Method for establishing deep-sea mining plume rheological model considering physical property change

Abstract

The invention provides a method for establishing a deep-sea mining plume rheological model considering physical property changes. The method comprises the following steps: establishing a deep-sea mining plume rheological database under different rheological models; analyzing and comparing the rheological parameter difference of the deep-sea mining plume under different rheological models; and constructing a deep-sea mining plume rheological model considering the physical property change, and constructing a relationship between the rheological parameters and the density. According to the technical scheme of the invention, the model uses the artificial sample kaolin plume with relatively stable properties to represent the mine sediment plume, and overcomes the defects of lack of mine sediment rheological test data and great rheological property difference of deep-sea sediments in various regions at present. The model provides an important reference for the change rule of the rheological property of the sediment in the mining area along with the density, and a deep-sea mining sediment plume rheological model under the full-life evolution period can be constructed on the basis of the important reference.

Description

Technical Field

[0001] The present invention relates to the technical field of deep sea mining, and in particular to a method for establishing a rheological model of a deep sea mining plume taking into account changes in physical properties. Background Art

[0002] Rheological model refers to the model that describes the change law of rheological parameters of fluid (such as apparent viscosity and yield strength) with increasing shear rate. Rheological model is used in the simulation of the propagation range of sediment plume in deep-sea mining.

[0003] Deep-sea mining will cause serious environmental pollution, including plumes, which is one of the important factors restricting the commercial exploitation of deep-sea minerals. The plumes caused by deep-sea mining activities come from two aspects: the plumes caused by mining vehicles during the ore collection process, and the tailings plumes formed by the treated tailings discharged into the seawater. The tailings plumes have a higher discharge concentration and speed, so they propagate farther and stay longer in the seawater. At present, the most favorable means to predict the propagation range of deep-sea mining plumes is numerical simulation. Since the rheological properties of the plume (such as viscosity) have an important influence on its propagation range, the accuracy of numerical simulation depends on the description of the rheological properties of the plume. During the entire life cycle of deep-sea mining plumes from release to distant propagation, due to the flocculation and sedimentation of sediments and the dilution of the plume by environmental fluids, its physical properties such as density will change significantly and cause the rheological properties of the plume to change accordingly. However, current studies regard plumes at different stages as Newtonian fluids, and rarely consider the changes in the rheological parameters of the plume as it evolves, which will have an important impact on the prediction of the plume. In order to describe the rheological properties of plumes, some scholars have conducted a large number of rheological tests using deep-sea sediment samples. Among them, the power law model, Bingham model and Herschel-Bulkley model have shown good applicability in describing the rheological properties of sediment plumes with a certain density. However, these rheological models only consider the effect of shear rate changes on rheological parameters, and do not consider changes in physical parameters represented by density. This may cause large errors in the results of the simulation range of deep-sea mining plume propagation. Summary of the invention

[0004] In order to more realistically describe the changes in rheological properties experienced by deep-sea mining plumes during propagation, it is necessary to improve the existing typical rheological models, such as the power law model, the Bingham model, and the Herschel-Bulkley model. Specifically, it is necessary to quantify the impact of changes in the physical parameters of the plume represented by density on its rheological parameters, and couple it with the typical rheological model to finally construct a deep-sea mining plume rheological model that takes into account changes in plume density. In order to make up for the deficiencies of the prior art, the present invention provides a method for establishing a deep-sea mining plume rheological model that takes into account changes in physical properties.

[0005] The present invention is implemented by the following technical solution: a method for establishing a rheological model of deep-sea mining plume taking into account changes in physical properties, characterized in that it specifically includes the following steps: Step S1, establishing a deep-sea mining plume rheology database under different rheological models, specifically comprising the following steps: Step S1-1, determining a rheological model describing a deep-sea mining plume with a certain density, including a typical non-Newtonian fluid rheological model such as a power law model, a Bingham model, and a Herschel-Bulkley model; Step S1-2, according to the physical property changes experienced by the deep-sea mining plume during its evolution as required, determine the physical property parameter representing the entire evolution process, and define the range of change of the parameter during the sediment evolution process; Step S1-3, establishing a database of rheological parameters of deep-sea mining plumes, and establishing a database of rheological property parameters of deep-sea mining plumes varying with density under different rheological models according to different rheological models describing the deep-sea mining plumes; Step S2, analyzing and comparing the differences in rheological parameters of deep-sea mining plumes under different rheological models, specifically includes the following steps: Step S2-1, data difference visualization analysis: dividing the full range of physical parameter changes of deep-sea mining plumes, and then evaluating the distribution range of rheological parameters within a smaller range of physical parameter changes by drawing box plots; Step S2-2, quantitative analysis of data differences; calculation of 0.5 g / cm 3 The range of rheological parameters within the range of physical parameter changes, and the average value of the range in the full range of physical parameter changes of deep-sea mining plumes, the ratio of the maximum value of the range to the average value, and the density range where the maximum value is located are counted; based on the visual analysis of data differences, the range of rheological test data of rheological parameters in each single density interval with a density gradient of 0.05 g / cm3 is calculated, and quantitative analysis of data differences is carried out; the range of data in a certain interval is the difference between the maximum and minimum values ​​of the data in the interval, which indicates the size of the data distribution range in this interval; Step S2-3, selecting a rheological model that describes the rheological characteristics of deep-sea mining sediment plumes; comprehensively considering the data difference visualization analysis and quantitative analysis results, selecting a rheological model with the smallest data difference, and constructing a deep-sea mining plume rheological model that considers changes in physical properties based on the model; Step S3, constructing a deep-sea mining plume rheological model taking into account the change of physical properties to construct the relationship between rheological parameters and density, specifically including the following steps: Step S3-1, constructing the quantitative relationship between rheological parameters and physical parameters; the relevant parameters of environmental water include ρ =1g / cm 3 ;K =0.001Pa·s; n =1 into the fitting database and ensure that the relevant parameters of water are consistent with the fitting results. ρ and K and n All of them show the relationship of power exponential function of three parameters; Step S3-2, constructing a rheological model of deep-sea mining plumes that takes into account changes in physical properties; determining the variation of rheological parameters with physical parameters by means of data fitting. By means of data fitting, it can be determined that there is a mathematical relationship of a three-parameter power function between the rheological parameters and density of the deep-sea mining plumes. By coupling it with the power law model, a rheological model of kaolin plumes that takes into account changes in density can be obtained. The specific coupling method is as follows: Formula (1) and formula (2) are rheological parameters K and n The relationship between density and density is expressed in formula (3). Substituting formula (1) and formula (2) into formula (3), a rheological model of deep-sea mining plume considering the change of plume density can be constructed, as shown in formula (4).

[0006] As a preferred solution, the density range of the deep-sea mining plume determined in step S1-2 does not exceed 1.50 g / cm3.

[0007] As a preferred solution, the box plot in step S2-1 shows the rheological test data under the density change and density gradient of 0.05 g / cm 3 The maximum value, minimum value, median, and upper and lower quartiles within the interval are used to describe the distribution range and dispersion of the data within the interval.

[0008] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art: the model uses a relatively stable artificial sample kaolin plume to represent the sediment plume in the mining area, overcoming the current lack of test data on the rheological properties of mining area sediments and the great differences in the rheological properties of deep-sea sediments in various regions. The model provides an important reference for the law of change of rheological properties of mining area sediments with density, and can be used as a basis to construct a rheological model of deep-sea mining sediment plumes under the full life cycle evolution cycle.

[0009] Additional aspects and advantages of the present invention will become apparent in the following description or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1The rheological database diagram of kaolin plume, where (a) is the relationship between K and density under the power law model, (b) is the relationship between n and density under the power law model, (c) is the relationship between τy and density under the Bingham model, (d) is the relationship between K and density under the Bingham model, (e) is the relationship between K and density under the HB model, (f) is the relationship between τy and density under the HB model, and (g) is the relationship between n and density under the HB model; Figure 2 The difference visualization diagram of kaolin plume rheological test data; (a) is the difference visualization of K under the power law model, (b) is the difference visualization of n under the power law model, (c) is the difference visualization of τy under the Bingham model, (d) is the difference visualization of K under the Bingham model, (e) is the difference visualization of K under the HB model, (f) is the difference visualization of τy under the HB model, and (g) is the difference visualization of n under the HB model; Figure 3 Figure 2 shows the relationship between rheological parameters and density of kaolin plume, where (a) is the relationship between K and density, and (b) is the relationship between n and density. DETAILED DESCRIPTION

[0011] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0012] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0013] Combine the following Figures 1 to 3 The method for establishing a rheological model of a deep-sea mining plume taking into account changes in physical properties according to an embodiment of the present invention is specifically described.

[0014] The present invention proposes a method for establishing a rheological model of a deep-sea mining plume taking into account changes in physical properties, which specifically includes the following steps: Step S1, establishing a deep-sea mining plume rheology database under different rheological models, specifically comprising the following steps: Step S1-1, determine the rheological model that describes the deep-sea mining plume of a certain density, including typical non-Newtonian fluid rheological models such as the power law model, Bingham model, and Herschel-Bulkley model. Non-Newtonian fluid refers to a fluid that does not satisfy Newton's law of internal friction. Time-independent non-Newtonian fluid is a common type of non-Newtonian fluid. Its shear stress is only related to the shear rate, and its apparent viscosity is expressed by the ratio of shear stress to shear rate. Non-Newtonian fluid models widely used to describe the changes in the mechanical properties of deep-sea sediment flows include the power law model, Bingham model, and Herschel-Bulkley model. The sediment plume caused by seabed mining is a type of seabed sediment flow, so it can also be described by the above three models.

[0015] Step S1-2: According to the physical property changes experienced by the deep-sea mining plume during its evolution, determine the physical property parameters representing the entire evolution process, and define the range of changes of the parameters during the sediment evolution process; currently, the monitored mining plume density is relatively low, not exceeding 1.01 g / cm 3 , but the maximum amount of sediment that can be resuspended due to deep-sea mining activities depends on the saturation density and water content of the seafloor sediments, which in turn affects the density of the seafloor sediment plume. For example, the saturation density of seafloor sediments in the polymetallic nodule deposit area of ​​the Peruvian Basin is between 1.10 and 1.27 g / cm 3 Therefore, the density at the head of the mining vehicle plume may exceed the density that has been monitored. In addition, during the process of tailings being transported from the surface mother ship to the seawater via a pipeline, the volume concentration of the sediment flow in the pipeline does not exceed 30%, that is, the density of the seabed sediment is 2.63 ~2.65 g / cm 3 The density of nodule debris is about 2.00 g / cm 3 Under the condition of 3 It is inferred that the density of the tailings plume discharged into the mid-water area through pipelines can reach nearly 1500 kg / m 3 Taking into account the maximum density that can be achieved by the mining vehicle plume and the tailings plume, it is finally determined that the density range of the deep-sea mining plume does not exceed 1.50 g / cm 3 .

[0016] Step S1-3, establish a database of rheological parameters of deep-sea mining plumes. According to the different rheological models describing deep-sea mining plumes, establish a database of the changes in rheological parameters of deep-sea mining plumes with density under different rheological models; therefore, at laboratory temperature (20 ~ 25℃), the rheological test data of kaolin plumes with a density not exceeding 1.50 g / cm³ were screened. Then, the data were classified according to the different rheological models applied, and the relationship between the density and rheological parameters of kaolin plumes under different models was analyzed, such as Figure 1 shown.

[0017] Step S2, analyzing and comparing the differences in rheological parameters of deep-sea mining plumes under different rheological models, specifically includes the following steps: Step S2-1, data difference visualization analysis; divide the full range of physical parameter changes of deep-sea mining plumes, and then evaluate the distribution range of rheological parameters within a smaller range of physical parameter changes by drawing box plots; data differences are visualized by drawing box plots, which are statistical graphs that describe data distribution. The box plot shows the maximum, minimum, median, and upper and lower quartiles of the rheological test data in the density change range of 0.05 g / cm3, thereby describing the distribution range and dispersion of the data within this range, such as Figure 2 As shown in (b); Figure 2 The visualization results of the difference in rheological test data under different models are shown in Figure 1. Specifically, the larger the distribution range of rheological parameters and the higher the degree of dispersion in this interval, the greater the difference in rheological test data, and the interval with the largest data difference is marked with blue shadows. The gray line is the line connecting the medians of different intervals, which directly reflects the changes in rheological parameters in the density range of 1.0 ~1.5g / cm3.

[0018] Step S2-2, quantitative analysis of data differences; calculation of 0.5 g / cm 3 The range of rheological parameters within the density variation range is calculated, and the average value of the range, the ratio of the maximum value of the range to the average value within the full range of physical parameter changes of deep-sea mining plumes are calculated, and the density range where the maximum value is located is counted; based on the visual analysis of data differences, the rheological parameters are calculated when the density gradient is 0.05 g / cm 3 The range of the rheological test data in each single density range is used to carry out quantitative analysis of data differences; the range of data in a certain range is the difference between the maximum and minimum values ​​of the data in the range, indicating the size of the data distribution range in this range; Table 1 shows the results of quantitative analysis of data differences, including the full density range (1.0 ~ 1.5 g / cm 3 ), the ratio of the maximum value of the range to the average value, and the range of the maximum value of the range. Among them, the average value of the range reflects the overall level of data differences in the full density variation range of the rheological parameters.

[0019] Table 1 Quantitative analysis of the differences in rheological parameters under different rheological models Step S2-3, selection of rheological model describing the rheological characteristics of deep-sea mining sediment plume; comprehensive consideration of data difference visualization analysis and quantitative analysis results, selection of rheological model with the smallest data difference, and construction of deep-sea mining plume rheological model considering the change of physical properties based on this model; quantitative results show that K The data difference under the power law model is the smallest, with the ratio of the maximum range to the average value being 240.76%. The difference under the Herschel-Bulkley model is the largest, with the ratio of the maximum range to the minimum being as high as 426.27%. τ y The data differences under the Bingham model are smaller than those under the Herschel-Bulkely model, while n Although the quantitative results of the data differences under the power law model and the Herschel-Bulkely model are not much different, the data difference visualization results show that the power law n The data distribution is more concentrated and the data difference is smaller. Therefore, considering the visualization and quantitative results of the data difference, the data difference of the rheological test data under the power law model is the smallest.

[0020] Step S3, constructing a deep-sea mining plume rheological model taking into account the change of physical properties to construct the relationship between rheological parameters and density, specifically including the following steps: Step S3-1, construct the quantitative relationship between rheological parameters and physical parameters; in the process of plume propagation from release to distant places, due to the flocculation and sedimentation of sediments and the dilution of the plume by the environmental fluid, the density of the plume gradually decreases and eventually becomes close to the density of the ambient water. Therefore, in order to simulate the evolution of the rheological properties of the plume over the entire life cycle, the relevant parameters of the ambient water ( ρ =1g / cm 3 ; K =0.001Pa·s; n =1) into the fitting database and ensure that the relevant parameters of water are consistent with the fitting results. Figure 3 The data fitting results of density and rheological parameters under power law are shown. Here, ρ and K and n All of them show the relationship of power exponential function of three parameters, and the fitting curve can better reflect the changing trend of rheological parameters with density.

[0021] Through data fitting, it can be determined that there is a mathematical relationship between the rheological parameters and density of deep-sea mining plumes with a three-parameter power function. By coupling it with the power law model, a rheological model of kaolin plumes that takes into account density changes can be obtained. Deep-sea mining sediments have shear-thinning properties like kaolin, so the three-parameter power function relationship provided by this model can also be used to describe the changes in the rheological properties of deep-sea mining plumes with density.

[0022] Step S3-2, constructing a rheological model of deep-sea mining plumes that takes into account changes in physical properties; determining the variation of rheological parameters with physical parameters by means of data fitting. By means of data fitting, it can be determined that there is a mathematical relationship of a three-parameter power function between the rheological parameters and density of the deep-sea mining plumes. By coupling it with the power law model, a rheological model of kaolin plumes that takes into account changes in density can be obtained. The specific coupling method is as follows: Formula (1) and formula (2) are rheological parameters K and n The relationship between density and density is expressed in formula (3). Substituting formula (1) and formula (2) into formula (3), a rheological model of deep-sea mining plume considering the change of plume density can be constructed, as shown in formula (4).

[0023] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0024] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for establishing a rheological model of deep-sea mining plumes taking into account changes in physical properties, characterized in that , specifically including the following steps: Step S1, establishing a deep-sea mining plume rheology database under different rheological models, specifically comprising the following steps: Step S1-1, determining a rheological model that describes a deep-sea mining plume with a certain density, including a typical non-Newtonian fluid rheological model such as a power law model, a Bingham model, and a Herschel-Bulkley model. A non-Newtonian fluid refers to a fluid that does not satisfy Newton's law of internal friction. Step S1-2, according to the physical property changes experienced by the deep-sea mining plume during its evolution as required, determine the physical property parameter representing the entire evolution process, and define the range of change of the parameter during the sediment evolution process; Step S1-3, establishing a database of rheological parameters of deep-sea mining plumes, and establishing a database of rheological property parameters of deep-sea mining plumes varying with density under different rheological models according to different rheological models describing the deep-sea mining plumes; Step S2, analyzing and comparing the differences in rheological parameters of deep-sea mining plumes under different rheological models, specifically includes the following steps: Step S2-1, data difference visualization analysis: dividing the full range of physical parameter changes of deep-sea mining plumes, and then evaluating the distribution range of rheological parameters within a smaller range of physical parameter changes by drawing box plots; Step S2-2, quantitative analysis of data differences; calculation of 0.5 g / cm 3 The range of rheological parameters within the range of physical parameter changes is calculated, and the average value of the range and the ratio of the maximum value of the range to the average value are calculated within the full range of physical parameter changes of deep-sea mining plumes, and the density range where the maximum value is located is statistically analyzed; based on the visual analysis of data differences, the rheological parameters are calculated at a density gradient of 0.05 g / cm 3 The range of rheological test data in each single density interval is used to carry out quantitative analysis of data differences; the range of data in a certain interval is the difference between the maximum and minimum values ​​of the data in the interval, indicating the size of the data distribution range in this interval; Step S2-3, selecting a rheological model that describes the rheological characteristics of deep-sea mining sediment plumes; comprehensively considering the data difference visualization analysis and quantitative analysis results, selecting a rheological model with the smallest data difference, and constructing a deep-sea mining plume rheological model that considers changes in physical properties based on the model; Step S3, constructing a deep-sea mining plume rheological model taking into account the change of physical properties to construct the relationship between rheological parameters and density, specifically including the following steps: Step S3-1, constructing the quantitative relationship between rheological parameters and physical parameters; the relevant parameters of environmental water include ρ =1g / cm 3 ; K =0.001Pa·s; n =1 into the fitting database and ensure that the relevant parameters of water are consistent with the fitting results. ρ and K and n All of them show the relationship of power exponential function of three parameters; Step S3-2, constructing a rheological model of deep-sea mining plumes that takes into account changes in physical properties; determining the variation of rheological parameters with physical parameters by means of data fitting. By means of data fitting, it can be determined that there is a mathematical relationship of a three-parameter power function between the rheological parameters and density of the deep-sea mining plumes. By coupling it with the power law model, a rheological model of kaolin plumes that takes into account changes in density can be obtained. The specific coupling method is as follows: Formula (1) and formula (2) are rheological parameters K and n The relationship between ρ and density is given by equation (3). Substituting equations (1) and (2) into equation (3), a rheological model of deep-sea mining plume considering the change of plume density can be constructed, as shown in equation (4). （1） （2） （3） （4）。 2. A method for establishing a rheological model of deep-sea mining plume considering changes in physical properties according to claim 1, characterized in that In step S1-2, the density range of the deep-sea mining plume is determined to be no more than 1.50 g / cm 3 .

3. A method for establishing a rheological model of deep-sea mining plume considering changes in physical properties according to claim 1, characterized in that The box plot in step S2-1 shows the rheological test data in the density change at a density gradient of 0.05 g / cm 3 The maximum value, minimum value, median, and upper and lower quartiles within the interval are used to describe the distribution range and dispersion of the data within the interval.

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