System and method for extracting metal through gas-liquid-liquid three-phase back extraction

Abstract

The invention relates to a system and method for extracting metal through gas-liquid-liquid three-phase back extraction. The system comprises a back extraction device, a gas-liquid mixing device, a condensing device, a gas temporary storage device and an oil-water separation device. The system can improve the utilization rate of acid gas, reduce the consumption, reduce the cost and ensure long-term stable operation of the system; the entrained extraction agent can be recycled, and the loss of the extraction agent is reduced, so that the operation cost is reduced, and the emission of VOCs is reduced; and redundant unreacted gas is recycled, so that the emission of acid gas is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy, and particularly relates to a system and method for extracting metals by gas-liquid-liquid three-phase counter-extraction. Background Art

[0002] Solvent extraction is a process of separating or enriching substances by utilizing the difference in the distribution ratio of substances between an organic solution and an aqueous solution. In hydrometallurgy, it is commonly used to extract valuable metals from leaching solutions, dissolution solutions or salt lake solutions for separation and enrichment, mainly including three processes: extraction, washing, and counter-extraction. In the counter-extraction process, the organic solution loaded with valuable metals is adjusted through acid-base balance control, so that metal ions are redissolved into the aqueous phase for the preparation of metal salt products, and at the same time, it is ensured that the organic solvent no longer contains metal ions and can be reused in the extraction section to realize the recycling of the extractant. In the counter-extraction process, in order to dissolve the metal ions in the organic solution into the aqueous phase to the greatest extent, according to the properties of the extractant, the pH of the aqueous phase is controlled by acids and alkalis, resulting in the consumption and waste of acids and alkalis.

[0003] In recent years, with the development of solvent extraction technology, the gas-liquid-liquid three-phase CO2 counter-extraction method has been gradually applied to the counter-extraction of metal ions in organic solutions, such as the CO2 three-phase counter-extraction method for extracting lithium from salt lakes in Tibet, the CO2 three-phase counter-extraction method in rubidium- and cesium-containing solutions, etc. By introducing CO2 during the counter-extraction process to form H2CO3 and adjusting the pH of the aqueous phase, the counter-extraction of metals such as lithium, rubidium, and cesium is realized. This process does not require the use of acids, and the obtained solution can be directly concentrated at high temperature to obtain products, making this process green and economical.

[0004] CN117604248A discloses a gas-liquid-liquid three-phase counter-extraction pulsed column for extracting valuable metals, including a column body, a bottom enlarged section, a top enlarged section, a pulsed leg, a gas recovery device and a gas mixing device. By using a combination of baffle plates and sieve plates, the residence time of the gas phase is increased by the baffle plates, and the pulsed and sieve plates strengthen the redistribution of gas and liquid droplets. By regulating the gas partial pressure, the gas-liquid-liquid three-phase mass transfer rate is enhanced to achieve mass transfer enhancement, but the tail gas generated during the counter-extraction process is not easy to treat.

[0005] CN110306040A discloses a liquid-liquid-solid three-phase counter-extraction system, including a counter-extraction tank, an oil-water separator and a solid-liquid separation device. By improving the structure of the counter-extraction tank and adjusting the shape of the counter-extraction tank shell and the position of the oil-water phase outlet, the liquid-liquid-solid three-phase reaction system can be simply separated, and it can ensure that solids are discharged smoothly and there will be no solid residues at the extraction organic phase outlet, but the tail gas generated during the process cannot be treated.

[0006] In summary, for the three-phase counter-extraction system disclosed in the prior art, there are problems such as difficult treatment of tail gas, low utilization rate of the acidic gas used in the counter-extraction treatment, and inability to recover the extractant entrained by the gas. Therefore, there is an urgent need to develop a gas-liquid-liquid three-phase counter-extraction system for extracting metals, improve the utilization rate of acidic gas, reduce the operating cost, and reduce the loss of extractant. Summary of the Invention

[0007] To solve the above technical problems, the present invention provides a gas-liquid-liquid three-phase counter-extraction system and method for extracting metals. The system of the present invention can improve the utilization rate of acidic gas, reduce consumption, lower costs and ensure the long-term stable operation of the system; recover the entrained extractant, reduce the loss of extractant, thereby reducing the operating cost and reducing the emission of VOCs; at the same time, recycle the excess unreacted gas, thereby reducing the emission of acidic gas.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a gas-liquid-liquid three-phase counter-extraction system for extracting metals, the system comprising a counter-extraction device, a gas-liquid mixing device, a condensation device, a gas buffer device and an oil-water separation device;

[0010] The counter-extraction device includes a gas-liquid phase inlet, an oil phase inlet, an oil-water phase outlet and a gas phase outlet; the gas-liquid phase inlet is connected to the gas-liquid mixing device; the oil-water phase outlet is connected to the oil-water separation device; the gas phase outlet is connected to the condensation device;

[0011] The gas phase outlet of the condensation device is connected to the gas buffer device; the liquid phase outlet of the condensation device and the liquid phase outlet of the gas buffer device are both connected to the oil-water separation device.

[0012] In the system of the present invention, the liquid phase outlets of the condensation device and the gas buffer device are connected to the oil-water separation device to recover the extractant entrained by the gas, reduce the loss of extractant, thereby reducing the operating cost and reducing the emission of VOCs. In addition, the gas in the gas buffer device can also pass through a gas compression device for recycling, thereby reducing the emission of acidic gas.

[0013] It should be noted that the present invention does not make specific requirements and special limitations on the positions of the gas-liquid phase inlet, oil phase inlet, oil-water phase outlet, and gas phase outlet in the stripping device. The functions of the gas-liquid phase inlet, oil phase inlet, oil-water phase outlet, and gas phase outlet in the stripping device are to provide inlets for the gas phase, water phase, and organic phase, as well as outlets for the stripping phase and extraction phase. As long as the gas phase, water phase, and organic phase can be fully contacted and evenly mixed in the stripping device, for example, the gas-liquid phase inlet and the oil phase inlet can be arranged at the lower part of the stripping device, the oil-water phase outlet can be arranged in the middle of the stripping device, and the gas phase outlet can be arranged at the upper part of the stripping device. Therefore, it can be understood that the positions of the gas-liquid phase inlet, oil phase inlet, oil-water phase outlet, and gas phase outlet that can achieve the same technical effect can all be used in the present invention, and those skilled in the art can adaptively adjust the positions of the gas-liquid phase inlet, oil phase inlet, oil-water phase outlet, and gas phase outlet according to the structure of the specifically selected stripping device.

[0014] As a preferred technical solution of the present invention, the system includes an oil phase storage device, a gas phase storage device, and a water phase storage device;

[0015] The oil phase storage device is connected to the oil phase inlet through an oil phase transfer pump; the gas phase storage device is connected to the gas-liquid mixing device through a pipeline; the water phase storage device is connected to the gas-liquid mixing device through a dissolved gas pump.

[0016] In the present invention, the water phase storage device is connected to the gas-liquid mixing device through a dissolved gas pump. After passing through the dissolved gas pump, the water phase can form nano microbubbles, thereby increasing the solubility of the gas phase in the liquid phase and making the gas-liquid mixing more uniform.

[0017] As a preferred technical solution of the present invention, the system further includes a gas temporary storage device; the gas buffer device is connected to the gas temporary storage device through a gas compression device;

[0018] The gas temporary storage device is connected to the gas phase storage device through a pipeline.

[0019] In the present invention, the gas compression device is provided to increase the gas pressure, thereby recycling the reaction gas phase and reducing the emission of acidic gases.

[0020] As a preferred technical solution of the present invention, the stripping device includes any one of a multi-stage packed tower, a pulsed sieve plate tower, a rotating disk extraction tower, and a gas-liquid-liquid three-phase reactor.

[0021] Preferably, the stripping device includes a multi-stage packed tower; a gas distribution component and packing are arranged in the multi-stage packed tower.

[0022] Preferably, the gas distribution component includes a gas distributor.

[0023] Preferably, the packing includes random packing and structured packing; the random packing includes one of Raschig rings, Pall rings, Intalox saddles, conjugate rings or cascade rings; the structured packing includes corrugated plate packing or grid packing.

[0024] In the multi-stage packed tower of the present invention, the gas distribution component and the packing are arranged to increase the contact area between the extraction phase and the stripping phase, thereby improving the efficiency of the stripping process.

[0025] As a preferred technical solution of the present invention, the oil-water separation device is provided with an oil phase outlet and a water phase outlet.

[0026] In a second aspect, the present invention provides a method for gas-liquid-liquid three-phase back-extraction to extract metal, and the method is carried out by using the system described in the first aspect.

[0027] As a preferred technical solution of the present invention, the method includes: adding the material to be stripped through the oil phase inlet into the stripping device; after the acidic gas and pure water are mixed evenly in the gas-liquid mixing device, they are added into the stripping device through the gas-liquid phase inlet for stripping treatment to obtain an extraction phase and residual gas-phase material; the extraction phase enters the oil-water separation device through the oil-water phase outlet for oil-water separation to obtain an extractant; the residual gas-phase material is subjected to tail gas treatment through the gas phase outlet;

[0028] The tail gas treatment includes: after the residual gas-phase material passes through the condensation device, the first gas phase and the first oil phase are condensed; the first gas phase passes through the gas buffer device to obtain the second gas phase and the second oil phase; the first oil phase and the second oil phase respectively enter the oil-water separation device through pipelines.

[0029] As a preferred technical solution of the present invention, the acidic gas includes any one or a combination of at least two of CO2, HCl, SO3 or NO2.

[0030] As a preferred technical solution of the present invention, the pure water also passes through a dissolved air pump to form nano microbubbles before entering the gas-liquid mixing device.

[0031] As a preferred technical solution of the present invention, the tail gas treatment further includes: the second gas phase sequentially passes through a gas compression device and a gas temporary storage device and enters the gas storage device.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] (1) The present invention is provided with a dissolved air pump to form nano microbubbles in the water phase, increase the solubility of the acidic gas in the water phase, thereby improving the utilization rate of the acidic gas, reducing the consumption of the acidic gas, reducing costs and ensuring the long-term stable operation of the system;

[0034] (2) The present invention connects the liquid phase outlets of the condensation device and the gas buffer device to the oil-water separation device to recover the extractant entrained in the gas, reduce the loss of the extractant, thereby reducing the operating cost and the emission of VOCs;

[0035] (3) The present invention arranges the gas buffer device to be connected to the gas temporary storage device through the gas compression device to recycle the excess unreacted gas, thereby reducing the emission of acidic gas. Description of the Drawings

[0036] Figure 1 is a schematic structural diagram of a system for gas-liquid-liquid three-phase counter-extraction to extract metals according to the present invention.

[0037] Wherein, 1 - multi-stage packing tower; 2 - gas-liquid mixing device; 3 - condensation device; 4 - gas buffer device; 5 - oil-water separation device; 6 - oil phase storage device; 7 - oil phase transfer pump; 8 - gas phase storage device; 9 - water phase storage device; 10 - dissolved air pump; 11 - gas temporary storage device; 12 - gas compression device; 13 - gas-liquid phase inlet; 14 - oil phase inlet; 15 - oil-water phase outlet; 16 - gas phase outlet; 17 - water phase outlet; 18 - oil phase outlet. Detailed Embodiments

[0038] The technical solutions of the present invention will be further described below in conjunction with the drawings and through specific embodiments. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention is subject to the claims.

[0039] Example 1

[0040] This example provides a system for gas-liquid-liquid three-phase counter-extraction to extract metals, as Figure 1 shown. The system includes a counter-extraction device 1, a gas-liquid mixing device 2, a condensation device 3, a gas buffer device 4, and an oil-water separation device 5;

[0041] The counter-extraction device 1 includes a gas-liquid phase inlet 13, an oil phase inlet 14, an oil-water phase outlet 15, and a gas phase outlet 16; the gas-liquid phase inlet 13 is connected to the gas-liquid mixing device 2; the oil phase outlet 15 is connected to the oil-water separation device 5; the gas phase outlet 16 is connected to the condensation device 3;

[0042] The gas phase outlet of the condensation device 3 is connected to the gas buffer device 4; the liquid phase outlet of the condensation device 3 and the liquid phase outlet of the gas buffer device 4 are both connected to the oil-water separation device 5;

[0043] The system includes an oil-phase storage device 6, a gas-phase storage device 8, and an aqueous-phase storage device 9; the oil-phase storage device 6 is connected to the oil-phase inlet 14 through an oil-phase transfer pump 7; the gas-phase storage device 8 is connected to the gas-liquid mixing device 2 through a pipeline; the aqueous-phase storage device 9 is connected to the gas-liquid mixing device 2 through a dissolved gas pump 10;

[0044] The system further includes a gas temporary storage device 11; the gas buffer device 4 is connected to the gas temporary storage device 11 through a gas compression device 12; the gas temporary storage device 11 is connected to the gas-phase storage device 8 through a pipeline; the stripping device 1 includes a multi-stage packing tower; a gas distribution component and packing are arranged in the multi-stage packing tower; the packing is a Raschig ring; the gas distribution component is a gas distributor; the oil-water separation device 5 is provided with an aqueous-phase outlet 17 and an oil-phase outlet 18.

[0045] Application Example 1

[0046] This application example provides a method for extracting metals by gas-liquid-liquid three-phase back-extraction, and the method is carried out using the system described in Example 1.

[0047] The method includes: adding the material to be back-extracted into the stripping device through the oil-phase inlet; after the acidic gas and pure water are evenly mixed in the gas-liquid mixing device, they are added into the stripping device through the gas-liquid phase inlet for back-extraction treatment to obtain an extraction phase and residual gas-phase material; the extraction phase enters the oil-water separation device through the oil-water phase outlet for oil-water separation to obtain an extractant; the residual gas-phase material is subjected to tail gas treatment through the gas-phase outlet; the tail gas treatment includes: after the residual gas-phase material passes through the condensation device, the first gas phase and the first oil phase are condensed; the first gas phase passes through the gas buffer device to obtain the second gas phase and the second oil phase; the first oil phase and the second oil phase respectively enter the oil-water separation device through pipelines;

[0048] The acidic gas includes any one or a combination of at least two of CO2, HCl, SO3, or NO2; the pure water also passes through a dissolved gas pump to form nano microbubbles before entering the gas-liquid mixing device;

[0049] The tail gas treatment further includes: the second gas phase sequentially passes through the gas compression device and the gas temporary storage device and enters the gas-phase storage device.

[0050] In summary, the present invention provides a system and method for extracting metals by gas-liquid-liquid three-phase counter-extraction. The system of the present invention can improve the utilization rate of acidic gas, reduce consumption, lower costs and ensure the long-term stable operation of the system; recover the entrained extractant, reduce extractant loss, thereby reducing operating costs and reducing VOC emissions; at the same time, recycle the excess unreacted gas, thereby reducing the emission of acidic gas.

[0051] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A system for extracting metals by gas-liquid-liquid three-phase back-extraction, characterized in that, The system includes a stripping device, a gas-liquid mixing device, a condensing device, a gas buffer device, and an oil-water separation device; The stripping device includes a gas-liquid phase inlet, an oil phase inlet, an oil-water phase outlet, and a gas phase outlet; the gas-liquid phase inlet is connected to the gas-liquid mixing device; the oil-water phase outlet is connected to the oil-water separation device; the gas phase outlet is connected to the condensing device; The gas phase outlet of the condensing device is connected to the gas buffer device; the liquid phase outlet of the condensing device and the liquid phase outlet of the gas buffer device are both connected to the oil-water separation device.

2. The system according to claim 1, characterized in that, The system includes an oil phase storage device, a gas phase storage device, and a water phase storage device; The oil phase storage device is connected to the oil phase inlet through an oil phase transfer pump; the gas phase storage device is connected to the gas-liquid mixing device through a pipeline; the water phase storage device is connected to the gas-liquid mixing device through a dissolved air pump.

3. The system according to claim 1 or 2, characterized in that, The system further includes a gas temporary storage device; the gas buffer device is connected to the gas temporary storage device through a gas compression device; The gas temporary storage device is connected to the gas phase storage device through a pipeline.

4. The system according to any one of claims 1 to 3, characterized in that, The stripping device includes any one of a multi-stage packing tower, a pulsed sieve plate tower, a rotating disc extraction tower, and a gas-liquid-liquid three-phase reactor; Preferably, the stripping device includes a multi-stage packing tower; a gas distribution assembly and packing are arranged in the multi-stage packing tower; Preferably, the gas distribution assembly includes a gas distributor; Preferably, the packing includes random packing and structured packing; the random packing includes one of Raschig rings, Pall rings, Intalox saddles, conjugate rings, or cascade rings; the structured packing includes corrugated plate packing or grid packing.

5. The system according to any one of claims 1-4, characterized in that, The oil-water separation device is provided with an oil phase outlet and a water phase outlet.

6. A method for extracting metals by gas-liquid-liquid three-phase back extraction, characterized in that, The method is carried out using the system according to any one of claims 1-5.

7. The method according to claim 6, wherein The method includes: adding the material to be stripped through the oil phase inlet into the stripping device; after the acidic gas and pure water are evenly mixed in the gas-liquid mixing device, they are added into the stripping device through the gas-liquid phase inlet for stripping treatment to obtain an extraction phase and residual gas phase material; the extraction phase enters the oil-water separation device through the oil-water phase outlet for oil-water separation to obtain an extractant; the residual gas phase material is subjected to tail gas treatment through the gas phase outlet; The tail gas treatment includes: after the residual gas phase material passes through the condensing device, a first gas phase and a first oil phase are condensed; the first gas phase passes through the gas buffer device to obtain a second gas phase and a second oil phase; the first oil phase and the second oil phase respectively enter the oil-water separation device through pipelines.

8. The method according to claim 6 or 7, characterized in that, [[ID= 9. The method according to any one of claims 6-8, characterized in that, ​ 10. The method according to any one of claims 6-9, characterized in that, ​

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