Preparation method and application of mine water flocculating agent with adsorption function

Abstract

The present application relates to a kind of mine water flocculation reagent with adsorption function and its application.The mine water flocculation reagent of the present application is made of raw materials including mineral material, chitosan, water, silicate, acid, aluminum chloride salt, ferric chloride salt and polyacrylamide.The preparation method is as follows: heat treatment of mineral material, then add water and chitosan, followed by adding silicate, reaction to form polysilicate grafted on chitosan macromolecule, then add aluminum chloride salt and ferric chloride salt, finally add polyacrylamide and age to obtain.The mine water flocculation reagent provided by the present application can simultaneously remove suspended solids, fluoride and COD, and has the advantages of low dosage, short reaction time and fast settling speed.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying a flocculant for mine water with adsorption function, belonging to the field of mine water treatment technology. Background Technology

[0002] Mine water, as a byproduct of coal mining, is a good choice for reserve water sources. Conventional mine water treatment mainly targets the separation of suspended solids and colloids in the mine water. Generally, after adding PAC or PAM for coagulation and sedimentation, it can meet the discharge standards. However, the dosage of these agents is large, and the sedimentation rate of the formed flocs is slow. With the increasing requirements for water resource reuse and recycling, pollutants such as fluoride and COD in mine water have become necessary to be treated. However, conventional coagulation and sedimentation treatment with polyaluminum chloride (PAC) and polyacrylamide (PAM) cannot remove fluoride and dissolved COD. To remove fluoride and dissolved COD, additional treatment measures are required. This leads to a sharp increase in the initial investment and system footprint of mine water treatment. Moreover, compared with traditional flocculation and sedimentation, it requires larger dosage of agents, longer reaction cycles, poorer treatment effects, and larger reaction equipment, which will also affect subsequent treatment systems. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address the aforementioned problems in the prior art, this invention provides a method for preparing a mine water flocculant with adsorption function. This flocculant simultaneously removes suspended solids, fluorides, and COD, and has low dosage, short reaction time, and fast sedimentation rate, effectively solving the problems existing in the background art.

[0005] (II) Technical Solution

[0006] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0007] A mine water flocculant with adsorption function is made from raw materials including mineral materials, chitosan, water, silicates, acids, aluminum chloride salts, ferric chloride salts and polyacrylamide.

[0008] The mine water flocculant described above, by mass, comprises 1-3 parts mineral materials, 3-4 parts chitosan, 5-10 parts water, 8-18 parts silicate, 5-10 parts aluminum chloride, 5-10 parts ferric chloride, and 0.03-0.4% polyacrylamide by mass of the aforementioned raw materials.

[0009] In the above-mentioned mine water flocculant, preferably, the mineral material is zeolite, porous clay or hydroxyapatite with a particle size of 80-120 micrometers; the silicate is sodium silicate or potassium silicate, and is prepared as an aqueous solution with a mass concentration of 20-40% before use.

[0010] In the above-mentioned mine water flocculant, preferably, the aluminum chloride salt is polyaluminum chloride and the ferric chloride salt is polyferric chloride.

[0011] The preparation method of the mine water flocculant as described above includes the following steps:

[0012] S1. Heat treatment of mineral materials;

[0013] S2. Add water and chitosan, mix and then sonicate to ensure uniform dispersion of the mineral material and chitosan;

[0014] S3. Add silicate solution to the ultrasonic mixture, stir, adjust the pH to acidic, add aluminum chloride and ferric chloride, and continue stirring to react.

[0015] S4. Add polyacrylamide to the mixture after stirring in S3, stir, and then age in a constant temperature chamber.

[0016] S5. After aging, remove, filter, air dry, and grind to obtain mine water flocculant.

[0017] In the preparation method described above, preferably, in step S1, the heat treatment is to keep the temperature at 300°C for 20 to 45 minutes.

[0018] In the preparation method described above, preferably, in step S2, the stirring time during mixing is 10-20 min; and the ultrasonic treatment conditions are 28-40 kHz for 20-60 min.

[0019] In the preparation method described above, preferably, in step S3, the acid is acetic acid or hydrochloric acid, and the pH value is adjusted to 2.0 to 4.0.

[0020] In the preparation method described above, preferably, in step S3, the stirring reaction time is 15-45 min and the stirring rate is 50-250 rpm.

[0021] In the preparation method described above, preferably, in step S4, the stirring time is 5 to 15 minutes; and the aging conditions are aging in a constant temperature chamber at 20°C for 20 to 28 hours.

[0022] The application of the mine water flocculant or the mine water flocculant prepared by the above-described method in the removal of fluoride and dissolved COD from mine water. When the mine water flocculant is used to remove fluoride and dissolved COD from mine water, the dosage is related to the concentration of fluoride and dissolved COD in the raw water, and the specific dosage can be determined through small-scale tests.

[0023] (III) Beneficial Effects

[0024] The beneficial effects of this invention are:

[0025] The present invention provides a method for preparing a flocculant for mine water with adsorption function. First, the mineral material is heat-treated to open its internal pores. Then, water and chitosan are added, allowing the chitosan to penetrate into the pores of the mineral material, transforming larger pores into denser micropores with ion adsorption capacity, thus enhancing its adsorption and removal capacity for fluoride and COD in mine water. Subsequently, silicates are added, reacting to generate polysilicic acid, which is grafted onto the chitosan macromolecules to form a macromolecular network structure, enhancing the flocculant's entrapment effect. Next, aluminum chloride and ferric chloride salts are added, loading the mineral material with these salts and combining them with the mineral metal elements abundant in the zeolite itself, giving the flocculant a stronger cationic effect, enhancing the electrostatic attraction and van der Waals forces of the flocculant to suspended solids, and improving the adsorption effect. Finally, a flocculant with adsorption capacity, centered on the mineral material, is prepared through further compounding with polyacrylamide.

[0026] The mine water flocculant provided by this invention can simultaneously remove suspended solids, fluorides and COD, and has the advantages of low dosage, short reaction time and fast sedimentation speed. Attached Figure Description

[0027] Figure 1 A flowchart illustrating the preparation process of the mine water flocculant provided by this invention;

[0028] Figure 2 The diagram shows the structural changes during the preparation process of the mine water flocculant provided by this invention. Detailed Implementation

[0029] The principle of this invention is that the mineral material is first heat-treated to fully release its internal pores; then, chitosan is used as a cross-linking agent to penetrate into the zeolite pores, making the larger pores into denser micropores with ion adsorption capacity, thus giving it a strong adsorption and removal effect on fluoride and COD in mine water; silicates react to generate polysilicic acid, which is grafted onto the chitosan macromolecules to form a network structure of macromolecules, enhancing the flocculant's entrapment effect; then, aluminum chloride salts and ferric chloride salts are loaded, combined with the mineral metal elements rich in the zeolite itself, giving the flocculant a stronger cationic effect, enhancing the flocculant's attraction to suspended solids and electrostatic attraction and van der Waals forces; finally, a flocculant with adsorption capacity based on mineral materials is prepared through further compounding with polyacrylamide.

[0030] Specifically, after heat treatment, mineral materials such as zeolite, porous clay, or hydroxyapatite can remove small amounts of volatile substances mixed in the material, and simultaneously remove substances adsorbed in the pores of the material, fully opening the pores. This is beneficial for the adsorption and removal of COD and fluoride ions in mine water during mine water treatment. The mineral materials serve as the crystal nuclei of the flocculant of this invention, as the basis for subsequent grafting reactions, and can also adjust the specific gravity of the final flocculant, which is beneficial for rapid sedimentation in the mine water treatment process. Chitosan is an alkaline polysaccharide with many functional groups and free amino groups in its molecular chain. In the preparation process of the flocculant described in this invention, ultrasonic treatment is used to make chitosan adhere more evenly to the mineral materials. On the surface and within the pores of the material, a positively charged preparation process product is formed, with mineral materials as the core and chitosan as the primary shell. During the silicate reaction, polysilicic acid is generated, which connects the dispersed preparation process product with mineral materials as the core and chitosan as the primary shell, increasing the degree of molecular polymerization and forming a long-chain flocculant with multiple mineral material particles connected by polysilicic acid. In the subsequent ferric chloride and aluminum chloride reactions, iron and aluminum ions combine with the long-chain flocs through coordination bonds, enhancing the positive charge of the flocculant. Finally, polyacrylamide bridges and traps the long-chain flocs through hydrogen bonding and electrostatic attraction, forming larger flocs, ultimately preparing the organic-inorganic composite mine water flocculant with adsorption function described in this invention.

[0031] Furthermore, the preparation method of the mine water flocculant with adsorption function of the present invention, such as... Figure 1 As shown, the process includes the following steps: S1, heating the mineral material;

[0032] S2. Add water and chitosan to react, mix and then sonicate to make the mineral material and chitosan evenly dispersed.

[0033] S3. Add silicate solution to the ultrasonic mixture, stir, adjust the pH to acidic, add aluminum chloride and ferric chloride, and continue stirring to react.

[0034] S4. Add polyacrylamide to the mixture after stirring and reaction in S3 to lengthen the chain. After stirring, age in a constant temperature chamber for bridging net capture.

[0035] S5. After aging, remove, filter, air dry, and grind to obtain the mine water flocculant. The structural changes of the substances during the preparation process can be found in... Figure 2 As shown.

[0036] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below through specific embodiments.

[0037] Example 1

[0038] 100g of zeolite was placed in a muffle furnace, and the temperature was increased by 50℃ every 10 minutes until it reached 300℃, which was then held at 300℃ for 30 minutes. After the heat-treated zeolite cooled naturally, 500mL of purified water and 350g of chitosan were added sequentially, and the mixture was stirred thoroughly for 15 minutes. The mixture was then sonicated at 35kHz for 40 minutes. 3000mL of a 30% silicate solution (containing 900g of sodium silicate) was added, and the pH was adjusted to 3.0 using acetic acid solution. 500g each of polyferric chloride and polyaluminum chloride were added, and the mixture was stirred thoroughly for 30 minutes. Finally, 3g of polyacrylamide was added, and the mixture was stirred for 10 minutes and then aged in a 20℃ constant temperature oven for 24 hours. After aging, the resulting flocculant for mine water with adsorption function was filtered, air-dried, and ground.

[0039] Example 2

[0040] 100g of zeolite was placed in a muffle furnace, and the temperature was increased from 100℃ to 300℃ every 10 minutes, and maintained at 300℃ for 30 minutes. After the heat-treated zeolite cooled naturally, 800mL of purified water and 300g of chitosan were added sequentially, and the mixture was stirred thoroughly for 15 minutes. The mixture was then sonicated at 30kHz for 30 minutes. 4000mL of 30% sodium silicate solution was added, and the pH was adjusted to 3.0 with acetic acid solution. 1000g each of polyferric chloride and polyaluminum chloride were added, and the mixture was stirred thoroughly for 30 minutes. Finally, 10g of polyacrylamide was added, and the mixture was stirred for 10 minutes and then aged in a 20℃ constant temperature oven for 24 hours. After aging, the mixture was removed, filtered, air-dried, and ground to obtain a mine water flocculant with adsorption function.

[0041] Example 3

[0042] 50g of zeolite was placed in a muffle furnace, and the temperature was increased from 100℃ to 300℃ every 10 minutes, continuing for 30 minutes. After the heat-treated zeolite cooled naturally, 300mL of purified water and 300g of chitosan were added sequentially, and the mixture was stirred thoroughly for 15 minutes. The mixture was then sonicated at 40kHz for 30 minutes. 2000mL of a 30% potassium silicate solution was added, followed by adjusting the pH to 3.0 with acetic acid solution. Then, 400g each of polyferric chloride and polyaluminum chloride were added, and the mixture was stirred thoroughly for 30 minutes. Finally, 2g of polyacrylamide was added, and the mixture was stirred for 10 minutes before being aged in a 20℃ incubator for 24 hours. After aging, the mixture was removed, filtered, air-dried, and ground to obtain a mine water flocculant with adsorption function.

[0043] Example 4

[0044] The mine water in a coal mine in Ordos contained 1200 mg / L of suspended solids, 35 mg / L of dissolved COD, and 2.0 mg / L of fluoride. Natural zeolite, polyaluminum chloride (PAC), polyferric sulfate (PFS), the flocculant prepared according to this invention, and polyacrylamide (PAM) were added respectively. The quality of the supernatant after the reaction was tested, and the treatment effects of the flocculant of this invention and PAC were compared. The addition details are as follows:

[0045] Condition 1: Add PAC 150mg / L, do not add PAM

[0046] Condition 2: Add PAC 150 mg / L, add PAM 1.5 mg / L

[0047] Condition 3: Add PFS 150 mg / L, add PAM 1.5 mg / L

[0048] Condition 4: Add 100 mg / L of the flocculant from Examples 1-3 of this invention and 1.0 mg / L of PAM respectively.

[0049] Condition 5: Add 20 mg / L of natural zeolite, 130 mg / L of PAC, and 1.5 mg / L of PAM.

[0050] The above-mentioned mine water was treated with the corresponding reagents under the above conditions, and the mixture was stirred and allowed to settle for 30 minutes. The supernatant was then collected, and the suspended solids (GB / T 11901-1989) and COD (potassium dichromate method) in the supernatant were tested using the national standard method. The fluoride concentration was determined using a fluoride detector. The treatment effects under the different conditions were judged by comparing the water quality indicators of Class III water in the "Surface Water Environmental Quality Standard" (GB3838-2022). The comparison of the treated water quality indicators is shown in Table 1 below.

[0051] Table 1

[0052]

[0053]

[0054] The results show that after treatment with the flocculants prepared in Examples 1-3 of this invention, the suspended solids, COD, and fluoride levels in the mine water meet the Class III water quality requirements of the "Surface Water Environmental Quality Standard" (GB3838-2022). Under other conditions, the relevant indicators did not meet the Class III water quality requirements of the "Surface Water Environmental Quality Standard" (GB3838-2022), indicating that the flocculants prepared in this invention have a good and significant removal effect on suspended solids, COD, and fluoride in mine water. This is because when the flocculant with adsorption capacity provided by this invention is added to the mine water, its cationic properties attract fluoride in the mine water through hydrogen bonds or electrostatic attraction, and then it is adsorbed by the micropores of the mineral material. The micropores also adsorb dissolved COD in the mine water. The network structure of the flocculant traps suspended solids and colloids in the mine water to form flocs with mineral materials as the core. Due to the high specific gravity of the mineral materials, the flocs will settle quickly and separate from the water.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art can make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A mine water flocculant with adsorption function, characterized in that, It is made from raw mineral materials, chitosan, water, silicates, acids, aluminum chloride salts, ferric chloride salts, and polyacrylamide; By weight, each raw material consists of 1-3 parts mineral materials, 3-4 parts chitosan, 5-10 parts water, 8-18 parts silicate, 5-10 parts aluminum chloride, 5-10 parts ferric chloride, and 0.03-0.4% polyacrylamide by weight of the sum of the aforementioned raw materials. The mineral material is zeolite, porous clay or hydroxyapatite, with a particle size of 80 to 120 micrometers. The mine water flocculant is obtained by the following preparation method: S1. Heat treatment of the mineral material; wherein, the heat treatment is to hold at 300°C for 20 to 45 minutes; S2. Add water and chitosan, mix and then sonicate to ensure uniform dispersion of the mineral material and chitosan; S3. Add silicate solution to the ultrasonic mixture, stir, adjust the pH to acidic, add aluminum chloride and ferric chloride, and continue stirring to react. S4. Add polyacrylamide to the mixture after stirring in S3, stir, and then age in a constant temperature chamber. S5. After aging, remove, filter, air dry, and grind to obtain mine water flocculant.

2. The mine water flocculant as described in claim 1, characterized in that, The silicate is sodium silicate or potassium silicate, and it should be prepared as an aqueous solution with a mass concentration of 20-40% before use.

3. The mine water flocculant as described in claim 1, characterized in that, The aluminum chloride salt is polyaluminum chloride, and the ferric chloride salt is polyferric chloride.

4. The mine water flocculant as described in claim 1, characterized in that, In step S2, the stirring time during mixing is 10-20 min; the ultrasonic treatment conditions are 28-40 kHz for 20-60 min.

5. The mine water flocculant as described in claim 1, characterized in that, In step S3, the acid is acetic acid or hydrochloric acid, and the pH value is adjusted to 2.0 to 4.0; the stirring reaction time is 15 to 45 minutes, and the stirring rate is 50 to 250 rpm.

6. The mine water flocculant as described in claim 1, characterized in that, In step S4, the stirring time is 5 to 15 minutes; the aging conditions are aging in a constant temperature chamber at 20°C for 20 to 28 hours.

7. The application of the mine water flocculant as described in any one of claims 1-6 in the removal of fluoride and dissolved COD from mine water.

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