A method for simultaneously detecting contents of multiple rare earth elements in vacuum distillation residues of rare earth magnesium alloy

Abstract

The present application relates to rare earth element content detection technical field, disclose a kind of simultaneously detecting the method for the content of multiple rare earth elements in rare earth magnesium alloy vacuum distillation residue, including preparation of sample to be measured, preparation of series standard solution, establishment of standard working curve and sample detection, wherein the preparation process of sample to be measured is dissolved by using dissolution system Rare earth magnesium alloy vacuum distillation residue is dissolved, diluted, to obtain sample to be measured, the dissolution system includes first acid solution and hydrofluoric acid, and the first acid solution is nitric acid and / or hydrochloric acid.The detection method of the present application is simple, suitable for the dissolution of multiple rare earth magnesium alloy vacuum distillation residues, and can simultaneously determine the content of yttrium, neodymium and gadolinium in the sample, with high accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rare earth element content detection, and particularly relates to a method for simultaneously detecting contents of multiple rare earth elements in vacuum distillation residues of rare earth magnesium alloy. BACKGROUND

[0002] Rare earths are widely used in metallurgy, aerospace, cutting-edge technology and other fields due to their unique physical and chemical properties and their status as non-renewable strategic resources. For example, adding yttrium, neodymium and gadolinium to magnesium alloys can strengthen the comprehensive mechanical properties and chemical properties of the magnesium alloys. However, as the production of rare earth magnesium alloys increases, a large amount of waste will also be generated. These wastes are one of the raw material sources for the recycling and secondary use of rare earths. In the vacuum distillation technology in vacuum metallurgy, the rare earth magnesium alloy waste is placed in a horizontal vacuum tube furnace, and under certain temperature and vacuum conditions, magnesium with low saturated vapor pressure volatilizes into a gas phase and condenses into a volatile substance at a low temperature zone, while rare earth elements with higher saturated vapor pressure remain in the liquid phase and cool to form residues, thereby achieving purification of magnesium and enrichment of rare earths. The content of rare earth elements in the volatile substance and the residue is an important basis for evaluating the effect of vacuum distillation. Therefore, rapid and accurate determination of the content of rare earth elements in the residue in the vacuum distillation process plays an important guiding role in the enrichment and recycling of rare earths.

[0003] Currently, in the national standard GB / T 13748.5-2005 "Chemical analysis method for magnesium and magnesium alloy - Determination of yttrium content", the content of yttrium is detected by inductively coupled plasma atomic emission spectrometry after dissolution with hydrochloric acid and hydrogen peroxide (if turbidity is present, 1-2 drops of hydrogen fluoride are added). This national standard method only specifies the determination of yttrium and does not specify the simultaneous determination of the contents of multiple rare earth elements. In the national standard GB / T 114635-2020 "Chemical analysis method for rare earth metals and their compounds - Determination of total amount of rare earths", the oxalate gravimetric method specified in this national standard has a long process, takes a long time, and is relatively complicated to operate. The EDTA titration method is suitable for the titration of the total amount of single rare earth elements (W>99.5%) and heavy rare earth elements, but it does not specify the titration of mixed light, medium and heavy rare earth elements. This national standard can only determine the total amount of rare earths and cannot determine the amounts of individual rare earth elements.

[0004] Therefore, how to provide a method for simultaneously detecting the contents of multiple rare earth elements in vacuum distillation residues of rare earth magnesium alloy is a problem that needs to be solved by those skilled in the art. SUMMARY

[0005] Therefore, the present application provides a method for simultaneously detecting the contents of multiple rare earth elements in vacuum distillation residues of rare earth magnesium alloy, to solve the problem that existing methods can only determine the total amount of rare earths or a certain rare earth element and cannot simultaneously detect the contents of multiple rare earth elements.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for simultaneously detecting the content of multiple rare earth elements in vacuum distillation residues of rare earth magnesium alloys includes the following steps:

[0008] (1) Preparation of the test sample: The vacuum distillation residue of rare earth magnesium alloy was dissolved and diluted using a dissolving system to obtain the test sample for later use;

[0009] (2) Preparation of a series of standard solutions: A series of standard solutions of different concentrations were prepared by using a mixed standard solution of various rare earth elements;

[0010] (3) Establishment of standard working curves: The signal intensity of each rare earth element in the series of standard solutions was detected by inductively coupled plasma atomic emission spectrometry. The signal intensity was used as the vertical axis and the ion concentration was used as the horizontal axis to establish standard working curves.

[0011] (4) Sample detection: The inductively coupled plasma atomic emission spectrometer automatically calculates the content of each rare earth element in the sample to be tested based on the standard working curve.

[0012] The dissolution system described in step (1) includes a first acid solution and hydrofluoric acid, wherein the first acid solution is nitric acid and / or hydrochloric acid.

[0013] Preferably, the ratio of the rare earth magnesium alloy vacuum distillation residue, the first acid solution, and hydrofluoric acid is 0.1000g:(10-25)mL:(0.05-0.15)mL.

[0014] Preferably, the nitric acid is concentrated nitric acid, or the nitric acid is obtained by mixing concentrated nitric acid with an equal volume of water, and the hydrofluoric acid content is ≥40%.

[0015] Preferably, the dissolving system further includes perchloric acid.

[0016] Preferably, in step (1), the acidity of the sample to be tested is maintained at 5-20% by adding an acidic medium during the dilution process.

[0017] Preferably, the acid medium is nitric acid or hydrochloric acid.

[0018] Preferably, the dissolution temperature in step (1) is 100-300℃.

[0019] Preferably, the operating parameters of the inductively coupled plasma atomic emission spectrometer are as follows: power 1000-1200W; auxiliary gas flow rate 0.1-0.3L / min; atomizing gas flow rate 0.5-0.7L / min; cooling gas flow rate 11-13L / min; pump speed 1-2r / s.

[0020] Preferably, the rare earth elements include yttrium, neodymium, and gadolinium.

[0021] This invention provides a method for simultaneously detecting the content of multiple rare earth elements in vacuum distillation residues of rare earth magnesium alloys. By using a suitable dissolution system, the material can be completely dissolved, allowing the metal elements in the material to be completely dissolved out and appear in the test solution in the form of metal ions for easy measurement. Furthermore, the suitable dissolution system provides sufficient excitation and accurate measurement of ICP, while minimizing the measurement interference between elements.

[0022] The detection method of this invention is simple to operate, can rapidly dissolve rare earth residues under normal pressure, and produces a clear solution. Inductively coupled plasma atomic emission spectrometry (ICP-AES) can simultaneously detect the contents of yttrium, neodymium, and gadolinium in the sample. The method of this invention can detect yttrium content in the range of 0.0006-40%, neodymium content in the range of 0.16-80%, and gadolinium content in the range of 0.35-90%. Furthermore, the spiked recoveries of this method are 97.5-99.1% for yttrium, 100.42-104.3% for neodymium, and 99.42-102.82% for gadolinium, indicating that this method has high accuracy and provides a reference for vacuum distillation process parameters. Detailed Implementation

[0023] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0024] This invention proposes a method for simultaneously detecting the content of multiple rare earth elements in vacuum distillation residues of rare earth magnesium alloys, comprising the following steps:

[0025] Step S100. Preparation of the sample to be tested: Dissolve and dilute the vacuum distillation residue of rare earth magnesium alloy using a dissolving system to obtain the sample to be tested, and set aside for later use;

[0026] In this step, the preparation process of the test sample includes three steps: pretreatment, dissolution, and dilution.

[0027] The pretreatment of the sample to be tested can be as follows: the vacuum distillation residue of rare earth magnesium alloy is processed into fragments smaller than 0.5 mm to facilitate more complete dissolution in the subsequent process. The vacuum distillation residue of rare earth magnesium alloy can be obtained by vacuum distillation of rare earth magnesium alloy under vacuum furnace conditions of 10 Pa, 800 °C, and holding for 2 h.

[0028] The sample to be tested can be dissolved as follows: Weigh 0.1000g (accurate to 0.0001g) of the pretreated sample into a beaker, add the dissolving system to the beaker, place the beaker on a 100-300℃ hot plate or a super microwave digester until the sample is completely dissolved and the solution is clear, then remove it and cool it to room temperature; transfer the solution to a 250mL volumetric flask, dilute to the mark with deionized water, shake well, and prepare a blank control solution at the same time.

[0029] Optionally, the dissolution system comprises a first acid solution and hydrofluoric acid in a volume ratio of 10-25:0.05-0.15, and preferably, the volume ratio of the first acid solution and hydrofluoric acid is 16:0.05.

[0030] Optionally, the first acid solution is nitric acid and / or hydrochloric acid, wherein the nitric acid is concentrated nitric acid with a density of 1.42 g / mL, or the nitric acid is obtained by mixing concentrated nitric acid with an equal volume of water (i.e., nitric acid 1+1), and the concentration of the hydrochloric acid is 1.18 g / mL. Preferably, when the first acid solution is nitric acid and hydrochloric acid, the volume ratio of nitric acid to hydrochloric acid is 1-3:3-1.

[0031] Because the reaction between the vacuum distillation residue of rare earth magnesium alloy and concentrated nitric acid produces violent sparks, the solution is prone to splashing out, affecting the accuracy of the measurement results and the safety of operation cannot be guaranteed. Therefore, if the first acid solution is only nitric acid, nitric acid (1+1) should be used to buffer the intensity of the reaction. When the first acid solution is a mixture of nitric acid and hydrochloric acid, hydrochloric acid can be added first. Although the reaction is violent, no sparks will be generated. Therefore, concentrated nitric acid can be added directly after hydrochloric acid.

[0032] Optionally, the hydrofluoric acid content is ≥40%, which is the hydrofluoric acid content indicated on the purchased reagent label.

[0033] Optionally, the dissolving system further includes perchloric acid, and the volume ratio of the perchloric acid to the first acid solution is 0-5:10-25, preferably 3-5:15-20, and more preferably 4:16.

[0034] The dilution of the sample to be tested can be as follows: transfer 5 mL of the dissolved sample to a 100-250 mL volumetric flask, add acid medium to maintain the acidity at 5-20%, preferably 10%, dilute to the mark with deionized water, shake well, and set aside for use.

[0035] Maintaining an acidity of 5-20% is to prevent the hydrolysis of metal ions in the diluent. Acidity affects the viscosity of the solution, which in turn affects the ICP determination process.

[0036] Optionally, the acid medium is nitric acid or hydrochloric acid, preferably the acid solution that is the main acid in the dissolution system.

[0037] Step S200. Preparation of a series of standard solutions: A series of standard solutions of different concentrations are prepared using a mixed standard solution of various rare earth elements;

[0038] In this step, various rare earth elements, including yttrium, neodymium, and gadolinium, are used. Prepare multiple volumetric flasks, for example, four, and sequentially add 0, 1, 5, and 10 mL of a 100 μg / mL mixed standard solution of yttrium, neodymium, and gadolinium to each flask. Make up to volume, shake well, and obtain a series of standard solutions for later use.

[0039] Step S300. Establishment of standard working curve: The signal intensity of each rare earth element in a series of standard solutions was detected by inductively coupled plasma atomic emission spectrometry. The signal intensity was used as the vertical axis and the ion concentration was used as the horizontal axis to establish a standard working curve.

[0040] In this step, the operating parameters of the inductively coupled plasma atomic emission spectrometer are as follows: power 1000-1200W; auxiliary gas flow rate 0.1-0.3L / min; nebulizing gas flow rate 0.5-0.7L / min; cooling gas flow rate 11-13L / min; pump speed 1-2r / s. Preferably, the power is 1100W; auxiliary gas flow rate 0.2L / min; nebulizing gas flow rate 0.6L / min; cooling gas flow rate 12L / min; pump speed 1.5r / s; and the yttrium element analysis spectral line is 371.029nm, the neodymium element analysis spectral line is 430.358nm, and the gadolinium element analysis spectral line is 335.047nm; the correlation coefficients of the standard curve fitting for each element are all ≥0.999.

[0041] Step S400. Sample detection: The inductively coupled plasma atomic emission spectrometer automatically calculates the content of each rare earth element in the sample to be tested according to the standard working curve.

[0042] The present invention will be described below through specific embodiments. Those skilled in the art will understand that the specific embodiments below are merely illustrative and do not limit the scope of the invention in any way. Furthermore, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If specific processing conditions and methods are not explicitly described in the later embodiments, conditions and methods known in the art can be used for processing.

[0043] Prepare four volumetric flasks and add 0, 1, 5, and 10 mL of a 100 μg / mL mixed standard solution of yttrium, neodymium, and gadolinium to each flask sequentially. Make up to volume and shake well before use. Use an inductively coupled plasma atomic emission spectrometer (ICP-AES) (instrument parameters: power 1100W; auxiliary gas flow rate 0.2 L / min; nebulizing gas flow rate 0.6 L / min; cooling gas flow rate 12 L / min; pump speed 1.5 r / s; injection volume 1 mL / min; analytical lines selected: Y371.029, Nd430.358, Gd335.047) to detect the signal intensities of yttrium, neodymium, and gadolinium in the series of standard solutions. Establish a standard curve for the rare earth elements yttrium, neodymium, and gadolinium by plotting signal intensity on the ordinate and ion concentration on the abscissa (Table 1). Measure the blank solution 11 times under the same instrument conditions, calculate the standard deviation, and use three times the standard deviation as the limit of detection.

[0044] Table 1. Linearity and detection limit of the standard working curve of the analyte.

[0045]

[0046]

[0047] In the following examples and comparative examples, samples 1, 2 and 3 are rare earth magnesium alloy residues with different contents of yttrium, neodymium and gadolinium, respectively.

[0048] Example 1

[0049] Weigh 0.1000 g of each of samples 1, 2, and 3 into a polytetrafluoroethylene (PTFE) beaker. Add 16 mL of nitric acid (1+1) and 0.05 mL of hydrofluoric acid to the beaker. Place the beaker on a 280°C hot plate until the samples are completely dissolved and the solution is clear. Remove from the heat and cool to room temperature. Transfer the solutions to a 250 mL volumetric flask and dilute to the mark with deionized water. Shake well to obtain sample solutions 1, 2, and 3.

[0050] Use a pipette to transfer 5 mL of sample solution No. 1 to a 100 mL volumetric flask, and transfer 5 mL of sample solutions No. 2 and No. 3 to 250 mL volumetric flasks respectively. Add nitric acid medium to each of the three volumetric flasks to maintain the acidity at 10%, and dilute to the mark with deionized water and shake well to obtain the test solution. Prepare a blank solution at the same time.

[0051] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to detect the emission intensity signals of rare earth elements in standard samples (instrument parameters: power 1100W; auxiliary gas flow rate 0.2L / min; nebulizing gas flow rate 0.6L / min; cooling gas flow rate 12L / min; pump speed 1.5r / s; injection volume 1mL / min; analytical lines selected: Y371.029, Nd430.358, Gd335.047). A working curve was established with concentration as the x-axis and emission signal intensity as the y-axis, and the correlation coefficient was ≥0.999. The rare earth element content in the samples was then determined. The mass fraction of the analyte was calculated based on the measured concentration. The results are shown in Table 2.

[0052] Table 2 Measurement Results

[0053]

[0054]

[0055] Example 2

[0056] Weigh 0.1000g of each of the three samples (sample 1, sample 2, and sample 3) into a polytetrafluoroethylene beaker. Add 12mL of hydrochloric acid, 4mL of nitric acid, and 0.05mL of hydrofluoric acid to the beaker. Place the beaker on a 280℃ hot plate until the samples are completely dissolved and the solution is clear. Remove the beaker and cool it to room temperature. Transfer the solution to a 250mL volumetric flask and dilute to the mark with deionized water. Shake well to obtain the solutions for sample 1, sample 2, and sample 3.

[0057] Use a pipette to transfer 5 mL of sample solution No. 1 to a 100 mL volumetric flask, and transfer 5 mL of sample solutions No. 2 and No. 3 to 250 mL volumetric flasks respectively. Add hydrochloric acid medium to each of the three volumetric flasks to maintain the acidity at 10%, and dilute to the mark with deionized water and shake well to obtain the test solution. Prepare a blank solution at the same time.

[0058] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to detect the emission intensity signals of rare earth elements in standard samples (instrument parameters: power 1100W; auxiliary gas flow rate 0.2L / min; nebulizing gas flow rate 0.6L / min; cooling gas flow rate 12L / min; pump speed 1.5r / s; injection volume 1mL / min; analytical lines selected: Y371.029, Nd430.358, Gd335.047). A working curve was established with concentration as the x-axis and emission signal intensity as the y-axis, and the correlation coefficient was ≥0.999. The rare earth element content in the samples was then determined. The mass fraction of the analyte was calculated based on the measured concentration. The results are shown in Table 3.

[0059] Table 3 Measurement Results

[0060]

[0061] Example 3

[0062] Weigh 0.1000g of each of the three samples (sample 1, sample 2, and sample 3) into a polytetrafluoroethylene beaker. Add 16mL of nitric acid (1+1), 0.05mL of hydrofluoric acid, and 4mL of perchloric acid to the beaker. Place the beaker on a 280℃ hot plate until the samples are completely dissolved and the solution is clear. Remove the beaker and cool it to room temperature. Transfer the solution to a 250mL volumetric flask and dilute to the mark with deionized water. Shake well to obtain the solutions for sample 1, sample 2, and sample 3.

[0063] Use a pipette to transfer 5 mL of sample solution No. 1 to a 100 mL volumetric flask, and transfer 5 mL of sample solutions No. 2 and No. 3 to 250 mL volumetric flasks respectively. Add nitric acid medium to each of the three volumetric flasks to maintain the acidity at 10%, and dilute to the mark with deionized water and shake well to obtain the test solution. Prepare a blank solution at the same time.

[0064] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to detect the emission intensity signals of rare earth elements in standard samples (instrument parameters: power 1100W; auxiliary gas flow rate 0.2L / min; nebulizing gas flow rate 0.6L / min; cooling gas flow rate 12L / min; pump speed 1.5r / s; injection volume 1mL / min; analytical lines selected: Y371.029, Nd430.358, Gd335.047). A working curve was established with concentration as the x-axis and emission signal intensity as the y-axis, and the correlation coefficient was ≥0.999. The rare earth element content in the samples was then determined. The mass fraction of the analyte was calculated based on the measured concentration. The results are shown in Table 4.

[0065] Table 4 Measurement Results

[0066]

[0067] Example 4

[0068] Weigh 0.1000g of each of the three samples (sample 1, sample 2, and sample 3) into a polytetrafluoroethylene beaker. Add 16mL of nitric acid (1+1) and 0.1mL of hydrofluoric acid to the beaker. Place the beaker on a 280℃ hot plate until the samples are completely dissolved and the solution is clear. Remove the beaker and cool it to room temperature. Transfer the solution to a 250mL volumetric flask and dilute to the mark with deionized water. Shake well to obtain the solutions for sample 1, sample 2, and sample 3.

[0069] Use a pipette to transfer 5 mL of sample solution No. 1 to a 100 mL volumetric flask, and transfer 5 mL of sample solutions No. 2 and No. 3 to 250 mL volumetric flasks respectively. Add nitric acid medium to each of the three volumetric flasks to maintain the acidity at 10%, and dilute to the mark with deionized water and shake well to obtain the test solution. Prepare a blank solution at the same time.

[0070] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to detect the emission intensity signals of rare earth elements in standard samples (instrument parameters: power 1100W; auxiliary gas flow rate 0.2L / min; nebulizing gas flow rate 0.6L / min; cooling gas flow rate 12L / min; pump speed 1.5r / s; injection volume 1mL / min; analytical lines selected: Y371.029, Nd430.358, Gd335.047). A working curve was established with concentration as the x-axis and emission signal intensity as the y-axis, and the correlation coefficient was ≥0.999. The rare earth element content in the samples was then determined. The mass fraction of the analyte was calculated based on the measured concentration. The results are shown in Table 5.

[0071] Table 5. Measurement Results

[0072]

[0073] Example 5

[0074] Weigh 0.1000g of each of the three samples (sample 1, sample 2, and sample 3) into a polytetrafluoroethylene beaker. Add 16mL of nitric acid (1+1) and 0.15mL of hydrofluoric acid to the beaker. Place the beaker on a 280℃ hot plate until the samples are completely dissolved and the solution is clear. Remove the beaker and cool it to room temperature. Transfer the solution to a 250mL volumetric flask and dilute to the mark with deionized water. Shake well to obtain the solutions for sample 1, sample 2, and sample 3.

[0075] Use a pipette to transfer 5 mL of sample solution No. 1 to a 100 mL volumetric flask, and transfer 5 mL of sample solutions No. 2 and No. 3 to 250 mL volumetric flasks respectively. Add nitric acid medium to each of the three volumetric flasks to maintain the acidity at 10%, and dilute to the mark with deionized water and shake well to obtain the test solution. Prepare a blank solution at the same time.

[0076] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to detect the emission intensity signals of rare earth elements in standard samples (instrument parameters: power 1100W; auxiliary gas flow rate 0.2L / min; nebulizing gas flow rate 0.6L / min; cooling gas flow rate 12L / min; pump speed 1.5r / s; injection volume 1mL / min; analytical lines selected: Y371.029, Nd430.358, Gd335.047). A working curve was established with concentration as the x-axis and emission signal intensity as the y-axis, and the correlation coefficient was ≥0.999. The rare earth element content in the samples was then determined. The mass fraction of the analyte was calculated based on the measured concentration. The results are shown in Table 6.

[0077] Table 6 Measurement Results

[0078]

[0079] Example 6

[0080] Weigh 0.1000g of each of the three samples (sample 1, sample 2, and sample 3) into a polytetrafluoroethylene beaker. Add 16mL of nitric acid (1+1) and 0.05mL of hydrofluoric acid to the beaker. Place the beaker on a 280℃ hot plate until the samples are completely dissolved and the solution is clear. Remove the beaker and cool it to room temperature. Transfer the solution to a 250mL volumetric flask and dilute to the mark with deionized water. Shake well to obtain the solutions for sample 1, sample 2, and sample 3.

[0081] Use a pipette to transfer 5 mL of sample solution No. 1 to a 100 mL volumetric flask, and transfer 5 mL of sample solutions No. 2 and No. 3 to 250 mL volumetric flasks respectively. Add nitric acid medium to each of the three volumetric flasks to maintain the acidity at 10%, and dilute to the mark with deionized water and shake well to obtain the test solution. Prepare a blank solution at the same time.

[0082] The emission intensity signals of rare earth elements in standard samples were detected using an inductively coupled plasma atomic emission spectrometer (instrument operating parameters: power 1100W; auxiliary gas flow rate 0.2L / min; nebulizing gas flow rate 0.6L / min; cooling gas flow rate 12L / min; pump speed 1.5r / s; injection volume 1mL / min; analytical lines selected: Y371.029, Nd430.358, Gd335.047). A working curve was established with concentration as the abscissa and emission signal intensity as the ordinate, and the correlation coefficient was ≥0.999. The rare earth element content in the samples was then determined.

[0083] The spiked recovery experiment was carried out on the sample according to the above scheme. The measured values, spiked amounts and spiked recovery rates are shown in Table 7.

[0084] Table 7 Measurement Results

[0085]

[0086] The calculated spiked recovery rate meets the deviation range of the method recovery rate in the national standard GB / T 27417-2017.

[0087] Comparative Example 1

[0088] Weigh 0.1000g of each of the three samples (sample 1, sample 2, and sample 3) into a polytetrafluoroethylene beaker. Add 16mL of nitric acid (1+1) and 0.25mL of hydrofluoric acid to the beaker. Place the beaker on a 280℃ hot plate until the samples are completely dissolved and the solution is clear. Remove the beaker and cool it to room temperature. Transfer the solution to a 250mL volumetric flask and dilute to the mark with deionized water. Shake well to obtain the solutions for sample 1, sample 2, and sample 3.

[0089] Use a pipette to transfer 5 mL of sample solution No. 1 to a 100 mL volumetric flask, and transfer 5 mL of sample solutions No. 2 and No. 3 to 250 mL volumetric flasks respectively. Add nitric acid medium to each of the three volumetric flasks to maintain the acidity at 10%, and dilute to the mark with deionized water and shake well to obtain the test solution. Prepare a blank solution at the same time.

[0090] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to detect the emission intensity signals of rare earth elements in standard samples (instrument parameters: power 1100W; auxiliary gas flow rate 0.2L / min; nebulizing gas flow rate 0.6L / min; cooling gas flow rate 12L / min; pump speed 1.5r / s; injection volume 1mL / min; analytical lines selected: Y371.029, Nd430.358, Gd335.047). A working curve was established with concentration as the x-axis and emission signal intensity as the y-axis, and the correlation coefficient was ≥0.999. The rare earth element content in the samples was then determined. The mass fraction of the analyte was calculated based on the measured concentration. The results are shown in Table 8.

[0091] Table 8 Measurement Results

[0092]

[0093] Comparative Example 2

[0094] Weigh 0.1000g of each of the three samples (sample 1, sample 2, and sample 3) into a polytetrafluoroethylene beaker. Add 16mL of hydrochloric acid to the beaker and place it on a 280℃ hot plate until the samples are completely dissolved. Remove the beaker and cool it to room temperature. Transfer the solutions to a 250mL volumetric flask and dilute to the mark with deionized water. Shake well to obtain the solutions of sample 1, sample 2, and sample 3.

[0095] Use a pipette to transfer 5 mL of sample solution No. 1 to a 100 mL volumetric flask, and transfer 5 mL of sample solutions No. 2 and No. 3 to 250 mL volumetric flasks respectively. Add hydrochloric acid medium to each of the three volumetric flasks to maintain the acidity at 10%, and dilute to the mark with deionized water and shake well to obtain the test solution. Prepare a blank solution at the same time.

[0096] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to detect the emission intensity signals of rare earth elements in standard samples (instrument parameters: power 1100W; auxiliary gas flow rate 0.2L / min; nebulizing gas flow rate 0.6L / min; cooling gas flow rate 12L / min; pump speed 1.5r / s; injection volume 1mL / min; analytical lines selected: Y371.029, Nd430.358, Gd335.047). A working curve was established with concentration on the x-axis and emission signal intensity on the y-axis, and the correlation coefficient was ≥0.999. The rare earth element content in the samples was then determined. The mass fraction of the analyte was calculated based on the measured concentration. The results are shown in Table 9.

[0097] Table 9 Measurement Results

[0098]

[0099] Comparative Example 3

[0100] Weigh 0.1000g of each of the three samples (sample 1, sample 2, and sample 3) into a polytetrafluoroethylene beaker. Add 16mL of nitric acid (1+1) to the beaker and place it on a 280℃ hot plate until the samples are completely dissolved. Remove the beaker and cool it to room temperature. Transfer the solutions to a 250mL volumetric flask and dilute to the mark with deionized water. Shake well to obtain the solutions of sample 1, sample 2, and sample 3.

[0101] Use a pipette to transfer 5 mL of sample solution No. 1 to a 100 mL volumetric flask, and transfer 5 mL of sample solutions No. 2 and No. 3 to 250 mL volumetric flasks respectively. Add nitric acid medium to each of the three volumetric flasks to maintain the acidity at 10%, and dilute to the mark with deionized water and shake well to obtain the test solution. Prepare a blank solution at the same time.

[0102] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to detect the emission intensity signals of rare earth elements in standard samples (instrument parameters: power 1100W; auxiliary gas flow rate 0.2L / min; nebulizing gas flow rate 0.6L / min; cooling gas flow rate 12L / min; pump speed 1.5r / s; injection volume 1mL / min; analytical lines selected: Y371.029, Nd430.358, Gd335.047). A working curve was established with concentration as the x-axis and emission signal intensity as the y-axis, and the correlation coefficient was ≥0.999. The rare earth element content in the samples was then determined. The mass fraction of the analyte was calculated based on the measured concentration. The results are shown in Table 10.

[0103] Table 10 Measurement Results

[0104]

[0105] Comparative Example 4

[0106] Weigh 0.1000g of each of the three samples (sample 1, sample 2, and sample 3) into a polytetrafluoroethylene beaker. Add 12mL of hydrochloric acid and 4mL of nitric acid to the beaker. Place the beaker on a 280℃ hot plate until the samples are completely dissolved. Remove the beaker and cool it to room temperature. Transfer the solutions to a 250mL volumetric flask and dilute to the mark with deionized water. Shake well to obtain the solutions of sample 1, sample 2, and sample 3.

[0107] Use a pipette to transfer 5 mL of sample solution No. 1 to a 100 mL volumetric flask, and transfer 5 mL of sample solutions No. 2 and No. 3 to 250 mL volumetric flasks respectively. Add hydrochloric acid medium to each of the three volumetric flasks to maintain the acidity at 10%, and dilute to the mark with deionized water and shake well to obtain the test solution. Prepare a blank solution at the same time.

[0108] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to detect the emission intensity signals of rare earth elements in standard samples (instrument parameters: power 1100W; auxiliary gas flow rate 0.2L / min; nebulizing gas flow rate 0.6L / min; cooling gas flow rate 12L / min; pump speed 1.5r / s; injection volume 1mL / min; analytical lines selected: Y371.029, Nd430.358, Gd335.047). A working curve was established with concentration as the x-axis and emission signal intensity as the y-axis, and the correlation coefficient was ≥0.999. The rare earth element content in the samples was then determined. The mass fraction of the analyte was calculated based on the measured concentration. The results are shown in Table 11.

[0109] Table 11 Measurement Results

[0110]

[0111] Comparative Example 5

[0112] Weigh 0.1000g of each of the three samples (sample 1, sample 2, and sample 3) into a polytetrafluoroethylene beaker. Add 12mL of hydrochloric acid and 4mL of perchloric acid to the beaker. Place the beaker on a 280℃ hot plate until the samples are completely dissolved. Remove the beaker and cool it to room temperature. Transfer the solutions to a 250mL volumetric flask and dilute to the mark with deionized water. Shake well to obtain the solutions of sample 1, sample 2, and sample 3.

[0113] Use a pipette to transfer 5 mL of sample solution No. 1 to a 100 mL volumetric flask, and transfer 5 mL of sample solutions No. 2 and No. 3 to 250 mL volumetric flasks respectively. Add hydrochloric acid medium to each of the three volumetric flasks to maintain the acidity at 10%, and dilute to the mark with deionized water and shake well to obtain the test solution. Prepare a blank solution at the same time.

[0114] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to detect the emission intensity signals of rare earth elements in standard samples (instrument parameters: power 1100W; auxiliary gas flow rate 0.2L / min; nebulizing gas flow rate 0.6L / min; cooling gas flow rate 12L / min; pump speed 1.5r / s; injection volume 1mL / min; analytical lines selected: Y371.029, Nd430.358, Gd335.047). A working curve was established with concentration as the x-axis and emission signal intensity as the y-axis, and the correlation coefficient was ≥0.999. The rare earth element content in the samples was then determined. The mass fraction of the analyte was calculated based on the measured concentration. The results are shown in Table 12.

[0115] Table 12 Measurement Results

[0116]

[0117] Comparative Example 6

[0118] Weigh 0.1000g of each of the three samples (sample 1, sample 2, and sample 3) into a polytetrafluoroethylene beaker. Add 12mL of nitric acid (1+1) and 4mL of perchloric acid to the beaker. Place the beaker on a 280℃ hot plate until the samples are completely dissolved. Remove the beaker and cool it to room temperature. Transfer the solutions to a 250mL volumetric flask and dilute to the mark with deionized water. Shake well to obtain the solutions of sample 1, sample 2, and sample 3.

[0119] Use a pipette to transfer 5 mL of sample solution No. 1 to a 100 mL volumetric flask, and transfer 5 mL of sample solutions No. 2 and No. 3 to 250 mL volumetric flasks respectively. Add nitric acid medium to each of the three volumetric flasks to maintain the acidity at 10%, and dilute to the mark with deionized water and shake well to obtain the test solution. Prepare a blank solution at the same time.

[0120] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to detect the emission intensity signals of rare earth elements in standard samples (instrument parameters: power 1100W; auxiliary gas flow rate 0.2L / min; nebulizing gas flow rate 0.6L / min; cooling gas flow rate 12L / min; pump speed 1.5r / s; injection volume 1mL / min; analytical lines selected: Y371.029, Nd430.358, Gd335.047). A working curve was established with concentration as the x-axis and emission signal intensity as the y-axis, and the correlation coefficient was ≥0.999. The rare earth element content in the samples was then determined. The mass fraction of the analyte was calculated based on the measured concentration. The results are shown in Table 13.

[0121] Table 13 Measurement Results

[0122]

[0123]

[0124] Comparative Example 7

[0125] Weigh 0.1000g of each of the three samples (sample 1, sample 2, and sample 3) into a polytetrafluoroethylene beaker. Add 12mL of hydrochloric acid, 4mL of nitric acid, and 4mL of perchloric acid to the beaker. Place the beaker on a 280℃ hot plate until the samples are completely dissolved. Remove the beaker and cool it to room temperature. Transfer the solutions to a 250mL volumetric flask and dilute to the mark with deionized water. Shake well to obtain the solutions of sample 1, sample 2, and sample 3.

[0126] Use a pipette to transfer 5 mL of sample solution No. 1 to a 100 mL volumetric flask, and transfer 5 mL of sample solutions No. 2 and No. 3 to 250 mL volumetric flasks respectively. Add hydrochloric acid medium to each of the three volumetric flasks to maintain the acidity at 10%, and dilute to the mark with deionized water and shake well to obtain the test solution. Prepare a blank solution at the same time.

[0127] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to detect the emission intensity signals of rare earth elements in standard samples (instrument parameters: power 1100W; auxiliary gas flow rate 0.2L / min; nebulizing gas flow rate 0.6L / min; cooling gas flow rate 12L / min; pump speed 1.5r / s; injection volume 1mL / min; analytical lines selected: Y371.029, Nd430.358, Gd335.047). A working curve was established with concentration as the x-axis and emission signal intensity as the y-axis, and the correlation coefficient was ≥0.999. The rare earth element content in the samples was then determined. The mass fraction of the analyte was calculated based on the measured concentration. The results are shown in Table 14.

[0128] Table 14 Measurement Results

[0129]

[0130] As can be seen from Comparative Examples 1-7, if hydrofluoric acid is not added to the dissolution system or if too much hydrofluoric acid is added, the degree of sample dissolution and the detection results of the content of each rare earth element will be lower.

[0131] Comparative Example 8

[0132] The sample in this invention was dissolved and determined using the method of GB / T 13748.5-2005 "Chemical Analysis Methods for Magnesium and Magnesium Alloys - Determination of Yttrium Content" in the national standard GB / T 13748.5-2005, with hydrochloric acid and hydrogen peroxide (1-2 drops of hydrogen fluoride were added if there was turbidity) as the solution system in the national standard.

[0133] Weigh 0.1000g of each of the three samples (sample 1, sample 2, and sample 3) into a polytetrafluoroethylene beaker. Add 20mL of hydrochloric acid (1+1), 5 drops of hydrogen peroxide, and 1 drop of hydrogen fluoride to the beaker. Place the beaker on a 280℃ hot plate until the samples are completely dissolved. Remove the beaker and cool it to room temperature. Transfer the solutions to a 250mL volumetric flask and dilute to the mark with deionized water. Shake well to obtain the solutions of sample 1, sample 2, and sample 3.

[0134] Use a pipette to transfer 5 mL of sample solution No. 1 to a 100 mL volumetric flask, and transfer 5 mL of sample solutions No. 2 and No. 3 to 250 mL volumetric flasks respectively. Add hydrochloric acid medium to each of the three volumetric flasks to maintain the acidity at 10%, and dilute to the mark with deionized water and shake well to obtain the test solution. Prepare a blank solution at the same time.

[0135] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to detect the emission intensity signals of rare earth elements in standard samples (instrument parameters: power 1100W; auxiliary gas flow rate 0.2L / min; nebulizing gas flow rate 0.6L / min; cooling gas flow rate 12L / min; pump speed 1.5r / s; injection volume 1mL / min; analytical lines selected: Y371.029, Nd430.358, Gd335.047). A working curve was established with concentration as the x-axis and emission signal intensity as the y-axis, and the correlation coefficient was ≥0.999. The rare earth element content in the samples was then determined. The mass fraction of the analyte was calculated based on the measured concentration. The results are shown in Table 15.

[0136] Table 15 Measurement Results

[0137]

[0138]

[0139] As can be seen from Comparative Example 8, if the national standard method is used to determine the dissolution of the samples in this invention, it will affect the degree of dissolution of some samples and the detection results of the content of some rare earth elements will be lower, and it will not be possible to effectively detect the content of yttrium, neodymium and gadolinium in the vacuum distillation residue of rare earth magnesium alloy.

[0140] In summary, this invention provides a method for simultaneously detecting the content of multiple rare earth elements in vacuum distillation residues of rare earth magnesium alloys. This detection method has a simple procedure, is applicable to the dissolution of various rare earth magnesium alloy vacuum distillation residues, and can simultaneously determine the content of yttrium, neodymium, and gadolinium in the sample with high accuracy.

[0141] In the description of this specification, the terms "one embodiment," "another embodiment," "yet another embodiment," "some embodiments," "some specific embodiments," "other specific embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment, which are included in at least one embodiment of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples, without contradiction. Additionally, it should be noted that in this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0142] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for simultaneously detecting the content of multiple rare earth elements in vacuum distillation residues of rare earth magnesium alloys, characterized in that, The method comprises the following steps: (1) Preparation of the sample to be tested: dissolving and diluting the vacuum distillation residue of a rare earth magnesium alloy by using a dissolving system to obtain a sample to be tested for standby; (2) Preparation of a series of standard solutions: preparing a series of standard solutions with different concentrations by using a mixed standard solution of multiple rare earth elements; (3) Establishment of a standard working curve: detecting the signal intensity of each rare earth element in the series of standard solutions by using an inductively coupled plasma atomic emission spectrometer, taking the signal intensity as the ordinate and the ion concentration as the abscissa to establish a standard working curve; (4) Sample detection: automatically calculating the content of each rare earth element in the sample to be tested according to the standard working curve by using the inductively coupled plasma atomic emission spectrometer; The dissolving system in step (1) comprises a first acid solution and hydrofluoric acid, the first acid solution is nitric acid and / or hydrochloric acid; the ratio of the vacuum distillation residue of the rare earth magnesium alloy, the first acid solution and the hydrofluoric acid is 0.1000g:(10-25)mL:(0.05-0.15)mL; The nitric acid is concentrated nitric acid with a density of 1.42g / mL, or the nitric acid is obtained by mixing concentrated nitric acid with the same volume of water, and the concentration of the hydrochloric acid is 1.18g / mL, when the first acid solution is nitric acid and hydrochloric acid, the volume ratio of nitric acid to hydrochloric acid is 1-3:3-1; The content of the hydrofluoric acid is ≥40%; The multiple rare earth elements comprise yttrium, neodymium and gadolinium.

2. The method of claim 1, wherein, The dissolving system further comprises perchloric acid.

3. The method of claim 1, wherein, During the dilution process in step (1), the acidity of the sample to be tested is maintained at 5-20% by adding an acid medium.

4. The method of claim 3, wherein, The acid medium is nitric acid or hydrochloric acid.

5. The method of claim 1, wherein, The dissolving temperature in step (1) is 100-300℃.

6. The method of claim 1, wherein, The working parameters of the inductively coupled plasma atomic emission spectrometer are as follows: power 1000-1200W; auxiliary gas flow rate 0.1-0.3L / min; atomizing gas flow rate 0.5-0.7L / min; cooling gas flow rate 11-13L / min; Pump speed 1-2r / s.

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