A surfactant and collector preparation method for coal slime flotation

Abstract

This invention discloses a surfactant and collector for coal slime flotation, and their preparation method, belonging to the technical field of separating solid materials from fluid minerals. The method includes: dissolving fatty acids of different carbon chain lengths and amino-terminated diamines in an organic solvent, mixing and stirring to prepare a pseudo-gemini surfactant; and mixing the pseudo-gemini surfactant with a non-polar hydrocarbon collector, followed by ultrasonic treatment to obtain a compound collector. The pseudo-gemini surfactant and collector prepared by this invention can enhance the adsorption, spreading, and dispersion performance of the reagents on the coal surface and in the slurry, exhibiting excellent synergistic effects in improving the flotation efficiency of low-rank coal slime. The pseudo-gemini surfactant of this invention has the advantages of good performance, low cost, and low pollution, which can promote the clean and efficient processing and utilization of coal resources.

Description

Technical Field

[0001] This invention relates to the technical field of separating solid materials from fluid minerals, and in particular to surfactants and collectors for separating coal slime by foam flotation, and methods for their preparation. Background Technology

[0002] Coal is a fundamental energy source and an important industrial raw material in my country. Currently, with the deepening of coal resource mining and the increasing mechanization of coal mining, the production of coal slime has been rising. Conventional flotation collectors are inefficient and costly in the separation and acquisition of coal slime. Therefore, finding efficient flotation collectors for coal slime is one of the effective methods to improve the processing capacity of low-rank coal and to cleanly produce high-quality low-rank coal.

[0003] Foam flotation separates coal from impurities by utilizing the differences in hydrophobicity of different mineral surfaces. Collectors can improve the surface hydrophobicity of coal and gangue minerals, playing a crucial role in the flotation process. In conventional flotation, hydrocarbon oils such as kerosene and diesel are generally used as flotation collectors for the selective separation of coal slime. However, low-rank coal, due to its lower degree of coalification, contains a large number of oxygen-containing functional groups on its surface, such as carboxyl, hydroxyl, and methoxy groups. This causes a large number of water molecules to be adsorbed on the coal surface through interaction with oxygen-containing groups during the flotation process, forming a hydration film. This severely hinders the adsorption and spreading of oil collector molecules on the coal surface, and this problem has become a major factor affecting the quality improvement of low-rank coal flotation. Summary of the Invention

[0004] In view of at least one of the above-mentioned technical problems, the present invention provides a surfactant and a method for preparing a collector for coal slime flotation. An eco-friendly pseudo-gemini surfactant is compounded with a traditional non-polar hydrocarbon collector and applied to the flotation of low-rank coal slime to promote the spreading effect of the reagent on the surface of low-rank coal. This enhances the hydrophobicity of the coal surface, improves flotation efficiency, and reduces flotation costs. The specific technical solution is as follows:

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

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

[0007]

[0008] Where R is Any one of them;

[0009] 6≤n≤16;

[0010] 2≤m≤6.

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

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

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

[0014] A method for preparing a collector for coal slime flotation involves placing the aforementioned surfactant and non-polar hydrocarbon oil in a container and mixing them uniformly by ultrasonic treatment to obtain the collector.

[0015] In some embodiments of this disclosure, the nonpolar hydrocarbon oil is any one of dodecane, kerosene, or diesel oil.

[0016] In some embodiments of this disclosure, the surfactant is 1% to 10% by mass, and the nonpolar hydrocarbon oil is 90% to 99% by mass.

[0017] In some embodiments of this disclosure, the conditions for 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 method described above.

[0019] Compared with existing technologies, the above-mentioned methods for preparing surfactants and collectors for coal slime flotation have the following advantages:

[0020] 1. The surfactant described in this disclosure 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 reagent consumption in the flotation of low-quality coal; the hydrophobic end can aggregate with non-polar hydrocarbon oils through hydrophobic interaction, thereby improving the hydrophobicity of the coal surface.

[0021] 2. The surfactants described in this disclosure have low critical micelle concentrations and good surface activity, which can significantly reduce the surface tension of the slurry system and the oil-water interfacial tension, thus enhancing the dispersion effect of collector droplets and their spreading on the surface of coal particles. Through synergistic action with non-polar hydrocarbon oils, the recovery rate of flotation clean coal products is improved.

[0022] 3. The pseudo-gemini surfactant proposed in this invention has significant advantages such as a wide range of raw material sources, simple and economical preparation process, and can effectively reduce the reagent cost of the flotation process. Attached Figure Description

[0023] Figure 1 ATR-FTIR plot of LAL / HMDA;

[0024] Figure 2 Surface tension diagram of LAL / HMDA;

[0025] Figure 3 A comparison 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 microdroplet spreading performance of the collector;

[0027] Figure 5 This is a schematic diagram comparing the equilibrium contact angles of kerosene and the collector of this application at the coal-water interface. Detailed Implementation

[0028] To better understand the purpose, structure, and function of this invention, the technical solutions in the embodiments of this 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 commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit this application.

[0029] This embodiment discloses a method for preparing a surfactant for coal slime flotation. The method involves dissolving fatty acids with different carbon chain lengths and diamines with different carbon chain lengths capped with amino groups in an organic solvent, mixing and stirring to prepare a pseudo-gemini surfactant.

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

[0031] Accurately weighed LAL (20.04 g, 0.1 mol), 1,6-hexanediamine (HMDA) (5.81 g, 0.05 mol), and 40 g of acetone were added to a beaker equipped with a magnetic stir bar. The beaker was sealed with plastic wrap and placed on a magnetic stir bar 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] Where R is Any one of them;

[0035] 6≤n≤16; 2≤m≤6.

[0036] In this embodiment, the synthesized pseudogemini surfactant LAL / HMDA was characterized by ATR-FTIR, and the results are as follows: Figure 1 As shown, the structure is:

[0037]

[0038] Where m = 6 and n = 12.

[0039] The surface activity of the synthesized LAL / HMDA was tested using the following method:

[0040] The surface tension of surfactants of different concentrations was determined using a K100 surface tension meter via the hanging plate method. The measurement temperature was 25℃, and each point was measured three times.

[0041] Plot a linear fit curve of the surface tension of the pseudo-gemini surfactant as a function of concentration, such as... Figure 2 As shown, the CMC of the pseudo-gemini surfactant is 0.4 mM, and the corresponding γcmc is 24.15 mN / m, proving 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 500.00 mg of LAL / HMDA and 500 mL of deionized water into a beaker, add a magnetic stir bar, seal the beaker with plastic wrap, and place it on a stirrer for stirring. Set the stirring temperature to 25°C and the stirring time to 45 min to obtain a LAL / HMDA solution with a mass concentration of 1000 ppm. The interfacial tensions between kerosene and water, and between kerosene and the LAL / HMDA solution, were measured using a K100 surface tension meter via the hanging plate method. The results are as follows: Figure 3As shown, the interfacial tension between kerosene and LAL / HMDA solution is 27.45 mN / m, which is much lower than that between kerosene and water (38.43 mN / m). This indicates that the pseudo-gemini surfactant prepared in this embodiment can significantly reduce the oil-water interfacial tension and promote the dispersion of kerosene in the slurry system.

[0044] A surfactant prepared by the above method is also disclosed.

[0045] A method for preparing a collector for coal slime flotation is also disclosed, wherein the above-mentioned surfactant and non-polar hydrocarbon oil are placed in a container and mixed evenly by ultrasonic treatment to obtain the collector.

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

[0047] Pure kerosene was prepared as a reference example for the coal slime flotation compound collector disclosed herein;

[0048] Prepare LAL / HMDA with a mass percentage of 1% and kerosene with a mass percentage of 99%; add them separately to small sample bottles and mix them evenly by ultrasonication to obtain the coal slime flotation compound collector 1 of this embodiment;

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

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

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

[0052] Microdroplet spreading performance tests were conducted on pure kerosene and coal slime flotation compound collector 1. A CHRONOS 2.1-HD high-speed dynamic analysis system was used to study the spreading behavior of kerosene and the coal slime flotation compound collectors 1, 2, and 3 in this embodiment at the low-rank coal / water interface. The resolution was 1920×1080, and an operation display system (which can be used to adjust the frame rate and exposure time) was also included. A schematic diagram of the experimental setup is shown below. Figure 4 As shown;

[0053] A transparent test tank is filled with deionized water 1. Lump coal 2 is placed in the tank and immersed in deionized water 1. A syringe 3 containing a collector pushes microdroplets into the test tank. A light source 4 is provided on one side of the test tank. The process of the collector microdroplets spreading and wetting on the surface of low-rank coal is recorded by a high-speed dynamic camera 5.

[0054] The image of the spread-out balanced contact angle was processed using ImageJ 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 compound collector at the low-rank coal-water interface is 98.2°. This indicates 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: A 1.0LXFD hanging-tank flotation machine with a spindle speed of 1800 rpm was used. 80g of dry coal slime was weighed and poured into a flotation cell containing tap water to prepare flotation slurry (slurry concentration of 80g / L). After stirring and adjusting the slurry for 2 minutes, the compound collector prepared in the above test was added at a dosage of 10.0kg / t and stirred for 4 minutes. Frothing agent (2-octanol) was added at a dosage of 200g / t and stirred for 30 seconds. After air was introduced, the foam was scraped off for 4 minutes. The foam scraped off and the residue at the bottom of the tank were the flotation concentrate and flotation tailings, respectively. They were filtered, dried and weighed, and the combustible recovery rate of the obtained products was calculated.

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

[0057] Table 1

[0058]

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

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

[0061] A collector for coal slime flotation prepared by the above method is also disclosed.

[0062] It is understood that the above description is only for illustrating specific embodiments of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be covered within the scope of disclosure of this 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 amino-terminated diamine are dissolved in an organic solvent, wherein the organic solvent is any one of acetone, toluene, and pyridine; the molar ratio of the fatty acids to the amino-terminated diamine is 2:1; the mixture is stirred to prepare a pseudo-gemini surfactant; the reaction formula for preparing the pseudo-gemini surfactant is as follows: ； Where R is , or Any one of them; 6≤n≤16； 2≤m≤6。 2. The method for preparing surfactant for coal slime flotation according to claim 1, characterized in that: The stirring temperature is 20-25℃, and the stirring time is 24-30h.

3. A surfactant for coal slime flotation, characterized in that, It is prepared by the method described in claim 1.

4. A method for preparing a collector for coal slime flotation, characterized in that, The surfactant described in claim 3 and a non-polar hydrocarbon oil are placed in a container and mixed evenly by ultrasonic treatment to obtain a collector.

5. The method for preparing the collector for coal slime flotation according to claim 4, characterized in that: The non-polar hydrocarbon oil is any one of dodecane, kerosene, or diesel oil.

6. The method for preparing the collector for coal slime flotation according to claim 5, characterized in that: The surfactant has a mass percentage of 1% to 10%, and the non-polar hydrocarbon oil has a mass percentage of 90% to 99%.

7. The method for preparing the collector for coal slime flotation according to claim 4, characterized in that, The conditions for ultrasonic treatment are: temperature 25-30℃, ultrasonic frequency 35-40kHz, and time 15-20min.

8. A collector for coal slime flotation, characterized in that, It is prepared by the method described in claim 6.

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