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GB/T 5686.2-2008 English PDF (GBT5686.2-2008)

GB/T 5686.2-2008 English PDF (GBT5686.2-2008)

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GB/T 5686.2-2008: Ferromanganese, ferromanganese-silicon, nitrogen-bearing ferromanganese and manganese metal -- Determination of silicon content -- Molybdenum blue photometric method, silicon potassium fluoride titrimetric method and perchloric acid dehydration gravimetri
This Part specifies the determination of silicon content in ferromanganese, ferromanganese-silicon, nitrogen-bearing ferromanganese, manganese metal and electrolytic manganese by the molybdenum blue photometric method, silicon potassium fluoride titrimetric method and perchloric acid dehydration gravimetric method.
GB/T 5686.2-2008
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.100
H 11
Replacing GB/T 5686.2-1985, GB/T 7730.2-2002, GB/T 8654.3~8654.4-1988
Ferromanganese, ferromanganese-silicon, nitrogen-
bearing ferromanganese and manganese metal -
Determination of silicon content - Molybdenum blue
photometric method, silicon potassium fluoride
titrimetric method and perchloric acid dehydration
gravimetric method
ISSUED ON: MAY 13, 2008
IMPLEMENTED ON: NOVEMBER 01, 2008
Issued by: General Administration of Quality Supervision, Inspection
and Quarantine;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 6
3 Method I, Molybdenum blue photometric method ... 6
4 Method II, Silicon potassium fluoride titrimetric method ... 9
5 Method III, Perchloric acid dehydration gravimetric method ... 12
6 Test report ... 16
Ferromanganese, ferromanganese-silicon, nitrogen-
bearing ferromanganese and manganese metal -
Determination of silicon content - Molybdenum blue
photometric method, silicon potassium fluoride
titrimetric method and perchloric acid dehydration
gravimetric method
Warning: the personnel who uses this Part shall have hands-on
experience in formal laboratory work. This Part does not address all
possible security issues. It is the responsibility of the user to take
appropriate safety and health measures and to ensure compliance with
the conditions which are set by the relevant national regulations.
1 Scope
This Part specifies the determination of silicon content in ferromanganese, ferromanganese-silicon, nitrogen-bearing ferromanganese, manganese metal and electrolytic manganese by the molybdenum blue photometric method,
silicon potassium fluoride titrimetric method and perchloric acid dehydration gravimetric method.
This Part applies to the determination of silicon content in ferromanganese, ferromanganese-silicon, nitrogen-bearing ferromanganese, manganese metal and electrolytic manganese metal. The determination range (mass fraction): 0.001% ~ 30.00%. Method I: molybdenum blue photometric method, suitable for the determination of silicon content in manganese metal and electrolytic manganese metal, with a determination range (mass fraction) of 0.001% ~ 0.60%; Method II: silicon potassium fluoride titrimetric method, suitable for the determination of silicon content in ferromanganese-silicon, with a determination range (mass fraction) of 12.00% ~ 30.00%; Method III: perchloric acid
dehydration gravimetric method, suitable for the determination of silicon content in ferromanganese, ferromanganese-silicon, manganese metal and electrolytic manganese metal, with a determination range (mass fraction) of 0.50% ~
30.00%.
3.5.3.3 Place the test solution (3.5.3.2) in a 50 °C water bath; when the temperature in the bottle is 50 °C, add 10 mL of ammonium molybdate solution (3.2.3) while shaking; use a small amount of water to rinse the ammonium molybdate that is attached to the inner wall of the bottle; keep the temperature in a 50°C constant temperature water bath for 5 minutes; shake occasionally; remove the running water to cool to room temperature.
3.5.3.4 Add 15 mL of hydrofluoric acid (3.2.2); mix well; add 5 mL of ammonium ferrous sulfate solution (3.2.4) within 30 seconds; mix well; use water to dilute to the mark; mix well; let stand for 15 minutes.
3.5.3.5 Transfer part of the test solution (3.5.3.4) into the corresponding quartz cuvette; use the blank solution with the sample as a reference; measure its absorbance at the wavelength of 810 nm of a spectrophotometer; find out the corresponding silicon content from the working curve.
3.5.4 Drawing of calibration curve
Pipette 0, 2.00 mL, 4.00 mL, 6.00 mL, 10.00 mL, 12.00 mL of silicon standard solution (3.2.5.1) into a set of 100 mL volumetric flasks; respectively add 9 mL of sulfuric acid (3.2.1); use water to dilute to 40 mL; perform the following according to the analysis steps 3.5.3.3 ~ 3.5.3.5; use the reagent blank as a reference; measure its absorbance at a wavelength of 810 nm of a
spectrophotometer. Take the silicon content as the abscissa and the
absorbance as the ordinate to draw the working curve.
3.6 Result calculation
Calculate the silicon content (mass fraction) in the sample according to Formula (1):
Where:
m1 -- the silicon content that is found from the working curve, in milligrams (mg); r -- test solution fraction ratio;
m -- sample mass, in grams (g).
3.7 Allowable difference
The difference of analysis results between laboratories shall not be greater than the allowable difference that is listed in Table 2.
0.202 4 -- the mass of the potassium hydrogen phthalate that is equivalent to 1 mL of sodium hydroxide standard titration solution [c(NaOH) = 1.000
mol/L], in grams (g).
4.3 Instruments
Common laboratory equipment that is used in the analysis.
4.4 Sample taking
Take samples according to regulations of GB/T 4010; the sample shall pass through a 0.125 mm sieve.
4.5 Analysis steps
4.5.1 Sample mass
Weigh 0.200 g of sample, to the nearest 0.0001 g.
4.5.2 Blank test
Carry out a blank test along with the sample.
4.5.3 Determination
4.5.3.1 Place the sample (4.5.1) in a 250 mL plastic beaker; add 30 mL of nitric acid (4.2.4); dropwise add 10 mL of hydrofluoric acid (4.2.2); shake gently until the sample is completely decomposed [if the sample is insoluble, add a few drops of hydrogen peroxide (4.2.3)]; drive out nitrogen oxides. Add 10 mL of urea solution (4.2.5); shake until no bubbles are generated; let stand for 1 min ~ 2 min.
4.5.3.2 Add 2 g of potassium fluoride (4.2.1); stir to dissolve; add a little filter paper pulp; let it stand in a water bath below 25°C for 30 minutes. Use medium- speed filter paper and a plastic funnel to filter; use a potassium nitrate-ethanol solution (4.2.6) less than 25 °C to quickly wash the plastic beaker, filter paper and precipitate, until the test paper does not appear blue when the washing liquor drops onto the Congo red test paper (4.2.8).
4.5.3.3 Transfer the precipitate and filter paper into a 500 mL conical flask; add 100 mL of warm neutral water (4.2.7); shake well; shake the filter paper to pieces. After heating the test solution to boiling, add 6 ~ 8 drops of
phenolphthalein solution (4.2.9); use sodium hydroxide standard titration solution (4.2.10) to titrate to the end point. Add 2 drops of phenolphthalein solution (4.2.9); continue to use sodium hydroxide standard titration solution (4.2.10) to titrate, until the reddish color does not fade as the end point. 4.6 Result calculation
5.5.3 Determination
5.5.3.1 Decomposition of ferromanganese-silicon sample
5.5.3.1.1 Place the sample (5.5.1) in a nickel crucible that contains 5 g ~ 8 g of sodium peroxide (5.2.1); mix well; cover with 3 g of sodium peroxide (5.2.1) or 3 g of anhydrous sodium carbonate (5.2.2). Place the crucible that contains the sample and flux on an electric hot plate at 350 °C ~ 400 °C; heat it until the melt turns black. Put the crucible and the blackened melt at 700 °C ~750 °C to melt for 10 min ~ 15 min. Take it out; cool.
5.5.3.1.2 Put the crucible into a 500 mL beaker that contains 200 mL of water; cover it with a watch glass; when there are no bubbles, take out the crucible and use hot water to wash it; collect the washing liquid into the same beaker. Add 30 mL of hydrochloric acid (5.2.3); heat to dissolve the salts. Evaporate the test solution to 100 mL; add 100 mL of perchloric acid (5.2.4); cover with a watch glass.
5.5.3.2 Decomposition of manganese metal, electrolytic manganese metal, nitrogen-bearing ferromanganese and manganese samples
5.5.3.2.1 Place the sample (5.5.1) in a 300 mL beaker; use a small amount of water to moisten; cover it with a watch glass; slowly add 20 mL of nitric acid (5.2.7) and 5 mL ~ 10 mL of hydrochloric acid (5.2.3); place on a low-
temperature electric furnace to heat to decompose; remove the sample after decomposition. Add 100 mL of hot water; boil; use a medium-speed quantitative filter paper with a little quantitative pulp to filter; use a glass rod with a rubber head to wipe the beaker; use hot water to wash the filter paper and residue 3 ~ 4 times; collect the filtrate and washing liquor in a 500 mL beaker; keep it as the main solution.
5.5.3.2.2 Put the residue together with the filter paper in a platinum crucible; heat at low temperature for carbonization and ashing. Burn in a high
temperature furnace at 800°C for 20 minutes; take it out; cool. Add 3 g of anhydrous sodium carbonate (5.2.2); mix well; cover with 1 g of anhydrous sodium carbonate (5.2.2). Place the platinum crucible in a high temperature furnace at 950 °C ~ 1 000 °C to melt for 10 min ~ 15 min; take it out; cool it; place it in the original 300 mL beaker that contains 50 mL hot hydrochloric acid (5.2.8) in advance; dissolve the melt; use water to wash the platinum crucible; take it out; combine the leaching solution with the main solution (5.5.3.2.1). 5.5.3.2.3 Heat and evaporate the test solution to 50 mL; add 20 mL of perchloric acid (5.2.4); cover with a watch glass.
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