Recovery method for microorganism-assisted electrochemical flotation mixed copper-cobalt ore

Abstract

The invention provides a brand-new efficient recovery method for mixed copper-cobalt ore, which comprises the following steps: firstly, crushing and desliming, then inoculating thiobacillus ferrooxidans in a culture medium in which nano iron oxide is pre-dispersed, culturing, and finally adopting an electrochemical flotation system with an anode as a titanium-based platinum-plated electrode and a cathode as a foamed nickel electrode, and flotation is performed in three stages under the control of a pulse power supply. According to the method, a microorganism-assisted electrochemical flotation technology and a nanometer material modification and gradient flotation strategy are combined, the surface property of the ore is changed through microorganism metabolism, metabolism is accelerated through electrochemistry to generate bubbles, flotation selectivity is enhanced with the help of a nanometer material, and finally efficient recovery of the mixed copper-cobalt ore is achieved.

Description

Technical Field

[0001] This invention relates to the field of copper and cobalt extraction technology, and specifically to a method for recovering mixed copper-cobalt ore by microbial-assisted electrochemical flotation. Background Technology

[0002] Copper and cobalt, as key strategic metals supporting modern industrial development, are directly related to the breakthroughs in the new energy revolution and high-end equipment manufacturing. As a core material for global electrification transformation, copper demand in new energy vehicles, smart grids, and 5G communications is growing exponentially, while cobalt, a key component of high-energy-density lithium batteries, is seeing its strategic value continuously rise in the aerospace and energy storage industries. However, the global distribution of copper and cobalt resources is extremely uneven. The absolute control of cobalt mines by resource-rich countries such as the Democratic Republic of Congo and the restrictions on the development of the South American copper belt make the international supply chain highly vulnerable. Seeking new recycling technologies will effectively alleviate my country's strategic problems such as the supply shortage of copper and cobalt resources.

[0003] Studies have shown that fine-grained copper-cobalt oxide ores require fine grinding to achieve monomer liberation. However, fine grinding alters the flotation behavior of copper-cobalt oxide ores. During flotation, fine-grained copper-cobalt oxide ores are difficult to float, resulting in low recovery rates. Simultaneously, mud content interferes with the flotation process, leading to poor recovery of fine-grained malachite, difficulty in enriching chrysocolla, and reduced concentrate quality due to easily floated gangue. Traditional copper-cobalt ore flotation processes suffer from low recovery rates, high costs, and severe environmental pollution. This is particularly true when processing fine-grained copper-cobalt oxide ores, where the complex flotation behavior makes recovery even more difficult. Therefore, seeking an efficient, environmentally friendly, and economical method for copper-cobalt ore recovery is of great significance. Summary of the Invention

[0004] Technical Problem to be Solved: Addressing the shortcomings of existing technologies, this invention proposes a method for recovering mixed copper-cobalt ores based on microbial-assisted electrochemical flotation. This method alters the surface properties of the ore through microbial metabolic activity, accelerates microbial metabolism and generates flotation bubbles using electrochemical methods, and enhances flotation selectivity using nanomaterials, ultimately achieving efficient recovery of mixed copper-cobalt ores.

[0005] Technical solution: A method for recovering mixed copper-cobalt ore by microbial-assisted electrochemical flotation, comprising the following steps: S1. After crushing the ore, the slime is removed to obtain deslimed ore; S2. Inoculate the culture medium with *Thiobacillus ferrooxidans* and shake to obtain *Thiobacillus ferrooxidans* culture medium; S3. Mix the deslimed ore with the culture medium of *Thiobacillus ferrooxidans*, add nano-iron oxide, shake the reaction, filter through a filter membrane, wash with dilute sulfuric acid, and dry to obtain surface-functionalized ore; S4. Add ferrooxidizing thiobacillus, nano-iron oxide and surface-functionalized ore to a flotation cell filled with dilute sulfuric acid solution, a nano bubble generator and electrodes to form an electrochemical system; S5. The electrochemical flotation system is connected to a pulse power supply to control the pulse and current. The flotation is carried out in three stages. The flotation foam is collected by a scraper. Copper and cobalt are filtered, dried and weighed.

[0006] Furthermore, in step S1, the ore crushing requirement is a fineness of ≥90% 200 mesh, and the particle size of the removed slime is 5-10 μm.

[0007] Furthermore, in step S2, the bacterial density of *Thiobacillus ferrooxidans* is 40-80%, the pH of the culture medium is 1.5, and the composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L; the shaking culture temperature is 20-30℃, and the time is 24-72 h.

[0008] Furthermore, in step S3, the particle size of the nano-iron oxide is 20-50 nm, and the content is 0.1-0.3 wt%; the mass ratio of the *Thiobacillus ferrooxidans* culture medium to the deslimed ore is 1:(5-6); the bacterial density of *Thiobacillus ferrooxidans* is 40-80%; the shaking reaction temperature is 20-30℃, the rotation speed is 120 rpm, and the time is 24-72 h; the pore size of the filter membrane is 0.22 μm, and the pH of the dilute sulfuric acid is 1.5; the drying temperature is 50-70℃, and the time is 1-2 h.

[0009] Furthermore, in step S4, the anode of the electrode is a platinum-plated titanium substrate electrode, and the cathode is a nickel foam electrode; the mass ratio of the *Thiobacillus ferrooxidans* culture medium, the nano-iron oxide solution, and the surface-functionalized ore is 1:5:(2-4); the pH of the dilute sulfuric acid solution is 1.5; the bacterial density of *Thiobacillus ferrooxidans* is 60%; and the concentration of the nano-iron oxide solution is 0.1 wt%.

[0010] Furthermore, the conditions for the three-stage flotation in step S5 are as follows: the first stage has a current density of 10-15 mA / cm² and a potential gradient of 0.5-0.7 V / cm for 6-8 min; the second stage has a potential gradient of 0.7-0.9 V / cm for 10-12 min; and the third stage has a potential gradient of 0.9-1.1 V / cm for 12-15 min. Beneficial effects

[0011] This invention combines nano-modification with microbial-assisted electrochemical flotation. *Acidithiobacillus ferrooxidans* oxidizes sulfides to produce Fe³⁺ / H₂SO₄, leading to the formation of pores and dissolution on the mineral surface, accelerating mineral dissolution and sulfide exposure. Microbial catalysis of cathodic electrolysis of water generates 50-100 μm hydrogen bubbles as a flotation carrier. Nano-iron oxide particles (20-50 nm) form an Fe-S bonded hydrophobic film on the mineral surface, selectively adsorbing copper-cobalt minerals, improving surface hydrophobicity, further stabilizing the bubble-mineral interface, enhancing the selectivity of the flotation process, enabling more effective separation of copper-cobalt minerals from gangue minerals, improving concentrate grade, significantly increasing mineral separation efficiency, and reducing environmental pollution.

[0012] This invention employs a gradient potential separation principle. Chalcopyrite, with a surface zeta potential of -15mV at 0.6V / cm, preferentially combines with H2 bubbles. Cobaltite undergoes surface sulfidation at 0.8V / cm, while gangue minerals (such as quartz) remain hydrophilic at 1.0V / cm. This gradient separation achieves a three-stage, highly efficient separation process: preferential capture of chalcopyrite, surface sulfidation activation of cobaltite, and inhibition of hydrophilicity in gangue minerals. This is an intelligent separation process that proceeds from easy to difficult. First, the minerals with the best floatability are rapidly floated at high current density and low potential. Then, the potential is gradually increased to overcome the difficult-to-float minerals that require more energy to float, ultimately maximizing the recovery rate and ensuring that the tailings grade is minimized.

[0013] The nano-iron oxide particles of the present invention have a synergistic effect with ferrous thiobacillus, which has the benefits of surface modification, metabolism promotion and enhanced stability, greatly enhances the selectivity of flotation, reduces the inclusion of gangue minerals, and is expected to yield a higher grade of concentrate, thereby reducing the cost of subsequent smelting processes.

[0014] The synergistic effect of the technical solution of this invention improves the copper grade of the concentrate compared with traditional flotation; and reduces the loss of metal in the tailings. Compared with existing technologies, it has the characteristics of low cost, high efficiency, environmental friendliness and simple process.

[0015] This invention not only achieves a breakthrough in technology through the integration of multiple technologies, resulting in a dual improvement in recovery rate and concentrate grade; but also demonstrates significant advantages in terms of economics and environmental protection, such as reduced costs, shorter cycles, and environmental friendliness; in particular, it provides a highly promising solution for the efficient and green development of complex mixed copper-cobalt mineral resources, and has significant industrial application prospects and promotional value. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the extraction of copper and cobalt from copper-cobalt ore according to the present invention; Figure 2 XRD analysis diagrams of copper-cobalt ore and slime; Figure 3 This is a scanning electron microscope (SEM) energy dispersive spectroscopy (EDS) image of raw copper-cobalt ore. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments. The following embodiments are illustrative of the present invention, but the present invention is not limited to the following embodiments: Example 1

[0018] A method for recovering mixed copper-cobalt ore by microbial-assisted electrochemical flotation includes the following steps: S1. The ore is crushed to a fineness of ≥90% (200 mesh) by combining a jaw crusher and a ball mill. Then, a hydrocyclone is used to remove 10μm of slime to obtain deslimed ore. S2. Inoculate *Acidithiobacillus ferrooxidans* into the culture medium with a bacterial density of 40%, and culture at 30℃ with shaking for 48 h to obtain *Acidithiobacillus ferrooxidans* culture medium with a pH of 1.5. The composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L. S3. The deslimed ore and the culture medium of *Thiobacillus ferrooxidans* were mixed at a mass ratio of 5:1, and 0.1 wt% of nano-iron oxide with a particle size of 20-50 nm was added. The mixture was shaken at 30 °C and 120 rpm for 48 h, filtered through a 0.22 μm filter membrane, washed with dilute sulfuric acid at pH 1.5, and dried at 50 °C for 2 h to obtain the surface-functionalized ore. S4. A mixture of *Thiobacillus ferrooxidans* culture medium, 0.1 wt% of nano-iron oxide solution with a particle size of 20-50 nm, and surface-functionalized ore at a mass ratio of 1:5:3 is added to a flotation cell filled with a dilute sulfuric acid solution of pH=1.5, a nano-bubble generator, and a titanium-based platinum-plated electrode as the anode and a nickel foam electrode as the cathode to form an electrochemical system. S5. The electrochemical flotation system is connected to a pulse power supply, with the pulse controlled at 50Hz. The flotation is carried out in three stages: the first stage has a current density of 15 mA / cm² and applies a potential gradient of 0.6V / cm for 8 min; the second stage has a potential gradient of 0.8V / cm for 12 min; and the third stage has a potential gradient of 1.0V / cm for 15 min. The flotation foam is collected by a scraper, and the copper and cobalt are filtered, dried, and weighed. Example 2

[0019] A method for recovering mixed copper-cobalt ore by microbial-assisted electrochemical flotation includes the following steps: S1. The ore is crushed to a fineness of ≥90% (200 mesh) by combining a jaw crusher and a ball mill. Then, a hydrocyclone is used to remove 10μm of slime to obtain deslimed ore. S2. Inoculate *Acidithiobacillus ferrooxidans* into the culture medium, with a bacterial density of 60%, and culture at 30℃ with shaking for 48 h to obtain *Acidithiobacillus ferrooxidans* culture medium with a pH of 1.5; the composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L; S3. The deslimed ore and the culture medium of *Thiobacillus ferrooxidans* were mixed at a mass ratio of 5:1, and 0.1 wt% of nano-iron oxide with a particle size of 20-50 nm was added. The mixture was shaken at 30 °C and 120 rpm for 48 h, filtered through a 0.22 μm filter membrane, washed with dilute sulfuric acid at pH 1.5, and dried at 50 °C for 2 h to obtain the surface-functionalized ore. S4. A mixture of *Thiobacillus ferrooxidans* culture medium, 0.1 wt% of nano-iron oxide solution with a particle size of 20-50 nm, and surface-functionalized ore at a mass ratio of 1:5:3 is added to a flotation cell filled with a dilute sulfuric acid solution of pH=1.5, a nano-bubble generator, and a titanium-based platinum-plated electrode as the anode and a nickel foam electrode as the cathode to form an electrochemical system. S5. The electrochemical flotation system is connected to a pulse power supply, with the pulse controlled at 50Hz. The flotation is carried out in three stages: the first stage has a current density of 15 mA / cm² and applies a potential gradient of 0.6V / cm for 8 min; the second stage has a potential gradient of 0.8V / cm for 12 min; and the third stage has a potential gradient of 1.0V / cm for 15 min. The flotation foam is collected by a scraper, and the copper and cobalt are filtered, dried, and weighed. Example 3

[0020] A method for recovering mixed copper-cobalt ore by microbial-assisted electrochemical flotation includes the following steps: S1. The ore is crushed to a fineness of ≥90% (200 mesh) by combining a jaw crusher and a ball mill. Then, a hydrocyclone is used to remove 10μm of slime to obtain deslimed ore. S2. Inoculate *Acidithiobacillus ferrooxidans* into the culture medium, with a bacterial density of 80%, and culture at 30℃ with shaking for 48 h to obtain *Acidithiobacillus ferrooxidans* culture medium with a pH of 1.5; the composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L; S3. The deslimed ore and the culture medium of *Thiobacillus ferrooxidans* were mixed at a mass ratio of 5:1, and 0.1 wt% of nano-iron oxide with a particle size of 20-50 nm was added. The mixture was shaken at 30 °C and 120 rpm for 48 h, filtered through a 0.22 μm filter membrane, washed with dilute sulfuric acid at pH 1.5, and dried at 50 °C for 2 h to obtain the surface-functionalized ore. S4. A mixture of *Thiobacillus ferrooxidans* culture medium, 0.1 wt% of nano-iron oxide solution with a particle size of 20-50 nm, and surface-functionalized ore at a mass ratio of 1:5:3 is added to a flotation cell filled with a dilute sulfuric acid solution of pH=1.5, a nano-bubble generator, and a titanium-based platinum-plated electrode as the anode and a nickel foam electrode as the cathode to form an electrochemical system. S5. The electrochemical flotation system is connected to a pulse power supply, with the pulse controlled at 50Hz. The flotation is carried out in three stages: the first stage has a current density of 15 mA / cm² and applies a potential gradient of 0.6V / cm for 8 min; the second stage has a potential gradient of 0.8V / cm for 12 min; and the third stage has a potential gradient of 1.0V / cm for 15 min. The flotation foam is collected by a scraper, and the copper and cobalt are filtered, dried, and weighed. Example 4

[0021] A method for recovering mixed copper-cobalt ore by microbial-assisted electrochemical flotation includes the following steps: S1. The ore is crushed to a fineness of ≥90% (200 mesh) by combining a jaw crusher and a ball mill. Then, a hydrocyclone is used to remove 10μm of slime to obtain deslimed ore. S2. Inoculate *Acidithiobacillus ferrooxidans* into the culture medium, with a bacterial density of 60%, and culture at 30℃ with shaking for 48 h to obtain *Acidithiobacillus ferrooxidans* culture medium with a pH of 1.5; the composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L; S3. The deslimed ore and the culture medium of *Thiobacillus ferrooxidans* were mixed at a mass ratio of 5:1, and 0.1 wt% of nano-iron oxide with a particle size of 20-50 nm was added. The mixture was shaken at 30 °C and 120 rpm for 48 h, filtered through a 0.22 μm filter membrane, washed with dilute sulfuric acid at pH 1.5, and dried at 50 °C for 2 h to obtain the surface-functionalized ore. S4. A mixture of *Thiobacillus ferrooxidans* culture medium, 0.1 wt% of nano-iron oxide solution with a particle size of 20-50 nm, and surface-functionalized ore at a mass ratio of 1:5:3 is added to a flotation cell filled with a dilute sulfuric acid solution of pH=1.5, a nano-bubble generator, and a titanium-based platinum-plated electrode as the anode and a nickel foam electrode as the cathode to form an electrochemical system. S5. The electrochemical flotation system is connected to a pulse power supply, with the pulse controlled at 30Hz. The flotation is carried out in three stages: the first stage has a current density of 15 mA / cm² and applies a potential gradient of 0.6V / cm for 8 min; the second stage has a potential gradient of 0.8V / cm for 12 min; and the third stage has a potential gradient of 1.0V / cm for 15 min. The flotation foam is collected by a scraper, and the copper and cobalt are filtered, dried, and weighed. Example 5

[0022] A method for recovering mixed copper-cobalt ore by microbial-assisted electrochemical flotation includes the following steps: S1. The ore is crushed to a fineness of ≥90% (200 mesh) by combining a jaw crusher and a ball mill. Then, a hydrocyclone is used to remove 10μm of slime to obtain deslimed ore. S2. Inoculate *Acidithiobacillus ferrooxidans* into the culture medium, with a bacterial density of 60%, and culture at 30℃ with shaking for 48 h to obtain *Acidithiobacillus ferrooxidans* culture medium with a pH of 1.5; the composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L; S3. The deslimed ore and the culture medium of *Thiobacillus ferrooxidans* were mixed at a mass ratio of 5:1, and 0.1 wt% of nano-iron oxide with a particle size of 20-50 nm was added. The mixture was shaken at 30 °C and 120 rpm for 48 h, filtered through a 0.22 μm filter membrane, washed with dilute sulfuric acid at pH 1.5, and dried at 50 °C for 2 h to obtain the surface-functionalized ore. S4. A mixture of *Thiobacillus ferrooxidans* culture medium, 0.1 wt% of nano-iron oxide solution with a particle size of 20-50 nm, and surface-functionalized ore at a mass ratio of 1:5:3 is added to a flotation cell filled with a dilute sulfuric acid solution of pH=1.5, a nano-bubble generator, and a titanium-based platinum-plated electrode as the anode and a nickel foam electrode as the cathode to form an electrochemical system. S5. The electrochemical flotation system is connected to a pulse power supply, with the pulse controlled at 70Hz. The flotation is carried out in three stages: the first stage has a current density of 15 mA / cm² and applies a potential gradient of 0.6V / cm for 8 min; the second stage has a potential gradient of 0.8V / cm for 12 min; and the third stage has a potential gradient of 1.0V / cm for 15 min. The flotation foam is collected by a scraper, and the copper and cobalt are filtered, dried, and weighed. Example 6

[0023] A method for recovering mixed copper-cobalt ore by microbial-assisted electrochemical flotation includes the following steps: S1. The ore is crushed to a fineness of ≥90% (200 mesh) by combining a jaw crusher and a ball mill. Then, a hydrocyclone is used to remove 10μm of slime to obtain deslimed ore. S2. Inoculate *Acidithiobacillus ferrooxidans* into the culture medium, with a bacterial density of 60%, and culture at 30℃ with shaking for 48 h to obtain *Acidithiobacillus ferrooxidans* culture medium with a pH of 1.5; the composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L; S3. The deslimed ore and the culture medium of *Thiobacillus ferrooxidans* were mixed at a mass ratio of 5:1. 0.1 wt% of nano-iron oxide with a particle size of 20-50 nm was added. The mixture was shaken at 120 rpm for 24 h at 30 °C. The mixture was then filtered through a 0.22 μm filter membrane, washed with dilute sulfuric acid at pH 1.5, and dried at 50 °C for 2 h to obtain the surface-functionalized ore. S4. A mixture of *Thiobacillus ferrooxidans* culture medium, 0.1 wt% of nano-iron oxide solution with a particle size of 20-50 nm, and surface-functionalized ore at a mass ratio of 1:5:3 is added to a flotation cell filled with a dilute sulfuric acid solution of pH=1.5, a nano-bubble generator, and a titanium-based platinum-plated electrode as the anode and a nickel foam electrode as the cathode to form an electrochemical system. S5. The electrochemical flotation system is connected to a pulse power supply, with the pulse controlled at 50Hz. The flotation is carried out in three stages: the first stage has a current density of 15 mA / cm² and applies a potential gradient of 0.6V / cm for 8 min; the second stage has a potential gradient of 0.8V / cm for 12 min; and the third stage has a potential gradient of 1.0V / cm for 15 min. The flotation foam is collected by a scraper, and the copper and cobalt are filtered, dried, and weighed. Example 7

[0024] A method for recovering mixed copper-cobalt ore by microbial-assisted electrochemical flotation includes the following steps: S1. The ore is crushed to a fineness of ≥90% (200 mesh) by combining a jaw crusher and a ball mill. Then, a hydrocyclone is used to remove 10μm of slime to obtain deslimed ore. S2. Inoculate *Acidithiobacillus ferrooxidans* into the culture medium, with a bacterial density of 60%, and culture at 30℃ with shaking for 48 h to obtain *Acidithiobacillus ferrooxidans* culture medium with a pH of 1.5; the composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L; S3. The deslimed ore and the culture medium of *Thiobacillus ferrooxidans* were mixed at a mass ratio of 5:1. 0.1 wt% of nano-iron oxide with a particle size of 20-50 nm was added. The mixture was shaken at 120 rpm for 72 h at 30 °C. The mixture was then filtered through a 0.22 μm filter membrane, washed with dilute sulfuric acid at pH 1.5, and dried at 50 °C for 2 h to obtain the surface-functionalized ore. S4. A mixture of *Thiobacillus ferrooxidans* culture medium, 0.1 wt% of nano-iron oxide solution with a particle size of 20-50 nm, and surface-functionalized ore at a mass ratio of 1:5:3 is added to a flotation cell filled with a dilute sulfuric acid solution of pH=1.5, a nano-bubble generator, and a titanium-based platinum-plated electrode as the anode and a nickel foam electrode as the cathode to form an electrochemical system. S5. The electrochemical flotation system is connected to a pulse power supply, with the pulse controlled at 50Hz. The flotation is carried out in three stages: the first stage has a current density of 15 mA / cm² and applies a potential gradient of 0.6V / cm for 8 min; the second stage has a potential gradient of 0.8V / cm for 12 min; and the third stage has a potential gradient of 1.0V / cm for 15 min. The flotation foam is collected by a scraper, and the copper and cobalt are filtered, dried, and weighed. Example 8

[0025] A method for recovering mixed copper-cobalt ore by microbial-assisted electrochemical flotation includes the following steps: S1. The ore is crushed to a fineness of ≥90% (200 mesh) by combining a jaw crusher and a ball mill. Then, a hydrocyclone is used to remove 10μm of slime to obtain deslimed ore. S2. Inoculate *Acidithiobacillus ferrooxidans* into the culture medium, with a bacterial density of 60%, and culture at 30℃ with shaking for 48 h to obtain *Acidithiobacillus ferrooxidans* culture medium with a pH of 1.5; the composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L; S3. The deslimed ore and the culture medium of *Thiobacillus ferrooxidans* were mixed at a mass ratio of 5:1, 0.3 wt% nano iron oxide was added, and the mixture was shaken at 30°C and 120 rpm for 48 h. The mixture was then filtered through a 0.22 μm filter membrane, washed with dilute sulfuric acid at pH 1.5, and dried at 50°C for 2 h to obtain the surface-functionalized ore. S4. A mixture of *Thiobacillus ferrooxidans* culture medium, 0.1 wt% of nano-iron oxide solution with a particle size of 20-50 nm, and surface-functionalized ore at a mass ratio of 1:5:3 is added to a flotation cell filled with a dilute sulfuric acid solution of pH=1.5, a nano-bubble generator, and a titanium-based platinum-plated electrode as the anode and a nickel foam electrode as the cathode to form an electrochemical system. S5. The electrochemical flotation system is connected to a pulse power supply, with the pulse controlled at 50Hz. The flotation is carried out in three stages: the first stage has a current density of 15 mA / cm² and applies a potential gradient of 0.6V / cm for 8 min; the second stage has a potential gradient of 0.8V / cm for 12 min; and the third stage has a potential gradient of 1.0V / cm for 15 min. The flotation foam is collected by a scraper, and the copper and cobalt are filtered, dried, and weighed. Comparative Example 1

[0026] The difference between this comparative example and Example 2 is that it does not contain *Thiobacillus ferrooxidans*, as detailed below: S1. The ore is crushed to a fineness of ≥90% (200 mesh) by combining a jaw crusher and a ball mill. Then, a hydrocyclone is used to remove 10μm of slime to obtain deslimed ore. S2. The deslimed ore and water are mixed at a mass ratio of 5:1, and 0.1wt% of nano iron oxide with a particle size of 20-50nm is added. The mixture is shaken at 30℃ and 120rpm for 48h, filtered through a 0.22μm filter membrane, washed with dilute sulfuric acid at pH 1.5, and dried at 50℃ for 2h to obtain surface-functionalized ore. S3. A 0.1 wt% solution of nano-iron oxide with a particle size of 20-50 nm is mixed with surface-functionalized ore at a mass ratio of 5:3 and added to a flotation cell filled with a dilute sulfuric acid solution of pH=1.5, a nano-bubble generator, and a titanium-based platinum-plated electrode as the anode and a nickel foam electrode as the cathode to form an electrochemical system. S4. The electrochemical flotation system is connected to a pulse power supply, with the pulse controlled at 50Hz. The flotation is carried out in three stages: the first stage has a current density of 15 mA / cm² and a potential gradient of 0.6V / cm for 8 min; the second stage has a potential gradient of 0.8V / cm for 12 min; and the third stage has a potential gradient of 1.0V / cm for 15 min. The flotation foam is collected by a scraper, and the copper and cobalt are filtered, dried, and weighed. Comparative Example 2

[0027] The difference between this comparative example and Example 2 is that no nano-iron oxide particles are added, as detailed below: S1. The ore is crushed to a fineness of ≥90% (200 mesh) by combining a jaw crusher and a ball mill. Then, a hydrocyclone is used to remove 10μm of slime to obtain deslimed ore. S2. Inoculate *Acidithiobacillus ferrooxidans* into the culture medium, with a bacterial density of 60%, and culture at 30℃ with shaking for 48 h to obtain *Acidithiobacillus ferrooxidans* culture medium with a pH of 1.5; the composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L; S3. The deslimed ore and the culture medium of *Thiobacillus ferrooxidans* were mixed at a mass ratio of 5:1, shaken at 30°C and 120 rpm for 48 h, filtered through a 0.22 μm filter membrane, washed with dilute sulfuric acid at pH 1.5, and dried at 50°C for 2 h to obtain the treated ore. S4. The culture medium of *Thiobacillus ferrooxidans* and the surface-functionalized ore were mixed at a mass ratio of 1:3 and added to a flotation cell filled with a dilute sulfuric acid solution of pH=1.5, a nanobubble generator, and a platinum-plated electrode with a titanium substrate as the anode and a nickel foam electrode as the cathode to form an electrochemical system. S5. The electrochemical flotation system is connected to a pulse power supply, with the pulse controlled at 50Hz. The flotation is carried out in three stages: the first stage has a current density of 15 mA / cm² and applies a potential gradient of 0.6V / cm for 8 min; the second stage has a potential gradient of 0.8V / cm for 12 min; and the third stage has a potential gradient of 1.0V / cm for 15 min. The flotation foam is collected by a scraper, and the copper and cobalt are filtered, dried, and weighed. Comparative Example 3

[0028] The difference between this comparative example and Example 2 is that the nano-iron oxide particles are replaced with a silver ion catalyst, as detailed below: S1. The ore is crushed to a fineness of ≥90% (200 mesh) by combining a jaw crusher and a ball mill. Then, a hydrocyclone is used to remove 10μm of slime to obtain deslimed ore. S2. Inoculate *Acidithiobacillus ferrooxidans* into the culture medium, with a bacterial density of 60%, and culture at 30℃ with shaking for 48 h to obtain *Acidithiobacillus ferrooxidans* culture medium with a pH of 1.5; the composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L; S3. The deslimed ore and the culture medium of *Thiobacillus ferrooxidans* were mixed at a mass ratio of 5:1, 0.1 wt% silver ion catalyst was added, and the mixture was shaken at 30°C and 120 rpm for 48 h. The mixture was then filtered through a 0.22 μm filter membrane, washed with dilute sulfuric acid at pH 1.5, and dried at 50°C for 2 h to obtain the surface-functionalized ore. S4. The culture medium of *Thiobacillus ferrooxidans*, 0.1 wt% silver ion catalyst solution and surface-functionalized ore are mixed at a mass ratio of 1:5:3 and added to a flotation cell filled with dilute sulfuric acid solution at pH=1.5, a nanobubble generator and a titanium-based platinum-plated electrode as the anode and a nickel foam electrode as the cathode to form an electrochemical system. S5. The electrochemical flotation system is connected to a pulse power supply, with the pulse controlled at 50Hz. The flotation is carried out in three stages: the first stage has a current density of 15 mA / cm² and applies a potential gradient of 0.6V / cm for 8 min; the second stage has a potential gradient of 0.8V / cm for 12 min; and the third stage has a potential gradient of 1.0V / cm for 15 min. The flotation foam is collected by a scraper, and the copper and cobalt are filtered, dried, and weighed. Comparative Example 4

[0029] The difference between this comparative example and Example 2 is that the nano-iron oxide particles are replaced with sodium dodecyl sulfate, as detailed below: S1. The ore is crushed to a fineness of ≥90% (200 mesh) by combining a jaw crusher and a ball mill. Then, a hydrocyclone is used to remove 10μm of slime to obtain deslimed ore. S2. Inoculate *Acidithiobacillus ferrooxidans* into the culture medium, with a bacterial density of 60%, and culture at 30℃ with shaking for 48 h to obtain *Acidithiobacillus ferrooxidans* culture medium with a pH of 1.5; the composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L; S3. The deslimed ore and the culture medium of *Thiobacillus ferrooxidans* were mixed at a mass ratio of 5:1, 0.1 wt% sodium dodecyl sulfate was added, and the mixture was shaken at 30°C and 120 rpm for 48 h. The mixture was then filtered through a 0.22 μm filter membrane, washed with dilute sulfuric acid at pH 1.5, and dried at 50°C for 2 h to obtain the surface-functionalized ore. S4. The culture medium of *Thiobacillus ferrooxidans*, 0.1 wt% sodium dodecyl sulfate solution and surface-functionalized ore are mixed at a mass ratio of 1:5:3 and added to a flotation cell filled with dilute sulfuric acid solution at pH=1.5, a nanobubble generator and a platinum-plated electrode with a titanium substrate as the anode and a nickel foam electrode as the cathode to form an electrochemical system. S5. The electrochemical flotation system is connected to a pulse power supply, with the pulse controlled at 50Hz. The flotation is carried out in three stages: the first stage has a current density of 15 mA / cm² and applies a potential gradient of 0.6V / cm for 8 min; the second stage has a potential gradient of 0.8V / cm for 12 min; and the third stage has a potential gradient of 1.0V / cm for 15 min. The flotation foam is collected by a scraper, and the copper and cobalt are filtered, dried, and weighed. Comparative Example 5

[0030] The difference between this comparative example and Example 2 is that it does not employ three-stage flotation, as detailed below: S1. The ore is crushed to a fineness of ≥90% (200 mesh) by combining a jaw crusher and a ball mill. Then, a hydrocyclone is used to remove 10μm of slime to obtain deslimed ore. S2. Inoculate *Acidithiobacillus ferrooxidans* into the culture medium, with a bacterial density of 60%, and culture at 30℃ with shaking for 48 h to obtain *Acidithiobacillus ferrooxidans* culture medium with a pH of 1.5; the composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L; S3. The deslimed ore and the culture medium of *Thiobacillus ferrooxidans* were mixed at a mass ratio of 5:1, and 0.1 wt% of nano-iron oxide with a particle size of 20-50 nm was added. The mixture was shaken at 30 °C and 120 rpm for 48 h, filtered through a 0.22 μm filter membrane, washed with dilute sulfuric acid at pH 1.5, and dried at 50 °C for 2 h to obtain the surface-functionalized ore. S4. A mixture of *Thiobacillus ferrooxidans* culture medium, 0.1 wt% of nano-iron oxide solution with a particle size of 20-50 nm, and surface-functionalized ore at a mass ratio of 1:5:3 is added to a flotation cell filled with a dilute sulfuric acid solution of pH=1.5, a nano-bubble generator, and a titanium-based platinum-plated electrode as the anode and a nickel foam electrode as the cathode to form an electrochemical system. S5. The electrochemical flotation system is connected to a pulse power supply, the pulse is controlled at 50Hz, the current density is 15 mA / cm², and a potential gradient of 0.6V / cm is applied for flotation for 35 minutes. The flotation foam is collected by a scraper, and the copper and cobalt are filtered, dried and weighed. Comparative Example 6

[0031] The difference between this comparative example and Example 2 lies in the current control of the three-stage flotation, which decreases from high to low, as detailed below: S1. The ore is crushed to a fineness of ≥90% (200 mesh) by combining a jaw crusher and a ball mill. Then, a hydrocyclone is used to remove 10μm of slime to obtain deslimed ore. S2. Inoculate *Acidithiobacillus ferrooxidans* into the culture medium, with a bacterial density of 60%, and culture at 30℃ with shaking for 48 h to obtain *Acidithiobacillus ferrooxidans* culture medium with a pH of 1.5; the composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L; S3. The deslimed ore and the culture medium of *Thiobacillus ferrooxidans* were mixed at a mass ratio of 5:1, and 0.1 wt% of nano-iron oxide with a particle size of 20-50 nm was added. The mixture was shaken at 30 °C and 120 rpm for 48 h, filtered through a 0.22 μm filter membrane, washed with dilute sulfuric acid at pH 1.5, and dried at 50 °C for 2 h to obtain the surface-functionalized ore. S4. A mixture of *Thiobacillus ferrooxidans* culture medium, 0.1 wt% of nano-iron oxide solution with a particle size of 20-50 nm, and surface-functionalized ore at a mass ratio of 1:5:3 is added to a flotation cell filled with a dilute sulfuric acid solution of pH=1.5, a nano-bubble generator, and a titanium-based platinum-plated electrode as the anode and a nickel foam electrode as the cathode to form an electrochemical system. S5. The electrochemical flotation system is connected to a pulse power supply, with the pulse controlled at 50Hz. The flotation is carried out in three stages: the first stage has a current density of 15 mA / cm² and applies a potential gradient of 1.0V / cm for 15 min; the second stage has a potential gradient of 0.8V / cm for 12 min; and the third stage has a potential gradient of 0.6V / cm for 8 min. The flotation foam is collected by a scraper, and the copper and cobalt are filtered, dried, and weighed. Comparative Example 7

[0032] The difference between this comparative example and Example 2 is that it does not use nano-iron oxide with a particle size greater than 50 nm, as detailed below: S1. The ore is crushed to a fineness of ≥90% (200 mesh) by combining a jaw crusher and a ball mill. Then, a hydrocyclone is used to remove 10μm of slime to obtain deslimed ore. S2. Inoculate *Acidithiobacillus ferrooxidans* into a culture medium containing 0.1 wt% of nano-iron oxide with a particle size of 60-100 nm, with a bacterial density of 60%. Incubate at 30°C with shaking for 48 h to obtain *Acidithiobacillus ferrooxidans* culture medium with a pH of 1.5. The composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L. S3. The deslimed ore and the culture medium of *Thiobacillus ferrooxidans* were mixed at a mass ratio of 5:1. 0.1 wt% of nano-iron oxide with a particle size of 60-100 nm was added. The mixture was shaken at 30 °C and 120 rpm for 48 h. The mixture was then filtered through a 0.22 μm filter membrane, washed with dilute sulfuric acid at pH 1.5, and dried at 50 °C for 2 h to obtain the surface-functionalized ore. S4. A culture medium of *Thiobacillus ferrooxidans*, 0.1 wt% of nano-iron oxide solution with a particle size of 60-100 nm, and surface-functionalized minerals are mixed at a mass ratio of 1:5:3 and added to a flotation cell filled with a dilute sulfuric acid solution of pH=1.5, a nano-bubble generator, and a titanium-based platinum-plated electrode as the anode and a nickel foam electrode as the cathode to form an electrochemical system. S5. The electrochemical flotation system is connected to a pulse power supply, with the pulse controlled at 50Hz. The flotation is carried out in three stages: the first stage has a current density of 15 mA / cm² and applies a potential gradient of 0.6V / cm for 8 min; the second stage has a potential gradient of 0.8V / cm for 12 min; and the third stage has a potential gradient of 1.0V / cm for 15 min. The flotation foam is collected by a scraper, and the copper and cobalt are filtered, dried, and weighed. Comparative Example 8

[0033] The difference between this comparative example and Example 2 is that no nano-iron oxide is added to the electrochemical flotation system, as detailed below: S1. The ore is crushed to a fineness of ≥90% (200 mesh) by combining a jaw crusher and a ball mill. Then, a hydrocyclone is used to remove 10μm of slime to obtain deslimed ore. S2. Inoculate *Acidithiobacillus ferrooxidans* into the culture medium, with a bacterial density of 60%, and culture at 30℃ with shaking for 48 h to obtain *Acidithiobacillus ferrooxidans* culture medium with a pH of 1.5; the composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L; S3. The deslimed ore and the culture medium of *Thiobacillus ferrooxidans* were mixed at a mass ratio of 5:1, and 0.1 wt% of nano-iron oxide with a particle size of 20-50 nm was added. The mixture was shaken at 30 °C and 120 rpm for 48 h, filtered through a 0.22 μm filter membrane, washed with dilute sulfuric acid at pH 1.5, and dried at 50 °C for 2 h to obtain the surface-functionalized ore. S4. The culture medium of *Thiobacillus ferrooxidans* and the surface-functionalized ore were mixed at a mass ratio of 1:3 and added to a flotation cell filled with a dilute sulfuric acid solution of pH=1.5, a nanobubble generator, and a platinum-plated electrode with a titanium substrate as the anode and a nickel foam electrode as the cathode to form an electrochemical system. S5. The electrochemical flotation system is connected to a pulse power supply, with the pulse controlled at 50Hz. The flotation is carried out in three stages: the first stage has a current density of 15 mA / cm² and applies a potential gradient of 0.6V / cm for 8 min; the second stage has a potential gradient of 0.8V / cm for 12 min; and the third stage has a potential gradient of 1.0V / cm for 15 min. The flotation foam is collected by a scraper, and the copper and cobalt are filtered, dried, and weighed. Performance testing

[0034] Yield, grade and recovery rate Weigh 0.1000 g of deslimed ore and place it in a 50 mL PTFE tube. Moisten the tube with a small amount of water, add 5 mL of HF, 5 mL of nitric acid, and 5 mL of hydrochloric acid. Place the tube in a heavy metal digester and digest at 120 °C for 4 h. Then add 5 mL of perchloric acid and digest at 160 °C for 4 h. Transfer the solution to a 25 mL volumetric flask and dilute to volume with 1% dilute nitric acid. Take a 5 mL sample for ICP determination. Determine the Cu and Co content in the digested and diluted solution.

[0035] The results are shown in Table 1. This invention significantly improves the separation efficiency of copper-cobalt ore using a synergistic process of microorganisms, nanomaterials, and electrochemistry. The examples show improvements in grade and recovery rate. Microbial density, pulse frequency, and oscillation reaction time all affect copper recovery rate and grade. The optimal example maintains a high cobalt recovery rate while keeping the copper grade at an excellent level, fully demonstrating the synergistic optimization effect of process parameters. The absence of nanomaterials (Comparative Example 2) significantly reduces the copper grade and lowers the recovery rate, proving that this invention achieves high-efficiency recovery through the dual effects of microbial metabolic modification and nanomaterial interface stabilization.

[0036] Table 1. Recovery rates and grades of copper and cobalt

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the technical solutions of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A method for recovering mixed copper-cobalt ore by microbial-assisted electrochemical flotation, characterized in that, Includes the following steps: S1. After crushing the ore, the slime is removed to obtain deslimed ore; S2. Inoculate *Thiobacillus ferrooxidans* into the culture medium and shake to obtain *Thiobacillus ferrooxidans* culture broth; S3. Mix the deslimed ore with the culture medium of *Thiobacillus ferrooxidans*, add nano-iron oxide, shake the reaction, filter through a filter membrane, wash with dilute sulfuric acid, and dry to obtain surface-functionalized ore; S4. An electrochemical system is formed by adding the culture medium of *Thiobacillus ferrooxidans*, nano-iron oxide and surface-functionalized minerals into a flotation cell filled with dilute sulfuric acid solution, a nano-bubble generator and electrodes. S5. The electrochemical flotation system is connected to a pulse power supply to control the pulse and current. The flotation is carried out in three stages. The flotation foam is collected by a scraper. Copper and cobalt are filtered, dried and weighed.

2. The method for recovering mixed copper-cobalt ore by microbial-assisted electrochemical flotation according to claim 1, characterized in that: In step S1, the ore crushing requirement is a fineness of ≥90% for 200 mesh, and the particle size of the removed slime is 5-10 μm.

3. The method for recovering mixed copper-cobalt ore by microbial-assisted electrochemical flotation according to claim 1, characterized in that: In step S2, the bacterial density of *Thiobacillus ferrooxidans* is 40-80%, and the pH of the culture medium is 1.

5. The composition of the culture medium is: (NH4)2SO4 3.0 g / L, KCl 0.1 g / L, K2HPO4 0.5 g / L, MgSO4·7H2O 0.5 g / L, Ca(NO3)2 0.01 g / L. The shaking culture temperature is 20-30℃, and the time is 24-72 h.

4. The method for recovering mixed copper-cobalt ore by microbial-assisted electrochemical flotation according to claim 1, characterized in that: In step S3, the nano-iron oxide has a particle size of 20-50 nm and a content of 0.1-0.3 wt%; the mass ratio of *Thiobacillus ferrooxidans* culture medium to deslimed ore is 1:(5-6); the bacterial density of *Thiobacillus ferrooxidans* is 40-80%; the shaking reaction temperature is 20-30℃, the rotation speed is 120 rpm, and the time is 24-72 h; the pore size of the filter membrane is 0.22 μm, and the pH of the dilute sulfuric acid is 1.5; the drying temperature is 50-70℃, and the time is 1-2 h.

5. The method for recovering mixed copper-cobalt ore by microbial-assisted electrochemical flotation according to claim 1, characterized in that: In step S4, the anode of the electrode is a platinum-plated titanium substrate electrode, and the cathode is a nickel foam electrode; the mass ratio of ferrooxidizobacterium ferrooxidans, nano-iron oxide solution and surface-functionalized ore is 1:5:(2-4); the pH of the dilute sulfuric acid solution is 1.5; and the concentration of the nano-iron oxide solution is 0.1wt%.

6. The method for recovering mixed copper-cobalt ore by microbial-assisted electrochemical flotation according to claim 1, characterized in that: The conditions for the three-stage flotation in step S5 are as follows: the first stage has a current density of 10-15 mA / cm² and a potential gradient of 0.5-0.7 V / cm for 6-8 min; the second stage has a potential gradient of 0.7-0.9 V / cm for 10-12 min; and the third stage has a potential gradient of 0.9-1.1 V / cm for 12-15 min.

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