Preparation method of fly ash-based artificial aggregate

Abstract

The invention discloses a preparation method of a fly ash-based artificial aggregate, which comprises the following preparation steps: 1, adding fly ash in the process of preparing a microbial liquid culture medium to adjust the pH value to be neutral, inoculating a bacterial strain with a mineralization function, culturing, and filtering to obtain a fly ash-based aggregate skeleton, namely a raw material A; 2, microorganisms forming a biological membrane are extracted from soil of the ecological reclamation site of the coal mine area; step 3, inoculating microorganisms forming a biological membrane into a biological liquid culture medium added with the raw material A through physical adsorption for fermentation, and performing filtration and low-temperature drying in a growth logarithmic phase to obtain a fly ash-based aggregate skeleton with biological activity, namely a raw material B; step 4, mixing charcoal, urea and diammonium phosphate with water, and drying to obtain a raw material C; and 5, mixing the raw material B with the raw material C to prepare the fly ash-based artificial aggregate with biological activity, namely a raw material D. The water retention, moisture increase, carbon sequestration and sink increase capacities of soil are enhanced, and the soil bearing capacity is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fly ash-based artificial aggregates, and specifically to a preparation method of fly ash-based artificial aggregates. Background Art

[0002] Soil aggregates are the most basic structural units of soil, the places for storing soil nutrients and the microenvironments for the growth and reproduction of microorganisms. The integrated mining-dumping-reclamation artificial open-pit mining activities lead to unstable soil structure and an irreversible degradation trend. Constructing soil aggregates to improve soil water retention, moisture conservation, quality improvement, carbon sequestration and erosion resistance has become an effective way to reverse the soil succession direction. Fly ash, as a large amount of typical industrial solid waste generated during the coal industry power generation process, the comprehensive disposal and utilization have become hot issues of fly ash in recent years.

[0003] At present, most of the research on the application of fly ash in soil improvement directly applies or comprehensively applies multi-source coal-based solid wastes for soil nutrient activation and water retention. There are few studies on building soil aggregates with microbial activity based on fly ash.

[0004] Therefore, it is particularly important to invent a preparation method of fly ash-based artificial aggregates to enhance soil water retention, moisture conservation, carbon sequestration and soil bearing capacity. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method of fly ash-based artificial aggregates to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A preparation method of fly ash-based artificial aggregates, characterized by including the following preparation steps:

[0008] Step 1: Add fly ash during the preparation of the microbial liquid medium to adjust the pH to neutral, inoculate the strains with mineralization function for culturing and filtering to obtain the fly ash-based aggregate skeleton, namely raw material A;

[0009] Step 2: Extract the microorganisms forming biofilms from the soil of the ecological restoration site in the coal mining area;

[0010] Step 3: Physically adsorb the microorganisms forming biofilms and inoculate them into the biological liquid medium added with raw material A for fermentation. Filter and dry at low temperature during the logarithmic growth phase to obtain the fly ash-based aggregate skeleton with biological activity, namely 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 and raw material C to prepare a bioactive fly ash-based artificial aggregate, namely raw material D.

[0013] Furthermore, the strain with mineralization function in Step 2 is a microorganism that can secrete urease and is screened from the grasslands reclaimed from mines for many years. Its molecular identification result is Sarcina pasteurii.

[0014] Furthermore, the microorganisms forming the biofilm in Step 3 are a microbial community extracted from the grasslands reclaimed from local mines for many years. The 16S high-throughput sequencing results show that the dominant flora are Proteobacteria and Pseudomonas.

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

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

[0017] Furthermore, in Step 1, fly ash is added during the preparation of the microbial liquid medium to adjust the pH to 7.

[0018] Furthermore, in Step 3, the microorganisms forming the biofilm are inoculated into the biological liquid medium supplemented with raw material A and fermented for one week.

[0019] Furthermore, the drying temperature in Step 4 is 45 °C.

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

[0021] The screened strain with mineralization function is fermented and cultured, which can not only secrete extracellular polymers such as proteins and polysaccharides, but also secrete urease to promote calcium carbonate nucleation. On the one hand, it increases the specific surface area and improves the colonization amount of the microorganisms forming the biofilm. On the other hand, it can passivate and flocculate heavy metals and other substances, realizing the low-toxic or non-toxic treatment of fly ash.

[0022] By inoculating the microorganisms forming the biofilm into the liquid medium containing raw material A and fermenting to prepare raw material B, mixing urea, diammonium phosphate and biochar to prepare raw material C, biochar adsorbs urea and phosphate due to its rich surface functional groups, forming a nitrogen and phosphorus slow-release functional material. At the same time, biochar can also provide various trace elements. Mixing raw material C and raw material B to obtain a bioactive fly ash-based artificial aggregate. Brief Description of the Drawings

[0023] Figure 1 It is the SEM image of the surface of the microbial colonization coal-based solid waste of the present invention. Detailed Embodiments

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0025] Example 1:

[0026] A preparation method of fly ash-based artificial aggregates provided by the present invention comprises the following steps:

[0027] Step 1: During the preparation of the microbial liquid medium, add fly ash to adjust the pH to 7, inoculate the strain with mineralization function and culture for 2 weeks, then filter to obtain the fly ash-based aggregate skeleton, i.e., raw material A;

[0028] Step 2: Extract the microorganisms forming biofilms from the soil of the ecological restoration site in Inner Mongolia coal mine area;

[0029] Step 3: Inoculate the microorganisms forming biofilms into the liquid medium added with raw material A by physical adsorption and ferment for one week, and filter and dry at low temperature during the logarithmic growth phase of the microorganisms to obtain raw material B, and obtain the fly ash-based aggregate skeleton with biological activity;

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

[0031] Step 5: Mix raw material B and raw material C in a ratio of 7:3 to prepare the fly ash-based artificial aggregates with biological activity, i.e., raw material D.

[0032] Example 2:

[0033] A preparation method of fly ash-based artificial aggregates provided by the present invention includes the following specific steps:

[0034] Step 1: During the preparation of the microbial liquid medium, add fly ash to adjust the pH to 7, inoculate the strain with mineralization function and culture for 2 weeks, then filter to obtain the fly ash-based aggregate skeleton, i.e., raw material A;

[0035] Step 2: Extract the microorganisms forming biofilms from the soil of the ecological restoration site in Inner Mongolia coal mine area;

[0036] Step 3: Inoculate the microorganisms forming biofilms into the liquid medium added with raw material A by physical adsorption and ferment for one week, and filter and dry at low temperature during the logarithmic growth phase of the microorganisms to obtain raw material B, and obtain the fly ash-based aggregate skeleton with biological activity;

[0037] Step 4: Mix biochar, urea, and diammonium phosphate in a ratio of 18:9:3 with water, and dry at about 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 aggregate, namely raw material D.

[0039] Example 3:

[0040] A preparation method of a fly ash-based artificial aggregate provided by the present invention includes the following specific steps:

[0041] Step 1: Add fly ash during the preparation of the microbial liquid medium to adjust the pH to 7, inoculate the strain with mineralization function and culture for 2 weeks, then filter to obtain a fly ash-based aggregate skeleton, namely raw material A;

[0042] Step 2: Extract the microorganisms forming biofilms from the soil of the ecological restoration site in Inner Mongolia coal mine area;

[0043] Step 3: Inoculate the microorganisms forming biofilms into the liquid medium added with raw material A by physical adsorption and ferment for one week, and filter and dry at low temperature during the logarithmic growth phase of the microorganisms to obtain raw material B, and obtain a fly ash-based aggregate skeleton with biological activity;

[0044] Step 4: Mix biochar, urea, and diammonium phosphate at a ratio of 12:7:2 with water and dry at about 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 aggregate, namely raw material D.

[0046] Compare the fly ash-based artificial aggregates prepared in the above Examples 1-3 to obtain the following data:

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

[0048] Soil aggregate content / % Example 1 Example 2 Example 3 > 2 mm 0.0014 0.0007 0.0001 2 - 1 mm 0.0420 0.0250 0.0191 1 - 0.5 mm 0.0821 0.0531 0.0418 0.5 - 0.25 mm 0.0555 0.1631 0.1427 0.25 - 0.106 mm 0.2274 0.2881 0.2651 Aggregate mean weight diameter / mm 0.1237 0.1244 0.1041

[0049] As can be seen from the above table, the fly ash-based artificial aggregates prepared in Examples 1-3 all have good performance in promoting the formation of soil aggregates. After use, the effect of Example 2 is the best, the average weight diameter of the aggregates is the largest, and the proportion of 0.5-0.25 mm soil aggregates is more.

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

Claims

1. A method for preparing fly ash-based artificial aggregates, characterized in that: The method comprises the following preparation steps: Step 1: during the preparation of the microbial liquid culture medium, fly ash is added to adjust the pH to neutral, and a strain with mineralization function is inoculated, cultured, and filtered to obtain a fly ash group polymer skeleton, i.e., raw material A; Step 2: Extracting biofilm-forming microorganisms from the soil of the ecological reclamation site in the coal mining area; Step 3: inoculating the biofilm-forming microorganisms into the biological liquid culture medium with raw material A added by physical adsorption, fermenting, filtering and low-temperature drying during the logarithmic growth phase, and obtaining a fly ash polymer skeleton with biological activity, namely raw material B; Step 4: adding water to biochar, urea and diammonium phosphate, mixing and drying to obtain raw material C; Step 5: Mix raw material B with raw material C to prepare fly ash-based artificial aggregates with biological activity, namely raw material D.

2. The method for preparing fly ash-based artificial aggregates according to claim 1, characterized in that: The bacterial strain with mineralization function in step 2 is a microorganism capable of secreting urease screened from grassland reclaimed from mines for many years, and its molecular identification result is Sarcina pasteurii.

3. The method for preparing fly ash-based artificial aggregates according to claim 1, characterized in that: The microorganisms forming the biofilm in step 3 are microbial communities extracted from grassland reclaimed from local mines for many years. The results of 16S high-throughput sequencing show that the dominant bacterial communities are Proteobacteria and Pseudomonas.

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

5. The method for preparing fly ash-based artificial aggregates according to claim 1, characterized in that: The components (by weight) in the raw material D are respectively 70g-85g of raw material B and 15g-30g of raw material C.

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

7. The method for preparing fly ash-based artificial aggregates according to claim 1, characterized in that: In the step 3, the biofilm-forming microorganisms are inoculated into the biological liquid culture medium to which the raw material A is added, and the fermentation time is one week.

8. The method for preparing fly ash-based artificial aggregates according to claim 1, characterized in that: The drying temperature in step 4 is 45°C.

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