Calculation method of critical injection strength for in-situ leaching of long bare-foot rare earth mines

Abstract

The present invention discloses a method for calculating the critical injection strength of in-situ leaching of a long-shaped barefoot rare earth mine, comprising: S1, conducting engineering geological exploration of production blocks, obtaining topographic and geological data of the production blocks, and drawing a typical geological profile; S2, designing the injection process of the production blocks on the typical geological profile, determining the topographic conditions according to the topographic and geological data, and determining the injection conditions according to the injection process design data; S3, calculating the injection infiltration line of the production blocks, and obtaining the equation of the stable injection infiltration line of the production blocks; S4, obtaining the injection infiltration line on the typical section of the production blocks according to the equation of the stable injection infiltration line of the production blocks; S5, calculating the safety factor of the mine slope, the critical injection strength of the blocks, and the critical injection water level of the blocks according to the typical geological profile and the injection infiltration line. The present invention realizes the accurate calculation of the critical injection strength of in-situ leaching of long-shaped barefoot rare earth mines.

Description

Technical Field

[0001] The invention relates to the field of rare earth mining, and in particular to a method for calculating the critical injection strength of in-situ leaching of an elongated barefoot rare earth mine. Background Art

[0002] Ion-absorption rare earth ore (abbreviated as ionic rare earth ore) is a new type of exogenous rare earth deposit found in southern my country. Its uniqueness lies in that rare earth elements are mainly adsorbed on clay, mica and other minerals in the weathering crust in an ionic state. It has the characteristics of complete rare earth distribution, low radioactivity, easy mining and rich in high-value medium and heavy rare earth elements. According to the exposed bedrock of the mine, ionic rare earth mines can be divided into two types: bare foot type (bedrock exposed at the foot of the mountain) and full cover type (bedrock covered by the full weathering layer). According to the terrain conditions, bare foot rare earth mines can be divided into two types: long strip and round.

[0003] The in-situ leaching process is an ionic rare earth mining process currently being promoted. This process mainly uses a 1% to 4% low-concentration ammonium sulfate solution as a leaching agent, which is injected into the ore body through a liquid injection hole network, and the rare earth mother liquor is recovered through a liquid collection project, and the rare earth mother liquor is sent to a ground factory for impurity removal, precipitation, extraction, and processing to achieve the purpose of recovering rare earth resources. The in-situ leaching process has the advantages of not destroying the vegetation on the surface of the ore body and not excavating the topsoil and ore, but there are also some problems that need to be solved urgently, such as: the determination of the injection intensity mainly depends on engineering experience. For barefoot rare earth mines, a low injection intensity will cause insufficient leaching. Many mines can still mine rare earths after multiple re-injections; a high injection intensity will cause the mine's infiltration surface to be too high, which is easy to induce geological disasters such as landslides. Summary of the invention

[0004] The purpose of the present invention is to provide a method for calculating the critical injection strength of in-situ leaching of an elongated barefoot rare earth mine, so as to achieve accurate calculation of the critical injection strength of in-situ leaching of an elongated barefoot rare earth mine.

[0005] In order to solve the above technical problems, the present invention provides a technical solution: a method for calculating the critical injection strength of in-situ leaching of long-shaped bare-foot rare earth mines, comprising the following steps:

[0006] S1. Conduct engineering geological exploration of production blocks, obtain topographic and geological data of production blocks, and draw typical geological profiles;

[0007] S2. Design the injection process of the production block on a typical geological profile, determine the topographic conditions based on the topographic geological data, and determine the injection conditions based on the injection process design data;

[0008] S3, calculating the infiltration line of the production block injection liquid, and obtaining the equation of the stable infiltration line of the production block injection liquid;

[0009] S4. According to the stable infiltration line equation of the production block, the input quantity takes a series of values ​​at intervals of k to obtain the infiltration line heights corresponding to different input quantities, and the calculation results are marked on the typical geological profile in the form of coordinates to form a series of scattered points, and these scattered points are connected into a smooth curve, which is the injection infiltration line on the typical profile of the production block;

[0010] S5. According to the typical geological profile and injection infiltration line, the safety factor of the mine slope, the critical injection strength of the ore block and the critical injection water level of the ore block are calculated; the larger the injection range and the injection intensity, the higher the profile infiltration line and the smaller the calculated value of the safety factor.

[0011] According to the above scheme, the topographic geological data described in S1 include: the distribution of topsoil, mineral layer, fully weathered layer, moderately weathered layer and bedrock, the basic physical parameters of topsoil, mineral layer, fully weathered layer, moderately weathered layer and bedrock, and the natural density, natural water content, porosity, particle grading, cohesion, internal friction angle and saturated permeability coefficient of each geological layer.

[0012] According to the above scheme, the terrain conditions described in S2 include: the watershed position A, the horizontal distance L3 from the watershed to the collection ditch, the slope α, and the bedrock bottom slope β.

[0013] According to the above scheme, the injection conditions in S2 include: injection area range L1, injection intensity W, and relative injection intensity λ.

[0014] According to the above scheme, the relative injection intensity λ is obtained by the following formula:

[0015] λ=W / K s

[0016] Among them, K s is the saturated permeability coefficient, in m / d.

[0017] According to the above scheme, the equation of the stable infiltration line of injection is:

[0018]

[0019] Among them, α is the slope gradient, β is the bedrock slope, λ is the relative injection intensity, L1 is the injection area range, L3 is the horizontal distance from the watershed to the collection ditch, H is the height of the infiltration line at any coordinate x, H0 is the height of the infiltration line at x = 0, H1 is the height of the infiltration line at x = L1, and H2 is the height of the infiltration line at x = L2; f1 and f2 are auxiliary functions, specifically:

[0020] f1=tan(β)·(2L3-L1-L2)

[0021] f2=tan(β)·(2L3-L1)

[0022] L2 is the horizontal distance from the watershed to the seepage point on the slope.

[0023] According to the above scheme, Excel is used as a drawing and calculation tool in S4.

[0024] According to the above scheme, k=1m.

[0025] According to the above scheme, S5 specifically adopts the limit equilibrium method: by adjusting the injection range and injection intensity until the calculated value of the safety factor is equal to the allowable value of the safety factor, the injection intensity obtained at this time is the critical injection intensity of the ore block, and the infiltration line is the critical injection water level of the ore block.

[0026] The beneficial effects of the present invention are as follows: the present invention solves the critical infiltration line equation according to geological conditions, injection conditions and the allowable value of the safety factor. Compared with the traditional method of setting the injection intensity according to engineering experience, the present invention has the advantage of being more accurate, and the method is simple to implement and easy to use. It has a good engineering guiding role in the layout of in-situ leaching injection engineering, injection intensity and slope landslide control in barefoot mines. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A typical cross-sectional view of a long, barefoot mine according to an embodiment of the present invention;

[0028] Figure 2 This is a typical cross-sectional view of a long strip barefoot mine in Longnan according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0030] In this embodiment, a strip-shaped barefoot ionic rare earth mine in Longnan is taken as an example, and the specific implementation process is as follows:

[0031] S1. Carry out engineering geological exploration of production blocks to obtain topographic geological data of production blocks: distribution of topsoil, ore layer, fully weathered layer, medium weathered layer and bedrock, basic physical parameters of topsoil, ore layer, fully weathered layer, medium weathered layer and bedrock, as well as natural density, natural water content, porosity, particle grading, cohesion, internal friction angle, saturated permeability coefficient of each geological layer, and draw typical geological profiles, see Figure 1 ; Among them, the stratification of each soil layer is not obvious enough, and the saturated permeability coefficient K of the soil above the bedrock is determined comprehensivelys =1.6m / d.

[0032] S2. Design the production block injection process on a typical geological profile. Determine the terrain conditions based on the topographic geological data: the watershed position (coordinate x = 47.3m), the horizontal distance L3 (unit: m) from the left and right slope watershed to the liquid collection ditch, the left and right slope side slopes α (unit: °), the left and right slope bedrock floor slopes β (unit: °), and determine the injection conditions based on the injection process design data: the left and right slope injection area range L1 (unit: m), the left and right slope injection intensity W (unit: m / d), and calculate the relative injection intensity λ using the following formula:

[0033] λ=W / K s

[0034] W is the injection strength, m / d; K s is the saturated permeability coefficient, m / d;

[0035] The section calculation conditions are shown in the following table:

[0036]

[0037] S3, calculate the production block injection infiltration line, and obtain the production block injection stable infiltration line equation, which is specifically:

[0038]

[0039] Among them, α is the slope gradient, in degrees; β is the bedrock slope, in degrees; λ is the relative injection intensity; L1 is the injection area range, in meters; L3 is the horizontal distance from the watershed to the sump, in meters; H is the height of the infiltration line at any coordinate x, in meters; H0 is the height of the infiltration line at x = 0, in meters; H1 is the height of the infiltration line at x = L1, in meters; H2 is the height of the infiltration line at x = L2, in meters; f1 and f2 are auxiliary functions, specifically:

[0040] f1=tan(β)·(2L3-L1-L2)

[0041] f2=tan(β)·(2L3-L1)

[0042] Among them, r2 is the horizontal distance from the watershed to the slope seepage point B, in meters;

[0043] S4. According to the stable infiltration line equation of the production block, use the Excel calculation tool to input a series of values ​​at intervals of 1m to obtain the infiltration line height corresponding to different input values. Mark the calculation results in the form of coordinates on the typical geological profile to form a series of scattered points, and connect these scattered points into a smooth curve, which is the injection infiltration line on the typical profile of the production block. The results are plotted in the following table. Figure 2 ;

[0044] S5. According to the typical geological profile and the injection infiltration line, the safety factor of the mine slope, the critical injection strength of the ore block and the critical injection water level of the ore block are calculated; the larger the injection range and the injection strength, the higher the profile infiltration line and the smaller the calculated value of the safety factor; by adjusting the injection range and the injection strength until the calculated value of the safety factor is equal to the allowable value of the safety factor, the injection strength obtained at this time is the critical injection strength of the ore block, and the infiltration line is the critical injection water level of the ore block; according to the calculation, the safety factors of the left and right slopes are 1.19 and 1.23 respectively, which are close to the allowable safety factor of 1.20, it can be considered that the injection strength of the ore block has reached the designed critical injection strength.

[0045] In order to verify the effectiveness of the critical injection strength calculation method for in-situ leaching of long-shaped barefoot rare earth mines, real-time monitoring of groundwater level and landslide monitoring were carried out during the in-situ leaching mining process of the test block. A total of 7 groundwater level observation wells 1# to 7# were arranged along the profile, and the locations of the observation wells and the water level observation results were plotted together on Figure 2 As can be seen from the figure, the water level of each observation hole is relatively close to the calculated value of the infiltration line, with an error between -3.3% and -12.1%, which meets the engineering requirements; and during the production process, the slope has been in a stable state.

[0046] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for calculating the critical injection strength of in-situ leaching in a long barefoot rare earth mine, characterized by: The following steps are involved: S1. Conduct engineering geological exploration of production blocks, obtain topographic and geological data of production blocks, and draw typical geological profiles; S2. Design the injection process of the production block on a typical geological profile, determine the topographic conditions based on the topographic geological data, and determine the injection conditions based on the injection process design data; S3, calculating the infiltration line of the production block injection liquid, and obtaining the equation of the stable infiltration line of the production block injection liquid; S4. According to the stable infiltration line equation of the production block, the input quantity takes a series of values ​​at intervals of k to obtain the infiltration line heights corresponding to different input quantities, and the calculation results are marked on the typical geological profile in the form of coordinates to form a series of scattered points, and these scattered points are connected into a smooth curve, which is the injection infiltration line on the typical profile of the production block; S5. According to the typical geological profile and the injection infiltration line, the safety factor of the mine slope, the critical injection strength of the ore block and the critical injection water level of the ore block are calculated; the larger the injection range and the injection strength, the higher the profile infiltration line and the smaller the calculated value of the safety factor; The equation of the stable infiltration line of injection is: Among them, α is the slope of the slope, β is the slope of the bedrock floor, λ is the relative injection intensity, L1 is the range of the injection area, L3 is the horizontal distance from the watershed to the collection ditch, H is the height of the infiltration line at any coordinate x, H0 is the height of the infiltration line at x = 0, H1 is the height of the infiltration line at x = L1, and H2 is the height of the infiltration line at x = L2; f1 and f2 are auxiliary functions, specifically: f1=tan(β)·(2L3-L1-L2) f2=tan(β)·(2L3-L1) L2 is the horizontal distance from the watershed to the seepage point on the slope; The relative injection intensity λ is obtained by the following formula: λ=W / K s Among them, K s is the saturated permeability coefficient, in m / d, and W is the injection intensity.

2. The method for calculating the critical injection strength of in-situ leaching of an elongated barefoot rare earth mine according to claim 1, characterized in that: The topographic and geological data described in S1 include: the distribution of topsoil, mineral layers, fully weathered layers, moderately weathered layers and bedrock, the basic physical parameters of topsoil, mineral layers, fully weathered layers, moderately weathered layers and bedrock, and the natural density, natural water content, porosity, particle grading, cohesion, internal friction angle and saturated permeability coefficient of each geological layer.

3. The method for calculating the critical injection strength of in-situ leaching of an elongated barefoot rare earth mine according to claim 1, characterized in that: The terrain conditions described in S2 include: the watershed position A, the horizontal distance L3 from the watershed to the collection ditch, the slope α, and the bedrock bottom slope β.

4. The method for calculating the critical injection strength of in-situ leaching of an elongated barefoot rare earth mine according to claim 1, characterized in that: The injection conditions in S2 include: injection area range L1, injection intensity W, and relative injection intensity λ.

5. The method for calculating the critical injection strength of in-situ leaching of long-shaped bare-foot rare earth mines according to claim 1 is characterized in that: Excel is used as a drawing and calculation tool in S4.

6. The method for calculating the critical injection strength of in-situ leaching of an elongated barefoot rare earth mine according to claim 1, characterized in that: k=1m.

7. The method for calculating the critical injection strength of in-situ leaching of an elongated barefoot rare earth mine according to claim 1, characterized in that: S5 specifically adopts the limit equilibrium method: by adjusting the injection range and injection intensity until the calculated value of the safety factor is equal to the allowable value of the safety factor, the injection intensity obtained at this time is the critical injection intensity of the ore block, and the infiltration line is the critical injection water level of the ore block.

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