This standard is applicable to the determination of silicon content in metallic vanadium. Determination range: 0.002% to 0.100%. This standard complies with GB 1467-78 "General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products". GB/T 8639.6-1988 Chemical Analysis Method for Vanadium - Determination of Silicon Content by n-Butanol Extraction Spectrophotometry GB/T8639.6-1988 Standard Download Decompression Password: www.bzxz.net

National Standard of the People's Republic of China
Vanadium Determination of
silicon content N-butyl alcohol extractionspectrophotometric method
This standard is applicable to the determination of silicon content in metallic vanadium. Determination range: 0.002%~0.100%. UDC 669. 292
GB 8639.6--88
This standard complies with GB1467--78 "General Principles and General Provisions for Chemical Analysis Methods for Metallurgical Products". 1 Method Summary
The sample is decomposed with dilute nitric acid. At a certain acidity, silicic acid and ammonium molybdate generate silicomolybdate yellow heteropoly acid. Oxalic acid and sulfuric acid are used to eliminate the interference of phosphorus and arsenic. Silicomolybdate yellow is extracted with n-butanol and reduced to silicomolybdate blue heteropoly acid with a mixed solution of ammonium ferrous sulfate and ascorbic acid. Its absorbance is measured at a wavelength of 700nm on a spectrophotometer.
2 Reagents www.bzxz.net
The water used for preparing solutions and analysis is double distilled water. 2.1 n-butanol.
2.2 Nitric acid (1+3). Premium grade.
2.3 Sodium sulfite solution (10%).
Ammonium molybdate solution (5%), filtered before use. Oxalic acid solution (1%).
2.6 Sulfuric acid (1+1).
Prepared).
Reducing agent: Weigh 4.0g ascorbic acid and 0.2g ammonium ferrous sulfate, dissolve in water and dilute to 100mL, add a few drops of sulfuric acid (prepared on the same day 2.8 Silicon standard solution:
2.8.1 Weigh 0.1070g high-purity silicon dioxide (pre-dried in a 105~110C oven for 1h) and 6g anhydrous sodium carbonate (reference reagent), mix in a platinum crucible, place in a 900C high-temperature furnace to melt for 15min, take out and cool, place in a 250mL plastic beaker, and leaching with water. Transfer to a 500mL volumetric flask, dilute to the mark with water, mix well, and store in a plastic bottle for later use. This solution contains 100μg silicon in 1mL. 2.8.2 Transfer 25.00mL of silicon standard solution (2.8.1) to a 500mL volumetric flask, use Dilute with water to the mark, mix well, and store in a plastic bottle for later use. This solution contains 5ug silicon in 1mL.
2.8.3 Transfer 10.00mL of silicon standard solution (2.8.1) to a 500mL volumetric flask, dilute with water to the mark, and mix. This solution contains 2g silicon in 1mL.
3 Instruments
Spectrophotometer.
Approved by China Nonferrous Metals Industry Corporation on January 11, 1988, and implemented on January 1, 1989
The sample should pass through a 0.351mm sieve.
5 Analysis steps
5.1 Sample quantity
Weigh the sample according to Table 1.
Content range, %
0.002~~0.010
≥0. 010~ 0. 100
5.2 Blank test
Carry out a blank test together with the sample.
5.3 Determination
GB 8639.6-88
Weighing sample weight, 8
Pipette amount, mL
Acidity adjustment
Add blank solution 5 mL
5.3.1 Place the sample (5.1) in a 250mL polytetrafluoroethylene beaker. Add 16.0mL nitric acid (2.2) and dissolve in a boiling water bath. Remove, cool slightly, add 7mL sodium sulfite solution (2.3), mix well, and leave for 8 minutes. Transfer to a 50mL volumetric flask, dilute to scale with water, and mix well.
5.3.2 Transfer the test solution (5.3.1) according to Table 1 to a 125mL separatory funnel (when the silicon content is ≥0.01% to 0.1%, add 5mL of blank solution). Add 20mL water, 5.0mL ammonium sulfate solution (2.4), mix well, and let stand at room temperature for 30 minutes. 5.3.3 Add 5mL oxalic acid (2.5), 10mL sulfuric acid (2.6), cool slightly, add 15mL n-butanol and shake for 1min, and discard the aqueous phase. 5.3.4 Add 5mL reducing agent (2.7), shake for 30s. Let stand for 10min, and discard the aqueous phase. Add 5mL n-butanol (2.1), mix with a spoon. 5.3.5 Transfer part of the solution into a 2cm or 1cm colorimetric III, use the blank accompanying the sample as a reference, measure its absorbance at a wavelength of 700nm on a spectrophotometer, and find the corresponding silicon content from the working curve. 5.4 Drawing of working curve
5.4.1 Drawing of working curve for silicon content between 0.002% and 0.010%. Take 0, 0.50, 1.00, 1.50, 2.00, 2.50mL of silicon standard solution (2.8.3) and place them in a set of 125mL separatory funnels respectively. Add 3.00mL of nitric acid (2.2), dilute to 30mL with water, add 5mL of ammonium molybdate (2.4), and proceed as per 5.3.3~5.3.4. Pipette part of the solution into a 2cm or 1cm colorimetric tube, use the reagent blank as reference, measure its absorbance at a wavelength of 700nm on a spectrophotometer, and draw a working curve with the silicon content as the horizontal coordinate and the absorbance as the vertical coordinate. 5.4.2 Drawing of working curve for silicon content ≥0.010%~0.100%. Take 0, 0.500, 1.00, 2.00, 3.00, 4.00, 5.00mL of silicon standard solution (2.8.2) and place them in a set of 125mL separatory funnels respectively, add 3.00mL of nitric acid (2.2), dilute to 30mL with water, add 5mL of ammonium molybdate (2.4), and proceed as per 5.3.3 to 5.3.4.
Put part of the solution into a 2cm or 1cm cuvette, use the reagent blank as reference, measure its absorbance at a wavelength of 700nm on a spectrophotometer, and draw a working curve with the silicon content as the horizontal axis and the absorbance as the vertical axis. 6 Calculation of analysis results
Calculate the percentage of silicon in the formula (1):
si(%) species × 10 × 100
Wherein: m, --- silicon content found from the working curve, ug; --- solution fraction ratio:
- sample volume, 8.
Allowable difference
GB 8639.688
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 2. Table 2
0.0020~0.0060
>0. 006 0 ~ 0. 015
>0. 015~0.040
>0.040～0.100
Additional remarks:
This standard was drafted by Jinzhou Ferroalloy Factory. This standard was drafted by Shanghai Ferroalloy Factory.
The main drafter of this standard is Huang Weiping.
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