A method for producing water-soluble organic fertilizer and mineral-based solid organic fertilizer using coal gangue and biomass

Abstract

The application discloses a method for preparing water-soluble organic fertilizer and mineral-based solid organic fertilizer by using coal gangue and biomass. Calcium carbonate, calcium chloride and biomass are used to assist high-temperature calcination and activation of coal gangue. In the process, the heat value of coal gangue and biomass is recycled, the energy cost is reduced, and energy saving and emission reduction are achieved. The activated coal gangue is used to promote the humification of biomass. By adjusting the catalyst, sulfonating agent and pyrolysis parameter, the humification yield is improved, and the property of humic acid is improved. The humic acid is extracted by the ammonium carbonate hydrothermal method to obtain the water-soluble organic fertilizer and the mineral-based solid organic fertilizer. At the same time, CO2 is fixed, and carbon emission is reduced. The obtained fertilizers have good fertilizer efficiency and can effectively promote crop growth. The above process realizes the collaborative resource utilization of coal gangue and biomass solid waste, and has the advantages of green environmental protection, high efficiency and the like.

Description

Technical Field

[0001] This invention relates to the field of environmental engineering, and in particular to a method for producing water-soluble organic fertilizer and mineral-based solid organic fertilizer using coal gangue and biomass. Background Technology

[0002] Overexploitation of farmland and excessive application of traditional chemical fertilizers have led to a series of agricultural and soil pollution problems. Therefore, there is an urgent need to find a new type of green and environmentally friendly fertilizer to reduce fertilizer use and increase efficiency in agricultural production. Coal gangue is a solid waste generated during coal mining, produced in huge quantities and difficult to treat. Its chemical composition is highly similar to soil, containing organic matter, silicon, and other mineral elements, and can be used as a raw material for producing silicon fertilizer or soil conditioner. Currently, alkaline reagents such as CaCO3 and Ca(OH)2 are commonly used to activate coal gangue through high-temperature calcination. This patent proposes using a mixture of calcium carbonate and calcium chloride as activators, and incorporating corn stalks into the coal gangue to increase its calorific value and supplement it with mineral elements. A high-temperature method is used to activate the coal gangue and remove heavy metals, while simultaneously recovering the waste heat generated during calcination to reduce energy costs. However, the high-temperature calcination process depletes the organic matter in coal gangue, and the use of calcium-based activators leaves a certain degree of alkalinity in the activated coal gangue. Both of these factors limit its agricultural application. Previous studies have shown that an alkaline environment helps improve the yield and properties of humic acid. As an important component of soil, humic acid plays a vital role in maintaining soil health and promoting plant growth and development, making it a green and environmentally friendly high-efficiency organic fertilizer. Natural humic acid forms slowly and has a low conversion rate, requiring accelerated synthesis through artificial means. Pyrolysis-humification technology, with its advantages of high efficiency, low cost, and simple operation, has become an important technology for artificial humification. The alkaline nature of activated coal gangue provides the necessary environment for biomass humification, and the steam generated from its calcination can be used in the low-temperature pyrolysis process. Furthermore, ammonium carbonate is used to extract humic acid from the pyrolysis products, supplementing nitrogen during extraction, releasing the complexed humic acid, and simultaneously fixing CO3. 2- To avoid CO2 emissions and reduce carbon loss, the coal gangue-based solid residue remaining after humic acid extraction contains mineral elements and residual organic matter, which can be used as mineral-based solid organic fertilizer. This process simultaneously activates coal gangue and humifies biomass, producing highly efficient water-soluble organic fertilizer and mineral-based solid organic fertilizer, promoting the synergistic resource utilization of coal gangue and biomass solid waste. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings and deficiencies of the prior art and to provide a method for producing water-soluble organic fertilizer and mineral-based solid organic fertilizer using coal gangue and biomass.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A method for producing water-soluble organic fertilizer and mineral-based solid organic fertilizer using coal gangue and biomass includes the following steps:

[0006] (1) The corn stalks are dried, crushed and sieved to obtain corn stalk powder. Activated coal gangue, nano iron oxide and sodium metabisulfite are added, water is added and mixed well, dried and then heated to pyrolyze to obtain pyrolysis products.

[0007] (2) Add the pyrolysis product to the reactor, add ammonium carbonate and water, seal, heat and keep warm to carry out the reaction, filter after the reaction is completed, and obtain the filtrate as water-soluble organic fertilizer, and the remaining solid is mineral-based solid organic fertilizer.

[0008] The corn stalks in step (1) are sieved through a 60-200 mesh sieve; preferably through a 100 mesh sieve.

[0009] The mass ratio of corn stalks, activated coal gangue, nano iron oxide, and sodium metabisulfite in step (1) is 1:0.5-0.7:0.05-0.1:0.1-0.2; preferably 1:0.6:0.05:0.1.

[0010] The pyrolysis temperature in step (1) is 200-300℃; preferably 270℃.

[0011] The pyrolysis time in step (1) is 0.5 to 3 hours; preferably 2 hours.

[0012] The method for preparing activated coal gangue in step (1) includes the following steps:

[0013] Coal gangue powder, calcium carbonate, calcium chloride and corn stalks are mixed, placed in a circulating fluidized bed and heated and roasted. After cooling, the mixture is ground and sieved to obtain activated coal gangue.

[0014] The mass ratio of corn stalks: calcium carbonate: calcium chloride: coal gangue is 0.2-0.4:0.2-0.4:0.1-0.2:0.5-2; preferably 0.3:0.3:0.1:1.

[0015] The heating and roasting time is 1 to 4 hours; preferably 2 hours.

[0016] The heating and roasting temperature is 800-950℃; preferably 900℃.

[0017] The mass ratio of ammonium carbonate to pyrolysis product in step (2) is 0.2:1 to 2:1, preferably 0.6:1.

[0018] The hydrothermal reaction time in step (2) is 0.5 to 3 hours; preferably 1 hour.

[0019] The temperature of the hydrothermal reaction in step (2) is 60-150℃; preferably 90℃.

[0020] The application of water-soluble organic fertilizer and mineral-based solid organic fertilizer made from coal gangue and biomass in the treatment of corn stalks.

[0021] The present invention has the following advantages over the prior art:

[0022] (1) The main mineral phases in coal gangue are kaolinite and quartz. In a high-temperature environment (>600℃), kaolinite in coal gangue will be transformed into metakaolinite. Metakaolinite reacts with activators to produce silicates, thereby activating silicon. At the same time, calcium chloride reacts with heavy metals present in coal gangue to produce chlorides. Some heavy metal chlorides will volatilize in the gaseous state at high temperatures to remove heavy metals from coal gangue.

[0023] (2) When biomass is pyrolyzed at low temperature, the organic macromolecules contained therein, such as lignin, cellulose, hemicellulose and protein, will decompose. Lignin will produce aromatic compounds, which will form the skeleton of humic acid molecules. Cellulose and hemicellulose will produce monosaccharides and reducing sugars. Further decomposition will produce small molecules such as furan, carboxylic acid, ketone, aldehyde and furfural. These small molecules will participate in the formation of humic acid and fulvic acid together with nitrogen-containing heterocycles and fatty acids produced by protein decomposition. They will form active side chains of humic acid through Maillard reaction, condensation reaction, aromatization reaction and other processes.

[0024] (3) During the biomass decomposition process, excessive contact between biomass and oxygen may lead to excessive oxidation, resulting in the loss of some organic matter in the form of gases such as carbon dioxide, thus affecting the production of humic acid. Adding an appropriate amount of activated coal gangue can reduce the contact area between corn stalk powder and air, and affect the heating mechanism of corn stalks, preventing them from being over-oxidized. Furthermore, activated coal gangue contains calcium and is alkaline, which can promote biomass pyrolysis, promote the decomposition of lignin, hemicellulose and cellulose, and produce more small molecule humic acid precursors, thereby promoting the formation of humic acid.

[0025] (4) Ammonium carbonate contains CO3 2- , easy to Ca 2+ The reaction produces calcium carbonate, which releases humic acid that is bound to calcium ions. The humic acid then combines with ammonium ions to produce water-soluble ammonium humate. The presence of ammonium ions can supplement humic acid with nitrogen, further enhancing its nutritional value.

[0026] The present invention has the following advantages over the prior art:

[0027] (1) This invention activates coal gangue, increases the content of available silicon and available calcium, removes heavy metals, and reduces environmental risks. By using activated coal gangue to promote the pyrolysis and humification of biomass (corn stalks), the yield of humic acid and fulvic acid is increased. At the same time, the mineral elements contained in activated coal gangue can increase the mineral elements in water-soluble humic acid, supplementing it with mineral elements such as silicon and calcium.

[0028] (2) The present invention utilizes high-temperature calcination to activate coal gangue. While activating coal gangue, the waste heat of coal gangue can be recovered, energy can be recycled and utilized, and energy costs can be reduced.

[0029] (3) This invention utilizes the hydrothermal method of ammonium carbonate to extract humic acid from the pyrolysis products, which can supplement the nitrogen element for humic acid. The CO3 contained in ammonium carbonate 2- Can be used with Ca 2+ Combined to release Ca 2+ Complexed humic acid increases the content of free humic acid.

[0030] (4) This invention utilizes ammonium carbonate to extract humic acid. The remaining solid residue, namely mineral-based solid organic fertilizer, contains effective calcium and effective silicon and other mineral elements. Furthermore, organic matter remains in the residue after the extraction of humic acid, which supplements the organic matter in the coal gangue-based residue and makes up for the lack of organic matter in activated coal gangue.

[0031] (5) The water-soluble organic fertilizer and mineral-based solid organic fertilizer prepared by the present invention contain organic matter and a variety of mineral elements such as silicon, calcium and potassium. They have good fertilizer effect, can effectively promote crop growth and reduce the cost of fertilization of cultivated land.

[0032] (6) The technology of this invention can consume large quantities of biomass solid waste such as coal gangue and corn stalks, thereby reducing their volume and making them into resources. It realizes the synergistic resource utilization of organic and inorganic solid waste. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the process flow of the present invention.

[0034] Figure 2 This is a schematic diagram of the reaction apparatus used in this invention.

[0035] Figure 3 The activated coal gangue prepared in Example 1 and the pyrolysis products prepared in Example 3 are shown.

[0036] Figure 4 This is a schematic diagram of the experiment to determine the yield of humic acid in Example 4.

[0037] Figure 5 This is a schematic diagram of the hydroponic planting experiment in Example 7; from left to right, the experimental groups are: blank group, coal gangue, activated coal gangue, and mineral-based solid organic fertilizer.

[0038] Figure 6 This is a schematic diagram of the hydroponic cultivation experiment in Example 7; from left to right, the values ​​are: blank group, 100 mg / L, 200 mg / L, 400 mg / L, 600 mg / L, and 800 mg / L ammonium humate. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0040] Unless otherwise specified in the following implementation plan, the test conditions are generally as per standard test conditions or the test conditions recommended by the reagent company. Unless otherwise specified, all materials and reagents used are commercially available.

[0041] The main chemical compositions of the coal gangue and corn stalks used in the following examples are shown in Tables 1 and 2.

[0042] Table 1 Chemical composition of coal gangue

[0043] element content / % <![CDATA[Na2O]]> 0.4734 MgO 0.5529 <![CDATA[Al2O3]]> 27.2818 <![CDATA[SiO2]]> 42.0055 <![CDATA[P2O5]]> 0.0889 <![CDATA[SO3]]> 1.0138 <![CDATA[K2O]]> 1.392 CaO 1.1866 <![CDATA[TiO2]]> 0.8334 <![CDATA[V2O5]]> 0.0237 <![CDATA[Cr2O3]]> 0.0138 MnO 0.0554 <![CDATA[Fe2O3]]> 4.4878 ZnO 0.0122 SrO 0.0365 <![CDATA[ZrO2]]> 0.0306 BaO 0.0714

[0044] Table 2 Chemical composition of corn stalk ash

[0045] element content / % <![CDATA[Na2O]]> 0.4482 MgO 1.5086 <![CDATA[Al2O3]]> 1.166 <![CDATA[SiO2]]> 76.231 <![CDATA[P2O5]]> 2.4284 <![CDATA[SO3]]> 1.4337 Cl 0.8561 <![CDATA[K2O]]> 9.9892 CaO 3.0889 <![CDATA[TiO2]]> 0.0955 <![CDATA[Cr2O3]]> 0.1384 MnO 0.6375 <![CDATA[Fe2O3]]> 1.807 CuO 0.0108 ZnO 0.0342 <![CDATA[Rb2O]]> 0.0113 SrO 0.0108 <![CDATA[ZrO2]]> 0.0089 BaO 0.0789 <![CDATA[WO3]]> 0.0167

[0046] Example 1 (30% calcium carbonate, 10% calcium chloride, 30% corn stalks, 900℃ for 2 hours)

[0047] Mix 500g of coal gangue powder with 150g of calcium carbonate, 50g of calcium chloride, and 150g of corn stalks. Place the mixture in a circulating fluidized bed and heat it to 900℃ at a rate of 10℃ / min, maintaining the temperature for 120 min for high-temperature calcination activation. After cooling to room temperature, remove the activated coal gangue and place it in a ball mill. Grind the activated coal gangue at 600 r / min for 2 hours. Pass the powder through a 1000-mesh sieve to obtain activated coal gangue powder for later use.

[0048] Comparative Example 1 (compared to Example 1, only 30% calcium carbonate and 30% corn stalks were added)

[0049] Mix 500g of coal gangue powder with 150g of calcium carbonate and 150g of corn stalks, place the mixture in a circulating fluidized bed, and heat to 900℃ at a rate of 10℃ / min, maintaining the temperature for 120 min for high-temperature calcination activation. After cooling to room temperature, remove the activated coal gangue and place it in a ball mill, grinding it at 600 r / min for 2 hours. Pass the powder through a 1000-mesh sieve to obtain activated coal gangue powder for later use.

[0050] Comparative Example 2 (compared to Example 1, only 10% calcium chloride and 30% corn stalks were added)

[0051] Mix 500g of coal gangue powder with 50g of calcium chloride and 150g of corn stalks, place the mixture in a circulating fluidized bed, and heat to 900℃ at a rate of 10℃ / min, maintaining the temperature for 120 min for high-temperature calcination activation. After cooling to room temperature, remove the activated coal gangue and place it in a ball mill, grinding it at 600 r / min for 2 hours. Pass the powder through a 1000-mesh sieve to obtain activated coal gangue powder for later use.

[0052] Comparative Example 3 (The activation temperature was changed to 1000°C compared to Example 1)

[0053] Mix 500g of coal gangue powder with 150g of calcium carbonate, 50g of calcium chloride, and 150g of corn stalks. Place the mixture in a circulating fluidized bed and heat it to 1000℃ at a rate of 10℃ / min, maintaining the temperature for 120 min for high-temperature calcination activation. After cooling to room temperature, remove the activated coal gangue and place it in a ball mill. Grind the activated coal gangue at 600 r / min for 2 hours. Pass the powder through a 1000-mesh sieve to obtain activated coal gangue powder for later use.

[0054] Comparative Example 4 (The activation temperature was changed to 800°C compared to Example 1)

[0055] Mix 500g of coal gangue powder with 150g of calcium carbonate, 50g of calcium chloride, and 150g of corn stalks. Place the mixture in a circulating fluidized bed and heat it to 800℃ at a rate of 10℃ / min, maintaining the temperature for 120 min for high-temperature calcination activation. After cooling to room temperature, remove the activated coal gangue and place it in a ball mill. Grind the activated coal gangue at 600 r / min for 2 hours. Pass the powder through a 1000-mesh sieve to obtain activated coal gangue powder for later use.

[0056] Comparative Example 5 (The activation time was changed to 1 h℃ compared to Example 1)

[0057] Mix 500g of coal gangue powder with 150g of calcium carbonate, 50g of calcium chloride, and 150g of corn stalks. Place the mixture in a circulating fluidized bed and heat it to 900℃ at a rate of 10℃ / min, maintaining the temperature for 60min for a high-temperature calcination activation reaction. After cooling to room temperature, remove the activated coal gangue and place it in a ball mill. Grind the activated coal gangue at 600r / min for 2 hours. Pass the powder through a 1000-mesh sieve to obtain activated coal gangue powder for later use.

[0058] Comparative Example 6 (The activation time was changed to 3 hours compared to Example 1)

[0059] Mix 500g of coal gangue powder with 150g of calcium carbonate, 50g of calcium chloride, and 150g of corn stalks. Place the mixture in a circulating fluidized bed and heat it to 900℃ at a rate of 10℃ / min, maintaining the temperature for 180 min for high-temperature calcination activation. After cooling to room temperature, remove the activated coal gangue and place it in a ball mill. Grind the activated coal gangue at 600 r / min for 2 hours. Pass the powder through a 1000-mesh sieve to obtain activated coal gangue powder for later use.

[0060] Example 2

[0061] The available silicon content in activated coal gangue was determined according to the method in "Soil Amendment - Determination of Calcium, Magnesium and Silicon Content" (Agricultural Industry Standard of the People's Republic of China, 2012). 1.0 g of the activated coal gangue obtained in Example 1 and Comparative Examples 1-6 was weighed and placed in a 250 mL Erlenmeyer flask. 150 mL of 0.5 mol / L hydrochloric acid solution preheated to approximately 30°C was added. The flask was sealed and placed in a 30°C constant temperature shaking incubator, where it was shaken at 180 rpm for 30 min. The filtrate was filtered through a 0.25 μm filter, and the available silicon content was quantitatively determined using ICP.

[0062] Weigh 1g of activated coal gangue powder, add nitric acid, hydrofluoric acid, and perchloric acid, and perform pyrolysis digestion (refer to standard HJ 491-2009). After the solids are completely digested and removed, transfer the digestion solution to a colorimetric tube, add deionized water to make up the volume, and determine the Cr and Mn content using ICP (the heavy metals in the coal gangue used in this example are mainly Cr and Mn; therefore, the content of these two is used as a reference indicator for the heavy metal removal effect).

[0063] The effective silicon and heavy metal contents in each group of activated coal gangue are shown in Table 3.

[0064] The activated coal gangue obtained in Example 1 had the highest effective silicon content and the lowest heavy metal content. The activated coal gangue from Example 1 was used in all subsequent examples and comparative examples.

[0065] Table 3. Available silicon content and heavy metal content in activated coal gangue

[0066] Processing group Effective silicon content / % Cr content / % Mn content / % Untreated coal gangue 0.06 0.013 0.062 Example 1 8.16 0.001 0.011 Comparative Example 1 7.29 0.008 0.029 Comparative Example 2 3.52 0.004 0.017 Comparative Example 3 7.21 0.002 0.012 Comparative Example 4 5.42 0.001 0.019 Comparative Example 5 3.67 0.003 0.017 Comparative Example 6 7.44 0.001 0.012

[0067] Example 3 (without the addition of sodium metabisulfite, a sulfonating agent)

[0068] Corn stalks were crushed using a crusher and sieved through a 100-mesh sieve to obtain corn stalk powder. 60g of the activated coal gangue prepared in Example 1 and 100g of corn stalk powder were weighed, mixed with water, and 5g of nano-iron oxide was added simultaneously. The mixture was then dried in an oven and placed in a pyrolysis furnace, reacting at 270℃ for 120 min. After the reaction was complete, the pyrolysis product was removed and allowed to cool to room temperature in air for later use.

[0069] Comparative Example 7 (corn stalks only)

[0070] Corn stalks were crushed using a crusher and sieved through a 100-mesh sieve to obtain corn stalk powder. 100 g of the corn stalk powder was weighed, mixed with water, dried in an oven, and then placed in a pyrolysis furnace and reacted at 270℃ for 120 min. After the reaction was complete, the pyrolysis product was removed and allowed to cool to room temperature in air for later use.

[0071] Comparative Example 8 (compared to Example 3, the amount of activated coal gangue added was changed to 0%)

[0072] Corn stalks were crushed using a crusher and sieved through a 100-mesh sieve to obtain corn stalk powder. 100 g of the corn stalk powder was weighed, mixed with water, and 5 g of nano-iron oxide was added and mixed. The mixture was then dried in an oven and placed in a pyrolysis furnace, reacting at 270℃ for 120 min. After the reaction was complete, the pyrolysis product was removed and allowed to cool to room temperature in air for later use.

[0073] Comparative Example 9 (compared to Example 3, the amount of activated coal gangue added was changed to 120%)

[0074] Corn stalks were crushed using a crusher and sieved through a 100-mesh sieve to obtain corn stalk powder. 120g of the activated coal gangue prepared in Example 1 and 100g of corn stalk powder were weighed, mixed with water, and 5g of nano-iron oxide was added simultaneously. The mixture was then dried in an oven and placed in a pyrolysis furnace, reacting at 270℃ for 120 min. After the reaction was complete, the pyrolysis product was removed and allowed to cool to room temperature in air for later use.

[0075] Comparative Example 10 (Compared to Example 3, the amount of nano-iron oxide was changed to 0%)

[0076] Corn stalks were crushed using a crusher and sieved through a 100-mesh sieve to obtain corn stalk powder. 60g of the activated coal gangue prepared in Example 1 and 100g of corn stalk powder were weighed, mixed with water, dried in an oven, and then placed in a pyrolysis furnace and reacted at 270℃ for 120 min. After the reaction was complete, the pyrolysis product was removed and cooled to room temperature in air for later use.

[0077] Comparative Example 11 (compared to Example 3, the amount of nano-iron oxide was changed to 7%)

[0078] Corn stalks were crushed using a crusher and sieved through a 100-mesh sieve to obtain corn stalk powder. 60g of the activated coal gangue prepared in Example 1 and 100g of corn stalk powder were weighed, mixed with water, and 7g of nano-iron oxide was added simultaneously. The mixture was then dried in an oven and placed in a pyrolysis furnace, reacting at 270℃ for 120 min. After the reaction was complete, the pyrolysis product was removed and cooled to room temperature in air for later use.

[0079] Comparative Example 12 (compared to Example 3, the pyrolysis time was changed to 1 hour)

[0080] The corn stalks were crushed using a crusher and sieved through a 100-mesh sieve to obtain corn stalk powder. 60g of the activated coal gangue prepared in Example 1 and 100g of the corn stalk powder were weighed, mixed with water, dried in an oven, and then placed in a pyrolysis furnace and reacted at 270℃ for 60 min. After the reaction was complete, the pyrolysis product was removed and cooled to room temperature in air for later use.

[0081] Comparative Example 13 (compared to Example 3, the pyrolysis time was changed to 3 hours)

[0082] Corn stalks were crushed using a crusher and sieved through a 100-mesh sieve to obtain corn stalk powder. 60g of the activated coal gangue prepared in Example 1 and 100g of corn stalk powder were weighed, mixed with water, dried in an oven, and then placed in a pyrolysis furnace and reacted at 270℃ for 180 min. After the reaction was complete, the pyrolysis product was removed and cooled to room temperature in air for later use.

[0083] Comparative Example 14 (compared to Example 3, the pyrolysis temperature was changed to 250°C)

[0084] Corn stalks were crushed using a crusher and sieved through a 100-mesh sieve to obtain corn stalk powder. 60g of the activated coal gangue prepared in Example 1 and 100g of corn stalk powder were weighed, mixed with water, dried in an oven, and then placed in a pyrolysis furnace for reaction at 250℃ for 120 min. After the reaction was complete, the pyrolysis product was removed and allowed to cool to room temperature in air for later use.

[0085] Comparative Example 15 (compared to Example 3, the pyrolysis time was changed to 290°C)

[0086] The corn stalks were crushed using a crusher and sieved through a 100-mesh sieve to obtain corn stalk powder. 60g of the activated coal gangue prepared in Example 1 and 100g of the corn stalk powder were weighed, mixed with water, dried in an oven, and then placed in a pyrolysis furnace and reacted at 290℃ for 120 min. After the reaction was complete, the pyrolysis product was removed and cooled to room temperature in air for later use.

[0087] Example 4

[0088] Humic acid was extracted from the pyrolysis products obtained in Examples 3 and Comparative Examples 7-15 using methods recommended by the International Humic Society (IHSS). The pyrolysis products were mixed with the extract (0.1 mol·L⁻¹) at a ratio of 1 g: 25 mL. -1 NaP₂O₇ and 0.1 mol·L⁻¹ -1 Mix the NaOH solution and incubate at 90°C in a reciprocating shaker for 1 hour. Centrifuge the mixture at 8000 rpm for 5 min, collect the supernatant, and wash the solid repeatedly with the extract until the supernatant is clear and colorless. Adjust the pH of the supernatant to 1 with 1 mol·L⁻¹ H₂SO₄ solution, allow it to stand to precipitate, separate the solid and liquid using a vacuum filter, and wash the solid with deionized water. Dry the solid to constant weight to obtain artificial humic acid, denoted as mAHA. Dilute the liquid to 250 mL, and determine the content of artificial fulvic acid (AFA) in the liquid using the potassium dichromate oxidation titration method according to Chinese National Standard HG / T 5334-2018: accurately transfer 2 mL of sample to an Erlenmeyer flask, add 2.5 mL of 0.8000 mol / L potassium dichromate standard solution. Then slowly add 15 mL of concentrated sulfuric acid, shake the mixture thoroughly, and heat in a boiling water bath at 95-100°C for oxidative oxidation for 30 minutes. After removing the sample and cooling it to room temperature, add 70 mL of deionized water and 3 drops of o-phenanthroline-ferrous ammonium sulfate mixed indicator solution. Titrate with 0.1 mol / L ferrous sulfate standard titration solution. The endpoint is reached when the solution changes from orange to green and then to brick red. Record the volume of ferrous ammonium sulfate standard titration solution consumed (V2). Simultaneously, replace the sample with deionized water and perform a blank experiment following the same steps. Record the volume of ferrous ammonium sulfate standard titration solution consumed in the blank experiment (V1).

[0089] The formulas for calculating the yields of AHA and AFA are as follows:

[0090]

[0091]

[0092] In the formula: YAHA is the yield of artificial humic acid, %; YAFA is the yield of artificial fulvic acid, %; mAHA is the mass of artificial humic acid, g; mCS is the mass of corn stalks, g; 0.003 is the carbon content equivalent to 1.00 mL of 1.000 mol / L ferrous ammonium sulfate standard solution, g; V1 is the volume of 0.1 mol / L ferrous ammonium sulfate standard solution consumed in the blank experiment, mL; V2 is the volume of 0.1 mol / L ferrous ammonium sulfate standard solution consumed in the fulvic acid sample, mL; c(Fe2+) is the actual concentration of the ferrous ammonium sulfate standard titration solution, mol / L; 125 is the volume conversion factor; k is the carbon coefficient of fulvic acid, calculated as 0.45 for bio-derived fulvic acid. The yields of humic acid and fulvic acid in each group are shown in Table 4. The total yield of humic acid and fulvic acid was the highest in Example 3.

[0093] Table 4. Humic acid yield and fulvic acid yield

[0094] Processing group Humic acid yield / % fulvic acid yield / % Example 3 28.84 35.37 Comparative Example 7 11.56 7.15 Comparative Example 8 14.57 11.46 Comparative Example 9 23.49 34.04 Comparative Example 10 25.56 29.98 Comparative Example 11 26.97 30.55 Comparative Example 12 16.09 33.97 Comparative Example 13 22.59 35.22 Comparative Example 14 25.13 34.92 Comparative Example 15 9.09 9.12

[0095] Example 5 (pyrolysis and humification: 0.6:1, 270℃, 2h, 5% nano iron oxide, 10% sodium metabisulfite)

[0096] Corn stalks were crushed using a crusher and sieved through a 100-mesh sieve to obtain corn stalk powder. 60g of the activated coal gangue prepared in Example 1 and 100g of corn stalk powder were weighed, mixed with water, and simultaneously 5g of nano-iron oxide and 10g of sodium metabisulfite were added and mixed. The mixture was then dried in an oven and placed in a pyrolysis furnace, reacting at 270℃ for 120 min. After the reaction, the pyrolysis product was removed and cooled to room temperature in air. It was then set aside for later use. Humic acid was extracted using the method in Example 4 to obtain sodium humate, which was then dried. The hard water resistance of sodium humate in Example 3 and this example was determined using the German standard. Water with hardnesses of 5, 8, 10, 12, 14, 16, 18, 20, 22, and 25° was prepared with calcium chloride, and the total hardness of the water was determined by EDTA complexometric titration. Solid sodium humate was mixed with the prepared hard water to achieve a humic acid concentration of 200 mg / L, shaken well, and allowed to stand. The time for flocculation to occur was recorded. The E4 / E6 value of humic acid was determined according to the method in "Analysis and Standards of Humic Acid Products". The anti-flocculation results are shown in Table 5. The E4 / E6 values ​​of the humic acid obtained in Example 3 and Example 5 were 4.06 and 5.12, respectively. This indicates that the addition of sodium metabisulfite improves the hard water resistance and hydrophilicity of humic acid, significantly improving its properties.

[0097] Table 5 Anti-flocculation effect of humic acid

[0098] hardness 5° 8° 10° 12° 14° 16° 18° 20° 22° 25° Example 3 - - - - 3.5 ↓ ↓ ↓ ↓ ↓ Example 5 - - - - - - 12 0.5

[0099] Example 6

[0100] The pyrolysis product used in this embodiment was prepared in Example 5. 3 g of the pyrolysis product was weighed and added to the lining of a hydrothermal reactor, along with 1.8 g of ammonium carbonate and 30 mL of deionized water. The reactor was then assembled and placed in an oven. The temperature was increased to 90°C at a rate of 5°C / min and maintained for 60 min. After the reaction, the reaction product was filtered using a vacuum filtration device to separate the liquid and solid phases. The filtrate was collected and diluted to 250 mL, yielding an ammonium humate solution. The solid was then the mineral-based solid organic fertilizer. After collection, the fertilizer was dried to constant weight and placed in a vacuum desiccator for later use. The contents of available silicon, available calcium, available magnesium, and available potassium in the mineral-based solid organic fertilizer were determined according to the methods in "Soil Improvement - Determination of Calcium, Magnesium, and Silicon Content" (Agricultural Industry Standard of the People's Republic of China, 2012) and "Fertilizer - Determination of Potassium Content" (Agricultural Industry Standard of the People's Republic of China, 2014). The organic matter content was determined according to the method in "Organic Fertilizer" (Agricultural Industry Standard of the People's Republic of China, 2012). Accurately transfer 5 mL of ammonium humate solution, add nitric acid to digest the organic matter, filter the digestion solution through a 0.25 μm filter, and determine the calcium, silicon, magnesium, and potassium contents by ICP method. The results are shown in Tables 7 and 8.

[0101] Table 6. Mineral element content in ammonium humate solution

[0102] sample <![CDATA[Available calcium / mg·L -1 > <![CDATA[Available magnesium / mg·L -1 > <![CDATA[Available potassium / mg·L -1 > <![CDATA[Available Silicon / mg·L -1 > ammonium humate solution 18.80 2.40 122.27 14.92

[0103] Table 7 Organic matter and mineral element content of mineral-based solid organic fertilizer

[0104] sample Organic matter / % Effective calcium / % Available magnesium / % Available potassium / % Effective silicon / % Mineral-based solid organic fertilizer 14.38 11.80 0.34 0.06 5.03

[0105] Example 7

[0106] The effects of ammonium humate solution (water-soluble organic fertilizer) and mineral-based solid organic fertilizer on wheat growth. Details are as follows:

[0107] A hydroponic experiment was conducted on wheat seeds. Each group of hydroponic baskets contained 600 mL of different culture media. Deionized water served as the blank control group. The experimental groups were prepared with the following concentrations: 100 mg / L ammonium humate, 200 mg / L ammonium humate, 400 mg / L ammonium humate, 600 mg / L ammonium humate, 800 mg / L ammonium humate, 2.0 g / L coal gangue, 2.0 g / L activated coal gangue, and 2.0 g / L mineral-based solid organic fertilizer. Wheat seeds were disinfected with 10% H₂O₂ solution for 30 min, washed with deionized water, and soaked for 8 h. Filter paper was moistened and placed in petri dishes. Plump wheat seeds were selected and placed on the filter paper. The petri dishes were covered with aluminum foil, and the wheat seeds were allowed to germinate in a dark environment for 2 days. After germination, the wheat seeds were transferred to hydroponic baskets, with 40 seeds in each group, and cultured at room temperature for 12 days. The length and dry weight of the roots and stems of the plants were measured. The results are shown in Table 7. Both ammonium humate and mineral-based solid organic fertilizer effectively promoted wheat growth. Compared to the control group, the 800 mg / L ammonium humate group increased wheat stem length, stem dry weight, root length, and root dry weight by 44.89%, 55.45%, 24.69%, and 39.74%, respectively. The mineral-based solid organic fertilizer increased these quantities by 23.41%, 42.32%, 221.30%, and 123.96%, respectively. This indicates that the fertilizer of this invention can effectively promote wheat growth.

[0108] Table 8. Dry weight and length of stems and roots for each hydroponic planting group

[0109] Processing group Average dry weight of stem / mg Root average dry weight / mg Average stem length / cm Average root length / cm Ionized water 12.18 4.34 12.85 7.11 Coal gangue 13.81 5.88 14.34 10.17 Activated coal gangue 13.00 5.95 14.88 9.89 Mineral-based solid organic fertilizer 17.34 9.72 15.86 22.84 100 mg / L ammonium humate 13.77 6.11 14.31 8.48 200 mg / L ammonium humate 15.91 6.68 14.01 7.61 400 mg / L ammonium humate 15.64 5.98 16.68 7.14 600 mg / L ammonium humate 15.19 5.65 16.00 8.00 800 mg / L ammonium humate 18.94 6.07 18.62 8.87

[0110] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

[0111] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for producing water-soluble organic fertilizer and mineral-based solid organic fertilizer using coal gangue and biomass, characterized in that... Includes the following steps: (1) The corn stalks are dried, crushed and sieved to obtain corn stalk powder. Activated coal gangue, nano iron oxide and sodium metabisulfite are added, water is added and mixed well, dried and then heated to pyrolyze to obtain pyrolysis products. (2) Add the pyrolysis product to the reactor, add ammonium carbonate and water, seal, heat and keep warm to carry out the reaction, filter after the reaction is completed, and obtain the filtrate as water-soluble organic fertilizer, and the remaining solid is mineral-based solid organic fertilizer.

2. The method for producing water-soluble organic fertilizer and mineral-based solid organic fertilizer from coal gangue and biomass according to claim 1, characterized in that: The mass ratio of corn stalks, activated coal gangue, nano iron oxide, and sodium metabisulfite in step (1) is 1:0.5-0.7:0.05-0.1:0.1-0.

2.

3. The method for producing water-soluble organic fertilizer and mineral-based solid organic fertilizer from coal gangue and biomass according to claim 1, characterized in that: The corn stalks in step (1) are sieved through a 60-200 mesh sieve.

4. The method for producing water-soluble organic fertilizer and mineral-based solid organic fertilizer from coal gangue and biomass according to claim 1, characterized in that: The pyrolysis temperature in step (1) is 200–300°C; The pyrolysis time in step (1) is 0.5 to 3 hours.

5. The method for producing water-soluble organic fertilizer and mineral-based solid organic fertilizer from coal gangue and biomass according to claim 1, characterized in that: The method for preparing activated coal gangue in step (1) includes the following steps: Coal gangue powder, calcium carbonate, calcium chloride and corn stalks are mixed, placed in a circulating fluidized bed and heated and roasted. After cooling, the mixture is ground and sieved to obtain activated coal gangue.

6. The method for producing water-soluble organic fertilizer and mineral-based solid organic fertilizer from coal gangue and biomass according to claim 5, characterized in that: The mass ratio of corn stalks: calcium carbonate: calcium chloride: coal gangue is 0.2-0.4: 0.2-0.4: 0.1-0.2: 0.5-2.

7. The method for producing water-soluble organic fertilizer and mineral-based solid organic fertilizer from coal gangue and biomass according to claim 5, characterized in that: The heating and roasting time is 1 to 4 hours; The heating and roasting temperature is 800-950℃.

8. The method for producing water-soluble organic fertilizer and mineral-based solid organic fertilizer from coal gangue and biomass according to claim 1, characterized in that: The mass ratio of ammonium carbonate to pyrolysis product in step (2) is 0.2:1 to 2:

1.

9. The method for producing water-soluble organic fertilizer and mineral-based solid organic fertilizer from coal gangue and biomass according to claim 1, characterized in that: The hydrothermal reaction time in step (2) is 0.5 to 3 hours; The temperature of the hydrothermal reaction in step (2) is 60 to 150°C.

10. The application of the water-soluble organic fertilizer and mineral-based solid organic fertilizer prepared from coal gangue and biomass as described in any one of claims 1 to 9 in the treatment of corn stalks.

Images