Method for determining tungsten impurity content in molybdenum powder by adopting ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometer)

Abstract

The invention relates to the field of chemical analysis and detection, and particularly discloses a method for determining the content of tungsten impurities in molybdenum powder by adopting ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer), which comprises the following steps: S1, preparing a standard solution; s2, preparing a solution to be detected; s3, drawing a standard curve: introducing the series of standard solutions into ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer) equipment, setting optimal parameters of the ICP-OES equipment according to the standard solutions, selecting 2-5 wavelengths for detecting corresponding tungsten elements, and measuring the strength of the tungsten elements in the series of standard solutions to obtain a standard solution curve; s4, judging: if the correlation coefficient of the standard curve is superior to 0.999, starting to measure the to-be-measured sample solution according to the method in the step S2; if the correlation coefficient of the standard curve is inferior to 0.999, a standard curve solution needs to be prepared again; and S5, detecting the to-be-detected solution, and automatically giving the mass concentration of tungsten in the to-be-detected sample through the standard curve computer. The invention provides a method for rapidly dissolving a sample, and by adding ammonium molybdate and labeling, the ICP-OES detection result is higher in accuracy and better in stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical analysis and detection, and particularly relates to a method for determining the content of tungsten impurities in molybdenum powder by ICP-OES. BACKGROUND

[0002] Metal molybdenum and its alloy material have the advantages of high melting point, high strength, high hardness, excellent wear resistance, thermal and electrical conductivity, corrosion resistance, thermal shock resistance, small expansion coefficient, good formability, specific strength, small thermal neutron absorption cross section, high endurance strength and the like, and are widely used in the fields of steel, electronics and electrical appliances, metal processing, aerospace, nuclear industry and the like. With the rapid development of high-tech, higher requirements are put forward for the performance of molybdenum and molybdenum alloy, and molybdenum powder is the main raw material for producing molybdenum and molybdenum alloy, and the quality of molybdenum powder directly affects the performance of molybdenum and molybdenum alloy material, so the analysis and detection requirements for the element content in molybdenum powder are higher and higher in the production process of molybdenum products. At present, the analysis method commonly used for the tungsten element in molybdenum powder is spectrophotometric colorimetry, which is complex and has a long analysis time, and cannot meet the requirements of the production line. SUMMARY

[0003] The present application provides a method for rapidly dissolving molybdenum powder and rapidly determining the content of tungsten impurities by ICP-OES, which can well meet the requirements of large-scale production analysis and testing.

[0004] The purpose of the present application is achieved by the following technical solutions:

[0005] A method for determining the content of tungsten impurities in molybdenum powder by ICP-OES, comprising the following steps:

[0006] S1, preparing a standard solution: adding ammonium molybdate equivalent to the molybdenum matrix in the sample to prepare five mass concentrations of tungsten standard solution;

[0007] S2, preparing a solution to be measured: dissolving the molybdenum powder sample in concentrated nitric acid and concentrated hydrochloric acid, and diluting with water to obtain a solution to be measured;

[0008] S3, drawing a standard curve: introducing the series of standard solutions into the ICP-OES equipment, setting the optimal parameters of the ICP-OES equipment according to the standard solution, selecting 2-5 wavelengths for detecting the tungsten element, measuring the intensity of the tungsten element in the series of standard solutions, and obtaining the standard solution curve;

[0009] S4, determining, if the correlation coefficient of the standard curve is better than 0.999, starting to measure the sample solution to be measured according to the method of step S2; if the correlation coefficient of the standard curve is worse than 0.999, the standard curve solution needs to be reconfigured;

[0010] S5, detecting the solution to be measured, and automatically giving the mass concentration of tungsten in the sample to be measured by the standard curve computer.

[0011] Preferably, the purity of the ammonium molybdate used in the preparation of the tungsten standard solution in step S1 is 99.9%.

[0012] Preferably, the tungsten standard solution in step S1 is GNM-SW-002-2013 tungsten single-element standard solution.

[0013] Preferably, the five mass concentrations in step S1 are 0 mg / L, 0.1 mg / L, 0.5 mg / L, 2.5 mg / L and 6.25 mg / L, respectively.

[0014] Preferably, in step S2, 3 mL of concentrated nitric acid and 1 mL of concentrated hydrochloric acid are added to 0.1 g of molybdenum powder, and then diluted with high-purity water to 50 mL.

[0015] Preferably, in step S2, the mass concentration of the concentrated nitric acid is 65%, and the mass concentration of the concentrated hydrochloric acid is 36%-38%.

[0016] Preferably, the detection wavelength used in step S3 is 209.475 nm, 239.709 nm or 224.875 nm.

[0017] Preferably, the detection wavelength used in step S3 is 209.475 nm.

[0018] The present application has the following beneficial effects:

[0019] The present application uses inductively coupled plasma atomic emission spectrometry, selects a specific wavelength, and uses a standard addition method to ensure the stability and accuracy of the analysis, reduce the interference of molybdenum in the analysis process, and is fast, simple, and suitable for quality detection of molybdenum powder and molybdenum products on site, with higher accuracy and better stability of the detection results.

[0020] 1. The method provided by the present application effectively reduces the detection error and has poor repeatability.

[0021] 2. The method of the present application selects a suitable solvent ratio to dissolve molybdenum powder, which is simple, fast, complete, safe, environmentally friendly and fast.

[0022] 3. The present application uses inductively coupled plasma emission spectrometry for detection, which has the advantages of good stability and high sensitivity.

[0023] 4. The present application reduces the interference of molybdenum in the analysis process, and makes a technical breakthrough for the production and detection of molybdenum powder and molybdenum products. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, not all.

[0025] The instruments, reagents, and raw materials used in the following implementation, without special instructions, can be purchased through commercial channels.

[0026] Instrument and working condition: inductively coupled plasma atomic emission spectrometer (Thermo Fisher ICAP7000); full-fixed structure with two-dimensional cross dispersion system of middle-order grating and prism; 27.12 MHz solid-state radio frequency generator; quartz tube as a matrix tube, concentric glass atomizer, glass cyclone atomizing chamber, detachable EMT torch device; plasma gas flow is 0.2 mL / min, atomizer flow is 0.5 L / min, cooling gas flow rate is 1 L / min, peristaltic pump speed is 45 rpm, and 2% nitric acid solution is selected as the eluent gradient setting time.

[0027] Example 1

[0028] The method for determining the tungsten impurity content in molybdenum powder by ICP-OES in this embodiment includes the following steps:

[0029] (1) Pretreatment of the sample to be tested: accurately weigh 0.1 g of molybdenum powder sample into a 100 mL beaker, add 3 mL of concentrated nitric acid and 1 mL of concentrated hydrochloric acid in sequence for dissolution, and dilute with first-grade water to 50 g to make the sample completely dissolved, obtaining sample 1.

[0030] (2) Preparation of standard solution: weigh 0.4 g of ammonium molybdate into a 500 mL beaker, add first-grade water to 200 g for dissolution, obtaining an ammonium molybdate standby solution; respectively weigh 0.0 g, 0.0581 g, 0.2526 g, 1.2543 g, and 3.1253 g of tungsten single-element standard solution with a concentration of 100 μg / mL into clean sampling tubes, and dilute to 50 g, 50.0405 g, 50.0044 g, 50.0134 g, and 50.0045 g with the ammonium molybdate standby solution, respectively, obtaining four gradient standard solutions with concentrations of 0.000 mg / L, 0.1161 mg / L, 0.5026 mg / L, 2.5079 mg / L, and 6.2500 mg / L.

[0031] (3) Preparation of standard addition recovery sample: accurately weigh 0.1 g of molybdenum powder sample into a 100 mL beaker, add 3 mL of concentrated nitric acid and 1 mL of concentrated hydrochloric acid in sequence for dissolution, and repeat this step 7 times. In the form of adding standard solution, 0.02 g of tungsten single-element standard solution with a concentration of 100 μg / mL is added to each beaker, and first-grade water is added for dilution to 50 g (the actual preparation of the standard addition solution has a concentration of 0.0407 μg / mL), obtaining 7 standard addition samples.

[0032] (4) Standard curve drawing: After the ICP-OES instrument was stabilized, four tungsten element standard solutions with concentrations of 0.000 mg / L, 0.1161 mg / L, 0.5026 mg / L, 2.5079 mg / L and 6.2503 mg / L were sequentially injected to draw the standard curve of the tungsten metal element, and the standard curve equation was Y = 1286.29X + 246.34; the correlation coefficient was 0.9998.

[0033] (5) Sample detection: Under the selected instrument conditions, sample 1 was injected, and sample 1 was detected in parallel for 7 times. The content of tungsten metal impurities in sample 1 was directly calculated by the instrument according to the excitation light intensity, and the relative standard deviation was calculated. The 7 standard addition samples were detected, and the standard addition recovery rate was calculated.

[0034] (6) Experimental results: The content of metal impurities in sample 1 is shown in Table 1, and the relative standard deviation (RSD) of 7 repeated measurements is less than 3%, and the repeatability is good; through the detection of 7 standard addition samples, it is calculated that the standard addition recovery rate of tungsten metal element meets 60%-120% of GB / T 27417-2017. The present application is further described in detail below in combination with Table 1.

[0035] Table 1 Content of tungsten impurities in sample 1

[0036]

[0037] Example 2

[0038] A method for determining the content of tungsten impurities in molybdenum powder by ICP-OES in the present embodiment includes the following steps:

[0039] (1) Pretreatment of sample to be tested: 0.1 g of molybdenum powder sample was accurately weighed by an electronic balance and placed in a 100 mL beaker, 3 mL of concentrated nitric acid and 1 mL of concentrated hydrochloric acid were sequentially added and dissolved, and the sample was completely dissolved by dilution with first-grade water to 50 g to obtain sample 2.

[0040] (2) Preparation of standard solution: 0.4 g of ammonium molybdate was weighed and placed in a 500 mL beaker, and first-grade water was added to 200 g to dissolve and obtain an ammonium molybdate standby solution; 0.0 g, 0.0581 g, 0.2526 g, 1.2543 g and 3.1253 g of tungsten single-element standard solution with a concentration of 100 μg / mL were respectively transferred to a clean sampling tube, and the ammonium molybdate standby solution was diluted to 50 g, 50.0405 g, 50.0044 g, 50.0134 g and 50.0045 g, respectively, to obtain four gradient standard solutions with concentrations of 0.000 mg / L, 0.1161 mg / L, 0.5026 mg / L, 2.5079 mg / L and 6.2500 mg / L.

[0041] (3) Spiked recovery sample preparation: 0.1 g of molybdenum powder sample was accurately weighed into a 100 mL beaker, 3 mL of concentrated nitric acid and 1 mL of concentrated hydrochloric acid were added in turn for dissolution, and this step was repeated 7 times. In the form of added standard solution, 0.01 g of tungsten single-element standard solution with a concentration of 100 μg / mL was added to each beaker, and water was added to dilute to 50 g (the actual preparation of the spiked solution concentration was 0.0112 μg / mL), obtaining 7 spiked samples.

[0042] (4) Preparation of standard curve: After the ICP-OES instrument was stabilized, four tungsten element standard solutions with concentrations of 0.000 mg / L, 0.1161 mg / L, 0.5026 mg / L, 2.5079 mg / L and 6.2503 mg / L were sequentially injected to draw the standard curve of the tungsten metal element, and the standard curve equation was Y = 434.84X + 294.73; the correlation coefficient was 0.9998.

[0043] (5) Sample detection: Under the selected instrument conditions, sample 2 was injected, and sample 2 was detected in parallel for 7 times, and the content of tungsten metal impurities in sample 1 was directly calculated by the instrument according to the excitation light intensity, and the relative standard deviation was calculated; the 7 spiked samples were detected, and the spiked recovery rate was calculated.

[0044] (6) Experimental results: The content of metal impurities in sample 2 is shown in Table 2, and the relative standard deviation (RSD) of 7 repeated measurements is less than 3%, and the repeatability is good; through the detection of 7 spiked samples, it is calculated that the spiked recovery rate of tungsten metal element meets 60%-120% of GB / T 27417-2017. The present application is further described in detail in combination with Table 2.

[0045] Table 2 Tungsten impurity content in sample 2

[0046]

[0047]

[0048] Example 3

[0049] A method for determining the content of tungsten impurities in molybdenum powder by ICP-OES in the present embodiment includes the following steps:

[0050] (1) Pretreatment of sample to be tested: 0.1 g of molybdenum powder sample was accurately weighed into a 100 mL beaker, 3 mL of concentrated nitric acid and 1 mL of concentrated hydrochloric acid were added in turn for dissolution, and water was added to dilute to 50 g, so that the sample was completely dissolved, obtaining sample 3.

[0051] (2) Standard solution preparation: 0.4 g of ammonium molybdate was weighed into a 500 mL beaker, and first-grade water was added to 200 g to dissolve, obtaining an ammonium molybdate standby solution; 0.0 g, 0.0581 g, 0.2526 g, 1.2543 g, and 3.1253 g of tungsten single-element standard solution with a concentration of 100 μg / mL were weighed into clean sampling tubes, respectively, and diluted with the ammonium molybdate standby solution to 50 g, 50.0405 g, 50.0044 g, 50.0134 g, and 50.0045 g, respectively, obtaining four gradient standard solutions with concentrations of 0.000 mg / L, 0.1161 mg / L, 0.5026 mg / L, 2.5079 mg / L, and 6.2500 mg / L.

[0052] (3) Sample preparation for standard addition recovery rate: 0.1 g of molybdenum powder sample was accurately weighed into a 100 mL beaker with an electronic balance, and 3 mL of concentrated nitric acid and 1 mL of concentrated hydrochloric acid were added in turn to dissolve, and this step was repeated 7 times. In the form of added standard solution, 0.05 g of tungsten single-element standard solution with a concentration of 100 μg / mL was added to each beaker, and first-grade water was added to dilute to 50 g (the actual preparation of the standard addition solution has a concentration of 0.1007 μg / mL), obtaining 7 standard addition samples.

[0053] (4) Standard curve drawing: After the ICP-OES instrument was stabilized, four tungsten element standard solutions with concentrations of 0.000 mg / L, 0.1161 mg / L, 0.5026 mg / L, 2.5079 mg / L, and 6.2503 mg / L were sequentially sampled to draw a standard curve of the tungsten metal element, and the standard curve equation was Y=268.71X+191.44; the correlation coefficient was 0.9999.

[0054] (5) Sample detection: Under the selected instrument conditions, sample 3 was sampled, and sample 3 was detected in parallel for 7 times, and the content of tungsten metal impurities in sample 3 was directly calculated by the instrument according to the excitation light intensity, and the relative standard deviation was calculated; the 7 standard addition samples were detected, and the standard addition recovery rate was calculated.

[0055] (6) Experimental results: The content of metal impurities in sample 1 is shown in Table 3, and the relative standard deviation (RSD) of 7 repeated measurements is less than 3%, and the repeatability is good; through the detection of the 7 standard addition samples, it is calculated that the standard addition recovery rate of the tungsten metal element meets 60%-120% of GB / T 27417-2017. The present application is further described in detail in combination with Table 3.

[0056] Table 3 Tungsten impurity content in sample 3

[0057]

[0058] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical solution and inventive concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for determining the tungsten impurity content in molybdenum powder using ICP-OES, characterized in that: Includes the following steps: S1. Preparation of standard solutions: Prepare five tungsten standard solutions with mass concentrations by adding ammonium molybdate equivalent to the molybdenum matrix in the sample. S2. Preparation of the test solution: Dissolve the molybdenum powder sample in concentrated nitric acid and concentrated hydrochloric acid, and dilute with water to obtain the test solution. S3. Plotting the standard curve: Introduce a series of standard solutions into the ICP-OES equipment, set the optimal parameters of the ICP-OES equipment according to the standard solutions, select 2-5 wavelengths for detecting the corresponding tungsten element, measure the intensity of the tungsten element in the series of standard solutions, and obtain the standard solution curve. S4. If the correlation coefficient of the standard curve is better than 0.999, start measuring the sample solution to be tested according to the method in step S2; if the correlation coefficient of the standard curve is worse than 0.999, the standard curve solution needs to be re-prepared. S5. Detect the solution to be tested, and the computer will automatically give the mass concentration of tungsten in the sample through the standard curve.

2. The method for determining the tungsten impurity content in molybdenum powder using ICP-OES according to claim 1, characterized in that: The ammonium molybdate used in step S1 to prepare the tungsten standard solution has a purity of 99.9%.

3. The method for determining the tungsten impurity content in molybdenum powder using ICP-OES according to claim 1, characterized in that: The tungsten standard solution in step S1 is GNM-SW-002-2013 tungsten single-element standard solution.

4. The method for determining the tungsten impurity content in molybdenum powder using ICP-OES according to claim 1, characterized in that: In step S1, the five mass concentrations are 0 mg / L, 0.1 mg / L, 0.5 mg / L, 2.5 mg / L and 6.25 mg / L, respectively.

5. The method for determining the tungsten impurity content in molybdenum powder using ICP-OES according to claim 1, characterized in that: In step S2, 3 mL of concentrated nitric acid and 1 mL of concentrated hydrochloric acid are added to every 0.1 g of molybdenum powder to dissolve it, and then high-purity water is added to dilute it to 50 mL.

6. The method for determining tungsten metal element in molybdenum powder using ICP-OES according to claim 5, characterized in that: The concentrated nitric acid in step S2 has a mass concentration of 65%, and the concentrated hydrochloric acid has a mass concentration of 36%-38%.

7. The method for determining the tungsten impurity content in molybdenum powder using ICP-OES according to claim 1, characterized in that: The detection wavelength used in step S3 is 209.475nm, 239.709nm or 224.875nm.

8. The method for determining the tungsten impurity content in molybdenum powder using ICP-OES according to claim 7, characterized in that: The detection wavelength used in step S3 is 209.475 nm.

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