A method for preparing a fly ash-based artificial agglomerate

Abstract

The application discloses a preparation method of fly ash-based artificial aggregate, which comprises the following preparation steps: step one: in the process of configuring a microbial liquid medium, fly ash is added to adjust the pH to neutral, a strain with mineralization function is inoculated, and filtration is carried out, so that a fly ash-based aggregate skeleton, i.e., raw material A, is obtained; step two: microorganisms for forming a biofilm are extracted from soil in an ecological reclamation site of a coal mine area; step three: the microorganisms for forming the biofilm are inoculated into a biological liquid medium added with the raw material A through physical adsorption and then fermented, and in the logarithmic growth phase, the microorganisms are filtered, dried at low temperature, and then a fly ash-based aggregate skeleton with biological activity, i.e., raw material B, is obtained; step four: biochar, urea and diammonium phosphate are mixed with water, and then dried, so that raw material C is obtained; and step five: the raw material B is mixed with the raw material C, so that a fly ash-based artificial aggregate with biological activity, i.e., raw material D, is prepared. The application has the advantages of enhancing the water-retention and moisture-increasing capacity, carbon fixation and sink capacity, and improving the bearing capacity of soil.

Description

Technical Field

[0001] This invention relates to the field of fly ash-based artificial agglomerates, specifically a method for preparing fly ash-based artificial agglomerates. Background Technology

[0002] Soil aggregates are the most basic structural units of soil, serving as storage sites for soil nutrients and microenvironments for microbial growth and reproduction. However, the integrated open-pit mining activities of extraction, drainage, and remediation lead to soil structural instability and irreversible degradation. Constructing soil aggregates to improve soil water retention, moisture absorption, soil quality, and erosion resistance is an effective way to reverse this trend. Fly ash, a typical industrial solid waste generated in large quantities during coal-fired power generation, has seen its comprehensive disposal and utilization become a hot topic in recent years.

[0003] Currently, most studies on the application of fly ash in soil improvement involve direct application or comprehensive application of multi-source coal-based solid waste for soil nutrient activation and moisture retention. There are very few studies on constructing soil aggregates with microbial activity based on fly ash.

[0004] Therefore, it is of great importance to invent a method for preparing fly ash-based artificial agglomerates to enhance soil water retention, carbon sequestration, and soil carrying capacity. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing fly ash-based artificial agglomerates to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing fly ash-based artificial agglomerates, characterized by comprising the following preparation steps:

[0008] Step 1: Add fly ash to adjust the pH to neutral during the preparation of microbial liquid culture medium, inoculate with strains that have mineralization function, culture and filter to obtain fly ash group aggregate framework, i.e. raw material A;

[0009] Step 2: Extracting microorganisms that form biofilms from the soil of the ecological reclamation site in the coal mining area;

[0010] Step 3: The microorganisms that form the biofilm are inoculated into the biological liquid culture medium containing raw material A through physical adsorption and fermented. During the logarithmic growth phase, the mixture is filtered and dried at low temperature to obtain a bioactive fly ash group aggregate framework, i.e., raw material B.

[0011] Step 4: Mix biochar, urea, and diammonium phosphate with water, and dry them to obtain raw material C;

[0012] Step 5: Mix raw material B with raw material C to prepare a bioactive fly ash-based artificial agglomerate, namely raw material D.

[0013] Furthermore, the strain with mineralization function in step two is a microorganism that secretes urease and was screened from grassland reclaimed from the mine over many years. Its molecular identification result is Pasteurella multocida.

[0014] Furthermore, the microorganisms that form the biofilm in step three are microbial communities extracted from grasslands reclaimed from local mines over many years. 16S high-throughput sequencing results show that the dominant bacterial groups are Proteobacteria and Pseudomonas.

[0015] Furthermore, the components (by weight) in the raw material C are 4g-9g of urea, 1g-3g of diammonium phosphate, and 10g-18g of biochar.

[0016] Furthermore, the components (by weight) in the raw material D are raw material B 70g-85g and raw material C 15g-30g.

[0017] Furthermore, in step one, fly ash is added during the preparation of the microbial liquid culture medium to adjust the pH to 7.

[0018] Furthermore, in step three, the microorganisms that form the biofilm are inoculated into a biological liquid culture medium containing raw material A, and the fermentation time is one week.

[0019] Furthermore, the drying temperature in step four is 45°C.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] The selected mineralizing functional strains, through fermentation culture, can secrete extracellular polymers such as proteins and polysaccharides, as well as urease to promote the nucleation of calcium carbonate. On the one hand, this increases the specific surface area and improves the colonization of microorganisms that form biofilms; on the other hand, it can passivate and flocculate heavy metals and other substances, thus achieving low-harm or harmless treatment of fly ash.

[0022] Raw material B is prepared by inoculating microorganisms that form biofilms into a liquid culture medium containing raw material A for fermentation. Raw material C is prepared by mixing urea, diammonium phosphate and biochar. Biochar adsorbs urea and phosphate due to its abundant functional groups on its surface, thus producing a material with nitrogen and phosphorus slow-release function. At the same time, biochar can also provide a variety of trace elements. By mixing raw material C and raw material B, a bioactive fly ash-based artificial agglomerate is obtained. Attached Figure Description

[0023] Figure 1 This is a SEM image of the surface of coal-based solid waste colonized by microorganisms according to the present invention. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0025] Example 1:

[0026] The present invention provides a method for preparing fly ash-based artificial agglomerates, comprising the following steps:

[0027] Step 1: Add fly ash to adjust the pH to 7 during the preparation of microbial liquid culture medium, inoculate with strains that have mineralization function and culture for 2 weeks, filter to obtain fly ash group aggregate skeleton, i.e. raw material A;

[0028] Step 2: Extracting microorganisms that form biofilms from the soil of ecological reclamation sites in Inner Mongolia coal mining areas;

[0029] Step 3: The microorganisms that form the biofilm are inoculated into the liquid culture medium containing raw material A through physical adsorption and fermented for one week. During the logarithmic growth phase of the microorganisms, the mixture is filtered and dried at low temperature to obtain raw material B, thus obtaining a bioactive fly ash group aggregate framework.

[0030] Step 4: Mix biochar, urea, and diammonium phosphate with water in a ratio of 10:4:1, and dry at around 45°C to obtain raw material C;

[0031] Step 5: Mix raw material B and raw material C at a ratio of 7:3 to prepare a bioactive fly ash-based artificial agglomerate, namely raw material D.

[0032] Example 2:

[0033] The present invention provides a method for preparing fly ash-based artificial agglomerates, comprising the following specific steps:

[0034] Step 1: Add fly ash to adjust the pH to 7 during the preparation of microbial liquid culture medium, inoculate with strains that have mineralization function and culture for 2 weeks, filter to obtain fly ash group aggregate skeleton, i.e. raw material A;

[0035] Step 2: Extracting microorganisms that form biofilms from the soil of ecological reclamation sites in Inner Mongolia coal mining areas;

[0036] Step 3: The microorganisms that form the biofilm are inoculated into the liquid culture medium containing raw material A through physical adsorption and fermented for one week. During the logarithmic growth phase of the microorganisms, the mixture is filtered and dried at low temperature to obtain raw material B, thus obtaining a bioactive fly ash group aggregate framework.

[0037] Step 4: Mix biochar, urea, and diammonium phosphate with water in a ratio of 18:9:3, and dry at around 45°C to obtain raw material C;

[0038] Step 5: Mix raw material B and raw material C at a ratio of 17:3 to prepare a bioactive fly ash-based artificial agglomerate, namely raw material D.

[0039] Example 3:

[0040] The present invention provides a method for preparing fly ash-based artificial agglomerates, comprising the following specific steps:

[0041] Step 1: Add fly ash to adjust the pH to 7 during the preparation of microbial liquid culture medium, inoculate with strains that have mineralization function and culture for 2 weeks, filter to obtain fly ash group aggregate skeleton, i.e. raw material A;

[0042] Step 2: Extracting microorganisms that form biofilms from the soil of ecological reclamation sites in Inner Mongolia coal mining areas;

[0043] Step 3: The microorganisms that form the biofilm are inoculated into the liquid culture medium containing raw material A through physical adsorption and fermented for one week. During the logarithmic growth phase of the microorganisms, the mixture is filtered and dried at low temperature to obtain raw material B, thus obtaining a bioactive fly ash group aggregate framework.

[0044] Step 4: Mix biochar, urea, and diammonium phosphate with water in a ratio of 12:7:2, and dry at around 45°C to obtain raw material C;

[0045] Step 5: Mix raw material B and raw material C at a ratio of 8:2 to prepare a bioactive fly ash-based artificial agglomerate, namely raw material D.

[0046] The following data were obtained by comparing the fly ash-based artificial agglomerates prepared in Examples 1-3 above:

[0047] Table 1 Soil aggregate content in different implementation cases

[0048] >2mm 0.0014 0.0007 0.0001 2-1mm 0.0420 0.0250 0.0191 1-0.5mm 0.0821 0.0531 0.0418 0.5-0.25mm 0.0555 0.1631 0.1427 0.25-0.106mm 0.2274 0.2881 0.2651 Average weight diameter of aggregates / mm 0.1237 0.1244 0.1041

[0049] As shown in the table above, the fly ash-based artificial agglomerates prepared in Examples 1-3 all showed good performance in promoting the formation of soil agglomerates. After use, Example 2 showed the best effect, with the largest average weight particle size of the agglomerates and a higher proportion of soil agglomerates with a diameter of 0.5-0.25 mm.

[0050] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing fly ash-based artificial agglomerates, characterized in that, The preparation steps include the following: Step 1: Add fly ash to adjust the pH to neutral during the preparation of microbial liquid culture medium, inoculate with strains that have mineralization function, culture and filter to obtain fly ash group aggregate framework, i.e. raw material A; Step 2: Extracting microorganisms that form biofilms from the soil of the ecological reclamation site in the coal mining area; Step 3: The microorganisms that form the biofilm are inoculated into the biological liquid culture medium containing raw material A through physical adsorption and fermented. During the logarithmic growth phase, the microorganisms are filtered and dried at low temperature to obtain the bioactive fly ash group aggregate framework, i.e., raw material B. Step 4: Mix biochar, urea, and diammonium phosphate with water, and dry them to obtain raw material C; Step 5: Mix raw material B with raw material C to prepare a bioactive fly ash-based artificial agglomerate, namely raw material D; The mineralization-functional strain in step two is a microorganism that secretes urease and was screened from grassland reclaimed from the mine over many years. Its molecular identification result is Pasteurella multocida. The microorganisms that form the biofilm in step three are microbial communities extracted from grasslands reclaimed from local mines over many years. 16S high-throughput sequencing results show that the dominant bacterial groups are Proteobacteria and Pseudomonas.

2. The method for preparing a fly ash-based artificial agglomerate according to claim 1, characterized in that: The components of raw material C, by weight, are 4g-9g urea, 1g-3g diammonium phosphate, and 10g-18g biochar.

3. The method for preparing a fly ash-based artificial agglomerate according to claim 1, characterized in that: The components of raw material D, by weight, are raw material B 70g-85g and raw material C 15g-30g.

4. The method for preparing a fly ash-based artificial agglomerate according to claim 1, characterized in that: In step one, fly ash is added during the preparation of the microbial liquid culture medium to adjust the pH to 7.

5. The method for preparing a fly ash-based artificial agglomerate according to claim 1, characterized in that: In step three, the microorganisms that form the biofilm are inoculated into a biological liquid culture medium containing raw material A, and the fermentation time is one week.

6. The method for preparing a fly ash-based artificial agglomerate according to claim 1, characterized in that: The drying temperature in step four is 45°C.

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