Ecological restoration composite material for high and steep slope of abandoned mine and ecological restoration and evaluation method

Abstract

The invention relates to a preparation method of a composite material for repairing the ecology of a high and steep slope of an abandoned mine, a composite material for improving the ecology of the high and steep slope of the abandoned mine repaired by dredged sludge, a method for improving the ecology of the high and steep slope of the abandoned mine repaired by dredged sludge and an evaluation method for ecological restoration of the high and steep slope of the abandoned mine. The preparation method of the composite material for repairing the ecology of the high and steep slope of the abandoned mine comprises the following steps: carrying out flocculating settling treatment on screened dredged sludge by utilizing chitosan and polyacrylamide; collecting pretreated sludge from the dredged sludge subjected to filter-press dehydration treatment; and mixing the pretreated sludge with calcium lignosulphonate, straw fibers, humic acid powder, a microbial agent and grass seeds, and uniformly stirring to form the composite material. By the adoption of the method, dredged sludge can be improved, the high and steep slope of the abandoned mine can be effectively repaired, the repairing effect is quantitatively evaluated, the scientificity and sustainability of repairing work are ensured, and green and sustainable development of the mine is promoted.

Description

Technical Field

[0001] This application relates to the field of rock slope ecological restoration technology, and in particular to a method for preparing a composite material for restoring the ecology of steep slopes in abandoned mines, a composite material for restoring the ecology of steep slopes in abandoned mines by improving dredged silt, a method for restoring the ecology of steep slopes in abandoned mines by improving dredged silt, and an evaluation method for ecological restoration of steep slopes in abandoned mines. Background Technology

[0002] In recent years, ecological and environmental issues have received increasing attention. Among them, steep rock slopes in open-pit mines are one of the key and challenging aspects of ecological restoration. Due to the effects of long-term mining, destructive development, and natural weathering, steep rock slopes in abandoned mines typically exhibit characteristics such as hard surfaces and poor soil stabilization, often facing serious problems such as soil erosion, soil infertility, and insufficient vegetation cover. Therefore, it is urgent to cover rock slopes with large amounts of high-quality soil to create favorable conditions for vegetation growth and achieve long-term revegetation of steep rock slopes.

[0003] my country has a dense river network and numerous lakes. With the rapid advancement of water system dredging projects and the construction of ports and coastlines, the output of dredged silt is increasing year by year. Against the backdrop of increasingly scarce land and high-quality soil resources, dredged silt, as a resource-rich waste, has the potential to provide natural cover soil for mine ecological restoration. However, dredged silt often suffers from high water content, poor mechanical properties, and potential heavy metal pollution. If applied directly to mine slopes without effective treatment, it may trigger geological disasters and environmental problems such as landslides and secondary pollution. Therefore, it is urgent to develop effective technologies to transform dredged silt into renewable geotechnical engineering materials for the ecological restoration of steep slopes in abandoned mines, achieving resource recycling.

[0004] Currently, research on the use of dredged silt for ecological restoration is scarce, and related restoration effects and evaluation methods are not yet perfected, leaving many technological gaps. Therefore, there is an urgent need to propose a new technical solution and a corresponding restoration effect evaluation system to optimize the effective utilization of dredged silt and the overall effect of mine ecological restoration. Summary of the Invention

[0005] Based on this, it is necessary to address the aforementioned technical problems by providing a method for preparing a composite material for ecological restoration of steep slopes in abandoned mines, which significantly improves the properties of dredged sludge through harmless treatment and transformation, enabling it to be used as an economical and environmentally friendly cover material and pumped to steep rock slopes in mines for ecological restoration; a composite material for ecological restoration of steep slopes in abandoned mines using improved dredged sludge; a method for ecological restoration of steep slopes in abandoned mines using improved dredged sludge; and an evaluation method for ecological restoration of steep slopes in abandoned mines.

[0006] In a first aspect, this application provides a method for preparing a composite material for restoring the ecology of steep slopes in abandoned mines, comprising:

[0007] Step S100: Take the cleaned dredged sludge and sieve it. Use chitosan and polyacrylamide to flocculate and settle the sludge after sieving.

[0008] Step S200: Perform filter press dewatering treatment on the dredged sludge after flocculation and sedimentation treatment, and collect the pretreated sludge from the dredged sludge after filter press dewatering treatment.

[0009] Step S300: Take the pretreated sludge and mix it with calcium lignosulfonate, straw fiber, humic acid powder, microbial agent and grass seeds and stir evenly to form a composite material.

[0010] In one embodiment, in step S100, the chitosan content k is controlled within the range of 0.6% ≤ k ≤ 0.8%, and the polyacrylamide content j is controlled within the range of 1.6% ≤ j ≤ 1.8%.

[0011] In one embodiment, step S200, which involves dewatering the dredged sludge after flocculation and sedimentation treatment by pressure filtration, includes:

[0012] A plate and frame filter press was used to dewater the dredged sludge after flocculation and sedimentation treatment, and the dewatering rate was adjusted to 35% to 55%.

[0013] In one embodiment, in step S300, the amount of calcium lignosulfonate added is 2% to 4% of the mass of the pretreated sludge; the amount of straw fiber added is 8% to 12% of the mass of the pretreated sludge; the amount of humic acid powder added is 20% to 30% of the mass of the pretreated sludge; the amount of microbial agent added is 3% to 5% of the mass of the pretreated sludge; the amount of grass seed added is 1% to 3% of the mass of the pretreated sludge; and the moisture content of the resulting composite material is controlled to be in the range of 22% to 25%.

[0014] Secondly, this application provides a composite material for improving the ecology of steep slopes in abandoned mines by dredging silt. The composite material is prepared using the method for preparing a composite material for improving the ecology of steep slopes in abandoned mines provided in the first aspect.

[0015] Thirdly, this application provides a method for improving the ecological restoration of steep slopes in abandoned mines by dredging silt, including:

[0016] The composite material is uniformly spread on the surface of the steep slope of the abandoned mine to be restored. The composite material is prepared using a method for preparing composite materials for restoring the ecology of steep slopes of abandoned mines provided in the first aspect.

[0017] Fourthly, this application provides an evaluation method for the ecological restoration of steep slopes in abandoned mines, used to evaluate the restoration effect of an improved method for restoring the ecology of steep slopes in abandoned mines by dredging silt, including:

[0018] Step S1: For the steep slopes of abandoned mines after the application of composite materials, obtain the slope stability index W1 and vegetation growth index W2; wherein the composite material is prepared using a composite material preparation method for restoring the ecology of steep slopes of abandoned mines provided in the first aspect.

[0019] Step S2: Determine the weight α corresponding to the slope stability index W1 and the weight β corresponding to the vegetation growth index W2 based on the slope of the steep slope of the abandoned mine after the application of composite materials.

[0020] Step S3: Based on the slope stability index W1 and its corresponding weight α, and the vegetation growth index W2 and its corresponding weight β, establish a contribution index model for the restoration of steep slopes in abandoned mines using improved dredged silt. Evaluate the restoration effect of a method for restoring the ecology of steep slopes in abandoned mines using improved dredged silt based on the restoration contribution index output by the model. The larger the restoration contribution index, the better the restoration effect.

[0021] In one embodiment, the evaluation indicators of the slope stability index W1 include slope moisture content, resistance to water erosion and resistance to wind erosion, and the evaluation indicators of the vegetation growth index W2 include vegetation germination rate, vegetation root density and vegetation coverage.

[0022] In one embodiment, step S2, determining the weight α corresponding to the slope stability index W1 and the weight β corresponding to the vegetation growth index W2 based on the slope of the steep slope of the abandoned mine after the application of the composite material, includes:

[0023] When the slope of the steep slope of the abandoned mine after the application of composite materials is [30, 50], the weight α corresponding to the slope stability index W1 is 0.45, and the weight β corresponding to the vegetation growth index W2 is 0.55.

[0024] When the slope of the steep slope of the abandoned mine after the application of composite materials is (50, 70], the weight α corresponding to the slope stability index W1 is 0.60, and the weight β corresponding to the vegetation growth index W2 is 0.40.

[0025] When the slope of a steep slope in an abandoned mine after the application of composite materials is greater than 70, the weight α corresponding to the slope stability index W1 is 0.70, and the weight β corresponding to the vegetation growth index W2 is 0.30.

[0026] In one embodiment, step S3 includes:

[0027] Step S301: Calculate the slope stability index W1 according to the formula W1=0.30×a+0.35×b+0.35×c; where a is the slope moisture content score, b is the water erosion resistance score, and c is the wind erosion resistance score.

[0028] Step S302: Calculate the vegetation growth index W2 according to the formula W2=0.33×d+0.34×e+0.33×f; where d is the vegetation germination rate score, e is the vegetation root density score, and f is the vegetation coverage score.

[0029] Step S303: Establish the contribution index model for improving dredged silt to the remediation of steep slopes in abandoned mines, as shown in the following formula:

[0030] YXM=α×W1+β×W2;

[0031] Among them, YXM is the repair contribution index. The larger the YXM value, the better the repair effect.

[0032] The aforementioned methods for preparing composite materials for ecological restoration of steep slopes in abandoned mines, improving dredged sludge for ecological restoration of steep slopes in abandoned mines, and evaluating the ecological restoration of steep slopes in abandoned mines, through the harmless treatment and transformation of dredged sludge, effectively utilize improved dredged sludge to restore steep slopes in abandoned mines, thus solving the problem of insufficient resource utilization of dredged sludge. By establishing a restoration effect evaluation system, the aim is to address the problems of insufficient resource utilization of dredged sludge and the difficulty in quantifying and evaluating restoration effects in existing technologies. Quantitatively evaluating restoration effects ensures the scientific and sustainable nature of restoration work, promotes resource recycling, and drives the green and sustainable development of mines. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating a method for preparing a composite material for restoring the ecology of steep slopes in abandoned mines, a method for improving the restoration of the ecology of steep slopes in abandoned mines by dredging silt, and an evaluation method for the restoration of the ecology of steep slopes in abandoned mines, as described in one embodiment.

[0034] Figure 2 This is a flowchart illustrating a method for preparing a composite material for restoring the ecology of steep slopes in abandoned mines, a method for improving the restoration of the ecology of steep slopes in abandoned mines by dredging silt, and an evaluation method for the ecological restoration of steep slopes in abandoned mines, as described in another embodiment. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0036] In one exemplary embodiment, such as Figure 1 and Figure 2 As shown, a method for preparing a composite material for restoring the ecology of steep slopes in abandoned mines is provided. The method includes:

[0037] Step S100: Take the cleaned dredged sludge and sieve it. Use chitosan and polyacrylamide to flocculate and settle the sludge after sieving.

[0038] Specifically, the dredged sludge after cleaning is screened, and chitosan and polyacrylamide are used to flocculate and settle the sludge.

[0039] Step S200: Perform filter press dewatering treatment on the dredged sludge after flocculation and sedimentation treatment, and collect the pretreated sludge from the dredged sludge after filter press dewatering treatment.

[0040] Specifically, the dredged sludge after flocculation and conditioning is subjected to pressure filtration and dewatering treatment to collect the pretreated sludge.

[0041] Step S300: Take the pretreated sludge and mix it with calcium lignosulfonate, straw fiber, humic acid powder, microbial agent and grass seeds and stir evenly to form a composite material.

[0042] In an exemplary embodiment, in step S100, the chitosan content k is controlled within the range of 0.6% ≤ k ≤ 0.8%, and the polyacrylamide content j is controlled within the range of 1.6% ≤ j ≤ 1.8%. At this point, the sludge flocculation effect is optimal, and the dewatering performance reaches its best.

[0043] In an exemplary embodiment, step S200, which involves dewatering the dredged sludge after flocculation and sedimentation treatment by pressure filtration, includes:

[0044] A plate and frame filter press was used to dewater the dredged sludge after flocculation and sedimentation treatment, and the dewatering rate was adjusted to 35% to 55%.

[0045] In an exemplary embodiment, in step S300, the amount of calcium lignosulfonate added is 2% to 4% of the mass of the dredged sludge (i.e., pretreated sludge); the amount of straw fiber added is 8% to 12% of the mass of the dredged sludge (i.e., pretreated sludge); the amount of humic acid powder added is 20% to 30% of the mass of the dredged sludge (i.e., pretreated sludge); depending on the local climate and environment, microbial agents (including lactic acid bacteria, yeast, actinomycetes, fungi, etc.) are preferred, and the amount added is 3% to 5% of the mass of the dredged sludge (i.e., pretreated sludge); depending on the site conditions of the abandoned mine, suitable grass species (such as seeds of plants with strong heavy metal adsorption, such as pokeweed, vetiver, and wild coriander) are preferred, and the amount added is 1% to 3% of the mass of the dredged sludge (i.e., pretreated sludge); in specific implementation, one or more types can be selected and used in combination according to the physicochemical properties of the dredged sludge and the expected treatment goals. The components are thoroughly mixed by mechanical stirring to prepare a composite material, and the moisture content of the resulting composite material is controlled within the range of 22% to 25%.

[0046] In one exemplary embodiment, a composite material for improving the ecology of steep slopes in abandoned mines by dredging silt is provided. This composite material is prepared using the method described above for preparing a composite material for improving the ecology of steep slopes in abandoned mines.

[0047] In one exemplary embodiment, a method for improving the ecological restoration of steep slopes in abandoned mines by dredging silt is provided, comprising:

[0048] The composite material is uniformly spread on the surface of the steep slope of the abandoned mine to be restored. The composite material is prepared by a method for preparing composite materials for restoring the ecology of steep slopes of abandoned mines provided in the above embodiment.

[0049] For example, applying composite materials to steep slopes of abandoned mines in areas requiring ecological restoration includes the following steps:

[0050] Before applying composite materials, the slope surface is first preliminarily treated by cleaning up waste, gravel, etc. on the rock slope and repairing the rock slope surface.

[0051] Subsequently, mechanized methods were used to evenly spread the composite material on the surface of the steep slope, ensuring that the composite material coverage was uniform and of appropriate thickness.

[0052] In one exemplary embodiment, an evaluation method for ecological restoration of steep slopes in abandoned mines is provided. This method is used to evaluate the restoration effect of an improved method for dredging silt to restore the ecology of steep slopes in abandoned mines. Figure 1 and Figure 2 As shown, the method includes:

[0053] Step S1: For the steep slopes of abandoned mines after the application of composite materials, obtain the slope stability index W1 and vegetation growth index W2; wherein the composite material is prepared using a composite material preparation method for restoring the ecology of steep slopes of abandoned mines provided in the above embodiment.

[0054] Specifically, in order to achieve an accurate assessment of the ecological restoration effect of steep rock slopes, field surveys and data collection were conducted on the restored steep rock slopes to obtain key evaluation elements for the restoration effect, including the slope stability index W1 and the vegetation growth index W2.

[0055] Step S2: Determine the weight α corresponding to the slope stability index W1 and the weight β corresponding to the vegetation growth index W2 based on the slope of the steep slope of the abandoned mine after the application of composite materials.

[0056] Specifically, the weights of the slope stability index W1 and the vegetation growth index W2 are determined as α and β, respectively, based on the slope gradient of the steep rock slope.

[0057] Step S3: Based on the slope stability index W1 and its corresponding weight α and the vegetation growth index W2 and its corresponding weight β, establish a contribution index model for improving dredged silt to restore steep slopes in abandoned mines. Evaluate the restoration effect of a method for improving dredged silt to restore the ecology of steep slopes in abandoned mines based on the restoration contribution index output by the model. The larger the restoration contribution index, the better the restoration effect.

[0058] Specifically, based on the evaluation elements and their weights, the contribution index model for improving dredged silt to the restoration of steep slopes in abandoned mines is established as follows: YXM=α×W1+β×W2;

[0059] Among them, YXM is the repair contribution index. The larger the YXM value, the better the repair effect.

[0060] For example, the remediation effect level proposed in step S3 is divided into 5 levels, and the contribution index YXM of improving dredged silt to remediation of steep slopes in abandoned mines is shown in Table 1 below:

[0061] Table 1

[0062]

[0063] When YXM∈(0,20], the effect of improving dredged silt to repair steep slopes in abandoned mines is poor; when YXM∈(20,40], the effect of improving dredged silt to repair steep slopes in abandoned mines is relatively poor; when YXM∈(40,60], the effect of improving dredged silt to repair steep slopes in abandoned mines is moderate; when YXM∈(60,80], the effect of improving dredged silt to repair steep slopes in abandoned mines is good; when YXM∈(80,100], the effect of improving dredged silt to repair steep slopes in abandoned mines is excellent.

[0064] In an exemplary embodiment, the evaluation indicators of the slope stability index W1 include slope moisture content, resistance to water erosion, and resistance to wind erosion, and their assigned scores are shown in Table 2 (Scoring Table of Evaluation Indicators for the Stability Index of the Repaired Mine Slope):

[0065] Table 2

[0066]

[0067] The evaluation indicators of the vegetation growth index W2 include vegetation germination rate, vegetation root density, and vegetation coverage. The scoring values ​​are shown in Table 3 (Scoring Table of Vegetation Growth Index Evaluation Indicators for Restored Mine Slopes):

[0068] Table 3

[0069]

[0070] Specifically, the slope moisture content is the percentage of water mass in the improved dredged sludge applied to the surface of steep rock slopes (i.e., steep slopes of abandoned mines) relative to the total mass of the soil; water erosion resistance is the rate at which the improved dredged sludge effectively reduces water erosion of the soil; wind erosion resistance is the rate at which the improved dredged sludge loses soil mass during wind erosion; vegetation germination rate is the percentage of plant seeds successfully germinating in the composite material; vegetation root density is the mass of vegetation roots per unit volume of improved dredged sludge; and vegetation coverage is the percentage of the area covered by vegetation on the slope per unit area relative to the total area of ​​the constructed slope.

[0071] In an exemplary embodiment, the slope stability index α (i.e., the weight α corresponding to the slope stability index W1) and the vegetation growth index weight β (i.e., the weight β corresponding to the vegetation growth index W2) are shown in Table 4 below (Evaluation of the weighting elements for the ecological restoration effect of steep slopes in abandoned mines):

[0072] Table 4

[0073]

[0074] When the slope of the steep slope of the abandoned mine after the application of composite materials is [30, 50], the weight α corresponding to the slope stability index W1 is 0.45, and the weight β corresponding to the vegetation growth index W2 is 0.55.

[0075] When the slope of the steep slope of the abandoned mine after the application of composite materials is (50, 70], the weight α corresponding to the slope stability index W1 is 0.60, and the weight β corresponding to the vegetation growth index W2 is 0.40.

[0076] When the slope of a steep slope in an abandoned mine after the application of composite materials is greater than 70, the weight α corresponding to the slope stability index W1 is 0.70, and the weight β corresponding to the vegetation growth index W2 is 0.30.

[0077] In an exemplary embodiment, the step S3 of establishing the contribution index model for improving dredged sludge remediation of steep slopes in abandoned mines includes:

[0078] Step S301: According to the formula W1=0.30×a+0.35×b+0.35×c, the slope stability in the evaluation elements is quantified and the slope stability index W1 is calculated; where a is the slope water content score, b is the water erosion resistance score, and c is the wind erosion resistance score.

[0079] Step S302: According to the formula W2=0.33×d+0.34×e+0.33×f, the vegetation growth status in the evaluation elements is quantified, and the vegetation growth status index W2 is calculated; where d is the vegetation germination rate score, e is the vegetation root density score, and f is the vegetation coverage score.

[0080] Step S303: Establish the contribution index model for improving dredged silt to remediate steep slopes of abandoned mines according to the formula YXM=α×W1+β×W2, and obtain the contribution index YXM for improving dredged silt to remediate steep slopes of abandoned mines based on the evaluation element indices obtained in the above steps.

[0081] In one exemplary embodiment, the technical solution of the present invention will be further described using a steep slope of an abandoned mine as an example, in conjunction with the accompanying drawings of the embodiments of the present invention.

[0082] Step S10: Take the cleaned dredged sludge and screen it. Use 0.6% chitosan and 1.8% polyacrylamide to flocculate and settle the sludge after screening.

[0083] Step S20: A plate and frame filter press is used to dewater the dredged sludge after flocculation conditioning (i.e. flocculation sedimentation treatment), and the dewatering rate is adjusted to about 35% to collect the pretreated sludge.

[0084] Step S30: Take the pretreated sludge and mix it with 4% calcium lignosulfonate, 10% straw fiber, 25% humic acid powder, 4% microbial agent and 2% vetiver seeds and stir evenly to form a composite material, and control its moisture content to about 24%.

[0085] Step S40: Apply the composite material to the steep slope of the abandoned mine.

[0086] Step S50 involves accurately assessing the ecological restoration effect of steep rock slopes. Field surveys and data collection are conducted on the restored slopes. Field tests using a distributed fiber optic monitoring system reveal a slope moisture content of 20%, water erosion resistance of 80%, and wind erosion resistance of 10%. Based on the scoring rules, the slope moisture content score is assigned as a = 90, water erosion resistance score as b = 80, and wind erosion resistance score as c = 70. Through field measurements and remote sensing technology, the vegetation germination rate is found to be 70%, and the root density is 350 g / m². 3 With a vegetation coverage of 85%, the vegetation germination rate is assigned a score of d=60, the vegetation root density is assigned a score of e=70, and the vegetation coverage is assigned a score of f=85, according to the scoring rules.

[0087] In step S60, based on the steep rock slope of 60°, the weights of the slope stability index W1 and the vegetation growth index W2 are determined to be 0.60 and 0.40 respectively.

[0088] In step S70, the slope stability in the evaluation elements is quantified according to the formula W1=0.30×a+0.35×b+0.35×c, and the slope stability index W1=79.5 is calculated.

[0089] In step S71, the vegetation growth status in the evaluation elements is quantified according to the formula W2=0.33×d+0.34×e+0.33×f, and the vegetation growth status index W2=71.65 is calculated.

[0090] Step S72: Based on the formula YXM=α×W1+β×W2, establish the contribution index model for improving dredged silt to remediate steep slopes in abandoned mines. Based on the evaluation element indices obtained in the above steps, the contribution index YXM for improving dredged silt to remediate steep slopes in abandoned mines is 76.36. According to Table 1, the effect of improving dredged silt to remediate steep slopes in abandoned mines is good.

[0091] In an exemplary embodiment, an improved composite material for ecological restoration of steep slopes in abandoned mines using dredged sludge, and a method for ecological restoration and evaluation are provided, comprising the following steps: S10 sieving the cleaned dredged sludge and using chitosan and polyacrylamide for flocculation and sedimentation treatment; S20 dewatering the flocculated and conditioned dredged sludge by pressure filtration and collecting the pretreated sludge; S30 mixing the pretreated sludge with calcium lignosulfonate, straw fiber, humic acid powder, microbial agents, and grass seeds and stirring evenly to form a composite material; S40 applying the composite material to the steep slopes of abandoned mines; S50... To achieve accurate evaluation of the ecological restoration effect of steep rock slopes, field investigations and data collection are conducted on the restored steep rock slopes to obtain key evaluation elements, including the slope stability index W1 and the vegetation growth index W2. S60 determines the weights of the slope stability index W1 and the vegetation growth index W2 as α and β, respectively, based on the slope gradient of the steep rock slope. S70 establishes a contribution index model for the restoration of steep rock slopes in abandoned mines using improved dredged silt, as follows: YXM = α × W1 + β × W2; where YXM is the restoration contribution index, and a larger YXM value indicates a better restoration effect.

[0092] This invention proposes a novel technical solution that effectively repairs steep slopes of abandoned mines by improving dredging techniques. By establishing a repair effect evaluation system, the repair effect can be quantitatively assessed, ensuring the scientific nature and sustainability of the repair work, promoting resource recycling, and driving the green and sustainable development of mines.

[0093] At least some steps in the flowcharts involved in the embodiments described above may include multiple steps or multiple stages, which may be executed at different times, or may be executed in turn or alternately with other steps or at least some of the steps or stages in other steps.

[0094] For those skilled in the art, various modifications and improvements can be made without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this application shall be determined by the appended claims.

Claims

1. A method for preparing a composite material for restoring the ecology of steep slopes in abandoned mines, characterized in that, The method includes: Step S100: Take the cleaned dredged sludge and sieve it. Use chitosan and polyacrylamide to flocculate and settle the sludge after sieving. Step S200: Perform filter press dewatering treatment on the dredged sludge after flocculation and sedimentation treatment, and collect the pretreated sludge from the dredged sludge after filter press dewatering treatment. Step S300: Take the pretreated sludge and mix it with calcium lignosulfonate, straw fiber, humic acid powder, microbial agent and grass seeds and stir evenly to form a composite material.

2. The method for preparing a composite material for restoring the ecology of steep slopes in abandoned mines according to claim 1, characterized in that, In step S100, the chitosan content k is controlled within the range of 0.6% ≤ k ≤ 0.8%, and the polyacrylamide content j is controlled within the range of 1.6% ≤ j ≤ 1.8%.

3. The method for preparing a composite material for restoring the ecology of steep slopes in abandoned mines according to claim 2, characterized in that, The step S200, which involves dewatering the dredged sludge after flocculation and sedimentation, includes: A plate and frame filter press was used to dewater the dredged sludge after flocculation and sedimentation treatment, and the dewatering rate was adjusted to 35% to 55%.

4. The method for preparing a composite material for restoring the ecology of steep slopes in abandoned mines according to claim 3, characterized in that, In step S300, the amount of calcium lignosulfonate added is 2% to 4% of the mass of the pretreated sludge; the amount of straw fiber added is 8% to 12% of the mass of the pretreated sludge; the amount of humic acid powder added is 20% to 30% of the mass of the pretreated sludge; the amount of microbial agent added is 3% to 5% of the mass of the pretreated sludge; the amount of grass seed added is 1% to 3% of the mass of the pretreated sludge; and the moisture content of the resulting composite material is controlled within the range of 22% to 25%.

5. A composite material for improving the ecology of steep slopes in abandoned mines by dredging silt, characterized in that, The composite material is prepared using a method for preparing composite materials for restoring the ecology of steep slopes in abandoned mines, as provided in any one of claims 1-4.

6. A method for improving the ecological restoration of steep slopes in abandoned mines by dredging silt, characterized in that, The method includes: The composite material is uniformly spread on the surface of the steep slope of the abandoned mine to be restored. The composite material is prepared by the method of preparing composite material for restoring the ecology of steep slope of abandoned mine as provided in any one of claims 1-4.

7. An evaluation method for the ecological restoration of steep slopes in abandoned mines, characterized in that, The method described above is used to evaluate the restoration effect of an improved method for dredging silt to restore the ecology of steep slopes in abandoned mines, including: Step S1: For the steep slopes of abandoned mines after the application of composite materials, obtain the slope stability index W1 and vegetation growth index W2; wherein the composite material is prepared by a composite material preparation method for restoring the ecology of steep slopes of abandoned mines provided in any one of claims 1-4. Step S2: Determine the weight α corresponding to the slope stability index W1 and the weight β corresponding to the vegetation growth index W2 based on the slope of the steep slope of the abandoned mine after the application of composite materials. Step S3: Based on the slope stability index W1 and its corresponding weight α, and the vegetation growth index W2 and its corresponding weight β, establish a contribution index model for the restoration of steep slopes in abandoned mines using improved dredged silt. Evaluate the restoration effect of a method for restoring the ecology of steep slopes in abandoned mines using improved dredged silt based on the restoration contribution index output by the model. The larger the restoration contribution index, the better the restoration effect.

8. The evaluation method for ecological restoration of steep slopes in abandoned mines according to claim 7, characterized in that, The evaluation indicators of the slope stability index W1 include slope moisture content, resistance to water erosion and resistance to wind erosion, while the evaluation indicators of the vegetation growth index W2 include vegetation germination rate, vegetation root density and vegetation coverage.

9. The evaluation method for ecological restoration of steep slopes in abandoned mines according to claim 7, characterized in that, In step S2, determining the weight α corresponding to the slope stability index W1 and the weight β corresponding to the vegetation growth index W2 based on the slope gradient of the steep slope of the abandoned mine after applying the composite material includes: When the slope of the steep slope of the abandoned mine after the application of composite materials is [30, 50], the weight α corresponding to the slope stability index W1 is 0.45, and the weight β corresponding to the vegetation growth index W2 is 0.

55. When the slope of the steep slope of the abandoned mine after the application of composite materials is (50, 70], the weight α corresponding to the slope stability index W1 is 0.60, and the weight β corresponding to the vegetation growth index W2 is 0.

40. When the slope of a steep slope in an abandoned mine after the application of composite materials is greater than 70, the weight α corresponding to the slope stability index W1 is 0.70, and the weight β corresponding to the vegetation growth index W2 is 0.

30.

10. The evaluation method for ecological restoration of steep slopes in abandoned mines according to claim 7, characterized in that, Step S3 includes: Step S301: Calculate the slope stability index W1 according to the formula W1=0.30×a+0.35×b+0.35×c; where a is the slope moisture content score, b is the water erosion resistance score, and c is the wind erosion resistance score. Step S302: Calculate the vegetation growth index W2 according to the formula W2=0.33×d+0.34×e+0.33×f; where d is the vegetation germination rate score, e is the vegetation root density score, and f is the vegetation coverage score. Step S303: Establish the contribution index model for improving dredged silt to the remediation of steep slopes in abandoned mines, as shown in the following formula: YXM=α×W1+β×W2; Among them, YXM is the repair contribution index. The larger the YXM value, the better the repair effect.

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