Quality-divided treatment and recycling method for lead-zinc beneficiation wastewater

Abstract

The invention discloses a quality-divided treatment and recycling method for lead-zinc beneficiation wastewater, and belongs to the technical field of beneficiation wastewater treatment.The method comprises the steps that beneficiation tail water is introduced into a Fenton reaction tank, a catalyst is added firstly, then hydrogen peroxide is added, a Fenton oxidation reaction is conducted, after the Fenton oxidation reaction is finished, the beneficiation tail water is introduced into a coagulation reaction tank, caustic soda liquid is added, and the mixture is stirred and mixed uniformly; adding a precipitating agent, a flocculating agent and a stabilizing agent, and flocculating and settling the precipitate; introducing the beneficiation tail water added with the treatment agent into a honeycomb inclined tube sedimentation tank, further flocculating and settling, then returning flocculated precipitates in a bottom tank to a coagulation reaction tank, and discharging redundant bottom mud into a tailing pond; and settled clear water enters a clear water tank and is used as production water for ore grinding classification and flotation operation. According to the invention, through quality-divided treatment-quality-divided recycling of the beneficiation wastewater, it is ensured that the beneficiation tail water meets the requirements of ore grinding and flotation production indexes, the treatment cost of concentrate overflow water and filtered water is reduced, and the purpose of 100% recycling of the beneficiation wastewater after quality-divided treatment is achieved.

Description

Technical Field

[0001] This invention belongs to the technical field of mineral processing wastewater treatment, and particularly relates to a method for the differentiated treatment and recycling of lead-zinc mineral processing wastewater. Background Technology

[0002] my country possesses abundant and widely distributed lead-zinc mineral resources. However, most lead-zinc polymetallic ores are complex in nature, low in grade, and contain numerous associated elements, resulting in significant differences in beneficiation potential. Lead-zinc polymetallic ores are typically recovered using grinding and flotation methods, with water consumption reaching 4-6 tons of water per ton of ore during the beneficiation process. If magnetic separation or gravity separation processes are involved, the water consumption is even higher. This beneficiation wastewater contains large amounts of beneficiation reagents, heavy metal ions, and suspended solids. Its discharge poses significant hazards to human health and industrial and agricultural production, while direct reuse negatively impacts beneficiation technical indicators. In recent years, "carbon neutrality" and energy conservation and emission reduction have become development trends in the non-ferrous metals industry. Improving wastewater recycling rates and reducing total wastewater discharge are essential requirements for achieving clean production and sustainable healthy development for enterprises.

[0003] The pollutants in circulating wastewater that significantly affect the flotation process are mainly suspended solids, residual mineral processing reagents, and heavy metal ions. After cumulative circulation, the COD (Chemical Oxygen Demand) content exceeds 200 mg / L. When mineral processing wastewater is untreated or poorly treated, the pollutants in the wastewater will have a significant impact on the mineral processing flotation process. Pollutants in wastewater mainly affect the mineral separation process in the following ways: first, they affect the full dispersion of mineral particles; second, they change the hydrophilicity or electrical properties of the mineral particle surface; third, they react with mineral processing reagents, thereby consuming a large amount of reagents; and fourth, they change the pH of the pulp, thus altering the proportion of various forms of electrically charged or ionic reagents on the mineral surface in the pulp, thereby affecting the separation process.

[0004] Most lead-zinc polymetallic ore beneficiation plants mix their beneficiation wastewater together and typically use sulfuric acid to adjust the pH, followed by coagulation and sedimentation processes such as polyferric sulfate and PAM. After treatment, the degradation and removal of frothers and flotation reagents are poor, and recycling them has a significant impact on beneficiation indicators. The zinc content in lead concentrate increases significantly, while the grade and recovery rate of zinc concentrate decrease markedly, especially in winter when the wastewater treatment effect is more pronounced. To ensure the quality of production water, deep treatment is required, and the wastewater treatment cost can reach 4-5 yuan per ton of water, seriously affecting the economic benefits of enterprises.

[0005] Overcoming the problems of high treatment costs and poor treatment effects of mineral processing wastewater, which affect mineral processing indicators, and finding a new method with low cost and minimal impact on mineral processing indicators is an urgent technical problem to be solved in this field. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for the differentiated treatment and recycling of lead-zinc ore beneficiation wastewater to solve the problems mentioned in the background art or achieve better technical effects.

[0007] To solve the above-mentioned technical problems, the inventors, through practice and summarization, derived the technical solution of this invention. This invention discloses a method for the differentiated treatment and recycling of lead-zinc ore beneficiation wastewater, comprising:

[0008] S1: First, the tailings water from the mineral processing is introduced into the lead-zinc tailings pond for natural decomposition and sedimentation, removing some suspended solids and heavy metal ions, and settling some organic matter.

[0009] S2: The clarified tailings water from S1 sedimentation is introduced into the Fenton reactor. Sulfuric acid is added to adjust the pH to 3-4, then a catalyst is added, followed by hydrogen peroxide. The Fenton oxidation reaction is carried out for 40-60 minutes. The porous structure of the catalyst can adsorb pollutants in the water. The Fe loaded in the catalyst... 2+ It can react with H2O2 to generate hydroxyl radicals and Fe 3+ It degrades pollutants in water through free radical oxidation; the support in the catalyst can also promote Fe 3+ Reduced to Fe 2+ This maintains the Fenton reaction and improves degradation efficiency.

[0010] S3: The tailings water from S2 is introduced into the coagulation reaction tank, liquid alkali is added to adjust the pH to 8~8.5, then a precipitant is added to react with the heavy metal ions in the water to generate insoluble precipitates; flocculants and stabilizers are added to flocculate and settle the precipitates.

[0011] S4: After the treatment agents are added, the tailings water is introduced into the honeycomb inclined tube sedimentation tank after coagulation and stirring for further flocculation and sedimentation. Then, the flocculated sediment in the bottom tank is returned to the coagulation reaction tank in S3, and the excess bottom mud is discharged into the tailings pond. The settled clear water enters the clear water tank and is used as production water for grinding, classification and flotation operations.

[0012] Furthermore, in S2, the catalyst is a supported Fe. 2+ Activated carbon micro powder, Fe 2+ The load is 3~6 wt.%.

[0013] Furthermore, the activated carbon has a particle size of 100 mesh and a specific surface area exceeding 800 m². 2 / g.

[0014] Furthermore, in S2, the amount of catalyst used is 200~400g / t; the concentration of hydrogen peroxide is 27.5%, and the amount of hydrogen peroxide used is 100~300g / t.

[0015] Furthermore, the liquid alkali is a mixed solution of sodium hydroxide and sodium carbonate, wherein the sodium hydroxide content is 30.29% and the sodium carbonate content is 0.28%.

[0016] Furthermore, in step S3, the precipitant is sodium hydrosulfide, and the dosage is 30~60g / t.

[0017] Furthermore, in S3, the flocculant is polyacrylamide, and the dosage is 5~20g / t.

[0018] Furthermore, in S3, the stabilizer is selected from one or more of polyferric sulfate, polyaluminum sulfate, polyferric chloride, and ferrous ammonium sulfate.

[0019] Furthermore, in S3, the amount of stabilizer used is 150~300g / t.

[0020] Furthermore, in S4, the flocculated sediment from the bottom pool, after being returned to the coagulation reaction tank in S3, can serve as a seed crystal that matches the target crystal structure. In the process of treating heavy metal ions in wastewater, it can skip the difficult and slow homogeneous nucleation, increase the contact opportunities between ions and seed crystals, and promote the precipitation of heavy metal ions.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] (1) This invention treats mineral processing wastewater separately and reuses it separately. First, the mineral processing tailings are naturally decomposed in the tailings pond and then enter the wastewater treatment station. After treatment with reagents such as sulfuric acid, catalyst, hydrogen peroxide, liquid alkali, sodium hydrosulfide, PAM and stabilizers, it is reused for grinding, classification and flotation operations with strict water quality requirements. The concentrate overflow water has a complex composition and a lot of residual mineral processing reagents, so it does not directly enter the grinding and flotation operations, but is recycled for magnetic separation and sulfur removal operations with no water quality requirements. The water from the concentrate ceramic filter is clear and is collected and recycled for washing the ceramic filter. This ensures that the mineral processing tailings meet the production index requirements of grinding and flotation, reduces the treatment cost of concentrate overflow water and filter water, and achieves the goal of 100% recycling of mineral processing wastewater after separate treatment.

[0023] (2) This invention utilizes natural sedimentation of tailings ponds + advanced chemical oxidation to treat lead-zinc polymetallic beneficiation tailings. Under acidic conditions with a pH of around 3.5, a highly efficient catalyst is used to replace the traditional ferrous sulfate Fenton reagent. Through coordination with iron ions, a stable chelate is formed, which enhances the reaction activity and improves the selectivity and stability of the catalytic process. The hydroxyl radicals generated by the catalytic decomposition of hydrogen peroxide by iron ions efficiently degrade pollutants. Iron ions can also be used as a coagulant to precipitate and remove organic matter. The treated beneficiation tailings can be reused as production water for lead-zinc grinding and flotation operations, which greatly reduces the impact of wastewater recycling on the technical indicators of lead-zinc beneficiation.

[0024] (3) The present invention uses a stabilizer to improve the flocculation and sedimentation effect. After the stabilizer undergoes a hydrolysis reaction, it generates colloidal particles with a large specific surface area, which adsorb suspended particles, colloidal substances and some negatively charged pollutants in the wastewater. Through the charge neutralization and electrostatic attraction reaction, it promotes the collision and aggregation between colloidal particles, thereby forming larger particles and accelerating sedimentation. For example, thallium ions in wastewater often exist in +1, +2 and +3 valences, but +1 valence is the main one. When sodium hydrosulfide is added, thallium reacts with sulfur to form hydrated colloidal particles such as thallium disulfide, thallium sulfide and thallium trisulfide. These particles are extremely small and charged, and are suspended colloidal particles in water. General coagulants and flocculants cannot completely capture these colloidal particles, so the water quality is turbid and the flocculation and sedimentation effect is low. The stabilizer is a compound agent with opposite charges that can compress the electric double layer of colloidal particles, simultaneously performing adsorption bridging, sedimentation, and trapping. Through these three mechanisms, it effectively reduces the potential of the colloidal particles, causing them to destabilize and form small, linear flocs. After the addition of the flocculant, large flocs are formed, which then separate from the water through gravity sedimentation, thus efficiently separating thallium compound colloidal particles from the water. This invention, with the addition of the stabilizer, significantly improves the flocculation effect, resulting in clear and transparent effluent that meets discharge concentration requirements far below industry standards.

[0025] (4) The present invention returns the sediment from the sedimentation tank to the front end of the coagulation reaction tank. By utilizing the large specific surface area and pore structure of the sediment, the adsorption and sedimentation of suspended particles, heavy metal particles and organic pollutants are enhanced. Through chemical action, the chemical components contained in the sediment react with some pollutants to generate precipitates, thereby promoting the degradation and transformation of pollutants.

[0026] (5) Compared with the mixed treatment method of mineral processing wastewater, the present invention has a low wastewater treatment cost of only 1 to 1.5 yuan / ton of water, and has almost no impact on lead and zinc beneficiation indicators. Attached Figure Description

[0027] Figure 1 This is a flowchart of the wastewater treatment and recycling method for lead-zinc ore beneficiation in Embodiment 1 of the present invention. Detailed Implementation

[0028] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to specific examples.

[0029] Unless otherwise specified, the raw materials or reagents used in the following examples and comparative examples are commercially available products or products prepared using conventional techniques.

[0030] The present invention classifies mineral processing wastewater into three types: tailings water, concentrate overflow water, and concentrate filtration water; and provides a method for treating and recycling lead-zinc mineral processing wastewater, such as... Figure 1 As shown, it includes the following steps:

[0031] S1: The COD content of the tailings is 80~100mg / L. It enters the lead-zinc tailings pond through the tailings pipeline for natural decomposition and sedimentation, removing some suspended solids and heavy metal ions and decomposing some organic matter. After settling and clarifying in the tailings pond, the tailings enter the raw water pool of the wastewater treatment plant through the drainage overflow well, and the inflow is controlled by an electric valve.

[0032] S2: Introduce the tailings water to be treated into the Fenton reactor, add sulfuric acid (100~300g / t) sequentially, adjust the pH of the wastewater influent to 3~4, add catalyst (200~400g / t) first, followed by hydrogen peroxide (100~300g / t), and carry out advanced Fenton oxidation reaction for 40~60min; the strong oxidizing hydroxyl radicals generated by iron salt catalysis react with the recalcitrant organic matter in the aqueous solution to generate organic free radicals, destroying their structure, and finally oxidizing and decomposing them to remove the residual reagents from the wastewater.

[0033] The reaction formula for the generation of highly oxidizing hydroxyl radicals from hydrogen peroxide under the catalysis of a catalyst is as follows:

[0034] Fe 2+ +H₂O₂→Fe 3+ +OH - +·OH;

[0035] S3: The tailings water from the reaction tank is introduced into the coagulation reaction tank. First, liquid alkali (300~600g / t) is added to adjust the pH value of the wastewater to between 8 and 8.5. Then, sodium hydrosulfide (30~60g / t) is added to utilize the reaction of sulfur ions with heavy metals to generate insoluble precipitates, precipitating heavy metal ions such as lead, zinc, cadmium, copper, and arsenic in the wastewater. Then, polyacrylamide (PAM) (5~20g / t) is added for flocculation and sedimentation. At the same time, in order to improve the flocculation and sedimentation effect, a stabilizer (150~300g / t) is added to accelerate the flocculation and sedimentation speed.

[0036] The reaction formula for precipitating heavy metal ions by adding sodium hydrosulfide and utilizing sulfide ions is as follows:

[0037] X 2+ +HS - =XS↓+H + ;

[0038] Where X represents a heavy metal ion.

[0039] S4: After the treatment agents are added, the tailings water from the mineral processing plant is introduced into the honeycomb inclined tube sedimentation tank after coagulation and stirring for flocculation and sedimentation. After the flocs settle, the flocculated sediment in the bottom tank is returned to the coagulation reaction tank by the sludge pump 1. This bottom sludge can provide a "growth template" that matches the target crystal structure as seed crystals, skipping the difficult and slow homogeneous nucleation, and also increasing the contact opportunities between ions and seed crystals. Then, the ions will accumulate rapidly along the crystal lattice of the seed crystals, making the crystals grow faster and larger and increasing the density. Finally, these large crystals can settle efficiently, promoting water treatment sedimentation and separation. Excess bottom sludge is discharged into the tailings pond by the sludge pump 2. After sedimentation, the clear water enters the clear water tank. The clear water treated in the clear water tank is pumped to the production water tank for use as production water for grinding, classification and flotation operations.

[0040] In S4, mineral processing tailings are treated using a honeycomb inclined tube sedimentation tank with added treatment agents for flocculation and sedimentation. By installing honeycomb inclined tube packing in the sedimentation tank, the sedimentation area is increased, improving sedimentation efficiency. After the wastewater enters the sedimentation tank, the flow velocity is slowed down by the guidance of the honeycomb inclined tubes, and suspended solids settle to the bottom of the tank under gravity, thus achieving solid-liquid separation. The special structure of the honeycomb inclined tubes makes the water flow more stable, reduces the impact of turbulence on the sedimentation effect, and increases the settling velocity of sludge, thereby improving treatment efficiency.

[0041] In S2, the sulfuric acid concentration is 98%, the hydrogen peroxide concentration is 27.5%, and the main components of the catalyst are ferrous sulfate and activated carbon. The concentration of ferrous sulfate ferric salt in the prepared solution is 32%. This invention utilizes a highly efficient catalyst to replace the traditional ferrous sulfate Fenton reagent, forming a stable chelate with iron ions through coordination. The preparation steps of this catalyst are as follows:

[0042] (1) Raw material pretreatment:

[0043] Take 10-20g of activated carbon powder as a carrier, with a particle size of 100 mesh and a specific surface area ≥800m². 2 Soak 10g of FeSO4•7H2O (analytical grade) in 200mL of deionized water for 4 hours, rinse repeatedly 4 times, then place in an oven and dry at 110℃ for 5 hours to completely remove moisture. Cool to room temperature for later use. 2+ Hydrolysis produces Fe(OH)2 precipitate.

[0044] (2) Add the pretreated carrier to the above ferrous sulfate solution, place it in a constant temperature water bath shaker (or magnetic stirrer), and shake and stir at 200 r / min for 4 h at 30℃ to ensure Fe 2+ It is fully loaded or adsorbed onto the surface and micropores of the carrier.

[0045] (3) For the Fe load in step (2)2+ The mixture of carriers was filtered using a Buchner funnel (lined with filter paper) to separate the supported Fe. 2+ The carrier was then rinsed 2-3 times with a small amount of deionized water to remove unadsorbed free Fe from the carrier surface. 2+ The sample was placed in a vacuum drying oven and dried at 65-80℃ for 6-8 hours. After natural cooling, the loaded Fe was obtained. 2+ Activated carbon catalyst, Fe 2+ The load is 3~6 wt.%.

[0046] The core function of the catalyst used in this invention is to utilize its porous structure to adsorb Fe through mechanisms of "pore adsorption," "van der Waals forces," and "electrostatic attraction." 2+ Alternatively, FeSO4 molecules may be "captured" within the pores or on the surface of the activated carbon carrier, forming a composite carrier. This composite carrier adsorbs pollutants in the water, while its porous structure also disperses Fe from ferrous sulfate. 2+ Promote Fe 2+ The reaction with H2O2 generates ·OH (hydroxyl radicals), which efficiently oxidize and degrade pollutants; the carrier can also promote Fe 3+ Reduced to Fe 2+ This maintains the Fenton reaction and improves degradation efficiency.

[0047] In S3, the main components of the liquid alkali are sodium hydroxide and sodium carbonate, with sodium hydroxide content of 30.29% and sodium carbonate content of 0.28%.

[0048] Sodium hydrosulfide is a flaky solid. It can be used in place of sodium sulfide to prepare a 0.75% aqueous solution. By using it in combination with liquid alkali, the safety risk of hydrogen sulfide gas release can be reduced.

[0049] PAM (polyacrylamide) is a powdered solid high molecular weight cationic flocculant with an industrial salt content of <20%, formulated as a 0.125% water solution.

[0050] The stabilizer components are one or more of polyferric sulfate, polyaluminum sulfate, polyferric chloride, and ferrous ammonium sulfate. Their properties are to improve flocculation effect, accelerate sedimentation, and ensure that suspended solids in the water settle completely, resulting in clear water.

[0051] Example 1

[0052] A method for the differentiated treatment and recycling of lead-zinc ore beneficiation wastewater is disclosed, taking the wastewater from a lead-zinc ore beneficiation plant in Hunan Province as an example. This ore is a high-sulfur lead-zinc ore, and a lime-free slurry beneficiation process was adopted, achieving efficient separation of lead, zinc, and sulfur under natural pH conditions. Specifically, the lead, zinc, ammonia nitrogen, and COD contents in the beneficiation tailings water were 0.09 mg / L, 1.48 mg / L, 1.29 mg / L, and 96 mg / L, respectively; the lead, zinc, ammonia nitrogen, and COD contents in the concentrate overflow water were 0.136 mg / L, 2.71 mg / L, 1.57 mg / L, and 215 mg / L, respectively; and the lead, zinc, ammonia nitrogen, and COD contents in the concentrate filtrate water were 2.143 mg / L, 2.69 mg / L, 0.52 mg / L, and 127 mg / L, respectively.

[0053] The aforementioned mineral processing wastewater is treated using the lead-zinc mineral processing wastewater separation and recycling method of this invention, such as... Figure 1 As shown, the steps are as follows:

[0054] S1: The tailings water from the mineral processing plant enters the lead-zinc tailings dam through the tailings pipeline for natural classification and settling. After settling and clarifying in the tailings dam, the tailings water enters the raw water pool of the wastewater treatment plant through the overflow well.

[0055] S2: The ore dressing tailings from the raw water tank are introduced into the Fenton reactor. Sulfuric acid is added at a rate of 150 g / t to adjust the pH, maintaining it at 3.5-4. Then, catalyst is added at a rate of 200 g / t, followed by hydrogen peroxide at a rate of 300 g / t. An advanced Fenton oxidation reaction is carried out for 40-60 minutes. This catalytic process generates highly oxidizing hydroxyl radicals, which react with recalcitrant organic matter in the aqueous solution to form organic free radicals, causing structural damage. Ultimately, this oxidative decomposition removes pollutants such as residual ore dressing reagents from the wastewater. The reaction formulas involved in the generation of highly oxidizing hydroxyl radicals through iron salt catalysis after adding the catalyst and hydrogen peroxide are as follows:

[0056] Fe 2+ +H₂O₂→Fe 3+ +OH - +·OH;

[0057] S3: Introduce the wastewater from the Fenton reactor into the coagulation reactor. First, add liquid alkali at a dosage of 350g / t to adjust the pH of the wastewater to 8. Then, add sodium hydrosulfide at a dosage of 35g / t to utilize the reaction of sulfur ions with heavy metals to generate insoluble precipitates, precipitating heavy metal ions such as lead, zinc, cadmium, and copper in the wastewater. Finally, add PAM at a dosage of 10g / t and stabilizer at a dosage of 200g / t to accelerate the flocculation and sedimentation rate in the coagulation reactor.

[0058] S4: After the treatment agents are added, the wastewater is introduced into the honeycomb inclined tube sedimentation tank after coagulation and stirring for flocculation and sedimentation. After the flocs settle, the flocculated sediment in the bottom tank is returned to the coagulation reaction tank by the sludge pump 1. The excess bottom sludge is discharged into the tailings pond by the sludge pump 2. The settled clear water is introduced into the clear water tank. The treated clear water in the clear water tank is pumped to the production water tank for use as production water for grinding, classification and flotation operations.

[0059] This embodiment employs a technology of separate treatment and reuse of mineral processing wastewater. First, the tailings water is treated through a wastewater treatment process and reused in lead-zinc grinding and flotation production after meeting standards. Then, the filtrate from the concentrate filter is collected in a high-level water tank and reused for washing the ceramic filter. Next, the overflow water from the high-COD concentrate concentration is directly reused for water magnetic separation operations, while operations without water quality requirements, such as sulfur flotation, are recycled. Finally, the treated tailings water and underground clean water are reused for grinding, classification, and flotation operations at the Huangshaping lead-zinc mine in Hunan Province to verify their impact on mineral processing indicators.

[0060] (1) Grinding: The raw ore is ground to a fineness of -74μm with a content of 70%;

[0061] (2) Lead selection: The process conditions for rough selection 1 are as follows: add 500g / t of zinc sulfur inhibitor D82, stir for 3-4 minutes, then add 160g / t of lead collector 25# sodium black powder and 20g / t of auxiliary collector diesel oil, and stir for 2-3 minutes; the process conditions for rough selection 1 are as follows: add 20g / t of lead collector 25# sodium black powder and stir for 2-3 minutes; the process conditions for scavenging 1 are as follows: add 10g / t of lead collector 25# sodium black powder; the process conditions for cleaning 1 are as follows: add 5g / t of auxiliary collector diesel oil; the process conditions for cleaning 2 are as follows: add 100g / t of zinc sulfur inhibitor zinc sulfate and 10g / t of lead collector 25# sodium black powder.

[0062] (3) Zinc selection: For zinc roughing, add 450 g / t of sodium metabisulfite, 550 g / t of copper sulfate, 45 g / t of ethyl thiocyanate, and 10 g / t of MIBC foaming agent. For zinc fine selection, add 200 g / t of sodium metabisulfite, stir, and then perform two-stage fine selection. For zinc fine selection two, add 50 g / t of sodium metabisulfite, 2 g / t of ethyl thiocyanate, stir, and then perform three-stage fine selection. The concentrate from the three stages is zinc concentrate. For zinc scavenging, add 50 g / t of copper sulfate, 3 g / t of ethyl thiocyanate. For scavenging two, add 30 g / t of copper sulfate, 3 g / t of ethyl thiocyanate. The scavenging foam sequence is returned to the previous operation, and the tailings are discharged into the tailings pond.

[0063] As shown in Table 1 below, the treated tailings water is reused for grinding and flotation of the high-sulfur lead-zinc ore. The raw ore contains 2.22% lead and 6.81% zinc, and can produce lead concentrate with a lead content of 57.89% and a lead recovery rate of 90.23%, and zinc concentrate with a zinc content of 45.96% and a zinc recovery rate of 94.53%. Compared with the use of underground clean water beneficiation, the beneficiation indicators are basically unaffected.

[0064] Table 1. Mineral processing parameters for reuse of treated tailings water in grinding and flotation of high-sulfur lead-zinc ores.

[0065]

[0066] The flotation tailings and well water were reused in the grinding, classification and flotation operations of a lead-zinc mine in Chenzhou, Hunan Province, to verify their impact on mineral processing indicators, as shown in Table 2 below. For lead processing, the zinc sulfur inhibitor zinc sulfate dosage was 350 g / t, the lead collector 25# sodium black reagent dosage was 180 g / t, and for zinc processing, the sulfur inhibitor sodium metabisulfite dosage was 400 g / t, the zinc activator copper sulfate dosage was 300 g / t, and the zinc collector ethyl thiouric acid 40 g / t. Comparison showed that the mineral processing indicators were consistent with those obtained from the well water.

[0067] Table 2. Beneficiation indicators for the reuse of flotation tailings and downhole water in lead-zinc ore grinding, classification, and flotation operations.

[0068]

[0069] This invention utilizes a differentiated treatment and reuse system for mineral processing wastewater. First, the tailings water undergoes natural sedimentation and decomposition in a tailings pond. Then, it enters a wastewater treatment plant where sulfuric acid, catalysts, hydrogen peroxide, liquid alkali, sodium hydrosulfide, PAM, and stabilizers are added for treatment before reuse in grinding, classification, and flotation operations with strict water quality requirements. Concentrate overflow water, due to its complex composition and high residue levels of mineral processing reagents, is not directly used in grinding and flotation operations but is recycled for magnetic separation and sulfur removal operations where water quality is not critical. The water from the ceramic filter in the concentrate is clear and is collected and recycled for washing the filter. This ensures that the tailings water meets the production requirements for grinding and flotation, reduces the treatment costs of concentrate overflow water and filter water, and achieves 100% recycling of treated mineral processing wastewater.

[0070] In addition, this invention returns the sediment from the sedimentation tank to the front end of the coagulation reaction tank. Through the large specific surface area and pore structure of the sediment, the adsorption capacity of suspended particles, heavy metal particles, and organic pollutants is enhanced. Through chemical action, the chemical components contained in the sediment react with some pollutants to form precipitates, promoting the degradation and transformation of pollutants. Compared with the mixed treatment method of mineral processing wastewater, this invention has a low wastewater treatment cost of only 1 to 1.5 yuan / ton of water, while having almost no impact on lead and zinc beneficiation indicators.

[0071] The stabilizer used in this invention can further synergize with and enhance the flocculation and sedimentation effect of flocculants. After hydrolysis, the stabilizer generates colloidal particles with a large specific surface area, which adsorb suspended particles, colloidal substances, and some negatively charged pollutants in wastewater. Through charge neutralization and electrostatic attraction, it promotes the collision and aggregation between colloidal particles, thereby forming larger particles and accelerating sedimentation. For example, thallium ions in wastewater often exist in +1, +2, and +3 valences, but are mainly +1. When sodium hydrosulfide is added, thallium reacts with sulfur to form hydrated colloidal particles such as thallium disulfide, thallium sulfide, and thallium trisulfide. These particles are extremely small and charged, and are suspended colloidal particles in water. General coagulants and flocculants cannot completely capture these colloidal particles, resulting in turbid water and low flocculation and sedimentation effect. The stabilizer used in this invention is a compound agent with opposite charges, which can compress the electric double layer of colloidal particles, simultaneously perform adsorption bridging, sedimentation, and trapping. Through these three mechanisms, the potential of the colloidal particles is effectively reduced, causing the colloidal particles in the water to destabilize and form small flocs with a linear structure. After the flocculant is added, large flocs are formed, and the flocs are separated from the water by gravity, thereby efficiently separating the thallium compound colloidal particles from the water. The stabilizer used in this invention can further synergistically enhance the flocculation effect, and the effluent is clear and transparent, meeting the requirements of discharge concentrations far below industry standards.

Claims

1. A method for treating and recycling lead-zinc ore dressing wastewater by quality, characterized in that, The method comprises the following steps: S1: first, the tailings water is introduced into the lead-zinc tailings pond for natural decomposition and settlement, to remove part of the suspended solids and heavy metal ions, and to settle part of the organic matter; S2: the clarified beneficiation tail water after S1 settlement is introduced into a Fenton reaction tank, sulfuric acid is added to adjust the pH to 3-4, a catalyst is added, hydrogen peroxide is added, and Fenton oxidation reaction is carried out for 40-60 min; the porous structure of the catalyst can adsorb pollutants in the water body, Fe 2+ in the catalyst can react with H2O2 to generate hydroxyl radicals 3+ , and the pollutants in the water body are degraded by radical oxidation; the carrier in the catalyst can also promote the reduction of Fe 3+ to Fe 2+ , maintain the continuous Fenton reaction, and improve the degradation efficiency; S3: the tailings water in S2 is introduced into a coagulation reaction tank, liquid caustic is added to adjust the pH to 8-8.5, a precipitant is added to react with the heavy metal ions in the water body to generate insoluble precipitates, a flocculating agent and a stabilizing agent are added to flocculate and settle the precipitates; S4: after the addition of the treatment reagents, the tailings water is introduced into a honeycomb inclined pipe sedimentation tank after coagulation and stirring, for further flocculation and settlement, then the flocculation and settlement of the bottom tank are returned to the coagulation reaction tank in S3, and the excess sludge is discharged into the tailings pond; the settled clear water is introduced into a clear water tank, to be used as the production water for grinding and classification and flotation operations.

2. The method for lead-zinc ore dressing wastewater treatment and recycling according to claim 1, characterized in that, In the S2, the catalyst is activated carbon powder loaded with Fe 2+ The loading amount of Fe 2+ is 3-6 wt.%.

3. The method for lead-zinc ore dressing wastewater treatment and recycling according to claim 2, characterized in that, The activated carbon has a particle size of 100 mesh and a specific surface area of more than 800 m 2 / g.

4. The method for lead-zinc ore dressing wastewater treatment and recycling according to claim 1, characterized in that, In S2, the amount of the catalyst is 200-400 g / t; the concentration of the hydrogen peroxide is 27.5%, and the amount of the hydrogen peroxide is 100-300 g / t.

5. The method for lead-zinc ore dressing wastewater treatment and recycling according to claim 1, characterized in that, The liquid caustic is a mixed solution of sodium hydroxide and sodium carbonate, wherein the content of sodium hydroxide is 30.29%, and the content of sodium carbonate is 0.28%.

6. The method for lead-zinc ore dressing wastewater treatment and recycling according to claim 1, characterized in that, In S3, the precipitant is sodium sulfide, and the amount is 30-60 g / t.

7. The method for lead-zinc ore dressing wastewater treatment and recycling according to claim 1, characterized in that, In S3, the flocculating agent is polyacrylamide, and the amount is 5-20 g / t.

8. The method for lead-zinc ore dressing wastewater treatment and recycling according to claim 1, characterized in that, In S3, the stabilizing agent is selected from one or more of polymeric ferric sulfate, polymeric aluminum sulfate, polymeric ferric chloride and ferrous ammonium sulfate.

9. The method for lead-zinc ore dressing wastewater treatment and recycling according to claim 1, characterized in that, In S3, the amount of the stabilizing agent is 150-300 g / t.

10. The method for lead-zinc ore dressing wastewater treatment and recycling according to claim 1, characterized in that, In S4, after the flocculation and settlement of the bottom tank are returned to the coagulation reaction tank in S3, the flocculation and settlement can be used as crystal seeds matching the target crystal structure, to skip the difficult and slow homogeneous nucleation in the process of treating the heavy metal ions in the wastewater, to increase the contact opportunities of the ions and the crystal seeds, and to promote the precipitation of the heavy metal ions.

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