controlling the flow rate is crucial for balancing leaching rate and material and energy consumption. Maintaining the flow rate between 0.7 L / min and 1.2 L / min provides a sufficient and stable oxygen source for the redox reaction, ensuring a high leaching rate. Simultaneously, this flow rate effectively avoids bubble escape and unnecessary oxygen waste caused by excessive gas supply, and in particular, prevents the loss of system heat and accelerated water evaporation when excessive gas escapes, maintaining the physical stability of the atmospheric pressure hydrothermal system.

[0054] In some embodiments, the leaching reaction is carried out under stirring conditions at a stirring speed of 300 rpm to 600 rpm. For example, the stirring speed can be 300 rpm, 320 rpm, 350 rpm, 400 rpm, 450 rpm, 480 rpm, 500 rpm, 550 rpm, 580 rpm, 600 rpm, etc.

[0055] Mechanical stirring is not only essential for maintaining the uniform suspension of fine copper sulfide particles in sulfuric acid solution and preventing sedimentation and agglomeration, but also a core driving force for enhancing mass transfer in the reaction. By controlling the speed within the range of 300 rpm to 600 rpm, the stirrer blades can generate suitable fluid shear force, further shearing and refining the bubbles overflowing from the gas distribution pipe. This achieves a highly homogeneous turbulent flow state among the gas, liquid, and solid phases, completely eliminating the product diffusion boundary layer on the particle surface. Simultaneously, this speed range avoids mass transfer deterioration caused by excessively low speeds, and also prevents unnecessary mechanical energy consumption and excessive equipment wear caused by excessively high speeds.

[0056] In a further preferred embodiment, in order to broaden the raw material adaptability of the process of this application and solve the technical problem of copper resource loss in existing hydrometallurgical processes, the specific source of the copper sulfide concentrate is preferably limited in this embodiment. In some embodiments, the copper sulfide concentrate includes leaching residue flotation concentrate obtained after leaching and residue flotation of copper oxide concentrate.

[0057] With the continuous exploitation of mineral resources, raw ores are gradually transforming from oxide ores to mixed sulfur and oxide ores. In conventional hydrometallurgical systems, easily soluble copper oxide components are usually extracted preferentially. However, due to the fine grain size of mineral crystals, severe symbiotic inclusions, or the presence of mineral entrainment, copper oxide concentrates often contain some copper sulfide minerals that are difficult to refine using conventional weakly oxidizing or non-oxidizing hydrometallurgical processes. These stubborn sulfides are left in the solid waste after front-end leaching, resulting in significant metal loss.

[0058] This embodiment addresses this industrial situation by using the "leaching residue flotation concentrate," obtained through conventional leaching followed by enrichment via flotation, as the raw material for atmospheric pressure oxygen-enriched leaching. Because this method constructs a synergistic strong oxidizing environment of high concentrations of free sulfuric acid and oxygen-rich gas, it effectively overcomes the lattice energy barrier of refractory sulfides in this type of flotation concentrate, achieving deep dissociation. This not only achieves efficient treatment of such complex industrial waste / intermediate products but also seamlessly integrates them into the existing mining and smelting cycle, completely solving the problem of resource waste from difficult-to-recover copper in the leaching residue and greatly improving the overall copper resource recovery rate throughout the entire process.

[0059] In a further preferred embodiment, in order to achieve a complete closed-loop process from copper-containing minerals to high-purity metal products, the present invention provides preferred and specific methods for purifying the solution obtained after leaching and for product extraction. In some embodiments, the step of using the copper-containing leachate to recover metallic copper includes: preparing electrowinning copper by passing the copper-containing leachate through an extraction-electrowinning process.

[0060] After atmospheric pressure oxygen-enriched leaching and liquid-solid separation, the copper-containing leachate obtained is often rich in target copper ions, but also contains gangue symbiotic impurities such as iron. In order to obtain pure elemental metals with high commercial value, this embodiment uses a mature extraction-electrowinning (SX-EW) combined process to deeply treat the leachate.

[0061] First, the copper-containing leachate obtained from liquid-solid separation is introduced into the extraction process. An organic extractant with high selectivity for copper ions is used to extract the Cu ions from the liquid phase. 2+ The copper sulfate electrolyte is selectively complexed and transferred to the organic phase, thereby achieving complete separation and enrichment from symbiotic impurity metals in the aqueous phase; subsequently, a pure and highly concentrated copper sulfate electrolyte is obtained through high-acid back-extraction.

[0062] Secondly, the purified and enriched copper sulfate electrolyte is introduced into the electrowinning process. Under the action of a DC electric field, copper ions in the electrolyte undergo an electrochemical reduction reaction on the cathode surface, depositing high-purity solid metallic copper (i.e., electrowinning copper). This process not only seamlessly integrates with the sulfuric acid leaching system at the front end of this invention, but also allows for the potential for internal recycling of the sulfuric acid system regenerated from oxygen evolution at the anode during electrowinning. This combined process completely opens up a short-process hydrometallurgical channel from low-grade / difficult-to-process copper sulfide minerals to high-purity cathode copper, achieving efficient, clean, and high-value-added recovery of metallic copper.

[0063] In a further preferred embodiment, in order to demonstrate the superior extraction capability of the process of the present invention for refractory minerals and its broad adaptability to polymetallic symbiotic minerals, the present invention has made preferred limitations on the mineral composition and symbiotic metal types to be processed.

[0064] In some embodiments, the copper-containing compounds in the copper sulfide concentrate include at least one of CuFeS2, CuS, and Cu2S.

[0065] In existing hydrometallurgical systems, these types of copper sulfide minerals, due to their extremely high lattice energy and chemical stability, are typically difficult to directly acid leach, often requiring harsh high-temperature and high-pressure conditions or extremely long bioleaching cycles. This invention utilizes an atmospheric pressure oxygen-enriched system, introducing a high concentration of oxygen as a strong oxidant into a sulfuric acid medium. Thermodynamic analysis shows that, with the participation of oxygen, the standard Gibbs free energy of the oxidation reaction of CuFeS2, CuS, and Cu2S with sulfuric acid to generate soluble copper ions is less than zero. This means that the atmospheric pressure oxygen-enriched system of this invention can spontaneously and efficiently break the lattice constraints of these stubborn sulfides, completely overcoming the technical barrier that traditional atmospheric pressure hydrometallurgical processes struggle to handle primary and secondary copper sulfide minerals such as CuFeS2.

[0066] In some embodiments, the copper sulfide concentrate is copper-cobalt sulfide concentrate; the copper-containing leachate also contains leached cobalt ions.

[0067] In actual mineral resources, cobalt often occurs closely associated with or forms symbiotic lattices with copper sulfide minerals. The atmospheric pressure oxygen-enriched acid leaching system of this invention efficiently disrupts the copper sulfide lattice while simultaneously generating a strong oxidative dissociation effect on the associated cobalt sulfide minerals. Through a single atmospheric pressure leaching process, the simultaneous release and liquid-phase enrichment of both copper and cobalt, two high-value metals, can be achieved, yielding a comprehensive leachate rich in copper and cobalt ions. This embodiment avoids the drawbacks of establishing complex extraction lines separately for associated metals, achieving maximum comprehensive recovery and utilization of multi-metal symbiotic mineral resources with extremely low process costs and mild operating conditions, possessing extremely high industrial economic value.

[0068] The present invention will be further illustrated below with specific embodiments. However, it should be understood that these embodiments are merely for the purpose of more detailed illustration and should not be construed as limiting the present invention in any way.

[0069] Experimental materials description: Before conducting the leaching experiments in the following examples and comparative examples, the copper sulfide concentrate from the slag beneficiation process provided in Table 1 was used as the test raw material. The specific composition of this test raw material is shown in Table 1: Table 1. Composition analysis of copper sulfide concentrate from slag beneficiation

[0070] Example 1 This embodiment provides a method for extracting cobalt and copper from copper-cobalt sulfide concentrate by atmospheric pressure oxygen-enriched leaching, and serves as a benchmark experiment to examine the overall effectiveness of atmospheric pressure oxygen-enriched leaching. The specific experimental method is as follows: Step S1: Mix sulfuric acid with water to obtain a first mixed solution, and control the initial concentration of sulfuric acid to be 250 g / L; Step S2: According to the liquid-solid ratio of 5:1, copper sulfide concentrate with a particle size of less than 0.074 mm is added to the first mixed solution and thoroughly mixed and stirred to obtain the second mixed solution. Step S3: Place the gas distribution tube into the mixed solution and continuously introduce oxygen, controlling the oxygen concentration at 80% and the oxygen flow rate at 0.9 L / min; control the leaching reaction temperature at 90℃, the stirring speed at 400 rpm / min, and the leaching time at 8 h. Step S4: After the leaching reaction is completed, the leaching solution and leaching residue are obtained through liquid-solid separation.

[0071] Example 2 This embodiment provides a method for extracting cobalt and copper from copper-cobalt sulfide concentrate by atmospheric pressure oxygen-enriched leaching, mainly investigating the effect of reducing oxygen flow rate on leaching efficiency within a limited range.

[0072] Specific experimental method: Other parameters are exactly the same as in Example 1, the only difference is that the oxygen flow rate in step S3 is set to 0.7 L / min.

[0073] Example 3 This embodiment provides a method for extracting cobalt and copper from copper-cobalt sulfide concentrate by atmospheric pressure oxygen-enriched leaching. The main focus is on the effect of increasing the oxygen flow rate on the leaching effect within a limited range.

[0074] Specific experimental method: Other parameters are exactly the same as in Example 1, the only difference is that the oxygen flow rate in step S3 is set to 1.2 L / min.

[0075] Example 4 This embodiment provides a method for extracting cobalt and copper from copper-cobalt sulfide concentrate by atmospheric pressure oxygen-enriched leaching. The main focus is on investigating the effect of reducing the leaching reaction temperature on the leaching effect within a limited range.

[0076] Specific experimental methods: Other parameters are exactly the same as in Example 1, the only difference being that the leaching reaction temperature in step S3 is set to 70°C.

[0077] Example 5 This embodiment provides a method for extracting cobalt and copper from copper-cobalt sulfide concentrate by atmospheric pressure oxygen-enriched leaching. The main focus is on the effect of increasing the leaching reaction temperature on the leaching effect within a limited range.

[0078] Specific experimental methods: Other parameters are exactly the same as in Example 1, the only difference being that the leaching reaction temperature in step S3 is set to 95°C.

[0079] Example 6 This embodiment provides a method for extracting cobalt and copper from copper-cobalt sulfide concentrate by atmospheric pressure oxygen-enriched leaching. The main focus is on the effect of shortening the leaching time on the leaching effect within a limited range.

[0080] Specific experimental method: Other parameters are exactly the same as in Example 1, the only difference is that the leaching time in step S3 is set to 6h.

[0081] Example 7 This embodiment provides a method for extracting cobalt and copper from copper-cobalt sulfide concentrate by atmospheric pressure oxygen-enriched leaching. The main focus is on the effect of extending the leaching time on the leaching effect within a limited range.

[0082] Specific experimental method: Other parameters are exactly the same as in Example 1, the only difference is that the leaching time in step S3 is set to 12h.

[0083] Example 8 This embodiment provides a method for extracting metals from copper-cobalt sulfide concentrate by atmospheric pressure oxygen-enriched leaching. The main focus is on the effect of the initial sulfuric acid concentration being at the lower limit within a defined range on the leaching effect.

[0084] Specific experimental methods: Other parameters are exactly the same as in Example 1, the only difference is that the initial concentration of sulfuric acid in step S1 is controlled to be 100 g / L.

[0085] Example 9 This embodiment provides a method for extracting metals from copper-cobalt sulfide concentrate by atmospheric pressure oxygen-enriched leaching. The main focus is on the effect of the initial sulfuric acid concentration being at its upper limit within a defined range on the leaching effect.

[0086] Specific experimental methods: Other parameters are exactly the same as in Example 1, the only difference is that the initial concentration of sulfuric acid in step S1 is controlled to be 400 g / L.

[0087] Example 10 This embodiment provides a method for extracting metals from copper-cobalt sulfide concentrate by atmospheric pressure oxygen-enriched leaching. The main focus is on the effect of the liquid-solid ratio of the mixed slurry being at the lower limit within a defined range on the leaching effect.

[0088] Specific experimental method: Other parameters are exactly the same as in Example 1, the only difference is that in step S2, copper sulfide concentrate is added to the first mixed solution at a liquid-solid ratio of 3:1.

[0089] Example 11 This embodiment provides a method for extracting metals from copper-cobalt sulfide concentrate by atmospheric pressure oxygen-enriched leaching. The main focus is on the effect of the liquid-solid ratio of the mixed slurry being at its upper limit within a defined range on the leaching effect.

[0090] Specific experimental method: Other parameters are exactly the same as in Example 1, the only difference is that in step S2, copper sulfide concentrate is added to the first mixed solution at a liquid-solid ratio of 10:1.

[0091] Example 12 This embodiment provides a method for extracting metals from copper-cobalt sulfide concentrate by atmospheric pressure oxygen-enriched leaching. The main focus is on the effect of the oxygen concentration in the introduced gas being at the lower limit within a specified range on the leaching effect.

[0092] Specific experimental method: Other parameters are exactly the same as in Example 1, the only difference is that the oxygen concentration of the introduced gas is controlled to be 70% in step S3.

[0093] Example 13 This embodiment provides a method for extracting metals from copper-cobalt sulfide concentrate by atmospheric pressure oxygen-enriched leaching. The main focus is on the effect of using extremely high concentrations of pure oxygen in the introduced gas on the leaching effect within a limited range.

[0094] Specific experimental method: Other parameters are exactly the same as in Example 1, the only difference is that in step S3, the oxygen concentration of the gas introduced is controlled to be 99.99% (industrial pure oxygen).

[0095] Example 14 This embodiment provides a method for extracting metals from copper-cobalt sulfide concentrate by atmospheric pressure oxygen-enriched leaching. The main focus is on the effect of the stirring speed being at the lower limit within a defined range on the leaching effect.

[0096] Specific experimental method: Other parameters are exactly the same as in Example 1, the only difference is that the stirring speed is controlled at 300 rpm in step S3.

[0097] Example 15 This embodiment provides a method for extracting metals from copper-cobalt sulfide concentrate by atmospheric pressure oxygen-enriched leaching. The main focus is on the effect of the stirring speed being at its upper limit within a defined range on the leaching effect.

[0098] Specific experimental method: Other parameters are exactly the same as in Example 1, the only difference is that the stirring speed is controlled at 600 rpm in step S3.

[0099] Example 16 This embodiment provides a method for extracting metals by atmospheric pressure oxygen-enriched leaching, mainly examining the universality and adaptability of the atmospheric pressure oxygen-enriched system of the present invention to the extremely difficult-to-leach primary chalcopyrite (CuFeS2).

[0100] Specific experimental method: Other parameters are exactly the same as in Example 1, the only difference is that the solid raw material used in step S2 is replaced with pure chalcopyrite (CuFeS2) mineral powder with a particle size of less than 0.074 mm.

[0101] Comparative Example 1 This comparative example provides a leaching recovery method, mainly examining the effect of oxygen flow rate being below the preferred range on the leaching effect.

[0102] Specific experimental method: Other parameters are exactly the same as in Example 1, the only difference is that the oxygen flow rate in step S3 is set to 0.3 L / min.

[0103] Comparative Example 2 This comparative example provides a leaching recovery method, mainly examining the impact of oxygen flow rates exceeding the preferred range on leaching efficiency and cost.

[0104] Specific experimental method: Other parameters are exactly the same as in Example 1, the only difference is that the oxygen flow rate in step S3 is set to 1.5 L / min.

[0105] Comparative Example 3 This comparative example provides a leaching recovery method, mainly examining the effect of reaction temperature below the preferred range on the leaching effect.

[0106] Specific experimental methods: Other parameters are exactly the same as in Example 1, the only difference being that the leaching reaction temperature in step S3 is set to 50°C.

[0107] Comparative Example 4 This comparative example provides a leaching recovery method, mainly examining the effect of changing the type of gas introduced (not using oxygen-enriched gas) on the leaching effect.

[0108] Specific experimental method: Other parameters are exactly the same as in Example 1, the only difference is that the type of gas introduced in step S3 is changed, and oxygen is replaced with air.

[0109] Comparative Example 5 This comparative example provides a leaching recovery method, mainly examining the impact of excessively short leaching time on the leaching effect.

[0110] Specific experimental method: Other parameters are exactly the same as in Example 1, the only difference is that the leaching time in step S3 is set to 2h.

[0111] Comparative Example 6 This comparative example provides a leaching recovery method, mainly examining the impact of excessively long leaching times on leaching efficiency and cost.

[0112] Specific experimental method: Other parameters are exactly the same as in Example 1, the only difference is that the leaching time in step S3 is set to 14h.

[0113] Test Experiment 1. Experimental results data: The leaching residue and leachate obtained from the above examples and comparative examples were collected, the Cu content was determined, and the Cu leaching rate was calculated. The results are shown in Table 2. Table 2 shows the Cu content in the slag and liquid, and the Cu leaching rate in the examples and comparative examples.

[0114] 2. Analysis: A comprehensive analysis of the experimental data in Table 2 shows that the atmospheric pressure oxygen-enriched leaching and recovery method provided in this application embodiment achieves extremely high copper extraction efficiency under mild conditions through the synergistic effect of various process parameters. Specific analysis is as follows: (1) As can be seen from the data of Examples 1 to 7, within the parameter conditions specified in the examples of this application (oxygen flow rate 0.7~1.2L / min, temperature 70~95℃, time 6~12h), Cu can achieve extremely high leaching rates, with the vast majority reaching over 99% (up to 99.50%). This proves that the synergistic leaching system of "atmospheric pressure + oxygen enrichment + sulfuric acid" adopted in this invention effectively breaks the lattice constraint of copper sulfide minerals, completely overcomes the dependence on high temperature and high pressure equipment in the prior art, and achieves excellent extraction results under safe and low-cost atmospheric pressure operation.

[0115] (2) Regarding the influence of the type of gas introduced and the oxygen flow rate (comparing Examples 1-3 with Comparative Examples 1, 2, and 4), the supply of oxidant is the core of atmospheric pressure leaching kinetics. Comparing Example 1 (using oxygen, leaching rate 99.23%) with Comparative Example 4 (replacing with ordinary air, leaching rate sharply reduced to 82.39%), it can be seen that directly introducing air will lead to extremely incomplete reaction, and oxygen-enriched gas is a necessary condition for achieving efficient atmospheric pressure leaching.

[0116] Regarding oxygen flow rate, the leaching rate of Comparative Example 1 (oxygen flow rate reduced to 0.3 L / min) was only 91.08%, a significant decrease compared to Example 1. This was mainly due to insufficient dissolved oxygen in the reaction system, preventing complete oxidation of the copper sulfide minerals. Examples 2 and 3, using flow rates of 0.7 L / min and 1.2 L / min respectively, maintained high leaching rates of 99.02% and 99.40%. However, as shown in Comparative Example 2, when the oxygen flow rate was further blindly increased to 1.5 L / min, the leaching rate was only 99.42%, showing little improvement compared to Example 3. Furthermore, this resulted in a large amount of oxygen escaping, significantly increasing the raw material cost of oxygen. Therefore, limiting the flow rate to 0.7–1.2 L / min is the optimal range that balances reaction kinetics and economic costs.

[0117] (3) Regarding the effect of leaching reaction temperature (comparing Examples 1, 4, and 5 with Comparative Example 3), temperature directly determines the thermodynamic activation energy of the leaching reaction. The leaching rates of Examples 4 (70°C), 1 (90°C), and 5 (95°C) were 95.15%, 99.23%, and 99.45%, respectively, indicating that within the preferred range, increasing the temperature significantly promotes the leaching rate of Cu. However, as shown in Comparative Example 3, when the temperature was reduced to 50°C, the leaching rate dropped to 93.63%. This is mainly because excessively low temperatures lead to slow reaction kinetics, making it difficult to completely destroy the crystal structure of the refractory sulfides. Limiting the temperature to 70~95°C provides sufficient reaction kinetics while avoiding excessive water evaporation caused by boiling of the solution under normal pressure.

[0118] (4) Regarding leaching time (comparing Examples 1, 6, and 7 with Comparative Examples 5 and 6), leaching time determines the thoroughness of the reaction. When the reaction time is too short (e.g., 2 hours in Comparative Example 5), the reactants fail to fully penetrate the solid particles, resulting in incomplete leaching and a leaching rate of only 94.61%. Extending the time to 6 hours (Example 6), 8 hours (Example 1), and 12 hours (Example 7) steadily increases the leaching rate to 99.12%, 99.23%, and 99.50%, respectively. However, as shown in Comparative Example 6, when the time is further extended to 14 hours, the leaching rate is 99.45%. Comparing Example 7, it can be seen that excessive reaction time does not significantly improve the leaching rate; instead, it leads to equipment idling and unnecessarily increases production operating and time costs. Therefore, 6–12 hours is the optimal time balance point for achieving efficient and economical extraction.

[0119] (5) Regarding the influence of sulfuric acid concentration and liquid-solid ratio boundary range (comparing Examples 1 with 8, 9, 10, and 11), sulfuric acid concentration and liquid-solid ratio directly affect the mass transfer resistance and acidity drive of the system. The leaching rates of Examples 8 (100 g / L) and 9 (400 g / L) were 96.52% and 99.41%, respectively, indicating that even at the lower limit of acidity of 100 g / L, the atmospheric pressure oxygen-enriched system of the present invention can still provide sufficient hydrogen ions to complete the oxidation reaction; while at 400 g / L, the leaching rate has reached its limit. Similarly, at the lower limit of liquid-solid ratio of 3:1 (Example 10, leaching rate 95.84%), although the slurry is thicker and hinders some mass transfer, it still maintains an excellent leaching level; at the upper limit of 10:1 (Example 11, leaching rate 99.35%), the extraction is extremely thorough. Data proves that the technical objectives of this invention can be fully achieved within the ranges of (100~400g / L) and (3~10:1) requested in this application.

[0120] (6) Regarding the influence of the boundary of the driving force of gas-phase oxidation (oxygen concentration) (comparing Examples 1 with 12 and 13), Example 12 (70% oxygen concentration) achieved a leaching rate of 97.15%, and Example 13 (99.99% industrial pure oxygen) achieved an ultimate leaching rate of 99.62%. Compared with Comparative Example 4 (21% air, leaching rate of 82.39% failure state), the boundary data of Example 12 strongly supports the scientific conclusion that "the oxygen concentration needs to be above 70% to break through the atmospheric pressure leaching mass transfer bottleneck." 70%~99.99% is a reasonable protection range that is well supported by experiments.

[0121] (7) Regarding the influence of the stirring speed boundary (comparing Examples 1 with 14 and 15), Examples 14 (300 rpm, leaching rate 96.88%) and 15 (600 rpm, leaching rate 99.55%) demonstrate the synergistic effect of fluid shear force. Within the range of 300~600 rpm, the stirring paddle can effectively break up the bubbles overflowing from the gas distribution pipe and maintain solid phase suspension, achieving the expected positive technical effects at both ends of the range.

[0122] (8) Regarding the universality of raw materials (Example 16), it is worth emphasizing that Example 16 directly uses pure mineral powder of primary chalcopyrite (CuFeS2), one of the most difficult single minerals to process in nature, as the raw material. Chalcopyrite, which is extremely difficult to dissolve in conventional wet processes, still achieved a leaching rate as high as 98.15% under the atmospheric pressure and oxygen-enriched conditions of this invention. This convincingly proves that this method is not only suitable for processing specific roasting leaching flotation residues, but also, as a broad-spectrum and efficient extraction method, is widely applicable to all types of copper sulfide concentrates containing difficult-to-leach compounds such as CuFeS2 and CuS, and has extremely high industrial application value.

[0123] The data comparison between the above embodiments and comparative examples fully demonstrates that there is a significant synergistic effect among the specific process parameters (concentration, liquid-to-solid ratio, specific oxygen-enriched gas and flow rate, medium-high temperature and suitable time) defined in the embodiments of this application. Only within this specific range of process parameters can the high efficiency and economy of the reaction be balanced without using high-pressure equipment, thus perfectly solving the problems of high production risk, long cycle and high cost in the background technology.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for recovering metallic copper by atmospheric pressure oxygen-enriched leaching, characterized in that, include: Copper sulfide concentrate is added to a sulfuric acid solution and mixed to obtain a mixed slurry; Under normal pressure, an oxygen-rich gas is introduced into the mixture slurry to carry out a leaching reaction; After the leaching reaction is completed, liquid-solid separation is performed to obtain a copper-containing leachate that can be used to recover metallic copper.

2. The atmospheric pressure oxygen-enriched leaching recovery method for metallic copper as described in claim 1, characterized in that, The initial concentration of the sulfuric acid solution is 100 g / L to 400 g / L; and / or, The copper sulfide concentrate has a particle size of less than 0.074 mm; and / or, In the mixed slurry, the liquid-to-solid ratio is (3~10):

1.

3. The atmospheric pressure oxygen-enriched leaching recovery method for metallic copper as described in claim 1, characterized in that, The oxygen-rich gas has an oxygen concentration of 70% to 99.99%.

4. The atmospheric pressure oxygen-enriched leaching recovery method for metallic copper as described in claim 1, characterized in that, The leaching reaction is carried out at a temperature of 70°C to 95°C; and / or, The leaching time for the leaching reaction is 6h to 12h.

5. The atmospheric pressure oxygen-enriched leaching recovery method for metallic copper as described in claim 1, characterized in that, The oxygen-rich gas is introduced into the mixed slurry through a gas distribution pipe.

6. The atmospheric pressure oxygen-enriched leaching recovery method for metallic copper as described in claim 1, characterized in that, The oxygen-rich gas is introduced at a flow rate of 0.7 L / min to 1.2 L / min; and / or, The leaching reaction is carried out under stirring conditions, with a stirring speed of 300 rpm to 600 rpm.

7. The atmospheric pressure oxygen-enriched leaching recovery method for metallic copper as described in claim 1, characterized in that, The copper sulfide concentrate comprises leaching residue flotation concentrate obtained from copper oxide concentrate after leaching and residue flotation.

8. The atmospheric pressure oxygen-enriched leaching recovery method for metallic copper as described in claim 1, characterized in that, The step of using the copper-containing leaching solution to recover metallic copper includes: preparing electrowinning copper by passing the copper-containing leaching solution through an extraction-electrowinning process.

9. The atmospheric pressure oxygen-enriched leaching recovery method for metallic copper as described in claim 1, characterized in that, The copper-containing compounds in the copper sulfide concentrate include at least one of CuFeS2, CuS, and Cu2S.

10. The atmospheric pressure oxygen-enriched leaching recovery method for metallic copper as described in claim 1, characterized in that, The copper sulfide concentrate is a copper-cobalt sulfide concentrate; the copper-containing leachate also contains leached cobalt ions.

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