CN113481013A

CN113481013A - Method for preparing soil conditioner by utilizing ceramsite in-situ hydrothermal combination with biochar

Info

Publication number: CN113481013A
Application number: CN202110794311.XA
Authority: CN
Inventors: 熊丹苓; 董祥; 孙亮; 张兰; 岑启宏; 赵焱
Original assignee: Kunming University of Science and Technology
Current assignee: Kunming University of Science and Technology
Priority date: 2021-07-14
Filing date: 2021-07-14
Publication date: 2021-10-08

Abstract

The invention discloses a method for preparing a soil conditioner by utilizing ceramsite in-situ hydrothermal combination with biochar. The biomass waste is combined with the ceramsite by a hydrothermal carbonization method, and the preparation raw materials all adopt solid waste, so that the production cost is reduced while the solid waste is fully utilized. According to the invention, the biomass is combined with the ceramsite, so that the preparation of the biochar combined ceramsite is realized, the ceramsite has stronger water absorption and adsorption performance due to the porous structure, the water retention of soil is enhanced, and harmful substances can be adsorbed, and besides, functional groups of the biomass waste raw material can also effectively adsorb pollutants. The heavy metal ions in the ceramsite are fixed after being fired, and secondary pollution to the environment cannot be caused, so that the ceramsite can be a better soil conditioner.

Description

Method for preparing soil conditioner by utilizing ceramsite in-situ hydrothermal combination with biochar

Technical Field

The invention relates to a method for preparing a soil conditioner by utilizing ceramsite in-situ hydrothermal combination with biochar, and belongs to the technical field of new materials.

Background

The rapid development of economy leads to the increasing discharge of industrial solid wastes, wherein the red mud is extremely fine particle solid wastes generated in the process of refining alumina by taking bauxite as a raw material, and is waste residues with extremely strong alkalinity. 0.8-1.5 tons of red mud can be produced when 1 ton of alumina is produced, the discharge amount of the red mud is large, and the utilization rate of the red mud in China is extremely low, namely only 4%. The red mud contains various harmful substances, which not only wastes land resources in the long-term stacking process, but also causes a large amount of alkaline liquor and harmful substances to permeate nearby lands, thereby causing damages to the environment, such as land alkalization, surface water and underground water pollution, and the like. At present, the red mud is researched to be used as a soil conditioner, but the harmless treatment and the comprehensive utilization of the red mud are still difficult problems worldwide.

The fly ash is fine ash collected from burned flue gas and is the main solid waste of coal-fired power plants. In recent years, along with the development of the power industry, the emission of fly ash of coal-fired power plants is increasing day by day, and the fly ash becomes one of the industrial waste residues with larger emission in China. The fly ash has strong alkalinity, a large amount of stockpiling causes waste to land resources, and harmful substances in the fly ash gradually permeate into the ground surface and surrounding water bodies to cause certain harm to the environment; and the fly ash dust can also pollute the surrounding air. However, the fly ash has more potential utilization value, wherein the content of silicon dioxide and aluminum oxide is high, the fly ash contains a glass phase and unburned carbon, and has good activity, and the performance of the ceramsite prepared by the fly ash serving as a raw material can be improved. Heavy metal elements in the fly ash exist in the form of aggregates, the activity is relatively low, heavy metal pollution to soil cannot be caused, and the fly ash is used for soil improvement in agriculture in the prior art. The potential value of the fly ash is reasonably recycled, and more economic values can be created while the problem of environmental pollution is solved.

The ceramsite is a ceramic particle generated by foaming, is one of novel materials which are developed rapidly in China in recent years, and has become the largest world China for producing the ceramsite, and the volume density of the ceramsite is 0.8-2.0g/cm³Much lower than the bulk density of natural agglomerates (typically 2.4-2.8 g/cm)³). The ceramsite has the advantages of small density, porous interior, uniform shape and components, large specific surface area and the like, and is widely applied. The raw materials for the preparation of the ceramsite must comprise two important components: one is a component that generates gas at high temperature, i.e., a pore-forming agent; the other one is that the ceramic particle can generate a molten phase with enough viscosity at high temperature, so that gas is reduced from overflowing to the outside, and the gas can move in the ceramic particle as much as possible, so that more holes are formed in the ceramic particle, the volume density of the ceramic particle is reduced, and the water retention performance and the adsorption performance are enhanced.

The yield of the by-product coffee grounds of the instant coffee is large, and 0.9kg of coffee grounds can be generated when 1kg of instant coffee is produced. The coffee grounds have high yield as agricultural and forestry wastes, and the dry matters of the coffee grounds comprise about 6% of moisture, 62% of volatile components, 23% of fixed carbon and 9% of ash, and researches show that the coffee grounds can be completely combusted at 520 ℃, only about 8% of ash is left, and most of the rest components can react at high temperature to generate a large amount of gas. In addition, the coffee grounds can also emit a large amount of heat energy during combustion, thereby being beneficial to sintering of the ceramsite; according to the principle of 'treating waste by waste', the waste is used as much as possible for preparing the material, so that the coffee grounds are used as the pore-forming agent for preparing the ceramsite, the coffee grounds are decomposed in the high-temperature roasting process of the ceramsite to generate gas, and a pore channel is formed in the ceramsite, thereby being beneficial to enhancing the porous performance of the ceramsite.

In the existing research, the preparation of ceramsite by utilizing red mud is still reported, so the invention combines the characteristics of coffee grounds, red mud and fly ash, mixes the three materials according to a certain proportion to prepare the ceramsite, and combines the biomass with the ceramsite by adopting an in-situ hydrothermal carbonization mode to produce the material with soil improvement performance.

Disclosure of Invention

In order to prepare a ceramsite material combined with biomass, improve the soil improvement performance of the ceramsite material and expand the application range of the ceramsite material, the invention provides a method for preparing a soil conditioner by utilizing ceramsite in-situ hydrothermal combined with biochar.

The invention is realized by the following technical scheme:

a method for preparing a soil conditioner by utilizing ceramsite in-situ hydrothermal combination with biochar comprises the following steps:

(1) preparing ceramsite: uniformly mixing fly ash, red mud, phosphogypsum and biomass, adding deionized water for pelletizing, then placing into a muffle furnace, roasting ceramsite by adopting a stepped heating method, and naturally cooling to room temperature after roasting; the addition amount of each raw material in the mixed material is 60-85 parts by weight of fly ash; 40-15 parts of red mud; 10-30 parts by weight of phosphogypsum; the biomass is 10-50 parts by weight.

(2) Biomass-bonded ceramsite: KOH and NH₄Mixing Cl and deionized water according to a ratio to obtain a mixed solution, adding biomass, taking dry ceramsite into a reaction kettle, and adding the mixed solution to completely soak the ceramsite; after the reaction kettle is tightly covered, the reaction kettle is placed in a drying box, after the reaction is finished and the reaction kettle is naturally cooled, the ceramsite is taken out, cleaned and dried to obtain the ceramsite in-situ hydrothermal junctionAnd synthesizing biochar.

Preferably, the biomass in the step (1) is coffee grounds, corn straw powder or organic fertilizer, and the fly ash, the red mud, the phosphogypsum and the biomass are sieved by a 100-mesh sieve.

Preferably, the diameter of the spherical blank obtained after the pelletization in the step (1) of the present invention is 5-10 mm.

Preferably, the specific process of the calcination in step (1) of the present invention comprises: and (3) a drying stage: heating to 105 ℃ at the heating rate of 3 ℃/min, and preserving the heat of the ceramsite for 180min at the temperature of 105 ℃; a preheating stage: heating to 400 ℃ at the heating rate of 5 ℃/min, and preserving the heat of the ceramsite at 400 ℃ for 30 min; and (3) roasting: heating to 800-1200 ℃ at the heating rate of 6-12 ℃/min, and roasting the ceramsite at the temperature of 800-1200 ℃ for 10-40 min.

Preferably, the amount of KOH added in step (2) of the present invention is 10.0 to 40.0g/L, NH₄The addition amount of Cl is 10.0-20.0 g/L, and the solvent is deionized water.

Preferably, the biomass in the step (2) is whole corn straw, corn straw inner core or corn straw outer shell powder, and the biomass is sieved by a 100-mesh sieve, wherein the addition amount is 10.0-40.0 g/L.

Preferably, the reaction temperature in the step (2) of the invention is 120-.

In the step (1), the water is added into the mixture to the extent that the mixture can be bonded and the surface of the mixture has certain moisture.

The invention has the advantages that:

(1) the invention can realize the resource utilization of the red mud and the fly ash solid wastes, and fixes harmful substances in the ceramsite by the toxic and harmful solid wastes in a high-temperature mode, thereby reducing the pollution of the solid wastes, enhancing the water-retaining property of the soil and endowing the soil with the property of improving the soil.

(2) Different biomass is combined with the ceramsite, so that different ceramsite soil improvement performances can be realized, and different substances are adsorbed by using functional groups of different biomass, so that the soil can be regulated and controlled to improve different performances; or the organic fertilizer and the ceramsite carrier can be compounded to form an organic-inorganic complex, so that the slow-release fertilizer effect on the soil is achieved.

(3) The preparation of the ceramsite by the stepwise temperature rise can reasonably control the firing of the ceramsite, and the temperature rise enables SiO in the ceramsite blank₂And Al₂O₃The materials are more completely melted, so that more materials are converted into viscous liquid, the internal holes of the ceramsite are expanded to the maximum extent, and the water retention performance of the ceramsite is enhanced.

(4) The method has the advantages of simple operation and few process steps; the combination of the materials and the biomass can be realized, and the soil can be improved.

Description of the drawings:

FIG. 1 is a graph comparing the effect of biomass content in ceramsite on the water absorption of ceramsite;

FIG. 2 is a graph comparing the effect of the baking temperature of ceramsite on the water absorption of ceramsite;

FIG. 3 is a graph showing the effect of different biomass on the water absorption of ceramsite.

Detailed Description

The present invention will be further illustrated with reference to the following examples, which are not intended to limit the scope of the present invention.

Example 1

(1) preparation of ceramsite

Mixing materials: 8.5g of fly ash, 1.5g of red mud and a certain amount of biomass are taken to be sieved by a 100-mesh sieve, the fly ash and the red mud are mixed to form a fly ash-red mud mixture, 1.5g of phosphogypsum powder sieved by the 100-mesh sieve is added, and then the biomass and the fly ash-red mud are mixed to form a ceramsite preparation raw material.

Pelletizing: adding a proper amount of water into the ceramsite preparation raw materials to enable the ceramsite preparation raw materials to be capable of being bonded and the surface of the ceramsite preparation raw materials still has a certain amount of water, manually pelletizing, manufacturing the ceramsite preparation raw materials into a spherical blank with the diameter of 10mm, and placing the blank into a tray to be naturally air-dried for 1 hour after the pelletizing is finished.

Roasting the ceramsite by adopting a stepped heating method: and (3) a drying stage: heating to 105 ℃ at the heating rate of 3 ℃/min, and preserving the heat of the ceramsite for 180min at the temperature of 105 ℃; a preheating stage: heating to 400 ℃ at the heating rate of 5 ℃/min, and preserving the heat of the ceramsite at 400 ℃ for 30 min; and (3) roasting: heating to 800 ℃ at the heating rate of 6 ℃/min, roasting the ceramsite for 20min at 800 ℃, and naturally cooling to room temperature after roasting to obtain the ceramsite.

(2) Biomass-bonded ceramsite: adding 1gKOH and 1gNH₄Mixing Cl and 75ml of deionized water, adding 1g of whole corn straw, sieving with a 100-mesh sieve, taking 10g of dried ceramsite in a reaction kettle, and adding the mixed solution to completely soak the ceramsite; and (3) tightly covering the reaction kettle, putting the reaction kettle into a drying box, preserving heat at 160 ℃ for 3 hours, and after the reaction is finished and the reaction kettle is naturally cooled, taking out the ceramsite, cleaning and drying to finish the hydrothermal carbonization and biochar combination of the ceramsite.

In the step (1) of this embodiment, an organic fertilizer is selected from the biomass, the addition amounts of the organic fertilizer are 1.8g, 2.4g, 3.0g, 3.6 g and 4.2 g, five samples are finally obtained, the obtained ceramsite is dried at 105 ℃ for 5 hours, the weight of the ceramsite is weighed before and after soaking the ceramsite for 24 hours, and the water absorption of the ceramsite is calculated as follows: the water absorption rates corresponding to the ceramsite with different proportions are shown in table 1 and figure 1:

TABLE 1

As can be seen from Table 1, the addition of biomass affects the water absorption of different ceramic particles; experiments show that the water absorption performance of the finally prepared ceramsite hydrothermal carbonization combined biochar material is equivalent to that of ceramsite.

Example 2

(1) preparing ceramsite:

mixing materials: 8.0g of fly ash, 3.0g of red mud, 2.0g of phosphogypsum and a certain amount of biomass are taken to pass through a 100-mesh sieve, the fly ash and the red mud are mixed to form a fly ash-red mud mixture, 1.5g of phosphogypsum powder is added, and then the biomass is mixed with the fly ash-red mud to form a ceramsite preparation raw material.

Pelletizing: adding a proper amount of water into the ceramsite preparation raw materials to enable the ceramsite preparation raw materials to be capable of being bonded and the surface of the ceramsite preparation raw materials still has a certain amount of water, manually pelletizing, manufacturing the ceramsite preparation raw materials into a spherical blank with the diameter of 5mm, and placing the blank into a tray to be naturally air-dried for 1 hour after the pelletizing is finished.

Roasting the ceramsite by adopting a stepped heating method: and (3) a drying stage: heating to 105 ℃ at the heating rate of 3 ℃/min, and preserving the heat of the ceramsite for 180min at the temperature of 105 ℃; a preheating stage: heating to 400 ℃ at the heating rate of 5 ℃/min, and preserving the heat of the ceramsite at 400 ℃ for 30 min; and (3) roasting: heating to 1110 ℃ or 900 ℃ at the heating rate of 6 ℃/min, roasting the ceramsite at 1110 ℃ or 900 ℃ for 20min, and naturally cooling to room temperature after roasting to obtain the ceramsite.

(2) Biomass-bonded ceramsite: adding 4g of KOH and 2g of NH₄Mixing Cl and 75ml of deionized water, adding 2g of whole corn straw, sieving with a 100-mesh sieve, taking 10g of dried ceramsite in a reaction kettle, and adding the mixed solution to completely soak the ceramsite; and (3) tightly covering the reaction kettle, putting the reaction kettle into a drying box, preserving heat for 2 hours at 200 ℃, taking out the ceramsite after the reaction is finished and the reaction kettle is naturally cooled, cleaning and drying the ceramsite, and finishing the hydrothermal carbonization of the ceramsite and the biochar.

In the step (1) of this embodiment, an organic fertilizer is selected as the biomass, the addition amounts of the organic fertilizer are 1.8g, 2.4g and 3.0g, the calcination temperatures are 1110 ℃ or 900 ℃, respectively, 6 samples are finally obtained, the obtained ceramsite is dried at 105 ℃ for 5 hours, the weight of the ceramsite is weighed before and after soaking the ceramsite for 24 hours, and the water absorption of the ceramsite is calculated as follows: the water absorption rates corresponding to the ceramsite with different proportions are shown in table 2 and figure 2:

TABLE 2

As can be seen from Table 2, the calcination temperature also affects the water absorption rates corresponding to different ceramic particles; experiments show that the water absorption performance of the finally prepared ceramsite hydrothermal carbonization combined biochar material is equivalent to that of ceramsite.

Example 3

(1) preparing ceramsite:

mixing materials: 6.0g of fly ash, 4.0g of red mud, 3.0g of phosphogypsum and 3.0g of biomass are taken to pass through a 100-mesh sieve, the fly ash and the red mud are mixed to form a fly ash-red mud mixture, 1.5g of phosphogypsum powder is added, and then the biomass is mixed with the fly ash-red mud to form a ceramsite preparation raw material.

Pelletizing: adding a proper amount of water into the ceramsite preparation raw materials to enable the ceramsite preparation raw materials to be capable of being bonded and the surface of the ceramsite preparation raw materials still has a certain amount of water, manually pelletizing, manufacturing the ceramsite preparation raw materials into a spherical blank with the diameter of 8mm, and placing the blank into a tray to be naturally air-dried for 1 hour after the pelletizing is finished.

Roasting the ceramsite by adopting a stepped heating method: and (3) a drying stage: heating to 105 ℃ at the heating rate of 3 ℃/min, and preserving the heat of the ceramsite for 180min at the temperature of 105 ℃; a preheating stage: heating to 400 ℃ at the heating rate of 5 ℃/min, and preserving the heat of the ceramsite at 400 ℃ for 30 min; and (3) roasting: heating to 1200 ℃ at the heating rate of 6 ℃/min, roasting the ceramsite at 1200 ℃ for 40min, and naturally cooling to room temperature to obtain the ceramsite.

(2) Biomass-bonded ceramsite: 3g of KOH and 1.5g of NH₄And mixing Cl and 75ml of deionized water, adding 4g of whole corn straw, sieving with a 100-mesh sieve, taking 10g of dried ceramsite in a reaction kettle, and adding the mixed solution to completely soak the ceramsite. And (3) tightly covering the reaction kettle, putting the reaction kettle into a drying box, preserving heat for 1h at 250 ℃, taking out the ceramsite after the reaction is finished and the reaction kettle is naturally cooled, cleaning and drying the ceramsite, and finishing the hydrothermal carbonization of the ceramsite and the biochar.

In the step (1) of this embodiment, organic fertilizer and coffee grounds are selected as biomass, 2 samples are finally obtained, the obtained ceramsite is dried at 105 ℃ for 5 hours, the weight of the ceramsite is weighed before and after the ceramsite is soaked for 24 hours, and the water absorption of the ceramsite is calculated as follows: the water absorption of the ceramsite prepared from different biomasses is shown in table 3 and fig. 3:

TABLE 3

The water absorption of the ceramsite prepared in the above example is shown in the table, and the result shows that the ceramsite soil conditioner after hydrothermal modification has good water absorption. Experiments show that the water absorption performance of the finally prepared ceramsite hydrothermal carbonization combined biochar material is equivalent to that of ceramsite.

The water in the soil can be increased due to good water absorption, meanwhile, the granular ceramsite can loosen the soil, increase the porosity, improve the air amount in the soil and facilitate the growth of plants; in addition, the ceramsite is combined with the biomass to finally form an organic-inorganic complex with a stable structure, so that the degradation rate of microorganisms to the biochar can be slowed down, the slow-release fertilizer effect on the soil is realized, the carbon dioxide release of the soil to the atmosphere can be slowed down while the fertility loss is slowed down, the greenhouse effect is relieved to a certain extent, and the using effect is good. And because the material has large particles and stable structure, the material can be recovered in application scenes applied in a small range such as nursery seedling culture and the like, and the improvement scheme of soil can be timely modified and the cyclic utilization of resources can be realized.

Claims

1. A method for preparing a soil conditioner by utilizing ceramsite in-situ hydrothermal combination with biochar is characterized by comprising the following steps:

(1) preparing ceramsite: uniformly mixing fly ash, red mud, phosphogypsum and biomass, adding deionized water for pelletizing, then placing into a muffle furnace, roasting ceramsite by adopting a stepped heating method, and naturally cooling to room temperature after roasting; the addition amount of each raw material in the mixed material is 60-85 parts by weight of fly ash; 40-15 parts of red mud; 10-30 parts by weight of phosphogypsum; 10-50 parts by weight of biomass;

(2) biomass-bonded ceramsite: KOH and NH₄Mixing Cl and deionized water in proportion to obtain a mixed solution, adding biomass, taking dry ceramsite in a reaction kettle, adding the mixed solution to completely soak the ceramsite(ii) a And (3) tightly covering the reaction kettle, putting the reaction kettle into a drying box, and after the reaction is finished and the reaction kettle is naturally cooled, taking out the ceramsite, cleaning and drying to obtain the ceramsite in-situ hydrothermal combined biochar.

2. The method for preparing the soil conditioner by utilizing the ceramsite and the in-situ hydrothermal combination biochar according to claim 1, is characterized by comprising the following steps of: the biomass in the step (1) is coffee grounds, corn straw powder or organic fertilizer, and the fly ash, the red mud, the phosphogypsum and the biomass are sieved by a 100-mesh sieve.

3. The method for preparing the soil conditioner by utilizing the ceramsite and the in-situ hydrothermal combination biochar according to claim 1, is characterized by comprising the following steps of: the diameter of the spherical blank body obtained after the pelletizing in the step (1) is 5-10 mm.

4. The method for preparing the soil conditioner by utilizing the ceramsite and the in-situ hydrothermal combination biochar according to claim 1, is characterized by comprising the following steps of: the roasting process in the step (1) comprises the following specific steps: and (3) a drying stage: heating to 105 ℃ at the heating rate of 3 ℃/min, and preserving the heat of the ceramsite for 180min at the temperature of 105 ℃; a preheating stage: heating to 400 ℃ at the heating rate of 5 ℃/min, and preserving the heat of the ceramsite at 400 ℃ for 30 min; and (3) roasting: heating to 800-1200 ℃ at the heating rate of 6-12 ℃/min, and roasting the ceramsite at the temperature of 800-1200 ℃ for 10-40 min.

5. The method for preparing the soil conditioner by utilizing the ceramsite and the in-situ hydrothermal combination biochar according to claim 1, is characterized by comprising the following steps of: the adding amount of KOH in the step (2) is 10.0 to 40.0g/L, and NH₄The addition amount of Cl is 10.0-20.0 g/L, and the solvent is deionized water.

6. The method for preparing the soil conditioner by utilizing the ceramsite and the in-situ hydrothermal combination biochar according to claim 1, is characterized by comprising the following steps of: the biomass in the step (2) is whole corn straw, corn straw inner core or corn straw outer shell powder, and is sieved by a 100-mesh sieve, and the adding amount is 10.0-40.0 g/L.

7. The method for preparing the soil conditioner by utilizing the ceramsite and the in-situ hydrothermal combination biochar according to claim 1, is characterized by comprising the following steps of: the reaction temperature in the step (2) is 120-250 ℃, and the reaction time is 1-3 hours.