GB/T 6730.5-2007 English PDF (GBT6730.5-2007)

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GB/T 6730.5-2007: Iron ores -- Determination of total iron content -- Titanium (Ⅲ) chloride reduction methods
GB/T 6730.5-2007
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 73.060.10
D 31
Replacing GB/T 6730.5-1986
Iron ores - Determination of total iron content -
Titanium (III) chloride reduction methods
(ISO 9507:1990, MOD)
ISSUED ON: AUGUST 14, 2007
IMPLEMENTED ON: MARCH 01, 2008
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of the PRC;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative references ... 5 
3 Principle ... 6 
4 Reagents ... 7 
5 Apparatus ... 9 
6 Sampling and samples ... 9 
7 Analytical procedures ... 10 
8 Result calculation ... 14 
9 Test report ... 16 
Appendix A (Normative) Flow chart for acceptance procedure of sample
analysis value ... 18 
Appendix B (Informative) Precision expression ... 19 
Foreword
This Part of GB/T 6703 modifies and adopts ISO 9507:1990 “Iron ores -
Determination of total iron content - Titanium (III) chloride reduction methods”.
Compared with ISO 9507:1990, this Part mainly makes the following changes:
- In “2 Normative references”, replace the corresponding international
standards with Chinese standards;
- In ISO 9507:1990, excess reducing agent is oxidized with dilute potassium
dichromate (Method 1) or perchloric acid (Method 2). In this Part, use dilute
potassium dichromate to oxidize;
- In ISO 9507:1990, for melting-acidification decomposition samples, use
zirconium crucible or glassy carbon crucible; ADD sodium carbonate and
sodium peroxide. In this Part, use platinum crucible; ADD sodium carbonate
and boric acid. Temperature and acidification conditions are adjusted
accordingly. The purpose of both is to completely decompose the sample;
- In ISO 9507:1990, for melting-filtration decomposition samples, use
zirconium crucible or glassy carbon crucible. This Part uses a corundum
crucible;
- In ISO 9507:1990, use isatin as an indicator of redox. This Part uses sodium
tungstate. Both have the same effect. Sodium tungstate is currently widely
used;
- ISO 9507:1990 does not specify the method used when the copper content
is high. This Part specifies the separation method when the copper content
is high.
This Part replaces GB/T 6730.5-1986 “Methods for chemical analysis of iron
ores - The titanium chloride-potassium dichromate volumetric method for the
determination of total iron content”. Compared with GB/T 6730.5-1986, the
main changes in this Part are as follows:
- ADD melting-acidification and melting-filtration decomposition sample
methods;
- GB/T 6730.5-1986 blank titration uses two additions of ammonium ferrous
sulfate solution. This Part uses the addition of iron standard solution.
Appendix A of this Part is a normative appendix. Appendix B is an informative
appendix.
Iron ores - Determination of total iron content -
Titanium (III) chloride reduction methods
WARNING: The personnel using this Part shall have practical experience
in regular laboratory work. This Part does not point out all possible safety
problems. It is the responsibility of the user to take appropriate safety and
health measures and to ensure compliance with the conditions stipulated
by relevant national regulations.
1 Scope
This Part of GB/T 6730 specifies the determination of total iron content by
titration of potassium dichromate after reduction of iron with titanium (III)
chloride.
This Part applies to the determination of total iron content in natural iron ores,
iron concentrates, and agglomerations, including sintered products. The
determination range (mass fraction): 30.0%~72.0%.
2 Normative references
The following documents contain provisions which, through reference in this
Part of GB/T 6730, constitute provisions of this Part. For the dated references,
their subsequent amendments (excluding corrections) or revisions do not apply
to this Part. However, the parties who enter into agreement based on this Part
are encouraged to investigate whether the latest editions of these documents
are applicable. For undated reference documents, the latest editions apply to
this Part.
GB/T 6682 Water for analytical laboratory use - Specification and test
methods (GB/T 6682-1992, neq ISO 3696:1987)
GB/T 6730.1 Methods for chemical analysis of iron ores - Preparation of
predried test samples for chemical analysis (GB/T 6730.1-1986, eqv ISO
7764:1985)
GB/T 6730.3 Methods for chemical analysis of iron ores - The gravimetric
method for the determination of hygroscopic moisture content in analytical
samples (GB/T 6730.3-1986, eqv ISO 2596:1984)
GB/T 10322.1 Iron ores - Sampling and sample preparation procedures
4.18 Potassium dichromate solution, 0.25 g/L.
4.19 Stannous chloride solution, 100 g/L.
Dissolve 100 g of stannous chloride crystal (SnCl2 • 2H2O) in 200 mL of
hydrochloric acid (4.5); dissolve by heating in a water bath. COOL the solution;
USE water to dilute to 1 L. The solution shall be stored in a brown glass bottle
with a small number of tin granules.
4.20 Titanium (III) chloride solution, 15 g/L.
USE 9 volumes of hydrochloric acid (4.6) to dilute 1 volume of titanium (III)
chloride solution [about 15% titanium (III) chloride solution]. Another method is
that: In a beaker with a watch glass, use about 30 mL of hydrochloric acid (4.5)
to dissolve 1 g of titanium sponge. COOL the solution; USE water to dilute to
200 mL. Prepare at the time of use.
4.21 Iron standard solution, 0.05 mol/L.
TRANSFER 2.79 g of pure iron to a 500 mL conical beaker and place a filter
cone at the neck. ADD 35 mL of hydrochloric acid (4.6) slowly and heat until
dissolved. COOL and successively add a small amount of 5 mL of hydrogen
peroxide oxidation solution. HEAT to boiling to decompose excess hydrogen
peroxide and remove chlorine gas. TRANSFER to a 1000 mL volumetric flask
and dilute to the mark.
1.00 mL of this solution is equivalent to 1.00 mL of standard potassium
dichromate solution.
4.22 Standard solution of potassium dichromate, 0.01667 mol/L.
WEIGH 4.904 g of potassium dichromate (reference) which is pre-dried at
140°C~150°C for 2 h and cooled to room temperature in a desiccator to dissolve
in water. After cooling to 20°C, transfer to a 1000 mL volumetric flask; USE
water to dilute to the mark and mix well.
Note 1: The volumetric flask shall be checked first. At 20°C, the mass of the water
contained is weighed and then converted into a volume.
Note 2: On the storage bottle, record the temperature at which the solution is diluted (20°C).
4.23 Sodium tungstate solution. WEIGH 25 g of sodium tungstate and dissolve
it in an appropriate amount of water (If turbid, it needs to be filtered). ADD 5 mL
of phosphoric acid (ρ 1.70 g/mL); USE water to dilute to 100 mL.
4.24 Sodium diphenylamine sulfonate indicator solution, 0.2 g/100 mL.
GB/T 6730.3:
a) Processed ore containing metallic iron;
b) Natural or processed ore with a sulfur content greater than 0.2%;
c) Natural or processed ore containing more than 2.5% of combined water.
6.2.2 Ores other than 6.2.1
Thoroughly mix the laboratory samples. USE the increment division method to
sample. In accordance with the provisions of GB/T 6730.1, the sample is dried
at a temperature of 105°C±2°C.
7 Analytical procedures
7.1 Number of determinations
According to Appendix A, the same sample shall be determined at least twice
independently.
Note: “Indepe...