A method for preparing a soil conditioner by coupling rice straw baking and water coal slurry gasification

Abstract

The present invention relates to the technical field of high-value utilization of bulk solid wastes, and specifically to a method for preparing a soil conditioner by coupling rice straw baking with water coal slurry gasification; in the present invention, the solid product of rice straw after baking treatment is partially used to replace the pulverized coal in the water coal slurry for pulping, reducing the carbon emissions generated by the consumption of fossil fuels; using the baked straw to prepare a composite water coal slurry and gasify it, and the gasification residue obtained is activated online for soil improvement, avoiding the problem of low activity of traditional fly ash for soil improvement, and at the same time increasing the activity of the nutrient components of rice straw ash residues, achieving high-value utilization of bulk solid wastes fly ash and biomass power plant ash residues; the present invention uses the waste rice straw raw material for baking pretreatment to realize comprehensive resource utilization and solve the problem of waste pollution. The prepared soil conditioner has an effective silicon content of >20% and a water-soluble potassium content of >60%, and the heavy metal adsorption and removal rate reaches more than 95% when applied to soil improvement.

Description

Technical Field

[0001] The present invention relates to the technical field of high-value utilization of bulk solid waste, and specifically to a method for preparing a soil conditioner by coupling rice straw baking with water coal slurry gasification. Background Art

[0002] Based on China's coal-dominated energy national conditions and the proposal of the dual-carbon strategy, the coupled utilization of biomass and coal will be an important way for large-scale consumption of biomass. However, the differences in density, calorific value, ignition point, and ash fusibility between biomass and coal have led to poor co-utilization of biomass and coal. Water coal slurry is a combustible black slurry with good fluidity and stability, which is convenient for storage and transportation and can be atomized for combustion. It is not only a clean energy with high combustion efficiency and low pollution, but also can be used to make a slurry with biomass and coal for better co-utilization. At the same time, during the biomass gasification process, the gasification temperature is low, and the content of effective nutrient components in the generated biomass ash residue is low, all of which are fixed oxides. Although the temperature is high during the coal gasification process, it is not enough to melt and activate the effective nutrient components in the fly ash. Fly ash needs to be further activated as a soil conditioner. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for preparing a soil conditioner by coupling rice straw baking with water coal slurry gasification to solve the problems raised in the above background art.

[0004] To solve the above technical problems, the present invention provides the following technical solution: A method for preparing a soil conditioner by coupling rice straw baking with water coal slurry gasification, comprising the following steps:

[0005] S1. Collect rice straw, wash it with clean water, dry the water after removing impurities, and crush it into granular rice straw with a particle size of 1-10 mm. Heat the granular rice straw to 280-320 °C in a low-oxygen environment, bake it for 0.5-1 h, collect the baked product, and ball-mill it to a particle size of 50-200 mesh to obtain baked rice straw.

[0006] S2. Mix the baked rice straw obtained in step S1 with coal powder, sodium lignosulfonate, and water, and mechanically stir and mix for 0.5-1 h to obtain a composite water coal slurry.

[0007] S3. Place the composite water coal slurry obtained in step S2 in a nitrogen-oxygen mixed atmosphere, heat it to 900-1000 °C, gasify it for 0-30 min to obtain gasification residue, switch the atmosphere to a CO2 environment atmosphere, continue to activate it for 2.5-3 h, stop heating, and cool it to room temperature to obtain the soil conditioner.

[0008] Further, in step S1, the oxygen concentration in the low-oxygen environment is 0-5%.

[0009] Further, in step S1, when heating up, the heating temperature is 8 - 10 °C / min.

[0010] Further, by mass parts, in step S2, the mass ratio of the roasted straw, pulverized coal, sodium lignosulfonate, and water is (14 - 16):(46 - 52):(0.4 - 0.6):(33 - 36).

[0011] Further, in step S2, the pulverized coal is a mixture of 80 - 100 mesh pulverized coal and 150 - 200 mesh pulverized coal, and the mass ratio of the 80 - 100 mesh pulverized coal to the 150 - 200 mesh pulverized coal is 1:1.

[0012] Further, in step S3, in the nitrogen - oxygen mixed atmosphere, the volume ratio of nitrogen to oxygen is (90 - 95):

[0013] (5 - 10), and the gas flow rate is 80 - 150 mL / min.

[0014] Further, in step S3, when heating up, the heating rate is 10 - 15 °C / min.

[0015] Further, in step S3, in the CO2 environment, the CO2 flow rate is 100 - 300 mL / min.

[0016] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: In the present invention, the solid product of roasted rice straw is partially used to replace the pulverized coal in the water - coal slurry for pulping, reducing the carbon emissions generated by the consumption of fossil fuels; using the roasted straw to prepare a composite water - coal slurry and gasifying it, and the gasification residue is activated online for soil improvement, avoiding the problem of low activity of traditional fly ash for soil improvement, and at the same time increasing the activity of the nutrient components of rice straw ash residues, achieving high - value utilization of bulk solid wastes such as fly ash and biomass power plant ash residues; the present invention uses waste rice straw raw materials for roasting pretreatment to achieve comprehensive resource utilization and solve the problem of waste pollution. The prepared soil conditioner has an effective silicon content > 20%, a water - soluble potassium content > 60%, and the heavy - metal adsorption and removal rate reaches more than 95% when applied to soil improvement. Specific Embodiments

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0018] Example 1.

[0019] A method for preparing a soil conditioner by coupling rice straw baking with water-coal slurry gasification comprises the following steps:

[0020] S1. Collect rice straw, wash it with clean water, remove impurities and dry it, and crush it into granular rice straw with a particle size of 1-10 mm. Put the granular rice straw into the compound grinder CM100M for grinding, weigh 20g of the ground rice straw and put it into a slender sample tube, use nitrogen / oxygen = 95:5 volume ratio as the reaction atmosphere, and heat it to 300℃ at a rate of 10℃ per minute under an atmosphere with a flow rate of 90ml / min, and keep it for 30min. After cooling, put the baked rice straw into the planetary ball mill QM-3SP04 and grind it for 15min, and pass it through a 200-mesh sieve with a maximum aperture of 0.075mm to obtain the baked rice straw.

[0021] S2. By mass percentage, 15% of the 200-mesh roasted rice straw prepared in step S1 was mixed with 0.5% sodium lignin sulfonate, 35.5% deionized water, and 49% coal powder, and stirred at a stirring rate of 100 to 200 r / min for 20 min under a DW-2 multifunctional electric stirrer, and then allowed to stand for 3 min to obtain a roasted biomass water-coal slurry;

[0022] The coal powder is a mixture of coal powder passing through a 100-mesh sieve and coal powder passing through a 200-mesh sieve in a mass ratio of 1:1.

[0023] S3. The composite water-coal slurry obtained in step S2 is gasified with air at 1000°C (nitrogen / oxygen = 80:20) to obtain gasified ash. The gasified ash is activated with 100 mL / min of CO2 for 3 h. The specific surface area of the obtained gasified ash is 123 m 2 / g, the effective silicon content of the prepared soil conditioner is 20.56%, the content of water-soluble potassium is 60.12%, and the Cr(VI) removal rate when applied to soil improvement reaches 95.23%.

[0024] Example 2.

[0025] A method for preparing a soil conditioner by coupling rice straw baking with water-coal slurry gasification comprises the following steps:

[0026] S1. Collect rice straw, wash it with clean water, remove impurities and dry it, and crush it into granular rice straw with a particle size of 1-10 mm. Put the granular rice straw into the compound grinder CM100M for grinding, weigh 20g of the ground rice straw and put it into a slender sample tube, use nitrogen / oxygen = 95:5 volume ratio as the reaction atmosphere, and heat it to 300℃ at a rate of 10℃ per minute under an atmosphere with a flow rate of 90ml / min, and keep it for 30min. After cooling, put the baked rice straw into the planetary ball mill QM-3SP04 and grind it for 15min, and pass it through a 200-mesh sieve with a maximum aperture of 0.075mm to obtain the baked rice straw.

[0027] S2. By mass percentage, 15% of the 200-mesh roasted rice straw prepared in step S1 was mixed with 0.5% sodium lignin sulfonate, 35.5% deionized water, and 49% coal powder, and stirred at a stirring rate of 100 to 200 r / min for 20 min under a DW-2 multifunctional electric stirrer, and then allowed to stand for 3 min to obtain a roasted biomass water-coal slurry;

[0028] The coal powder is a mixture of coal powder passing through a 100-mesh sieve and coal powder passing through a 200-mesh sieve in a mass ratio of 1:1.

[0029] S3. The composite water-coal slurry obtained in step S2 is gasified with air at 900°C (nitrogen / oxygen = 80:20) to obtain gasified ash. The gasified ash is activated by CO2 at 100 mL / min for 3 h. The specific surface area of the obtained gasified ash is 123 m 2 / g, the effective silicon content of the prepared soil conditioner is 20.56%, the content of water-soluble potassium is 60.12%, and the Cr(VI) removal rate when applied to soil improvement reaches 95.23%.

[0030] Comparative Example 1.

[0031] Compared with Example 1, this comparative example did not prepare a composite water-coal slurry;

[0032] A method for preparing a soil conditioner by coupling rice straw baking with water-coal slurry gasification comprises the following steps:

[0033] S1. Collect rice straw, wash it with clean water, remove impurities and dry it, and crush it into granular rice straw with a particle size of 1-10 mm. Put the granular rice straw into the compound grinder CM100M for grinding, weigh 20g of the ground rice straw and put it into a slender sample tube, use nitrogen / oxygen = 95:5 volume ratio as the reaction atmosphere, and heat it to 300℃ at a rate of 10℃ per minute under an atmosphere with a flow rate of 90ml / min, and keep it for 30min. After cooling, put the baked rice straw into the planetary ball mill QM-3SP04 and grind it for 15min, and pass it through a 200-mesh sieve with a maximum aperture of 0.075mm to obtain the baked rice straw.

[0034] S3. The baked rice straw obtained in step S1 was activated by 100 mL / min CO2 at 300 ° C for 3 h, and the gasified ash had a specific surface area of 146 m 2 / g, the effective silicon content of the prepared soil conditioner is 10.23%, the water-soluble potassium content is 80.23%, and the Cr(VI) removal rate when applied to soil improvement reaches 90.16%.

[0035] Comparative Example 2: Gasification with pure coal-water slurry at 900°C (nitrogen / oxygen = 80:20) to obtain gasified ash with a specific surface area of 78m 2 / g, the effective silicon content of the prepared soil conditioner is 25.31%, the content of water-soluble potassium is 5.46%, and the Cr(VI) removal rate when applied to soil improvement reaches 85.23%.

[0036] The pure coal-water slurry is a mixture of 49 wt% coal powder and 51 wt% water; the coal powder is a mixture of coal powder passing through a 100 mesh sieve and coal powder passing through a 200 mesh sieve in a mass ratio of 1:1

[0037] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a soil conditioner by coupling rice straw baking and water coal slurry gasification, characterized in that, It includes the following steps: S1. Collect rice straws, wash them with clean water, dry the water after removing impurities, and crush them into granular rice straws with a particle size of 1 - 10 mm. Heat the granular rice straws to 280 - 320 °C in a low-oxygen environment, after baking for 0.5 - 1 h, collect the baking product, and ball-mill it to a particle size of 50 - 200 mesh to obtain baked rice straws; S2. Mix the baked rice straws obtained in step S1 with pulverized coal, sodium lignosulfonate, and water, mechanically stir and mix for 0.5 - 1 h to obtain a composite water coal slurry; S3. Place the composite water coal slurry obtained in step S2 in a nitrogen-oxygen mixed atmosphere, heat it to 900 - 1000 °C, gasify for 0 - 30 min to obtain gasification residues, switch the atmosphere to a CO2 environmental atmosphere, continue to activate for 2.5 - 3 h, then stop heating and cool to room temperature to obtain the soil conditioner; In step S1, the oxygen concentration in the low-oxygen environment is 0 - 5%; In step S1, when heating up, the heating rate is 8 - 10 °C / min.

2. The method for preparing a soil conditioner by coupling rice straw baking and water coal slurry gasification according to claim 1, characterized in that: By mass, in step S2, the mass ratio of the baked straws, pulverized coal, sodium lignosulfonate, and water is (14 - 16):(46 - 52):(0.4 - 0.6):(33 - 36).

3. A method for preparing a soil conditioner by coupling rice straw baking and water coal slurry gasification according to claim 1, characterized in that: In step S2, the pulverized coal is a mixture of 80 - 100 mesh pulverized coal and 150 - 200 mesh pulverized coal, and the mass ratio of the 80 - 100 mesh pulverized coal to the 150 - 200 mesh pulverized coal is 1:

1.

4. A method for preparing a soil conditioner by coupling rice straw baking and water coal slurry gasification according to claim 1, characterized in that: In step S3, in the nitrogen-oxygen mixed atmosphere, the volume ratio of nitrogen to oxygen is (90 - 95):(5 - 10), and the gas flow rate is 80 - 150 mL / min.

5. A method for preparing a soil conditioner by coupling rice straw baking and water coal slurry gasification according to claim 1, characterized in that: In step S3, when heating up, the heating rate is 10 - 15 °C / min.

6. A method for preparing a soil conditioner by coupling rice straw baking and water coal slurry gasification according to claim 1, characterized in that: In step S3, in the CO2 environment, the CO2 flow rate is 100 - 300 mL / min.

7. A soil conditioner prepared by the method for preparing a soil conditioner by coupling rice straw baking and water coal slurry gasification according to any one of claims 1 - 6.