Method for removing COD from lead-zinc oxide ore flotation wastewater

Abstract

The application discloses a method for removing COD from lead-zinc oxide ore flotation wastewater, comprising the following steps: (1) pretreating flotation tailings of lead-zinc oxide ore by using a hydrodynamic cavitation device; (2) separating solid and liquid of the slurry obtained in the step (1) to obtain mineral processing wastewater and slag; (3) adding an oxidizing agent to the mineral processing wastewater obtained in the step (2) to perform an oxidation reaction; (4) adding acid to the reaction liquid after the step (3) to adjust pH and perform a hydrolysis reaction; (5) adding a biological agent to the reaction liquid after the step (4) to perform a catalytic oxidation reaction; and (6) separating solid and liquid of the reaction liquid after the step (5). The application can realize efficient removal of COD in lead-zinc oxide ore flotation wastewater, and the wastewater can be reused, and compared with the prior art, the application is more efficient, more environmentally friendly, low in cost and simple in operation.

Description

Technical Field

[0001] This invention belongs to the field of industrial wastewater treatment, and particularly relates to a method for removing COD from lead-zinc ore flotation wastewater. Background Technology

[0002] With the increasing depletion of lead-zinc sulfide resources, the efficient development and utilization of lead-zinc oxide resources has become an important issue for mineral processing workers. Currently, the flotation process for lead-zinc oxide ores generally involves: crushing – grinding – flotation – concentrate / tailings. During ball milling, activators (sodium sulfide) are added to activate lead oxide, inhibitors (zinc sulfate, sodium carbonate, lime) are added to inhibit sphalerite, and collectors (xanthate, dithiocyanate, etc.) are added to complete lead flotation. After adjusting the pH, activators (copper sulfate, lead nitrate, etc.) are added to activate sphalerite, and collectors (xanthate, dithiocyanate, etc.) and frothers are added to complete zinc sulfide mineral flotation. Finally, dispersants (water glass, sodium hexametaphosphate, etc.), activators (sodium sulfide, JF series activators, organic chelating agents, etc.), collectors (amines, xanthates, fatty acids, thiols, CF, CSFA, DZ-6, etc.) and frothers are added to complete non-desliming flotation of zinc oxide minerals. The foaming agents mainly include pine oil, cresol oil, terpineol, and methylpentanol.

[0003] The complex and difficult-to-process properties of oxidized lead-zinc ores are due to: high and highly variable lead-zinc oxidation rates; complex and varied mineral composition; complex ore structure; highly unstable associated components; and the presence of large amounts of clay, ferric hydroxide (such as limonite), and alum. These substances are prone to mud formation, making flotation control difficult. Furthermore, the presence of large amounts of soluble salts (such as oxides and sulfides of carbonates, sulfates, and silicates) not only causes slime agglomeration but also reacts with carbonate ions to form calcium carbonate precipitates that cover the mineral surface, significantly hindering the flotation process of oxidized lead-zinc ores. The complex interpenetration and interlocking of valuable minerals (such as hemimorphite, smithsonite, cerussite, and alum) with gangue minerals further increases the difficulty of flotation. Furthermore, the presence of fine minerals in the slime has a significant impact, especially in lead oxide ores heavily contaminated with ferric hydroxide, where the flotation effect is extremely poor. The flotation effect of fine-grained lead oxide ores is not ideal, and the flotation activity of coarse-grained zinc oxide ores is easily lost during the beneficiation process, causing them to fall off the flotation tank. The amount of reagents used, especially sodium sulfide, is large, and amine collectors are sensitive to slime and are used in large quantities. At the same time, beneficiation reagents such as frothers, xanthates, black reagents, ethyl thiocyanates, and water glass also need to be added. As a result, the wastewater from lead oxide zinc ore flotation has a complex composition, high salinity, high COD concentration, and very high pH, ​​usually around 12.0 to 13.0, exhibiting strong alkalinity, making it difficult to treat.

[0004] Currently, commonly used methods for treating mineral processing wastewater both domestically and internationally include coagulation sedimentation, oxidation, chemical precipitation, activated carbon adsorption, biological methods, and membrane methods. However, these methods are all difficult to achieve deep purification and reuse of wastewater in a low-cost and efficient manner. Existing technologies for COD removal from lead-zinc ore beneficiation wastewater are suitable for low-salinity, low-COD wastewater or low-salinity, high-COD wastewater, but not for treating high-salinity, high-COD lead-zinc ore beneficiation wastewater. Therefore, there is an urgent need to find an efficient, reasonable, effective, and practical treatment method for high-salinity, high-COD lead-zinc ore beneficiation wastewater. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for removing COD from flotation wastewater of lead-zinc ore with high salinity and high COD, in view of the current limitations in COD removal.

[0006] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0007] A method for removing COD from lead-zinc ore flotation wastewater includes the following steps:

[0008] (1) The flotation tailings of oxidized lead-zinc ore are pretreated by a hydraulic cavitation device; the flotation tailings are obtained directly from flotation without solid-liquid separation and contain residual mineral processing reagents.

[0009] (2) Separate the slurry obtained from the pretreatment in step (1) to obtain mineral processing wastewater and slag;

[0010] (3) Add an oxidant to the mineral processing wastewater obtained in step (2) to carry out an oxidation reaction;

[0011] (4) Add acid to the reaction solution after step (3) to adjust the pH and carry out the hydrolysis reaction;

[0012] (5) Add a biological agent to the reaction solution after step (4) to carry out a catalytic oxidation reaction; the biological agent includes bacterial solution and modified biochar, the bacterial solution is obtained by culturing a complex bacterial group including iron-reducing bacteria and Bacillus, and the modified biochar is biochar loaded with iron salts;

[0013] (6) Separate the liquid, solid and liquid after the reaction in step (5).

[0014] The remaining mineral processing reagents include frothers.

[0015] The COD concentration of the flotation tailings is 2000–5000 mg / L, and the TDS is ≥10 g / L.

[0016] As a further improvement, the flow rate of the flotation tailings through the hydraulic cavitation device in step (1) is 18-30 L / min.

[0017] As a further improvement, step (4) adjusts the pH to 4-6 and reacts for 15-20 minutes.

[0018] As a further improvement, the amount of biological agent added in step (5) is 0.2 to 1.0 g / L, and the reaction time is 15 to 30 min.

[0019] As a further improvement, the preparation method of the biological agent in step (5) includes:

[0020] (a) A complex microbial community including iron-reducing bacteria and Bacillus was cultured in a complex culture medium containing the mineral processing wastewater to obtain a bacterial solution;

[0021] (b) Add biochar to the iron salt solution, disperse evenly, and dry to obtain modified biochar;

[0022] (c) The modified biochar is added to the bacterial solution and dispersed evenly to obtain the biological agent.

[0023] As a further improvement, the mass ratio of iron-reducing bacteria to Bacillus in the complex microbial community described in step (a) is 3:(6-8).

[0024] As a further improvement, the amount of biochar added in step (b) is 20% to 30% of the mass of iron salt.

[0025] As a further improvement, the amount of modified biochar added in step (c) is 10% to 20% of the bacterial culture mass.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] (1) This invention utilizes the properties of the slurry after flotation of oxidized lead-zinc ore to achieve preliminary removal of COD and salts from the ore slurry under the action of hydraulic cavitation. Specifically, this invention utilizes the frother in the residual beneficiation reagents in the slurry after flotation and the gravity of the slurry itself to enhance the hydraulic cavitation effect, thereby generating a local high concentration of strong oxidizing free radicals inside the slurry, which plays an activation role. These free radicals can directly oxidize the residual beneficiation reagents in the slurry, thereby inducing, initiating and enhancing the chemical reaction. At the same time, the strong hydrodynamic shear force generated when the cavitation bubbles collapse will also cause the chemical bonds on the main chain of macromolecules to break and generate free radicals, thereby achieving preliminary removal of COD from the slurry, greatly reducing the amount of subsequent COD removal reagents added and lowering the reagent cost. Cavitation generates a mechanical effect, which can generate enough energy to break up some of the ore, clay, etc. in the slurry, increasing the specific surface area and its adsorption capacity. Through adsorption, some beneficiation reagents and some salts are removed, thereby reducing the salt content in the slurry and improving the subsequent oxidation efficiency.

[0028] (2) Based on the properties of wastewater, this invention makes full use of the oxidant to form peroxy organic acids with organic matter in the wastewater in a strongly alkaline environment to further mineralize COD.

[0029] (3) Adjust the pH to weakly acidic. Some of the residual mineral processing reagents will undergo molecular rearrangement or hydrolysis into small molecules, which will generate free sulfur ions.

[0030] In biological agents, iron salts loaded on biochar primarily react with sulfur ions in wastewater through precipitation to remove sulfur ions. Simultaneously, the iron salts catalyze residual oxidants, generating more strong oxidizing free radicals (sulfoxy radicals, hydroxyl radicals, or chloroxy radicals, etc.). Combined with the catalytic and adsorption functions of biochar and microbial metabolites (catalase, capsules, mucus, polysaccharides, polypeptides, and proteins, etc.), this process efficiently removes organic matter from wastewater, achieving deep COD removal. The loaded Bacillus can reduce Fe... 3+ For Fe 2+ This enables the loaded iron salt to achieve Fe 2+ Fe 3+ The cycle increases the production rate of strong oxidizing free radicals.

[0031] (4) The method for removing COD from lead-zinc oxide ore flotation wastewater provided by the present invention reduces the amount of alkali and acid used compared with the traditional Fenton method for removing COD. At the same time, no toxic and harmful gases such as H2S and CO are detected, making it more environmentally friendly and achieving higher COD removal efficiency, thus realizing deep purification of flotation wastewater.

[0032] (5) This invention pre-treats the wastewater at the front end of the mineral processing wastewater generation (before the solid-liquid separation of the slurry). With the concept of treating waste with waste, it is more efficient and environmentally friendly than existing processes, with lower investment and operating costs, simpler operation, and stronger resistance to shock loads. It can achieve efficient removal of COD from the flotation wastewater of oxidized lead-zinc ore, and the wastewater can be reused. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a process flow diagram of a specific embodiment of the present invention. Detailed Implementation

[0035] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0036] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0037] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0038] As is known in the art, oxidized lead-zinc ore is ground and flotated to obtain concentrate and flotation tailings. During the flotation process, activators, collectors, and frothers are added. The method of this invention deals with flotation tailings that have not undergone solid-liquid separation (i.e., the slurry after flotation). The suspended solids in the flotation tailings mainly include unfloted ore components, flotation reagent residues, gangue minerals, clay, and other impurities.

[0039] In some embodiments, the COD concentration of the flotation tailings of oxidized lead-zinc ore is 2000–5000 mg / L, and the TDS is ≥10 g / L. In some embodiments, the pH of the flotation tailings of oxidized lead-zinc ore is 12.3–13.3, and the COD concentration is 2739–4681 mg / L. 2- The content ranges from 417 to 826 mg / L, and the total dissolved solids (TDS) ranges from 13984 to 17530 mg / L. The mineral processing reagents are reflected in the COD concentration, while the salt content is reflected in the TDS content.

[0040] like Figure 1 The method for removing COD from lead-zinc ore flotation wastewater of the present invention includes the following steps:

[0041] (1) The flotation tailings (flotation slurry) of oxidized lead-zinc ore are pretreated using a hydraulic cavitation device.

[0042] In some embodiments, the flow rate of flotation tailings through the hydraulic cavitation device is 18–30 L / min, and the rotation speed is 2600–2900 rpm. Under the action of hydraulic cavitation, the COD of oxidized lead-zinc ore flotation tailings is initially removed, and the TDS and S are reduced. 2- content.

[0043] (2) Separate the slurry obtained from the pretreatment in step (1) to obtain mineral processing wastewater and slag.

[0044] (3) Add an oxidant to the mineral processing wastewater obtained in step (2) to carry out an oxidation reaction.

[0045] In some embodiments, during the oxidation reaction, the added oxidant is one or more of H2O2 (20-40 wt%), hypochlorite solution (8-20 wt%), and perchlorate solution, and the reaction time is 30-60 min. The amount of oxidant added is proportional to the COD concentration at a ratio of 1 ml oxidant to (100-220) mg COD.

[0046] (4) Add acid to the reaction solution after step (3) to adjust the pH and carry out the hydrolysis reaction.

[0047] In some embodiments, the pH of the wastewater is adjusted to 4-6, and the reaction is carried out for 15-20 minutes.

[0048] (5) Add biological agents to the reaction solution after step (4) to carry out catalytic oxidation reaction.

[0049] In some embodiments, in the catalytic oxidation of biological agents, the amount of biological agent added is 0.2 to 1.0 g / L, and the reaction time is 15 to 30 min.

[0050] (6) Separate the liquid, solid and liquid phases after the reaction in step (5). The effluent can be reused, and the slag is sent to the tailings pond.

[0051] In some embodiments, the preparation method of the biological agent is as follows:

[0052] (1) The complex bacterial group including iron-reducing bacteria and Bacillus was domesticated and cultured in a complex culture medium with a small amount of the mineral processing wastewater added to obtain bacterial solution.

[0053] In some embodiments, the mass ratio of iron-reducing bacteria to Bacillus in the complex microbiota is 3:(6-8).

[0054] In some embodiments, the proportion of mineral processing wastewater added is 10-30% of the mass of the composite culture medium.

[0055] In some embodiments, the main components of the composite culture medium include: 10.0-20.0 g / L of peptone soybean broth, 10.0-20.0 g / L of glucose, 10.0-20.0 g / L of peptone, 1.0-2.0 g / L of sodium dihydrogen phosphate, 1.0-2.0 g / L of calcium chloride, 3.0-4.0 g / L of biotin, and 5.0-10.0 g / L of ferrous sulfate.

[0056] In some embodiments, the pH of the domestication culture is 4.5 to 6.0, and the temperature is 20 to 35°C.

[0057] In some embodiments, the concentration of bacteria in the bacterial solution is 5.0 × 10⁻⁶. 8 cfu / mL~9.0×10 8 cfu / mL.

[0058] (2) Preparation of modified biochar. Biochar was added to an iron salt solution, dispersed evenly, and dried at a low temperature (30-40℃) to obtain modified biochar.

[0059] In some specific embodiments, the iron salt is one or more of ferrous chloride, ferrous sulfate, ferric sulfate, polyferric sulfate, ferric chloride, ferrous nitrate, ferric nitrate, and ferrous acetate.

[0060] In some specific embodiments, the biochar is one or more of pine nut shell biochar, sawdust biochar, rice husk biochar, bagasse biochar, and coconut shell biochar.

[0061] In some specific embodiments, the iron salt solution concentration is 10–30 wt%. The amount of biochar added is 20%–30% of the iron salt mass.

[0062] (3) Add the modified biochar to the bacterial solution in step (1) to obtain the modified biochar biological agent loaded with bacteria.

[0063] In some specific embodiments, the amount of modified biochar added is 10% to 20% of the bacterial solution mass.

[0064] The method for removing COD from lead-zinc ore flotation wastewater provided by this invention has the advantages of simple and stable process, high wastewater reuse rate, easy operation, small footprint, low cost, and no secondary pollution.

[0065] Example 1

[0066] The flotation tailings of a certain oxidized lead-zinc ore were selected. The pH was 12.9, the COD concentration was 2739 mg / L, and the S... 2- The content was 417 mg / L, and the TDS was 13984 mg / L.

[0067] (1) Oxidized lead-zinc ore flotation tailings were treated with a hydraulic cavitation device, with the rotation speed controlled at 2600 rpm and the flow rate at 20 L / min, and the power at approximately 14.5 KW, to achieve preliminary COD removal. The COD concentration in the effluent was 1427 mg / L. 2- The content was not detected, and the TDS was 6293 mg / L;

[0068] (2) In step (1), the mud is separated into solid and liquid by passing it through an inclined plate sedimentation tank;

[0069] (3) Add 8.0 ml / L NaClO solution (10 wt%) to the effluent (mineral processing wastewater) in step (2), react for 30 min, and the COD of the effluent is 619.9 mg / L;

[0070] (4) After the reaction in step (3), add an appropriate amount of sulfuric acid to adjust the pH to 6 and react for 15 minutes.

[0071] (5) Add 0.2 g / L of biological agent to the reaction solution after step (4) and react for 15 min;

[0072] (6) The liquid after the reaction in step (5) enters the inclined plate sedimentation tank to achieve solid-liquid separation. The COD concentration in the effluent is 374 mg / L, which can be reused. The tailings enter the tailings pond.

[0073] The preparation method of the biological agent in this embodiment is as follows:

[0074] (1) A complex bacterial culture consisting of approximately 30% iron-reducing bacteria and approximately 70% Bacillus was cultured in a complex culture medium containing a small amount of mineral processing wastewater (10%) (10.0 g / L peptone soybean broth, 10.0 g / L glucose, 10.0 g / L peptone, 1.0 g / L sodium dihydrogen phosphate, 1.0 g / L calcium chloride, 3.0 g / L biotin, and 5.0 g / L ferrous sulfate). The culture was acclimatized at a pH of 5.0 and a temperature of 20°C.

[0075] (2) Preparation of modified biochar: Prepare a 10% ferric chloride + polyferric sulfate solution, add appropriate amounts of rice husk biochar and sawdust biochar, the amount of which is 20% of the iron salt, and dry at low temperature (25℃) to obtain modified biochar.

[0076] (3) The modified biochar was added to a bacterial solution containing iron-reducing bacteria and Bacillus (the concentration of bacteria in the bacterial solution was approximately 5.0 × 10⁻⁶). 8 The bacteria were evenly dispersed in a solution of cfu / mL to obtain modified biochar loaded with bacteria. The amount of modified biochar added was 10% of the mass of the bacterial solution.

[0077] Example 2

[0078] The flotation tailings of a certain oxidized lead-zinc ore were selected. The pH was 12.3, the COD concentration was 3859 mg / L, and the S... 2- The content was 713 mg / L, and the TDS was 15860 mg / L.

[0079] (1) The tailings slurry from the flotation of oxidized lead-zinc ore was subjected to a hydraulic cavitation device. The device was operated at a speed of 2800 rpm and a flow rate of 25 L / min, with a power of approximately 15.0 KW. This achieved preliminary COD removal, resulting in a COD concentration of 2351 mg / L in the effluent. 2- The content was 0.32 mg / L, and the TDS was 8904 mg / L;

[0080] (2) In step (1), the mud is separated into solid and liquid by passing it through an inclined plate sedimentation tank;

[0081] (3) 7.5 ml / L H2O2 (30 wt%) was added to the effluent (mineral processing wastewater) in step (2), and the reaction was carried out for 30 min. The COD of the effluent was 674 mg / L.

[0082] (4) After the reaction in step (3), add an appropriate amount of sulfuric acid to adjust the pH to 5.0 and react for 15 minutes.

[0083] (5) Add 0.5 g / L of biological agent to the reaction solution after step (4) and react for 30 min;

[0084] (6) The liquid after the reaction in step (5) enters the inclined plate sedimentation tank to achieve solid-liquid separation. The COD concentration in the effluent is 246 mg / L, which can be reused. The tailings enter the tailings pond.

[0085] The preparation method of the biological agent is as follows:

[0086] (1) A complex bacterial culture consisting of approximately 30% iron-reducing bacteria and approximately 70% Bacillus was cultured in a complex culture medium containing a small amount of mineral processing wastewater (25%) (15.0 g / L peptone soybean broth, 12.0 g / L glucose, 15.0 g / L peptone, 1.2 g / L sodium dihydrogen phosphate, 1.5 g / L calcium chloride, 3.5 g / L biotin, and 8.0 g / L ferrous sulfate). The culture was acclimatized at a pH of 6.0 and a temperature of 30°C.

[0087] (2) Preparation of modified biochar: Prepare a 20% ferrous sulfate solution, add an appropriate amount of pine nut shell biochar, the amount of which is 25% of the iron salt, and dry at low temperature (30℃) to obtain modified biochar.

[0088] (3) The modified biochar was added to a bacterial solution containing iron-reducing bacteria and Bacillus (the concentration of bacteria in the bacterial solution was approximately 7.0 × 10⁻⁶). 8 In a solution of cfu / mL, modified biochar with loaded bacteria was obtained, with the amount of modified biochar added being 15% of the mass of the bacterial solution.

[0089] Example 3

[0090] The flotation tailings of a certain oxidized lead-zinc ore were selected. The pH was 13.3, the COD concentration was 4681 mg / L, and the S... 2- The content is 826 mg / L, and the TDS is 17530 mg / L.

[0091] (1) The tailings slurry from the flotation of oxidized lead-zinc ore was subjected to a hydraulic cavitation device with a controlled rotation speed of 2900 rpm and a flow rate of 25 L / min, with a power of approximately 15.5 KW, to achieve preliminary COD removal. The COD concentration in the effluent was 2549 mg / L. 2-The content was not detected, and the TDS was 9116 mg / L;

[0092] (2) In step (1), the mud is separated into solid and liquid by passing it through an inclined plate sedimentation tank;

[0093] (3) Add 10 ml / L H2O2 (30 wt%) to the effluent (mineral processing wastewater) in step (2), react for 60 min, and the COD of the effluent is 759 mg / L;

[0094] (4) After the reaction in step (3), add an appropriate amount of sulfuric acid to adjust the pH to 5.5 and react for 15 minutes.

[0095] (5) Add 0.6 g / L of biological agent to the reaction solution after step (4) and react for 20 min;

[0096] (6) The liquid after the reaction in step (5) enters the inclined plate sedimentation tank to achieve solid-liquid separation. The COD concentration in the effluent is 362 mg / L, which can be reused. The tailings enter the tailings pond.

[0097] The preparation method of the biological agent is as follows:

[0098] (1) A complex bacterial culture consisting of approximately 30% iron-reducing bacteria and approximately 70% Bacillus was cultured in a complex culture medium containing a small amount of mineral processing wastewater (30%) (20.0 g / L peptone soybean broth, 20.0 g / L glucose, 20.0 g / L peptone, 2.0 g / L sodium dihydrogen phosphate, 2.0 g / L calcium chloride, 4.0 g / L biotin, and 10.0 g / L ferrous sulfate) to obtain a bacterial solution. The pH of the culture was 6.0 and the temperature was 30℃.

[0099] (2) Preparation of modified biochar: Prepare a 30% ferric sulfate solution, add an appropriate amount of coconut shell biochar, the amount of which is 30% of the ferric salt, and dry at low temperature (35℃) to obtain modified biochar.

[0100] (3) The modified biochar was added to a bacterial solution containing iron-reducing bacteria and Bacillus (the concentration of bacteria in the bacterial solution was approximately 9.0 × 10⁻⁶). 8 In a solution of cfu / mL, modified biochar with loaded bacteria was obtained, with the amount of modified biochar added being 20% ​​of the mass of the bacterial solution.

[0101] Comparative Example 1: Fenton Method

[0102] The flotation tailings of a certain oxidized lead-zinc ore were selected. The pH was 13.5, the COD concentration was 4681 mg / L, and the S... 2- The content is 826 mg / L, and the TDS is 17530 mg / L.

[0103] (1) Add 4.5 kg / m 3The pH was adjusted to 3.0 with concentrated sulfuric acid. During this stage, a large amount of hydrogen sulfide and CO, which have irritating odors, were produced. The COD concentration in the effluent was 2195 mg / L.

[0104] (2) Add 3.5 kg / m 3 FeSO4·7H2O and 10L / m 3 H2O2, react for 40 min;

[0105] (3) Add 1.8 kg / m 3 NaOH, adjust pH to 7.0, hydrolyze for 15 min;

[0106] (4) Add a small amount of flocculant, let it settle for 2 hours. The effluent is turbid, with COD concentration of 1272 mg / L, TDS of 21589 mg / L, and S... 2- The content was not detected.

[0107] Comparative Example 2: Biological Agent Treatment

[0108] The flotation tailings of a certain oxidized lead-zinc ore were selected. The pH was 13.3, the COD concentration was 4681 mg / L, and the S... 2- The content is 826 mg / L, and the TDS is 17530 mg / L.

[0109] (1) Add 3.5g / L concentrated sulfuric acid to adjust the pH to 5.5. During this stage, a large amount of hydrogen sulfide and CO and other gases with irritating odors are produced. The COD concentration in the effluent is 3517mg / L.

[0110] (2) Add 0.6 g / L of biological agent and react for 20 min;

[0111] (3) The reaction liquid after step (2) enters the inclined plate sedimentation tank to achieve solid-liquid separation. The COD concentration in the effluent is 2264 mg / L, and the TDS content is 19187 mg / L (adding sulfuric acid will increase TDS). 2- The content was not detected.

[0112] The preparation method of the biological agent is the same as in Example 3.

[0113] Comparative Example 3: Treatment of mineral processing wastewater by hydraulic cavitation

[0114] The flotation tailings of a certain oxidized lead-zinc ore were selected. The pH was 13.3, the COD concentration was 4681 mg / L, and the S... 2- The content is 826 mg / L, and the TDS is 17530 mg / L.

[0115] After the slurry passes through a solid-liquid separation device, mineral processing wastewater and tailings are obtained.

[0116] The supernatant (mineral processing wastewater) enters the hydraulic cavitation device, with a controlled rotation speed of 2900 rpm and a flow rate of 25 L / min. The power is approximately 15.5 KW, and the COD concentration in the effluent is 4419 mg / L.

[0117] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims

1. A method for COD removal from lead-zinc oxide ore flotation wastewater, characterized by, The method comprises the following steps: (1) the flotation tailings of lead-zinc oxide ore are pretreated by a hydrodynamic cavitation device; the flotation tailings are directly obtained by flotation without solid-liquid separation, and contain residual beneficiation reagents, including a foaming agent; the flow rate of the flotation tailings through the hydrodynamic cavitation device is 18-30 L / min, and the rotation speed is 2600-2900 rpm; (2) the slurry obtained in step (1) is subjected to solid-liquid separation to obtain beneficiation wastewater and slag; (3) an oxidizing agent is added to the beneficiation wastewater obtained in step (2) to perform an oxidation reaction; (4) an acid is added to the reaction solution after step (3) to adjust the pH and perform a hydrolysis reaction; (5) a biological agent is added to the reaction solution after step (4) to perform a catalytic oxidation reaction; the biological agent comprises a bacterial solution and modified biomass charcoal, the bacterial solution is obtained by culturing a complex microbial population comprising iron-reducing bacteria and bacillus, and the modified biomass charcoal is biomass charcoal loaded with iron salt; the preparation method of the biological agent comprises: (a) culturing a complex microbial population comprising iron-reducing bacteria and bacillus in a complex culture medium added with the beneficiation wastewater to obtain a bacterial solution; (b) adding biomass charcoal to an iron salt solution, uniformly dispersing, and drying to obtain modified biomass charcoal; (c) adding the modified biomass charcoal to the bacterial solution, uniformly dispersing, and obtaining the biological agent; (6) the reaction solution after step (5) is subjected to solid-liquid separation.

2. The method of COD removal from lead-zinc oxide ore flotation wastewater according to claim 1, characterized in that, The COD concentration of the flotation tailings is 2000-5000 mg / L, and the TDS is ≥10 g / L.

3. The method of COD removal from lead-zinc oxide ore flotation wastewater as claimed in claim 1, wherein, In step (4), the pH is adjusted to 4-6, and the reaction is performed for 15-20 min.

4. The method of COD removal from lead-zinc oxide ore flotation wastewater according to claim 1, characterized in that, In step (5), the addition amount of the biological agent is 0.2-1.0 g / L, and the reaction time is 15-30 min.

5. The method of COD removal from lead-zinc oxide ore flotation wastewater as claimed in claim 1, wherein, In step (a), the mass ratio of iron-reducing bacteria to bacillus in the complex microbial population is 3: (6-8).

6. The method of COD removal from lead-zinc oxide ore flotation wastewater as claimed in claim 1, wherein, In step (b), the addition amount of the biomass charcoal is 20%-30% of the mass of the iron salt.

7. The process for removal of COD from lead-zinc oxide ore flotation wastewater as claimed in claim 1 wherein, In step (c), the addition amount of the modified biomass charcoal is 10%-20% of the mass of the bacterial solution.

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