Method for removing refractory organic flotation reagent xanthate in beneficiation wastewater

Abstract

The present application relates to the technical field of ore dressing wastewater treatment, and particularly relates to a method for removing refractory organic flotation reagent xanthate in ore dressing wastewater, which comprises the following steps: S1: first adjusting the pH of the residual xanthate-containing ore dressing wastewater to 5.5-9.5; S2: under the stirring condition of 250-400 rpm, the adjusted ore dressing wastewater is added with natural ilmenite catalyst and 30% concentration H2O2 respectively to carry out heterogeneous Fenton oxidation reaction, and the reaction is carried out at room temperature 25 DEG C for 60-90 min; S3: filtration is carried out to obtain filtrate and precipitate respectively, the filtrate is the treated ore dressing wastewater, and the precipitate is recycled and reused; the heterogeneous Fenton reaction formed by the natural ilmenite and H2O2 generates ·OH and ·HO2 free radicals with strong oxidation capacity, which promotes the efficient conversion of the residual organic xanthate in the ore dressing wastewater into harmless small molecular substances such as CO2 and H2O, and reduces the COD of the wastewater. In addition, the catalytic performance of the ilmenite is superior, and the ilmenite is easy to recycle and reuse.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of beneficiation wastewater treatment, and particularly relates to a method for removing refractory organic flotation reagent xanthate in beneficiation wastewater. BACKGROUND

[0002] Beneficiation of non-ferrous metal ores mainly adopts flotation process, which will produce a large amount of beneficiation wastewater. The main pollutants in the beneficiation wastewater are usually residual organic flotation reagents and soluble metal ions (such as Cu, Pb, Zn, Fe). Xanthate is one of the most commonly used organic sulfur-based collectors in sulfide ore and part of oxidized ore flotation, and its consumption is expected to reach about 37182.6 million tons by 2025. In the process of mineral flotation separation, part of the xanthate collector enters the concentrate product with the foam, while the remaining part of the collector remains in the ore pulp and is discharged to the tailings pond with the tailings. When directly recycling the tailings wastewater, the residual reagent will affect the flotation index and have an adverse effect on the selectivity of mineral flotation. At the same time, xanthate naturally decomposes under acidic conditions to produce carbon disulfide (CS2) molecules, which pose a serious threat to biological systems due to their strong odor and toxicity. In addition, xanthate has always been a problem in the field of mineral processing wastewater disposal due to its characteristics of being difficult to degrade, strong irritancy, high toxicity, polluting the ecological environment, and damaging the nervous system and liver of humans and animals. Therefore, effectively treating residual xanthate in flotation wastewater is of great importance to the sustainable development of mines and environmental protection.

[0003] In the past few decades, various methods have been developed to remove xanthate from flotation wastewater, mainly including chemical oxidation, physical adsorption, coagulation-flocculation, microbial method, etc. However, these methods require continuous supply of chemicals and energy, have low treatment efficiency, incomplete treatment, and cannot meet the discharge standards, and there is a possibility of secondary pollution. Therefore, it is very urgent to develop an efficient disposal method for wastewater containing xanthate.

[0004] In order to overcome the shortcomings of these traditional treatment methods, Fenton oxidation method as an advanced green oxidation technology has been widely used in the field of beneficiation wastewater treatment. According to the different catalysts used, Fenton method is divided into homogeneous Fenton method and heterogeneous Fenton method. In the traditional Fenton oxidation process, Fe 2+Under acidic conditions, H2O2 is catalyzed to generate hydroxyl radicals (·OH) with a high redox potential of 2.8 eV, which can effectively degrade most organic pollutants in wastewater. However, homogeneous Fenton technology has many limitations, such as narrow acidic pH range, large amount of iron-containing sludge, etc. For example, the invention patent with application number 202010348241.0 discloses a method for degrading butyl xanthate in beneficiation wastewater, which reports that the treatment of xanthate by Fenton reagent oxidation method will produce red-brown precipitate, which will affect the colority of the effluent, thereby limiting its application. Therefore, the development of heterogeneous Fenton method has received more and more attention, that is, through natural iron-based catalyst, the stability and decomposition efficiency of Fenton reagent are improved, and then the degradation efficiency of pollution source is improved.

[0005] Typical natural iron-based catalysts include pyrite, pyrrhotite, hematite, magnetite, goethite, ilmenite, etc. On the one hand, the above-mentioned minerals have certain magnetism, which makes them easier to be recovered after the catalyst reaction. On the other hand, due to their unique structure and crystallinity, they exhibit excellent catalytic activity and stability in the process of H2O2 activation. In addition, in the process of natural iron-based catalyst activating H2O2, not only the decomposition efficiency of H2O2 is improved, but also various active substances such as ·OH, and ·HO2 are generated, which play a crucial role in the degradation of organic pollutants. Although the heterogeneous Fenton system formed by natural iron-based catalysts activating H2O2 has made great progress in degrading organic pollutants, there are still some problems such as being limited by acidic pH value, complex process, catalyst poisoning, not easy to recover and low degradation efficiency of organic pollutants.

[0006] Therefore, it is of great significance to develop a method for treating beneficiation wastewater containing residual xanthate, which is simple in process, easy to operate, low in running cost and good in treatment effect, for the sustainable development of mines and environmental protection. SUMMARY

[0007] In view of the shortcomings of the current treatment technology, the present application aims to provide a method for removing refractory organic flotation reagent xanthate in beneficiation wastewater, which has a wide pH adaptation range, does not produce iron sludge, the catalyst is easy to recover, the running cost is low, and the treatment efficiency is high.

[0008] In order to achieve the above technical purpose and achieve the above technical effect, the present application is realized by the following technical scheme:

[0009] A method for removing refractory organic flotation reagent xanthate in beneficiation wastewater, comprising the following steps:

[0010] S1: adjusting the pH of the beneficiation wastewater containing residual xanthate to 5.5-9.5;

[0011] S2: The adjusted mineral processing wastewater was subjected to heterogeneous Fenton oxidation reaction by adding ilmenite as a catalyst and 30% H2O2 under stirring conditions of 250-400 rpm, and the reaction was carried out at room temperature (25℃) for 60-90 min.

[0012] S3: Filter the solution after the heterogeneous Fenton oxidation reaction in step S2 to obtain filtrate and precipitate respectively. The filtrate is the treated mineral processing wastewater, and the precipitate is recycled and reused.

[0013] Furthermore, the ilmenite is a single mineral with a purity greater than 95% and a particle size of -74 to +38 μm.

[0014] Furthermore, in the flotation wastewater to be treated, the xanthate content is 20-100 mg / L, and the number of carbon atoms in the alkyl group is 2-5.

[0015] Furthermore, before adding the ilmenite catalyst and H2O2, the pH of the wastewater is adjusted to 5.5–9.5 using diluted HCl or NaOH.

[0016] Furthermore, the amount of ilmenite catalyst added is 2.0–5.0 g / L, measured by the volume of mineral processing wastewater.

[0017] Furthermore, based on the volume of mineral processing wastewater, the amount of H2O2 added is 2.0–5.0 mM.

[0018] On the other hand, the present invention proposes the application of the above method in removing xanthate, a recalcitrant organic flotation reagent, from mineral processing wastewater.

[0019] The beneficial effects of this invention are:

[0020] Highly efficient removal of xanthate, a recalcitrant organic flotation reagent: The heterogeneous Fenton oxidation reaction is the key treatment method in this invention. In this reaction, the addition of natural ilmenite catalyst and H2O2 generates hydroxyl radicals (·OH) with high redox potential. These hydroxyl radicals have strong oxidizing power and can effectively degrade xanthate molecules. Compared with traditional chemical oxidation methods, the heterogeneous Fenton oxidation reaction has higher treatment efficiency and better selectivity, and can completely remove xanthate. The heterogeneous Fenton reaction composed of natural ilmenite and H2O2 generates ·OH radicals with strong oxidizing power. The presence of H₂O and HO₂ free radicals promotes the efficient conversion of residual organic xanthates in mineral processing wastewater into harmless small molecules such as CO₂ and H₂O, thereby reducing the COD of the wastewater. Furthermore, ilmenite exhibits excellent catalytic performance and is easily recyclable.

[0021] Wide applicability: The application adjusts the pH value range of the beneficiation wastewater to adapt to different types of wastewater. The degradation of xanthate is affected by the pH value, and a certain pH range can improve the degradation efficiency. In addition, the purity of the ilmenite catalyst is required to be greater than 95%, and it has appropriate particle size, which can better adapt to the content and characteristics of xanthate in different wastewater. The heterogeneous Fenton reaction composed of natural ilmenite and H2O2 has strong oxidizing property in the pH range of 5.5-9.5, and can realize effective degradation of residual xanthate in beneficiation wastewater under the condition of natural pH of wastewater = 8.7, without the need for additional pH adjustment, reducing the cost of wastewater treatment.

[0022] No iron sludge is produced, and the catalyst is easy to recover: Compared with the traditional homogeneous Fenton technology, the heterogeneous Fenton oxidation reaction does not produce a large amount of iron-containing sludge. The problem of such sludge production is common in traditional treatment methods, which needs further treatment and disposal. However, the ilmenite catalyst used in the application has certain magnetism, which can be recovered and reused by simple operation methods such as magnetic separation. This reduces the consumption and cost of the catalyst in the treatment process.

[0023] Low operating cost and high treatment efficiency: The application is simple and convenient to operate, and does not need to continuously supply a large amount of chemicals and energy. The heterogeneous Fenton oxidation reaction can be carried out at room temperature, without the need for additional heating equipment, reducing the operating cost. Adjusting the pH value of the wastewater and the addition amount of the catalyst and H2O2 can realize efficient reaction, thereby improving the treatment efficiency. Compared with the prior art, the application has wide pH adaptability, simple process flow, high removal efficiency of xanthate in wastewater, and good application prospect.

[0024] In summary, the application has the ability to efficiently remove the difficult-to-degrade organic flotation reagent xanthate, has wide applicability, does not produce iron sludge, the catalyst is easy to recover, has low operating cost, high treatment efficiency and other outstanding effects. Based on the understanding and use of heterogeneous Fenton oxidation reaction, and by selecting a suitable catalyst and adjusting the reaction conditions, the application has important significance for the treatment of beneficiation wastewater, and can promote the sustainable development of mines and protect the environment.

[0025] Of course, it is not necessary for any product implementing the application to achieve all the advantages described above at the same time. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creating laborious work.

[0027] Figure 1 Mechanism diagram for the degradation of xanthate by natural ilmenite-H2O2 heterogeneous Fenton reaction in the present application;

[0028] Figure 2 (a) XRD pattern of natural FeTiO3; (b) N2 adsorption-desorption isotherm of natural FeTiO3; (c) SEM image of natural FeTiO3 and (d) EDS spectrum. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0030] Example 1:

[0031] The self-prepared butyl xanthate (SBX) was used as a simulated beneficiation wastewater sample, and a SBX solution with a concentration of 50 mg / L and an initial pH of 8.7 was prepared. The initial solution pH was adjusted to 5.5 with a diluted HCl solution, and then 4.0 g / L of ilmenite catalyst (purity greater than 95%, particle size of-74~+38 μm) and 2.0 mM of 30% H2O2 were sequentially added. The reaction was carried out at room temperature of 25°C with continuous mechanical stirring at a speed of 350 rpm. After 60, 75 and 90 min of reaction, the catalyst and the solution were separated by filtration with a 0.22 μm polytetrafluoroethylene (PTFE) filter membrane. Then, the residual concentration of SBX was measured in the wavelength range of 200-400 nm by a UV-visible spectrophotometer, and the degradation rate was calculated. The results are shown in Table 1.

[0032] Example 2:

[0033] The treatment conditions of this example were the same as those of Example 1, except that the initial solution pH was adjusted to 7.5 with a diluted HCl solution. The results are shown in Table 1.

[0034] Example 3:

[0035] The treatment conditions of this example were the same as those of Example 1, except that the solution was not adjusted in pH, and the initial solution pH was 8.7. The results are shown in Table 1.

[0036] Example 4:

[0037] The treatment conditions of this example are the same as those of Example 1, except that the pH of the initial solution is adjusted to 9.5 with a dilute NaOH solution. The results are shown in Table 1.

[0038] Table 1 Comparison of the concentration and degradation rate of butyl xanthate after treatment in Examples 1-4.

[0039]

[0040] Examples 1-4 above are the treatment results of wastewater under different pH conditions and reaction times. As can be seen from Table 1, when the pH of the simulated wastewater is 5.5-9.5, the degradation rate of butyl xanthate is more than 90%. When the pH of the simulated wastewater is 5.5 (i.e. acidic conditions), the degradation rate of butyl xanthate reaches 95.17% after 90 minutes of reaction. When the initial pH is 8.7, i.e. the natural pH of the solution, the degradation rate of butyl xanthate reaches 92.64% after 90 minutes of reaction. This shows that the pH of the mineral processing wastewater has an important influence on the degradation rate of butyl xanthate. Moreover, the method of the present application shows excellent degradation efficiency for butyl xanthate in mineral processing wastewater under weak acid and weak base conditions, indicating that it has a wide pH applicability.

[0041] As can be seen from Example 3, the method of the present application for removing the refractory organic flotation reagent xanthate in mineral processing wastewater does not need to adjust the pH of the mineral processing wastewater to be treated, and is carried out under the condition of natural pH of 8.7. This not only reduces the treatment cost, but also is beneficial to the final discharge of wastewater.

[0042] Example 5:

[0043] A butyl xanthate (SBX) solution with a concentration of 50 mg / L was prepared as a simulated mineral processing wastewater sample, and the initial pH was 8.7. The solution was not adjusted in pH, and 2.0 g / L of a titanium iron ore catalyst (purity greater than 95%, particle size of -74 to +38 μm) and 2.0 mM of 30% H2O2 were sequentially added under the condition of natural pH of 8.7, and continuous mechanical stirring was carried out at a speed of 350 rpm at room temperature of 25°C. After 60, 75 and 90 minutes of reaction, the catalyst and the solution were separated by filtering with a 0.22 μm polytetrafluoroethylene (PTFE) filter membrane. Then, the residual concentration of SBX was measured in the wavelength range of 200-400 nm by a UV-visible spectrophotometer, and the degradation rate was calculated. The results are shown in Table 2.

[0044] Example 6:

[0045] The treatment conditions of this example are the same as those of Example 5, except that the amount of titanium iron ore catalyst added is 5.0 g / L. The results are shown in Table 2.

[0046] Table 2 Comparison data of concentration and degradation rate of butyl xanthate after treatment in Examples 5-6

[0047]

[0048]

[0049] The above Examples 5-6 are the treatment results of wastewater under different ilmenite catalyst dosages and reaction times. As shown in Table 2, when the ilmenite addition amount is 2.0 g / L, the degradation rate of butyl xanthate reaches more than 90%. When the ilmenite addition amount is 5.0 g / L, the degradation rate of butyl xanthate reaches 97.74% after 90 min of reaction. It is shown that within the catalyst dosage of 2.0-5.0 g / L, H2O2 has a good degradation effect on the degradation of butyl xanthate in the mineral processing wastewater.

[0050] Example 7

[0051] Butyl xanthate (SBX) was self-prepared as a simulated mineral processing wastewater sample, and a SBX solution with a concentration of 50 mg / L was prepared, and the initial pH was 8.7. The solution was not adjusted in pH, and 4.0 g / L of ilmenite catalyst (purity greater than 95%, particle size of-74-+38 μm) and 3.0 mM of 30% concentration H2O2 were sequentially added under the condition of natural pH of 8.7, and continuous mechanical stirring was carried out at a speed of 350 rpm at room temperature of 25°C. After 60, 75, and 90 min of reaction, the catalyst and the solution were separated by filtering with a 0.22 μm polytetrafluoroethylene (PTFE) filter membrane. Then, the residual concentration of SBX was measured in the wavelength range of 200-400 nm by using a UV-visible spectrophotometer, and the degradation rate was calculated, and the results are shown in Table 3.

[0052] Example 8

[0053] The treatment conditions of this example are the same as those of Example 7, except that the H2O2 addition amount is 5.0 mM. The results are shown in Table 3.

[0054] Table 3 Comparison data of concentration and degradation rate of butyl xanthate after treatment in Examples 7-8

[0055]

[0056]

[0057] The above examples 7-8 are the treatment results of wastewater under different H2O2 dosages and reaction times. As shown in Table 3, under the same conditions, the greater the H2O2 dosage, the higher the degradation rate of butyl xanthate. When the H2O2 dosage is 5.0 mM, the degradation rate of butyl xanthate reaches 98.12% after 90 min of reaction. It shows that with the increase of H2O2 concentration, the generated active free radicals increase, which effectively promotes the degradation of butyl xanthate. Under the recommended H2O2 dosage, H2O2 has good degradation effect on the degradation of butyl xanthate in the beneficiation wastewater.

[0058] Example 9:

[0059] An ethyl xanthate solution with a concentration of 80 mg / L is prepared as a simulated beneficiation wastewater sample, and the initial pH is 8.7. Without adjusting the pH of the solution, 4.0 g / L of ilmenite catalyst (purity greater than 95%, particle size of-74~+38 μm) and 2.0 mM of 30% H2O2 are sequentially added under the condition of natural pH of 8.7, and the solution is continuously mechanically stirred at a speed of 350 rpm at room temperature of 25°C. After 60, 75, and 90 min of reaction, the catalyst and the solution are separated by filtering with a 0.22 μm polytetrafluoroethylene (PTFE) filter membrane. Then, the residual concentration of SBX in the filtrate is measured by a UV-visible spectrophotometer in the wavelength range of 200-400 nm, and the degradation rate is calculated, and the results are shown in Table 4.

[0060] Example 10:

[0061] The treatment conditions of this example are the same as those of example 9, except that a pentyl xanthate solution with a concentration of 30 mg / L is prepared as a simulated beneficiation wastewater sample, and the initial pH is 8.7. The results are shown in Table 4.

[0062] Table 4 Comparison data of concentrations and degradation rates of different xanthates after treatment in examples 9-10

[0063]

[0064]

[0065] The above examples 9-10 are the treatment results of wastewater under different types of xanthate and reaction time. As shown in Table 4, in the heterogeneous Fenton system composed of ilmenite and H2O2, the degradation rates of different types of xanthate all reach more than 90%. It shows that the method for removing the refractory organic flotation reagent xanthate in the beneficiation wastewater is suitable for the degradation of different types of xanthate.

[0066] Comparative example 1:

[0067] The self-prepared butyl xanthate was used as a simulated beneficiation wastewater sample, and a butyl xanthate solution with a concentration of 50 mg / L was prepared, and the initial pH was 8.7. The solution was not adjusted in pH, and only 2.0 mM of 30% H2O2 was added, and continuous mechanical stirring was carried out at a speed of 350 rpm at room temperature of 25°C. After 60, 75, 90 min of reaction, the catalyst and the solution were separated by filtering with a 0.22 μm polytetrafluoroethylene (PTFE) filter membrane. Then, the filtrate was measured for the residual concentration of SBX in the wavelength range of 200-400 nm by a UV-visible spectrophotometer, and the degradation rate was calculated, and the results are shown in Table 5.

[0068] Table 5 is the concentration and degradation rate of butyl xanthate after treatment in Comparative Example 1

[0069]

[0070] The above Comparative Example 1 is the treatment result of butyl xanthate wastewater by adding only H2O2, and it can be seen from Table 5 that under the same conditions, the degradation rate of butyl xanthate by adding only H2O2 is less than 60%, which indicates that the oxidation ability of the H2O2 system alone is limited and cannot completely oxidize butyl xanthate.

[0071] Example 11:

[0072] The recovery step of the ilmenite catalyst is that the mixed solution after reaction is centrifuged and filtered to obtain a filtrate and a precipitate (used ilmenite). The precipitate is used as the catalyst in the next degradation experiment. Five consecutive degradation experiments are carried out under the same conditions. The degradation experiment steps are as follows: butyl xanthate (SBX) is self-prepared as a simulated beneficiation wastewater sample, and a SBX solution with a concentration of 50 mg / L is prepared, and the initial pH is 8.7. The solution is not adjusted in pH, and 4.0 g / L of ilmenite catalyst (purity greater than 95%, particle size of-74 to +38 μm) and 2.0 mM of 30% H2O2 are sequentially added under the condition of natural pH of 8.7, and continuous mechanical stirring is carried out at a speed of 350 rpm at room temperature of 25°C. After 75 min of reaction, the catalyst and the solution are separated by filtering with a 0.22 μm polytetrafluoroethylene (PTFE) filter membrane. Then, the filtrate is measured for the residual concentration of SBX in the wavelength range of 200-400 nm by a UV-visible spectrophotometer, and the degradation rate is calculated. The results are shown in Table 6.

[0073] Table 6 is the effect of the number of times of recycling and reuse of the ilmenite catalyst on the degradation of butyl xanthate in Example 12

[0074]

[0075] The above embodiment 11 is the influence of the number of recycling times of the ilmenite catalyst on the degradation of butyl xanthate. As shown in Table 6, under the same conditions, the influence of the ilmenite catalyst on the degradation rate of butyl xanthate is small. After 5 cycles, the degradation rate of butyl xanthate by ilmenite is still as high as 89.46%. This shows that the ilmenite catalyst has good reusability and stability.

[0076] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details and limit the application to the specific embodiments described. Obviously, many modifications and changes can be made according to the content of the specification. The specification selects and describes these embodiments in order to better explain the principles and practical applications of the application, so that those skilled in the art can well understand and use the application. The application is limited only by the claims and their full scope and equivalents.

Claims

1. A method for removing the non-biodegradable organic flotation reagent xanthate from beneficiation wastewater, characterized by, The method comprises the following steps: S1: adjusting the pH of the flotation wastewater containing residual xanthate to 5.5-9.5; S2: under the stirring condition of 250-400 rpm, the adjusted flotation wastewater is subjected to heterogeneous Fenton oxidation reaction by adding ilmenite as a catalyst and 30% concentration H2O2, and the reaction is carried out at room temperature 25℃ for 60-90 min; S3: the solution after the heterogeneous Fenton oxidation reaction in step S2 is filtered to obtain filtrate and precipitate, and the filtrate is the treated flotation wastewater, and the precipitate is recycled and reused; In the flotation wastewater to be treated in step S1, the content of xanthate is 20-100 mg / L, and the number of carbon atoms in the alkyl group is 2-5; Before the addition of ilmenite catalyst and H2O2 in step S2, the pH of the wastewater is adjusted to 5.5-9.5 by using diluted HCl or NaOH; According to the volume of the flotation wastewater, the addition amount of ilmenite catalyst in step S2 is 2.0-5.0 g / L; According to the volume of the flotation wastewater, the addition amount of H2O2 in step S2 is 2.0-5.0 mM; The ilmenite in step S2 is a single mineral with a purity of more than 95% and a particle size of-74+38 μm.

2. The application of the method according to claim 1 in removing the refractory organic flotation reagent xanthate in the flotation wastewater.

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