Liquid type ultra-high cationic water purifying agent for treating mine wastewater as well as preparation and application of liquid type ultra-high cationic water purifying agent

Abstract

The invention discloses a liquid type ultra-high cationic water purifying agent for treating mine wastewater. The liquid type ultra-high cationic water purifying agent is mainly prepared by stably dispersing an AM-DM oily emulsion copolymer and a PDM homopolymer in an oily solvent under the action of an emulsifier, the water purifying agent comprises the following components in parts by weight: 11-15 parts of an AM-DM oily emulsion copolymer containing an AM-DM copolymer, 60-65 parts of a PDM homopolymer, 2-3 parts of an emulsifier and the balance of an oily solvent, the AM-DM oily emulsion copolymer is obtained by emulsifying an AM-DM copolymer through an oily solvent. The ultrahigh cationic water purifying agent can maintain the stability and uniformity of the ultrahigh cationic charge density while improving the molecular weight and viscosity of the water purifying agent product, and can significantly improve the treatment effect when being used for treating mine wastewater, so that the supernatant of the treated wastewater is clear and transparent, and the treatment cost can be greatly reduced; the positive market application value is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of water purifying agents for treating mine wastewater, and specifically to a liquid ultra-high cation water purifying agent for treating mine wastewater, as well as the preparation and application of the water purifying agent. Background Art

[0002] Mine wastewater is the wastewater discharged during the process of mine exploitation. It not only contains suspended substances such as gangue and pulverized coal with a solid content of about 7% - 8%, but also has relatively high amounts of heavy metals, ammonia nitrogen, phosphorus, COD and other organic substances, which seriously pollute the environment. To maintain the ecological balance and protect the environment, it is necessary to treat the wastewater before discharge to meet the discharge standards. Currently, ordinary deep cone sedimentation technology is often used to treat mine wastewater, and a water purifying agent is used in combination to achieve clarification and purification through rapid sedimentation. However, due to the large amount of mine wastewater, large fluctuations in water quality, and being restricted by the mine geographical environment and the limited space at the construction site, the treated wastewater fluctuates greatly, especially the suspended solids (turbidity) index changes significantly, directly affecting the discharge.

[0003] The pulverized coal or ore powder particles contained in mine wastewater generally carry negative charges. However, due to its large molecular weight and relatively low charge density, cationic polyacrylamide PAM will make the water quality sticky and stringy after treating mine wastewater. Even if the usage amount is reduced, the clear liquid is still sticky and the flocs are dispersed, which is not suitable for the treatment of mine wastewater; anion polyacrylamide PAM cannot be used alone as a water purifying agent for mine wastewater either, because using anion PAM alone will repel the charges in mine wastewater and cannot complete the functions of adsorption, sweeping and flocculation; therefore, currently, anion PAM and polyaluminum chloride (PAC) are often used in combination as water purifying agents. PAC provides high ionic strength, and PAM provides high molecular weight. Through the combination of the two, bridging and charge neutralization reactions occur with the charged particles in mine wastewater to achieve the purification purpose. However, the mine wastewater treated with anion PAM and PAC still has problems of fine particulate matter suspension and high turbidity. To further reduce the turbidity to ensure the purification effect of the wastewater, only the addition amounts of PAM and PAC can be increased. Since the addition amounts of PAM and PAC need to be strictly in proportion, and in the actual wastewater treatment process, the on-site operation environment is relatively harsh, the raw material PAC is prone to absorb moisture and agglomerate, and the dosing operation is rough, resulting in a large deviation in the dosing ratio, making the wastewater treatment result unstable and often causing non-compliance phenomena. If a liquid single agent with good purification effect on mine wastewater can be developed, it will have a positive effect on promoting the application of automated wastewater treatment systems in mine wastewater treatment and improving the level of mine wastewater treatment. Summary of the Invention

[0004] To address the deficiencies of the above-mentioned existing technologies, the present invention provides a liquid ultra-high cationic water purifying agent for treating mine wastewater. It can increase the molecular weight and viscosity of the water purifying agent product while maintaining the stable uniformity of the ultra-high cationic charge density. When used for treating mine wastewater, it can significantly improve the wastewater treatment effect, making the supernatant of the treated wastewater clear and transparent, and greatly reducing the treatment cost, having positive market application value.

[0005] To achieve the above object, the liquid ultra-high cationic water purifying agent for treating mine wastewater provided by the present invention is mainly prepared by stably dispersing an AM-DM oil-based emulsion copolymer and a PDM homopolymer in an oil-based solvent under the action of an emulsifier; the water purifying agent includes the following components:

[0006] 11-15 parts of an AM-DM oil-based emulsion copolymer containing an AM-DM copolymer, 60-65 parts of a PDM homopolymer, 2-3 parts of an emulsifier, and the rest is an oil-based solvent;

[0007] The AM-DM oil-based emulsion copolymer is obtained by emulsifying an AM-DM copolymer with an oil-based solvent;

[0008] The mass ratio of the AM-DM copolymer in the total mass of the AM-DM oil-based emulsion copolymer does not exceed 50%, and the mass sum of the AM-DM copolymer and the PDM homopolymer in the total mass of the water purifying agent does not exceed 50%;

[0009] The rotational viscosity of the AM-DM copolymer is 60000-270000 mPa·s; the rotational viscosity of the PDM homopolymer is above 60000 mPa·s.

[0010] As a limitation to the above technical solution, the cationicity of the AM-DM copolymer ≥60%, the cationicity of the water purifying agent ≥85%, and the molecular weight of the water purifying agent is 1 million - 3 million.

[0011] Cationicity refers to the cationic charge density, which is an index describing the number of cations in a cationic polymer solution. Its size reflects the charge amount and dissociation degree of the cationic polymer. Generally, the cationicity of a cationic solution is between 20% and 50%. This application breaks through the limitation of the conventional cationicity, uses an AM-DM copolymer and a PDM homopolymer with a cationicity ≥60% for composite emulsification to form a liquid water purifying agent with a cationicity ≥85%. While maintaining the stable uniformity of the ultra-high cationic charge density, it significantly increases the molecular weight and viscosity of the water purifying agent product, realizing the performance of both high cationicity and high molecular weight in a single liquid water purifying agent product.

[0012] The monomer DM has 100% cationic charge. However, due to its own structure, its activity is poor, and the homopolymer PDM is difficult to reach a ultra-high molecular weight of more than 3 million. Therefore, in the present invention, AM is used as the backbone to copolymerize with DM, and the obtained AM-DM copolymer can reach an ultra-high molecular weight of 6 million to 12 million. However, since AM does not contain cationic charge, the AM-DM copolymer will greatly reduce the cationic charge density. Then, by blending the AM-DM copolymer and the PDM homopolymer, high cationicity and high molecular weight can be achieved simultaneously. However, polymer-based water treatment agents usually need to be dissolved and diluted in advance before use and cannot be directly added, otherwise they will agglomerate and be unfavorable for the exertion of the treatment effect. Based on the dissolution problem, during the preparation of the AM-DM copolymer in the present invention, an oily solvent is added for emulsification simultaneously, and then the AM-DM oily emulsion copolymer and the PDM homopolymer are compounded and emulsified, so that the two polymers can be fully combined and evenly dispersed in the oily solvent to form a liquid water purification agent product that does not need to be dissolved in advance and can be directly added for use. This water purification agent is extremely easy to be evenly dispersed in the water phase during use, thereby effectively synergizing the ultra-high molecular weight advantage of the AM-DM copolymer and the ultra-high cationic charge density advantage of the PDM homopolymer.

[0013] In view of the characteristics of high gangue and coal powder content, high turbidity, and large water volume in mine wastewater, the present invention realizes the effective treatment of mine wastewater by blending the AM-DM copolymer and the PDM homopolymer in a specific ratio. It can not only replace the existing treatment method of using two polymers, PAC and PAM, in combination, but also has more advantages in terms of use convenience and use effect. Specifically, the water purification agent product has a fast dissolution rate and good stability, and only needs to be added to water and stirred quickly during use; the supernatant of the treated wastewater is clear and transparent, the flocs are compact, and the sedimentation speed is fast, and the state of the flocs will not be damaged after being disturbed. The main role of the oily emulsion in the water purification agent is to wrap the two polymers to achieve uniform dispersion for rapid dissolution during use. The dosage of the oily emulsion for achieving the dispersion purpose cannot be lower than the amounts of the AM-DM copolymer and the PDM homopolymer, but the addition of too much oily emulsion is not conducive to cost, and at the same time will also affect the cationicity and use effect of the water purification agent. Therefore, the dosage of the oily solvent is reasonably adjusted according to the application requirements.

[0014] In addition, by adjusting the dosage ratio of the AM-DM copolymer and the PDM homopolymer according to the characteristics of different wastewaters, different liquid ultra-high cationic water purification agents applicable to various polluted wastewaters can also be obtained.

[0015] As a limitation to the above technical solution, the AM-DM oily emulsion copolymer is prepared by polymerizing the monomers acrylamide and dimethylaminoethyl methacrylate under the action of an initiator at a normal pressure of 95-115°C to obtain an AM-DM copolymer, and then adding an oily solvent for emulsification;

[0016] Preferably, the mass ratio of acrylamide to dimethylaminoethyl methacrylate used in the polymerization reaction is 35:70 to 80.

[0017] As a limitation to the above technical solution, the PDM homopolymer is prepared by polymerizing monomer acrylamide under the action of an initiator at 110-115°C under normal pressure.

[0018] As a limitation to the above technical solution, the initiator is selected as zinc chloride, and the addition amount of the initiator does not exceed 5% of the monomer amount used in the polymerization reaction, that is, in the preparation process of the AM-DM oil-in-water emulsion copolymer, the addition amount of the initiator does not exceed 5% of the sum of the masses of monomer acrylamide and dimethylaminoethyl methacrylate, and in the preparation process of the PDM homopolymer, the addition amount of the initiator does not exceed 5% of the mass of monomer acrylamide.

[0019] As a limitation to the above technical solution, the emulsifier is selected from at least one of N-dodecyldimethylamine, N-dodecyldimethylamine derivatives, and quaternary ammonium salts; the oil-based solvent is selected from one or more of de-aromatic solvent oil D60, D80, D100, or white oil.

[0020] As a limitation to the above technical solution, the water purification agent further includes a cationic surfactant with a mass concentration not exceeding 0.05%, and / or a stabilizer with a mass concentration not exceeding 0.05%; preferably, the cationic surfactant is selected as dodecyldimethylbenzylammonium chloride, and the stabilizer is selected as thiourea.

[0021] The present invention polymerizes two monomer substances AM and DM separately to obtain an AM-DM oil-in-water emulsion copolymer and a PDM homopolymer, and further improves the polymerization conditions and other component raw materials in the water purification agent to improve the performance and use advantages of the water purification agent.

[0022] Meanwhile, the present invention provides a preparation method of the liquid ultra-high cationic water purification agent for treating mine wastewater as described above, including the following preparation steps:

[0023] a. Prepare the AM-DM oil-in-water emulsion copolymer: Weigh acrylamide, dimethylaminoethyl methacrylate, and an initiator quantitatively, add them to a reaction tank, slowly raise the temperature in the tank to 95-115°C and keep it stable under normal pressure and stirring conditions, carry out the polymerization reaction, stop the reaction when the rotational viscosity of the AM-DM copolymer reaches 60000-270000 mPa·s, add an oil-based solvent to fully emulsify, and obtain a uniform AM-DM oil-in-water emulsion copolymer; or, after the polymerization of AM-DM starts, flow in the oil-based solvent while carrying out the polymerization reaction, and react for 4-6 hours to obtain a uniform AM-DM oil-in-water emulsion copolymer;

[0024] b. Preparation of PDM homopolymer: Weigh dimethylaminoethyl methacrylate and initiator quantitatively and add them into another reaction tank. Under normal pressure and stirring, raise the temperature in the tank to 110 - 115 °C and keep it stable for polymerization reaction. After the rotational viscosity of the reaction material reaches more than 60000 mPa·s, stop the reaction to obtain PDM homopolymer;

[0025] c. Preparation of water purifying agent: Add AM-DM oil-based emulsion copolymer and PDM homopolymer into the emulsifying tank in proportion, then add oil-based solvent, emulsifier, and the required cationic surfactant and stabilizer, and stir at high speed to uniformly emulsify the mixed system to obtain a homogeneous and stable milky white viscous liquid, which is the liquid ultra-high cationic water purifying agent for treating mine wastewater; Preferably, the stirring speed is 30 - 60 rad / min.

[0026] In actual production, for the preparation of AM-DM oil-based emulsion copolymer, it can be emulsified by adding oil-based emulsion after obtaining the AM-DM copolymer that meets the viscosity requirements, or the oil-based emulsion can be added continuously as the polymerization reaction proceeds during the polymerization of AM-DM copolymer, so as to obtain the AM-DM oil-based emulsion copolymer that meets the requirements.

[0027] As a limitation to the above technical solution, the mass ratio of AM-DM copolymer in the total mass of AM-DM oil-based emulsion copolymer is 40 - 50%; the mass sum of AM-DM copolymer and PDM homopolymer in the total mass of the water purifying agent is 40 - 50%.

[0028] Considering the production cost, it is more appropriate to control the dosage of the oil-based emulsion so that the polymer mass ratio is 40 - 50%.

[0029] The liquid ultra-high cationic water purifying agent of the present invention does not require a special environment for preparation, and the operation is simple and convenient. Since all raw materials used are liquids, precise dosing and reaction of various raw materials can be carried out, continuous preparation can be carried out, and automated production can be realized, which is conducive to the popularization and application of the water purifying agent.

[0030] Meanwhile, the present invention also provides the application of the above-mentioned liquid ultra-high cationic water purifying agent for treating mine wastewater. This water purifying agent is suitable for treating coal preparation wastewater in the coal mining industry. When the suspended solid content in the wastewater is between 3% - 5%, the recommended dosage of the water purifying agent is 50 - 100 mg / L, and the suspended solid content of the treated wastewater reaches the pollutant discharge limit requirements in Table 2 of the Coal Industry Pollutant Discharge Standard GB20426-2006 for coal mining wastewater; Preferably, the suspended solid content of the treated wastewater is < 50 mg / L.

[0031] When the water purifying agent of the present invention is applied, only one liquid water treatment agent needs to be added to complete two functions: charge neutralization of charged particles in wastewater and flocculation and sedimentation of suspended solids. The supernatant of the treated wastewater is clear and transparent, the flocs are compact, the sedimentation speed is fast, and the state of the flocs will not be damaged after perturbation.

[0032] In summary, the liquid ultra-high cationic water purifying agent of the present invention realizes the dual advantageous properties of high cationic degree and high molecular weight in a single water purifying agent product. Compared with the combined use of the existing two agents, PAC and PAM, it can not only significantly improve the water treatment effect and reduce the turbidity of the effluent, but also simplify the operation, ensure stable operation while improving the operation environment and increasing the operation efficiency. It can also greatly reduce the use cost. Specifically, for the water purifying agent product of the present invention, when the effective content (i.e., the total mass of the AM-DM copolymer and the PDM homopolymer in the water purifying agent product) is 40%, the molecular weight is between 1 million and 3 million, the charge density reaches about 90%, and the operating cost is 0.578 yuan per ton of water, which is significantly lower than the operating cost of 2.436 yuan per ton of water when using the existing PAC+PAM (anionic) in combination, and has significant application value for the treatment of mine wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Photographs of the AM-DM oil-based emulsion copolymer, PDM homopolymer and water purifying agent sample of the present invention;

[0034] Figure 2 Photographs of the water quality after treating ore dressing wastewater with the agent of Comparative Example 2;

[0035] Figure 3 Photographs of the water quality after treating ore dressing wastewater with the agent of Comparative Example 1;

[0036] Figure 4 Photographs of the water quality after treating ore dressing wastewater with the water purifying agent of the present invention;

[0037] Figure 5 Photographs of the on-site on the first day of the pilot test;

[0038] Figure 6 Photographs of the on-site on the second day of the pilot test. DETAILED DESCRIPTION OF THE INVENTION

[0039] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] The raw materials used in the following examples and comparative examples are all typical products purchased from the market. Quantitative tests were all set up with three repeated experiments, and the results were averaged.

[0041] Example

[0042] This example relates to the preparation of a liquid ultra-high cationic water purifying agent, and the specific operation is as follows.

[0043] a. Preparation of AM-DM oil-based emulsion copolymer: Weigh acrylamide, dimethylaminoethyl methacrylate, and initiator quantitatively, add them to a reaction tank, and slowly raise the temperature in the tank to 95 - 115°C under normal pressure and stirring, then keep it stable for polymerization reaction. Stop the reaction when the rotational viscosity of the AM-DM copolymer reaches 60000 - 270000 mPa·s, and add an oil-based solvent for full emulsification to obtain a uniform AM-DM oil-based emulsion copolymer; or, after the polymerization of AM-DM starts, flow in the oil-based solvent while carrying out the polymerization reaction for 4 - 6 hours to obtain a uniform AM-DM oil-based emulsion copolymer;

[0044] b. Preparation of PDM homopolymer: Weigh dimethylaminoethyl methacrylate and initiator quantitatively and add them to another reaction tank. Raise the temperature in the tank to 110 - 115°C under normal pressure and stirring, then keep it stable for polymerization reaction. Stop the reaction after the rotational viscosity of the reaction material reaches 60000 mPa·s or more to obtain PDM homopolymer;

[0045] c. Preparation of water purifying agent: Add the AM-DM oil-based emulsion copolymer and PDM homopolymer to an emulsification tank in proportion, then add an oil-based solvent, an emulsifier, and the required cationic surfactant and stabilizer, and stir at high speed, controlling the stirring speed at 30 - 60 rad / min to make the mixed system uniformly emulsified, obtaining a uniform and stable milky white viscous liquid, which is the liquid ultra-high cationic degree water purifying agent.

[0046] The compositions of the water purifying agents in different examples are shown in Table 1 below.

[0047] Table 1

[0048]

[0049]

[0050] Note: The preparation conditions of the AM-DM oil-based emulsion copolymer and the PDM homopolymer provided in the above embodiments are for the convenience of experiments and comparisons. Only the polymerization time is changed while other conditions are fixed. In actual production, the preparation conditions of the water purifying agent, including the preparation and compounding of the AM-DM oil-based emulsion copolymer and the PDM homopolymer, can be adjusted within a certain range of conditions. Specifically, for example, the dosage ratio of AM and DM in the AM-DM polymerization reaction can be in the range of 35:70 - 80 by mass ratio, and the polymerization temperature can be 95 - 115°C; the polymerization temperature of the DM polymerization reaction can be 110 - 115°C, and the addition amount of the oil-based solvent can be adjusted according to product requirements, etc.

[0051] The charge density, viscosity, and molecular weight of the AM-DM oil-based emulsion copolymer, PDM homopolymer, and water purifying agent prepared in different embodiments were detected respectively.

[0052] The detection basis for the charge density: Q / LJSW1012001 - 2023(4.6).

[0053] The viscosity was detected using a rotational viscometer, and the detection standard was referred to Q / LJSW1012001 - 2023(4.3).

[0054] The detection standard for the relative molecular weight was referred to GB / T31246 - 2014(5.2).

[0055] According to the above detection standards or detection methods, the performance indicators of the water purifying agent in each embodiment were determined, as shown in Table 2 below; the appearance forms of the AM-DM oil-based emulsion copolymer, PDM homopolymer, and water purifying agent are as shown in the attached drawings Figure 1 as shown.

[0056] Table 2

[0057]

[0058] Comparative example

[0059] The comparative examples involve existing water treatment agents and water purifying agents different from the present invention.

[0060] Comparative example 1

[0061] Existing water treatment agent, using 20% PAC solution (prepared by dissolving solid PAC into a 20% wt solution, and the solid PAC is purchased as a commercially available product with a content of 28%) + 1.5‰ anionic PAM solution (prepared by dissolving commercially available solid anionic PAM with a molecular weight of 16 million into a 1.5‰ solution).

[0062] Comparative example 2

[0063] Existing water treatment agents use a 1.5‰ cationic PAM solution (prepared by dissolving commercially available solid cationic PAM with a molecular weight of 10 million to 12 million into a 1.5‰ solution).

[0064] Comparative Example 3

[0065] The difference between this comparative example and the examples lies in the dosage ratio of the AM-DM oil-based emulsion copolymer and the PDM homopolymer in the water purifying agent.

[0066] For Comparative Example 3-1, 63 kg of AM-DM oil-based emulsion copolymer (containing 25.9 kg of AM-DM copolymer), 30 kg of PDM homopolymer, 4 kg of N-dodecyldimethylamine, and 3 kg of de-aromatic solvent oil D80 were compounded and emulsified. Other preparation conditions were the same as those in Example 1, obtaining an oil-based emulsion with a viscosity of 270,000 mp·s, a cationic degree of 72%, and a molecular weight of 8 million.

[0067] For Comparative Example 3-2, 12 kg of AM-DM oil-based emulsion copolymer (containing 4.9 kg of AM-DM copolymer), 83 kg of PDM homopolymer, 3 kg of N-dodecyldimethylamine, and 2 kg of de-aromatic solvent oil D80 were compounded and emulsified. Other preparation conditions were the same as those in Example 1, obtaining an oil-based emulsion with a viscosity of 37,000 mp·s, a cationic degree of 95%, and a molecular weight of 600,000.

[0068] Comparative Example 4

[0069] The difference between this comparative example and the examples lies in that the viscosities of the AM-DM oil-based emulsion copolymer and the PDM homopolymer in the water purifying agent do not meet the requirements.

[0070] For Comparative Example 4-1, the preparation conditions of the AM-DM oil-based emulsion copolymer were changed: the polymerization reaction time was 3 hours, and other material ratios and reaction conditions remained unchanged (the same as in Example 1), obtaining an oil-based emulsion with a viscosity of 10,000 mp.s, a cationic degree of 90%, and a molecular weight of 50,000.

[0071] For Comparative Example 4-2, the preparation conditions of the PDM homopolymer were changed, and the polymerization reaction temperature was controlled between 130 and 150 °C. A violent reaction occurred, and it quickly gelatinized, obtaining a gelatinous and viscous material, making it impossible to carry out subsequent process production.

[0072] The wastewater treatment effects of the water purifying agent in the comparative example, the existing agents in the comparative example, and different water purifying agents in the comparative example were compared. Using the beneficiation wastewater of the coal mine industry as the raw water, a small-scale test was carried out to observe the wastewater treatment phenomenon and treatment effect.

[0073] Raw water quality: Suspended solid concentration is 50,381 mg / L. The detection method of suspended solids adopts the gravimetric method according to GB / T 11901.

[0074] Experimental steps: (1) For each group of experiments, take 3 portions of the wastewater to be treated with the same volume (usually 250 mL or 1000 mL) for parallel experiments;

[0075] (2) Add the water purification agent according to Table 3 below, stir the reaction slowly clockwise for 5 - 10 seconds, let it stand, and observe the floc situation and sedimentation rate of the wastewater.

[0076] Table 3

[0077]

[0078] From the small-scale test phenomena and water quality treatment results in Table 3, it can be seen that the cationic PAM in Comparative Example 2 has a large molecular weight and a relatively low charge density. After treatment, the water quality has a wire-drawing phenomenon and is sticky, as shown in the attached drawing Figure 2 shown. However, when the dosage is reduced, the flocs disperse and the clear liquid is still sticky. Therefore, cationic PAM is not suitable for the treatment of mine wastewater.

[0079] In Comparative Example 1, PAC and anionic PAM are used in combination to treat mine wastewater. The main function of PAC is to provide a high ionic strength, while the main function of anionic PAM is to provide a high molecular weight. The combination of the two bridges and neutralizes the charges with the charged particles in the wastewater, thereby purifying the water quality. However, there are still some fine particles suspended in the treated wastewater and the turbidity is relatively high, as shown in the attached drawing Figure 3 shown.

[0080] For the treatment of ore dressing wastewater with the water purification agent of the present invention, only one agent is needed to neutralize the charges of the charged particles in the wastewater and flocculate and settle the suspended matter. The supernatant of the treated wastewater is clear and transparent, as shown in the attached drawing Figure 4 shown. The flocs are compact, the sedimentation rate is fast, and the state of the flocs will not be damaged after disturbance.

[0081] According to the above small-scale test results, take a coal preparation plant of a certain mine in Guizhou as the test base to conduct on-site pilot tests on the wastewater, conduct substitution tests with the polyaluminum chloride (PAC) and PAM (anionic) used on-site, and calculate the operating cost.

[0082] On-site pilot test

[0083] Test method: Continuous operation, track the 24-hour operation data, and take the average value for data analysis and cost calculation.

[0084] Test steps:

[0085] (1) On the first day, adjust the dosage of the chemicals on-site to stabilize the effluent quality and monitor the on-site operation. Among them, the PAC preparation tank stores PAC chemicals with a dissolved concentration of 20% wt, and the PAC dosing pump is set to a dosing rate between 650 - 700 mg / L; the PAM preparation tank stores anionic PAM chemicals with a dissolved concentration of 1.5‰ wt, and the PAM dosing pump is set to a dosing rate between 10 - 20 mg / L. Operate stably for 24 hours, and take samples every 4 hours to detect the suspended solid concentration in the effluent, and record the flow rate of the dosing pump and the wastewater flow rate.

[0086] (2) On the second day, clean the original PAC preparation tank, which is used to prepare and store the water purifying agent product of the present invention (the specific formula is according to Example 1), with a dissolved concentration of 10% wt (that is, take 10 kg of the liquid water purifying agent product and add water to make 100 kg of solution). Still use the original PAC dosing pump for dosing, adjust the dosing rate to 70 - 80 mg / L, and only use this one water treatment agent, the water purifying agent. Operate stably for 24 hours, observe the flocs and the effluent quality, and take samples every 4 hours to detect the suspended solid concentration in the effluent, and record the flow rate of the dosing pump and the wastewater flow rate.

[0087] (3) Organize the data and take the average value for data analysis and cost accounting.

[0088] The summary of the experimental data is shown in Table 4 and Table 5:

[0089] Table 4

[0090]

[0091] Table 5

[0092]

[0093] The PAC content used on-site is 28% (calculated based on the alumina content), the charge density is about 20 - 30%, and after calculation, the charge density is 23.74%. The dosage is large during the operation process, and the effluent is unstable due to the influence of the fluctuation of the water quality to be treated. The operation cost is about 2.436 yuan per ton of water.

[0094] The water purifying agent of the present invention operates stably, and the supernatant is clear and transparent. In the examples, the effective content of the water purifying agent is about 40%, the charge density is about 90%, the molecular weight is higher than that of the product used in combination with PAC + PAM (anionic), the ability to neutralize charges and coagulate is stronger, the comprehensive dosage is more economical, and the calculated cost is only 0.578 yuan per ton of water. It is significantly more suitable than the combined product of PAC and PAM and has a better development prospect.

[0095] In summary, for the liquid ultra-high cationic water purifying agent product of the present invention, the molecular weight of the effective content of 40% is between 1 million and 3 million, the charge density reaches about 90%, the operating cost is calculated to be 0.578 yuan per ton of water, which is significantly lower than the operating cost of 2.436 yuan per ton of water when using the existing PAC+PAM (anionic) in combination. The supernatant of the treated wastewater is clear and transparent, the flocs are compact, the sedimentation speed is fast, and the state of the flocs will not be damaged after disturbance, which has significant application value for the treatment of mine wastewater.

Claims

1. A liquid ultra-high cationic water purifying agent for treating mine wastewater, characterized in that: The water purifying agent is mainly prepared by stably dispersing an AM-DM oil-based emulsion copolymer and a PDM homopolymer in an oil-based solvent under the action of an emulsifier; the water purifying agent comprises the following components: 11-15 parts of an AM-DM oil-based emulsion copolymer containing the AM-DM copolymer, 60-65 parts of the PDM homopolymer, 2-3 parts of the emulsifier, and the balance being the oil-based solvent; The AM-DM oil-based emulsion copolymer is obtained by emulsifying the AM-DM copolymer with an oil-based solvent; The mass ratio of the AM-DM copolymer in the total mass of the AM-DM oil-based emulsion copolymer does not exceed 50%, and the sum of the masses of the AM-DM copolymer and the PDM homopolymer in the total mass of the water purifying agent does not exceed 50%; The rotational viscosity of the AM-DM copolymer is 60,000-270,000 mPa·s; the rotational viscosity of the PDM homopolymer is above 60,000 mPa·s.

2. The liquid ultra-high cationic water purifying agent for treating mine wastewater according to claim 1, characterized in that: The cationicity of the AM-DM copolymer is ≥60%, the cationicity of the water purifying agent is ≥85%, and the molecular weight of the water purifying agent is 1 million - 3 million.

3. The liquid ultra-high cationic water purifying agent for treating mine wastewater according to claim 1, wherein: The AM-DM oil-based emulsion copolymer is prepared by polymerizing monomers acrylamide and dimethylaminoethyl methacrylate under the action of an initiator at 95-115°C under normal pressure to obtain the AM-DM copolymer, and then adding an oil-based solvent for emulsification; Preferably, the dosage ratio of acrylamide and dimethylaminoethyl methacrylate in the polymerization reaction is 35:70-80 by mass ratio.

4. The liquid ultra-high cationic water purifying agent for treating mine wastewater according to claim 1, characterized in that: The PDM homopolymer is prepared by polymerizing the monomer acrylamide under the action of an initiator at 110-115°C under normal pressure.

5. The liquid-type ultra-high cationic water purifying agent for treating mine wastewater according to claim 3 or 4, characterized in that: The initiator is selected as zinc chloride, and the addition amount of the initiator does not exceed 5% of the monomer dosage in the polymerization reaction.

6. The liquid ultra-high cationic water purifying agent for treating mine wastewater according to claim 1, wherein: The emulsifier is selected from at least one of N-dodecyldimethylamine, N-dodecyldimethylamine derivatives, and quaternary ammonium salts; the oil-based solvent is selected from one or more of de-aromaticized solvent oil D60, D80, D100, or white oil.

7. The liquid ultra-high cationic water purifying agent for treating mine wastewater according to claim 1, characterized in that: The water purifying agent further comprises a cationic surfactant with a mass concentration not exceeding 0.05%, and / or a stabilizer with a mass concentration not exceeding 0.05%; preferably, the cationic surfactant is selected as dodecyldimethylbenzylammonium chloride, and the stabilizer is selected as thiourea.

8. A preparation method of a liquid ultra-high cationic water purifying agent for treating mine wastewater as described in any one of claims 1 to 7, characterized in that, It includes the following preparation steps: a. Prepare the AM-DM oil-based emulsion copolymer: Weigh acrylamide, dimethylaminoethyl methacrylate, and the initiator quantitatively, add them to a reaction tank, slowly raise the temperature in the tank to 95-115°C under normal pressure and stirring, and keep it stable for polymerization reaction. Stop the reaction when the rotational viscosity of the AM-DM copolymer reaches 60,000-270,000 mPa·s, and add an oil-based solvent for full emulsification to obtain a uniform AM-DM oil-based emulsion copolymer; or, after the polymerization of AM-DM starts, flow in the oil-based solvent while carrying out the polymerization reaction for 4-6 hours to obtain a uniform AM-DM oil-based emulsion copolymer; b. Preparation of PDM homopolymer: Weigh dimethylaminoethyl methacrylate and initiator quantitatively and add them into another reaction tank. Under normal pressure and stirring, raise the temperature in the tank to 110 - 115 °C and keep it stable for polymerization reaction. Stop the reaction after the rotational viscosity of the reaction material reaches over 60000 mPa·s to obtain PDM homopolymer; c. Preparation of water purifying agent: Add AM - DM oil - based emulsion copolymer and PDM homopolymer into the emulsifying tank in proportion, then add oil - based solvent, emulsifier, required cationic surfactant and stabilizer, and stir at high speed to make the mixed system emulsify evenly to obtain a uniform and stable milky white viscous liquid, which is the liquid - type ultra - high cation water purifying agent for treating mine wastewater; Preferably, the stirring speed is 30 - 60 rad / min.

9. The preparation method of the liquid ultra-high cation water purifying agent for treating mine wastewater according to claim 8, characterized in that: The mass ratio of AM - DM copolymer in the total mass of AM - DM oil - based emulsion copolymer is 40 - 50%; The sum of the masses of AM - DM copolymer and PDM homopolymer accounts for 40 - 50% of the total mass of the water purifying agent.

10. Use of a liquid ultra-high cationic water purifying agent for treating mine wastewater as described in any one of claims 1 to 7, characterized in that: This water purifying agent is applicable to the treatment of coal - washing wastewater in the coal mining industry. When the suspended solid content in the wastewater is between 3% and 5%, the recommended dosage of the water purifying agent is 50 - 100 mg / L, and the suspended solid content of the treated wastewater meets the requirements of the Coal Industry Pollutant Discharge Standard GB20426 - 2006; Preferably, the suspended solid content of the treated wastewater is < 50 mg / L.

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