SN/T 3323.1-2012 English PDF (SNT3323.1-2012)

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SN/T 3323.1-2012: Mill scale. Part 1: Determination of ferrous oxide. Potassium dichromate titration
SN/T 3323.1-2012
ENTRY-EXIT INSPECTION AND QUARANTINE INDUSTRY
STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA
Mill scale - Part 1: Determination of ferrous oxide -
Potassium dichromate titration
ISSUED ON: DECEMBER 12, 2012
IMPLEMENTED ON: JULY 01, 2013
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Method summary ... 4 
4 Reagents ... 4 
5 Instruments and equipment ... 5 
6 Specimen ... 5 
7 Analysis steps ... 5 
8 Result calculation ... 6 
9 Precision ... 7 
Annex A (normative) Determination of hygroscopic water in mill scale ... 8 
Mill scale - Part 1: Determination of ferrous oxide -
Potassium dichromate titration
1 Scope
This Part of SN/T 3323 specifies potassium dichromate titration, the method to
determine the ferrous oxide content in mill scale.
This Part is applicable to the determination of ferrous oxide content in mill scale. The
determination range is 10%~60%.
2 Normative references
The following referenced documents are indispensable for the application of this
document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
GB/T 6682, Water for analytical laboratory use - Specification and test methods
GB/T 6730.6-1986, Methods for chemical analysis of iron ores - The ferric chloride-
sodium acetate volumetric method for the determination of metallic iron content
GB/T 6730.7-1986, Methods for chemical analysis of iron ores - The sulfosalicylic
acid photometric method for the determination of metallic iron content
3 Method summary
In the absence of air, use hydrochloric acid and sodium fluoride to decompose the
specimen. Use sodium diphenylamine sulfonate as indicator. Determine ferrous and
metallic iron content by potassium dichromate volumetric method. After subtracting the
amount of metallic iron, the amount of ferrous iron is obtained.
4 Reagents
Unless otherwise stated, all reagents are analytically pure and above. Water is grade
two water specified in GB/T 6682.
4.1 Sodium fluoride.
4.2 Sodium bicarbonate.
4.3 Hydrochloric acid (ρ=1.19g/mL).
4.4 Saturated sodium bicarbonate solution.
4.5 Mixed sulfuric acid: Put 200mL of sulfuric acid (ρ=1.84g/mL) under stirring, then
pour into 500mL of water slowly. Then, add 300mL of phosphoric acid (ρ=l.70g/mL).
Mix well.
4.6 Sodium diphenylamine sulfonate solution (2g/L): Weigh 0.2g of sodium
diphenylamine sulfonate and dissolve in 100mL of water.
4.7 Potassium dichromate standard titration solution (0.0050mol/L): Weigh 1.4709g of
potassium dichromate (reference reagent) that has been pre-dried at 150°C for 1h, and
dissolve in water. Transfer into a 1000mL volumetric flask. Use water to dilute to the
scale. Mix well.
4.8 Ferrous ammonium sulfate solution (about 0.03mol/L): Weigh 11.82g of ferrous
ammonium sulfate [(NH4)2(SO4)2•6H2O] and dissolve in sulfuric acid (5+95). Transfer
into a 1000mL volumetric flask. Use sulfuric acid (5+95) to dilute to the scale. Mix
well.
5 Instruments and equipment
5.1 Balance: the sensitivity is 0.1mg.
5.2 Geiger funnel: 250mL.
6 Specimen
The specimen shall pass through the sieve mesh of 0.100mm.
7 Analysis steps
7.1 Test material
Weigh about 0.15g of specimen (Chapter 6), accurate to 0.0001g.
Weigh two portions of test material for parallel determination. Take the average value
as the result.
7.2 Blank test
Conduct the blank test, along with test material.
7.3 Determination