A double modified styrene-acrylic emulsion tailings passivation agent, a preparation method and application thereof

Abstract

The application discloses a double-modified phenylpropyl emulsion tailing passivator and a preparation method and application thereof. The double-modified phenylpropyl emulsion tailing passivator with uniform particle size and good stability is prepared by adopting a semi-continuous emulsion polymerization method and adopting functional monomers of phytic acid and hydroxyethyl methyl acrylate phosphate to double-modify the phenylpropyl emulsion. The pyrite surface is coated and passivated by a spraying method, film curing at room temperature can be realized, the chemical bonding force between the phenylpropyl emulsion and the tailing is enhanced, and the tailing oxidation can be effectively inhibited. The double-modified phenylpropyl emulsion tailing passivator is green, environmentally friendly, simple in process, low in cost, simple to use and convenient to apply to the passivation treatment of tailings.

Description

Technical Field

[0001] This invention belongs to the field of acid mine wastewater treatment technology, specifically relating to a dual-modified styrene-acrylic emulsion tailings passivating agent and its application in tailings treatment, applicable to the field of metal mine tailings passivation. Background Technology

[0002] With my country's economic development, existing mining activities have resulted in a large number of abandoned mines and accumulated tailings. These tailings, under the combined effects of natural weathering, rain leaching, and microbial activity, easily generate acidic mine wastewater (AMD), releasing large amounts of heavy metal ions, severely polluting the environment surrounding mining areas, and threatening human living space. Currently, most measures to control AMD pollution focus on end-of-pipe treatment, such as sterilization, neutralization, and wetland remediation. However, these methods cannot control AMD generation at its source. Surface passivation inhibits tailings oxidation from a microscopic perspective, forming a physicochemical barrier film through a chemical reaction with the surface of metal sulfide ores, enhancing the oxidation resistance of pyrite. This method is low-cost and simple to operate, making it one of the most promising methods for controlling pyrite pollution at its source. Existing surface passivation technologies include the formation of various passivation coatings (inorganic, organic, and organosilanes) and carrier microencapsulation.

[0003] Phosphates in inorganic passivation materials can easily cause secondary pollution, and silicates generally require pretreatment; otherwise, passivation will not occur. Compared to inorganic passivators, there are more types of organic passivators. Among them, organosilane passivators have been extensively studied. Patent CN114504759A discloses a method for preparing a room-temperature curable long-lasting tailings passivator, which achieves room-temperature curing of the organosilane passivation film through chemical reaction, avoiding the disadvantages of complex preparation and high-temperature curing. Although the passivation efficiency of silane films for pyrite is quite considerable, the formation of the silane film inevitably requires the use of a large amount of organic solvent, and the curing temperature is relatively high, making it unsuitable for the actual passivation treatment of pyrite tailings.

[0004] Styrene-acrylic emulsions possess numerous advantages, including good weather resistance, corrosion resistance, low cost, and wide applicability, leading to their broad application. Patent CN114044848A discloses a method for preparing fatty acid-modified styrene-acrylic emulsions, utilizing unsaturated fatty acids as monomers in emulsion polymerization to improve the stability and mechanical properties of the emulsion. Combined with other pigments, it can be used as an anti-rust coating for metal substrates. However, anti-rust coatings based on styrene-acrylic emulsions have complex formulations and poor adhesion to the substrate, resulting in easy latex film detachment. This patent modifies the styrene-acrylic emulsion by incorporating functional monomers that can form chemical bonds and chelate with the tailings surface, enhancing the coating passivation effect of the styrene-acrylic emulsion on the tailings from a chemical perspective. Furthermore, direct application of modified styrene-acrylic emulsions to substrate passivation is rarely reported, and issues such as poor adhesion to tailings and insufficient hydrophobicity of the passivation film need to be addressed. This patent utilizes unsaturated monomers containing P=O and P-OH and long-chain reactive emulsifiers to modify styrene-acrylic emulsions. Taking advantage of the spontaneous film-forming property of styrene-acrylic emulsions at room temperature, chemical bonds and metal complexes are formed with the tailings surface, enhancing the adhesion between the styrene-acrylic emulsion and the tailings surface, improving the hydrophobicity of the passivation film, and better achieving the coating passivation of tailings with the styrene-acrylic emulsion. Applying the modified styrene-acrylic emulsion to the surface passivation of pyrite tailings avoids the problems of using organic solvents and high-temperature curing, providing a new solution for the development of tailings passivation materials. Summary of the Invention

[0005] To address the shortcomings and deficiencies of existing technologies, the primary objective of this invention is to provide a dual-modified styrene-acrylic emulsion tailings passivating agent. This agent is prepared by modifying the styrene-acrylic emulsion with the functional monomers phytic acid and hydroxyethyl methacrylate phosphate, resulting in a passivating agent with uniform particle size and good stability. By coating and passivating the pyrite surface using a spraying method, a film can be formed at room temperature, enhancing the chemical bonding between the styrene-acrylic emulsion and the tailings, and effectively inhibiting tailings oxidation.

[0006] This tailings passivating agent uses water as a solvent and can solidify on the surface of pyrite at room temperature to form a dense passivation film with antioxidant properties. It avoids the problems of high-temperature curing and large-scale use of solvents in organosilane passivating materials. Not only is the preparation process green and environmentally friendly and low-cost, but it also has good feasibility for practical tailings passivation and is easy to operate.

[0007] Another object of the present invention is to provide a method for preparing the above-mentioned dual-modified styrene-acrylic emulsion tailings passivating agent.

[0008] Another object of the present invention is to provide the application of the above-mentioned dual-modified styrene-acrylic emulsion tailings passivating agent in the treatment of metal tailings pollution.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] A method for preparing a dual-modified styrene-acrylic emulsion, comprising modifying a styrene-acrylic emulsion with phytic acid and hydroxyethyl methyl styrene phosphate to obtain a dual-modified styrene-acrylic emulsion.

[0011] Preferably, the above preparation method includes the following steps:

[0012] (1) Phytic acid-modified functional monomers were prepared by reacting phytic acid, glycidyl methacrylate, a first initiator, a polymerization inhibitor and water.

[0013] (2) The phytic acid-modified functional monomer, hydroxyethyl methyl styrene phosphate, styrene monomer, acrylate monomer, second initiator, emulsifier, electrolyte and water described in step (1) are used to prepare the double-modified styrene-acrylic emulsion.

[0014] Preferably, in step (1), the first initiator is one or more of azobisisobutyronitrile or tetrabutylammonium bromide; the polymerization inhibitor is hydroquinone;

[0015] In step (2), the acrylate monomers are butyl acrylate and methyl methacrylate; the second initiator is one or more of azobisisobutyronitrile or ammonium persulfate; the emulsifier is a reactive emulsifier, allyloxyisobutyl ether sulfate SR-10 or sodium dodecyl sulfate K12; and the electrolyte is one or more of sodium bicarbonate or disodium hydrogen phosphate.

[0016] Preferably, the specific operation of step (1) is as follows: an aqueous solution containing a first initiator and a polymerization inhibitor is added to phytic acid and glycidyl methacrylate, and the mixture is kept at 80-95°C for 0.5-2 hours to separate the phytic acid-modified functional monomer.

[0017] The molar ratio of phytic acid to glycidyl methacrylate is 1:6 to 1:12.

[0018] The mass ratio of the first initiator to the polymerization inhibitor is 10:1.

[0019] Preferably, the specific operation of step (2) is as follows:

[0020] S1: Take the following dosages (by mass) of monomers: 0.1-0.5 parts of phytic acid-modified functional monomer, 0.5 parts of hydroxyethyl methacrylate phosphate, 2 parts of methyl methacrylate, 40 parts of styrene and butyl acrylate, then add 0.10 parts of ammonium persulfate, 0.88 parts of K12 and SR-10, 0.14 parts of sodium bicarbonate and 60 parts of deionized water, and then stir and disperse for 5-30 minutes to obtain a well dispersed pre-emulsified solution;

[0021] S2: Take 1 volume part of the pre-emulsified solution and carry out emulsion polymerization at 75-90℃ and 600-750rpm for 0.5-2h to obtain solution A;

[0022] S3: Take 0.3 to 1 volume part of the pre-emulsified solution, add the second initiator to obtain solution B; add solution B dropwise to solution A within 1 to 3 hours, react at 75 to 90℃ for 0.5 to 2 hours; finally cool down to 40℃, adjust the pH of the solution to 7-8, filter, and obtain styrene-acrylic emulsion.

[0023] Preferably, the mass ratio of phytic acid-modified functional monomer to hydroxyethyl methacrylate phosphate monomer is 1:2 to 1:5, and the total mass of the two accounts for 0.6% to 1% of the total mass of the entire system.

[0024] The mass ratio of reactive emulsifiers SR-10 and K12 is 5:6;

[0025] The mass ratio of the two monomers, styrene and butyl acrylate, is 1:3 to 3:2.

[0026] A double-modified styrene-acrylic emulsion prepared by the above method.

[0027] The above-mentioned dual-modified styrene-acrylic emulsion is used in the treatment of metal tailings pollution.

[0028] Preferably, the double-modified styrene-acrylic emulsion is sprayed onto the surface of the tailings and cured into a film at room temperature.

[0029] Preferably, the tailings particle size is 25μm to 15mm, and the room temperature is 20℃ to 35℃.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] (1) This invention employs a semi-continuous emulsion polymerization method, resulting in controllable emulsion particle size and good stability. The reactive emulsifier SR-10 and K12 are compounded for emulsification, serving both as emulsifiers and monomers in the emulsion polymerization process. Their long carbon chains also enhance the hydrophobic properties of the latex film. Since phytic acid and hydroxyethyl methacrylate phosphate contain P=O and P-OH bonds, the styrene-acrylic emulsion, modified with phytic acid and hydroxyethyl methacrylate phosphate functional monomers, forms PO-Fe bonds with the iron ions on the pyrite surface, increasing the adhesion between the emulsion and the pyrite. The modified styrene-acrylic emulsion is then coated and passivated with tailings. At room temperature, with the evaporation of moisture, the latex particles bond together to form a dense latex film, effectively blocking the invasion of oxidizing media such as oxygen and water molecules, thereby inhibiting the oxidation of the tailings.

[0032] (2) The present invention uses phytic acid and hydroxyethyl methacrylate phosphate functional monomers to modify styrene-acrylic emulsion, and prepares styrene-acrylic emulsion with uniform particle size and good stability, which greatly enhances the adhesion of styrene-acrylic emulsion to tailings.

[0033] (3) The double-modified styrene-acrylic emulsion tailings passivating agent provided by the present invention is green and environmentally friendly, with simple process, economical cost, and easy to use, and is convenient to be applied to the passivation treatment of tailings. Attached Figure Description

[0034] Figure 1 The infrared spectrum of the dual-modified styrene-acrylic emulsion tailings passivator in Example 1 is shown.

[0035] Figure 2 This is a SEM image of the raw ore.

[0036] Figure 3 The image shows the DLS diagram of the dual-modified styrene-acrylic emulsion tailings passivating agent in Example 1.

[0037] Figure 4 The cyclic voltammetry (CV) curves for Example 1 and the raw ore are shown.

[0038] Figure 5 The graph shows the change of total iron concentration over time in the antioxidant experiments of Examples 1, 2, 3, 4 and Control Examples 1, 2, 3. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0040] All materials used in the following examples are commercially available. Component quantities are in parts.

[0041] The physicochemical stability test conditions for the dual-modified styrene-acrylic emulsion tailings passivating agent are as follows:

[0042] Storage stability: First, put the emulsion into a 50ml centrifuge tube and place it at room temperature of 25℃ for at least 3 months. Observe whether the emulsion sample in the centrifuge tube has stratification. If no precipitate or gel is formed, the storage stability of the emulsion sample is passed; otherwise, it is not passed.

[0043] Centrifugal stability: The test was conducted using a Sigma 1-14 centrifuge manufactured by Sigma. An appropriate amount of the emulsion to be tested was placed in a 10ml centrifuge tube. The centrifuge speed was set to 3000 rpm for 15 minutes. After centrifugation, the sample was removed, placed vertically, and its morphology was observed. If the sample remained homogeneous without stratification or gel formation, the centrifugal stability test of the emulsion sample was passed; otherwise, it failed.

[0044] Ca 2+Stability: Take 10 ml of the test sample emulsion in a beaker, add 4 ml of 0.5 wt% CaCl2 aqueous solution to the emulsion, and let it stand at room temperature for 24 h. Observe whether the sample emulsion separates into layers or whether flocculation and precipitation occur. If no separation or flocculation and precipitation occurs, and the emulsion remains in a homogeneous and stable state, then the CaCl2 content of the emulsion sample is considered stable. 2+ Stability is considered passed; otherwise, it is considered failed.

[0045] The chemical oxidation resistance test steps are as follows: pyrite passivated sample is added to 100 ml of 0.5 wt% hydrogen peroxide solution, pH value is 6.18, oxidation time is 0-24 h, reaction temperature is 25℃, oscillation is performed at 150 rpm, and the total iron concentration is measured periodically. The passivation efficiency of the passivating agent is calculated using formula (1).

[0046]

[0047] Where c0 represents the total concentration of the leaching solution for unpassivated ore, c i This represents the total concentration of the leachate from the passivated pyrite sample.

[0048] The electrochemical testing procedures are as follows: Testing was conducted using a Shanghai Chenhua CHI660 electrochemical workstation, including open-circuit voltage (OCP), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and Tafel curve measurements. A three-electrode system was used: a pyrite electrode as the working electrode, a platinum sheet electrode as the counter electrode, and a saturated calomel electrode (SCE) as the reference electrode. Sodium sulfate solution at pH 2 was used as the electrolyte. The electrochemical experimental conditions were as follows: OCPT testing time was 400 s, with a sampling interval of 0.1 s; the EIS frequency range was 10... 5 ~10 -2 Hz, sinusoidal disturbance voltage amplitude 5mV; CV scan rate 0.1mV / s, scan range -0.65~+0.65V; Tafel scan range OCPT±0.2V, scan rate 1mV / s; sensitivity of all tests is 10. -3 .

[0049] In the examples and control examples, the tailings particle size was 25μm to 15mm.

[0050] Example 1

[0051] (1) Preparation of phytic acid-modified glycidyl methacrylate monomer

[0052] 6.6 g (0.01 mol) of phytic acid and 17.064 g (0.12 mol) of glycidyl methacrylate were weighed into a reaction flask. Separately, 0.437 g of tetrabutylammonium bromide initiator and 43.7 mg of hydroquinone polymerization inhibitor were dissolved in deionized water, and the prepared solutions were transferred to the above reaction flask. The reaction temperature was set to 90 °C, and the reaction time was 1 h. After separation, the phytic acid-modified glycidyl methacrylate monomer (PG) was obtained.

[0053] (2) Preparation of dual-modified styrene-acrylic emulsion tailings passivating agent

[0054] The following monomers were added sequentially to a beaker: 0.1 parts PG, 0.5 parts hydroxyethyl methacrylate phosphate, 16 parts styrene, 24 parts butyl acrylate, and 2 parts methyl methacrylate. Then, 0.10 parts ammonium persulfate, 0.40 parts sodium dodecyl sulfate (K12), 0.48 parts allyl oxyisomeric alcohol ether sulfate ammonium salt (SR-10), 0.14 parts sodium bicarbonate, and 60 parts deionized water were added. The mixture was then magnetically stirred for 10 minutes to obtain a well-dispersed pre-emulsion solution. A three-necked flask equipped with a magnetic stirrer, a reflux condenser, and a constant-pressure dropping funnel was placed in a constant-temperature water bath. One-third of the volume of the pre-emulsion solution was added, and the temperature was raised to 80°C. The stirring speed was controlled at 700 rpm, and the reaction was allowed to proceed for 1 hour. The remaining two-thirds of the volume of the pre-emulsion solution was then added to the remaining 0.10 parts of the initiator ammonium persulfate, and the mixture was transferred to a constant-pressure dropping funnel. When the reflux in the condenser decreases, the solution in the constant-pressure dropping funnel is added dropwise over 2 hours. The reaction is maintained at 80℃ for 1 hour. Finally, the temperature is lowered to 40℃, the pH is adjusted to 7-8 with an appropriate amount of ammonia, and the product is filtered out to obtain a milky white styrene-acrylic emulsion with a blue luster, named PAM-0.5-PG-0.1. The various physicochemical stability parameters are shown in Table 1.

[0055] (3) Pyrite coating passivation

[0056] The double-modified styrene-acrylic emulsion prepared in step (2) was used to immerse the pyrite that had been washed with water and alcohol. After stirring magnetically for 4 hours, the mixture was separated and left to stand at room temperature for 12 hours.

[0057] Analyzing the chemical composition of the double-modified styrene-acrylic emulsion tailings passivating agent using infrared spectroscopy (e.g.) Figure 1 (as shown), of which 2955cm -1 The absorption peak at 1732 cm⁻¹ is attributed to the stretching vibrations of -CH and -CH₂. -1 The absorption peak at 1640 cm⁻¹ is attributed to the stretching vibration of C=O. -1 The absence of a characteristic C=C absorption peak at 1164 cm⁻¹ indicates that the monomer conversion was relatively complete. -1The absorption peaks that appeared were attributed to P=O, indicating that the two monomers, phytic acid and hydroxyethyl methacrylate phosphate, were successfully polymerized onto the polymer chain; the SEM morphology characterization of the raw ore (e.g., Figure 2 As shown); the particle size distribution of latex particles in aqueous solution was tested using a dynamic light scattering instrument (e.g., as shown). Figure 3 As shown); perform electrochemical performance tests (such as...). Figure 4 (As shown).

[0058] Example 2

[0059] (1) Preparation of phytic acid-modified glycidyl methacrylate monomer

[0060] 6.6 g (0.01 mol) of phytic acid and 17.064 g (0.06 mol) of glycidyl methacrylate were weighed into a reaction flask. Separately, 0.437 g of tetrabutylammonium bromide initiator and 43.7 mg of hydroquinone polymerization inhibitor were dissolved in an appropriate amount of deionized water, and the prepared solutions were transferred to the above reaction flask. The reaction temperature was set at 85 °C, and the reaction time was 1.5 h. After separation, the phytic acid-modified glycidyl methacrylate monomer (PG) was obtained.

[0061] (2) Preparation of dual-modified styrene-acrylic emulsion tailings passivating agent

[0062] The following monomers were added sequentially to a beaker: 0.5 parts PG, 0.5 parts hydroxyethyl methacrylate phosphate, 20 parts styrene, 20 parts butyl acrylate, and 2 parts methyl methacrylate. Then, 0.10 parts ammonium persulfate, 0.48 parts K12, 0.40 parts SR-10, 0.14 parts sodium bicarbonate, and 60 parts deionized water were added. The mixture was then magnetically stirred for 15 minutes to obtain a well-dispersed pre-emulsified solution. A three-necked flask equipped with a magnetic stirrer, a reflux condenser, and a constant-pressure dropping funnel was placed in a constant-temperature water bath. One-quarter of the pre-emulsified solution was added, and the temperature was raised to 85°C. The stirring speed was controlled at 650 rpm, and the reaction was allowed to proceed for 0.5 hours. The remaining 0.10 parts of ammonium persulfate initiator was then added to the remaining three-quarters of the pre-emulsified solution, and the mixture was transferred to a constant-pressure dropping funnel. As the reflux in the condenser decreased, the solution in the constant-pressure dropping funnel was added dropwise over 1.5 hours. The reaction was maintained at 85℃ for 1.5 hours. Finally, the temperature was lowered to 40℃, the pH was adjusted to 7-8 with an appropriate amount of ammonia, and the product was filtered out to obtain a milky white styrene-acrylic emulsion with a blue luster, named PAM-0.5-PG-0.5. The various physicochemical stability parameters are shown in Table 1.

[0063] (3) Pyrite coating passivation

[0064] The double-modified styrene-acrylic emulsion prepared in step (2) was used to immerse the pyrite that had been washed with water and alcohol. After stirring magnetically for 2 hours, the mixture was separated and left to stand at room temperature for 16 hours.

[0065] The chemical composition of the double-modified styrene-acrylic emulsion tailings passivator was analyzed by infrared spectroscopy, its morphology was characterized by SEM, the particle size of the latex particles was tested, and its electrochemical performance was tested. The results were similar to those in Example 1.

[0066] Example 3

[0067] (1) Preparation of phytic acid-modified glycidyl methacrylate monomer

[0068] 6.6 g (0.01 mol) of phytic acid and 17.064 g (0.08 mol) of glycidyl methacrylate were weighed into a reaction flask. Separately, 0.437 g of tetrabutylammonium bromide initiator and 43.7 mg of hydroquinone polymerization inhibitor were dissolved in an appropriate amount of deionized water, and the prepared solutions were transferred to the above reaction flask. The reaction temperature was set at 80 °C, and the reaction time was 2 h. After separation, the phytic acid-modified glycidyl methacrylate monomer (PG) was obtained.

[0069] (2) Preparation of dual-modified styrene-acrylic emulsion tailings passivating agent

[0070] The following monomers were added sequentially to a beaker: 0.25 parts PG, 0.5 parts hydroxyethyl methacrylate phosphate, 24 parts styrene, 16 parts butyl acrylate, and 2 parts methyl methacrylate. Then, 0.10 parts ammonium persulfate, 0.60 parts K12, 0.28 parts SR-10, 0.14 parts sodium bicarbonate, and 60 parts deionized water were added. The mixture was then magnetically stirred for 20 minutes to obtain a well-dispersed pre-emulsified solution. A three-necked flask equipped with a magnetic stirrer, a reflux condenser, and a constant-pressure dropping funnel was placed in a constant-temperature water bath. Two-fifths of the pre-emulsified solution was added, and the temperature was raised to 90°C. The stirring speed was controlled at 600 rpm, and the reaction was allowed to proceed for 1.5 hours. The remaining 0.10 parts of the initiator, ammonium persulfate, was then added to the remaining three-fifths of the pre-emulsified solution, and the mixture was transferred to a constant-pressure dropping funnel. When the reflux in the condenser decreases, the solution in the constant-pressure dropping funnel is added dropwise over 1 hour. The reaction is maintained at 90℃ for 0.5 hours. Finally, the temperature is lowered to 40℃, the pH is adjusted to 7-8 with an appropriate amount of ammonia, and the product is filtered out to obtain a milky white styrene-acrylic emulsion with a blue luster, named PAM-0.5-PG-0.25. The various physicochemical stability parameters are shown in Table 1.

[0071] (3) Pyrite coating passivation

[0072] Immerse 1.0g of water-washed and alcohol-washed pyrite in the double-modified styrene-acrylic emulsion prepared in step (2), stir magnetically for 1h, separate, and let stand at room temperature for 20h.

[0073] The chemical composition of the double-modified styrene-acrylic emulsion tailings passivator was analyzed by infrared spectroscopy, its morphology was characterized by SEM, the particle size of the latex particles was tested, and its electrochemical performance was tested. The results were similar to those in Example 1.

[0074] Example 4

[0075] (1) Preparation of phytic acid-modified glycidyl methacrylate monomer

[0076] 6.6 g (0.01 mol) of phytic acid and 17.064 g (0.10 mol) of glycidyl methacrylate were weighed into a reaction flask. Separately, 0.437 g of tetrabutylammonium bromide initiator and 43.7 mg of hydroquinone polymerization inhibitor were dissolved in deionized water, and the prepared solutions were transferred to the above reaction flask. The reaction temperature was set to 95 °C, and the reaction time was 0.5 h. After separation, the phytic acid-modified glycidyl methacrylate monomer (PG) was obtained.

[0077] (2) Preparation of dual-modified styrene-acrylic emulsion tailings passivating agent

[0078] The following monomers were added sequentially to a beaker: 0.15 parts PG, 0.5 parts hydroxyethyl methacrylate phosphate, 10 parts styrene, 30 parts butyl acrylate, and 2 parts methyl methacrylate. Then, 0.10 parts ammonium persulfate, 0.48 parts K12, 0.40 parts SR-10, 0.14 parts sodium bicarbonate, and 60 parts deionized water were added. The mixture was then magnetically stirred for 5 minutes to obtain a well-dispersed pre-emulsified solution. A three-necked flask equipped with a magnetic stirrer, a reflux condenser, and a constant-pressure dropping funnel was placed in a constant-temperature water bath. Half a volume of the pre-emulsified solution was added, and the temperature was raised to 75°C. The stirring speed was controlled at 750 rpm, and the reaction was allowed to proceed for approximately 2 hours. The remaining 0.10 parts of the initiator ammonium persulfate was then added to the remaining half volume of the pre-emulsified solution and transferred to the constant-pressure dropping funnel. As the reflux in the condenser decreased, the solution in the constant-pressure dropping funnel was added dropwise over 3 hours. The reaction was maintained at 75℃ for 2 hours. Finally, the temperature was lowered to 40℃, the pH was adjusted to 7-8 with an appropriate amount of ammonia, and the product was filtered out to obtain a milky white styrene-acrylic emulsion with a blue luster, named PAM-0.5-PG-0.15. The various physicochemical stability parameters are shown in Table 1.

[0079] (3) Pyrite coating passivation

[0080] The pyrite that had been washed with water and alcohol was immersed in the double-modified styrene-acrylic emulsion prepared in step (2), and after being magnetically stirred for 0.5 h, it was separated and left to stand at room temperature for 24 h.

[0081] The chemical composition of the double-modified styrene-acrylic emulsion tailings passivator was analyzed by infrared spectroscopy, its morphology was characterized by SEM, the particle size of the latex particles was tested, and its electrochemical performance was tested. The results were similar to those in Example 1.

[0082] Compare with Example 1

[0083] Unpassivated pyrite particles were added to 100 ml of 0.5 wt% hydrogen peroxide solution with a pH of 6.18. After reacting for 24 h, the total iron concentration was measured to be 174.3 mg / L.

[0084] Compare with Example 2

[0085] The following monomers were added sequentially to a beaker: 0.5 parts hydroxyethyl methacrylate phosphate, 16 parts styrene, 24 parts butyl acrylate, and 2 parts methyl methacrylate. Then, 0.10 parts ammonium persulfate, 0.40 parts K12, 0.48 parts SR-10, 0.14 parts sodium bicarbonate, and 60 parts deionized water were added. The mixture was then magnetically stirred for 10 minutes to obtain a well-dispersed pre-emulsified solution. A three-necked flask equipped with a magnetic stirrer, a reflux condenser, and a constant-pressure dropping funnel was placed in a constant-temperature water bath. One-third of the volume of the pre-emulsified solution was added, and the temperature was raised to 80°C. The stirring speed was controlled at 700 rpm, and the reaction was allowed to proceed for 1 hour. The remaining two-thirds volume of the pre-emulsified solution was then added to the remaining 0.10 parts of the initiator ammonium persulfate and transferred to the constant-pressure dropping funnel. As the reflux in the condenser decreased, the solution in the constant-pressure dropping funnel was added dropwise over 2 hours. The reaction was maintained at 80℃ for 1 hour. Finally, the temperature was lowered to 40℃, the pH was adjusted to 7-8 with an appropriate amount of ammonia, and the product was filtered out to obtain a milky white styrene-acrylic emulsion with a blue luster, named PAM-0.5. The various physicochemical stability parameters are shown in Table 1.

[0086] The hydroxyethyl methacrylate phosphate-modified styrene-acrylic emulsion was used to immerse pyrite that had been washed with water and alcohol. After stirring magnetically for 4 hours, the mixture was separated and left to stand at room temperature for 12 hours.

[0087] The reaction product was added to 100 ml of 0.5 wt% hydrogen peroxide solution with a pH of 6.18. After reacting for 24 h, the total iron concentration was measured to be 61.8 mg / L and the passivation efficiency was 64.5%.

[0088] Compare with Example 3

[0089] The following monomers were added sequentially to a beaker: 16 parts styrene, 24 parts butyl acrylate, and 2 parts methyl methacrylate. Then, 0.10 parts ammonium persulfate, 0.40 parts K12, 0.48 parts SR-10, 0.14 parts sodium bicarbonate, and 60 parts deionized water were added. The mixture was then magnetically stirred for 10 minutes to obtain a well-dispersed pre-emulsified solution. A three-necked flask equipped with a magnetic stirrer, a reflux condenser, and a constant-pressure dropping funnel was placed in a constant-temperature water bath. One-third of the volume of the pre-emulsified solution was added, and the temperature was raised to 80°C. The stirring speed was controlled at 700 rpm, and the reaction was allowed to proceed for 1 hour. The remaining two-thirds volume of the pre-emulsified solution was then added to the remaining 0.10 parts of the initiator ammonium persulfate and transferred to the constant-pressure dropping funnel. As the reflux in the condenser decreased, the solution in the constant-pressure dropping funnel was added dropwise over 2 hours. The reaction was maintained at 80°C for 1 hour. Finally, the temperature was lowered to 40℃, and the pH was adjusted to 7-8 with an appropriate amount of ammonia. The mixture was then filtered to obtain a milky white styrene-acrylic emulsion with a blue sheen, which was named PAM-0.

[0090] Pyrite that had been washed with water and alcohol was immersed in a styrene-acrylic emulsion modified with phosphate hydroxyethyl methacrylate without additives. After being magnetically stirred for 4 hours, the mixture was separated and left to stand at room temperature for 12 hours.

[0091] The reaction product was added to 100 ml of 0.5 wt% hydrogen peroxide solution with a pH of 6.18. After reacting for 24 h, the total iron concentration was measured to be 157.6 mg / L, and the passivation efficiency was 9.6%.

[0092] Example 5: Evaluation of the antioxidant properties of passivating agents

[0093] Antioxidant performance was evaluated using Examples 1, 2, 3, and 4 and Control Examples 1, 2, and 3.

[0094] Antioxidant experiments revealed that the total iron concentration in Example 1 after 24 hours was 24.7 mg / L, with a passivation efficiency of 85.8%, significantly lower than that in Control Examples 1 and 2. This was mainly because the phytic acid and hydroxyethyl methacrylate phosphate-modified styrene-acrylic emulsion enhanced the adhesion between the emulsion and pyrite, allowing the emulsion polymer to form more PO-Fe bonds with the iron ions on the pyrite surface, thus improving the antioxidant performance of the passivation film (e.g., ...). Figure 5 (As shown).

[0095] Table 1. Physicochemical stability of the emulsion

[0096]

[0097] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a dual-modified styrene-acrylic emulsion, characterized in that, Includes the following steps: (1) Phytic acid-modified functional monomers were prepared by reacting phytic acid, glycidyl methacrylate, a first initiator, a polymerization inhibitor and water. (2) A double-modified styrene-acrylic emulsion is prepared by reacting the phytic acid-modified functional monomer, hydroxyethyl methacrylate phosphate, styrene monomer, acrylate monomer, second initiator, emulsifier, electrolyte, and water described in step (1). The mass ratio of phytic acid-modified functional monomers to hydroxyethyl methacrylate phosphate monomers is 1:2 to 1:5, and the total mass of the two accounts for 0.6% to 1% of the total mass of the entire system. In step (2), the acrylate monomers are butyl acrylate and methyl methacrylate.

2. The preparation method according to claim 1, characterized in that, In step (1), the first initiator is tetrabutylammonium bromide; the polymerization inhibitor is hydroquinone; In step (2), the second initiator is one or more of azobisisobutyronitrile or ammonium persulfate; the emulsifier is a reactive emulsifier, allyloxyisobutyl ether sulfate SR-10 or sodium dodecyl sulfate K12; and the electrolyte is one or more of sodium bicarbonate or disodium hydrogen phosphate.

3. The preparation method according to claim 2, characterized in that, The specific operation of step (1) is as follows: add an aqueous solution containing the first initiator and the polymerization inhibitor to phytic acid and glycidyl methacrylate, and separate the phytic acid modified functional monomer at 80~95℃ for 0.5~2h. The molar ratio of phytic acid and glycidyl methacrylate is 1:6 to 1:

12. The mass ratio of the first initiator to the polymerization inhibitor is 10:

1.

4. The preparation method according to claim 3, characterized in that, The specific steps for step (2) are as follows: S1: Take the following amounts of monomers: 0.1~0.25 parts of phytic acid-modified functional monomer, 0.5 parts of hydroxyethyl methacrylate phosphate, 2 parts of methyl methacrylate, 40 parts of styrene and butyl acrylate, then add 0.10 parts of ammonium persulfate, 0.88 parts of K12 and SR-10, 0.14 parts of sodium bicarbonate and 60 parts of deionized water, and then stir and disperse for 5~30 minutes to obtain a well dispersed pre-emulsion solution; S2: Take 1 volume part of the pre-emulsified solution and carry out emulsion polymerization at 75~90℃ and 600~750rpm for 0.5~2h to obtain solution A; S3: Take 0.3~1 volume part of the pre-emulsified solution, add the second initiator to obtain solution B; add solution B dropwise to solution A within 1~3 hours, react at 75~90℃ for 0.5~2 hours; finally cool down to 40℃, adjust the pH of the solution to 7-8, filter, and obtain styrene-acrylic emulsion.

5. The preparation method according to claim 4, characterized in that, The mass ratio of reactive emulsifiers SR-10 and K12 is 5:6; The mass ratio of styrene and butyl acrylate monomers is 1:3 to 3:

2.

6. A dual-modified styrene-acrylic emulsion prepared by any one of claims 1-5.

7. The application of the dual-modified styrene-acrylic emulsion as described in claim 6 in the treatment of metal tailings pollution.

8. The application according to claim 7, characterized in that, The modified styrene-acrylic emulsion was sprayed onto the surface of the tailings and cured into a film at room temperature.

9. The application according to claim 8, characterized in that, The tailings particles have a size of 25μm to 15mm and a room temperature of 20℃ to 35℃.

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