Composite flocculant as well as preparation method and use method thereof

Abstract

The invention aims to provide a composite flocculant as well as a preparation method and a use method thereof, aiming at the problems existing in the use of the existing flocculant. The composite flocculating agent is a mixture obtained by polymerizing inorganic salt containing aluminum and iron, polyoxyethylene and dimethyl diallyl ammonium chloride, wherein the inorganic salt containing aluminum and iron is obtained by treating iron tailings through acid liquor. The composite flocculant not only retains the advantages of high settling speed and wide application range of an inorganic flocculant, but also has the advantages of high flocculation speed, strong adsorption bridging performance and small sludge generation amount of an organic polymer flocculant, and can quickly flocculate granular turbid substances to achieve the effect of purifying water. And dosing is convenient, and the cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment products, and specifically relates to a composite flocculant and a preparation and use method thereof. Background Art

[0002] Water resources are an important resource that is indispensable in daily life and social production. With the progress of society and the objective requirements of industrial development, the generation of various industrial wastewaters has brought great pressure to the utilization of freshwater resources. The secondary utilization of wastewater and sewage and the secondary purification technology of ordinary water have become the focus of research. Flocculation is one of the most common and important technologies in the field of water treatment. It is a way of combining physical and chemical treatment methods. This process has the characteristics of large processing capacity, relatively low cost, and wide adaptability. It still occupies an important position in the water purification process. High-efficiency flocculants are the core elements of flocculation. Flocculants are one of the key factors that determine the flocculation effect and even the entire water treatment effect. The flocculation effect has a great influence on the final effluent water quality, treatment cost and operating conditions of subsequent processes.

[0003] Flocculants can be divided into inorganic flocculants, organic flocculants, and microbial flocculants. Inorganic flocculants have the advantages of strong electrical neutralization ability, simple preparation process, wide sources, low price, and non-toxicity, but they also have problems such as large dosage, large scum production, small floc volume, and poor stability. Organic polymer flocculants have the advantages of strong adsorption and bridging performance, low dosage, low scum production, and high flocculation efficiency, but they have problems such as high price and difficulty in sinking flocs. Simply mixing the two can improve the water treatment effect of the flocculant to a certain extent, but inorganic flocculants and organic flocculants are added separately, requiring two feeding devices, and there are factors such as inconvenience in adding drugs and whether they can be used directly. Therefore, it is necessary to study a composite flocculant with good treatment effect, high efficiency, convenient dosing, low cost, and environmental friendliness. Summary of the invention

[0004] The purpose of the present invention is to provide a composite flocculant and its preparation and use method in view of the problems existing in the use of existing flocculant agents. The composite flocculant of the present invention not only retains the advantages of inorganic flocculants in terms of fast sedimentation speed and wide application range, but also has the advantages of organic polymer flocculants in terms of fast flocculation speed, strong adsorption and bridging performance, and small amount of generated sludge, and can quickly flocculate granular turbidity to achieve the effect of water purification. It is also convenient to add the drug and reduce the cost.

[0005] The technical scheme of the present invention is a composite flocculant, which is a mixture obtained by polymerizing an inorganic salt containing aluminum and iron obtained by treating iron tailings with acid, polyethylene oxide and dimethyl diallyl ammonium chloride.

[0006] The present invention also provides a method for preparing the composite flocculant, comprising the following steps:

[0007] Step 1: Mix iron tailings (TFe mass percentage ≥ 9%, Al2O3 mass percentage ≥ 3%) with acid solution, react at a temperature of 75-85°C for 1-2h, then filter, concentrate and dry the filtrate to obtain an inorganic salt containing aluminum and iron;

[0008] Step 2: Add polyethylene oxide, dimethyldiallylammonium chloride and an inorganic salt containing aluminum and iron into a container, then add water and stir at a speed of 300-400 r / min for 15-20 minutes to obtain a solution A;

[0009] Step 3: Add a surfactant to solution A, stir at a speed of 300-400 r / min for 20-30 min, and simultaneously introduce nitrogen into the reaction solution for deoxygenation to obtain solution B;

[0010] Step 4: Add initiator to solution B to initiate polymerization reaction. After reacting for 1.5 to 2 hours at a rotation speed of 300-400 r / min, raise the solution temperature to 60-80°C, react for 4-6 hours, filter the precipitate, and dry to obtain a composite flocculant.

[0011] Furthermore, in the preparation method of the composite flocculant, in step 1, the acid solution is hydrochloric acid or sulfuric acid or a mixed solution of the two with a mass concentration of 8 to 15%.

[0012] Furthermore, in the preparation method of the composite flocculant, in step 1, the mass ratio of the iron tailings to the acid solution is 1:3-5.

[0013] Furthermore, in the preparation method of the above-mentioned composite flocculant, in step 2, the added mass ratio of polyethylene oxide, dimethyldiallyl ammonium chloride, inorganic salt containing aluminum and iron, and water is: 6-10 parts of polyethylene oxide, 8-12 parts of dimethyldiallyl ammonium chloride, 10-12 parts of inorganic salt containing aluminum and iron, and 100 parts of water.

[0014] Furthermore, in the preparation method of the composite flocculant, in step 3, the surfactant is dodecyltrimethylammonium chloride, or hexadecyltrimethylammonium chloride, or a mixture of the two.

[0015] Furthermore, in the preparation method of the composite flocculant, in step 3, the amount of surfactant added is 0.6-0.8 parts.

[0016] Furthermore, in the method for preparing the composite flocculant, in step 4, the initiator is one or more of potassium persulfate, ammonium persulfate and ammonium ferrous sulfate.

[0017] Furthermore, in the preparation method of the composite flocculant, in step 4, the amount of initiator added is 0.1-0.2 parts.

[0018] The present invention also provides a method for using the composite flocculant, which is to add the composite flocculant into water with suspended matter ≥500 mg / L and let it stand for 3 to 5 minutes, wherein 6 to 10 g of the composite flocculant is added per ton of water.

[0019] Compared with the prior art, the advantages of the present invention are:

[0020] 1. The composite flocculant of the present invention not only has the advantages of fast settling speed and wide application range of inorganic flocculants, but also has the advantages of fast flocculation speed, strong adsorption and bridging performance, and less sludge generation of organic polymer flocculants, with good flocculation effect and fast flocculation speed.

[0021] 2. The composite flocculant of the present invention has a wide range of applications and has extremely strong flocculation and precipitation capabilities for various conditions such as low turbidity and high turbidity. The composite flocculant treats high turbidity wastewater (suspended matter in water>1000mg / L) and low turbidity wastewater (suspended matter in water>500mg / L), and the turbidity of suspended matter in the water is lower than 50mg / L after 3 minutes.

[0022] 3. The composite flocculant of the present invention is convenient for adding medicine during water treatment, saves equipment investment, and achieves the purpose of improving water purification efficiency and saving costs. DETAILED DESCRIPTION

[0023] A method for preparing a composite flocculant comprises the following steps:

[0024] Step 1: Mix iron tailings (TFe mass percentage ≥ 9%, Al2O3 mass percentage ≥ 3%) with acid solution, react at a temperature of 75-85°C for 1-2h, then filter, concentrate and dry the filtrate to obtain an inorganic salt containing aluminum and iron;

[0025] Step 2: Add polyethylene oxide, dimethyldiallylammonium chloride and an inorganic salt containing aluminum and iron into a container, then add water and stir at a speed of 300-400 r / min for 15-20 minutes to obtain a solution A;

[0026] Step 3: Add a surfactant to solution A, stir at a speed of 300-400 r / min for 20-30 min, and simultaneously introduce nitrogen into the reaction solution for deoxygenation to obtain solution B;

[0027] Step 4: Add initiator to solution B to initiate polymerization reaction. After reacting for 1.5 to 2 hours at a rotation speed of 300-400 r / min, raise the solution temperature to 60-80°C, react for 4-6 hours, filter the precipitate, and dry to obtain a composite flocculant.

[0028] Furthermore, in the preparation method of the composite flocculant, in step 1, the acid solution is hydrochloric acid or sulfuric acid or a mixed solution of the two with a mass concentration of 8 to 15%.

[0029] Furthermore, in the preparation method of the composite flocculant, in step 1, the mass ratio of the iron tailings to the acid solution is 1:3-5.

[0030] Furthermore, in the preparation method of the above-mentioned composite flocculant, in step 2, the added mass ratio of polyethylene oxide, dimethyldiallyl ammonium chloride, inorganic salt containing aluminum and iron, and water is: 6-10 parts of polyethylene oxide, 8-12 parts of dimethyldiallyl ammonium chloride, 10-12 parts of inorganic salt containing aluminum and iron, and 100 parts of water.

[0031] Furthermore, in the preparation method of the composite flocculant, in step 3, the surfactant is dodecyltrimethylammonium chloride, or hexadecyltrimethylammonium chloride, or a mixture of the two.

[0032] Furthermore, in the preparation method of the composite flocculant, in step 3, the amount of surfactant added is 0.6-0.8 parts.

[0033] Furthermore, in the method for preparing the composite flocculant, in step 4, the initiator is one or more of potassium persulfate, ammonium persulfate and ammonium ferrous sulfate.

[0034] Furthermore, in the preparation method of the composite flocculant, in step 4, the amount of initiator added is 0.1-0.2 parts.

[0035] A method for using a composite flocculant is provided, which comprises adding the composite flocculant into water with a suspended matter content of ≥500 mg / L and letting the water stand for 3 to 5 minutes, wherein 6 to 10 g of the composite flocculant is added into each ton of water.

[0036] The specific implementation methods of the present invention are further explained below in conjunction with specific examples. The following implementation cases are only part of the implementation cases of the present invention.

[0037] Example

[0038] A preparation method and application of a composite flocculant, comprising the following specific steps:

[0039] Step 1: The iron tailings (TFe content 12.76%, Al2O3 content 4.22%) were mixed with a mixed solution of 10% hydrochloric acid and sulfuric acid at a solid-liquid mass ratio of 1:4, placed in an acid-resistant reactor, reacted at a temperature of 80°C for 2h, and concentrated and dried to obtain an inorganic salt containing aluminum and iron.

[0040] Step 2: Add 6 parts of polyethylene oxide, 8 parts of dimethyldiallylammonium chloride, and 10 parts of inorganic salt containing aluminum and iron in sequence into a four-necked flask equipped with a stirring device, a gas guide device, a feeding device and a thermometer, then add 100 parts of water and stir at a speed of 300-400r / min for 20 minutes, mix thoroughly, and obtain solution A.

[0041] Step 3: Add 0.6 parts of dodecyltrimethylammonium chloride to solution A, stir at a speed of 300-400 r / min for 30 min, and introduce nitrogen to deoxygenate, to obtain solution B.

[0042] Step 4: Slowly add potassium persulfate to solution B to initiate polymerization reaction. After reacting for 2 hours at a rotation speed of 300-400 r / min, raise the solution temperature to 60°C and react for 4 hours. Filter the precipitate and dry it to obtain a composite flocculant.

[0043] Example 2-Example 10

[0044] The steps of Example 2 to Example 10 are the same as those of Example 1, and the specific process parameters are shown in Table 1.

[0045] Comparative Example 1

[0046] An inorganic flocculant, which is the aluminum-iron-containing inorganic salt obtained in step 1 of Example 1.

[0047] Comparative Example 2

[0048] An organic flocculant, the preparation method of which is as follows:

[0049] 1. Add 6 parts of polyethylene oxide and 8 parts of dimethyldiallylammonium chloride into a four-necked flask equipped with a stirrer, a gas guide device, a feeding device and a thermometer, then add 100 parts of water and stir at a speed of 300-400r / min for 20 minutes to mix thoroughly;

[0050] 2. Add 0.6 parts of dodecyltrimethylammonium chloride to the reaction solution, stir at a speed of 300-400r / min for 30min, and introduce nitrogen to deoxygenate at the same time;

[0051] Step 4: Slowly add potassium persulfate to the reaction solution to initiate polymerization reaction. At a rotation speed of 300-400 r / min, after reacting for 2 hours, raise the solution temperature to 60°C, react for 4 hours after heating, filter the precipitate, and dry to obtain an organic flocculant.

[0052] Application Examples

[0053] The composite flocculants prepared in Examples 1-10 of the present invention and the flocculants prepared in Comparative Examples 1 and 2 were applied to the treatment of mine wastewater. 8 g of flocculant was added per ton of water and the flocculation was allowed to stand for 3 minutes. The test conditions and treatment results are shown in Table 1. As can be seen from Table 1, in Examples 1-10, the turbidity of suspended matter in the water was less than 60 mg / L after 3 minutes of treating high turbidity wastewater (suspended matter in the water>1000 mg / L); and the turbidity of suspended matter in the water was less than 50 mg / L after 3 minutes of treating low turbidity wastewater (suspended matter in the water>500 mg / L). In Examples 6-10, after treating high turbidity and low turbidity wastewater, the turbidity of suspended matter in the wastewater was less than 50 mg / L, which met the suspended matter discharge standard (≤50 mg / L) in the Iron and Steel Industry Water Pollutant Discharge Standard (GB 13456-2012), and the treatment effect was good. However, the use of inorganic flocculants and organic flocculants alone is not as good as the composite flocculant in treating wastewater.

[0054] Table 1 Experimental conditions and treatment results of sewage with different turbidity in Examples 1-10

[0055]

[0056]

Claims

1. A composite flocculant, characterized in that: It is a mixture obtained by polymerizing an inorganic salt containing aluminum and iron obtained by treating iron tailings with acid, polyethylene oxide and dimethyldiallylammonium chloride.

2. The method for preparing the composite flocculant according to claim 1, characterized in that: The following steps are involved: Step 1: Mix the iron tailings with a TFe content of ≥9% and an Al2O3 content of ≥3% with an acid solution, react at a temperature of 75-85°C for 1-2h, filter, concentrate and dry the filtrate to obtain an inorganic salt containing aluminum and iron; Step 2: Add polyethylene oxide, dimethyldiallylammonium chloride and an inorganic salt containing aluminum and iron into a container, then add water and stir at a speed of 300-400 r / min for 15-20 minutes to obtain a solution A; Step 3: Add a surfactant to solution A, stir at a speed of 300-400 r / min for 20-30 min, and simultaneously introduce nitrogen into the reaction solution for deoxygenation to obtain solution B; Step 4: Add initiator to solution B to initiate polymerization reaction. After reacting for 1.5 to 2 hours at a rotation speed of 300-400 r / min, raise the solution temperature to 60-80°C, react for 4-6 hours, filter the precipitate, and dry to obtain a composite flocculant.

3. The method for preparing the composite flocculant according to claim 2, characterized in that: In step 1, the acid solution is hydrochloric acid or sulfuric acid or a mixed solution of the two with a mass concentration of 8-15%.

4. The method for preparing the composite flocculant according to claim 2, characterized in that: In step 1, the mass ratio of iron tailings to acid solution is 1:3-5.

5. The method for preparing the composite flocculant according to claim 2, characterized in that: In step 2, the added mass ratio of polyethylene oxide, dimethyldiallyl ammonium chloride, inorganic salt containing aluminum and iron, and water is: 6-10 parts of polyethylene oxide, 8-12 parts of dimethyldiallyl ammonium chloride, 10-12 parts of inorganic salt containing aluminum and iron, and 100 parts of water.

6. The method for preparing a composite flocculant according to claim 2, characterized in that: In step 3, the surfactant is dodecyltrimethylammonium chloride, or hexadecyltrimethylammonium chloride, or a mixture of the two.

7. The method for preparing a composite flocculant according to claim 2, characterized in that: In step 3, the amount of surfactant added is 0.6-0.8 parts.

8. The method for preparing a composite flocculant according to claim 2, characterized in that: In step 4, the initiator is one or more of potassium persulfate, ammonium persulfate and ferrous ammonium sulfate.

9. The method for preparing a composite flocculant according to claim 2, characterized in that: In step 4, the amount of initiator added is 0.1-0.2 parts.

10. The method for using the composite flocculant according to claim 1, characterized in that: Add composite flocculant into water with suspended matter ≥500mg / L and let it stand for 3-5 minutes, wherein 6-10g composite flocculant is added per ton of water.

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