Composite anion modified polyacrylate flocculant emulsion, its preparation method and application

Abstract

The present application relates to the technical field of water-soluble polymer emulsion, in particular to a composite anion modified polyacrylate flocculant emulsion, a preparation method and application thereof.The preparation method comprises (1) water phase preparation, (2) oil phase preparation, (3) mixed emulsification, (4) inverse emulsion polymerization, (5) emulsion monomer modification, and (6) emulsion post-treatment.The composite anion modified polyacrylate flocculant emulsion can be used in the red mud settling and washing process.The present application increases flocculation, adds polymerization aids, structural functional monomers and emulsion monomer modification processes, maximizes the content of active components, enriches the monomer functional groups, makes the molecular weight of long-chain molecules of the flocculant larger, enhances the bridging capacity and electrical neutralization performance, and improves the applicability of low aluminum-silicon ratio diaspore and the economy of alumina production.

Description

Technical Field

[0001] This invention relates to the field of water-soluble polymer emulsion technology, specifically to a composite anionic modified polyacrylate flocculant emulsion, its preparation method, and its application. Background Technology

[0002] Currently, alumina production processes are all alkaline processes, with the Bayer process being the primary method. After crushing, the raw bauxite slurry is dissolved in a leaching machine to form a leached slurry. Due to the high concentration of the leached slurry, it needs to be diluted before sedimentation and separation to form a solid and liquid two-phase mixture. The solid material is red mud, which is transported to a red mud storage yard after multiple washings. The liquid material is coarse liquid, which enters a leaf filter to further remove the entrained red mud, yielding sodium aluminate concentrate. The concentrate then enters the decomposition workshop and other subsequent processes.

[0003] The rapid separation of red mud from sodium aluminate concentrate is a key factor restricting alumina production capacity and product quality. Currently, both domestic and international alumina industries achieve rapid sedimentation and separation of red mud by adding a certain proportion of flocculant. Under the action of flocculant, the red mud particles suspended in the system are adsorbed, electrically neutralized, and bridged, agglomerating into large particles that then settle.

[0004] Although my country is rich in bauxite resources, the ore is mainly composed of gibbsite monohydrate, with a generally low aluminum-to-silicon ratio (A / S) and high levels of impurities such as ferric oxide (around 1.5%). Therefore, the red mud sedimentation and separation process requires more stringent process control, posing new challenges to existing flocculant products. Current alumina flocculants are mainly anionic polyacrylamide and sodium polyacrylate, which generally suffer from simple synthesis technology, simple structure, low activity content, and a low proportion of modified functional groups. This leads to large flocculant dosages, poor sedimentation effects, poor stability, and unsatisfactory results, sometimes even resulting in the simultaneous use of multiple flocculants. Summary of the Invention

[0005] To address the technical problems of poor solubility, large dosage, and poor sedimentation stability of existing alumina flocculants, particularly their unsatisfactory performance in the sedimentation and washing process of red mud from monohydrate gibbsite ore, this invention provides a composite anionic modified polyacrylate flocculant emulsion, its preparation method, and its application. This invention incorporates flocculation-enhancing polymerization aids, structural functional monomers, and emulsion monomer modification processes, maximizing the content of active components and enriching monomer functional groups. This results in larger molecular weights, enhanced bridging ability, and improved charge neutralization performance of the flocculant's long-chain molecules, thereby improving the applicability to low-alumina-silicon ratio monohydrate gibbsite ore and the economic efficiency of alumina production.

[0006] In a first aspect, the present invention provides a method for preparing a composite anionic modified polyacrylate flocculant emulsion, comprising the following steps:

[0007] (1) Aqueous phase preparation: First, acrylic acid is neutralized with alkaline substances and the pH value is controlled in the range of 6.5-8.0 to obtain acrylate. Then, flocculant-enhancing polymerization aid, structural functional monomer, monomer modifier, anti-crosslinking aid, molecular weight regulator and metal ion chelating agent are added and stirred in water to dissolve to obtain the aqueous phase.

[0008] The preparation method of the flocculation-enhancing polymerization aid is as follows:

[0009] Acrylic acid, long-chain hydrogen-bonded monomers, toluenesulfonic acid, and hydroquinone are added in a molar ratio of 1-5:1-2:3.5-5:1-10. The reaction temperature is controlled at 60-90℃ and the reaction time is 2-6 hours. After the reaction, the material is purified by anion exchange resin and vacuum distillation to finally obtain the flocculation-enhancing polymerization aid.

[0010] (2) Preparation of oil phase: The oil phase solvent, composite emulsifier, polymerization stabilizer and initiator are stirred and dissolved to obtain the oil phase;

[0011] (3) Mixing and emulsification: The aqueous phase is added dropwise to the oil phase, mixed, sheared and stirred, and then the oxygen in the material is removed;

[0012] (4) Reverse emulsion polymerization: Add an oxidant to the deoxygenated material, stir and mix, then add a reducing initiator dropwise, and heat to carry out the polymerization reaction;

[0013] (5) Modification of emulsion monomers: Hydroxamic acid modifier is added to the reacted material to obtain the modified semi-finished emulsion;

[0014] (6) Emulsion post-treatment: After the modified semi-finished emulsion is cooled, a demulsifier is added to obtain the final product.

[0015] Furthermore, the neutralization temperature in step (1) does not exceed 50°C, and is preferably 25-50°C.

[0016] Furthermore, the amounts of each raw material used in step (1) are as follows, by weight:

[0017] 30-90 parts by weight of deionized water, 80-150 parts by weight of acrylic acid, 85-135 parts by weight of alkaline substances, 4-7.5 parts by weight of flocculation-enhancing polymerization aid, 15-58 parts by weight of structural functional monomers, 5-12 parts by weight of monomer modifiers, 0.05-0.5 parts by weight of anti-crosslinking aid, 0.005-0.05 parts by weight of molecular weight regulator, and 0.1-2.5 parts by weight of metal ion chelating agent.

[0018] Furthermore, in step (1), the alkaline substance includes ammonia water and a second component. The second component is any one of NaOH (liquid or solid), KOH, sodium carbonate, and sodium bicarbonate. The mass ratio of ammonia water to the alkaline compound in the second component is (2:3) to (9:1).

[0019] The structural functional monomer is one or more of acrylamide, itaconic acid monomethyl ester, p-methylstyrene, p-ethylstyrene, and sulfonic acid anionic monomers;

[0020] The monomer modifier is phenylpropenyl hydroxamic acid;

[0021] The anti-crosslinking agent is sodium fatty acid or urea;

[0022] The molecular weight regulator is any one of sodium hypophosphite, tetrachloromethane, fatty thiols, and dodecyl thiols;

[0023] The metal ion chelating agent is any one of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetic acid, and pentasodium diethylenetriaminepentaacetic acid.

[0024] Furthermore, the acrylic acid used in the preparation of the flocculation-enhancing polymerization aid is acrylic acid with a content of 60%-99.5%.

[0025] Furthermore, the long-chain hydrogen-bonded monomers used in the preparation of the flocculation-enhancing polymerization aid are one or more of hexadecyl methacrylate, octadecyl acrylate, octadecyl vinyl ether, and C12-C18 fatty alcohol polyoxyethylene ethers.

[0026] Furthermore, the mixing temperature in step (2) is 15-35℃.

[0027] Furthermore, the amounts of each raw material used in step (2) are as follows, by weight:

[0028] 80-150 parts by weight of oil phase solvent, 10.5-25 parts by weight of composite emulsifier, 0.5-2.5 parts by weight of polymerization stabilizer, and 0.085-0.135 parts by weight of initiator.

[0029] Furthermore, in step (2), the oil phase solvent is one or more of liquid paraffin, white oil, solvent oil, and cyclohexane;

[0030] The composite emulsifier includes Span emulsifiers and Tween emulsifiers in a mass ratio of 0.2-2:1. The Span emulsifier can be one or more of Span 20, Span 60, Span 80, and Span 85, and the Tween emulsifier can be one or more of Tween 20, Tween 60, and Tween 80. The composite emulsifier meets the requirement of an HLB value of 5-9.

[0031] The polymerization stabilizer is one or more of Hypermer B246SF, Hypermer 1599, Hypermer 2234, Hypermer 2296, and Hypermer 2524;

[0032] The initiator is one or more of azobisisobutyronitrile, azobisisobutyrimidazole hydrochloride, azobisisobutyramidine hydrochloride, azobisisopropylimidazoline, and azobiscyanopentanoic acid.

[0033] Furthermore, the specific method for mixing and emulsifying in step (3) is as follows:

[0034] Add the aqueous phase to the oil phase at a dropping rate of 50 mL to 300 L / min. After mixing, shear and stir the material for 20 to 60 minutes until the emulsified viscosity of the material after shearing reaches 500 cPs or more (preferably 500 to 2500 cPs). Purge the material with an inert gas (preferably nitrogen) for 30 to 90 minutes to remove oxygen.

[0035] Furthermore, the specific method for reverse emulsion polymerization in step (4) is as follows:

[0036] Add 0.001-0.002 parts by weight of oxidant to the deoxygenated material, stir and mix for 5-30 minutes, then add 0.0001-0.0008 parts by weight of reduction initiator dropwise. Control the heating rate to 50-200 seconds / 1℃, and keep the temperature in the range of 50-65℃ for polymerization until the reaction is completed.

[0037] Furthermore, in step (4), the oxidant is one or more of ammonium persulfate, sodium persulfate, potassium persulfate, and tert-butyl hydroperoxide; the reduction initiator is one or two of sodium metabisulfite, sodium bisulfite, sodium sulfite, and potassium bisulfite.

[0038] Furthermore, the specific method for modifying the emulsion monomer in step (5) is as follows:

[0039] Add 18.5-35 parts by weight of hydroxamic acid modifier to the reacted material, control the modification reaction temperature at 65-85℃, and the modification reaction time at 1-12 hours to obtain the modified semi-finished emulsion.

[0040] Furthermore, in step (5), the hydroxamic acid modifier is one or more of hydroxylamine, hydroxylamine hydrochloride, and hydroxylamine sulfate.

[0041] Furthermore, the specific method for post-treatment of the emulsion in step (6) is as follows:

[0042] After the transfer reaction is complete, wait for the material to cool to 40-45℃, add 11-25 parts by weight of demulsifier and stir for 15-30 minutes to obtain the final product.

[0043] Furthermore, the demulsifier is one or more of nonylphenol polyoxyethylene ether, polyoxyethylene ether sorbitan lauryl ester, isotridecyl alcohol polyoxyethylene ether, and octylphenol polyoxyethylene ether.

[0044] Secondly, the present invention provides a composite anionic modified polyacrylate flocculant emulsion prepared by the above preparation method.

[0045] Furthermore, the flocculation-enhancing polymerization aid accounts for 1.0wt%-2.0wt% of the composite anionic modified polyacrylate flocculant emulsion.

[0046] Thirdly, the present invention also provides an application of the above-mentioned composite anionic modified polyacrylate flocculant emulsion in red mud settling and washing.

[0047] The beneficial effects of this invention are as follows:

[0048] (1) This invention introduces a long-chain water-soluble flocculant-enhancing polymerization aid that participates in the polymerization process. This aid contains abundant hydrogen-bonded functional groups, which enhances the water solubility of the flocculant. Simultaneously, the composite anionic modified polyacrylate flocculant emulsion obtained by controlling the reaction process has the aid dispersed in the form of intercalators on the flocculant molecular chains. Due to the influence of charge repulsion, this facilitates the extension of the long-chain flocculant molecules in the sodium aluminate solution, significantly improving the "capture" ability and bridging performance of red mud particles, resulting in high flocculation efficiency and fast sedimentation speed. Furthermore, the introduction of the aid increases the flocculant's tolerance under strong alkaline and strong electrolyte conditions, enhancing the structural stability of the flocculant.

[0049] (2) The composite anionic modified polyacrylate flocculant emulsion obtained in this invention has diverse structural and functional monomers and abundant flocculation functional groups. In addition to traditional amide groups, the flocculant emulsion contains carboxylic acid groups, ester groups, benzene ring groups, sulfonic acid groups, and hydroxamic acid groups. The introduction of these functional groups greatly improves the flocculant's interception rate for metal ions, which is beneficial for metal enrichment and deep separation, and greatly improves the turbidity of the supernatant overflow, resulting in a lower content of suspended solids in the supernatant. The superior performance of the product of this invention in metal ion enrichment and deep flocculation separation is significant in bauxite mines both domestically and internationally, especially solving the current problem of high iron content and high suspended solids in domestic bauxite.

[0050] (3) The active component content of the composite anionic modified polyacrylate flocculant emulsion is 40.02%-54%, which is higher than that of flocculant products reported at home and abroad. At the same time, the production process is simple, and the emission of toxic and harmful gases can be avoided by selecting the technical route. The production energy consumption is low and the economic benefits are high. Detailed Implementation

[0051] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0052] Example 1: Preparation of composite anionic modified polyacrylate flocculant emulsion one

[0053] (1) Preparation of aqueous phase: 35g of deionized water and 95g of 99.5% acrylic acid were added to a stirred reactor at 500r / min. The reaction temperature was controlled to not exceed 35℃. First, 75g of 28% ammonia water was slowly added dropwise, and then 10.5g of 30% liquid alkali was added dropwise. The final pH value was controlled to be in the range of 6.5-6.6 to obtain acrylate. Then, 4.2g of flocculant-enhancing polymerization aid, 25.2g of acrylamide aqueous solution (80% content), 5g of itaconic acid monomethyl ester, 5g of phenylpropenyl hydroxamic acid, 0.05g of sodium fatty acid, 0.0055g of sodium hypophosphite, and 0.12g of ethylenediaminetetraacetic acid were added to the reactor and stirred to dissolve for 20 minutes to obtain the aqueous phase.

[0054] The preparation method of the flocculation-enhancing polymerization aid is as follows:

[0055] Weigh 2.5g of 90% acrylic acid, and then sequentially add acrylic acid and long-chain hydrogen-bonded monomer C. 12 H 25 -O-(CH2CH2O) 10 -H, toluenesulfonic acid, and hydroquinone were added in a molar ratio of 1:1:3.8:6. The reaction temperature was controlled at 69℃ and the reaction was carried out for 5 hours. The reacted material was purified by anion exchange resin and vacuum distillation to finally obtain 12.5g of water-soluble fatty alcohol polyoxyethylene ether acrylate flocculation enhancement polymerization aid.

[0056] (2) Preparation of oil phase: 90g of white oil was added to a stirred reactor at 400r / min, followed by 6.8g of Span 60, 4.7g of Tween 80, 1g of Hypermer 2234 stabilizer, and 0.09g of azobisisobutyronitrile. The mixture was stirred at 25°C for 20 minutes to dissolve the oil phase.

[0057] (3) Mixing and emulsification: The above aqueous phase material is slowly added to the oil phase material at a dropping rate of 50 mL / min, and the process temperature is maintained at 25-30℃. After mixing, the material is sheared and stirred for 30 minutes. The emulsion viscosity is >1500 cPs. Then, nitrogen is purged for 30 minutes to remove oxygen from the material.

[0058] (4) Reverse emulsion polymerization: Under nitrogen protection, add 0.0012 g of tert-butyl hydrogen peroxide to the above materials, continue stirring for 5 minutes, then add 0.0002 g of sodium metabisulfite at a concentration of 5 g / L, maintain the heating rate in the range of 50-200 seconds / 1℃, and control the temperature of the reaction to 50-55℃ through refrigeration until the reaction is completed;

[0059] (5) Modification of emulsion monomers: The temperature of the reacted material is raised to 70-75℃, 19g of hydroxylamine sulfate is added, and the mixture is kept warm and aged for 5 hours to obtain the modified semi-finished emulsion.

[0060] (6) Post-treatment of emulsion: After the reaction is completed, the material is transferred and cooled to 40-45℃. 12g of nonylphenol polyoxyethylene ether is added and stirred for 30 minutes to obtain composite anionic modified polyacrylate flocculant emulsion product one.

[0061] Example 2: Preparation of composite anionic modified polyacrylate flocculant emulsion II

[0062] (1) Preparation of aqueous phase: 40g of deionized water and 120g of 95% acrylic acid were added to a stirred reactor at 500r / min. The reaction temperature was controlled to not exceed 30℃. First, 90g of 28% ammonia water was slowly added dropwise, and then 11.4g of 50% potassium hydroxide solution was added dropwise. The final pH value was controlled to be in the range of 6.9-7.0 to obtain acrylate. Then, 5.8g of flocculant-enhancing polymerization aid, 30g of acrylamide aqueous solution (80% content), 6g of p-methylstyrene, 8g of phenylpropenyl hydroxamic acid, 0.05g of urea, 0.0064g of sodium hypophosphite, and 0.22g of ethylenediaminetetraacetic acid were added to the reactor and stirred to dissolve for 20 minutes to obtain the aqueous phase.

[0063] The preparation method of the flocculation-enhancing polymerization aid is as follows:

[0064] Weigh 4.2g of 90% acrylic acid, and then sequentially add acrylic acid and the long-chain hydrogen-bonded monomer C. 14 H 29 -O-(CH2CH2O) 15 -H, toluenesulfonic acid, and hydroquinone were added in a molar ratio of 1:1:5:4. The reaction temperature was controlled at 80℃ and the reaction was carried out for 5 hours. The reacted material was purified by anion exchange resin and vacuum distillation to finally obtain 16.5g of water-soluble fatty alcohol polyoxyethylene ether acrylate flocculation enhancement polymerization aid.

[0065] (2) Preparation of oil phase: 100g of cyclohexane was added to a stirred reactor at 500r / min, followed by 8g of Span 80, 6.5g of Tween 60, 1.5g of Hypermer 2296 stabilizer and 0.1g of azobisisobutyronitrile. The mixture was stirred at 25°C for 20 minutes to dissolve the mixture and obtain the oil phase.

[0066] (3) Mixing and emulsification: The above aqueous phase material is slowly added to the oil phase material at a dropping rate of 60 mL / min, and the process temperature is maintained at 25-30℃. After mixing, the material is sheared and stirred for 30 minutes. The emulsion viscosity is >1500 cPs. Then, nitrogen is purged for 30 minutes to remove oxygen from the material.

[0067] (4) Reverse emulsion polymerization: Under nitrogen protection, add 0.0012 g of sodium persulfate to the above materials, continue stirring for 5 minutes, then add 0.0001 g of sodium bisulfite at a concentration of 15 g / L, maintain the heating rate in the range of 150-200 seconds / 1℃, and control the temperature of the reaction to 50-58℃ through cooling until the reaction is completed;

[0068] (5) Modification of emulsion monomers: The temperature of the reacted material is raised to 70-75℃, 23.5g of hydroxylamine hydrochloride is added, and the mixture is kept warm and aged for 8 hours to obtain the modified semi-finished emulsion.

[0069] (6) Post-treatment of emulsion: After the reaction is completed, the material is transferred and cooled to 40-45℃. 14.1g of isomeric tridecyl alcohol polyoxyethylene ether is added and stirred for 15 minutes to obtain composite anionic modified polyacrylate flocculant emulsion product two.

[0070] Example 3: Preparation of composite anionic modified polyacrylate flocculant emulsion III

[0071] (1) Preparation of aqueous phase: 40g of deionized water and 130g of 99.5% acrylic acid were added to a stirred reactor at 300r / min. The reaction temperature was controlled to not exceed 25℃. First, 104g of 28% ammonia water was slowly added dropwise, and then 6.8g of 50% liquid alkali was added dropwise. The final pH value was controlled to be in the range of 7.0-7.1 to obtain acrylate. Then, 7.3g of flocculant-enhancing polymerization aid, 38.5g of acrylamide aqueous solution (60% content), 6g of p-ethylstyrene, 9.5g of phenylpropenyl hydroxamic acid, 0.06g of urea, 0.0073g of sodium hypophosphite, and 0.29g of diethylenetriaminepentaacetic acid pentasodium were added to the reactor and stirred to dissolve for 20 minutes to obtain the aqueous phase.

[0072] The preparation method of the flocculation-enhancing polymerization aid is as follows:

[0073] Weigh 5.5g of 80% acrylic acid, and then sequentially add acrylic acid and the long-chain hydrogen-bonded monomer C. 16 H 33 -O-(CH2CH2O) 15-H, toluenesulfonic acid, and hydroquinone were added in a molar ratio of 1:2:5:4. The reaction temperature was controlled at 75℃, and the reaction time was controlled at 6 hours. The reacted material was purified by anion exchange resin and vacuum distillation to finally obtain 23.1g of water-soluble fatty alcohol polyoxyethylene ether acrylate flocculation enhancement polymerization aid.

[0074] (2) Preparation of oil phase: 118g of cyclohexane was added to a stirred reactor at 380r / min, followed by 10.5g of Span 80, 8g of Tween 60, 2.2g of Hypermer B246SF stabilizer, and 0.16g of azobisisobutyronitrile. The mixture was stirred at 25°C for 20 minutes to dissolve the mixture and obtain the oil phase.

[0075] (3) Mixing and emulsification: The above aqueous phase material is slowly added to the oil phase material at a dropping rate of 100 mL / min, and the process temperature is maintained at 25-30℃. After mixing, the material is sheared and stirred for 30 minutes. The emulsion viscosity is >1500 cPs. Then, nitrogen is purged for 30 minutes to remove oxygen from the material.

[0076] (4) Reverse emulsion polymerization: Under nitrogen protection, add 0.002g of ammonium persulfate to the above materials, continue stirring for 15 minutes, then add 0.0005g of sodium bisulfite at 30g / L dropwise, maintain the heating rate in the range of 50-80 seconds / 1℃, and control the temperature of the reaction to 60-65℃ through cooling control until the reaction is completed;

[0077] (5) Modification of emulsion monomers: The temperature of the reacted material is raised to 70-75℃, 25.3g of hydroxylamine hydrochloride is added, and the mixture is kept warm and aged for 5 hours to obtain the modified semi-finished emulsion.

[0078] (6) Post-treatment of emulsion: After the reaction is completed, the material is transferred and cooled to 40-45℃. 13.5g of polyoxyethylene ether sorbitan laurate is added and stirred for 20 minutes to obtain composite anionic modified polyacrylate flocculant emulsion product three.

[0079] Example 4: Preparation of composite anionic modified polyacrylate flocculant emulsion four

[0080] (1) Preparation of aqueous phase: 30g of deionized water and 145g of 99.5% acrylic acid were added to a stirred reactor at 420r / min. The reaction temperature was controlled to not exceed 25℃. First, 121g of 27% ammonia water was slowly added dropwise, and then 7.3g of 50% liquid alkali was added dropwise. The final pH value was controlled to be in the range of 7.5-7.6 to obtain acrylate. Then, 7.5g of flocculant-enhancing polymerization aid, 52.5g of acrylamide aqueous solution (90% content), 8.8g of itaconic acid monomethyl ester, 11.6g of phenylpropenyl hydroxamic acid, 0.03g of sodium fatty acid, 0.008g of sodium hypophosphite, and 0.35g of diethylenetriaminepentaacetic acid pentasodium salt were added to the reactor and stirred to dissolve for 20 minutes to obtain the aqueous phase.

[0081] The preparation method of the flocculation-enhancing polymerization aid is as follows:

[0082] Weigh 5.5g of 90% acrylic acid, and then sequentially add acrylic acid and the long-chain hydrogen-bonded monomer C. 16 H 33 -O-(CH2CH2O) 25 -H, toluenesulfonic acid, and hydroquinone were added in a molar ratio of 1:1.5:4:3.5. The reaction temperature was controlled at 82℃, and the reaction time was controlled at 5 hours. The reacted material was purified by anion exchange resin and vacuum distillation to finally obtain 21.9g of water-soluble fatty alcohol polyoxyethylene ether acrylate flocculation enhancement polymerization aid.

[0083] (2) Preparation of oil phase: 120g of liquid paraffin was added to a stirred reactor at 500r / min, followed by 12.4g of Span 60, 8.5g of Tween 80, 2.5g of Hypermer 1599 stabilizer, and 0.13g of azobisisobutyronitrile. The mixture was stirred at 25°C for 20 minutes to dissolve the paraffin and obtain the oil phase.

[0084] (3) Mixing and emulsification: The above aqueous phase material is slowly added to the oil phase material at a dropping rate of 120 mL / min, and the process temperature is maintained at 25-30℃. After mixing, the material is sheared and stirred for 30 minutes. The emulsion viscosity is >1200 cPs. Then, nitrogen is purged for 30 minutes to remove oxygen from the material.

[0085] (4) Reverse emulsion polymerization: Under nitrogen protection, add 0.002g of ammonium persulfate to the above materials and continue stirring for 15 minutes. Then add 0.0008g of sodium bisulfite at a concentration of 30g / L. Maintain the heating rate in the range of 50-80 seconds / 1℃. Control the temperature of the reaction to 45-50℃ through cooling until the reaction is completed.

[0086] (5) Modification of emulsion monomers: The temperature of the reacted material is raised to 70-75℃, 32.7g of hydroxylamine hydrochloride is added, and the mixture is kept warm and aged for 8 hours to obtain the modified semi-finished emulsion.

[0087] (6) Post-treatment of emulsion: After the reaction is completed, the material is transferred and cooled to 40-45℃. 10.1g of polyoxyethylene ether sorbitan laurate and 6.4g of octylphenol polyoxyethylene ether are added and stirred for 30 minutes to obtain composite anionic modified polyacrylate flocculant emulsion product four.

[0088] Comparative Example 1: Preparation of polyacrylate flocculant emulsion without flocculant-enhancing polymerization aid

[0089] (1) Preparation of aqueous phase: 40g of deionized water and 120g of 95% acrylic acid were added to a stirred reactor at 500r / min. The reaction temperature was controlled to not exceed 30℃. First, 90g of 28% ammonia water was slowly added dropwise, and then 11.4g of 50% potassium hydroxide solution was added dropwise. The final pH value was controlled to be in the range of 6.9-7.0 to obtain acrylate. Then, 30g of acrylamide aqueous solution (80% content), 6g of p-methylstyrene, 8g of phenylpropenyl hydroxamic acid, 0.05g of urea, 0.0064g of sodium hypophosphite, and 0.22g of ethylenediaminetetraacetic acid were added to the reactor and stirred to dissolve for 20 minutes to obtain the aqueous phase.

[0090] (2) Preparation of oil phase: 96g of cyclohexane was added to a stirred reactor at 500r / min, followed by 8g of Span 80, 6.5g of Tween 60, 1.5g of Hypermer 2296 stabilizer and 0.1g of azobisisobutyronitrile. The mixture was stirred at 25°C for 20 minutes to dissolve the mixture and obtain the oil phase.

[0091] (3) Mixing and emulsification: The above aqueous phase material is slowly added to the oil phase material at a dropping rate of 60 mL / min, and the process temperature is maintained at 25-30℃. After mixing, the material is sheared and stirred for 30 minutes. The emulsion viscosity is >1500 cPs. Then, nitrogen is purged for 30 minutes to remove oxygen from the material.

[0092] (4) Reverse emulsion polymerization: Under nitrogen protection, add 0.0012 g of sodium persulfate to the above materials, continue stirring for 5 minutes, then add 0.0001 g of sodium bisulfite at a concentration of 15 g / L, maintain the heating rate in the range of 150-200 seconds / 1℃, and control the temperature of the reaction to 50-58℃ through cooling until the reaction is completed;

[0093] (5) Modification of emulsion monomers: The temperature of the reacted material is raised to 70-75℃, 23.5g of hydroxylamine hydrochloride is added, and the mixture is kept warm and aged for 8 hours to obtain the modified semi-finished emulsion.

[0094] (6) Post-emulsion treatment: After the reaction is completed, the material is transferred and cooled to 40-45℃. 14.1g of isomeric tridecyl alcohol polyoxyethylene ether is added and stirred for 15 minutes to obtain a polyacrylate flocculant emulsion product without the addition of water-soluble flocculant to enhance polymerization.

[0095] Comparative Example 2: Preparation of flocculant emulsions with conventional carboxylic acid-amide groups

[0096] (1) Preparation of aqueous phase: 37g of deionized water and 120g of 95% acrylic acid were added to a stirred reactor at 500r / min. The reaction temperature was controlled to not exceed 30℃. First, 90g of 28% ammonia water was slowly added dropwise, and then 11.4g of 50% potassium hydroxide was added dropwise. The final pH value was controlled to be in the range of 6.9-7.0 to obtain acrylate. Then, 30g of acrylamide aqueous solution (80% content), 0.05g of urea, 0.0064g of sodium hypophosphite and 0.22g of ethylenediaminetetraacetic acid were added to the reactor and stirred to dissolve for 20 minutes to obtain the aqueous phase.

[0097] (2) Preparation of oil phase: 96g of cyclohexane was added to a stirred reactor at 500r / min, followed by 8g of Span 80, 6.5g of Tween 60, 1.5g of Hypermer 2296 stabilizer and 0.1g of azobisisobutyronitrile. The mixture was stirred at 25°C for 20 minutes to dissolve the mixture and obtain the oil phase.

[0098] (3) Mixing and emulsification: The above aqueous phase material is slowly added to the oil phase material at a dropping rate of 60 mL / min, and the process temperature is maintained at 25-30℃. After mixing, the material is sheared and stirred for 30 minutes. The emulsion viscosity is >1500 cPs. Then, nitrogen is purged for 30 minutes to remove oxygen from the material.

[0099] (4) Reverse emulsion polymerization: Under nitrogen protection, add 0.0012 g of sodium persulfate to the above materials, continue stirring for 5 minutes, then add 0.0001 g of sodium bisulfite at a concentration of 15 g / L, maintain the heating rate in the range of 150-200 seconds / 1℃, and control the temperature of the reaction to 50-58℃ through cooling until the reaction is completed;

[0100] (5) Post-emulsion treatment: After the reaction is completed, the material is transferred and cooled to 40-45℃. 14.1g of isomeric tridecyl alcohol polyoxyethylene ether is added and stirred for 15 minutes to obtain the flocculant emulsion product of traditional carboxylic acid-amide group.

[0101] Application examples

[0102] The flocculant emulsion products obtained in Examples 1-4 and Comparative Examples 1-2, as well as KM721 supplied by a domestic manufacturer, were used in the red mud settling process of monohydrate gibbsite mines. The red mud slurry used in the experiments was freshly obtained from an alumina plant, and its index analysis is shown in Table 1 below.

[0103] Table 1. Red mud slurry index

[0104]

[0105] To ensure that all experimental flocculant emulsion products are subjected to red mud sedimentation under the same conditions, the following steps are taken:

[0106] (1) First, take 200mL of flocculant preparation water from the sedimentation workshop and put it into a 500mL plastic bottle. Then, use a 1mL syringe to take 0.6mL of flocculant and add it to the preparation water. Shake the bottle quickly to allow the flocculant to dissolve fully in the preparation water until there are no flocculent clumps in the water, and obtain 3‰ liquid flocculant.

[0107] (2) Take 1L of diluted slurry and put it into a graduated cylinder of the corresponding volume. Stir it quickly 4-5 times with a stirring rod. Then, take 3mL of the prepared 3‰ liquid flocculant with a 5mL syringe and add it to the diluted slurry. Stir it slowly 4-5 times with a stirring rod until the flocculant is fully added to the diluted slurry. Start timing with a stopwatch when the stirring rod is removed and record the height of the clear liquid layer corresponding to each time point. The graduated cylinder scale value gradually increases from top to bottom.

[0108] The experimental results are shown in Table 2 below.

[0109] Table 2. Graduated cylinder graduations (in mL) for the clear liquid layer at each time point.

[0110]

[0111] The results above show that, at each detection time point, the liquid level on the supernatant in Examples 1-4 corresponds to a larger graduation on the measuring cylinder than that in Comparative Examples 1-2 and KM721, indicating that the red mud treated in Examples 1-4 has a faster settling speed and better compressibility. This is because the addition of long-chain water-soluble flocculant-enhancing polymerization aids participates in the polymerization reaction, resulting in the formation of abundant hydrogen-bonded functional groups in the flocculant emulsion, thus enhancing the water solubility of the flocculant. Simultaneously, the introduction of various functional monomers demonstrates significant advantages in settling performance and supernatant suspended solids content through comparison.

[0112] In addition, the active content of the product of this invention is higher than that of products sold at home and abroad. The solid content of the products of Examples 1-4, Comparative Examples 1-2 and KM721 were tested according to the national standard testing method, and the results are shown in Table 3 below.

[0113] Table 3 Solid content of various flocculant emulsion products

[0114]

[0115] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A method for preparing a composite anionic modified polyacrylate flocculant emulsion, characterized in that, Includes the following steps: (1) Aqueous phase preparation: First, acrylic acid is neutralized with alkaline substances and the pH value is controlled in the range of 6.5-8.0 to obtain acrylate. Then, flocculant-enhancing polymerization aid, structural functional monomer, monomer modifier, anti-crosslinking aid, molecular weight regulator and metal ion chelating agent are added and stirred in water to dissolve to obtain the aqueous phase. The preparation method of the flocculation-enhancing polymerization aid is as follows: Acrylic acid, long-chain hydrogen-bonded monomers, toluenesulfonic acid, and hydroquinone are added in a molar ratio of 1-5:1-2:3.5-5:1-10. The reaction temperature is controlled at 60-90℃ and the reaction time is 2-6 hours. After the reaction, the material is purified by anion exchange resin and vacuum distillation to finally obtain the flocculation-enhancing polymerization aid. The long-chain hydrogen-bonded monomers are one or more of the C12-C18 fatty alcohol polyoxyethylene ethers; The structural functional monomer is a combination of acrylamide with any one of the following three: itaconic acid monomethyl ester, p-methylstyrene, or p-ethylstyrene; The monomer modifier is phenylpropenyl hydroxamic acid; (2) Preparation of oil phase: The oil phase solvent, composite emulsifier, polymerization stabilizer and initiator are stirred and dissolved to obtain the oil phase; (3) Mixing and emulsification: The aqueous phase is added dropwise to the oil phase, mixed, sheared and stirred, and then the oxygen in the material is removed; (4) Reverse emulsion polymerization: Add an oxidant to the deoxygenated material, stir and mix, then add a reducing initiator dropwise, and heat to carry out the polymerization reaction; (5) Modification of emulsion monomers: Hydroxamic acid modifier is added to the reacted material to obtain the modified semi-finished emulsion; (6) Emulsion post-treatment: After the modified semi-finished emulsion is cooled, a demulsifier is added to obtain the final product.

2. The preparation method according to claim 1, characterized in that, The amounts of each raw material used in step (1) are as follows, by weight: 30-90 parts by weight of deionized water, 80-150 parts by weight of acrylic acid, 85-135 parts by weight of alkaline substances, 4-7.5 parts by weight of flocculant-enhancing polymerization aid, 15-58 parts by weight of structural and functional monomers, 5-12 parts by weight of monomer modifier, 0.05-0.5 parts by weight of anti-crosslinking aid, 0.005-0.05 parts by weight of molecular weight regulator, and 0.1-2.5 parts by weight of metal ion chelating agent; The alkaline substance includes ammonia water and a second component, which is any one of NaOH, KOH, sodium carbonate, and sodium bicarbonate. The anti-crosslinking agent is sodium fatty acid or urea; The molecular weight regulator is any one of sodium hypophosphite, tetrachloromethane, fatty thiols, and dodecyl thiols; The metal ion chelating agent is any one of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetic acid, and pentasodium diethylenetriaminepentaacetic acid.

3. The preparation method according to claim 1, characterized in that, The amounts of each raw material used in step (2) are as follows, by weight: Oil phase solvent 80-150 parts by weight, composite emulsifier 10.5-25 parts by weight, polymerization stabilizer 0.5-2.5 parts by weight, initiator 0.085-0.135 parts by weight; The oil phase solvent is one or more of liquid paraffin, white oil, solvent oil, and cyclohexane; Composite emulsifiers include Span-type emulsifiers and Tween-type emulsifiers with a mass ratio of 0.2-2:1; The polymerization stabilizer is one or more of Hypermer B246SF, Hypermer 1599, Hypermer 2234, Hypermer 2296, and Hypermer 2524; The initiator is one or more of azobisisobutyronitrile, azobisisobutyrimidazole hydrochloride, azobisisobutyramidine hydrochloride, azobisisopropylimidazoline, and azobiscyanopentanoic acid.

4. The preparation method according to claim 1, characterized in that, The specific method for mixing and emulsifying in step (3) is as follows: Add the aqueous phase to the oil phase at a dropping rate of 50 mL to 300 L / min. After mixing, shear and stir the material for 20 to 60 minutes to make the emulsion viscosity of the material after shearing reach more than 500 cPs. Purge with inert gas for 30 to 90 minutes to remove oxygen from the material.

5. The preparation method according to claim 1, characterized in that, The specific method for reverse emulsion polymerization in step (4) is as follows: Add 0.001-0.002 parts by weight of oxidant to the deoxygenated material, stir and mix for 5-30 minutes, then add 0.0001-0.0008 parts by weight of reduction initiator dropwise. Control the heating rate to 50-200 seconds / 1℃, and keep the temperature in the range of 50-65℃ for polymerization until the reaction is completed. The oxidant is one or more of ammonium persulfate, sodium persulfate, potassium persulfate, and tert-butyl hydroperoxide; the reduction initiator is one or two of sodium metabisulfite, sodium bisulfite, sodium sulfite, and potassium bisulfite.

6. The preparation method according to claim 1, characterized in that, The specific method for modifying the emulsion monomer in step (5) is as follows: Add 18.5-35 parts by weight of hydroxamic acid modifier to the reacted material, control the modification reaction temperature at 65-85℃, and the modification reaction time at 1-12 hours to obtain the modified semi-finished emulsion. The hydroxamic acid modifier is one or more of hydroxylamine, hydroxylamine hydrochloride, and hydroxylamine sulfate.

7. The preparation method according to claim 1, characterized in that, The specific method for post-treatment of the emulsion in step (6) is as follows: After the transfer reaction is complete, wait for the material to cool to 40-45℃, add 11-25 parts by weight of demulsifier and stir for 15-30 minutes to obtain the final product. The demulsifier is one or more of nonylphenol polyoxyethylene ether, polyoxyethylene ether sorbitan lauryl ester, isotridecyl alcohol polyoxyethylene ether, and octylphenol polyoxyethylene ether.

8. A composite anionic modified polyacrylate flocculant emulsion prepared by any one of the preparation methods described in claims 1-7.

9. The application of the composite anionic modified polyacrylate flocculant emulsion as described in claim 8 in the settling and washing of red mud.

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