A rapid rare earth concentration detection component and its application

Abstract

This invention relates to the technical field of rare earth concentration detection, specifically to a rapid rare earth concentration detection component and its application. The component includes a detection unit and detection reagents. The detection reagents include a buffer, a masking agent, and xylenol orange indicator. The detection unit is equipped with a reading scale and contains ethylenediaminetetraacetic acid (EDTA). In use, the liquid to be tested is mixed thoroughly with the detection reagent to obtain a mixture. The detection end of the detection unit is then inserted into the mixture, and the unit draws in the mixture. As the mixture rises along the detection unit, a wetting front and a color interface are formed. The reading at the color interface is taken and compared with a pre-calibrated conversion card to determine the rare earth concentration of the test solution. This invention calculates the concentration of the test solution by measuring the distance between the interface and the fluid wetting front, and adding the concentration of EDTA in the reaction medium, enabling rapid and accurate determination of the rare earth concentration in the test solution.

Description

Technical Field

[0001] This invention relates to the technical field of rare earth concentration detection, and specifically to a rapid rare earth concentration detection component and its application. Background Technology

[0002] Currently, the main methods for determining rare earth content include spectrophotometry, atomic emission spectrometry, oxalate gravimetric analysis, oxalate turbidimetric analysis, and EDTA titration. Spectrophotometry and atomic emission spectrometry can accurately determine rare earth content, but both require large, expensive instruments, have long testing cycles, and are unsuitable for field surveys. Oxalate gravimetric analysis uses oxalic acid to precipitate rare earth elements, followed by high-temperature calcination and weighing to obtain the rare earth content. However, this method is lengthy, cumbersome, and dependent on high-temperature calcination equipment, making it unsuitable for field surveys. Oxalate turbidimetric analysis uses a dispersant to disperse the precipitate formed by the reaction of oxalic acid and rare earth elements. The rare earth content is calculated by observing and measuring the suspension's morphology and turbidity. However, oxalic acid reacts with aluminum and iron impurities in the leachate to form soluble complexes, affecting the measurement results due to the concentration of these impurities. Traditional EDTA titration has advantages such as speed, simplicity, high accuracy, and no need for complex instruments and equipment. However, it requires a variety of reagents, has a long titration cycle, and the titration equipment is not easy to carry, which limits its application in field exploration. Summary of the Invention

[0003] One of the objectives of this invention is to provide a rapid rare earth concentration detection component that innovatively utilizes the EDTA (ethylenediaminetetraacetic acid) titration principle and reactive transport principle to achieve rapid determination of rare earth concentration. This component can quickly detect rare earth concentration with accurate and reliable results.

[0004] The second objective of this invention is to provide an application of a rapid rare earth concentration detection component.

[0005] One of the solutions adopted to achieve the objective of this invention is: a rapid rare earth concentration detection component, including a detection unit and a detection reagent. The detection reagent includes a buffer, a masking agent, and a xylenol orange indicator. The detection unit is equipped with a reading scale and contains ethylenediaminetetraacetic acid. In use, the liquid to be tested is mixed evenly with the detection reagent to obtain a mixed solution. Then, the detection end of the detection unit is inserted into the mixed solution, and the detection unit draws up the mixed solution. The mixed solution rises along the detection unit. During this process, a wetting front and a color interface are formed. The reading at the color interface is read and compared with a pre-calibrated reading conversion card to determine the rare earth concentration of the liquid to be tested.

[0006] Preferably, the buffering agent is any one of the following: acetic acid-sodium acetate buffer system, citric acid-sodium citrate buffer system, and hexamethylenetetramine-hydrochloric acid buffer system, and the pH of the buffering agent is 5.0 to 5.5.

[0007] Preferably, the masking agent is an aluminum ion masking agent or an aluminum ion masking agent and an iron ion masking agent.

[0008] Preferably, the aluminum ion masking agent is one or more of sulfosalicylic acid, citric acid, and tartaric acid; the iron ion masking agent is one or more of ascorbic acid, citric acid, and tartaric acid.

[0009] Preferably, the detection unit is a test strip or a test pipette. When a test strip is used, it is prepared by soaking neutral test paper in an EDTA solution and then drying it. When a test pipette is used, it is filled with a medium containing EDTA powder and can draw a fixed volume of solution.

[0010] Preferably, when the test strip is used for detection, the detection end of the test strip is inserted into the mixture. The mixture will rise along the test strip under capillary action. During this process, a wetting front and a color interface will be formed. When the wetting front reaches the designated position, the reading at the color interface is read and compared with the pre-calibrated reading conversion card to read the rare earth concentration of the test liquid.

[0011] Preferably, when using the detection pipette, a fixed volume of the mixture is drawn up with the pipette. When the drawing is complete, the reading at the color interface is read and compared with a pre-calibrated reading conversion card to determine the rare earth concentration of the test liquid.

[0012] Preferably, the system also includes a standard colorimetric card. The detection unit comprises multiple units, each filled with a different amount of ethylenediaminetetraacetic acid. The color of the mixture is compared with the standard colorimetric card, and then a suitable detection unit is selected for detection.

[0013] Preferably, the detection reagent comprises 10 mL of buffer, 0.5–1.5 g of aluminum ion masking powder, 0–1 g of iron ion masking powder, and 0.1–0.15 mL of xylenol orange indicator.

[0014] The concentration of xylenol orange indicator used is generally 2 g / L, and the volume of the liquid to be tested is generally 5 to 15 mL.

[0015] The second objective of this invention is achieved through the application of a rapid rare earth concentration detection component, which is used to detect the rare earth concentration in the leaching solution of weathered crust leached rare earth ore.

[0016] The components of this invention provide a rapid determination of rare earth concentration based on the principles of EDTA titration and reactive transport. The EDTA titration principle is as follows: Xylenol orange indicator is bright yellow in acidic solutions. When rare earth ions are present in the solution, xylenol orange undergoes a complexation reaction with the rare earth ions, turning the solution purplish-red. After adding EDTA, the complexation ability of EDTA with rare earths is stronger than that of xylenol orange. When the rare earth ions in the solution are completely complexed with EDTA, the solution returns to a bright yellow color. The reactive transport principle is as follows: when the reactant passes through the reaction medium in a dissolved form, the front of the reactant lags behind the front of the fluid, and the transport distance of the reactant is approximately exponentially related to the transport distance of the fluid. Utilizing these two principles, rare earth elements are used as the reactants, a rare earth-containing test solution as the fluid, and xylenol orange as the indicator. A certain amount of buffer and masking agent are also added. The entire mixture is passed through a reaction medium containing EDTA. During transport, the fluid tip gradually turns bright yellow, forming a color interface with the purplish-red color of the bulk solution. By measuring the distance between the interface and the fluid wetting tip, and adding this distance to the EDTA concentration in the reaction medium, the concentration of the test solution can be calculated. Compared to the oxalate gravimetric method and EDTA titration method, this method can rapidly and accurately determine the rare earth concentration in the test solution.

[0017] The present invention has the following advantages and beneficial effects:

[0018] The rapid rare earth concentration detection component of this invention is based on the principles of EDTA titration and reactive transport. It uses rare earth as the reactant, a rare earth-containing test liquid as the fluid, xylenol orange as the indicator, and adds buffers and masking agents. The entire component passes through a reaction medium containing EDTA. During transport, the color of the fluid tip gradually turns bright yellow, forming a color interface with the purplish-red color of the bulk solution. By measuring the distance between the interface and the fluid wetting tip, and adding the concentration of EDTA in the reaction medium, the concentration of the test liquid can be calculated. Compared with the oxalate gravimetric method and EDTA titration method, it can quickly and accurately determine the rare earth concentration in the test solution. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the detection principle of the present invention;

[0020] Figure 2 Simulated results of color development of test paper under different rare earth concentrations in the test solution;

[0021] Figure 3 Relationship between rare earth concentration in the test liquid and transport distance. Detailed Implementation

[0022] To better understand the present invention, the following embodiments are further illustrations of the present invention, but the content of the present invention is not limited to the following embodiments.

[0023] Example 1

[0024] A rapid rare earth concentration detection kit includes: ① a reagent mixing bottle; ② test strips. The reagent mixing bottle contains 10 mL of buffer (pH = 5.0–5.5), 1 g of aluminum ion masking powder, 0.5 g of iron ion masking powder (optional), and 3–5 drops of 2 g / L xylenol orange indicator. These reagents are mixed thoroughly to form a solution. The rapid test strip is made by soaking neutral test paper in EDTA solution and then drying it. The test strip has a pre-calibrated reading scale. The concentration of the EDTA solution is determined based on the concentration of the test solution; higher concentrations of EDTA solution are suitable for measuring high rare earth concentrations in test solutions. In use, the test solution is added to the reagent mixing bottle and shaken thoroughly. The color of the solution is observed, compared with a standard colorimetric card pre-made on the reagent mixing bottle, and the corresponding concentration range of rapid test strips or rapid detection pipettes is selected for testing.

[0025] Insert the test strip into the bottle. The mixture in the bottle will rise along the test strip under capillary action. During this process, a wetting front and a color interface will be formed. When the wetting front reaches the designated position, read the reading at the color interface and compare it with the pre-calibrated reading conversion card to determine the rare earth concentration of the test solution. Figure 1 As shown.

[0026] When the test liquid rises along the test paper under the action of capillary pressure, the volume fractions (also known as saturation) of the liquid phase and gas phase in the test paper satisfy the porous medium phase transport equations (1) and (2), respectively:

[0027]

[0028]

[0029] Where: ε p ρ is the porosity; ρ1 and ρ2 are the densities (kg / m³) of the liquid and gas phases in the test paper, respectively. 3 ); s1 and s2 are the saturation degrees of the liquid and gas phases, respectively, and s1 + s2 = 1; κ is the permeability of the test paper (m). 2 );κ r1 and κ r2 The relative permeability (m) of the liquid phase and the gas phase are respectively. 2 μ1 and μ2 are the dynamic viscosities (Pa·s) of the liquid and gas phases, respectively; p1 and p2 are the pressures (Pa) of the liquid and gas phases, respectively; g is the acceleration due to gravity (m / s²). 2 The capillary pressure in the phase transfer equation adopts the Brooks-Corey capillary pressure model.

[0030] In numerical simulations, the two phase transport equations and the Brooks-Corey capillary pressure model also need to be coupled with the continuity equation and Darcy's law:

[0031]

[0032]

[0033] In the formula: ρ is the average density of the liquid phase and the gas phase (kg / m³). 3 μ is the average dynamic viscosity of the liquid and gas phases (Pa·s); u is the flow velocity (m / s); p is the fluid pressure (Pa).

[0034] As the test solution containing rare earth ions rises along the test paper, the rare earth ions in the liquid phase are continuously complexed by EDTA on the solid phase during their ascent. This mass transfer process satisfies the convection-diffusion equation containing a sink term:

[0035]

[0036] In the formula: Rare earth ion concentration (mol / L); The effective diffusion coefficient (m) 2 k is the reaction rate constant (L·mol⁻¹ / s); k is the reaction rate constant (L·mol⁻¹ / s). -1 ·s -1 ); The concentration of EDTA on the solid phase is expressed in mol / L.

[0037] The concentration of EDTA on the solid phase satisfies the following relationship:

[0038]

[0039] Equations (1) to (6) fully describe the phase transfer and mass transfer process that occurs when the test liquid rises along the rapid test paper under capillary pressure. By combining appropriate initial values ​​and boundary conditions for numerical simulation, the position of the rare earth ion advance front in the test liquid when the top of the test paper is wetted can be determined. The liquid phase below this position contains rare earth ions and appears purplish-red, while the liquid phase above this position does not contain rare earth ions and appears bright yellow. The two colors thus form a clear interface. The dimensionless distance at this interface will have a certain relationship with the concentration of rare earth ions in the test liquid. Now, taking the parameters shown in Table 1 as an example, this relationship diagram is generated through numerical simulation. See Appendix for details. Figure 2 and attached Figure 3 .

[0040] Table 1. Numerical Simulation Related Parameters

[0041]

[0042]

[0043] Example 2

[0044] A rapid rare earth concentration detection kit includes: ① a reagent mixing bottle; ② a detection pipette. The reagent mixing bottle contains 10 mL of buffer (pH = 5.0–5.5), 1 g of aluminum ion masking powder, 0.5 g of iron ion masking powder (optional), and 3–5 drops of 2 g / L xylenol orange indicator. These reagents are mixed thoroughly to form a solution. The rapid detection pipette is filled with a medium containing EDTA powder and can draw a fixed volume of solution. In use, the test solution is added to the reagent mixing bottle and shaken thoroughly. The color of the solution is observed, and compared with a standard colorimetric card pre-prepared on the reagent mixing bottle. The corresponding concentration range of rapid test strip or rapid detection pipette is then selected for testing.

[0045] Insert the test pipette into the bottle and draw a fixed volume of the mixture at a certain speed. When the drawing is complete, read the reading at the color interface and compare it with the pre-calibrated reading conversion card to determine the rare earth concentration of the test solution.

[0046] The above description is merely a preferred embodiment of the present invention, and should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A rapid rare earth concentration detection method, implemented using a rapid rare earth concentration detection component, characterized in that: The rapid rare earth concentration detection component includes a detection unit and a detection reagent. The detection reagent includes a buffer, a masking agent, and a xylenol orange indicator. The detection unit is equipped with a reading scale and contains ethylenediaminetetraacetic acid. In use, the test solution and the detection reagent are mixed evenly to obtain a mixed solution. The detection end of the detection unit is then inserted into the mixed solution. The detection unit draws up the mixed solution, which rises along the detection unit. During this process, a wetting front and a color interface are formed. The reading at the color interface is read and compared with a pre-calibrated reading conversion card to determine the rare earth concentration of the test solution. The detection unit is a test strip or a test pipette. When a test strip is used, it is prepared by soaking neutral test paper in ethylenediaminetetraacetic acid solution and then drying it. When a test pipette is used, it is filled with a medium containing EDTA powder and can draw a fixed volume of solution. When the test strip is used for testing, the test end of the test strip is inserted into the mixture. The mixture will rise along the test strip under capillary action. During this process, a wetting front and a color interface will be formed. When the wetting front reaches the designated position, the reading at the color interface is read and compared with the pre-calibrated reading conversion card to read the rare earth concentration of the test liquid. When using the aforementioned detection pipette, a fixed volume of the mixture is drawn using the pipette. Once the drawing is complete, the reading at the color interface is taken and compared with a pre-calibrated reading conversion card to determine the rare earth concentration of the test liquid.

2. The rapid rare earth concentration detection method according to claim 1, characterized in that: The buffer is any one of the following: acetic acid-sodium acetate buffer system, citric acid-sodium citrate buffer system, and hexamethylenetetramine-hydrochloric acid buffer system, and the pH of the buffer is 5.0~5.

5.

3. The rapid detection method for rare earth concentration according to claim 1, characterized in that: The masking agent is an aluminum ion masking agent or an aluminum ion masking agent and an iron ion masking agent.

4. The rapid rare earth concentration detection method according to claim 3, characterized in that: The aluminum ion masking agent is one or more of sulfosalicylic acid, citric acid, and tartaric acid; the iron ion masking agent is one or more of ascorbic acid, citric acid, and tartaric acid.

5. The rapid rare earth concentration detection method according to claim 1, characterized in that: It also includes a standard colorimetric card, and the detection unit consists of multiple units, each filled with a different amount of ethylenediaminetetraacetic acid. The color of the mixture is compared with the standard colorimetric card, and then a suitable detection unit is selected for detection.

6. The rapid rare earth concentration detection method according to claim 1, characterized in that: The detection reagent includes 10 mL of buffer, 0.5-1.5 g of aluminum ion masking powder, 0-1 g of iron ion masking powder, and 0.1-0.15 mL of xylenol orange indicator.

7. The application of a rapid rare earth concentration detection method as described in any one of claims 1-6, characterized in that: The rapid rare earth concentration detection component was applied to detect the rare earth concentration in the leachate of weathered crust leached rare earth ore.

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