Method for deashing raw coal using deep eutectic solvent

Abstract

The present invention relates to a method for deashing raw coal using a deep eutectic solvent. In the technical solution, a hydrogen bond acceptor and a hydrogen bond donor are first heated and mixed in a certain molar ratio to prepare a deep eutectic solvent, and then the raw coal and the prepared deep eutectic solvent are mixed in a certain mass ratio to perform a deashing process, and finally the treated coal is washed clean with deionized water by utilizing the property that the deep eutectic solvent is easily soluble in water. According to the present invention, the raw coal ash content can be reduced by 9-18%, and the technical solution is simple to operate, low in cost, and harmless to human body and environment.

Description

Technical Field

[0001] The present invention relates to the field of coal chemical process technology, and in particular to a method for treating raw coal by using a low eutectic solvent, which can reduce the ash content in the raw coal for preparing low-ash coal and clean coal. Background Art

[0002] At present, coal is one of the world's main energy sources. In the face of increasingly scarce oil resources, how to efficiently utilize coal resources has become a hot issue. In my country, particulate pollutants have gradually become the primary pollutant of urban air pollution, and coal combustion in power plants is one of the main sources of pollution. During the combustion of coal, the ash of coal will become fine particles. The surface of these particles is enriched with heavy metal elements. After being discharged into the air, it will cause great harm to the human body and the environment. In addition, the ash of coal will inhibit the transfer of combustion heat, thereby reducing thermal efficiency and greatly reducing the utilization rate of coal. Therefore, it is particularly important to deash the coal before use.

[0003] At present, some of the deashing methods being studied are mainly physical and chemical methods. Physical deashing methods of coal mainly include magnetic separation, electrostatic separation and flotation, which are determined by the mineral properties of coal and the physical properties of some coal. Chemical deashing methods of coal mainly include acid and alkali methods, which react the organic components in coal with chemical substances to effectively remove minerals, thereby achieving the purpose of reducing ash content. However, the existing technology requires high costs and complex operations. Most of the chemical reagents used are harmful to the human body and the environment, and are corrosive to instruments and equipment.

[0004] Therefore, providing a low-cost, green and environmentally friendly method for deashing raw coal is of great significance to improving the utilization rate of coal resources. Summary of the invention

[0005] In view of this, the present invention provides a method for deashing raw coal using a low eutectic solvent, which effectively removes ash from the raw coal, reduces production costs, reduces harm to the environment, improves the quality of coal, and has good economic benefits.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The method for deashing raw coal using a deep eutectic solvent comprises the following steps:

[0008] (1) After the raw coal is naturally air-dried for 12-24 hours, it is crushed to obtain coal powder;

[0009] (2) Mixing a hydrogen bond acceptor and a hydrogen bond donor reagent in a certain molar ratio, heating and continuously stirring to prepare a low eutectic solvent;

[0010] (3) The coal powder obtained in step (1) is added to the low eutectic solvent obtained in step (2) in proportion, heated and stirred continuously, filtered while hot, washed with deionized water, and dried.

[0011] Preferably, the particle size of the raw coal crushed in step (1) is 100-300 μm. The small particle size increases the contact area between the raw coal and the reagent, thereby improving the treatment efficiency and treatment effect.

[0012] Preferably, the heating temperature in step (2) is 70-90° C. until all the solids are melted and the solvent is transparent.

[0013] Preferably, in step (3), the mass ratio of coal powder to low eutectic solvent is 1:2.

[0014] Preferably, the heating temperature in step (3) is 50-180° C., and the reaction is stirred for 3-5 hours.

[0015] Preferably, in step (3), washing is performed with deionized water until the filtrate is neutral to ensure that the low eutectic solvent is completely removed.

[0016] Preferably, the drying temperature in step (3) is 50-90° C., and the drying time is 20-24 hours.

[0017] Through the above technical scheme, compared with the existing technology, the technical scheme of the present invention uses hydrogen bond acceptors and hydrogen bond donors to prepare a low eutectic solvent and then deashes the raw coal, and uses the hydrophilicity of the low eutectic solvent to separate the treated coal from the solvent, thereby achieving the purpose of reducing ash and improving the quality of coal. It is low-cost, green and environmentally friendly, and has a simple method and process, achieving good economic and practical benefits. Specific implementation plan

[0018] The technical solutions in the embodiments of the present invention are described clearly and completely below. The described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention. All other embodiments made by other persons without creative development are within the scope of protection of the present invention.

[0019] Example 1

[0020] The present invention provides a method for deashing raw coal using a deep eutectic solvent, comprising the following steps:

[0021] (1) After the raw coal is naturally air-dried for 18 hours, the raw coal is crushed to a particle size of 200 μm to obtain coal powder;

[0022] (2) Proline and p-toluenesulfonic acid are mixed in a molar ratio of 1:2, and after mixing, the mixture is heated to 80° C. and stirred continuously until no solid remains, thereby completing the preparation of a low eutectic solvent;

[0023] (3) The coal powder obtained in step (1) is added to the low eutectic solvent obtained in step (2) in a mass ratio of 1:2, heated to 50°C, and stirred for 3 hours, then filtered while hot and washed with deionized water, and the obtained coal powder is placed in a drying oven at 70°C and dried for 12 hours.

[0024] The ash content before and after the test treatment was tested, and the ash removal rate reached 9.39%.

[0025] Example 2

[0026] The present invention provides a method for deashing raw coal using a deep eutectic solvent, comprising the following steps:

[0027] (1) After the raw coal is naturally air-dried for 18 hours, the raw coal is crushed to a particle size of 200 μm to obtain coal powder;

[0028] (2) acetamide and p-toluenesulfonic acid are mixed in a molar ratio of 1:3, heated to 80° C. after mixing, and stirred continuously until no solid remains, thereby completing the preparation of the low eutectic solvent;

[0029] (3) The coal powder obtained in step (1) is added to the low eutectic solvent obtained in step (2) in a mass ratio of 1:2, heated to 50°C, and stirred for 3 hours, then filtered while hot and washed with deionized water, and the obtained coal powder is placed in a drying oven at 70°C and dried for 12 hours.

[0030] The ash content before and after the test treatment showed that the ash removal rate reached 9.92%.

[0031] Example 3

[0032] The present invention provides a method for deashing raw coal using a deep eutectic solvent, comprising the following steps:

[0033] (1) After the raw coal is naturally air-dried for 18 hours, the raw coal is crushed to a particle size of 200 μm to obtain coal powder;

[0034] (2) acetamide and glutaric acid are mixed in a molar ratio of 1:2, heated to 80° C. after mixing, and stirred continuously until no solid remains, thereby completing the preparation of a low eutectic solvent;

[0035] (3) The coal powder obtained in step (1) is added to the low eutectic solvent obtained in step (2) in a mass ratio of 1:2, heated to 50°C, and stirred for 3 hours, then filtered while hot and washed with deionized water, and the obtained coal powder is placed in a drying oven at 70°C and dried for 12 hours.

[0036] The ash content before and after the test treatment was tested, and the ash removal rate reached 9.00%.

[0037] Example 4

[0038] The present invention provides a method for deashing raw coal using a deep eutectic solvent, comprising the following steps:

[0039] (1) After the raw coal is naturally air-dried for 18 hours, the raw coal is crushed to a particle size of 200 μm to obtain coal powder;

[0040] (2) mixing choline chloride and p-toluenesulfonic acid in a molar ratio of 1:2, heating the mixture to 80° C., and continuously stirring the mixture until no solid remains, thereby completing the preparation of a low eutectic solvent;

[0041] (3) The coal powder obtained in step (1) is added to the low eutectic solvent obtained in step (2) in a mass ratio of 1:2, heated to 50°C, and stirred for 3 hours, then filtered while hot and washed with deionized water, and the obtained coal powder is placed in a drying oven at 70°C and dried for 12 hours.

[0042] The ash content before and after the test treatment was tested, and the ash removal rate reached 11.65%.

[0043] Example 5

[0044] The present invention provides a method for deashing raw coal using a deep eutectic solvent, comprising the following steps:

[0045] (1) After the raw coal is naturally air-dried for 18 hours, the raw coal is crushed to a particle size of 200 μm to obtain coal powder;

[0046] (2) mixing choline chloride and urea in a molar ratio of 1:2, heating to 80° C. after mixing, and continuously stirring until no solid remains, thereby completing the preparation of a low eutectic solvent;

[0047] (3) The coal powder obtained in step (1) is added to the low eutectic solvent obtained in step (2) in a mass ratio of 1:2, heated to 150° C., and stirred for 3 h, then filtered while hot and washed with deionized water, and the obtained coal powder is placed in a drying oven at 70° C. and dried for 12 h.

[0048] The ash content before and after the test treatment showed that the ash removal rate reached 11.09%.

[0049] Example 6

[0050] The present invention provides a method for deashing raw coal using a deep eutectic solvent, comprising the following steps:

[0051] (1) After the raw coal is naturally air-dried for 18 hours, the raw coal is crushed to a particle size of 200 μm to obtain coal powder;

[0052] (2) mixing choline chloride and ethylene glycol in a molar ratio of 1:2, heating the mixture to 80° C., and continuously stirring the mixture until no solid residue remains, thereby completing the preparation of a low eutectic solvent;

[0053] (3) The coal powder obtained in step (1) is added to the low eutectic solvent obtained in step (2) in a mass ratio of 1:2, heated to 150° C., and stirred for 3 h, then filtered while hot and washed with deionized water, and the obtained coal powder is placed in a drying oven at 70° C. and dried for 12 h.

[0054] The ash content before and after the test treatment was tested, and the ash removal rate reached 18.12%.

[0055] Example 7

[0056] The present invention provides a method for deashing raw coal using a deep eutectic solvent, comprising the following steps:

[0057] (1) After the raw coal is naturally air-dried for 18 hours, the raw coal is crushed to a particle size of 200 μm to obtain coal powder;

[0058] (2) mixing choline chloride and p-toluenesulfonic acid in a molar ratio of 1:2, heating the mixture to 80° C., and continuously stirring the mixture until no solid remains, thereby completing the preparation of a low eutectic solvent;

[0059] (3) The coal powder obtained in step (1) is added to the low eutectic solvent obtained in step (2) in a mass ratio of 1:2, heated to 150° C., and stirred for 3 h, then filtered while hot and washed with deionized water, and the obtained coal powder is placed in a drying oven at 70° C. and dried for 12 h.

[0060] The ash content before and after the test treatment showed that the ash removal rate reached 15.97%.

[0061] Example 8

[0062] The present invention provides a method for deashing raw coal using a deep eutectic solvent, comprising the following steps:

[0063] (1) After the raw coal is naturally air-dried for 18 hours, the raw coal is crushed to a particle size of 200 μm to obtain coal powder;

[0064] (2) Tetrabutylammonium chloride and p-toluenesulfonic acid are mixed in a molar ratio of 1:2, and after mixing, the mixture is heated to 80° C. and stirred continuously until no solid remains, thereby completing the preparation of a low eutectic solvent;

[0065] (3) The coal powder obtained in step (1) is added to the low eutectic solvent obtained in step (2) in a mass ratio of 1:2, heated to 150° C., and stirred for 3 h, then filtered while hot and washed with deionized water, and the obtained coal powder is placed in a drying oven at 70° C. and dried for 12 h.

[0066] The ash content before and after the test treatment was tested, and the ash removal rate reached 16.26%.

[0067] Example 9

[0068] The present invention provides a method for deashing raw coal using a deep eutectic solvent, comprising the following steps:

[0069] (1) After the raw coal is naturally air-dried for 18 hours, the raw coal is crushed to a particle size of 200 μm to obtain coal powder;

[0070] (2) mixing choline chloride and propylene glycol in a molar ratio of 1:2, heating the mixture to 80° C., and continuously stirring the mixture until no solid residue remains, thereby completing the preparation of a low eutectic solvent;

[0071] (3) The coal powder obtained in step (1) is added to the low eutectic solvent obtained in step (2) in a mass ratio of 1:2, heated to 150° C., and stirred for 3 h, then filtered while hot and washed with deionized water, and the obtained coal powder is placed in a drying oven at 70° C. and dried for 12 h.

[0072] The ash content before and after the test treatment showed that the ash removal rate reached 17.15%.

[0073] The different conditions and related data of Examples 1-11 refer to Table 1

[0074] Table 1 Conditions and data related to Examples 1-11

[0075] Example Hydrogen bond acceptor (HBA) Hydrogen bond donor (HBD) Mass ratio of HBA to HBD Mass ratio of deep eutectic solvent to coal Reaction temperature Deashing rate Example 1 Proline p-Toluenesulfonic acid 1:2 1:2 50℃ 9.39% Example 2 Acetamide p-Toluenesulfonic acid 1:3 1:2 50℃ 9.92% Example 3 Acetamide Glutaric acid 1:2 1:2 50℃ 9.00% Example 4 Choline chloride p-Toluenesulfonic acid 1:2 1:2 50℃ 11.65% Example 5 Choline chloride Urea 1:2 1:2 150℃ 11.09% Example 6 Choline chloride Ethylene glycol 1:2 1:2 150℃ 18.12% Example 7 Choline chloride p-Toluenesulfonic acid 1:2 1:2 150℃ 15.97% Example 8 Tetrabutylammonium chloride p-Toluenesulfonic acid 1:2 1:2 150℃ 16.26% Example 9 Choline chloride Glycerol 1:2 1:2 150℃ 17.15%

[0076] According to the data in Table 1, it can be seen that by deashing the raw coal according to the treatment method provided by the present invention, 9.00%-18.12% of the ash in the coal can be removed.

[0077] According to the data comparison of Examples 1-4 and Examples 5-9, it can be seen that under high temperature conditions, the low eutectic solvent has a better desulfurization effect on coal.

[0078] Through the test of the above specific implementation scheme, the hydrogen bond acceptor and hydrogen bond donor reagents used in the technical solution of the present invention are relatively common, low-cost, non-toxic and pollution-free, and have a good deashing effect.

[0079] The embodiments in this specification mainly focus on the different selection and mixing ratios of hydrogen bond acceptors and hydrogen bond donors in the low eutectic solvent, as well as the different mixing temperatures of the low eutectic solvent and the raw coal. Due to the different structures and compositions of different coal samples, the deashing effects of the low eutectic solvent on different coals vary greatly. Therefore, the same and similar parts between the embodiments can be referenced to each other.

[0080] It should be understood that the above-disclosed embodiments are merely exemplary. For professionals in the field, the above-disclosed embodiments can be modified, replaced, improved, etc. in various ways, and the general principles defined herein can be applied to other embodiments without departing from the spirit and scope of the present technical solution. Therefore, the above-disclosed embodiments do not limit the present invention, and the scope of limitation should be the widest scope consistent with the principles and innovations disclosed in the present technical solution.

Claims

1. A method for deashing raw coal using a deep eutectic solvent, characterized in that: The following steps are involved: (1) After the raw coal is naturally air-dried for 18 hours, the raw coal is crushed to a particle size of 200 μm to obtain coal powder; (2) mixing a hydrogen bond acceptor and a hydrogen bond donor reagent in a molar ratio of 1:2, heating the mixture to 80° C., and continuously stirring until no solid remains, thereby completing the preparation of a deep eutectic solvent; (3) adding the coal powder obtained in step (1) to the low eutectic solvent obtained in step (2) in a mass ratio of 1:2, heating to 150° C., stirring continuously for 3 h, filtering while hot, washing with deionized water, and drying the obtained coal powder in a drying oven at 70° C. for 12 h; The hydrogen bond acceptor is choline chloride or tetrabutylammonium chloride; When the hydrogen bond acceptor is choline chloride, the hydrogen bond donor is ethylene glycol, glycerol or p-toluenesulfonic acid; When the hydrogen bond acceptor is tetrabutylammonium chloride, the hydrogen bond donor is p-toluenesulfonic acid.