Preparation method of surfactant and collecting agent for coal slime flotation

Abstract

The invention discloses a surfactant and a collecting agent for coal slime flotation and a preparation method of the surfactant and the collecting agent, and belongs to the technical field of separation of solid materials from fluid minerals, and the preparation method comprises the following steps: dissolving fatty acids with different carbon chain lengths and amine-terminated diamine in an organic solvent, and mixing and stirring to prepare a pseudo gemini surfactant; and mixing the pseudo-gemini surfactant with a non-polar hydrocarbon collecting agent, and carrying out ultrasonic treatment to obtain the compound collecting agent. The pseudo gemini surfactant and the collector prepared by the invention can enhance the adsorption and spreading performance of the agent on the surface of coal and the dispersing performance of the agent in ore pulp, and show an excellent synergistic effect on improving the flotation efficiency of low-rank coal slime. The pseudo gemini surfactant provided by the invention has the advantages of good effect, low cost and small pollution, and can promote clean and efficient processing and utilization of coal resources.

Description

Technical Field

[0001] The present invention relates to the technical field of separating solid materials from fluid minerals, in particular to a surfactant and a collector for separating coal slime through froth flotation and a preparation method thereof. Background Art

[0002] Coal is a basic energy source and an important industrial raw material in my country. At present, with the deep mining of coal resources and the improvement of mechanized coal mining, the output of coal slime has been increasing. When separating and obtaining coal slime, conventional flotation collectors are inefficient and have poor benefits. Therefore, finding a flotation collector for efficient coal slime is one of the effective methods to increase the capacity of low-rank coal processing and cleanly produce high-quality low-rank coal.

[0003] Froth flotation uses the difference in surface hydrophobicity of different minerals to separate coal from impurities. Collectors can improve the surface hydrophobicity of coal and gangue minerals, and collectors play a vital role in the flotation process. In conventional flotation, hydrocarbon oils such as kerosene and diesel are generally used as flotation collectors to selectively separate coal slime. However, low-rank coal has a low degree of coalification and contains a large number of oxygen-containing functional groups on its surface, such as carboxyl, hydroxyl and methoxy groups. As a result, during the flotation process, a large number of water molecules are adsorbed on the coal surface through interaction with oxygen-containing groups to form a hydration film, which seriously hinders the adsorption and spreading of oil collector molecules on the coal surface. Such problems have become the main factors affecting the flotation quality improvement of low-rank coal. Summary of the invention

[0004] In view of at least one of the above technical problems, the present invention provides a surfactant and a collector preparation method for coal slime flotation, which is a compound of an eco-friendly pseudo-gemini surfactant and a traditional non-polar hydrocarbon collector for low-rank coal slime flotation, so as to promote the spreading effect of the agent on the surface of low-rank coal, thereby enhancing the hydrophobicity of the coal surface, improving the flotation efficiency and reducing the flotation cost. The specific technical scheme is as follows:

[0005] A method for preparing a surfactant and a collector for coal slime flotation comprises dissolving two fatty acids with different carbon chain lengths and a diamine terminated with an amine group in an organic solvent, wherein the molar ratio of the fatty acid to the diamine terminated with an amine group is 2:1; mixing and stirring to prepare a pseudo-gemini surfactant.

[0006] In some embodiments of the present disclosure, the reaction formula for preparing the pseudo-gemini surfactant is as follows:

[0007]

[0008] Among them, R is Any of the following;

[0009] 6≤n≤16;

[0010] 2≤m≤6.

[0011] In some embodiments of the present disclosure, the organic solvent is any one of acetone, toluene and pyridine.

[0012] In some embodiments of the present disclosure, the stirring temperature is 20-25° C., and the stirring time is 24-30 h.

[0013] A surfactant is prepared by the above method.

[0014] A method for preparing a collector for coal slime flotation comprises placing the above-mentioned surfactant and non-polar hydrocarbon oil in a container, mixing them uniformly through ultrasonic treatment, and obtaining the collector.

[0015] In some embodiments of the present disclosure, the non-polar hydrocarbon oil is any one of dodecane, kerosene or diesel.

[0016] In some embodiments of the present disclosure, the mass percentage of the surfactant is 1% to 10%, and the mass percentage of the non-polar hydrocarbon oil is 90% to 99%.

[0017] In some embodiments of the present disclosure, the conditions of the ultrasonic treatment are: temperature 25-30° C., ultrasonic frequency 35-40 kHz, and time 15-20 min.

[0018] A collector for coal slime flotation is prepared by the above method.

[0019] Compared with the prior art, the above-mentioned method for preparing surfactant and collector for coal slime flotation has the following beneficial effects:

[0020] 1. The surfactant disclosed in the present invention has a hydrophilic end that can shield the hydrophilic sites on the coal surface, thereby achieving surface modification of oxygen-containing functional groups on the surface of low-rank coal, avoiding the adsorption of water molecules on the coal surface, and solving the problem of high flotation drug consumption of low-quality coal; the hydrophobic end can aggregate with non-polar hydrocarbon oils through hydrophobic interactions, thereby improving the hydrophobicity of the coal surface;

[0021] 2. The surfactant disclosed in the present invention has a low critical micelle concentration and good surface activity, which can significantly reduce the surface tension of the slurry system and the oil-water interfacial tension, and is conducive to enhancing the dispersion effect of the collector droplets and the spreading on the surface of the coal particles. By synergizing with non-polar hydrocarbon oils, the recovery rate of the flotation clean coal product is improved;

[0022] 3. The pseudo-gemini surfactant proposed in the present invention has the significant advantages of a wide source of synthetic raw materials, a simple and economical preparation process, and can effectively reduce the reagent cost of the flotation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the ATR-FTIR graph of LAL / HMDA;

[0024] Figure 2 is the surface tension diagram of LAL / HMDA;

[0025] Figure 3 It is a comparison diagram of the interfacial tension between kerosene and water, and between kerosene and LAL / HMDA solution;

[0026] Figure 4 A schematic diagram of the device structure for testing the droplet spreading performance of the collector;

[0027] Figure 5 It is a schematic diagram comparing the equilibrium contact angles of kerosene and the collector of the present application at the coal-water interface. DETAILED DESCRIPTION

[0028] In order to better understand the purpose, structure and function of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below. It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present application. The terms used herein in this application are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0029] This embodiment discloses a method for preparing a surfactant for coal slime flotation, wherein fatty acids with different carbon chain lengths and diamines with different carbon chain lengths terminated with amine groups are dissolved in an organic solvent, mixed and stirred, and a pseudo-gemini surfactant is prepared.

[0030] Wherein, the organic solvent is any one of acetone, toluene and pyridine; the pseudo-gemini surfactant of this embodiment is prepared by mixing fatty acids of different carbon chain lengths and diamines terminated with amine groups in a substance ratio of 2:1 using acetone as solvent, preferably, the fatty acid is a combination of any two of C6 to C16 fatty acids, in this embodiment, the fatty acid is lauric acid, and lauric acid LAL (20.04 g, 0.1 mol) is accurately weighed during the preparation of this embodiment; the diamine terminated with amine groups is any one of C2 to C6 diamines, in this embodiment, the diamine is 1,6-hexanediamine HMDA, and 1,6-hexanediamine HMDA (5.81 g, 0.05 mol) is accurately weighed during the preparation of this embodiment;

[0031] Accurately weighed lauric acid LAL (20.04 g, 0.1 mol), 1,6-hexanediamine HMDA (5.81 g, 0.05 mol) and 40 g acetone were added into a beaker equipped with a magnetic stirrer. The beaker was sealed with plastic wrap and placed on a magnetic stirrer for stirring. The stirring temperature was set to 25°C and the reaction time was 24 h.

[0032] The reaction formula for preparing the pseudo-gemini surfactant is as follows:

[0033]

[0034] Among them, R is Any of the following:

[0035] 6≤n≤16; 2≤m≤6.

[0036] In this example, the synthesized pseudo-gemini surfactant LAL / HMDA was characterized by ATR-FTIR. Figure 1 As shown, the structure is:

[0037]

[0038] Among them, m=6, n=12.

[0039] The surface activity of the synthetic LAL / HMDA was tested as follows:

[0040] The surface tension of surfactants with different concentrations was measured by the K100 surface tension meter hanging plate method. The measuring temperature was 25°C and each point was measured three times.

[0041] Draw a linear fitting curve of the surface tension of pseudo-gemini surfactants as a function of concentration, such as Figure 2 The cmc of the pseudo-gemini surfactant is 0.4 mM, and the corresponding γ cmc is 24.15 mN / m, which proves that LAL / HMDA has extremely strong surface activity.

[0042] The surface activity of the synthesized LAL / HMDA was tested by oil-water interfacial tension as follows:

[0043] Accurately weigh LAL / HMDA (500.00 mg) and 500 mL of deionized water into a beaker and add a magnetic stirrer. Seal the beaker mouth with plastic wrap and place it on a stirrer for stirring. The stirring temperature is set to 25°C and the stirring time is 45 minutes to obtain a LAL / HMDA solution with a mass concentration of 1000 ppm. The interfacial tension of kerosene and water, and kerosene and LAL / HMDA solution was measured using the K100 surface tension meter hanging plate method. The results are as follows: Figure 3As shown in the figure: the interfacial tension between kerosene and LAL / HMDA solution is 27.45 mN / m, which is much lower than 38.43 mN / m between kerosene and water. It can be seen that the pseudo-gemini surfactant prepared in this example can significantly reduce the oil-water interfacial tension and promote the dispersion of kerosene in the slurry system.

[0044] Also disclosed is a surfactant prepared by the method.

[0045] Also disclosed is a method for preparing a collector for coal slime flotation, which comprises placing the above-mentioned surfactant and non-polar hydrocarbon oil in a container, mixing them uniformly through ultrasonic treatment, and obtaining the collector.

[0046] The non-polar hydrocarbon oil can be any one of dodecane, kerosene or diesel; in this embodiment, the non-polar hydrocarbon oil is kerosene.

[0047] Prepare pure kerosene as a reference example of the composite collector for coal slime flotation disclosed in the present invention;

[0048] The mass percentage of LAL / HMDA is 1%, and the mass percentage of kerosene is 99%; they are added into a small sample bottle respectively, and ultrasonically mixed to obtain the coal slime flotation composite collector 1 of this embodiment;

[0049] Prepare the LAL / HMDA with a mass percentage of 5% and the kerosene with a mass percentage of 95%; add them into a small sample bottle respectively, and mix them evenly by ultrasonication to obtain the coal slime flotation composite collector 2 of this embodiment;

[0050] Prepare the LAL / HMDA with a mass percentage of 10% and the kerosene with a mass percentage of 90%; add them into a small sample bottle respectively, and mix them evenly by ultrasonication to obtain the coal slime flotation composite collector 3 of this embodiment;

[0051] The coal slime flotation compound collector 1, the coal slime flotation compound collector 2 and the coal slime flotation compound collector 3 are respectively mixed uniformly by ultrasound, and the conditions of the ultrasound treatment are: temperature 25-30° C., ultrasonic frequency 35-40 kHz, and time 15-20 min.

[0052] The droplet spreading performance tests were carried out on pure kerosene and coal slime flotation composite collector 1 respectively: the CHRONOS2.1-HD high-speed dynamic analysis system was used to study the spreading behavior of kerosene and the coal slime flotation composite collector 1, coal slime flotation composite collector 2 and coal slime flotation composite collector 3 at the low-rank coal / water interface in this embodiment, with a resolution of 1920×1080 and equipped with an operation display system (which can be used to adjust the frame rate and exposure time). The schematic diagram of the test device is shown in FIG. Figure 4 As shown;

[0053] A transparent test tank is filled with deionized water 1, a coal block 2 is placed in the tank and immersed in the deionized water 1, a syringe 3 filled with a collector pushes droplets into the test tank, a light source 4 is provided on one side of the test tank, and a high-speed dynamic camera 5 is used to record the spreading and wetting process of the collector droplets on the surface of the low-rank coal.

[0054] The images of the spread equilibrium contact angle were processed using Image J software. Figure 5 It can be seen that the equilibrium contact angle of kerosene at the low-rank coal-water interface is 143.2°, while the equilibrium contact angle of the composite collector at the low-rank coal-water interface is 98.2°, indicating that the addition of the pseudo-gemini surfactant prepared in Example 1 greatly improves the spreading performance of the collector on the coal surface.

[0055] Flotation test: 1.0LXFD hanging trough flotation machine was used, and the main shaft speed was 1800rpm. 80g of dry coal sludge was weighed and poured into the flotation tank filled with tap water to prepare flotation slurry (slurry concentration was 80g / L), stirred and slurried for 2min, and then the compound collector prepared in the above test was added at a dosage of 10.0kg / t and stirred for 4min, and the frother (sec-octanol) was added at a dosage of 200g / t, stirred for 30s, and scraped for 4min after air was introduced. The scraped foam and the residue at the bottom of the tank were the flotation clean coal and flotation tail coal, which were filtered, dried and weighed respectively, and the combustible recovery rate of the obtained products was calculated.

[0056] The flotation test results are shown in Table 1.

[0057] Table 1

[0058]

[0059] It can be seen from Table 1 that, under the condition of the same collector dosage, compared with the traditional hydrocarbon oil collector, the composite collector for coal slime flotation of the present invention can significantly improve the recovery rate of clean coal combustibles, indicating that the pseudo-gemini surfactant prepared by the present invention has an excellent synergistic effect with the traditional hydrocarbon oil collector in enhancing the flotation performance of low-rank coal slime.

[0060] It should be noted that, in the coal sample of lump coal 2 in this embodiment, the raw coal ash content is 26.79%. After crushing, the coal slime with a particle size of -0.045 mm accounts for 44.51% of the coal sample.

[0061] Also disclosed is a collector for coal slime flotation prepared by the method.

[0062] It can be understood that the above description is only for illustrating the specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any changes or substitutions within the technical scope disclosed in the present application should be included in the disclosure scope of the present application.

Claims

1. A method for preparing a surfactant for coal slime flotation, characterized in that: Two fatty acids with different carbon chain lengths and an amine-terminated diamine are dissolved in an organic solvent, wherein the molar ratio of the fatty acid to the amine-terminated diamine is 2:1; the mixture is mixed and stirred to prepare a pseudo-gemini surfactant.

2. The method for preparing a surfactant for coal slime flotation according to claim 1, characterized in that: The reaction formula for the preparation of the pseudo-gemini surfactant is as follows: Among them, R is Any of the following: 6≤n≤16； 2≤m≤6。 3. The method for preparing a surfactant for coal slime flotation according to claim 2, characterized in that: The organic solvent is any one of acetone, toluene and pyridine.

4. The method for preparing a surfactant for coal slime flotation according to claim 3, characterized in that: The stirring temperature is 20-25°C and the stirring time is 24-30h.

5. The surfactant according to claim 1, characterized in that Prepared by the method according to claim 1.

6. A method for preparing a collector for coal slime flotation, characterized in that: The surfactant according to claim 5 and the non-polar hydrocarbon oil are placed in a container and mixed evenly by ultrasonic treatment to obtain a collector.

7. The method for preparing a collector for coal slime flotation according to claim 6, characterized in that: The non-polar hydrocarbon oil is any one of dodecane, kerosene or diesel.

8. The method for preparing a collector for coal slime flotation according to claim 7, characterized in that: The mass percentage of the surfactant is 1% to 10%, and the mass percentage of the non-polar hydrocarbon oil is 90% to 99%.

9. The method for preparing a collector for coal slime flotation according to claim 6, characterized in that: The conditions of the ultrasonic treatment are as follows: temperature 25-30° C., ultrasonic frequency 35-40 kHz, and time 15-20 min.

10. The collector for coal slime flotation according to claim 6, characterized in that: Prepared by the method according to claim 6.

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