Method for measuring optimized ionic liquid surfactant wetting long flame coal in laboratory

Abstract

The invention discloses a method for measuring long flame coal wetted by an optimized ionic liquid surfactant in a laboratory, which is characterized in that wetting parameters are calculated through a physical experiment to carry out numerical objective evaluation on the wetting effect of the surfactant, and meanwhile, the difference of the evaluation effect is revealed from a micro perspective in combination with a molecular simulation mode. Therefore, the optimal effect of the ionic liquid surfactant is achieved. Meanwhile, the invention provides reference suggestions for the evaluation of the main effect influence of the anionic group and imidazole chain length factors of the ionic liquid surfactant for the model selection of the ionic liquid surfactant in the aspect of long flame coal wetting in the future, and has great significance for the wider application of the ionic liquid surfactant in wet dust removal of coal mines.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mining, and in particular relates to a method for laboratory determination of a preferred ionic liquid surfactant for wetting long flame coal. Background Art

[0002] my country boasts abundant reserves of mineral resources. By the end of 2023, coal reserves reached 218.57 billion tons, a 5.6% increase from the end of 2022. In today's era of rapid global technological advancement, adequate energy supply has become a crucial cornerstone of scientific and economic development. Therefore, until new, reliable, and green energy sources are developed that can meet significant energy demand, coal will continue to dominate energy production for a long time to come. Currently, the coal mining industry is actively pursuing green mine construction, significantly improving the intelligence and technological advancements in coal production. However, dust, one of the five major hazards in coal mining, remains a significant safety hazard that is difficult to eradicate during current coal mining.

[0003] Inner Mongolia is rich in coal resources, with a total explored reserves of 1,001.179 billion tons, ranking first in the country in terms of proven reserves. Inner Mongolia has large reserves of low-metamorphic coal, such as lignite, long flame coal, and non-caking coal, and their distribution is extensive. The reserves of these three types of coal account for 97.66% of Inner Mongolia's coal reserves. At the same time, since most of the long flame coal mines in Inner Mongolia have simple occurrence conditions, there are many tens of millions of tons mines in the region, with high output and high mining intensity, so the difficulty of dust prevention increases accordingly, resulting in the problem of dust prevention and control in coal mine production in the region that cannot be ignored.

[0004] In order to prevent and control problems such as excessive dust concentration during coal mining, many mines have adopted wet dust removal methods to suppress dust generation and dust emission during coal mining and transportation. As for the currently more widely used wet dust prevention and dust reduction measures, the wetting effect of water on coal has a significant impact on the effectiveness of coal dust prevention and control measures. Therefore, research on how to improve the wetting effect of water on coal dust is of great significance to improving the dust prevention and control effect in coal mines.

[0005] During wet dust removal, surfactants are often added to reduce the surface tension of water, improve its wettability on coal, and optimize dust reduction. Ionic liquid surfactants are a new type of green solvent based on molten salts. Compared with other molecular solvents, ionic liquid surfactants have the characteristics of low volatility and strong stability. In addition, because they are composed of anions and cations, the properties of the ionic liquid surfactant molecules themselves can be changed by regulating the structure of anions and cations, thereby preparing surfactants with different properties and high designability. These characteristics make ionic liquid surfactants superior to general surfactants and have good prospects in wet dust removal in mines.

[0006] Currently, research on dust suppression relies primarily on experiments. Theoretical understanding of the microscopic wetting mechanisms of coal is incomplete, and progress in addressing fundamental issues in dust control remains slow, significantly hindering its development. Computer simulation technology can be used to study the microscopic interactions between surfactants, coal, and water at the molecular and atomic levels, thus addressing the limitations of experimental instrumentation. Summary of the Invention

[0007] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and provide a laboratory method for determining the optimal ionic liquid surfactant for wetting long flame coal, so as to achieve the optimal surfactant in the wet dust removal process and improve the dust reduction effect.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0009] A laboratory method for determining the wettability of a preferred ionic liquid surfactant for long flame coal comprises the following steps:

[0010] (1) Collect coal dust samples, prepare multiple coal slices, polish the surface of the coal slices to make them smooth, and dry them for later use;

[0011] (2) selecting an ionic liquid surfactant and determining its CMC concentration, and preparing several ionic liquid surfactant solutions with concentration gradients near the CMC concentration;

[0012] (3) Determine the wetting parameters through physical experiments, including the contact angle between the surfactant solution and the coal and the surface tension of the surfactant solution, and analyze the spreading coefficient of the surfactant on the coal surface;

[0013] (4) The relationship between the spreading coefficient, the coal-water contact angle, and the liquid surface tension is calculated using the following formula:

[0014] S=γ LG (cosθ-1) (1-1)

[0015] Where S is the spreading coefficient, mN / m;

[0016] γ LG is the surface tension of the surfactant solution, mN / m;

[0017] θ is the contact angle, °;

[0018] The contact angle θ is calculated by combining the interaction force between the liquid and the coal dust surface, the cohesive force between the liquid molecules, and the dynamic interaction between the liquid and the coal dust surface as follows:

[0019]

[0020] Where: θ0 is the initial contact angle of the liquid droplet falling on the coal sample surface, °;

[0021] θ e is the equilibrium contact angle when diffusion and penetration approach zero infinitely, °;

[0022] K is the wetting factor, representing the contact angle change rate constant, s -1 .

[0023] (5) Combined with molecular simulation to obtain a molecular structure model, the adsorption of long flame coal on ionic liquid surfactants was analyzed from a microscopic perspective;

[0024] (6) performing dynamic simulation on the molecular structure model obtained in step (5), calculating the binding energy of the water-surfactant-long flame coal molecular system, and verifying the wetting effect;

[0025] (7) By analyzing and comparing the adsorption performance obtained in step (6) with the wetting parameters obtained in step (4), the ionic liquid surfactant with the best wetting effect can be obtained.

[0026] The interaction energy between the long flame coal molecules and the water molecules in step (6) is calculated as follows:

[0027] In the pure water-long flame coal system, the interaction energy between long flame coal molecules and water molecules is calculated using formula (1-3):

[0028]

[0029] In the ionic liquid surfactant-water / long flame coal system, the interaction energy between long flame coal molecules and water molecules is calculated using formula (1-4):

[0030]

[0031] The interaction energy expression between long flame coal molecules and ionic liquid surfactant molecules is calculated using formula (1-5):

[0032]

[0033] The interaction energy between water molecules and ionic liquid surfactant molecules is calculated using formula (1-6):

[0034]

[0035] Among them, E total It represents the total energy in the entire molecular system;

[0036] E coal Represents the total energy of the long flame coal molecules in the system;

[0037] Represents the total energy of water molecules in the system;

[0038] E surfactant Represents the total energy of the ionic liquid surfactant molecules in the system;

[0039] E int represents the interaction energy, kcal / mol.

[0040] In step (5), the molecular simulation methods include but are not limited to industrial analysis, elemental analysis, nuclear magnetic resonance experiment, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD).

[0041] In step (6), SPSS software was used and multi-factor variance analysis was adopted for testing.

[0042] In step (1), coal slices with a diameter of 3 to 5 mm are used.

[0043] The beneficial effects of the present invention are:

[0044] (1) The present invention discloses a laboratory method for determining the optimal wetting performance of ionic liquid surfactants for long flame coal. The method numerically and objectively evaluates the wetting effect of surfactants by calculating wetting parameters through physical experiments. The method also combines molecular simulation to reveal the differences in the evaluation effects from a microscopic perspective, thereby achieving the optimal effect of ionic liquid surfactants. At the same time, the present invention's evaluation of the main effects of anionic groups and imidazole chain length factors of ionic liquid surfactants provides reference suggestions for the future selection of ionic liquid surfactants for long flame coal wetting, which is of great significance for the wider application of ionic liquid surfactants in wet dust removal in coal mines.

[0045] (2) The effect of ionic liquid surfactants on wetting long flame coal was measured in the laboratory to optimize the ionic liquid surfactants for wet dust removal. The functional group structure of long flame coal was studied and analyzed, the molecular structure of coal suitable for the sample was constructed, and the system binding effect was verified by molecular simulation. At the same time, the main factors affecting the water-coal contact angle of ionic liquid surfactants were analyzed using significant effect analysis, which provided guidance for the future application of ionic liquid surfactants in wet dust removal in mines, and has important significance for the application of ionic liquid surfactants in dust suppression and control.

[0046] (3) Compared with the research method of single physical experiment, molecular simulation approaches from the perspective of microscopic mechanism, providing new ideas for research, reducing costs and improving research efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a flow chart of the present invention;

[0048] Figure 2 It is the macromolecular structure of Inner Mongolia long flame coal constructed by the present invention;

[0049] Figure 3 is the spreading coefficient of the six ionic liquid surfactants on the coal surface;

[0050] Figure 4 This paper is an analysis of the dynamic wetting factor of ionic liquid surfactants on the surface of long flame coal. DETAILED DESCRIPTION

[0051] The following describes the implementation of the present invention through specific embodiments. People skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0052] The present invention provides a method for laboratory determination of the wettability of long flame coal by a preferred ionic liquid surfactant, such as Figures 1 to 4 shown.

[0053] A laboratory method for determining the wettability of a preferred ionic liquid surfactant for long flame coal comprises the following steps:

[0054] (1) Collect coal dust samples, prepare a plurality of coal slices, grind the surface of the coal slices to be smooth, and dry them for later use; in this embodiment, a plurality of coal slices of 3 to 5 mm are prepared, the surface of the coal slices is grinded to be smooth, and the coal slices are dried for later use.

[0055] (2) Select an ionic liquid surfactant and determine its CMC concentration, and prepare several ionic liquid surfactant solutions with concentration gradients near the CMC concentration.

[0056] Several widely used ionic liquid surfactants were selected, their CMC concentrations were determined by consulting the literature, and several ionic liquid surfactant solutions with concentration gradients near the CMC concentration were prepared.

[0057] (3) Determine the wetting parameters through physical experiments, including the contact angle between the surfactant solution and the coal and the surface tension of the surfactant solution, and analyze the spreading coefficient of the surfactant on the coal surface;

[0058] Through physical experiments, the contact angle between the surfactant solution and the coal, the surface tension of the surfactant solution, and the wettability parameters such as the spreading coefficient of the surfactant on the coal surface were determined.

[0059] (4) The relationship between the spreading coefficient, the coal-water contact angle, and the liquid surface tension is calculated using the following formula:

[0060] S=γ LG (cosθ-1) (1-1)

[0061] Where S is the spreading coefficient, mN / m;

[0062] γ LG is the surface tension of the surfactant solution, mN / m;

[0063] θ is the contact angle, °;

[0064] The larger the spreading coefficient of the ionic liquid surfactant solution on the coal surface, the better the wetting effect of this type of surfactant on the coal.

[0065] In the discussion of coal-water contact angle, dynamic wetting takes into account the interaction force between the liquid and the coal dust surface and the cohesive force between liquid molecules in more depth, which can better reflect the wetting efficiency of the liquid in practical applications. It also takes into account the dynamic interaction between the liquid and the coal dust surface, which can more accurately describe the wetting efficiency of the surfactant solution on the coal.

[0066] The contact angle θ is calculated by combining the interaction force between the liquid and the coal dust surface, the cohesive force between the liquid molecules, and the dynamic interaction between the liquid and the coal dust surface as follows:

[0067]

[0068] Where: θ0 is the initial contact angle of the liquid droplet falling on the coal sample surface, °;

[0069] θ e is the equilibrium contact angle when diffusion and penetration approach zero infinitely, °;

[0070] K is the wetting factor, representing the contact angle change rate constant, s -1 .

[0071] In this kinetic model, K is the wettability factor, which can characterize the wetting ability of the solution droplets on the coal surface. The larger the K value, the better the wettability of the droplets on the coal sample surface, and the faster the diffusion and penetration rates. Based on the calculation of the K value of the ionic liquid surfactant and the spreading coefficient, the ability of the ionic liquid surfactant to wet long flame coal can be basically ranked.

[0072] (5) Combined with molecular simulation to obtain a molecular structure model, the adsorption of ionic liquid surfactants on coal was analyzed from a microscopic perspective;

[0073] (6) performing dynamic simulation on the molecular structure model obtained in step (5), calculating the binding energy of the water-surfactant-coal molecular system, and verifying the wetting effect;

[0074] (7) By analyzing and comparing the adsorption performance obtained in step (6) with the wetting parameters obtained in step (4), the ionic liquid surfactant with the best wetting effect can be obtained.

[0075] To further verify this from a molecular perspective, we inferred the coal's molecular formula through FTIR and XPS experiments. We analyzed the molecular structure using industrial analysis, elemental analysis, nuclear magnetic resonance, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Using Materials Studio molecular simulation software, we constructed a macromolecular structure model of the long flame coal suitable for the sample.

[0076] A reasonable surfactant molecular model was constructed, and the wetting effect was verified by calculating the binding energy of the water-surfactant-coal molecular system through dynamic simulation. To analyze the adsorption of long flame coal on ionic liquid surfactant solution, a molecular dynamics adsorption simulation system of long flame coal molecules, water molecules, and surfactant molecules was constructed and calculated using Materials Studio 2023.

[0077] First, in the Forcite module, the Geometry Optimization task was selected to perform geometry optimization on the ionic liquid surfactant and long flame coal molecules. The convergence algorithm was selected as Smart, and the calculation accuracy was gradually increased to Fine. The optimization was repeated to obtain the lowest energy configuration, which was then subjected to Anneal annealing. This configuration was then selected for the dynamics system. Using the Amorphous cell module and the Build Layers function, a mixed system was constructed using 20 long flame coal molecules, 10 ionic liquid surfactant molecules, and 2000 water molecules. The mixed system was subjected to the same geometry optimization and annealing procedures using the COMPASSIII force field. Dynamics simulations were performed on the resulting lowest energy configuration. The COMPASSIII force field was used throughout the dynamics simulations, with the NVT ensemble selected, the temperature set to 298 K, the Nose temperature control method selected, a step size of 1.0 fs, and a simulation duration of 2000 ps to ensure that the reaction proceeded fully to adsorption equilibrium.

[0078] In the coal-water-surfactant system, the interaction energy between the components is a key factor in providing a deeper understanding of the microscopic mechanisms of wetting. Molecular dynamics simulations were used to calculate the interaction energy between the components in the system. The analysis revealed the adsorption behavior of ionic liquid surfactant molecules on the surface of long flame coal, the strength of the interactions between water molecules, the long flame coal surface, and the ionic liquid surfactant, and how these interactions affect the wettability of long flame coal. A negative interaction energy indicates that the reaction process is spontaneous; a larger absolute value of the interaction energy indicates a stronger interaction between the molecules.

[0079] In the pure water-long flame coal system, the interaction energy between long flame coal molecules and water molecules can be calculated by formula (1-3):

[0080]

[0081] In the ionic liquid surfactant-water / long flame coal system, the interaction energy between long flame coal molecules and water molecules should be expressed by formula (1-4):

[0082]

[0083] The interaction energy expression between long flame coal molecules and ionic liquid surfactant molecules is shown in formula (1-5):

[0084]

[0085] The expression of the interaction energy between water molecules and ionic liquid surfactant molecules is shown in formula (1-6):

[0086]

[0087] In formulas (1-3) to (1-6), E total Represents the total energy of the entire molecular system; E coal Represents the total energy of the long flame coal molecules in the system; Represents the total energy of water molecules in the system; E surfactant represents the total energy of the ionic liquid surfactant molecules in the system; E int represents the interaction energy, kcal / mol.

[0088] The energy_ThreeEint_Ebin.pl script was used to calculate the interaction energies between ionic liquid surfactant molecules and long flame coal molecules, ionic liquid surfactant molecules and water molecules, and long flame coal molecules and water molecules in the system. Combined with the wetting parameter analysis, the ionic liquid surfactant with the best wetting effect on long flame coal was obtained.

[0089] To investigate the effects of the anionic group and cationic imidazole chain length of ionic liquid surfactant molecules on improving the wetting properties of long flame coal, a multi-factor analysis of variance (ANOVA) was performed using SPSS software. The contact angles between ionic liquid surfactants with different imidazole chain lengths and anionic groups and long flame coal at similar time points were tested for inter-subject effects. The significance of the main effects and interaction effects of each factor was determined. This study can provide a reference for the future selection of other types of ionic liquid surfactants.

[0090] The following describes the embodiments of the present invention using specific examples. The present invention provides a laboratory method for determining the wettability of a preferred ionic liquid surfactant for long flame coal wet dust removal. The following example illustrates the wettability of long flame coal dust from the Shangwan Coal Mine in Inner Mongolia using an ionic liquid surfactant, and provides a detailed description with accompanying diagrams.

[0091] The process of this method is as follows Figure 1 shown.

[0092] (1) The samples from Shangwan Coal Mine in Inner Mongolia were crushed and sieved, and six ionic liquid surfactants, C12MImBF4, C12MImBr, C12MImCl, C16MImBr, C14MImBr and C16MImCl, were selected. The 200-mesh coal powder was fully stirred, filtered and dried using the ionic liquid surfactants.

[0093] (2) The surface tension of the ionic liquid surfactant solution and the contact angle of the coal-surfactant solution were measured to obtain the spreading coefficient and dynamic wetting equation. Analysis of the wetting parameters showed that among the six ionic liquid surfactants, C12MImBF4 had the best wetting effect on long flame coal, while C12MImBr had the worst effect.

[0094] (3) After normalizing the long flame coal according to the elemental analysis data, Table 2-1 was obtained. The atomic ratios of various types in the coal sample were calculated, among which H / C was 0.599, O / C was 0.147, N / C was 0.001, and S / C was 0.003. The molecular formula of the coal sample structure model was preliminarily determined to be C n H 0.599n O 0.147n N 0.001n S 0.003n .

[0095] Table 2-1 Normalized results and atomic ratio of long flame coal

[0096]

[0097] Bridge carbon ratio (X BP ) represents the average degree of polycondensation of aromatic carbon and the size of the aromatic nucleus. The formula for the bridging carbon ratio is:

[0098]

[0099] Substituting the data into formula (2-1) we can get X BPThe ratio of the bridge carbon of benzene, naphthalene, phenanthrene to anthracene and pyrene is about 0.15, and the bridge carbon ratios of benzene, naphthalene, phenanthrene, anthracene and pyrene are 0, 0.25, 0.4 and 0.5 respectively. Therefore, it is determined that the aromatic structural units of long flame coal are mainly benzene rings and naphthalene rings. Assuming that the relative molecular mass of coal is 2000-3000, the number of benzene rings is x1, the number of naphthalene rings is x2, the number of pyrroles is 1, and the number of thiophenes is 1. Based on X BP The results and equations (2-2) to (2-4) are used for calculation, with the initial assumption that the total number of carbon atoms in coal is 148.

[0100] 6x1+10x2+8=63.61%×148(2-2)

[0101]

[0102] The solution is: x1=4, x2=6

[0103] Substitute the calculated aromatic structural unit into X BP Formula is calculated to get the new X BP *=0.15. XBP* and X BP Keep two significant figures and make them exactly the same. Substitute into X BP *, we get formula (2-5):

[0104] 6×4+10×6+8=63.62%×n(2-5)

[0105] The solution is n = 145, that is, the total number of carbon atoms in long flame coal is 145, and the molecular formula of long flame coal is finally determined to be C 145 H 87 O 21 NS.

[0106] (4) According to the obtained molecular formula, a long flame coal macromolecular model corresponding to the sample was constructed, and an ionic liquid surfactant-water-coal molecular system was constructed for dynamic simulation, and the binding energy between the system components was calculated according to the formula.

[0107] Table 2-2 Intermolecular interaction energy in the ionic liquid surfactant / water / long flame coal system

[0108]

[0109] From the perspective of molecular simulation, it can be concluded that after the addition of ionic liquid surfactants, the interaction strength between coal molecules and water molecules in the system is enhanced, the interaction between water molecules and long flame coal becomes closer, and the wettability of long flame coal is also improved. The order of the interaction strength between the six ionic liquid surfactant molecules and water molecules is C 12 MImBF4>C 16 MImBr>C 14 MImBr>C 16MImCl>C 12 MImCl>C 12 MImBr. The feasibility of the method was also verified.

[0110] (5) A multivariate analysis of variance was conducted. The contact angle was set as the dependent variable, and the imidazole chain length and anionic group of the ionic liquid surfactant were included in the model as independent variables. The significance of the model as a whole and the effects of each factor were tested by calculating statistics such as the type III sum of squares, degrees of freedom, mean square, and F value. The degree to which each factor explained the variation in the dependent variable was evaluated using the partial Eta square. The results are shown in Table 3-1.

[0111] Table 3-1 Analysis of the significance of the effects of imidazole chain length and anionic group of ionic liquid surfactants on wetting properties

[0112]

[0113] The above analysis results show that both the imidazole chain length and the anionic group of the ionic liquid surfactant have significant main effects on the coal-water contact angle between long flame coal and the ionic liquid surfactant solution, and the effect of the anionic group is more significant than that of the imidazole chain length, while the interaction between the two has no significant effect on the contact angle. Therefore, in the future, the wetting effect of long flame coal can be improved by selecting ionic liquid surfactants with different anionic group polarity or imidazole chain length.

[0114] This laboratory method for determining the optimal wetting performance of ionic liquid surfactants for long-flame coal uses physical experiments to calculate wetting parameters, objectively evaluating the surfactant's wetting effect numerically. This method, combined with molecular simulations, reveals microscopic differences in the evaluation effects, thereby achieving the optimal effect of ionic liquid surfactants. Furthermore, this method's assessment of the primary effects of the anionic group and imidazole chain length of ionic liquid surfactants provides guidance for future selection of ionic liquid surfactants for long-flame coal wetting, and is of great significance for the wider application of ionic liquid surfactants in wet dust removal in coal mines.

[0115] If the terms "first" and "second" are used in this patent to limit components, those skilled in the art should know that the use of "first" and "second" is only for the convenience of describing the present invention and simplifying the description, and the above terms have no special meaning.

[0116] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications are possible without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the claimed invention. The scope of the present invention is defined by the appended claims and their equivalents.

[0117] In the description of the present invention, it should be understood that the terms "front", "rear", "left", "right", "center", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the protection content of the present invention.

Claims

1. A laboratory method for determining the wettability of long flame coal by a preferred ionic liquid surfactant, characterized in that: The following steps are involved: (1) Collect coal dust samples, prepare multiple coal slices, polish the surface of the coal slices to make them smooth, and dry them for later use; (2) selecting an ionic liquid surfactant and determining its CMC concentration, and preparing several ionic liquid surfactant solutions with concentration gradients near the CMC concentration; (3) Determine the wetting parameters through physical experiments, including the contact angle between the surfactant solution and the coal and the surface tension of the surfactant solution, and analyze the spreading coefficient of the surfactant on the coal surface; (4) The relationship between the spreading coefficient, the coal-water contact angle, and the liquid surface tension is calculated using the following formula: S=γ LG (cosθ-1) (1-1) Where S is the spreading coefficient, mN / m; γ LG is the surface tension of the surfactant solution, mN / m; θ is the contact angle, °; The contact angle θ is calculated by combining the interaction force between the liquid and the coal dust surface, the cohesive force between the liquid molecules, and the dynamic interaction between the liquid and the coal dust surface as follows: Where: θ0 is the initial contact angle of the liquid droplet falling on the coal sample surface, °; θ e is the equilibrium contact angle when diffusion and penetration approach zero infinitely, °; K is the wetting factor, representing the contact angle change rate constant, s -1 . (5) Combined with molecular simulation to obtain a molecular structure model, the adsorption of long flame coal on ionic liquid surfactants was analyzed from a microscopic perspective; (6) performing dynamic simulation on the molecular structure model obtained in step (5), calculating the binding energy of the water-surfactant-long flame coal molecular system, and verifying the wetting effect; (7) By analyzing and comparing the adsorption performance obtained in step (6) with the wetting parameters obtained in step (4), the ionic liquid surfactant with the best wetting effect can be obtained.

2. A method for laboratory determination of the preferred ionic liquid surfactant wetting of long flame coal according to claim 1, characterized in that: The interaction energy between the long flame coal molecules and the water molecules in step (6) is calculated as follows: In the pure water-long flame coal system, the interaction energy between long flame coal molecules and water molecules is calculated using formula (1-3): In the ionic liquid surfactant-water / long flame coal system, the interaction energy between long flame coal molecules and water molecules is calculated using formula (1-4): The interaction energy expression between long flame coal molecules and ionic liquid surfactant molecules is calculated using formula (1-5): The interaction energy between water molecules and ionic liquid surfactant molecules is calculated using formula (1-6): Among them, E total It represents the total energy in the entire molecular system; E coal Represents the total energy of the long flame coal molecules in the system; Represents the total energy of water molecules in the system; E surfactant Represents the total energy of the ionic liquid surfactant molecules in the system; E int represents the interaction energy, kcal / mol.

3. The method for laboratory determination of the preferred ionic liquid surfactant wetting of long flame coal according to claim 1, characterized in that: In step (5), the molecular simulation methods include but are not limited to industrial analysis, elemental analysis, nuclear magnetic resonance experiment, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD).

4. The method for laboratory determination of the wetting performance of long flame coal by an ionic liquid surfactant according to claim 1, characterized in that: In step (6), SPSS software was used and multi-factor variance analysis was adopted for testing.

5. The method for laboratory determination of the wetting performance of long flame coal by an ionic liquid surfactant according to claim 1, characterized in that: In step (1), coal slices with a diameter of 3 to 5 mm are used.

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