Preparation method and application of composite water purifier for desulfurization wastewater

Abstract

The present invention provides a preparation method and application of a composite high-efficiency water purifier for desulfurization wastewater, which solves the technical problems of high cost, complex treatment process, poor purification effect and inability to meet discharge standards in the prior art using the traditional triple-box process to treat desulfurization wastewater. The preparation method is as follows, in parts by weight, composed of the following raw materials: 75 parts-85 parts of modified magnesium rectorite slurry flocculant of component A, 15 parts-20 parts of polysilicate iron zinc composite flocculant of component B, 5 parts-10 parts of sodium diethyl dithiocarbamate of component C, 1 part-3 parts of water-soluble amphoteric starch of component D, after mixing and stirring the above raw materials, heat and dry them under vacuum conditions, and when the moisture content of the mixture is less than 8%, stop heating and continue stirring until the temperature of the mixture drops below 40°C, remove the vacuum, grind the mixture into a solid powder, and prepare a composite high-efficiency water purifier for desulfurization wastewater. It can be widely used in the field of desulfurization wastewater treatment in power plants.

Description

Technical Field

[0001] The invention relates to the field of desulfurization wastewater treatment in power plants, and in particular to a preparation method and application of a composite high-efficiency water purifier for desulfurization wastewater. Background Art

[0002] Desulfurization wastewater is the discharge water from the absorption tower during the wet desulfurization of boiler flue gas (limestone / gypsum method). In order to maintain the balance of materials in the slurry circulation system of the desulfurization device, prevent the soluble part (chlorine concentration) in the flue gas from exceeding the specified value and ensure the quality of gypsum, a certain amount of wastewater must be discharged from the system, namely desulfurization wastewater. Desulfurization wastewater mainly comes from the gypsum dehydration and cleaning system. The impurities contained in desulfurization wastewater mainly include suspended matter, supersaturated sulfites, sulfates and heavy metals, including many first-class pollutants that are strictly controlled in national environmental protection standards.

[0003] At present, with the development of various industries, the electricity consumption of various industries is also increasing with the expansion of the scale of the industry, and thermal power plants account for the highest proportion of the power generation industry. Therefore, while the power plants are continuously generating electricity, a large amount of desulfurization wastewater is also generated. At present, the commonly used treatment method for desulfurization wastewater in various power plants is the three-tank process, that is, the desulfurization wastewater is treated with lime method, organic sulfur method and iron / aluminum flocculant-polyacrylamide flocculation method in sequence. The three-tank process mainly plays the role of reducing the concentration of suspended matter and removing heavy metals.

[0004] The general treatment process of desulfurization wastewater in the traditional three-tank process is: add lime slurry to the desulfurization wastewater to increase the pH value of the desulfurization wastewater, and make heavy metal ions such as iron ions, zinc ions, copper ions, nickel ions, and chromium ions produce hydroxide precipitation. 2+ It can also react with some fluoride ions in wastewater to generate insoluble CaF2, which reacts with As 3+ Complexation generates insoluble substances. 2+ , Hg 2+ It remains in the wastewater in the form of ions, and then organic sulfide (TMT-15) is added to make it react with Pb 2+ , Hg 2+The reaction forms insoluble sulfides that settle down. After the chemical precipitation reaction, the desulfurization wastewater still contains many small and dispersed particles and colloidal substances. Then a certain proportion of flocculants are added to make them condense into larger particles and settle down. Then, high molecular weight polyelectrolytes are added as coagulants to neutralize the particle charge to reduce the surface tension of the particles, strengthen the growth process of the particles, and further promote the precipitation of hydroxides and sulfides, so that the fine floccules slowly become larger and easier to deposit floccules. At the same time, the suspended matter in the desulfurization wastewater also settles down. However, with the continuous deterioration of the current water quality, especially the continuous decrease in the quality of the make-up water entering the desulfurization system, the traditional three-unit treatment process is increasingly unable to meet the current desulfurization wastewater treatment requirements, making the desulfurization wastewater unable to meet the discharge standards.

[0005] At the same time, the organic or inorganic flocculants used in the prior art are used alone for treatment, and their water treatment range is relatively narrow. The effects of removing heavy metals and reducing COD are not good, the treatment process is relatively complicated and the treatment cost is high. Therefore, there is an urgent need for a water purifier with a simple treatment process and good treatment effect on desulfurization wastewater. Summary of the invention

[0006] In view of the shortcomings and deficiencies in the prior art, the present invention provides a method for preparing a composite high-efficiency water purifier for desulfurization wastewater, which can significantly improve the flocculation treatment efficiency of heavy metals and suspended matter in water, enhance the water purification rate, and achieve the upgrading of the existing desulfurization wastewater treatment process. The method is suitable for a wide range of water types and has low treatment cost, and its application.

[0007] To achieve the above objectives, the present invention is implemented by the following technical scheme: The preparation method of the composite high-efficiency water purifier for desulfurization wastewater provided by the present invention is composed of the following raw materials in parts by weight: 75-85 parts of modified magnesium rectorite slurry flocculant as component A, 15-20 parts of polysilicate iron zinc composite flocculant as component B, 5-10 parts of sodium diethyl dithiocarbamate as component C, and 1-3 parts of water-soluble amphoteric starch as component D;

[0008] After the above raw materials are mixed and stirred, they are heated and dried under vacuum conditions. When the moisture content of the mixture is lower than 8%, the heating is stopped and stirring is continued until the temperature of the mixture drops below 40°C. The vacuum is removed and the mixture is ground into a solid powder to obtain a composite high-efficiency water purifier for desulfurization wastewater.

[0009] Preferably, the method further comprises the following steps:

[0010] (1) Preparation of modified magnesium rectorite slurry flocculant

[0011] A certain amount of magnesium sulfate, organic polysaccharide and magnesium polyphosphate are added to a hydrated slurry of natural rectorite, the above materials are stirred evenly, ball milled, sealed and aged to obtain a modified magnesium rectorite flocculant;

[0012] Wherein: the mass ratio of the added amounts of rectorite, magnesium sulfate, organic polysaccharide and magnesium polyphosphate is: rectorite: magnesium sulfate: organic polysaccharide: magnesium polyphosphate = 100:5-10:5:1-5;

[0013] (2) Preparation of polysilicate iron zinc composite flocculant

[0014] (a) diluting silicate solid with water to obtain a silicate aqueous solution with a mass fraction of SiO2 of 3% to 5%, and adjusting the pH value to 5.0 to 5.5 using a pH adjuster; stirring and observing that the silicate aqueous solution gradually changes from clear to milky white, and the bubbles gradually become smaller; when the bubbles are about to disappear, immediately adding a certain amount of saturated aqueous solution of Fe2(SO4)3 and saturated aqueous solution of ZnSO4, stirring until the reaction is complete, and obtaining a polysilicate iron zinc flocculant;

[0015] The mass ratio of the silicate aqueous solution, the saturated Fe2(SO4)3 aqueous solution and the saturated ZnSO4 aqueous solution is: silicate aqueous solution: saturated Fe2(SO4)3 aqueous solution: saturated ZnSO4 aqueous solution = 100: 10-20: 10-20;

[0016] (b) adding 2% to 5% by weight of polyepoxysuccinic acid to the polysilicate iron zinc flocculant prepared in step (a), activating the mixture at room temperature to prepare a polysilicate iron zinc composite flocculant;

[0017] (3) Preparation of composite high-efficiency water purifier for desulfurization wastewater

[0018] In parts by weight, 75-85 parts of the modified magnesium rectorite slurry flocculant prepared as component A, 15-20 parts of the polysilicate iron zinc composite flocculant as component B, 5-10 parts of sodium diethyldithiocarbamate as component C and 1-3 parts of water-soluble amphoteric starch as component D are mixed and stirred, and the mixture is heated and dried under the conditions of a vacuum degree of -0.2~-0.1MPa and a temperature of 85℃-90℃. When the moisture content of the mixture is lower than 8%, the heating is stopped and the stirring is continued until the temperature of the mixture drops below 40℃, the vacuum is removed, and the mixture is ground into a solid powder to obtain a composite high-efficiency water purifier for desulfurization wastewater.

[0019] Preferably, the particle size of the rectorite in step (1) is 300-400 mesh.

[0020] Preferably, in step (3), the water-soluble amphoteric starch is an amphoteric starch having a carboxymethyl group and a quaternary ammonium group.

[0021] Preferably, the anionic substitution degree of the water-soluble amphoteric starch is 0.7-1.0, and the cationic substitution degree is 0.15-0.20.

[0022] Preferably, in step (1), the pH adjuster is a 40% by mass H2SO4 solution and a 40% by mass NaOH solution.

[0023] Preferably, the ball milling process in step (1) is as follows: the material is ball milled in a ceramic ball mill for 3h-4h, and then taken out and sealed for aging for 24h-30h.

[0024] Preferably, the activation time of the polysilicate iron zinc flocculant and polyepoxysuccinic acid in step (2) is 24h-30h.

[0025] A composite high-efficiency water purifier for desulfurization wastewater is prepared according to the above-mentioned preparation method of the composite high-efficiency water purifier for desulfurization wastewater.

[0026] Preferably, the addition amount of the desulfurization wastewater composite high-efficiency water purifier to the desulfurization wastewater is 0.05g / L-0.1g / L.

[0027] Beneficial effects of the present invention:

[0028] (1) The preparation method and application of the composite high-efficiency water purifier for desulfurization wastewater of the present invention simplify the process design and reagent cost investment for desulfurization wastewater treatment, have strong flocculation ability, significantly improve the treatment efficiency of heavy metals, suspended solids, etc. in water bodies, improve the water purification rate, and realize the upgrading and transformation of the existing desulfurization wastewater treatment process.

[0029] The components in the water purifier prepared by the present invention interact with each other and synergize to purify the desulfurization wastewater: first, the reduction effect, the water purifier of the present invention reduces the COD of the wastewater through exchange; second, the adsorption effect, the water purifier of the present invention can adsorb heavy metals in the wastewater, and form colloids through displacement and precipitation to remove them from the water; third, the flocculation effect, the water purifier of the present invention removes colloids such as suspended matter and insoluble matter in the water body through flocculation, forms flocs, and then performs solid-liquid separation to reduce turbidity.

[0030] (2) The composite high-efficiency water purifier for desulfurization wastewater of the present invention does not require the addition of other chemicals when treating desulfurization wastewater. On the basis of a smaller dosage of chemicals, it can replace the addition of the original flocculant / coagulant aid and reduce the dosage of the original lime, thereby reducing the dosage of chemicals in the overall desulfurization wastewater treatment process, thereby reducing the operating cost of the desulfurization wastewater treatment system.

[0031] (3) The composite high-efficiency water purifier for desulfurization wastewater of the present invention has a thorough reaction and excellent flocculation effect through the strong combination of inorganic and organic flocculants. In the process of treating desulfurization wastewater, the water body will not be polluted by secondary pollution.

[0032] (4) The composite high-efficiency water purifier for desulfurization wastewater of the present invention is applicable to a wide range of water types and has low treatment costs. It has broad application prospects in the fields of chemical industry, water treatment, heavy metal recovery, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The present invention simplifies the process flow of desulfurization wastewater treatment in a chemical-dosing power plant;

[0034] Figure 2 This is a schematic diagram of the traditional chemical dosing process for desulfurization wastewater treatment in power plants. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer as the description proceeds. However, these embodiments are exemplary only and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solution of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the scope of protection of the present invention. Example 1

[0036] The preparation of a composite high-efficiency water purifier for desulfurization wastewater includes the following specific steps:

[0037] (1) Preparation of modified magnesium rectorite slurry flocculant

[0038] 5Kg of magnesium sulfate, 5Kg of cellulose and 5Kg of magnesium polyphosphate were added into 100Kg of hydrated slurry of natural rectorite with a particle size of 300-400 mesh, the above materials were stirred evenly, ball-milled in a ceramic ball mill for 3 hours, taken out and sealed for 24 hours to obtain a modified magnesium rectorite flocculant.

[0039] The particle size range of the rectorite used in the embodiments of the present invention is 300 mesh-400 mesh, which can better maintain the spatial network and step-by-step layered structure of the rectorite from a microscopic perspective; the ball milling time of the modified magnesium rectorite flocculant in the ceramic ball mill is optimized to 3 hours, and the sealed aging time after removal is optimized to 24 hours, which can maximize the integrity of the remodeled structure and the high efficiency activity of the flocculant.

[0040] The modified magnesium rectorite flocculant of the present invention is prepared by reacting rectorite powder as a carrier, adding magnesium sulfate, organic polysaccharide and magnesium polyphosphate. First, the magnesium ions in the material can form coordination bonds with the hydroxyl and amino groups in the organic polysaccharide, so that the magnesium ions and the polysaccharide form aggregates with larger particle sizes under the action of the coordination bonds, and as the particle size of the aggregates increases, the viscosity of the aggregates in water increases, thereby accelerating the adsorption of suspended matter and improving the flocculation efficiency. Secondly, due to the different lengths of the coordination bonds formed by magnesium ions and polysaccharides, there are pores of different sizes in the formed aggregates, and these pores are conducive to the adsorption of suspended matter of different particle sizes, thereby further improving the flocculation efficiency. Finally, the desulfurization wastewater is filtered and settled by the overall molecular sieve type and porous structure of the fine modified magnesium rectorite flocculant of the present invention to reduce the chromaticity of the wastewater, making the water clearer.

[0041] At the same time, the modified magnesium rectorite flocculant is a weakly alkaline solid substance that can adjust the pH value in desulfurization wastewater to increase the pH value of the wastewater. As the pH value of the wastewater increases, the solubility of heavy metals in the wastewater decreases and it is easier to be adsorbed. Magnesium rectorite has a large specific surface area and high dispersibility, which can improve its adsorption capacity and remove heavy metals by adsorbing them on the surface of the modified magnesium rectorite.

[0042] (2) Preparation of polysilicate iron zinc composite flocculant

[0043] (a) Dilute the sodium silicate solid with water to 100 kg of a silicate aqueous solution with a mass fraction of 3% SiO2, and use a 40% H2SO4 solution and a 40% NaOH solution to adjust the pH value to 5.0-5.5; after stirring for a period of time, observe that the silicate aqueous solution gradually changes from clear to milky white, and the bubbles gradually become smaller. When the bubbles are about to disappear, immediately add 10 kg of a saturated Fe2(SO4)3 aqueous solution and 10 kg of a saturated ZnSO4 aqueous solution, and stir thoroughly until the reaction is complete to obtain a polysilicate iron zinc flocculant.

[0044] (b) adding 2% by weight of polyepoxysuccinic acid to the polysilicate iron zinc flocculant prepared in step (a), and activating the mixture at room temperature for 24 hours to prepare a polysilicate iron zinc composite flocculant.

[0045] The polysilicate iron zinc composite flocculant of the present invention is a composite flocculant obtained by adding an appropriate amount of polyepoxysuccinic acid to the polysilicate iron zinc flocculant and activating it at room temperature. The polysilicate iron zinc flocculant is a ternary copolymer of silicon, iron and zinc. During the flocculation process, the suspended colloidal particles in the heavy metal wastewater can be adsorbed by the adsorption and bridging effect of polysilicate acid to form large flocs in a short time. The formed flocs are not easily broken by mechanical stirring, so that they can be completely settled in a short time, thereby improving the treatment efficiency. Polysilicate iron zinc is a layered adsorption material, in which Zn2+ and Fe 3+ The ions are easily replaced by heavy metal ions in the wastewater, and an ion exchange reaction occurs, thereby achieving the solidification and adsorption of heavy metal ions in the wastewater and causing them to settle; and the surface of polysilicate iron zinc is charged, and it has a strong selective adsorption of polar substances in water.

[0046] Appropriate amounts of polyepoxysuccinic acid and polysilicate iron zinc flocculants have a synergistic effect after being activated in a certain proportion, and can play a role in corrosion inhibition to protect equipment from erosion. The polysilicate iron zinc composite flocculant activated by polyepoxysuccinic acid can chelate and inhibit scale at a low dose, has a coagulant effect, and strengthens the bonding, bridging, and net-catching and sweeping effects, further enhancing the overall flocculation and adsorption effect of the polysilicate iron zinc composite flocculant.

[0047] (3) Preparation of composite high-efficiency water purifier for desulfurization wastewater

[0048] In parts by weight, 75 parts of the prepared modified magnesium rectorite slurry flocculant, 20 parts of polysilicate iron zinc composite flocculant, 5 parts of sodium diethyldithiocarbamate and 3 parts of water-soluble amphoteric starch with an anion substitution degree of 0.7 and a cation substitution degree of 0.15 are fully mixed and stirred into a mixture, and the mixture is heated and dried under vacuum conditions of -0.1 MPa and a temperature of 85°C. When the moisture content of the mixture is 8%, the heating is stopped and the stirring is continued until the temperature of the mixture drops below 40°C. The vacuum is removed and the mixture is ground into a solid powder to obtain a composite high-efficiency water purifier for desulfurization wastewater.

[0049] In order to further ensure the wide applicability of adsorption, shorten the reaction time of the high-efficiency water purifier, and improve the water purification effect, a small amount of sodium diethyldithiocarbamate is added to the composite high-efficiency water purifier for desulfurization wastewater of the present invention. After sodium diethyldithiocarbamate is dissolved in water, an anion group containing S is formed. The anion group combines with the heavy metal ions in the wastewater to form a stable organic sulfur chelate, thereby further ensuring the integrity and thoroughness of removing heavy metals in the wastewater.

[0050] The composite high-efficiency water purifier for desulfurized wastewater of the present invention comprises a water-soluble amphoteric starch with a carboxymethyl group and a quaternary ammonium group, and a high-degree-of-substitution water-soluble amphoteric starch with an anion degree of substitution of 0.7-1.0 and a cation degree of substitution of 0.15-0.20. The surface of the water-soluble amphoteric starch particles forms unevenly distributed small holes, and the particle surface is severely damaged and honeycomb-shaped. The viscosity increases with the increase of the degree of substitution of anions and cations, so that the adsorption bridging after charge neutralization is more obvious and more thorough. The addition of water-soluble amphoteric starch enhances the overall coagulation of the water purifier, accelerates the sedimentation rate of suspended matter in the wastewater, increases the flocs formed, makes the flocculation more thorough, ensures the thoroughness of the residual water purifier components in the wastewater after cleaning, makes the supernatant of the treated wastewater more thorough, and effectively reduces the COD, SS and heavy metals in the wastewater.

[0051] In summary, the components of the composite high-efficiency water purifier for desulfurization wastewater of the present invention cooperate with each other and synergize. The modified magnesium rectorite slurry flocculant is used as the matrix material. After adding the polysilicate iron zinc composite flocculant, the number and strength of coordination bonds formed between magnesium ions and the hydroxyl and amino groups of polysaccharides can be promoted, and large and dense aggregates are formed under the action of the coordination bonds. At the same time, the matrix material and flocculant of the present invention both present a step-by-step layered spatial network structure, which allows the wastewater to be filtered through the layered network structure during the reaction and mixing process, greatly reducing the heavy metal content and COD of the wastewater.

[0052] In order to ensure the completeness and thoroughness of the removal of heavy metals from wastewater, a certain amount of sodium diethyldithiocarbamate is added to the water purifier of the present invention. At the same time, in order to avoid secondary pollution of wastewater by residual water purifier, a small amount of water-soluble amphoteric starch is added to the water purifier of the present invention, which can more obviously and thoroughly enhance the coagulation property from the perspective of charge neutralization and intermolecular adsorption bridging flocculation, accelerate the sedimentation rate, increase the floccules, make the flocculation more thorough, and make the supernatant of the treated wastewater more thorough, so as to more completely remove COD, suspended solids and heavy metals in the wastewater, effectively avoid secondary pollution of wastewater after treatment by the water purifier, and improve the economic and environmental benefits of the product. Example 2

[0053] The preparation of a composite high-efficiency water purifier for desulfurization wastewater includes the following specific steps:

[0054] (1) Preparation of modified magnesium rectorite slurry flocculant

[0055] 10Kg of magnesium sulfate, 5Kg of cellulose and 1Kg of magnesium polyphosphate were added into 100Kg of hydrated slurry of natural rectorite with a particle size of 300-400 mesh, the above materials were stirred evenly, ball-milled in a ceramic ball mill for 4 hours, taken out and sealed for 30 hours to obtain a modified magnesium rectorite flocculant.

[0056] (2) Preparation of polysilicate iron zinc composite flocculant

[0057] (a) Dilute the sodium silicate solid with water to 100 kg of a silicate aqueous solution with a mass fraction of 5% SiO2, and use a 40% H2SO4 solution and a 40% NaOH solution to adjust the pH value to 5.0-5.5; after stirring for a period of time, observe that the silicate aqueous solution gradually changes from clear to milky white, and the bubbles gradually become smaller. When the bubbles are about to disappear, immediately add 20 kg of a saturated Fe2(SO4)3 aqueous solution and 20 kg of a saturated ZnSO4 aqueous solution, and stir thoroughly until the reaction is complete to obtain a polysilicate iron zinc flocculant.

[0058] (b) adding 3% by weight of polyepoxysuccinic acid to the polysilicate iron zinc flocculant prepared in step (a), and activating the mixture at room temperature for 30 hours to prepare a polysilicate iron zinc composite flocculant.

[0059] (3) Preparation of composite high-efficiency water purifier for desulfurization wastewater

[0060] In parts by weight, 85 parts of the prepared modified magnesium rectorite slurry flocculant, 15 parts of polysilicate iron zinc composite flocculant, 5 parts of sodium diethyldithiocarbamate and 1 part of water-soluble amphoteric starch with an anion substitution degree of 0.8 and a cation substitution degree of 0.2 are fully mixed and stirred into a mixture, and the mixture is heated and dried under vacuum conditions of -0.2 MPa and a temperature of 90°C. When the moisture content of the mixture is 5%, the heating is stopped and the stirring is continued until the temperature of the mixture drops below 40°C, the vacuum is removed, and the mixture is ground into a solid powder to obtain a composite high-efficiency water purifier for desulfurization wastewater. Example 3

[0061] The preparation of a composite high-efficiency water purifier for desulfurization wastewater includes the following specific steps:

[0062] (1) Preparation of modified magnesium rectorite slurry flocculant

[0063] 8Kg of magnesium sulfate, 5Kg of cellulose and 3Kg of magnesium polyphosphate were added into 100Kg of hydrated slurry of natural rectorite with a particle size of 300-400 mesh. After the above materials were stirred evenly, they were ball-milled in a ceramic ball mill for 3 hours, taken out and sealed for 26 hours to obtain a modified magnesium rectorite flocculant.

[0064] (2) Preparation of polysilicate iron zinc composite flocculant

[0065] (a) Dilute potassium silicate solid with water to obtain 100 kg of silicate aqueous solution with a mass fraction of SiO2 of 4%, and use 40% H2SO4 solution and 40% NaOH solution to adjust the pH value to 5.0-5.5; after stirring for a period of time, observe that the silicate aqueous solution gradually changes from clear to milky white, and the bubbles gradually become smaller. When the bubbles are about to disappear, immediately add 15 kg of Fe2(SO4)3 saturated aqueous solution and 15 kg of ZnSO4 saturated aqueous solution, stir thoroughly until the reaction is complete, and obtain polysilicate iron zinc flocculant.

[0066] (b) Add 5% polyepoxysuccinic acid to the polysilicate iron zinc flocculant prepared in step (a), and activate at room temperature for 26 hours to prepare a polysilicate iron zinc composite flocculant.

[0067] (3) Preparation of composite high-efficiency water purifier for desulfurization wastewater

[0068] In parts by weight, 80 parts of the prepared modified magnesium rectorite slurry flocculant, 15-20 parts of polysilicate iron zinc composite flocculant, 10 parts of sodium diethyldithiocarbamate and 2 parts of water-soluble amphoteric starch with an anion substitution degree of 0.7 and a cation substitution degree of 0.15 are fully mixed and stirred into a mixture, and the mixture is heated and dried under the conditions of a vacuum degree of -0.15 MPa and a temperature of 85°C. When the moisture content of the mixture is 5%, the heating is stopped and the stirring is continued until the temperature of the mixture drops below 40°C, the vacuum is removed, and the mixture is ground into a solid powder to obtain a composite high-efficiency water purifier for desulfurization wastewater. Example 4

[0069] The preparation of a composite high-efficiency water purifier for desulfurization wastewater includes the following specific steps:

[0070] (1) Preparation of modified magnesium rectorite slurry flocculant

[0071] 5Kg of magnesium sulfate, 5Kg of cellulose and 4Kg of magnesium polyphosphate were added into 100Kg of hydrated slurry of natural rectorite with a particle size of 300-400 mesh, the above materials were stirred evenly, ball-milled in a ceramic ball mill for 4 hours, taken out and sealed for 24 hours to obtain a modified magnesium rectorite flocculant.

[0072] (2) Preparation of polysilicate iron zinc composite flocculant

[0073] (a) Dilute the sodium silicate solid with water to 100 kg of a silicate aqueous solution with a mass fraction of 3% SiO2, and use a 40% H2SO4 solution and a 40% NaOH solution to adjust the pH value to 5.0-5.5; after stirring for a period of time, observe that the silicate aqueous solution gradually changes from clear to milky white, and the bubbles gradually become smaller. When the bubbles are about to disappear, immediately add 10 kg of a saturated Fe2(SO4)3 aqueous solution and 12 kg of a saturated ZnSO4 aqueous solution, and stir thoroughly until the reaction is complete to obtain a polysilicate iron zinc flocculant.

[0074] (b) adding 5% polyepoxysuccinic acid to the polysilicate iron zinc flocculant prepared in step (a), activating the mixture at room temperature for 24 hours, and preparing a polysilicate iron zinc composite flocculant.

[0075] (3) Preparation of composite high-efficiency water purifier for desulfurization wastewater

[0076] In parts by weight, 80 parts of the prepared modified magnesium rectorite slurry flocculant, 15 parts of polysilicate iron zinc composite flocculant, 7 parts of sodium diethyldithiocarbamate and 3 parts of water-soluble amphoteric starch with an anionic substitution degree of 1.0 and a cationic substitution degree of 0.15 are fully mixed and stirred into a mixture, and the mixture is heated and dried under vacuum conditions of -0.1 MPa and a temperature of 90°C. When the moisture content of the mixture is 4%, the heating is stopped and the stirring is continued until the temperature of the mixture drops below 40°C. The vacuum is removed and the mixture is ground into a solid powder to obtain a composite high-efficiency water purifier for desulfurization wastewater. Example 5

[0077] The preparation of a composite high-efficiency water purifier for desulfurization wastewater includes the following specific steps:

[0078] (1) Preparation of modified magnesium rectorite slurry flocculant

[0079] 7Kg of magnesium sulfate, 5Kg of cellulose and 5Kg of magnesium polyphosphate were added into 100Kg of hydrated slurry of natural rectorite with a particle size of 300-400 mesh, the above materials were stirred evenly, ball-milled in a ceramic ball mill for 3 hours, taken out and sealed for 30 hours to obtain a modified magnesium rectorite flocculant.

[0080] (2) Preparation of polysilicate iron zinc composite flocculant

[0081] (a) Dilute potassium silicate solid with water to obtain 100 kg of silicate aqueous solution with a mass fraction of 5% SiO2, and use 40% H2SO4 solution and 40% NaOH solution to adjust the pH value to 5.0-5.5; after stirring for a period of time, observe that the silicate aqueous solution gradually changes from clear to milky white, and the bubbles gradually become smaller. When the bubbles are about to disappear, immediately add 13 kg of Fe2(SO4)3 saturated aqueous solution and 10 kg of ZnSO4 saturated aqueous solution, stir thoroughly until the reaction is complete, and obtain polysilicate iron zinc flocculant.

[0082] (b) Add 3% polyepoxysuccinic acid to the polysilicate iron zinc flocculant prepared in step (a), and activate at room temperature for 30 hours to prepare a polysilicate iron zinc composite flocculant.

[0083] (3) Preparation of composite high-efficiency water purifier for desulfurization wastewater

[0084] In parts by weight, 75 parts of the prepared modified magnesium rectorite slurry flocculant, 15 parts of polysilicate iron zinc composite flocculant, 5 parts of sodium diethyldithiocarbamate and 1 part of water-soluble amphoteric starch with an anion substitution degree of 0.7 and a cation substitution degree of 0.15 are fully mixed and stirred into a mixture, and the mixture is heated and dried under vacuum conditions of -0.1 MPa and a temperature of 90°C. When the moisture content of the mixture is 3%, the heating is stopped and the stirring is continued until the temperature of the mixture drops below 40°C, the vacuum is removed, and the mixture is ground into a solid powder to obtain a composite high-efficiency water purifier for desulfurization wastewater.

[0085] Comparative Example 1

[0086] Preparation of desulfurization wastewater purifier, comparative example 1 compared with implementation 2, no polysilicate iron zinc composite flocculant component is added, the specific steps include the following:

[0087] (1) Preparation of modified magnesium rectorite slurry flocculant

[0088] 10Kg of magnesium sulfate, 5Kg of cellulose and 1Kg of magnesium polyphosphate were added into 100Kg of hydrated slurry of natural rectorite with a particle size of 300-400 mesh, the above materials were stirred evenly, ball-milled in a ceramic ball mill for 4 hours, taken out and sealed for 30 hours to obtain a modified magnesium rectorite flocculant.

[0089] (2) Preparation of desulfurization wastewater purifier

[0090] In parts by weight, 85 parts of the prepared modified magnesium rectorite slurry flocculant, 5 parts of sodium diethyldithiocarbamate and 1 part of water-soluble amphoteric starch with an anionic substitution degree of 0.8 and a cationic substitution degree of 0.2 are fully mixed and stirred into a mixture. The mixture is heated and dried under vacuum conditions of -0.2 MPa and a temperature of 90°C. When the moisture content of the mixture is 5%, the heating is stopped and the stirring is continued until the temperature of the mixture drops below 40°C. The vacuum is removed and the mixture is ground into a solid powder to obtain a desulfurization wastewater purifier.

[0091] Comparative Example 2

[0092] Preparation of desulfurization wastewater purifier, comparative example 2 compared with implementation 2, no modified magnesium rectorite slurry flocculant component is added, the specific steps include the following:

[0093] (1) Preparation of polysilicate iron zinc composite flocculant

[0094] (a) Dilute the sodium silicate solid with water to 100 kg of a silicate aqueous solution with a mass fraction of 5% SiO2, and use a 40% H2SO4 solution and a 40% NaOH solution to adjust the pH value to 5.0-5.5; after stirring for a period of time, observe that the silicate aqueous solution gradually changes from clear to milky white, and the bubbles gradually become smaller. When the bubbles are about to disappear, immediately add 20 kg of a saturated Fe2(SO4)3 aqueous solution and 20 kg of a saturated ZnSO4 aqueous solution, and stir thoroughly until the reaction is complete to obtain a polysilicate iron zinc flocculant.

[0095] (b) adding 3% by weight of polyepoxysuccinic acid to the polysilicate iron zinc flocculant prepared in step (a), and activating the mixture at room temperature for 30 hours to prepare a polysilicate iron zinc composite flocculant.

[0096] (2) Preparation of composite high-efficiency water purifier for desulfurization wastewater

[0097] In parts by weight, 90 parts of the prepared polysilicate iron zinc composite flocculant, 5 parts of sodium diethyldithiocarbamate and 1 part of water-soluble amphoteric starch with an anionic substitution degree of 0.8 and a cationic substitution degree of 0.2 are fully mixed and stirred into a mixture. The mixture is heated and dried under vacuum conditions of -0.2 MPa and a temperature of 90°C. When the moisture content of the mixture is 5%, the heating is stopped and the stirring is continued until the temperature of the mixture drops below 40°C. The vacuum is removed and the mixture is ground into a solid powder to obtain a desulfurization wastewater purifier.

[0098] Comparative Example 3

[0099] Preparation of desulfurization wastewater purifier, comparative example 3 compared with implementation 2, no sodium diethyldithiocarbamate and water-soluble amphoteric starch components were added, and the specific steps included the following:

[0100] (1) Preparation of modified magnesium rectorite slurry flocculant

[0101] 10Kg of magnesium sulfate, 5Kg of cellulose and 1Kg of magnesium polyphosphate were added into 100Kg of hydrated slurry of natural rectorite with a particle size of 300-400 mesh, the above materials were stirred evenly, ball-milled in a ceramic ball mill for 4 hours, taken out and sealed for 30 hours to obtain a modified magnesium rectorite flocculant.

[0102] (2) Preparation of polysilicate iron zinc composite flocculant

[0103] (a) Dilute the sodium silicate solid with water to 100 kg of a silicate aqueous solution with a mass fraction of 5% SiO2, and use a 40% H2SO4 solution and a 40% NaOH solution to adjust the pH value to 5.0-5.5; after stirring for a period of time, observe that the silicate aqueous solution gradually changes from clear to milky white, and the bubbles gradually become smaller. When the bubbles are about to disappear, immediately add 20 kg of a saturated Fe2(SO4)3 aqueous solution and 20 kg of a saturated ZnSO4 aqueous solution, and stir thoroughly until the reaction is complete to obtain a polysilicate iron zinc flocculant.

[0104] (b) adding 3% by weight of polyepoxysuccinic acid to the polysilicate iron zinc flocculant prepared in step (a), and activating the mixture at room temperature for 30 hours to prepare a polysilicate iron zinc composite flocculant.

[0105] (3) Preparation of composite high-efficiency water purifier for desulfurization wastewater

[0106] In parts by weight, 85 parts of the prepared modified magnesium rectorite slurry flocculant and 15 parts of polysilicate iron zinc composite flocculant are fully mixed and stirred into a mixture. Under the conditions of a vacuum degree of -0.2 MPa and a temperature of 90°C, the mixture is heated and dried. When the moisture content of the mixture is 5%, the heating is stopped and stirring is continued until the temperature of the mixture drops below 40°C. The vacuum is removed and the mixture is ground into a solid powder to obtain a desulfurization wastewater purifier.

[0107] The performance of the composite high-efficiency water purifier for desulfurization wastewater prepared in the embodiment of the present invention is tested below.

[0108] Test Example 1

[0109] Desulfurization wastewater purification performance test

[0110] The desulfurization wastewater composite high-efficiency water purifier prepared in Example 1 of the present invention was added to the desulfurization wastewater taken from Datang Qingyuan Thermal Power Plant at an addition amount of 0.05 g / L. The treatment process was as follows: Figure 1As shown, the original process pipeline is not modified for continuous production and treatment. Specifically, the effluent from the desulfurization wastewater cyclone or the filtrate from the gypsum dehydrator is mixed evenly in the wastewater buffer tank and then sent to the triple box through the wastewater pump. A water purifier is added to the first box (water inlet tank) of the triple box and stirred and mixed at a speed of 100rmp. Then, it is fully reacted through the second and third boxes. During this process, part of the water body is flocculated and separated. Finally, it is further mixed and reacted through the pipeline to make the flocs further adsorbed and dense and increase in volume. When the flocs enter the clarification tank, the substances in the water body are fully flocculated and precipitated and separated. The supernatant is taken for water quality testing. The water quality indicators after treatment are shown in Table 1:

[0111] Table 1: Water quality indicators of desulfurization wastewater after treatment with water purifier in Example 1

[0112]

[0113] The desulfurization wastewater composite high-efficiency water purifier prepared by Example 1 of the present invention is used to treat desulfurization wastewater at a dosage of 0.05g / L. Its components cooperate with each other and synergize. The components interact with each other to form dense aggregates with larger particle sizes. The buoyancy of the aggregates in water is small, and the suspended matter in the water can be effectively adsorbed and settled, thereby improving the flocculation effect and sedimentation efficiency. At the same time, the active sites on the modified magnesium rectorite slurry flocculant are oxidized, chelated and coordinated with the heavy metals and reducing colloids in the wastewater, thereby greatly reducing the COD of the wastewater. In addition, the matrix material and flocculant of the present invention both present a step-by-step layered spatial network structure, which allows the wastewater to be filtered through the layered network structure during the reaction and mixing with it, thereby greatly reducing the heavy metal content and COD of the wastewater. It can be seen from the data in Table 1 that the concentrations of heavy metals and suspended solids in the desulfurization wastewater after treatment with the water purifier of the present invention are lower than the discharge standard in DL / T 997-2006 "Water Quality Control Index of Limestone-Gypsum Wet Desulfurization Wastewater in Thermal Power Plants", and the overall water quality after treatment reaches the discharge standard. The treatment effect of heavy metals and COD in the water is good, and compared with the original treatment process in Comparative Example 1 using 15g / L of NaOH or lime milk, the present invention realizes the upgrading and transformation process of the desulfurization wastewater system of the power plant on the basis of using low dosage of the drug for treatment, effectively reduces the operating cost, simplifies the process flow, has strong practicality, and has broad application prospects.

[0114] Test Example 2

[0115] Desulfurization wastewater purification performance test

[0116] The desulfurization wastewater composite high-efficiency water purifier prepared in Example 2 of the present invention was added to the desulfurization wastewater taken from Tianjin Huaneng Yangliuqing Thermal Power Plant at an addition amount of 0.05 g / L, and the stirring speed was 100 rmp. After treatment according to the method in Test Example 1, the supernatant was taken for water quality detection. The water quality indicators after treatment are shown in Table 2:

[0117] Table 2: Water quality indicators of desulfurization wastewater after treatment with water purifier in Example 2

[0118]

[0119] It can be seen from the data in Table 2 that the desulfurization wastewater is treated with the desulfurization wastewater composite high-efficiency water purifier prepared in Example 2, and the concentrations of heavy metals and suspended solids are lower than the emission standards in DL / T 997-2006 "Water Quality Control Indicators for Limestone-Gypsum Wet Desulfurization Wastewater in Thermal Power Plants", and the overall water quality after treatment meets the emission standards.

[0120] Test Example 3

[0121] Desulfurization wastewater purification performance test

[0122] The desulfurization wastewater composite high-efficiency water purifier prepared in Example 3 of the present invention was added to the desulfurization wastewater taken from the Shiheng Power Plant in Feicheng City at an addition amount of 0.1 g / L, and the stirring speed was 100 rmp. After treatment according to the method in Test Example 1, the supernatant was taken for water quality detection. The water quality indicators after treatment are shown in Table 3:

[0123] Table 3: Water quality indicators of desulfurization wastewater after treatment with water purifier in Example 3

[0124]

[0125] It can be seen from the data in Table 3 that the desulfurization wastewater is treated with the desulfurization wastewater composite high-efficiency water purifier prepared in Example 3, and the concentrations of heavy metals and suspended solids are lower than the emission standards in DL / T 997-2006 "Water Quality Control Indicators for Limestone-Gypsum Wet Desulfurization Wastewater in Thermal Power Plants", and the overall water quality after treatment meets the emission standards.

[0126] Test Example 4

[0127] Desulfurization wastewater purification performance test

[0128] The desulfurization wastewater composite high-efficiency water purifier prepared in Example 4 of the present invention was added to the desulfurization wastewater taken from the National Energy Feixian Power Generation Co., Ltd. at an addition amount of 0.05 g / L, and the stirring speed was 100 rmp. After treatment according to the method in Test Example 1, the supernatant was taken for water quality detection. The water quality indicators after treatment are shown in Table 4:

[0129] Table 4: Water quality indicators of desulfurization wastewater after treatment with water purifier in Example 4

[0130]

[0131] It can be seen from the data in Table 4 that the desulfurization wastewater is treated with the desulfurization wastewater composite high-efficiency water purifier prepared in Example 4, and the concentrations of heavy metals and suspended solids are lower than the emission standards in DL / T 997-2006 "Water Quality Control Indicators for Limestone-Gypsum Wet Desulfurization Wastewater in Thermal Power Plants", and the overall water quality after treatment meets the emission standards.

[0132] It can be seen from the results of Example 1 to Example 4 that the composite high-efficiency water purifier for desulfurization wastewater prepared by the present invention has a good purification effect on desulfurization wastewater in different regions, can be used for upgrading and transforming the desulfurization wastewater systems of different power plants, and has good application prospects.

[0133] Test Example 5

[0134] The wastewater used in the test of Test Example 5 is the same as the desulfurization wastewater from Datang Qingyuan Thermal Power Plant used in the test of Example 1 of the present invention. Figure 2 The traditional dosing treatment process shown in the figure is used for treatment, specifically: the effluent of the desulfurization wastewater cyclone or the filtrate water of the gypsum dehydrator is mixed evenly in the wastewater buffer tank as the desulfurization wastewater raw water and then sent to the triple box through the wastewater pump. In the neutralization box of the triple box, NaOH or lime milk is added at an amount of 15g / L, and the acidic wastewater is quickly stirred to make the acidic wastewater alkaline (the pH value is controlled at 9.0-9.5). In this process, most of the heavy metals form slightly soluble hydroxides and precipitate from the wastewater. The water in the neutralization box flows to the reaction box, and 1.5g / L of organic sulfur and 12g / L are added to the reaction box. The water in the reaction box flows to the flocculation box, and 0.5g / L of coagulant polyacrylamide is added to the flocculation box. After flocculation reaction is carried out by slow stirring, the water in the flocculation box flows to the clarifier. The wastewater flocs gradually become larger in the clarifier, and then precipitate and separate. The supernatant is taken for water quality testing. The water quality indicators after treatment are shown in Table 5:

[0135] Table 5: Water quality indicators of desulfurization wastewater after treatment with traditional dosing treatment process

[0136]

[0137] By comparing the data in Table 1 and Table 5, it can be seen that the various water quality detection pollutant content indicators of the desulfurization wastewater treated by the traditional dosing treatment process are higher than the water quality indicators treated by the composite high-efficiency water purifier of Example 1 of the present invention, indicating that the components in the water purifier of the present invention interact with each other and synergize, and its components can adsorb heavy metals in the wastewater, and form colloids through displacement and precipitation to remove them from the water, and remove suspended matter and insoluble matter in the water body through flocculation, so that they form flocs and then perform solid-liquid separation, thereby reducing the turbidity of the water. And the chemical oxygen demand (COD) content after treatment is unqualified, exceeding the DL / T 997-2006 emission standard. The spatial structure of the water purifier component of the present invention is a step-by-step layered spatial network structure. This structure allows the wastewater to be filtered through the layered network structure during the reaction and mixing process, so that the COD of the wastewater is greatly reduced. The above fully shows that the water purifier of the present invention has a better desulfurization wastewater purification effect than the traditional dosing treatment process.

[0138] At the same time, in combination with Example 1, it can be seen that the addition amount of the water purifier used in the present invention is 0.05g / L, and the addition amount of NaOH or lime milk in the traditional dosing treatment process is generally 15g / L. It can be seen that the present invention can purify the desulfurization wastewater with a smaller dosage of medicine, and at the same time can replace the addition of the original organic sulfur and the addition of flocculants and coagulants, reduce the overall desulfurization wastewater treatment process The amount of medicine added reduces the operating cost of the desulfurization wastewater treatment system, and on the basis of improving the desulfurization wastewater treatment indicators and promoting the desulfurization wastewater discharge to meet the standards, the desulfurization wastewater treatment process is greatly simplified, and has broad application prospects and value.

[0139] Test Example 6

[0140] Test Example 6 The wastewater used for the test treatment comes from the same Datang Qingyuan thermal power desulfurization wastewater as that used in the test of Example 2 of the present invention in Test Example 2. The desulfurization wastewater purifiers prepared in Comparative Examples 1 to Comparative Examples 3 were added to the desulfurization wastewater taken from Datang Qingyuan thermal power at an addition amount of 0.05 g / L, respectively. The desulfurization wastewater was treated according to the steps in Test Example 2, and the supernatant was taken for water quality detection after treatment. The water quality indicators after treatment are shown in Table 6:

[0141] Table 6: Water quality indicators of desulfurization wastewater after treatment with water purifier in comparative example 1-3

[0142]

[0143] From the data in Table 6, it can be seen that the desulfurization wastewater treated with the water purifiers of Comparative Examples 1 to Comparative Examples 3 does not meet the emission standard of DL / T 997-2006, and the desulfurization wastewater treatment effect of Comparative Example 3 is better than that of Comparative Example 1 and Comparative Example 2. Compared with Example 2, Comparative Example 1 does not add the polysilicate iron zinc composite flocculant component, and the zinc content and chemical oxygen demand of the desulfurization wastewater after treatment exceed the standard; Compared with Example 2, Comparative Example 2 does not add the modified magnesium rectorite slurry flocculant component, and the chemical oxygen demand, sulfide and suspended solids content of the desulfurization wastewater after treatment exceed the standard; Compared with Example 2, Comparative Example 3 does not add sodium diethyldithiocarbamate and water-soluble amphoteric starch components, and the chemical oxygen demand of the desulfurization wastewater after treatment exceeds the standard.

[0144] Combined with Test Example 2, it can be seen that by reasonably proportioning the modified magnesium rectorite slurry flocculant of the water purifier A component of the present invention, the polysilicate iron zinc composite flocculant of the B component, the sodium diethyl dithiocarbamate of the C component and the water-soluble amphoteric starch of the D component, the components cooperate with each other and synergize, and the modified magnesium rectorite slurry flocculant is used as the matrix material, and the polysilicate iron zinc composite flocculant promotes the number and strength of coordination bonds formed between magnesium ions and the hydroxyl and amino groups of polysaccharides, and forms large and dense aggregates under the action of coordination bonds. After the synergistic effect, the matrix material and the flocculant both present a step-by-step layered spatial network structure, which allows the wastewater to be filtered through the layered network structure during the reaction and mixing process, greatly reducing the heavy metal content and COD of the wastewater. And by adding sodium diethyldithiocarbamate, the completeness and thoroughness of heavy metal removal in wastewater treatment is guaranteed, and by adding water-soluble amphoteric starch, the coagulation property is more obviously and thoroughly enhanced from the perspective of charge neutralization and intermolecular adsorption bridging flocculation, the sedimentation rate is accelerated, the flocs are increased, and the flocculation is more thorough. Therefore, the composite high-efficiency water purifier for desulfurization wastewater of the present invention can synergistically exert a significant desulfurization wastewater treatment purification effect when the components are reasonably proportioned, so as to simplify the desulfurization wastewater treatment process.

[0145] In summary, the preparation method and application of the composite high-efficiency water purifier for desulfurization wastewater of the present invention are simple in preparation method and have a wide source of raw materials. The components in the water purifier interact with each other and synergize to remove colloids such as heavy metals, suspended matter and insoluble matter in the water body through flocculation, so that floccules are formed and then solid-liquid separation is performed to reduce turbidity. On the basis of using a smaller dosage of chemicals, the present invention can replace the addition of the original flocculant / coagulant aid, and at the same time can reduce the dosage of the original lime, reduce the dosage of the overall desulfurization wastewater treatment process, and thus reduce the operating cost of the desulfurization wastewater treatment system, simplify the process design of desulfurization wastewater treatment and the cost investment of the reagent, significantly improve the treatment efficiency of suspended matter in the water body, improve the water purification rate, and realize the upgrading of the existing desulfurization wastewater treatment process. It is applicable to a wide range of water types and has a low treatment cost. It has broad application prospects in the fields of chemical industry, water treatment, heavy metal recovery, etc.

[0146] The above are only embodiments of the present invention. For example, the silicate used in the embodiments is sodium silicate and the organic polysaccharide is cellulose. In practical applications, the effects of the present invention can be achieved by using other types of silicates and polysaccharides.

[0147] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A method for preparing a composite water purifier for desulfurization wastewater, characterized in that: The composition is composed of the following raw materials in parts by weight: 75-85 parts of modified magnesium rectorite slurry flocculant as component A, 15-20 parts of polysilicate iron zinc composite flocculant as component B, 5-10 parts of sodium diethyl dithiocarbamate as component C, and 1-3 parts of water-soluble amphoteric starch as component D; After the above raw materials are mixed and stirred, they are heated and dried under vacuum conditions. When the moisture content of the mixture is lower than 8%, the heating is stopped and the stirring is continued until the temperature of the mixture drops below 40° C., the vacuum is removed, and the mixture is ground into a solid powder to obtain a composite water purifier for desulfurization wastewater; The following steps are also included: (1) Preparation of modified magnesium rectorite slurry flocculant A certain amount of magnesium sulfate, organic polysaccharide and magnesium polyphosphate are added to a hydrated slurry of natural rectorite, the above materials are stirred evenly, ball milled, sealed and aged to obtain a modified magnesium rectorite flocculant; Wherein: the mass ratio of the added amounts of rectorite, magnesium sulfate, organic polysaccharide and magnesium polyphosphate is: rectorite: magnesium sulfate: organic polysaccharide: magnesium polyphosphate = 100:5-10:5:1-5; (2) Preparation of polysilicate iron zinc composite flocculant (a) diluting silicate solid with water to obtain a silicate aqueous solution with a mass fraction of SiO2 of 3% to 5%, and adjusting the pH value to 5.0 to 5.5 using a pH adjuster; stirring and observing that the silicate aqueous solution gradually changes from clear to milky white, and the bubbles gradually become smaller; when the bubbles are about to disappear, immediately adding a certain amount of saturated aqueous solution of Fe2(SO4)3 and saturated aqueous solution of ZnSO4, stirring until the reaction is complete, and obtaining a polysilicate iron zinc flocculant; The mass ratio of the silicate aqueous solution, the saturated Fe2(SO4)3 aqueous solution and the saturated ZnSO4 aqueous solution is: silicate aqueous solution: saturated Fe2(SO4)3 aqueous solution: saturated ZnSO4 aqueous solution = 100: 10-20: 10-20; (b) adding 2% to 5% by weight of polyepoxysuccinic acid to the polysilicate iron zinc flocculant prepared in step (a), activating the mixture at room temperature to prepare a polysilicate iron zinc composite flocculant; (3) Preparation of composite water purifier for desulfurization wastewater In parts by weight, 75-85 parts of the modified magnesium rectorite slurry flocculant prepared as component A, 15-20 parts of the polysilicate iron zinc composite flocculant as component B, 5-10 parts of sodium diethyldithiocarbamate as component C and 1-3 parts of water-soluble amphoteric starch as component D are mixed and stirred, and the mixture is heated and dried under the conditions of a vacuum degree of -0.2 to -0.1 MPa and a temperature of 85°C to 90°C. When the moisture content of the mixture is lower than 8%, the heating is stopped and the stirring is continued until the temperature of the mixture drops below 40°C, the vacuum is removed, and the mixture is ground into a solid powder to obtain a desulfurization wastewater composite water purifier.

2. The method for preparing a composite water purifier for desulfurization wastewater according to claim 1, characterized in that: The particle size of the rectorite in step (1) is 300-400 mesh.

3. The method for preparing a composite water purifier for desulfurization wastewater according to claim 1, characterized in that: In step (3), the water-soluble amphoteric starch is an amphoteric starch having a carboxymethyl group and a quaternary ammonium group.

4. The method for preparing a composite water purifier for desulfurization wastewater according to claim 3, characterized in that: The anionic substitution degree of the water-soluble amphoteric starch is 0.7-1.0, and the cationic substitution degree is 0.15-0.

20.

5. The method for preparing a composite water purifier for desulfurization wastewater according to claim 1, characterized in that: In step (1), the pH adjusting agent is a 40% by mass H2SO4 solution and a 40% by mass NaOH solution.

6. The method for preparing a composite water purifier for desulfurization wastewater according to claim 1, characterized in that: The ball milling process in step (1) is as follows: the material is ball milled in a ceramic ball mill for 3h-4h, and then taken out and sealed for aging for 24h-30h.

7. The method for preparing a composite water purifier for desulfurization wastewater according to claim 1, characterized in that: In step (2), the activation time of the polysilicate iron zinc flocculant and polyepoxysuccinic acid is 24h-30h.

8. A composite water purifier for desulfurization wastewater, characterized in that: The composite water purifier for desulfurization wastewater is prepared according to the preparation method of any one of claims 1 to 7.

9. The use of a composite water purifier for desulfurization wastewater according to claim 8 in the treatment of desulfurization wastewater, characterized in that: The addition amount of the desulfurization wastewater composite water purifier in the desulfurization wastewater is 0.05g / L-0.1g / L.

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