A water-soluble composite flocculant, its preparation method and application

Abstract

This invention relates to the field of flocculant technology, and discloses a water-soluble composite flocculant, its preparation method, and its application. The raw materials for the water-soluble composite flocculant include: acrylic acid, ethylenediamine, sodium dodecyl sulfonate, modified starch, carboxymethyl cellulose, thiourea, and a solvent. This invention utilizes the polymer adsorption and bridging effects of modified starch and carboxymethyl cellulose, as well as the further entrapment effect of floc formation, ultimately forming a relatively dense network of flocs that settle, thus clarifying the overflow water. The flocculant product prepared by this invention is an aqueous solution with good solubility, good anti-aging properties, and excellent effluent flocculation effect. The raw materials required for preparing the flocculant by this invention are readily available, exhibit excellent flocculation performance, high tailings dewatering efficiency, low dosage, and low preparation cost.

Description

Technical Field

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

[0002] Currently, some quartz sand beneficiation tailings contain high levels of clay minerals such as kaolin. These clay minerals have fine natural particle size, high viscosity, and slow settling speed. Adding conventional flocculants such as PAC and PAM results in poor flocculation and settling effects. Improper operation can cause the overflow water from the thickener to become turbid, which can worsen quartz sand beneficiation production.

[0003] Polyaluminum chloride (PAC) is a water-soluble inorganic polymer intermediate between AlCl3 and Al(OH)3. It possesses strong adsorption and bridging properties, and during hydrolysis, it undergoes physicochemical processes such as coagulation, adsorption, and precipitation. The fundamental difference between PAC and traditional inorganic coagulants lies in their structure. Traditional inorganic coagulants are low-molecular-weight crystalline salts, while PAC's structure consists of multi-component carboxyl complexes with varying morphologies, resulting in rapid flocculation and sedimentation and a wide applicable pH range.

[0004] Polyacrylamide (PAM) is a water-soluble polymer with excellent flocculation properties. It can reduce frictional resistance between liquids and can be classified into four types according to its ionic characteristics: nonionic, anionic, cationic, and amphoteric. Its application in flocculation is related to the type of flocculated material, surface properties, especially zeta potential, viscosity, turbidity, and pH of the suspension. The zeta potential of the particle surface is the cause of particle aggregation inhibition; adding PAM with opposite surface charge can reduce the zeta potential and promote coagulation.

[0005] PAC and PAM are often used together, usually with PAC added first and then PAM added. However, in production practice, this combination of flocculants has not been very effective in treating tailings from quartz sand beneficiation with high clay mineral content. Therefore, it is particularly important to find new flocculants suitable for dewatering this type of quartz sand beneficiation tailings.

[0006] Therefore, it is necessary to develop a water-soluble composite flocculant, its preparation method, and its application to solve the problem of sedimentation and dewatering of tailings from quartz sand beneficiation with high clay mineral content. Summary of the Invention

[0007] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a water-soluble composite flocculant, its preparation method and application, thereby solving the problem of sedimentation and dewatering of tailings from quartz sand beneficiation with high clay mineral content.

[0008] A first aspect of the present invention provides a water-soluble composite flocculant.

[0009] Specifically, the raw materials of the water-soluble composite flocculant include: acrylic acid, ethylenediamine, sodium dodecyl sulfonate, modified starch, carboxymethyl cellulose, thiourea, and solvent.

[0010] Preferably, the solvent includes water.

[0011] Preferably, by weight, the components are 40-50 parts acrylic acid, 20-25 parts ethylenediamine, 6-15 parts sodium dodecyl sulfonate, 4-10 parts modified starch, 4-10 parts carboxymethyl cellulose, 4-10 parts thiourea, and 6-15 parts solvent.

[0012] A second aspect of the present invention provides a method for preparing a water-soluble composite flocculant.

[0013] Specifically, it includes the following steps:

[0014] Acrylic acid and ethylenediamine are mixed, a solvent is added, and the mixture is stirred and heated to 60-75°C to obtain solution A;

[0015] Sodium dodecyl sulfonate, modified starch, carboxymethyl cellulose, and thiourea were added sequentially to solution A and stirred to obtain a water-soluble composite flocculant.

[0016] Preferably, the method for preparing the modified starch includes the following steps:

[0017] By weight, mix 40-50 parts corn starch with 20-25 parts sodium hydroxide, then add 25-40 parts water, stir and heat to 30-50°C to obtain solution B;

[0018] Add 3-10 parts of sodium sulfate to solution B and stir to obtain modified starch.

[0019] A third aspect of the present invention provides an application of a water-soluble composite flocculant in the dewatering of tailings from quartz sand beneficiation.

[0020] Preferably, the method of application includes the following steps:

[0021] (1) Mix the water-soluble composite flocculant with water to obtain a flocculant solution;

[0022] (2) Add the flocculant solution to the inlet of the main pipeline of the quartz sand beneficiation tailings;

[0023] (3) The flocculant solution and the tailings from the quartz sand beneficiation process flow and mix in the main pipeline;

[0024] (4) The quartz sand beneficiation tailings mixed with the flocculant solution enter the thickening tank for flocculation, sedimentation and thickening to obtain concentrated quartz sand beneficiation tailings.

[0025] (5) The concentrated quartz sand beneficiation tailings are fed into a plate and frame filter press by a slurry pump for mud-water separation, and finally the quartz sand beneficiation tailings are dewatered.

[0026] Preferably, in step (1), the mass concentration of the water-soluble composite flocculant in the flocculant solution is 0.1-0.3%.

[0027] Preferably, in step (2), the mass concentration of kaolin in the quartz sand beneficiation tailings is 5-40%.

[0028] Preferably, in step (2), the amount of water-soluble composite flocculant added is 5-15g per ton of quartz sand beneficiation tailings.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] (1) This invention utilizes the polymer adsorption bridging effect of modified starch and carboxymethyl cellulose, as well as the further netting effect of floc formation, to finally form a relatively dense net-like floc settling, making the overflow water clear.

[0031] (2) The flocculant product prepared by the present invention is in the form of an aqueous solution, has good solubility, good anti-aging properties, and excellent effluent flocculation effect.

[0032] (3) The raw materials required for preparing the flocculant of the present invention are readily available, have excellent flocculation performance, and have high efficiency in tailings dewatering, low dosage and preparation cost. Attached Figure Description

[0033] Figure 1 A flowchart illustrating the preparation method of water-soluble composite flocculant and its application in the dewatering of tailings from quartz sand beneficiation.

[0034] Figure 2 This is a comparison chart showing the application effects of water-soluble composite flocculants in the dewatering of quartz sand beneficiation tailings. Detailed Implementation

[0035] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0036] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0037] Example 1

[0038] Water-soluble composite flocculant, its preparation method, and its application in the dewatering of tailings from quartz sand beneficiation.

[0039] The mass concentration of kaolin in the tailings of quartz sand beneficiation is 20%.

[0040] The specific steps are as follows (e.g.) Figure 1 As shown):

[0041] (1) By weight, 42 parts of corn starch and 20 parts of sodium hydroxide are mixed, and then 33 parts of water are added, stirred and heated to 40°C to obtain solution B; 5 parts of sodium sulfate are added to solution B and stirred to obtain modified starch.

[0042] (2) Then, acrylic acid, ethylenediamine, sodium dodecyl sulfonate, modified starch, carboxymethyl cellulose, thiourea, and water are mixed as raw materials to prepare a water-soluble composite flocculant, which specifically includes the following steps:

[0043] Step 1: Mix 44 parts acrylic acid and 22 parts ethylenediamine in the specified proportion, add 10 parts water, stir and heat to 65°C to obtain solution A.

[0044] Step 2: Add 9 parts sodium dodecyl sulfonate, 5 parts modified starch, 5 parts carboxymethyl cellulose, and 5 parts thiourea to solution A in Step 1 in sequence, and stir to obtain a water-soluble composite flocculant.

[0045] (3) Add water-soluble composite flocculant to water to prepare a flocculant solution with a mass concentration of 0.2%.

[0046] (4) Add the flocculant solution to the inlet of the main pipeline of the quartz sand beneficiation tailings at a dosage of 10g of water-soluble composite flocculant per ton of quartz sand beneficiation tailings. The flocculant solution and the quartz sand beneficiation tailings slurry will flow and mix in the main pipeline.

[0047] (5) The quartz sand beneficiation tailings, after being mixed with the flocculant solution, enter the thickening tank for flocculation, sedimentation, and thickening to obtain concentrated quartz sand beneficiation tailings. The concentrated quartz sand beneficiation tailings are then pumped into a plate and frame filter press for slurry-water separation, ultimately achieving dewatering of the quartz sand beneficiation tailings. The flocculation and sedimentation effect is shown in [reference needed]. Figure 2 .

[0048] Example 2

[0049] Water-soluble composite flocculant, its preparation method, and its application in the dewatering of tailings from quartz sand beneficiation.

[0050] The mass concentration of kaolin in the tailings of quartz sand beneficiation is 40%.

[0051] The specific steps are as follows:

[0052] (1) By weight, 42 parts of corn starch and 22 parts of sodium hydroxide are mixed, and then 30 parts of water are added, stirred and heated to 45°C to obtain solution B; 3 parts of sodium sulfate are added to solution B and stirred to obtain modified starch.

[0053] (2) Then, acrylic acid, ethylenediamine, sodium dodecyl sulfonate, modified starch, carboxymethyl cellulose, thiourea, and water are mixed as raw materials to prepare a water-soluble composite flocculant, which specifically includes the following steps:

[0054] Step 1: Mix 46 parts acrylic acid and 23 parts ethylenediamine in the specified proportion, add 8 parts water, stir and heat to 68°C to obtain solution A.

[0055] Step 2: Add 8 parts sodium dodecyl sulfonate, 5 parts modified starch, 5 parts carboxymethyl cellulose, and 5 parts thiourea to solution A in Step 1 in sequence, and stir to obtain a water-soluble composite flocculant.

[0056] (3) Add water-soluble composite flocculant to water to prepare a flocculant solution with a mass concentration of 0.2%.

[0057] (4) Add the flocculant solution to the inlet of the main pipeline of the quartz sand beneficiation tailings at a dosage of 12g of water-soluble composite flocculant per ton of quartz sand beneficiation tailings. The flocculant solution and the quartz sand beneficiation tailings slurry will flow and mix in the main pipeline.

[0058] (5) The quartz sand beneficiation tailings, after being mixed with the flocculant solution, enter the thickening tank for flocculation, sedimentation, and thickening to obtain concentrated quartz sand beneficiation tailings. The concentrated quartz sand beneficiation tailings are then pumped into a plate and frame filter press for slurry-water separation, ultimately achieving dewatering of the quartz sand beneficiation tailings. The flocculation and sedimentation effect is shown in [reference needed]. Figure 2 .

[0059] Example 3

[0060] Water-soluble composite flocculant, its preparation method, and its application in the dewatering of tailings from quartz sand beneficiation.

[0061] The mass concentration of kaolin in the tailings of quartz sand beneficiation is 30%.

[0062] The specific steps are as follows:

[0063] (1) By weight, 48 parts of corn starch and 24 parts of sodium hydroxide were mixed, and then 25 parts of water were added, stirred and heated to 50°C to obtain solution B; 3 parts of sodium sulfate were added to solution B and stirred to obtain modified starch.

[0064] (2) Then, acrylic acid, ethylenediamine, sodium dodecyl sulfonate, modified starch, carboxymethyl cellulose, thiourea, and water are mixed as raw materials to prepare a water-soluble composite flocculant, which specifically includes the following steps:

[0065] Step 1: Mix 48 parts acrylic acid and 24 parts ethylenediamine in a certain proportion, add 10 parts water, stir and heat to 70°C to obtain solution A.

[0066] Step 2: Add 6 parts sodium dodecyl sulfonate, 4 parts modified starch, 4 parts carboxymethyl cellulose, and 4 parts thiourea to solution A in Step 1 in sequence, and stir to obtain a water-soluble composite flocculant.

[0067] (3) Add water-soluble composite flocculant to water to prepare a flocculant solution with a mass concentration of 0.3%.

[0068] (4) Add the flocculant solution to the inlet of the main pipeline of the quartz sand beneficiation tailings at a dosage of 15g of water-soluble composite flocculant per ton of quartz sand beneficiation tailings. The flocculant solution and the quartz sand beneficiation tailings slurry will flow and mix in the main pipeline.

[0069] (5) The quartz sand beneficiation tailings, after being mixed with the flocculant solution, enter the thickening tank for flocculation, sedimentation, and thickening to obtain concentrated quartz sand beneficiation tailings. The concentrated quartz sand beneficiation tailings are then pumped into a plate and frame filter press for slurry-water separation, ultimately achieving dewatering of the quartz sand beneficiation tailings. The flocculation and sedimentation effect is shown in [reference needed]. Figure 2 .

[0070] Example 4

[0071] Water-soluble composite flocculant, its preparation method, and its application in the dewatering of tailings from quartz sand beneficiation.

[0072] The mass concentration of kaolin in the tailings of quartz sand beneficiation is 10%.

[0073] The specific steps are as follows:

[0074] (1) By weight, 40 parts of corn starch and 20 parts of sodium hydroxide are mixed, and then 30 parts of water are added, stirred and heated to 30°C to obtain solution B; 10 parts of sodium sulfate are added to solution B and stirred to obtain modified starch.

[0075] (2) Then, acrylic acid, ethylenediamine, sodium dodecyl sulfonate, modified starch, carboxymethyl cellulose, thiourea, and water are mixed as raw materials to prepare a water-soluble composite flocculant, which specifically includes the following steps:

[0076] Step 1: Mix 40 parts acrylic acid and 20 parts ethylenediamine in the specified ratio, add 15 parts water, stir and heat to 60°C to obtain solution A.

[0077] Step 2: Add 10 parts sodium dodecyl sulfonate, 5 parts modified starch, 5 parts carboxymethyl cellulose, and 5 parts thiourea to solution A in Step 1 in sequence, and stir to obtain a water-soluble composite flocculant.

[0078] (3) Add water-soluble composite flocculant to water to prepare a flocculant solution with a mass concentration of 0.1%.

[0079] (4) Add the flocculant solution to the inlet of the main pipeline of the quartz sand beneficiation tailings at a dosage of 8g of water-soluble composite flocculant per ton of quartz sand beneficiation tailings. The flocculant solution and the quartz sand beneficiation tailings slurry will flow and mix in the main pipeline.

[0080] (5) The quartz sand beneficiation tailings, after being mixed with the flocculant solution, enter the thickening tank for flocculation, sedimentation, and thickening to obtain concentrated quartz sand beneficiation tailings. The concentrated quartz sand beneficiation tailings are then pumped into a plate and frame filter press for slurry-water separation, ultimately achieving dewatering of the quartz sand beneficiation tailings. The flocculation and sedimentation effect is shown in [reference needed]. Figure 2 .

[0081] Example 5

[0082] Water-soluble composite flocculant, its preparation method, and its application in the dewatering of tailings from quartz sand beneficiation.

[0083] The mass concentration of kaolin in the tailings of quartz sand beneficiation is 5%.

[0084] The specific steps are as follows:

[0085] (1) By weight, 44 parts of corn starch and 22 parts of sodium hydroxide are mixed, and then 30 parts of water are added, stirred and heated to 35°C to obtain solution B; 4 parts of sodium sulfate are added to solution B and stirred to obtain modified starch.

[0086] (2) Then, acrylic acid, ethylenediamine, sodium dodecyl sulfonate, modified starch, carboxymethyl cellulose, thiourea, and water are mixed as raw materials to prepare a water-soluble composite flocculant, which specifically includes the following steps:

[0087] Step 1: Mix 42 parts acrylic acid and 21 parts ethylenediamine in the specified ratio, add 12 parts water, stir and heat to 62°C to obtain solution A.

[0088] Step 2: Add 7 parts sodium dodecyl sulfonate, 6 parts modified starch, 6 parts carboxymethyl cellulose, and 6 parts thiourea to solution A in Step 1 in sequence, and stir to obtain a water-soluble composite flocculant.

[0089] (3) Add water-soluble composite flocculant to water to prepare a flocculant solution with a mass concentration of 0.3%.

[0090] (4) Add the flocculant solution to the inlet of the main pipeline of the quartz sand beneficiation tailings at a dosage of 6g of water-soluble composite flocculant per ton of quartz sand beneficiation tailings. The flocculant solution and the quartz sand beneficiation tailings slurry will flow and mix in the main pipeline.

[0091] (5) The quartz sand beneficiation tailings, after being mixed with the flocculant solution, enter the thickening tank for flocculation, sedimentation, and thickening to obtain concentrated quartz sand beneficiation tailings. The concentrated quartz sand beneficiation tailings are then pumped into a plate and frame filter press for slurry-water separation, ultimately achieving dewatering of the quartz sand beneficiation tailings. The flocculation and sedimentation effect is shown in [reference needed]. Figure 2 .

[0092] Comparative Example 1

[0093] Water-soluble composite flocculant, its preparation method, and its application in the dewatering of tailings from quartz sand beneficiation.

[0094] The mass concentration of kaolin in the tailings of quartz sand beneficiation is 20%.

[0095] The specific steps are as follows:

[0096] (1) By weight, 42 parts of corn starch and 20 parts of sodium hydroxide are mixed, and then 33 parts of water are added, stirred and heated to 40°C to obtain solution B; 5 parts of sodium sulfate are added to solution B and stirred to obtain modified starch.

[0097] (2) Then, acrylic acid, ethylenediamine, sodium dodecyl sulfonate, modified starch, carboxymethyl cellulose, thiourea, and water are mixed as raw materials to prepare a water-soluble composite flocculant, which specifically includes the following steps:

[0098] Step 1: Mix 55 parts acrylic acid and 20 parts ethylenediamine in the specified proportion, add 6 parts water, stir and heat to 65°C to obtain solution A.

[0099] Step 2: Add 6 parts sodium dodecyl sulfonate, 4 parts modified starch, 4 parts carboxymethyl cellulose, and 5 parts thiourea to solution A in Step 1 in sequence, and stir to obtain a water-soluble composite flocculant.

[0100] (3) Add water-soluble composite flocculant to water to prepare a flocculant solution with a mass concentration of 0.2%.

[0101] (4) Add the flocculant solution to the inlet of the main pipeline of the quartz sand beneficiation tailings at a dosage of 10g of water-soluble composite flocculant per ton of quartz sand beneficiation tailings. The flocculant solution and the quartz sand beneficiation tailings slurry will flow and mix in the main pipeline.

[0102] (5) The quartz sand beneficiation tailings, after being mixed with the flocculant solution, enter the thickening tank for flocculation, sedimentation, and thickening to obtain concentrated quartz sand beneficiation tailings. The concentrated quartz sand beneficiation tailings are then pumped into a plate and frame filter press for slurry-water separation, ultimately achieving dewatering of the quartz sand beneficiation tailings. The flocculation and sedimentation effect is shown in [reference needed]. Figure 2 .

[0103] Comparative Example 2

[0104] Water-soluble composite flocculant, its preparation method, and its application in the dewatering of tailings from quartz sand beneficiation.

[0105] The mass concentration of kaolin in the tailings of quartz sand beneficiation is 30%.

[0106] The specific steps are as follows:

[0107] (1) By weight, 45 parts of corn starch and 22 parts of sodium hydroxide are mixed, and then 33 parts of water are added, stirred and heated to 45°C to obtain solution B; 3 parts of sodium sulfate are added to solution B and stirred to obtain modified starch.

[0108] (2) Then, acrylic acid, ethylenediamine, sodium dodecyl sulfonate, modified starch, carboxymethyl cellulose, thiourea, and water are mixed as raw materials to prepare a water-soluble composite flocculant, which specifically includes the following steps:

[0109] Step 1: Mix 35 parts acrylic acid and 25 parts ethylenediamine in the specified ratio, add 10 parts water, stir and heat to 68°C to obtain solution A.

[0110] Step 2: Add 10 parts sodium dodecyl sulfonate, 10 parts modified starch, 5 parts carboxymethyl cellulose, and 5 parts thiourea to solution A in Step 1 in sequence, and stir to obtain a water-soluble composite flocculant.

[0111] (3) Add water-soluble composite flocculant to water to prepare a flocculant solution with a mass concentration of 0.2%.

[0112] (4) Add the flocculant solution to the inlet of the main pipeline of the quartz sand beneficiation tailings at a dosage of 12g of water-soluble composite flocculant per ton of quartz sand beneficiation tailings. The flocculant solution and the quartz sand beneficiation tailings slurry will flow and mix in the main pipeline.

[0113] (5) The quartz sand beneficiation tailings, after being mixed with the flocculant solution, enter the thickening tank for flocculation, sedimentation, and thickening to obtain concentrated quartz sand beneficiation tailings. The concentrated quartz sand beneficiation tailings are then pumped into a plate and frame filter press for slurry-water separation, ultimately achieving dewatering of the quartz sand beneficiation tailings. The flocculation and sedimentation effect is shown in [reference needed]. Figure 2 .

[0114] Comparative Example 3

[0115] Application of commercial PAC+PAM combined flocculant in dewatering tailings from quartz sand beneficiation.

[0116] The mass concentration of kaolin in the tailings of quartz sand beneficiation is 15%.

[0117] The specific steps are as follows:

[0118] (1) Add flocculant PAC to water to prepare a flocculant solution with a mass concentration of 3%; add the flocculant PAC solution to the overflow trough of the desliming bucket according to the addition amount of 1000g flocculant PAC per ton of quartz sand beneficiation tailings.

[0119] (2) Add flocculant PAM to water to prepare a flocculant solution with a mass concentration of 0.2%; add the flocculant PAM solution to the inlet of the main pipeline of the quartz sand beneficiation tailings at an addition rate of 15g of flocculant PAM per ton of quartz sand beneficiation tailings. The flocculant solution and the quartz sand beneficiation tailings flow and mix in the pipeline.

[0120] (3) The quartz sand beneficiation tailings slurry, after being mixed with the flocculant solution, enters a thickening tank for flocculation, sedimentation, and concentration to obtain concentrated quartz sand beneficiation tailings. The concentrated quartz sand beneficiation tailings are then pumped into a plate and frame filter press for slurry-water separation, ultimately achieving dewatering of the quartz sand beneficiation tailings. The flocculation and sedimentation effect is shown in [reference needed]. Figure 2 .

[0121] This invention relates to a water-soluble composite flocculant formulated with surfactants such as acrylic acid, ethylenediamine, sodium dodecyl sulfonate, modified starch, and carboxymethyl cellulose. This flocculant leverages the advantages of each component, achieving a synergistic effect and effectively flocculating and dewatering tailings from quartz sand beneficiation with high clay mineral content. Figure 2 It can be seen that the water-soluble composite flocculant prepared by the present invention is used for dewatering tailings of quartz sand beneficiation, and achieves good flocculation and sedimentation effect. The overflow water of the thickening tank has a high degree of clarity, which better ensures the normal production of quartz sand beneficiation.

[0122] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, any technical solutions obtained by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concept of the present invention and on the existing technology should be within the scope of protection defined by the claims.

Claims

1. A water-soluble complex flocculant, characterized by, The raw materials of the water-soluble composite flocculant include 40-50 parts of acrylic acid, 20-25 parts of ethylenediamine, 6-15 parts of sodium dodecyl sulfonate, 4-10 parts of modified starch, 4-10 parts of carboxymethyl cellulose, 4-10 parts of thiourea and 6-15 parts of solvent. The preparation method of the water-soluble composite flocculant comprises the following steps: The acrylic acid and the ethylenediamine are mixed, the solvent is added and stirred, and heated to 60-75℃ to obtain solution A; The sodium dodecyl sulfonate, the modified starch, the carboxymethyl cellulose and the thiourea are sequentially added to the solution A and stirred to obtain the water-soluble composite flocculant.

2. The water-soluble complex flocculant according to claim 1, characterized by, The solvent comprises water.

3. The water soluble complex flocculant according to claim 1, characterized by, The preparation method of the modified starch comprises the following steps: 40-50 parts of corn starch and 20-25 parts of sodium hydroxide are mixed, 25-40 parts of water is added, stirred and heated to 30-50℃ to obtain solution B; 3-10 parts of sodium sulfate is added to the solution B and stirred to obtain the modified starch.

4. The water-soluble composite flocculant according to any one of claims 1-3 is applied in the dehydration of quartz sand beneficiation tailings.

5. Use according to claim 4, characterized in that, The application method comprises the following steps: (1) mixing the water-soluble composite flocculant and water to obtain a flocculant solution; (2) adding the flocculant solution to the inlet of the total pipeline of the quartz sand beneficiation tailings; (3) mixing the flocculant solution and the quartz sand beneficiation tailings in the total pipeline; (4) the quartz sand beneficiation tailings mixed with the flocculant solution enter the thickening tank for flocculation, sedimentation, thickening to obtain thickened quartz sand beneficiation tailings; (5) the thickened quartz sand beneficiation tailings are input into a plate and frame filter press by a slurry pump for separation of the slurry and water, and finally realizing the dehydration of the quartz sand beneficiation tailings.

6. Use according to claim 5, characterized in that, In step (1), the mass concentration of the water-soluble composite flocculant in the flocculant solution is 0.1-0.3%.

7. Use according to claim 5, characterized in that, In step (2), the mass concentration of kaolin in the quartz sand beneficiation tailings is 5-40%.

8. Use according to claim 5, characterized in that, In step (2), the addition amount of the water-soluble composite flocculant is 5-15 g per ton of quartz sand beneficiation tailings.

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