A method for removing hydroxyxamic acid from flotation wastewater containing hydroxyxamic acid compounds

Abstract

This invention provides a method for removing hydroxyxamic acid from flotation wastewater containing hydroxyxamic acid compounds, relating to the field of wastewater treatment technology. The method includes: S1, adjusting the pH of the hydroxyxamic acid-containing flotation wastewater to 5.5-7, and then adding a long-chain quaternary ammonium salt while stirring to obtain wastewater containing yellowish-brown flocculent matter; wherein the mass ratio of the quaternary ammonium salt to the hydroxyxamic acid in the wastewater is 1-6:1; S2, using an air flotation device to perform air flotation separation on the wastewater containing the yellowish-brown flocculent matter to remove the flocculent matter. The method provided by this invention effectively treats flotation wastewater containing hydroxyxamic acid compounds by utilizing the interaction between the long-chain quaternary ammonium salt and hydroxyxamic acid. This method features high treatment efficiency, simple process, and low cost.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a method for removing hydroxyxamic acid from flotation wastewater containing hydroxyxamic acid compounds. Background Technology

[0002] Since the processing of fine-grained products is crucial in rare earth flotation, and these products are difficult to process because when the grinding particle size is too fine, the fine slime and gangue have similar properties and are difficult to separate. Therefore, the selection of collectors is particularly important. In existing technologies, because the flotation characteristics of bastnaesite are similar to those of calcium-bearing minerals, sodium oleate and other similar collectors were often used in early flotation processes. However, sodium oleate has poor separation performance, low flotation efficiency, high collector consumption, and high cost.

[0003] Researchers have found that, compared to sodium oleate, using hydroxamic acid as a flotation agent offers advantages such as lower cost, lower agent consumption, and improved flotation efficiency. Hydroxamic acid exists in isomers (see formula below) and is a class of chelating collectors with highly efficient collecting properties for cations in metal oxide ores. It has already been used in the beneficiation of some oxide ores, such as tungsten-molybdenum ores, rare earth ores, and non-ferrous metal ores. These minerals require the use of hydroxamic acid as a collector due to their low flotation efficiency, high collector consumption, and high cost. Therefore, in existing technologies, chelating collectors such as hydroxamic acid, which have a high efficiency in collecting cations of metal oxide ores, are widely used in the beneficiation of some oxide ores such as tungsten-molybdenum ores, rare earth ores, and non-ferrous metal ores. For example, modified hydroxamic acid is used as a collector for the flotation of rare earth in the beneficiation of rare earth fluorocarbon cerium ore in Mianning, Sichuan. In the early flotation of rare earth fluorocarbon cerium ore in Weishan, Shandong, sodium oleate and other collectors were often used, but the separation index was poor. Later, by drawing on foreign beneficiation reagent systems, salicylhydroxamic acid was introduced as a collector, which greatly improved the separation effect.

[0004]

[0005] Hydroxyxamic acids' strong collecting properties facilitate mineral beneficiation. However, to obtain more valuable minerals, higher levels of hydroxyxamic acid reagents are often added during beneficiation processes, leading to widespread overuse. Furthermore, hydroxyxamic acids exhibit good chemical stability and are difficult to degrade naturally. When beneficiation wastewater is reused, the accumulation of these residues often disrupts the normal operation of the beneficiation process. If this residual hydroxyxamic acid wastewater is discharged into natural water bodies, it can cause color changes, foul odors, and eutrophication, even leading to the death of aquatic and nearby flora and fauna. Specifically, in wastewater treated by hydroxyxamic acid flotation, hydroxyxamic acid can react with Fe in the slurry. 3+A chelation reaction occurs, forming a soluble, blood-red iron hydroxamic acid complex, which causes the water to darken in color. In addition, untreated hydroxamic acid agents, which are biologically toxic, highly corrosive, and difficult to degrade, can seep into groundwater and cause large-scale irreversible environmental pollution as they flow with the groundwater, making subsequent environmental pollution control much more difficult.

[0006] Currently, commonly used methods for treating mineral processing wastewater in China include natural degradation, coagulation and sedimentation, neutralization, adsorption, and biological methods. Because the wastewater containing hydroxamic acid flotation reagents contains hydroxamic acid, which is biotoxic, highly corrosive, has high solution density, and is difficult to degrade, in order to meet the discharge or reuse standards of mineral processing wastewater and avoid impacting the ecological environment, the following oxidation methods are usually used for treatment: (1) O3 oxidation technology degrades organic pollutants by generating hydroxyl radicals with high redox potential through reaction. It has obvious advantages, and the reaction of hydroxyl radicals is a free radical reaction, which greatly shortens the reaction time and can achieve the purpose of high mineralization rate and harmlessness of difficult-to-degrade organic matter. When ozone oxidation is used, the removal rate of salicylic acid reaches 93.94% after 15 minutes of ozone oxidation degradation reaction. However, the operating cost of ozone oxidation device is high, and its application is limited; (2) In actual production, there is also a process of using Fenton method to degrade salicylic acid mineral processing wastewater, such as the mineral processing wastewater of Weishan rare earth mine, which uses Fenton method to degrade mineral processing wastewater containing salicylic acid. Water, but it requires sulfuric acid to adjust the pH value to 2.5-3, and then hydrogen peroxide is used for oxidation. The Fenton method will generate a large amount of hazardous solid waste. Because the introduction of sulfuric acid to adjust the pH value also leads to an increase in the salt content of the wastewater, after the salicylic acid in the wastewater is degraded, the salt in the wastewater also needs to be treated, which increases the workload of treatment; (3) A study has explored the effect of microwave-activated persulfate on the degradation of hydroxamic acid. The study found that the mineralization rate of hydroxamic acid after 180 minutes of degradation reaction was 45.22%. Since microwaves were used in the degradation process, this method is only suitable for small-scale use and cannot be used for large-scale degradation; (4) Another study used TiO2 photocatalytic material to degrade hydroxamic acid collectors in water (Metal Mines, 2011, 3, 147-151). The degradation and decolorization rate of hydroxamic acid by TiO2 photocatalysis for 3 hours can reach 95%, but the cost is very high due to the use of photocatalysis. Most of the oxidation methods described above suffer from high equipment maintenance costs, high treatment costs, and the generation of large amounts of additional solid waste. Therefore, there is a need to develop a method for the large-scale treatment of mineral processing wastewater containing hydroxyxamic acid compounds that has a high hydroxyxamic acid removal rate, low cost, and generates no large amounts of additional solid waste or even hazardous waste. Summary of the Invention

[0007] To address the above problems, this invention provides a method for removing hydroxyxamic acid from flotation wastewater containing hydroxyxamic acid compounds, the method comprising:

[0008] S1, after adjusting the pH of the flotation wastewater containing hydroxamic acid compounds to 5.5-7, a quaternary ammonium salt containing long-chain molecules is added under stirring to obtain wastewater containing yellowish-brown flocculent matter; wherein, the mass ratio of the amount of quaternary ammonium salt added to the mass of hydroxamic acid in the flotation wastewater containing hydroxamic acid compounds is 1-6:1.

[0009] S2, The wastewater containing yellowish-brown flocculent matter is separated by air flotation using an air flotation device to remove the yellowish-brown flocculent matter.

[0010] Preferably, the quaternary ammonium salt is one or more of hexadecyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium chloride (DTAC), octadecyltrimethylammonium chloride, and dioctadecyldimethylammonium chloride.

[0011] Preferably, the mass ratio of the amount of quaternary ammonium salt added to the mass of hydroxamic acid content in the flotation wastewater containing hydroxamic acid compounds is 1 to 2:1.

[0012] Preferably, the hydroxamic acid-containing compound includes at least one of salicylic acid, alkyl hydroxamic acid, benzoic acid, and isohydroxamic acid.

[0013] Preferably, the flotation wastewater containing hydroxyoxime compounds is the wastewater after the flotation of fluorocarbon cerium ore.

[0014] Preferably, after step S2, the method further includes:

[0015] The underflow wastewater obtained by removing the hydroxamic acid is introduced into a coagulation reaction tank. Coagulant and flocculant are added sequentially under stirring to carry out the coagulation reaction and obtain coagulated wastewater.

[0016] The coagulated wastewater enters a sedimentation tank for static settling. The resulting supernatant is pumped into a biochemical treatment system, where zeolite is added to further remove COD and total nitrogen. The wastewater obtained after removal is returned to the original mineral processing flow for recycling or discharged in compliance with standards.

[0017] Preferably, the coagulant is an inorganic polymer, and the amount of coagulant added is 3 g / m³. 3 ~15g / m 3 .

[0018] Preferably, the flocculant is polyacrylamide, and the amount of flocculant added is 1 g / m³. 3 ~4g / m 3 .

[0019] Preferably, the settling time is 30 min to 180 min.

[0020] Preferably, the amount of zeolite added is 10 g / L to 20 g / L.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] This invention provides a method for removing hydroxyxamic acid from flotation wastewater containing hydroxyxamic acid compounds, relating to the field of wastewater treatment technology. The method includes: S1, adjusting the pH of the hydroxyxamic acid-containing flotation wastewater to 5.5-7, and then adding a long-chain quaternary ammonium salt while stirring to obtain wastewater containing yellowish-brown flocculent matter; wherein the mass ratio of the quaternary ammonium salt to the hydroxyxamic acid in the wastewater is 1-6:1; S2, using an air flotation device to perform air flotation separation on the wastewater containing the yellowish-brown flocculent matter to remove the flocculent matter. The method provided by this invention effectively treats flotation wastewater containing hydroxyxamic acid compounds by utilizing the interaction between the long-chain quaternary ammonium salt and hydroxyxamic acid. This method features high treatment efficiency, simple process, and low cost.

[0023] In this embodiment of the invention, a quaternary ammonium salt reagent containing long-chain molecules is added under conditions of pH 5.5–7. The four-membered rings formed by the hydroxamic acid itself in the flotation wastewater containing hydroxamic acids collide with the long-chain molecules in the quaternary ammonium salt, rapidly forming loose, yellowish-brown flocs. Then, a simple and convenient air flotation device is used for separation, effectively removing more than 90% of the hydroxamic acid from the flotation wastewater. Furthermore, the method provided by this invention has advantages such as simple process, rapid reaction, low equipment installation requirements for the hydroxamic acid reaction, small footprint, and low infrastructure cost. Since the method provided by this invention does not require the use of costly, highly oxidizing, corrosive, flammable, explosive, or toxic oxidizing agents for pre-oxidation and decomposition treatment, it features lower management costs and safety risks, weak corrosiveness of the reagent medium, low cost, no hazardous solid waste generation, and the ability to treat hydroxamic acid wastewater on a large scale. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application 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 only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart illustrating the steps of a method for removing hydroxyxamic acid from flotation wastewater containing hydroxyxamic acid compounds, as described in this embodiment of the invention.

[0026] Figure 2 This is a flowchart illustrating the steps for removing COD and total nitrogen from flotation wastewater containing hydroxamic acid compounds in an embodiment of the present invention.

[0027] Figure 3This is a flowchart of the method in Embodiment 1 of the present invention. Detailed Implementation

[0028] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0029] Specific experimental steps or conditions are not specified in the embodiments; they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products. Furthermore, the accompanying drawings are merely illustrative diagrams of the embodiments of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0030] This invention provides a method for treating flotation wastewater containing hydroxyoxime acids, such as... Figure 1 As shown, the method includes:

[0031] S1, after adjusting the pH of the flotation wastewater containing hydroxamic acid compounds to 5.5-7, a quaternary ammonium salt containing long-chain molecules is added under stirring to obtain wastewater containing yellowish-brown flocculent matter; wherein, the mass ratio of the amount of quaternary ammonium salt added to the mass of hydroxamic acid in the flotation wastewater containing hydroxamic acid compounds is 1-6:1.

[0032] The time for step S1 is 30 min to 60 min;

[0033] Because a large amount of hydroxamic acid beneficiation reagents are added during the mineral processing to obtain more valuable minerals, the flotation wastewater containing hydroxamic acid compounds in this embodiment contains a large amount of hydroxamic acid and chemical oxygen demand. This type of wastewater is one of the most difficult wastewaters to treat in mineral processing enterprises. In addition, the flotation wastewater containing hydroxamic acid compounds in this embodiment can also be any water body containing hydroxamic acid, such as surface water containing hydroxamic acid.

[0034] The yellowish-brown flocculent material is a complex formed by quaternary ammonium salts and hydroxamic acid compounds in this embodiment.

[0035] In this embodiment, the pH of the flotation wastewater containing hydroxamic acid compounds is adjusted to 5.5–7. The four-membered rings formed by the hydroxamic acid itself in the wastewater collide with the long-chain molecules in the quaternary ammonium salt. Certain groups in the quaternary ammonium salt molecules adsorb onto the hydroxamic acid or its rings, rapidly forming loose, yellowish-brown flocs at this pH. It should also be noted that the pH of the flotation wastewater containing hydroxamic acid compounds cannot be adjusted to 2–5. At pH values ​​of 2–5, the formation of yellowish-brown flocs is not conducive, and the removal of hydroxamic acid compounds cannot be effectively achieved. Furthermore, the added quaternary ammonium salt also achieves decolorization. Quaternary ammonium salt has a high efficiency in collecting cations from metal oxide ores. By providing a large number of cations, it neutralizes and destabilizes the negative charges attached to the chromophore molecules in the wastewater, causing the chromophore molecules to adsorb onto the flocs, thereby achieving decolorization.

[0036] Specifically, dilute sulfuric acid can be used to adjust the pH value of flotation wastewater containing hydroxyoxime compounds.

[0037] S2, The wastewater containing yellowish-brown flocculent matter is separated by air flotation using an air flotation device to remove the yellowish-brown flocculent matter.

[0038] Among them, the air flotation equipment is a special air flotation equipment for water treatment or a flotation machine and flotation column for mining.

[0039] In this embodiment, an air flotation device is used to conveniently separate the yellowish-brown flocculent matter from the wastewater. For example, the depth of the flotation wastewater containing hydroxamic acid compounds is h. By using air flotation, the yellowish-brown flocculent matter floats to the surface and aggregates to a thickness of 1 / 10h. By scraping off the floating yellowish-brown flocculent matter, the hydroxamic acid compounds in the wastewater can be removed. If an air flotation device is not used for air flotation separation, the yellowish-brown flocculent matter will be dispersed in the flotation wastewater containing hydroxamic acid compounds, making the wastewater more turbid and difficult to remove.

[0040] In this embodiment of the invention, a quaternary ammonium salt reagent containing long-chain molecules is added under conditions of pH 5.5–7. The four-membered rings formed by the hydroxamic acid itself in the flotation wastewater containing hydroxamic acids collide with the long-chain molecules in the quaternary ammonium salt, rapidly forming loose, yellowish-brown flocs. Then, a simple and convenient air flotation device is used for separation, effectively removing more than 90% of the hydroxamic acid from the flotation wastewater. Furthermore, the method provided by this invention has advantages such as simple process, rapid reaction, low equipment installation requirements for the hydroxamic acid reaction, small footprint, and low infrastructure cost. Since the method provided by this invention does not require the use of costly, highly oxidizing, corrosive, flammable, explosive, or toxic oxidizing agents for pre-oxidation and decomposition treatment, it features lower management costs and safety risks, weak corrosiveness of the reagent medium, low cost, no hazardous solid waste generation, and the ability to treat hydroxamic acid wastewater on a large scale.

[0041] Preferably, the quaternary ammonium salt with long-chain molecules is one or more of hexadecyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium chloride (DTAC), octadecyltrimethylammonium chloride, and dioctadecyldimethylammonium chloride.

[0042] By adding quaternary ammonium salt reagents, more than 90% of hydroxamic acid in flotation wastewater containing hydroxamic acid compounds can be effectively removed. In this embodiment, the larger the number of carbon atoms in the main chain of the quaternary ammonium salt, the better the removal effect on hydroxamic acid. Therefore, the preferred quaternary ammonium salt is one or more of hexadecyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium chloride (DTAC), octadecyltrimethylammonium chloride, and dioctadecyldimethylammonium chloride. It should also be noted that the quaternary ammonium salt in this embodiment cannot be a polyquaternary ammonium salt or a quaternary ammonium salt containing an acryloyloxy group, as these two types of quaternary ammonium salts do not have long-chain molecules, such as acryloyloxy2-hydroxypropyltrimethylammonium chloride, acryloyloxybutyltrimethylammonium chloride, methacryloyloxybutyltrimethylammonium chloride, methacryloyloxypentyltrimethylammonium chloride, or dimethyldipropenylammonium chloride, etc.

[0043] Preferably, the mass ratio of the amount of quaternary ammonium salt added to the mass of hydroxamic acid content in the flotation wastewater containing hydroxamic acid compounds is 1 to 2:1.

[0044] In this embodiment, a certain concentration of quaternary ammonium salt can collide with the hydroxamic acid or residual hydroxamic acid four-membered ring and long-chain molecules in the quaternary ammonium salt in the flotation wastewater containing hydroxamic acid compounds, forming bridging material at this pH value, thereby forming loose flocs, i.e., yellowish-brown flocs, to better achieve the purpose of effectively removing hydroxamic acid from the flotation wastewater containing hydroxamic acid compounds, thereby reducing COD and total nitrogen in the wastewater.

[0045] In practical applications, if large-scale treatment of flotation wastewater containing hydroxamic acid compounds is required, the dosage of quaternary ammonium salt can be appropriately increased. However, the ratio of the two needs to be considered to avoid exceeding the total nitrogen standard due to residual quaternary ammonium salt.

[0046] Preferably, the flotation wastewater containing hydroxyoxime compounds is flotation wastewater from fluorocarbon cerium ore.

[0047] In this embodiment, the flotation wastewater containing hydroxamic acid compounds is further preferably fluorocarbon cerium ore flotation wastewater. Fluorocarbon cerium ore flotation wastewater contains rare earth metals, which can more effectively remove hydroxamic acid from the rare earth fluorocarbon cerium ore flotation wastewater and improve the removal rate of hydroxamic acid.

[0048] When the wastewater to be treated is rare earth fluorocarbon cerium ore flotation wastewater, which contains rare earth metals, the hydroxamic acid in the wastewater forms a five-membered ring with the rare earth metals, which is more stable and easier to form than a four-membered ring. This five-membered ring collides with the long-chain molecules of quaternary ammonium salt, and the groups in the long-chain molecules (compared to the four-membered ring) are more quickly adsorbed onto the five-membered ring to rapidly form a yellowish-brown flocculent substance to remove the hydroxamic acid from the wastewater. At the same time, the residual hydroxamic acid in the wastewater that has not formed a five-membered ring forms four-membered rings with each other. This four-membered ring collides with the long-chain molecules of quaternary ammonium salt, and the groups in the long-chain molecules are adsorbed onto the four-membered ring to rapidly form a yellowish-brown flocculent substance to remove the hydroxamic acid from the wastewater. Therefore, when the wastewater to be treated is rare earth fluorocarbon cerium ore flotation wastewater, adding quaternary ammonium salt reagents with long-chain molecules to this type of wastewater under pH conditions of 5.5 to 7 can improve the removal rate of hydroxamic acid and more effectively remove hydroxamic acid from this type of wastewater.

[0049] Preferably, after step S2, such as Figure 2 As shown, the method further includes:

[0050] S3, the underflow wastewater obtained by removing the hydroxamic acid is introduced into the coagulation reaction tank, and coagulant and flocculant are added in sequence under stirring to carry out the coagulation reaction and obtain coagulated wastewater;

[0051] S4, the coagulated wastewater enters the sedimentation tank for static settling, and the resulting supernatant is pumped into the biochemical treatment system and zeolite is added to further remove COD and total nitrogen. The wastewater obtained after removal is returned to the original mineral processing flow for recycling or discharged in compliance with standards.

[0052] In this embodiment, steps S3 and S4 are used for deep removal of COD and total nitrogen to further ensure that the obtained wastewater can be recycled or discharged in compliance with standards: step S3 is used to remove COD from the underflow wastewater to obtain coagulated wastewater; step S4 is used to deeply remove COD and total nitrogen from the supernatant so that the wastewater with completely removed COD and total nitrogen can be recycled or discharged in compliance with standards.

[0053] After completing steps S1 and S2, the hydroxamic acid compounds in the flotation wastewater are removed. Then, by completing steps S3 and S4, COD and total nitrogen in the wastewater are removed, allowing the wastewater to be recycled back into the original mineral processing flow or discharged in compliance with standards. Since the hydroxamic acid compounds in the flotation wastewater have been removed in steps S1 and S2, adding coagulants and flocculants to the underflow wastewater for coagulation and biochemical treatment at this point can easily precipitate the COD, thus better removing COD and total nitrogen.

[0054] The biochemical treatment system includes an anaerobic unit, a secondary MBBR treatment unit, a secondary sedimentation tank, a secondary BAF treatment unit, ozone oxidation, deep defluorination, and a clear water tank process.

[0055] Preferably, the coagulant is an inorganic polymer, and the amount of coagulant added is 3 g / m³. 3 ~15g / m 3 .

[0056] In this embodiment, the inorganic polymer is polyaluminum or aluminum chloride.

[0057] Preferably, the flocculant is polyacrylamide, and the amount of flocculant added is 1 g / m³. 3 ~4g / m 3 .

[0058] Preferably, the settling time is 30 min to 180 min.

[0059] Preferably, the amount of zeolite added is 10 g / L to 20 g / L.

[0060] To enable those skilled in the art to better understand the present invention, the preparation method provided by the present invention will be described below through several specific embodiments.

[0061] Example 1

[0062] The wastewater containing salicylic acid after flotation of fluorocarbon cerium ore in Weishan Lake, Shandong Province, has a pH of 7, a COD content of 283.5 mg / L, and a total nitrogen content of 74.7 mg / L.

[0063] Reference Figure 3 , Figure 3 This is a flowchart of the method in Example 1.

[0064] In the pretreatment reaction tank, the pH value of the wastewater was monitored online using a pH meter. Dilute sulfuric acid was added during stirring to adjust the pH value to 5.5. Under mixed conditions, cetyltrimethylammonium bromide was added to the flotation wastewater at a ratio of 2:1 in a flotation column, resulting in wastewater containing yellowish-brown flocculent matter. Air flotation separation was then performed, and the floating yellowish-brown flocculent matter was scraped off. The removal rate of salicylic acid was 93%, and the removal rates of COD and total nitrogen in the wastewater were 85.3% and 72.1%, respectively.

[0065] The remaining underflow wastewater from the air flotation separation is introduced into the coagulation reaction tank, and mixed with water at a concentration of 4 g / m³ under stirring. 3 coagulant and 2mg / m 3 Flocculant is added to obtain coagulated wastewater.

[0066] After coagulation, the wastewater is allowed to settle to obtain supernatant, which is then pumped into a biochemical treatment system to remove COD and total nitrogen. The COD and total nitrogen in the wastewater are 26.4 mg / L and 12.7 mg / L, respectively (the emission standards for pollutants in the rare earth industry are 70 mg / L for COD and 30 mg / L for total nitrogen). Therefore, the obtained wastewater can be returned to the original mineral processing flow for recycling or discharged in compliance with standards.

[0067] Example 2

[0068] The flotation wastewater from the fluorocarbon cerium mine in Mianning, Sichuan Province, was selected. The pH value was 10, the COD content was 353.4 mg / L, and the total nitrogen content was 96.3 mg / L.

[0069] In the pretreatment reaction tank, the pH value of the wastewater was monitored online using a pH meter. Dilute sulfuric acid was slowly added during stirring to adjust the pH value to 6.1. While stirring, octadecyltrimethylammonium chloride was added to the flotation wastewater containing hydroxamic acid compounds at a 1:1 ratio, resulting in wastewater containing yellowish-brown flocculent matter.

[0070] Wastewater containing yellowish-brown flocculent hydroxyoxime compounds was transferred to a dedicated wastewater flotation unit for flotation separation to remove the yellowish-brown flocculent precipitate and thus remove the hydroxyoxime compounds from the wastewater. The removal rate of hydroxyoxime compounds was 91%, while the removal rates of COD and total nitrogen in the wastewater were 83.6% and 70.3%, respectively.

[0071] The remaining underflow wastewater from the air flotation separation is introduced into the coagulation reaction tank, and 3g / m³ of additives are added sequentially under stirring. 3 coagulant and 3mg / m 3 The flocculant undergoes a coagulation reaction to remove COD from the underflow wastewater, resulting in coagulated wastewater.

[0072] The coagulated wastewater is sent to a sedimentation tank for settling for 120 minutes to obtain supernatant (underflow wastewater with most of the COD removed). The supernatant is then pumped into a biochemical treatment system and 18 g / L of natural zeolite powder is added to completely remove COD and total nitrogen from the supernatant. The resulting wastewater has a COD content of 32.8 mg / L and a total nitrogen content of 14.1 mg / L. Therefore, the resulting wastewater can be returned to the original mineral processing flow for recycling or discharged in compliance with standards.

[0073] Example 3

[0074] The flotation wastewater from a nickel-cobalt mine in Qinghai Province was selected. The pH value was 8.3, the COD content was 297.8 mg / L, and the total nitrogen content was 17.3 mg / L.

[0075] In the pretreatment reaction tank, the pH value of the wastewater was monitored online using a pH meter. Dilute sulfuric acid was slowly added during stirring to adjust the pH value of the wastewater to 6.5. Under stirring, octadecyltrimethylammonium chloride was added to the flotation wastewater containing hydroxamic acid compounds at a dosage of 1.5:1, resulting in wastewater containing yellowish-brown flocculent matter.

[0076] Wastewater containing yellowish-brown flocculent hydroxyxamic acid compounds was transferred to a dedicated wastewater flotation unit for flotation separation to remove the yellowish-brown flocculent precipitate and thus remove the hydroxyxamic acid from the wastewater. The removal rate of hydroxyxamic acid was 94%, and the removal rates of COD and total nitrogen in the wastewater were 85.6% and 72.5%, respectively.

[0077] The remaining underflow wastewater from the air flotation separation is introduced into the coagulation reaction tank, and 3g / m³ of additives are added sequentially under stirring. 3 coagulant and 3mg / m 3 The flocculant undergoes a coagulation reaction to remove COD from the underflow wastewater, resulting in coagulated wastewater.

[0078] After coagulation, the wastewater is sent to a sedimentation tank for settling for 120 minutes to obtain supernatant (underflow wastewater with most of the COD removed). The supernatant is then pumped into a biochemical treatment system and 18 g / L of natural zeolite powder is added to completely remove COD and total nitrogen from the supernatant. The resulting wastewater has a COD content of 28.1 mg / L and a total nitrogen content of 5.6 mg / L (the first-level discharge standard for industrial wastewater is 100 mg / L for COD and 10 mg / L for total nitrogen). Therefore, the treated wastewater can be returned to the original mineral processing flow for recycling or discharged in compliance with standards.

[0079] In this embodiment, flotation wastewater from a nickel-cobalt mine in Qinghai Province was selected. Since the nickel-cobalt mine in Qinghai Province does not contain rare earth metals, the dosage of hydroxamic acid reagent used in the flotation of the mine is relatively small. Therefore, the method provided by this invention can easily remove hydroxamic acid from the flotation wastewater, with a removal rate of up to 94%.

[0080] Example 4

[0081] The flotation wastewater from the fluorocarbon cerium mine in Mianning, Sichuan Province, was selected. The pH value was 10, the COD content was 353.4 mg / L, and the total nitrogen content was 96.3 mg / L.

[0082] In the pretreatment reaction tank, the pH value of the wastewater was monitored online using a pH meter. Dilute sulfuric acid was slowly added during stirring to adjust the pH value to 7. Under stirring, octadecyltrimethylammonium chloride was added to the flotation wastewater containing hydroxamic acid compounds at a dosage of 6:1, resulting in wastewater containing yellowish-brown flocculent matter.

[0083] Wastewater containing yellowish-brown flocculent hydroxyxamic acid compounds was transferred to a dedicated wastewater flotation unit for flotation separation to remove the yellowish-brown flocculent precipitate and thus remove the hydroxyxamic acid from the wastewater. The removal rate of hydroxyxamic acid was 93%, and the removal rates of COD and total nitrogen in the wastewater were 95.1% and 83.6%, respectively.

[0084] The remaining underflow wastewater from the air flotation separation is introduced into the coagulation reaction tank, and 3g / m³ of additives are added sequentially under stirring. 3 coagulant and 3mg / m 3 The flocculant undergoes a coagulation reaction to remove COD from the underflow wastewater, resulting in coagulated wastewater.

[0085] After coagulation, the wastewater is sent to a sedimentation tank for settling for 120 minutes to obtain supernatant (underflow wastewater with most of the COD removed). The supernatant is then pumped into a biochemical treatment system and 18 g / L of natural zeolite powder is added to completely remove COD and total nitrogen from the supernatant. The resulting wastewater has a COD content of 20.5 mg / L and a total nitrogen content of 10.7 mg / L. Therefore, the treated wastewater can be returned to the original mineral processing flow for recycling or discharged in compliance with standards.

[0086] Comparative Example 1

[0087] This comparative example is the comparative example of Example 1.

[0088] The wastewater containing salicylic acid after flotation of fluorocarbon cerium ore in Weishan Lake, Shandong Province, has a pH of 7, a COD content of 283.5 mg / L, and a total nitrogen content of 74.7 mg / L.

[0089] Wastewater containing hydroxyoxime compounds from flotation was introduced into a coagulation reaction tank, and 4 g / m³ of additives were added sequentially under stirring. 3 coagulant and 2mg / m 3 The flocculant undergoes a coagulation reaction to remove COD from flotation wastewater containing hydroxamic acid compounds, resulting in coagulated wastewater.

[0090] The coagulated wastewater was sent to a sedimentation tank for settling for 120 minutes to obtain supernatant (flotation wastewater containing hydroxamic acid compounds with most of the COD removed). The supernatant was then pumped into a biochemical treatment system to remove COD and total nitrogen. The resulting wastewater had a COD content of 216.2 mg / L and a total nitrogen content of 70.1 mg / L. Therefore, the resulting wastewater could not be recycled back to the original mineral processing flow or discharged in compliance with standards.

[0091] Comparative Example 2

[0092] This comparative example is the comparative example of Example 2.

[0093] Wastewater containing modified hydroxamic acid from the flotation of fluorocarbon cerium ore in Mianning, Sichuan Province, has a pH of 7, a COD content of 353.4 mg / L, and a total nitrogen content of 96.3 mg / L.

[0094] Wastewater containing hydroxyoxime compounds from flotation was introduced into a coagulation reaction tank, and 3 g / m³ of additives were added sequentially under stirring. 3 coagulant and 3mg / m 3 The flocculant undergoes a coagulation reaction to remove COD from flotation wastewater containing hydroxamic acid compounds, resulting in coagulated wastewater.

[0095] The coagulated wastewater was sent to a sedimentation tank for settling for 120 minutes to obtain supernatant (underflow wastewater with most of the COD removed). The supernatant was then pumped into a biochemical treatment system and 15 g / L of natural zeolite powder was added to remove COD, ammonia nitrogen, and total nitrogen from the supernatant. The resulting wastewater had a COD content of 315.5 mg / L and a total nitrogen content of 69.5 mg / L. Therefore, the resulting wastewater could not be recycled back to the original mineral processing flow or discharged in compliance with standards.

[0096] Comparative Examples 1 and 2 employed conventional COD removal methods—utilizing flocculation to remove COD from wastewater. Compared to Examples 1 and 2, the comparative examples showed poorer COD and nitrogen removal effects. This is because the methods provided in the examples first remove most of the hydroxamic acid from the wastewater, which further enhances the subsequent COD and total nitrogen removal effects, allowing the resulting wastewater to be recycled back into the original mineral processing flow or discharged in compliance with standards.

[0097] Comparative Example 3

[0098] This comparative example is the comparative example of Example 4.

[0099] The flotation wastewater from the fluorocarbon cerium mine in Mianning, Sichuan Province, was selected. The pH value was 10, the COD content was 353.4 mg / L, and the total nitrogen content was 96.3 mg / L.

[0100] Under stirring, octadecyltrimethylammonium chloride was added directly to flotation wastewater containing hydroxamic acid compounds at a dosage of 1:1 to obtain wastewater containing trace amounts of yellowish-brown flocculent matter.

[0101] The flotation wastewater containing yellowish-brown flocculent hydroxyoxime acid compounds was transferred to a dedicated wastewater flotation equipment for flotation separation to remove trace amounts of yellowish-brown flocculent precipitate. This indicates that the amount of hydroxyoxime acid removed from the flotation wastewater was relatively small.

[0102] The remaining underflow wastewater from the air flotation separation is introduced into the coagulation reaction tank, and 3g / m³ of additives are added sequentially under stirring. 3 coagulant and 3mg / m 3 The flocculant undergoes a coagulation reaction to remove COD from the underflow wastewater, resulting in coagulated wastewater.

[0103] The coagulated wastewater was sent to a sedimentation tank for settling for 120 minutes to obtain supernatant (underflow wastewater with most of the COD removed). The supernatant was then pumped into a biochemical treatment system and 18 g / L of natural zeolite powder was added to completely remove COD and total nitrogen from the supernatant. The resulting wastewater had a COD content of 310.2 mg / L and a total nitrogen content of 84.3 mg / L. Therefore, the treated wastewater cannot be returned to the original mineral processing flow for recycling or discharged in compliance with standards.

[0104] Because the pH value of the flotation wastewater was not adjusted, even with the addition of octadecyltrimethylammonium chloride, the hydroxamic acid in the flotation wastewater was not significantly removed. Consequently, even after coagulation and biochemical treatment, the COD and total nitrogen content in the resulting wastewater showed little change compared to the COD and total nitrogen content in the untreated flotation wastewater.

[0105] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0106] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0107] The above provides a detailed description of a method for removing hydroxamic acid from flotation wastewater containing hydroxamic acid compounds, as provided by this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention; furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for removing hydroxyxamic acid from flotation wastewater containing hydroxyxamic acid compounds, characterized in that, The method includes: S1, after adjusting the pH of the flotation wastewater containing hydroxamic acid compounds to 5.5-7, a quaternary ammonium salt with long-chain molecules is added under stirring to obtain wastewater containing yellowish-brown flocculent matter; wherein, the mass ratio of the amount of quaternary ammonium salt added to the mass of hydroxamic acid in the flotation wastewater containing hydroxamic acid compounds is 1-6:

1. The quaternary ammonium salt with long-chain molecules is one or more of hexadecyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium chloride (DTAC), octadecyltrimethylammonium chloride, and dioctadecyldimethylammonium chloride; S2, The wastewater containing yellowish-brown flocculent matter is separated by air flotation using an air flotation device to remove the yellowish-brown flocculent matter; S3, the underflow wastewater obtained by removing the hydroxamic acid is introduced into the coagulation reaction tank, and coagulant and flocculant are added in sequence under stirring to carry out the coagulation reaction and obtain coagulated wastewater; S4, the coagulated wastewater is introduced into a sedimentation tank for static settling, and the resulting supernatant is pumped into a biochemical treatment system where zeolite is added to further remove COD and total nitrogen. The wastewater obtained after removal is returned to the original mineral processing flow for recycling or discharged in compliance with standards.

2. The method according to claim 1, characterized in that, The dosage of the quaternary ammonium salt is in a mass ratio of 1 to 2:1 to the mass of the hydroxamic acid in the flotation wastewater containing hydroxamic acid compounds.

3. The method according to claim 1, characterized in that, The hydroxamic acid-containing compounds include at least one of salicylic acid, alkyl hydroxamic acid, benzoic acid, and isohydroxamic acid.

4. The method according to claim 1, characterized in that, The flotation wastewater containing hydroxyoxime compounds is the wastewater after the flotation of fluorocarbon cerium ore.

5. The method according to claim 1, characterized in that, The coagulant is an inorganic polymer, and the amount of coagulant added is 3 g / m³. 3 ~15 g / m 3 .

6. The method according to claim 1, characterized in that, The flocculant is polyacrylamide, and the dosage of the flocculant is 1 g / m³. 3 ~4 g / m 3 .

7. The method according to claim 1, characterized in that, The settling time is 30 min to 180 min.

8. The method according to claim 1, characterized in that, The amount of zeolite added is 10 g / L to 20 g / L.

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