Method for determining multiple metal impurity elements in sodium diuranate based on ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry)

Abstract

The invention discloses a method for measuring multiple metal impurity elements in sodium diuranate based on an ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry) method, which comprises the following steps: step 1, weighing sodium diuranate with a preset weight, sequentially adding a hydrogen peroxide solution and concentrated nitric acid, then heating to a nearly dry state, adding a nitric acid solution, and dissolving to a clear state to obtain a sample solution to be separated; step 2, transferring the to-be-separated sample solution into a chromatographic column, leaching a small amount of the to-be-separated sample solution for multiple times by adopting a nitric acid solution, and fixing the volume of the leacheate into a 50mL volumetric flask to obtain a to-be-measured sample solution; and 3, preparing a plurality of standard solutions, determining the standard solutions by adopting ICP-AES, drawing a corresponding working curve, and analyzing and determining a plurality of elements, including Ti, Mo, Cr, V and W, in the sample solution to be determined. The invention aims to efficiently measure various metal impurity elements in sodium diuranate.

Description

Technical Field

[0001] The invention relates to the technical field of element determination in sodium diuranate, and in particular to a method for determining multiple metal impurity elements in sodium diuranate based on an ICP-AES method. Background Art

[0002] Sodium diuranate is a product of uranium mining and metallurgy. As a professional raw material for uranium purification, its Ti, Mo, Cr, V, and W content has an important impact on uranium purification, extraction, separation, and product quality. Due to the differences in uranium mining and metallurgy production processes and ore raw materials, the content of various impurity elements in the prepared sodium diuranate products fluctuates widely, and the total amount of work required for the separate analysis of impurity elements is large. The existing invention patent with the patent publication number CN103601245A discloses a method for preparing a standard substance of non-metallic elements of diuranate. The method first co-precipitates phosphorus and silicon into diuranate by precipitation crystallization, and partially co-precipitates fluorine into diuranate; then, sulfur, chlorine, and a small amount of fluorine are synthesized into diuranate by pulping evaporation, and a standard substance that meets the fixed values ​​of sulfur, phosphorus, silicon, fluorine, and chlorine in sodium diuranate is obtained. However, this method is only used to determine the non-metallic impurity elements in diuranate, and cannot be used to determine the metal elements inside it. Summary of the invention

[0003] The main purpose of the present invention is to provide a method for determining multiple metal impurity elements in sodium diuranate based on the ICP-AES method, aiming to solve the technical problem that the existing element determination method in sodium diuranate cannot efficiently determine multiple metal impurity elements.

[0004] To achieve the above object, the present invention provides a method for determining multiple metal impurity elements in sodium diuranate based on ICP-AES method, the method comprising the following steps:

[0005] Step 1, weighing a preset weight of sodium diuranate and adding hydrogen peroxide solution and concentrated nitric acid in sequence, then heating to a nearly dry state, and then adding nitric acid solution to dissolve until clear, to obtain a sample solution to be separated;

[0006] Step 2, transferring the sample solution to be separated into the chromatographic column, eluting with a nitric acid solution in small amounts and multiple times, and diluting the eluent into a 50 mL volumetric flask to obtain a sample solution to be measured;

[0007] Step 3, prepare multiple standard solutions and use ICP-AES to measure the standard solutions, draw corresponding working curves, and analyze and measure multiple elements in the sample solution to be measured, including Ti, Mo, Cr, V and W.

[0008] Optionally, in step 1, 0.3000±0.0005 g of sodium diuranate is weighed into a 50 mL beaker, and 3 to 5 drops of hydrogen peroxide solution and concentrated nitric acid are added respectively to dissolve the sodium diuranate.

[0009] Optionally, the solubility of the nitric acid solution in step 1 and step 2 is 5 mol / L.

[0010] Optionally, in step 2, the height of the resin in the chromatography column is 12 cm.

[0011] Optionally, in step 3, the standard solutions of the four elements Ti, Mo, Cr, and V are prepared using deionized water and 5 mol / L nitric acid as media to prepare 0.1, 1, 10, and 20 μg / mL solutions, respectively, and the standard solution of the element W is prepared using deionized water and 0.1 g / L NaOH solution to prepare 0.1, 1, 10, and 20 μg / mL solutions, respectively.

[0012] Optionally, in step 3, the setting conditions of ICP-AES are: RF power of 1350 kW, pump speed of 160 rpm, carrier gas flow rate of 20 psi, and auxiliary gas flow rate of 0.5 LPM.

[0013] Optionally, in step 3, 323.452 nm is used for the spectrum line of the Ti element; 202.030 nm is used for the spectrum line of the Mo element; 205.552 nm is used for the spectrum line of the Cr element; 292.402 nm is used for the spectrum line of the V element; and 207.911 nm is used for the spectrum line of the W element.

[0014] Optionally, in step 3, the observation method for Ti, Mo, Cr, V and W is horizontal observation.

[0015] Optionally, in step 3, the observation time of the five elements Mo, Cr, W, Ti and V is 10-20S.

[0016] Optionally, in step 1, the density of concentrated nitric acid is 1.4 g / mL, and the mass fraction of H2O2 is 30%.

[0017] Beneficial effects:

[0018] By pretreating the sodium diuranate before determination and adjusting the determination instrument, the contents of five elements, Ti, Mo, Cr, V, and W in the sodium diuranate can be finally obtained. The relative deviation of the test results of the same sample is less than 3%, thus meeting the inspection requirements and being applicable to a wide range of uses. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the elution curve of Ti element;

[0020] Figure 2is the elution curve of Mo element;

[0021] Figure 3 is the elution curve of Cr element;

[0022] Figure 4 is the elution curve of element V;

[0023] Figure 5 This is the elution curve of the W element.

[0024] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0025] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0026] Reagents and materials used in the experiment

[0027] Table 1 Experimental materials

[0028] Reagents concentration Sodium hydroxide Premium Pure Titanium standard solution 1000 μg / mL Molybdenum standard solution 1000 μg / mL Chromium standard solution 1000 μg / mL Vanadium standard solution 1000 μg / mL Tungsten Standard Solution 1000 μg / mL Titanium standard solution 100 μg / mL Molybdenum standard solution 100 μg / mL Chromium standard solution 100 μg / mL Vanadium standard solution 100 μg / mL Tungsten Standard Solution 100 μg / mL Cl-TBP leaching resin

[0029] Experimental instruments and equipment

[0030] Electric furnace: 2.4kW, temperature < 300℃

[0031] Chromatographic column: inner diameter 8cm

[0032] Treatment before measurement

[0033] Step 1, weighing 0.3000±0.0005g of sodium diuranate into a 50mL beaker, and adding hydrogen peroxide solution and concentrated nitric acid in sequence, and then heating and dissolving on an electric furnace until nearly dry, and then adding 3mL of 5mol / L nitric acid solution to dissolve until clear, to obtain a sample solution to be separated; wherein, 3 to 5 drops of hydrogen peroxide solution and concentrated nitric acid are added, and the mass fraction of hydrogen peroxide is about 30%, and the density of concentrated nitric acid is about 1.4g / mL.

[0034] Step 2, transfer the sample solution to be separated into the chromatographic column, use 5mol / L nitric acid solution for multiple small amount of elution, collect 1.7mL of sample solution in the container each time, collect 30 times continuously, and dilute the eluent into a 50mL volumetric flask to obtain the sample solution to be measured; wherein, based on the resin height of Ti, Cr, and W being 10 to 14cm, and the signal-to-back ratio of Mo and V being 12cm at the resin height, the resin height in the chromatographic column used in this embodiment is 12cm. The purpose of elution is to remove the elemental uranium in the sodium diuranate solution, and the elution data shown in Table 2 are obtained.

[0035] Table 2 Sample elution data

[0036]

[0037] Based on the elution data of Ti, Cr, W, Mo, and V in Table 2, the following Figure 1-5 The elution curves of Ti, Cr, W, Mo, and V are shown in the figure. It can be seen from the figure that the sample elution has an empty volume of no less than 5 mL, Mo and W have a small amount of tailing, Ti, Cr, and V can be basically eluted clean in 25 mL, and Mo and W can be eluted clean in nearly 40 mL. In order to prevent tailing, 5 mL of empty volume is released, and then a 50 mL volumetric flask is used to receive the sample to the scale, which can ensure that the elements in the sample are basically eluted clean.

[0038] Standard solution preparation

[0039] Prepare multiple standard solutions and measure the standard solutions using ICP-AES, and draw the corresponding working curves.

[0040] Specifically, experiments were conducted on the medium concentrations of 1000μg / mL and 100μg / mL standard solution series, and deionized water and 5mol / L nitric acid were used as the medium to prepare four standard solutions of 0.1μg / mL, 1μg / mL, 10μg / mL, and 20μg / mL for the four elements Ti, Mo, Cr, and V, respectively. Deionized water and 0.1g / L NaOH solution were used to prepare four standard solutions of 0.1μg / mL, 1μg / mL, 10μg / mL, and 20μg / mL for the element W, respectively. Then, respective working curves were drawn to measure the same sample solution. The results are shown in Tables 3-4.

[0041] Table 3- Matching results of standard solutions of four elements: Ti, Mo, Cr, and V

[0042]

[0043] Table 4-W element standard solution matching results

[0044]

[0045] From Table 3-4 above, it can be determined that the matching degree of the standard solution has little effect on the measured structure, but the tungsten standard should not be used with deionized water and nitric acid as the medium, and a small amount of NaOH is added to prevent hydrolysis.

[0046] Spectral line selection

[0047] In this embodiment, the spectral line selection condition is based on selecting elements with less interference, and 2-3 spectral lines are screened for each element in advance for analysis. The selected spectral lines are shown in Table 5, and the analysis data are shown in Table 6.

[0048] Table 5- Spectral line selection of each element

[0049] Ti Mo Cr V W 323.452 202.030 205.552 292.402 239.109 336.121 204.598 206.149 311.838 207.911 337.280 203.844 - - -

[0050] Table 6 - Analysis data table

[0051]

[0052]

[0053] Note: The concentration of each element in the standard solution is 1 μg / mL.

[0054] From Table 6, it can be seen that by comprehensively comparing the signal value of the standard solution and the signal-to-background ratio of the sample solution, the spectral line selection is 323.452nm for Ti element and 202.030nm for Mo element; 205.552nm for Cr element, 292.402nm for V element, and 207.911nm for W element.

[0055] Choice of observation method

[0056] The same sample was measured using different observation methods, and the final results are shown in Table 7.

[0057] Table 7 Measurement results of different observation methods

[0058]

[0059] Note: In the initial instrument custom observation, Mo is observed vertically, and other elements are observed horizontally.

[0060] As can be seen from Table 7, the signal value of the horizontal observation method is stronger than that of the vertical observation method. For the four elements Ti, Cr, V, and W with low content, the horizontal observation method is adopted. For the Mo element: the Mo element analysis line is a low band, and horizontal observation is suitable. Due to the high content in this sample, the interference of the vertical observation method is small, but by comparing with the horizontal observation method, the relative error of the content values ​​measured by the two observation methods is less than 5%, and the impurity content of the sodium diuranate product fluctuates in a large range. In order to make the determination method universal, the observation method of the Mo element is positioned as horizontal observation. Furthermore, in this embodiment, the observation methods of Ti, Mo, Cr, V, and W are set to horizontal observation.

[0061] Flushing time determination

[0062] In order to reduce the error in measuring different samples, before measuring each sample, it is necessary to rinse the residual sample of the previous measurement. Then, after measuring the sample at different rinsing times, the sampling tube is inserted into the primary water for measurement. The results are shown in Table 8.

[0063] Table 8 Test results at different flushing times

[0064]

[0065]

[0066] From Table 8, we can see that the Mo element with a relatively high content has a small amount of residue. In order to rinse the sample residue as cleanly as possible and minimize the memory effect caused by the sample residue, the rinsing time is selected as 30S. If the content difference between the two samples is large, the injection tube is placed in primary water for 2 minutes.

[0067] Observation time determination

[0068] The same sample was measured at different observation times through testing, and the results are shown in Table 9.

[0069] Table 9 Content measurement results at different observation times

[0070]

[0071] It can be seen from Table 9 that the results of observing the three low-band elements Mo, Cr, and W in the 10-20S time period are not much different, and the results of observing the two high-band elements Ti and V in the 10-20S time period are not much different. Therefore, in this embodiment, the observation time can be selected as 10-20S, and in order to further improve the measurement stability, the observation time can be preferably 15-20S.

[0072] Instrument conditions determination

[0073] In order to obtain the best sensitivity and make the net signal value reach the strongest under this condition, an orthogonal experiment with 4 factors and 4 levels was established for the four conditions of peristaltic pump speed, RF power, carrier gas flow rate, and auxiliary gas flow rate. The condition factor level table is shown in Table 10 to determine the optimal instrument conditions.

[0074] Table 10 Instrument condition factor level table

[0075] level RF power (kW) Pump speed (rpm) Carrier gas flow rate (psi) Auxiliary gas flow (LPM) 1 750 100 20 0 2 950 120 25 0.5 3 1150 140 30 1 4 1350 160 35 1.5

[0076] An orthogonal experiment was conducted based on the conditional factors in Table 10, and the analytical instrument conditions were finally determined: RF power of 1350 kW, pump speed of 160 rpm, carrier gas flow rate of 20 psi, and auxiliary gas flow rate of 0.5 LPM.

[0077] Five element analysis

[0078] According to the above selected parameters, Ti, Mo, Cr, V and W in the sample solution to be measured were analyzed and measured, that is, under the conditions of RF power of 1350kW, pump speed of 160rpm, carrier gas flow rate of 20psi and auxiliary gas flow rate of 0.5LPM, the same sample was measured 10 times and its stability was observed. The data are shown in Table 11.

[0079] Table 11 Instrument stability test results

[0080]

[0081] As can be seen from Table 11, the relative standard deviations of the 10 determination results of the five elements are all less than 3%, indicating that the determination repeatability of the above-determined instrument conditions is good.

[0082] Method precision and spike recovery experiments

[0083] Take any sodium diuranate sample for the experiment, the standard addition amount of titanium is 20μg, the standard addition amount of molybdenum is 500μg, the standard addition amount of chromium is 1μg, the standard addition amount of vanadium is 50μg, and the standard addition amount of tungsten is 10μg. The test results are shown in Table 12.

[0084] Table 12 Precision and recovery test results

[0085]

[0086] As can be seen from Table 12, the maximum RSD value of the parallel sample determinations of the five impurity elements is 9.7%. According to the previous ICP-AES determination methods for various samples, the RSD of the determination results of 6 parallel samples is required to be less than 10%, so the precision of this experiment can meet the analysis requirements.

[0087] The recovery rate of Ti element addition is between 90.0% and 101.0%, the recovery rate of Mo element addition is between 92.9% and 98.9%, the recovery rate of Cr element addition is between 84.0% and 108.0%, the recovery rate of V element addition is between 91.0% and 96.6%, and the recovery rate of W element addition is between 87.0% and 103.0%. The average recovery rate of each element addition is between 90% and 100%, which can meet the requirements of analysis and determination.

[0088] Method detection limit experiment

[0089] The reagent blank was measured ten times continuously, and 5 times the standard deviation of the measurement results of each element was taken as the detection limit of the element, see Table 13.

[0090] Table 13 Method detection limit data table

[0091]

[0092] Analytical method control experiment

[0093] A random sample of sodium diuranate was taken for experiment. The results of titanium, molybdenum and vanadium determined by the national standard method were compared with the experimental results of this method. The results of the comparative test of the analytical methods are shown in Table 14. The relative deviation of the results of the same sample determined by the two methods was within 5%, and the analytical results were basically consistent.

[0094] Table 14 Analytical method control experimental results

[0095]

[0096] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0097] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0098] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for determining multiple metal impurity elements in sodium diuranate based on ICP-AES method, characterized in that: The method comprises the following steps: Step 1, weighing a preset weight of sodium diuranate and adding hydrogen peroxide solution and concentrated nitric acid in sequence, then heating to a nearly dry state, and then adding nitric acid solution to dissolve until clear, to obtain a sample solution to be separated; Step 2, transferring the sample solution to be separated into the chromatographic column, eluting with a nitric acid solution in small amounts and multiple times, and diluting the eluent into a 50 mL volumetric flask to obtain a sample solution to be measured; Step 3, prepare multiple standard solutions and use ICP-AES to measure the standard solutions, draw corresponding working curves, and analyze and measure multiple elements in the sample solution to be measured, including Ti, Mo, Cr, V and W.

2. The method for determining multiple metal impurity elements in sodium diuranate based on ICP-AES according to claim 1, characterized in that: In step 1, weigh 0.3000±0.0005 g of sodium diuranate into a 50 mL beaker, and add 3 to 5 drops of hydrogen peroxide solution and concentrated nitric acid respectively to dissolve the sodium diuranate.

3. The method for determining multiple metal impurity elements in sodium diuranate based on ICP-AES according to claim 1, characterized in that: The solubility of the nitric acid solution in step 1 and step 2 is 5 mol / L.

4. The method for determining multiple metal impurity elements in sodium diuranate based on ICP-AES according to claim 1, characterized in that: The resin height in the chromatography column in step 2 was 12 cm.

5. The method for determining multiple metal impurity elements in sodium diuranate based on ICP-AES according to claim 1, characterized in that: In step 3, the standard solutions of the four elements Ti, Mo, Cr, and V are prepared using deionized water and 5 mol / L nitric acid as the medium to prepare 0.1, 1, 10, and 20 μg / mL solutions, respectively. The standard solution of the element W is prepared using deionized water and 0.1 g / L NaOH solution to prepare 0.1, 1, 10, and 20 μg / mL solutions, respectively.

6. The method for determining multiple metal impurity elements in sodium diuranate based on ICP-AES according to claim 1, characterized in that: In step 3, the setting conditions of ICP-AES are as follows: RF power of 1350 kW, pump speed of 160 rpm, carrier gas flow rate of 20 psi, and auxiliary gas flow rate of 0.5 LPM.

7. The method for determining multiple metal impurity elements in sodium diuranate based on ICP-AES according to claim 1, characterized in that: In step 3, 323.452 nm is used for the spectrum line of Ti element; 202.030 nm is used for the spectrum line of Mo element; 205.552 nm is used for the spectrum line of Cr element; 292.402 nm is used for the spectrum line of V element; and 207.911 nm is used for the spectrum line of W element.

8. The method for determining multiple metal impurity elements in sodium diuranate based on ICP-AES according to claim 1, characterized in that: In step 3, the observation method for Ti, Mo, Cr, V and W is horizontal observation.

9. The method for determining multiple metal impurity elements in sodium diuranate based on ICP-AES according to claim 1, characterized in that: In step 3, the observation time of the five elements Mo, Cr, W, Ti, and V is 10-20S.

10. The method for determining multiple metal impurity elements in sodium diuranate based on ICP-AES according to any one of claims 1 to 9, characterized in that: In step 1, the density of concentrated nitric acid is 1.4 g / mL, and the mass fraction of H2O2 is 30%.

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