Method for preparing humic acid by microbial decomposition and conversion of coal gangue and product and application thereof

Abstract

The present application provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue, and products and applications thereof. The method comprises the following steps: mixing coal gangue, microbial strains and water to obtain a mixed system, and allowing the microbial strains to act to obtain humic acid. The microbial strains include mineral bioweathering microbial strains for decomposing inorganic minerals wrapped in an organic outer layer, and microbial strains for transforming organic matter in coal gangue into humic acid. The method can significantly increase the content of humic acid in coal gangue, and can be applied in the fields of farmland, forest land, grassland soil improvement, desertification control and the like.

Description

Technical Field

[0001] This invention belongs to the field of microbial technology, specifically relating to a method for preparing humic acid by microbial decomposition and transformation of coal gangue, as well as its products and applications. Background Technology

[0002] Coal gangue is a type of dark gray rock with a low carbon content and harder than coal, which is associated with coal seams during coal formation. As a solid waste discharged during coal mining, its annual discharge exceeds 700 million tons. Currently, coal gangue suffers from low utilization; only a small portion is used for brick making, cement calcination, power generation, road paving, or backfilling, while the majority is stored in open pits. However, the long-term storage of large quantities of coal gangue not only occupies a significant amount of land but also poses a risk of landslides, creating a major safety hazard for nearby residents. Furthermore, coal gangue is prone to undergoing a series of physicochemical changes during long-term storage, leading to the release of toxic and harmful substances that can seep into the surrounding soil or water bodies, harming the ecological environment and human health. Therefore, strengthening the resource utilization of coal gangue is urgently needed.

[0003] Humic acid, as a mixture of various organic acids with different molecular weights and types, can serve as an excellent soil conditioner and plant fertilizer in agriculture and forestry. It improves soil quality, enhances fertilizer efficiency, strengthens plant resistance, and reduces heavy metal pollution in the soil. Coal gangue typically contains 5-30% organic matter and a small amount of humic acid. While the organic matter, as the main raw material for humic acid production, is converted to humic acid at an extremely slow rate under natural conditions, appropriate processing techniques can significantly accelerate the conversion of organic matter in coal gangue into humic acid, potentially transforming coal gangue solid waste into a humic acid fertilizer.

[0004] Currently, there are two main methods for preparing humic acid: chemical methods and microbial methods. The most widely used chemical method utilizes lignite for humic acid production. For example, CN111607407A discloses a lignite-derived soil conditioner and its preparation method. In this method, the lignite raw material is crushed and fed into a hot blast furnace at a temperature of 500-1300℃ with an oxygen content of less than 5%. The humic acid content is increased through anoxic high-temperature pyrolysis. This method uses readily available raw materials and produces a rapid increase in humic acid content, but the preparation process is costly. CN110372881A discloses a method for preparing humic acid from vegetable waste through wet hydrolysis. This method involves crushing vegetable waste, adding a chemical catalyst, pre-soaking, and wet hydrolysis to obtain humified material. Subsequently, alkaline materials are added for extraction, and acidic substances are precipitated to obtain humic acid. This method has a wide range of applicable raw materials and a high product yield, but the preparation process requires a large amount of chemical reagents, which can cause environmental pollution and safety hazards.

[0005] Microbial methods are also a common approach for humic acid preparation. For example, CN110526766A discloses a method for extracting fulvic acid from corn stalks to process organic fertilizer. This organic fertilizer comprises 98% humic acid organic fertilizer, 1.5% special functional bacteria, and 0.5% activator. Using corn stalks as raw material for humic acid production is readily available and inexpensive. The addition of special functional bacteria can significantly increase humic acid yield. Furthermore, using humic acid and poultry manure to prepare organic fertilizer effectively utilizes agricultural waste, improves resource utilization, and greatly reduces production and usage costs.

[0006] Based on the above research, it can be seen that both chemical and microbial methods can effectively prepare humic acid. Among them, the microbial method is more widely used due to its advantages of being environmentally friendly and having low economic cost. However, there are currently no reports on the preparation of humic acid from coal gangue. Therefore, finding a suitable microbial transformation method for coal gangue to increase its humic acid content is of great significance for preparing it into humic acid fertilizer for use in the remediation of mines, saline-alkali lands, desertified soils, and farmland improvement, and is crucial for solving the problem of large-scale stockpiling of coal gangue. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing humic acid from coal gangue through microbial decomposition and transformation, as well as the product and its applications. The method effectively increases the humic acid content in coal gangue, and the obtained humic acid is mainly composed of fulvic acid. Because fulvic acid has a smaller molecular weight, lower aromaticity, and higher activity compared to other humic acids, it is more easily decomposed and utilized, making it the best core component of humic acid.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue, the method comprising the following steps:

[0010] Coal gangue, microbial strains, and water are mixed to obtain a mixed system. The microbial strains then act to produce humic acid.

[0011] The above-mentioned method for preparing humic acid by microbial decomposition and transformation of coal gangue can improve the conversion effect of organic matter in coal gangue and increase the humic acid content in coal gangue by using microbial strains.

[0012] In this invention, the mass ratio of coal gangue to microbial inoculum is 1000:(0.1-1), for example, it can be 1000:0.1, 1000:0.2, 1000:0.3, 1000:0.4, 1000:0.5, 1000:0.6, 1000:0.7, 1000:0.8, 1000:0.9 or 1000:1, etc., but is not limited to the listed values, other values ​​not listed in this range are also applicable.

[0013] Preferably, the mass fraction of water in the mixed system is 10-60%, for example, it can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55% or 60%, etc., but is not limited to the listed values, and other values ​​not listed in this range are also applicable.

[0014] In this invention, the microbial strains include microbial strains that decompose inorganic minerals wrapped around organic matter through bioweathering and microbial strains that convert organic matter in coal gangue into humic acid.

[0015] This invention combines microbial strains for mineral bioweathering with microbial strains that convert organic matter in coal gangue into humic acid, thereby synergistically improving the conversion effect of organic matter in coal gangue and increasing the humic acid content in coal gangue.

[0016] Preferably, the microbial strains for mineral bioweathering include microbial strains for pyrite bioweathering and / or microbial strains for aluminosilicate mineral bioweathering.

[0017] The microbial strains for mineral bioweathering can dissociate inorganic minerals in coal gangue, fully exposing organic matter that is intercalated with or encapsulated by inorganic minerals. When used in combination with microbial strains that convert organic matter in coal gangue into humic acid, the conversion effect of organic matter in coal gangue is synergistically improved. Furthermore, the use of microbial strains for pyrite bioweathering and microbial strains for aluminosilicate mineral bioweathering further enhances the effect of exposing organic matter, which is conducive to promoting its conversion into humic acid.

[0018] Preferably, the microbial strains used in the bioweathering of pyrite include desulfurizing bacteria.

[0019] Preferably, the desulfurizing bacteria include any one or a combination of at least two of Thiobacillus, Thiorhynchus, or Sulfophyllum. The combination of at least two can be a combination of Thiobacillus and Thiorhynchus or a combination of Thiorhynchus and Sulfophyllum, etc. Any other combination is acceptable and will not be described in detail here. Thiobacillus is preferred.

[0020] The present invention preferably uses Thiobacillus because this bacterium is relatively common in soil and water, and can better adapt to the soil environment and survive after entering the soil with coal gangue.

[0021] Preferably, the microbial strains used for the bioweathering of aluminosilicate minerals include silicate bacteria.

[0022] Preferably, the silicate bacteria include Bacillus mucilaginosus and / or Bacillus amyloliquefaciens, with Bacillus mucilaginosus being the most preferred.

[0023] The present invention preferably uses Bacillus mucilaginosus because this bacterium not only decomposes potassium, silicon and phosphorus in minerals, but also has nitrogen-fixing properties. At the same time, it can produce organic acids, amino acids, polysaccharides and hormones during its growth and reproduction, which are beneficial to plant absorption and utilization.

[0024] Preferably, the microbial strains that convert organic matter in coal gangue into humic acid include any one or a combination of at least two of Bacillus subtilis, Bacillus licheniformis, Bacillus laterosporus, phosphate-solubilizing bacteria, potassium-solubilizing bacteria, or nitrogen-fixing bacteria. The combination of at least two strains can be a combination of Bacillus subtilis and Bacillus licheniformis, or a combination of Bacillus licheniformis and Bacillus laterosporus, etc. Any other combination is acceptable and will not be described in detail here. The preferred combination is a combination of Bacillus subtilis, Bacillus licheniformis, and Bacillus laterosporus.

[0025] The aforementioned combination of specific microbial strains that convert organic matter in coal gangue into humic acid can improve the degradation and conversion effect of organic matter in coal gangue.

[0026] Preferably, nutrients may also be added to the mixture, including nitrogen fertilizer and / or phosphorus fertilizer.

[0027] Preferably, the mass ratio of carbon, nitrogen and phosphorus in the mixed system is (60-300):(7-10):1.

[0028] The range (60-300) can be 60, 80, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280 or 300, but is not limited to the listed values. Other values ​​not listed in this range are also applicable.

[0029] The (7-10) can be 7, 7.5, 8, 8.5, 9, 9.5 or 10, etc., but is not limited to the listed values. Other values ​​not listed in this range are also applicable.

[0030] The addition of the above nutrients can meet the needs of microbial strains during the degradation process, enabling them to complete the transformation of organic matter.

[0031] In this invention, the coal gangue needs to be crushed and sieved before mixing.

[0032] Preferably, the mesh size of the sieve is 20-200 mesh, for example, it can be 20 mesh, 40 mesh, 60 mesh, 80 mesh, 100 mesh, 120 mesh, 140 mesh, 150 mesh, 160 mesh, 180 mesh or 200 mesh, etc., but is not limited to the listed values, other values ​​not listed in this range are also applicable.

[0033] Preferably, the duration of action of the microbial strain is 10-90 days, for example, it can be 10 days, 12 days, 15 days, 18 days, 20 days, 25 days, 30 days, 35 days, 40 days, 45 days, 50 days, 55 days, 60 days, 65 days, 70 days, 75 days, 80 days, 85 days or 90 days, etc., but is not limited to the listed values, other values ​​not listed in this range are also applicable.

[0034] Preferably, the microbial strains are used under conditions of 20-60°C.

[0035] The range of 20-60℃ can be 20℃, 22℃, 24℃, 25℃, 26℃, 28℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, or 60℃, but is not limited to the listed values. Other values ​​not listed within this range also apply.

[0036] Preferably, the microbial strains need to be turned over during operation, and the frequency of turning over is once every 2-10 days. For example, the turning interval can be 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days or 10 days, etc., but it is not limited to the listed values. Other values ​​not listed in this range are also applicable.

[0037] Secondly, the present invention provides an application of the method for preparing humic acid by microbial decomposition and transformation of coal gangue as described in the first aspect in the treatment of coal-based solid waste.

[0038] Thirdly, the present invention provides a humic acid prepared by the method for preparing humic acid by microbial decomposition and transformation of coal gangue as described in the first aspect.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] This invention provides a method for preparing humic acid from coal gangue through microbial decomposition and transformation. By using a combination of microbial strains for mineral bioweathering and microbial strains for converting organic matter in coal gangue into humic acid, the conversion effect of organic matter in coal gangue can be synergistically improved, increasing the humic acid content in coal gangue. When combined with nutrients, the conversion effect of organic matter in coal gangue can be further enhanced. This method can be applied to fields such as farmland, forest land, grassland soil improvement, and desertification control, realizing the high-value utilization of coal gangue and opening up a new avenue for the treatment of coal gangue solid waste. Detailed Implementation

[0041] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0042] The sources of the raw materials for the corresponding materials in the following examples and comparative examples are as follows:

[0043] The coal gangue was sourced from a coal mine in Yulin, Shaanxi Province. Bacillus subtilis was purchased from Beina Biotechnology (model BNCC188062); Bacillus licheniformis was purchased from Beina Biotechnology (model BNCC189067); Bacillus laterosporus was purchased from Beina Biotechnology (model BNCC175768); Thiobacillus strain was purchased from Beina Biotechnology (model BNCC173437); and Bacillus mucilaginosus strain was purchased from Beina Biotechnology (model BNCC335819). All other materials and raw materials, unless otherwise specified, were commercially available.

[0044] Example 1

[0045] This embodiment provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue, the specific steps of which are as follows:

[0046] (1) Crush the coal gangue through a 100-mesh sieve, take 1000 parts of the sieved coal gangue, add 0.2 parts of Bacillus subtilis, 0.2 parts of Bacillus licheniformis, 0.2 parts of Bacillus laterosporus, 0.2 parts of Thiobacillus, and 0.2 parts of Bacillus mucilaginosus to it, mix them evenly to obtain a mixture;

[0047] (2) Add nitrogen fertilizer, phosphorus fertilizer and water to the mixture in step (1) so that the mass ratio of C:N:P is 150:8.5:1 and the water content is 30%;

[0048] (3) Microbial strains were used at 30℃ to degrade the organic matter in coal gangue for 40 days, with the mixture being turned over on average every 2 days.

[0049] Example 2

[0050] This embodiment provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue, the specific steps of which are as follows:

[0051] (1) Crush the coal gangue through a 20-mesh sieve, take 1000 parts by weight of the sieved coal gangue, add 0.03 parts of Bacillus subtilis, 0.1 parts of Bacillus licheniformis, 0.2 parts of Bacillus laterosporus, 0.1 parts of Thiobacillus, and 0.09 parts of Bacillus mucilaginosus to it, mix them evenly to obtain a mixture;

[0052] (2) Add nitrogen fertilizer, phosphorus fertilizer and water to the mixture in step (1) so that the mass ratio of C:N:P is 60:7:1 and the water content is 10%.

[0053] (3) Microbial strains were used at 20℃ to degrade the organic matter in coal gangue for 80 days, and the mixture was stirred every 5 days on average.

[0054] Example 3

[0055] This embodiment provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue, the specific steps of which are as follows:

[0056] (1) Crush the coal gangue through a 200-mesh sieve, take 1000 parts by weight of the sieved coal gangue, add 0.1 parts of Bacillus subtilis, 0.15 parts of Bacillus licheniformis, 0.2 parts of Bacillus laterosporus, 0.15 parts of Thiobacillus thiobacillus, and 0.3 parts of Bacillus mucilaginosus to it, mix them evenly to obtain a mixture;

[0057] (2) Add nitrogen fertilizer, phosphorus fertilizer and water to the mixture in step (1) so that the mass ratio of C:N:P is 60:7:1 and the water content is 10%.

[0058] (3) Microbial strains were used at 20℃ to degrade the organic matter in coal gangue for 20 days, and the mixture was stirred every 10 days on average.

[0059] Example 4

[0060] This embodiment provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue. Compared with Example 1, step (1) does not include Bacillus licheniformis, and the reduced weight fraction is equally distributed to Bacillus subtilis and Bacillus laterosporus. The remaining parameters and steps are consistent with those of Example 1.

[0061] Example 5

[0062] This embodiment provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue. Compared with Example 1, step (1) does not include Bacillus subtilis, and its reduced weight is equally distributed to Bacillus licheniformis and Bacillus laterosporus. The remaining parameters and steps are consistent with Example 1.

[0063] Example 6

[0064] This embodiment provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue. Compared with Example 1, step (1) does not include Bacillus laterosporus, and its reduced weight is equally distributed to Bacillus licheniformis and Bacillus subtilis. The remaining parameters and steps are consistent with those of Example 1.

[0065] Example 7

[0066] This embodiment provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue. Compared with Example 1, step (1) does not include Bacillus laterosporus and Bacillus licheniformis. The reduced weight fraction is made up by Bacillus subtilis. The remaining parameters and steps are consistent with those of Example 1.

[0067] Example 8

[0068] This embodiment provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue. Compared with Example 1, step (1) does not include Bacillus laterosporus and Bacillus subtilis. The reduced weight fraction is made up by Bacillus licheniformis. The remaining parameters and steps are consistent with Example 1.

[0069] Example 9

[0070] This embodiment provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue. Compared with Example 1, step (1) does not include Bacillus licheniformis and Bacillus subtilis. The reduced weight fraction is made up by Bacillus laterosporus. The remaining parameters and steps are consistent with Example 1.

[0071] Example 10

[0072] This embodiment provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue. Compared with Example 1, step (1) does not include Bacillus licheniformis, Bacillus laterosporus and Bacillus subtilis. The reduced weight fractions are evenly distributed to Thiobacillus and Bacillus mucilaginosus. The remaining parameters and steps are consistent with Example 1.

[0073] Example 11

[0074] This embodiment provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue. Compared with Example 1, step (1) does not include Thiobacillus and Bacillus mucilaginosus. The reduced weight fractions are evenly distributed to Bacillus licheniformis, Bacillus laterosporus, and Bacillus subtilis. The remaining parameters and steps are consistent with those of Example 1.

[0075] Example 12

[0076] This embodiment provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue. Compared with Example 1, step (1) does not include Thiobacillus, and the reduced weight fraction is made up by Bacillus mucilaginosus. The remaining parameters and steps are consistent with Example 1.

[0077] Example 13

[0078] This embodiment provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue. Compared with Example 1, step (1) does not include Bacillus mucilaginosus, and the reduced weight fraction is made up by Thiobacillus. The remaining parameters and steps are consistent with Example 1.

[0079] Example 14

[0080] This embodiment provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue. Compared with Example 1, the degradation time in step (3) is 50 days, and the other parameters and steps are consistent with Example 1.

[0081] Example 15

[0082] This embodiment provides a method for preparing humic acid by microbial decomposition and transformation of coal gangue, the specific method including the following steps:

[0083] (1) Crush the coal gangue through a 100-mesh sieve, take 1000 parts by weight of the sieved coal gangue, add 0.2 parts by weight of Bacillus subtilis, 0.2 parts by weight of Bacillus licheniformis, 0.2 parts by weight of Bacillus laterosporus, 0.2 parts by weight of Thiobacillus and 0.2 parts by weight of Bacillus mucilaginosus, mix evenly to obtain a mixture;

[0084] (2) Add water to the mixture in step (1) with a water content of 30%;

[0085] (3) Microbial strains were used at 30℃ to degrade the organic matter in coal gangue for 40 days, with the mixture being turned over on average every 2 days.

[0086] Comparative Example 1

[0087] This comparative example provides a method for preparing humic acid from coal gangue, the specific method including the following steps:

[0088] (1) Crush the coal gangue through a 100-mesh sieve, take 1000 parts by weight of the sieved coal gangue, add nitrogen fertilizer, phosphate fertilizer and water, so that the mass ratio of C:N:P is 150:8.5:1 and the water content is 30%.

[0089] (2) The organic matter in the coal gangue was degraded at 30℃ for 10 days, and the mixture was stirred every 2 days on average.

[0090] Comparative Example 2

[0091] This comparative example provides a method for converting coal gangue into humic acid, the specific method including the following steps:

[0092] (1) Crush the coal gangue through a 100-mesh sieve, take 1000 parts by weight of the sieved coal gangue, add water to make the water content 30%.

[0093] (2) The organic matter in the coal gangue was degraded at 30℃ for 10 days, and the mixture was stirred every 2 days on average.

[0094] Test Example 1

[0095] This test example describes the extraction and detection of humic acid in coal gangue samples obtained in Examples 1-15 and Comparative Examples 1-2. The detection method is as follows:

[0096] The extraction method for humic acid is in accordance with the national standard GB / T 11957-2001.

[0097] The test results are shown in Table 1 below:

[0098] Table 1

[0099]

[0100]

[0101] As can be seen from the data in the table above, the method for preparing humic acid by microbial decomposition and transformation of coal gangue provided by the present invention can effectively degrade the organic matter in coal gangue and convert it into humic acid. Comparing Example 1 with Comparative Examples 1-2 reveals that the use of microbial strains can significantly improve the conversion effect of organic matter in coal gangue. Comparing Example 1 with Examples 4-9 reveals that the combination of Bacillus subtilis, Bacillus licheniformis, and Bacillus laterosporus can synergistically improve the conversion effect of organic matter in coal gangue. Comparing Example 1 with Examples 10-11 reveals that the combination of microbial strains for mineral bioweathering and microbial strains for converting organic matter in coal gangue into humic acid can significantly improve the conversion effect of organic matter in coal gangue. Comparing Example 1 with Examples 12-13 reveals that the combination of Thiobacillus and Bacillus mucilaginosus can improve the conversion effect of organic matter in coal gangue. Comparing Example 1 with Examples 14-15 reveals that nutrients and degradation time affect the conversion of organic matter in coal gangue.

[0102] In summary, the method for preparing humic acid from coal gangue by microbial decomposition and transformation provided by this invention can effectively degrade the organic matter in coal gangue and convert it into humic acid. By using a combination of microbial strains for mineral bioweathering and microbial strains for converting organic matter in coal gangue into humic acid, the conversion effect of organic matter in coal gangue can be synergistically improved, increasing the humic acid content in coal gangue. Combined with nutrient supplementation, the conversion effect of organic matter in coal gangue can be further enhanced.

[0103] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing humic acid by microbial decomposition and transformation of coal gangue, characterized in that, The method for preparing humic acid by microbial decomposition and transformation of coal gangue includes the following steps: Coal gangue, microbial inoculum, and water are mixed to obtain a mixed system. The microbial inoculum then produces humic acid. The microbial strains include microbial strains that decompose inorganic minerals wrapped around organic matter through bioweathering and microbial strains that convert organic matter in coal gangue into humic acid. The microbial strains for mineral bioweathering include microbial strains for pyrite bioweathering and microbial strains for aluminosilicate mineral bioweathering. The microbial strains used in the bioweathering of pyrite include desulfurizing bacteria; The desulfurizing bacteria is Thiobacillus thiobacillus with model number BNCC173437; The microbial strains involved in the bioweathering of aluminosilicate minerals include silicate bacteria; The silicate bacteria are Bacillus mucilaginosus; The microbial strains that convert organic matter in coal gangue into humic acid are a combination of Bacillus subtilis, Bacillus licheniformis, and Bacillus laterosporus. The mass ratio of Thiobacillus, Bacillus mucilaginosus, Bacillus subtilis, Bacillus licheniformis, and Bacillus laterosporus is 0.2:0.2:0.2:0.2:0.2 or 0.15:0.3:0.1:0.15:0.

2. The mass ratio of coal gangue to microbial inoculum is 1000:(0.9-1); The mass ratio of carbon, nitrogen and phosphorus in the mixed system is (60-300):(7-10):

1.

2. The method for preparing humic acid from coal gangue by microbial decomposition and transformation according to claim 1, characterized in that, The mass fraction of water in the mixture is 10-60%.

3. The method for preparing humic acid from coal gangue by microbial decomposition and transformation according to claim 1, characterized in that, The mixture system also includes the addition of nutrients, including nitrogen fertilizer and / or phosphorus fertilizer.

4. The method for preparing humic acid from coal gangue by microbial decomposition and transformation according to claim 1, characterized in that, The coal gangue needs to be crushed and sieved before mixing.

5. The method for preparing humic acid from coal gangue by microbial decomposition and transformation according to claim 4, characterized in that, The sieve mesh size is 20-200 mesh.

6. The method for preparing humic acid from coal gangue by microbial decomposition and transformation according to claim 1, characterized in that, The duration of action of the microbial strains is 10-90 days.

7. The method for preparing humic acid from coal gangue by microbial decomposition and transformation according to claim 1, characterized in that, The microbial strains were used under conditions of 20-60℃.

8. The method for preparing humic acid from coal gangue by microbial decomposition and transformation according to claim 1, characterized in that, The microbial strains need to be turned over during operation, and the turning frequency is once every 2-10 days.

9. The method for preparing humic acid from coal gangue by microbial decomposition and transformation according to any one of claims 1-8, applied in coal gangue treatment.

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