A system for recovering metal ions from acid solutions

Abstract

This invention discloses a system for recovering metal ions from acidic solutions. The system includes a hydrogen sulfide preparation device, a purification device, and a solid-liquid separation device. The hydrogen sulfide preparation device includes a bioreactor and an environmental control component. The bioreactor contains a reaction chamber, and the environmental control component regulates the conditions within the reaction chamber to maintain microbial activity and generate hydrogen sulfide gas. The purification device includes a gas-liquid contact reactor, into which acidic wastewater is fed, allowing hydrogen sulfide-containing gas to mix with the acidic wastewater. Unreacted hydrogen sulfide-containing gas is returned to the bioreactor. The solid-liquid separation device includes a precipitator, which receives the mixed wastewater and separates the metal sulfides generated in the wastewater from the liquid phase. This invention utilizes on-site biological preparation of inexpensive hydrogen sulfide to replace purchased reagents, achieving selective recovery and resource utilization of valuable metals while efficiently and safely removing heavy metals from wastewater.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment and resource recovery technology, and in particular to a system for recovering metal ions from acid solutions. Background Technology

[0002] Many industrial sectors, such as metallurgy, mining, electroplating, and electronic component manufacturing, generate large quantities of acidic wastewater containing heavy metals, such as acid mine wastewater (AMD) and smelting wastewater. This type of wastewater typically contains copper (Cu²⁺). + ), Zinc (Zn²) + ), lead (Pb²) + ), cadmium (Cd² + High concentrations of metal ions with recycling value, if not properly handled, will pose a serious threat to the ecological environment and human health, and will also cause the loss of valuable metal resources.

[0003] In related technologies, the industrial treatment of acidic heavy metal wastewater mainly relies on neutralization precipitation, which involves adding alkaline agents (such as lime) to cause metal ions to precipitate as hydroxides. However, this method suffers from significant drawbacks, including poor selectivity, co-precipitation of multiple metal hydroxides leading to difficulties in resource recovery, low precipitation efficiency, insufficient stability resulting in easy back-dissolution, large sludge production and high disposal costs, and high reagent consumption leading to high operating costs. Although sulfide precipitation is recognized as having superior theoretical performance due to its more thorough precipitation, better settling and dewatering properties, and potential for stepwise precipitation, its large-scale engineering application has long been severely limited by core bottlenecks such as the high procurement cost of commercial sulfiding agents (such as sodium sulfide), the inconvenience and danger of transportation and storage, and the complexity of on-site chemical preparation. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, embodiments of the present invention propose a system for the recovery of metal ions from acidic solutions, which integrates a closed-loop system of biogas production and chemical precipitation. By using inexpensive hydrogen sulfide produced on-site to replace purchased reagents, the system can efficiently and safely remove heavy metals from wastewater while achieving selective recovery and resource utilization of valuable metals. This solves the problems of high cost, poor selectivity, large sludge volume, and high operational risk associated with traditional methods.

[0006] The system for recovering metal ions from acid solutions according to embodiments of the present invention includes:

[0007] A hydrogen sulfide preparation apparatus includes a bioreactor, an environmental control component, and a gas circulation component. The bioreactor has a reaction chamber for containing hydrogen sulfide-producing microbial communities and reaction liquid. The bioreactor is equipped with a feed pipe connected to the reaction chamber. The environmental control component is connected to the bioreactor and is used to control the reaction conditions in the reaction chamber to maintain microbial activity and generate hydrogen sulfide gas. The gas circulation component includes a gas output pipe and a gas return pipe respectively connected to the reaction chamber. A purification treatment device includes a gas-liquid contact reactor. The gas-liquid contact reactor is equipped with a wastewater delivery pipe and a treated water discharge pipe. Acidic wastewater is delivered to the gas-liquid contact reactor through the wastewater delivery pipe. The gas-liquid contact reactor is connected to a bioreactor through a gas output pipe to receive hydrogen sulfide-containing gas, allowing the introduced hydrogen sulfide-containing gas to contact and mix with the flowing acidic wastewater. The mixed wastewater is discharged through the treated water discharge pipe. The gas-liquid contact reactor is connected to the bioreactor through a gas return pipe to return unreacted hydrogen sulfide-containing gas to the bioreactor. A solid-liquid separation device includes a precipitator, which is equipped with a recovery pipe and an outlet pipe. The precipitator is connected to the gas-liquid contact reactor through the treated water discharge pipe to receive the mixed wastewater, so that the metal sulfide precipitate generated in the wastewater is separated from the liquid phase and discharged through the recovery pipe. The supernatant in the precipitator is discharged through the outlet pipe.

[0008] In some embodiments, the environmental control component includes a heat exchanger and a circulation pump. The heat exchanger is connected to the reaction chamber via a pipeline to form a heat exchange circulation loop. The circulation pump is located on the heat exchange circulation loop. The heat exchanger is externally connected to a cooling water and / or hot water circulation system. The temperature inside the reaction chamber is controlled within a preset range by the heat exchanger to ensure the activity of microorganisms.

[0009] In some embodiments, the environmental control component further includes a feed pipe connected to the heat exchange circulation loop or the reaction chamber. The feed pipe is used to add carbon sources, nutrients, and pH adjusters to maintain the nutrient conditions and pH range required for the biological reaction.

[0010] In some embodiments, the environmental control component further includes a drain pipe connected to the heat exchange circulation loop or the reaction chamber, and is equipped with a controlled valve for periodically draining a portion of the reaction liquid to control salt accumulation.

[0011] In some embodiments, the environmental control component further includes an online monitoring instrument, which is located on the heat exchange circulation loop and is used to continuously monitor at least one parameter among pH, temperature and conductivity within the reaction chamber.

[0012] In some embodiments, the gas circulation assembly further includes a circulation fan, which is disposed on the gas output pipe and / or the gas return pipe, for driving the gas to circulate between the hydrogen sulfide preparation device and the purification treatment device.

[0013] In some embodiments, the system integrates a control unit, which adjusts the operation of the gas circulation component based on the process parameters within the gas-liquid contact reactor to control the flow rate of hydrogen sulfide-containing gas supplied to the gas-liquid contact reactor in real time, thereby achieving selective or stepwise precipitation of different metal ions.

[0014] In some embodiments, the connection between the gas output pipe and the bioreactor is located at the top of the bioreactor, the connection between the gas output pipe and the gas-liquid contact reactor is located at the bottom of the gas-liquid contact reactor, the connection between the gas return pipe and the bioreactor is located at the bottom of the bioreactor, and the connection between the gas return pipe and the gas-liquid contact reactor is located at the top of the gas-liquid contact reactor.

[0015] In some embodiments, the gas-liquid contact reactor is equipped with a stirring assembly to ensure that the hydrogen sulfide-containing gas and the acidic wastewater are fully contacted and mixed.

[0016] In the embodiments of this invention, a closed-loop treatment system of on-site biological gasification, precise chemical precipitation, and gas recirculation was constructed. This system solves the problems of low precipitation efficiency, poor selectivity, and high sludge disposal costs in the traditional lime process, and also addresses the high cost and high risk associated with relying on purchased commercial sulfiding agents. The system can stably and efficiently remove heavy metal ions from acidic wastewater, producing large metal sulfide precipitates with excellent dewatering performance, significantly reducing sludge volume. Simultaneously, through the intelligent control unit's linkage adjustment of process parameters (such as pH and redox potential) and hydrogen sulfide gas flow rate, selective or stepwise precipitation of different metal ions is achieved, enabling high-grade recovery and resource utilization of valuable metals. This system boasts significant advantages in terms of safe operation, strong adaptability, and low overall cost. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a system for recovering metal ions from acid solutions according to an embodiment of the present invention.

[0018] Figure label: 10-Make-up water pipe; 11-Bioreactor; 12-Feed pipe; 13-Heat exchanger; 14-Circulation pump; 15-Feeding pipe; 16-Drain pipe; 17-Gas output pipe; 18-Gas return pipe; 19-Circulation fan; 21-Gas-liquid contact reactor; 22-Wastewater conveying pipe; 23-Treatment water discharge pipe; 24-Agitator assembly; 31-Sedimenter; 32-Recovery pipe; 33-Outlet pipe. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] The system for recovering metal ions from acid solutions according to embodiments of the present invention is described below with reference to the accompanying drawings.

[0021] like Figure 1 As shown, the system for recovering metal ions from acidic solutions according to an embodiment of the present invention includes a hydrogen sulfide preparation device, a purification device, and a solid-liquid separation device.

[0022] The hydrogen sulfide production apparatus includes a bioreactor 11, an environmental control component, and a gas circulation component. The bioreactor 11 contains a reaction chamber for housing hydrogen sulfide-producing microorganisms and the reaction solution, and a feed pipe 12 communicating with the reaction chamber. The environmental control component is connected to the bioreactor 11 and is used to regulate the reaction conditions within the reaction chamber to maintain microbial activity and generate hydrogen sulfide gas. The gas circulation component includes a gas output pipe and a gas return pipe, both communicating with the reaction chamber.

[0023] By adding elemental sulfur, carbon source, and nutrients into the reaction chamber, sulfur is reduced to hydrogen sulfide gas under the biocatalytic action of hydrogen sulfide-producing microbial communities (such as sulfate-reducing bacteria). This process occurs independently of the acidic wastewater to be treated. The growth environment (temperature, pH, nutrients) of the microorganisms is precisely controlled by environmental control components, unaffected by fluctuations in influent water quality or heavy metal toxicity. The generated hydrogen sulfide gas is supplied downstream through a gas output pipe, while unreacted gas is returned through a gas return pipe, forming an internal gas circulation.

[0024] The hydrogen sulfide preparation device uses inexpensive elemental sulfur as raw material to continuously produce hydrogen sulfide gas on-site through a biological method, replacing the need to purchase high-cost and high-risk commercial reagents such as sodium sulfide. This fundamentally solves the problems of high procurement costs and dangerous and inconvenient transportation and storage in related technologies.

[0025] The purification and treatment device includes a gas-liquid contact reactor 21, which is equipped with a wastewater delivery pipe 22 and a treated water discharge pipe 23. Acidic wastewater is delivered to the gas-liquid contact reactor 21 through the wastewater delivery pipe 22. The gas-liquid contact reactor 21 is connected to the bioreactor 11 through a gas output pipe to receive hydrogen sulfide gas, so that the introduced hydrogen sulfide gas comes into contact with and mixes with the flowing acidic wastewater. The mixed wastewater is discharged through the treated water discharge pipe 23. The gas-liquid contact reactor 21 is connected to the bioreactor 11 through a gas return pipe to return unreacted hydrogen sulfide gas to the bioreactor 11.

[0026] The gas-liquid contact reactor 21 is the core unit for achieving chemical precipitation, and its technical principle is gas-liquid mass transfer and chemical reaction. Hydrogen sulfide gas from bioreactor 11 and acidic wastewater entering through wastewater delivery pipe 22 are thoroughly mixed and contacted within the reactor. The hydrogen sulfide gas dissolves in water and ionizes into sulfur ions. These sulfur ions react rapidly with heavy metal ions in the wastewater to form corresponding metal sulfide precipitates. The resulting mixture then enters subsequent units.

[0027] The solid-liquid separation device includes a precipitator 31, which is equipped with a recovery pipe 32 and an outlet pipe 33. The precipitator 31 is connected to the gas-liquid contact reactor 21 through the treated water discharge pipe 23 to receive the mixed wastewater, so that the metal sulfide precipitates generated in the wastewater are separated from the liquid phase and discharged through the recovery pipe 32. The supernatant in the precipitator 31 is discharged through the outlet pipe 33.

[0028] The sedimentation tank 31 separates solids and liquids based on the principle of gravity settling. After the mud-water mixture containing metal sulfide precipitate particles from the gas-liquid contact reactor 21 enters the sedimentation tank 31, under relatively static or slow flow conditions, the denser metal sulfide particles gradually settle to the bottom of the tank under the action of gravity to form sludge, while the clarified supernatant is located in the upper layer.

[0029] The precipitator 31 separates the generated metal sulfide precipitate from the treated water and discharges it through the recovery pipe 32, becoming valuable metal concentrate or easily disposed solid waste. Simultaneously, the metal sulfide precipitate itself has the characteristics of large particles, strong hydrophobicity, and fast settling velocity, resulting in high separation efficiency and a much smaller volume of sludge compared to the hydroxide sludge produced by the lime process. Furthermore, the separated supernatant is discharged through the effluent pipe 33, achieving the purpose of wastewater purification.

[0030] This invention relates to a system for recovering metal ions from acidic solutions. A hydrogen sulfide preparation device stably produces hydrogen sulfide gas under optimized biological conditions. This gas is then transported to a purification unit, where it reacts with continuously flowing acidic wastewater to generate metal sulfide precipitates. Subsequently, the wastewater carrying the precipitates enters a solid-liquid separation unit to separate the precipitates from the purified water. Simultaneously, any unconsumed hydrogen sulfide gas in the purification unit is recovered and returned to the bioreactor 11 to participate in the next cycle. The entire system achieves the input of materials (sulfur, wastewater), the output of valuable products (metal sulfides, purified water), and the internal circulation of the gaseous medium.

[0031] Therefore, the system for recovering metal ions from acidic solutions according to this invention, by using on-site biological preparation of hydrogen sulfide gas to replace commercial sulfiding agents, overcomes cost and safety bottlenecks, providing an economic basis for the large-scale application of the superior sulfide precipitation method. Combining the natural advantages of thorough removal and good sludge settling and dewatering properties of the sulfide precipitation method, it significantly improves treatment efficiency and reduces the burden of sludge disposal. The high purity of the metal sulfide precipitates produced by the system creates favorable conditions for the subsequent resource recovery of valuable metals.

[0032] Furthermore, by connecting the biological and chemical processes through gas pipelines while decoupling their functions, both processes can be independently optimized and controlled, resulting in a more stable and controllable system operation. This lays the foundation for the system architecture of fine-tuning the process (such as achieving selective precipitation).

[0033] In some embodiments, such as Figure 1 As shown, the environmental control components include a heat exchanger 13 and a circulation pump 14. The heat exchanger 13 is connected to the reaction chamber via a pipeline to form a heat exchange circulation loop. The circulation pump 14 is located on the heat exchange circulation loop. The heat exchanger 13 controls the temperature in the reaction chamber within a preset range to ensure the activity of microorganisms.

[0034] Heat exchanger 13 serves as a heat exchange interface, with one side in contact with the reaction liquid and the other side flowing with cooling water or hot water supplied by an external system. The system starts working when the temperature of the reaction liquid deviates from the preset range due to the exothermic reaction of microbial metabolism or the influence of ambient temperature.

[0035] Circulation Drive and Heat Distribution: The circulation pump 14 serves as the power source, driving the reaction liquid to continuously flow in a closed loop consisting of the reaction chamber → pipeline → heat exchanger 13 → pipeline → reaction chamber. When flowing through the heat exchanger 13, the reaction liquid and the heat exchange medium (cooling water / hot water) exchange heat efficiently through the wall of the heat exchanger 13.

[0036] When cooling is required, cooling water is introduced, and the heat of the reaction liquid is carried away, thus lowering the temperature. When heating or maintaining the temperature is required, hot water is introduced, and the heat is transferred to the reaction liquid, raising its temperature or maintaining it at a suitable level.

[0037] This hardware, in conjunction with a temperature sensor and an automatic control valve, forms a closed-loop temperature control system. The sensor monitors the reaction solution temperature in real time and feeds the signal back to the controller. The controller precisely controls the heat exchange by adjusting the speed of the circulating pump 14 (controlling the flow rate) and / or adjusting the valves on the external water supply pipeline (controlling the temperature and flow rate of the heat exchange medium), thereby dynamically stabilizing the reaction temperature within the preset optimal range.

[0038] In the embodiments of the present invention, the temperature is stably controlled within the optimal range (such as 30-40°C for mesophilic bacteria), ensuring that the microbial community is in a highly active state, thereby guaranteeing the stability and high yield of hydrogen sulfide generation rate and avoiding the decrease in yield or microbial dormancy caused by temperature fluctuations.

[0039] The device itself does not have a built-in chiller or heater, but is designed with standard interfaces for easy connection to the common utility networks in industrial sites. Cooling water usually comes from a cooling tower system (approximately 25-32°C), while hot water can come from a boiler system or waste heat recovery system (approximately 50-80°C).

[0040] For example, in summer or when the reaction is highly exothermic: the cooling water circulation mode is mainly used to continuously remove the excess heat generated by the reaction and metabolism to prevent overheating.

[0041] When starting up in winter or when the ambient temperature is low: the hot water circulation mode is mainly used to provide the initial heat source and maintain heat for the reactor, ensuring rapid start-up and stable operation.

[0042] In some embodiments, such as Figure 1 As shown, the environmental control component also includes a feed pipe 15, which is connected to a heat exchange circulation loop or a reaction chamber. The feed pipe 15 is used to add carbon sources, nutrients and pH adjusters to maintain the nutritional conditions and pH range required for the biological reaction.

[0043] Driven by the circulating pump 14, the reaction liquid flows at high speed in the heat exchange circuit. By placing the feed point here, the high-speed liquid flow can be used as a high-efficiency mixer to ensure that the added carbon source, nutrients or alkali solution can be quickly and evenly dispersed throughout the reaction chamber, avoiding excessively high local concentrations that could impact microorganisms or create dead sedimentation zones.

[0044] Carbon sources and nutrients are added to provide food for microbial growth and sulfur reduction reactions. They are typically added continuously or intermittently based on preset flow rates or indirect parameters such as the rate of sulfide formation and ORP (oxidation-reduction potential) within the reactor to maintain stable substrate concentrations.

[0045] When alkali solution is added, the process of microorganisms producing hydrogen sulfide will generate acidic substances (such as H2S dissolving in water to form HS). - and H+ This causes the pH to drop. The feed pipe 15 is used to add alkaline solutions (such as NaOH or Na2CO3 solutions). Its addition is linked to the online pH sensor, forming a closed-loop pH control circuit. When the pH sensor detects that the pH value is below the set lower limit (e.g., 6.0), the controller automatically opens the alkaline feed valve, injecting an appropriate amount of alkaline solution through the feed pipe 15 until the pH returns to the optimal range (e.g., 6.5-8.0).

[0046] Furthermore, such as Figure 1 As shown, the environmental control component also includes a drain pipe 16, which is connected to the heat exchange circulation loop or the reaction chamber and is equipped with a controlled valve for periodically draining a portion of the reaction liquid to control salt accumulation. Its operation is controlled by a liquid level sensor and an automatic control valve.

[0047] Microbial metabolism and alkali addition lead to the gradual accumulation of salts such as sodium and sulfate ions in the reaction solution. Conductivity is a reliable indicator of total dissolved solids (TDS) or salt concentration. When the conductivity sensor detects a value exceeding a preset safety threshold (indicating that salt accumulation may begin to inhibit microbial activity), the valve on the makeup water pipe 10 automatically opens to dilute and reduce the salt concentration. As the reactor liquid level rises, the valve on the drain pipe 6 automatically opens to maintain the liquid level within the normal range.

[0048] For example, when the hydrogen sulfide preparation unit is operating under normal steady-state conditions, the feed pipe 15 continuously or intermittently adds carbon sources (such as high-concentration organic wastewater) and nutrients (such as N and P) according to a preset rate; based on feedback from the pH sensor, it automatically adds small amounts of alkaline solution frequently to maintain pH stability. The drain pipe 16 is in standby mode at this time. The conductivity rises slowly but does not reach the threshold.

[0049] When the hydrogen sulfide preparation unit is in salinity control mode, the conductivity sensor triggers a high-limit alarm, and the valve on the water supply pipe 10 automatically opens to dilute and reduce the salinity concentration. As the reactor liquid level rises, the valve on the drain pipe 6 automatically opens to maintain the liquid level within the normal range.

[0050] When the hydrogen sulfide preparation unit is in start-up or shock recovery mode, during system startup, the feed pipe 15 is responsible for adding sufficient carbon source, nutrients, and alkali solution in one go or in batches to quickly adjust the reaction conditions to the optimal range.

[0051] Therefore, the feed pipe 15, the water supply pipe 10, and the drain pipe 16 correspond to the input and output management of the reactor, respectively. The feed pipe 15 is responsible for precise supply to maintain reaction kinetics and chemical balance; the water supply pipe 10 and the drain pipe 16 are responsible for periodic purification to prevent chronic poisoning and aging of the system. Through online monitoring data linkage, the two achieve fully automatic and intelligent maintenance of the internal chemical environment of the reactor.

[0052] In some embodiments, the environmental control component further includes an online monitoring instrument (not shown in the figure), which is located on the heat exchange circulation loop and is used to continuously monitor at least one parameter among pH, temperature and conductivity in the reaction chamber.

[0053] In some embodiments, the gas circulation assembly further includes a circulation fan 19, which is disposed on the gas output pipe and / or gas return pipe for driving the gas to circulate between the hydrogen sulfide preparation device and the purification treatment device.

[0054] That is, the circulating fan 19 can be installed only on the gas output pipe, downstream of the hydrogen sulfide preparation device (bioreactor 11) and upstream of the purification device (gas-liquid contact reactor 21); the circulating fan 19 can also be installed only on the gas return pipe, downstream of the purification device (gas-liquid contact reactor 21) and upstream of the hydrogen sulfide preparation device (bioreactor 11). Alternatively, circulating fans 19 can be installed on both the gas output pipe and the gas return pipe.

[0055] Understandably, the circulating fan 19 provides the necessary pressure difference and gas flow rate for the entire closed gas circulation pipeline, overcomes the resistance generated by components such as pipes, reactors, and valves, and ensures that hydrogen sulfide-containing gas can be stably transported from the bioreactor 11 to the gas-liquid contact reactor 21, and effectively transports unreacted waste gas from the gas-liquid contact reactor 21 back to the bioreactor 11.

[0056] Furthermore, the system for recovering metal ions from acid in this embodiment of the invention integrates a control unit. The control unit adjusts the operation of the gas circulation component according to the process parameters in the gas-liquid contact reactor 21 to control the flow rate of hydrogen sulfide gas supplied to the gas-liquid contact reactor 21 in real time, so as to achieve selective or stepwise precipitation of different metal ions.

[0057] The control unit continuously and in real-time collects key process parameters reflecting the precipitation reaction progress using online sensors (such as pH meters, redox potentiometers, and specific metal ion concentration meters) installed within the gas-liquid contact reactor 21. These parameters are directly related to the critical conditions for the precipitation of different metal sulfides. For example, the sulfide ion concentration and potential conditions required for copper ion precipitation into CuS differ significantly from those required for zinc ion precipitation into ZnS.

[0058] The control unit has preset control strategies and setpoints. These setpoints are determined based on the solubility product constant of the target metal sulfide and the precipitation-dissolution equilibrium theory. For example, when the system target is to preferentially precipitate copper, the control unit will maintain the ORP value in the gas-liquid contact reactor 21 within a low set range (strong reducing environment). The control unit compares the parameters monitored in real time (such as the current ORP value) with the preset target setpoints and calculates the deviation between the current gas supply (represented by the circulating fan 19) and the target demand using a built-in algorithm (such as a PID control algorithm).

[0059] Based on the calculated deviation, the control unit generates an adjustment command and outputs it to the actuator of the gas circulation assembly—namely, the circulating fan 19. The adjustment command is typically a control signal for the fan speed (frequency) or valve opening.

[0060] By precisely and dynamically matching the supply of hydrogen sulfide gas with the actual needs of the chemical reaction, the system can stably control the environment within the gas-liquid contact reactor 21 within a narrow window period. During this window period, only the target metal with the smallest solubility product can form sulfide precipitates, while other metals remain in a dissolved state. After the first metal has completely precipitated, the control unit can automatically or manually switch the setpoint to change the reaction conditions, thereby orderly and selectively precipitating and recovering multiple valuable metals.

[0061] In some embodiments, such as Figure 1 As shown, the connection between the gas output pipe and the bioreactor 11 is located at the top of the bioreactor 11, the connection between the gas output pipe and the gas-liquid contact reactor 21 is located at the bottom of the gas-liquid contact reactor 21, the connection between the gas return pipe and the bioreactor 11 is located at the bottom of the bioreactor 11, and the connection between the gas return pipe and the gas-liquid contact reactor 21 is located at the top of the gas-liquid contact reactor 21.

[0062] Gas output path (top of bioreactor 11 → bottom of gas-liquid contact reactor 21). In bioreactor 11, hydrogen sulfide gas produced by microorganisms, due to its lower density than liquid, will naturally rise and accumulate in the top space of the reaction chamber. Placing the gas output pipe interface at the top allows for the most direct and efficient collection of the generated hydrogen sulfide gas, avoiding unnecessary retention or dissolution loss of gas in the liquid layer.

[0063] Gas is introduced from the bottom of the gas-liquid contact reactor 21. After the less dense gas is released from the bottom, it will naturally pass through the entire liquid layer under the action of buoyancy, which prolongs the residence time of the gas in the liquid phase and disperses it in the form of bubbles, greatly increasing the contact area between the gas and liquid phases.

[0064] Gas reflux path (top of gas-liquid contact reactor 21 → bottom of bioreactor 11). In gas-liquid contact reactor 21, the unreacted residual gas (mainly hydrogen sulfide, possibly mixed with a small amount of carbon dioxide, etc.) will also accumulate in the top space of the reactor. It is most efficient to draw the reflux gas from this point.

[0065] The reflux gas enters the liquid layer of bioreactor 11 from the bottom, where it will again form bubbles and rise. During this process, the residual hydrogen sulfide in the bubbles may further dissolve in the reaction liquid and be utilized by microorganisms, or at least play a role in stirring and mixing. Furthermore, the introduction of hydrogen sulfide-rich gas from the bottom helps maintain a highly reducing anaerobic microenvironment in the lower part of bioreactor 11.

[0066] In some embodiments, such as Figure 1 As shown, the gas-liquid contact reactor 21 is equipped with a stirring assembly 24, which is used to ensure that the hydrogen sulfide gas and the acidic wastewater are fully contacted and mixed.

[0067] For example, the stirring assembly 24 can be a radial flow agitator (such as a disc turbine or a straight-blade turbine). As the blades rotate, the fluid is thrown radially at high speed, impacting the reactor wall and then splitting into upper and lower circulating streams. This is suitable for gas-liquid dispersion processes. The powerful shear force efficiently cuts and breaks down bubbles introduced from the bottom into small, uniform bubble clusters.

[0068] The stirring assembly 24 can be an axial flow agitator (such as a slanted blade turbine or propeller type). The blade design allows the fluid to be primarily propelled along the stirring axis (upward or downward), forming a strong overall circulating flow. This is suitable for applications requiring strong overall mixing and prevention of solid sedimentation. It effectively ensures the uniformity of pH, concentration, and temperature within the reactor and keeps the generated precipitate in suspension.

[0069] The stirring assembly 24 can also employ a combined stirring system. Different types of stirrers can be combined and installed on the same or multiple stirring shafts. For example, a radial-flow turbine stirrer can be installed at the bottom for powerful gas dispersion, while an axial-flow inclined-blade turbine can be installed at the top to enhance overall circulation, so as to simultaneously ensure efficient gas dispersion and uniform mixing of reactants.

[0070] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0071] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0072] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0073] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0074] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0075] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A system for recovering metal ions from acid solutions, characterized in that, include: A hydrogen sulfide preparation apparatus includes a bioreactor, an environmental control component, and a gas circulation component. The bioreactor has a reaction chamber for containing hydrogen sulfide-producing microbial communities and reaction liquid. The bioreactor is equipped with a feed pipe connected to the reaction chamber. The environmental control component is connected to the bioreactor and is used to control the reaction conditions in the reaction chamber to maintain microbial activity and generate hydrogen sulfide gas. The gas circulation component includes a gas output pipe and a gas return pipe respectively connected to the reaction chamber. A purification treatment device includes a gas-liquid contact reactor. The gas-liquid contact reactor is equipped with a wastewater delivery pipe and a treated water discharge pipe. Acidic wastewater is delivered to the gas-liquid contact reactor through the wastewater delivery pipe. The gas-liquid contact reactor is connected to a bioreactor through a gas output pipe to receive hydrogen sulfide-containing gas, allowing the introduced hydrogen sulfide-containing gas to contact and mix with the flowing acidic wastewater. The mixed wastewater is discharged through the treated water discharge pipe. The gas-liquid contact reactor is connected to the bioreactor through a gas return pipe to return unreacted hydrogen sulfide-containing gas to the bioreactor. A solid-liquid separation device includes a precipitator, which is equipped with a recovery pipe and an outlet pipe. The precipitator is connected to the gas-liquid contact reactor through the treated water discharge pipe to receive the mixed wastewater, so that the metal sulfide precipitate generated in the wastewater is separated from the liquid phase and discharged through the recovery pipe. The supernatant in the precipitator is discharged through the outlet pipe.

2. The system for recovering metal ions from acidic solutions according to claim 1, characterized in that, The environmental control component includes a heat exchanger and a circulating pump. The heat exchanger is connected to the reaction chamber via a pipeline to form a heat exchange circulation loop. The circulating pump is located on the heat exchange circulation loop. The heat exchanger is externally connected to a cooling water and / or hot water circulation system. The temperature inside the reaction chamber is controlled within a preset range by the heat exchanger to ensure the activity of microorganisms.

3. The system for recovering metal ions from acidic solutions according to claim 2, characterized in that, The environmental control component also includes a feed pipe, which is connected to the heat exchange circulation loop or the reaction chamber. The feed pipe is used to add carbon sources, nutrients and pH adjusters to maintain the nutritional conditions and pH range required for the biological reaction.

4. The system for recovering metal ions from acidic solutions according to claim 2, characterized in that, The environmental control component also includes a drain pipe, which is connected to the heat exchange circulation loop or the reaction chamber and is equipped with a controlled valve for periodically draining part of the reaction liquid to control salt accumulation.

5. The system for recovering metal ions from acidic solutions according to any one of claims 2-4, characterized in that, The environmental control component also includes an online monitoring instrument, which is installed on the heat exchange circulation loop and is used to continuously monitor at least one parameter among pH value, temperature and conductivity in the reaction chamber.

6. The system for recovering metal ions from acidic solutions according to claim 1, characterized in that, The gas circulation assembly further includes a circulation fan, which is located on the gas output pipe and / or the gas return pipe, and is used to drive the gas to circulate between the hydrogen sulfide preparation device and the purification treatment device.

7. The system for recovering metal ions from acidic solutions according to claim 6, characterized in that, The system integrates a control unit, which adjusts the operation of the gas circulation component based on the process parameters within the gas-liquid contact reactor to control the flow rate of hydrogen sulfide-containing gas supplied to the gas-liquid contact reactor in real time, thereby achieving selective or stepwise precipitation of different metal ions.

8. The system for recovering metal ions from acidic solutions according to claim 1, characterized in that, The connection point between the gas output pipe and the bioreactor is located at the top of the bioreactor, the connection point between the gas output pipe and the gas-liquid contact reactor is located at the bottom of the gas-liquid contact reactor, the connection point between the gas return pipe and the bioreactor is located at the bottom of the bioreactor, and the connection point between the gas return pipe and the gas-liquid contact reactor is located at the top of the gas-liquid contact reactor.

9. The system for recovering metal ions from acidic solutions according to claim 1, characterized in that, The gas-liquid contact reactor is equipped with a stirring assembly to ensure that hydrogen sulfide gas and acidic wastewater come into full contact and mix.

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