Soil conditioner based on coal gangue and application thereof

Abstract

The invention relates to the technical field of coal gangue treatment, in particular to a soil conditioner based on coal gangue and application of the soil conditioner. The soil conditioner is prepared by the following steps: putting calcined and modified coal gangue into domestic sewage, adsorbing organic matters, mineral nutrient elements and microorganisms in the sewage into a coal gangue material through domestic sewage reinforcement treatment, and then carrying out standing and aging treatment to change a microbial community structure in the coal gangue, so that the soil conditioner is prepared. The bio-availability of organic matters and mineral nutrient elements in the gangue is improved, and standing and aging are performed for 15-45 days to obtain the soil conditioner. The soil conditioner provided by the invention is rich in nitrogen, phosphorus, potassium, organic matters and abundant microbial communities, the saline-alkali soil quality can be improved by applying the soil conditioner provided by the invention to saline-alkali soil, the crop germination rate and biomass are further improved, and the goal of integrating ecological gradient utilization of coal gangue and saline-alkali soil improvement is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of coal gangue treatment, and particularly relates to a soil conditioner based on coal gangue and application thereof. Background Art

[0002] As a solid waste with a large emission volume, coal gangue is discharged at least 200 million tons every year, which means that the storage of coal gangue occupies a large amount of land resources. Due to the significant regional differences in resources and the constraints of economic conditions, technical equipment, etc., the utilization rate of coal gangue is only about 65%. Therefore, it is urgent to develop a method for treating coal gangue to improve the utilization rate of coal gangue.

[0003] The main components of coal gangue are Al2O3 and SiO2, which exist in the form of quartz and kaolinite, and also contain a small amount of Fe2O3, CaO, MgO, K2O, Na2O, SO3, TiO2, P2O5, MnO, etc. Coal gangue after safety pretreatment can reduce the background value of pollutants it may contain, and has a good resource utilization value.

[0004] At present, the technology of resource utilization of coal gangue at home and abroad focuses on the research and development of water treatment agents or soil improvement technology. The application of coal gangue in the field of water treatment is mainly based on the research and development of adsorption materials. However, adsorbents often have a certain adsorption capacity. Even if the chemical stability and regeneration efficiency of coal gangue can be improved to a certain extent through modification, there are still problems such as decreased regeneration efficiency and inability of adsorption capacity to meet water treatment requirements after repeated use. Finally, it has to be discharged into the environment as solid waste, becoming a new source of pollution.

[0005] The direct application of coal gangue in soil improvement also has problems such as poor water holding capacity and insufficient fertility. The hydrogen ions released by coal gangue also pose the risk of forming extreme soil pH values. At the same time, the lack of nutrients in coal gangue limits its ability to serve as a high-quality soil conditioner. Therefore, it is urgent to develop new products and technologies for the resource utilization of coal gangue. Summary of the invention

[0006] In view of the technical problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a soil conditioner based on coal gangue and its application. The soil conditioner provided by the present invention contains rich nitrogen, phosphorus, organic matter and rich microbial communities, which can be used to improve saline-alkali soil and promote crop growth, thus achieving the goal of integrated ecological cascade utilization of coal gangue and improvement of saline-alkali land.

[0007] The first aspect of the present invention provides a soil conditioner based on coal gangue, wherein the soil conditioner is prepared by the following steps:

[0008] The calcined modified coal gangue is placed in domestic sewage for enhanced treatment so as to adsorb organic matter, mineral nutrients and microorganisms in the sewage into the coal gangue material;

[0009] The reinforced treated coal gangue material is subjected to aging treatment to change the microbial community structure of the coal gangue and improve the biological effectiveness of organic matter and mineral nutrient elements. The aging treatment is performed for 15 to 45 days to obtain the soil conditioner.

[0010] Furthermore, the soil conditioner has a moisture content of 15% to 40%, a nitrogen content of 400 mg / kg to 600 mg / kg, a phosphorus content of 700 mg / kg to 900 mg / kg, a potassium content of 10 g / kg to 30 g / kg, and an organic matter content of 30 g / kg to 60 g / kg.

[0011] Furthermore, the strengthening treatment time is 60d to 730d. 。

[0012] Furthermore, the conditions for the aging treatment are: ventilation, avoiding direct sunlight and relative humidity of 15% to 40%.

[0013] Preferably, the static aging time is 20 days.

[0014] Furthermore, the calcined modified coal gangue preparation steps are as follows:

[0015] Crushing the coal gangue into coal gangue particles with a particle size of 3 to 10 mm;

[0016] The coal gangue particles are calcined at a high temperature of 600-800°C for 1-2 hours to obtain calcined modified coal gangue.

[0017] The second aspect of the present invention provides a use of the above-mentioned soil conditioner in improving saline-alkali soil.

[0018] Furthermore, when the soil conditioner is used, the mixing mass ratio of the soil conditioner to the saline-alkali soil is 10 to 20:100.

[0019] The third aspect of the present invention provides a use of the above-mentioned soil conditioner in promoting crop growth.

[0020] Furthermore, the soil conditioner is used to increase the biomass of crops.

[0021] Furthermore, the soil conditioner is used to increase the germination rate of crops.

[0022] In summary, compared with the prior art, the present invention has the following advantages and effects:

[0023] (1) The present invention provides a soil conditioner based on coal gangue, which contains rich nitrogen, phosphorus, potassium, organic matter and rich microbial communities. When the soil conditioner is mixed with saline-alkali soil, the pH value of the saline-alkali soil can be reduced and the soil fertility can be improved. When wheat is planted after the soil conditioner is mixed with the saline-alkali soil, the germination rate of wheat is increased by 400% and the biomass is increased by 10.2 times compared with wheat planted in bare soil.

[0024] (2) The soil conditioner provided by the present invention is obtained by treating the modified coal gangue with domestic sewage, and then aging it. The experiment of the present invention shows that through the process of strengthening the treatment of domestic sewage, the nitrogen, phosphorus, potassium, organic matter and rich microbial communities in the sewage can be adsorbed into the pores of the forged modified coal gangue, and then the strengthened coal gangue is left to stand for aging under the conditions of ventilation, avoiding direct light and relative humidity of 15% to 40%, which can further increase the number of effective live bacteria in the coal gangue, improve the biological effectiveness of organic matter and mineral nutrients, and effectively reduce the abundance of harmful bacteria such as Faecalibacterium and Blautia in the soil conditioner. The preparation process is simple, the raw materials are widely available, and the cost is low. The modified coal gangue in this preparation process can also be used as filler for domestic sewage in aerobic / anaerobic biofilters, different types of artificial wetlands, etc. It can not only remove nitrogen and phosphorus from domestic sewage, but the final prepared soil conditioner can also be applied to saline-alkali soil to improve soil quality, achieving the goal of integrated ecological cascade utilization of coal gangue and saline-alkali land improvement.

[0025] (3) The inventive concept of the present invention is as follows:

[0026] The mineral phase composition of coal gangue is mainly quartz, montmorillonite, kaolinite and illite. The metal oxides such as SiO2 and Al2O3 on its surface have certain adsorption capacity for phosphate, organic matter and ammonia. By crushing and high-temperature calcining the coal gangue, the specific surface area, porosity and number of active sites of ordinary coal gangue are improved, the mineral structure of coal gangue is improved, and the surface performance of coal gangue is strengthened, which can well solve the problem of insufficient water holding capacity of soil improvement and make it have stronger adsorption capacity. Domestic sewage is rich in nitrogen, phosphorus and organic matter. Excessive content of these conventional pollutants will lead to eutrophication pollution of receiving water bodies. Through the enhanced treatment of domestic sewage, the nitrogen, phosphorus and organic matter in domestic sewage can be attached to the calcined modified coal gangue through physical adsorption, chemical adsorption and microbial absorption and transformation. It can not only solve the problem of low C / N ratio of water treatment to a certain extent, but also solve the problem of simple nutrient structure of coal gangue and enhance the biological effectiveness of nutrients in the material. The long-term water treatment process can also well balance the acid-base release of the calcined modified coal gangue material, ensuring the acid-base balance of subsequent soil improvement. The coal gangue material after long-term water treatment not only contains mineral nutrients such as silicon, aluminum, carbon, iron, sulfur, and calcium, but also increases nitrogen, phosphorus, organic matter and rich microbial communities. The static aging process can further change the microbial community structure in the material, increase the number of effective live bacteria, and improve the biological effectiveness of the effective components it contains. The soil conditioner prepared by the present invention is applied to saline-alkali soil, and the acidic functional groups in the soil conditioner can release H + , lowering the soil pH value. The rich chemical elements in it can exchange cations with the soil, which can effectively improve the problems of salinized soil such as expansion and dispersion when wet, compaction when dry, and poor water permeability and air permeability. It can improve saline-alkali soil, increase soil fertility, benefit crop absorption and slow release of nutrients, and promote plant growth. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart for preparing the soil conditioner of Example 1.

[0028] Figure 2 The wheat planting test results are as follows: the soils for wheat planting in Figures A, B and C are saline-alkali soil, saline-alkali soil with 15% common coal gangue added, and saline-alkali soil with 15% soil conditioner prepared in Example 1 added. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below in conjunction with specific embodiments and drawings.

[0030] In the description of the present invention, unless otherwise specified, all reagents used are commercially available and all methods used are conventional techniques in the art.

[0031] Gangue is a porous mineral material with kaolinite as the main component and rich in organic matter, nitrogen, phosphorus and potassium. At present, the technology for the resource utilization of gangue focuses on the research and development of water treatment agents or soil improvement technology. The application of gangue in the field of water treatment is mainly based on the research and development of adsorption materials, but when its adsorption capacity is relatively saturated and cannot meet the water treatment requirements, it will have to be discharged into the environment as solid waste and become a new source of pollution. The direct application of gangue in soil improvement also has problems such as poor water retention, uneven fertility and risk of acid and alkali release. Therefore, it is urgent to develop new products and technologies for the resource utilization of gangue.

[0032] The present invention provides a soil conditioner based on coal gangue. The present invention places calcined modified coal gangue in domestic sewage for enhanced treatment, so that organic matter, mineral nutrients and microorganisms in sewage are adsorbed in the coal gangue material, and then the microbial community structure in the coal gangue material is changed by static aging treatment, the biological effectiveness of organic matter and mineral nutrients is improved, and the material is aged for 15 to 45 days under ventilation, avoiding direct light and relative humidity of 15% to 40%, thereby obtaining a soil conditioner. By applying the prepared soil conditioner to saline-alkali soil, it is found that the soil conditioner can increase the content of organic matter and effective nitrogen and phosphorus in saline-alkali soil, and the number of live bacteria in the soil is significantly improved, thereby improving the soil properties of saline-alkali soil. The soil conditioner provided by the present invention has the advantages of abundant raw material resources, low cost, easy preparation and good applicability, and has important application value in the fields of improving saline-alkali soil quality and promoting crop growth, and realizes the multi-level ecological utilization of coal gangue.

[0033] In some embodiments of the present invention, the gangue is derived from the Datun Coal Washing Plant of Datun Coal and Electricity Group, Peixian County, Xuzhou, Jiangsu Province. Its main chemical composition is SiO2 (60.23%), Al2O3 (27.07%), Fe2O3 (4.16%) and K2O (2.07%). The heavy metal content contained in the gangue is shown in the table below, which is lower than the risk screening standard of GB15618-2018 "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)".

[0034] Table 1 Heavy metal content in coal gangue

[0035]

[0036] In some embodiments of the present invention, domestic wastewater is derived from the domestic sewage treatment plant of China University of Mining and Technology, and the main pollutant detection indicators in the water include: chemical oxygen demand (COD), biochemical oxygen demand (BOD), suspended solids (SS), total nitrogen (TN) and total phosphorus (TP); the COD value is 320 mg / L, the BOD value is 120 mg / L, the SS value is 170 mg / L, the TN value is 35 mg / L, and the TP value is 3.12 mg / L.

[0037] In some embodiments of the present invention, the saline-alkali soil is taken from the coastal saline-alkali soil of Nantong, Jiangsu Province. The main properties of the saline-alkali soil are shown in Table 2:

[0038] Table 2 Physical and chemical properties of saline-alkali soil

[0039]

[0040] Example 1

[0041] A method for preparing a soil conditioner based on coal gangue comprises the following steps. The preparation flow chart is shown in Figure 1 :

[0042] S1, crushing the coal gangue into coal gangue particles with a particle size of 5 mm;

[0043] S2, calcining the coal gangue particles at a high temperature of 600° C. for 2 h to obtain calcined modified coal gangue;

[0044] S3, putting the calcined modified coal gangue into the domestic sewage aeration tank as water treatment filler for 60 days;

[0045] S4. Place the reinforced gangue in a ventilated environment away from direct sunlight and at a relative humidity of 35% for 20 days, then crush and sieve to obtain a soil conditioner.

[0046] Example 2

[0047] A method for preparing a soil conditioner based on coal gangue comprises the following steps. The preparation flow chart is shown in Figure 1 :

[0048] S1. crushing the coal gangue into coal gangue particles with a particle size of 10 mm;

[0049] S2, calcining the coal gangue particles at a high temperature of 700° C. for 1 h to obtain calcined modified coal gangue;

[0050] S3, putting the calcined modified coal gangue into the domestic sewage aeration tank as water treatment filler for 365 days;

[0051] S4. Place the reinforced gangue in a ventilated environment away from direct sunlight and at a relative humidity of 40% for 15 days, then crush and sieve to obtain a soil conditioner.

[0052] Example 3

[0053] A method for preparing a soil conditioner based on coal gangue comprises the following steps. The preparation flow chart is shown in Figure 1 :

[0054] S1. crushing the coal gangue into coal gangue particles with a particle size of 3 mm;

[0055] S2, calcining the coal gangue particles at a high temperature of 800° C. for 2 h to obtain calcined modified coal gangue;

[0056] S3, putting the calcined modified coal gangue into the domestic sewage aeration tank as water treatment filler for 730 days;

[0057] S4. Place the reinforced gangue in a ventilated environment away from direct sunlight and at a relative humidity of 15% for 45 days, then crush and sieve to obtain a soil conditioner.

[0058] Comparative Example 1

[0059] A method for preparing a soil conditioner based on coal gangue comprises the following steps:

[0060] S1, crushing the coal gangue into coal gangue particles with a particle size of 5 mm;

[0061] S2, calcining the coal gangue particles at a high temperature of 600° C. for 2 h to obtain calcined modified coal gangue;

[0062] S3, putting the calcined modified coal gangue into the domestic sewage aeration tank as water treatment filler for 60 days;

[0063] S4. The coal gangue after strengthening treatment is crushed and sieved to obtain a soil conditioner.

[0064] Comparative Example 2

[0065] A method for preparing a soil conditioner based on coal gangue comprises the following steps:

[0066] S1, crushing the coal gangue into coal gangue particles with a particle size of 5 mm;

[0067] S2, calcining the coal gangue particles at a high temperature of 600° C. for 2 h to obtain calcined modified coal gangue;

[0068] S3. Crush and sieve the calcined and modified coal gangue to obtain a soil conditioner.

[0069] In order to verify the effect of the soil conditioner prepared by the present invention on improving saline-alkali soil and promoting crop growth, the inventors conducted the following experiments:

[0070] Since Examples 1 to 3 have similar effects, for the convenience of subsequent discussion and reference, the test results of Example 1 shall prevail. The following are the test results of Example 1.

[0071] 1. Characterization of soil conditioners

[0072] The moisture, nitrogen, phosphorus, potassium and organic matter contents of the soil conditioner prepared in Example 1 were detected.

[0073] After testing, the soil conditioner prepared in Example 1 has a moisture content of 32%, a nitrogen content of 431 mg / kg, a phosphorus content of 754 mg / kg, a potassium content of 14.3 g / kg, and an organic matter content of 38.7 g / kg.

[0074] 2. Soil property testing after application

[0075] The soil conditioners prepared in Example 1, Comparative Example 1 and Comparative Example 2 were mixed with saline-alkali soil at a mass ratio of 15:100, and bare soil without adding soil conditioner was used as a control group (CK). After 45 days, the changes in soil properties were detected. The results are shown in Table 3.

[0076] Table 3 Changes in soil properties under different implementation conditions

[0077]

[0078] From the results in Table 3, it can be seen that the soil pH value can be reduced and the content of organic matter, nitrogen and phosphorus in saline-alkali soil can be increased through intensive treatment and aging treatment.

[0079] 3. Analysis of microbial community structure in soil conditioners

[0080] The present invention detects the bacterial community structure of the effective live bacteria in the soil conditioner prepared in Example 1 and Comparative Example 1, and the experimental results are shown in Table 4.

[0081] Table 4 Microbial community structure of soil conditioners under different preparation conditions

[0082]

[0083]

[0084] The experimental results in Table 4 show that aging treatment can effectively improve the abundance and diversity of microorganisms in forging-modified coal gangue, effectively reduce the abundance of harmful bacteria such as Faecalibacterium and Blautia in soil conditioners, increase the abundance of bacteria such as Sphingomonas and Roseomonas, and significantly increase the number of live bacteria.

[0085] 4. Wheat planting experiment

[0086] The soil conditioner prepared in Example 1 and common coal gangue were mixed with saline-alkali soil at a volume ratio of 15%, and a wheat planting experiment was conducted. Group 1 was wheat planted in bare soil, Group 2 was wheat planted after adding 15% common coal gangue, and Group 3 was wheat planted after adding 15% soil conditioner prepared in Example 1. The experimental results are shown in FIG. Figure 2 shown.

[0087] from Figure 2 It can be seen that 7 days after wheat planting, the germination rate of wheat in group 1 was 2%, the germination rate of wheat in group 2 was 4%, and the germination rate of wheat in group 3 was 8%. Compared with wheat planted in bare soil, the germination rate of wheat planted with the soil conditioner prepared in Example 1 increased by 400%. By measuring the biomass, it was found that the biomass of wheat planted in groups 2 and 3 increased by 3.4 times and 10.2 times respectively compared with group 1, indicating that the soil conditioner provided by the present invention can promote nutrient release and plant growth.

Claims

1. A soil conditioner based on coal gangue, characterized in that: The soil conditioner is prepared by the following steps: The calcined modified coal gangue is placed in domestic sewage for enhanced treatment so as to adsorb organic matter, mineral nutrients and microorganisms in the sewage into the coal gangue material; The reinforced gangue material is subjected to aging treatment to change the microbial community structure of the gangue and improve the biological effectiveness of organic matter and mineral nutrient elements. The aging treatment is performed for 15 to 45 days to obtain the soil conditioner.

2. The soil conditioner according to claim 1, characterized in that The soil conditioner has a moisture content of 15% to 40%, a nitrogen content of 400 mg / kg to 600 mg / kg, a phosphorus content of 700 mg / kg to 900 mg / kg, a potassium content of 10 g / kg to 30 g / kg, and an organic matter content of 30 g / kg to 60 g / kg.

3. The soil conditioner according to claim 1, characterized in that The strengthening treatment time is 60d to 730d.

4. The soil conditioner according to claim 1, characterized in that The conditions of the aging treatment are: ventilation, avoiding direct sunlight and relative humidity of 15% to 40%.

5. The soil conditioner according to claim 1, characterized in that The steps for preparing the calcined modified coal gangue are as follows: Crushing the coal gangue into coal gangue particles with a particle size of 3 to 10 mm; The coal gangue particles are calcined at a high temperature of 600-800°C for 1-2 hours to obtain calcined modified coal gangue.

6. Use of the soil conditioner according to claim 1 in improving saline-alkali soil.

7. Use of the soil conditioner according to claim 6, wherein when the soil conditioner is used, the mixing mass ratio of the soil conditioner to saline-alkali soil is 10 to 20:

100.

8. Use of the soil conditioner according to claim 1 in promoting crop growth.

9. The use of the soil conditioner according to claim 8, characterized in that: The soil conditioner is used to increase the biomass of crops.

10. The use of the soil conditioner according to claim 8, characterized in that: The soil conditioner is used for improving the germination rate of crops.

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