Method and system for improving dump leaching efficiency of metal ore by using micro-nano bubbles

Abstract

The invention discloses a method and a system for improving heap leaching efficiency of metal ore by using micro-nano bubbles, which comprise the following steps: a) generating the micro-nano bubbles: installing a micro-reactor on a leachate conveying pipeline, introducing oxygen or air, and enabling the leachate to pass through the micro-reactor under a certain pressure to generate a leachate containing the micro-nano bubbles; b) conveying the gas-containing leachate: conveying the leachate containing the micro-nano bubbles to an ore dump leaching area, and enabling the leachate to be in full contact with the ore in the dump leaching process; and c) reinforcement of the dump leaching process: promoting leachate to permeate into fine gaps of ore particles by utilizing high permeability and high mass transfer characteristics of the micro-nano bubbles, enhancing the oxidation reaction and improving the leaching rate of metal. According to the method, the metal leaching rate is remarkably increased, the leaching time is shortened, the agent consumption is reduced, and remarkable economic benefits and environmental benefits are achieved.

Description

Technical Field

[0001] The present invention relates to the field of hydrometallurgy of mineral resources, and particularly to a method and system for improving the heap leaching efficiency of metal ores by using micro-nano bubbles. Background Art

[0002] Heap leaching is an economical and effective method for metal recovery, especially suitable for low-grade and large-scale metal ores. However, in the actual heap leaching process, there are problems such as low leaching efficiency, long leaching time, and high reagent consumption. This is mainly due to the complex occurrence state of valuable metals in the ore, the uneven pores and fissures of ore particles, and the poor permeability of the leaching solution in the ore heap, resulting in low mass transfer efficiency during the leaching process.

[0003] In recent years, as a new means of enhancing mass transfer, micro-nano bubble technology has achieved remarkable results in the fields of water treatment, flotation, etc. Due to their small size, large specific surface area, surface charge, and long lifespan in water, micro-nano bubbles can significantly improve the mass transfer efficiency at the liquid-solid interface. However, the application of micro-nano bubble technology to the heap leaching process of metal ores lacks systematic research and application.

[0004] Therefore, it is an urgent problem for those skilled in the art to provide a method and system that can improve the leaching rate of metals, shorten the leaching time, and reduce production costs. Summary of the Invention

[0005] In view of this, the present invention provides a method and system for improving the heap leaching efficiency of metal ores by using micro-nano bubbles.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A method for improving the heap leaching efficiency of metal ores by using micro-nano bubbles, comprising the following steps:

[0008] a) Generation of micro-nano bubbles: Install a micro-reactor on the leaching solution conveying pipeline, introduce oxygen or air, and pass the leaching solution through the micro-reactor under a certain pressure to generate a leaching solution containing micro-nano bubbles;

[0009] b) Transportation of the gas-containing leaching solution: Transport the leaching solution containing micro-nano bubbles to the ore heap leaching area to make it fully contact with the ore during the heap leaching process;

[0010] c) Enhancement of the heap leaching process: Utilize the high permeability and high mass transfer characteristics of micro-nano bubbles to promote the leaching solution to penetrate into the fine gaps of ore particles, enhance the oxidation reaction, and improve the leaching rate of metals.

[0011] Preferably, in step a), the microreactor generates micro-nano bubbles by means of porous media, jet cavitation or vortex cavitation, and the pressure range is 0.1 - 0.5 MPa.

[0012] Preferably, in step a), the leaching solution is a cyanide solution, a sulfuric acid solution or other leaching agents suitable for the target metal.

[0013] Preferably, the cyanide solution is used for gold ore leaching, the concentration of NaCN is 0.02% - 0.1%, and the dosage is 1 - 5 m 3 / ton of ore;

[0014] The sulfuric acid solution is used for copper ore leaching, the concentration of H2SO4 is 3 - 10%, and the dosage is 2 - 8 m 3 / ton of ore;

[0015] For the other leaching agents, such as the concentration of thiourea for gold ore leaching is 0.5 - 2.0%, and the concentration of ammonia water for copper ore leaching is 2 - 8%.

[0016] Preferably, in step b), the ore heap leaching area refers to the pre-treated metal ore stacking area, which includes the following parts:

[0017] Heap leaching base cushion layer: The bottom layer laid with anti-seepage material HDPE membrane or clay layer to prevent the leaching solution from leaking;

[0018] Ore heap body: A highly permeable ore heap formed by stacking ores in layers according to particle size, with a height usually of 3 - 10 meters;

[0019] Spraying area: The surface area of the ore heap covered by the leaching solution through the drip irrigation or spraying system;

[0020] Percolation collection area: The leaching solution collection ditch or pipeline system located below the heap leaching base cushion layer.

[0021] Preferably, the pretreatment is crushing, grading, and stacking;

[0022] The spraying rate is 5 - 15 L / m 2 ·h, preferably 8 - 12 L / m 2 ·h.

[0023] Preferably, in step b),

[0024] Heap leaching time: Adjusted according to the ore type and target metal content, usually 15 - 60 days;

[0025] Gold ore: 20 - 40 days;

[0026] Copper ore: 30 - 60 days.

[0027] Preferably, in step b),

[0028] The particle size of the ore is 0 - 50 mm, preferably 0 - 20 mm for gold ore and 0 - 30 mm for copper ore;

[0029] The metal content of the ore:

[0030] For gold ore: 0.5 - 3.0 g / t;

[0031] For copper ore: 0.3 - 1.5%.

[0032] A system for improving the heap leaching efficiency of metal ores using micro - nano bubbles, comprising: a leaching solution storage tank, a micro - reactor, a gas supply device, a conveying pipeline, and a heap leaching field; wherein,

[0033] The leaching solution storage tank: used for storing the leaching solution;

[0034] The micro - reactor: used for generating a leaching solution containing micro - nano bubbles;

[0035] The gas supply device: used for providing oxygen or air to the micro - reactor;

[0036] The conveying pipeline: used for transporting the gas - containing leaching solution to the heap leaching field;

[0037] The heap leaching field: used for placing the metal ore heap to be processed.

[0038] Preferably, the micro - reactor is installed on the leaching solution conveying pipeline.

[0039] The present invention has achieved the following technical effects compared with the prior art:

[0040] (1) Improving leaching efficiency: Micro - nano bubbles enhance the permeability and oxidation ability of the leaching solution, promote the dissolution of metals, and increase the leaching rate;

[0041] (2) Shortening the leaching time: The enhanced mass transfer process accelerates the reaction rate, promotes the internal and external diffusion processes of solutes in the leaching solution, and shortens the time to reach the target leaching rate;

[0042] (3) Reducing production costs: Due to the shortened leaching time and reduced consumption of reagents, the overall production cost is reduced;

[0043] (4) Environmental protection benefits: Reducing the usage and emissions of reagents, and reducing the impact on the environment;

[0044] (5) Improving oxidation ability: Micro - nano bubbles have a high specific surface area, can increase the solubility and mass transfer rate of oxygen in the leaching solution, and enhance the efficiency of the oxidation reaction;

[0045] (6) Broad application prospects and promotion value: It has simple operation and is applicable to the heap leaching process of various metal ores such as gold ore and copper ore, with broad application prospects and promotion value. Description of the Drawings

[0046] Figure 1 It is a flow chart of the present invention. Detailed Embodiments

[0047] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0048] As Figure 1 shown, the present invention discloses a method for improving the heap leaching efficiency of metal ores by using micro-nano bubbles, including the following steps:

[0049] a) Generation of micro-nano bubbles: Install a micro-reactor on the leaching solution conveying pipeline, introduce oxygen or air, and pass the leaching solution through the micro-reactor under a certain pressure to generate a leaching solution containing micro-nano bubbles;

[0050] b) Transportation of the gas-containing leaching solution: Transport the leaching solution containing micro-nano bubbles to the ore heap leaching area to make it fully contact with the ore during the heap leaching process;

[0051] c) Enhancement of the heap leaching process: Utilize the high permeability and high mass transfer characteristics of micro-nano bubbles to promote the infiltration of the leaching solution into the fine gaps of ore particles, enhance the oxidation reaction, and improve the leaching rate of metals.

[0052] In step a), the micro-reactor generates micro-nano bubbles by using a porous medium, jet cavitation or vortex cavitation method, and the pressure range is 0.1 - 0.5 MPa.

[0053] In step a), the leaching solution is a cyanide solution, a sulfuric acid solution or other leaching agents suitable for the target metal.

[0054] The cyanide solution is used for gold ore leaching, the concentration of NaCN is 0.02% - 0.1%, and the dosage is 1 - 5 m 3 / ton of ore;

[0055] The sulfuric acid solution is used for copper ore leaching, the concentration of H2SO4 is 3 - 10%, and the dosage is 2 - 8 m 3 / ton of ore;

[0056] For the other leaching agents, such as the concentration of thiourea for gold ore leaching is 0.5 - 2.0%, and the concentration of ammonia water for copper ore leaching is 2 - 8%.

[0057] In step b), the ore heap leaching area refers to the area where the pretreated metal ore is stacked, including the following parts:

[0058] Heap leaching base cushion layer: The bottom layer laid with anti-seepage material HDPE membrane or clay layer to prevent the leaching solution from leaking;

[0059] Ore heap body: A highly permeable ore heap formed by stacking ore in layers according to particle size, with a height usually of 3 - 10 meters;

[0060] Spraying area: The surface area of the ore heap covered by the leaching solution through drip irrigation or spraying system;

[0061] Percolation collection area: The leaching solution collection ditch or pipeline system located below the heap leaching base cushion layer.

[0062] The pretreatment is crushing, grading, and stacking;

[0063] The spraying rate is 5 - 15 L / m 2 ·h, preferably 8 - 12 L / m 2 ·h.

[0064] In step b), the heap leaching time: adjusted according to the ore type and the target metal content, usually 15 - 60 days;

[0065] For gold ore: 20 - 40 days;

[0066] For copper ore: 30 - 60 days.

[0067] In step b), the ore particle size is 0 - 50 mm, preferably 0 - 20 mm for gold ore and 0 - 30 mm for copper ore;

[0068] Ore metal content:

[0069] For gold ore: 0.5 - 3.0 g / t;

[0070] For copper ore: 0.3 - 1.5%.

[0071] The present invention also discloses a system for improving the heap leaching efficiency of metal ore by using micro-nano bubbles, including: a leaching solution storage tank, a micro-reactor, a gas supply device, a conveying pipeline, and a heap leaching field; wherein,

[0072] Leaching solution storage tank: Used to store the leaching solution;

[0073] Micro-reactor: Used to generate the leaching solution containing micro-nano bubbles;

[0074] Gas supply device: Used to provide oxygen or air for the micro-reactor;

[0075] Conveying pipeline: Used to convey the gas-containing leaching solution to the heap leaching field;

[0076] Heap leaching yard: used to place the metal ore heap to be processed.

[0077] The microreactor is installed on the leachate conveying pipeline.

[0078] Example 1: Application in the heap leaching process of gold ore

[0079] 1. Preparation work:

[0080] Ore preparation: Select low-grade gold ore with a gold content of 1.5 g / t, crush it to a particle size of 0 - 20 mm, stack it on the heap leaching site, and the stack height is 5 meters;

[0081] Leachate preparation: Prepare a sodium cyanide (NaCN) solution with a concentration of 0.05% as the leachate.

[0082] 2. Micro-nano bubble generation:

[0083] Equipment configuration: Install a microreactor on the leachate conveying pipeline, select the jet cavitation method, and the operating pressure is 0.3 MPa;

[0084] Gas supply: Use industrial pure oxygen, the gas supply pressure is 0.35 MPa, and the gas-liquid ratio is 1:20;

[0085] Generate gas-containing leachate: The leachate passes through the microreactor, fully contacts with oxygen, and generates a leachate containing high-concentration micro-nano oxygen bubbles.

[0086] 3. Heap leaching process:

[0087] Leachate spraying: Spray the gas-containing leachate evenly on the surface of the ore heap through the spraying system, and the spraying rate is 10 L / m 2 ·h;

[0088] Percolation collection: The leachate penetrates the ore heap under the action of gravity, dissolves gold, and is collected at the bottom of the heap;

[0089] Recycling: The collected rich liquid is sent to the gold recovery system, and the tail liquid is returned to the leachate storage tank for recycling after treatment.

[0090] 4. Result analysis:

[0091] Improved leaching rate: After 30 days of heap leaching, the leaching rate of gold reaches 85%, which is 10 percentage points higher than the traditional method;

[0092] Shortened leaching time: The time required to reach the same leaching rate is reduced by 20%;

[0093] Reduced cyanide consumption: The unit ore consumption of cyanide is reduced by 15%;

[0094] Example 2: Application in the heap leaching process of copper ore

[0095] 1. Preparation work:

[0096] Ore preparation: Select copper oxide ore with a copper content of 0.5%, crush it to a particle size of 0 - 30 mm, stack it on the heap leaching site, and the stack height is 6 meters;

[0097] Leaching solution preparation: Prepare a sulfuric acid solution with a concentration of 5% as the leaching solution.

[0098] 2. Micro - nano bubble generation:

[0099] Equipment configuration: Install a porous medium micro - reactor on the leaching solution conveying pipeline, and the operating pressure is 0.2 MPa;

[0100] Gas supply: Use air as the gas source, the gas supply pressure is 0.25 MPa, and the gas - liquid ratio is 1:15;

[0101] Generate gas - containing leaching solution: The leaching solution passes through the micro - reactor and is fully mixed with air to generate a leaching solution containing micro - nano bubbles.

[0102] 3. Heap leaching process:

[0103] Leaching solution spraying: Uniformly spray the gas - containing leaching solution on the copper ore heap, and the spraying rate is 8 L / m 2 ·h.

[0104] Percolation collection: The leaching solution penetrates the ore heap, dissolves copper, and is collected at the bottom of the heap;

[0105] Recycling: The collected rich solution is sent to the copper electrowinning recovery system, and the tail liquid is recycled after treatment.

[0106] 4. Result analysis:

[0107] Leaching rate improvement: After 40 days of heap leaching, the leaching rate of copper reaches 75%, which is 12 percentage points higher than the traditional method;

[0108] Acid consumption reduction: The unit ore consumption of sulfuric acid is reduced by 10%;

[0109] Environmental benefits: The pollutant concentration in the tail liquid is reduced, reducing the burden of tail liquid treatment.

[0110] Example 3: Heap leaching of copper sulfide ore (strengthened by adding thiourea)

[0111] Ore parameters:

[0112] Copper content 1.2% (copper sulfide), particle size 0 - 30 mm, stack height 7 meters.

[0113] Leaching solution preparation:

[0114] Sulfuric acid concentration 8% + thiourea 0.8% (composite leaching agent).

[0115] Micro-nano bubble generation:

[0116] Micro-reactor type: vortex cavitation, pressure 0.4 MPa, gas-liquid ratio 1:10 (oxygen).

[0117] Heap leaching process:

[0118] Spraying rate 12 L / m 2 ·h, leaching time 50 days.

[0119] Result: Copper leaching rate reaches 82% (65% for traditional method), acid consumption is reduced by 18%.

[0120] Example 4: Heap leaching of low-grade gold ore (thiourea replaces cyanide)

[0121] Ore parameters:

[0122] Gold content 0.8 g / t, particle size 0 - 15 mm, heap height 4 m.

[0123] Leaching solution preparation:

[0124] Thiourea concentration 1.5%, sulfuric acid concentration 0.5%.

[0125] Micro-nano bubble generation:

[0126] Micro-reactor type: porous ceramic, pressure 0.25 MPa, gas-liquid ratio 1:18 (air).

[0127] Heap leaching process:

[0128] Spraying rate 10 L / m 2 ·h, leaching time 35 days.

[0129] Result: Gold leaching rate reaches 78% (65% for traditional cyanidation method), thiourea consumption is reduced by 12%. The influence of different leaching agent concentrations on gold leaching rate is shown in Table 1;

[0130] Table 1:

[0131]

[0132] Through the above examples, it can be seen that the present invention utilizes micro-nano bubble technology, significantly improves the leaching efficiency, shortens the leaching time, reduces the reagent consumption, and has significant economic and environmental benefits in the heap leaching process of metal ores.

[0133] As described above, this is only a preferred embodiment of the present invention and does not impose any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for improving the heap leaching efficiency of metal ores by using micro-nano bubbles, characterized in that, It includes the following steps: a) Generation of micro-nano bubbles: Install a micro-reactor on the leaching solution conveying pipeline, introduce oxygen or air, and pass the leaching solution through the micro-reactor under a certain pressure to generate a leaching solution containing micro-nano bubbles; b) Transportation of the gas-containing leaching solution: Transport the leaching solution containing micro-nano bubbles to the ore heap leaching area to make it fully contact with the ore during the heap leaching process; c) Enhancement of the heap leaching process: Utilize the high permeability and high mass transfer characteristics of micro-nano bubbles to promote the leaching solution to penetrate into the fine gaps of ore particles, enhance the oxidation reaction, and improve the leaching rate of metals.

2. The method for improving the heap leaching efficiency of metal ores by using micro-nano bubbles according to claim 1, characterized in that, In step a), the micro-reactor generates micro-nano bubbles by means of porous media, jet cavitation or vortex cavitation, and the pressure range is 0.1 - 0.5 MPa.

3. A method for improving the heap leaching efficiency of metal ores by using micro-nano bubbles according to claim 1, characterized in that, In step a), the leaching solution is a cyanide solution, a sulfuric acid solution or other leaching agents suitable for the target metal.

4. A method for improving the heap leaching efficiency of metal ores by using micro-nano bubbles according to claim 3, characterized in that, The cyanide solution is for gold ore leaching, with the NaCN concentration being 0.02% - 0.1% and the dosage being 1 - 5 m 3 / ton of ore; The sulfuric acid solution is for copper ore leaching, with an H2SO4 concentration of 3-10% and a dosage of 2-8 m 3 / ton of ore; For the other leaching agents, such as the concentration of thiourea for gold ore leaching is 0.5 - 2.0%, and the concentration of ammonia water for copper ore leaching is 2 - 8%.

5. A method for improving the heap leaching efficiency of metal ores by using micro-nano bubbles according to claim 1, characterized in that, In step b), The ore heap leaching area refers to the stacked area of pretreated metal ore, which includes the following parts: Heap leaching base cushion layer: The bottom layer laid with anti-seepage material HDPE membrane or clay layer to prevent the leaching solution from leaking; Ore heap body: A highly permeable ore heap formed by stacking ore in layers according to particle size, with a height usually of 3 - 10 meters; Spraying area: The surface area of the ore heap covered by the leaching solution through a drip irrigation or spraying system; Percolation collection area: The leaching solution collection ditch or pipeline system located below the heap leaching base cushion layer.

6. A method for improving the heap leaching efficiency of metal ores by using micro-nano bubbles according to claim 5, characterized in that, The pretreatment is crushing, grading, and stacking; The spraying rate is 5 - 15 L / m 2 ·h, preferably 8 - 12 L / m 2 ·h.

7. A method for improving the heap leaching efficiency of metal ores by using micro-nano bubbles according to claim 1, characterized in that, In step b), Heap leaching time: Adjusted according to the ore type and the target metal content, usually 15 - 60 days; For gold ore: 20 - 40 days; For copper ore: 30 - 60 days.

8. A method for improving the heap leaching efficiency of metal ores by using micro-nano bubbles according to claim 1, characterized in that In step b), The ore particle size is 0 - 50 mm, preferably 0 - 20 mm for gold ore, and preferably 0 - 30 mm for copper ore; Ore metal content: For gold ore: 0.5 - 3.0 g / t; For copper ore: 0.3 - 1.5%.

9. A system for improving the heap leaching efficiency of metal ores by using micro-nano bubbles, characterized in that, It includes: A leaching solution storage tank, a micro-reactor, a gas supply device, a conveying pipeline, and a heap leaching field; among them, The leaching solution storage tank: Used to store the leaching solution; The micro-reactor: Used to generate a leaching solution containing micro-nano bubbles; The gas supply device: Used to provide oxygen or air for the micro-reactor; The conveying pipeline: Used to transport the gas-containing leaching solution to the heap leaching field; The heap leaching field: Used to place the metal ore heap to be treated.

10. A system for improving the heap leaching efficiency of metal ores by using micro-nano bubbles according to claim 9, characterized in that, The micro-reactor is installed on the leaching solution conveying pipeline.

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