Mine water heavy metal fractionation precipitation and flocculation sedimentation separation method

Abstract

The application discloses a kind of mine water heavy metal grading precipitation and flocculation sedimentation separation method, it is related to mine water treatment and heavy metal separation technical field, with copper, zinc mine water filtration, deoxygenation and adjust to copper section condition, under copper sulfide seed circulation, sulfurizing agent is divided into first-stage sulfurizing agent and secondary sulfurizing agent;First-stage sulfurizing agent is determined according to seed dry mass and BET specific surface area, first with seed millisecond level precontacting, after transient high shear, then mixed with mine water, then low shear grows, decreasing speed gradient flocculation, clarification and cyclone classification, backflow seed particle size and according to solid content and product dry solid flow rate are discharged copper sulfide product in cascade control.Copper section effluent is adjusted to zinc section condition, and then treated in the same order with zinc sulfide seed.The method includes the closed loop of seed BET total area, sulfurizing agent feeding, contact order, shear timescale, pS* compensation and product discharge, maintains the stable operation of grading precipitation and solid-liquid separation.

Description

Technical Field

[0001] This invention relates to the field of mine water treatment and heavy metal separation technology, specifically a method for the graded precipitation and flocculation sedimentation separation of heavy metals in mine water. Background Technology

[0002] Acidic mine water, leachate from waste rock piles, and wastewater from low-grade mine piles often contain copper, zinc, iron, aluminum, and high concentrations of sulfate ions. Existing treatment methods typically involve lime or alkali neutralization, hydroxide precipitation, sulfide precipitation, flocculation sedimentation, and pressure filtration. Sulfide precipitation can selectively remove copper at lower pH levels and continue to precipitate zinc at higher pH levels, thus possessing the potential for fractional recovery of valuable metals. To improve the sedimentation and filtration performance of sulfide particles, existing methods also employ pH or sulfide electrode control, seed crystal reflux, multi-point dosing, static mixing, and polyacrylamide flocculation. However, the reaction rate between copper and zinc ions and the sulfiding agent is usually significantly faster than the macroscopic mixing rate in large reactors. Even if the reactor's average pH or sulfide electrode reading is within the set range, a short-term high sulfide concentration zone may still form near the dosing port, causing homogeneous nucleation in the bulk phase to reach the seed crystal surface before the sulfides, forming submicron or multimicron fine particles. These fine particles have a high surface charge, making them easy to penetrate the clarifier and form a high specific resistance filter cake. Increasing the amount of flocculant added can temporarily form flocs, but it may increase the product moisture content, organic matter entrainment, and subsequent treatment load.

[0003] On the other hand, if the sulfiding agent is added in excess to ensure the removal rate, hydrogen sulfide is easily generated and escaped in the acidic copper section, and zinc enters the copper product prematurely; if only the feedback of the terminal sulfide electrode is relied upon, the feedback signal usually lags behind the local nucleation history that has already occurred at the dosing point.

[0004] Furthermore, in existing schemes, seed stock, seed BET specific surface area, sulfiding agent flow rate, micromixing energy, product discharge, and particle size classification are often set separately, lacking unified dynamic constraints. As the seed surface area changes over operating time, a fixed dosage can easily cause surface load drift, while a fixed sludge discharge may destabilize the reactor's solids age and particle size distribution. Therefore, a fractional sedimentation method is needed that can simultaneously constrain the instantaneous load of the sulfiding agent on the seed surface, the contact sequence between the sulfiding agent and the seed and aqueous metal phase, the shear timescale, end-of-pipe sulfide compensation, and seed stock, to improve the stability of copper-zinc fractional recovery and subsequent flocculation and sedimentation separation. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a method for the graded precipitation and flocculation sedimentation separation of heavy metals in mine water. In mine water with high sulfate content, multiple associated ions, and fluctuating influent load, this method reduces local homogeneous nucleation and sulfide penetration near the sulfiding agent dosing point, avoids particle breakage caused by continuous high shear, and forms copper sulfide and zinc sulfide particles that can be clarified, graded, refluxed, and continuously discharged with a lower flocculant dosage.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for separating heavy metals in mine water through graded precipitation and flocculation sedimentation involves filtering, deoxygenating, and temperature-regulating copper- and zinc-containing mine water to reduce the dissolved oxygen concentration to no higher than 0.30 mg / L, adjusting the pH at the copper section inlet to 2.95-3.05, and establishing a copper sulfide seed slurry circulation system in the copper section reactor. The total sulfiding agent in the copper section is divided into primary and secondary sulfiding agents, with the primary sulfiding agent accounting for 82%-90% of the total. Based on the most recently measured dry mass and BET specific surface area of ​​the seed crystals in the reactor, the primary sulfur load, normalized to the total BET area of ​​the seed crystals, is controlled at 30-80 μmol / (m²·h).

[0010] The primary sulfiding agent first enters the copper sulfide seed enrichment zone through radial nozzles. Conductivity pulse tracking ensures its median residence time (t50) in the seed enrichment zone is 4-10 ms. It then merges with mine water, which is the aqueous phase containing the target metal. A unit mass energy dose of 40-120 J / kg is applied within 0.06-0.15 s, followed immediately by a velocity gradient of 35-60 s. -1 Low-shear growth region.

[0011] The secondary sulfiding agent is only used to compensate for residual copper load, influent analysis error and sulfiding agent oxidation loss, and is adjusted according to the operational apparent sulfide activity index pS* to maintain the copper segment pS* at 24.5-25.5.

[0012] The copper slurry is rapidly mixed with low-charge cationic polyacrylamide and then subjected to three-stage decreasing velocity gradient flocculation before entering the clarifier. The underflow of the clarifier is classified by hydrocyclone, and the copper sulfide seed crystals obtained from the classification are returned to the copper section reactor. The copper sulfide product is continuously discharged by cascade control of reactor solid content and product dry solids flow rate.

[0013] The clarified solution of the copper segment was adjusted to pH 5.70-6.30 and used as the aqueous phase containing the target metal in the zinc segment. A zinc sulfide seed slurry was circulated in the zinc segment. The total sulfiding agent for the zinc segment was added according to the same segment ratio as in the copper segment, the same BET total area loading method for seed crystals, the millisecond-level contact sequence of seed crystals followed by aqueous phase, and the transient high-shear to low-shear growth relationship, and zinc precipitation was implemented. This resulted in a primary sulfur loading of 50-120 μmol / (m²·h) in the zinc segment and a velocity gradient of 30-55 s in the low-shear growth region of the zinc segment. -1 The pS* value is 17.7-18.4.

[0014] The zinc slurry undergoes rapid polyacrylamide mixing, decreasing rate gradient flocculation, clarification, and particle size classification in the same manner as the copper slurry. The zinc sulfide seed crystals obtained from the classification are returned to the zinc slurry reactor, and the zinc sulfide product is continuously discharged.

[0015] Both the copper and zinc sections determine the primary sulfurizing agent flow rate based on the most recent seed dry mass and BET specific surface area. Seed inventory is maintained by cascade control of reactor solid content and product dry solid flow rate. Solid steady state is determined by solid age and material balance. Safety interlocks are formed by dual pS* probes, tail gas hydrogen sulfide, equipment negative pressure, seed circulation volume, and micro-mixer pressure difference.

[0016] In this invention, the above technical solution is divided into five steps according to the operation sequence: the filtration, deoxygenation and pH adjustment of the mine water inlet are recorded as step S1; the establishment of copper segment seed slurry circulation, the segmented addition of total sulfiding agent, the millisecond-level contact between the primary sulfiding agent and the seed crystal, transient high shear, low shear growth and secondary sulfiding agent compensation based on pS* are recorded as step S2; the rapid mixing of copper segment slurry with polyacrylamide, the decreasing velocity gradient flocculation, clarification, particle size classification, seed crystal reflux particle size return and continuous discharge of copper sulfide products are recorded as step S3; the pH adjustment of copper segment clarified liquid, the establishment of zinc segment seed slurry circulation and the addition of zinc segment total sulfiding agent according to the method described in step S2 are recorded as step S4; the zinc segment slurry is treated according to the method described in step S3 and continuously discharged as zinc sulfide products are recorded as step S5.

[0017] Preferably, the copper sulfide seed crystals in the copper section reactor have a solid content of 40-70 g / L, a D50 of 30-50 μm, and a BET specific surface area of ​​4.0-7.0 m² / g, with copper sulfide accounting for no less than 90% of the mass fraction of crystalline sulfides in the seed crystals; the zinc sulfide seed crystals in the zinc section reactor have a solid content of 40-70 g / L, a D50 of 20-40 μm, and a BET specific surface area of ​​3.0-6.0 m² / g; and the ratio of seed crystal circulation rate to corresponding influent flow rate is 0.75-0.95 for both the copper and zinc sections.

[0018] Preferably, the measurement interval for the BET specific surface area of ​​the copper and zinc sections is no longer than 24 hours. When the change in the BET specific surface area of ​​the corresponding treatment section relative to the previous measurement value exceeds 20%, the flow rate of the primary vulcanizing agent in that treatment section is recalculated. The measurement interval for the solid content of the reactor is no longer than 8 hours.

[0019] Preferably, the molar ratio of total sulfiding agent to copper in the copper segment is 0.995-1.015, and the nominal residence time of the low-shear growth zone in the copper segment is 16.5-20.0 min; the molar ratio of total sulfiding agent to zinc in the zinc segment is 1.000-1.025, and the nominal residence time of the low-shear growth zone in the zinc segment is 25.5-31.0 min.

[0020] In this invention, the operational apparent sulfide activity index pS* is not the absolute thermodynamic S. 2- Activity is not the process control index, but rather a process control index obtained by calibrating a double silver / silver sulfide electrode with an oxygen-free medium that matches the pH, temperature, sulfate concentration, main cation composition, and ionic strength of the water sample at the corresponding treatment stage, using an offline-defined four-stage sulfide standard solution.

[0021] Linear regression was performed on each electrode separately, and the calibration relationship is shown in the following formula:

[0022]

[0023] In the formula, k is the electrode number, k=1 or 2; Ek is the stable potential of the k-th electrode, in mV; E0,k is the intercept obtained by the k-th electrode in the matrix matching four-point calibration, in mV; Sk is the effective slope of the k-th electrode, in mV / decade; pSop,k is the operability index calculated for the k-th electrode, and is used as the pS* value of that electrode. When the difference between the pS* values ​​of the two electrodes is not greater than 0.50 pS* units, the process control value is taken as the arithmetic mean of the two; if the difference exceeds this value, the pS* value of this cycle is determined to be invalid and a safe fixed flow rate or emergency pool switching is performed.

[0024] In this invention, the primary sulfur load, normalized to the total BET area of ​​the seed crystals, is determined according to the following formula:

[0025]

[0026] In the formula, ΦS,1 is the normalized first-order sulfur load of the total BET area of ​​the seed crystals, in μmol / (m²·h); is the effective sulfur molar flow rate of the primary vulcanizing agent, in μmol / h; Aseed is the total BET surface area of ​​the seed crystals in the reactor, in m²; Mseed is the dry mass of the seed crystals, in kg; aBET is the BET specific surface area measured according to the specified sampling, washing, drying, and degassing methods, in m² / g. It is calculated by multiplying the effective sulfur molar concentration of the primary vulcanizing agent by the volumetric flow rate of the primary vulcanizing agent; 1000 is the unit conversion factor for converting kg to g.

[0027] The energy dose per unit mass of a micromixer is determined by the following formula:

[0028]

[0029] In the formula, Em is the unit mass energy dose, in J / kg; ΔP is the inlet and outlet static pressure difference measured by the micromixer under stable full liquid condition, in Pa; ρslurry is the measured density of the mixed slurry under the same temperature as the pressure difference measurement, in kg / m³. The density of the mixed slurry is determined using a calibrated vibratory densitometer or a specific gravity bottle, and the pressure difference is taken as the average value of stable records for no less than 60s.

[0030] The acid load generated by sulfide precipitation in the copper and zinc sections is controlled by a combination of sodium hydroxide feedforward and pH feedback. The sodium hydroxide volumetric flow rate is determined according to the following formula:

[0031]

[0032] In the formula, Q is the influent volumetric flow rate, in L / h; Atitr is the titration alkalinity required to titrate a unit volume of water sample from the current pH to the target pH, in mol / L; To generate the corresponding H for the target metal sulfide + Acid production equivalent flow rate, in mol / h; OH- introduced by the vulcanizing agent working fluid - The titratable alkali equivalent flow rate is expressed in mol / h; CNaOH is the measured equivalent concentration of the sodium hydroxide working solution, expressed in mol / L; FNaOH and Ffb are both expressed in L / h. Ffb is the pH feedback correction amount, with a positive value indicating an increase in sodium hydroxide flow rate and a negative value indicating a decrease in sodium hydroxide flow rate, and the total flow rate after correction must not be less than zero. Atitr is determined by titrating to the corresponding target pH with a calibrated sodium hydroxide standard solution at 25.0±0.5℃ under nitrogen protection, and after blank correction.

[0033] Atitr, the titration alkalinity, is calculated using the following formula:

[0034]

[0035] In the formula, Cb is the measured equivalent concentration of sodium hydroxide standard solution, in mol / L; Vb is the volume of standard solution consumed in titrating the water sample to the target pH, in L; V0 is the volume consumed in the blank test, in L; and Vs is the volume of the water sample, in L.

[0036] The theoretical solid age is calculated using the following formula:

[0037]

[0038] In the formula, τs is the theoretical solid age in hours (h); Mseed is the dry mass of the seed crystals in the reactor in kilograms. The product dry solids flow rate is expressed in kg / h. It is obtained by multiplying the product slurry mass flow rate by the simultaneously measured dry solids content.

[0039] (III) Beneficial Effects

[0040] This invention provides a method for the fractional precipitation and flocculation sedimentation separation of heavy metals in mine water, which has the following beneficial effects:

[0041] A unified dynamic feeding constraint is established using the primary vulcanizing agent molar flow rate, seed crystal dry mass, and BET specific surface area. The primary vulcanizing agent flow rate is recalculated when the BET specific surface area changes by more than 20%, ensuring that the primary vulcanizing agent load corresponds to the seed crystal surface area inventory. The contact between the primary vulcanizing agent and the seed crystals is confined to a millisecond-level seed enrichment region, with high shear confined to a subsequent short-time mixing region. After leaving the mixing region, the process transitions to a low-shear growth region, allowing interfacial mixing and particle growth to occur at different time scales.

[0042] The primary vulcanizing agent bears the main precipitation load constrained by the total BET area of ​​the seed crystals. The secondary vulcanizing agent only compensates for the residual load and vulcanizing agent loss based on pS*, and is used to reduce the operating conditions where the secondary addition point again bears the main precipitation load and free sulfide accumulation. Decreasing rate gradient flocculation, clarification, cyclone classification, seed crystal reflux, and continuous product discharge together form a solid inventory closed loop, enabling measurable control over seed crystal quantity, particle size distribution, product dry solids flow rate, and solids age.

[0043] The copper and zinc sections use copper sulfide seed crystals and zinc sulfide seed crystals respectively, and pH and pS* control windows are set separately to avoid mixing of seed crystals, feed and control parameters between the two treatment sections, and to maintain the continuous operation of copper and zinc graded precipitation. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the overall process of the method for separating heavy metals in mine water by graded precipitation and flocculation sedimentation according to the present invention.

[0045] Figure 2 This is a schematic diagram of the single-stage isophase seed precipitation, low-shear growth, flocculation sedimentation and seed classification reflux process of the present invention.

[0046] Figure 3 This is a schematic diagram of the structure of the three-stream coaxial micromixer of the present invention;

[0047] Figure 4This is a schematic diagram of the control logic for vulcanizing agent feeding, seed crystal storage, product discharge, and safety interlocking in this invention.

[0048] Figure labeling: 110, Raw water buffer and filtration unit; 120, Vacuum deoxygenation and copper segment pH adjustment unit; 200, Copper sulfide homogeneous seed micro-mixing and sedimentation unit; 201, Aqueous phase containing target metal; 202, Homogeneous seed slurry; 203, Primary sulfiding agent; 204, Three-stream coaxial micro-mixer; 205, Low-shear growth tank; 206, Secondary sulfiding agent; 207, Decreasing velocity gradient flocculation unit; 208, Clarifier; 209, Hydrocyclone classification unit; 210, Copper sulfide seed slurry; 211, Coarse product; 221, Central inlet; 222, Annular seed slurry channel; 223, Radial nozzle; 224, Mixing throat; 225, Mixed slurry outlet; 230, Copper segment low-shear growth and secondary pS* compensation unit; 250, Copper segment flocculation clarification and cyclone classification unit; 270, Copper sulfide product; 30 0. Zinc segment pH adjustment unit; 400. Zinc sulfide homogeneous seed micro-mixing precipitation and growth unit; 410. Zinc sulfide seed slurry; 450. Zinc segment flocculation clarification and cyclone classification unit; 470. Zinc sulfide product; 480. Treated effluent; 500. Two-stage tail gas scrubbing and hydrogen sulfide interlock unit; 600. Control unit; 601. Inlet flow rate and target metal concentration; 602. Seed dry mass and BET specific surface area; 603. First-stage sulfiding agent surface area load feedforward calculation; 604. Dual pS* probes; 605. pS* calibration and effectiveness determination; 606. Second-stage sulfiding agent feedback compensation; 607. Reactor solids content and product slurry solids content; 608. Product dry solids flow rate and seed reflux cascade control; 609. Safety interlock input signal; 610. Safety interlock and emergency pool switching; 611. Controlled actuator. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] The present invention will be further described below with reference to the accompanying drawings and embodiments. The following embodiments are used to illustrate the process structure, parameter determination method and operation steps of the present invention, and are not intended to limit the scope of protection of the present invention.

[0051] refer to Figures 1 to 4This invention provides a method for the graded precipitation and flocculation sedimentation separation of heavy metals in mine water. Under the premise of not changing the total area load constraint of seed crystals, the primary sulfiding agent first contacting the corresponding metal sulfide seed crystals and then contacting the water phase containing the target metal, transient high shear to low shear growth, secondary pS* compensation, and the closed-loop relationship of seed crystal inventory, the equipment volume and reagent flow rate are determined according to the actual water volume, the target metal load of the influent, and the material balance relationship.

[0052] Combination Figure 1 Mine water containing copper and zinc ions passes sequentially through a raw water buffer and filtration unit 110 and a vacuum deoxygenation and copper section pH adjustment unit 120 before entering a copper sulfide homogeneous seed micro-mixing precipitation unit 200. Under the circulation of copper sulfide seed slurry 210, copper sulfide precipitation is completed. The precipitated slurry then passes through a copper section low-shear growth and secondary pS* compensation unit 230 before entering a copper section flocculation clarification and cyclone classification unit 250. The seed crystals obtained from the classification are returned to the copper sulfide homogeneous seed micro-mixing precipitation unit 200, while the product particles are discharged as copper sulfide product 270. The clarified solution from the copper segment enters the zinc sulfide homogeneous seed micro-mixing precipitation and growth unit 400 via the zinc segment pH adjustment unit 300. Under the circulation of the zinc sulfide seed slurry 410, zinc sulfide precipitation is completed. Subsequently, it enters the zinc segment flocculation clarification and cyclone classification unit 450. The seed crystals obtained from classification are returned to the zinc sulfide homogeneous seed micro-mixing precipitation and growth unit 400, while the product particles are discharged as zinc sulfide product 470, and the clarified solution is discharged as treated effluent 480. The gas phases from the copper and zinc segments are respectively connected to a two-stage tail gas scrubbing and hydrogen sulfide interlock unit 500. The control unit 600 implements centralized control of sulfiding agent feeding, seed crystal storage, product discharge, and safety interlocks using a feedforward calculation and product discharge closed-loop control method.

[0053] Combination Figure 2In the single-stage isophase seed precipitation, low-shear growth, flocculation sedimentation, and seed classification reflux process, the target metal-containing aqueous phase 201, isophase seed slurry 202, and primary vulcanizing agent 203 are respectively connected to a three-flow coaxial micro-mixer 204. The primary vulcanizing agent 203 first contacts the isophase seed slurry 202 in the seed enrichment zone, and then merges with the target metal-containing aqueous phase 201 and enters the low-shear growth tank 205 after transient high shear. A low-shear growth zone is formed in the low-shear growth tank 205, and the secondary vulcanizing agent 206 compensates in this zone based on pS* feedback. The flow rate of the primary vulcanizing agent 203 is determined by the primary vulcanizing agent surface area load feedforward calculation 603, and the discharge of product particle size is determined by the product dry solids flow rate and seed reflux cascade control 608. The grown slurry passes sequentially through a decreasing velocity gradient flocculation unit 207 and a clarifier 208. The clarified liquid from the clarifier 208 enters the next processing stage, and the underflow from the clarifier 208 enters a hydrocyclone classification unit 209. The hydrocyclone classification unit 209 divides the underflow into a seed reflux particle size that returns to the three-stream coaxial micro-mixer 204 and a product particle size that is discharged as coarse product 211.

[0054] Combination Figure 3 The three-flow coaxial micro-mixer 204 includes a central inlet 221, an annular seed slurry channel 222, radial nozzles 223, a mixing throat 224, and a mixed slurry outlet 225. The target metal aqueous phase 201 enters axially from the central inlet 221, the same phase seed slurry 202 enters from the annular seed slurry channel 222 and forms a seed enrichment zone in the channel, and the primary sulfurizing agent 203 is injected into the seed enrichment zone through the radial nozzles 223 set in the annular seed slurry channel 222. Subsequently, the materials converge in the mixing throat 224 and complete transient high-shear mixing. The mixed slurry is discharged from the mixed slurry outlet 225.

[0055] Combination Figure 4 Under normal control conditions, the control unit 600 uses the influent flow rate and target metal concentration 601, as well as the dry mass of the seed crystals and the BET specific surface area 602 as inputs, and determines the flow rate of the primary sulfurizing agent through the feedforward calculation 603 of the surface area load of the primary sulfurizing agent; the readings of the dual pS* probes 604 are used for secondary sulfurizing agent feedback compensation 606 after pS* calibration and validity determination 605; the solid content of the reactor and the solid content of the product slurry 607 are maintained by the cascade control 608 of the dry solids flow rate of the product and the seed crystal reflux to maintain the seed crystal inventory and solid age; the safety interlock input signal 609 is applied to the controlled actuator 611 through the safety interlock and emergency pool switching 610.

[0056] I. Terminology, Parameter Definitions, and Measurement Diameter

[0057] In this invention, the seed enrichment zone refers to the flow space within the reactor or mixer occupied by the same-phase seed slurry, where the primary sulfiding agent first contacts the seed crystals but has not yet merged with the aqueous phase containing the target metal; the low-shear growth tank is the tank equipment that forms the low-shear growth zone, which is the flow region within the tank where the velocity gradient is within a specified range; particle size classification refers to the operation of dividing the clarifier underflow into seed return particle size and product particle size according to the particle size, with cyclone classification and hydraulic cyclone classification being specific implementations of particle size classification; decreasing velocity gradient flocculation refers to the flocculation operation where the velocity gradient decreases step by step, with three-stage decreasing velocity gradient flocculation being a specific implementation when the number of stages is three.

[0058] In this invention, the Chinese name and corresponding symbol or abbreviation of the same object refer to the same object: sodium hydrosulfide is denoted as NaHS, polyacrylamide as PAM, sodium hydroxide as NaOH, hydrogen sulfide as H2S, copper sulfide as CuS, zinc sulfide as ZnS, and copper ion as Cu. 2+ Zinc ions are denoted as Zn. 2+ Residence time distribution is denoted as RTD; BET specific surface area refers to the specific surface area determined by the Brunauer-Emmett-Teller method for nitrogen adsorption; D10, D50 and D90 refer to the equivalent particle size when the cumulative volume distribution reaches 10%, 50% and 90%, respectively.

[0059] Calibration and use of pS*:

[0060] The sulfide mother liquor was first valued using acidification distillation absorption spectrophotometry, and then four working standards were prepared stepwise in oxygen-free matrices matched with the copper or zinc water samples. When matching the matrix, the pH deviation should not exceed ±0.02, the temperature deviation should not exceed ±0.5℃, the sulfate concentration deviation should not exceed ±5%, the major cation concentration deviation should not exceed ±10%, and the ionic strength deviation calculated based on the measured conductivity should not exceed ±10%. The four standards should cover the target control range, with at least one standard point set below the lower limit and above the upper limit of the control range.

[0061] The assignment of the Level 4 work standard is pS*. Determined. In the formula, pS*k is the assigned value pS* for the k-th level working standard, k=1, 2, 3, 4; CT,k is the measured total dissolved sulfide concentration of the k-th level working standard, in mol / L, calculated from the mother liquor concentration and preparation volume according to the dilution relationship; Δj is the conventional constant for the treatment section, which is specified as 20.0 for the copper section and 14.0 for the zinc section in this invention.

[0062] The above-mentioned Δ value is the fixed benchmark for determining the pS* scale in this invention and is not changed due to differences in the values ​​of the hydrogen sulfide second-order ionization constant in the literature; indices obtained using other Δ values ​​or other conversion methods are not considered pS* in this invention. The difference in Δ values ​​between the copper and zinc sections is 6.0, which is consistent with the pH control of the two treatment sections at (3.000 and 6.000) for S. 2- The difference corresponds to approximately six orders of magnitude in the total dissolved sulfide mole fraction; therefore, the same free sulfide concentration gives different pS* values ​​in the two treatments, and the two are not interchangeable.

[0063] Since the working standards and the corresponding treatment section water samples have been matched with the matrix according to the aforementioned specifications in terms of pH, temperature, sulfate concentration, main cation composition, and ionic strength, S 2- The activity coefficients cancel each other out between calibration and measurement. Therefore, the value pS* is calculated based on the total dissolved sulfide molar concentration and no longer introduces a separate activity coefficient term. This is the meaning of the term "operational apparent index".

[0064] As per the above agreement, the copper segment control window pS*24.5-25.5 corresponds to a total dissolved sulfide concentration of 0.10-1.01 mgS / L under matrix-matched conditions, while the zinc segment control window pS*17.7-18.4 corresponds to 1.28-6.40 mgS / L. The corresponding four working standards cover approximately 0.05-2.02 mgS / L and 0.64-12.76 mgS / L, respectively, both within the conventional determination range of acid distillation absorption spectrophotometry. Calibration was performed at 25.0±0.2℃; the difference between the electrode temperature and the calibration temperature during process measurement did not exceed ±3.0℃, and the calibration slope was converted to the measurement temperature according to the relationship that the effective slope is proportional to the thermodynamic temperature.

[0065] The standard operating procedure is to prepare and use the solution immediately under closed, anaerobic conditions. For each stage, the batch number of the mother liquor, the measured total dissolved sulfide concentration, the preparation volume, the stable potential, and the assigned pS* value are recorded. Two silver / silver sulfide electrodes are calibrated at four points at 25.0±0.2℃, and pS* is calculated according to the aforementioned calibration equation. The linear correlation coefficient is not less than 0.995, the effective slope is 26-32 mV / decade, the 90% response time is not greater than 45 s, the difference between the two probes is not greater than 0.50 pS* units, and the zero-point drift over 8 hours is not greater than 3 mV. The process pS* is the arithmetic mean of the calculated values ​​from the two effective probes. The controller takes the median of the effective process values ​​from the most recent 60 seconds, and performs a maximum of one adjustment to the secondary sulfiding agent flow rate every 60 seconds. If any effectiveness index is exceeded, the secondary sulfiding agent branch is locked at a safe, fixed flow rate determined through commissioning, automatic increase is prohibited, and the effluent is switched to the emergency tank. pS* is only used for process comparisons within the same treatment section, the same matrix matching caliber, and the effective calibration period. It does not directly convert to total sulfide concentration across copper and zinc sections.

[0066] Determination and updating of the total area of ​​BET:

[0067] Before seed crystal sampling, the seed crystal circulation loop should be run stably at the set flow rate for at least 10 minutes. Three equal-volume slurry samples should be continuously obtained from the same sampling point and combined into a mixed sample. The mixed sample should be filtered under nitrogen protection, rapidly washed with deoxygenated water, and vacuum dried at 40℃ to constant weight. The constant weight criterion is that the mass change between two consecutive weighings with an interval of 1 hour should not exceed 0.10%. Before nitrogen adsorption determination, the sample should be degassed at 40℃ and an absolute pressure not exceeding 100 Pa for at least 6 hours. At least 5 effective points should be selected within the relative pressure range of 0.05-0.30, and the specific surface area should be calculated using the multi-point BET method, with a linear regression correlation coefficient not less than 0.999. For each determination, three parallel samples should be taken from the mixed sample. If the relative standard deviation of the parallel results does not exceed 5%, the arithmetic mean should be taken. If it exceeds 5%, the sample should be resampled and determined. The dry mass Mseed of the reactor seed crystals is determined by multiplying the effective volume by the synchronously measured dry solid content. The dry solid content is measured at least once every 8 hours, and the BET specific surface area is measured at least once every 24 hours. The control system calculates the total BET area of ​​the seed crystals and the flow rate of the primary vulcanizing agent based on the most recent effective Mseed and BET specific surface area. The flow rate of the primary vulcanizing agent is recalculated when the change in BET specific surface area relative to the previous effective measurement value exceeds 20%.

[0068] Distinguishing between dissolved state and total amount:

[0069] Unfiltered water samples were acidified and digested before being used to determine total copper, total zinc, total iron, and total aluminum. Dissolved metal samples were filtered through a 0.45 μm filter under nitrogen protection before determination. Sulfide samples were filtered through a 0.45 μm anaerobic filter and immediately fixed before determination to avoid confusing suspended metal sulfides with dissolved sulfides as the same indicator.

[0070] Seed crystal terminology:

[0071] The copper sulfide seed crystals referred to in this invention are seed crystals with copper sulfide as the main crystalline sulfide and recycled in the copper section; the zinc sulfide seed crystals refer to seed crystals with zinc sulfide as the main crystalline sulfide and recycled in the zinc section. The same-phase seed crystals in the accompanying drawings and some embodiments refer to the above-mentioned seed crystals that have the same main metal sulfide composition as the target precipitate in the corresponding treatment section.

[0072] Dwell time distribution parameters:

[0073] The residence time distribution of the primary sulfurizing agent from its entry into the seed enrichment zone through the radial nozzle to its confluence with the target metal-containing aqueous phase was determined using non-reactive conductivity pulse tracing. During tracing, an oxygen-free LiCl solution was pulsed into the primary sulfurizing agent branch, with the pulse volume not exceeding 0.5% of the effective liquid holdup in the seed enrichment zone. The target metal-containing aqueous phase was replaced by a metal-free simulated solution with matching ionic strength. Seed circulation volume, total flow rate, pressure, and temperature were maintained at actual operating values. Conductivity responses were collected downstream of the confluence point at a frequency of at least 1 kHz, and normalized by the area under the response curve after baseline subtraction. t50 represents the time when the cumulative response reaches 50%, and P10 and P90 represent the times when the cumulative response reaches 10% and 90%, respectively. Each operating condition was independently traced three times, and the average value was taken when the relative standard deviations of t50, P10, and P90 all did not exceed 10%. The t50 of the primary sulfurizing agent in the seed enrichment zone was controlled at 4-10 ms, P10 at least 3 ms, and P90 at least 12 ms.

[0074] Micromixer parameters:

[0075] The three-flow coaxial micromixer has 10-14 radial nozzles with a single nozzle diameter of 0.18-0.22 mm. The effective axial distance between the radial nozzles and the junction of the target metal aqueous phase and the seed slurry is 9-15 mm. The mixing throat inner diameter is 17.5-18.5 mm, the effective reaction length is 190-215 mm, and the effective liquid volume is 48-55 mL. The inlet and outlet pressure difference is determined according to ΔP=Em·ρslurry and is 40-135 kPa. The mixer is maintained at a full liquid state with a gauge pressure of not less than 0.15 MPa. The minimum free flow channel size of the seed slurry channel is not less than 50 times the seed slurry D90.

[0076] The velocity gradient G in the low-shear growth region and the flocculation region is checked according to the following formula:

[0077]

[0078] In the formula, G is the velocity gradient, with units of seconds (s). -1 P represents the measured power input to the slurry in the axial direction of the agitator, in W; μ represents the apparent dynamic viscosity of the slurry under the corresponding temperature and shear conditions, in Pa·s; V represents the effective mixing volume, in m³; NP represents the impeller power number; ρ represents the slurry density, in kg / m³; N represents the rotational speed, in s. -1 D represents the propeller diameter in meters. Power is calculated using measured values ​​of P obtained from a power analyzer; the power formula is used for equipment selection and cross-verification.

[0079] Flocculation, clarification, and classification parameters:

[0080] The PAM working solution concentration is 0.040-0.060 wt%, the copper fraction dosage is 0.20-0.35 mg / L, and the zinc fraction dosage is 0.25-0.40 mg / L; PAM is first applied at a rate gradient of 150-220 s. -1 Mix for 6-10 seconds, then mix at the velocity gradient for 30-40 seconds. -1 20-28s -1 and 12-18s -1 Three-stage flocculation is carried out. The surface loading of the clarifier is 0.95-1.30 m³ / (m²·h), the diameter of the hydrocyclone is 20-30 mm, the inlet pressure is 0.16-0.24 MPa, and the grading particle size is 25-40 μm. The seed crystals obtained from grading are returned to the corresponding reactor, and the product is continuously discharged according to the cascade control of the reactor solid content and the dry solids flow rate of the product.

[0081] Particle size, zeta potential, and slurry property measurement aperture:

[0082] D10, D50, and D90 represent the equivalent particle size at cumulative volume distributions of 10%, 50%, and 90%, respectively. Particle size samples were analyzed using the clarified filtrate from the corresponding treatment stage as the dispersion medium. Wet laser particle size analysis was performed without sonication or the addition of chemical dispersants, and the injection cycle shear conditions were kept consistent across groups. Each sample was measured five times consecutively, and the technical repeatability average was calculated first, then used as the particle size result for a single independent run. The zeta potential was measured using the same dispersion medium at 25.0 ± 0.5℃ without additional pH adjustment, and pH, conductivity, viscosity, and temperature were recorded simultaneously. The density of the mixed slurry was measured using a calibrated vibratory densitometer, and the apparent dynamic viscosity was measured using a rotational viscometer at a shear rate close to the corresponding G value. The chord length counts less than 10 μm obtained from focused beam reflection measurements were only used for online fine particle trend assessment and did not directly replace the particle size volume fraction given by the wet laser particle size analyzer.

[0083] Measurement aperture for sedimentation and filtration performance:

[0084] The interfacial settling velocity was measured using the slurry exiting the final stage flocculant in the corresponding treatment section. The sample was not diluted and was placed in a transparent settling column with an inner diameter of 50±2mm and an effective height of 500±10mm at 25.0±0.5℃. The linear segment of the displacement of the solid-liquid interface from 50mm to 200mm from the initial liquid surface was recorded as a function of time, and the slope of this linear segment was used as the interfacial settling velocity. The specific resistance of the filter cake was determined using the underflow from the same batch of clarifiers. Constant pressure filtration was performed at 25.0±0.5℃, a filtration pressure differential of 0.100±0.005MPa, an effective filtration area of ​​50.0±0.5cm², and using the same batch of polypropylene filter cloth with a nominal pore size of 10μm. The filtrate volume V and time t were recorded. The slope b obtained from the linear regression of t / V on V was used to calculate the specific resistance of the filter cake according to α=2A²ΔP·b / (μc), where A is the effective filtration area, ΔP is the filtration pressure differential, μ is the dynamic viscosity of the filtrate, and c is the dry solids mass per unit volume of filtrate. Each group used the same batch of filter cloth and recorded the initial slurry solids content, filtrate temperature, and regression correlation coefficient. The regression correlation coefficient was not less than 0.995.

[0085] II. Example 1: Continuous staged sedimentation treatment of high-sulfate copper-zinc mine water

[0086] This embodiment employs a continuous pilot-scale skid-mounted system with a processing capacity of 1,000 m³ / h, comprising, in sequence, a raw water buffer and filtration unit 110, a vacuum deoxygenation and copper segment pH adjustment unit 120, a copper sulfide homogeneous seed micro-mixing precipitation unit 200, a copper segment low-shear growth and secondary pS* compensation unit 230, a copper segment flocculation clarification and cyclone classification unit 250, a zinc segment pH adjustment unit 300, a zinc sulfide homogeneous seed micro-mixing precipitation and growth unit 400, a zinc segment flocculation clarification and cyclone classification unit 450, a two-stage tail gas scrubbing and hydrogen sulfide interlock unit 500, and an emergency tank. The raw water, reagents, and baseline operating conditions for this embodiment are shown in Table 1.

[0087]

[0088] Before use, the effective sulfur content, density, free NaOH, Na2S, and total titratable alkalinity of the NaHS working solution should be determined; the actual equivalent concentration of the NaOH working solution should be determined. PAM uses low-charge cationic polyacrylamide with a cationic unit molar fraction of 6%-10% and a weight-average molecular weight of 6.0 × 10⁻⁶. 6 -9.0×10 6 g / mol, the hardness of the water used for preparing the solution is not higher than 100 mg / L, calculated as CaCO3; after wetting and dispersing the working solution for 15 min, it should be matured under low shear for 60 min and used within 8 h.

[0089] Pre-driving preparation

[0090] The pH electrode was calibrated at two points using pH 4.000 and pH 7.000 buffer solutions, and the two pS* electrodes were calibrated at four points using the method described above.

[0091] Close all reagent valves and purge the gas phase space of the copper section reactor, zinc section reactor, and clarifier with nitrogen at a rate of 3.00 Nm³ / h for 20 minutes. Then reduce the nitrogen flow rate to 0.20 Nm³ / h to maintain inert purging. Start the exhaust gas fan to maintain the gas phase gauge pressure at -120 Pa. The exhaust gas first enters a primary alkali absorption tower with a pH of 10.5-11.5, and then enters a secondary oxidation absorption tower with silver / silver chloride as a reference and a redox potential of +350 mV to +550 mV.

[0092] Add 250.0 L of deoxygenated water to the copper section reactor. While the seed crystal circulation pump is running at 300.0 L / h, add 16.50 kg of copper sulfide seed crystals (dry basis) within 15 min. Add deoxygenated water to bring the effective volume to 300.0 L, then increase the circulation rate to 850.0 L / h and circulate for 30 min. The copper sulfide content in the seed crystals should be no less than 90 wt%, the seed crystal D50 is 38.0 μm, the BET specific surface area is 5.50 m² / g, and the solid content in the reactor is 55.0 g / L. Add 25.685 kg of zinc sulfide seed crystals (dry basis) to the zinc section reactor in the same manner, bringing the liquid volume to 467.0 L. The zinc sulfide is predominantly cubic sphalerite phase, with a D50 of 28.0 μm, a BET specific surface area of ​​4.20 m² / g, and a solid content in the reactor of 55.0 g / L.

[0093] raw water pretreatment

[0094] Raw water enters a buffer tank through a 50μm bag filter and is heated to 25.0±0.3℃. It then flows at a rate of 1000.0 L / h through a PVDF hollow fiber vacuum membrane contactor, maintaining the absolute pressure on the membrane gas side at 20.0 kPa to reduce the outlet dissolved oxygen concentration to 0.20±0.05 mg / L. A 5.00 wt% NaOH or H₂SO₄ solution is used for fine-tuning to achieve an inlet pH of 3.000±0.020 for the copper section.

[0095] Selective precipitation, growth and separation of copper sulfides

[0096] Start the copper sulfide seed crystal circulation pump and stabilize the circulation rate at 850.0 L / h. Raw water initially enters the micro-mixer at 200.0 L / h and runs for 5 minutes, then sequentially increases to 400.0, 600.0, 800.0, and 1000.0 L / h, maintaining each stage for 4 minutes. Once the raw water flow rate reaches 600.0 L / h and the tank level, inlet pH, and circulation rate stabilize, the first-stage NaHS is started proportionally to the influent copper molar load. The copper section micro-mixer uses... Figure 3The three-channel coaxial structure shown has a central inlet 221 through which copper- and zinc-containing raw water is introduced, an annular seed slurry channel 222 through which copper sulfide seed slurry is introduced, and 20.00 wt% NaHS working solution enters the annular seed slurry channel through twelve radial nozzles 223 with a diameter of 0.20 mm. The effective axial distance between the radial nozzles and the junction of the copper- and zinc-containing raw water and seed slurry is 12.0 mm, the mixing throat 224 has an inner diameter of 18.0 mm, an effective reaction length of 202 mm, and an effective liquid volume of 51.4 mL. Conductivity pulse tracing is used to achieve a t50 of 6.0 ms, a P10 of 4.2 ms, and a P90 of 7.9 ms for NaHS in the seed enrichment region.

[0097] Under baseline operating conditions, the copper feed molar load was 4.721 mol / h, the total S / Cu molar ratio was 1.002, and the total NaHS flow rate was 19.050 mL / min; the primary NaHS flow rate was 16.478 mL / min, accounting for 86.5% of the total, and the secondary baseline flow rate was 2.572 mL / min. The total BET area of ​​the copper seed crystal was 90750 m², and the primary sulfur load was 45.1 μmol / (m²·h). The total flow rate of raw water, seed slurry, and NaHS was 1.851 m³ / h, and the average linear velocity of the mixing throat was 2.02 m / s. Based on the measured slurry density and according to ΔP=Em·ρslurry, the inlet and outlet pressure difference was adjusted to 76-85 kPa, the full liquid gauge pressure was not lower than 0.15 MPa, the corresponding unit mass energy dose was 74-80 J / kg, and the high shear average residence time was 0.100 s.

[0098] The mixed slurry entered a long, low-shear copper section tank with an effective volume of 300.0 L. An axial-flow hydrofoil with a diameter of 350.0 mm and a power rating of 0.30 was used inside the tank, operating at 45.0 r / min. The axial slurry input power was measured using a power analyzer, and the measured slurry density, apparent dynamic viscosity, and effective volume were substituted into the velocity gradient formula to back-calculate and stabilize the velocity gradient G at 47.0 s⁻¹. -1 The first 250.0L is the primary long zone, with a nominal residence time of 15.0 min calculated based on the external influent flow rate. The following 50.0L is the compensation zone, with a nominal residence time of 3.0 min. The acid production load from copper sulfide precipitation is controlled by a combination of NaOH feedforward and pH feedback, with a NaOH baseline feedforward rate of 28.4 mL / min equivalent to 10.00 wt%. After online dilution to approximately 2 wt%, the NaOH is added via a porous annular distributor at least 5 times the pipe diameter downstream of the micro-mixer and separated from the NaHS dosing point.

[0099] The compensation zone is equipped with a secondary NaHS dosing point, with a pS* setpoint of 25.00 and a control dead zone of 24.85-25.15. The controller takes the median of the effective process values ​​over the most recent 60 seconds and performs flow adjustment at most once every 60 seconds. When pS* is higher than 25.15, the secondary flow rate is increased in steps not exceeding 0.050 mL / min; when pS* is lower than 24.85, the secondary flow rate is decreased by the same step size. The upper limit of the secondary flow rate is 4.000 mL / min.

[0100] The initial PAM dosage for the copper segment was 0.250 mg / L, and the reference flow rate for the 0.050 wt% working solution was 8.333 mL / min. PAM was first added at G=150-220 s. -1 Mix for 6-10 seconds, then proceed to the three-stage flocculation chamber: first chamber G=35s -1 Stay for 3.0 minutes, second frame G=24s -1 Stay for 3.5 minutes, third grid G=15s -1 Stay for 3.5 minutes.

[0101] The flocculated slurry enters a clarifier with a projected area of ​​0.85 m² and a surface loading of 1.18 m³ / (m²·h). The underflow from the clarifier enters a 25 mm diameter hydrocyclone with an inlet pressure of 0.200 MPa and a cut particle size of 32.0 μm. The copper sulfide seed crystals obtained from the classification are returned to the copper section reactor. The dry basis copper sulfide production rate, calculated based on the baseline influent copper load, is 0.451 kg / h. Product discharge is controlled by cascade control of reactor solids content and product dry solids flow rate, with an allowable deviation of no more than ±8%.

[0102] Zinc sulfide selective precipitation, growth, and separation:

[0103] The clarified copper fraction solution enters a pH adjustment tank with an effective volume of 83.3 L, with a nominal residence time of 5.0 min calculated based on the external influent flow rate. A 10.00 wt% NaOH pre-neutralization design reference flow rate of 51.10 mL / min is used to adjust the aqueous phase pH from 3.000 to 6.000; this design flow rate corresponds to a titratable alkalinity of 8.50 mmol / L. During start-up, the measured Atitr value obtained using the aforementioned method is used to replace the design value. A zinc sulfide precipitation acidification compensation branch is also set up, with a reference flow rate of 55.17 mL / min, and a total feedforward reference flow rate of 106.27 mL / min. The actual flow rates are corrected based on the titratable alkalinity, the influent zinc molar load, the titratable alkalinity of the NaHS working solution, and the pH feedback.

[0104] After establishing the zinc sulfide seed crystal circulation, the zinc segment seed crystal circulation rate was stabilized at 850.0 L / h. Primary NaHS was added at 32.292 mL / min, and secondary NaHS was added at 5.040 mL / min with pS* compensation. The total S / Zn molar ratio was 1.010, and the primary addition ratio was 86.5%. The total BET area of ​​the zinc segment seed crystals was 107877 m², and the primary sulfur loading was 74.3 μmol / (m²·h). The primary NaHS first contacted the zinc sulfide seed crystals for 6.0 ms via a three-stream coaxial micromixer, with a unit mass energy dose of 74-80 J / kg and a high-shear average residence time of 0.100 s; subsequently, it entered the velocity gradient for 40.0 s. -1 A low-shear growth zone with a nominal residence time of 28.0 min calculated based on the external influent flow rate is maintained, keeping pS* at 18.00 and pH at 6.000.

[0105] The initial PAM dosage for the zinc segment was 0.300 mg / L, and the baseline flow rate of the 0.050 wt% working solution was 10.000 mL / min. The same rapid distribution mixing and three-stage decreasing velocity gradient flocculation methods as those used in the copper segment were employed. After clarification and cyclone classification, the zinc sulfide seed crystals obtained from the classification were returned to the zinc segment reactor. The dry basis zinc sulfide production, calculated based on the baseline influent zinc load, was 0.894 kg / h, and the permissible deviation of the product discharge did not exceed ±8%.

[0106] Solid steady state, sampling and safety interlocks:

[0107] The single solid age for the copper segment is 36.6 h, and for the zinc segment, it is 28.7 h. In this embodiment, the solid steady-state confirmation operation time is set to be no less than 200 h, with the copper segment operating for no less than 183 h and the zinc segment operating for no less than 144 h. When three consecutive samples obtained at 8-h intervals simultaneously meet the following conditions: reactor solid content variation not exceeding ±5%, D50 relative range not exceeding 10%, deviation between product dry solids flow rate and the amount generated calculated based on the target metal load of the influent not exceeding ±8%, and solid-liquid two-phase metal material balance closure rate of 95%-105%, the corresponding treatment segment is considered to have reached solid steady state. During operation, flow rate, pH, pS*, pressure difference, power, exhaust gas hydrogen sulfide concentration, and product discharge rate are recorded at a frequency of no less than 1 Hz. Focused beam reflection measurement is used to monitor the chord length count of particles smaller than 10 μm. When the fine particle count increases by more than 50% within 30 minutes and the solid content of the sludge in the product decreases simultaneously, the fine particle generation trend is determined to be abnormal. The feedforward amount of primary NaHS is reduced and the effluent is switched to the emergency pool. The PAM dosage is not used as a compensation variable for this abnormality.

[0108] A 0-2 vol% hydrogen sulfide analyzer is installed on the reactor gas phase or tail gas main, and the standard volumetric flow rate is recorded simultaneously. A 0-100 ppm detector is installed in the local enclosure space of the equipment, and a 0-20 ppm detector is installed in the personnel breathing area. The first-level alarm value between equipment is 5 ppm, and the interlock value is 10 ppm. When hydrogen sulfide reaches the interlock value, the equipment gas phase negative pressure is lost for more than 30 seconds, the induced draft fan or washing circulation pump stops operating, the seed crystal circulation rate is lower than 70% of the set value, the deviation of the dual pS* probes exceeds 1.0 pS* unit, the pressure difference between the inlet and outlet of the micro-mixer increases by more than 50% relative to the stable operating value, or stable cavitation occurs, all NaHS valves should be immediately closed and the material switched to the emergency pool. The above-mentioned tail gas hydrogen sulfide concentration, equipment gas phase negative pressure, and the operating status of the induced draft fan and washing circulation pump constitute the... Figure 4 The safety interlock input signal 609 in the system consists of the NaHS metering pump, product valve, reflux valve, and bypass valve. Figure 4 The controlled actuator 611 in the middle.

[0109] III. Examples 2 and 3: Operational Combinations within the Parameter Range

[0110] Example 2 uses a low-load combination, and Example 3 uses a high-load combination. Both combinations maintain... Figures 1 to 4 The equipment structure, pS* calibration method, two-stage tail gas scrubbing, decreasing velocity gradient flocculation, and solid inventory control logic remain unchanged. The ratio of seed crystal circulation volume to corresponding influent flow rate in the copper and zinc sections is set to 0.85. The NaHS flow rate is calculated based on the measured effective sulfur concentration, target metal molar load in the influent, and the selected primary sulfurizing agent ratio. The calculation results are shown in Table 2.

[0111]

[0112] Example 2 uses a higher total seed BET area, a lower proportion of primary sulfiding agent, and a lower energy dosage; Example 3 uses a lower total seed BET area, a higher proportion of primary sulfiding agent, and a higher energy dosage. In Table 2, the nominal residence time for low shear is calculated as the ratio of effective volume to external influent flow rate; the average residence time for high shear is calculated as the ratio of the effective liquid volume of the micro-mixer to the total volumetric flow rate of influent, seed circulating slurry, and reagents. Both combinations maintain the principle of primary sulfiding agent contacting the corresponding metal sulfide seed crystal first, secondary pS* compensation, and seed stock closed-loop. The parameters in the table are used in groups according to mutual constraints.

[0113] IV. Testing Items, Calculation Verification and Quality Control

[0114] The testing items, operating methods, and methodological basis are shown in Table 3.

[0115]

[0116] The chemical stoichiometry, product dry solids flow rate, solids age, and micro-mixer hydraulic parameters of Example 1 are verified and calculated as shown in Table 4. The values ​​in the table are obtained based on the given influent composition, effective reagent concentration, equipment size, and calculation relationships of Example 1; the effluent concentration, product purity, particle size, settling velocity, and filter cake specific resistance are measured and recorded according to the aforementioned detection methods and are not replaced by calculated values.

[0117]

[0118] The analytical quality control requirements are as follows: ICP-MS uses internal standard calibration, and dilution, matrix matching calibration, or spike verification are performed for high sulfate matrices; the spike recovery rate is controlled at 90%-110%, and when the sample concentration is greater than 10 times the limit of quantitation, the relative deviation of parallel samples should not exceed 10%; the solid-liquid two-phase metal material balance closure rate is controlled at 95%-105%; X-ray diffraction quantification is performed at least 3 times with independent sample loading; each particle size sample is continuously measured 5 times, and the relative standard deviation of D50 does not exceed 5%; the clock deviation of key measuring points does not exceed 1 second. When the detection result is lower than the limit of quantitation of the method used, it should be reported as "less than the limit of quantitation," and the quantitative value below the limit of quantitation should not be recorded; if a lower limit of quantitation is required, method validation should be completed separately, and the limit of detection, limit of quantitation, recovery rate, and uncertainty should be recorded.

[0119] The solid-liquid metal material balance takes the inflow of raw water into the copper section as the system inlet and the copper section products, zinc section products, and the final effluent from the zinc section as the system outlet, and also includes the changes in the solid inventory of the copper and zinc sections at the start and end of the evaluation window.

[0120] For any metal M, the closure ratio ηMB,M=( Copper products + Zinc products + , Outflow + ΔMM, Inventory / Δt) / The influent concentration is 100%; the solid-liquid metal balance closure rate in the table is the lower of the calculated values ​​for Cu and Zn. All flow rates, concentrations, and solid contents are time-aligned using the same clock reference, and the continuous flow rate within the evaluation window is taken as the time-weighted average.

[0121] The statistical analysis uses independent operation as the experimental unit. Parallel instrument measurements within each independent operation constitute technical repetition; the mean of the technical repetition for that operation is calculated first and not included in the independent sample size. For continuous process quantities, a time-weighted representative value is first formed according to the specified evaluation window. In the table, n=3, the sample standard deviation is calculated with n-1 degrees of freedom, and the two-sided 95% confidence interval is calculated using... Calculate t0.975,2 = 4.303. The mean and standard deviation are rounded after calculation, and the confidence intervals are calculated from the unrounded data.

[0122] Process evaluation indicators include total unfiltered copper in the clarified effluent of the copper section, dissolved copper after anaerobic filtration in the copper section, total unfiltered zinc in the final effluent of the zinc section, the proportion of zinc entering the copper product, the standard deviation of pS* in the copper and zinc sections, effective utilization rate of NaHS, space productivity of effective metal recovery, sulfides in the final effluent of the zinc section after anaerobic filtration, H2S mass load of the combined tail gas from the two treatment sections at the inlet of the scrubbing tower, suspended solids in the clarified effluent, total PAM consumption, unit power consumption, and time of initial separation failure or bypass.

[0123] The zinc ratio entering the copper product is calculated as the ratio of the dry-basis mass flow rate of zinc in the copper product to the mass flow rate of zinc in the influent; the effective utilization rate of NaHS is calculated as the ratio of the sum of the molar flow rates of copper and zinc consumed in the actual formation of CuS and ZnS to the total molar flow rate of effective sulfur input; the space-time yield of effective metal recovery is calculated by dividing the sum of the actual recovered copper and zinc mass flow rates in the copper and zinc products by the total effective reaction volume of the copper and zinc segments; the target metal index of the product is expressed as the mass fraction of the target metal relative to the sum of the measured masses of the four metals Cu, Zn, Fe, and Al, and is not expressed as the purity of the target metal relative to the total dry solids of the product.

[0124] The total PAM consumption is the sum of the dosage of copper and zinc segments converted to a unit volume of raw water. The unit power consumption is calculated by dividing the net power consumption of the micro-mixer feed pump, seed circulation pump, agitator of the growth tank and flocculation tank, hydrocyclone feed pump, exhaust gas fan and washing circulation pump by the water volume treated in the same period, excluding the power consumption of external raw water lifting and experimental analysis instruments.

[0125] pS* standard deviation is first calculated by taking the effective median sequence formed every 1 minute within the evaluation window of each independent run, and then the time standard deviations obtained from the three independent runs are summarized.

[0126] The initial separation failure or bypass time is defined as the moment when the system reaches and remains stable at the set flow rate, pH, seed circulation rate, and reagent feedforward rate for 30 consecutive minutes. The endpoint is defined as any of the following events: suspended solids in the clarified effluent from any treatment section are greater than 20 mg / L for two consecutive 30-minute mixed samples; the clarified interface is continuously above 0.20 m below the effluent weir for 30 minutes; or the emergency pool switching or safety interlock is triggered. The observation limit is 260 hours. During operation where the endpoint event has not occurred, records are deleted to the right, and the observation limit is not directly used to replace the failure time.

[0127] Product and solid-liquid separation performance evaluation indicators include product D50, volume fraction of particles smaller than 5μm, floc interface settling velocity, suspended solids in clarified effluent, filter cake specific resistance, target metal as a percentage of the mass fraction of the four measured metals, crystal phase composition, BET specific surface area, and zeta potential. Groups meeting the solid-state steady-state criterion use solid-state steady-state samples; groups that experienced an endpoint event before reaching 5 solid-state ages use the last complete 8-hour evaluation window without bypass before the endpoint event, and it is clearly stated that this group has not reached solid-state steady-state.

[0128] V. Verification Plan and Data Recording Requirements

[0129] To verify the effects of total BET area of ​​seed crystals, seed surface reaction state, contact sequence, transient high shear and primary sulfur load on fractional precipitation and solid-liquid separation, experiments were conducted according to the control scheme shown in Table 5.

[0130]

[0131] In Comparative Example 2, the surface reaction state of the seed crystals was confirmed using a 60s sulfide adsorption test: In an oxygen-free medium with pH, ​​temperature, and ionic strength matching the corresponding treatment section, seed crystals were added with the same total BET area and the same initial amount of sulfide. After 60s, the remaining sulfide in the 0.45μm oxygen-free filtrate was measured, and the surface reactivity was expressed as the reduction in sulfide per unit BET area. This indicator for Comparative Example 2 was 5% lower than that for Example 1. Comparative Example 5 used low-BET inert ceramic microspheres, verified by blank testing, to supplement the total solids content. The BET specific surface area of ​​the microspheres was no higher than 0.05 m² / g, and the blank adsorption rates of Cu and Zn in the water sample of the corresponding treatment section were both less than 1%. The primary sulfur load was calculated based on the measured total BET area of ​​the mixed system. The above control materials were only used to control variables and were not used in the normal operation of Example 1.

[0132] Process and engineering performance record

[0133] Each group synchronously recorded the following: unfiltered total copper in the clarified effluent from the copper section; dissolved copper after anaerobic filtration in the copper section; unfiltered total zinc in the final effluent from the zinc section; the zinc ratio entering the copper product; the initial and calculated potentials of the dual pS* probes; the effective utilization rate of NaHS; the space-time yield of effective metal recovery; the sulfide content in the final effluent from the zinc section after anaerobic filtration; the H2S mass load at the scrubbing tower inlet; the total PAM consumption; the unit power consumption; and the time of initial separation failure or bypass. Flow rate, pH, pS*, pressure difference, power, tail gas H2S, and product discharge were continuously recorded at a frequency of not less than 1 Hz. Water and product samples were obtained at least once every 8 hours within the evaluation window, with no fewer than 3 time points in each evaluation window. To compare the PAM dosage required to achieve the same clarification target under different operating conditions, the initial dosages for the copper and zinc treatments were 0.250 mg / L and 0.300 mg / L, respectively. If the suspended solids in the clarified effluent of the corresponding treatment section were greater than 10 mg / L for two consecutive 30-minute mixed samples, the PAM dosage for that section was increased by 0.050 mg / L every 30 minutes until two consecutive samples did not exceed 10 mg / L, or further increases failed to reduce suspended solids by more than 10%. The upper limit of the total PAM dosage for the copper and zinc treatments was 1.50 mg / L. The total PAM consumption in the table is the time-weighted average of the sum of the actual dosages for the two sections within the evaluation window.

[0134] Product and solid-liquid separation performance records

[0135] For groups meeting the aforementioned solid-state steady-state criteria, the D10, D50, D90, and volume fraction of fine particles smaller than 5 μm for CuS and ZnS products were measured within the solid-state steady-state evaluation window. The floc interface settling velocity, suspended solids in the clarified effluent, filter cake specific resistance, target metal mass fraction of the four measured metals, crystal phase composition, XRD grain size, BET specific surface area, and zeta potential were recorded. For groups experiencing an endpoint event before reaching 5 solid-state ages, samples were taken using the same method within the last complete 8-hour non-bypass evaluation window before the first endpoint event. The sampling location, sample pretreatment, dispersion medium, temperature, and instrument parameters for each indicator remained consistent across groups.

[0136] Test execution and data integrity requirements

[0137] Each group used three independent run-throughs as statistical replicates. Between each independent run-through, the reactor, pipelines, and sampling system were emptied and cleaned; reagents were re-prepared; and seed stock was re-established. Segmented sampling within the same continuous operation was not considered an independent replicate. For Example 1 and the group that met the solid-state steady-state criterion before the endpoint event, the running time was no less than 5 solid-state ages and the total running time was no less than 200 hours. Solid-state steady-state product samples of the copper segment were collected after at least 183 hours of operation, and solid-state steady-state product samples of the zinc segment were collected after at least 144 hours of operation. Comparative Example 1 did not use seed stock, and the solid-state age was not calculated. Evaluation began 2 hours after the flow rate, pH, and reagent dosage stabilized. For the other comparative examples, if the endpoint event occurred before reaching 5 solid-state ages, the evaluation window was the last complete 8-hour window without bypass before the endpoint event.

[0138] Comparative Examples 2-5 should maintain comparability for non-investigated variables such as total solids content, particle size distribution, effective volume of micromixer, total pressure difference between inlet and outlet, and residence time distribution; for groups requiring matching RTD, the same conductivity pulse tracing method should be used to confirm t50, P10, and P90.

[0139] Total metal samples were analyzed using unfiltered acid digestion; dissolved metals were analyzed using 0.45μm oxygen-free filtration; sulfide indicators were analyzed using 0.45μm oxygen-free filtration and immediate fixation of dissolved acid volatile sulfides in the samples, and were not presented as unfiltered total sulfide. H2S process indicators were calculated using the mass load converted from the scrubbing tower inlet concentration and standard volumetric flow rate; ppm detection values ​​in the equipment's local enclosure space and personnel breathing zone were recorded as safety monitoring data and were not mixed with process tail gas main pipe data.

[0140] Save DCS trend data of at least 1Hz, dual pS* probe records, raw FBRM chord length spectrum, RTD curve, ICP calibration curve and raw report, raw XRD spectrum and refined files, raw SEM / EDS plots, raw particle size distribution, product slurry flow rate and solids content records.

[0141] For each indicator, a representative value is first obtained within each independent run using the aforementioned evaluation window. Then, the arithmetic mean and sample standard deviation are calculated using the results of three independent runs. Two-sided 95% confidence intervals are then calculated using... Calculations. The mean and standard deviation in the table are rounded after calculation; confidence intervals are calculated from the unrounded data. Parallel instrument measurements do not increase the value of n. The failure time is reported using the above method only when the endpoint event is observed in all three runs; if right censoring exists, the Kaplan-Meier method is used to report the median and its interval.

[0142] VI. Test Results

[0143] The values ​​in Tables 6 to 9 are presented in the form of three independent runs, using a uniform format of mean ± sample standard deviation / two-sided 95% confidence interval. For each independent run, the technical replicates were first averaged within the run; comparative runs that did not reach solid steady state used the last complete 8-hour uninterrupted evaluation window before the first endpoint event, and the results were not considered as solid steady-state data.

[0144]

[0145]

[0146]

[0147]

[0148] The solid-liquid metal material balance closure rate of Example 1 was 100.1 ± 1.0%, and a solid steady-state sample was obtained after at least 5 solid ages. The first endpoint event time of each comparative example was earlier than 144 hours (5 solid ages) for the zinc segment, therefore none of them were judged to be in a solid steady state; their product and solid-liquid separation indicators were derived from the evaluation window before the first endpoint event. The average material balance closure rate of Comparative Examples 1, 2, 4, and 5 was less than 95%, consistent with their fine particle penetration, product discharge mismatch, or bypass events.

[0149] Compared to Comparative Example 3, which only eliminated the transient high shear at the reaction site, in Example 1, the unfiltered total Cu in the copper segment decreased from 2.70 mg / L to 0.46 mg / L, and the final unfiltered total Zn decreased from 4.20 mg / L to 0.83 mg / L. The D50 of the CuS and ZnS products increased from 22.4 μm and 19.8 μm to 41.6 μm and 31.2 μm, respectively. The specific resistance of the filter cake in the copper and zinc segments increased from 17.0 / 21.0 × 10⁻⁶, respectively. 12 m / kg decreased to 4.2 / 5.0×10 12 m / kg. Compared to Comparative Example 4, which reversed the contact sequence, and Comparative Example 5, which increased the primary sulfur load, Example 1 simultaneously exhibited lower effluent metal, fine particle volume fraction, H2S mass load, and PAM consumption. These results, under the same statistical caliber, support the synergistic relationship between seed BET total area constraint, seed-before-aqueous phase contact sequence, transient high shear at the reaction site, and secondary pS* compensation.

[0150] The above embodiments are used to illustrate the technical solution of the present invention. For those skilled in the art, equivalent substitutions made to the seed source, reactor type, flocculant type, clarifier type, particle size classification equipment, or reagent delivery method without changing the seed BET total area load constraint, the primary sulfiding agent first contacting the corresponding metal sulfide seed crystal before contacting the aqueous phase containing the target metal, transient high shear to low shear growth, secondary pS* compensation, and seed inventory closed loop are equivalent embodiments of the technical concept of the present invention; the scope of protection of the present invention is defined by the claims.

Claims

1. A method for the graded precipitation and flocculation sedimentation separation of heavy metals in mine water, used to treat mine water containing copper and zinc ions, characterized in that, include: S1 filters and deoxygenates the mine water, reducing the dissolved oxygen concentration to no more than 0.30 mg / L, and adjusts the pH of the copper section inlet to 2.95-3.05; S2. A copper sulfide seed slurry circulation system is established within the copper segment reactor. The total sulfiding agent in the copper segment is divided into a primary sulfiding agent (82%-90%) and a secondary sulfiding agent (the remainder). The primary sulfiding agent flow rate is determined based on the most recently measured seed dry mass and BET specific surface area, ensuring the primary sulfiding agent load, normalized to the total BET surface area of ​​the seed crystals, is 30-80 μmol / (m²·h). The primary sulfiding agent first enters the copper sulfide seed enrichment zone. After the median residence time (t50) in the seed enrichment zone is confirmed to be 4-10 ms by conductivity pulse tracing, it is then mixed with mine water containing the target metal aqueous phase. A high-shear treatment of 0.06-0.15 s is applied at a unit mass energy dose of 40-120 J / kg, followed by a velocity gradient of 35-60 s. -1 The low-shear growth region is established, and the secondary sulfiding agent is compensated according to the operable apparent sulfide activity index pS* of the copper segment, so that the pS* of the copper segment is 24.5-25.

5. S3, the copper segment slurry is subjected to rapid polyacrylamide mixing, decreasing rate gradient flocculation, clarification and particle size classification in sequence. The copper sulfide seed crystals obtained from the classification are returned to the copper segment reactor, and the copper sulfide product is continuously discharged by cascade control of reactor solid content and product dry solids flow rate. S4. Adjust the pH of the copper segment clarifying solution to 5.70-6.30, establish a zinc sulfide seed slurry circulation in the zinc segment reactor, and use the copper segment clarifying solution as the aqueous phase containing the target metal. Add the total sulfiding agent of the zinc segment according to the method described in step S2 to precipitate zinc sulfides, so that the primary sulfur loading of the zinc segment is 50-120 μmol / (m²·h) and the velocity gradient of the low shear growth region of the zinc segment is 30-55 s. -1 The pS* of the zinc segment is 17.7-18.4; S5. The zinc slurry is processed in the manner described in step S3, and zinc sulfide products are continuously discharged.

2. The method for separating heavy metals in mine water by graded precipitation and flocculation sedimentation according to claim 1, characterized in that: The pS* is an operational apparent sulfide activity index obtained by using two silver / silver sulfide electrodes in an oxygen-free medium with pH, ​​temperature, sulfate concentration, main cation composition, and ionic strength matched to the water sample at the corresponding treatment stage, calibrated using a fourth-level sulfide standard solution with offline values. The pS* value of the fourth-level sulfide standard solution is assigned according to... The values ​​are defined as follows: pS*k is the assigned pS* value of the k-th sulfide standard solution, k = 1, 2, 3, 4; CT,k is the measured total dissolved sulfide concentration of the k-th sulfide standard solution, in mol / L; Δj is the conventional constant for the treatment segment, 20.0 for the copper segment and 14.0 for the zinc segment; the effective slope of the electrode during calibration is 26-32 mV / decade, the 90% response time is no greater than 45 s, the difference in readings of the two electrodes in the same standard solution is no greater than 0.50 pS* units, and the zero drift is no greater than 3 mV over 8 hours.

3. The method for separating heavy metals in mine water by graded precipitation and flocculation sedimentation according to claim 2, characterized in that: In the copper-segment reactor, the solid content of copper sulfide seed crystals is 40-70 g / L, the seed crystal D50 is 30-50 μm, the BET specific surface area is 4.0-7.0 m² / g, and the mass fraction of copper sulfide in the seed crystals is not less than 90%; in the zinc-segment reactor, the solid content of zinc sulfide seed crystals is 40-70 g / L, the seed crystal D50 is 20-40 μm, and the BET specific surface area is 3.0-6.0 m² / g. The ratio of seed crystal circulation volume to corresponding influent flow rate for both copper and zinc segments is 0.75-0.

95.

4. The method for separating heavy metals in mine water by classification precipitation and flocculation sedimentation according to claim 3, characterized in that: The normalized primary sulfur load of the seed crystal BET total area is calculated according to... Calculate, where Aseed = 1000·Mseed·aBET, The effective sulfur molar flow rate of the primary vulcanizing agent is given by Mseed, the dry mass of the seed crystals in the reactor is given by aBET, and the BET specific surface area of ​​the seed crystals is given by aBET. The seed crystal samples were filtered under nitrogen protection, washed with deoxygenated water, and vacuum dried at 40°C to constant weight before nitrogen adsorption was measured. The measurement interval of the solid content in the reactor was no longer than 8 hours. The measurement interval of the BET specific surface area of ​​the copper and zinc sections was no longer than 24 hours. When the change of the BET specific surface area of ​​the corresponding treatment section relative to the previous measurement value exceeded 20%, the flow rate of the primary vulcanizing agent in that treatment section was recalculated.

5. The method for separating heavy metals in mine water by graded precipitation and flocculation sedimentation according to claim 4, characterized in that: The primary sulfiding agent is added through a three-stream coaxial micro-mixer. The micro-mixer includes a central inlet for introducing the aqueous phase containing the target metal, an annular seed slurry channel for introducing the seed slurry of the corresponding metal sulfide, and 10-14 radial nozzles disposed within the annular seed slurry channel. The diameter of a single radial nozzle is 0.18-0.22 mm, the effective axial distance between the radial nozzle and the intersection of the aqueous phase containing the target metal and the seed slurry is 9-15 mm, the inner diameter of the mixing throat is 17.5-18.5 mm, the effective reaction length is 190-215 mm, and the effective liquid volume is 48-55 mL. The pressure difference between the inlet and outlet of the micro-mixer is set to 40-135 kPa according to ΔP=Em·ρslurry. The micro-mixer is kept in a full liquid state with a gauge pressure of not less than 0.15 MPa, and the residence time distribution P10 is not less than 3 ms and P90 is not more than 12 ms.

6. The method for separating heavy metals in mine water by graded precipitation and flocculation sedimentation according to claim 1, characterized in that: The molar ratio of total sulfiding agent to copper in the copper segment was 0.995-1.015, and the nominal residence time in the low-shear growth zone of the copper segment was 16.5-20.0 min; the molar ratio of total sulfiding agent to zinc in the zinc segment was 1.000-1.025, and the nominal residence time in the low-shear growth zone of the zinc segment was 25.5-31.0 min; the acid production load of sulfide precipitation in the copper and zinc segments was controlled by sodium hydroxide feedforward and pH feedback, which were independent of the sulfiding agent addition point.

7. The method for separating heavy metals in mine water by classification precipitation and flocculation sedimentation according to claim 6, characterized in that: The polyacrylamide is a low-charge cationic polyacrylamide with a cationic unit molar fraction of 6%-10% and a weight-average molecular weight of 6.0 × 10⁻⁶. 6 -9.0×10 6 g / mol, to prepare a working solution of 0.040-0.060 wt%; The dosage of copper segment is 0.20-0.35 mg / L, and the dosage of zinc segment is 0.25-0.40 mg / L; polyacrylamide is applied at a rate gradient of 150-220 s. -1 Mix for 6-10 seconds, then mix at the velocity gradient for 30-40 seconds. -1 20-28s -1 and 12-18s -1 The next step is to carry out three-stage flocculation.

8. The method for separating heavy metals in mine water by graded precipitation and flocculation sedimentation according to claim 7, characterized in that: The surface loading of the clarifiers for both copper and zinc segments is 0.95-1.30 m³ / (m²·h). The underflow from the clarifier enters a hydrocyclone with a diameter of 20-30 mm. The inlet pressure of the hydrocyclone is 0.16-0.24 MPa, and the grading and cutting particle size is 25-40 μm. The deviation between the dry solids flow rate of the product and the amount generated based on the target metal load of the influent is controlled within ±8%.

9. The method for separating heavy metals in mine water by classification precipitation and flocculation sedimentation according to claim 8, characterized in that: Solid age according to The calculation is performed, where Mseed is the dry mass of the seed crystals in the reactor. For product dry solids flow rate; The solid steady-state confirmation operation time of the corresponding treatment section shall not be less than 5 solid ages. When three consecutive samples obtained at 8-hour intervals simultaneously meet the following conditions, the solid content change in the reactor shall not exceed ±5%, the relative range of seed crystal D50 shall not exceed 10%, and the solid-liquid two-phase metal material balance closure rate shall be 95%-105%, the treatment section shall be judged to have reached solid steady state.

10. The method for separating heavy metals in mine water by graded precipitation and flocculation sedimentation according to claim 9, characterized in that: At least one location in the reactor's gas phase space and the tail gas main is equipped with a hydrogen sulfide analyzer with a range of 0-2 vol%, a detector with a range of 0-100 ppm is installed in the local enclosure space of the equipment, and a detector with a range of 0-20 ppm is installed in the personnel breathing area. The tail gas is sequentially treated by primary alkaline absorption with a pH of 10.5-11.5 and secondary oxidation absorption with silver / silver chloride as reference and an oxidation-reduction potential of +350 mV to +550 mV. The sulfurizing agent metering pump, nitrogen sealing, tail gas induced draft fan, and two-stage washing circulation pump form a causal interlock. When any of the following occurs: hydrogen sulfide reaches the interlock value, equipment negative pressure is lost, seed crystal circulation is lower than 70% of the set value, the deviation of the dual pS* probe exceeds 1.0 pS* unit, the pressure difference between the inlet and outlet of the micro mixer increases by more than 50% relative to the stable operating value, or a stable cavitation occurs in the micro mixer, the sulfurizing agent valve is closed and the material is switched to the emergency pool.

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