GB/T 5686.4-2008 English PDF (GBT5686.4-2008)

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GB/T 5686.4-2008: Ferromanganese, ferromanganese-silicon, nitrogen-bearing ferromanganese and manganese metal -- Determination of phosphorus content -- Molybdenum blue photometric method and alkali content titrimetric method
GB/T 5686.4-2008
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.100
H 11
Replacing GB/T 5686.4-1998, GB/T 7730.3-1997, GB/T 8654.5-1988
Ferromanganese, ferromanganese-silicon, nitrogen-
bearing ferromanganese and manganese metal -
Determination of phosphorus content - Molybdenum
blue photometric method and alkali content titrimetric
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 ... 5 
3 Method I: Molybdenum blue photometric method ... 6 
4 Method II: Alkali content titrimetric method ... 10 
5 Test report ... 16 
Ferromanganese, ferromanganese-silicon, nitrogen-
bearing ferromanganese and manganese metal -
Determination of phosphorus content - Molybdenum
blue photometric method and alkali content titrimetric
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 phosphorus content in ferromanganese,
ferromanganese-silicon, nitrogen-bearing ferromanganese, manganese metal
and electrolytic manganese by the molybdenum blue photometric method and
the alkali content titrimetric method.
This Part applies to the determination of phosphorus content in
ferromanganese, ferromanganese-silicon, nitrogen-bearing ferromanganese,
manganese metal. The determination range (mass fraction): 0.0030% ~
0.650%. Method I: molybdenum blue photometric method, applicable to the
determination of silicon content in ferromanganese, ferromanganese-silicon,
nitrogen-bearing ferromanganese, manganese metal, determination range
(mass fraction): 0.003 0% ~ 0.450%; method II: alkali content titrimetric method,
applicable to the determination of ferromanganese, determination range (mass
fraction): 0.080% ~ 0.650%.
2 Normative references
The terms in the following documents become the terms of this Part by
reference to this Part. For dated references, all subsequent amendments (not
including errata content) or revisions do not apply to this Part. However, parties
to agreements that are based on this Part are encouraged to study whether the
latest versions of these documents can be used. For undated references, the
latest edition applies to this Part.
to evaporate until white smoke is emitted; keep heating for about 10 minutes
while the perchloric acid vapor is refluxing along the wall of the beaker; then,
remove it. Perform the following operations according to 3.5.3.2.
3.5.3.1.2 Decomposition of ferromanganese, ferromanganese-silicon, and
nitrogen-bearing ferromanganese samples
3.5.3.1.2.1 Place the sample (3.5.1) in a 200 mL PTFE beaker (or a 100 mL
platinum dish); add 20 mL of nitric acid (3.2.1); put it in a cold-water bath. If the
test solution contains silicon of ≤50 mg, add 5 mL of hydrofluoric acid (3.2.3)
dropwise at a time to decompose. When the silicon content is at 50 mg ~ 70 mg
(when it is more than 70 mg, there will be interference), 5 mL of hydrofluoric
acid and 5 mL of perchloric acid can be added for the second volatilization of
silicon.
3.5.3.1.2.2 Add 10 mL of perchloric acid (3.2.5); heat and evaporate to smoke
for about 5 minutes to drive off hydrofluoric acid. After cooling, use warm water
to wash into a 150 mL beaker; cover with a watch glass.
3.5.3.1.2.3 Continue to heat and evaporate until perchloric acid smokes; reflux
for about 10 minutes; remove all nitric acid; cool. If the test solution contains
arsenic of ≤5 mg, directly operate according to (3.5.3.1.2.2). When the arsenic
content in the test solution is at 5 mg ~ 9 mg (interference occurs when it is
greater than 9 mg), add 5 mL of hydrochloric acid (3.2.2); heat to decompose
the manganese dioxide; continue to heat and evaporate until there is just
perchloric acid fume; cool. Add 5 mL of hydrobromic acid (3.2.4); remove the
watch glass; heat it to evaporate at low temperature; when perchloric acid fume
appears, cover the watch glass; continue to heat to evaporate until perchloric
acid fume is emitted, and reflux for about 10 minutes; make arsenic and
hydrogen bromide escapes completely; cool. Perform the following operations
according to 3.5.3.2.
3.5.3.2 Reduction, color development and colorimetric operations
3.5.3.2.1 After cooling slightly, add about 30 mL of warm water to dissolve the
soluble salts; add sodium hydrogensulfite (3.2.6) dropwise to decompose
manganese dioxide, etc.; use medium-speed filter paper to filter it in a 250 mL
volumetric flask; use warm water to wash until acid-free; cool to room
temperature; use water to dilute to the mark; mix well.
3.5.3.2.2 Pipette 25.00 mL of test solution (3.5.3.2.1) into a 100 mL volumetric
flask; add 10 mL of sodium hydrogensulfite (3.2.6); heat it in a boiling water
bath until the solution is colorless; remove it immediately and add 25 mL of the
color-developing agent solution (3.2.9); then, heat it in a boiling water bath for
15 minutes; remove the running water and cool to room temperature; use water
to dilute to the mark; mix well.
Use nitric acid to dissolve the sample; the perchloric acid smokes, and
generates ammonium phosphomolybdate precipitates in the nitric acid-
ammonium nitrate medium. Use excess sodium hydroxide standard solution to
dissolve the precipitate; use nitric acid standard solution for back titration.
According to the consumption of sodium hydroxide standard solution, calculate
the mass fraction of phosphorus.
4.2 Reagents
4.2.1 Ammonium nitrate, solid.
4.2.2 Hydrochloric acid, ρ 1.19 g/mL.
4.2.3 Nitric acid, ρ 1.42 g/mL.
4.2.4 Nitric acid, 1 + 50.
4.2.5 Nitric acid, 1 + 5 000.
4.2.6 Hydrofluoric acid, ρ 1.15 g/mL.
4.2.7 Perchloric acid, ρ 1.67 g/mL.
4.2.8 Hydrobromic acid, 40.0 g/L.
4.2.9 Ammonium hydroxide, ρ 0.90 g/mL.
14.2.10 Sodium nitrite solution, 200 g/L.
4.2.11 Ammonium molybdate solution. Weigh 40 g of ammonium molybdate
[(NH4)6Mo7O2·4H2O] in a 500 mL beaker; add 300 mL of water; slightly heat to
dissolve it; add 80 mL of ammonium hydroxide (4.2.9); cool. Slowly pour this
solution into 600 mL of nitric acid (1 + 1); place the beaker in running water to
cool; stir constantly; filter before use.
4.2.12 Potassium nitrate solution (10 g/L); use nitric acid neutralize to neutral
in advance.
4.2.13 Bromothymol blue indicator solution (10 g/L). Weigh 0.1 g of
bromothymol blue into a 150 mL beaker; add 20 mL of ethanol (950 g/L) to
dissolve; add water to dilute to 100 mL.
4.2.14 Phenolphthalein indicator solution (1 g/L). Weigh 0.1 g of
phenolphthalein into a 150 mL beaker; add 50 mL of ethanol (950 g/L) to
dissolve; add water to dilute to 100 mL.
4.2.15 Sodium hydroxide standard solution, 0.01 mol/L. Store in a polyethylene
bottle with a soda lime tube.
platinum dish; add 20 mL of nitric acid (4.2.3); add 3 ~ 5 drops of hydrofluoric
acid (4.2.6); heat at low temperature until the sample is dissolved; add 10 mL
of perchloric acid (4.2.7); heat and evaporate until the white smoke of perchloric
acid starts ...