Method for improving removal efficiency of COD (Chemical Oxygen Demand) and total oil in overflow water of tailings pond of copper mine

Abstract

The invention discloses a method for improving the removal efficiency of COD (Chemical Oxygen Demand) and total oil in overflow water of a tailing pond of a copper mine, which comprises the following steps: S1, adjusting the pH (Potential of Hydrogen) of copper ore copper separation alkaline wastewater to 4.5 to 5.5 by adopting an acidic medicament; s2, the wastewater with the pH adjusted enters an iron-carbon micro-electrolysis reaction tank; s4, the wastewater subjected to advanced oxidation treatment enters a neutralization reaction tank, the pH of the wastewater is adjusted to 8-9 through an alkaline agent, the reaction is sufficient, and then a modified macromolecule anion flocculant solution is added. According to the technology, through the technical scheme of wastewater pH adjustment, iron-carbon micro-electrolysis oxidation, reduction reaction, advanced oxidation with sodium persulfate and flocculent precipitation, the concentration of pollutants such as COD and total oil in the copper ore copper separation alkaline wastewater can be remarkably reduced, and the problem that the removal efficiency of COD and total oil in existing copper ore copper separation wastewater is not high is solved; the risk that the wastewater affects the environment is effectively reduced, and a foundation is provided for effective utilization of the treated wastewater.

Description

Technical Field

[0001] The invention relates to the technical field of treatment and utilization of copper mine wastewater, and in particular to a method for improving the removal efficiency of COD and total oil in overflow water of a copper mine tailings pond. Background Art

[0002] The overflow water of the copper concentrator of the copper mine is directly discharged into the tailings pond. The wastewater contains pollutants such as high concentrations of tailings and residual beneficiation agents. During the stay in the tailings pond, the tailings wastewater undergoes natural degradation treatment of pollutants such as sunlight, natural oxidation, and sedimentation purification. Due to the oxidation of sulfur in the tailings and the influence of tailings acidification, the pH of the wastewater shows a downward trend. The pH of the wastewater can be reduced from 9 to 11 to 5 to 8, and some metals may be dissolved. Some tailings pond wastewater uses artificial aeration to enhance the degradation and removal of pollutants. The beneficiation wastewater undergoes the effects of tailings sedimentation and compression in the tailings pond, and finally forms overflow water with a very low suspended matter concentration and is discharged from the tailings pond. Generally, the pH of this type of wastewater is 6.0 to 9.0. However, due to the influence of meteorological factors such as temperature, rainfall, and sunshine, the water quality of the tailings pond overflow water fluctuates. The COD in the overflow water fluctuates between 15 and 150 mg / L, and the total oil fluctuates between 1.5 and 6.0 mg / L. In severe cases, other metals occasionally exceed the standard, and the pH of the wastewater can be reduced to 5.0. Therefore, this type of wastewater still poses an environmental risk in terms of discharge.

[0003] Some copper mine tailings ponds return part of the overflow water for use, and the excess overflow water is discharged for treatment; some mine tailings ponds have wastewater treatment facilities built on site for treatment or direct discharge due to problems such as difficulty in wastewater transportation. At present, there are roughly two types of copper mine alkaline wastewater treatment: (1) copper mine alkaline wastewater is mixed with mine acidic wastewater, and the pH of the two wastewaters is controlled to be 7.0-8.5 after neutralization, and then coagulated and precipitated. The precipitated sludge is transported to the tailings pond, and the supernatant is directly discharged as wastewater. This type of treatment method can play a certain role in governance. However, the amount of acidic wastewater produced by mines and water quality conditions vary greatly due to rainfall, mining locations and other factors, resulting in a mismatch between the mixing ratio of copper mine alkaline wastewater and mine acidic wastewater, and there is still a hidden danger in the treatment of discharged wastewater; (2) First, sulfuric acid or hydrochloric acid is used to adjust the pH of copper mine alkaline wastewater to weak acidity, and then lime is used for neutralization to adjust the pH of the wastewater to 7-9, and then coagulation and precipitation are carried out. The precipitated sludge is transported to the tailings pond, and the supernatant is directly discharged as wastewater. The above treatment method can effectively remove heavy metals in wastewater, but the reducing substances (COD) and total oil in the wastewater still fluctuate greatly.

[0004] In summary, according to the direct emission limit of the "Copper-Nickel-Cobalt Industrial Pollutant Emission Standard" (GB 25467-2010), the COD of the discharged wastewater is required to be ≤60mg / L and the petroleum is ≤3.0mg / L. Obviously, it is necessary to improve the removal efficiency of COD and total oil in the overflow water of the copper mine tailings pond. Therefore, this application provides a method for improving the removal efficiency of COD and total oil in the overflow water of the copper mine tailings pond to meet the demand. Summary of the invention

[0005] The purpose of this application is to provide a method for improving the removal efficiency of COD and total oil in the overflow water of the copper mine tailings pond, to enhance the removal depth of COD and total oil in such wastewater, and to improve the treatment efficiency.

[0006] To achieve the above purpose, the present application provides the following technical solution: a method for improving the removal efficiency of COD and total oil in the overflow water of a copper mine tailings pond, comprising the following steps:

[0007] S1: Use acidic reagents to adjust the pH of copper ore copper beneficiation alkaline wastewater to 4.5-5.5;

[0008] S2: The wastewater after pH adjustment enters the iron-carbon micro-electrolysis reaction tank to achieve chain-breaking degradation of organic matter in the ring-chain or long-chain mineral processing reagents in the wastewater, and decompose the macromolecular pollutants into small molecular organic matter that is easy to remove;

[0009] S3: The wastewater after the iron-carbon micro-electrolysis reaction enters the sodium persulfate advanced oxidation reaction tank, and the Fe 2+ It produces highly active SO4- ions with the added sodium persulfate, which synergistically degrade organic pollutants in wastewater under weakly acidic conditions. At the same time, it also degrades some Fe 2+ Oxidized to Fe 3+ , forming Fe(OH)3 colloids that can adsorb or aggregate fine particles;

[0010] High sodium sulfate advanced oxidation fully utilizes the Fe remaining in the wastewater after iron-carbon micro-electrolysis reaction 2+ It works synergistically with the highly active SO4- ions produced by sodium persulfate under weakly acidic conditions to degrade pollutants such as residual mineral processing organic agents in the wastewater.

[0011] S4: The wastewater after advanced oxidation treatment enters the neutralization reaction tank, and the pH value of the wastewater is adjusted to 8-9 with an alkaline agent to fully react. Then, a modified polymer anion flocculant solution is added to allow the suspended matter, colloids and other fine particles in the wastewater to fully react with the flocculant. Finally, the wastewater is allowed to stand to achieve solid-liquid separation in the wastewater. The supernatant can be directly discharged or returned for use, and the underflow can be mixed with the tailings for treatment or use;

[0012] The static wastewater described in S4 is set at a particle sedimentation rate of 0.50 to 0.65 m3 / (m 2 ˙h), determine the standing time.

[0013] Acidic agents may include commonly used acid materials such as sulfuric acid, hydrochloric acid, nitric acid, oxalic acid, or acid salts such as ferrous sulfate. Considering that some acid materials or salts may lead to an increase in pollutants such as COD and total nitrogen in the treated effluent, sulfuric acid is used as the agent for adjusting the pH of the wastewater in this application document.

[0014] Process characteristics of this application

[0015] (1) The pH is adjusted to 4.5-5.5, which can satisfy the conversion of iron in the iron-carbon material (equivalent to the negative electrode of the microbattery and the electrolytic anode) into ferrous ions: Fe-2e - →Fe 2+ ; Carbon (equivalent to the positive electrode of the microbattery and the cathode of electrolysis): O2+2H2O+4e - =4OH - 、O2+4H + +4e - →2H2O (sufficient oxygen), this application does not add oxygen, and keeps a small amount of Fe in the wastewater 2+ , it can serve as electron transfer for the subsequent sodium persulfate oxidation, but it cannot oxidize all the ferrous ions. In that case, the oxidation efficiency of sodium persulfate will be greatly reduced.

[0016] (2) The iron-carbon microbattery reaction mainly uses elemental iron to release electrons to become ferrous ions; it uses dissolved oxygen in the wastewater and organic matter in the wastewater to accept electrons to achieve chain breaking and degradation of organic matter.

[0017] (3) Using weak acid conditions to improve the oxidation effect of sodium persulfate.

[0018] (4) After oxidation, the pH value of the wastewater is increased. The use of composite alkali can reduce the amount of sludge produced and the amount of alkaline materials used. In addition, the carbon powder contained in the composite alkali can be used as an adsorption material to aggregate the fine particles in the wastewater and facilitate sedimentation.

[0019] The method of the present invention not only effectively removes COD and total oil in the overflow water of the copper mine tailings pond, but also can further remove pollutants such as related metals, fluorides, sulfides and the like in the wastewater.

[0020] As a preferred implementation in this embodiment, in the step S1, the acidic agent is sulfuric acid, and the concentration of the sulfuric acid is 15% to 45%.

[0021] The advantages of using sulfuric acid with a concentration of 15% to 45% to adjust the pH of wastewater are: sulfuric acid has a strong neutralizing ability; when the concentration of sulfuric acid is 47% to 50%, sulfuric acid is the most corrosive; the wastewater pH = 8 to 9 is adjusted to 4.5 to 5.5, and the amount of sulfuric acid used is very small. If 98% sulfuric acid is directly used for adjustment, the addition method is difficult to control. Therefore, using sulfuric acid with a concentration of 15% to 45% to adjust the pH of wastewater can ensure neutralization capacity, slow down the corrosion of sulfuric acid on the dosing pipeline and pump, and ensure accurate addition.

[0022] As a preferred implementation in this embodiment, in S2, the iron carbon is in the form of tiny particles with a particle size of 1 to 10 mm, and the composition of the iron carbon is: iron content = 65% to 85%, carbon content = 15% to 35%.

[0023] The advantages of the present invention in degrading COD and total oil in wastewater are: controlling the amount of iron and carbon in the iron-carbon material (Fe / C=0.39-1.21 mol / mol), achieving matching of the electron transfer capacity between the anode and the cathode, and maximizing the concentration of activated hydrogen (˙H or [H]), thereby improving the efficiency of degrading organic matter in wastewater.

[0024] As a preferred implementation in this embodiment, in S2, the iron-carbon micro-electrolysis reaction cell includes a first tank body and a second tank body, the first tank body is an oxidation-reduction reaction area, the second tank body is a wastewater and iron-carbon powder separation area, the stirring device of the first tank body adopts a plate-frame stirrer with a rotation speed of 15 to 30 rpm, and the surface load rate of the precipitation area of ​​the second tank body is 1.15 to 1.25 m 3 / (m 2 h), the bottom flow generated in the sedimentation area of ​​the second tank body is directly returned to the first tank body, realizing the full utilization of iron and carbon. Under the acidic conditions of the wastewater, iron and carbon produce new ecological H and Fe 2+ Active reducing media such as chlorinated bicarbonate can break the chains of macromolecular and polycyclic organic matter in wastewater, generating pollutants that are easily degraded, adsorbed and neutralized.

[0025] The advantage of using a plate and frame agitator in the reaction area of ​​the iron-carbon micro-electrolysis cell is that the iron-carbon that reacts with organic matter in the wastewater is in granular form. The use of a plate and frame agitator can produce a greater disturbance to the wastewater and the iron-carbon material, which is beneficial to the renewal of the iron-carbon surface, promotes full contact between the organic pollutants in the wastewater and the iron-carbon surface, and increases the mass transfer rate between the liquid-solid interface.

[0026] The function of the precipitation area of ​​the iron-carbon micro-electrolysis cell is to precipitate larger particles of iron-carbon materials. The precipitated iron-carbon particles can be returned to the reaction tank of the iron-carbon micro-electrolysis, and the wastewater carries a small amount of fine particles (with organic pollutants attached) into the subsequent advanced oxidation reaction tank. Due to the high density of iron-carbon particles (1.2-1.5t / m3 ), the average particle size is greater than 1mm, the precipitation rate of iron and carbon is relatively high, and there are fewer fine particles in the wastewater of the reaction device. Therefore, the surface loading rate of the precipitation area is determined to be 1.15-1.25m 3 / (m 2 ˙h), the area required for precipitation can be reduced while meeting the efficacy.

[0027] As a preferred implementation in this embodiment, in S3, the concentration of the sodium persulfate solution is 10% to 15%. Sodium persulfate is a strong oxidant. The concentration of the sodium persulfate solution is linearly positively correlated with its corrosion rate to carbon steel, stainless steel, copper, etc. To ensure that the equipment, pipelines and other materials added with the sodium persulfate solution are not corroded, the concentration of the sodium persulfate solution must be controlled within 25%. Therefore, under the premise of ensuring the oxidation capacity of the sodium persulfate solution, the experiment determines that the concentration of the sodium persulfate solution is 10% to 15% for the best effect, and the amount of sodium persulfate used is 50 to 100 g / m 3 , the oxidation reaction residence time is 2 to 4 hours.

[0028] As a preferred implementation in this embodiment, the alkaline agent is a composite alkaline solution with a concentration of 20% to 30%;

[0029] The alkaline agent can be selected from composite alkali, lime, caustic soda, sodium carbonate and other alkaline agents. The present invention uses composite alkali, and uses calcium oxide or calcium hydroxide in the composite alkali to adjust the pH of wastewater. Fine particles are formed during the reaction process, which can be adsorbed by diatomaceous earth, activated carbon and the like in the composite alkali and aggregated into larger particles, and can also destabilize the colloid in the wastewater, thereby improving the removal effect of fine suspended pollutants.

[0030] As a preferred implementation of this embodiment, in S4, the modified polymer anionic flocculant is a sulfonic acid modified polymer anionic polyacrylamide, with a concentration of 0.02% to 0.05% and a usage amount of 4 to 10 g / m 3 .

[0031] The modified polymer anionic flocculant used is easy to stretch in water and form a polymer complex with strong bonding force, which has strong netting and bridging capabilities. According to tests, when its preparation concentration is higher than 0.1%, it forms a gel and is difficult to measure and add to the wastewater. Therefore, the amount of this flocculant used is very small. On the basis of ensuring the excellent use effect, its preparation concentration is determined to be 0.02% to 0.05%

[0032] A modified polymer anionic flocculant, comprising 35% to 45% of a polymer flocculant with a molecular weight greater than 20 million, 2% to 5% of an alcohol amine flocculant synergist, 1% to 5% of an alcohol antioxidant and 55% to 62% of an additive;

[0033] The polymer flocculant is a sulfonated polyacrylamide or polyacrylamide with a molecular weight greater than 20 million;

[0034] The alcoholamine flocculant synergist is one or more of the organic amines of triethylenetetramine, tetraethylenepentamine, and diethylenetriamine;

[0035] The alcohol antioxidant is one or more of ethylene glycol, dipropylene glycol and diethylene glycol;

[0036] The additive is one of soluble chloride salt water, water and acid.

[0037] The role of alcohol amine synergist is to use the intermolecular static electricity between flocculant and alcohol amine to introduce some hydrophobic groups on the flocculant polymer chain, which is beneficial to the separation of oil and water; the role of antioxidant is that wastewater contains a certain amount of dissolved oxygen, and flocculants dissolve and diffuse in wastewater to form a bridge structure, resulting in a very low concentration of flocculants, which are easily oxidized by dissolved oxygen in water. In the preparation of flocculants, alcohol substances that are easily soluble in water are introduced to provide attack points for oxygen in water and protect amino, hydroxyl and other groups of flocculants;

[0038] The larger the molecular weight of the polymer flocculant, the stronger the introduced electrophilic groups, the easier it is to extend in water, and the denser the network structure formed, which is conducive to the flocculant capturing fine particles and colloids, and can allow organic pollutants with very weak electrical properties and fine oil pollution to enter the flocs.

[0039] As a preferred implementation in this embodiment, the molecular weight of the polymer flocculant is 22 million to 25 million.

[0040] When the molecular weight of the polymer flocculant is less than 22 million, the flocculant with a lower molecular weight may not be able to form a sufficiently long chain structure, thereby reducing its ability to capture and aggregate suspended particles;

[0041] Flocculants with lower molecular weight form smaller flocs, which settle more slowly in wastewater, thus prolonging the time required for wastewater treatment;

[0042] Flocculants with lower molecular weight may not be able to effectively adsorb oil, resulting in an increase in the amount of oil residue in the wastewater;

[0043] When the molecular weight of the polymer flocculant is higher than 25 million, the solubility of the flocculant with too high molecular weight in water may deteriorate, making it difficult to disperse evenly during the wastewater treatment process, which may affect the flocculation effect; the flocculant with too high molecular weight may be difficult to completely degrade during the wastewater treatment process, thereby causing secondary pollution in the environment;

[0044] Therefore, the molecular weight of the polymer flocculant is set to 22 million to 25 million, which can effectively capture and aggregate suspended particles and soluble organic matter in the wastewater, and has a good oil adsorption capacity. At the same time, the sedimentation rate is faster, which is beneficial to shorten the wastewater treatment time.

[0045] In summary, the technical effects and advantages of the present invention are as follows:

[0046] The structure of the present invention is reasonable. The process can significantly reduce the concentration of pollutants such as COD and total oil in the alkaline wastewater of copper ore dressing through the technical scheme of "adjusting the pH value of wastewater + iron-carbon micro-electrolysis oxidation-reduction reaction + sodium persulfate advanced oxidation + flocculation precipitation", and solves the problem of low removal efficiency of COD and total oil in the existing copper ore dressing wastewater. It not only effectively reduces the risk of wastewater affecting the environment, but also provides a basis for the effective utilization of the treated wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0048] Figure 1 It is a schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] Example 1

[0051] The COD concentration of the overflow water from the tailings pond of a copper mine is 85 mg / L, the total oil concentration is 3.5 mg / L, and the pH is 7.8. The treatment steps are as follows: S1 introduces the overflow water into the acid adjustment tank, and uses sulfuric acid to adjust the wastewater pH to 4.5. The sulfuric acid concentration used is 35.5%, and the wastewater retention time is 20 minutes. The acid adjustment tank is made of steel-lined rubber; S2 The effluent from the acid adjustment tank enters the iron-carbon micro-electrolytic oxidation-reduction reaction tank. The initial iron-carbon dosage in the reaction tank is determined according to the volume of the reaction tank. The initial iron-carbon dosage is 100 kg / m 3During the treatment process, the continuous supply of iron and carbon is 35kg / h, the wastewater stays in the pool for 2.0h, and the micro-electrolysis reaction pool is made of concrete lined acid-resistant tiles; the effluent of the S3 iron-carbon micro-electrolysis reaction pool enters the sodium persulfate advanced oxidation reaction pool, and sodium persulfate solution is added to the water inlet of the advanced oxidation reaction pool through the dosing pipeline. The concentration of the sodium persulfate solution used is 15%, and the sodium persulfate dosage is determined to be 100g / m according to the wastewater flow rate. 3 The wastewater retention time is 3.0h. The advanced oxidation reaction tank is made of concrete-lined acid-resistant tiles. The effluent from the S4 advanced oxidation reaction enters the alkali adjustment tank, and the composite alkali suspension is added through the dosing pipeline. The dosing point is located at the water inlet to adjust the pH of the wastewater to 9.0. The mixing reaction time of the alkali solution and the wastewater is 15min, and the agitator speed is 60rpm. Then the wastewater after alkali adjustment overflows to the flocculant reaction tank, and the flocculant is dripped into the wastewater from the dosing nozzle. The agitator speed of the flocculation tank is 25rpm, and the wastewater retention time is 10min. The wastewater after flocculation reaction enters the sedimentation tank, and the surface load of the sedimentation tank is 0.55m 3 / (m2·h), the wastewater retention time is 3.0h, the precipitated water can be discharged or reused through the discharge port, and the precipitated underflow is transported to the tailings pond.

[0052] After testing, the concentrations of pollutants in the treated precipitated water were as follows: COD = 10.55 mg / L, total oil = 0.68 mg / L, Cu = 0.065 mg / L, Pb = 0.015 mg / L, As = 0.0025 mg / L, and Mn = 0.0056 mg / L.

[0053] Example 2

[0054] The COD concentration of the overflow water from the tailings pond of a copper mine is 130mg / L, the total oil concentration is 5.3mg / L, and the pH is 6.8. The treatment steps are as follows: S1 introduces the overflow water into the acid adjustment tank, and uses sulfuric acid to adjust the wastewater pH to 5.5. The sulfuric acid concentration used is 25.8%, and the wastewater retention time is 15min. The acid adjustment tank is made of steel-lined rubber; S2 The effluent from the acid adjustment tank enters the iron-carbon micro-electrolysis oxidation-reduction reaction tank. The initial iron-carbon dosage in the reaction tank is determined according to the volume of the reaction tank. The initial iron-carbon dosage is 100kg / m 3 During the treatment process, the continuous supply of iron and carbon is 20kg / h, the wastewater stays in the pool for 1.5h, and the micro-electrolysis reaction pool is made of concrete lined acid-resistant tiles; the effluent of the S3 iron-carbon micro-electrolysis reaction pool enters the sodium persulfate advanced oxidation reaction pool, and sodium persulfate solution is added to the water inlet of the advanced oxidation reaction pool through the dosing pipeline. The concentration of the sodium persulfate solution used is 10%, and the sodium persulfate dosage is determined to be 75g / m according to the wastewater flow rate. 3The wastewater retention time is 2.3h. The advanced oxidation reaction tank is made of concrete-lined acid-resistant tiles. The effluent from the S4 advanced oxidation reaction enters the alkali adjustment tank, and the composite alkali suspension is added through the dosing pipeline. The dosing point is located at the water inlet to adjust the pH of the wastewater to 8.5. The mixing reaction time of the alkali solution and the wastewater is 12min, and the agitator speed is 60rpm. Then the wastewater after alkali adjustment overflows into the flocculant reaction tank, and the flocculant is dripped into the wastewater from the dosing nozzle. The agitator speed of the flocculation tank is 25rpm, and the wastewater retention time is 5min. The wastewater after flocculation reaction enters the sedimentation tank, and the surface load of the sedimentation tank is 0.65m 3 / (m2·h), the wastewater retention time is 2.5h, the precipitated water can be discharged or reused through the discharge port, and the precipitated underflow is transported to the tailings pond.

[0055] After testing, the concentrations of pollutants in the treated precipitated water were as follows: COD = 18.56 mg / L, total oil = 1.52 mg / L, Cu = 0.045 mg / L, Pb = 0.035 mg / L, As = 0.0058 mg / L, Mn = 0.036 mg / L.

[0056] Example 3

[0057] The COD concentration of the overflow water from the tailings pond of a copper mine is 65mg / L, the total oil concentration is 4.5mg / L, and the pH is 6.2. The treatment steps are as follows: S1 introduces the overflow water into the acid adjustment tank, and uses sulfuric acid to adjust the wastewater pH to 4.0. The sulfuric acid concentration used is 15.0%, and the wastewater retention time is 25min. The acid adjustment tank is made of steel-lined rubber; S2 The effluent from the acid adjustment tank enters the iron-carbon micro-electrolytic oxidation-reduction reaction tank. The initial iron-carbon dosage in the reaction tank is determined according to the volume of the reaction tank. The initial iron-carbon dosage is 100kg / m 3 During the treatment process, the continuous supply of iron and carbon is 30kg / h, the wastewater stays in the pool for 2.5h, and the micro-electrolysis reaction pool is made of concrete lined acid-resistant tiles; the effluent of the S3 iron-carbon micro-electrolysis reaction pool enters the sodium persulfate advanced oxidation reaction pool, and sodium persulfate solution is added to the water inlet of the advanced oxidation reaction pool through the dosing pipeline. The concentration of the sodium persulfate solution used is 12%, and the sodium persulfate dosage is determined to be 85g / m according to the wastewater flow rate. 3The wastewater retention time is 3.5h. The advanced oxidation reaction tank is made of concrete-lined acid-resistant tiles. The effluent from the S4 advanced oxidation reaction enters the alkali adjustment tank, and the composite alkali suspension is added through the dosing pipeline. The dosing point is located at the water inlet to adjust the pH of the wastewater to 7.5. The mixing reaction time of the alkali solution and the wastewater is 20min, and the agitator speed is 60rpm. Then the wastewater after alkali adjustment overflows into the flocculant reaction tank, and the flocculant is dripped into the wastewater from the dosing nozzle. The agitator speed of the flocculation tank is 25rpm, and the wastewater retention time is 8min. The wastewater after flocculation reaction enters the sedimentation tank, and the surface load of the sedimentation tank is 0.50m 3 / (m2·h), the wastewater retention time is 3.5h, the precipitated water can be discharged or reused through the discharge port, and the precipitated underflow is transported to the tailings pond.

[0058] After testing, the concentrations of pollutants in the treated precipitated water were as follows: COD = 12.35 mg / L, total oil = 2.44 mg / L, Cu = 0.025 mg / L, Pb = 0.028 mg / L, As = 0.0062 mg / L, Mn = 0.0084 mg / L.

[0059] Example 4

[0060] The COD concentration of the overflow water from the tailings pond of a copper mine is 90mg / L, the total oil concentration is 6.0mg / L, and the pH is 8.5. The treatment steps are as follows: S1 introduces the overflow water into the acid adjustment tank, and uses sulfuric acid to adjust the wastewater pH to 6.0. The sulfuric acid concentration used is 30.0%, and the wastewater retention time is 30min. The acid adjustment tank is made of steel-lined rubber; S2 The effluent from the acid adjustment tank enters the iron-carbon micro-electrolytic oxidation-reduction reaction tank. The initial iron-carbon dosage in the reaction tank is determined according to the volume of the reaction tank. The initial iron-carbon dosage is 100kg / m 3 During the treatment process, the continuous supply of iron and carbon is 15kg / h, the wastewater stays in the pool for 3.0h, and the micro-electrolysis reaction pool is made of concrete lined acid-resistant tiles; the effluent of the S3 iron-carbon micro-electrolysis reaction pool enters the sodium persulfate advanced oxidation reaction pool, and sodium persulfate solution is added to the water inlet of the advanced oxidation reaction pool through the dosing pipeline. The concentration of the sodium persulfate solution used is 15%, and the sodium persulfate dosage is determined to be 45g / m according to the wastewater flow rate. 3The wastewater retention time is 3.5h. The advanced oxidation reaction tank is made of concrete-lined acid-resistant tiles. The effluent from the S4 advanced oxidation reaction enters the alkali adjustment tank, and the composite alkali suspension is added through the dosing pipeline. The dosing point is located at the water inlet to adjust the pH of the wastewater to 7.0. The mixing reaction time of the alkali solution and the wastewater is 25min, and the agitator speed is 60rpm. Then the wastewater after alkali adjustment overflows to the flocculant reaction tank, and the flocculant is dripped into the wastewater from the dosing nozzle. The agitator speed of the flocculation tank is 25rpm, and the wastewater retention time is 20min. The wastewater after flocculation reaction enters the sedimentation tank, and the surface load of the sedimentation tank is 0.50m 3 / (m2·h), the wastewater retention time is 4.0h, the precipitated water can be discharged or reused through the discharge port, and the precipitated underflow is transported to the tailings pond.

[0061] After testing, the concentrations of pollutants in the treated precipitated water were as follows: COD = 36.58 mg / L, total oil = 2.85 mg / L, Cu = 0.076 mg / L, Pb = 0.0083 mg / L, As = 0.0034 mg / L, Mn = 0.015 mg / L.

[0062] Comparative Example 1

[0063] The COD concentration of the overflow water from the tailings pond of a copper mine is 95mg / L, the total oil concentration is 4.2mg / L, and the pH is 7.3. The treatment steps are as follows: S1 introduces the overflow water into the acid adjustment tank, and uses sulfuric acid to adjust the wastewater pH to 4.0. The sulfuric acid concentration used is 98.0%, and the wastewater retention time is 20min. The acid adjustment tank is made of steel-lined rubber; S2 The effluent of the acid adjustment tank enters the ferrous sulfate reaction tank. During the treatment process, the continuous supply of ferrous sulfate is 65kg / h. The wastewater retention time in the tank is 2.0h. The reaction tank is made of concrete-lined acid-resistant tiles; The effluent from the S3 reaction enters the hydrogen peroxide oxidation reaction tank, and the hydrogen peroxide solution is added to the water inlet of the oxidation reaction tank through the dosing pipeline. The concentration of hydrogen peroxide used is 10%. The hydrogen peroxide dosage is determined to be 80kg / h according to the wastewater flow rate. The wastewater retention time is 3.0h. The oxidation reaction tank is made of concrete lined acid-resistant tiles; The effluent from the S4 oxidation reaction enters the alkali adjustment tank, and the lime milk suspension is added through the dosing pipeline. The dosing point is located at the water inlet. The pH of the wastewater is adjusted to 9.0. The mixing reaction time of the alkali solution and the wastewater is 15min, and the agitator speed is 60rpm. Then the wastewater after alkali adjustment overflows to the flocculant reaction tank, and the PAM flocculant (lower molecular weight) is dripped into the wastewater from the dosing pipe. The agitator speed of the flocculation tank is 25rpm, and the wastewater retention time is 10min. The wastewater after flocculation reaction enters the sedimentation tank, and the surface load of the sedimentation tank is 0.53m 3 / (m2·h), the wastewater retention time is 3.0h, the precipitated water can be discharged or reused through the discharge port, and the precipitated underflow is transported to the tailings pond.

[0064] After testing, the concentrations of pollutants in the treated precipitated water were as follows: COD = 145.60 mg / L, total oil = 2.52 mg / L, Cu = 0.35 mg / L, Pb = 0.27 mg / L, As = 0.045 mg / L, and Mn = 0.24 mg / L.

[0065] Comparative Example 2

[0066] The COD concentration of the overflow water from the tailings pond of a copper mine is 75 mg / L, the total oil concentration is 3.7 mg / L, and the pH is 7.8. The treatment steps are as follows: S1 introduces the overflow water into the acid adjustment tank, and uses sulfuric acid to adjust the wastewater pH to 5.2. The sulfuric acid concentration used is 98.0%, and the wastewater retention time is 30 minutes. The acid adjustment tank is made of steel-lined rubber; S2 The effluent from the acid adjustment tank enters the ferrous sulfate reaction tank. During the treatment process, no ferrous sulfate is added. The wastewater stays in the tank for 3.0 hours. The reaction tank is made of concrete-lined acid-resistant tiles; S3 The reaction The effluent after S4 oxidation reaction enters the hydrogen peroxide oxidation reaction tank, and the hydrogen peroxide solution is added to the water inlet of the oxidation reaction tank through the dosing pipeline. The concentration of hydrogen peroxide used is 27%. The hydrogen peroxide dosage is determined to be 15kg / h according to the wastewater flow rate. The wastewater retention time is 4.0h. The oxidation reaction tank is made of concrete lined acid-resistant tiles; the effluent after S4 oxidation reaction enters the alkali adjustment tank, and lime milk suspension is added through the dosing pipeline. The dosing point is located at the water inlet. The pH of the wastewater is adjusted to 8.0. The mixing reaction time of alkali solution and wastewater is 30min, and the agitator speed is 60rpm. Then the wastewater after alkali adjustment overflows to the flocculant reaction tank, and PAM flocculant (lower molecular weight) is dripped into the wastewater from the dosing pipe. The agitator speed of the flocculation tank is 25rpm, and the wastewater retention time is 20min. The wastewater after flocculation reaction enters the sedimentation tank, and the surface load of the sedimentation tank is 0.45m 3 / (m2·h), the wastewater retention time is 4.5h, the precipitated water can be discharged or reused through the discharge port, and the precipitated underflow is transported to the tailings pond.

[0067] After testing, the concentrations of pollutants in the treated precipitated water were as follows: COD = 85.25 mg / L, total oil = 2.80 mg / L, Cu = 0.085 mg / L, Pb = 0.12 mg / L, As = 0.063 mg / L, and Mn = 0.35 mg / L.

[0068] The difference between Comparative Example 1 and the embodiment is that: (1) Comparative Example 1 uses ferrous sulfate as a reducing agent, and the embodiment uses iron carbon as an oxidizing-reducing agent; (2) Comparative Example 1 uses hydrogen peroxide as an oxidant, and the embodiment uses sodium persulfate as an oxidant; (3) Comparative Example 1 uses lime milk as an alkaline agent to adjust the pH of the wastewater, and the embodiment uses a composite alkali as an alkaline agent to adjust the pH of the wastewater; (4) Comparative Example 1 uses an anionic polyacrylamide (PAM) with a relatively low molecular weight (molecular weight of about 15 million), and the embodiment uses a polymer anionic polyacrylamide (PAM). Comparing the treated effluent of Comparative Example 1 with the embodiment, the depth and effect of pollutant treatment are better than those of Comparative Example 1. Therefore, the technical solution of "iron carbon micro-electrolytic oxidation-reaction + sodium peroxide advanced oxidation + composite alkali adjustment + polymer flocculant flocculation" adopted in this application is more superior.

[0069] The difference between Comparative Example 2 and Comparative Example 1 is that: Comparative Example 2 does not add ferrous sulfate as a reducing agent, and the increase in the COD concentration of the effluent after the treatment of Comparative Example 2 is small.

[0070] The above two comparative examples both have the problem that the COD concentration of the treated effluent is higher than the COD concentration of the influent, which is a defect of the comparative examples because the excessive hydrogen peroxide and ferrous iron react with potassium dichromate during the determination process, consuming potassium dichromate, thereby affecting the determination of COD.

[0071] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for improving the removal efficiency of COD and total oil in overflow water from a copper mine tailings pond, characterized in that: The steps include: S1: Use acidic reagents to adjust the pH of copper ore copper beneficiation alkaline wastewater to 4.5-5.5; S2: The wastewater after pH adjustment enters the iron-carbon micro-electrolysis reaction tank to achieve chain-breaking degradation of organic matter in the ring-chain or long-chain mineral processing reagents in the wastewater, and decompose the macromolecular pollutants into small molecular organic matter that is easy to remove; S3: The wastewater after the iron-carbon micro-electrolysis reaction enters the sodium persulfate advanced oxidation reaction tank. The Fe2+ produced by the micro-electrolysis and the added sodium persulfate produce highly active SO4- ions, which synergistically degrade organic pollutants in the wastewater under weakly acidic conditions. At the same time, part of the Fe2+ is oxidized to Fe3+, forming Fe(OH)3 colloids that can adsorb or aggregate fine particles; S4: The wastewater after advanced oxidation treatment enters the neutralization reaction tank, and the pH value of the wastewater is adjusted to 8-9 with alkaline agents to fully react. Then, a modified polymer anion flocculant solution is added to allow the suspended matter, colloids and other fine particles in the wastewater to fully react with the flocculant. Finally, the wastewater is allowed to stand to achieve solid-liquid separation. The supernatant can be directly discharged or returned for utilization, and the underflow can be mixed with the tailings for treatment or utilization.

2. The method for improving the COD and total oil removal efficiency in the overflow water of the copper mine tailings pond according to claim 1, characterized in that: In the step S1, the acidic agent is sulfuric acid, and the concentration of the sulfuric acid is 15% to 45%.

3. The method for improving the COD and total oil removal efficiency in the overflow water of the copper mine tailings pond according to claim 1, characterized in that: In S2, the iron carbon is in the form of tiny particles with a particle size of 1 to 10 mm, and the composition of the iron carbon is: iron content = 65% to 85%, carbon content = 15% to 35%.

4. The method for improving the COD and total oil removal efficiency in the overflow water of the copper mine tailings pond according to claim 1, characterized in that: In S2, the iron-carbon micro-electrolysis reaction cell includes a first trough body and a second trough body, the first trough body is an oxidation-reduction reaction area, the second trough body is a wastewater and iron-carbon powder separation area, the stirring device of the first trough body adopts a plate and frame stirrer with a rotation speed of 15 to 30 rpm, and the surface load rate of the sedimentation area of ​​the second trough body is 1.15 to 1.25 m3 / (㎡˙h). The bottom flow generated in the sedimentation area of ​​the second trough body directly returns to the first trough body to achieve full utilization of iron and carbon.

5. The method for improving the COD and total oil removal efficiency in the overflow water of the copper mine tailings pond according to claim 1, characterized in that: In S3, the concentration of the sodium persulfate solution is 10% to 15%, the amount of sodium persulfate used is 50 to 100 g / m3, and the oxidation reaction residence time is 2 to 4 hours.

6. The method for improving the removal efficiency of COD and total oil in overflow water of a copper mine tailings pond according to claim 1, characterized in that: The alkaline agent is a composite alkaline solution with a concentration of 20% to 30%.

7. The method for improving the removal efficiency of COD and total oil in overflow water of a copper mine tailings pond according to claim 1, characterized in that: In S4, the modified polymer anionic flocculant is a sulfonic acid modified polymer anionic polyacrylamide, with a concentration of 0.02% to 0.05% and a usage amount of 4 to 10 g / m3.

8. A modified polymer anionic flocculant used in a method for improving the removal efficiency of COD and total oil in overflow water from a copper mine tailings pond, characterized in that: The ingredients include 35% to 45% of a high molecular weight flocculant with a molecular weight greater than 20 million, 2% to 5% of an alcohol amine flocculant synergist, 1% to 5% of an alcohol antioxidant and 55% to 62% of an additive; The polymer flocculant is a sulfonated polyacrylamide or polyacrylamide with a molecular weight greater than 20 million; The alcoholamine flocculant synergist is one or more of the organic amines of triethylenetetramine, tetraethylenepentamine, and diethylenetriamine; The alcohol antioxidant is one or more of ethylene glycol, dipropylene glycol and diethylene glycol; The additive is one of soluble chloride salt water, water and acid.

9. The method for improving the removal efficiency of COD and total oil in overflow water of a copper mine tailings pond according to claim 5, characterized in that: The molecular weight of the polymer flocculant is 22 million to 25 million.

Images