Method for in-situ land reclamation screening and indigenous crop planting of coal gangue storage yard

Abstract

The invention discloses a method for planting indigenous crops by in-situ land reclamation of a coal gangue storage yard, which comprises the following steps: firstly, mixing screened shale coal gangue with other materials for in-situ composting fermentation, then flatly laying the fermented product on the surface of the coal gangue storage yard in a set pilot plant test area to obtain a growth substrate, primarily screening a plurality of indigenous crops for planting and tending, and finally, carrying out primary screening on the indigenous crops to obtain the indigenous crops. According to the conditions of crop growth vigor, yield, product quality and the like, final crops are determined for amplification engineering, and finally coal gangue storage yard in-situ land reclamation and indigenous crop screening planting are completed.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive resource utilization and vegetation restoration in coal gangue dumps, and particularly relates to a method for in-situ land reclamation and planting of native crops in coal gangue dumps. Background Art

[0002] According to statistics, Guizhou Province has approximately 200 million tons of coal gangue in stock, with approximately 20 million tons added annually, primarily in natural stockpiles. As a general industrial solid waste, coal gangue is currently being utilized for comprehensive utilization, including power generation, construction material production, extraction of valuable elements, underground backfill, and the preparation of organic compound fertilizers. However, due to cost, technical, and other limitations, large-scale application is difficult.

[0003] Coal mines in Guizhou Province are primarily located in mountainous ravines, far from urban or built-up areas, with inconvenient road access. Most mines are small-scale and have poor economic returns. Furthermore, mining in clusters of coal seams creates severe gas hazards. Underground backfilling eliminates the protective layer's mining function, significantly hindering coal mine gas management. Manufacturing building materials locally results in a lack of market opportunities or high export costs, resulting in no economic benefits. Therefore, a comprehensive method for utilizing coal gangue resources is urgently needed. Summary of the Invention

[0004] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0005] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0006] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for in-situ land reclamation, screening and planting of native crops in a coal gangue dump.

[0007] In order to solve the above technical problems, the present invention provides the following technical solution: a method for in-situ land reclamation, screening and planting of native crops in a coal gangue dump, characterized by comprising:

[0008] The shale gangue is mixed with prickly pear residue, corn stalks, mushroom sticks, sludge and phosphogypsum, and then subjected to in-situ composting and fermentation. The pile is turned over every three days. After the fermentation is completed, a decomposed product is obtained. The decomposed product is spread on the gangue yard and evenly mixed with the surface soil to obtain a crop growth medium.

[0009] Initial screening of dominant fungi in native crops and crop root systems;

[0010] The auxiliary materials are evenly spread in the crop growth matrix to cultivate the selected native crops and dominant fungi.

[0011] As a preferred embodiment of the method of the present invention, the mass ratio of the shale gangue, roxburghii residue, corn straw, mushroom sticks, sludge and phosphogypsum is 30-50:1-10:1-10:1-10:10-30:1-5.

[0012] As a preferred embodiment of the method of the present invention, the particle sizes of the shale gangue, roxburghii residue, corn straw, and mushroom sticks are 0.05-10, 1-10, 1-30, and 1-10 mm.

[0013] As a preferred embodiment of the method of the present invention, the in-situ composting fermentation time is 10 to 15 days, the pile is turned every 2 to 3 days, the C / N ratio is controlled at 20 to 35:1, and the temperature is 50 to 60°C.

[0014] As a preferred embodiment of the method of the present invention, the mass ratio of the decomposed product to the surface soil is 1 to 3:1.

[0015] As a preferred embodiment of the method of the present invention, the thickness of the crop growth substrate is 20 to 50 cm.

[0016] As a preferred embodiment of the method of the present invention, the initial screening of native crops specifically involves selecting crops with a survival rate greater than 85% after 3 to 7 months of planting and a yield that can reach or exceed the average value of surrounding crops of the same type.

[0017] As a preferred embodiment of the method of the present invention, the dominant bacteria include phosphate-solubilizing bacteria, potassium-solubilizing bacteria, silicate-reducing bacteria, sulfate-reducing bacteria, and organic carbon-reducing bacteria.

[0018] As a preferred embodiment of the method of the present invention, the auxiliary material is evenly laid in the growth matrix, wherein 3 layers of cylindrical layers are laid, each layer is 15 cm thick and 50 cm long, and the laying density is 30m 2 / piece, the laying depth is 15 to 30 cm.

[0019] As a preferred embodiment of the method of the present invention, the auxiliary material is a biodegradable material wrapping, the wrapping including one or more of a heavy metal passivator, an alkaline neutralizing material, and a composite bacterial agent; the biodegradable material is one or more of PLA, PBS, PBAT, and PHA; the heavy metal passivator is one or more of phosphate, biochar, zeolite, bentonite, and sepiolite; the alkaline neutralizing material includes one or more of quicklime, slaked lime, limestone, and organic materials; and the composite bacterial agent is one or more of phosphate-solubilizing bacteria, potassium-solubilizing bacteria, silicate-reducing bacteria, sulfate-reducing bacteria, and organic carbon-reducing bacteria.

[0020] Beneficial effects of the present invention:

[0021] (1) The pilot land preparation and crop screening tests of the present invention are carried out in situ, and the data and result feedback obtained can be directly used as support conditions for the scale-up, promotion and application project, and have strong persuasiveness and reliability.

[0022] (2) The present invention fully considers the terrain conditions of the gangue dump in Guizhou Province, the comprehensive utilization of the downstream market and the policy environment, and proposes to combine gangue land reclamation with native crop planting, so as to "tailor-make" a new path and new idea for the high-value treatment and utilization of gangue in Guizhou Province.

[0023] (3) When the present invention is scaled up and promoted for application, auxiliary materials are laid out in the field, and heavy metal passivators, alkaline neutralizing materials, composite bacterial agents, etc. are slowly released according to the cycle of biodegradable materials, which can continuously improve the field conditions and provide a good matrix environment for crop growth.

[0024] (4) The present invention mixes coal gangue with other materials for in-situ composting and maturation, which not only promotes the coordinated resource utilization of other solid wastes, but also the high temperature environment generated during the fermentation process can accelerate the transformation of primary minerals in coal gangue into secondary minerals, thereby accelerating the soilification process of coal gangue. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0028] The components and contents of roxburghii residue, corn stalks, mushroom sticks, sludge, and phosphogypsum in the embodiment of the present invention are shown in Table 1.

[0029] Table 1

[0030]

[0031]

[0032] Example 1

[0033] This embodiment provides a method for in-situ land reclamation, screening, and planting native crops in a coal gangue dump, comprising the following steps:

[0034] (1) Shale gangue is mixed with prickly pear residue, corn straw, mushroom sticks, sludge, and phosphogypsum in a mass ratio of 50:5:5:5:20:5 and then subjected to in-situ composting and fermentation. The fermentation time is 10 days, and the pile is turned over every 3 days. The C / N ratio is controlled at 20:1 and the temperature is 50°C to 60°C. After the fermentation is completed, a decomposed product is obtained. The decomposed product is then spread on the coal gangue dump in the designated pilot area and evenly mixed with the surface soil in a mass ratio of 3:1 to a thickness of 20 cm to obtain a crop growth matrix.

[0035] (2) Preliminary screening of native crops such as peppers, peanuts, and potatoes, and planting and tending them in the growth medium of step (1). After 3 to 7 months of planting, the native crops with a survival rate greater than 85%, a yield that can reach or exceed the average value of the surrounding crops of the same kind, and whose products meet the limits specified in the "National Food Safety Standard Limits of Contaminants in Food" (GB2762-2017) are determined to be suitable crops for planting, and dominant bacterial species such as phosphate-solubilizing bacteria, potassium-solubilizing bacteria, silicate-reducing bacteria, sulfate-reducing bacteria, and organic carbon-reducing bacteria in the crop roots are screened and cultivated;

[0036] The growth and heavy metal content of edible parts of peppers, peanuts, and potatoes 3 to 7 months after planting are shown in Table 2:

[0037] Table 2

[0038]

[0039] (3) Repeat step (1) and evenly lay three layers of cylindrical auxiliary materials (bentonite, biochar, limestone, phosphate-solubilizing bacteria, silicate-reducing bacteria) in the growth matrix, each layer with a thickness of 15 cm and a length of 50 cm, with a laying density of 30 m 2 / , with a laying depth of 15 to 30 cm, and finally the superior bacteria strains and crops screened and cultivated in step (2) are used for the in-situ land reclamation of the coal gangue dump site and the planting of native crops for scaled-up promotion and application.

[0040] The dominant bacterial strains screened and cultivated in this process and the phosphate-solubilizing bacteria, potassium-solubilizing bacteria, silicate-reducing bacteria, sulfate-reducing bacteria, and organic carbon-reducing bacteria in the coating materials can mineralize elements such as phosphorus, potassium, and silicon in the coal gangue for use by plants and microorganisms. The organic acids secreted by the bacteria themselves cooperate with the root secretions of crops to convert primary minerals such as pyrite into secondary minerals such as goethite and lepidocrocite, or can convert the form of heavy metals in the soil from acid-soluble and reduced states to oxidized or residual states. Phosphates, biochar, zeolite, bentonite, sepiolite, quicklime, slaked lime, limestone, organic materials and other materials are gradually released into the matrix as the coating materials slowly degrade, thereby achieving the effects of increasing physical fitness, passivating metals, and promoting the weathering of minerals into soil.

[0041] Example 2

[0042] This embodiment provides a method for in-situ land reclamation, screening, and planting native crops in a coal gangue dump, comprising the following steps:

[0043] (1) Shale gangue is mixed with prickly pear residue, corn straw, mushroom sticks, sludge, and phosphogypsum in a mass ratio of 40:5:5:5:20:3 and then subjected to in-situ composting and fermentation. The fermentation time is 12 days, and the pile is turned over every 3 days. The C / N ratio is controlled to be 25:1 and the temperature is 50°C to 60°C. After the fermentation is completed, a decomposed product is obtained. The decomposed product is then spread on the coal gangue dump in the designated pilot area and evenly mixed with the surface soil in a mass ratio of 3:1 to a thickness of 30 cm to obtain a crop growth matrix.

[0044] (2) Preliminary screening of native crops such as peppers, eggplants, and peanuts, and planting and tending them in the growth medium of step (1). After 3 to 7 months of planting, the native crops with a survival rate greater than 85%, a yield that can reach or exceed the average value of the surrounding crops of the same kind, and whose products meet the limits specified in the "National Food Safety Standard Limits of Contaminants in Food" (GB2762-2017) are determined to be suitable crops for planting, and dominant bacterial species such as phosphate-solubilizing bacteria, potassium-solubilizing bacteria, silicate-reducing bacteria, sulfate-reducing bacteria, and organic carbon-reducing bacteria in the crop roots are screened and cultivated;

[0045] The growth and heavy metal content of edible parts of peppers, eggplants and peanuts 3 to 7 months after planting are shown in Table 3:

[0046] Table 3

[0047]

[0048] (3) Repeat step (1) and evenly lay 3 layers of cylindrical auxiliary materials, each with a thickness of 15 cm and a length of 50 cm, in the growth matrix with a laying density of 30m 2 / , with a laying depth of 15 to 30 cm, and finally the superior bacteria strains and crops screened and cultivated in step (2) are used for the in-situ land reclamation of the coal gangue dump site and the planting of native crops for scaled-up promotion and application.

[0049] Example 3

[0050] This embodiment provides a method for in-situ land reclamation, screening, and planting native crops in a coal gangue dump, comprising the following steps:

[0051] (1) Shale gangue is mixed with prickly pear residue, corn straw, mushroom sticks, sludge, and phosphogypsum in a mass ratio of 35:5:5:5:20:2 and then subjected to in-situ composting and fermentation. The fermentation time is 13 days, and the pile is turned over every 3 days. The C / N ratio is controlled to be 30:1 and the temperature is 50°C to 60°C. After the fermentation is completed, a decomposed product is obtained. The decomposed product is then spread on the coal gangue dump in the designated pilot area and evenly mixed with the surface soil in a mass ratio of 2:1 to a thickness of 40 cm to obtain a crop growth matrix.

[0052] (2) Preliminary screening of native crops such as peppers, eggplants, peanuts, soybeans, and potatoes, and planting and tending them in the growth medium of step (1). After 3 to 7 months of planting, the native crops with a survival rate greater than 85%, a yield that can reach or exceed the average value of the surrounding crops of the same kind, and whose products meet the limits specified in the "National Food Safety Standard Limits of Contaminants in Food" (GB2762-2017) are determined to be suitable crops for planting, and dominant bacterial species such as phosphate-solubilizing bacteria, potassium-solubilizing bacteria, silicate-reducing bacteria, sulfate-reducing bacteria, and organic carbon-reducing bacteria in the crop roots are screened and cultivated;

[0053] The growth and heavy metal content of edible parts of eggplant, peanut and soybean after 3 to 7 months of planting are shown in Table 4:

[0054] Table 4

[0055]

[0056] (3) Repeat step (1) and evenly lay 3 layers of cylindrical auxiliary materials, each with a thickness of 15 cm and a length of 50 cm, in the growth matrix with a laying density of 25m 2 / , with a laying depth of 15 to 30 cm, and finally the superior bacteria strains and crops screened and cultivated in step (2) are used for the in-situ land reclamation of the coal gangue dump site and the planting of native crops for scaled-up promotion and application.

[0057] Example 4

[0058] This embodiment provides a method for in-situ land reclamation, screening, and planting native crops in a coal gangue dump, comprising the following steps:

[0059] (1) Shale gangue is mixed with prickly pear residue, corn straw, mushroom sticks, sludge, and phosphogypsum in a mass ratio of 30:5:5:5:20:1 and then subjected to in-situ composting and fermentation. The fermentation time is 15 days, and the pile is turned over every 3 days. The C / N ratio is controlled to be 35:1 and the temperature is 50°C to 60°C. After the fermentation is completed, a decomposed product is obtained. The decomposed product is then spread on the coal gangue dump in the established pilot area and evenly mixed with the surface soil in a mass ratio of 1:1 to a thickness of 50 cm to obtain a crop growth matrix.

[0060] (2) Preliminary screening of native crops such as peppers, soybeans, and potatoes, and planting and tending them in the growth medium of step (1). After 3 to 7 months of planting, the native crops with a survival rate greater than 85%, a yield that can reach or exceed the average value of the surrounding crops of the same kind, and whose products meet the limits specified in the "National Food Safety Standard Limits of Contaminants in Food" (GB2762-2017) are determined to be suitable crops for planting, and dominant bacterial species such as phosphate-solubilizing bacteria, potassium-solubilizing bacteria, silicate-reducing bacteria, sulfate-reducing bacteria, and organic carbon-reducing bacteria in the crop roots are screened and cultivated;

[0061] The growth of peppers, soybeans, and potatoes and the heavy metal content in their edible parts 3 to 7 months after planting are shown in Table 5:

[0062] Table 5

[0063]

[0064] (3) Repeat step (1) and evenly lay 3 layers of cylindrical auxiliary materials, each with a thickness of 15 cm and a length of 50 cm, in the growth matrix with a laying density of 20m 2 / , with a laying depth of 15 to 30 cm, and finally the superior bacteria strains and crops screened and cultivated in step (2) are used for the in-situ land reclamation of the coal gangue dump site and the planting of native crops for scaled-up promotion and application.

[0065] Comparative Example 1

[0066] The difference between this comparative example and Example 1 is that the mass ratio of roxburghii residue, corn straw, mushroom sticks, sludge, and phosphogypsum in step (1) is adjusted to 30:5:5:5:40:5, and the remaining steps are the same as Example 1. The results may be due to the high specific gravity of the sludge. The heavy metal content in the crop matrix exceeded the standard, among which Cd pollution was the highest.

[0067] Comparative Example 2

[0068] The difference between this comparative example and Example 1 is that the mass ratio of roxburghii residue, corn straw, mushroom sticks, sludge, and phosphogypsum in step (1) is adjusted to 40:5:5:5:20:10, and the remaining steps are the same as in Example 1. The results may be due to the dilution effect caused by the large specific gravity of phosphogypsum, resulting in insufficient organic carbon in the crop growth matrix, decreased maturity, and the seed germination index dropped to below 70%.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Example 1 is that the corn straw in step (1) is replaced by wheat straw, and the remaining steps are the same as those in Example 1.

[0071] Comparative Example 4

[0072] The difference between this comparative example and Example 1 is that the phosphogypsum in step (1) is replaced by fly ash, and the remaining steps are the same as those in Example 1.

[0073] Comparative Example 5

[0074] The difference between this comparative example and Example 1 is that the corn straw and phosphogypsum in step (1) are replaced by wheat straw and fly ash respectively, and the remaining steps are the same as those in Example 1.

[0075] The growth conditions of peppers, peanuts and potatoes in Comparative Examples 3 to 5 after 3 to 7 months of planting are shown in Table 6:

[0076] Table 6

[0077]

[0078] It can be seen that crop yields have dropped significantly. This is because the synergistic effect of corn straw and phosphogypsum achieves soil remediation and crop yield increase through organic-mineral coupling, adsorption-precipitation complementarity, and structure-function mutual promotion. The in-situ land reclamation of the coal gangue dump in the embodiment of the present invention is used for site closure and storage, and can also be applied to ditch filling and land reclamation in barren mountains, collapsed areas, etc., and several regionally suitable local economic crops have been successfully planted. It can be seen that the present invention can reduce the amount of coal gangue in Guizhou Province and utilize resources at a high value.

[0079] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all of these should be included in the scope of the present invention.

Claims

1. A method for in-situ land reclamation and planting of native crops in a coal gangue dump, characterized by: include, The shale gangue is mixed with prickly pear residue, corn stalks, mushroom sticks, sludge and phosphogypsum, and then subjected to in-situ composting and fermentation. The pile is turned over every three days. After the fermentation is completed, a decomposed product is obtained. The decomposed product is spread on the gangue yard and evenly mixed with the surface soil to obtain a crop growth medium. Initial screening of dominant fungi in native crops and crop root systems; The auxiliary materials are evenly spread in the crop growth matrix to cultivate the selected native crops and dominant fungi.

2. The method according to claim 1, wherein: The mass ratio of the shale gangue, roxburghii residue, corn straw, mushroom sticks, sludge and phosphogypsum is 30-50:1-10:1-10:1-10:10-30:1-5.

3. The method according to claim 2, wherein: The particle sizes of the shale gangue, roxburghii residue, corn straw and mushroom sticks are 0.05-10, 1-10, 1-30 and 1-10 mm.

4. The method according to claim 1, wherein: The in-situ composting fermentation time is 10 to 15 days, the pile is turned every 2 to 3 days, and the C / N ratio is controlled at 20 to 35:

1. The temperature is 50-60℃.

5. The method according to claim 1, wherein: The mass ratio of the decomposed product to the surface soil is 1 to 3:

1.

6. The method according to claim 1, wherein: The thickness of the crop growth matrix is ​​20 to 50 cm.

7. The method according to claim 1, wherein: The primary screening of native crops specifically involves selecting crops with a survival rate greater than 85% after 3 to 7 months of planting and a yield that can reach or exceed the average value of surrounding crops of the same kind.

8. The method according to claim 7, wherein: The dominant bacteria include phosphate-solubilizing bacteria, potassium-solubilizing bacteria, silicate-reducing bacteria, sulfate-reducing bacteria, and organic carbon-reducing bacteria.

9. The method according to claim 8, wherein: The auxiliary materials are evenly laid in the growth matrix, wherein 3 layers of cylindrical shapes are laid, each layer is 15 cm thick and 50 cm long, and the laying density is 30m 2 / piece, the laying depth is 15 to 30 cm.

10. The method according to claim 9, wherein: The auxiliary material is a biodegradable material wrapping, which includes one or more of a heavy metal passivator, an alkaline neutralizing material, and a composite bacterial agent; the biodegradable material is one or more of PLA, PBS, PBAT, and PHA; the heavy metal passivator is one or more of phosphate, biochar, zeolite, bentonite, and sepiolite; the alkaline neutralizing material includes one or more of quicklime, slaked lime, limestone, and organic materials; and the composite bacterial agent is one or more of phosphate-solubilizing bacteria, potassium-solubilizing bacteria, silicate-reducing bacteria, sulfate-reducing bacteria, and organic carbon-reducing bacteria.

Images