Monitoring method for identifying form and concentration of uranium in neutral in-situ leaching leachate based on Raman spectrum

Abstract

The invention belongs to the technical field of in-situ leaching uranium mining in uranium mining and smelting, and particularly relates to a monitoring method for recognizing the form and concentration of uranium in neutral in-situ leaching leachate based on Raman spectrum. The monitoring method comprises the following steps: identifying the form of uranium in the in-situ leaching uranium extraction leachate and optionally quantitatively monitoring the concentration of uranium in the in-situ leaching uranium extraction leachate, wherein the identification of the form of uranium in the in-situ leaching uranium extraction leachate comprises the following steps: (1) collecting a first Raman spectrum; (2) processing first spectral data; quantitatively monitoring the uranium concentration in the in-situ leaching uranium extraction leachate; (3) collecting a second Raman spectrum; (4) processing second spectral data; (5) establishing a Raman quantitative relation; and (6) determining the uranium concentration of unknown leachate. The method is an in-situ, lossless and rapid quantitative detection means, and can make up for the defects of the existing test means.

Description

Technical Field

[0001] This invention belongs to the field of in-situ leaching uranium mining technology, specifically involving a monitoring method for identifying the uranium spectra and concentration in neutral leaching solutions based on Raman spectroscopy. Background Technology

[0002] In-situ leaching is currently the primary method for mining natural uranium deposits. Leaching solution is injected into the uranium reservoir through a mine shaft. Through a water-rock reaction process, the solid uranium ore dissolves into the solution, which is then extracted. Leaching methods include acid leaching and neutral leaching. Uranium complexes with ions such as hydroxide or carbonate to form soluble uranyl ion complexes, facilitating extraction. The concentration of uranium in the leaching solution extracted from the mine is a key indicator of the efficiency of in-situ leaching uranium mining.

[0003] Currently, the main methods for determining the uranium content in leaching solutions include X-ray fluorescence spectrometry, alpha energy dispersive spectroscopy, mass spectrometry, and inductively coupled plasma atomic emission spectrometry. Existing methods primarily focus on the relative proportion and content of uranium in the leaching solution. However, uranium in leaching solutions exists in more than one form: uranyl ion complexes, such as [UO2(CO3)2]. 2- and [UO2(CO3)3] 4- Most existing methods rely on the pH and HCO3 of the solution. - Methods such as content analysis are used to infer the morphology and content of different complexed ions in the solution. However, existing methods can damage the leaching solution sample during the determination process, making non-destructive testing impossible. Furthermore, these methods suffer from long sample processing and testing cycles and high economic costs. Summary of the Invention

[0004] The purpose of this invention is to address the problem in neutral uranium leaching processes where Raman spectroscopy analysis of uranium-containing leachates lacks a quantitative relationship between characteristic peak information of uranium acyl ion complexes and uranium concentration, making it impossible to directly obtain the concentration of different uranium forms in the solution. This invention provides a monitoring method based on Raman spectroscopy to identify the uranium forms and concentrations in neutral leaching solutions, solving the problem that traditional testing methods cannot quickly detect the uranium forms and concentrations in neutral leaching solutions. This method is simple and allows for rapid analysis.

[0005] Therefore, this invention provides a monitoring method for identifying the speciation and concentration of uranium in neutral leaching solutions based on Raman spectroscopy. The monitoring method includes identifying the speciation of uranium in the leaching solution and, optionally, quantitatively monitoring the concentration of uranium in the leaching solution. I. Identification of uranium speciation in uranium leaching solutions from in-situ uranium mining: (1) First Raman spectral acquisition: Raman spectra of uranyl ion complexes in the filtered unknown leachate were collected, and high signal-to-noise ratio Raman spectra were collected on the surface of the unknown leachate. (2) First spectral data processing: The Raman peak shifts of the characteristic peaks of uranyl ion complexes were obtained using Labspec software, and the type of uranyl ion complex was determined based on the Raman peak shifts. II. Quantitative monitoring of uranium concentration in uranium leaching solution from in-situ uranium mining: (3) Select multiple groups of leaching solutions with known uranium concentrations as standard solutions and perform steps (1) and (2) respectively. (4) Second Raman spectral acquisition: Raman characteristic peaks of water in ground leachate were collected; (5) Second spectral data processing: The Raman characteristic peaks of uranyl ion complexes and water in ground leaching solution were fitted using GRAMS / AI software to obtain the peak height data of their respective Raman characteristic peaks. (6) Establishment of Raman quantitative relationship: The Raman peak height ratio (HR) is used to establish a quantitative relationship. That is, the ratio of the peak height of the uranyl ion complex to that of water in the leaching solution is used to obtain a quantitative relationship between HR and the uranium concentration in the leaching solution by fitting a function between the peak height of the uranium ion complex and the concentration value. (7) Determination of uranium concentration in unknown leachate: The peak heights of the uranyl ion complex and the water in the leaching solution are obtained, and the corresponding peak height ratio HR is calculated. The concentration of uranium in the unknown leaching solution is calculated based on the quantitative relationship obtained in step (6).

[0006] Raman spectroscopy is a non-destructive method based on the inelastic scattering spectrum produced by laser light acting on molecules. The Raman shift, calculated from the difference in frequencies between the incident and reflected light, allows for the identification of molecular species and qualitative analysis of the chemical composition of substances. Furthermore, by using concentration standard curves, the magnitude of the Raman characteristic peaks of each substance can be used to calculate its concentration within the observed area. In summary, this method is an in-situ, non-destructive, and rapid quantitative detection technique. Therefore, Raman spectroscopy can be used for in-situ, non-destructive monitoring of the speciation and concentration of uranium in leaching solutions, overcoming the limitations of existing testing methods.

[0007] According to the present invention, in step (4) of the above-mentioned monitoring method for identifying the uranium spectra and concentration in neutral ground leaching solution based on Raman spectroscopy, the peak intensity of water in the ground leaching solution is not fixed each time the concentration is measured by spectral acquisition in the solution. Therefore, step (4) needs to be performed again each time to collect the Raman characteristic peaks of water in the ground leaching solution to calculate the peak height ratio HR.

[0008] As a preferred embodiment, in step (1) of the above-mentioned monitoring method for identifying the uranium spectra and concentration in neutral ground leaching solution based on Raman spectroscopy, a sample is taken from the neutral ground leaching solution to be measured, and the leaching solution sample is filtered using a polypropylene filter membrane with a pore size of 0.22~0.45μm to obtain the filtered leaching solution.

[0009] According to the present invention, in step (1) of the above-described monitoring method for identifying the speciation and concentration of uranium in neutral ground leaching solutions based on Raman spectroscopy, at 700-950 cm⁻¹ -1 The Raman spectrum of the uranyl ion complex was collected at this location. This is determined by the shift of the Raman characteristic peak of the uranyl ion complex. This range can ensure the collection of complete Raman characteristic peaks and is a conventional choice for Raman acquisition.

[0010] As a preferred embodiment, in step (1) of the above-mentioned monitoring method for identifying the uranium spectra and concentration in neutral ground leaching solutions based on Raman spectroscopy, the exposure time is (200~300 s) × (15-25 times). This high exposure time and number of exposures can reduce the signal-to-noise ratio of spectral acquisition and improve the accuracy of data acquisition.

[0011] As a preferred embodiment, in step (1) of the above-mentioned monitoring method for identifying the uranium spectra and concentration in neutral leaching solutions based on Raman spectroscopy, the laser wavelength of the Raman spectrometer is 532 nm and the grating is 1800 scales / mm.

[0012] The Raman characteristic peak range of water is 2650-3900 cm⁻¹. -1 As a preferred embodiment, in step (4) of the above-mentioned monitoring method for identifying the speciation and concentration of uranium in neutral ground leaching solution based on Raman spectroscopy, the concentration is measured at 2600-4000 cm⁻¹. -1 It can collect the complete Raman characteristic peaks of water in ground leaching solution.

[0013] As a preferred embodiment, in step (4) of the above-mentioned monitoring method for identifying the uranium spectra and concentration in neutral ground leaching solutions based on Raman spectroscopy, the exposure time is (10~20 s) × (10-15 times). This is to obtain spectral data with a good signal-to-noise ratio. Because the intensity of the single-second Raman peak of water is much higher than that of uranyl ion complexes, the exposure time for water only needs to be 10-20 s, and the number of acquisitions required is also lower than that for uranyl ion complexes.

[0014] As a preferred embodiment, in step (5) of the above-mentioned monitoring method for identifying the speciation and concentration of uranium in neutral ground leaching solution based on Raman spectroscopy, GRAMS / AI software is used at 770-850 cm⁻¹. -1 The Raman characteristic peaks of uranyl ion complexes were fitted within a specific range. [UO2(CO3)3] 4- Raman Peak is located at 770-850 cm. -1During the data fitting process, it is necessary to determine the two endpoints of the Raman peak. This range is the two endpoints of the characteristic peak of the substance, which can completely obtain the peak height data of the Raman peak.

[0015] As a preferred embodiment, in step (5) of the above-mentioned monitoring method for identifying the speciation and concentration of uranium in neutral ground leaching solution based on Raman spectroscopy, GRAMS / AI software is used at 2650-3900 cm⁻¹. -1 The Raman characteristic peaks of water in the infiltration solution were fitted within a specific range. This range is determined by the Raman characteristic peak range of water in the infiltration solution, with the peak endpoints at 2650 and 3900 cm⁻¹. -1 .

[0016] As a preferred embodiment, in step (6) of the above-mentioned monitoring method for identifying the speciation and concentration of uranium in neutral ground leaching solution based on Raman spectroscopy, the goodness of fit R... 2 ≥0.99.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: This invention provides a monitoring method for identifying the speciation and concentration of uranium in neutral ground leaching solutions based on Raman spectroscopy. This method, previously unseen both domestically and internationally, involves analyzing uranium-containing leaching solutions using Raman spectroscopy to establish a quantitative relationship between the characteristic peak information of uranyl ion complexes and the uranium concentration, thereby obtaining the uranium concentration in the leaching solution from neutral ground leaching. This method is an in-situ, non-destructive, and rapid quantitative detection technique that can overcome the shortcomings of existing testing methods.

[0018] This invention enables rapid and accurate identification and determination of the speciation and concentration of uranium in leaching solutions without damaging the sample. The Raman quantitative relationship only needs to be established during the initial use; subsequent uses do not require re-establishment. This significantly reduces the workload, testing time, and costs.

[0019] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0020] Figure 1 A partial operation flowchart of the monitoring method of the present invention is shown; Figure 2 The identification of uranyl ion speciation in the neutral leachate of Example 1 of the present invention is shown; Figure 3 The [UO2(CO3)3] shown in Embodiment 2 of the present invention is illustrated. 4- The fitting relationship between the peak height ratio (HR) of water in the leaching solution and the uranium concentration in the leaching solution. Detailed Implementation

[0021] The following description provides numerous specific details to offer a more thorough understanding of the technical solutions provided by this invention. However, it will be apparent to those skilled in the art that the technical solutions provided by this invention can be implemented without one or more of these details.

[0022] Example 1 This embodiment provides a method for identifying the uranium speciation in uranium leaching solutions obtained from in-situ uranium mining. The specific operation steps are as follows: Step 1: Leachate Treatment Take 2 mL of neutral leachate using a syringe, filter the leachate through a 0.22 μm polypropylene filter membrane to obtain the filtered leachate.

[0023] Step 2: Raman spectroscopy acquisition The filtered leachate was placed in an open glass bottle with a diameter of 15 mm and positioned below the objective lens of a Raman spectrometer. The spectra of the leachate were acquired using the Raman spectrometer. The objective lens height was adjusted to focus and regulate the intensity of the Raman signal until the Raman characteristic peak reached its maximum height, indicating optimal signal strength. The optimal range was 700-950 cm⁻¹. -1 Raman spectra of uranyl ion complexes were collected. Due to the low uranium content in the leaching solution, the exposure time needed to be increased to obtain Raman spectra with a high signal-to-noise ratio. The exposure time was set to 240 s × 20 times. Key parameters of the Raman spectrometer in this embodiment are: laser wavelength of 532 nm and grating of 1800 graduations / mm.

[0024] Step 3: Data Processing Use Labspec software to open the Raman spectrum and find the Raman characteristic peaks. The Raman shift corresponding to the highest intensity of the Raman characteristic peak is the Raman shift of that characteristic peak. Based on the leaching method and the Raman shift of uranyl ions, determine the uranyl ion morphology corresponding to the spectrum. Figure 2 (The horizontal axis represents the Raman shift, and the vertical axis represents the relative intensity of the Raman scattering signal.) As shown in Table 1, in this embodiment, the uranyl ion complex in the neutral leachate is [UO2(CO3)3]. 4- No other forms of uranyl ion complexes were detected.

[0025] Table 1. Raman peak shifts and corresponding ion speciations of uranyl ions in neutral leachate.

[0026] Example 2 This embodiment provides a method for identifying uranium speciation in uranium leaching solutions and a method for quantitatively monitoring uranium concentration, referencing... Figure 1 The specific operating steps are as follows: Step 1: Leachate Treatment Take 3 mL of the leachate using a syringe, and filter the leachate through a 0.22 μm polypropylene filter membrane to obtain the filtered leachate.

[0027] Step 2: Raman spectroscopy acquisition The filtered leachate was placed in an open glass bottle with a diameter of 15 mm and positioned below the objective lens of a Raman spectrometer. The leachate was then subjected to Raman spectroscopy to collect spectra in the range of 750-950 cm⁻¹. -1 Raman spectra of uranyl ion complexes were collected at the site. In this embodiment, the exposure time was set to 300 s × 20 times.

[0028] In addition, it is also necessary to be in the 2600-4000 cm range. -1 Raman spectra of water in the leaching solution were collected. Since the Raman characteristic peaks of water in the leaching solution are strong, the required exposure time is short; in this embodiment, the exposure time is 20 s × 10 times. Neutral leaching solutions with uranium concentrations of 16.09, 138, and 506 mg / L were used in this embodiment.

[0029] Step 3: Data Processing The Raman characteristic peaks of the three sets of Raman spectra were identified using Labspec software, and the Raman shifts of each peak were obtained, as shown in Table 2. The results show that the Raman shifts of the spectra obtained for the three solutions are 810-811 cm⁻¹. -1 Therefore, the uranyl ion complex in the three solutions is [UO2(CO3)3]. 4- .

[0030] After determining the type of uranyl ion complex, the spectrum was integrated using GRAMS / AI software to obtain UO2(CO3)3. 4- (770-850 cm) -1 ) and water in the ground leachate (2650-3900 cm) -1 The peak height of UO2(CO3)3 in different solutions was calculated based on the different exposure times of the two spectra. Since the exposure times of the two spectra were different, the peak height was divided by the respective exposure time to obtain the peak height per second, and the concentration of UO2(CO3)3 in different solutions was calculated accordingly. 4- The peak height ratio (HR) of water in the ground leaching solution is shown in Table 2.

[0031] Table 2. [UO2(CO3)3] in leachates of different concentrations 4- HR

[0032] Step 4: Establishing Raman quantitative relationships Use [UO2(CO3)3] 4-A relationship was fitted between the uranium peak height ratio (HR) and the concentration of water in the leaching solution. The relationship must pass through the origin because the Raman peak height is 0 when the uranium concentration is 0. Based on these two fitting principles, the following results were obtained: Figure 3 The fitting relationship is shown. The fitting formula is: uranium concentration in leachate = 57229 × peak height ratio, i.e., ρ = 57229 × HR, in mg / L, with a goodness of fit R. 2 It is 0.997.

[0033] Step 5: Based on the fitting formula obtained in Step 4, Raman spectra were acquired using a solution sample with a uranium concentration of 44 mg / L. After data processing, the Raman characteristic peak shift was 816 cm⁻¹. -1 , is [UO2(CO3)3] 4- The peak height ratio (HR) was obtained as 0.000780, and the uranium concentration was calculated to be 44.64 mg / L, which differed from the actual concentration of the sample by about 1.45%, proving that the formula can accurately predict the concentration of uranium in the solution.

[0034] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A monitoring method for identifying the speciation and concentration of uranium in neutral ground leaching solutions based on Raman spectroscopy, characterized in that, The monitoring method includes the identification of uranium speciation in in-situ uranium leaching solution and, optionally, the quantitative monitoring of uranium concentration in in-situ uranium leaching solution: I. Identification of uranium speciation in uranium leaching solutions from in-situ uranium mining: (1) First Raman spectral acquisition: Raman spectra of uranyl ion complexes in the filtered unknown leachate were collected, and high signal-to-noise ratio Raman spectra were collected on the surface of the unknown leachate. (2) First spectral data processing: The Raman peak shifts of the characteristic peaks of uranyl ion complexes were obtained using Labspec software, and the type of uranyl ion complex was determined based on the Raman peak shifts. II. Quantitative monitoring of uranium concentration in uranium leaching solution from in-situ uranium mining: (3) Select multiple groups of leaching solutions with known uranium concentrations as standard solutions and perform steps (1) and (2) respectively. (4) Second Raman spectral acquisition: Raman characteristic peaks of water in ground leachate were collected; (5) Second spectral data processing: The Raman characteristic peaks of uranyl ion complexes and water in ground leaching solution were fitted using GRAMS / AI software to obtain the peak height data of their respective Raman characteristic peaks. (6) Establishment of Raman quantitative relationship: The Raman peak height ratio (HR) is used to establish a quantitative relationship, that is, the ratio of the peak height of uranyl ion complex to that of water in the leaching solution is used to obtain a quantitative relationship between HR and the uranium concentration in the leaching solution by performing a function fitting between the peak height ratio of uranyl ion complex to that of water in the leaching solution and the concentration value. (7) Determination of uranium concentration in unknown leachate: The peak heights of the uranyl ion complex and the water in the leaching solution are obtained, and the corresponding peak height ratio HR is calculated. The concentration of uranium in the unknown leaching solution is calculated based on the quantitative relationship obtained in step (6).

2. The monitoring method for identifying the speciation and concentration of uranium in neutral ground leaching solution based on Raman spectroscopy according to claim 1, characterized in that, In step (1), a sample is taken from the neutral leachate to be tested, and the leachate sample is filtered using a polypropylene filter membrane with a pore size of 0.22~0.45μm to obtain the filtered leachate.

3. The monitoring method for identifying the speciation and concentration of uranium in neutral ground leaching solution based on Raman spectroscopy according to claim 1, characterized in that, In step (1), at 700-950 cm -1 Raman spectra of uranyl ion complexes were collected at the site.

4. The monitoring method for identifying the speciation and concentration of uranium in neutral ground leaching solution based on Raman spectroscopy according to claim 1, characterized in that, In step (1), the exposure time is (200~300 s) × (15-25 times).

5. The monitoring method for identifying the speciation and concentration of uranium in neutral ground leaching solution based on Raman spectroscopy according to claim 1, characterized in that, In step (1), the laser wavelength of the Raman spectrometer is 532 nm and the grating is 1800 scales / mm.

6. The monitoring method for identifying the speciation and concentration of uranium in neutral ground leaching solution based on Raman spectroscopy according to claim 1, characterized in that, In step (4), at 2600-4000 cm -1 Raman characteristic peaks of water in ground leachate were collected.

7. The monitoring method for identifying the speciation and concentration of uranium in neutral ground leaching solution based on Raman spectroscopy according to claim 1, characterized in that, In step (4), the exposure time is (10~20 s) × (10-15 times).

8. The monitoring method for identifying the speciation and concentration of uranium in neutral ground leaching solution based on Raman spectroscopy according to claim 1, characterized in that, In step (5), GRAMS / AI software was used at 770-850 cm. -1 The Raman characteristic peaks of uranyl ion complexes were fitted within a certain range.

9. The monitoring method for identifying the speciation and concentration of uranium in neutral ground leaching solution based on Raman spectroscopy according to claim 1, characterized in that, In step (5), GRAMS / AI software was used at 2650-3900 cm. -1 The Raman characteristic peaks of water in the ground leaching solution were fitted within the interval.

10. The monitoring method for identifying the speciation and concentration of uranium in neutral ground leaching solution based on Raman spectroscopy according to claim 1, characterized in that, In step (6), the goodness of fit R 2 ≥0.99.

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