GB/T 5686.2-2022 PDF English
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Ferromanganese, ferromanganese-silicon, nitrogen-bearing ferromanganese and manganese metal -- Determination of silicon content -- Molybdenum blue spectrophotometric method, silicon potassium fluoride titrimetric method and perchloric acid dehydration gra
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GB/T 5686.2-2008 | English | 145 |
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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
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GB/T 5686.2-1985 | English | 199 |
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Methods for chemical analysis of silicomanganese alloy--The gravimetric method for the determination of silicon content
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GB/T 5686.2-2022: PDF in English (GBT 5686.2-2022) GB/T 5686.2-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.100
CCS H 11
Replacing GB/T 5686.2-2008
Ferromanganese, Ferromanganese-silicon, Nitrogen-bearing
Ferromanganese and Manganese Metal - Determination of Silicon
Content - Molybdenum Blue Spectrophotometric Method, Silicon
Potassium Fluoride Titrimetric Method and Perchloric Acid
Dehydration Gravimetric Method
ISSUED ON: OCTOBER 12, 2022
IMPLEMENTED ON: FEBRUARY 1, 2023
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
Introduction ... 5
1 Scope ... 7
2 Normative References ... 7
3 Terms and Definitions ... 8
4 Method 1: Molybdenum Blue Spectrophotometric Method ... 8
5 Method 2: Silicon Potassium Fluoride Titrimetric Method ... 12
6 Method 3: Perchloric Acid Dehydration Gravimetric Method ... 16
7 Test Report ... 20
Appendix A (normative) Flow Chart of Specimen Analysis Result Acceptance
Procedure ... 21
Ferromanganese, Ferromanganese-silicon, Nitrogen-bearing
Ferromanganese and Manganese Metal - Determination of
Silicon Content - Molybdenum Blue Spectrophotometric
Method, Silicon Potassium Fluoride Titrimetric Method and
Perchloric Acid Dehydration Gravimetric Method
WARNING---the personnel using this document shall have practical experience in formal
laboratory work. This document does not point out all possible safety issues. Users are
responsible for taking appropriate safety and health measures and ensuring compliance
with the conditions stipulated in relevant national regulations.
1 Scope
This document specifies the determination of silicon content in ferromanganese,
ferromanganese-silicon, micro-low carbon ferromanganese-silicon, nitrogen-bearing
ferromanganese and manganese metal, using molybdenum blue spectrophotometric method,
silicon potassium fluoride titrimetric method and perchloric acid dehydration gravimetric
method.
This document is applicable to the determination of silicon content in ferromanganese,
ferromanganese-silicon, micro-low carbon ferromanganese-silicon, nitrogen-bearing
ferromanganese and manganese metal. The determination range (mass fraction) is 0.10% ~
40.00%. Method 1: molybdenum blue spectrophotometric method, which is applicable to the
determination of silicon content in manganese metal, with a determination range (mass fraction)
of 0.10% ~ 2.00%; Method 2: silicon potassium fluoride titrimetric method, which is applicable
to the determination of silicon content in ferromanganese-silicon and micro-low carbon
ferromanganese-silicon, with a determination range (mass fraction) of 12.00% ~ 40.00%;
Method 3: perchloric acid dehydration gravimetric method, which is applicable to the
determination of silicon content in ferromanganese, ferromanganese-silicon, micro-low carbon
ferromanganese-silicon, nitrogen-bearing ferromanganese and manganese metal, with a
determination range (mass fraction) of 0.50% ~ 40.00%.
2 Normative References
The contents of the following documents constitute indispensable clauses of this document
through the normative references in the text. In terms of references with a specified date, only
versions with a specified date are applicable to this document. In terms of references without a
specified date, the latest version (including all the modifications) is applicable to this document.
GB/T 4010 Ferroalloys Sampling and Preparation of Samples for Chemical Analysis
GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods
GB/T 12805 Laboratory Glassware - Burettes
GB/T 12806 Laboratory Glassware - One-mark Volumetric Flasks
GB/T 12807 Laboratory Glassware - Graduated Pipettes
GB/T 12808 Laboratory Glassware - One Mark Pipettes
3 Terms and Definitions
This document does not have terms or definitions that need to be defined.
4 Method 1: Molybdenum Blue Spectrophotometric Method
4.1 Principle
The test portion is dissolved with sodium peroxide-sodium carbonate and acidified with sulfuric
acid. Single molecule silicic acid and ammonium molybdate generate silicomolybdenum
heteropoly acid. Add oxalo-sulfur mixed acid to eliminate the impact of phosphorus, arsenic
and other impurities, etc., and use ferrous ammonium sulfate to reduce silicon-molybdenum
yellow to generate silicon-molybdenum blue. At a wavelength of 810 nm, use a
spectrophotometer to measure its absorbance, and calculate the mass fraction of silicon.
4.2 Reagents and Materials
Unless otherwise specified, only reagents that are confirmed to be analytically pure are used in
the analysis.
4.2.1 Water, GB/T 6682, Grade-3.
4.2.2 High-purity manganese, wMn > 99.9%.
4.2.3 Sodium peroxide, solid.
4.2.4 Anhydrous sodium carbonate, solid.
4.2.5 Sulfuric acid, 1 + 2.
4.2.6 Sodium sulfite solution, 100 g/L. Weigh-take 100 g of anhydrous sodium sulfite, dissolve
it in water (see 4.2.1), then, use water (see 4.2.1) to dilute it to 1,000 mL.
4.2.7 Ammonium molybdate solution, 40 g/L. Weigh-take 40 g of ammonium molybdate
[(NH4)6Mo7O24 4H2O], place it in a 400 mL beaker, add 200 mL of water (see 4.2.1), warm
to dissolve it, filter it, then add 800 mL of water (see 4.2.1), and mix it well.
4.2.8 Oxalic acid-sulfuric acid mixed acid solution. Weigh-take 65 g of oxalic acid (H2C2O4
2H2O), place it in a 2,000 mL triangular flask, add 500 mL of water (see 4.2.1) to dissolve it;
add 600 mL of sulfuric acid (1 + 1), add 900 mL of water (see 4.2.1), and mix it well.
4.2.9 Ferrous ammonium sulfate solution, 100 g/L. Weigh-take 100 g of ferrous ammonium
sulfate [(NH4)2Fe(SO4)2 6H2O], place it in a 2,000 mL triangular flask, add 20 mL of sulfuric
acid (1 + 1), and add 500 mL of water (see 4.2.1). After complete dissolution, add water to
1,000 mL, and mix it well before use.
4.2.10 Silicon standard solution, 400 g/mL. Weigh-take 0.8558 g of silica (with a purity not
lower than 99.9%) that has been dried at 105 C for 1 hour and cooled to room temperature in
a desiccator, place it in a platinum crucible containing 6 g of anhydrous sodium carbonate (see
4.2.4), evenly stir it, and cover it with a little amount of anhydrous sodium carbonate (see 4.2.4);
in a high-temperature furnace at 900 C, melt it for 15 minutes, then, take it out to cool. Place
it in a 400 mL polytetrafluoroethylene breaker and use hot water (see 4.2.1) to leach the frit and
dissolve it; use water (see 4.2.1) to wash the crucible. After cooling, transfer it to a 1,000 mL
volumetric flask, and use water (see 4.2.1) to dilute to the scale, and mix it well. Pour it into a
dry plastic bottle and set aside. 1 mL of this solution contains 400 g of silicon.
4.2.11 Iron solution, 4 mg/mL. Weigh-take 3.5 g of iron sulfate into a 500 mL beaker, add 200
mL of water (see 4.2.1) and heat to dissolve it. After the sample is completely dissolved, transfer
it to a 250 mL volumetric flask, use water (see 4.2.1) to dilute to the scale, and mix it well. 1
mL of this solution contains approximately 4 mg of iron.
4.3 Instruments
In the analysis, only common laboratory instruments are used. The one-mark volumetric flasks,
graduated pipettes and one-mark pipettes used shall respectively comply with the requirements
of GB/T 12806, GB/T 12807 and GB/T 12808.
4.4 Sampling and Sample Preparation
In accordance with the provisions of GB/T 4010, conduct sampling and sample preparation.
The specimens shall all pass the 0.125 mm sieve mesh.
4.5 Analytical Steps
4.5.1 Number of determinations
For the same specimen, conduct at least 2 independent determinations.
4.5.2 Amount of test portion
In accordance with Table 1, weigh-take the specimens, accurate to 0.0001 g.
Transfer part of the test solution (see 4.5.4.2) into a suitable cuvette, at a wavelength of 810 nm,
zero the spectrophotometer with the corresponding reference solution, measure its absorbance,
and subtract the absorbance value of the accompanying test portion blank solution to obtain the
net absorbance of the test portion solution. From the calibration curve, find the corresponding
silicon content.
4.5.5 Drawing of calibration curve
4.5.5.1 Weigh-take 7 portions of 0.2000 g of high-purity manganese (see 4.2.2) into nickel
crucibles containing 3 g of sodium peroxide (see 4.2.3) and 1 g of anhydrous sodium carbonate
(see 4.2.4), and evenly stir them. Place them in a high-temperature furnace at 700 C to melt
for 7 minutes ~ 8 minutes, take them out and let them slightly cool. Carefully use hot water (see
4.2.1) to immerse them in 200 mL plastic beakers containing 0 mL, 1.00 mL, 2.00 mL, 4.00
mL, 6.00 mL, 8.00 mL and 10.00 mL of silicon standard solution (see 4.2.10) and 2 mL of iron
solution (see 4.2.11), clean the crucibles and take them out. While using a plastic rod to stir it,
slowly add 35 mL of sulfuric acid (see 4.2.5), add 10 mL of sodium sulfite solution (see 4.2.6),
until the solution is clear. Transfer it into a 200 mL volumetric flask and use running water to
cool it to room temperature. Use water (see 4.2.1) to dilute to the scale and mix it well.
Respectively transfer-take two portions of 10.00 mL into two 100 mL volumetric flasks. The
subsequent steps shall comply with 4.5.4.2.
4.5.5.2 The absorbance of each solution in the calibration curve series minus the absorbance of
the zero-concentration solution is the net absorbance of the solution in the silicon calibration
curve series. With the silicon content (g) as the x-coordinate and the net absorbance as the y-
coordinate to draw the calibration curve.
4.6 Calculation of Analysis Results
In accordance with Formula (1), calculate the silicon content wSi in the specimen, expressed in
mass fraction (%):
Where,
m1---the silicon content found through the calibration curve, expressed in (g);
m---the amount of test portion, expressed in (g);
V1---the volume of the test solution dispensed, expressed in (mL);
V---the total volume of the test solution, expressed in (mL).
4.7 Allowable Difference
The difference in the inter-laboratory analysis results shall be not greater than the allowable
difference listed in Table 2. Otherwise, the number of additional measurements and the analysis
5.2.9 Potassium nitrate-ethanol solution, 40 g/L. Weigh-take 40 g of potassium nitrate and
dissolve it in 1,000 mL of ethanol solution (1 + 4).
5.2.10 Phenolphthalein indicator solution, 5 g/L, prepared with ethanol solution (1 + 1).
5.2.11 Sodium hydroxide standard titration solution, c (NaOH) = 0.18 mol/L. Weigh-take 7.2 g
of sodium hydroxide and dissolve it in 1,000 mL of boiled and cooled water (see 5.2.1). After
dissolving, add 1 mL of barium hydroxide solution (100 g/L) and let it stand for above 36 hours
to allow barium carbonate to completely precipitate. Use a plastic siphon to to suck the upper-
layer clarified liquid into another polyethylene tubulated bottle or container, and use it after
calibration.
Weigh-take 1.0 g of potassium hydrogen phthalate (standard reagent) that has been dried at 105
C ~ 110 C in advance, place it in a 500 mL conical flask, and add 100 mL of boiled and cooled
water (see 5.2.1). At a low temperature, heat to dissolve it, cool to room temperature, add 6
drops ~ 8 drops of phenolphthalein indicator solution (see 5.2.10), and use sodium hydroxide
standard titration solution (see 5.2.11) to titrate, until it turns reddish, which is the end point.
Along with the calibration, carry out a reagent blank test.
In accordance with Formula (2), calculate the concentration of sodium hydroxide standard
titration solution (see 5.2.11):
Where,
c---the concentration of sodium hydroxide standard titration solution, expressed in (mol/L);
m2---the mass of the weighed potassium hydrogen phthalate, expressed in (g);
V2---the volume of the sodium hydroxide standard titration solution consumed during
calibration, expressed in (mL);
V0---the volume of the sodium hydroxide standard titration solution consumed during the
reagent blank test, expressed in (mL);
0.2042---the molar mass of potassium hydrogen phthalate, expressed in (g/mmoL).
5.3 Instruments
In the analysis, only common laboratory instruments are used. The burettes used shall comply
with the provisions of GB/T 12805.
5.4 Sampling and Sample Preparation
In accordance with the provisions of GB/T 4010, conduct sampling and sample preparation.
The specimens shall all pass the 0.125 mm sieve mesh.
5.5 Analytical Steps
5.5.1 Number of determinations
For the same specimen, conduct at least 2 independent determinations.
5.5.2 Amount of test portion
Weigh-take 0.20 g of specimen. When the silicon content is above 25%, weigh-take 0.15 g of
specimen, accurate to 0.0001 g.
5.5.3 Blank test
Along with the test portion, carry out a blank test.
5.5.4 Determination
5.5.4.1 Decomposition of test portion
Place the test portion (see 5.5.2) in a 250 mL plastic beaker (or Teflon beaker, or platinum dish),
and place the plastic beaker in a cold water dish below 20 C (ice cubes can be added to adjust
the water temperature, or directly place the plastic beaker on the surface of the ice tubes for
dissolution). Add 10 mL of nitric acid (see 5.2.2), while shaking it, slowly dropwise add 4 mL
~ 5 mL of hydrofluoric acid (see 5.2.3), until the test portion is completely decomposed. If it is
difficult to dissolve the test portion, a few drops of hydrogen peroxide (see 5.2.4) can be added.
Add 5 mL of urea solution (see 5.2.7) and shake it, until no bubbles are generated.
5.5.4.2 Precipitation
Add 10 mL of potassium fluoride solution (see 5.2.5) and 10 mL of potassium nitrate solution
(see 5.2.6), shake it well, place it in a cold water dish below 20 C, and let it stand for 15
minutes.
5.5.4.3 Filtration
Use a quick filter paper containing a little pulp to filter on a plastic funnel (or use a medium-
speed double-layer filter paper to perform suction filtration), use potassium nitrate solution (see
5.2.8) to wash the plastic beaker for 3 times, and wash the precipitate for 3 times. The washing
liquid for each wash shall not exceed 5 mL, and the total amount of washing liquid shall be
controlled within 30 mL.
5.5.4.4 Neutralization and titration
Transfer the filter paper and precipitate into a 400 mL plastic beaker containing 10 mL of
potassium nitrate-ethanol solution (see 5.2.9), add 10 drops of phenolphthalein indicator
solution (see 5.2.10), use a plastic rod to thoroughly stir it, and mash the filter paper. While
6 Method 3: Perchloric Acid Dehydration Gravimetric
Method
6.1 Principle
The test portion is dissolved with nitric acid, hydrochloric acid or sodium peroxide. Use
perchloric acid to evaporate and smoke to dehydrate silicic acid. After filtering and washing,
burn the precipitate at 1,100 C to a constant mass. Add hydrofluoric acid to volatilize and
eliminate the silicon as silicon tetrafluoride, then, burn it to a constant mass. Based on the mass
difference before and after hydrofluoric acid treatment, calculate the mass fraction of silicon.
6.2 Reagents and Materials
Unless otherwise specified, only reagents that are confirmed to be analytically pure are used in
the analysis.
6.2.1 Water, GB/T 6682, Grade-3.
6.2.2 Sodium peroxide, solid.
6.2.3 Anhydrous sodium carbonate, solid.
6.2.4 Hydrochloric acid, is approximately 1.19 g/mL.
6.2.5 Perchloric acid, is approximately 1.67 g/mL.
6.2.6 Hydrofluoric acid, is approximately 1.15 g/mL.
6.2.7 Hydrogen peroxide, 30% (volume fraction).
6.2.8 Nitric acid, 1 + 1.
6.2.9 Hydrochloric acid, 1 + 1.
6.2.10 Hydrochloric acid, 1 + 10.
6.2.11 Sulfuric acid, 1 + 3.
6.2.12 Ammonium thiocyanate solution, 50 g/L.
6.2.13 Silver nitrate solution, 10 g/L.
6.3 Instruments
In the analysis, only common laboratory instruments are used.
6.4 Sampling and Sample Preparation
6.5.4.2.1 Place the test portion (see 6.5.2) in a 300 mL beaker, use a small amount of water (see
6.2.1) to moisten it, use a watch glass to cover it, and slowly add 20 mL of nitric acid (see 6.2.8)
and 5 mL ~ 10 mL of hydrochloric acid (see 6.2.4). Place it on a low-temperature electric
furnace for heating and decomposition. After the test portion is decomposed, remove it. Add
100 mL of hot water (see 6.2.1), boil it, and use a medium-speed quantitative filter paper
containing a little quantitative pulp to filter it. Use a glass rod with a rubber tip to wipe the
beaker, use hot water (see 6.2.1) to wash the filter paper and residue for 3 ~ 4 times. Collect the
filtrate and washing liquid in a 500 mL beaker, and reserve it as the main liquid.
6.5.4.2.2 Place the residue, together with the filter paper, in a platinum crucible. At a low
temperature, heat to carbonize and ash it. Burn it in a high-temperature furnace at 800 C for
20 minutes, take out and cool it. Add 3 g of anhydrous sodium carbonate (see 6.2.3). Evenly
mix it, then, use 1 g of anhydrous sodium carbonate (see 6.2.3) to cover it. Place the platinum
crucible in a high-temperature furnace at 950 C ~ 1,000 C, melt it for 10 minutes ~ 15 minutes,
take out and cool it. Place it in the original 300 mL beaker containing 50 mL of hot hydrochloric
acid (see 6.2.9), dissolve the melt, and use water (see 6.2.1) to wash the platinum crucible and
take it out. Combine the leachate with the main solution (see 6.5.4.2.1).
6.5.4.2.3 Heat and evaporate the test solution (see 6.5.4.2.2) to 50 mL, add 20 mL of perchloric
acid (see 6.2.5), use a watch glass to cover it, leave a gap, and place it on the electric hot plate.
6.5.4.3 Heat and evaporate the above-mentioned test solution (see 6.5.4.1.2 or 6.5.4.2.3), until
thick smoke of perchloric acid emerges, and continue heating, until it becomes viscous. Remove
and let it slightly cool.
6.5.4.4 Add 100 mL of hot water (see 6.2.1), heat, stir and dropwise add hydrogen peroxide
(see 6.2.7) to dissolve manganese dioxide and soluble salts. While it is still hot, use a medium-
speed quantitative filter paper containing a little quantitative pulp to filter it. Use a glass rod
with a rubber tip to wipe the beaker, use hot hydrochloric acid (see 6.2.10) to wash the filter
paper and precipitate, until there is no iron ion. Use ammonium thiocyanate solution (see 6.2.12)
to test it, then, use hot water (see 6.2.1) to wash it, until there is no chloride ion. Use silver
nitrate solution (see 6.2.13) to test it, and collect the filtrate and washing liquid in a beaker.
6.5.4.5 Transfer the filtrate and washing liquid into the beaker used for preliminary dehydration,
evaporate to 50 mL, add 20 mL of perchloric acid (see 6.2.5), and follow 6.5.4.3 ~ 6.5.4.4 for
the subsequent operations.
6.5.4.6 Place the precipitate obtained in 6.5.4.4 and 6.5.4.5, together with the filter paper in a
platinum crucible. At a low temperature, heat to carbonize and ash it. At 1,100 C, burn it for
30 minutes, and take it out to slightly cool. Place it in a desiccator, cool to room temperature,
weigh it, and repeatedly burn it, until reaching a constant mass.
6.5.4.7 Use a few drops of water (see 6.2.1) to moisten the residue in the platinum crucible, add
4 drops of sulfuric acid solution (see 6.2.11), and add 10 mL of hydrofluoric acid (see 6.2.6) to
ferromanganese-silicon and micro-low carbon ferromanganese-silicon, add 5 mL of
hydrofluoric acid (see 6.2.6) to the remaining specimens. Place it on an electric hot plate or
...... Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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