Strip mine boundary optimization method simultaneously considering mining carbon emission and slope safety

Abstract

The invention relates to an open-pit mine boundary optimization method simultaneously considering mining carbon emission and slope safety. The open-pit mine boundary optimization method comprises the following steps: establishing a three-dimensional model of a mine; establishing an open-pit mining carbon emission calculation model; determining mine rock indexes and rock mass types; the mining area geology is divided, the acceptable slope angle range of each area is determined, and a slope angle combination scheme is formed; calculating a final state under each slope angle combination one by one; obtaining a realm three-dimensional geologic model sequence; the slope instability probability of each subarea is calculated; calculating the obtained carbon emission of each realm; dividing a boundary result according to an acceptable slope instability probability index, and directly calculating a benefit evaluation index of a result meeting the requirement; designing a reinforcement scheme for a result which does not meet the slope instability probability index, and calculating the minimum reinforcement workload and a benefit evaluation index thereof; and calculating comprehensive evaluation indexes of all the realm sequences to obtain an optimal realm. According to the method, carbon emission and slope safety factors are quantitatively considered in boundary optimization, and sustainable development of mines is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of open-pit mine mining boundary design, and particularly to an open-pit mine boundary optimization method that simultaneously considers mining carbon emissions and slope safety. Background Art

[0002] Open-pit mining has the advantages of low cost, strong safety, and high efficiency in the development of shallow mineral resources. In the short term, it remains the main way of mineral resource development in China. The delineation of the open-pit stope boundary determines the amount of ore mined and waste rock stripped, the impact of the entire activity on the ecological environment, and the safety and stability of the slope during the mining process. Especially for medium and large open-pit mines, minor adjustments in the boundary design will lead to significant changes in important parameters such as stripping ratio, ore quantity, and slope geometry, bringing a series of impacts on multiple aspects such as mining efficiency, slope safety and stability, and ecological environment damage.

[0003] In the traditional open-pit mine mining boundary design and optimization process, the optimization goal is the ore quantity (mining efficiency), and the ecological environment problems caused by open-pit mining and the slope safety and stability problems are studied separately and independently. This results in the inability to comprehensively consider multiple issues such as mining efficiency, ecological environment, and slope safety during the mine planning and design stage, and it is impossible to obtain the optimal solution under multi-objective conditions.

[0004] At present, in the existing open-pit mine boundary optimization methods, the mining efficiency and ecological value loss are comprehensively incorporated into the boundary design, or the mining efficiency and slope safety cost are comprehensively incorporated into the boundary design, realizing the dual-objective optimization of the open-pit mine boundary, which has promoted the development of the boundary optimization design method towards green, safe, and efficient to a certain extent. However, since the benefits obtained from mining, the ecological environment impacts caused by mining, and the slope instability caused by mining disturbances belong to problems in three different dimensions, with different quantification methods and indicators, there is still no relatively perfect method to simultaneously incorporate the three optimization goals of the benefits obtained from open-pit mining, the environmental problems caused by mining, and the slope safety and stability during the mining disturbance process into the boundary optimization method. In addition, in the boundary optimization method considering slope safety, the control of the slope shape often fixes a certain point on the slope body and then changes the angle or height, which cannot achieve random changes in the slope shape and easily leads to conflicts between the optimization results of the slope geometry and the boundary optimization results. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides an open-pit mine boundary optimization method that simultaneously considers mining carbon emissions and slope safety. The ecological and environmental problems caused by mining are quantified in the form of comprehensive carbon emissions, and the stability degree under the boundary slope form is quantified by an instability probability index. Combining with the mining benefits of the boundary, a complete set of open-pit mine boundary optimization methods that fully and simultaneously consider the ecological and environmental problems and slope stability problems brought by mining in the boundary design are established to promote the sustainable development of open-pit mine mining.

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

[0007] An open-pit mine boundary optimization method that simultaneously considers mining carbon emissions and slope safety, including:

[0008] Step 1: Respectively establish a three-dimensional geological model, an ore body model, and a grade model of the mine according to geological borehole data;

[0009] Step 2: Determine the vegetation distribution and soil structure around the mining area based on on-site investigation methods, and establish an open-pit mine mining carbon emission calculation model in combination with the economic and technical parameters of mine mining;

[0010] Step 3: Determine the strength indexes of the mine rocks based on on-site point load and laboratory tests, establish distribution functions of each strength index, obtain the distribution of rock mass structural planes, and determine the rock mass structure type;

[0011] Step 4: Divide the rock masses within the mining area according to the slope instability mode, determine the acceptable slope angle range of the rock masses in each area, use the lower limit of the acceptable slope angle of each partition as the initial boundary slope angle, and change the azimuth boundary slope angle one by one according to the same incremental step distance to obtain an orthogonal combination scheme of the boundary slope angles;

[0012] Step 5: Optimize the final boundary under each azimuth boundary slope angle combination condition one by one based on the negative cone exclusion method, and obtain parameters such as the ore quantity, waste rock quantity, average stripping ratio, and the floor areas of the boundary, waste dump, and tailings pond under each final boundary;

[0013] Step 6: Project each final boundary form onto the three-dimensional geological model of the mine one by one, and delete the geological bodies inside the final boundary to obtain a sequence of three-dimensional geological models of the mine final boundary;

[0014] Step 7: Intercept the slope profiles in the sequence of three-dimensional geological models of the final boundary according to the rock mass partitions, obtain the two-dimensional slope profiles of each final boundary in each partition, calculate the slope instability probability of each profile based on the reliability theory, and obtain the partition slope instability probability indexes of all the final boundary model sequences;

[0015] Step 8: Calculate the carbon emissions of each final pit according to the open-pit mine exploitation carbon emission calculation model in Step 2 one by one, and obtain the carbon emission evaluation indexes of each pit;

[0016] Step 9: Determine the acceptable slope instability probability index, find out the final pit results in the sequence of 3D geological models of the final pit where the slope instability probability indexes of all partitions are higher than the acceptable slope instability probability index, and obtain the benefit evaluation indexes of these final pit results;

[0017] Step 10: Extract the remaining 3D geological models of the final pit in Step 9 as a subsequence, and design slope reinforcement schemes for the partition pits in the final pits of the subsequence where the slope instability probability indexes of all partitions are lower than the acceptable slope instability probability index. Calculate the minimum reinforcement workload when the combined instability probability of the reinforced slope exceeds the acceptable slope instability probability index, and obtain the reinforcement workloads of all final pits in the subsequence. At the same time, calculate the benefit evaluation indexes of each final pit in the subsequence;

[0018] Step 11: Calculate the comprehensive evaluation indexes of all sequences of final pits, compare all comprehensive evaluation indexes, and find out the final pit with the largest comprehensive evaluation index value as the optimized result of the open-pit mine pit considering both mining carbon emissions and slope safety.

[0019] Furthermore, the economic and technical parameters of the mine exploitation include the final bench slope angle, stripping ratio, cut-off grade, mining and stripping cost, ore dressing cost, concentrate price, concentrate grade and comprehensive recovery rate;

[0020] Furthermore, the open-pit mine exploitation carbon emission calculation model is as follows:

[0021] C S = C D + C I (1)

[0022] Where: C S is the carbon emissions of the open-pit mine exploitation (t), C D is the direct carbon emissions of the open-pit mine exploitation (t), C I is the indirect carbon emissions of the open-pit mine exploitation (t).

[0023] Furthermore, the direct carbon emissions of the open-pit mine exploitation can be calculated according to the following formula:

[0024] C D = C DE + C DO + C DB (2)

[0025] Where: C DE is the carbon emissions generated by the electricity consumption in the open-pit mine exploitation (t), C DOThe carbon emissions (t) generated by the consumption of fossil energy in open-pit mining, C DB The carbon emissions (t) generated by explosive blasting in open-pit mining.

[0026] The carbon emissions generated by the consumption of electricity in open-pit mining can be calculated by the following formula:

[0027] C DE = [Q(e W1 + e W2 ) + Q1e W3 + ae W4 η e (3)

[0028] In the formula: Q is the total stripping volume (t) under the final pit limit; Q1 is the total ore volume to be processed (t) under the final pit limit; a is the mining life (years) under the final pit limit; e W1 is the average electricity consumption per unit stripping volume (kW·h / t); e W2 is the average electricity consumption for processing per unit stripping volume of rock or ore (kW·h / t); e W3 is the average electricity consumption for processing per unit ore volume to be processed; e W4 is the total annual average electricity consumption of mine auxiliary facilities and other equipment (kW·h / year), η e is the carbon emissions generated per unit electricity consumption (t / (kW·h)).

[0029] The carbon emissions generated by the consumption of fossil energy in open-pit mining can be calculated by the following formula:

[0030] C DO = Q[(d W1 + d W3 )η d1 + (d W2 + d W4 )η d2 (4)

[0031] In the formula: d W1 is the average gasoline consumption per unit stripping volume (t / t); d W2 is the average diesel consumption per unit stripping volume (t / t); d W3 is the average gasoline consumption for processing per unit stripping volume of rock or ore (t / t); d W4 is the average diesel consumption for processing per unit stripping volume of rock or ore (t / t); η d1 is the carbon emissions generated per unit gasoline consumption (t / t); η d2 is the carbon emissions generated per unit diesel consumption (t / t);

[0032] The carbon emissions generated by explosive blasting in open-pit mining can be calculated by the following formula:

[0033]

[0034] In the formula: b w is the unit consumption of explosive for ore and rock blasting (t / m 3 ); η b is the carbon emission factor of the explosive (t / t); γ is the average bulk density of ore and rock within the boundary (t / m 3 ).

[0035] Furthermore, the indirect carbon emissions in open-pit mining can be calculated by the following formula:

[0036] C I = C IF + C IR + C IT + C IS (6)

[0037] In the formula: C IF is the reduction in carbon sequestration caused by the damaged land in the open-pit stope (t); C IR is the reduction in carbon sequestration caused by the damaged land in the waste dump (t); C IT is the reduction in carbon sequestration caused by the damaged soil in the tailings pond (t); C IS is the carbon emissions generated during the production of raw materials for the construction of auxiliary facilities in the open-pit mine (t).

[0038] The reduction in carbon sequestration caused by the damaged land in the open-pit stope can be calculated by the following formula:

[0039]

[0040] In the formula: A Fi is the cumulative land damage area in the stope in the i-th year (km 2 ); p i is the proportion of damaged forest land area in the land damage area in the stope in the i-th year (%); q i is the proportion of damaged grassland area in the land damage area in the stope in the i-th year (%); y npp is the net primary productivity of forest land (t / km 2 ·year); is the CO2 fixation coefficient of forest land; h s is the average soil thickness of the damaged grassland (m); γ s is the average soil bulk density of the damaged grassland (t / m 3 ); r so is the soil organic matter content (%); r oc is the carbon content ratio in soil organic matter (%); ζ is the conversion coefficient for converting carbon to CO2, taking 3.6667.

[0041] The carbon sequestration reduction caused by the damaged land of the waste dump can be calculated by the following formula:

[0042]

[0043] Where: R i is the total cumulative amount of waste rock discharged in the i-th year (t); k w is the bulking factor of waste rock after the waste dump subsides and stabilizes; γ w is the average bulk density of waste rock (t / m 3 ); H D is the average stacking height of the waste dump (m), f D is the shape coefficient of the waste dump.

[0044] The carbon sequestration reduction caused by the damaged soil body of the tailings pond can be calculated by the following formula:

[0045]

[0046] Where: Q2 is the total amount of ore mined within the boundary (t); g o is the average grade of the ore to be processed (%); g p is the average grade of the concentrate (%); r p is the metal recovery rate of ore dressing (%); γ T is the average bulk density of the tailings after stacking (t / m 3 ); H T is the average depth of the tailings pond (m), p i ′ is the proportion of the damaged forest land area in the damaged land area of the tailings pond (%); q′ is the proportion of the damaged grassland area in the damaged land area of the tailings pond (%).

[0047] The carbon emissions generated during the production of raw materials for the construction of auxiliary facilities in open-pit mines can be calculated by the following formula:

[0048]

[0049] Where: V c is the total amount of concrete used in the construction of auxiliary facilities in open-pit mines (m 3 ); V b is the total amount of steel used in the construction of auxiliary facilities in open-pit mines (m 3 ); is the carbon emissions during the production of raw materials required for the production of unit volume of concrete (t / m 3 ); is the carbon emissions during the production of raw materials required for the production of unit volume of steel (t / m 3 ).

[0050] Further, the upper and lower limits of the acceptable slope angle range of the regional rock mass are the slope angles corresponding to the ultimate state and the safe state of the overall safety and stability of the slope under the condition of the maximum slope height in this region;

[0051] Further, the maximum slope height in the region is the vertical distance between the bottom of the ore body with the maximum burial depth in this region and the ground surface;

[0052] Further, the acceptable slope instability probability index is comprehensively selected according to the mine scale, engineering geology and hydrogeological conditions, etc.;

[0053] Further, the slope instability probability of each section is determined by the Monte Carlo simulation method;

[0054] Further, the slope reinforcement plan is the cable - anchor reinforcement type;

[0055] Further, the combined instability probability of the reinforced slope is calculated as follows:

[0056] P f (F|L,θ,X t ,n)=max{P f (F SS -e≤0),P f (F SO -f≤0)} (11)

[0057] In the formula: P f (F|L,θ,X t ,n) is the combined instability probability of the reinforced slope under different cable - anchor design parameters; P f (F SS -e≤0) is the failure probability of anti - sliding stability; P f (F SO -f≤0) is the failure probability of anti - overturning stability; e and f are the reduction constants of anti - sliding stability and anti - overturning stability respectively; L is the anchorage section length of the cable - anchor; θ is the angle between the cable - anchor and the horizontal plane; X t is the horizontal distance from the cable - anchor layout point on the slope surface to the slope toe; n is the number of rows of cable - anchors.

[0058] Among them, the anti - sliding stability and anti - overturning stability of the reinforced slope are calculated according to formulas (12) and (13) respectively:

[0059]

[0060]

[0061] In the formula: c is the cohesion of the slope rock mass (kPa); is the internal friction angle of the slope rock mass (°); A is the bottom area of the sliding surface per unit width (m2 ); W is the self-weight of the sliding mass (kN); T is the anchoring force of the cable bolt; k h is the horizontal blasting vibration acceleration coefficient; V is the resultant force of the water pressure acting on the tensile crack (kN); U is the resultant force of the water pressure acting on the bottom sliding surface (kN); X W is the horizontal distance from the acting point of the gravity of the sliding mass to the toe of the slope (m); X V is the vertical distance from the acting point of the resultant force of the water pressure acting on the tensile crack to the toe of the slope (m); X U is the shortest distance from the acting point of the resultant force of the water pressure acting on the bottom sliding surface to the toe of the slope (m); X K is the vertical distance from the acting point of the gravity of the sliding mass to the toe of the slope (m).

[0062] Furthermore, when the combined instability probability of the reinforced slope exceeds the acceptable slope instability probability index, the minimum reinforcement workload is determined as follows:

[0063] S1: Determine the distribution range of the design parameters of each cable bolt according to the geometric parameters of the slope, and substitute them into Equation (11) in the form of a uniform distribution to calculate the combined instability probability of the reinforced slope under different combinations of cable bolt design parameters;

[0064] S2: Exclude all combinations with instability probability exceeding the acceptable slope instability probability index;

[0065] S3: Calculate the cable bolt reinforcement workload of the remaining combinations and sort them, and find the combination with the lowest cable bolt reinforcement workload as the minimum reinforcement workload C when the combined instability probability of the reinforced slope exceeds the acceptable slope instability probability index Wmin .

[0066] Furthermore, the comprehensive evaluation index is calculated as follows:

[0067] C Z = λ1C S + λ2C Wmin + λ3C P (14)

[0068] In the formula: C Z is the comprehensive evaluation index for the optimization of the boundary considering carbon emissions and slope safety; λ1 is the conversion coefficient of the international carbon emission price; λ2 is the conversion coefficient of the slope treatment cost; λ3 is the conversion coefficient of the boundary profit; C P is the value of the boundary.

[0069] Compared with the prior art, the beneficial effects of the present invention are:

[0070] 1. The open-pit mine boundary optimization method considering both mining carbon emissions and slope safety takes the economic benefits of open-pit mine mining, the environmental problems caused by mining, and the slope safety and stability during the mining disturbance process as three optimization objectives, and incorporates them into the boundary optimization method at the same time. It realizes the quantitative consideration of multiple influencing factors in different dimensions during the optimization of the final boundary of the open-pit mine. This method can control the calculation accuracy and workload of the optimization model by adjusting the azimuth boundary slope angle combination scheme, and can be used for the optimization of the phased boundary or local boundary, as well as the overall boundary.

[0071] 2. The open-pit mine boundary optimization method considering both mining carbon emissions and slope safety refines and classifies the carbon emissions directly and indirectly involved in the whole process of open-pit mine mining, and gives the carbon emission calculation formula applicable to open-pit mines. According to these formulas, the carbon emission problems brought by open-pit mining can be quantified, and the dimensional consistency between the carbon emission problems and the mining benefits of the mine is realized.

[0072] 3. The open-pit mine boundary optimization method considering both mining carbon emissions and slope safety adopts the method of generating the final boundary sequence of the three-dimensional geological structure, avoiding the problem of artificial intervention in the change of slope morphology during the boundary optimization process, making the generated final boundary slope morphology have random characteristics, and solving the problem of conflict between the traditional boundary optimization method and the optimization result of the open-pit mine slope morphology.

[0073] 4. The open-pit mine boundary optimization method considering both mining carbon emissions and slope safety quantifies the slope safety and stability problem into a function related to the slope reinforcement treatment workload, realizing the quantitative consideration of slope safety and stability factors during the boundary optimization process. Description of the Drawings

[0074] Figure 1 It is a schematic flow chart of the open-pit mine boundary optimization method considering both mining carbon emissions and slope safety provided by the present invention;

[0075] Figure 2 It is a schematic flow chart for determining the minimum reinforcement workload when the combined instability probability of the slope after reinforcement exceeds the acceptable slope instability probability index in the open-pit mine boundary optimization method considering both mining carbon emissions and slope safety provided by the present invention;

[0076] Figure 3 It is a schematic diagram of the geological zoning within the mining area in the embodiment of the present invention;

[0077] Figure 4 It is a schematic slope profile diagram of the boundary sequence in the embodiment of the present invention;

[0078] Figure 5 It is a schematic diagram of the distribution trend of the comprehensive evaluation index results of the boundary sequence in the embodiment of the present invention. Detailed Embodiment

[0079] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0080] Embodiment 1:

[0081] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0082] The object of the present invention is to provide an open-pit mine boundary optimization method that simultaneously considers mining carbon emissions and slope safety, and can quantitatively consider the influence of three factors, namely boundary value, slope safety, and ecological environment, in the process of optimizing the final boundary of an open-pit mine. In this embodiment, a large open-pit iron mine is taken as an example. To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0083] As Figure 1 shown, the open-pit mine boundary optimization method that simultaneously considers mining carbon emissions and slope safety includes the following steps:

[0084] Step 1: Establish a three-dimensional geological model of the mine based on the lithology data obtained from geological boreholes, and establish an ore body model and a grade model based on the grade data obtained from geological boreholes. Since the lithology conditions in the mining area are complex, it is necessary to simplify the geological model and only retain the main rock mass structures.

[0085] Step 2: Investigate the vegetation distribution and soil structure within the scope of the open-pit iron mine mining area; determine the groundwater level within the scope of the mining area by drilling; determine the distribution of biological species in the mining area and its surroundings by sampling survey; determine the technical and economic parameters based on the mine production data; adopt the technical route of the present invention in the optimization of the boundary of the large open-pit iron mine, and the technical and economic parameters involved in the case mine are shown in Table 1;

[0086] Table 1 Technical and Economic Parameter Table

[0087]

[0088] According to on-site investigation and analysis, the carbon emissions generated during the open-pit iron ore mining process are divided into two aspects: (1) the carbon emissions directly generated by the energy and explosives consumed during the mine production process; (2) the indirect carbon emissions brought about by mine construction and production, including the reduction of carbon sequestration caused by mining and the carbon emissions generated during the production process of raw materials used for the construction of mine auxiliary facilities. The present invention uses the amount of carbon emissions to measure the carbon emission level during the open-pit iron ore mining process, specifically including:

[0089] The carbon emissions brought about by open-pit iron ore mining are calculated according to the formula C S = C D + C I ;

[0090] In the formula: C S is the carbon emissions of open-pit mine mining (t), C D is the direct carbon emissions of open-pit mine mining (t), C I is the indirect carbon emissions of open-pit mine mining (t).

[0091] Among them, the direct carbon emissions of mining are calculated according to the formula C D = C DE + C DO + C DB ;

[0092] In the formula: C DE is the carbon emissions generated by the electricity consumption of open-pit mine mining (t), C DO is the carbon emissions generated by the consumption of fossil energy in open-pit mine mining (t), C DB is the carbon emissions generated by the explosion of explosives in open-pit mine mining (t).

[0093] Among them, the carbon emissions generated by the electricity consumption of mining are calculated according to the formula C DE = [Q(e W1 + e W2 ) + Q1e W3 + ae W4 η e ;

[0094] In the formula: Q is the total stripping volume under the final pit limit (t); Q1 is the total ore volume to be processed under the final pit limit (t); a is the mining life under the final pit limit (years); e W1 is the average electric energy consumption per unit stripping volume (kW·h / t); e W2 is the average electric energy consumption for processing per unit of rock or ore for stripping volume (kW·h / t); e W3 is the average electric energy consumption for processing per unit of ore volume to be processed; e W4 is the total annual average electric energy consumption of mine auxiliary facilities and other equipment (kW·h / year), η eCarbon emissions generated per unit of electricity consumption (t / (kW·h)).

[0095] Among them, the carbon emissions generated from the consumption of fossil energy in mining are calculated according to the formula C DO = Q[(d W1 + d W3 )η d1 +(d W2 + d W4 )η d2 ; In the formula: d W1 is the average gasoline consumption per unit of overburden volume (t / t); d W2 is the average diesel consumption per unit of overburden volume (t / t); d W3 is the average gasoline consumption for processing per unit of overburden volume of rock or ore (t / t); d W4 is the average diesel consumption for processing per unit of overburden volume of rock or ore (t / t); η d1 is the carbon emissions generated per unit of gasoline consumption (t / t); η d2 is the carbon emissions generated per unit of diesel consumption (t / t).

[0096] Among them, the carbon emissions generated by explosive blasting during mining are calculated according to the formula calculate;

[0097] In the formula: b w is the explosive consumption per unit of ore and rock blasting (t / m 3 ); η b is the carbon emission factor of the explosive (t / t); γ is the average bulk density of ore and rock within the boundary (t / m 3 ).

[0098] The indirect carbon emissions of open-pit iron ore mining are calculated according to the formula C I = C IF + C IR + C IT + C IS calculate;

[0099] In the formula: C IF is the reduction in carbon sequestration caused by the damage of land in the open-pit mining area (t); C IR is the reduction in carbon sequestration caused by the damage of land in the waste dump (t); C IT is the reduction in carbon sequestration caused by the damage of soil in the tailings pond (t); C IS is the carbon emissions generated during the production of raw materials for the construction of auxiliary facilities in the open-pit mine (t).

[0100] Among them, the reduction in carbon sequestration caused by the damage of land in the open-pit mining area is calculated according to the formula calculate;

[0101] In the formula: A Fi is the cumulative land damage area of the stope in the i-th year (km 2 ); p i is the proportion of damaged forest land area in the land damage area of the stope in the i-th year (%); q i is the proportion of damaged grassland area in the land damage area of the stope in the i-th year (%); y npp is the net primary productivity of forest land (t / km 2 ·year); is the CO2 fixation coefficient of forest land; h s is the average soil thickness of the damaged grassland (m); γ s is the average soil bulk density of the damaged grassland (t / m 3 ); r so is the soil organic matter content (%); r oc is the carbon content ratio in soil organic matter (%), and ζ is the conversion coefficient of carbon to CO2, taking 3.6667.

[0102] Among them, the reduction in carbon fixation caused by land damage in the waste dump is calculated according to the formula ;

[0103] In the formula: R i is the total cumulative waste rock discharge in the i-th year (t); k w is the bulking coefficient of waste rock after the waste dump subsides and stabilizes; γ w is the average bulk density of waste rock (t / m 3 ); H D is the average stacking height of the waste dump (m), f D is the shape coefficient of the waste dump. Among them, the reduction in carbon fixation caused by land damage in the tailings pond is calculated according to the formula ;

[0104] In the formula: Q2 is the total amount of ore mined within the boundary (t); g o is the average grade of the ore to be selected (%); g p is the average grade of the concentrate (%); r p is the metal recovery rate of ore dressing (%); γ T is the average bulk density of the tailings after stacking (t / m 3 ); H T is the average depth of the tailings pond (m), p i ′ is the proportion of damaged forest land area in the land damage area of the tailings pond (%); q′ is the proportion of damaged grassland area in the land damage area of the tailings pond (%).

[0105] Among them, the carbon emissions generated in the production process of raw materials for the construction of auxiliary facilities in open-pit mines are calculated according to the formula ;

[0106] Where: V c is the total amount of concrete used in the construction of auxiliary facilities in open-pit mines (m 3 ); V b is the total amount of steel used in the construction of auxiliary facilities in open-pit mines (m 3 ); is the carbon emission during the production process of raw materials required for producing unit volume of concrete (t / m 3 ); is the carbon emission during the production process of raw materials required for producing unit volume of concrete (t / m 3 ).

[0107] Step 3: Determine the strength indexes of the mine rocks according to the in-situ point load and laboratory tests, establish the distribution functions of each strength index, obtain the distribution of rock mass structural planes, and determine the rock mass structure type;

[0108] The lithological parameters involved in the case of an open-pit iron mine are shown in Table 2:

[0109] Table 2 Mine Lithological Parameter Table

[0110]

[0111] Step 4: Divide the rock masses within the mining area according to the slope instability mode, determine the acceptable slope angle ranges for the rock masses in each area, take the lower limit of the acceptable slope angle in each area as the initial boundary slope angle, and change the azimuth boundary slope angle step by step in the same increment to obtain the orthogonal combination scheme of the boundary slope angle;

[0112] The upper and lower limits of the acceptable slope angle range of the rock mass in the area are the slope angles corresponding to the ultimate state and the safe state of the overall safety and stability of the slope under the condition of the maximum slope height in the area;

[0113] The maximum slope height in the area is the vertical distance between the bottom of the ore body with the maximum buried depth in the area and the ground surface;

[0114] The geological zoning of the case open-pit iron mine is as Figure 3 shown, and the acceptable slope angle ranges for each area are shown in Table 3, where the increment step of the change of the azimuth boundary slope angle is taken as 1°.

[0115] Table 3 Acceptable Slope Angle Ranges for the Boundary Slopes in Each Azimuth

[0116]

[0117]

[0118] In the embodiment, taking the 180° azimuth (Area IV) of an open-pit iron mine as an example, a combined scheme of the boundary slope angle is designed. While keeping the boundary slope angles in other azimuths unchanged, with an increment step of 1°, starting from the lower limit of the acceptable slope angle and ending at the upper limit of the acceptable slope angle, a total of 8 combined schemes of the boundary slope angle are designed.

[0119] Step 5: Based on the negative cone exclusion method, calculate the final boundary under each combined condition of the boundary slope angle in each azimuth one by one, and obtain parameters such as the ore quantity, waste rock quantity, average stripping ratio, and boundary occupied area under each final boundary.

[0120] The result parameters of the open-pit iron mine under 8 combined schemes of the boundary slope angle are shown in Table 4.

[0121] Table 4 Optimization results of the final boundary under each slope angle scheme

[0122]

[0123] Step 6: Project each final boundary shape onto the 3D geological model of the mine one by one, and delete the geological bodies inside the final boundary to obtain a sequence of 3D geological models of the mine's final boundary when mined to the final boundary.

[0124] In the case of the open-pit iron mine, this step is completed using 3DMine software.

[0125] Step 7: According to the rock mass zoning, intercept the slope profiles in the sequence of 3D geological models of the final boundary to obtain the 2D slope profiles of each final boundary in each zone. Based on the reliability theory, calculate the slope instability probability of each profile to obtain the partition slope instability probability index of all the final boundary model sequences.

[0126] The slope instability probability of each profile is determined by the Monte Carlo simulation method.

[0127] In the case of the open-pit iron mine, the screenshots of the slope profiles of the above 8 schemes are shown in Figure 4 As shown. In this embodiment, since the slope angles in other azimuths are fixed, only the calculation results of the slope profile instability probabilities of the 8 schemes in the 180° azimuth (Area IV) are given here, as shown in Table 5.

[0128] Table 5 Calculation results of the slope profile instability probabilities of each scheme

[0129]

[0130] Step 8: Calculate the carbon emissions of each final boundary one by one according to the carbon emission calculation model of open-pit mine mining in Step 2 to obtain the carbon emission evaluation index of each boundary.

[0131] The carbon emission results of 8 example schemes of the open-pit iron mine are shown in Table 6.

[0132] Carbon emission results of each scheme in Table 6

[0133]

[0134] Step 9: Determine the acceptable slope instability probability index, find out the final pit results in the sequence of 3D geological models of the final pit where the slope instability probability indices of all partitions are higher than the acceptable slope instability probability index, and obtain the benefit evaluation indices of these final pit results;

[0135] The acceptable slope instability probability index is comprehensively selected according to the mine scale, engineering geology and hydrogeological conditions, etc.;

[0136] The acceptable slope instability probability index for the case of the open-pit iron mine is taken as 0.0062.

[0137] Step 10: Extract the remaining 3D geological models of the final pit in Step 9 as a subsequence, and design slope reinforcement schemes for the partition pits in the final pit of the subsequence where the slope instability probability indices of all partitions are lower than the acceptable slope instability probability index. Calculate the minimum reinforcement workload when the combined instability probability of the reinforced slope exceeds the acceptable slope instability probability index, and obtain the reinforcement workloads of all final pits in the subsequence. At the same time, calculate the benefit evaluation indices of each final pit in the subsequence;

[0138] The slope reinforcement scheme is the cable anchor reinforcement type;

[0139] The minimum reinforcement workload when the combined instability probability of the reinforced slope exceeds the acceptable slope instability probability index is determined according to the steps as shown in Figure 2 the following:

[0140] S1: Determine the distribution range of each cable anchor design parameter according to the slope geometric parameters, and substitute it into the formula P f (F|L,θ,X t ,n) = max{P f (F SS -e ≤ 0), P f (F SO -f ≤ 0)} to calculate the combined instability probability of the reinforced slope under different cable anchor design parameter combinations;

[0141] Where: P f (F|L,θ,X t ,n) is the combined instability probability of the reinforced slope under different cable anchor design parameters; P f (F SS -e ≤ 0) is the probability of anti-slide stability failure; P f (F SO-f ≤ 0) is the probability of anti-overturning stability failure; e and f are the reduction constants of anti-sliding stability and anti-overturning stability respectively; L is the anchorage length of the cable anchor; θ is the angle between the cable anchor and the horizontal plane; X t is the horizontal distance from the cable anchor layout point on the slope surface to the toe of the slope; n is the number of rows of cable anchors.

[0142] The anti-sliding stability of the reinforced slope is calculated according to the formula The anti-overturning stability of the reinforced slope is calculated according to the formula Calculate;

[0143] Among them, c is the cohesion of the slope rock mass (kPa); is the internal friction angle of the slope rock mass (°); A is the bottom area of the sliding surface per unit width (m 2 ); W is the self-weight of the sliding mass (kN); T is the anchoring force of the cable anchor; k h is the horizontal blasting vibration acceleration coefficient; V is the resultant force of the water pressure acting on the tension crack (kN); U is the resultant force of the water pressure acting on the bottom sliding surface (kN); X W is the horizontal distance from the acting point of the gravity of the sliding mass to the toe of the slope (m); X V is the vertical distance from the acting point of the resultant force of the water pressure acting on the tension crack to the toe of the slope (m); X U is the shortest distance from the acting point of the resultant force of the water pressure acting on the bottom sliding surface to the toe of the slope (m); X K is the vertical distance from the acting point of the gravity of the sliding mass to the toe of the slope (m).

[0144] S2: Exclude all combinations with instability probability exceeding the acceptable slope instability probability index;

[0145] S3: Calculate the cable anchor reinforcement workload of the remaining combinations and sort them, and find the combination with the lowest cable anchor reinforcement workload as the minimum reinforcement workload C when the combined instability probability of the reinforced slope exceeds the acceptable slope instability probability index Wmin .

[0146] The minimum reinforcement workload when the 8 example schemes of the case open-pit iron mine reach the acceptable slope instability probability index is shown in Table 7.

[0147] Table 7 The minimum reinforcement workload of each scheme when reaching the acceptable slope instability probability index

[0148]

[0149]

[0150] Step 11: Calculate the comprehensive evaluation index of all final pit sequences, compare all the comprehensive evaluation indexes, and find out the final pit with the largest comprehensive evaluation index value as the optimization result of the open-pit mine boundary considering both mining carbon emissions and slope safety. The comprehensive evaluation index is calculated according to the formula C Z = λ1C S + λ2C Wmin + λ3C P ;

[0151] Where: C Z is the comprehensive evaluation index for the optimization of the pit boundary considering carbon emissions and slope safety; λ1 is the conversion coefficient of the international carbon emission price; λ2 is the conversion coefficient of the slope treatment cost; λ3 is the conversion coefficient of the pit profit; C P is the value of the pit boundary.

[0152] The comprehensive evaluation results of the above 8 schemes of the case open-pit iron mine are as Figure 5 shown. The results show that when not considering the two factors of carbon emissions and slope safety and stability brought by open-pit mining, the comprehensive evaluation index of open-pit mining gradually increases with the steepening of the regional slope angle, and the optimal solution cannot be obtained; the comprehensive evaluation index of open-pit mining obtained by the present invention not only considers the two factors of carbon emissions and slope safety and stability brought by open-pit mining, but also can obtain the optimal pit boundary. Figure 5 The optimal pit boundary result in it is Scheme No. 5. The present invention realizes the simultaneous incorporation of the three optimization objectives of the benefits obtained from open-pit mining, the environmental problems caused by mining, and the slope safety and stability during the mining disturbance process into the pit boundary optimization method, evaluates the optimal pit sequence with a comprehensive evaluation index system, and realizes the generation of random regional or overall slope shapes, solving the problem of mutual conflict between the optimization results of slope geometric shapes and pit boundary optimization results.

[0153] For the technical content not described in the above manner, the existing technology can be adopted or borrowed to achieve it.

[0154] It should be noted that those skilled in the art can also make various easily changed ways under the teaching of this specification, such as equivalent ways or obvious deformation ways. The above changed ways should all be within the protection scope of the present invention.

Claims

1. An open-pit mine boundary optimization method that considers both mining carbon emissions and slope safety, characterized by Use the following steps: Step 1: Establish the mine 3D geological model, ore body model and grade model based on the geological drilling data; Step 2: Determine the vegetation distribution and soil structure around the mining area based on the on-site survey method, and establish a carbon emission calculation model for open-pit mining in combination with the economic and technical parameters of mining; Step 3: Determine the strength index of the mine rock based on on-site point loads and indoor tests, establish the distribution function of each strength index, obtain the distribution of the rock mass structure surface, and determine the rock mass structure type; Step 4: Divide the rock mass within the mining area according to the slope instability mode, determine the acceptable slope angle range of the rock mass in each area, take the lower limit of the acceptable slope angle of each partition as the initial boundary slope angle, change the boundary slope angles of all directions one by one according to the same incremental step, and obtain the orthogonal combination scheme of the boundary slope angle; Step 5: Based on the negative cone elimination method, the final state under the conditions of the slope angle combination of each azimuth state is optimized one by one, and the ore volume, waste rock volume, average stripping ratio and the land area parameters of the state, spoil dump and tailings pond under each final state are obtained; Step 6: Project each final state form one by one into the three-dimensional geological model of the mine, and delete the geological body inside the final state to obtain the three-dimensional geological model sequence of the final state of the mine; Step 7: According to the rock mass zoning, the slope profile is intercepted in the final state three-dimensional geological model sequence to obtain the two-dimensional slope profile of each final state in each partition, and the slope instability probability of each profile is calculated based on the reliability theory to obtain the partition slope instability probability index of all final state model sequences; Step 8: Calculate the carbon emissions of each final state one by one according to the open-pit mining carbon emission calculation model in step 2 to obtain the carbon emission evaluation index of each state; Step 9: Determine the acceptable slope instability probability index, find the final state results in which the sub-area slope instability probability indexes in the final state three-dimensional geological model sequence are all higher than the acceptable slope instability probability index, and obtain the benefit evaluation index of these final state results; Step 10: Extract the remaining final boundary three-dimensional geological model in step 9 as a subsequence, design slope reinforcement schemes for all sub-district boundaries in the final boundary of the subsequence whose slope instability probability index is lower than the acceptable slope instability probability index, calculate the minimum reinforcement workload when the combined instability probability of the slope after reinforcement exceeds the acceptable slope instability probability index, obtain the reinforcement workload of all final boundaries in the subsequence, and at the same time, calculate the benefit evaluation index of each final boundary in the subsequence; Step 11: Calculate the comprehensive evaluation index of all final boundary sequences, compare all comprehensive evaluation indexes, and find the final boundary with the largest comprehensive evaluation index value as the open-pit mine boundary optimization result that considers both mining carbon emissions and slope safety; The comprehensive evaluation index of the final state sequence specifically includes: Using formula C Z =λ1C S +λ2C Wmin +λ3C P Determine the comprehensive evaluation index of the final realm sequence; Where: C Z is a comprehensive evaluation index for optimizing the boundary between carbon emissions and slope safety; λ1 is the international carbon emission price conversion coefficient; C S is the carbon emission of open-pit mining (t); λ2 is the slope management cost conversion coefficient; C Wmin is the minimum reinforcement workload (m) when the probability of combined slope instability after reinforcement exceeds the acceptable slope instability probability index; λ3 is the boundary profit conversion coefficient; C P For the value of the realm.

2. The open-pit mine boundary optimization method according to claim 1, wherein: The open-pit mining carbon emission calculation model specifically includes: Using formula C S =C D +C I Determining carbon emissions from open pit mining; Where: C S is the carbon emission from open-pit mining (t), C D is the direct carbon emission from open-pit mining (t), C I is the indirect carbon emissions from open-pit mining (t); Using formula C D =C DE +C DO +C DB Determine direct carbon emissions from open pit mining; Where: C DE Carbon emissions from electricity consumption for open-pit mining (t), C DO is the carbon emissions generated by open-pit mining consuming fossil energy (t), C DB is the carbon emission caused by explosive explosion in open-pit mining (t); Using formula C DE =[Q(e W1 +e W2 )+Q1e W3 +ae W4 ]η e Determine the carbon emissions from electricity consumption in open pit mining; Where: Q is the total stripping volume at the final state (t); Q1 is the total ore volume at the final state (t); a is the mining life at the final state (years); e W1 is the average electric energy consumed per unit stripping volume (kW·h / t); e W2 The average electrical energy consumed to process a unit amount of rock or ore (kW·h / t); e W3 The average electric energy consumed for processing a unit of ore; W4 is the annual average total power consumption of mining ancillary facilities and other equipment (kW·h / year), η e is the carbon emissions per unit of electricity consumption (t / (kW·h)); Using formula C DO =Q[(d W1 +d W3 )η d1 +(d W2 +d W4 )η d2 ] Determine the carbon emissions from open-pit mining consuming fossil energy; Where: d W1 is the average gasoline consumption per unit stripping volume (t / t); d W2 is the average diesel consumption per unit stripping volume (t / t); d W3 The average gasoline consumption for processing a unit amount of rock or ore (t / t); d W4 The average diesel consumption for processing a unit amount of rock or ore (t / t); η d1 is the carbon emission per unit gasoline consumption (t / t); η d2 is the carbon emission per unit diesel consumption (t / t); Using the formula Determine carbon emissions from explosive blasts in open pit mining; Where: b w The unit consumption of explosives for mine and rock blasting (t / m 3 );η b is the carbon emission factor of explosives (t / t); γ is the average bulk density of ore and rock within the boundary (t / m 3 ); Using formula C I =C IF +C IR +C IT +C IS Determine indirect carbon emissions from open pit mining; Where: C IF is the reduction in carbon sequestration caused by land destruction in open pit mining (t); C IR is the reduction in carbon sequestration caused by land damage in the dump (t); C IT is the reduction in carbon fixation caused by the damaged soil in the tailings pond (t); C IS Carbon emissions generated during the production of raw materials for the construction of ancillary facilities in open-pit mines (t); Using the formula Determine the reduction in carbon sequestration caused by land destruction from open pit mining; Among them: A Fi is the cumulative land damage area of ​​the mining site in year i (km 2 );p i is the proportion of damaged forest land in the land damaged area of ​​the mining site in the i-th year (%); q i is the proportion of damaged grassland area to the damaged land area in the mining site in the i-th year (%); y npp is the net primary productivity of forest land (t / km 2 ·Year); is the CO2 fixation coefficient of forest land; h s is the average soil thickness of damaged grassland (m); γ s is the average soil bulk density of damaged grassland (t / m 3 );r so is the soil organic matter content (%); r oc is the carbon content ratio in soil organic matter (%), ζ is the conversion coefficient of carbon to CO2, which is 3.6667; Using the formula Determine the reduction in carbon sequestration caused by land destruction at dump sites; Where: R i is the total amount of waste rock discharged in year i (t); k w is the expansion coefficient of waste rock after the dump is settled and stabilized; γ w is the average bulk density of waste rock (t / m 3 );H D is the average dumping height of the spoil dump (m), f D is the shape coefficient of the dump; Using the formula Determine the reduction in carbon sequestration due to soil damage from tailings ponds; Where: Q2 is the total amount of ore mined within the boundary (t); g o is the average grade of the selected ore (%); g p is the average grade of concentrate (%); r p is the metal recovery rate of ore dressing (%); γ T is the average bulk density of tailings after accumulation (t / m 3 );H T is the average depth of the tailings pond (m), p i ′ is the proportion of damaged forest land in the damaged land area of ​​the tailings pond (%); q′ is the proportion of damaged grassland in the damaged land area of ​​the tailings pond (%); Using formula C IS =V c c CO2 +V b b CO2 Determine the carbon emissions generated during the production of raw materials for the construction of open-pit mine ancillary facilities; Where: V c is the total amount of concrete used in the construction of open-pit mine ancillary facilities (m 3 );V b The total amount of steel used in the construction of open-pit mine ancillary facilities (m 3 );c CO2 The carbon emissions during the production of raw materials required to produce a unit volume of concrete (t / m 3 );b CO2 The carbon emissions during the production of raw materials required to produce a unit volume of concrete (t / m 3 ).

3. The open-pit mine boundary optimization method according to claim 1, wherein: The combined instability probability of the slope after reinforcement specifically includes: Using the formula P f (F|L,θ,X t ,n)=max{P f (F SS -e≤0),P f (F SO -f≤0)} to determine the probability of joint instability of the slope after reinforcement; Where: P f (F|L,θ,X t , n) is the joint instability probability of the reinforced slope under different anchor cable design parameters; P f (F SS -e≤0) is the failure probability of anti-sliding stability; P f (F SO -f≤0) is the failure probability of anti-overturning stability; e and f are the reduction constants of anti-sliding stability and anti-overturning stability respectively; L is the length of the anchoring section of the anchor cable; θ is the angle between the anchor cable and the horizontal plane; X t is the horizontal distance from the point where the anchor cable is laid on the slope to the foot of the slope; n is the number of rows of anchor cables.

4. The open-pit mine boundary optimization method according to claim 1, wherein: The minimum reinforcement workload when the combined instability probability of the reinforced slope exceeds the acceptable slope instability probability index is determined according to the following steps: S1: Determine the distribution range of each anchor cable design parameter according to the slope geometric parameters, substitute it into the calculation formula of the joint instability probability of the reinforced slope in the form of uniform distribution, and calculate the joint instability probability of the reinforced slope under different combinations of anchor cable design parameters; S2: Eliminate all combinations where the probability of instability exceeds the acceptable slope instability probability index; S3: Calculate the anchor reinforcement workload of the remaining combinations and sort them, and find the combination with the lowest anchor reinforcement workload as the minimum reinforcement workload C when the probability of slope joint instability after reinforcement exceeds the acceptable slope instability probability index Wmin .

5. The open-pit mine boundary optimization method considering both mining carbon emissions and slope safety according to claim 1 is characterized in that: The economic and technical parameters of mining include final slope angle, stripping ratio, cut-off grade, mining and stripping cost, beneficiation cost, concentrate price, concentrate grade and comprehensive recovery rate; The upper and lower limits of the acceptable slope angle range of the rock mass in the region are the slope angles corresponding to the limit state and the safe state of the overall safety and stability of the slope under the condition of the maximum slope height in the region; The maximum slope height of the area is the vertical distance between the bottom of the maximum buried ore body in the area and the ground surface; The acceptable slope instability probability index is selected comprehensively according to the mine scale, engineering geology and hydrogeological conditions; The probability of slope instability of each section is determined by Monte Carlo simulation method; The slope reinforcement scheme is an anchor cable reinforcement type.

6. The open-pit mine boundary optimization method considering both mining carbon emissions and slope safety according to claim 3 is characterized in that: The anti-sliding stability and anti-overturning stability of the reinforced slope specifically include: Using the formula Determine the anti-sliding stability of the reinforced slope; use the formula Determine the anti-overturning stability of the reinforced slope; Where: c is the cohesion of the slope rock mass (kPa); is the internal friction angle of the slope rock mass (°); A is the bottom area of ​​the sliding surface per unit width (m 2 ); W is the weight of the sliding body (kN); T is the anchoring force of the anchor cable; k h is the horizontal blasting vibration acceleration coefficient; V is the resultant force of water pressure acting on the tension crack (kN); U is the resultant force of water pressure acting on the bottom sliding surface (kN); X W is the horizontal distance from the point where the gravity force of the sliding block acts to the foot of the slope (m); V is the vertical distance from the point of action of the resultant water pressure on the tension crack to the slope foot (m); X U is the shortest distance from the point of action of the resultant water pressure on the bottom sliding surface to the slope foot (m); K It is the vertical distance from the point where the gravity force of the sliding block acts to the foot of the slope (m).

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