A method for treating high-salt coal chemical fluorine-containing wastewater

Abstract

The present application relates to a kind of high-salt coal chemical fluorine-containing wastewater treatment methods, comprising (1) adding fluoride removal agent in wastewater, adjust pH to 6.5-7.5, after stirring reaction, adjust pH to 5.5-6.4 again, after stirring reaction, stand, separate out precipitate, obtain primary defluorination wastewater;(2) introducing flocculating agent in primary defluorination wastewater, after stirring reaction, stand, separate out precipitate and obtain water;The flocculating agent is polymeric silicic acid-based inorganic-organic hybrid flocculating agent.The treatment method of the present application not only has high pollutant removal rate, but also is simple and easy to operate, and has lower investment and operating cost.

Description

Technical Field

[0001] This invention belongs to the field of water pollution control technology, specifically relating to a method for treating high-salt coal chemical fluoride-containing wastewater. Background Technology

[0002] Among the trace elements contained in coal, fluoride content is relatively high, mostly ranging from 20-300 mg / kg, resulting in excessive fluoride ion content in coal chemical wastewater. Excessive fluoride ion content easily causes severe equipment corrosion, harms the environment, and affects crop growth and human bone health. The Class I standard of the "Integrated Wastewater Discharge Standard" (GB 8798-1996) stipulates that the maximum allowable discharge concentration of fluoride is 10 mg / L. Therefore, simple, low-cost, and efficient treatment of fluoride ions in wastewater is of great significance.

[0003] Traditional defluoridation methods include chemical precipitation, coagulation sedimentation, adsorption, reverse osmosis, and electrodialysis. Among these, reverse osmosis and electrodialysis have high process costs and are difficult to implement on a large scale in industrial applications. Adsorption is more suitable for the treatment of low-fluoride wastewater and the advanced treatment of fluoride-containing wastewater. The combination of chemical precipitation and coagulation sedimentation is currently the most widely studied and applied method in the treatment of fluoride-containing wastewater.

[0004] Chemical precipitation typically involves adding calcium-containing agents such as CaCl2, Ca(OH)2, and CaO to fluoride-containing wastewater. When the Ca in the water... 2+ and F - When the concentration reaches supersaturation, CaF2 precipitate will form. Since CaF2 is a slightly soluble mineral, homogeneous nucleation and crystallization requires high reaction kinetics, and the resulting calcium fluoride sludge is amorphous with high water content, resulting in poor settling and ultimately unsatisfactory defluorination. Especially in complex, high-salt wastewater environments, such as high-salt coal chemical wastewater, the presence of scale inhibitors, complexing agents, and high concentrations of inorganic salt ions increases the solubility of CaF2, further complicating defluorination. Some researchers have proposed adding seed crystals such as quartz sand, calcite, apatite, and CaF2 to fluoride-containing wastewater to promote heterogeneous CaF2 nucleation, thereby reducing the initial calcium concentration and further lowering the fluoride ion concentration. However, limited by the solubility of CaF2, chemical precipitation can generally reduce the fluoride ion concentration in wastewater to between 20-30 mg / L. Deep removal of fluoride ions, i.e., reducing the concentration to below 10 mg / L, often requires further coagulation and sedimentation. In addition, the CaF2 precipitate, coagulation precipitate, and hardness precipitate generated, as newly formed suspended solids, also require further turbidity removal treatment.

[0005] CN111439865A proposes a method for defluoridation of coal gasification wastewater. First, the wastewater undergoes pre-oxidation treatment to remove scale inhibitors. Then, reflux adsorption sludge is added to the pre-oxidized wastewater for primary defluoridation, yielding primary defluoridated wastewater. 10%-20% of the primary defluoridated wastewater is injected into a seed tank, and a composite defluoridating agent is added. The wastewater reacts with the composite defluoridating agent to form metal fluoride crystals, creating metal fluoride-containing crystal nuclei. This in-situ generated seed crystals replace externally added seed crystals, promoting heterogeneous CaF2 nucleation. The remaining primary defluoridated wastewater and the wastewater containing metal fluoride crystal nuclei are then fed into a reaction tank. The composite defluoridating agent continues to react with fluoride ions in the primary defluoridated wastewater, enriching them on the metal fluoride crystal nuclei, causing crystal growth and the formation of metal fluoride crystals. Finally, polyaluminum chloride, a coagulant, is added for coagulation treatment, yielding secondary defluoridated wastewater. The fluoride ion concentration in the secondary defluorination wastewater was reduced to 10-15 mg / L. This invention employs a combined process of pre-oxidation, pre-adsorption, in-situ seed crystal-induced defluorination, and coagulation for the defluorination of coal gasification wastewater, but the process flow is still relatively lengthy.

[0006] CN210764753U discloses a pretreatment system for zero-discharge of high-salinity wastewater from coal coking. In the defluorination stage, it requires the addition of calcium chloride, ferric chloride, and polyacrylamide in two steps. Furthermore, due to the introduction of calcium chloride, a hardening removal stage is necessary, requiring the step-by-step addition of liquid alkali, sodium carbonate, ferric chloride, and polyacrylamide. This results in high reagent consumption and a complex process flow. In addition, since acidic pH is suitable for defluorination and alkaline pH is suitable for hardening removal, this invention involves the addition of both alkali and acid, leading to high acid and alkali consumption and increasing the burden on subsequent membrane desalination.

[0007] Therefore, simple, efficient, and applicable treatment methods for fluoride-containing wastewater from coal chemical industry in high-salt environments still need to be developed. Summary of the Invention

[0008] To address the shortcomings of existing treatment technologies for high-salinity coal chemical wastewater containing fluoride, such as complex processes and high reagent consumption, this invention provides a method for treating such wastewater. This method not only achieves a high pollutant removal rate but also features simple operation and low investment and operating costs.

[0009] To achieve the objective of this invention, a method for treating high-salinity coal chemical fluoride-containing wastewater is provided, comprising the following steps:

[0010] (1) Add defluorinating agent to wastewater, adjust pH to 6.5-7.5, stir and react, then adjust pH to 5.5-6.4 again, stir and react, let stand, separate the precipitate, and obtain primary defluorinated wastewater.

[0011] (2) A flocculant is introduced into the primary defluorination wastewater, and after stirring and reaction, it is allowed to stand and the precipitate is separated to produce water; the flocculant is a polymeric silicate-based inorganic-organic hybrid flocculant.

[0012] In step (1), the concentration of fluoride ions in the high-salt coal chemical fluoride wastewater is higher than 10 mg / L, generally 20-100 mg / L; the TDS concentration is greater than 10000 mg / L; and the pH is 8-10.

[0013] In step (1), the defluorinating agent is a calcium compound, preferably at least one of calcium chloride, calcium hydroxide, calcium oxide, etc., and the dosage of the defluorinating agent is 300-800 mg / L based on calcium.

[0014] In step (1), pH adjustment involves adjusting the wastewater from its initial pH to 6.5-7.5; the stirring reaction rate is 300-500 rpm, and the stirring time is 10-30 min.

[0015] In step (1), after adjusting the pH to 5.5-6.4 again, the stirring rate is 200-400 rpm and the stirring time is 10-30 min; the standing time is 30-60 min.

[0016] In step (2), the introduced flocculant is a polymeric silicate-based inorganic-organic hybrid flocculant, and its preparation method is as follows:

[0017] (a) Prepare a sodium silicate solution, adjust the pH to 3-6, and activate it to obtain mixed solution I;

[0018] (b) Prepare an organic monomer solution, wherein the organic monomers are carboxylic acid monomers and sulfonic acid monomers, adjust the pH to 3-6, and obtain mixed solution II;

[0019] (c) Mix liquids I and II, place them in a constant temperature water bath, add an initiator under an inert atmosphere, and carry out a polymerization reaction to obtain a polymerized silicate-based inorganic-organic hybrid flocculant.

[0020] In step (a) of the above method, the sodium silicate solution has a SiO2 molar concentration of 0.1-0.5 mol / L.

[0021] In step (a) of the above method, the pH is adjusted using an inorganic or organic acid. The inorganic acid can be at least one of hydrochloric acid, sulfuric acid, phosphoric acid, or hydrobromic acid, preferably phosphoric acid; the organic acid can be at least one of citric acid, oxalic acid, formic acid, or acetic acid, preferably acetic acid. The inorganic or organic acid is prepared to a concentration of 0.1-1 mol / L for use. After pH adjustment, an activation reaction is carried out at room temperature for 0.5-1 h.

[0022] In step (b) of the above method, the carboxylic acid monomer may be at least one of acrylic acid, methacrylic acid or maleic acid, and the concentration of the carboxylic acid monomer solution is 0.5-2.0 mol / L.

[0023] In step (b) of the above method, the sulfonic acid monomer may be at least one of vinyl sulfonic acid or 2-acrylamido-2-methylpropanesulfonic acid, and the mass ratio of the sulfonic acid monomer to the carboxylic acid monomer is 1:9-1:1.

[0024] In step (b) of the above method, the pH is adjusted by adding alkali solution dropwise under stirring conditions. The stirring rate is 200-500 rpm, and the dropping rate is 0.1-0.5 mL / min. The alkali can be at least one of NaOH, KOH, or NH3·H2O, and the concentration of the alkali solution is 0.1-1.0 mol / L.

[0025] In step (c) of the above method, mixtures I and II are mixed at a volume ratio of 5:1 to 50:1. The temperature of the constant temperature water bath is 40-90℃.

[0026] In step (c) of the above method, the inert atmosphere is in the presence of nitrogen or an inert gas, wherein the inert gas is at least one of helium, argon, etc.

[0027] In step (c) of the above method, the initiator can be at least one of a redox initiator or an azo initiator. The redox initiator can be at least one group selected from ammonium persulfate and sodium bisulfite, potassium persulfate and sodium bisulfite, etc. The azo initiator can be at least one selected from azobisisobutyramidine hydrochloride, azobisisobutyramidine imidazoline hydrochloride, etc., preferably an azo initiator.

[0028] In step (c) of the above method, the mass ratio of initiator to organic monomer is 1:1000-1:50. The polymerization reaction time is 8-24 hours.

[0029] In step (2), the dosage of the polymeric silicate-based inorganic-organic hybrid flocculant is 10-200 mg / L.

[0030] In step (2), the stirring rate after adding the flocculant is 100-500 rpm, and the stirring time is 10-30 min. More preferably, after adding the flocculant, the mixture is first stirred at a high speed of 300-500 rpm for 1-10 min, and then stirred at a low speed of 100-295 rpm for 10-20 min.

[0031] In step (2), after the stirring reaction is complete, the standing time is 30-60 minutes.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] (1) In view of the shortcomings of using calcium-containing defluoridating agents for high-salt wastewater from coal chemical industry, this invention utilizes two-stage pH adjustment. The first pH adjustment breaks the complexation between calcium ions and complexing agents, scale inhibitors, or hydroxide ions, releasing some free calcium ions to form calcium fluoride seed crystals. The second pH adjustment further releases calcium ions, promotes the reaction between the remaining fluoride ions and calcium ions, and enriches them on the calcium fluoride crystals, thereby promoting crystal growth. On this basis, the polymeric silicate-based inorganic-organic hybrid flocculant described in this invention is added to achieve the adsorption, coagulation, and rapid separation of fluoride ions. After treatment, the fluoride ion concentration in the wastewater is less than 10 mg / L, and the effluent quality can meet the Class I standard of the Integrated Wastewater Discharge Standard (GB 8798-1996).

[0034] (2) The present invention can induce the generation of seed crystals in situ by means of two-stage pH adjustment, saving the consumption of external seed crystals and facilitating the recycling and reuse of CaF2 crystals.

[0035] (3) The present invention uses a polymeric silicate-based inorganic-organic hybrid flocculant as a flocculant, which acts on both suspended solids and free metal ions to form flocs with larger particle size, which can effectively shorten the separation time of pollutants, reduce turbidity to below 3 NTU, and reduce total hardness to below 200 mg / L, ultimately achieving efficient wastewater treatment.

[0036] (4) Compared with existing processes, the process of the present invention shortens the process flow and reduces the amount of reagents consumed and the amount of slag produced. Therefore, this method has low operating costs, is easy to operate, and has good application prospects. Detailed Implementation

[0037] The technical solution and its effects of the present invention will be further illustrated below with reference to specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0038] Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples were purchased from conventional biochemical reagent stores.

[0039] In this invention, the concentration of fluoride ions in the wastewater was measured using a multi-parameter water quality analyzer (Seven Excellence, Mettler Toledo, Switzerland), the total hardness of the wastewater was measured using EDTA complexometric titration, and the turbidity of the wastewater was measured using a turbidimeter (TL2300EPA, Hach, USA).

[0040] Example 1

[0041] The high-salinity coal chemical wastewater containing fluoride in this embodiment has the following characteristics: pH 8.0, TDS concentration 12000 mg / L, and fluoride ion concentration 80 mg / L. The treatment process is as follows:

[0042] (1) Add 500 mg / L (calculated as calcium) of calcium chloride to the wastewater to adjust the pH to 7.0. Stir at 500 rpm for 10 min, then adjust the pH to 6.0 and stir at 400 rpm for 10 min. The total hardness of the wastewater was found to be 1095 mg / L and the turbidity was 924 NTU. After the reaction, allow the mixture to settle for 1 h to separate the precipitate, obtaining the primary defluoridated wastewater.

[0043] (2) Add 70 mg / L of polymeric silicate-based inorganic-organic hybrid flocculant to the primary defluorination wastewater, stir at 400 rpm for 5 min, then stir at 200 rpm for 15 min, let stand for 30 min, separate the precipitate, and obtain the effluent.

[0044] The preparation method of the polymeric silicate-based inorganic-organic hybrid flocculant is as follows: (a) Prepare a sodium silicate solution with a SiO2 molar concentration of 0.2 mol / L, adjust the pH value to 4 with 0.5 mol / L hydrochloric acid solution, and activate the reaction at room temperature for 1 h to obtain mixed solution I; (b) Prepare acrylic acid and vinyl sulfonic acid solutions, control the concentration of acrylic acid solution to 0.5 mol / L, and the mass ratio of vinyl sulfonic acid to acrylic acid to 1:5. Under stirring at 300 rpm, slowly add 0.5 mol / L NaOH solution at a rate of 0.3 mL / min, and the pH of the final addition is 4 to obtain mixed solution II; (c) Mix mixed solutions I and II at a volume ratio of 10:1, place them in a constant temperature water bath at 70℃, introduce nitrogen gas for 0.5 h, add azobisisobutyramidine hydrochloride initiator, control the mass ratio of initiator to organic monomer to 1:200, carry out the polymerization reaction, and the polymerization reaction time is 10 h to obtain the polymeric silicate-based inorganic-organic hybrid flocculant.

[0045] The test results showed that the fluoride ion concentration in the effluent was 9.87 mg / L, the total hardness was 176 mg / L, and the turbidity was 2.03 NTU.

[0046] Example 2

[0047] The high-salinity coal chemical wastewater containing fluoride in this embodiment has the following characteristics: pH 8.3, TDS concentration 10500 mg / L, and fluoride ion concentration 30 mg / L. The treatment process is as follows:

[0048] (1) Add 300 mg / L (calculated as calcium) of calcium chloride to the wastewater to adjust the pH to 7.5. Stir at 300 rpm for 30 min, then adjust the pH to 6.4 and stir at 300 rpm for 20 min. The total hardness of the wastewater at this point was 705 mg / L, and the turbidity was 463 NTU. After the reaction, allow it to settle for 1 h to separate the precipitate, obtaining the primary defluoridated wastewater.

[0049] (2) Add 40 mg / L of polymeric silicate-based inorganic-organic hybrid flocculant to the primary defluorination wastewater, stir at 500 rpm for 5 min, then stir at 150 rpm for 20 min, let stand for 30 min, separate the precipitate, and obtain the effluent.

[0050] The preparation method of the polymeric silicate-based inorganic-organic hybrid flocculant is as follows: (1) Prepare a sodium silicate solution with a SiO2 molar concentration of 0.5 mol / L, adjust the pH value to 3 with 1 mol / L sulfuric acid solution, activate the reaction at room temperature for 45 min, and obtain mixed solution I; (2) Prepare maleic acid and vinyl sulfonic acid solutions, control the concentration of maleic acid solution to 2 mol / L, and the mass ratio of vinyl sulfonic acid to maleic acid to 1:9, and stir at 500 rpm with 0 Add 1 mol / L KOH solution slowly at a rate of 0.5 mL / min, and control the pH of the final addition point to be 6 to obtain mixture II; (3) Mix mixture I and II at a volume ratio of 50:1, place them in a 90℃ constant temperature water bath, introduce nitrogen gas for 0.5 h, add azobisisobutyrazoline hydrochloride initiator, control the mass ratio of initiator to organic monomer to be 1:1000, carry out polymerization reaction, and the polymerization reaction time is 8 h to obtain polymerized silicate-based inorganic-organic hybrid flocculant.

[0051] The test results showed that the fluoride ion concentration in the effluent was 9.63 mg / L, the total hardness was 195 mg / L, and the turbidity was 2.52 NTU.

[0052] Example 3

[0053] The high-salinity coal chemical wastewater containing fluoride in this embodiment has the following characteristics: pH 7.8, TDS concentration 13200 mg / L, and fluoride ion concentration 50 mg / L. The treatment process is as follows:

[0054] (1) Add 500 mg / L (calculated as calcium) of calcium chloride to the wastewater to adjust the pH to 6.5. Stir at 400 rpm for 20 min, then adjust the pH to 5.8 and stir at 200 rpm for 30 min. The total hardness of the wastewater at this point was 1182 mg / L, and the turbidity was 732 NTU. After the reaction, allow it to settle for 1 h to separate the precipitate, obtaining the primary defluoridated wastewater.

[0055] (2) Add 45 mg / L of polymeric silicate-based inorganic-organic hybrid flocculant to the primary defluorination wastewater, stir at 300 rpm for 10 min, then stir at 200 rpm for 15 min, let stand for 30 min, separate the precipitate, and obtain secondary defluorination wastewater.

[0056] The preparation method of the polymeric silicate-based inorganic-organic hybrid flocculant is as follows: (a) Prepare a sodium silicate solution with a SiO2 molar concentration of 0.1 mol / L, adjust the pH value to 6 with a 0.1 mol / L formic acid solution, and activate the reaction at room temperature for 0.5 h to obtain mixed solution I; (b) Prepare a mixed solution of methacrylic acid and vinyl sulfonic acid, control the concentration of the methacrylic acid solution to be 1 mol / L, and the mass ratio of vinyl sulfonic acid to methacrylic acid to be 1:1, and stir at 200 rpm. (c) Add 0.1 mol / L NH3·H2O solution slowly at a rate of 0.1 mL / min, controlling the pH of the final addition point to be 3, to obtain mixture II; (d) Mix mixture I and II at a volume ratio of 30:1, place in a constant temperature water bath at 40℃, purge with argon gas for 0.5 h, add azobisisobutyramidine hydrochloride initiator, control the mass ratio of initiator to organic monomer to be 1:50, carry out polymerization reaction, and the polymerization reaction time is 24 h to obtain polymerized silicate-based inorganic-organic hybrid flocculant.

[0057] The test results showed that the fluoride ion concentration in the effluent was 9.51 mg / L, the total hardness was 188 mg / L, and the turbidity was 1.98 NTU.

[0058] Example 4

[0059] Same as Example 1, except that calcium hydroxide was used as the defluoridating agent. The final purified water was obtained. Testing showed that the fluoride ion concentration in the effluent was 9.57 mg / L, the total hardness was 184 mg / L, and the turbidity was 2.87 NTU.

[0060] Example 5

[0061] Same as Example 2, except that calcium oxide was used as the defluoridating agent. The final purified water was obtained. Testing showed that the fluoride ion concentration in the effluent was 9.13 mg / L, the total hardness was 191 mg / L, and the turbidity was 2.81 NTU.

[0062] Example 6

[0063] Same as Example 1, except that: in step (2), the agent was not stirred in stages after addition, but was stirred at 400 rpm for 20 minutes. The effluent concentration was 9.89 mg / L, the total hardness was 190 mg / L, and the turbidity was 2.67 NTU.

[0064] Comparative Example 1

[0065] Same as Example 1, except that in step (1), the pH was adjusted to 7.0 only once, and the reaction was stirred at 500 rpm for 20 min. The test results showed that the fluoride ion concentration in the effluent was 16.07 mg / L, the total hardness was 552 mg / L, and the turbidity was 5.08 NTU.

[0066] Comparative Example 2

[0067] Same as Example 1, except that in step (1), the pH was adjusted to 6.0 only once, and the reaction was stirred at 400 rpm for 20 min. The experimental results showed that the fluoride ion concentration in the effluent was 18.67 mg / L, the total hardness was 480 mg / L, and the turbidity was 6.27 NTU.

[0068] Comparative Example 3

[0069] Same as Example 1, except that polyacrylamide was used instead of the polymeric silicate-based inorganic-organic hybrid flocculant of this invention. The test results showed that the fluoride ion concentration in the wastewater was 20.6 mg / L, the total hardness was 702 mg / L, and the turbidity was 23.28 NTU.

[0070] Comparative Example 4

[0071] Same as Example 1, except that polyaluminum chloride was used instead of the polysilicic acid-based inorganic-organic hybrid flocculant of this invention. The test results showed that the fluoride ion concentration in the wastewater was 21.6 mg / L, the total hardness was 756 mg / L, and the turbidity was 32.86 NTU.

Claims

1. A method for treating fluoride-containing wastewater from high-salt coal chemical industry, characterized in that... Includes the following steps: (1) Add defluorinating agent to wastewater, adjust pH to 6.5-7.5, stir and react, then adjust pH to 5.5-6.4 again, stir and react, let stand, separate the precipitate, and obtain primary defluorinated wastewater; (2) Introduce flocculant into primary defluorination wastewater, stir and react, let stand, separate the precipitate and effluent; the flocculant is a polymeric silicate-based inorganic-organic hybrid flocculant; the preparation method of polymeric silicate-based inorganic-organic hybrid flocculant is as follows: (a) prepare sodium silicate solution, adjust pH to 3-6, and activate to obtain mixed solution I; (b) prepare organic monomer solution, the organic monomer is carboxylic acid monomer and sulfonic acid monomer, adjust pH to 3-6, and obtain mixed solution II; the carboxylic acid monomer is at least one of acrylic acid, methacrylic acid or maleic acid, and the concentration of carboxylic acid monomer solution is 0.5-2.0 mol / L; the sulfonic acid monomer is at least one of vinyl sulfonic acid or 2-acrylamido-2-methylpropanesulfonic acid; the mass ratio of sulfonic acid monomer to carboxylic acid monomer is 1:9-1:1; (c) mix mixed solution I and II, place in a constant temperature water bath, add initiator under inert atmosphere, carry out polymerization reaction, and obtain polymeric silicate-based inorganic-organic hybrid flocculant.

2. The method according to claim 1, characterized in that: In step (1), the concentration of fluoride ions in the high-salt coal chemical fluoride wastewater is higher than 10 mg / L, the TDS concentration is greater than 10000 mg / L, and the pH is 8-10.

3. The method according to claim 2, characterized in that: The concentration of fluoride ions in the high-salt coal chemical fluoride wastewater is 20-100 mg / L.

4. The method according to claim 1, characterized in that: In step (1), the defluorinating agent is a calcium compound, and the dosage of the defluorinating agent is 300-800 mg / L based on calcium.

5. The method according to claim 4, characterized in that: The defluorinating agent is at least one of calcium chloride, calcium hydroxide, and calcium oxide.

6. The method according to claim 1, characterized in that: In step (1), pH adjustment is to adjust the wastewater from the initial pH to 6.5-7.5; the stirring reaction rate is 300-500 rpm, and the stirring time is 10-30 min.

7. The method according to claim 1 or 6, characterized in that: In step (1), after adjusting the pH to 5.5-6.4 again, the stirring rate is 200-400 rpm and the stirring time is 10-30 min; the standing time is 30-60 min.

8. The method according to claim 1, characterized in that: In step (a), the sodium silicate solution has a SiO2 molar concentration of 0.1-0.5 mol / L.

9. The method according to claim 1, characterized in that: In step (a), the pH is adjusted using an inorganic acid or an organic acid, wherein the inorganic acid is at least one of hydrochloric acid, sulfuric acid, phosphoric acid or hydrobromic acid; and the organic acid is at least one of citric acid, oxalic acid, formic acid or acetic acid.

10. The method according to claim 9, characterized in that: The inorganic acid is phosphoric acid; the organic acid is acetic acid.

11. The method according to claim 9 or 10, characterized in that: In step (a), the inorganic or organic acid is prepared to a concentration of 0.1-1 mol / L for use; after adjusting the pH, the activation reaction is carried out at room temperature for 0.5-1 h.

12. The method according to claim 1, characterized in that: In step (b), an alkaline solution is added dropwise under stirring conditions to adjust the pH. The stirring rate is 200-500 rpm, and the dropping rate is 0.1-0.5 mL / min. The alkaline solution is at least one of NaOH, KOH, or NH3·H2O, and the concentration of the alkaline solution is 0.1-1.0 mol / L.

13. The method according to claim 1, characterized in that: In step (c), mixtures I and II are mixed at a volume ratio of 5:1 to 50:1; the temperature of the constant temperature water bath is 40-90℃.

14. The method according to claim 1, characterized in that: In step (c), the inert atmosphere is in the presence of nitrogen or an inert gas, wherein the inert gas is at least one of helium and argon.

15. The method according to claim 1, characterized in that: In step (c), the initiator is at least one of a redox initiator or an azo initiator; the redox initiator is at least one group of ammonium persulfate and sodium bisulfite, potassium persulfate and sodium bisulfite; the azo initiator is at least one of azobisisobutyramidine hydrochloride and azobisisobutyramidine hydrochloride.

16. The method according to claim 15, characterized in that: In step (c), the initiator is an azo initiator.

17. The method according to claim 1, characterized in that: In step (c), the mass ratio of initiator to organic monomer is 1:1000-1:50; the polymerization reaction time is 8-24h.

18. The method according to claim 1, characterized in that: The dosage of the polymeric silicate-based inorganic-organic hybrid flocculant is 10-200 mg / L.

19. The method according to claim 1, characterized in that: In step (2), the stirring rate after adding flocculant is 100-500 rpm and the stirring time is 10-30 min.

20. The method according to claim 19, characterized in that: In step (2), after adding the flocculant, first stir at high speed of 300-500 rpm for 1-10 min, and then stir at low speed of 100-295 rpm for 10-20 min.