Salt soil repairing agent and preparation method thereof

Abstract

The invention discloses a saline soil remediation agent and a preparation method thereof, and belongs to the field of soil remediation. According to the method, residual carbonaceous substances in the tailing slime are subjected to pore forming through a hydrothermal method by utilizing a saline soil leaching concentrated solution, the tailing slime, gasified ash, livestock and poultry manure, biomass, coal gangue, low-rank coal slime, plant ash, clay minerals, oxalic acid and a biomass binder, and meanwhile, the pore forming efficiency of the residual carbonaceous substances in the tailing slime in the hydrothermal process is promoted by utilizing the saline soil leaching concentrated solution; through solid-liquid separation treatment of the livestock and poultry manure, the fermentation efficiency is fully exerted, and the ratio of fixed organic matters to free organic matters is adjusted. The method is simple in steps and convenient to use, and the repairing agent for repairing saline soil is efficiently prepared.

Description

Technical Field

[0001] The invention belongs to the field of soil remediation, and specifically relates to a saline soil remediation agent and a preparation method thereof. Background Art

[0002] Salt accumulates in the surface layer of saline soil, and the high salt content will cause physiological dehydration of plants, which is not conducive to the greening and development of saline soil. In addition to physical and chemical methods such as deep plowing and loosening the soil, laying isolation layers, irrigation and drainage, and applying chemical modifiers, existing saline soil treatment technologies also include biological methods such as cultivating salt-tolerant crops and cultivating green manure. In the arid and rainless areas of the northwest, due to geographical and climatic limitations, the available saline soil remediation methods are more challenging. Soil remediation agents and organic fertilizers belong to a physical and chemical method, which has attracted widespread attention in recent years due to their strong feasibility and quick results. Most of the existing soil remediation agents use straw and livestock and poultry manure compost as the main source of organic fertilizer and humic acid. The direct use of fly ash and tailings cannot give full play to their physical structure and high humic acid content. There are problems of high cost, neglect of heavy metal pollution and insufficient performance.

[0003] Prior art CN112210382A discloses a farmland heavy metal contaminated soil repair agent and a preparation method thereof, wherein the repair agent is prepared from the following raw materials: the raw materials are in the following weight proportions: 25-30 parts of plant ash, 10-12 parts of lime, 2-3 parts of phosphate, 3-5 parts of soil humic acid, 6-8 parts of phosphate fertilizer, 1-3 parts of ethylenediaminetetraacetic acid, 2-4 parts of sodium lauryl sulfate, 3-5 parts of organic acid, 4-8 parts of calcium carbide, 2-3 parts of multifunctional auxiliary agent, 3-5 parts of chelating agent, and 45-55 parts of deionized water; the present invention adopts phosphate, soil humic acid, ethylenediaminetetraacetic acid, sodium lauryl sulfate and organic acid as auxiliary materials, which can only remove heavy metals in the soil, but cannot provide hydrophilic organic and inorganic pores with richer pores to improve fertilizer retention and delay salt enrichment, and cannot improve the water retention capacity of the soil. Summary of the invention

[0004] In view of the shortcomings of the existing technology, a saline soil remediation agent and a preparation method thereof are provided, wherein residual carbon in tailings slime is used for hydrothermal pore formation, and the saline soil leaching concentrate recovered from the saline soil leaching and treatment area is used to promote the hydrothermal pore formation efficiency; porous tailings slime and clay minerals are used to enrich the pore structure of the saline soil remediation agent to provide a large number of adsorption sites for water, organic matter and inorganic salts; through the solid-liquid separation and treatment of livestock and poultry manure, the fermentation efficiency is fully utilized, and the proportion of solid organic matter and free organic matter is adjusted; the waste gas produced by the comprehensive treatment process is used to generate fuel, fix gaseous nitrogen elements and reduce external emissions.

[0005] To achieve the above technical purpose, the present invention relates to a salt soil repair agent, comprising the following weight ratios: 0.5-1.5% of salt soil leaching concentrate, 25-35% of tailings slime, 3-7% of gasification ash, 20-35% of livestock and poultry manure, 20-30% of biomass, 5-10% of coal gangue, 10-15% of low-rank coal slime, 2-10% of plant ash, 5-9% of clay minerals, 1-5% of oxalic acid, and 2-4% of biomass binder;

[0006] The hydrothermal method is used to create pores for the residual carbon in the tailings slime. At the same time, the salt soil leaching concentrate is used to promote the pore-forming efficiency of the residual carbon in the tailings slime during the hydrothermal process to generate a salt soil repair agent. Through the solid-liquid separation and treatment of livestock and poultry manure, the fermentation efficiency is fully utilized and the proportion of fixed organic matter and free organic matter is adjusted.

[0007] A method for preparing a saline soil repair agent, the specific steps are as follows:

[0008] d. Collect the salt soil leaching concentrate in the salt soil leaching treatment area, add the salt soil leaching concentrate and the tail coal slime / gasification ash mixture with a weight ratio of 5:1 into the hydrothermal reactor for hydrothermal reaction to generate hydrothermal reaction products and reaction gas, feed the hydrothermal reaction products into the plate and frame filter press for solid-liquid separation, separate the hydrothermal reaction mixture and the porous tail coal slime, feed the porous tail coal slime into the porous tail coal slime bin, feed the hydrothermal reaction mixture into the separator for oil-water separation, generate coal tar through coking coal hydrothermal, use the coal tar as coal slime flotation agent or other industrial raw materials, and feed the hydrothermal reaction liquid separated from the oil and water into the tail liquid pool;

[0009] e. Collect livestock and poultry manure and feed it into a dehydration screen for solid-liquid separation, separate livestock and poultry manure water and livestock and poultry manure solid phase, feed the livestock and poultry manure water into an anaerobic fermentation tank for anaerobic fermentation to generate fermentation gas and fermentation products, the fermentation products are rich in free organic matter, the livestock and poultry manure solid phase is mixed with agricultural biomass crushed material and then added to a tank composting device to produce a compost product containing solid organic matter;

[0010] f. Feed the gangue into the crusher to obtain crusher discharge with a particle size of less than 2 mm, and then feed the crusher discharge into a vibrating arc screen Φ2 mm for screening, wherein the vibrating arc screen Φ2 mm vibrating screen screen material continues to be fed into the crusher for crushing, and the fine-grained gangue screened by the vibrating arc screen Φ2 mm is fed into the reaction tank;

[0011] Add low-rank coal sludge with a weight ratio of 1:0.2 and dilute nitric acid with a volume concentration of 7% into a nitrification tank for nitrification to generate nitrated low-rank coal, feed the nitrated low-rank coal into a reaction tank, and then feed plant ash into the reaction tank, the weight ratio of nitrated low-rank coal to plant ash is 10:3;

[0012] The low-rank coal slime and dilute nitric acid are mixed to undergo nitrification to increase the humic acid content in the nitrated low-rank coal. The nitrated low-rank coal, plant ash and fine-grained coal gangue are mixed and reacted in a reaction tank to neutralize the residual nitric acid in the reaction tank, generate various free inorganic ions, and obtain a reaction tank product.

[0013] d. The porous tailings slime, fermentation products, compost products and reaction tank products are added to a stirrer and stirred to obtain an organic mixture, and the organic mixture is added to a composting bin for composting to obtain decomposed organic matter;

[0014] Clay minerals and biomass binders are added to decomposed organic matter, and then mixed and stirred with a stirrer to obtain a granulation matrix, and then a granulator is used to produce a saline soil repair agent. The weight ratio of the decomposed organic matter, the clay minerals and the biomass binder is 20:2:1.

[0015] Furthermore, the agricultural biomass crushed material is straw crushed by a crusher.

[0016] Furthermore, the hydrothermal reaction gas generated by the hydrothermal reactor and the fermentation gas produced by the anaerobic fermentation tank are fed into the absorption tower, and oxalic acid and clean water are added to the absorption tower as needed. The absorption tower generates usable fuel gas and absorption tower waste liquid, and the absorption tower waste liquid is fed into the tail liquid pool.

[0017] Furthermore, the hydrothermal reaction liquid in the tailings pool and the waste liquid in the absorption tower are mixed to form a mixed tailings liquid, which is mixed with the porous tailings slime, fermentation products, compost products, and reaction pool products and stirred together and fed into the composting bin.

[0018] Furthermore, the product of the hydrothermal reaction is porous tailings sludge. The porous tailings sludge, hydrothermal reaction mixture, absorption tower waste liquid, nitrified low-rank coal, and fermentation products are all weakly acidic, wood ash is weakly alkaline, and the compost product is neutral. Under comprehensive formulation, the final pH value of the saline soil remediation agent should be adjusted to neutral or weakly acidic.

[0019] A system used in a preparation method, comprising a hydrothermal reactor, a plate-frame filter press, a separator, a porous tail coal slime bin, an absorption tower, a tail liquid pool, a dehydration screen, an anaerobic fermentation tank, a pulverizer, a tank composting machine, a nitrification tank, a crusher, a vibrating arc screen Φ2 mm, a reaction tank, a stirrer, a composting bin, a stirrer, a granulator, and a clear water tank;

[0020] The inlet of the hydrothermal reactor for treating the tail coal slime / gasification ash mixture is connected to the separator, the outlet of the hydrothermal reactor is connected to the plate-frame filter press, the discharge port of the plate-frame filter press is connected to the porous tail coal slime bin, the liquid outlet is connected to the separator, the coal tar separated by the separator is not used, and the separated hydrothermal reaction liquid pipeline is connected to the tail liquid pool;

[0021] The clear water tank pipeline is connected to the absorption tower, the hydrothermal reaction gas outlet of the hydrothermal reactor is connected to the absorption tower inlet, the exhaust port of the absorption tower outputs the fuel gas, and the liquid discharge port of the absorption tower is connected to the tail liquid pool;

[0022] The discharge port of the dehydration screen for processing livestock and poultry manure is connected to the anaerobic fermentation tank, and the hydrothermal reaction gas outlet of the hydrothermal reactor is also connected to the anaerobic fermentation tank; the outlet of the pulverizer for processing biomass straw and the discharge port of the dehydration screen are both connected to the inlet of the tank composting machine;

[0023] The outlet of the nitrification tank for processing low-rank coal slime is connected to the reaction tank through a pipeline, and the crusher for processing coal gangue is also connected to the reaction tank through the outlet of the vibrating arc screen Φ2mm undersize;

[0024] The outlet of the porous tail coal slime bin is connected to the inlet of the agitator through a conveyor belt, and the tail liquid pool is connected to the inlet of the agitator through a pump; the fermentation product discharge outlet of the anaerobic fermentation tank is connected to the inlet of the agitator through a pipeline, the outlet of the tank composter is connected to the inlet of the agitator, the outlet of the reaction tank is connected to the inlet of the agitator, and the outlet of the agitator is connected to the composting bin;

[0025] The discharge port of the composting bin is connected to the agitator, and the discharge port of the agitator is connected to the granulator.

[0026] Beneficial effects: The present invention proposes a saline soil repair agent and a production method thereof, which realizes the synthesis of a saline soil repair agent capable of retaining water and fertilizer, passivating soil heavy metals, reducing soil salinity, and improving soil pore structure according to hydrothermal reaction of tailings slime, solid-liquid separation and disposal of biomass, oxalic acid loading modification, and nitrification of low-rank coal. The comprehensive utilization of coal-based solid waste and agricultural solid waste is achieved, and the advantages of the invention are as follows:

[0027] a. The pore expansion promoting ions needed to promote pore formation in hydrothermal reactions come from saline soil leaching concentrate, which will reduce the additional salt added to the land and the salt content in the soil, and also reduce the materials needed for hydrothermal reactions.

[0028] b. Nitration of low-rank coal provides additional sources of organic matter and humic acid, making the process more flexible and can be used as a short-term source of organic matter when livestock and poultry manure and straw are in short supply.

[0029] c. The minerals in the tailings slime, gasification ash, coal gangue and wood ash provide the necessary calcium, magnesium, potassium, silicon, iron and other minerals and trace elements for plant growth after reaction. Natural inorganic fertilizers and organic fertilizers improve soil fertility.

[0030] d. Porous tailings slime and clay minerals provide hydrophilic surfaces and abundant hydrophilic pores, and provide hydrophilic pores of various shapes and sizes, which improve the pore composition of saline soil remediation agents and increase the ability of soil ion adsorption and exchange. A large number of hydrophilic surfaces and pores provide adsorption sites for water and nutrients, enhance the water and fertilizer retention capacity of saline soil, and slow down water evaporation and salt accumulation on the soil surface.

[0031] e. The small molecule acid produced by oxalic acid and hydrothermal reaction is loaded in a porous matrix. After the remediation agent is applied, it can chelate with the heavy metal ions in the soil, passivate the heavy metal ions in the soil, and reduce the risk of uncontrolled heavy metal pollution in the soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a process flow chart of the preparation method of the salt soil repair agent of the present invention;

[0033] Figure 2 It is an equipment connection diagram of the method for preparing the saline soil repair agent of the present invention.

[0034] In the figure: 1- tail coal slime / gasification ash mixture, 2- salt soil leaching concentrate, 3- hydrothermal reaction gas, 4- hydrothermal reaction product, 5- hydrothermal reaction mixed liquid, 6- porous tail coal slime, 7- coal tar, 8- hydrothermal reaction liquid, 9- oxalic acid, 10- clean water, 11- fuel gas, 12- absorption tower waste liquid, 13- mixed tail liquid, 14- livestock and poultry manure, 15- livestock and poultry manure water, 16- livestock and poultry manure solid phase, 17- fermentation gas, 18- fermentation product, 19- straw stalks, etc., 20-agricultural biomass crushed materials, 21-compost products, 22-wood ash, 23-low-rank coal slime, 24-dilute nitric acid, 25-nitrified low-rank coal, 26-coal gangue, 27-crusher discharge, 28-vibrating screen oversize, 29-fine-grained coal gangue, 30-reaction tank products, 31-clay minerals, 32-biomass binder, 33-organic matter mixture, 34-decomposed organic matter, 35-granulation matrix, 36-saline soil repair agent.

[0035] A-hydrothermal reactor, B-plate and frame filter press, C-separator, D-porous tailings slime bin, E-absorption tower, F-tailings pool, G-dewatering screen, H-anaerobic fermentation tank, I-crusher, J-tank composter, K-nitrification tank, L-crusher, M-vibrating arc screen Φ2mm, N-reaction tank, O-mixer, P-maturity bin, Q-mixer, R-granulator, S-clear water tank, Z-pump. DETAILED DESCRIPTION

[0036] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings:

[0037] like Figure 1 As shown in Figure 2, the present invention discloses a method for preparing a saline soil repair agent by machine, which is as follows:

[0038] Coal-based organic matter treatment: The treatment of coal-based organic matter includes nitration of low-rank coal slime using porous tailing slime / gasification ash as raw materials and low-rank coal slime as raw materials. Preparation of porous tailing slime: The tailing slime / gasification ash mixture 1 and the salt soil leaching concentrate 2 pass through the hydrothermal reactor A to produce hydrothermal reaction gas 3 and hydrothermal reaction product 4. The hydrothermal reaction product 4 passes through a plate and frame filter press for solid-liquid separation to obtain a hydrothermal reaction mixture 5 and porous tailing slime 6. The porous tailing slime 6 enters the porous tailing slime bin D. The hydrothermal reaction mixture 5 passes through a separator C to obtain coal tar 7 and hydrothermal reaction liquid 8. Coal tar 7 is a by-product. The hydrothermal reaction liquid enters the tail liquid pool F. Nitrification of low-rank coal slime: After the low-rank coal slime 23 and dilute nitric acid 24 undergo an oxidation reaction in the nitration tank K, the digested nitrated low-rank coal 25 is obtained. The nitrated low-rank coal 25 enters the reaction tank N for further reaction to remove the residual dilute nitric acid 24.

[0039] Biological organic matter treatment: Biological organic matter includes livestock and poultry manure 14 and straw 19. The livestock and poultry manure 14 passes through the dehydration screen G to achieve solid-liquid separation to obtain livestock and poultry manure water 15 under the screen and livestock and poultry manure solid phase 16 on the screen. The livestock and poultry manure water 15 enters the anaerobic fermentation tank H for anaerobic fermentation to obtain fermentation gas 17 and fermentation product 18. The agricultural biomass crushed material 20 obtained by the straw 19 passes through the pulverizer I and the livestock and poultry manure 16 is aerobically composted in the tank composter J to obtain a compost product 21.

[0040] Production gas treatment: The hydrothermal reaction gas 3 and the fermentation gas 17 enter the absorption tower E, and are absorbed by the absorption tower supplementary water 10 and the oxalic acid 9 to obtain the purified fuel gas 11 and the absorption tower waste liquid 12, and the absorption tower waste liquid enters the tail liquid pool F.

[0041] Preparation of nitrification matrix: The coal gangue 26 passes through the crusher L to obtain the crusher discharge 27. The crusher discharge 27 passes through the vibrating screen Φ2mm M and the vibrating screen oversize 28 is returned to the crusher L for further crushing. The vibrating screen Φ2mm P undersize is fine-grained coal gangue 29. The fine-grained coal gangue 29, nitrated low-rank coal 25 and wood ash / fly ash mixture 22 neutralize the residual dilute nitric acid in the reaction tank N and produce some free mineral ions to obtain the reaction tank product 30.

[0042] Composting and molding of salt soil repair agent: the mixed tail liquid 13, porous tail coal slime 6, fermentation product 18 and compost product 21, and reaction tank product 30 are mixed by a stirrer O to obtain an organic mixture 33, and the organic mixture 33 enters the composting bin P for composting to obtain decomposed organic matter 34, and the decomposed organic matter 34, clay mineral 31 and polymer binder 32 are mixed in a stirrer Q to obtain a granulation matrix 35, and the granulation matrix 35 passes through a granulator R to obtain a salt soil repair agent 36.

[0043] Nitrification of low-rank coal sludge increases the flexibility of the system. Its main purpose is to provide a means to flexibly regulate the content of organic matter and humic acid in saline soil remediation agents. In the case of insufficient supply of straw or livestock and poultry manure, nitrification of low-rank coal can provide a part of the humic acid source.

[0044] Example

[0045] like Figure 2 As shown, a system for preparing a saline soil repair agent comprises a hydrothermal reactor A, a plate and frame filter press B, a separator C, a porous tail coal slime bin D, an absorption tower E, a tail liquid pool F, a dehydration screen G, an anaerobic fermentation tank H, a pulverizer I, a tank composting device J, a nitrification tank K, a crusher L, a vibrating arc screen Φ2 mm M, a reaction tank N, a stirrer O, a composting bin P, a stirrer Q, a granulator R, and a clear water tank S;

[0046] The inlet of the hydrothermal reactor A for treating the tail coal slime / gasification ash mixture is connected to the separator C, the outlet of the hydrothermal reactor A is connected to the plate-frame filter press B, the discharge port of the plate-frame filter press B is connected to the porous tail coal slime bin D, the liquid outlet is connected to the separator C, the coal tar separated by the separator C is not used, and the separated hydrothermal reaction liquid pipeline is connected to the tail liquid pool F;

[0047] The clear water tank S pipeline is connected to the absorption tower E, the hydrothermal reaction gas outlet of the hydrothermal reactor A is connected to the absorption tower E inlet, the exhaust port of the absorption tower E outputs the fuel gas, and the liquid discharge port of the absorption tower E is connected to the tail liquid tank F;

[0048] The discharge port of the dehydration screen G for processing livestock and poultry manure 14 is connected to the anaerobic fermentation tank H, and the hydrothermal reaction gas outlet of the hydrothermal reactor A is also connected to the anaerobic fermentation tank H; the outlet of the pulverizer I for processing biomass straw and the discharge port of the dehydration screen G are both connected to the inlet of the tank composter J;

[0049] The outlet of the nitrification tank K for processing low-rank coal slime is connected to the reaction tank N through a pipeline, and the crusher L for processing coal gangue is also connected to the reaction tank N through the outlet of the vibrating arc screen Φ2mm M;

[0050] The outlet of the porous tail coal slime bin D is connected to the inlet of the agitator O through a conveyor belt, and the tail liquid pool F is connected to the inlet of the agitator O through a pump Z; the fermentation product discharge outlet of the anaerobic fermentation tank H is connected to the inlet of the agitator O through a pipeline, the outlet of the tank composter J is connected to the inlet of the agitator O, the outlet of the reaction tank N is connected to the inlet of the agitator O, and the outlet of the agitator O is connected to the decomposition bin P;

[0051] The discharge port of the composting bin P is connected to the agitator Q, and clay minerals 31 and biomass binder 32 are added to the agitator Q. Finally, the discharge port of the agitator Q is connected to the granulator R to produce the salt soil repair agent 36.

Claims

1. A saline soil repair agent, characterized in that: The invention comprises the following components in weight ratio: 0.5-1.5% of saline soil leaching concentrate, 25-35% of tailings slime, 3-7% of gasification ash, 20-35% of livestock and poultry manure, 20-30% of biomass, 5-10% of coal gangue, 10-15% of low-rank coal slime, 2-10% of plant ash, 5-9% of clay minerals, 1-5% of oxalic acid, and 2-4% of biomass binder; The hydrothermal method is used to create pores for the residual carbon in the tailings slime. At the same time, the salt soil leaching concentrate is used to promote the pore-forming efficiency of the residual carbon in the tailings slime during the hydrothermal process to generate a salt soil repair agent. Through the solid-liquid separation and treatment of livestock and poultry manure, the fermentation efficiency is fully utilized and the proportion of fixed organic matter and free organic matter is adjusted.

2. A method for preparing the saline soil repair agent as claimed in claim 1, characterized in that: The specific steps are as follows: a. Collect the salt soil leaching concentrate (2) in the salt soil leaching treatment area, add the salt soil leaching concentrate (2) and the tail coal slime / gasification ash mixture (1) with a weight ratio of 5:1 into the hydrothermal reactor (A) for hydrothermal reaction to generate hydrothermal reaction products (4) and reaction gas (3), the hydrothermal reaction products (4) are fed into the plate and frame filter press (B) for solid-liquid separation, and the hydrothermal reaction mixture (5) and the porous tail coal slime (6) are separated, the porous tail coal slime (6) is fed into the porous tail coal slime bin (D), the hydrothermal reaction mixture (5) is fed into the separator (C) for oil-water separation, and coal tar is generated by coking coal hydrothermal (7), and the coal tar is used as a coal slime flotation agent or other industrial raw materials. The hydrothermal reaction liquid (8) separated from the oil and water is fed into the tail liquid pool (F); b. Collecting livestock and poultry manure (14) and feeding it to a dewatering screen (G) for solid-liquid separation, separating livestock and poultry manure water (15) and livestock and poultry manure solid phase (16), feeding the livestock and poultry manure water (15) to an anaerobic fermentation tank (H) for anaerobic fermentation to generate fermentation gas (17) and fermentation product (18), wherein the fermentation product (18) is rich in free organic matter, and mixing the livestock and poultry manure solid phase (16) with the agricultural biomass crushed material (20) and adding it to a tank composting device (J) to produce a compost product (21) containing solid organic matter; c. The gangue (26) is fed into a crusher (L) for crushing to obtain a crusher discharge (27) with a particle size of less than 2 mm, and then the crusher discharge (27) is fed into a vibrating arc screen Φ2 mm (M) for screening, wherein the vibrating screen oversize (28) of the vibrating arc screen Φ2 mm (M) is further fed into the crusher (L) for crushing, and the fine-grained gangue (29) screened out by the vibrating arc screen Φ2 mm (M) is fed into a reaction tank (N); Adding low-rank coal sludge (23) with a weight ratio of 1:0.2 and dilute nitric acid (24) with a volume concentration of 7% to a nitrification tank (K) for nitrification to generate nitrated low-rank coal (25), feeding the nitrated low-rank coal (25) into a reaction tank (N), and then feeding plant ash (22) into the reaction tank (N), wherein the weight ratio of the nitrated low-rank coal (25) to the plant ash (22) is 10:3; The low-rank coal sludge (23) and the dilute nitric acid (24) are mixed to undergo nitrification to increase the humic acid content in the nitrated low-rank coal (25); the nitrated low-rank coal (25), the plant ash (22) and the fine-grained coal gangue (29) are mixed and reacted in a reaction tank (N) to neutralize the nitric acid remaining in the reaction tank (N) to generate various free inorganic ions, and obtain a reaction tank product (30); d. The porous tailings slime (6), fermentation product (18), compost product (21) and reaction tank product (30) are added to a stirrer (Q) for stirring to obtain an organic matter mixture (33), and the organic matter mixture (33) is added to a composting bin (P) for composting to obtain a decomposed organic matter (34); Clay minerals (31) and biomass binder (32) are added to decomposed organic matter (34), and the mixture is mixed and stirred using a stirrer (Q) to obtain a granulation matrix (35), and then a granulator (R) is used to produce a saline soil repair agent (36). The weight ratio of the decomposed organic matter (34), the clay minerals (31) and the biomass binder (32) is 20:2:

1.

3. The method for preparing the saline soil repair agent according to claim 2, characterized in that: The agricultural biomass crushed material (20) is straw (19) crushed by a crusher (I).

4. The method for preparing the saline soil repair agent according to claim 2, characterized in that: The hydrothermal reaction gas (3) generated by the hydrothermal reactor (A) and the fermentation gas (17) generated by the anaerobic fermentation tank (H) are fed into the absorption tower (E), and oxalic acid (9) and clean water (10) are added to the absorption tower (E) as needed. The absorption tower (E) generates usable fuel gas (11) and absorption tower waste liquid (12), and the absorption tower waste liquid (12) is fed into the tail liquid pool (F).

5. The method for preparing the saline soil repairing agent according to claim 4, characterized in that: The hydrothermal reaction liquid (8) in the tail liquid pool (F) and the waste liquid (12) from the absorption tower are mixed to form a mixed tail liquid (13), which is mixed with the porous tail coal sludge (6), the fermentation product (18), the compost product (21), and the reaction pool product (30) and stirred and fed into the composting bin (P).

6. The method for preparing the saline soil repair agent according to claim 3, characterized in that: The hydrothermal reaction product (4) is porous tailings sludge. The porous tailings sludge, the hydrothermal reaction mixture (5), the absorption tower waste liquid (12), the nitrified low-rank coal (25), and the fermentation product (18) are all weakly acidic. The wood ash (22) is weakly alkaline. The compost product (21) is neutral. Under comprehensive preparation, the final pH value of the saline soil repair agent should be adjusted to neutral or weakly acidic.

7. A system for use in the preparation method according to claim 2, characterized in that it includes a hydrothermal reactor (A), a plate and frame filter press (B), a separator (C), a porous tailings slime bin (D), an absorption tower (E), a tailings pool (F), a dewatering screen (G), an anaerobic fermentation tank (H), a pulverizer (I), a tank composting device (J), a nitrification tank (K), a crusher (L), a vibrating arc screen Φ2mm (M), a reaction tank (N), a stirrer (O), a composting bin (P), a stirrer (Q), a granulator (R), and a clear water tank (S); The inlet of the hydrothermal reactor (A) for treating the tail coal slime / gasification ash mixture is connected to the separator (C), the outlet of the hydrothermal reactor (A) is connected to the plate and frame filter press (B), the discharge port of the plate and frame filter press (B) is connected to the porous tail coal slime bin (D), the liquid outlet is connected to the separator (C), the coal tar separated by the separator (C) is used separately, and the separated hydrothermal reaction liquid pipeline is connected to the tail liquid pool (F); The clear water tank (S) pipeline is connected to the absorption tower (E), the hydrothermal reaction gas outlet of the hydrothermal reactor (A) is connected to the absorption tower (E) inlet, the exhaust port of the absorption tower (E) outputs the fuel gas, and the liquid discharge port of the absorption tower (E) is connected to the tail liquid tank (F); The liquid discharge port of the dehydration screen (G) for processing livestock and poultry excrement (14) is connected to the anaerobic fermentation tank (H), and the hydrothermal reaction gas outlet of the hydrothermal reactor (A) is also connected to the anaerobic fermentation tank (H); the outlet of the pulverizer (I) for processing biomass straw and the discharge port of the dehydration screen (G) are both connected to the inlet of the tank composting device (J); The outlet of the nitrification tank (K) for processing low-rank coal slime is connected to the reaction tank (N) through a pipeline, and the crusher (L) for processing coal gangue is also connected to the reaction tank (N) through the outlet of the vibrating arc screen Φ2mm (M); The outlet of the porous tail coal slime bin (D) is connected to the inlet of the agitator (O) through a conveyor belt, and the tail liquid pool (F) is connected to the inlet of the agitator (O) through a pump (Z); the fermentation product discharge outlet of the anaerobic fermentation tank (H) is connected to the inlet of the agitator (O) through a pipeline, the outlet of the tank composter (J) is connected to the inlet of the agitator (O), the outlet of the reaction tank (N) is connected to the inlet of the agitator (O), and the outlet of the agitator (O) is connected to the composting bin (P); The discharge port of the composting bin (P) is connected to the agitator (Q), and the discharge port of the agitator (Q) is connected to the granulator (R).

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