Coal slime water treatment agent, preparation method and application thereof

Abstract

The present application belongs to the technical field of wastewater treatment, and discloses a coal slime water treatment agent, a preparation method and application thereof. The coal slime water treatment agent comprises a coagulant aid G and a flocculant F prepared respectively. The coagulant aid G comprises the following components in mass percentage: 3-5% of sodium hypochlorite, 2-4% of water glass, 3-5% of active silicic acid, 1-2% of sodium carboxymethyl starch, and the balance of water, and the total amount of the coagulant aid G is 100%. The flocculant F comprises the following components in mass percentage: 2-5% of sodium alginate, 2-6% of polyethyleneimine, 2-5% of chitosan, 1-4% of hydroxyethyl cellulose, 2-5% of dimethyl diallyl ammonium chloride, 3-6% of tannic acid, and the balance of water, and the total amount of the flocculant F is 100%. When the coal slime water treatment agent is applied, the coagulant aid G is first added to perform micro-treatment and pre-flocculation on the coal slime water, and then the flocculant F is added to perform intensified flocculation, so that the components complement each other, synergistically promote flocculation and sedimentation of suspended matters, and efficient separation of the suspended matters and water is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wastewater treatment, and particularly relates to a coal slurry water treatment agent and a preparation method and application thereof. BACKGROUND

[0002] Coal slurry water mainly refers to sewage mixed with a large amount of coal powder and soil. The main feature of coal slurry water is high concentration of suspended solids, which can reach more than 40000 mg / L. The suspended solids have small particle size, light specific gravity, and strong negative charge on the particles, and have the characteristics of a colloidal dispersion system, so it is difficult to settle naturally. The fundamental reason is that the suspended particles have a strong negative charge colloidal system, and it is mainly reflected in the zeta potential of the colloidal particles. The strong electrostatic repulsion is generated, and the higher the zeta potential, the greater the electrostatic repulsion between the colloidal particles, and the more stable the colloidal particles. In addition, due to the charging of the colloidal particles of coal slurry water, polar water molecules are attracted to its surroundings to form a hydration film. The hydration film can prevent the mutual contact between the colloidal particles, and the thickness of the hydration film determines the thickness of the diffusion layer, which in turn affects the zeta potential. Therefore, it is very difficult to purify and treat coal slurry water.

[0003] At present, the most common treatment process for coal slurry water is flocculation and sedimentation, and the most commonly used flocculant is polyacrylamide. However, the flocculation efficiency is low during the treatment process, the usage amount is large, the disposal cost is high, and the universality is poor. The settling effect of coal slurry water with different solid content and pollutants is quite different, and the settling effect is significantly affected. In addition, new flocculants are also being actively developed, but the effect is still not good. For example, Chinese patent CN105126719A discloses a preparation method of a coal slurry water flocculant, which grafts sodium p-styrene sulfonate onto the surface of fly ash to prepare a coal slurry water flocculant. However, the patent makes the polymeric reaction of sodium p-styrene sulfonate on the surface of fly ash, and the fly ash does not change the flocculation efficiency of the polymeric reaction product in the later stage. Even the dispersion effect of the dispersion liquid of fly ash is poor, which reduces the degree of polymerization of the mature polymeric reaction, thereby affecting the coagulation effect of polystyrene sulfonate. Chinese patent CN106830240A discloses a method for treating coal slurry water by using a coal gangue-based flocculant. However, the high dispersibility of the flocculant in the coal slurry water is the basis for high-efficiency flocculation of the flocculant, and the poor dispersibility of the coal gangue-based flocculant cannot guarantee the flocculation effect.

[0004] Therefore, based on the special properties of high mud content, high stability, and high zeta potential of coal slurry water, it is necessary to develop a more optimal coal slurry water treatment agent to solve the problems of low flocculation efficiency, high disposal cost, and poor universality. SUMMARY

[0005] The technical problem solved by the present application is to provide a coal slime water treatment agent, a preparation method and application thereof, which can solve the problems of the prior art.

[0006] To solve the technical problem proposed in the present application, the present application provides a coal slime water treatment agent, which comprises a coagulant aid G and a flocculant F prepared separately; the coagulant aid G comprises the following components in mass percentage: 3-5% of sodium hypochlorite, 2-4% of water glass, 3-5% of active silicic acid, 1-2% of sodium carboxymethyl starch, and the balance of water, and the total amount of the coagulant aid G is 100%; the flocculant F comprises the following components in mass percentage: 2-5% of sodium alginate, 2-6% of polyethyleneimine, 2-5% of chitosan, 1-4% of hydroxyethyl cellulose, 2-5% of dimethyl diallyl ammonium chloride, and 3-6% of tannic acid, and the balance of water, and the total amount of the flocculant F is 100%.

[0007] In the above scheme, the water glass has a Na2O content of 10-13%, a SiO2 content of 25-29%, and a modulus of 2.4-2.6.

[0008] In the above scheme, the preparation method of the active silicic acid is as follows: the pH value of a sodium silicate solution is adjusted to be acidic by sulfuric acid, and then an aluminum chloride solution is added and left to stand to obtain the active silicic acid.

[0009] Further, the pH value is 2-3.

[0010] Further, the mass concentration of the sodium silicate solution is 2-5%.

[0011] Further, the mass concentration of the aluminum chloride solution is 5-10%.

[0012] Further, the molar ratio of sodium silicate in the sodium silicate solution to aluminum chloride in the aluminum chloride solution is (2-5):1.

[0013] Further, the standing time is 1-2 h.

[0014] In the above scheme, the sodium content of the carboxymethyl starch is 4-5.5%, and the sodium degree of substitution D.S is 0.35-0.50.

[0015] In the above scheme, the polyethyleneimine is linear polyethyleneimine with a molecular weight of 5000-10000.

[0016] The present application further provides a preparation method of the coal slime water treatment agent, comprising the following steps:

[0017] 1) according to the component allocation ratio of the coagulant G, sodium hypochlorite, water glass, active silicon acid and sodium carboxymethyl starch are mixed and dissolved in water to prepare the coagulant G;

[0018] 2) according to the component allocation ratio of the flocculant F, sodium alginate, polyethyleneimine, hydroxyethyl cellulose, dimethyl diallyl ammonium chloride and tannic acid are mixed and dissolved in water, and then chitosan is added and uniformly mixed to prepare the flocculant F.

[0019] The application further provides an application method of the coal slime water treatment agent.

[0020] 1) the coagulant G is first added into the coal slime water to be treated, and then stirred and placed;

[0021] 2) the flocculant F is further added into the coal slime water, and then stirred and placed, and the supernatant is the treated coal slime water.

[0022] In the above scheme, the adding amount of the coagulant G is 30-50 g per ton of water.

[0023] In the above scheme, the adding amount of the flocculant F is 150-500 g per ton of water.

[0024] In the above scheme, the mass ratio of the coagulant G to the flocculant F is 1:(5-10).

[0025] In the above scheme, the stirring rate after adding the coagulant G is 200-300 r / min, the stirring time is 2-5 min, and the standing time is 15-25 min.

[0026] In the above scheme, the stirring rate after adding the flocculant F is 200-300 r / min, the stirring time is 2-5 min, and the standing time is 30-60 min.

[0027] In the above scheme, the pH value of the coal slime water to be treated is 5-8, and the total suspended substance content is 10000-25000 mg / L.

[0028] In the above scheme, the total suspended substance content of the treated coal slime water is ≤1000 mg / L, and the removal rate of the coal slime water treatment agent to the total suspended substance in the coal slime water is ≥95%.

[0029] The technical principle of the application is as follows:

[0030] The present application respectively prepares coagulant aid G and flocculant F and sequentially adds them into coal slurry water. First, the coagulant aid G micro-treats and pre-flocculates the suspended matter in the coal slurry water. For example, sodium hypochlorite can inhibit the foam formed by trace organic matter in the oxidized coal slurry water, reducing the interference of the foam on the later flocculation process. The water glass component can form a micro-support, so that the flocculation body which is continuously getting larger in the later flocculation process has a sufficient flocculation bed body. The active silicic acid can reduce the Zeta potential of the coal slurry water system, thereby strengthening the flocculation body's coagulation bridging and netting in the later flocculation process. The sodium carboxymethyl starch has good thickening and suspending effects, and can promote the low specific gravity particles in the coal slurry water to flocculate and precipitate in the later process. After the coagulant aid G micro-treats and pre-flocculates the coal slurry water, the flocculant F contains a large amount of electrolyte of high-valence positive ion. The electrolyte enters the surface of the colloidal particles in the coal slurry water through electrostatic attraction, replacing the original low-valence positive ion. The reduction of the number of positive ions makes the thickness of the double electric layer thin, thereby reducing the ξ potential on the sliding surface of the colloidal particles, making the colloidal particles aggregate. Some substances in the coagulant aid G, such as water glass, can make the adsorption flocculation of the flocculant F and the colloidal particles on the surface of the coal slurry water more gentle and more sustainable, so that the flocculation effect of the flocculant F is slowly released. In the flocculation process, the flocculant F neutralizes part of the charges of the colloidal particles in the coal slurry water, reduces the electrostatic attraction between the colloidal particles in the coal slurry water, and makes the colloidal particles in the coal slurry water more easily aggregate and settle.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] 1) The coal slurry water treatment agent of the present application includes coagulant aid G and flocculant F, which are used separately. In application, the coagulant aid G is added first to micro-treat and pre-flocculate the coal slurry water, and then the flocculant F is added to strengthen the flocculation. The components complement each other and synergistically promote the flocculation and sedimentation of the suspended matter, realize the efficient separation of the suspended matter and water, and ensure the stable operation and normal treatment of the coal slurry water treatment system of the plant.

[0033] 2) The coagulant aid G and the flocculant F of the coal slurry water treatment agent of the present application have a good synergistic effect. The coagulant aid G can promote the flocculation of the flocculant F and make the flocculation of the flocculant F slowly released. In this way, the flocculation effect exists in the coal slurry water for a certain period of time, and the coal slurry water can be continuously flocculated and precipitated without adding the flocculant multiple times, thereby reducing the dosage of the reagent. Since the dissolution and dispersion of the coagulant aid G in water and the micro-treatment process require a certain time, adding the two separately is more conducive to the electric neutralization and charge adsorption bridging of the flocculant F in the flocculation system. DETAILED DESCRIPTION

[0034] In order to better understand the present application, the following examples are further illustrated the content of the present application, but the content of the present application is not limited to the following examples.

[0035] In the following examples, the Na2O content of the water glass is 11.61%, the SiO2 content is 28.53%, and the modulus is 2.54; the carboxymethyl starch is a solid powder, the sodium content is 4.86%, and the sodium degree of substitution D.S is 0.39; the polyethyleneimine is a linear polyethyleneimine, a viscous liquid, the molecular weight is 10000, and the purity is 99%; the preparation method of the active silicic acid is as follows: taking 20 mL of a sodium silicate solution with a mass concentration of 3.2%, adjusting the pH value of the sodium silicate solution to 3 with sulfuric acid, then adding 2 mL of an aluminum chloride solution with a mass concentration of 10%, uniformly mixing, and then standing for 1 h to obtain the active silicic acid.

[0036] In the following examples, the selected sodium hypochlorite is a white solid powder, chemically pure, and the concentration is more than 98%; the selected sodium alginate is a white solid powder, analytically pure, and the content is more than 99.9%; the selected chitosan is a solid powder, chemically pure, and the content is more than 99%; the selected hydroxyethyl cellulose, dimethyldiallylammonium chloride, and tannic acid are all solid powders, chemically pure.

[0037] In the following examples, the determination of the total suspended solids content in the slime water is performed according to MT / T 805-1999 "Determination of Suspended Solids in Coal Mine Water".

[0038] Example 1

[0039] The slime water treatment agent of Example 1 comprises a coagulant aid G and a flocculant F prepared respectively;

[0040] The coagulant aid G comprises the following components in mass percentage: sodium hypochlorite 3%, water glass 2%, active silicic acid 5%, sodium carboxymethyl starch 1%, and water 89%; according to the component allocation, the sodium hypochlorite, the water glass, the active silicic acid, and the sodium carboxymethyl starch are mixed and dissolved in water to prepare the coagulant aid G;

[0041] The flocculant F comprises the following components in mass percentage: sodium alginate 2%, polyethyleneimine 4%, chitosan 2%, hydroxyethyl cellulose 2%, dimethyldiallylammonium chloride 5%, tannic acid 3%, and water 82%; according to the component allocation, the sodium alginate, the polyethyleneimine, the hydroxyethyl cellulose, the dimethyldiallylammonium chloride, and the tannic acid are mixed and dissolved in water, and then the chitosan is added and uniformly mixed to prepare the flocculant F.

[0042] The slime water treatment agent of Example 1 is applied to treat a slime water with a pH of 8.5 and a total suspended solids content of 13800 mg / L, and the specific steps are as follows:

[0043] 1) to the coal slurry water to be treated, first add coagulant G, the dosage is 50g per ton of water, after adding, stir at a rate of 200r / min for 5min, then stand for 20min;

[0044] 2) then add flocculant F to the coal slurry water, the dosage is 300g per ton of water, after adding, stir at a rate of 250r / min for 5min, then stand for 40min, the supernatant is the treated coal slurry water.

[0045] After detection, the total suspended solids content of the treated coal slurry water is 652mg / L, and the removal rate of the coal slurry water treatment agent on the total suspended solids is 95.3%.

[0046] Example 2

[0047] The coal slurry water treatment agent of Example 2 comprises coagulant G and flocculant F prepared respectively;

[0048] The coagulant G comprises the following components in mass percentage: sodium hypochlorite 5%, water glass 3%, active silicic acid 5%, sodium carboxymethyl starch 2%, water 85%; according to the component proportion, mix sodium hypochlorite, water glass, active silicic acid and sodium carboxymethyl starch, then dissolve them in water to prepare coagulant G;

[0049] The flocculant F comprises the following components in mass percentage: sodium alginate 4%, polyethyleneimine 5%, chitosan 3%, hydroxyethyl cellulose 3%, dimethyl diallyl ammonium chloride 4%, tannic acid 5%, water 76%; according to the component proportion, mix sodium alginate, polyethyleneimine, hydroxyethyl cellulose, dimethyl diallyl ammonium chloride and tannic acid, then dissolve them in water, and then add chitosan and mix uniformly to prepare flocculant F.

[0050] The coal slurry water treatment agent of Example 2 is applied to treat a coal slurry water with pH of 7.5 and total suspended solids content of 24200mg / L, and the specific steps are as follows:

[0051] 1) to the coal slurry water to be treated, first add coagulant G, the dosage is 50g per ton of water, after adding, stir at a rate of 250r / min for 3min, then stand for 15min;

[0052] 2) then add flocculant F to the coal slurry water, the dosage is 250g per ton of water, after adding, stir at a rate of 300r / min for 2min, then stand for 30min, the supernatant is the treated coal slurry water.

[0053] After detection, the total suspended solids content of the treated coal slurry water is 816mg / L, and the removal rate of the coal slurry water treatment agent on the total suspended solids is 96.6%.

[0054] Example 3

[0055] The coal slurry treatment agent of Example 3 comprises coagulant aid G and flocculant F prepared separately;

[0056] The coagulant aid G comprises the following components in mass percentage: sodium hypochlorite 3%, water glass 3%, active silicic acid 4%, sodium carboxymethyl starch 2%, and water 88%; the coagulant aid G is prepared by mixing sodium hypochlorite, water glass, active silicic acid, and sodium carboxymethyl starch in the above proportions and dissolving them in water;

[0057] The flocculant F comprises the following components in mass percentage: sodium alginate 2%, polyethyleneimine 5%, chitosan 5%, hydroxyethyl cellulose 1%, dimethyl diallyl ammonium chloride 5%, tannic acid 3%, and water 79%; the flocculant F is prepared by mixing sodium alginate, polyethyleneimine, hydroxyethyl cellulose, dimethyl diallyl ammonium chloride, and tannic acid in the above proportions and dissolving them in water, and then adding chitosan and mixing uniformly.

[0058] The coal slurry treatment agent of Example 3 is applied to treat a coal slurry with pH of 7.5 and total suspended solids content of 15600 mg / L, and the specific steps are as follows:

[0059] 1) The coagulant aid G is first added to the coal slurry to be treated at a dosage of 40 g per ton of water, and after the addition, the mixture is stirred at a speed of 250 r / min for 5 min and then left to stand for 25 min;

[0060] 2) The flocculant F is then added to the coal slurry at a dosage of 220 g per ton of water, and after the addition, the mixture is stirred at a speed of 200 r / min for 5 min and then left to stand for 40 min, and the supernatant is the treated coal slurry.

[0061] After detection, the total suspended solids content of the treated coal slurry is 643 mg / L, and the removal rate of the coal slurry treatment agent on the total suspended solids is 95.9%.

[0062] Example 4

[0063] The coal slurry treatment agent of Example 4 comprises coagulant aid G and flocculant F prepared separately;

[0064] The coagulant aid G comprises the following components in mass percentage: sodium hypochlorite 3%, water glass 3%, active silicic acid 5%, sodium carboxymethyl starch 1%, and water 88%; the coagulant aid G is prepared by mixing sodium hypochlorite, water glass, active silicic acid, and sodium carboxymethyl starch in the above proportions and dissolving them in water;

[0065] The flocculant F comprises the following components in mass percentage: sodium alginate 3%, polyethyleneimine 6%, chitosan 4%, hydroxyethyl cellulose 3%, dimethyl diallyl ammonium chloride 4%, tannic acid 4%, and water 76%; the sodium alginate, polyethyleneimine, hydroxyethyl cellulose, dimethyl diallyl ammonium chloride and tannic acid are mixed according to the component ratio, and then dissolved in water, and then chitosan is added and uniformly mixed to prepare the flocculant F.

[0066] The coal slurry treatment agent of Example 4 is applied to treat a coal slurry with a pH of 6.5 and a total suspended solids content of 18900 mg / L, and the specific steps are as follows:

[0067] 1) The coagulant aid G is first added to the coal slurry to be treated at a dosage of 50 g per ton of water, and after the addition, the mixture is stirred at a speed of 200 r / min for 2 min, and then is left to stand for 20 min;

[0068] 2) The flocculant F is then added to the coal slurry at a dosage of 350 g per ton of water, and after the addition, the mixture is stirred at a speed of 300 r / min for 3 min, and then is left to stand for 30 min, and the supernatant is the treated coal slurry.

[0069] After detection, the total suspended solids content of the treated coal slurry is 739 mg / L, and the removal rate of the coal slurry treatment agent on the total suspended solids is 96.1%.

[0070] Example 5

[0071] The coal slurry treatment agent of Example 5 comprises the coagulant aid G and the flocculant F prepared respectively;

[0072] The coagulant aid G comprises the following components in mass percentage: sodium hypochlorite 4%, water glass 4%, active silicic acid 5%, carboxymethyl starch sodium 2%, and water 85%; the sodium hypochlorite, water glass, active silicic acid and carboxymethyl starch sodium are mixed according to the component ratio, and then dissolved in water to prepare the coagulant aid G;

[0073] The flocculant F comprises the following components in mass percentage: sodium alginate 5%, polyethyleneimine 6%, chitosan 5%, hydroxyethyl cellulose 4%, dimethyl diallyl ammonium chloride 5%, tannic acid 6%, and water 69%; the sodium alginate, polyethyleneimine, hydroxyethyl cellulose, dimethyl diallyl ammonium chloride and tannic acid are mixed according to the component ratio, and then dissolved in water, and then chitosan is added and uniformly mixed to prepare the flocculant F.

[0074] The coal slurry treatment agent of Example 5 is applied to treat a coal slurry with a pH of 7.5 and a total suspended solids content of 15200 mg / L, and the specific steps are as follows:

[0075] 1) to the coal slurry water to be treated, first add coagulant G, the dosage is 30g per ton of water, after adding, stir at the rate of 250r / min for 5min, then stand for 25min;

[0076] 2) then add flocculant F to the coal slurry water, the dosage is 150g per ton of water, after adding, stir at the rate of 250r / min for 2min, then stand for 40min, the supernatant is the treated coal slurry water.

[0077] After detection, the total suspended solids content of the treated coal slurry water is 229mg / L, the removal rate of the coal slurry water treatment agent to the total suspended solids is 98.5%.

[0078] The above examples are only examples for clearly illustrating, but not limit the embodiments. For those skilled in the art, on the basis of the above description, other different forms of changes or variations can also be made, here do not need and can not be exhausted all the embodiments, and thus the obvious changes or variations still within the scope of the present invention.

Claims

1. A method for applying a coal slime water treatment agent, characterized in that, Includes the following steps: 1) Add coagulant G to the coal slurry water to be treated, stir, and then let it stand; 2) Add flocculant F to the coal slurry water, stir and let stand. The supernatant is the treated coal slurry water. The coal slime water treatment agent comprises separately formulated coagulant aid G and flocculant F; wherein, the coagulant aid G comprises the following components by mass percentage: sodium hypochlorite 3-5%, water glass 2-4%, activated silica 3-5%, sodium carboxymethyl starch 1-2%, with the balance being water, and the total amount of coagulant aid G is 100%; the flocculant F comprises the following components by mass percentage: sodium alginate 2-5%, polyethyleneimine 2-6%, chitosan 2-5%, hydroxyethyl cellulose 1-4%, dimethyl diallyl ammonium chloride 2-5%, tannic acid 3-6%, with the balance being water, and the total amount of flocculant F is 100%; The water glass has a Na2O content of 10-13%, a SiO2 content of 25-29%, and a modulus of 2.4-2.6; the sodium carboxymethyl starch has a sodium content of 4-5.5% and a sodium substitution degree (DS) of 0.35-0.50; the polyethyleneimine is linear polyethyleneimine with a molecular weight of 5000-10000.

2. The application method of the coal slime water treatment agent according to claim 1, characterized in that, The method for preparing the active silicic acid is as follows: adjust the pH value of the sodium silicate solution to 2-3 with sulfuric acid, then add aluminum chloride solution and let it stand to obtain active silicic acid.

3. The application method of the coal slime water treatment agent according to claim 2, characterized in that, The sodium silicate solution has a mass concentration of 2-5%, the aluminum chloride solution has a mass concentration of 5-10%, and the molar ratio of sodium silicate in the sodium silicate solution to aluminum chloride in the aluminum chloride solution is (2-5):

1.

4. The application method of the coal slime water treatment agent according to claim 1, characterized in that, The preparation method of the coal slime water treatment agent includes the following steps: 1) Sodium hypochlorite, water glass, activated silica and sodium carboxymethyl starch were mixed and dissolved in water according to the component ratio of coagulant aid G to obtain coagulant aid G; 2) According to the component ratio of flocculant F, sodium alginate, polyethyleneimine, hydroxyethyl cellulose, dimethyl diallyl ammonium chloride and tannic acid are mixed and dissolved in water, and then chitosan is added and mixed evenly to obtain flocculant F.

5. The application method of the coal slime water treatment agent according to claim 1, characterized in that, The dosage of the coagulant aid G is 30-50 g per ton of water, and the dosage of the flocculant F is 150-500 g per ton of water.

6. The application method of the coal slime water treatment agent according to claim 1, characterized in that, The mass ratio of the coagulant aid G to the flocculant F is 1:(5~10).

7. The application method of the coal slime water treatment agent according to claim 1, characterized in that, The stirring rate is 200~300 r / min; the stirring time in step 1) is 2~5 min, and the settling time is 15~25 min; the stirring time in step 2) is 2~5 min, and the settling time is 30~60 min.

8. The application method of the coal slime water treatment agent according to claim 1, characterized in that, The pH value of the coal slurry water to be treated is 5-8, and the total suspended solids content is 10000-25000 mg / L; the total suspended solids content of the treated coal slurry water is ≤1000 mg / L, and the removal rate of total suspended solids by the coal slurry water treatment agent is ≥95%.