Method for measuring and analyzing lead, cadmium, iron and zinc in lead smoke dust through X-ray fluorescence spectrometry

Abstract

The invention discloses a method for determining and analyzing lead, cadmium, iron and zinc in lead smoke dust through X-ray fluorescence spectrometry, and belongs to the technical field of determination and analysis of components of comprehensively recycled lead smoke dust in zinc smelting production. The method comprises the following steps: preparing an analysis sample by adopting a direct tabletting method without acid digestion of a sample and directly preparing soot powder under the working pressure of 30-40T and the dwell time of 15 seconds. A multiple regression correction method is adopted to correct matrix interference, a Pb L beta 1 element spectral line is selected to eliminate overlapping interference of a Pb K alpha 1.2 spectral line and an As K alpha 1.2 spectral line, and then a correction formula is added. The sample does not need to be subjected to complex chemical treatment, the original state of the cigarette ash sample can be kept, and multiple analysis or other subsequent tests can be carried out on the same batch of samples. The method can be used for simultaneously analyzing multiple elements, namely simultaneously determining multiple elements in the soot from macroelements to microelements such as Pb, Zn, Cd, Fe and the like, so that the analysis efficiency is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of analytical techniques for the determination of lead, cadmium, iron, and zinc components in lead-containing dust recovered during zinc smelting production, specifically to a method for determining and analyzing lead, cadmium, iron, and zinc in lead-containing dust using X-ray fluorescence spectrometry. Background Technology

[0002] Lead dust is a dust product from the flue gas produced during the roasting of zinc oxide in a rotary kiln for defluorination and chlorination in the hydrometallurgical process of zinc smelting. This material has a high lead content, and also contains impurities such as zinc and cadmium. The content of these main components is a crucial monitoring indicator for analyzing and determining the stable operation of the furnace and the overall recovery efficiency. Therefore, it is essential to establish a simple, rapid, accurate, and sensitive analytical method for its determination.

[0003] Routine lead fume analysis typically employs conventional methods such as volumetric analysis for lead, flame atomic absorption spectrophotometry, and inductively coupled plasma optical emission spectrometry (ICP-OES) to analyze impurities. These methods involve complex sample pretreatment processes, including sample collection, pretreatment, and separation. Furthermore, single-element analysis is time-consuming, extending the overall analysis cycle. Rapid and accurate detection results are crucial for production status monitoring and process parameter optimization. Conventional analytical methods result in delayed data feedback, failing to meet production demands.

[0004] Conventional analytical methods, such as the EDTA volumetric method for determining zinc and lead, require prior precipitation to separate interfering elements, making the operation complex and the analytical process lengthy. The ICP-OES method for determining cadmium and the flame atomic absorption spectrophotometry method for determining iron both require measures such as matrix matching to eliminate interference. The sample pretreatment process is cumbersome, and the selection of instrument measurement conditions has a significant impact on the accuracy of the analytical results. These methods are not well-suited for analyzing similar samples such as lead dust. Summary of the Invention

[0005] The purpose of this invention is to establish a rapid method for determining the content of lead, zinc, cadmium, and iron in lead-containing flue dust from zinc smelting processes. The method primarily employs a direct compression method, eliminating the need for acid digestion. Flue dust powder is directly compressed under a working pressure of 30–40T for 15 seconds to prepare analytical samples. A multiple regression correction method is used to correct for matrix interferences, with Pb L... β 1 elemental spectral lines to eliminate Pb K α 1.2 Spectral lines and As K α 1.2 The overlapping interference of spectral lines is addressed by incorporating a correction formula. This solves the problems of conventional determination methods, such as complex processing, significant matrix interference, long detection time, limited sample applicability, and narrow application range.

[0006] The technical solution adopted in this invention is as follows:

[0007] A method for determining and analyzing lead, cadmium, iron, and zinc in lead-containing dust using X-ray fluorescence spectrometry includes the following steps:

[0008] Step 1: Collection: Collect multiple soot samples at different time periods to ensure a sufficient number of samples for establishing a standard working curve;

[0009] Step 2, Drying: The collected samples need to be dried by heating to prevent them from absorbing moisture in the natural environment and to ensure that the samples are dry.

[0010] Step 3: Grinding and sieving: Grind the dried sample and sieve it using a standard sieve. All samples used for analysis must pass through a 200-mesh standard sieve to ensure uniform particle size and reduce analytical errors caused by particle size effects.

[0011] Step 4, tableting: Take an appropriate amount of the ground sample and put it into a tablet press. With boric acid edging, it is pressed into a thin sheet under a certain pressure for X-ray fluorescence spectroscopy analysis. During the tableting process, the sample surface must be flat, dense, free from contamination, cracks, and flaking.

[0012] Step 5: Preparation of standard samples: 30 samples with different contents during the production process were selected, and 4 parallel samples were analyzed and determined by EDTA volumetric method and flame atomic absorption spectrophotometry respectively. After removing outliers with large deviations from the 8 sets of Pb, Zn, Cd and Fe data, the overall average value was determined as the final standard sample data, which is used to establish the standard working curve.

[0013] Step Six: Instrument Parameter Setting: Using an X-ray fluorescence spectrometer, set the X-ray fluorescence spectrometer operating conditions according to the analysis software measurement mode. When analyzing and determining the four elements Pb, Zn, Cd, and Fe, measurements were performed under conditions of 50kV voltage and 50mA current. The selected spectral lines were: Pb L β 1. Zn K α 1. Cd K α 1.2, Fe K α 1.2; Cd, Pb, and Zn were measured using scintillation detectors, while Fe was measured using a gas flow detector. The spectroscopic crystals were all LiF220. The measurement time for Pb and Zn was 15 s, and the measurement time for Cd and Fe was 20 s.

[0014] Step 7: Spectral interference correction: Multivariate regression correction method is used to correct matrix interference. For Pb spectral lines, the As spectral line overlap correction method AI is used for correction; for Zn spectral lines, the Cd empirical coefficient method is used for correction; for Cd spectral lines, the Pb empirical coefficient method is used for correction; and for Fe spectral lines, the Zn empirical coefficient method is used for correction.

[0015] Step 8, Sample Measurement and Analysis: Place the prepared sample into an X-ray fluorescence spectrometer with pre-set parameters for measurement. The instrument automatically collects, processes, and analyzes the data to obtain the contents of Pb, Zn, Cd, and Fe in the lead dust.

[0016] Furthermore, in step four, the ground sample is placed in a tablet press and prepared using a working pressure of 30-40T and a holding time of 15 seconds to complete the preparation of the analytical sample.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0018] 1. This invention eliminates the need for complex chemical treatment of samples, preserving the original state of the flue ash samples and allowing for multiple analyses or other subsequent tests on the same batch of samples. Simultaneous multi-element analysis: It can simultaneously determine multiple elements in flue ash, from macroelements to trace elements, such as Pb, Zn, Cd, and Fe, greatly improving analytical efficiency.

[0019] 2. The present invention has a fast analysis speed: the analysis of a sample can be completed in a few minutes, which significantly reduces the time compared with some traditional chemical analysis methods.

[0020] 3. This invention has low environmental pollution: The analysis process does not require the use of large amounts of chemical reagents, which reduces the pollution of the environment and the harm to the health of operators caused by chemical reagents, making it a relatively green analytical method.

[0021] 4. The instrument of this invention has a high degree of automation: Modern X-ray fluorescence spectrometers are equipped with advanced software and automated control systems, which are easy to operate and master. They can automatically collect, process and analyze data, reducing human error. Attached Figure Description

[0022] Figure 1 This is a standard sample data table for embodiments of the present invention;

[0023] Figure 2 This is a standard operating curve diagram of Pb according to an embodiment of the present invention;

[0024] Figure 3 This is a standard working curve diagram of Zn according to an embodiment of the present invention;

[0025] Figure 4 This is a Cd standard operating curve diagram according to an embodiment of the present invention;

[0026] Figure 5 This is a standard working curve diagram of Fe according to an embodiment of the present invention;

[0027] Figure 6 This is a scan peak height diagram of intensity overflow in an embodiment of the present invention;

[0028] Figure 7 This is a scan peak height diagram after adjusting the collimator according to an embodiment of the present invention;

[0029] Figure 8 This is an abnormal scanning peak diagram of high-content elements in an embodiment of the present invention;

[0030] Figure 9 This is a normal scan peak diagram after optimizing the measurement conditions and parameters according to an embodiment of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0033] Example 1

[0034] This embodiment provides a method for determining and analyzing lead, cadmium, iron, and zinc in lead-containing dust using X-ray fluorescence spectrometry, including the following steps:

[0035] Sample Collection and Preparation: Lead dust samples were collected from the zinc oxide produced by the defluorination and chlorination rotary kiln roasting process in the hydrometallurgical zinc smelting process. Samples were collected at different time periods to ensure a sufficient number of samples for establishing the standard working curve. The collected samples were heated and dried to prevent moisture absorption. The dried samples were then ground and sieved using a standard sieve. All samples used for analysis were sieved through a 200-mesh standard sieve to ensure uniform particle size and reduce analytical errors caused by particle size effects. An appropriate amount of the ground sample was placed in a tablet press, edged with boric acid, and made into thin sheets under a working pressure of 30-40T and a holding pressure of 15 seconds. The surface of the sheets was flat, dense, free of contamination, cracks, and slag.

[0036] Preparation of standard samples: Thirty lead fume samples with different contents were selected during the production process. Each sample was analyzed in four parallel sets using EDTA volumetric method and flame atomic absorption spectrophotometry. After removing outliers with large deviations from the eight sets of Pb, Zn, Cd and Fe data, the overall average value was determined as the final standard sample data, which was used to establish the standard working curve.

[0037] Instrument parameter settings: An X-ray fluorescence spectrometer was used. Considering the characteristics of the main components of the sample and the lifespan of the instrument's X-ray tube, a voltage of 50 kV and a current of 50 mA were selected for the analysis and determination of four elements: Pb, Zn, Cd, and Fe. The selected spectral lines were Pb Lβ1, Zn Kα1, Cd Kα1.2, and Fe Kα1.2, respectively. Scintillation detectors were used for Cd, Pb, and Zn, and a gas flow detector was used for Fe. The spectroscopic crystals were all LiF220. The measurement time for Pb and Zn was 15 seconds, and the measurement time for Cd and Fe was 20 seconds. When analyzing Pb, if the angle scan intensity exceeded the optimal measurement range of the instrument (10-1500 kcps), the collimator was adjusted from 0.4 to 0.15.

[0038] Spectral interference correction: Matrix interference was corrected using a multiple regression correction method. For Pb spectral lines, the As spectral line overlap correction method (AI) was used; for Zn spectral lines, the Cd empirical coefficient method (MI correction based on intensity relationship) was used; for Cd spectral lines, the Pb empirical coefficient method (MI correction based on intensity relationship) was used; and for Fe spectral lines, the Zn empirical coefficient method (MC correction based on concentration relationship) was used.

[0039] Sample determination and analysis: The prepared sample to be analyzed is placed in an X-ray fluorescence spectrometer with the parameters set for determination. The instrument automatically collects, processes and analyzes the data to obtain the contents of Pb, Zn, Cd and Fe in lead dust.

[0040] In this embodiment, the Thermo Fisher Scientific wavelength dispersive X-ray fluorescence spectrometer (ARL PERFORM, X) was selected as the main analytical instrument.

[0041] Preparation of standard samples

[0042] Thirty samples with different contents from the production process were selected, and four parallel sets of samples were analyzed using EDTA volumetric method and flame atomic absorption spectrophotometry, respectively. After removing outliers with significant deviations from the eight sets of Pb, Zn, Cd, and Fe data, the overall mean was determined as the final standard sample data. The standard sample data used to establish the standard working curve are as follows: Figure 1 As shown.

[0043] Instrument measurement conditions

[0044] Taking into account the characteristics of the main components of the sample and the lifespan of the instrument's X-ray tube, the analysis and determination of the four elements were performed under conditions of 50 kA voltage and 50 mA current; the selected spectral lines were: PbL. β 1. CdK α 1.2, ZnK α 1. FeK α1.2; Scintillation detectors were used for Cd, Pb, and Zn, and a gas flow detector was used for Fe. The spectroscopic crystal for all samples was LiF220. The measurement time for Pb and Zn was 15 seconds, and the measurement time for Cd and Fe was 20 seconds. The operating conditions were set according to the measurement mode of the analysis software, as shown in Table 2.

[0045] Table 2X Fluorescence Spectrometer Operating Conditions

[0046] element Spectral lines crystal 2Thcta detector collimator Pb <![CDATA[PbK β 1]]> LiF220 28.257 SC 0.40 Zn <![CDATA[ZnK α 1]]> LiF220 60.570 SC 0.40 Cd <![CDATA[CdK α 1.2]]> LiF220 15.313 SC 0.40 Fe <![CDATA[FeK α 1.2]]> LiF220 57.518 FPC 0.15

[0047] Spectral interference and correction

[0048] Experiments revealed that the Pb spectral curve showed poor linearity after fitting, and the standard points were discrete. Correction using the As spectral overlap correction method (AI) significantly improved the linearity. The Pb standard working curve after correction was then measured as follows: Figure 2 As shown.

[0049] Experiments revealed that the Zn spectral curve showed poor linearity after fitting, with some standard points being discrete. Correction using the Cd empirical coefficient method (MI corrected by intensity relationship) significantly improved the linearity. The corrected Zn standard working curve was then measured as follows: Figure 3 As shown.

[0050] Experiments revealed that the Cd spectral curve showed poor linearity after fitting, with some standard points being discrete. Correction using the Pb empirical coefficient method (MI corrected by intensity relationship) significantly improved the linearity. The corrected Cd standard working curve was then measured as follows: Figure 4 As shown.

[0051] Experiments revealed that the linearity of the Fe spectral curve after fitting was poor, and some standard points were discrete. Correction using the Zn empirical coefficient method (MC corrected for concentration relationship) significantly improved the linearity. The corrected Fe standard working curve was then measured as follows: Figure 5 As shown.

[0052] Experiment to eliminate influencing factors

[0053] 1. Analyze the impact of time

[0054] The length of the analysis time determines the stability of the measurement results. Shorter analysis times have a greater impact on low-content elements, but less so on high-content elements. Appropriately increasing the elemental analysis time (e.g., adjusting from the instrument's recommended 15s to 30-40s) will improve the linearity of the curve. This will result in better stability of the analytical results when measuring samples.

[0055] 2. Intensity overflow effect of high-content elements

[0056] Experiments revealed that higher elemental content in the sample resulted in higher intensity values. However, the intensity of these intensities during elemental characteristic spectral scanning exceeded the instrument's optimal measurement range (10–1500 Kcps), causing deviations in the analytical results. When intensity overflowed, the peak height during scanning was as follows: Figure 6 As shown.

[0057] When establishing the spectral lines of Pb (40%–60%), the Pb element is represented by PbL. β During spectral analysis, the angular scan intensity overflowed (1700 kcps). After adjusting the collimator size, the intensity values ​​of the characteristic spectral lines of the scanned elements decreased when the collimator was adjusted from 0.4 to 0.15, which was then controlled within the optimal measurement range. The scan peak height after adjusting the collimator is shown below. Figure 7 As shown.

[0058] Scanning elemental characteristic spectral lines experiment

[0059] Experiments revealed that the higher the measured elemental concentration in the sample, the more abnormal peaks appeared when scanning the elemental characteristic spectral lines. These scanned elemental characteristic spectral lines exhibited double peaks, and the abnormal scanning peaks were as follows: Figure 8 As shown.

[0060] After multiple experimental analyses, it was determined that the sample element concentration was too high, the measurement conditions were improperly set, and the measured intensity value exceeded the instrument's detection range (2100 Kcps). This issue was effectively resolved by replacing the characteristic spectral lines of the measured elements or by adjusting the collimator. After changing the settings, the measured scan peaks returned to normal. Figure 9 As shown.

[0061] Particle size effect experiment

[0062] Take 100-200g of dried lead fume sample and test it under different conditions such as grinding time, tableting pressure, and holding time. Take 3.0g of the ground sample and press it into a tablet with boric acid edging to ensure that the tablet is free of cracks, slag, and contamination, and that the analytical surface is smooth and flat.

[0063] 1. Grinding time experiment.

[0064] The grinding time of the vibratory mill was adjusted, and samples were pressed into specimens for analysis and determination of the content of each element. Experiments showed that when lead dust was ground for 20 seconds, the particle size of the sample was too large, and it felt coarse to the touch. Between 30 and 50 seconds, the sample felt smooth and free of particles. All samples were completely sieved through an 180-mesh sieve, meeting the requirements for X-ray fluorescence analysis. There was no significant difference in the intensity of the analytical spectral lines, and the effect of particle size was eliminated. To ensure analytical stability, a grinding time of 40 seconds was selected for the samples. Experimental test data are shown in Table 3.

[0065] Table 3. Experimental data on sample grinding time (unit: Kcps)

[0066] Grinding time / s Pb Zn Cd Fe 20s 751.919 929.790 59.388 77.965 30s 752.636 931.413 59.343 77.435 40s 752.694 933.871 59.398 77.325 50s 752.705 932.235 59.375 77.543

[0067] 2. Tablet sample experiment

[0068] Using the same sample, a compression pressure experiment was conducted. The experiment revealed that under a sample preparation pressure of 10T, the analytical sample was loose and not compact, and was easily broken by hand. Under pressures of 20–40T, the sample was firm and compact, with a smooth and flat appearance. To ensure the uniformity and stability of the analytical sample, a sample preparation pressure of 30T was selected. The experimental test data are shown in Table 4.

[0069] Table 4. Experimental data on sample preparation pressure (unit: Kcps)

[0070] Sample preparation pressure / T Pb Zn Cd Fe 10 850.697 522.078 62.850 43.952 20 851.672 522.829 63.139 43.998 30 852.664 522.701 63.192 44.815 40 852.499 522.658 63.351 44.727

[0071] 3. Pressure holding time test

[0072] Using the same sample, a pressure holding experiment was conducted. The experiment found that under a sample preparation pressure of 30T and a holding time of 15s to 30s, the sample was dense and the surface was relatively smooth. To ensure analytical stability, a sample preparation holding time of 20s was selected. The experimental test data are shown in Table 5.

[0073] Table 5. Experimental data on sample preparation and holding time (unit: Kcps)

[0074] Pressure holding time / s Pb Zn Cd Fe 10 790.506 809.173 53.220 72.687 15 791.233 808.644 53.201 72.662 20 790.381 811.220 53.111 72.961 25 789.396 811.100 53.362 73.132 30 789.230 812.166 53.259 72.954

[0075] Precision test

[0076] Six parallel determinations were performed on lead fume samples to verify the test precision. The results are shown in Table 6.

[0077] Table 6. Precision Inspection

[0078]

[0079] The data in the table show that the intensity values ​​are above approximately 80 (Kcps), and the differences in sample thickness and normal instrument fluctuations have little impact on the analytical results. The relative standard deviation of the analytical results is between 0.22% and 1.50%, indicating good test precision.

[0080] Sample analysis and test data comparison experiment

[0081] Using the established X-ray fluorescence spectrometry method, production materials with different contents were selected as experimental samples according to the analytical steps. The data were compared with those obtained by volumetric analysis and flame atomic absorption spectrophotometry to verify the good agreement between the X-ray fluorescence spectrometry data and the analytical data. The comparative analysis results are shown in Table 7.

[0082] Table 7 Comparison of X-ray fluorescence spectroscopy analysis data and chemical method analysis data

[0083]

[0084]

[0085] Experimental results show that there is no significant difference between the results obtained by this method and the original method, and the data have a high degree of agreement. This indicates that the accuracy of the X-ray fluorescence spectrometry method in determining the content of the main components in lead dust meets the requirements of rapid analysis and detection, and can meet the detection needs of production monitoring samples.

[0086] The experimental setup of this invention addresses various aspects, including the selection of standard samples, matrix correction factors, analysis of material properties, and measurement parameter conditions. It clarifies the factors affecting the accuracy and precision of analytical data and implements effective measures for improvement and optimization, achieving excellent results. The proposed measures are practical and applicable to the establishment of X-ray fluorescence analysis methods for various zinc-containing materials in zinc smelting.

Claims

1. A method for determining lead, cadmium, iron and zinc in lead soot by X-ray fluorescence spectroscopy, characterized in that, Comprising the following steps: Step one, collection: collect multiple soot samples at different time periods, ensure sufficient sample quantity for establishing standard working curve; Step two, drying: the collected samples need to be heated and dried to avoid moisture absorption in the natural environment and ensure sample drying; Step three, grinding and sieving: grind the dried samples and sieve them with standard sieves, the samples for analysis must pass through 200 mesh standard sieves to ensure uniform sample particle size and reduce analysis errors caused by particle size effect; Step four, tabletting: take an appropriate amount of ground sample and put it into a tablet press to make thin slices under a certain pressure with boric acid inlay to facilitate X fluorescence spectrum analysis, the tabletting process should ensure that the sample surface is flat, dense, non-polluted, non-cracked and non-dropped residue; Step five, standard sample preparation: select 30 samples with different contents in the production process, use EDTA volumetric method and flame atomic absorption spectrophotometry to analyze and determine 4 groups of parallel samples respectively; after eliminating the outlying values with larger deviations from the obtained 8 groups of Pb, Zn, Cd and Fe data, determine the overall average value as the final standard sample data for establishing standard working curve; Step six, instrument parameter setting: using X fluorescence spectrometer, according to the analysis software measurement mode setting X fluorescence instrument working condition, analysis and determination of Pb, Zn, Cd, Fe 4 kinds of elements are selected 50kV voltage, 50mA current conditions under measurement; Select the spectral line: Pb L β 1, Zn K α 1, Cd K α 1.2, Fe K α 1.2; Cd, Pb, Zn use scintillation detector, Fe selects the flow gas detector, the spectral crystal is LiF220; Pb, Zn measurement time is 15s, Cd, Fe measurement time is 20s; Step seven, spectral line interference correction: use multivariate regression correction method to correct matrix interference, for Pb spectral line, use As spectral line overlap correction method AI for correction; for Zn spectral line, use Cd empirical coefficient method for correction; for Cd spectral line, use Pb empirical coefficient method for correction; for Fe spectral line, use Zn empirical coefficient method for correction; Step eight, sample determination and analysis: put the prepared sample into the X fluorescence spectrometer with set parameters for determination, the instrument automatically collects, processes and analyzes the data to obtain the content of Pb, Zn, Cd and Fe in lead soot.

2. A method for determining lead, cadmium, iron and zinc in lead soot by X-ray fluorescence spectroscopy according to claim 1, characterized in that, In step four, the ground sample is put into the tablet press to complete the preparation of analysis sample under working pressure of 30-40T and pressure holding time of 15 seconds.

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