Integrated system for multistage deep treatment and reuse of lead-zinc ore dressing wastewater

Abstract

The application belongs to the technical field of beneficiation wastewater treatment, and particularly relates to a lead-zinc beneficiation wastewater multi-stage deep treatment and reuse integrated system, which comprises: a homogenization conditioning tank used for receiving overflow water and buffering water quality and quantity fluctuation of the inflow water; a pH adjusting tank used for adjusting the pH value of the wastewater; a sedimentation tank used for removing heavy metal sludge in the wastewater; an aeration oxidation tank used for degrading chemical oxygen demand in the wastewater; a secondary sedimentation tank used for solid-liquid separation of the wastewater; a filter cloth filter tank used for filtering suspended solids in the wastewater; a disinfection tank used for killing residual bacteria in the wastewater and decomposing residual organic matters in the wastewater; and a desalination unit used for desalination treatment of the wastewater, wherein the produced water is collected, and the concentrated water is transported to a tailing filling system. The integrated system can effectively realize stable and up-to-standard COD treatment of the beneficiation wastewater, the effluent water quality meets the requirements of the beneficiation water, the influence on the lead-zinc concentrate grade fluctuation is small, the wastewater can be efficiently reused, and zero discharge of the contaminated wastewater is realized.

Description

Technical Field

[0001] This application belongs to the field of mineral processing wastewater treatment technology, specifically relating to an integrated system for multi-stage deep treatment and reuse of lead-zinc mineral processing wastewater. Background Technology

[0002] The flotation process for non-ferrous metal ores generates a large amount of beneficiation wastewater, accounting for approximately 30% of the total wastewater discharged from the non-ferrous metal industry. This wastewater typically contains high concentrations of heavy metal ions (such as lead and zinc), as well as various organic reagents such as xanthates, ethyl thiocyanates, phenylene terpenes, and sodium humate. It is characterized by its complex composition, high toxicity, and reluctance to degrade, and long-term discharge can cause serious pollution to surrounding soil, water bodies, and ecosystems. Therefore, achieving advanced treatment and reuse of beneficiation wastewater is crucial for alleviating water shortages and regional environmental pollution problems.

[0003] With the implementation of the special emission limits in the "Emission Standard for Pollutants from Lead and Zinc Industry" (GB25466-2010) and the advancement of regulatory policies such as the "Green Shield Action," the traditional tailings dam discharge model has been gradually phased out. For example, the Fankou Lead-Zinc Mine completed "pipeline closure and discharge shutdown" on May 25, 2025, achieving zero wastewater discharge from the tailings dam. At present, concentrators must construct an internal closed-loop circulation system within the plant area to achieve both zero wastewater discharge and ensure stable use of flotation recycled water under the premise of COD≤40mg / L, heavy metal compliance, and no reagent interference.

[0004] However, existing technologies mostly focus on the removal of single pollutants, such as chemical precipitation to remove heavy metals, biochemical degradation of organic matter, or ozone oxidation to treat residual reagents. These solutions struggle to simultaneously address issues of residual organic matter, salt accumulation, and system balance. Existing devices generally lack designs for dynamic control of water and salt balance. Membrane system concentrate is often simply discharged or improperly circulated, leading to problems such as salt enrichment, scaling, and reagent deactivation, failing to achieve true deep treatment and closed-loop reuse of mineral processing wastewater. Therefore, there is an urgent need for a multi-stage synergistic system integrating "neutralization and precipitation of heavy metals + biochemical degradation of organic matter + ozone detoxification + SS removal via filter cloth + membrane salt control" to achieve the synergistic removal of heavy metals, organic matter, and salts, maintain system water-salt balance, and ensure long-term stable operation for mineral processing reuse. Utility Model Content

[0005] To address at least one technical problem in the existing technology, this application provides an integrated system for multi-stage deep treatment and reuse of lead-zinc ore beneficiation wastewater.

[0006] An integrated system for multi-stage deep treatment and reuse of lead-zinc ore beneficiation wastewater, the integrated system comprising:

[0007] The homogenization equalization tank has its inlet connected to the overflow outlet of the thickening equipment, and is used to receive overflow water and buffer fluctuations in the quality and quantity of the influent.

[0008] The pH adjustment tank has its inlet connected to the outlet of the homogenization tank, and is used to adjust the pH of the wastewater transported from the homogenization tank to 9.5-10.

[0009] A sedimentation tank, the inlet of which is connected to the outlet of the pH adjustment tank, is used to remove heavy metal sludge from the wastewater transported by the pH adjustment tank.

[0010] An aerated oxidation tank, whose inlet is connected to the outlet of the sedimentation tank, is used to degrade the chemical oxygen demand in the wastewater transported from the sedimentation tank, so that its concentration is not greater than 40 mg / L.

[0011] The secondary sedimentation tank has its inlet connected to the outlet of the aerated oxidation tank, and is used to perform solid-liquid separation on the wastewater sent from the aerated oxidation tank.

[0012] The filter cloth filter tank has its inlet connected to the outlet of the secondary sedimentation tank and is used to filter suspended solids in the wastewater transported from the secondary sedimentation tank so that the concentration of suspended solids is not greater than 10 mg / L.

[0013] The disinfection tank has its inlet connected to the outlet of the filter cloth filter tank, and is used to kill residual bacteria in the wastewater transported by the filter cloth filter tank and decompose the residual organic matter therein.

[0014] The clear water tank has its inlet connected to the outlet of the disinfection tank and is used to store the disinfected water delivered from the disinfection tank. The clear water tank includes a reuse outlet and a desalination outlet. A portion of the water in the clear water tank can be directly reused in the flotation process through its reuse outlet.

[0015] The desalination unit has its inlet connected to the desalination outlet of the clear water tank, and is used to desalinate another part of the water transported from the clear water tank. The desalination product water is collected, and the desalination concentrate is transported to the tailings backfilling system.

[0016] Optionally, a pipeline pump is installed at the inlet of the homogenization and equalization tank, and the pipeline pump is configured to control the fluctuation of the influent water quality and quantity within ±20%.

[0017] Optionally, a booster pump is installed at the inlet of the pH adjustment tank. Additionally, the integrated system further includes:

[0018] A CO2 storage tank, connected to the air inlet of the pH adjustment tank, is used to provide CO2 into the pH adjustment tank in a controlled manner;

[0019] A lime slurry tank, connected to the inlet of the pH adjustment tank, is used for controlled addition of lime slurry into the pH adjustment tank;

[0020] The PLC control unit is used to adjust the pH value of the wastewater in the tank by controlling the amount of CO2 and / or lime slurry added.

[0021] A pH monitoring probe is installed inside the pH adjustment tank to monitor the pH value of the wastewater in real time and feed the signal back to the PLC control unit to optimize the dosing efficiency of CO2 and / or lime slurry.

[0022] Optionally, the aerated oxidation tank is also provided with a feeding port, which is connected to the lime slurry tank through a pipe. In this case, the PLC control unit is also used to control the lime slurry tank to feed lime slurry into the aerated oxidation tank in order to adjust the pH value of the wastewater in the aerated oxidation tank.

[0023] Optionally, the sedimentation tank is a vertical flow sedimentation tank, and the sludge discharge port of the vertical flow sedimentation tank is connected to a closed sludge equalization tank through a sludge discharge system. In addition, the sludge discharge ports of the homogenization equalization tank and the pH equalization tank are also connected to the sludge equalization tank through a sludge discharge system.

[0024] Optionally, the aerated oxidation tank is equipped with a microporous aeration pipe network, and correspondingly, the integrated system further includes:

[0025] A blower room, which is connected to the microporous aeration pipe network, is used to provide continuous aeration to the aerated oxidation tank through the microporous aeration pipe network.

[0026] Optionally, the integrated system further includes a sludge thickening tank, which is connected to the sludge discharge port of the secondary sedimentation tank and the sludge inlet of the aeration oxidation tank via pipelines, and each pipeline is equipped with a return pump. In addition, the sludge thickening tank is also connected to the sludge equalization tank via a pipeline.

[0027] Optionally, the sludge discharge port of the filter cloth filter is connected to the sludge inlet of the aerated oxidation tank via a pipeline, and a return pump is installed on the pipeline.

[0028] Optionally, an ozone generator is installed in the disinfection pool.

[0029] Optionally, the desalination unit uses a reverse osmosis membrane to desalinate the water. In addition, the desalination unit also includes a salt monitoring unit and a dynamic regulating valve. The salt monitoring unit is used to monitor the salt concentration of the internal water in real time, and the dynamic regulating valve is used to dynamically adjust the concentrate ratio according to the real-time changes in salt concentration.

[0030] This application has at least the following beneficial technical effects:

[0031] First, the multi-stage deep treatment and reuse integrated system for lead-zinc ore beneficiation wastewater in this application has a high degree of integration, constructing a multi-stage synergistic treatment chain. The integrated system of this application includes a homogenization equalization tank, a pH adjustment tank, a sedimentation tank, an aeration oxidation tank, a secondary sedimentation tank, a filter cloth tank, a disinfection tank, a clear water tank, and a membrane treatment unit connected in a cascade manner. Among them, the homogenization equalization tank is used to buffer fluctuations in water volume and water quality, the pH adjustment tank optimizes the alkalinity of the wastewater (9.5-10), the sedimentation tank efficiently settles heavy metal ions, the aeration oxidation tank and the secondary sedimentation tank form an aerobic sludge system to thoroughly decompose organic matter, the upper water body then passes through the filter cloth tank and the disinfection tank to further remove suspended solids and microorganisms, and then enters the clear water tank for storage and reuse. Finally, the desalination unit diverts concentrated water to tailings backfill to maintain the salt balance of the system. The integrated system of this application can achieve the synergistic removal of heavy metals, organic matter, bacteria and suspended solids, ensuring that the effluent COD≤40mg / L and SS≤10mg / L, meeting the requirements for mineral processing water, with minimal fluctuation in the grade of lead and zinc concentrate, enabling efficient reuse of wastewater and achieving zero discharge of polluted wastewater.

[0032] Secondly, in the integrated system of this application, the membrane concentrate backfill design achieves closed-loop and dynamic control of salt content. A desalination unit is installed at the end of the clear water tank, using a reverse osmosis membrane for desalination. The permeate is reused, and the concentrate discharge ratio is controlled (15%–25%) via a dynamic regulating valve and transported to the tailings backfilling system, where it is mixed with tailings, cement, and fly ash to form a slurry. Partially solidified salts in the slurry are retained, while the unsolidified portion is returned to the return water tank with the leachate for further treatment by the system, thus forming a cross-system cycle of "membrane unit—tailings backfill—slurry return—treatment system". This scheme maintains the salt accumulation rate below 15% per month through dynamic monitoring and feedback control, effectively preventing salt enrichment and scaling problems. It is the first engineering solution to achieve dynamic salt balance control in mineral processing wastewater treatment.

[0033] Finally, the integrated system presented in this application demonstrates excellent operational results, balancing environmental and economic benefits. The synergistic operation of the membrane system and tailings backfill achieves zero wastewater discharge and resource utilization of salts, resulting in a system reuse rate exceeding 95%. Compared to traditional treatment methods, this integrated system significantly reduces operating costs and tailings water risks with the same investment. It not only achieves water resource recycling but also provides a technical pathway for the continuous operation of tailings ponds in mineral processing plants under "pipe-cutting and discharge cessation" conditions, possessing significant industrial application value and environmental benefits. Attached Figure Description

[0034] Figure 1 This is a structural diagram of the lead-zinc ore beneficiation wastewater deep treatment and closed-loop recycling system of this application.

[0035] Among them, 1-homogenization tank; 2-pH adjustment tank; 3-sedimentation tank; 4-aeration oxidation tank; 5-secondary sedimentation tank; 6-filter cloth filter; 7-disinfection tank; 8-clear water tank; 9-desalination unit; 10-pipeline pump; 11-lift pump; 12-CO2 storage tank; 13-lime slurry tank; 14-sludge equalization tank; 15-blower room; 16-sludge thickening tank; 17-return pump. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0037] The following is in conjunction with the appendix Figure 1 This application provides a more detailed description of the integrated system for multi-stage deep treatment and reuse of lead-zinc ore beneficiation wastewater.

[0038] like Figure 1 As shown, this application discloses an integrated system for multi-stage deep treatment and reuse of lead-zinc ore beneficiation wastewater, including a homogenization equalization tank 1, a pH equalization tank 2, a sedimentation tank 3, an aeration oxidation tank 4, a secondary sedimentation tank 5, a filter cloth filter 6, a disinfection tank 7, a clear water tank 8, and a desalination unit 9 connected in sequence.

[0039] The homogenization tank 1 is used to buffer changes in flow rate and concentration to ensure the stability of subsequent treatment. Specifically, the homogenization tank 1 includes an inlet, which is connected to the overflow port of the deep cone thickener through a pipeline, and a pipeline pump 10 is set to transport wastewater to stabilize the influent water quality and quantity. In this embodiment, the pipeline pump 10 is preferably configured to control the fluctuation of influent water quality and quantity within ±20%.

[0040] pH adjustment tank 2 is used to adjust the pH value of the wastewater delivered from homogenization tank 1. In this embodiment, it is preferable to adjust the pH of the wastewater to 9.5-10. The pH adjustment tank 2 may specifically include a liquid inlet, an air inlet and a feed inlet. Its liquid inlet is connected to the liquid outlet of homogenization tank 1, and a booster pump 11 is provided at the liquid inlet.

[0041] In addition, the integrated system of this application also includes a CO2 storage tank 12, a lime slurry tank 13, a dosing pump, a PLC control unit, and a pH monitoring probe. The CO2 storage tank 12 is connected to the air inlet of the pH adjustment tank 2 and is used to provide CO2 to the pH adjustment tank 2 in a controlled manner (manual control or automatic control by the PLC control unit). The lime slurry tank 13 is connected to the feed inlet of the pH adjustment tank 2 and is used to add lime slurry to the pH adjustment tank 2 in a controlled manner through the dosing pump. The PLC control unit is used to adjust the pH value of the wastewater in the tank by controlling the amount of CO2 and / or lime slurry added. The pH monitoring probe is set in the pH adjustment tank (2) and is used to monitor the pH value of the wastewater in real time and feed the signal back to the PLC control unit to optimize the dosing efficiency of CO2 and / or lime slurry.

[0042] The sedimentation tank 3 is used to remove heavy metal sludge from the wastewater transported by the pH adjustment tank. Various suitable sedimentation tanks can be selected as needed. In this embodiment, a vertical flow sedimentation tank is preferred.

[0043] After pH adjustment, the wastewater flows into a vertical flow sedimentation tank and is left to stand for 2 hours. Gravity sedimentation is used to remove the initially generated heavy metal sludge, which mainly includes lead and zinc, with a removal rate of >99%.

[0044] In addition, this application also includes a closed (to prevent secondary pollution) sludge equalization tank 14 (also called a sludge collection tank), which is made of corrosion-resistant material and equipped with a stirring device to prevent sludge from caking; the sludge discharge ports of the aforementioned vertical flow sedimentation tank, homogenization equalization tank 1 and pH equalization tank 2 are respectively connected to the closed sludge equalization tank 14 through a sludge discharge system, and their bottom sludge can be discharged to the sludge equalization tank 14 for collection.

[0045] The aeration oxidation tank 4 is used to degrade the chemical oxygen demand (COD) in the wastewater transported from the sedimentation tank 3. In this embodiment, the COD is preferably ≤40mg / L. Specifically, the aeration oxidation tank 4 may include an inlet and a dosing outlet. The inlet is connected to the outlet of the sedimentation tank 3, and the dosing outlet is connected to the lime slurry tank 13 through a pipe. At this time, the above-mentioned PLC control unit is also used to control the lime slurry tank 13 to add lime slurry to the aeration oxidation tank 4 (for example, by adding it through a set dosing pump) to adjust the pH value of the wastewater in the aeration oxidation tank 4 to be between 7.0 and 8.0.

[0046] Furthermore, a microporous aeration network is also installed within the aerated oxidation tank 4. Correspondingly, the integrated system of this application also includes a blower room 15, which is connected to the microporous aeration network and used to provide continuous aeration to the aerated oxidation tank 4 through the microporous aeration network. In this embodiment, it is preferable to control the dissolved oxygen at 2.0–4.0 mg / L through the microporous aeration network, with a hydraulic retention time of 18.8 hours and a sludge return ratio of 75%.

[0047] In addition, biological sludge is provided in aeration oxidation tank 4. The biological sludge is prepared by acclimation, which is divided into the following three stages:

[0048] In the initial stage, when MLSS is below 4 g / L, nutrients (including a mixture of glucose, urea and potassium dihydrogen phosphate) are added at a ratio of five-day biochemical oxygen demand (BOD5):N:P = 100:5:1 or directly introduced into the diluted mineral processing wastewater to supplement carbon sources and nutrients and maintain the metabolic activity of activated sludge.

[0049] After entering the gradual load phase, when SV30 stabilizes above 25%, water is intermittently added at 5% of the designed treatment capacity, and the influent load is gradually increased daily according to the sludge settling performance until it reaches 100%, until the system design flow rate is reached.

[0050] During the stable operation phase, the system switches to continuous influent mode, maintaining the dissolved oxygen concentration in the aeration tank at 2.0–4.0 mg / L, ensuring that the effluent COD remains consistently below 40 mg / L. At this time, the sludge acclimation indicators are maintained at SV30 of 20%–30% and MLSS of no less than 4 g / L. The system's biochemical performance is stable, and it can enter normal operation.

[0051] The inlet of the secondary sedimentation tank 5 is connected to the outlet of the aerated oxidation tank 4, and is used to perform solid-liquid separation on the wastewater sent from the aerated oxidation tank 4.

[0052] Furthermore, the integrated system of this application also includes a sludge thickening tank 16; the sludge thickening tank 16 is connected to the sludge discharge port of the secondary sedimentation tank 5 and the sludge inlet of the aerated oxidation tank 4 through pipelines, and each pipeline is equipped with a return pump 17, so that the settled sludge in the secondary sedimentation tank 5 can be transported to the sludge thickening tank 16; in addition, the sludge thickening tank 16 is also connected to the sludge equalization tank 14 through pipelines, so that part of the settled sludge is returned to the aerated oxidation tank 4, and the remaining sludge is discharged to the sludge equalization tank 14.

[0053] The inlet of the cloth filter 6 is connected to the outlet of the secondary sedimentation tank 5, and is used to filter suspended solids (SS) in the wastewater transported from the secondary sedimentation tank 5. Specifically, the cloth filter includes a central cylinder, filter cloth, and a self-priming pump. During filtration, the filter disc remains stationary, and the sludge is discharged to the sludge tank through the sludge discharge pipe after sedimentation. The backwashing process can be controlled by the aforementioned PLC control unit. When the water level in the filter rises to a preset threshold, the level sensor is triggered to start the drum rotation and the backwash pump. The self-priming pump removes the attached sludge through the suction port. The backwashing cycle is adjustable, and the filtration operation continues during backwashing. During system operation, the backwashing frequency and sludge discharge cycle can be set and adjusted through the PLC program, usually once every 2 to 4 hours, to adapt to different water quality and load conditions. In this embodiment, after treatment by the cloth filter, the effluent SS is no more than 10 mg / L. Pre-filtration not only effectively removes fine suspended particles and prevents suspended solids from encapsulating organic molecules and clogging membrane pores, but also improves the reaction efficiency of the subsequent ozone oxidation unit by about 20% to 30%.

[0054] The disinfection tank 7 is used to kill residual bacteria in the wastewater transported from the filter cloth filter tank 6 and decompose the residual organic matter therein, ensuring that the effluent COD ≤ 40 mg / L and the total number of bacteria < 100 CFU / mL; in this embodiment, the disinfection tank 7 is preferably an ozone disinfection tank, which is equipped with an ozone generator. In addition, the ozone disinfection tank also has a buffer function.

[0055] Clear water tank 8 is used to store disinfected water and serves as a hub for reclaimed water allocation. Specifically, the inlet of clear water tank 8 is connected to the outlet of disinfection tank 7 and is used to store the disinfected water delivered from disinfection tank 7. Clear water tank 7 includes a reuse outlet and a desalination outlet. A portion of the water in clear water tank 7 can be directly reused in the flotation process through its reuse outlet, while the other portion undergoes subsequent desalination treatment.

[0056] The inlet of desalination unit 9 is connected to the desalination outlet of clear water tank 8, and is used to desalinate another portion of the water transported from clear water tank 8. The desalination product water is collected, and the concentrated water is transported to the tailings backfilling system for utilization, thereby achieving dynamic control of the system's salt balance. In this embodiment, desalination unit 9 preferably uses a reverse osmosis membrane, and its outlet is equipped with a dynamic regulating valve to control the concentrated water discharge ratio to 15%–25%, ensuring that the system's salt accumulation rate does not exceed 15% per month. Furthermore, the desalination product water has a COD ≤ 40 mg / L, total lead ≤ 0.2 mg / L, and total zinc ≤ 1.0 mg / L, conforming to GB25466-2010 standards.

[0057] The wastewater treatment process of this system is as follows:

[0058] 1) Homogenization and pH Adjustment: After overflowing from the deep cone thickener, the mineral processing wastewater first enters the homogenization tank 1, where the water quality and quantity are homogenized by the pipeline pump 10 to avoid shocks caused by intermittent discharge. Subsequently, the wastewater in the homogenization tank 1 is pumped into the pH adjustment tank 2 by the lift pump 11, where the pH is adjusted to 9.5-10 by adding CO2 and / or lime slurry.

[0059] 2) Heavy metal removal: Wastewater from pH adjustment tank 2 flows into sedimentation tank 3 by gravity, where heavy metal sludge settles by gravity (preferably for 2 hours), and the bottom sludge is discharged to sludge equalization tank 14.

[0060] 3) Biochemical degradation: The supernatant in sedimentation tank 3 flows into aeration oxidation tank 4 and reacts with the acclimated sludge for 18.8 hours (dissolved oxygen 2-4 mg / L), reducing COD to <40 mg / L. The effluent is then settled in secondary sedimentation tank 5, and the sludge is returned to aeration oxidation tank 4.

[0061] 4) Advanced Treatment: The effluent from the secondary sedimentation tank 5 flows into the cloth filter tank 6 by gravity, and after filtration through the filter cloth, it flows into the central cylinder and is discharged. Sludge is intercepted by the filter cloth and deposited in the filter tank or adheres to the filter cloth. The deposited sludge is discharged to the sludge tank through the sludge discharge pipe. The sludge adhering to the filter cloth is sucked away by the self-priming pump during back suction. During normal filtration, the filter disc remains stationary, and the surface of the filter cloth after back suction can quickly enter the normal filtration state. The suspended solids (SS) in the effluent from the cloth filter tank is reduced to ≤10mg / L. The filtered water flows into the disinfection tank 7 to kill bacteria and decompose residual organic matter.

[0062] Regarding the backwashing process in the filter cloth filter, it's important to note that as particles in the wastewater accumulate on the inner side of the filter cloth, a sludge layer gradually forms. As the sludge accumulates on the filter cloth, the flow rate to the filter disc slows down when it reaches a certain level, causing the water level in the filter to gradually rise. When the water level reaches a certain point, the level sensor is triggered, activating the rotating drum and simultaneously starting the backwash pump. This initiates a backwashing process, with the rotating drum slowly rotating and the self-priming pump sucking away the accumulated particles from both sides of the filter cloth through suction ports located on either side of the drum. The filtration system continues to operate normally during backwashing.

[0063] 5) Reuse and Salt Balance: The effluent from disinfection tank 7 is stored in clear water tank 7, with a portion directly reused in the flotation process; the remainder enters desalination unit 9 (reverse osmosis membrane treatment unit), the concentrate from the membrane system is discharged to the tailings backfilling system, and the permeate enters the new water tank. The system's salt balance is achieved by adjusting the concentrate ratio.

[0064] The integrated system for multi-stage advanced treatment and reuse of lead-zinc ore beneficiation wastewater of this application will be further illustrated below through a specific example.

[0065] Example 1

[0066] This embodiment is used to verify the overall operational performance and treatment effect of the integrated system for multi-stage deep treatment and reuse of lead-zinc ore beneficiation wastewater.

[0067] The specific settings for system operation are as follows:

[0068] pH adjustment tank 2 automatically controls the addition of CO2 and / or lime slurry through a PLC control unit to maintain the effluent pH value between 9.5 and 10. The sludge adopts a staged acclimatization method, gradually increasing the influent load to obtain activated sludge with SV30 of 20% to 30% and MLSS of not less than 4 g / L. During stable operation, the hydraulic retention time of aeration oxidation tank 4 is 18.8 hours, the COD volumetric load is 0.25 (COD / (kg·MLSS·d)), the dissolved oxygen concentration is maintained at 2.0 to 4.0 mg / L, the activated sludge return ratio is 75%, and a microporous aeration pipe network is laid at the bottom of the tank to ensure uniform oxygen distribution.

[0069] During stable system operation, the salt concentration of wastewater is monitored in real time using a salt monitoring device, and the proportion of concentrated water discharged from desalination unit 9 is dynamically adjusted within the range of 15% to 25%, controlling the salt accumulation rate of the system to not exceed 15% / month. All concentrated water generated by desalination unit 9 is transported to the tailings backfilling system, mixed with tailings slurry, and then solidified, realizing the resource utilization of concentrated water and closed-loop transfer of salt.

[0070] During the full system operation test, effluent samples were taken during the stable operation period after sludge acclimation in the example, and the water samples were tested in accordance with the relevant methods specified in the "Integrated Wastewater Discharge Standard" GB8978-1996 to compare the pollutant indicators of the mineral processing wastewater before treatment.

[0071] The COD monitoring results of the influent and effluent are shown in Table 1 below:

[0072] Table 1. COD Monitoring Results of Influent and Effluent

[0073]

[0074]

[0075]

[0076] The results showed that the COD of the recycled water in the clear water tank in Example 1 was ≤40mg / L, the COD removal rate was stable at over 90%, and the effluent quality met the relevant requirements of the special emission limits for water pollutants in the "Emission Standard of Pollutants for Lead and Zinc Industry" (GB 25466-2010).

[0077] The monitoring results of heavy metal indicators in the vertical flow sedimentation tank are shown in Table 2 below:

[0078] Table 2. Monitoring results of heavy metal indicators in vertical flow sedimentation tanks

[0079]

[0080]

[0081]

[0082] The results showed that the total lead concentration in the downstream effluent (clear water tank or ozone oxidation tank) of Example 1 was ≤0.2mg / L and the total zinc concentration was ≤1.0mg / L. The effluent quality met the relevant requirements of the special emission limits for water pollutants in the "Emission Standard of Pollutants for Lead and Zinc Industry" (GB 25466-2010).

[0083] In summary, the effluent quality of this system is stable (COD≤40mg / L, all heavy metal indicators meet the standards), which can meet the water requirements of the flotation process and is suitable for zero-discharge scenarios of lead-zinc ore beneficiation wastewater.

[0084] The multi-stage deep treatment and reuse integrated system for lead-zinc ore beneficiation wastewater provided in this application achieves efficient purification and reuse of ore beneficiation wastewater through multi-stage coupling and closed-loop circulation, reaching the goal of zero wastewater discharge and eliminating environmental pollution at the source. This system can efficiently treat ore beneficiation wastewater with high heavy metal content and high organic matter concentration, operates stably, has a wide range of applications, and has good engineering promotion value.

[0085] The above embodiments are used to illustrate the technical solutions of this application, and not to limit its protection scope; any equivalent substitutions or modifications made without departing from the technical concept of this application shall fall within the protection scope of this application.

Claims

1. An integrated system for multi-stage deep treatment and reuse of lead-zinc ore beneficiation wastewater, characterized in that, The integrated system includes: The homogenization equalization tank (1) has its inlet connected to the overflow outlet of the thickening equipment, which is used to receive overflow water and buffer fluctuations in the quality and quantity of the influent. pH adjustment tank (2), whose inlet is connected to the outlet of the homogenization tank (1), is used to adjust the pH of the wastewater transported from the homogenization tank (1) to 9.5-10. The sedimentation tank (3) has its inlet connected to the outlet of the pH adjustment tank (2) and is used to remove heavy metal sludge from the wastewater transported by the pH adjustment tank. The aeration oxidation tank (4) has its inlet connected to the outlet of the sedimentation tank (3) and is used to degrade the chemical oxygen demand in the wastewater transported from the sedimentation tank (3) so that its concentration is not greater than 40 mg / L. The secondary sedimentation tank (5) has its inlet connected to the outlet of the aeration oxidation tank (4) and is used to perform solid-liquid separation on the wastewater sent from the aeration oxidation tank (4). The filter cloth filter (6) has its inlet connected to the outlet of the secondary sedimentation tank (5) and is used to filter the suspended solids in the wastewater transported from the secondary sedimentation tank (5) so that the concentration of suspended solids is not greater than 10 mg / L. The disinfection tank (7) has its inlet connected to the outlet of the filter cloth filter tank (6) and is used to kill residual bacteria in the wastewater transported by the filter cloth filter tank (6) and decompose the residual organic matter therein. The clear water tank (8) has its inlet connected to the outlet of the disinfection tank (7) and is used to store the disinfected water delivered by the disinfection tank (7). The clear water tank (8) includes a reuse outlet and a desalination outlet. A portion of the water in the clear water tank (8) can be directly reused in the flotation process through its reuse outlet. The desalination unit (9) has its inlet connected to the desalination outlet of the clear water tank (8) and is used to desalinate another part of the water body transported from the clear water tank (8). The desalination product water is collected and the desalination concentrate is transported to the tailings backfilling system.

2. The integrated system according to claim 1, characterized in that, A pipeline pump (10) is installed at the inlet of the homogenization tank (1), and the pipeline pump (10) is configured to control the fluctuation of the influent water quality and quantity within ±20%.

3. The integrated system according to claim 1, characterized in that, A booster pump (11) is installed at the inlet of the pH adjustment tank (2). In addition, the integrated system also includes: A CO2 storage tank (12) is connected to the air inlet of the pH adjustment tank (2) for controlled supply of CO2 into the pH adjustment tank (2); A lime slurry tank (13) connected to the inlet of the pH adjustment tank (2) is used to add lime slurry into the pH adjustment tank (2) in a controlled manner. The PLC control unit is used to adjust the pH value of the wastewater in the tank by controlling the amount of CO2 and / or lime slurry added. A pH monitoring probe is installed inside the pH adjustment tank (2) to monitor the pH value of the internal wastewater in real time and feed the signal back to the PLC control unit to optimize the addition efficiency of CO2 and / or lime slurry.

4. The integrated system according to claim 3, characterized in that, The aeration oxidation tank (4) is also provided with a feeding port, which is connected to the lime slurry tank (13) through a pipe. At this time, the PLC control unit is also used to control the lime slurry tank (13) to feed lime slurry into the aeration oxidation tank (4) in order to adjust the pH value of the wastewater in the aeration oxidation tank (4).

5. The integrated system according to claim 1, characterized in that, The sedimentation tank (3) is a vertical flow sedimentation tank. The sludge discharge port of the vertical flow sedimentation tank is connected to the closed sludge conditioning tank (14) through the sludge discharge system. In addition, the sludge discharge ports of the homogenization conditioning tank (1) and the pH conditioning tank (2) are also connected to the sludge conditioning tank (14) through the sludge discharge system.

6. The integrated system according to claim 1, characterized in that, The aerated oxidation tank (4) is equipped with a microporous aeration network. Correspondingly, the integrated system also includes: The blower room (15) is connected to the microporous aeration network and is used to provide continuous aeration to the aeration oxidation tank (4) through the microporous aeration network.

7. The integrated system according to claim 5, characterized in that, It also includes a sludge thickening tank (16), which is connected to the sludge discharge port of the secondary sedimentation tank (5) and the sludge inlet of the aeration oxidation tank (4) through pipelines. Each pipeline is equipped with a return pump (17). In addition, the sludge thickening tank (16) is also connected to the sludge equalization tank (14) through pipelines.

8. The integrated system according to claim 1, characterized in that, The sludge discharge port of the filter cloth filter (6) is connected to the sludge inlet of the aerated oxidation tank (4) through a pipeline, and a return pump (17) is installed on the pipeline.

9. The integrated system according to claim 1, characterized in that, An ozone generator is installed in the disinfection pool (7).

10. The integrated system according to claim 1, characterized in that, The desalination unit (9) uses a reverse osmosis membrane to desalinate the water. In addition, the desalination unit also includes a salt monitoring unit and a dynamic regulating valve. The salt monitoring unit is used to monitor the salt concentration of the internal water in real time, and the dynamic regulating valve is used to dynamically adjust the concentration ratio according to the real-time changes in salt concentration.

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