GB/T 38812.2-2020 English PDF (GBT38812.2-2020)

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GB/T 38812.2-2020: Direct reduced iron--Determination of metallic iron content--The potassium dichromate titrimetric method after decomposition of sample by ferric chloride
GB/T 38812.2-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 73.060.10
D 31
Direct reduced iron - Determination of metallic iron
content - The potassium dichromate titrimetric
method after decomposition of sample by ferric
chloride
ISSUED ON: JUNE 02, 2020
IMPLEMENTED ON: DECEMBER 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Principle ... 5 
4 Reagents and materials ... 5 
5 Instruments ... 6 
6 Sampling and sample preparation ... 6 
7 Analysis steps ... 6 
8 Result calculation and expression ... 7 
9 Test report ... 8 
Appendix A (Normative) Sample analysis result acceptance procedure flow
chart ... 9 
Direct reduced iron - Determination of metallic iron
content - The potassium dichromate titrimetric
method after decomposition of sample by ferric
chloride
Caution -- 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 of GB/T 38812 specifies the potassium dichromate titrimetric method
after decomposition of sample by ferric chloride to determine the metallic iron
content.
This Part applies to the determination of metallic iron content in direct reduced
iron; the determination range (mass fraction): ≥ 50.00%.
2 Normative references
The following documents are indispensable for the application of this document.
For dated references, only the dated version applies to this document. For
undated references, the latest edition (including all amendments) applies to this
document.
GB/T 6682, Water for analytical laboratory use - Specification and test
methods
GB/T 8170, Rules of rounding off for numerical values and expression and
judgment of limiting values
GB/T 12805, Laboratory glassware - Burettes
GB/T 12806, Laboratory glassware - One-mark volumetric flasks
GB/T 12808, Laboratory glassware - One mark pipettes
5 Instruments
5.1 Common laboratory equipment that is used in the analysis. Burettes, one-
mark volumetric flasks and one mark pipettes shall meet the requirements of
GB/T 12805, GB/T 12806 and GB/T 12808.
5.2 Oscillator: reciprocating multi-functional oscillator. Oscillation frequency:
150 times/min ~ 160 times/min; amplitude: 20 mm (reciprocating).
6 Sampling and sample preparation
Perform sampling and sample preparation according to the provisions of GB/T
24239.
7 Analysis steps
7.1 Number of determinations
Make at least two independent determinations on the same sample.
Note: "Independent" means that the second and any subsequent determination
result is not affected by the previous determination result. In this analysis
method, this condition means that in the same laboratory, the same
operator uses the same equipment and the same test method to
independently repeat the determination on the same tested object in a
short time, including the use of appropriate recalibration.
7.2 Sample mass
Weigh 0.10 g of sample, to the nearest 0.000 1 g.
7.3 Blank test
Carry out a blank test along with the sample.
7.4 Determination
7.4.1 Sample decomposition
Place the sample (see 7.2) in a dry 300 mL conical flask; add 40 mL of ferric
trichloride solution (see 4.4); stopper the bottle; place it on an oscillator and
shake for 40 min. Use a medium-speed filter paper to filter; collect the filtrate in
a 500 mL conical flask. Use water to wash the conical flask, stopper and residue
6 ~ 8 times; control the solution volume to 150 mL ~ 200 mL.