Metal mine ecological restoration carbon sink accounting method

Abstract

According to the carbon sink accounting method for ecological restoration of the metal mine provided by the invention, the carbon sequestration amount of vegetation and the carbon sequestration amount of soil are calculated in stages, and the carbon sink benefits of different restoration stages can be accurately evaluated, so that the carbon sink in the whole life cycle of ecological restoration is calculated. Secondly, indirect carbon reduction measures such as solid waste utilization, acidic water treatment and photovoltaic power generation in a mine reclamation project are also considered, and the carbon reduction effect of ecological restoration is comprehensively evaluated. According to the invention, a reliable technical basis is provided for carbon sink management of a mine ecological restoration project.

Description

Technical Field

[0001] The present invention belongs to the dual carbon field, and specifically relates to a carbon sink accounting method for ecological restoration of metal mines. Background Art

[0002] The development and utilization of metal mineral resources strongly disturbs the "vegetation-soil carbon pool" within a certain time and space range, and is a key factor affecting carbon emissions in mining areas. Abandoned metal mine sites emit large amounts of solid waste. The types of abandoned sites are diverse and complex, with poor site conditions, weak ecological carrying capacity, and low comprehensive utilization rates of solid waste, causing serious damage to the ecological environment. Ecological restoration, as the main force in changing land use patterns, can achieve land reclamation where suitable, forestation where suitable, shrubs where suitable, and grass where suitable on abandoned metal mine sites, adapting to local conditions. This will increase vegetation coverage, improve the quality of forests and grasslands, increase ecosystem carbon sinks, and enhance biodiversity. This is of great strategic significance for improving and optimizing metal mine ecosystems, maintaining ecological security, building ecological civilization, and promoting harmonious coexistence between man and nature.

[0003] Currently, research on metal mine ecological restoration focuses primarily on restoring ecological benefits such as mine ecosystems and landscape functions. Few studies have examined methods for calculating emission reduction and carbon sink enhancement in mine ecological restoration. The soil quality and vegetation type involved in mine ecological restoration directly impact the restored ecosystem. Different restoration models determine the carbon sequestration capacity of the ecosystem, and different measures influence the accumulation of soil organic carbon. Different vegetation types have varying carbon storage densities. Vegetation type not only affects the vegetation carbon pool but also influences the soil carbon pool through its influence on soil factors. Engineering measures related to mine reclamation, such as comprehensive solid waste resource utilization, acidic water emission reduction, and photovoltaic power generation, are also important factors influencing mine carbon sinks. Summary of the Invention

[0004] The purpose of the present invention is to provide a carbon sink accounting method for ecological restoration of metal mines.

[0005] The technical solutions of the present invention are as follows:

[0006] A carbon sink accounting method for metal mine ecological restoration includes the following:

[0007] 1) Accounting methods for vegetation carbon sinks;

[0008] 2) Methods for calculating soil carbon sequestration;

[0009] 3) Methods for calculating indirect carbon reduction from mine ecological reclamation projects;

[0010] Furthermore, the vegetation carbon sink calculation method specifically includes:

[0011] Calculate vegetation carbon sequestration in stages based on ecosystem evolution characteristics;

[0012] The analogy method, empirical coefficient method or vegetation biomass monitoring method is used to calculate the vegetation carbon sequestration rate at each stage.

[0013] Furthermore, the ecosystem evolution stages specifically include: grassland stage, shrub-grass combined stage, tree-shrub-grass combined stage, shrub-tree and tree-dominated stage and tree-dominated stage.

[0014] Furthermore, the soil carbon sequestration calculation method specifically includes:

[0015] The formula method was used to calculate the changes in carbon sequestration caused by changes in the matrix before and after soil improvement;

[0016] Soil organic carbon content and soil bulk density were determined by monitoring method.

[0017] Furthermore, the soil improvement includes comprehensive utilization of mine solid waste as soil improvement material and surface covering.

[0018] Furthermore, the indirect carbon reduction accounting method of the mine ecological reclamation project specifically includes:

[0019] The indirect carbon reduction of mine ecological reclamation projects includes carbon reduction from comprehensive utilization of solid waste, carbon reduction from acidic water treatment and carbon reduction from photovoltaic utilization in mines.

[0020] Carbon reduction from comprehensive utilization of solid waste: Calculate the carbon emissions reduced from solid waste disposal due to comprehensive utilization of mine solid waste;

[0021] Carbon reduction from acidic water treatment: Calculate the annual reduction in acidic wastewater after the implementation of ecological restoration, and calculate the carbon reduction based on the carbon emissions reduced by acidic water treatment;

[0022] Carbon reduction from photovoltaic utilization in mines: Calculate the carbon reduction from energy substitution brought about by photovoltaic utilization in mine ecological restoration areas;

[0023] Other indirect carbon reduction measures include other indirect measures that result in carbon reduction.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] Ecological restoration is a systematic project, and vegetation succession and environmental changes run through the entire process. First, the present invention combines the different vegetation succession stages in the ecological restoration process, and by calculating the carbon sequestration of vegetation and soil in stages, it can accurately evaluate the carbon sink benefits of different restoration stages, thereby calculating the carbon sink throughout the life cycle of ecological restoration. Secondly, indirect carbon reduction measures such as solid waste utilization, acidic water treatment and photovoltaic power generation in mine reclamation projects are also considered to comprehensively evaluate the carbon reduction effect of ecological restoration. The present invention provides a reliable technical basis for carbon sink management in mine ecological restoration projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings illustrate various embodiments generally by way of example and not limitation, and together with the description and claims, serve to explain embodiments of the invention. Where appropriate, the same reference numerals are used throughout the drawings to refer to the same or similar parts. Such embodiments are illustrative and are not intended to be exhaustive or exclusive of the embodiments of the present apparatus or method.

[0027] Figure 1 Shows a schematic diagram of the framework of the present invention;

[0028] Figure 2 It shows a schematic diagram of the waste rock field before and after ecological restoration in an embodiment of the present invention;

[0029] Figure 3 The ecological structure of the combination of shrubs and grasses at the restoration site in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0030] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0031] An embodiment of the present invention provides a method for calculating carbon sinks in metal mine ecological restoration, comprising the following steps:

[0032] 1) Calculation methods for vegetation carbon sinks

[0033] Vegetation restoration is crucial for the ecological restoration of abandoned mining sites, as the restoration of nearly all natural ecosystems presupposes the restoration of vegetation. Therefore, selecting appropriate plants based on specific environmental conditions is a key technique for ecological restoration. With the gradual introduction of restoration ecology theory, the concept of ecological restoration has shifted from simple "greening" to a "near-natural restoration" approach. This has led to the adoption of a model for the coordinated deployment of trees, shrubs, and grasses in ecological restoration projects.

[0034] The present invention adopts a phased carbon sink accounting method to calculate the carbon sink of mine ecological restoration based on the ecosystem evolution characteristics of mine ecological restoration. The vegetation carbon sequestration amount is calculated in stages according to the ecosystem evolution characteristics.

[0035] Phase 1: Year 0-2 of ecological restoration, the initial stage of mine ecological restoration, when the ground vegetation is mainly herbaceous plants, the carbon sequestration of grassland is calculated.

[0036]

[0037] Among them, C p(0～2) is the carbon sequestration amount of vegetation from year 0 to year 2, i is the number of ecological restoration sites, S gi is the grassland area for mine ecological restoration, P giis the carbon sequestration rate per unit area of ​​grassland, and k is the conversion factor between C and CO2.

[0038] The second stage: the second to fifth year of ecological restoration, a vegetation growth environment combining shrubs and grasses is formed, and the ground vegetation is mainly herbaceous plants and shrubs. The carbon sequestration of herbaceous plants and shrubs is calculated separately.

[0039]

[0040] Among them, C p(2～5) is the carbon sequestration amount of vegetation in the 2nd to 5th year, i is the number of ecological restoration sites, S gi is the grassland area for mine ecological restoration, P gi is the carbon sequestration rate of grassland per unit area, S bi is the shrub area for mine ecological restoration, P bi is the carbon sequestration rate of shrubs per unit area, and k is the conversion factor between C and CO2.

[0041] The third stage: the 5th to 10th year of ecological restoration: a mining ecosystem of "combination of trees, shrubs and grasses" is gradually formed, with ground vegetation mainly composed of herbs, shrubs and trees. The carbon sequestration of herbs, shrubs and trees is calculated separately.

[0042]

[0043] Among them, C p(5～10) is the carbon sequestration amount of vegetation in the 5th to 10th year, i is the number of ecological restoration sites, S gi is the grassland area for mine ecological restoration, P gi is the carbon sequestration rate of grassland per unit area, S bi is the shrub area for mine ecological restoration, P bi is the shrub carbon sequestration rate per unit area, S ai is the area of ​​trees for mine ecological restoration, P ai is the carbon sequestration rate of trees per unit area, and k is the conversion factor between C and CO2.

[0044] The fourth stage: the 10th to 20th year of ecological restoration: most herbaceous plants gradually degenerate, and the ground vegetation is mainly shrubs and trees. The carbon sequestration of shrubs and trees is calculated separately.

[0045]

[0046] Among them, C p(10～20) is the carbon sequestration of vegetation in the 10th to 20th year, i is the number of ecological restoration sites, S bi is the shrub area for mine ecological restoration, P bi is the shrub carbon sequestration rate per unit area, S ai is the area of ​​trees for mine ecological restoration, P aiis the carbon sequestration rate of trees per unit area, and k is the conversion factor between C and CO2.

[0047] Phase 5: More than 20 years of ecological restoration: Shrubs and herbaceous plants have completed degradation, and the ground vegetation is mainly trees. The carbon sequestration of trees is calculated.

[0048]

[0049] Among them, C p(20～) is the amount of carbon sequestered by vegetation after the 20th year, i is the number of ecological restoration sites, S ai is the area of ​​trees for mine ecological restoration, P ai is the carbon sequestration rate of trees per unit area, and k is the conversion factor between C and CO2.

[0050] The vegetation carbon sequestration rate is calculated using the analogy method, empirical coefficient method, and vegetation carbon sequestration monitoring method.

[0051] 2) Calculation methods for soil carbon sequestration

[0052] Soil carbon sequestration is calculated based on the characteristics of soil improvement in abandoned mines. Because abandoned mines are primarily waste rock dumps and mining pits, the original site type before ecological restoration was primarily composed of large-particle waste rock. Therefore, the soil carbon sequestration before restoration is assumed to be 0.

[0053] The change in carbon sequestration due to soil improvement is calculated using the following formula:

[0054] C s =S×C×D×r

[0055] Where: C s is the soil organic carbon stock; S is the ecological restoration area; C is the soil organic carbon content; D is the thickness of the soil covering the ecological restoration area; r is the soil bulk density.

[0056] Soil organic carbon content and soil bulk density were determined by monitoring method.

[0057] 3) Indirect carbon reduction accounting method for mine ecological restoration projects

[0058] Calculate the carbon reduction brought about by the comprehensive utilization of solid waste as a soil improvement matrix, the reduction of acidic water emissions brought about by ecological restoration, the utilization of photovoltaics in ecological restoration sites, and other engineering measures.

[0059] Carbon reduction from comprehensive solid waste utilization: This refers to the carbon reduction from solid waste disposal resulting from comprehensive solid waste utilization. Mine ecological restoration often utilizes solid waste from mine wastewater treatment as a soil improvement substrate. Compared to traditional acid waste rock field ecological restoration methods, this further reduces the amount of lime used and avoids carbon emissions from lime application. For example, neutralized sludge produced from acid mine water treatment is often used to improve the substrate for acidic soils. The carbon reduction from comprehensive solid waste utilization is calculated as follows:

[0060] C w =W×P w ×k

[0061] Among them, C w is the carbon reduction amount of comprehensive utilization of solid waste, W is the comprehensive utilization amount of mine solid waste, P w is the carbon emission per unit mass of solid waste treated, and k is the conversion factor between C and CO2.

[0062] Carbon reduction from acidic wastewater treatment: This measure measures the reduction in acidic wastewater generated after ecological restoration of abandoned sites, calculated based on the reduction in carbon emissions from acidic wastewater treatment. Mine ecological restoration significantly reduces the generation of acidic mine wastewater through soil improvement and revegetation, thereby avoiding the carbon emissions associated with its treatment.

[0063] C WT =WT×P WT ×k

[0064] Among them, C WT is the carbon reduction of acidic water treatment, WT is the reduction of acid mine drainage, P WT is the carbon emission rate per unit mass of acidic wastewater treated, and k is the conversion factor between C and CO2.

[0065] Photovoltaic utilization in mines reduces carbon emissions: The amount of carbon emissions reduced by energy substitution brought about by photovoltaic utilization in mine ecological restoration sites. Mine ecological restoration sites often adopt a restoration model of photovoltaic power generation + ecological restoration, gradually achieving a green and low-carbon transformation of the mine's energy structure while carrying out ecological restoration. Carbon dioxide emissions can be calculated using the following formula:

[0066] C l =E×EF

[0067] Where: C l is the carbon reduction amount of photovoltaic power generation energy substitution, E is the photovoltaic power generation, and EF is the carbon dioxide emission factor of coal-fired power generation.

[0068] Other indirect carbon reduction measures: carbon reduction brought about by other indirect carbon reduction measures.

[0069] 4) The total carbon sink C of the ecological restoration of abandoned metal mine sites is the sum of the vegetation carbon sink, soil carbon sequestration, and indirect carbon reduction from the mine ecological restoration project calculated in the above steps, and is calculated using the following formula:

[0070] C=C p +C s +C w +C WT +C l

[0071] Example 1:

[0072] The waste rock dump at a copper sulfide mine covers an area of ​​approximately 20 hectares. The acidic wastewater generated is temporarily stored in a downstream acidic reservoir and then treated using a high-density slurry (HDS) process to meet discharge standards. The HDS process neutralizes acidic water (after copper ion recovery), lime milk, and a certain amount of circulating slurry to control the pH. Sedimentation is then performed to separate the solid and liquid. A portion of the clarified supernatant that meets the treatment standards is directly reused in production, while the remainder is directly discharged. A portion of the bottom sludge is used as self-circulating slurry. The HDS sludge is identified as general solid waste and is handled by a qualified organization.

[0073] In 2021, the waste rock dump began to carry out ecological restoration. While the solid waste was being piled up, an interlayer of alkaline materials was used to cover it (HDS sludge and imported soil were mixed in a ratio of 4:1). The HDS sludge was filtered and transferred to the waste rock dump for comprehensive utilization of ecological restoration. Ecological restoration was carried out by combining trees, shrubs and grasses. Based on the survey of plant species, through acid resistance and drought resistance experiments, a comprehensive comparison of vegetation changes, soil changes and diversity indexes was conducted, and the best plant configuration pattern was selected as horsethorn (shrub) + locust (tree) + saltwort (tree) + alfalfa (herb) + bahia grass (herb) + tall fescue (herb) + coreopsis (herb). No photovoltaic power generation project has been implemented in this waste rock dump.

[0074] Aerial photos before and after ecological restoration are shown in Figure 2 .

[0075] The carbon sequestration amount of the ecological restoration project calculated using the calculation method of the present invention is shown in Table 1:

[0076] Table 1 Carbon sequestration calculation process of ecological restoration projects

[0077]

[0078] The above is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, can make equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, which should be covered by the scope of protection of the present invention.

Claims

1. A method for calculating carbon sinks in metal mine ecological restoration, characterized in that: These include: 1) Accounting methods for vegetation carbon sinks; 2) Methods for calculating soil carbon sequestration; 3) Indirect carbon reduction accounting method for mine ecological reclamation projects.

2. A carbon sink accounting method for metal mine ecological restoration according to claim 1, characterized in that: The calculation method of vegetation carbon sink specifically includes: Calculate vegetation carbon sequestration in stages based on ecosystem evolution characteristics; The analogy method, empirical coefficient method or vegetation biomass monitoring method is used to calculate the vegetation carbon sequestration rate at each stage.

3. A carbon sink accounting method for metal mine ecological restoration according to claim 2, characterized in that: The ecosystem evolution stages specifically include: grassland stage, shrub-grass combined stage, tree-shrub-grass combined stage, shrub-tree and tree-dominated stage, and tree-dominated stage.

4. A carbon sink accounting method for metal mine ecological restoration according to claim 1, characterized in that: The soil carbon sequestration calculation method specifically includes: The formula method was used to calculate the changes in carbon sequestration caused by changes in the matrix before and after soil improvement; Soil organic carbon content and soil bulk density were determined by monitoring method.

5. A carbon sink accounting method for metal mine ecological restoration according to claim 4, characterized in that: The soil improvement materials include solid waste generated from mine wastewater treatment.

6. A carbon sink accounting method for metal mine ecological restoration according to claim 1, characterized in that: The indirect carbon reduction accounting method of the mine ecological reclamation project specifically includes: The indirect carbon reduction from mine ecological reclamation projects includes carbon reduction from comprehensive utilization of solid waste, carbon reduction from acidic water treatment, and carbon reduction from photovoltaic utilization in mines; Carbon reduction from comprehensive utilization of solid waste: Calculate the carbon emissions reduced from solid waste disposal due to comprehensive utilization of mine solid waste; Carbon reduction from acidic water treatment: Calculate the annual reduction in acidic wastewater after the implementation of ecological restoration, and calculate the carbon reduction based on the carbon emissions reduced by acidic water treatment; Carbon reduction from photovoltaic utilization in mines: Calculate the carbon reduction from energy substitution brought about by photovoltaic utilization in mine ecological restoration areas; The formula method is used to calculate indirect carbon reduction.

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