Method for determining aluminum in ferro-aluminum through ICP-AES
By constructing an ICP-AES method with scandium and yttrium dual internal standard calibration system, the problems of cumbersome operation and insufficient accuracy in detecting aluminum content in aluminum-iron have been solved, realizing rapid and accurate detection in the high aluminum content range, which is suitable for the high precision requirements of steelmaking production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INNER MONGOLIA BAOTOU STEEL UNION
- Filing Date
- 2026-03-20
- Publication Date
- 2026-05-12
AI Technical Summary
In existing technologies, the methods for detecting aluminum content in ferroaluminum are cumbersome to operate and lack sufficient accuracy, failing to meet the rapid response and high precision requirements of steelmaking production. ICP-AES technology is not widely used in the detection of ferroaluminum in steelmaking, and there is a lack of effective testing standards.
A dual internal standard calibration system was adopted, using scandium (Sc) and yttrium (Y) as internal standard elements to construct an ICP-AES method. Through mixed acid dissolution and dilution steps, combined with conventional ICP-AES instruments, accurate detection in the high aluminum content range was achieved.
It achieves rapid and accurate detection in the high aluminum content range, with a relative error of less than ±0.07%, shortens the analysis cycle by 71%~83%, reduces the difficulty and cost of operation, and is suitable for the rapid quality control needs of steelmaking production lines.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of metallurgical analysis technology, and is particularly suitable for the accurate and rapid detection of aluminum-iron ratios of 10.00% to 60.00%. It can be widely used in steelmaking raw material quality control, metallurgical product research and development, and routine analysis by third-party testing institutions. Background Technology
[0002] Ferroaluminum, as an indispensable key deoxidizer and alloying additive in the steelmaking process, directly determines the deoxidation efficiency and steel cleanliness during steelmaking, thus affecting the final steel's mechanical properties (such as strength and toughness), processing properties (such as weldability and plasticity), and corrosion resistance. In the production of high-end steels (such as high-strength structural steel, precision machinery steel, and marine engineering steel), the aluminum content must be strictly controlled within a specific range—too low a content will lead to incomplete deoxidation, excessive oxygen content in the molten steel, and the formation of oxide inclusions; too high a content will cause defects such as increased brittleness and hot working cracking in the steel. Therefore, accurate and rapid aluminum content detection is a core link in ensuring the stability of steelmaking production and the quality of steel products.
[0003] Currently, the mainstream method used in industry is the EDTA titration method specified in the YB / T 4393-2014 standard to determine the aluminum content in aluminum-iron alloys. This method achieves quantitative analysis through chemical titration reaction, but it has significant technical limitations: the operation process is cumbersome, requiring multiple pretreatment steps such as sample dissolution, masking interfering ions, and pH adjustment, with a single analysis cycle lasting 2 to 4 hours, which is difficult to meet the rapid response requirements of steelmaking processes for raw material detection; the titration process relies on manual judgment of the endpoint, which is easily affected by the operator's experience, and matrix elements such as iron and manganese can cause interference, resulting in a relative error of more than 5%, which cannot meet the high precision requirements of high-end steel production.
[0004] However, there are still gaps in the application of existing ICP-AES technology in the detection of aluminum content in ferroaluminum used in steelmaking. There are currently no ICP-AES testing specifications for aluminum content in ferroaluminum in the industry standards. The only ICP testing method for aluminum content in ferroaluminum reported in the existing article cannot be reproduced. The existing instrumental analysis standards mostly focus on minor elements such as calcium and magnesium, which cannot meet the detection requirements of the main parameter of aluminum content.
[0005] Therefore, developing an ICP-AES detection method that is suitable for the matrix characteristics of aluminum-iron alloys used in steelmaking and possesses both accuracy and efficiency, to solve the problems of cumbersome operation and insufficient accuracy of traditional chemical methods and the limitations of existing instrumental methods, has become an urgent need to ensure the quality control of steelmaking raw materials. Based on the above situation, this invention proposes an ICP-AES method for determining aluminum in aluminum-iron alloys. Summary of the Invention
[0006] To address the shortcomings of existing detection methods, the purpose of this invention is to provide an ICP-AES method for determining aluminum in aluminum-iron alloys that is simple to operate, fast to detect, highly accurate, has strong anti-interference capabilities, and requires no special instruments. By introducing scandium (Sc) as the primary internal standard and yttrium (Y) as the alternative internal standard, a dual internal standard calibration system is constructed to solve the matrix effect problem under high aluminum content, achieving accurate detection within the content range of 10.00% to 60.00%. This meets the requirements of rapid quality control in steelmaking production and high precision in the production of high-end steel products, thus broadening the applicability and flexibility of the method.
[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0008] This invention discloses a method for determining aluminum in aluminum-iron alloys using ICP-AES, which is specifically accomplished through the following steps:
[0009] Weigh 0.1000g of aluminum-iron sample. This sample size balances detection sensitivity and matrix concentration, avoiding interference caused by excessive matrix concentration due to excessive sampling. Place the sample in a 300mL beaker, add 20mL of mixed acid, heat at low temperature until the sample is completely dissolved, cool to room temperature, transfer to a 250mL plastic volumetric flask, add water to make up to volume and shake well; aliquot 10mL of the test solution into a 100mL volumetric flask, add water to make up to volume and shake well to obtain the test solution;
[0010] The dilution step involves taking 10 mL to 100 mL after bringing the volume to 250 mL. This can dilute high aluminum content (10% to 60%) to the linear range of 1.0% to 6.0% that is compatible with conventional ICP-AES instruments, while preserving the matrix characteristics and ensuring detection accuracy.
[0011] Preparation of internal standard solutions: Dilute 1000 μg / mL scandium standard solution and 1000 μg / mL yttrium standard solution to 10 μg / mL respectively to prepare them as primary and alternative internal standard stock solutions. Store the stock solutions in a sealed container away from light. The shelf life is 6 months.
[0012] The solutions were nebulized and introduced into the ICP-AES instrument in order of increasing concentration from low to high. The intensity ratio of the spectral lines of aluminum (396.152 nm) to the primary internal standard scandium (361.384 nm) or the alternative internal standard yttrium (371.030 nm) was measured. A calibration curve was plotted with the concentration of the analyte on the x-axis and the intensity ratio on the y-axis. The linear correlation coefficient R² ≥ 0.999 (R² ≥ 0.999 for the primary internal standard and R² ≥ 0.999 for the alternative internal standard).
[0013] Furthermore, the sample is accurate to 0.0002g.
[0014] Furthermore, the volume ratio of the mixed acids is: hydrochloric acid + nitric acid + water = 1 + 1 + 3.
[0015] Furthermore, the primary internal standard element is scandium (45Sc), whose atomization energy is close to that of aluminum (27Al) (Sc atomization energy 6.56eV, Al atomization energy 5.98eV). It is chemically stable, does not interfere in the aluminum-iron matrix, can effectively correct matrix effects and instrument drift, and does not rely on special instrument functions, making it the preferred choice.
[0016] Furthermore, the alternative internal standard element is yttrium (89Y), which is chemically stable (atomic energy 6.22 eV) and has little spectral interference with aluminum. It can be used as an alternative when scandium internal standard reagents are not readily available or when there are special interferences in the matrix, ensuring the flexibility and applicability of the method.
[0017] Furthermore, the linear correlation coefficient R² ≥ 0.999.
[0018] Furthermore, the primary scandium internal standard enables ultra-high precision detection with a relative error within ±0.07%.
[0019] Compared with the prior art, the beneficial technical effects of the present invention are as follows:
[0020] The dual internal standard system has strong adaptability and outstanding risk avoidance capabilities: the primary scandium internal standard achieves ultra-high precision detection (relative error within ±0.07%), while the alternative yttrium internal standard still maintains high accuracy (relative error ≤ ±0.77%). The dual internal standard design solves the problems of difficulty in obtaining single internal standard reagents or special matrix interference, thereby improving the market competitiveness and application stability of the method.
[0021] Leading in accuracy and precision: The relative error of the primary scandium internal standard is ≤ ±0.07%, and the relative error of the alternative yttrium internal standard is ≤ ±0.77%. The RSDs of 11 parallel tests are 0.0346%~0.08% and 0.105%~0.42%, respectively, both far below the industry-allowed error threshold of ±2% and the RSD threshold of 1%. The test results are stable and reliable, and are not affected by differences in instrument model or operator.
[0022] Significant matrix interference suppression effect: The matrix interference suppression rate of the primary scandium internal standard reaches 99%, and that of the alternative yttrium internal standard reaches 92%, which is a significant improvement over the traditional EDTA titration method (65%), and completely solves the problem of interference of high-concentration iron matrix on aluminum detection.
[0023] The analysis efficiency is significantly improved, making it suitable for rapid industrial testing: the analysis cycle is only 30 minutes per batch, which is 71% to 83% shorter than the EDTA titration method (3 to 3.5 hours). It eliminates the need for cumbersome masking and titration steps, enabling rapid testing of batch samples and meeting the rapid quality control needs of steelmaking production lines.
[0024] Simple to operate and environmentally friendly, with low promotion costs: Pretreatment only requires mixing acid for dissolution and dilution, without complex reagents and cumbersome steps, reducing operational difficulty and human error; reagent consumption is only 1 / 5 of that of EDTA titration, significantly reducing waste liquid generation, which is in line with the development trend of green metallurgy; it can be achieved using a conventional commercial ICP-AES instrument, without the need for special parameter adjustments or accessory modifications, and the instrument cost is far lower than that of ICP-MS, making it easy to promote and apply in metallurgical production lines, research institutes and third-party testing institutions. Detailed Implementation
[0025] A method for determining aluminum in aluminum-iron alloys by ICP-AES includes:
[0026] 1. Scope
[0027] This method specifies the determination of aluminum content in aluminum-iron alloys using inductively coupled plasma atomic emission spectrometry (ICP-AES). The determination range is Al: 10.00%–60.00%. Suitable sample types include conventional aluminum-iron samples. This method has no special instrument requirements; any conventional commercial ICP-AES instrument is applicable. It also includes two calibration methods: primary scandium internal standard and alternative yttrium internal standard, adaptable to different application scenarios.
[0028] 2. Method Summary
[0029] A certain amount of aluminum-iron sample is weighed and dissolved in a mixed acid of hydrochloric acid, nitric acid, and water. After dilution, the sample is introduced into a conventional ICP-AES instrument. Scandium (45Sc) is selected as the primary internal standard element or yttrium (89Y) as the alternative internal standard element. The intensity ratio of aluminum spectral lines is determined by the calibration curve method, and the aluminum content is calculated. This method achieves low-interference and high-precision detection under high aluminum content without the need for special instrument support.
[0030] 3. Reagents and Materials
[0031] 3.1 High-purity iron powder (purity ≥ 99.99%, free of aluminum impurities, to avoid matrix interference);
[0032] 3.2 Hydrochloric acid, ρ approx. 1.19 g / mL (analytical grade);
[0033] 3.3 Nitric acid, ρ approx. 1.42 g / mL (analytical grade);
[0034] 3.4 Mixed acid: hydrochloric acid + nitric acid + water = 1 + 1 + 3 (volume ratio), prepare fresh before use;
[0035] 3.5 Aluminum standard solution: 1000 μg / mL (National standard material, GBW (E) 080219), dilute to 100 μg / mL before use;
[0036] 3.6 Primary internal standard solution: Scandium standard solution (1000 μg / mL, GBW (E) 080581), diluted to 10 μg / mL for use, sealed and protected from light, shelf life 6 months;
[0037] 3.7 Alternative internal standard solution: Yttrium standard solution (1000 μg / mL, GBW (E) 080582), diluted to 10 μg / mL for use, sealed and protected from light, shelf life 6 months;
[0038] 3.8 Deionized water, resistivity ≥18.2MΩ・cm (to reduce blank interference).
[0039] 4. Main instruments and testing conditions
[0040] 4.1 Conventional commercial bidirectional or radial observation full-spectrum direct-reading plasma spectrometers (such as the PE Avio500 from the United States, the SPECTRO ARCOS from Germany, and the ICPE-9820 from Shimadzu, Japan) can be equipped with a standard concentric nebulizer and quartz torch tube, without the need for special accessories;
[0041] 4.2 General instrument parameters (can be fine-tuned according to instrument default conditions);
[0042] 4.3 The analytical line wavelengths for the elements to be analyzed are: Al: 396.152 nm; primary internal standard Scandium Sc: 361.384 nm (no interference, stable signal, recognizable by conventional instruments); alternative internal standard Yttrium Y: 371.030 nm (low interference, stable signal, recognizable by conventional instruments); backup spectral lines (if interference occurs): Al 309.271 nm, Sc 424.683 nm, Y 324.228 nm.
[0043] 5. Analysis Steps
[0044] 5.1 Sample quantity: Weigh 0.1000g of the sample, accurate to 0.0002g, and weigh 3 copies in parallel for parallel sample testing.
[0045] 5.2 Sample preparation:
[0046] Place the sample in a 300 mL beaker, add 20 mL of mixed acid, and heat on a 250℃ hot plate at low temperature for about 20 minutes until the solution is clear and free of precipitate. Remove from heat and cool to room temperature. Transfer the solution to a 250 mL plastic volumetric flask, dilute to the mark with deionized water, and shake well. Take 10.00 mL of the above solution into a 100 mL steel volumetric flask, add 1.00 mL of the primary internal standard solution (or alternative internal standard solution), dilute to the mark with deionized water, and shake well to obtain the test solution.
[0047] Preparation of blank solution: 0.0040 g high-purity iron + 20 mL mixed acid + 1.00 mL corresponding internal standard solution, dilute and bring to volume according to the above steps.
[0048] 5.3 Standard Series Preparation:
[0049] Add 0.0040 g of high-purity iron, 10 mL of mixed acid, and 1.00 mL of primary internal standard solution (or alternative internal standard solution) to five 100 mL volumetric flasks, respectively. Then add 0.0 mL, 1.0 mL, 2.0 mL, 3.0 mL, and 6.0 mL of 100 μg / mL aluminum standard solution, respectively. Dilute to the mark with deionized water and shake well to obtain a series of standard solutions with aluminum concentrations of 0.10%, 0.20%, 0.30%, and 0.60% (corresponding to aluminum contents of 10.00%, 20.00%, 30.00%, and 60.00% in the original samples).
[0050] 5.4 Detection: Inject the blank solution → standard series solutions (from low to high concentration) → test solution in the following order. Record the intensity ratio of Al 396.152nm (or spare spectral line) to the corresponding internal standard in each solution. Calculate the aluminum concentration in the test solution based on the calibration curve and convert it to obtain the aluminum content in the original sample.
[0051] 6 Results and Discussion
[0052] 6.1 Accuracy Experiment
[0053] Weigh out aluminum and iron standard samples respectively, and test them according to this method. The test results are shown in Table 1:
[0054] Table 1. Accuracy of Measurement Results (%)
[0055] Aluminum Iron Standard Samples Standard value Measured value YSBC19610-2017 39.55 39.53 GBW(E)010608 46.30 46.33
[0056] The data in the table shows that the detection method has high accuracy.
[0057] 6.2 Precision Experiment
[0058] Eleven aluminum-iron standard samples were weighed and subjected to precision testing according to the above experimental method. The test results are shown in Table 2.
[0059] Table 2 Precision of Measurement Results (%)
[0060] element to be tested average value Standard deviation RSD Al 46.31 3.2% 0.070%
[0061] The above data indicates that the detection method has good precision.
[0062] 7. Conclusion
[0063] This invention, by optimizing pretreatment conditions (mixed acid 1+1+3 dissolution + fractional dilution), constructing a primary scandium (Sc) + alternative yttrium (Y) dual internal standard calibration system, and adapting to conventional instrument parameters, has developed an ICP-AES detection method suitable for aluminum-iron high-aluminum matrices and without special instrument requirements. This solves the technical problems of existing methods, such as cumbersome operation, low accuracy, severe matrix interference, high instrument requirements, and insufficient flexibility.
[0064] This method has a measurement range of 10.00% to 60.00%, is suitable for conventional aluminum and iron samples, has an analysis cycle of only 30 minutes, and can be performed on conventional commercial ICP-AES instruments without the need for special parameter adjustments or accessory modifications.
[0065] The design of the dual internal standard system not only broadens the applicable scenarios of the method, but also forms a unique technical protection point and patent circumvention protection capability. It is easy to operate, environmentally friendly and energy-saving, and has low promotion cost. It can meet the needs of rapid quality control of aluminum and iron raw materials and high precision production of high-end steel in the metallurgical industry, and has extremely high promotion and application value and patent protection value.
[0066] The core innovations and non-obviousness of the technical solution of this invention are as follows:
[0067] 1. The construction of a dual internal standard system for the detection of high aluminum content exhibits non-obviousness.
[0068] In existing technologies, a single internal standard (Sc, Cs, Rh) is used for the detection of low-content elements, without addressing the dual internal standard design for high-content aluminum. Those skilled in the art generally believe that "internal standards are unnecessary for the detection of high-content elements" or that "a single internal standard is sufficient for calibration needs," and are unaware that yttrium (Y) can be used as a suitable alternative internal standard to scandium (Sc) for high-aluminum content detection. This invention breaks through this understanding. Through systematic screening experiments, it was discovered that scandium (Sc) is suitable for high-precision calibration of high-aluminum content, and yttrium (Y) can be used as a substitute in special scenarios, constructing a dual internal standard system. This system not only solves the problem of obtaining single internal standard reagents but also achieves a balance between accuracy and flexibility through the functional division of primary and alternative internal standards. The combined effect cannot be derived from a single internal standard, representing a non-obvious innovation.
[0069] 2. The synergistic adaptation between dual internal standards and conventional instruments is non-obvious.
[0070] In existing technologies, accurate detection of high-content elements often relies on specialized instruments or special modifications. Those skilled in the art generally believe that "accurate detection of high-content elements requires specialized instruments." However, the dual internal standard system of this invention does not rely on special instrument functions; it achieves ultra-high precision through only minor adjustments to conventional instrument parameters, significantly improving accuracy compared to traditional EDTA titration. This synergistic design of "dual internal standards + conventional instruments" breaks through the traditional understanding that "high-content detection requires specialized instruments." Its synergistic effect requires extensive experimental verification combining the characteristics of internal standards, matrix interference patterns, and the performance of conventional instruments, making it a non-obvious technical solution.
[0071] 3. The functional division and patent protection design of the dual internal standard system are non-obvious.
[0072] This invention does not simply list two types of internal standard elements, but rather clarifies the functional positioning of the primary and alternative internal standard elements through experimental data (scandium internal standard for high-precision focusing, and yttrium internal standard for flexible focusing and patent protection scenarios), which differs from existing technologies that do not have clearly defined functional divisions in internal standard selection. The construction of this functional dual internal standard system not only improves the practicality of the method but also broadens the scope of patent protection, avoiding the vulnerability of single internal standards to circumvention. Its design concept and protection logic are beyond the reach of those skilled in the art and constitute a non-obvious innovation.
[0073] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. A method for determining aluminum in aluminum-iron alloys by ICP-AES, characterized in that: This is accomplished through the following steps: Weigh 0.1000g of aluminum-iron sample. This sample size balances detection sensitivity and matrix concentration, avoiding interference caused by excessive matrix concentration due to excessive sampling. Place the sample in a 300mL beaker, add 20mL of mixed acid, heat at low temperature until the sample is completely dissolved, cool to room temperature, transfer to a 250mL plastic volumetric flask, add water to make up to volume and shake well; aliquot 10mL of the test solution into a 100mL volumetric flask, add water to make up to volume and shake well to obtain the test solution; The dilution step involves taking 10 mL to 100 mL after bringing the volume to 250 mL. This can dilute high aluminum content (10% to 60%) to the linear range of 1.0% to 6.0% that is compatible with conventional ICP-AES instruments, while preserving the matrix characteristics and ensuring detection accuracy. Preparation of internal standard solutions: Dilute 1000 μg / mL scandium standard solution and 1000 μg / mL yttrium standard solution to 10 μg / mL respectively to prepare them as primary and alternative internal standard stock solutions. Store the stock solutions in a sealed container away from light. The shelf life is 6 months. The solutions were nebulized and introduced into the ICP-AES instrument in order of increasing concentration from the standard series solutions. The ratio of the spectral intensity of aluminum to that of the primary or alternative internal standard element was measured, and a calibration curve was plotted with the concentration of the element to be measured as the x-axis and the intensity ratio as the y-axis.
2. The method for determining aluminum in aluminum-iron alloys by ICP-AES according to claim 1, characterized in that: The sample was measured to an accuracy of 0.0002 g.
3. The method for determining aluminum in aluminum-iron alloys by ICP-AES according to claim 1, characterized in that: The volume ratio of the mixed acids is: hydrochloric acid + nitric acid + water = 1 + 1 + 3.
4. The method for determining aluminum in aluminum-iron alloys by ICP-AES according to claim 1, characterized in that: The primary internal standard element is scandium, which has an atomization energy close to that of aluminum, stable chemical properties, and no interference in the aluminum-iron matrix. It can effectively correct matrix effects and instrument drift without relying on special instrument functions, making it the preferred choice.
5. The method for determining aluminum in aluminum-iron alloys by ICP-AES according to claim 1, characterized in that: Alternative internal standard element: Yttrium. It is chemically stable and has little interference with the spectral lines of aluminum. It can be used as an alternative when scandium internal standard reagent is not readily available or when there are special interferences in the matrix, ensuring the flexibility and applicability of the method.
6. The method for determining aluminum in aluminum-iron alloys by ICP-AES according to claim 4, characterized in that: The linear correlation coefficient R² ≥ 0.
999.
7. The method for determining aluminum in aluminum-iron alloys by ICP-AES according to claim 4, characterized in that: The primary scandium internal standard enables ultra-high precision detection with a relative error within ±0.07%.