This standard specifies the determination of phosphorus content by phosphomolybdenum blue spectrophotometry. This standard is applicable to the determination of phosphorus content in manganese silicon alloy. Determination range: ≤0.450%. GB/T 5686.4-1998 Chemical analysis method for manganese silicon alloys Determination of phosphorus content by phosphomolybdenum blue spectrophotometry GB/T5686.4-1998 Standard download decompression password: www.bzxz.net

GB/T5686.4—1998
This standard is equivalent to the determination of phosphorus content by phosphomolybdenum blue spectrophotometry in Chapter 6 of JIS G1314—1987 "Analysis Method for Manganese Silicon Alloys" in terms of technical content.
This revision extends the upper limit of the determination range of the original national standard from 0.400% to 0.450%, and supplements the corresponding condition test. JIS G1314-1987 does not have an arsenic removal step when decomposing the sample. Considering the actual situation in my country, the removal step of the original national standard is still retained.
Determination of phosphorus content by neutralization titration"
From the date of implementation of this standard, it replaces GB/T5686.3--1988 "Chemical Analysis Method for Manganese Silicon Alloys" and GB/T5686.4—1985 "Chemical Analysis Method for Manganese Silicon Alloys - Determination of Phosphorus Content by Molybdenum Blue Photometric Method". This standard is proposed by the State Bureau of Metallurgical Industry. This standard is under the jurisdiction of the Information Standards Research Institute of the State Bureau of Metallurgical Industry. This standard was drafted by Nanjing Ferroalloy Plant. The main drafters of this standard are Zhang Jianian and Jiang Weixin. This standard was first issued in December 1985. 280
1 Scope
National Standard of the People's Republic of China
Chemical analysis method of silicomanganese-The phosphomolybdenum blue phtometric method forthe determination of phosphorus content This standard specifies the determination of phosphorus content by phosphomolybdenum blue spectrophotometry. This standard is applicable to the determination of phosphorus content in silicomanganese alloys. Determination range: ≤0.450%. 2 Method Summary
GB/T 5686.4—1998
GB/T5686.3—1988
Replace GB/15686.4-1985
The sample is decomposed with nitric acid and hydrofluoric acid, evaporated with perchloric acid until smoke appears, oxidize phosphorus to orthophosphoric acid, reduce iron with sodium bisulfite, add ammonium molybdate and sulfuric acid to generate phosphomolybdenum blue, and measure its absorbance at a wavelength of 825nm on a spectrophotometer. 3 Reagents
3.1 Nitric acid (ol.42 g/mL).
3.2 Hydrochloric acid (pl.19 g/mL).
3.3 Hydrofluoric acid (pl.15 g/mL).
3.4 ​​Perchloric acid (pl.67 g/mL).
3.5 Hydrobromic acid (p1.38 g/mL).
3.6 Sodium bisulfite (100g/L).
3.7 Color developer solution
3.7.1 Ammonium molybdate solution: Weigh 20g ammonium molybdate [(NH4Mo,O24·4H4O] and place it in a 1000mL beaker, add 250mL water and heat to dissolve, add 700mL sulfuric acid (1+1), cool, transfer to a 1000mL volumetric flask, dilute to scale, and mix. 3.7.2 Sulfuric acid solution: 1.5g/L
3.7.3 When using, take 25mL ammonium molybdate solution (3.7.1), 10mL sulfuric acid solution (3.7.2) and 65mL water, place in a 150mL beaker, and mix.
3.8 Phosphorus standard solution: Weigh 0.4394g of potassium dihydrogen phosphate (KH,PO.) (reference reagent) which has been pre-dried to constant weight at 105110℃ and cooled to room temperature in a desiccator, place in a 200mL beaker, dissolve in water, transfer to a 1000mL volumetric flask, dilute to scale, and mix. This solution contains 100μg of phosphorus in 1mL.
4 Sample
The sample should pass through a 0.125mm sieve.
Approved by the State Administration of Quality and Technical Supervision on December 14, 1998 and implemented on August 14, 1999
5 Analysis steps
5.1 Sample quantity
Weigh the sample quantity according to Table 1.
Phosphorus content, %
≥0.150~0.450
5.2 Blank test
Carry out a blank test together with the sample.
5.3 Determination
GB/T 5686.4—1998
Sample amount + g
5.3.1 Place the sample (5.1) in a 100ml platinum dish (or a 200ml polytetrafluoroethylene beaker), add 20ml nitric acid (3.1), place the platinum dish in a cold water bath, and add 5ml hydrofluoric acid (3.3) dropwise for decomposition. 5.3.2 Add 10ml perchloric acid (3.4), heat and evaporate until smoke appears for about 5min to drive off the hydrofluoric acid. After cooling, wash with warm water and transfer to a 150ml beaker and cover with a watch glass.
5.3.3 Continue heating and evaporating until perchloric acid smoke appears, and reflux for about 15 minutes to remove nitric acid and cool. If the test solution contains more than 5 mg of arsenic, add 5 mL of hydrochloric acid (3.2), heat to decompose manganese dioxide, continue heating and evaporating until perchloric acid smoke just appears, and cool. Add 5 mL of hydrobromic acid (3.5), remove the table dish, heat and evaporate at low temperature, when perchloric acid smoke appears, cover the table blood, continue heating and evaporating until perchloric acid smoke appears, and reflux for about 10 minutes to allow arsenic and hydrogen bromide to escape completely, and cool. 5.3.4 Add 30 mL of warm water to dissolve the salts, add sodium bisulfite solution (3.6) dropwise, reduce manganese dioxide, filter into a 250 ml volumetric flask with medium-speed filter paper with a small amount of filter paper pulp, wash with warm water until there is no acidity, cool, dilute to the scale with water, and mix. 5.3.5 Transfer 2500mL of solution (5.3.4) to a 100mL volumetric flask, add 10mL of sodium bisulfite (3.6), heat in a boiling water bath until the solution is colorless, immediately add 25mL of color developer solution (3.7.3), heat in a boiling water bath for 15min, remove, cool to room temperature with running water, dilute to scale with water, and mix. wwW.bzxz.Net
5.3.6 Transfer part of the solution (5.3.5) to an appropriate absorber, and measure its absorbance at a wavelength of 825nm on a spectrophotometer using the blank solution accompanying the sample as a reference.
5.4T Plotting the curve
5.4.1 Take 0, 1.00, 3.00, 5.00, 7.00, 9.00 ml of phosphorus standard solution (3.8) and place them in a 100 ml beaker respectively, add 5 ml of perchloric acid (3.4), heat until perchloric acid smoke appears, and cool. The following is carried out according to 5.3.4 to 5.3.5, with the reagent blank as the reference, and measure its absorbance according to 5.3.6. Plot the working curve with phosphorus content as the horizontal axis and absorbance as the vertical axis. 6 Calculation of analysis results
Calculate the percentage of phosphorus according to the following formula:
Where: m-
Phosphorus content·name found from the working curve; -Sample volume, g;
7 Allowable difference
Test solution split ratio.
The difference in analysis results between laboratories should not be greater than the allowable difference specified in Table 2. 282
0. 050~0. 100
>0.100~0.150
>0.150~~0.300
≥0.300~0. 450
GB/T 5686.4—1998
Allowable difference
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