A coal powder binder and its application

Abstract

The present application relates to the technical field of coal dust binders, and specifically discloses a coal dust binder and its application. The coal dust binder disclosed in the present application comprises the following components in parts by weight: 60-80 parts of coal dust, 8-12 parts of sodium hydroxide, 0.4-0.8 parts of cyclodextrin, and 0.06-0.12 parts of polyethyleneimine. The present application also discloses the application of the above-mentioned coal dust binder in the preparation of pellets. The coal dust binder disclosed in the present application can be used to obtain preheated balls and roasted balls with excellent compressive strength, as well as pellets with high total iron grade, thereby improving the quality of the pellets. The coal dust binder also eliminates the step of extracting humic acid from the coal, reducing energy consumption and lowering the production cost of the binder.

Description

Technical Field

[0001] The present application relates to the technical field of coal powder binders, and in particular to a coal powder binder and applications thereof. Background Art

[0002] As a high-quality raw material essential for optimizing blast furnace charge structure, oxidized pellets account for an increasing proportion of blast furnace charge in the steel industry. With growing awareness of environmental protection, people are placing higher demands on the structural optimization of oxidized pellets.

[0003] Currently, inorganic bentonite is the most widely used pellet binder, with the typical addition level ranging from 1.2-3.0wt% and sometimes as high as 3.0-4.0wt%. However, after high-temperature roasting, approximately 90% of the bentonite remains in the pellets, significantly reducing their total iron grade. Furthermore, when the iron grade of the charge decreases by 1%, the coke ratio increases by 1.5%, and the blast furnace output decreases by 2.5%. Therefore, the search for new pellet binders to replace bentonite has become a research hotspot.

[0004] When preparing iron pellets, organic binders can also be added to the pellets. This is because the organic matter contained in these binders can be completely decomposed and burned during the preheating and roasting process, leaving no inorganic residue and improving the total iron grade of the pellets. However, numerous studies have shown that during the preheating phase of this method, the organic binder has already completely decomposed and burned, and the strength formed by the primary crystallization between the mineral particles is insufficient to meet production requirements. This makes the preheated pellets prone to breakage and pulverization, and generates a large amount of dust in the rotary kiln, which is harmful to both operation and the environment. Therefore, organic binders have not been widely used.

[0005] Researchers have developed a sodium humate binder, a composite of organic and inorganic materials. The resulting pellets meet production requirements in all strengths, and the resulting pellets have a higher iron grade than pellets made with the same amount of bentonite. However, sodium humate binder is derived from humic acid extracted from low-rank lignite using alkaline solution, which still requires significant alkali consumption and equipment wear. Compared to bentonite binder, commercially available sodium humate binder costs 500 yuan per ton more. Therefore, further reductions in binder costs are still needed. Summary of the Invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present application provides a coal powder binder and its application.

[0007] In a first aspect, the present application provides a coal powder binder comprising the following components in parts by weight: 60-80 parts of coal powder, 8-12 parts of sodium hydroxide, 0.4-0.8 parts of cyclodextrin, and 0.06-0.12 parts of polyethyleneimine; the coal powder has a humic acid content greater than 40%.

[0008] The present application utilizes coal powder, sodium hydroxide, cyclodextrin, and polyethyleneimine as raw materials, and controls the weight proportion of each raw material within the above-mentioned range, and provides a coal powder binder as a binder for preparing pellets, which can obtain finished pellets with high compressive strength and high total iron grade.

[0009] The cyclodextrin used in this application has a molecular structure that is hydrophobic inside and hydrophilic outside. The hydrophobic pores it contains can be embedded in various organic compounds and have good thermal stability. Many functional groups can be cross-linked on the cyclodextrin molecules to promote the formation of inclusion complexes. The polyethyleneimine used in this application has amino and hydroxyl groups with high adhesion and adsorption properties, which can react with the carboxyl groups in coal to form hydrogen bonds or ionic bonds, and the hydrophobic group vinyl therein can be embedded in the pores of cyclodextrin. The NaOH added in this application can promote the hydroxylation of the surface of the wetted mineral particles. Therefore, using the formula raw materials provided in this application, cyclodextrin can undergo complex polymerization and cross-linking reactions with polyethyleneimine and humic acid in coal powder to generate network structure polymers, and the network structure polymers can be adsorbed on the surface of hydroxylated mineral particles, and further connect and agglomerate the mineral microparticles through bridging, wrapping and winding, thereby greatly improving the strength of the green ball.

[0010] In addition, when the coal powder binder provided by the present application is used to prepare pellets, in the preheating section, on the one hand, due to the good thermal stability of cyclodextrin, it begins to gradually decompose at temperatures above 300°C, and the pyrolysis temperature of low-rank lignite is also around 500-800°C. Therefore, even as the calcination process proceeds, the binder in the present invention begins to gradually pyrolyze in the preheating section, but the undecomposed or incompletely decomposed part still plays a bonding role. On the other hand, after partial pyrolysis and volatilization of the binder, a small amount of holes are left in the pellet structure, which is conducive to the entry of external oxygen, promotes the interfacial reaction during the calcination process, and then is conducive to the initial crystallization of the metal oxide ore particles in the pellets during the preheating process, thereby strengthening the strength of the preheated balls. In addition, the binder used in the present invention contains some inorganic components, which can promote the reaction of FeO, SiO2, and MgO, further improving the compressive strength of the preheated balls and the final calcined balls.

[0011] In the technical solution of the present application, only when coal powder reacts with sodium hydroxide, cyclodextrin and polyethyleneimine in appropriate proportions can a stable network structure polymer be formed, and it can be ensured that the polymer network structure contains a large number of cross-linked group structures, and adsorbed on the surface of iron ore, thereby forming bridges or agglomerations between mineral particles to form an effective organic-inorganic composite binder.

[0012] Preferably, the cyclodextrin is selected from one or more of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.

[0013] Preferably, the cyclodextrin is α-cyclodextrin and γ-cyclodextrin.

[0014] Preferably, the cyclodextrin is α-cyclodextrin and γ-cyclodextrin in a weight ratio of 5:(0.2-1).

[0015] In a specific embodiment, the weight ratio of the α-cyclodextrin to the γ-cyclodextrin can be 5:0.2, 5:0.6, or 5:1.

[0016] In some specific embodiments, the weight ratio of α-cyclodextrin to γ-cyclodextrin can also be 5:(0.2-0.6) or 5:(0.6-1).

[0017] Preferably, the number average molecular weight of the polyethyleneimine is 2000-10000.

[0018] Preferably, the number average molecular weight of the polyethyleneimine is 4000-6000.

[0019] Preferably, the coal powder is coal powder with a humic acid content greater than 45%.

[0020] Furthermore, the coal powder is coal powder with a humic acid content greater than 60%.

[0021] Furthermore, the coal powder is lignite or weathered coal.

[0022] Through experimental analysis, it can be seen that the present application further improves the compressive strength of the pellets by selecting α-cyclodextrin and γ-cyclodextrin in the above weight ratio as cyclodextrin, and screening the above number average molecular weight of polyethyleneimine and the above humic acid content of coal powder raw materials to prepare the coal powder binder.

[0023] In a second aspect, the present application provides the use of the above-mentioned coal powder binder in the preparation of pellets.

[0024] In a fourth aspect, the present application provides a method for preparing the above-mentioned iron pellets, which specifically comprises the following steps:

[0025] The coal powder binder is added to the metal oxide ore powder raw material, water is added to perform moist grinding pretreatment, and then the pellets are formed, dried, preheated and roasted to obtain the pellets.

[0026] Preferably, the weight ratio of the coal powder binder to the metal oxide ore powder raw material is (0.5-1.0):100.

[0027] In summary, the technical solution of this application has the following effects:

[0028] The present application uses coal powder, sodium hydroxide, cyclodextrin, and polyethyleneimine as raw materials and controls the ratio of each raw material to provide a coal powder binder as a binder for preparing pellets, which can obtain finished pellets with high compressive strength and high total iron grade.

[0029] The cyclodextrin provided by the present application can undergo complex polymerization and cross-linking reactions with polyethyleneimine and coal powder to generate a network structure polymer, and promote the hydroxylation of the surface of the mineral particles through sodium hydroxide, so that the network polymer is adsorbed on the surface of the mineral particles, and further connects and agglomerates the mineral particles through bridging, wrapping and winding to improve the strength of the green ball. Furthermore, the excellent thermal stability of the binder provided by the present invention and the pores formed after pyrolysis can improve the strength of the preheated pellets, and the inorganic components contained therein promote the primary crystallization and recrystallization behavior between the mineral particles in the pellets, thereby improving the compressive strength of the finished iron pellets.

[0030] Compared with using bentonite as a pellet binder, the organic components of the coal powder mixed binder provided by this application decompose and burn during the preheating and roasting process of the pellets, and the inorganic matter remaining in the pellets is less than that of the same amount of bentonite added, thereby improving the TFe grade of the finished pellets. Compared with organic binders, since the inorganic components in the mixed binder can react with other oxidized minerals during the preheating and roasting process of the pellets, they promote the primary crystallization and recrystallization behavior between the mineral particles in the pellets, and the strength of the finished pellets is higher than that of organic binders. Compared with the sodium humate binder prepared by NaOH extraction, the mixed binder omits the steps of extracting humic acid from coal, filtering and drying the sodium humate mixture, reducing energy consumption and further reducing the binder production cost. DETAILED DESCRIPTION

[0031] The present application is further described in detail below in conjunction with examples, comparative examples and performance testing experiments. These examples should not be construed as limiting the scope of protection claimed in this application.

[0032] The α-cyclodextrin used in this application was purchased from Sigma-Aldrich, product number C4642; β-cyclodextrin was purchased from Sigma-Aldrich, product number C4805; γ-cyclodextrin was purchased from Sigma-Aldrich, product number C4892; polyethyleneimine (linear polyethyleneimine with a number average molecular weight of 2100, linear polyethyleneimine with a number average molecular weight of 5000, and linear polyethyleneimine with a number average molecular weight of 10000) was purchased from Sigma-Aldrich.

[0033] Preparation Example

[0034] Preparation Examples 1-9

[0035] Preparation Examples 1-9 each provide a coal powder binder.

[0036] The difference between the coal powder binders in the above preparation examples is that the addition amount of each component is different, as shown in Table 1.

[0037] The components of the coal powder binder in the above preparation example are: the coal powder is lignite with a humic acid content of 67.6 wt% (purchased from Shanxi), the cyclodextrin is α-cyclodextrin, and the polyethyleneimine is linear polyethyleneimine with a number average molecular weight of 5000.

[0038] The preparation method of the coal powder binder in the above preparation example is specifically as follows:

[0039] According to Table 1, the corresponding weights of the various component materials were weighed respectively, and the coal powder and sodium hydroxide particles were ground to a particle size of less than 200 meshes, and then the various materials were mixed evenly to obtain the coal powder binder.

[0040] Table 1 Addition amount of each component in Preparation Examples 1-9

[0041]

[0042] Preparation Example 10

[0043] This preparation example provides a coal powder binder.

[0044] The difference between this preparation example and preparation example 2 is that the cyclodextrin is β-cyclodextrin. The other raw materials used in this preparation example are the same as those in preparation example 2.

[0045] Preparation Example 11

[0046] This preparation example provides a coal powder binder.

[0047] The difference between this preparation example and preparation example 2 is that the cyclodextrin is γ-cyclodextrin. The other raw materials used in this preparation example are the same as those in preparation example 2.

[0048] Preparation Example 12

[0049] This preparation example provides a coal powder binder.

[0050] The difference between this preparation example and preparation example 2 is that the cyclodextrin is α-cyclodextrin and β-cyclodextrin in a weight ratio of 5:0.6. The other raw materials used in this preparation example are the same as those in preparation example 2.

[0051] Preparation Example 13

[0052] This preparation example provides a coal powder binder.

[0053] The difference between this preparation example and preparation example 2 is that the cyclodextrin is β-cyclodextrin and γ-cyclodextrin in a weight ratio of 5:0.6. The other raw materials used in this preparation example are the same as those in preparation example 2.

[0054] Preparation Example 14

[0055] This preparation example provides a coal powder binder.

[0056] The difference between this preparation example and preparation example 2 is that the cyclodextrin is α-cyclodextrin and γ-cyclodextrin in a weight ratio of 5:0.1. The other raw materials used in this preparation example are the same as those in preparation example 2.

[0057] Preparation Example 15

[0058] This preparation example provides a coal powder binder.

[0059] The difference between this preparation example and preparation example 2 is that the cyclodextrin is α-cyclodextrin and γ-cyclodextrin in a weight ratio of 5:0.2. The other raw materials used in this preparation example are the same as those in preparation example 2.

[0060] Preparation Example 16

[0061] This preparation example provides a coal powder binder.

[0062] The difference between this preparation example and preparation example 2 is that the cyclodextrin is α-cyclodextrin and γ-cyclodextrin in a weight ratio of 5:0.6. The other raw materials used in this preparation example are the same as those in preparation example 2.

[0063] Preparation Example 17

[0064] This preparation example provides a coal powder binder.

[0065] The difference between this preparation example and preparation example 2 is that the cyclodextrin is α-cyclodextrin and γ-cyclodextrin in a weight ratio of 5:1. The other raw materials used in this preparation example are the same as those in preparation example 2.

[0066] Preparation Example 18

[0067] This preparation example provides a coal powder binder.

[0068] The difference between this preparation example and preparation example 2 is that the cyclodextrin is α-cyclodextrin and γ-cyclodextrin in a weight ratio of 5:1.2. The other raw materials used in this preparation example are the same as those in preparation example 2.

[0069] Preparation Example 19

[0070] This preparation example provides a coal powder binder.

[0071] The difference between this preparation example and preparation example 2 is that the polyethyleneimine is a linear polyethyleneimine with a number average molecular weight of 2100. The other raw materials used in this preparation example are the same as those in preparation example 2.

[0072] Preparation Example 20

[0073] This preparation example provides a coal powder binder.

[0074] The difference between this preparation example and preparation example 2 is that the polyethyleneimine is a linear polyethyleneimine with a number average molecular weight of 10000. The other raw materials used in this preparation example are the same as those in preparation example 2.

[0075] Preparation Example 21

[0076] This preparation example provides a coal powder binder.

[0077] The difference between this preparation example and preparation example 2 is that the coal powder is lignite with a humic acid content of 45.2 wt% (purchased from Shanxi). The other raw materials used in this preparation example are the same as those in preparation example 2.

[0078] Preparation Example 22

[0079] This preparation example provides a coal powder binder.

[0080] The difference between this preparation example and preparation example 2 is that the coal powder is lignite with a humic acid content of 42.7 wt% (purchased from Shanxi). The other raw materials used in this preparation example are the same as those in preparation example 2.

[0081] Preparation Example 23

[0082] This preparation example provides a coal powder binder.

[0083] The difference between this preparation example and preparation example 2 is that the coal powder binder does not contain cyclodextrin. The other raw materials used in this preparation example are the same as those in preparation example 2.

[0084] Preparation Example 24

[0085] This preparation example provides a coal powder binder.

[0086] The difference between this preparation example and preparation example 2 is that the coal powder binder does not contain polyethyleneimine. The other raw materials used in this preparation example are the same as those in preparation example 2.

[0087] Preparation Example 25

[0088] This preparation example provides a coal powder binder.

[0089] The difference between this preparation example and preparation example 2 is that maltodextrin (purchased from Sigma-Aldrich, product number 419680) is used instead of cyclodextrin in the coal powder binder. The other raw materials used in this preparation example are the same as those in preparation example 2.

[0090] Preparation Example 26

[0091] This preparation example provides a coal powder binder.

[0092] The difference between this preparation example and Preparation Example 2 is that polyamide (purchased from Sigma-Aldrich, product number 02395) is used instead of polyethyleneimine in the powder binder. The other raw materials used in this preparation example are the same as those in Preparation Example 2.

[0093] Example

[0094] Examples 1-20

[0095] Examples 1-20 each provide an iron pellet.

[0096] The difference between the iron pellets in the above embodiments is that the sources of the coal powder binder are different, as shown in Table 2.

[0097] The preparation method of iron pellets in the above embodiment comprises the following specific steps:

[0098] Raw material mixing and milling pretreatment: Take 5kg of magnetite concentrate (magnetite concentrate with a particle size less than 200 mesh accounts for 91.7%, and the raw material moisture content is 3%), add 36g of coal powder binder into it, mix the two and add water to the mixture until the moisture content is 7%, and then use a mill for milling pretreatment for 5 minutes to obtain the raw material for pelletizing.

[0099] Preparation of iron ore pellets: The above-mentioned pelletizing raw materials that have been pre-treated by grinding are pelletized using a disc pelletizing machine. During the pelletizing process, the disc speed is maintained at 18r / min, the disc inclination angle is 45°, the pelletizing time is fixed at 12min, and the moisture content of the raw balls is controlled to be about 8%. Finally, qualified raw balls with a diameter of 10-12mm are obtained; the raw balls are then dried to constant weight at 100°C, preheated (preheating temperature 950°C, preheating time 10min), and roasted (roasting temperature 1250°C, roasting time 10min) to obtain iron ore pellets.

[0100] Table 2 Sources of coal powder binder in Examples 1-20

[0101] Example Source of pulverized coal binder Example Source of pulverized coal binder 1 Preparation Example 1 11 Preparation Example 13 2 Preparation Example 2 12 Preparation Example 14 3 Preparation Example 3 13 Preparation Example 15 4 Preparation Example 4 14 Preparation Example 16 5 Preparation Example 5 15 Preparation Example 17 6 Preparation Example 6 16 Preparation Example 18 7 Preparation Example 7 17 Preparation Example 19 8 Preparation Example 10 18 Preparation Example 20 9 Preparation Example 11 19 Preparation Example 21 10 Preparation Example 12 20 Preparation Example 22

[0102] Example 21

[0103] This embodiment provides an iron pellet.

[0104] The difference between this embodiment and embodiment 2 is that the raw material of the metal oxide ore powder is 5 kg of hematite concentrate powder (the hematite concentrate powder with a particle size less than 200 mesh accounts for 94.9%).

[0105] Example 22

[0106] This embodiment provides an iron pellet.

[0107] The difference between this embodiment and embodiment 2 is that the raw material of the metal oxide ore powder is 5 kg of specularite powder (the specularite powder with a particle size less than 200 mesh accounts for 96.9%).

[0108] Comparative Example

[0109] Comparative Example 1

[0110] This comparative example provides an iron pellet.

[0111] In this comparative example, CMC was used as an organic binder to prepare iron pellets. The specific method was as follows:

[0112] Raw material mixing and milling pretreatment: Take 5kg of magnetite concentrate (magnetite concentrate with a particle size of less than 200 mesh accounts for 91.7%, and the raw material moisture content is 3%), add 25g of CMC binder thereto, mix the two and add water to the mixture until the moisture content is 7%, and then use a mill for milling pretreatment for 5 minutes to obtain the raw material for pelletizing.

[0113] Preparation of iron ore pellets: The above-mentioned pelletizing raw materials that have been pre-treated by grinding are pelletized using a disc pelletizing machine. During the pelletizing process, the disc speed is maintained at 18r / min and the disc inclination angle is 45°; the pelletizing time is fixed at 12min, and the moisture content of the raw balls is controlled to be about 8%, and finally qualified raw balls with a diameter of 10-12mm are obtained; the raw balls are then dried to constant weight at 100°C, and after preheating (preheating temperature 950°C, preheating time 10min) and roasting (roasting temperature 1250°C, roasting time 10min), iron ore pellets are obtained.

[0114] Comparative Example 2

[0115] This comparative example provides an iron pellet.

[0116] In this comparative example, bentonite is used as an inorganic binder to prepare iron pellets. The specific method is as follows:

[0117] Raw material mixing and milling pretreatment: Take 5kg of magnetite concentrate (magnetite concentrate with a particle size less than 200 mesh accounts for 91.7%, and the raw material moisture content is 3%), add 36g of bentonite thereto, mix the two and add water to the mixture until the moisture content is 7%, and then use a mill for milling pretreatment for 5 minutes to obtain the raw material for pelletizing.

[0118] Preparation of iron ore pellets: The above-mentioned pelletizing raw materials that have been pre-treated by grinding are pelletized using a disc pelletizing machine. During the pelletizing process, the disc speed is maintained at 18r / min and the disc inclination angle is 45°; the pelletizing time is fixed at 12min, and the moisture content of the raw balls is controlled to be about 8%, and finally qualified raw balls with a diameter of 10-12mm are obtained; the raw balls are then dried to constant weight at 100°C, and after preheating (preheating temperature 950°C, preheating time 10min) and roasting (roasting temperature 1250°C, roasting time 10min), iron ore pellets are obtained.

[0119] Comparative Examples 3-8

[0120] Comparative Examples 3-8 each provide an iron pellet.

[0121] The difference between the comparative example and Example 2 is that the sources of the coal powder binder are different, as shown in Table 3.

[0122] Table 3 Sources of coal powder binder in comparative examples 3-8

[0123] Comparative Example Source of pulverized coal binder Comparative Example Source of pulverized coal binder 3 Preparation Example 8 6 Preparation Example 24 4 Preparation Example 9 7 Preparation Example 25 5 Preparation Example 23 8 Preparation Example 26

[0124] Drop Strength: The drop strength of the green balls in Examples 1-22 and Comparative Examples 1-8 was tested using the following method. The specific steps are as follows: Select green balls of the same diameter (10-15 mm, based on the average qualified ball diameter d ± 0.5 mm) and allow them to freely drop from a height of 0.5 m onto a 10 mm thick steel plate. Repeat the process until the balls exhibit noticeable cracks or breakage. The number of times they fall until they break is the drop strength, with the average number of drops for 10 balls serving as the drop strength indicator.

[0125] Compressive strength: The compressive strength of the green balls and iron pellets in Examples 1-22 and Comparative Examples 1-8 was tested with reference to the determination method of GB / T14201-1993.

[0126] TFe grade: The TFe grade of the iron pellets in Examples 1-22 and Comparative Examples 1-8 was tested with reference to the determination method of GB / T 6730.6-2016.

[0127] Test results: as shown in Table 4.

[0128] Table 4 Performance test results of green balls and iron pellets in Examples 1-22 and Comparative Examples 1-8

[0129]

[0130]

[0131] Combined with Table 4, according to the test results of Examples 1-22 and Comparative Examples 1-8, it can be seen that the present application uses 60-80 parts of coal powder, 8-12 parts of sodium hydroxide, 0.4-0.8 parts of cyclodextrin, and 0.06-0.12 parts of polyethyleneimine as a binder for preparing oxidized pellets, and obtains finished pellets with a compressive strength of ≥2702N / piece and a total iron grade of ≥62.5%.

[0132] By comparing the test results of Example 2 with those of Comparative Examples 4-7, it can be seen that when cyclodextrin and polyethyleneimine are not added to the coal dust binder, or when other dextrins are used instead of cyclodextrin and other polyamines are used instead of polyethyleneimine, the compressive strength of the prepared pellets is poor. Therefore, the present application selects cyclodextrin, polyethyleneimine, coal dust, and sodium hydroxide as components of the coal dust binder. Further, by comparing the test results of Examples 1-7 with those of Comparative Examples 1-2, the present application can significantly improve the compressive strength of the pellets by controlling the addition amount of each component to 60-80 parts of coal dust, 8-12 parts of sodium hydroxide, 0.4-0.8 parts of cyclodextrin, and 0.06-0.12 parts of polyethyleneimine.

[0133] By comparing the test results of Examples 2, 8-16, compared with selecting one of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin as cyclodextrin, or selecting α-cyclodextrin and β-cyclodextrin as cyclodextrin, or selecting β-cyclodextrin and γ-cyclodextrin as cyclodextrin, the present application selects α-cyclodextrin and γ-cyclodextrin as cyclodextrin, which further improves the compressive strength of the pellets.

[0134] Furthermore, by comparing the test results of Examples 2 and 17-20, the present application further improves the compressive strength of the pellets by selecting polyethyleneimine with a number average molecular weight of 4000-6000 and controlling the coal powder to have a humic acid content greater than 45%.

[0135] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A coal powder binder, characterized in that: The invention comprises the following components in parts by weight: 60-80 parts of coal powder, 8-12 parts of sodium hydroxide, 0.4-0.8 parts of cyclodextrin, and 0.06-0.12 parts of polyethyleneimine; wherein the coal powder has a humic acid content greater than 45%; The number average molecular weight of the polyethyleneimine is 4000-6000.

2. The pulverized coal binder according to claim 1, characterized in that The cyclodextrin is selected from one or more of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.

3. The pulverized coal binder according to claim 2, characterized in that: The cyclodextrins are α-cyclodextrin and γ-cyclodextrin.

4. The pulverized coal binder according to claim 3, characterized in that: The cyclodextrins are α-cyclodextrin and γ-cyclodextrin in a weight ratio of 5:(0.2-1).

5. The method for preparing the coal powder binder according to claim 1, wherein: The pulverized coal has a humic acid content greater than 50%.

6. Use of the coal powder binder according to any one of claims 1 to 5 in the preparation of pellets.

7. A method for preparing pellets, characterized in that: The method is prepared using the coal powder binder according to any one of claims 1 to 5, and specifically comprises the following steps: The coal powder binder is added to the metal oxide ore powder raw material, water is added to carry out pre-grinding treatment, and then the pellets are formed, dried, preheated and roasted to obtain the pellets.

8. The method for preparing pellets according to claim 7, characterized in that: The weight ratio of the coal powder binder to the metal oxide ore powder raw material is (0.5-1.0):100.

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