GB/T 4333.9-1988 Chemical analysis methods for ferrosilicon - Determination of aluminum content by flame atomic absorption spectrometry
Some standard content:
National Standard of the People's Republic of China
Method for chemical analysis of ferrositicanThe flame atomic absorptlon spectromctric methodfor the determination of aluminium contentUDC. 669.15'782
:543-06
GB 4333.9: 88
This standard is equivalent to the international standard 1S04139-1979 Ferrosilicon--Determination of aluminium content--·Fire atomic absorption spectrometry" 1 Subject content and scope of application
This standard specifies the determination of aluminium content by flame atomic absorption spectrometry. This standard is applicable to the determination of aluminium content in ferrosilicon, with a determination range of 1.05%~5.0% 2 Method summary
The sample is dissolved in nitric acid, hydrofluoric acid and peroxy acid, and the solution is evaporated until chloric acid smoke is separated. The residue is melted with a mixture of sodium carbonate and boric acid, and the molten residue is dissolved in the main solvent. The solution is absorbed into a nitrous oxide-acetylene flame and the lead is determined by atomic absorption spectroscopy through the 309.3 μm spectral line emitted by an aluminum hollow electrode lamp.
3 ReagentsbZxz.net
3.1 Anhydrous sodium carbonate.
3.2 Boric acid crystals.
3. 3 Nitric acid (p 1. 42 g/mL)
3. 4 Hydrofluoric acid (p 1. 16 g/mL).
3. 5 Perfluoric acid (p 1. 68 g/mL),
3. 6 Hydrochloric acid (p 1. 19 g/mL).
3. 7 Hydrochloric acid (1+9).
3.8 Iron bath solution: 10/L
Weigh 10.000 g pure iron (99.99%, aluminum-free), place in a 600 mL beaker, add 50 mL hydrochloric acid (3.6) and heat slowly until completely dissolved, transfer to a 1 000 mL volumetric flask, dilute to scale with water, and mix well. 3.9 Iron solution: t0 g/L,
Weigh 5.000 g pure iron (99.99%, aluminum-free), place in a 600 mL beaker, add 25 ml hydrochloric acid (3.6) and stir until completely dissolved. 6), slowly heat until completely dissolved, add 25mL perchloric acid (3.5), heat until perchloric acid smoke appears, cool, add 50mL hydrochloric acid (3.6), wait until the solution is clear, then add 50mL water.
Melt the platinum site containing 5g sodium carbonate (3.1) and 2.5g mortar (3.2) in a 1000℃ high-temperature furnace, place it to cool, immerse it in the above iron wave, slowly heat the chamber molten block to completely dissolve, remove the crucible from the beaker, and wash it carefully with water, collect the washing liquid into the original beaker, cool, then transfer the solution in the beaker to a 500mL volumetric flask, dilute with water to the scale, mix it. Approved by the Ministry of Metallurgical Industry of the People's Republic of China on December 20, 1988 and implemented on January 1, 1990
GB 4333.988
3.10 Standard curve base solution: melt the platinum crucible containing 5B sodium carbonate (3.1) and 2.5 alkali acid (3.2) in a 1000℃ high temperature furnace, place it to cool, immerse it in a 250mL beaker containing 30mL hydrochloric acid (3.6), 15mL pernitrogen acid (3.5) and 50mL water, slowly heat until the molten block is completely dissolved, remove the crucible from the beaker and rinse it carefully into the beaker, cool it, then transfer the solution in the beaker to a 200mL volumetric flask, dilute it to the mark with water, and mix it. 3.11 Aluminum standard solution: 1g/
Weigh 1.000 D g of pure lead (99.99%), place it in a 600mL beaker, dissolve it with 30mL hydrochloric acid (3.6), transfer it to a 1000mL volumetric flask, dilute it to the mark with water, and mix it. 4 Instruments
4.1 Platinum crucible: volume about 40 mL,
4.2 Polytetrafluoroethylene beaker or platinum beaker: volume is appropriate. 4.3 Atomic absorption spectrometer; with oxy-acetylene flame burner. 4.4 Aluminum hollow cathode lamp,
4. 5 Parameters of the best working conditions of the instrument are shown in Appendix A (reference). 5 Sample
The test group should pass through a 0.125 mm sieve
6 Analysis steps
6.1 Safety measures
In the presence of ammonia or organic matter, the fumes of chlorine acid are prone to explosion, which should be prevented. 8.2 Determination quantity
The same test should be analyzed twice independently, and the average value should be taken. 6.3 Sample quantity
Weigh 1.00008 sample.
6.4 Blank test
Carry out a blank test with the sample. In all cases, the same analytical procedure is followed, except that 50 mL of iron solution (3.B) is added, and all reagents of the phase vector are used.
6.5 Determination
6.5.1 Preparation of test solution
Place the sample (6.3) in a 150 mL polytetrafluoroethylene beaker or a platinum dish (4.2) of about 100 mL, and add 10 mL of nitric acid (3.3). Then carefully add dropwise (shake the container after each addition to allow the reaction to gradually occur) 10 mL of hydrofluoric acid (3.4), and allow the reaction to proceed at room temperature until gas bubbles stop.
If the silicon content of the sample is equal to or greater than 65%, add 30 mL of iron solution (3.R) to the resulting solution. In all cases, add 5 mL of perchloric acid (3.5). Place the beaker on a hot plate and heat at a temperature not exceeding 350°C until a lot of white perchloric acid fumes are emitted, and cool. Add 30 mL of hydrochloric acid (3.7) to a beaker, heat until all soluble salts are dissolved, filter the residue with filter paper, and collect the filtrate in a 250 mL beaker. Wash the residue and filter paper with about 100 mL of warm water to remove the remaining traces of peroxyacid. Put the filter paper in platinum (1.1).
Put the crucible in a low-temperature furnace, first ash it at low temperature, and then burn it at 1000°C for about 15 minutes. Cool it in a desiccator. Add 1 g of sodium carbonate (3.1) and 0.5 g of boric acid (3.2) to the molten salt, heat it on a hot plate at 250°C for 15 minutes, and then burn it at a high temperature of 1000°C for 15 minutes.
Put the cooled molten salt in a beaker with the filtrate, add 15 mL of boric acid (3.6), and heat it slowly until the molten mass is completely dissolved. Remove the tungsten from the beaker and rinse carefully. Keep the rinse liquid in the beaker and concentrate the solution at a medium temperature to keep its volume at about GB 4333. 9 - 88
60 mL. Cool it and transfer the solution in the beaker to a 100 mL volumetric flask, dilute it to the mark with water and mix it well. 6.5.1.1 Cobalt content less than 0.50% (n/m) Take the test solution (6.5.1) and measure it according to 6.5.2.
6.5.1.2 Aluminum content 0.50%~1.25% (m/m) Take 20.00 mL of the test solution (6,5.1) in a 50 mL volumetric flask, add 24.0) mL of the iron solution (3.9) with a burette, dilute it to the mark with water, mix it well and measure it according to 6.5.2.
6.5.1.3 Aluminum content 1.25%~5.00% (m/m) Take 5.00mL of test solution (6.5.1) in a 50mL volumetric flask and add 36.00mL of iron solution (3.9) with a burette. Dilute to the mark with water and mix well. Measure according to 6.5.2.
Note: Depending on the sensitivity of the instrument used, dilution can be performed in a larger volume. 6.5.2 Spectral measurement
Start the flame atomic absorption spectrometer (4.3) and allow sufficient time for the aluminum hollow cathode lamp (1.1) to reach stability. Adjust the wavelength to 309.3nm. Adjust the pressure of nitrous oxide and acetylene according to the characteristics of the burner. Use an aluminum solution of known concentration to obtain the best signal. The aluminum solution concentration can be varied according to the instrument to obtain the maximum sensitivity and stability. After adjusting the instrument zero point with the reagent blank test solution used to draw the calibration curve (6.6), measure the absorbance of the test solution (6.5, 1.1 or 6.5.1.2 or 6.5:1.3).
Note: In the "nitrous oxide-acetylene flame, aluminum is partially ionized. Iron acts as an ionization buffer, thereby enhancing the aluminum signal. The test shows that under all conditions, the enhancement effect is constant when the solution contains 3~148 iron per liter. 6.6 Drawing of the calibration curve
Add 50.0mL of iron solution (3.9) and 20.00mL of calibration curve base solution (3.10) to 8 100mL volumetric flasks respectively. Then add aluminum calibration solution (3.11) as shown in Table 1, dilute to the scale with water, and mix well. In 6.5.2 Measure the absorbance of each quasi-solution under the specified conditions. Draw a calibration curve with the mass percentage of aluminum in ferrosilicon as the horizontal axis and the corresponding absorbance value as the vertical axis. Table
Standard (3.11)
Corresponding aluminum content
Note: 1) Reagent blank test solution of the calibration curve, 7 cumulative calculation
Equivalent to the mass fraction of aluminum in the sample
Storage (8.5.1.1)
1 g/100 ml
Solution (6.5.1.2)
1 g/250 ml
Dissolution (6, ±. 1. 3)
1 g/1 000 ml
Using the calibration curve, calculate the corresponding concentration from the absorbance measured by the sample dissolution and white test solution, and calculate the mass percentage of aluminum in ferrosilicon as the difference between the two concentrations.
The percentage of aluminum content A1(%) is calculated as follows: Where,
GB4333.9—88
Al = (i- α) X
The aluminum concentration of the sample solution is obtained from the calibration curve, ug/ml.; The aluminum concentration of the blank test is obtained from the calibration curve, ug/mL: The total volume of the test solution, ml
The ratio of the test solution to be divided;
8 Allowable difference
Sample volume·more.
The difference in the analysis results between laboratories should not be greater than the allowable difference listed in Table 2. Table 2
0. 05 ~ 0. 10
>0. 10 ~ 0. 20
>0.20~0.50
>0. 50~ 1. 00
>1. 00--2. 00
>2. 00~3. 50
>3.50~5. 00
allowance difference
GB 4333. 9—88
Appendix A
3030B atomic absorption spectrometer working condition parameters (reference)
3030B atomic absorption spectrometer working condition parameters are shown in Table A1. Table A1
Additional notes:
Lamp current
Observation height
Fluorine monoxide flow rate
This standard was drafted by Shanghai Ferroalloy Plant and the Information Standard Research Institute of the Ministry of Metallurgical Industry. The main drafters of this standard are Sun Qida, Wu Guofang and Zhan Zhaoxiang. The level of this standard is marked as GB4333.9-881 B fast flow rate
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