CN116754588B - Method for predicting ion adsorption type rare earth deposit burial depth in weathered crust - Google Patents

Abstract

The invention discloses a method for predicting the burial depth of ion adsorption rare earth deposits in weathering crust, and relates to the technical field of exploration and mineralization. It includes: using clay mineral non-oriented powder crystal X-ray diffraction and directional plate X-ray diffraction analysis results, through Jade 6.5 Analyze and calculate the characteristic peak areas of kaolinite and halloysite mineral phases to obtain the kaolinite-halloysite mineral content in the weathering crust; calculate the crystallinity of kaolinite in the weathering crust from the X-ray diffraction spectrum of clay mineral powder crystals. This invention determines the position of the groundwater phreatic surface fluctuation zone through the rapid changes in kaolinite-halloysite content and kaolinite crystallization index, and determines that the enrichment layer of ion-adsorbed rare earth in the weathering crust is at the bottom of the groundwater fluctuation zone; This invention can combine the correlation between the specific parameters of the visible-near infrared reflection spectrum and the crystallinity of kaolinite to quickly and accurately delineate the weathering crust ion adsorption type rare earth ore body in the prospecting and exploration work.

Description

A method for predicting the burial depth of ion-adsorbed rare earth deposits in weathering crust

Technical field

The invention relates to the technical field of exploration and mineralization, and in particular to a method for predicting the burial depth of ion adsorption rare earth deposits in weathering crust.

Background technique

As "industrial vitamins", rare earth elements are widely used in new energy technology, new materials, aerospace, national defense and military industry and other fields. As the global demand for rare earths (especially heavy rare earths) increases year by year, the exploration, development and utilization of rare earth deposits has become particularly important. Ion-adsorbed rare earth deposits are my country's dominant mineral resources. They are mainly distributed in the weathering crust of granitic rocks in South my country. They have the characteristics of high content of medium and heavy rare earths, complete distribution, low radioactive activity and easy mining. They provide more than 100,000 ion-absorbing rare earth deposits in the world. 90% heavy rare earth resources.

It is generally believed that clay minerals can absorb rare earth ions released by rare earth accessory minerals during the weathering process, thereby enriching ore deposits in the entire weathering layer of the weathering crust. Among them, kaolinite and halloysite are the main carriers of ionic rare earths. The mineral composition and crystal structure properties of clay minerals can reflect the adsorption capacity of the weathering crust to rare earth ions. When the exchangeable ionic rare earth content adsorbed by the clay in the weathering crust reaches the cut-off grade for mining (above 300ppm), it can be formed. mineral deposits.

The burial depth of weathered crust ion-adsorbed rare earth ore bodies is generally 5-30m, and the use of geochemical exploration to delineate ore bodies often results in parts of the ore bodies being ignored. Therefore, using mineralogy indicators to determine the approximate location and distribution of ore bodies can provide effective support for the prospecting and exploration of weathered crust ion adsorption rare earth deposits, improve the accuracy of deposit assessment, and achieve the purpose of efficient utilization of rare earth resources.

Therefore, proposing a method for predicting the burial depth of ion-adsorbed rare earth deposits in weathering crust to solve the difficulties existing in the existing technology is an urgent problem that those skilled in the art need to solve.

Contents of the invention

In view of this, the present invention provides a method for predicting the burial depth of ion-adsorbed rare earth deposits in weathering crust, using the relative content of kaolinite (Kln)-halloysite (Hly) in the weathering crust and the kaolinite crystallinity index R2 and SC11-int and other means to determine the fluctuation zone of the groundwater phreatic surface, and then through the burial depth of the rare earth element-rich ore layer in the South China weathering crust, which is mainly distributed under the phreatic surface, to further improve the accuracy of the ion-adsorbed rare earth mineral deposit-rich layer in the weathering crust. The accuracy of delineating and evaluating mineral deposit reserves satisfies the purpose of prospecting and exploration of weathered crust ion adsorption rare earth deposits and efficient utilization of rare earth resources.

In order to achieve the above objects, the present invention adopts the following technical solutions:

A method for predicting the burial depth of ion-adsorbed rare earth deposits in weathering crust, including the following steps:

S1. Take weathering crust samples and conduct powder crystal X-ray diffraction analysis on the whole rock;

S2. Extract clay minerals from weathered crust samples;

S3. Perform powder crystal X-ray diffraction and directional plate X-ray diffraction analysis on the extracted clay minerals;

S4. Use the powder crystal X-ray diffraction and clay mineral oriented plate X-ray diffraction analysis results of the whole rock to obtain and calculate the characteristic peak area of the kaolinite-halloysite mineral phase, and obtain the kaolinite-halloysite minerals in the weathering crust. content;

S5. In the X-ray diffraction spectrum of clay mineral powder crystal, calculate the crystallinity of kaolinite in the weathering crust through the following formula;

R2＝[1/2(K1+K2)-k]/[1/3(K1+K2+k)]

Among them, K1 is the diffraction intensity value of kaolinite (131) crystal plane in the weathering crust, K2 is the diffraction intensity value of kaolinite (1-31) crystal plane in the weathering crust, k is the difference between kaolinite (1-31) and (1-31) in the weathering crust. 131) The height value of the peak and valley between crystal plane diffraction;

S6. Determine the fluctuation zone of groundwater phreatic surface through changes in kaolinite-halloysite mineral content and kaolinite crystallinity, and the correlation between the visible-near-infrared reflectance spectrum specific parameter SC11-int and kaolinite crystallinity , to quickly and efficiently predict the occurrence layers of weathering crust ion adsorption rare earth deposits.

In the above method, optionally, in S2, the clay minerals in the weathering crust sample are obtained by physical sedimentation according to Stokes' law.

For the above method, optionally, the specific extraction of directional sheet X-ray diffraction analysis in S3 includes:

First, test the natural orientation of clay minerals, then heat the naturally oriented clay minerals at 120°C for 6 hours and then test the clay minerals that have been saturated with formamide for 20 minutes.

The above method, optionally, uses Jade 6.5 in S4 to obtain and calculate the characteristic peak area of kaolinite-halloysite mineral phase.

The above method, optionally, S6 also includes near-infrared spectroscopic analysis of the extracted clay minerals.

For the above method, optionally, use ViewSpecPro to perform the second-order derivation of the near-infrared spectrum to obtain the intensity value SC11-int of the spectral contribution center in the range of 4559.14–4561.54cm ^-1 . Through the spectral parameter SC11-int and kaolinite The correlation of crystallinity can determine the location of the fluctuation zone of groundwater phreatic surface and predict the occurrence layers of ion adsorption type mineral deposits.

It can be seen from the above technical solutions that compared with the existing technology, the present invention provides a method for predicting the burial depth of ion adsorption rare earth deposits in weathering crust.

(1) The present invention is a method of using clay minerals to find rare earth rich ore layers in weathering crust. Through the rapid changes in kaolinite-halloysite content and kaolinite crystallization index R2 and SC11-int, the groundwater phreatic surface fluctuation zone is determined. , and determined that the rare earth enrichment layer is at the bottom of the groundwater fluctuation zone.

(2) The present invention provides accurate mineralogical indicators, can avoid leakage of rare earth ore bodies, accurately evaluate rare earth minerals, and utilize rare earth resources efficiently and rationally.

(3) The present invention can use the combined visible light-near infrared reflectance spectrum to meet the needs of the weathering crust ion adsorption type rare earth mineral deposit prospecting and exploration work to quickly and accurately delineate the ore body of the sample.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the provided drawings without exerting creative efforts.

Figure 1 is a flow chart of a method for predicting the burial depth of ion-adsorbed rare earth deposits in weathering crust provided by the present invention;

Figure 2 is a diagram showing the relationship between the rapid changes in kaolinite-halloysite relative content and the rapid changes in kaolinite crystallinity index R2 and SC11-int of the weathering crust sample provided by the present invention, and the enrichment levels of rare earth elements in the weathering crust.

Detailed ways

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 some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

Referring to Figure 1, the present invention discloses a method for predicting the burial depth of ion adsorption rare earth deposits in weathering crust, which includes the following steps:

S1. Take weathering crust samples and conduct powder crystal X-ray diffraction analysis on the whole rock;

S2. Extract clay minerals from weathered crust samples;

S3. Perform powder crystal X-ray diffraction and directional plate X-ray diffraction analysis on the extracted clay minerals;

S4. Use the powder crystal X-ray diffraction and clay mineral oriented plate X-ray diffraction analysis results of the whole rock to obtain and calculate the characteristic peak area of the kaolinite-halloysite mineral phase, and obtain the kaolinite-halloysite minerals in the weathering crust. content;

S5. In the X-ray diffraction spectrum of clay mineral powder crystal, calculate the crystallinity of kaolinite in the weathering crust through the following formula;

R2＝[1/2(K1+K2)-k]/[1/3(K1+K2+k)]

Among them, K1 is the diffraction intensity value of kaolinite (131) crystal plane in the weathering crust, K2 is the diffraction intensity value of kaolinite (1-31) crystal plane in the weathering crust, k is the difference between kaolinite (1-31) and (1-31) in the weathering crust. 131) The height value of the peak and valley between crystal plane diffraction;

S6. Use kaolinite-halloysite mineral content and changes in kaolinite crystallinity to determine the fluctuation zone of groundwater phreatic surface, and predict the occurrence layers of ion-adsorbed rare earth mineral deposits in weathering crust.

Furthermore, in S2, according to Stokes' law, the clay minerals in the weathering crust sample were obtained through physical sedimentation.

Further, the specific extraction of directional film X-ray diffraction analysis in S3 includes:

First, test the natural orientation of clay minerals, then heat the naturally oriented clay minerals at 120°C for 6 hours and then test the clay minerals that have been saturated with formamide for 20 minutes.

Furthermore, the characteristic peak area of kaolinite-halloysite mineral phase was obtained and calculated through Jade 6.5 in S4.

Further, S6 also includes near-infrared spectroscopy analysis of the extracted clay minerals.

Furthermore, ViewSpecPro was used to perform the second-order derivation of the near-infrared spectrum, and the intensity value SC11-int of the spectral contribution center in the range of 4559.14–4561.54cm ^-1 was obtained. Through the correlation between the spectral parameter SC11-int and the crystallinity of kaolinite , determine the position of the fluctuation zone of the groundwater phreatic surface, and predict the occurrence layers of ion adsorption type mineral deposits.

In a specific embodiment, the method for predicting weathered crust ion adsorption rare earth deposits based on clay mineral content and crystallinity is implemented as follows:

a. Conduct whole-rock powder crystal X-ray diffraction (XRD) phase analysis on weathering crust samples taken from the field;

b. According to Stokes' law, the clay minerals in the sample were obtained by physical sedimentation, and oriented XRD analysis was performed. Samples after natural orientation, heat treatment (120°C for 6 hours) and formamide saturation for 20 minutes were tested respectively;

c. Conduct powder crystal XRD and near-infrared spectroscopy (VNIR) analyzes on the extracted clay;

d. Use the powder crystal XRD and oriented XRD analysis results of the whole rock to obtain the characteristic peak area of each mineral phase through Jade 6.5, and calculate the area to obtain the relative content of kaolinite-halloysite minerals in the weathering crust;

e. In the XRD spectrum of clay powder crystal, calculate the crystallinity of kaolinite in the weathering crust through the following formula;

R2＝[1/2(K1+K2)-k]/[1/3(K1+K2+k)]

Among them, K1 is the diffraction intensity value of kaolinite (131) crystal plane in the weathering crust, K2 is the diffraction intensity value of kaolinite (1-31) crystal plane in the weathering crust, k is the difference between kaolinite (1-31) and (1-31) in the weathering crust. 131) The height value of the peak and valley between crystal plane diffraction;

f. Use ViewSpecPro to perform the second-order derivation of the VNIR spectrum to obtain the intensity value (SC11-int) of the spectral contribution center in the range of 4559.14–4561.54cm ^-1 , and use SC11-int to assist in judging the crystallinity of kaolinite;

g. Determine the fluctuation zone of groundwater phreatic surface through the relative content of kaolinite-halloysite minerals and changes in kaolinite crystallinity. Combined with the understanding that the rich ore layers of weathering crust ion adsorption rare earth deposits are below the phreatic surface, delineate Rare earth ore bodies and estimated deposit reserves.

The sample of the above embodiment comes from the rock weathering crust of an ion-adsorbed rare earth deposit in Meizhou City, Guangdong Province. In this embodiment, as shown in Table 1 below, the relative content of kaolinite Kln and halloysite Hly, kaolinite crystallization The measurement of degree index R2, SC11-int and rare earth element REE, as shown in Figure 2, shows that the sharp changes in clay mineral content and crystallinity indicate the fluctuation zone of the groundwater phreatic surface, thereby indicating the enrichment location of REE in the weathering crust.

Table 1

Depth(m) Kln(%) Hly(%) R2 SC11-int(a.u.E-04) REE(μg/g) 2 74.3 5.6 1.02 1.26 607 3 64.1 5.2 1.03 1.42 - 4 53.7 12.0 0.97 1.74 315 5 57.5 9.7 0.98 1.45 - 6 56.1 17.7 0.86 1.33 537 7 35.9 39.0 0.85 0.44 - 8 51.2 20.8 0.87 0.98 354 9 48.2 18.7 0.85 0.61 - 10 22.5 47.5 0.84 -1.10 501 12 14.1 54.5 0.79 -1.42 1107 14 40.4 15.4 0.90 0.93 996 16 57.6 11.5 0.95 1.35 3343 18 27.5 31.2 0.87 0.22 1761 20 33.6 25.2 0.95 -0.14 1661 twenty two 44.7 9.0 1.05 1.93 1143 twenty four 22.5 27.1 0.98 0.95 1976 26 37.4 6.8 0.98 1.04 1420 28 33.4 16.4 0.99 1.16 817 30 38.5 2.1 0.99 1.40 918 32 40.2 3.9 0.94 0.72 966 34 45.8 3.9 1.00 1.09 660

The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be practiced in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (4)

1. A method for predicting the burial depth of ion adsorption rare earth deposits in weathering crust, which is characterized by including the following steps: S1. Take weathering crust samples and conduct powder crystal X-ray diffraction analysis on the whole rock; S2. Extract clay minerals from weathered crust samples; S3. Perform powder crystal X-ray diffraction and directional plate X-ray diffraction analysis on the extracted clay minerals; S4. Use the powder crystal X-ray diffraction and clay mineral oriented X-ray diffraction analysis results of the whole rock to obtain and calculate the characteristic peak area of the kaolinite-halloysite mineral phase, and obtain the kaolinite-halloysite minerals in the weathering crust. content; S5. In the X-ray diffraction spectrum of clay mineral powder crystal, calculate the crystallinity of kaolinite in the weathering crust through the following formula; R2＝[1/2(K1+K2)-k]/[1/3(K1+K2+k)] Among them, K1 is the diffraction intensity value of kaolinite (131) crystal plane in the weathering crust, K2 is the diffraction intensity value of kaolinite (1-31) crystal plane in the weathering crust, k is the difference between kaolinite (1-31) and (1-31) in the weathering crust. 131) The height value of the peak and valley between crystal plane diffraction; S6. Determine the fluctuation zone of groundwater phreatic surface through changes in kaolinite-halloysite mineral content and kaolinite crystallinity, and predict the occurrence layers of weathering crust ion adsorption rare earth deposits; S6 also includes near-infrared spectroscopy analysis of the extracted clay minerals; Use ViewSpecPro to perform the second-order derivation of the near-infrared spectrum, and obtain the intensity value SC11-int of the spectral contribution center in the range of 4559.14–4561.54cm ^-1 . Through the correlation between the spectral parameter SC11-int and the crystallinity of kaolinite, the groundwater can be judged. The position of the water table fluctuation zone predicts the occurrence layers of ion adsorption type mineral deposits. 2. A method for predicting the burial depth of ion adsorption rare earth deposits in weathering crust according to claim 1, characterized in that, In S2, according to Stokes' law, the clay minerals in the weathering crust sample were obtained by physical sedimentation. 3. A method for predicting the burial depth of ion adsorption rare earth deposits in weathering crust according to claim 1, characterized in that, The specific extraction of directional film X-ray diffraction analysis in S3 includes: First, test the natural orientation of clay minerals, then heat the naturally oriented clay minerals at 120°C for 6 hours and then test the clay minerals that have been saturated with formamide for 20 minutes. 4. A method for predicting the burial depth of ion adsorption rare earth deposits in weathering crust according to claim 1, characterized in that, The characteristic peak area of kaolinite-halloysite mineral phase was obtained and calculated through Jade 6.5 in S4.