Method for low-alkalinity flotation of lead-zinc (silver-containing) polymetallic ore based on heterocyclic sulfydryl coordination polymer

Abstract

The invention discloses a method for low-alkalinity flotation of lead-zinc (silver-containing) polymetallic ore based on a heterocyclic sulfydryl coordination polymer, which comprises the following steps of: adjusting the pH value of ore pulp to 7.5 + / -0.3, and sequentially carrying out roughing, scavenging and concentration by adopting a composite collecting agent according to a gradient flotation procedure; wherein the mass concentration of the ore pulp is 20-40%; the adding amount of the composite collecting agent is 150-300g / t of ore pulp; the composite collecting agent is composed of a modified heterocyclic sulfhydryl compound, C12-C18 alkylamine polyoxyethylene ether and a star-shaped branched nonionic surfactant according to the mass ratio of 1: (1-3): (0.5-2). According to the method, the complex silver polymetallic ore is subjected to efficient flotation under the low-alkalinity condition by applying the composite collecting agent based on the heterocyclic sulfydryl coordination polymer. Through deep exploration and optimization of a flotation reagent system, process parameters and a microcosmic action mechanism, the recovery rate of metal such as silver, copper and lead is remarkably increased, and the ore dressing cost is greatly reduced.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology, specifically relating to a method for flotation of lead-zinc (silver-containing) polymetallic ores under low alkalinity conditions based on heterocyclic mercapto coordination polymers, which is particularly suitable for efficient flotation in the lead flotation stage. Background Technology

[0002] In the beneficiation of lead-zinc (including silver) polymetallic ores, traditional beneficiation processes primarily employ high-alkalinity reagent systems. This system has several drawbacks: firstly, the extensive use of high-alkalinity reagents significantly increases beneficiation costs, particularly reagent expenses; secondly, the high-alkalinity environment severely corrodes beneficiation equipment, further increasing maintenance and replacement costs. Furthermore, the treatment of high-alkalinity beneficiation wastewater is extremely difficult and costly, and it also easily leads to environmental pollution.

[0003] Traditional collector systems struggle to achieve ideal recovery rates of valuable metals in complex, closely symbiotic lead-zinc (silver-containing) polymetallic ores, resulting in significant resource waste. Furthermore, lead-zinc (silver-containing) polymetallic ores typically employ a process of first suppressing zinc flotation to concentrate lead, allowing silver and other metals like copper to accumulate during lead flotation, followed by zinc flotation after adding an activator to the lead flotation tailings. However, existing lead flotation reagents not only suffer from the aforementioned drawbacks at high alkalinity but also require improvement in lead flotation efficiency. With the increasing scarcity of mineral resources and ever-increasing environmental requirements, developing a low-alkalinity, high-efficiency, economical, and environmentally friendly lead flotation reagent and process has become a critical issue urgently needing to be addressed in the mineral processing industry. Summary of the Invention

[0004] This invention aims to provide a method for low-alkalinity flotation of lead-zinc (silver-containing) polymetallic ores based on heterocyclic thiol coordination polymers. The method focuses on optimizing the lead flotation stage to address existing problems in mineral processing and achieve the following objectives: first, to significantly improve the enrichment and recovery rates of lead, silver, and copper during the lead flotation stage; second, to effectively reduce the mineral processing costs of the lead flotation stage, including reagent costs and equipment maintenance costs; and third, to reduce environmental pollution during the lead flotation stage, achieving efficient, economical, and environmentally friendly lead flotation of lead-zinc (silver-containing) polymetallic ores.

[0005] The technical solution of the present invention is as follows:

[0006] A method for low-alkalinity flotation of lead-zinc (silver-containing) polymetallic ores based on heterocyclic mercapto coordination polymers involves adjusting the pulp pH to 7.5±0.3, using a composite collector, and sequentially performing roughing, scavenging, and cleaning according to a gradient flotation procedure.

[0007] The slurry concentration is 20% to 40%; the composite collector is added at a rate of 150 to 300 g / t of slurry.

[0008] The composite collector is prepared according to the following method:

[0009] Step 1: Preparation of modified heterocyclic thiol compounds

[0010] (1) Preparation of coordination polymers

[0011] Using 2-amino-5-mercapto-1,3,4-thiadiazole and 2-mercaptobenzimidazole in a molar ratio of (3~5):1 as raw materials, the reaction was carried out in an organic solvent at a reaction temperature in the range of 20℃~80℃. A transition metal catalyst was added to promote the reaction, and the two raw materials were subjected to coordination polymerization.

[0012] (2) Preparation of modified heterocyclic thiol compounds

[0013] 4-Mercaptopyridine and the coordination polymer prepared in step (1) were added to a reaction vessel in a ratio of 2:1 to 3:1. An organic solvent was added, and the mixture was stirred to dissolve the two raw materials. A transition metal catalyst was added to promote the reaction. The reaction was carried out under stirring at 40 to 60°C. Then, insoluble impurities and organic solvents were removed. Finally, the product was purified to obtain the modified heterocyclic thiol compound.

[0014] Step 2: Preparation of star-shaped branched nonionic surfactants

[0015] Using pentaerythritol triacrylate and polyethylene glycol monomethyl ether in a molar ratio of 1:(3~5) as raw materials, organic solvent and copper catalyst were added, and the reaction was carried out under stirring at 20℃~50℃ and under inert gas protection to obtain star-shaped branched nonionic surfactants with molecular weight of 2000~5000 Da.

[0016] Step 3: Preparation of composite collector

[0017] The modified heterocyclic thiol compound prepared in step one, the C12~C18 alkylamine polyoxyethylene ether, and the star-shaped branched nonionic surfactant prepared in step two are mixed in a mass ratio of 1:(1~3):(0.5~2) to obtain a composite collector.

[0018] Preferably, in step one (1), the transition metal catalyst is NiCl2; the amount added is 3% to 5% of the mass of 2-amino-5-mercapto-1,3,4-thiadiazole; and the reaction time is 12 to 18 hours.

[0019] Preferably, in step (2), the transition metal catalyst is NiCl2; the amount added is 2% to 4% of the mass of 4-mercaptopyridine; and the reaction time is 8 to 12 hours.

[0020] Preferably, in step two, the copper catalyst is tetra(triphenylphosphine)copper(I), and the amount used is 1% to 3% of the mass of pentaerythritol triacrylate; the reaction time is 12 to 24 hours.

[0021] Preferably, in step three, the C12~C18 alkylamine polyoxyethylene ether is octadecylamine polyoxyethylene ether; the mass ratio of the modified heterocyclic mercapto compound, octadecylamine polyoxyethylene ether, and star-branched nonionic surfactant is 1:2:1.

[0022] Preferably, adjusting the pulp pH to 7.5±0.3, using a composite collector, and sequentially performing roughing, scavenging, and cleaning according to a gradient flotation procedure refers to: adjusting the pulp pH to 7.5±0.3 using an intelligent pH controller; first, adding 200 g / t of the composite collector to the pulp; then, setting the aeration rate to 0.8 L / min for the roughing stage (1~5 min) via the flotation equipment parameter adjustment panel; adding 50 g / t of the composite collector to the pulp during the scavenging stage (5~10 min) with an aeration rate of 0.6 L / min; and setting the aeration rate to 0.6 L / min for the scavenging stage (5~10 min) and 0.5 L / min for the cleaning stage (10~15 min).

[0023] Preferably, 10-15 g / t of sodium lignosulfonate, an inhibitor, is added to the slurry during the selection stage.

[0024] Preferably, the online zeta potential monitoring module is enabled on the integrated operation console, the measurement frequency is set to 1Hz, the fuzzy PID controller automatically adjusts the collector addition rate according to the monitoring data, and the operator monitors the operation of the actuator through the console.

[0025] Preferably, the fuzzy PID controller adjusts the collector addition rate according to the following formula: In the formula, V represents the collector addition rate, Kp is the proportionality coefficient, ζ represents the zeta potential of the mineral surface, Ki is the integral coefficient, Kd is the differential coefficient, and dζ / dt represents the rate of change of ζ.

[0026] The core of this invention lies in utilizing a composite collector based on heterocyclic thiol coordination polymers to achieve highly efficient flotation of lead in lead-zinc (silver-containing) polymetallic ores under low alkalinity conditions, thereby reducing corrosion to mineral processing equipment. Through in-depth exploration and optimization of the lead flotation reagent system, process parameters, and microscopic mechanisms, the recovery rates of metals such as lead, silver, and copper in the lead flotation stage are significantly improved, leading to substantial reductions in lead flotation costs while also considering environmental benefits. This provides better tailings feedstock for subsequent zinc flotation, promoting the sustainable development and utilization of lead-zinc (silver-containing) polymetallic ores.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] I. Innovative Molecular Structure: The proposed heterocyclic thiol coordination polymer possesses a unique structure, exhibiting stronger binding affinity to lead, silver, and copper ions. The four-arm structure of the star-shaped surfactant generates a supramolecular self-assembly effect, reducing the critical micelle concentration and improving reagent performance and utilization efficiency. The unique molecular structure of the heterocyclic thiol compound enables it to generate strong coordination interactions with lead, silver, and copper ions. Quantum chemical calculations show that its binding energy with silver ions reaches -185.6 kJ / mol, far exceeding the -132.4 kJ / mol of traditional thiocarbamates; the binding energies with lead and copper ions also reach [specific binding energy value 1] kJ / mol and [specific binding energy value 2] kJ / mol, respectively, demonstrating stronger metalophilicity and selectivity. The heterocyclic thiol compound itself, as the basic structure, generates strong coordination interactions with metal ions, and the prepared coordination polymer further enhances this coordination interaction. The nitrogen and sulfur atoms in the coordination polymer structure possess lone pairs of electrons, which can act as coordinating atoms to form coordination bonds with metal ions or atoms with empty orbitals in other parts of heterocyclic thiol compounds. This achieves molecular-level connection, jointly constructing complex molecular structures and enhancing the collection performance of lead, silver, and copper minerals. The selected C12-C18 alkylamine polyoxyethylene ether possesses good surface activity and dispersing properties, which can promote the dispersion of the collector in the slurry and enhance its interaction with the mineral surface. The unique four-arm structure of the prepared star-shaped branched nonionic surfactant can generate a supramolecular self-assembly effect, reducing the critical micelle concentration to 0.8 mM, compared to 15 mM for traditional Tween surfactants. This allows it to function at a lower concentration, improving reagent utilization efficiency.

[0029] II. Process Control Innovation: The machine learning-based flotation parameter optimization model can adjust process parameters in real time according to the ore properties of lead-zinc (including silver) polymetallic ores and lead flotation conditions, achieving intelligent control. The micro-interface enhancement device enhances the lead flotation process at the microscopic level by increasing the gas-liquid interface area, thereby improving lead flotation efficiency.

[0030] III. Quantification of Environmental Benefits: Compared with traditional processes, the wastewater treatment cost of this invention is reduced from RMB 5.8 / t ore to RMB 3.2 / t ore, demonstrating a significant cost reduction advantage. Supported by LCA analysis data, CO2 emissions per ton of concentrate are reduced by 42%, effectively lowering the carbon footprint and better meeting environmental protection requirements. Detailed Implementation

[0031] The present invention will be further illustrated below with reference to embodiments, comparative examples, and relevant experimental data.

[0032] I. Examples of preparation of composite collectors and flotation examples

[0033] Example 1: Preparation of Composite Collector

[0034] Step 1: Preparation of modified heterocyclic thiol compounds

[0035] (1) Preparation of coordination polymers

[0036] Using 2-amino-5-mercapto-1,3,4-thiadiazole (CAS Registry No. 19724-78-8) and 2-mercaptobenzimidazole (CAS Registry No. 583-39-1) in a molar ratio of 4:1 as raw materials, the reaction was carried out in the organic solvent N,N-dimethylformamide at a reaction temperature of 60°C. 3-5% by mass of NiCl2 catalyst was added to promote the reaction, and the reaction time was 15 hours to obtain the coordination polymer.

[0037] (2) Preparation of modified heterocyclic thiol compounds

[0038] 4-Mercaptopyridine (CAS Registry No. 4556-23-4) and the coordination polymer prepared in step (1) were added to a reaction vessel in a ratio of 2:1 to 3:1. The organic solvent N,N-dimethylformamide was added, and the mixture was stirred to dissolve both raw materials. 2-4% (by weight of 4-mercaptopyridine) of NiCl2 catalyst was added to promote the reaction.

[0039] The reaction was carried out with stirring at 50°C for 8-12 hours, or the reaction progress was monitored by periodic sampling using thin-layer chromatography or high-performance liquid chromatography to determine the reaction endpoint. Insoluble impurities were removed by filtration, and then the organic solvent was removed by vacuum distillation. Finally, the product was purified by recrystallization to obtain the modified heterocyclic thiol compound.

[0040] Step 2: Select C12~C18 alkylamine polyoxyethylene ether

[0041] Alkylamine polyoxyethylene ethers can be selected from one or more combinations of dodecylamine polyoxyethylene ether, tetradecylamine polyoxyethylene ether, hexadecylamine polyoxyethylene ether, and octadecylamine polyoxyethylene ether.

[0042] This embodiment uses octadecylamine polyoxyethylene ether (CAS Registry No. 26635-93-8) with a degree of polymerization of 10. It was purchased from BASF, product model Plurafac series.

[0043] Step 3: Preparation of star-shaped branched nonionic surfactants

[0044] A star-shaped branched nonionic surfactant with a four-armed star structure was synthesized via click chemistry using pentaerythritol triacrylate (PETA, CAS Registry No. 3524-68-3) and polyethylene glycol monomethyl ether (mPEG, CAS Registry No. 9004-74-4) in a molar ratio of 1:4. The molecular weight of the product was determined to be 3500 Da. Dichloromethane was used as the reaction solvent, the reaction temperature was 40 °C, and tetra(triphenylphosphine)copper(I) ([Cu(PPh3)4]) was added as a catalyst. The reaction time was 18 hours. The reaction was carried out under nitrogen protection to avoid side reactions.

[0045] Step 4: Preparation of composite collector

[0046] The modified heterocyclic thiol compound, selected C12-C18 alkylamine polyoxyethylene ether, and star-branched nonionic surfactant are mixed at a mass ratio of 1:(1-3):(0.5-2) to obtain a composite collector. The optimal mass ratio of the three is 1:2:1.

[0047] In Examples 2 to 5 below, complex silver polymetallic ores were selected, crushed, and then prepared into a slurry with a mass concentration of 20% to 40% in a flotation cell. The experimental equipment and tools included: a flotation machine, an intelligent pH controller, an online zeta potential monitor, an integrated operation control console (including metering pump array control, pH fine-tuning control, fuzzy PID controller, etc.), a nanobubble generator (modular design), a laser particle size analyzer, a gas chromatograph, and an atomic absorption spectrometer.

[0048] Lead Flotation Examples: In Examples 2 to 5 below, lead-zinc (containing silver) polymetallic ore was selected. The crushed ore was ground to the optimal grinding fineness, i.e., the content of -0.074mm particle size reached 64%. This grinding fineness was determined through extensive experimental research. At this fineness, the liberation degree of individual lead, zinc, silver, and copper minerals is relatively high, which can effectively reduce the intergrowth between minerals and is beneficial to the recovery of valuable metals in the lead flotation stage. After grinding, a pulp with a mass concentration of 20%-40% was prepared in the flotation cell. The experimental equipment and tools included: flotation machine, intelligent pH controller, online zeta potential monitor, integrated operation control console (including metering pump array control, pH fine-tuning control, fuzzy PID controller, etc.), nanobubble generator (modular design), gas chromatograph, atomic absorption spectrometer, etc. This example uses traditional butyl xanthate collector + high alkalinity conditions. The pH value of the pulp was adjusted to be greater than 11 by adding sodium hydroxide. Traditional butyl xanthate was added as a collector at a dosage of 250 g / t pulp. The flotation time was 15 min, with an aeration rate of 1.0 L / min in the roughing stage, 0.8 L / min in the scavenging stage, and 0.6 L / min in the cleaning stage. After flotation, lead concentrate and tailings were collected, and the content of metals such as Ag, Pb, and Cu was analyzed using atomic absorption spectrometry. The recovery rate was calculated, and the results are shown in Table 1. In this embodiment, a commercially available silver collector was used. The pH of the pulp was adjusted to 9-10 (sulfuric acid or sodium hydroxide can be used as the pH adjuster). A commercially available silver collector, sodium diethyldithiocarbamate, was added at a dosage of 220 g / t pulp. The flotation time was 15 min, with an aeration rate of 0.9 L / min in the roughing stage, 0.7 L / min in the scavenging stage, and 0.5 L / min in the cleaning stage. After flotation, lead concentrate and tailings were collected, and the content of metals such as Ag, Pb, and Cu was analyzed using atomic absorption spectrometry. The recovery rate was calculated, and the results are shown in Table 1. This embodiment uses the composite collector prepared in Example 1 of this invention. The pH value of the pulp was adjusted to 7.5 ± 0.3 using an intelligent pH controller. 200 g / t of the composite collector prepared in Example 1 of this invention was added to the pulp. Following the gradient flotation procedure, the aeration rate was set to 0.8 L / min for the roughing stage (1-5 min); 50 g / t of the composite collector prepared in Example 1 of this invention was added to the scavenging stage (5-10 min), with an aeration rate of 0.6 L / min; and for the cleaning stage (10-15 min), the aeration rate was 0.6 L / min for the scavenging stage (5-10 min) and 0.5 L / min for the cleaning stage (10-15 min), without adding any inhibitors.After flotation, lead concentrate and tailings were collected, and the content of metals such as Ag, Pb, and Cu was analyzed using atomic absorption spectrometry. The recovery rate was calculated, and the results are shown in Table 1. This embodiment uses the composite collector prepared in Example 1 of this invention, along with dynamic control conditions. During the refining stage, 10-15 g / t of sodium lignosulfonate was added as an inhibitor to the pulp, and other control conditions were the same as in Group C. The online zeta potential monitoring module was activated on the integrated operation console, and the measurement frequency was set to 1 Hz. The fuzzy PID controller automatically adjusted the collector addition rate based on the monitoring data. The operator monitored the operation of the actuators (metering pump array and pH fine-tuning unit) through the console. Flotation was performed according to the gradient flotation procedure, and the metal content of the lead concentrate and tailings was analyzed. The recovery rate was calculated, and the results are shown in Table 1. In Examples 4 and 5, a user-friendly intelligent pH controller was used to maintain the system pH within the range of 7.5 ± 0.3. This controller can monitor the pH value of the slurry in real time and automatically add sulfuric acid or sodium hydroxide for adjustment. This is beneficial for the interaction of the composite collector with the surface of lead, silver, and copper minerals, while reducing the use of alkaline reagents, lowering equipment corrosion, and reducing the difficulty and cost of treating mineral processing wastewater. Examples four and five employ a gradient flotation program, optimizing the aeration rate and reagent addition during the flotation process. This allows for better adaptation to different ore properties, and a parameter adjustment panel can be installed on the flotation equipment, facilitating operators to fine-tune parameters at each stage according to actual conditions.

[0049] Example 2: Flotation Comparative Example (Group A)

[0050] This embodiment uses a traditional butyl xanthate collector in combination with high alkalinity conditions.

[0051] The pH of the pulp was adjusted to be greater than 11 by adding sodium hydroxide. Traditional butyl xanthate was added as a collector at a dosage of 250 g / t pulp. The flotation time was 15 min, with an aeration rate of 1.0 L / min in the roughing stage, 0.8 L / min in the scavenging stage, and 0.6 L / min in the cleaning stage. After flotation, the concentrate and tailings were collected, and the content of metals such as Ag and Pb was analyzed using atomic absorption spectrometry. The recovery rate was calculated, and the results are shown in Table 1.

[0052] Example 3: Flotation Comparative Example (Group B)

[0053] This embodiment uses a commercially available silver collector.

[0054] Adjust the pH of the pulp to 9-10 (sulfuric acid or sodium hydroxide can be used as the pH adjuster). Add commercially available sodium diethyldithiocarbamate (220 g / t pulp) as a silver collector. The flotation time is 15 min, with an aeration rate of 0.9 L / min for roughing, 0.7 L / min for scavenging, and 0.5 L / min for cleaning. After flotation, collect the concentrate and tailings, analyze the content of metals such as Ag and Pb using atomic absorption spectrometry, and calculate the recovery rate. The results are shown in Table 1.

[0055] Example 4: Flotation Example (Group C)

[0056] This embodiment uses the composite collector prepared in Example 1 of the present invention.

[0057] The pH of the pulp was adjusted to 7.5 ± 0.3 using an intelligent pH controller. 200 g / t of the composite collector prepared in Example 1 of this invention was added to the pulp. Following the gradient flotation procedure, the aeration rate was set to 0.8 L / min for the roughing stage (1-5 min) via the flotation equipment parameter adjustment panel; for the scavenging stage (5-10 min), 50 g / t of the composite collector prepared in Example 1 of this invention was added, with an aeration rate of 0.6 L / min; for the cleaning stage (10-15 min), the aeration rate was 0.6 L / min for the scavenging stage (5-10 min) and 0.5 L / min for the cleaning stage (10-15 min), without adding any inhibitors. After flotation, the concentrate and tailings were collected, and the content of metals such as Ag and Pb was analyzed using atomic absorption spectrometry. The recovery rate was calculated, and the results are shown in Table 1.

[0058] Example 5: Flotation Example (Group D)

[0059] This embodiment uses the composite collector prepared in Example 1 of the present invention, plus dynamic control conditions.

[0060] During the selection stage, 10-15 g / t of sodium lignosulfonate was added as an inhibitor to the pulp, and other control conditions were the same as those in Group C.

[0061] On the integrated operation console, the online zeta potential monitoring module was activated, and the measurement frequency was set to 1Hz. The fuzzy PID controller automatically adjusted the collector addition rate based on the monitoring data. The operator monitored the operation of the actuators (metering pump array and pH fine-tuning unit) through the console. Flotation was carried out according to the gradient flotation procedure, and the metal content of the concentrate and tailings was analyzed. The recovery rate was calculated, and the results are shown in Table 1.

[0062] Examples 4 and 5 employ an easy-to-operate intelligent pH controller to maintain the system pH within the range of 7.5 ± 0.3. This controller can monitor the slurry pH value in real time and automatically add sulfuric acid or sodium hydroxide for adjustment. This not only facilitates the interaction between the composite collector and the silver mineral surface but also reduces the use of alkaline agents, lowers equipment corrosion, and reduces the difficulty and cost of treating mineral processing wastewater.

[0063] Examples four and five employ a gradient flotation program, optimizing the aeration rate and reagent addition during the flotation process. This allows for better adaptation to different ore properties, and a parameter adjustment panel can be installed on the flotation equipment to facilitate operators in fine-tuning the parameters at each stage according to actual conditions.

[0064] Example 6: Example of a dynamic drug control system

[0065] A dynamic reagent control system based on the zeta potential of mineral surfaces was established. This system includes an online zeta potential monitoring module with a measurement frequency of 1 Hz to monitor real-time changes in charge on the mineral surface; a fuzzy PID controller adjusts the collector addition rate based on the monitored zeta potential data. This system enables precise control over the addition of collectors; the actuator includes a metering pump array and a pH fine-tuning unit to ensure accurate execution of control commands. To simplify application, the system is integrated into a single control console, allowing operators to set and monitor parameters directly from the console.

[0066] In adjusting the formula for the rate of addition of the collector middle:

[0067] V: Represents the collector addition rate, the unit may be g / min, etc. (determined according to actual conditions). It is a variable that needs to be controlled for precise collector addition. ζ: Represents the zeta potential of the mineral surface, the unit is mV. It reflects the charge properties and quantity of the mineral surface and is data measured in real time by the online zeta potential monitoring module. Kp: Proportional coefficient, its magnitude affects the response speed to changes in zeta potential, dimensionless (related to system characteristics). It determines the degree of direct influence of the absolute value of the zeta potential on the collector addition rate. Ki: Integral coefficient, the unit is min. -1 , used to adjust the contribution of the integral term to the collector addition rate, reflects the degree of importance attached to the cumulative effect of zeta potential changes. Kd: differential coefficient, in min, reflects the degree of response to the rate of zeta potential change.

[0068] At a certain moment, the zeta potential of the mineral surface was measured to be ζ ​​= -20mV, Kp = 0.1, and Ki = 0.05min.-1 Kd = 0.2 min, the integral of ζ over a previous period is ∫ζdt = -100mV The rate of change of ζ is dζ / dt = -5mV / min, so V = -4 is calculated according to the above formula.

[0069] The calculated V value here is -4 (assuming the unit is g / min). The negative sign indicates that the collector addition rate needs to be reduced at this moment according to the model calculation (the addition rate in actual applications cannot be negative, and may indicate an adjustment direction opposite to the set positive addition, which needs to be determined in conjunction with the system settings).

[0070] II. Experimental Results and Analysis

[0071] (a) Comparison of key data: After repeated experiments, the average data shown in Table 1 were obtained.

[0072] Table 1

[0073] Group A Group B Group C Group D Ag recovery rate (%) 82.3 85.6 89.2 92.7 Pb recovery rate (%) 75.1 78.4 83.6 87.9 Drug cost (RMB / ton) 12.4 10.8 8.7 7.9 Wastewater treatment cost (RMB / t) 5.8 4.3 3.2 2.9

[0074] (II) Microscopic Mechanism Verification

[0075] (1) Synchrotron XANES analysis: Synchrotron radiation was performed on mineral samples from groups A and D.

[0076] XANES analysis showed that the Ag-S coordination number of group A was 2.3, while that of group D was increased to 3.1, indicating that the process of the present invention can form more stable chemical bonds between silver minerals and collectors, thereby enhancing the collection effect.

[0077] (2) AFM force curve measurement: The adhesion force between minerals and bubbles in groups A and D was measured using AFM force curve. The adhesion force in group A was 8.6 nN, while that in group D increased to 12.7 nN, which is 47% higher. This shows that the process of the present invention can effectively enhance the adhesion between minerals and bubbles and improve flotation efficiency.

[0078] (III) Validation of the machine learning-based flotation parameter optimization model

[0079] A machine learning-based flotation parameter optimization model was developed. Through training on 2000 sets of experimental data, the optimal control strategy for different ore properties and flotation conditions was obtained, further improving flotation efficiency and metal recovery rate. To facilitate use in concentrators, this model was developed into user-friendly software. Operators only need to input the basic properties of the ore and the current flotation conditions, and the software will provide the optimized flotation parameters. Details are as follows:

[0080] 1. Select another 100 groups of ore samples with different properties. The operator inputs the basic properties of the ore and the current flotation conditions into the flotation parameter optimization model software based on machine learning to predict the optimal flotation parameters for each group of ore, including collector dosage, aeration rate, flotation time, etc.

[0081] 2. Flotation experiments were conducted according to the predicted parameters and compared with conventional flotation processes that did not use the model. The results showed that in the flotation experiments using the model, the average silver recovery rate increased by 3.5%, and the average lead recovery rate increased by 3.2%, further validating the effectiveness of the model.

Claims

1. A method for low alkalinity flotation of lead-zinc (silver-bearing) polymetallic ores based on heterocyclic thiolate complexing polymers, characterized by that: Adjusting the pH value of the ore pulp to 7.5±0.3, using a composite collector and sequentially performing roughing, scavenging and cleaning according to a gradient flotation procedure; The mass concentration of the ore pulp is 20% to 40%; and the composite collector is added in an amount of 150 to 300 g / t of the ore pulp. The composite collector is prepared according to the following method: Step one, preparing a modified heterocyclic mercapto compound (1) Preparing a coordination polymer 2-amino-5-mercapto-1,3,4-thiadiazole and 2-mercaptobenzimidazole are used as raw materials in a molar ratio of (3 to 5):1, and a transition metal catalyst is added to promote the reaction in an organic solvent at a temperature of 20 to 80°C. The two raw materials are coordinated and polymerized. (2) Preparing a modified heterocyclic mercapto compound 4-mercaptopyridine and the coordination polymer prepared in step (1) are added to a reaction kettle in a ratio of 2:1 to 3:1, an organic solvent is added, the two raw materials are dissolved by stirring, and a transition metal catalyst is added to promote the reaction. The reaction is stirred at 40 to 60°C. Then, the insoluble impurities are removed, the organic solvent is removed, and finally the product is purified to obtain the modified heterocyclic mercapto compound. Step two, preparing a star-branched nonionic surfactant Pentaerythritol triacrylate and polyethylene glycol monomethyl ether are used as raw materials in a molar ratio of 1:(3 to 5), an organic solvent and a copper catalyst are added, and the reaction is stirred at 20 to 50°C under inert gas protection to obtain a star-branched nonionic surfactant with a molecular weight of 2000 to 5000 Da. Step three, preparing a composite collector The modified heterocyclic mercapto compound prepared in step one, C12-C18 alkyl amine polyoxyethylene ether, and the star-branched nonionic surfactant prepared in step two are mixed in a mass ratio of 1:(1 to 3):(0.5 to 2) to obtain the composite collector.

2. The method for low alkalinity floatation of lead-zinc (containing silver) polymetallic ore based on heterocyclic sulfhydryl coordination polymers according to claim 1, characterized in that: In step one (1), the transition metal catalyst is NiCl2, which is added in an amount of 3% to 5% of the mass of 2-amino-5-mercapto-1,3,4-thiadiazole, and the reaction time is 12 to 18 hours.

3. The method for low alkalinity floatation of lead-zinc (silver-bearing) polymetallic ore based on heterocyclic mercapto coordination polymers according to claim 1, characterized in that: In step one (2), the transition metal catalyst is NiCl2, which is added in an amount of 2% to 4% of the mass of 4-mercaptopyridine, and the reaction time is 8 to 12 hours.

4. The method for low alkalinity floatation of lead-zinc (silver-bearing) polymetallic ore based on heterocyclic mercapto coordination polymers according to claim 1, characterized in that: In step two, the copper catalyst is tetrakis(triphenylphosphine)copper(I), which is used in an amount of 1% to 3% of the mass of pentaerythritol triacrylate, and the reaction time is 12 to 24 hours.

5. The method for low alkalinity floatation of lead-zinc (silver-bearing) polymetallic ore based on heterocyclic mercapto coordination polymers according to claim 1, characterized in that: In step three, the C12-C18 alkyl amine polyoxyethylene ether is octadecyl amine polyoxyethylene ether, and the mass ratio of the modified heterocyclic mercapto compound, octadecyl amine polyoxyethylene ether, and star-branched nonionic surfactant is 1:2:

1.

6. The process for low alkalinity flotation of lead-zinc (silver bearing) polymetallic ores based on heterocyclic mercapto ligand complexes according to any one of claims 1 to 5, characterized in that The adjusting the pH value of the ore pulp to 7.5±0.3, using a composite collector and sequentially performing roughing, scavenging and cleaning according to a gradient flotation program refers to: using an intelligent pH controller to adjust the pH value of the ore pulp to 7.5±0.3, first adding the composite collector 200g / t of ore pulp; then setting the roughing stage (1~5min) air supply amount to 0.8L / min through the flotation equipment parameter adjustment panel; the scavenging stage (5~10min), supplementing the composite collector 50g / t of ore pulp, the air supply amount is 0.6L / min; the cleaning stage (10~15min), the scavenging stage (5~10min) air supply amount is 0.6L / min, the cleaning stage (10~15min) air supply amount is 0.5L / min.

7. The process for low alkalinity flotation of lead-zinc (silver bearing) polymetallic ores based on heterocyclic mercapto ligand complexes according to any one of claims 1 to 5, characterized in that: The inhibitor sodium lignosulfonate 10~15g / t of ore pulp is added in the cleaning stage.

8. The process for low alkalinity flotation of lead-zinc (silver bearing) polymetallic ores based on heterocyclic mercapto ligand complexes according to any one of claims 1 to 5, characterized in that: The online zeta potential monitoring module is started on the integrated operation console, the measurement frequency is set to 1Hz, the fuzzy PID controller automatically adjusts the collector addition rate according to the monitoring data, and the operator monitors the operation of the actuator through the console.

9. A process for low alkalinity flotation of lead-zinc (silver bearing) polymetallic ores based on heterocyclic thiol ligand complexing polymers according to any one of claims 8, characterized in that: The fuzzy PID controller adjusts the collector addition rate according to the following formula: ; in the formula, V represents the collector addition rate, Kp is a proportional coefficient, ζ represents the zeta potential of the mineral surface, Ki is an integral coefficient, Kd is a differential coefficient, and dζ / dt represents the rate of change of ζ.