Method for determining acid-soluble aluminum in a coil of sheet

Abstract

This application relates to the field of testing technology for acid-soluble aluminum in steel coils, and particularly to a method for determining acid-soluble aluminum in steel coils. The method includes: dissolving a steel coil sample in stages using different reagents, followed by dilution to obtain a steel coil sample solution; preparing a series of aluminum standard solutions; and then analyzing the steel coil sample solution and the series of aluminum standard solutions using inductively coupled plasma atomic emission spectrometry to determine the acid-soluble aluminum content in the steel coil sample. This application solves the technical problems of existing photoelectric direct-reading spectrometry methods, which struggle to directly detect the surface of solid samples to represent the entire sample's acid-soluble aluminum content (as acid-soluble aluminum in steel coils exhibits obvious stratification), and the complexity of wet chemical methods for determining acid-soluble aluminum in steel coils.

Description

Technical Field

[0001] This application relates to the field of testing technology for acid-soluble aluminum in steel coils, and more particularly to a method for determining acid-soluble aluminum in steel coils. Background Technology

[0002] The control range of acid-soluble aluminum in steel coils is relatively narrow, requiring high-precision detection.

[0003] Data analysis revealed significant stratification of acid-soluble aluminum in the sheet rolls, with higher content in the central areas. Since process requirements dictate that acid-soluble aluminum test data represent the entire sample thickness, direct-reading photoelectric spectroscopy cannot accurately represent the acid-soluble aluminum content of the entire sample. The national standard chemical testing method for acid-soluble aluminum uses colorimetry, which is cumbersome, requires numerous reagents, and cannot meet the needs of rapid testing on production lines. Dissolving samples with perchloric acid is also problematic due to its lengthy testing process; perchloric acid is a potentially explosive chemical, difficult to procure, expensive, and poses a fire risk with prolonged use in fume hoods. Summary of the Invention

[0004] This application provides a method for determining acid-soluble aluminum in steel plates and coils, which solves the technical problems of existing photoelectric direct-reading spectrometry, which makes it difficult to directly detect the surface of solid samples to represent the acid-soluble aluminum content of the entire sample (acid-soluble aluminum in steel plates and coils exhibits obvious stratification), and the relatively complex wet chemical determination method for acid-soluble aluminum in steel plates and coils.

[0005] In a first aspect, this application provides a method for determining acid-soluble aluminum in steel coils, the method comprising:

[0006] The outer skin of the sheet roll is removed, followed by punching and cleaning to obtain a sheet roll sample;

[0007] The plate roll sample was dissolved in stages using different reagents and then diluted to obtain a plate roll sample solution.

[0008] A series of aluminum standard solutions were prepared, and then inductively coupled plasma atomic emission spectrometry was used to measure the spectral intensity of aluminum in the series of aluminum standard solutions to obtain the spectral intensity of aluminum in the series of aluminum standard solutions, and working curves of aluminum in the series of aluminum standard solutions were plotted.

[0009] The inductively coupled plasma atomic emission spectrometry (ICP-AES) method was used to measure the spectral intensity of aluminum in the plate and coil sample solution to obtain the spectral intensity of aluminum in the plate and coil sample solution. Based on the working curve of aluminum in the series of aluminum standard solutions, the acid-soluble aluminum content in the plate and coil sample was obtained.

[0010] Optionally, the step of dissolving the plate-roll sample in stages using different reagents, followed by dilution to obtain a plate-roll sample solution, includes:

[0011] Nitric acid is added to the plate roll sample to carry out a first stage of dissolution, resulting in a first solution;

[0012] Ammonium persulfate is added to the first solution to carry out a second stage of dissolution, resulting in a second solution.

[0013] Hydrochloric acid was added to the second dissolving solution for a third stage of dissolution, followed by dilution to obtain the plate roll sample solution.

[0014] Optionally, the nitric acid has a volume density of 1.42 g / mL.

[0015] Optionally, the amount of nitric acid added is 3 to 10 ml.

[0016] Optionally, the concentration of the ammonium persulfate is 10% by weight.

[0017] Optionally, the amount of ammonium persulfate added is 3 to 10 ml.

[0018] Optionally, the hydrochloric acid has a volume density of 1.19 g / mL.

[0019] Optionally, the amount of hydrochloric acid added is 3 to 5 ml.

[0020] Optionally, the process parameters for the inductively coupled plasma atomic emission spectrometry include:

[0021] The test solution introduction pump speed is 100-125 rpm, the radio frequency power is 1100-1200 W, the observation height is 12-15 mm, the test solution lifting rate is 0.5-1.2 L / min, and the light intensity acquisition time is 10-30 s.

[0022] Optionally, the weight of the sheet roll sample is 0.45 to 0.55 g.

[0023] The technical solutions provided in this application have the following advantages compared with the prior art:

[0024] The method for determining acid-soluble aluminum in the plate roll provided in this application involves surface treatment of the plate roll, followed by dissolution and dilution with different reagents to obtain a plate roll sample solution. Next, a series of aluminum standard solutions are prepared. Then, inductively coupled plasma atomic emission spectrometry (ICP-AES) is used to determine the acid-soluble aluminum content in the plate roll sample. This method reduces the number of sample dissolution steps, simplifies operation, improves work efficiency, and reduces energy and chemical consumption. It features short analysis time, high speed, high accuracy, and a linear correlation coefficient of over 99.9% between the tested sample and the standard working curve. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic flowchart of a method for determining acid-soluble aluminum in a sheet roll, provided as an embodiment of this application. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0030] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the orientation shown in the accompanying drawings. Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to."

[0031] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any actual relationship or order between these entities or operations. In this document, "and / or" describes the association between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can both represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0032] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0033] Firstly, this application provides a method for determining acid-soluble aluminum in steel coils; please refer to [link to relevant documentation]. Figure 1 The method includes:

[0034] S1. Remove the outer skin of the sheet roll, then punch and clean it to obtain a sheet roll sample;

[0035] Specifically, the sample is fixed with a special fixture, the plate roll is held in place by the fixture, and placed in a milling machine to remove the skin. The upper and lower skins are removed, and the sample is punched out into particles using a punching machine. The resulting sample particles are then ultrasonically cleaned with anhydrous ethanol and set aside for use.

[0036] In some embodiments, the weight of the sheet roll sample is 0.45 to 0.55 g.

[0037] The positive effects of controlling the weight of the plate roll sample to 0.45–0.55 g: Because the sample is granular, the weighing mass cannot be precisely controlled to 0.5000 g. If the weight of the plate roll sample is too high or too low, it will cause the calibration coefficient to be too large or too small, resulting in some data deviation. Therefore, the weighing weight of the plate roll sample can be controlled between 0.45 and 0.55 g.

[0038] S2. The plate roll sample is dissolved in stages using different reagents, and then diluted to obtain a plate roll sample solution;

[0039] In some embodiments, the step of dissolving the plate roll sample in stages using different reagents, followed by dilution to obtain a plate roll sample solution, includes:

[0040] Nitric acid is added to the plate roll sample to carry out a first stage of dissolution, resulting in a first solution;

[0041] Ammonium persulfate is added to the first solution to carry out a second stage of dissolution, resulting in a second solution.

[0042] Hydrochloric acid was added to the second dissolving solution for a third stage of dissolution, followed by dilution to obtain the plate roll sample solution.

[0043] The positive effects of using different reagents to dissolve the plate roll sample in stages: Directly adding a mixture of hydrochloric acid and nitric acid results in a violent reaction, causing sample splashing and data deviation.

[0044] The positive effects of using nitric acid for the initial dissolution: While ordinary acids dissolve iron relatively slowly, the oxidizing properties of nitric acid accelerate the dissolution process. Hydrochloric acid quickly forms an oxide film on the steel sample surface, while nitric acid does not, and the resulting nitrates dissolve rapidly.

[0045] The positive effects of using ammonium persulfate for secondary dissolution: Adding ammonium persulfate can increase the oxidizing capacity and further dissolve the aluminum in the steel sample that is not easily dissolved.

[0046] The positive effects of using hydrochloric acid for the third dissolution: hydrochloric acid reacts with nitric acid to form aqua regia, which thoroughly dissolves the sample.

[0047] In some embodiments, the nitric acid has a volume density of 1.42 g / mL.

[0048] In some embodiments, the amount of nitric acid added is 3 to 10 ml.

[0049] The advantages of controlling the bulk density of nitric acid to 1.42 g / mL and adding 3–10 ml of nitric acid are as follows: Use analytical grade nitric acid for heating and dissolution. Using impure acid will result in a higher aluminum content, leading to inaccurate data. Adding an appropriate amount of nitric acid ensures complete sample dissolution. Too much nitric acid will cause incomplete dissolution, resulting in lower data, as inductively coupled plasma atomic emission spectrometry (ICP-AES) requires maintaining a solution acidity of 5%–10%, and higher acidity leads to a more significant matrix effect. Too little nitric acid will result in incomplete sample dissolution, leading to lower data. Specifically, the amount of nitric acid used can be 3 ml, 7 ml, or 10 ml.

[0050] In some embodiments, the concentration of the ammonium persulfate is 10% by weight.

[0051] In some embodiments, the amount of ammonium persulfate added is 3 to 10 ml.

[0052] Controlling the ammonium persulfate concentration to 10% by weight and the addition amount to 3–10 ml has the following positive effects: Adding an appropriate amount of ammonium persulfate oxidizes the poorly soluble aluminum in the sample. If too much ammonium persulfate is added, it decomposes upon heating into ammonia and ammonium sulfate, which may produce ammonia gas harmful to health, and the matrix effect will be more pronounced. If too little ammonium persulfate is added, incomplete oxidation may occur. Specifically, the amount of ammonium persulfate used can be 3 ml, 7 ml, 10 ml, etc.

[0053] In some embodiments, the hydrochloric acid has a volume density of 1.19 g / mL.

[0054] In some embodiments, the amount of hydrochloric acid added is 3 to 5 ml.

[0055] The positive effects of controlling the volume density of hydrochloric acid to 1.19 g / mL and adding 3–5 ml of hydrochloric acid include: using analytical grade concentrated hydrochloric acid for heating and dissolution. However, there are also negative effects on the numerical values: using impure acid, such as a high aluminum content, can lead to inaccurate data. Adding an appropriate amount of hydrochloric acid to completely dissolve the sample is crucial. Adding too much hydrochloric acid can cause incomplete reaction, reducing data accuracy, as inductively coupled plasma atomic emission spectrometry (ICP-AES) requires maintaining a solution acidity of 5%–10%, and higher acidity leads to more significant matrix effects. Adding too little hydrochloric acid can also result in incomplete reaction and reduced data accuracy. Specifically, the amount of hydrochloric acid used can be 3 ml, 4 ml, or 5 ml.

[0056] S3. Prepare a series of aluminum standard solutions, and then use inductively coupled plasma atomic emission spectrometry to measure the spectral intensity of aluminum in the series of aluminum standard solutions, and plot the working curve of aluminum in the series of aluminum standard solutions.

[0057] Specifically, S3 above includes: preparing an aluminum standard solution with a concentration of 50 μg / ml: transfer 5 ml of aluminum standard solution (1000 μg / ml) into a 100 ml volumetric flask, dilute with water to the mark, and mix well;

[0058] Weigh 6 portions (0.45 g) of pure iron, similar in content to the sample, into a 300 ml beaker. Add dimethyl methacrylate (DMD) water, add nitric acid, and heat at low temperature until bubbling stops. Remove from heat and let cool slightly. Add ammonium persulfate and heat slowly until the excess ammonium persulfate is completely decomposed. Add hydrochloric acid and continue heating until the sample is completely dissolved. Remove from heat and cool to room temperature. Transfer the solution to a 100 ml volumetric flask. Add 0.00 ml, 1.00 ml, 2.00 ml, 3.00 ml, 4.00 ml, and 5.00 ml of a 50 g / ml aluminum standard solution, respectively. Dilute to the mark with water and mix well. Calculate the corresponding aluminum mass percentages: 0.00%, 0.010%, 0.020%, 0.030%, 0.040%, and 0.050%, respectively.

[0059] Six volumetric flasks containing aluminum standard solution were introduced into an inductively coupled plasma atomic emission spectrometer (ICP-AES) for measurement. The ICP-AES automatically plotted a standard working curve for the aluminum standard solution.

[0060] S4. The inductively coupled plasma atomic emission spectrometry method is used to measure the spectral intensity of aluminum in the plate and coil sample solution to obtain the spectral intensity of aluminum in the plate and coil sample solution, and the acid-soluble aluminum content in the plate and coil sample is obtained according to the working curve of aluminum in the series of aluminum standard solutions.

[0061] In some embodiments, the process parameters of the inductively coupled plasma atomic emission spectrometry include:

[0062] The test solution introduction pump speed is 100-125 rpm, the radio frequency power is 1100-1200 W, the observation height is 12-15 mm, the test solution lifting rate is 0.5-1.2 L / min, and the light intensity acquisition time is 10-30 s.

[0063] The advantages of using inductively coupled plasma atomic emission spectrometry (ICP-AES) include: faster analysis speed, fewer reagents required, better stability, higher precision and accuracy, and less spectral background interference compared to wet chemical analysis methods. The advantages of controlling the process parameters of ICP-AES are also discussed: spectral line intensity increases with increasing power, but the signal-to-background ratio decreases after a certain point. Too low a power level affects the excitation of the analyte; too high a power level increases background intensity, consumes more energy, and may burn out the torch. Therefore, a comprehensive consideration of the RF power is 1100–1200 W. Insufficient sample injection volume results in insufficient atomized sample gas entering the plasma per unit time, leading to inadequate detection sensitivity. However, excessive injection volume affects the atomization efficiency of the solution and wastes sample.

[0064] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0065] Example

[0066] Method for determining acid-soluble aluminum in sheet coils:

[0067] S1. Remove the outer skin of the sheet roll, then punch and clean it to obtain a sheet roll sample;

[0068] Specifically, the sample is fixed with a special fixture, the plate roll is held in place by the fixture, and then placed in a milling machine to remove the outer skin. The upper and lower skins are removed, and the sample is punched out into particles using a punching machine. The resulting sample particles are ultrasonically cleaned with anhydrous ethanol for 3 minutes before use.

[0069] S2. The plate roll sample is dissolved in stages using different reagents, and then diluted to obtain a plate roll sample solution;

[0070] Weigh the sample and record the actual weight. Dissolve the sample particles in a 300ml beaker, add secondary water, add nitric acid and heat at low temperature until bubbling stops. Remove and cool, add ammonium persulfate and heat slowly until the excess ammonium persulfate is completely decomposed. Add hydrochloric acid and continue heating until the sample is completely decomposed. Remove and cool to room temperature, transfer to a 100ml volumetric flask, dilute with water to the mark, shake well, and prepare for testing.

[0071] S3. Prepare a series of aluminum standard solutions, and then use inductively coupled plasma atomic emission spectrometry to measure the spectral intensity of aluminum in the series of aluminum standard solutions, and plot the working curve of aluminum in the series of aluminum standard solutions.

[0072] Specifically, to prepare an aluminum standard solution with a concentration of 50 μg / ml: transfer 5 ml of aluminum standard solution (1000 μg / ml) into a 100 ml volumetric flask, dilute with water to the mark, and mix well;

[0073] Weigh six portions (0.45 g) of pure iron, approximately equal to the sample content, into a 300 ml beaker. Add dimethyl methacrylate (DMD) water, add nitric acid, and heat at low temperature until bubbling stops. Remove from heat and cool. Add ammonium persulfate and heat slowly until excess ammonium persulfate is completely decomposed. Add hydrochloric acid and continue heating until the sample is completely dissolved. Remove from heat and cool to room temperature. Transfer the solution to a 100 ml volumetric flask. Add 0.00 ml, 1.00 ml, 2.00 ml, 3.00 ml, 4.00 ml, and 5.00 ml of a 50 g / ml aluminum standard solution, respectively. Dilute to the mark with water and mix well. Calculate the corresponding aluminum mass percentages: 0.00%, 0.010%, 0.020%, 0.030%, 0.040%, and 0.050%, respectively.

[0074] Six volumetric flasks containing aluminum standard solution were introduced into an inductively coupled plasma atomic emission spectrometer (ICP-AES) for measurement. The ICP-AES automatically plotted a standard working curve for the aluminum standard solution.

[0075] S4. The inductively coupled plasma atomic emission spectrometry method is used to measure the spectral intensity of aluminum in the plate and coil sample solution to obtain the spectral intensity of aluminum in the plate and coil sample solution, and the acid-soluble aluminum content in the plate and coil sample is obtained according to the working curve of aluminum in the series of aluminum standard solutions.

[0076] The dissolved sample solution was introduced into an inductively coupled plasma atomic emission spectrometer (ICP-AES) for measurement. The intensity of the test solution was calculated by ICP-AES based on the standard working curve of aluminum to determine the acid-soluble aluminum content in the measured plate. Each sample was exposed and measured three times, followed by rinsing with 2% hydrochloric acid for 20 seconds and then with clean water for 10 seconds. Specific process parameters are shown in Table 1.

[0077] Table 1. Process parameters for determining acid-soluble aluminum in sheet rolls in the examples.

[0078]

[0079] Table 2. Process parameters for determining acid-soluble aluminum in comparative sample coils.

[0080]

[0081] Table 2 shows the process parameters for determining acid-soluble aluminum in the coils of Comparative Examples 1-3. The results analyzed using the given conditions are basically consistent with the accuracy and precision of the results obtained by the Chromium Azurite S spectrophotometric method, nitric acid + hydrochloric acid + perchloric acid analysis methods. Considering factors such as analysis time, quantity of reagents used, and environmental protection, the nitric acid + ammonium persulfate + hydrochloric acid method used in the examples is faster and uses more environmentally friendly reagents.

[0082] The method described in this application also has the following beneficial effects:

[0083] (1) It solved the problems of the danger of using and the difficulty of procuring perchloric acid as an easily explosive hazardous chemical;

[0084] (2) Compared with the colorimetric method, the sample dissolution method is simple to operate, has high operational safety, is easy to promote and use, and meets the needs of rapid testing in production lines.

[0085] (3) It solves the problem that direct detection of solid sample surface by photoelectric direct reading spectroscopy is difficult to represent the acid-soluble aluminum content of the entire sample (the acid-soluble aluminum in the plate roll has obvious stratification).

[0086] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for determining acid-soluble aluminum in sheet rolls, characterized in that, The method includes: The outer skin of the sheet roll is removed, followed by punching and cleaning to obtain a sheet roll sample; Nitric acid was added to the plate roll sample to carry out the first stage of dissolution, resulting in a first solution. The volume density of the nitric acid was 1.42 g / mL, and the amount of nitric acid added was 3 to 10 ml. Ammonium persulfate is added to the first solution to carry out a second stage of dissolution, resulting in a second solution. The concentration of ammonium persulfate is 10% by weight, and the amount of ammonium persulfate added is 3 to 10 ml. Hydrochloric acid was added to the second dissolving solution for the third stage of dissolution, followed by dilution to obtain a plate roll sample solution. The volume density of hydrochloric acid was 1.19 g / mL, and the amount of hydrochloric acid added was 3-5 ml. A series of aluminum standard solutions were prepared, and then inductively coupled plasma atomic emission spectrometry was used to measure the spectral intensity of aluminum in the series of aluminum standard solutions to obtain the spectral intensity of aluminum in the series of aluminum standard solutions, and working curves of aluminum in the series of aluminum standard solutions were plotted. The inductively coupled plasma atomic emission spectrometry (ICP-AES) method was used to measure the spectral intensity of aluminum in the plate and coil sample solution to obtain the spectral intensity of aluminum in the sample solution. Based on the working curve of aluminum in the series of aluminum standard solutions, the acid-soluble aluminum content in the plate and coil sample was obtained.

2. The method according to claim 1, characterized in that, The process parameters for the inductively coupled plasma atomic emission spectrometry method include: The test solution introduction pump speed is 100–125 rpm, the radio frequency power is 1100–1200 W, and the observation height is 12–15 mm. The liquid injection rate was 0.5–1.2 L / min, and the light intensity collection time was 10–30 s.

3. The method according to claim 1, characterized in that, The weight of the sheet / coil sample is 0.45–0.55 g.

Images