X-ray fluorescence analysis method for rapidly analyzing phosphoric acid components

Abstract

The invention provides an X-ray fluorescence analysis method for rapidly analyzing phosphoric acid components, which comprises the following steps: adding nitric acid into a crude phosphoric acid solution sample for digestion, heating and boiling, and cooling to room temperature to obtain a phosphoric acid solution to be detected; preparing phosphoric acid standard samples with chemical values in content gradient, and treating according to the digestion step to obtain phosphoric acid standard solutions with different contents; detecting the phosphoric acid standard liquid by using an X-ray fluorescence spectrophotometer to obtain the test intensity of different components under different contents; drawing standard curves of the different components by taking the content changes of the different components as abscissas and the corresponding test intensities as ordinates; and detecting the phosphoric acid solution to be detected by using the X-ray fluorescence spectrophotometer to obtain the test intensity of different components, and calculating the contents of different components in the phosphoric acid sample by using the standard curve. The detection method disclosed by the invention has the advantages of short analysis time, simple process, environmental friendliness, easiness in operation and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of element detection and analysis, and in particular relates to an X-ray fluorescence analysis method for rapidly analyzing phosphoric acid components. Background Art

[0002] Phosphoric acid is an important industrial raw material with a wide range of applications in industry, agriculture, food, and medicine. Phosphoric acid production primarily involves two processes: wet and thermal. The wet process is currently the most commonly used method, accounting for 70%-80% of phosphoric acid production. The wet process involves decomposing phosphate rock with inorganic acid, separating crude phosphoric acid, and then purifying it to produce the final product. Consequently, the phosphoric acid produced during the production process is unpurified and often contains impurities. These impurities can form insoluble phosphate precipitates, making the solution turbid and non-uniform. Therefore, P2O5 is a primary component and economic indicator of phosphoric acid production and requires testing. Crude phosphoric acid also requires testing for impurities such as SO3, Fe2O3, CaO, Al2O3, and MgO.

[0003] Currently, HG / T 4068-2022, "Industrial Wet-Process Crude Phosphoric Acid," states that P2O5 is analyzed gravimetrically. The analysis process includes accurate sample weighing, chemical digestion, volume determination, titration, precipitation, filtration, drying, and weighing. This method takes 2-3 hours and requires the use of multiple chemical reagents, resulting in high costs, complexity, and high operator skills. Other components, such as SO3, Fe2O3, CaO, Al2O3, and MgO, are analyzed gravimetrically, titrated, or instrumentally. The barium sulfate gravimetric method analyzes sulfur content by converting sulfur in the sample into sulfate ions, which are then precipitated as barium sulfate using barium chloride. This complex analysis process is influenced by numerous factors, requiring instrumental analysis or chemical titration to determine the results. However, the above chemical analysis methods have disadvantages such as complex processes, long analysis time, large number of chemical reagents required, relatively high cost, poor environmental friendliness, and high requirements for operating skills, which makes it difficult to detect the active ingredients and impurities of phosphoric acid products.

[0004] Therefore, there is an urgent need for a phosphate component analysis method with a simple detection process, short analysis time, fewer reagents required, environmental friendliness, good adaptability, and simple operation. Summary of the Invention

[0005] The present invention aims to provide an X-ray fluorescence analysis method for rapidly analyzing phosphoric acid components, addressing the aforementioned shortcomings of phosphoric acid analysis using HG / T 4068-2022, "Industrial Wet-Process Crude Phosphoric Acid," which include complex procedures, long analysis times, the requirement for numerous chemical reagents, relatively high costs, poor environmental friendliness, and high operator skill requirements. The present method utilizes an X-ray fluorescence spectrometer to analyze the composition of a phosphoric acid digestion solution. It can simultaneously analyze the major and trace components in a crude phosphoric acid solution sample, offering advantages such as a short analysis time, a simple procedure, environmental friendliness, and ease of operation.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: An X-ray fluorescence analysis method for rapidly analyzing phosphoric acid components comprises the following steps: S1: Phosphoric acid sample digestion Add nitric acid solution and distilled water to the crude phosphoric acid solution sample, mix and heat to perform digestion treatment, cool to room temperature after the digestion treatment is completed, and filter to obtain the phosphoric acid solution to be tested; S2: Preparation of standard curve Prepare a phosphoric acid standard sample with a chemical value showing a content gradient, and process it according to the digestion treatment step in step S1 to obtain phosphoric acid standard solutions with different contents according to different dilution ratios; The phosphoric acid standard liquid with different contents was tested using an X-ray fluorescence spectrometer to obtain the test intensity of different components at different contents; With the content changes of different components as the horizontal axis and the corresponding test intensity as the vertical axis, draw standard curves of different compositions; S3: Sample testing The phosphoric acid solution to be tested is tested using an X-ray fluorescence spectrometer to obtain the test intensity of different components, and the content of different components in the crude phosphoric acid solution sample is calculated using a standard curve.

[0007] Preferably, in step S1, the crude phosphoric acid solution sample is digested with a nitric acid solution, and the dilution ratio is controlled by the amount of distilled water added, and the dilution ratio is between 2 and 50.

[0008] The impurities contained in the crude phosphoric acid solution sample of the present invention can form insoluble phosphates, and the solution is turbid and is a non-uniform system.

[0009] Preferably, in step S1, the nitric acid solution is prepared by mixing concentrated nitric acid and water in a volume ratio of 1:1.

[0010] A crude phosphoric acid solution sample contains impurities, resulting in turbidity and the generation of precipitation. Direct analysis is prone to errors. The present invention uses a nitric acid digestion method to treat the crude phosphoric acid solution sample, dissolves impurities and precipitates in the sample, and prepares a uniformly dispersed solution system. Furthermore, the added nitric acid components are outside the test range of the X-ray fluorescence spectrometer and do not interfere with the test object in the test spectrum.

[0011] Preferably, in step S1, the crude phosphoric acid solution sample and the nitric acid solution are mixed and then heated on a hot plate until the solution becomes clear, then boiled for 2-3 minutes, taken out, and then cooled to room temperature.

[0012] Preferably, in step S1, the mass m1 of the conical flask is weighed and recorded, a crude phosphoric acid solution sample is taken and placed in the conical flask, the mass m2 of the phosphoric acid is recorded, 1+1 nitric acid is added, and then distilled water is added to mix, the mixture is placed on a hot plate and heated to boil for 2 to 3 minutes, taken out, cooled to room temperature, weighed and recorded, and the mass m3 is obtained to obtain the phosphoric acid solution to be tested. The mass of the phosphoric acid solution to be tested is m3-m1, and the dilution ratio is (m3-m1) / m2.

[0013] The present invention controls the approximate volume of the solution after digestion to achieve a suitable dilution ratio for the digestion solution. Too high a dilution ratio may introduce a dilution error.

[0014] Preferably, in step S2, the detection conditions of the X-ray fluorescence spectrometer are: the atmosphere is helium or air, the spot diameter of the collimator is 10 mm, the target material is Rh, the voltage is 15-50 kV, the dead time of the detector is 30%, and the analysis time is 100 s.

[0015] The present invention adopts an X-ray fluorescence spectrometer to detect the phosphoric acid solution to be detected. The X-ray fluorescence spectrometer can adopt an internal standard correction method to correct the influence of different sample contents, impurity amounts, and test shapes on the test results, thereby improving the applicability of the analysis method.

[0016] The X-ray fluorescence spectrometer in this invention completes a sample analysis in approximately three minutes. It can simultaneously analyze various components, including P2O5, SO3, Fe2O3, CaO, and Al2O3 (MgO requires a helium atmosphere). The instrument can also be configured with a multi-position turntable and set to automatic analysis mode, allowing unattended analysis of batches of samples, improving work efficiency. The analysis time for a batch of six phosphoric acid-digested samples was approximately 18 minutes.

[0017] Preferably, before testing the phosphoric acid standard solution and the phosphoric acid solution to be tested, 5 mL of the phosphoric acid standard solution or 5 mL of the phosphoric acid solution to be tested are respectively placed in a sample cup pre-installed with a PP film, and a lid is placed on the sample cup to isolate it.

[0018] Compared with the prior art, the advantages and beneficial effects of the present invention are: 1. The present invention only takes about 3 minutes to complete the test of a digestion solution sample. Traditional chemical analysis methods require multiple detection methods to analyze together, and it takes 2 to 3 hours to complete the analysis of a sample. The detection method of the present invention is faster and saves time.

[0019] 2. The present invention only requires the addition of nitric acid solution to process the crude phosphoric acid solution sample, without the consumption of other chemical reagents. Traditional chemical analysis methods require the addition of multiple chemical reagents, which increases the analysis cost. The analysis cost of the present invention is lower.

[0020] 3. The present invention uses an X-ray fluorescence spectrometer to analyze the phosphoric acid solution to be tested, and completes the analysis of the content of the main components and impurity components in one analysis. Traditional chemical analysis methods require multiple schemes such as gravimetric analysis, titration, and instrumental analysis to complete the analysis. The present invention can complete the detection of multiple components in one analysis, and the detection and analysis efficiency is higher.

[0021] 4. The detection process of the present invention is simple to operate and does not rely on operating experience. Traditional chemical analysis methods require multiple schemes, the analysis process is complicated, and it relies more on personal operating experience. The operation method of the present invention is simpler.

[0022] 5. In addition to the digestion process, the present invention does not require other chemical reagents and produces almost no other pollution. Traditional chemical analysis methods use multiple reagents, which will increase pollution emissions. The present invention is more environmentally friendly.

[0023] 6. The detection method of the present invention provides a new method for component detection and impurity detection of phosphoric acid samples, which has good factory application effect and good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the standard curve of P2O5; Figure 2 is the standard curve of SO3; Figure 3 is the standard curve of Fe2O3; Figure 4 is the standard curve of CaO; Figure 5 is the standard curve of Al2O3; Figure 6 is the standard curve of MgO; Figure 7 The comparison results of the X-ray fluorescence analysis method and the traditional analysis method for P2O5 in Example 1 are shown; Figure 8 The comparison results of the X-ray fluorescence analysis method and the traditional analysis method for SO3 in Example 1 are shown. DETAILED DESCRIPTION

[0025] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0026] Example 1

[0027] This embodiment provides an X-ray fluorescence analysis method for rapidly analyzing phosphoric acid components, comprising the following steps: S1: Phosphoric acid sample digestion S11: Accurately weigh the mass m1 of a 100ml Erlenmeyer flask (accurate to 0.0001g); S12: Weigh 10 g of crude phosphoric acid solution sample into a 100 ml conical flask and record the mass of phosphoric acid m2 (accurate to 0.0001 g); S13: Then, add 6 ml of 1+1 HNO3 solution to the conical flask. The nitric acid solution is prepared by mixing concentrated nitric acid and distilled water in a volume ratio of 1:1. S14: Then add 10 ml of distilled water to the conical flask; S15: Place the Erlenmeyer flask on a hot plate and heat until the solution is clear and continue boiling for 3 minutes. Remove the flask and cool it to room temperature. S16: Weigh the total mass of the Erlenmeyer flask containing the solution and record the mass m3 (accurate to 0.0001 g); S17: Shake the solution in the conical flask. If insoluble impurities are found, filter to obtain the phosphoric acid solution to be tested, and set aside. The mass of the phosphoric acid solution to be tested is m3-m1.

[0028] S2: Preparation of standard curve Prepare phosphoric acid standard samples with chemical values ​​showing a content gradient, and process them according to the digestion treatment steps in step S1 to obtain phosphoric acid standard solutions with different contents; Before the test, take 5 ml of phosphoric acid standard solution and place it in a sample cup pre-installed with PP film. Cover the sample cup with a lid to isolate it and number the samples. Sample numbers are S1 to S5. The phosphoric acid standard liquid with different contents was tested using an X-ray fluorescence spectrometer to obtain the test intensity of different components at different contents; Taking the Shimadzu EDX-7200 X-ray fluorescence spectrometer as an example, the detection conditions are listed in Table 1: Table 1 Test conditions

[0029] With the content changes of different components as the horizontal axis and the corresponding test intensity as the vertical axis, draw standard curves of different compositions; The content of each component in the phosphoric acid standard sample and the test intensity obtained by the test are shown in Table 2.

[0030] Table 2 Component content and strength test results of phosphoric acid standard sample (helium)

[0031] Figures 1 to 6 A standard curve showing the variation of test intensity of different components with their content.

[0032] S3: Sample testing Before the test, take 5 ml of the phosphoric acid solution to be tested and place it in a sample cup pre-installed with PP film, and cover the sample cup with PE film for isolation; The phosphoric acid solution to be tested is tested using an X-ray fluorescence spectrometer to obtain the test intensity of different components, and the content of different components in the phosphoric acid sample is calculated using a standard curve.

[0033] The test results are: the phosphoric acid sample contains P2O5 23.58%, SO3 1.63%, Fe2O30.46%, CaO 0.47%, Al2O3 0.39%, and MgO 1.06%.

[0034] The same crude phosphoric acid solution sample in Example 1 was analyzed according to the traditional analytical method, and the results of the above traditional chemical analysis method were compared with the test results in Example 1. The comparison results are shown in FIG. Figure 7 and Figure 8 , Figure 7 The blue line in the middle represents the error between the EDX test results and the chemical test results of phosphorus pentoxide, that is, the result of subtracting the chemical test value from the EDX test value. Figure 8 The purple line in the middle is the analytical error between the sample EDX analysis value and the chemical value, the green line CL is the center line, the yellow lines UCL and LCL are error control lines, and the red line is the error reference upper and lower limits.

[0035] The traditional analysis method is: P2O5 analysis method specified in HG / T 4068-2022 "Industrial Wet-process Crude Phosphoric Acid". The test process is as follows: (1) Preparation of test solution Weigh approximately 1g of crude phosphoric acid solution to the nearest 0.0002g and place it into a 100ml beaker. Add 10ml of hydrochloric acid solution and a small amount of water, cover with a watch glass, and boil for 10 minutes. After cooling, transfer the entire amount to a 250ml volumetric flask, add 10ml of hydrochloric acid solution, dilute to the mark with water, and shake well. Dry filter before use, discarding the first 20ml of filtrate to obtain the test solution.

[0036] (2) Preparation of blank test solution Except for not adding the sample, the amount of other reagents added is exactly the same as that used in preparing the test solution, and they are treated at the same time and in the same way as the test solution to obtain a blank test solution.

[0037] (3) Experiment Use a pipette to transfer 10 ml of the test solution and blank solution to a 150 ml beaker. Dilute with water to approximately 100 ml. Add 10 ml of nitric acid solution and 35 ml of quinoline molybdate solution, then cover with a watch glass. Heat the contents of the beaker on a hot plate or in a water bath until they reach 75 ± 5 °C. Hold for 30 seconds, remove, and cool to room temperature (stir 3 to 4 times during cooling). Pre-dry at 180 ± 5 °C for 45 minutes, or stabilize and dry at 250 ± 10 °C for 15 minutes. Remove and allow to cool slightly, then cool to room temperature in a desiccator. Weigh to the nearest 0.0002 g.

[0038] (4) Experimental data processing Phosphoric acid content is calculated as the mass fraction w1 of P2O5: w1=0.03207(m1-m0) / m(10 / 250)×100%; m1: The mass of quinoline precipitate generated in the test solution, g m0: The mass of quinolyl molybdate precipitate generated in the test blank solution, g m: mass of the sample, g.

[0039] from Figure 7 It can be seen that the X-ray fluorescence analysis data of phosphoric acid sample P2O5 are in good agreement with the chemical value.

[0040] from Figure 8 It can be seen that the X-ray fluorescence analysis data of the phosphoric acid sample SO3 is consistent with the chemical value.

[0041] Example 2

[0042] The spiked test was performed on the phosphoric acid solution to be tested in Example 1. The results of the spiked test on the phosphoric acid digestion solution P2O5 are shown in Table 3.

[0043] Table 3 Results of spiked phosphoric acid solution to be tested

[0044] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for rapid analysis of phosphoric acid components by X-ray fluorescence analysis, characterized in that: The following steps are involved: S1: Phosphoric acid sample digestion Add nitric acid solution and distilled water to the crude phosphoric acid solution sample, mix and heat to perform digestion treatment, cool to room temperature after the digestion treatment is completed, and filter to obtain the phosphoric acid solution to be tested; S2: Preparation of standard curve Prepare a phosphoric acid standard sample with a chemical value showing a content gradient, and process it according to the digestion treatment step in step S1 to obtain phosphoric acid standard solutions with different contents according to different dilution ratios; The phosphoric acid standard liquid with different contents was tested using an X-ray fluorescence spectrometer to obtain the test intensity of different components at different contents; With the content changes of different components as the horizontal axis and the corresponding test intensity as the vertical axis, draw standard curves of different compositions; S3: Sample testing The phosphoric acid solution to be tested is tested using an X-ray fluorescence spectrometer to obtain the test intensity of different components, and the content of different components in the crude phosphoric acid solution sample is calculated using a standard curve.

2. The X-ray fluorescence analysis method for rapid analysis of phosphoric acid components according to claim 1, characterized in that: In step S1, the crude phosphoric acid solution sample is digested with a nitric acid solution, and the dilution ratio is controlled by the amount of distilled water added, and the dilution ratio is between 2 and 50.

3. The X-ray fluorescence analysis method for rapid analysis of phosphoric acid components according to claim 1, characterized in that: In step S1, a crude phosphoric acid solution sample and a nitric acid solution are mixed and heated on a hot plate until the solution becomes clear, then boiled for 2-3 minutes, taken out, and then cooled to room temperature.

4. The X-ray fluorescence analysis method for rapid analysis of phosphoric acid components according to claim 1, characterized in that: In step S1, the mass m1 of the conical flask is weighed and recorded, a crude phosphoric acid solution sample is taken and placed in the conical flask, and the mass of the phosphoric acid is recorded m2. A 1+1 nitric acid solution is added, and then distilled water is added to mix. The mixture is placed on a hot plate and heated to boil for 2-3 minutes, then taken out and cooled to room temperature, and the mass m3 is weighed and recorded to obtain the phosphoric acid solution to be tested. The mass of the phosphoric acid solution to be tested is m3-m1, and the dilution ratio is (m3-m1) / m2.

5. The X-ray fluorescence analysis method for rapid analysis of phosphoric acid components according to claim 1, characterized in that: In step S2, the detection conditions of the X-ray fluorescence spectrometer are: atmosphere is helium or air, collimator spot diameter is 10 mm, target material is Rh, voltage is 15-50 kV, detector dead time is 30%, and analysis time is 100 s.

6. The X-ray fluorescence analysis method for rapid analysis of phosphoric acid components according to claim 1, characterized in that: Before testing the phosphoric acid standard solution and the phosphoric acid solution to be tested, 5 mL of the phosphoric acid standard solution or 5 mL of the phosphoric acid solution to be tested were respectively placed in a sample cup pre-installed with PP film, and the sample cup was covered with a lid for isolation.

Images