Concealed carbonate type rare earth ore exploration method

Abstract

The invention discloses a concealed carbonate type rare earth ore exploration method, and relates to the technical field of remote sensing hyperspectrum. Comprising the following steps: collecting overground part samples of different types of dominant plants in the carbonate type rare earth mining area, pre-treating the samples as different types of plant samples, measuring by using inductively coupled plasma mass spectrometry (ICP-MS) to obtain the Nd element content, screening out the plant sample with the strongest Nd element enrichment capacity as the dominant plant for spectral measurement, and determining the content of the Nd element in the dominant plant. Determining an actual reflection spectrum value; constructing an Nd element content estimation model based on the Nd element content and the actual reflection spectrum value in the plant sample; performing hyperspectral measurement on the research area, and screening the spatial distribution range of dominant plants to obtain a plant plane distribution diagram; and obtaining an Nd element content spatial distribution diagram by combining the Nd element content estimation model and the plant plane distribution diagram. According to the method, the spatial distribution range of the dominant plants can be effectively identified, so that the rare earth mineralization potential area is accurately delineated.

Description

Technical Field

[0001] The invention relates to the technical field of remote sensing hyperspectral technology, and in particular to a method for prospecting concealed carbonate-type rare earth mines. Background Art

[0002] Rare earth elements refer to 17 elements in the IIIB group of the periodic table, including lanthanide elements, yttrium and scandium. They are known as "vitamins of industry" and have irreplaceable excellent magnetic, optical and electrical properties. They play a huge role in improving product performance, increasing product variety and improving production efficiency. Due to their great role and small amount, rare earths have become an important element for improving product structure, increasing scientific and technological content and promoting technological progress in the industry. They are widely used in metallurgy, military, petrochemical, glass and ceramics, agriculture, new materials and other fields. The increasingly significant economic and social benefits and the continuously increasing demand have made it a strategic resource closely related to the development of emerging industries. In recent years, with the continuous mining of surface rare earth mines, the recoverable reserves are constantly decreasing. It is urgent to find new ore bodies in the deep and peripheral areas of the mining area to ensure the safety of rare earth mineral supply.

[0003] Using spectral measurement technology to measure the spectral absorption characteristics of soil, minerals, and plants, and using them for material composition analysis and mineralization clue identification is a new development direction of hyperspectral remote sensing technology in recent years. It has the advantages of fast speed, high efficiency, low cost, and low loss.

[0004] Boesche et al. used the Hyspex hyperspectral imager to map Nd, Er, Dy, Ho, Sm and Tm in the Fen carbonate rock mass in Telemark County, Norway, and used its diagnostic spectral absorption characteristics to identify rare earth elements in minerals. For example, the indicator bands of Sm are 1250nm and 1567nm, and the indicator bands of Nd are 800nm ​​and 744nm. Dai Jingjing et al. used the spectral absorption characteristics of rare earth elements in water bodies in southern Jiangxi to quantitatively invert the rare earth concentration, and thus achieve the goal of hydrochemical prospecting in areas with developed water systems. Chenggong et al. found through experiments that the five characteristic absorption bands of rare earth elements in visible light and near-infrared wavelengths are 370, 950, 1400, 1900 and 2200nm respectively. Through regression modeling of 5 rare earth characteristic absorption bands and visible light bands with the total rare earth content and 15 rare earth element contents of the ore samples, a quantitative prediction model for the rare earth content of the ore samples was obtained, which has a certain reference value for the rapid quantitative and semi-quantitative evaluation of rare earth ores. Zhang Hongrui et al. conducted a quantitative inversion study on ion-adsorbed rare earth ores based on the chemical exploration data and Landsat 8 remote sensing image data of Liutang ion-adsorbed rare earth mining area in Chongzuo City, Guangxi. The correlation analysis showed that the rare earth ore grade content of the sample was significantly negatively correlated with the spectral reflectance of the 1st, 2nd, 3rd, 5th, 6th and 7th bands of Landsat8 images. Cao Shengsheng et al. proposed a hyperspectral inversion method (national invention patent) for the content of sedimentary rare earth La elements. This method provides a new test method for the rapid quantitative inversion study of hyperspectral La elements on "points", and also provides a scientific and technical basis for the implementation of quantitative inversion evaluation of regional hyperspectral rare earth resources. At present, the research on extracting the distribution of rare earth minerals using remote sensing information has made certain progress. For example, in the research work conducted by Zhang Qinyu et al. on the rare earth mineralization area in Banqiao, Zhejiang, SPOT5 data was used to extract residual landform information in the study area, and the location of rare earth deposits in the study area was predicted and verified in combination with the range of weathered minerals extracted from ASTER images.

[0005] Although remote sensing technology has been applied in rare earth mining, most of it is focused on dynamic monitoring of mines and environmental pollution, while there are few results in rare earth prospecting. The limited literature on remote sensing prospecting of rare earths is mainly focused on weathering crust ion adsorption type rare earth ores, and their number is significantly less than that of bauxite, nickel ore and other minerals of the same weathering crust type. There are two main reasons for this. First, there are few professional and technical personnel in rare earth minerals, and the few practitioners have limited understanding of remote sensing technology, so remote sensing technology is not widely used in rare earth prospecting. Second, since some rare earth mines are mostly distributed in humid climate areas with relatively developed vegetation, the prospecting effect of remote sensing technology is affected to a certain extent.

[0006] Therefore, providing a method for prospecting for concealed carbonate-type rare earth minerals to solve the difficulties existing in the prior art is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0007] In view of this, the present invention provides a method for prospecting concealed carbonate-type rare earth deposits, which can effectively identify the spatial distribution range of dominant plants, thereby accurately delineating rare earth mineralization potential areas.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] A method for prospecting for concealed carbonate-type rare earth ore comprises the following steps:

[0010] S1. Collect the above-ground samples of different types of dominant plants in carbonate rock rare earth mining areas, and pre-treat the samples as different types of plant samples;

[0011] S2. Using inductively coupled plasma mass spectrometry (ICP-MS) to measure different types of plant samples, obtain the Nd content of different types of plant samples, and select the plant samples with the strongest Nd enrichment ability as dominant plants;

[0012] S3, performing spectral measurement on plant samples of different types to determine actual reflectance spectral values;

[0013] S4. Based on the Nd element content in the plant samples and the actual reflectance spectrum values, a Nd element content estimation model based on hyperspectral is constructed;

[0014] S5. Conduct hyperspectral measurement in the study area, screen the spatial distribution range of dominant plants and obtain a plant plan distribution map;

[0015] S6. Combine the Nd element content estimation model and the plant plan distribution map to obtain the spatial distribution map of the Nd element content.

[0016] Optionally, collecting above-ground samples in S1 includes: selecting plants with relatively consistent growth within an area of ​​5m×5m to 10m×10m at each sampling point, and collecting petioles and leaves of the plants.

[0017] Optionally, the sample pretreatment in S1 includes: freezing the sample overnight, freezing the plant sample in a freeze dryer and then crushing and mixing the plant sample, adding nitric acid and perchloric acid for digestion, and fixing the volume after the digestion is completed.

[0018] Optionally, the spectral measurement in S3 includes: performing multiple spectral measurements of the dominant plant outdoors using a ground object spectrometer, and taking an arithmetic mean of the multiple measurements as an actual reflectance spectral value of the plant sample.

[0019] Optionally, the Nd element content estimation model based on hyperspectral in S4 is constructed using partial least squares method or BP neural network algorithm.

[0020] Optionally, the hyperspectral measurement in S5 uses a UAV hyperspectral imaging system.

[0021] It can be seen from the above technical solution that compared with the prior art, the present invention provides a method for exploring concealed carbonate-type rare earth mines, which has the following beneficial effects: the present invention can eliminate and utilize the role of vegetation, by analyzing the enrichment ability of the dominant plants in the study area for the rare earth Nd element, combined with the fine recognition ability of the UAV hyperspectral imaging system, effectively identifying the spatial distribution range of the dominant plants, thereby accurately delineating the rare earth mineralization potential area. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0023] Figure 1 A flow chart of a method for prospecting a concealed carbonate-type rare earth ore disclosed in the present invention;

[0024] Figure 2 The plan distribution map of Crape Myrtles in the research area disclosed by the present invention;

[0025] Figure 3 This is the spatial distribution diagram of the Nd element content disclosed in the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In this application, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, the elements defined by the sentence "comprise one..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0028] Reference Figure 1 As shown, the present invention discloses a method for prospecting concealed carbonate-type rare earth ore, comprising the following steps:

[0029] S1. Collect the above-ground samples of different types of dominant plants in carbonate rock rare earth mining areas, and pre-treat the samples as different types of plant samples;

[0030] S2. Using inductively coupled plasma mass spectrometry (ICP-MS) to measure different types of plant samples, obtain the Nd content of different types of plant samples, and select the plant samples with the strongest Nd enrichment ability as dominant plants;

[0031] S3, performing spectral measurement on plant samples of different types to determine actual reflectance spectral values;

[0032] S4. Based on the Nd element content in the plant samples and the actual reflectance spectrum values, a Nd element content estimation model based on hyperspectral is constructed;

[0033] S5. Conduct hyperspectral measurement in the study area, screen the spatial distribution range of dominant plants and obtain a plant plan distribution map;

[0034] S6. Combine the Nd element content estimation model and the plant plan distribution map to obtain the spatial distribution map of the Nd element content.

[0035] Furthermore, collecting above-ground samples in S1 includes: selecting plants with relatively uniform growth in an area of ​​5m×5m to 10m×10m at each sampling point, and collecting petioles and leaves of the plants.

[0036] Furthermore, the sample pretreatment in S1 includes: freezing the sample overnight, crushing and mixing the plant sample after freeze drying in a freeze dryer, adding nitric acid and perchloric acid for digestion, and fixing the volume after digestion.

[0037] Specifically, after the samples were brought back to the laboratory, they were rinsed with deionized water for 2 to 3 times and placed in polyethylene bags. All plant samples were placed in a refrigerator at -20°C overnight and dried in a cold dryer for 72 hours. The plant samples were crushed and mixed, and about 0.3g to 0.5g of powder was weighed into a crucible. 10ml to 15ml of nitric acid and 0.3ml to 0.5ml of perchloric acid were added for digestion. After digestion, the volume was adjusted to 50ml.

[0038] Furthermore, the spectrum measurement in S3 includes: performing multiple spectrum measurements on the dominant plant using a ground object spectrometer outdoors, and taking the arithmetic mean of the multiple measurements as the actual reflectance spectrum value of the plant sample.

[0039] Specifically, the ground object spectrometer adopts the iSpecFiled-WNIR-HRs portable ground object spectrometer produced by Shenzhen Laisen Optics Co., Ltd. in China, and its wavelength range is 350nm-2500nm.

[0040] Furthermore, the Nd element content estimation model based on hyperspectral in S4 is constructed using partial least squares method or BP neural network algorithm.

[0041] Specifically, constructing a Nd element content estimation model includes: first, performing first-order derivative processing, SG filtering processing, standard normal variable transformation processing, multivariate scattering correction processing, and standard normal variable transformation on multiple spectral data obtained by resampling, and then performing SG filtering processing; then, the processed spectral data are screened using a continuous projection algorithm to obtain several characteristic bands; then, partial least squares regression is used to establish a model, and the several characteristic bands screened out are used as independent variables, and the thorium element content is used as the dependent variable; the training set and the prediction set are fitted to obtain the fitting results; finally, according to the fitting results, a model with a larger determination coefficient and a smaller root mean square error is selected as the final inversion model.

[0042] Furthermore, the hyperspectral measurement in S5 uses a UAV hyperspectral imaging system.

[0043] Specifically, the UAV hyperspectral imaging system adopts the GaiaSky-mini3-VN airborne hyperspectral imaging system produced by Jiangsu Shuangli Hepu Technology Co., Ltd. in China, and its spectral range is 400-1000nm.

[0044] In a specific embodiment, referring to Figure 2 and Figure 3As shown in the figure, taking the Yaoniuping rare earth mine in Mianning County, Liangshan Prefecture, Sichuan Province as an example, 15 samples of four local dominant herbaceous plants, namely, crape myrtle, potentilla, Bryophyllum sibiricum and Artemisia selengensis, were collected in the mining area, the rare earth element content in the plants was determined, and the plants with the strongest Nd element enrichment ability were screened out, that is, crape myrtle>potentilla>Bryophyllum sibiricum>Artemisia selengensis. The spectra of crape myrtle, potentilla, Bryophyllum sibiricum and Artemisia selengensis were measured outdoors using a ground object spectrometer, a total of 10 measurements were made, and the arithmetic mean of the 10 measured values ​​was taken as the actual reflectance spectrum value of the plant sample. The partial least squares method was used to construct the Nd element content estimation model based on hyperspectral data, and the expression is:

[0045] Y Nd =12.5+6.4X 560 -18.3X 720 +21.9X 810 +35.4X 840 -16.1X 920 ,

[0046] Among them, X 560 is the reflectivity value at 560nm, X 720 is the reflectivity value at 720nm, X 810 is the reflectivity value at 810nm, X 840 is the reflectivity value at 840nm, X 920 The reflectance value at 920nm was obtained by using the GaiaSky-mini3-VN UAV hyperspectral imaging system to carry out hyperspectral measurement in the study area. The hyperspectral data of the study area were obtained, and the spatial distribution range of Lagerstroemia indica was delineated to obtain the plane distribution map of Lagerstroemia indica. The spatial distribution map of Nd element content was obtained by combining the Nd element content estimation model and the plane distribution map of Lagerstroemia indica.

[0047] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for prospecting for concealed carbonate-type rare earth ore, characterized in that: The following steps are involved: S1. Collect the above-ground samples of different types of dominant plants in carbonate rock rare earth mining areas, and pre-treat the samples as different types of plant samples; S2. Using inductively coupled plasma mass spectrometry (ICP-MS) to measure different types of plant samples, obtain the Nd content of different types of plant samples, and select the plant samples with the strongest Nd enrichment ability as dominant plants; S3, performing spectral measurement on plant samples of different types to determine actual reflectance spectral values; S4. Based on the Nd element content in the plant samples and the actual reflectance spectrum values, a Nd element content estimation model based on hyperspectral is constructed; S5. Conduct hyperspectral measurement in the study area, screen the spatial distribution range of dominant plants and obtain a plant plan distribution map; S6. Combine the Nd element content estimation model and the plant plan distribution map to obtain the spatial distribution map of the Nd element content.

2. A method for prospecting for concealed carbonate-type rare earth ore according to claim 1, characterized in that: The aboveground part samples collected in S1 include: selecting plants with relatively uniform growth in an area of ​​5m×5m to 10m×10m at each sampling point, and collecting the petioles and leaves of the plants.

3. A method for prospecting for concealed carbonate-type rare earth ore according to claim 1, characterized in that: Sample pretreatment in S1 includes: freezing the samples overnight, using a freeze dryer to freeze-dry the plant samples, crushing and mixing them, adding nitric acid and perchloric acid for digestion, and fixing the volume after digestion.

4. A method for prospecting for concealed carbonate-type rare earth ore according to claim 1, characterized in that: The spectrum measurement in S3 includes: using a ground object spectrometer outdoors to perform multiple spectrum measurements on the dominant plants, and taking the arithmetic mean of the multiple measurements as the actual reflectance spectrum value of the plant sample.

5. The method for prospecting for concealed carbonate-type rare earth ore according to claim 1, characterized in that: The Nd element content estimation model based on hyperspectral in S4 is constructed using partial least squares method or BP neural network algorithm.

6. A method for prospecting for concealed carbonate-type rare earth ore according to claim 1, characterized in that: The S5 mid- and high-spectral measurements use a drone hyperspectral imaging system.

Images