Method for determining titanium in niobium iron

Abstract

The application discloses a method for determining titanium in ferrocolumbite, and belongs to the technical field of steel metallurgical analysis. The method is characterized in that: the ferrocolumbite sample is dissolved by nitric acid and hydrofluoric acid, fluorine is removed by sulfuric acid fuming, and then, dilute ammonium oxalate solution is added for low-temperature evaporation coordination masking of niobium and tantalum to avoid their hydrolysis; the salts are dissolved by hydrochloric acid; and titanium in the sample solution is directly determined by ICP-OES. The application aims to provide a method for determining titanium in ferrocolumbite, which has a wide detection range, solves the problem of niobium matrix interference completely, greatly improves the detection accuracy, simplifies the operation process, significantly improves the detection efficiency, has high detection sensitivity, meets the accurate quality control demand of trace titanium, has good stability, and has strong result reliability.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel metallurgical analysis technology, and particularly relates to a method for determining titanium in ferroniobium. Background Technology

[0002] Ferroniobium can combine with C, N, O, etc. at high temperatures to form stable, high-melting-point compounds, and is infinitely miscible with iron. It is a core microalloying additive in steelmaking, its core functions being to refine steel grains, achieve precipitation strengthening, and simultaneously improve the steel's strength, toughness, and high-temperature performance. It can also deoxidize, fix nitrogen, and desulfurize, improve the weldability of steel, inhibit embrittlement of the weld heat-affected zone, and regulate phase transformation in steel. Furthermore, it enhances the steel's corrosion resistance and resistance to hydrogen embrittlement, making it a key auxiliary material in high-end steel production. Titanium is a critical harmful impurity in ferroniobium, and accurate analysis of its content is crucial for steelmaking.

[0003] To date, the mainstream detection methods and related literature for titanium in ferroniobium are as follows: Spectrophotometry is commonly used in the industry, including the chromotropic acid method and the diantipyrine methane method, corresponding to the national standard GB / T 3654.8-2023. Its disadvantages include strong interference from the niobium matrix, requiring complex masking and separation, cumbersome operation, and precision greatly affected by conditions. Zhang Guiqin et al. studied the "Determination of Titanium in Ferroniobium by Flame Atomic Absorption Spectrometry." Atomic absorption spectrometry has low sensitivity, is suitable for titanium contents of 0.1%–1%, has difficulty eliminating matrix interference, and results in large errors in trace analysis. Li Yan et al. discussed the "Determination of High-Content Titanium in Ferroniobium by Aluminum Reduction-Potassium Dichromate Titration Method," which is suitable for samples with titanium content >1%. However, it is time-consuming to operate, has large endpoint judgment errors, and poor accuracy, and has been gradually replaced. Summary of the Invention

[0004] The purpose of this invention is to provide a method for determining titanium in ferroniobium. Combining modern analytical techniques, the ferroniobium sample is dissolved in nitric acid and hydrofluoric acid, and after defluorination by sulfuric acid fuming, a dilute ammonium oxalate solution is added for low-temperature evaporation to coordinate and mask niobium and tantalum to avoid their hydrolysis. The salts are dissolved in hydrochloric acid. Taking advantage of the wide linear range and high accuracy of ICP-OES, a horizontal observation method is used to detect titanium in ferroniobium, with a detection range of 0.005% to 3.0%.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] This invention discloses a method for determining titanium in ferroniobium, comprising the following steps:

[0007] Step 1: Weigh the sample into a polytetrafluoroethylene beaker, add hydrochloric acid and hydrofluoric acid and dissolve on a low-temperature hot plate; prepare a blank sample at the same time.

[0008] Step 2: After the sample is completely dissolved, add sulfuric acid to generate fumes, remove and cool to room temperature;

[0009] Step 3: Add ammonium oxalate solution to the cooled sample to dissolve the salts, transfer to a tall beaker, evaporate on a low-temperature hot plate, and remove.

[0010] Step 4: Immediately add hydrochloric acid, cool, transfer to a volumetric flask, dilute to volume with high-purity water, and shake well;

[0011] Step 5: Take a certain amount of solution into a volumetric flask, add hydrochloric acid, dilute to the mark with high-purity water, and shake well; wait for the solution to be used in the instrument.

[0012] Table 1 Separation volume

[0013] Titanium content / % Volume of liquid / mL Add acid / mL ≤0.500 0 0 0.500〜3.00 20 4 mL ammonium oxalate (4%) + 15 mL hydrochloric acid

[0014] Step 6: Preparation of standard calibration curve solution

[0015] Titanium single-element standard solution: concentration 1000 μg / mL, sourced from the National Standard Material Center;

[0016] Take 6 20 mL portions of hydrochloric acid into a 100 mL volumetric flask, add 8 mL of 4% ammonium oxalate solution, and then add titanium single-element standard solution to prepare solutions with concentrations of 0%, 0.0050%, 0.025%, 0.100%, 0.500%, and 1.00%, respectively. Dilute to the mark with high-purity water and shake well. This solution is used to prepare a standard curve.

[0017] Step 7: Select spectral lines

[0018] The observation method was horizontal; Ti was analyzed at 334.941 nm.

[0019] Step 8: Plot the calibration curve: Introduce the standard calibration curve solution into the inductively coupled plasma atomic emission spectrometer, measure the signal intensity of Ti ions, and plot the calibration curve with the mass percentage of the element as the abscissa and the emission intensity of the element as the ordinate.

[0020] Step 9: Introduce the sample solution and blank sample solution into the inductively coupled plasma atomic emission spectrometer to measure the signal intensity of Ti ions. Based on the calibration curve of the standard solution with known mass percentage, determine the Ti content in the sample solution.

[0021] The Ti content in the sample is calculated using the following formula:

[0022] W% = (W i -W0)×f

[0023] Where: W - the mass percentage of the element in the sample;

[0024] The mass percentage of W0- element in the blank solution to be tested;

[0025] W i- The mass percentage of the element in the sample to be tested;

[0026] f - dilution factor.

[0027] Furthermore, the measuring instrument was an Optima 5300DV.

[0028] Furthermore, the detection range of this method is: Ti 0.005~3.00%.

[0029] Further, in step 1: weigh 0.2000g of sample into a polytetrafluoroethylene beaker, add 5mL of hydrochloric acid and 2mL of hydrofluoric acid, and dissolve on a low-temperature electric hot plate at 250℃.

[0030] Furthermore, in step 2: after the sample is completely dissolved, add 2 mL of sulfuric acid to fume until the solution is reduced to 1 mL.

[0031] Further, in step 3: add 40 mL of 4% ammonium oxalate solution to the cooled sample to dissolve the salts, transfer it to a 100 mL tall beaker, and evaporate it to a volume of 7-8 mL on a 200°C low-temperature hot plate, then remove it.

[0032] Furthermore, in step 4: immediately add 20 mL of hydrochloric acid, cool, and then transfer to a 100 mL volumetric flask.

[0033] Furthermore, in step 5: a certain amount of solution is taken into a 100mL volumetric flask.

[0034] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0035] 1. Extremely wide detection range, suitable for titanium detection across the entire content gradient: This method has a titanium detection range of 0.005%~3.00%, covering the detection range of existing spectrophotometry (0.01%~1%), atomic absorption spectrometry (0.1%~1%), and volumetric methods (>1%). It can meet the accurate determination of trace, routine, and medium-to-high content titanium in niobium iron in one step, without the need to change the detection method according to the titanium content, and has extremely strong adaptability.

[0036] 2. Completely solves the problem of niobium matrix interference, significantly improving detection accuracy: Addressing the industry pain point that niobium and tantalum are easily hydrolyzed and strongly interfere with titanium detection, an innovative sulfuric acid fuming defluorination + ammonium oxalate low-temperature evaporation coordination masking process is adopted. This effectively suppresses niobium and tantalum hydrolysis and eliminates their matrix interference on titanium determination. Simultaneously, the optimal Ti 334.941 nm analytical line, combined with a horizontal observation mode and a matrix-matched standard curve preparation method, further avoids spectral interference. Compared to the cumbersome masking and separation of spectrophotometry and the difficulty in eliminating matrix interference in atomic absorption spectrometry, this method provides higher accuracy and precision, and lower blank interference. No complex separation or manual visual judgment is required; batch samples can be rapidly pre-processed. Combined with the automated detection characteristics of ICP-OES instruments, the detection cycle for a single sample is significantly shortened, and the detection efficiency is far superior to traditional methods.

[0037] 3. Simplified and efficient operation process, significantly improving detection efficiency: Existing spectrophotometric methods require multiple masking and color development processes and are subject to strict limitations such as temperature and pH; volumetric methods are time-consuming and have large errors in endpoint determination; atomic absorption methods involve complex pretreatment and instrument debugging; this invention standardizes the sample dissolution, defluorination, masking, and volume adjustment processes.

[0038] 4. High detection sensitivity, meeting the requirements for precise quality control of trace titanium: The lowest detection limit of this method is 0.005%, which is far superior to atomic absorption spectrometry (0.1%), and can accurately determine trace titanium impurities in niobium iron.

[0039] 5. The method exhibits good stability and high reliability: By employing blank sample cascading, matrix-matched standard curve preparation, and optimized specific spectral lines and observation methods, various errors caused by reagents, instruments, and the matrix are effectively avoided. This results in superior repeatability, stability, and recovery rate of the detection data, providing accurate and reliable titanium content data support for steel smelting. Multiple tests on ferroniobium samples have demonstrated excellent application results, making this invention suitable for widespread adoption within the metallurgical industry. Detailed Implementation

[0040] In this embodiment of the invention, the preferred reagents used are:

[0041] Hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid: analytical grade; ammonium oxalate solution (4%)

[0042] Titanium single-element standard solution: concentration of 1000 μg / mL, sourced from the National Standard Material Center.

[0043] PTFE beaker; 100mL tall beaker; 100mL volumetric flask; argon: argon purity ≥99.9%; compressed air.

[0044] The preferred inductively coupled plasma atomic emission spectrometer is the PE Optima 5300DV; the observation method is horizontal observation.

[0045] Sample Analysis

[0046] Decomposed sample

[0047] Take 0.2000g of sample in a polytetrafluoroethylene beaker, add 5mL of hydrochloric acid and 2mL of hydrofluoric acid, and dissolve on a 250℃ low-temperature hot plate. After the sample is completely dissolved, add 2mL of sulfuric acid to fume until the solution is reduced to 1mL. Remove from heat and cool to room temperature. Add 40mL of ammonium oxalate solution (4%) to the cooled sample to dissolve the salts, transfer to a 100mL tall beaker, and evaporate on a 200℃ low-temperature hot plate until the volume is reduced to 7-8mL. Remove from heat. Immediately add 20mL of hydrochloric acid, cool, and transfer to a 100mL volumetric flask. Dilute to volume with high-purity water and mix well. Prepare a blank sample simultaneously.

[0048] Separation

[0049] A portion of the solution is transferred to a 100mL volumetric flask, hydrochloric acid is added, and the solution is diluted to the mark with high-purity water and shaken well. Ready to run on the instrument.

[0050] Table 2. Separation volume

[0051]

[0052] Preparation of standard calibration curve solution

[0053] Titanium single-element standard solution: concentration of 1000 μg / mL, sourced from the National Standard Material Center.

[0054] Take 6 portions (20 mL each) of hydrochloric acid into 100 mL volumetric flasks, add 8 mL of ammonium oxalate (4%), and then add titanium single-element standard solution to prepare solutions with concentrations of 0%, 0.0050%, 0.025%, 0.100%, 0.500%, and 1.00%, respectively. Dilute to the mark with high-purity water and shake well. This solution is used to prepare a standard curve.

[0055] Plot the calibration curve:

[0056] Ti 334.941 nm was used as the analytical line.

[0057] The standard calibration curve solution was introduced into an inductively coupled plasma atomic emission spectrometer to measure the signal intensity of Ti ions. The calibration curve was plotted with the mass percentage of the element on the x-axis and the emission intensity of the element on the y-axis.

[0058] Measurement:

[0059] The sample solution and blank sample solution are introduced into an inductively coupled plasma atomic emission spectrometer to measure the signal intensity of Ti ions. Based on the calibration curve of the standard solution with known mass percentage, the content of Ti in the sample solution is determined.

[0060] The Ti content in the sample is calculated using the following formula:

[0061] W% = (W i -W0)×f

[0062] Where: W - the mass percentage of the element in the sample;

[0063] The mass percentage of W0- element in the blank solution to be tested;

[0064] W i - The mass percentage of the element in the sample to be tested;

[0065] f - Dilution factor

[0066] The detection range of this method is: Ti 0.005~3.00%.

[0067] Example 1

[0068] The working curve was prepared according to the above method. The correlation coefficient r of Ti was 0.99993. Eleven blank solutions were prepared according to the experimental method and measured three times. According to the detection limit formula defined by the International Union of Pure and Applied Chemistry (IUPAC) CL=3Sb / k (Sb is the standard deviation of the blank and k is the slope of the corresponding calibration curve), the detection limit of Ti was calculated to be 0.024 μg / mL.

[0069] Example 2

[0070] To evaluate the accuracy of the method, four niobium-iron standard substances were measured four times, and a spiked recovery test was conducted. The difference between the measured value and the certified value was less than the uncertainty of the standard substance, and the spiked recovery rate was 97% to 101%, which met the requirements of analytical chemistry. The results are shown in Table 3.

[0071] Table 3 Accuracy Test

[0072]

[0073] Example 3. Method Precision

[0074] Under the selected experimental method, samples 1#, 2#, 3#, and 4# of niobium iron were weighed, and eight sample solutions were prepared in parallel for each sample to investigate precision. The standard deviation (SD) and relative standard deviation (RSD) of the determination results for each component were calculated. The relative standard deviation (RSD) was less than 2.0%, which meets the requirements of analytical chemistry. The results are shown in Table 4.

[0075] Table 4 Precision Test Results

[0076]

[0077] Therefore, through the verification of the above implementation examples, it can be seen that the present invention uses ICP-OES to determine titanium in ferroniobium, with ammonium oxalate to eliminate interference from niobium and tantalum, achieving a Ti detection range of 0.005%–3.0%. The present invention has demonstrated good application results through multiple tests on ferroniobium samples. The present invention features a wide linear range, high sensitivity, simple operation, fast analysis speed, and accurate and reliable analytical results, providing reliable data for the detection of titanium in ferroniobium.

[0078] 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 titanium in ferroniobium, characterized in that, Includes the following steps: Step 1: Weigh the sample into a polytetrafluoroethylene beaker, add hydrochloric acid and hydrofluoric acid and dissolve on a low-temperature hot plate; prepare a blank sample at the same time. Step 2: After the sample is completely dissolved, add sulfuric acid to generate fumes, remove and cool to room temperature; Step 3: Add ammonium oxalate solution to the cooled sample to dissolve the salts, transfer to a tall beaker, evaporate on a low-temperature hot plate, and remove. Step 4: Immediately add hydrochloric acid, cool, transfer to a volumetric flask, dilute to volume with high-purity water, and shake well; Step 5: Take a certain amount of solution into a volumetric flask, add hydrochloric acid, dilute to the mark with high-purity water, and shake well; wait for the solution to be used in the instrument. Step 6: Preparation of standard calibration curve solution Titanium single-element standard solution: concentration 1000 μg / mL, sourced from the National Standard Material Center; Take 6 20 mL portions of hydrochloric acid into a 100 mL volumetric flask, add 8 mL of 4% ammonium oxalate solution, and then add titanium single-element standard solution to prepare solutions with concentrations of 0%, 0.0050%, 0.025%, 0.100%, 0.500%, and 1.00%, respectively. Dilute to the mark with high-purity water and shake well. This solution is used to prepare a standard curve. Step 7: Select spectral lines The observation method was horizontal; Ti was analyzed at 334.941 nm. Step 8: Plot the calibration curve: Introduce the standard calibration curve solution into the inductively coupled plasma atomic emission spectrometer, measure the signal intensity of Ti ions, and plot the calibration curve with the mass percentage of the element as the abscissa and the emission intensity of the element as the ordinate. Step 9: Introduce the sample solution and blank sample solution into the inductively coupled plasma atomic emission spectrometer to measure the signal intensity of Ti ions. Based on the calibration curve of the standard solution with known mass percentage, determine the Ti content in the sample solution. The Ti content in the sample is calculated using the following formula: W%=(W i -W0)×f Where: W - the mass percentage of the element in the sample; The mass percentage of W0- element in the blank solution to be tested; W i - The mass percentage of the element in the sample to be tested; f - dilution factor.

2. The method for determining titanium in ferroniobium according to claim 1, characterized in that, The measuring instrument was an Optima 5300DV.

3. The method for determining titanium in ferroniobium according to claim 1, characterized in that, The detection range of this method is: Ti 0.005~3.00%.

4. The method for determining titanium in ferroniobium according to claim 1, characterized in that, Step 1: Weigh 0.2000g of the sample into a polytetrafluoroethylene beaker, add 5mL of hydrochloric acid and 2mL of hydrofluoric acid, and dissolve them on a 250℃ low-temperature hot plate.

5. The method for determining titanium in ferroniobium according to claim 4, characterized in that, Step 2: After the sample is completely dissolved, add 2 mL of sulfuric acid to fume until the solution is reduced to 1 mL.

6. The method for determining titanium in ferroniobium according to claim 1, characterized in that, Step 3: Add 40 mL of 4% ammonium oxalate solution to the cooled sample to dissolve the salts, transfer it to a 100 mL tall beaker, and evaporate it to a volume of 7-8 mL on a 200°C low-temperature hot plate, then remove it.

7. The method for determining titanium in ferroniobium according to claim 6, characterized in that, Step 4: Immediately add 20 mL of hydrochloric acid, cool, and then transfer to a 100 mL volumetric flask.

8. The method for determining titanium in ferroniobium according to claim 7, characterized in that, Step 5: Take a certain amount of the solution into a 100mL volumetric flask.

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