Soil conditioner prepared from coal-based solid waste and preparation method thereof

Abstract

The invention relates to the technical field of comprehensive utilization of solid wastes, and discloses a soil conditioner prepared from coal-based solid wastes and a preparation method thereof, the soil conditioner comprises the following raw materials by weight: 80-100 parts of coal-based solid wastes, 5-15 parts of an inorganic salt material, 100-150 parts of pure water, 1-10 parts of a microbial agent fertilizer and 20-50 parts of crop straw biochar. According to the scheme, the inorganic salt is added, so that multivalent cations such as calcium, iron and aluminum are loaded on the coal-based solid waste and can be replaced with exchangeable sodium ions on soil colloid, and the soil desalting efficiency is improved; the crop straw biochar can increase the content of nutrient elements such as carbon, nitrogen and phosphorus for soil; the porous structure of the modified coal-based solid waste can provide a proper place for growth and reproduction of microorganisms, and the soil microenvironment is improved; the soil conditioner is simple in raw material composition, the coal-based solid waste is used as the main raw material for improving the saline-alkali soil, the source is wide, the production cost is low, pollution to the environment is avoided, and large-area popularization and application in saline-alkali soil areas can be facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive utilization of solid wastes, and in particular to a soil conditioner prepared from coal-based solid wastes and a preparation method thereof. Background Art

[0002] Generally speaking, saline-alkali soil has a compact structure, poor water and air permeability, lacks nutrients, has a high salt content, and has a high pH value and alkalinity. At present, the main method for improving saline-alkali soil is chemical improvement, that is, adding improvers to the soil. Soil improvers mainly include inorganic improvers, organic improvers, and microbial improvers. Various types of soil improvers have certain improvement effects, but there are some problems, such as large dosage, high cost, slow effect, and secondary pollution.

[0003] In addition, my country's coal-based solid waste production is large and the comprehensive utilization rate is low. The transportation and disposal costs of coal chemical enterprises are high. Landfill storage requires a large amount of land resources, which has a certain impact on the ecological environment.

[0004] Therefore, it is necessary to develop a method that can not only improve saline-alkali soil, but also treat coal-based solid waste and reduce its impact on the environment. Summary of the invention

[0005] The present invention aims to provide a soil conditioner and a preparation method thereof to solve the problems of high cost of coal-based solid waste disposal and large dosage of saline-alkali soil conditioner and slow effect.

[0006] To achieve the above-mentioned purpose, the present invention provides a soil conditioner prepared using coal-based solid waste, comprising the following raw materials in parts by weight: 80 to 100 parts of coal-based solid waste, 5 to 15 parts of inorganic salt materials, 100 to 150 parts of pure water, 1 to 10 parts of microbial agent fertilizer, and 20 to 50 parts of biochar, wherein the biochar is acid-modified.

[0007] The inventors have found that coal-based solid wastes, such as coal gasification slag, fly ash, and coal gangue, all have porous structures and are rich in silicon, potassium, iron, and other trace elements. Transforming them to make them suitable for soil improvement can not only save land resources but also reduce environmental pollution. However, in reality, the effect of directly using coal-based solid waste to improve saline-alkali land is not good. This is because, on the one hand, the pH value of coal-based solid waste itself is too high, which will further aggravate the degree of salinization; on the other hand, direct application to saline-alkali soil cannot improve soil structure, nor will it increase the content of soil nutrients. The present application combines coal-based solid waste and crop straw biochar with inorganic salt materials to reduce soil bulk density, increase soil porosity, improve desalination efficiency, and increase soil nutrient content. The structural characteristics of the above materials are used to promote the growth and reproduction of soil microorganisms by combining microbial agents and fertilizers to comprehensively improve saline-alkali soil. The raw material composition of the soil improver of the present application is simple, and coal-based solid waste is used as the main raw material to improve saline-alkali soil, turning waste into treasure. It has a wide source, which not only reduces the pollution of the environment caused by coal-based solid waste, but also greatly reduces the production cost of soil improvers, and is suitable for large-scale promotion and use in saline-alkali soil areas.

[0008] Preferably, the weight proportions of raw materials of the soil conditioner prepared from the coal-based solid waste are: 90 parts of coal-based solid waste, 6 parts of inorganic salt materials, 120 parts of pure water, 5 parts of microbial agent fertilizer, and 30 parts of crop straw biochar.

[0009] Preferably, the coal-based solid waste includes: one or more of coal gasification slag, fly ash and coal gangue.

[0010] Preferably, the inorganic salt material includes: one or more of calcium chloride, ferric chloride and aluminum chloride.

[0011] Preferably, the microbial fertilizer comprises: one or more of arbuscular mycorrhizal fungal agents and Bacillus fertilizers.

[0012] Preferably, the Bacillus fertilizer contains one or more of Bacillus subtilis, Bacillus licheniformis, Bacillus megaterium, and Bacillus amyloliquefaciens.

[0013] Preferably, the crop straw biochar is prepared from one or more of rice straw, corn straw, sorghum straw, alfalfa straw, soybean straw, wheat straw, and cotton straw.

[0014] To achieve the above object, the present invention also provides a method for preparing a soil conditioner using coal-based solid waste, comprising:

[0015] S1: The collected coal-based solid waste is magnetically separated, crushed, and passed through a 2 mm sieve;

[0016] S2: adding calcium chloride, ferric chloride or aluminum chloride into pure water to prepare a 0.5-1.0 mol / L calcium chloride solution, ferric chloride solution or aluminum chloride solution;

[0017] S3: Add coal-based solid waste to the above solution, heat to 60-80°C and stir evenly for 1-2h;

[0018] S4: After stirring evenly, filter, and dry the solid matter containing the coal-based solid waste at 100-110° C. for 6-8 hours to obtain modified coal-based solid waste;

[0019] S5: Crush the crop straw and dry it; then perform pyrolysis under anaerobic conditions, maintain it at 250-800°C, and perform pyrolysis for 1-2 hours; after the pyrolysis is completed, cool it to room temperature to prepare different crop straw biochars; then put the obtained biochar into a stirring tank, control the initial pressure to 0.05-0.08MPa, then add 0.5-1.0mol / L nitric acid or hydrochloric acid solution, gradually restore the normal pressure, stir it at normal pressure, filter and dry it, and obtain modified crop straw biochar;

[0020] S6: uniformly mixing the modified coal-based solid waste, the modified crop straw biochar and the microbial agent fertilizer in a weight ratio of 8 to 10:2 to 5:1;

[0021] S7: ball-milling the obtained mixed solid material and passing it through a 2 mm sieve;

[0022] S8: Obtain coal-based solid waste soil conditioner.

[0023] Preferably, in step (5), the obtained biochar is immersed in a 0.5-1.0 mol / L nitric acid or hydrochloric acid solution and stirred for 5-24 hours, filtered, and dried at 60-85° C. to obtain modified crop straw biochar.

[0024] To achieve the above object, the present invention also provides a method for using a soil conditioner prepared using coal-based solid waste, comprising:

[0025] The soil conditioner is applied in saline-alkali soil, evenly spread on the leveled soil surface at one time, and then plowed and irrigated. It is best to use rotary tillage for plowing, and the rotary tillage depth is not less than 30 cm to ensure that the soil conditioner is evenly mixed with the surface soil. The application amount depends on the degree of salinity and alkali, and the amount used is 500-2000kg / mu.

[0026] Advantages of this solution:

[0027] (1) The soil conditioner of the present invention has several raw materials with simple composition, wide sources and low production cost, which can be promoted and used in large-scale saline-alkali soil improvement.

[0028] (2) Magnetic separation pretreatment of coal-based solid waste can remove most of the heavy metals in coal-based solid waste.

[0029] (3) The raw material coal-based solid waste required for the present invention is solid waste. Using it as the main raw material of the soil conditioner can fully solve the problem of solid waste recycling.

[0030] (4) The present invention combines the calcium, iron and / or aluminum and other multivalent cations rich in modified coal-based solid waste with soil organic matter to form a soil binder, thereby promoting the formation of soil aggregates, increasing soil porosity, and improving soil desalination efficiency.

[0031] (5) The modified biochar in the soil conditioner of the present invention effectively absorbs the required acid through a porous structure by a special method. Not only is the overall soil conditioner acidic, but the pH value of the finished soil conditioner is also below 7, which is weakly acidic. After being added to the soil, it can be continuously released and react with carbonate and bicarbonate in saline-alkali soil to neutralize, thereby reducing soil acidity, continuously alleviating soil salinization problems, and increasing soil organic carbon and various nutrient contents.

[0032] (6) The soil conditioner of the present invention not only provides microbial agents for saline-alkali soil, but also utilizes the porous structure of coal-based solid waste to provide favorable conditions for the growth and reproduction of microorganisms, thereby effectively improving saline-alkali soil and promoting plant growth. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The present invention is a schematic flow chart of a method for preparing a soil conditioner using coal-based solid waste according to an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following is further described in detail through specific implementation methods:

[0035] Embodiment 1:

[0036] A soil conditioner prepared from coal-based solid waste, comprising 80 parts by weight of coal-based solid waste, 6 parts by weight of inorganic salt materials, 120 parts by weight of pure water, 1 part by weight of microbial agent fertilizer, and 30 parts by weight of crop straw biochar. Among them, the coal-based solid waste includes: one or more of coal gasification slag, fly ash and coal gangue; the inorganic salt materials include: one or more of calcium chloride, ferric chloride and aluminum chloride; the microbial agent fertilizer includes: one or more of arbuscular mycorrhizal fungi agents and Bacillus fertilizers. Bacillus fertilizers contain one or more of Bacillus subtilis, Bacillus licheniformis, Bacillus megaterium and Bacillus amyloliquefaciens. The crop straw biochar is prepared from one or more of rice straw, corn straw, sorghum straw, alfalfa straw, soybean straw, wheat straw and cotton straw. The microbial agents are all commercially available microbial fertilizers.

[0037] The preparation method is as follows:

[0038] S1: Magnetic separation and crushing of the collected coal-based solid waste. Specifically, the coal-based solid waste is initially crushed by a coarse crusher and then magnetically separated by a high-intensity magnetic separator. After the magnetic separation, the coal-based solid waste is crushed again and passed through a 2 mm sieve.

[0039] S2: Add calcium chloride into pure water to prepare a 1.0 mol / L calcium chloride solution.

[0040] S3: Add coal-based solid waste into the above solution, heat to 80°C and stir evenly for 1 hour at a stirring speed of 100-300 r / min.

[0041] S4: After stirring evenly, filter and dry the solid matter containing coal-based solid waste at 110° C. for 6 h to obtain modified coal-based solid waste.

[0042] S5: Crush the crop straw, dry it, and put it into a carbonization furnace; then pyrolyze it under anaerobic conditions, maintain it at 800℃, and pyrolyze it for 1 hour; after the pyrolysis is completed, cool it to room temperature to prepare different crop straw biochars; then put the obtained biochar into a stirring tank, control the initial pressure to 0.08MPa, immerse it in 1.0mol / L nitric acid solution, gradually restore it to normal pressure, stir it at normal pressure for 24 hours, filter it, and dry it at 85℃ to obtain modified crop straw biochar.

[0043] S6: Evenly mix the modified coal-based solid waste, modified crop straw biochar and microbial fertilizer in a weight ratio of 10:5:1.

[0044] S7: The obtained mixed solid material is ball-milled using a ball mill and passed through a 2 mm sieve.

[0045] S8: Obtain coal-based solid waste soil conditioner.

[0046] The test method of soil conditioner is: apply soil conditioner in saline-alkali soil potted plants, and its application amount is equivalent to 500kg / mu in field application. First, take the original soil for testing of various soil indicators, then mix the soil conditioner and saline-alkali soil evenly, sow 20 selected high-quality alfalfa seeds in the pot, water regularly to maintain the field water holding rate of about 60%, and test various soil indicators after 60 days.

[0047] The test results show that after using the soil conditioner of this embodiment, the bulk density of the soil increased from 1.46 g / cm 3 Reduced to 1.38g / cm 3, pH decreased from 9.80 to 8.87, total salt content decreased from 6.75g / kg to 5.76g / kg, total porosity increased from 33.30% to 39.54%, the proportion of water-stable aggregates increased by 30.88%, organic matter content increased from 5.61g / kg to 7.93g / kg, total nitrogen, available potassium and available phosphorus increased from the original 0.81g / kg, 182.47mg / kg and 4.58mg / kg to 1.12g / kg, 249.17mg / kg and 9.73mg / kg respectively, microbial biomass carbon increased by 40.95%, and the contents of harmful heavy metal elements were lower than the limit values ​​of GB15618-2018 "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)".

[0048] Embodiment 2:

[0049] A soil conditioner prepared from coal-based solid waste, comprising 100 parts by weight of coal-based solid waste, 15 parts by weight of inorganic salt materials, 150 parts by weight of pure water, 10 parts by weight of microbial agent fertilizer, and 50 parts by weight of crop straw biochar. Among them, the coal-based solid waste includes: one or more of coal gasification slag, fly ash and coal gangue; the inorganic salt materials include: one or more of calcium chloride, ferric chloride and aluminum chloride; the microbial agent fertilizer includes: one or more of arbuscular mycorrhizal fungal agents and Bacillus fertilizers. Bacillus fertilizers contain one or more of Bacillus subtilis, Bacillus licheniformis, Bacillus megaterium, and Bacillus amyloliquefaciens. The crop straw biochar is prepared from one or more of rice straw, corn straw, sorghum straw, alfalfa straw, soybean straw, wheat straw, and cotton straw. The microbial agents are all commercially available microbial fertilizers.

[0050] The preparation method is as follows:

[0051] S1: Magnetic separation and crushing of the collected coal-based solid waste. Specifically, the coal-based solid waste is initially crushed by a coarse crusher and then magnetically separated by a high-intensity magnetic separator. After the magnetic separation, the coal-based solid waste is crushed again and passed through a 2 mm sieve.

[0052] S2: Add ferric chloride to pure water to prepare a 0.5 mol / L ferric chloride solution.

[0053] S3: Add coal-based solid waste into the above solution, heat to 60°C and stir evenly for 2 hours at a stirring speed of 100-300 r / min.

[0054] S4: After stirring evenly, filter and dry the solid matter containing coal-based solid waste at 100° C. for 8 h to obtain modified coal-based solid waste.

[0055] S5: Crush the crop straw, dry it, and put it into the carbonization furnace; then pyrolyze it under anaerobic conditions, keep it at 250℃, and pyrolyze it for 2h; after pyrolysis is completed, cool it to room temperature to prepare different crop straw biochars; then put the obtained biochars into a stirring tank, immerse it in a 0.7mol / L nitric acid solution, stir it for 23h, filter it, and dry it at 75℃ to obtain modified crop straw biochars. The initial pressure of the stirring tank is controlled to be 0.07MPa, and after immersion in the nitric acid solution, it gradually returns to normal pressure and stirs at normal pressure.

[0056] S6: Evenly mix the modified coal-based solid waste, modified crop straw biochar and microbial fertilizer in a weight ratio of 8:2:1.

[0057] S7: The obtained mixed solid material is ball-milled using a ball mill and passed through a 2 mm sieve.

[0058] S8: Obtain coal-based solid waste soil conditioner.

[0059] The test method of soil conditioner is: apply soil conditioner in saline-alkali soil potted plants, and the amount of soil conditioner is equivalent to 1000kg / mu for field application. First, take the original soil for testing of various soil indicators, then mix the soil conditioner and saline-alkali soil evenly, sow 20 selected high-quality alfalfa seeds in the pot, water regularly to maintain the field water holding rate of about 60%, and test various soil indicators after 60 days.

[0060] The test results show that after using the soil conditioner of this embodiment, the bulk density of the soil increased from 1.46 g / cm 3 Reduced to 1.33g / cm 3 , pH decreased from 9.80 to 8.62, total salt content decreased from 6.75g / kg to 4.60g / kg, total porosity increased from 33.30% to 40.96%, the proportion of water-stable aggregates increased by 41.74%, organic matter content increased from 5.61g / kg to 8.21g / kg, total nitrogen, available potassium and available phosphorus increased from the original 0.81g / kg, 182.47mg / kg and 4.58mg / kg to 1.31g / kg, 265.96mg / kg and 9.97mg / kg respectively, microbial biomass carbon increased by 57.25%, and the contents of harmful heavy metal elements were lower than the limit values ​​of GB15618-2018 "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)".

[0061] Embodiment 3:

[0062] A soil conditioner prepared from coal-based solid waste, comprising 90 parts by weight of coal-based solid waste, 5 parts by weight of inorganic salt materials, 100 parts by weight of pure water, 5 parts by weight of microbial agent fertilizer, and 20 parts by weight of crop straw biochar. Among them, the coal-based solid waste includes: one or more of coal gasification slag, fly ash and coal gangue; the inorganic salt materials include: one or more of calcium chloride, ferric chloride and aluminum chloride; the microbial agent fertilizer includes: one or more of arbuscular mycorrhizal fungi agents and Bacillus fertilizers. Bacillus fertilizers contain one or more of Bacillus subtilis, Bacillus licheniformis, Bacillus megaterium, and Bacillus amyloliquefaciens. The crop straw biochar is prepared from one or more of rice straw, corn straw, sorghum straw, alfalfa straw, soybean straw, wheat straw, and cotton straw. The microbial agents are all commercially available microbial fertilizers.

[0063] The preparation method is as follows:

[0064] S1: Magnetic separation and crushing of the collected coal-based solid waste. Specifically, the coal-based solid waste is initially crushed by a coarse crusher and then magnetically separated by a high-intensity magnetic separator. After the magnetic separation, the coal-based solid waste is crushed again and passed through a 2 mm sieve.

[0065] S2: Add aluminum chloride into pure water to prepare a 0.7 mol / L aluminum chloride solution.

[0066] S3: Add coal-based solid waste into the above solution, heat to 70°C and stir evenly for 1.5 hours at a stirring speed of 100-300 r / min.

[0067] S4: After stirring evenly, filter and dry the solid matter containing coal-based solid waste at 105° C. for 7.5 h to obtain modified coal-based solid waste.

[0068] S5: Crush the crop straw, dry it, and put it into the carbonization furnace; then pyrolyze it under anaerobic conditions, keep it at 600℃, and pyrolyze it for 1.5h; after pyrolysis, cool it to room temperature to prepare different crop straw biochars; then put the obtained biochar and 0.5mol / L hydrochloric acid solution into a stirring tank and stir it for 5h, filter it, and dry it at 60℃ to obtain modified crop straw biochar. The initial pressure of the stirring tank is controlled to 0.06MPa, and after immersing in the hydrochloric acid solution, it gradually returns to normal pressure and stirs at normal pressure.

[0069] S6: Evenly mix the modified coal-based solid waste, modified crop straw biochar and microbial fertilizer in a weight ratio of 9:4:1.

[0070] S7: The obtained mixed solid material is ball-milled using a ball mill and passed through a 2 mm sieve.

[0071] S8: Obtain coal-based solid waste soil conditioner.

[0072] The test method of soil conditioner is: apply soil conditioner in saline-alkali soil potted plants, and its application amount is equivalent to 1500kg / mu in field application. First, take the original soil for testing of various soil indicators, then mix the soil conditioner and saline-alkali soil evenly, sow 20 selected high-quality alfalfa seeds in the pot, water regularly to maintain the field water holding rate of about 60%, and test various soil indicators after 60 days.

[0073] The test results show that after using the soil conditioner of this embodiment, the bulk density of the soil increased from 1.46 g / cm 3 Reduced to 1.30g / cm 3 , pH decreased from 9.80 to 8.57, total salt content decreased from 6.75g / kg to 3.77g / kg, total porosity increased from 33.30% to 41.77%, the proportion of water-stable aggregates increased by 41.84%, organic matter content increased from 5.61g / kg to 8.99g / kg, total nitrogen, available potassium and available phosphorus increased from 0.81g / kg, 182.47mg / kg and 4.58mg / kg to 1.40g / kg, 277.10mg / kg and 10.19mg / kg respectively, microbial biomass carbon increased by 58.76%, and the contents of harmful heavy metal elements were lower than the limit values ​​of GB15618-2018 "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)".

[0074] Comparative Example 1:

[0075] The difference between this comparative example and Example 1 is that in this comparative example, steps S2, S3, and S4 are not performed to modify the coal-based solid waste, and the coal-based solid waste screened in step (1) is directly mixed with the modified crop straw biochar and microbial agent fertilizer to prepare a coal-based solid waste soil conditioner.

[0076] The test method is the same as that of Example 1, and the test results are:

[0077] After using the soil of this comparative example to improve the substrate, the bulk density of the soil increased from 1.46 g / cm 3 Reduced to 1.43g / cm 3, pH decreased from 9.80 to 9.24, total salt content decreased from 6.75g / kg to 6.56g / kg, total porosity increased from 33.30% to 39.17%, the proportion of water-stable aggregates increased by 10.88%, organic matter content increased from 5.61g / kg to 6.95g / kg, total nitrogen, available potassium and available phosphorus increased from the original 0.81g / kg, 182.47mg / kg and 4.58mg / kg to 1.10g / kg, 250.33mg / kg and 9.69mg / kg respectively, microbial biomass carbon increased by 37.12%, and the contents of harmful elements were all lower than the limit values ​​of GB15618-2018 "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)".

[0078] Comparative Example 2:

[0079] The difference between this comparative example and Example 1 is that in this comparative example, step S5 of immersing the obtained biochar in a 0.5-1.0 mol / L nitric acid or hydrochloric acid solution and stirring is not performed to modify the crop straw biochar, and the modified coal-based solid waste, unmodified crop straw biochar and microbial agent fertilizer are evenly mixed to prepare a coal-based solid waste soil conditioner.

[0080] The test method is the same as that of Example 1, and the test results are:

[0081] After using the soil of this comparative example to improve the substrate, the bulk density of the soil increased from 1.46 g / cm 3 Reduced to 1.31g / cm 3 , pH decreased from 9.80 to 9.77, total salt content decreased from 6.75g / kg to 4.72g / kg, total porosity increased from 33.30% to 37.67%, the proportion of water-stable aggregates increased by 40.73%, organic matter content increased from 5.61g / kg to 7.10g / kg, total nitrogen, available potassium and available phosphorus increased from 0.81g / kg, 182.47mg / kg and 4.58mg / kg to 1.13g / kg, 229.12mg / kg and 9.48mg / kg respectively, microbial biomass carbon increased by 19.72%, and the contents of harmful elements were all lower than the limit values ​​of GB15618-2018 "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)".

[0082] Comparative Example 3:

[0083] The difference between this comparative example and Example 1 is that in step S1 of this comparative example, the coal-based solid waste is sieved through a 4 mm sieve after magnetic separation.

[0084] The test method is the same as that of Example 1, and the test results are:

[0085] After using the soil of this comparative example to improve the substrate, the bulk density of the soil increased from 1.46 g / cm 3 Reduced to 1.38g / cm 3 , pH decreased from 9.80 to 8.96, total salt content decreased from 6.75g / kg to 4.42g / kg, total porosity increased from 33.30% to 38.59%, the proportion of water-stable aggregates increased by 24.61%, organic matter content increased from 5.61g / kg to 9.07g / kg, total nitrogen, available potassium and available phosphorus increased from the original 0.81g / kg, 182.47mg / kg and 4.58mg / kg to 1.31g / kg, 260.46mg / kg and 9.16mg / kg respectively, microbial biomass carbon increased by 36.08%, and the contents of harmful elements were lower than the limit values ​​of GB15618-2018 "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)".

[0086] It can be seen from the above embodiments and comparative examples that after applying the soil conditioner of the present invention, the bulk density, pH value and total salt content of the saline-alkali soil all have a significant downward trend, while the total porosity, water-stable aggregate ratio, organic matter content, nitrogen, phosphorus and potassium content, and microbial biomass carbon content are significantly increased, and the content of harmful elements is lower than the limit value of GB15618-2018 "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)"; however, when the coal-based solid waste is not modified or a large-aperture sieve is used for sieving in step S1, the final soil conditioner has a small increase in the total porosity and water-stable aggregate ratio of the saline-alkali soil, indicating that the modified coal-based solid waste in the soil conditioner of the present invention is loaded with Multivalent cations can promote the formation of soil aggregates, replace sodium ions adsorbed by colloids, and promote soil desalination. Therefore, the role of modified coal-based solid waste is mainly reflected in improving the structure of saline-alkali soil and promoting desalination. Without acid modification of crop straw biochar, the prepared soil conditioner has little effect on the pH value of saline-alkali soil, and the increase in organic carbon content and microbial biomass carbon content is very small, indicating that the pH value of the acid-modified biochar in the soil conditioner of the present invention is very low, which can neutralize the alkaline ions in saline-alkali soil, and is more suitable for the growth and reproduction of microorganisms, and promotes the growth and reproduction of microorganisms. Microbial agents can be used as activators to promote the release and conversion of nutrients in coal-based solid waste and biochar.

[0087] Other similar reagents, and the selection of similar reaction parameters, those skilled in the art can determine the above-mentioned only embodiments of the present invention according to common knowledge, and the common knowledge such as the known specific structure, characteristics and reactant ratio in the scheme is not described too much here. It should be pointed out that for those skilled in the art, without departing from the concept of the present invention, several deformations and improvements can also be made, such as simply adjusting the selection of parameters within or near the specified parameter range, which should also be regarded as the protection scope of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent. The protection scope required by this application shall be based on the content of its claims, and the specific implementation methods in the specification and other records can be used to explain the content of the claims.

Claims

1. A soil conditioner prepared from coal-based solid waste, characterized in that: The invention comprises the following raw materials in parts by weight: 80 to 100 parts of coal-based solid waste, 5 to 15 parts of inorganic salt materials, 100 to 150 parts of pure water, 1 to 10 parts of microbial agent fertilizer, and 20 to 50 parts of biochar, wherein the biochar is acid-modified.

2. The soil conditioner prepared from coal-based solid waste according to claim 1, characterized in that: The weight proportions of the raw materials are: 90 parts of coal-based solid waste, 6 parts of inorganic salt materials, 120 parts of pure water, 5 parts of microbial fertilizer, and 30 parts of crop straw biochar.

3. The soil conditioner prepared from coal-based solid waste according to claim 1, characterized in that: The coal-based solid waste includes: one or more of coal gasification slag, fly ash and coal gangue.

4. The soil conditioner prepared from coal-based solid waste according to claim 1, characterized in that: The inorganic salt material includes: one or more of calcium chloride, ferric chloride and aluminum chloride.

5. The soil conditioner prepared from coal-based solid waste according to claim 1, characterized in that: The microbial fertilizer comprises: one or more of arbuscular mycorrhizal fungal fertilizer and bacillus fertilizer.

6. The soil conditioner prepared from coal-based solid waste according to claim 5, characterized in that: The Bacillus fertilizer contains one or more of Bacillus subtilis, Bacillus licheniformis, Bacillus megaterium and Bacillus amyloliquefaciens.

7. The soil conditioner prepared from coal-based solid waste according to claim 1, characterized in that: The crop straw biochar is prepared from one or more of rice straw, corn straw, sorghum straw, alfalfa straw, soybean straw, wheat straw, and cotton straw.

8. A method for preparing a soil conditioner using coal-based solid waste, characterized in that: include: S1: The collected coal-based solid waste is magnetically separated, crushed, and passed through a 2 mm sieve; S2: adding calcium chloride, ferric chloride or aluminum chloride into pure water to prepare 0.5-1.0 mol / L calcium chloride solution, ferric chloride solution or aluminum chloride solution respectively; S3: Add coal-based solid waste to the solution prepared in S2, heat to 60-80°C and stir evenly for 1-2h; S4: After stirring evenly, filter, and dry the solid matter containing the coal-based solid waste at 100-110° C. for 6-8 hours to obtain modified coal-based solid waste; S5: Crush the crop straw and dry it; then perform pyrolysis under anaerobic conditions, maintain it at 250-800°C, and perform pyrolysis for 1-2 hours; after the pyrolysis is completed, cool it to room temperature to prepare crop straw biochar; then put the obtained biochar into a stirring tank, control the initial pressure to 0.05-0.08MPa, then add 0.5-1.0mol / L nitric acid or hydrochloric acid solution, then gradually restore the normal pressure for stirring, filter and dry, and obtain modified crop straw biochar; S6: uniformly mixing the modified coal-based solid waste, the modified crop straw biochar and the microbial agent fertilizer in a weight ratio of 8 to 10:2 to 5:1; S7: ball-milling the obtained mixed solid material and passing it through a 2 mm sieve; S8: Obtain coal-based solid waste soil conditioner.

9. The method for preparing a soil conditioner using coal-based solid waste according to claim 8, characterized in that: The stirring time of step (5) is 5 to 24 hours, and the drying temperature is 60 to 85°C.

10. A soil conditioner prepared from coal-based solid waste according to any one of claims 1 to 7, characterized in that: The soil conditioner is applied in saline-alkali soil, and is evenly spread on the leveled soil surface at one time, and then plowed and irrigated. The amount used is 500-2000 kg / mu.

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