GB/T 6730.8-2016 PDF English
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| GB/T 6730.8-2016 | English | 150 |
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Iron ores - Determination of iron (II) content - Potassium dichromate titrimetric method
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| GB/T 6730.8-1986 | English | 199 |
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Methods for chemical analysis of iron ores. The potassium dichromate volumetric method for the determination of iron (Ⅱ) content
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GB/T 6730.8-2016: Iron ores - Determination of iron (II) content - Potassium dichromate titrimetric method
---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT6730.8-2016
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 73.060.10
D 31
Replacing GB/T 6730.8-1986
Iron ores - Determination of iron (II) content -
Potassium dichromate titrimetric method
Issued on. OCTOBER 13, 2016
Implemented on. SEPTEMBER 01, 2017
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 and materials... 6
5 Apparatus... 7
6 Sampling and sample preparation... 7
7 Analytical procedures... 8
8 Analysis results and their representation... 10
9 Test report... 12
Appendix A (Normative) Flow chart for acceptance procedure of sample
analysis value... 13
Appendix B (Informative) Additional information on joint precision test... 14
Appendix C (Informative) Graphical representation of precision result... 15
Foreword
GB/T 6730 “Iron ores” is divided into dozens of parts.
This Part is Part 8 of GB/T 6730.
This Part is drafted in accordance with the rules given in GB/T 1.1-2009.
This Part replaces GB/T 6730.8-1986 “Methods for chemical analysis of iron
ores - The potassium dichromate volumetric method for the determination of
iron (II) content”. Compared with GB/T 6730.8-1986, in addition to editorial
changes, the main technical changes of this Part are as follows.
- CHANGE the name to “Iron ores - Determination of iron (II) content -
Potassium dichromate titrimetric method”;
- ADD contents such as “Warning”, “Normative references”, “Apparatus”,
“Test report”, “Appendix B”, “Appendix C”;
- CHANGE the determination range from “ >0.70%” to “0.700%~30.00%”;
- ADD treatment method to eliminate high-valent manganese interference in
samples;
- Modify the weighing quantity of the test portion;
- Modify the calculation formula of “calculation of analysis results”;
- Carry out an interlaboratory precision joint test; USE the repeatability limit
r and reproducibility limit R obtained by statistics instead of the “tolerance”.
This Part was proposed by China Iron and Steel Association.
This Part shall be under the jurisdiction of National Technical Committee 317
on Iron Ores and Direct Reduction of Standardization Administration of China
(SAC/TC 317).
Main drafting organizations of this Part. Changsha Research Institute of Mining
and Metallurgy Co., Ltd., China Metallurgical Information and Standardization
Institute.
Main drafters of this Part. Xia Huaibin, Xu Bin, Zhang Bin, Yi Jia, Zhang Zhiyong,
Sun Xiangli, Chen Shu, Yang Lin.
The previous editions of the standard replaced by this Part were released as
follows.
- GB/T 6730.8-1986.
Iron ores - Determination of iron (II) content -
Potassium dichromate titrimetric method
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 iron (II) content by
potassium dichromate titrimetric method.
This Part applies to the determination of iron (II) content in iron ores, iron
concentrates, sinters, and pellets. Determination range (mass fraction).
0.700%~30.00%.
2 Normative references
The following documents are indispensable for the application of this document.
For the dated references, only the editions with the dates indicated are
applicable to this document. For the undated references, the latest edition
(including all the amendments) are applicable to this document.
GB/T 6379.1 Accuracy (trueness and precision) of measurement methods
and results - Part 1.General principles and definitions
GB/T 6379.2 Accuracy (trueness and precision) of measurement methods
and results - Part 2.Basic method for the determination of repeatability and
reproducibility of a standard measurement method
GB/T 6682 Water for analytical laboratory use - Specification and test
methods
3 Principle
The general test portion is added with hydrochloric acid to transfer iron (II) into
the solution. USE potassium dichromate titrimetric method to measure the iron
content in the solution, to obtain the iron (II) content.
4 Reagents and materials
Unless otherwise stated, in the analysis, only reagents that are confirmed as
analytically pure and the grade 3 or higher distilled or deionized water that
meets the requirements of GB/T 6682 or water of equivalent purity shall be used.
4.1 Sodium fluoride.
4.2 Sodium bicarbonate.
4.6 Saturated sodium bicarbonate solution.
4.7 Mixture of sulfuric phosphoric acid, 4+4+2.
POUR 400 mL of phosphoric acid (ρ=1.70 g/mL), while stirring, into 400 mL of
water; then slowly add 200 mL of sulfuric acid (ρ=1.84 g/mL) and mix well.
4.8 Ferric trichloride solution, 30 g/L.
4.10 Ammonium ferrous sulfate solution, about 0.03 mol/L.
WEIGH 11.8 g of ammonium ferrous sulfate [(NH4)2Fe(SO4)2 • 6H2O] dissolved
in a certain volume of sulfuric acid (5+95); TRANSFER to a 1000 mL volumetric
flask; USE sulfuric acid (5+95) to dilute to the mark and mix well.
4.11 Sodium diphenylamine sulfonate indicator solution, 2 g/L.
WEIGH 0.1 g of sodium diphenylamine sulfonate; dissolve it in 50 mL of water;
ADD 2 drops~3 drops of concentrated sulfuric acid (ρ=1.84 g/mL); USE it after
the solution is clear.
5 Apparatus
In the analysis, only ordinary experimental apparatus are used. The burette,
one-mark volumetric flask, and one-mark pipette used shall meet the
requirements of GB/T 12805, GB/T 12806, and GB/T 12808, respectively.
6 Sampling and sample preparation
6.1 Laboratory sample
Laboratory samples for analysis shall be sampled and prepared in accordance
with GB/T 10322.1.The particle size shall be less than 100 μm. If the sample
contains high levels of combined water or readily oxidizable substance, its
particle size shall be less than 160 μm.
6.2 Predried sample
Thoroughly mix laboratory samples. According to the provisions of GB/T 6730.1,
dry the samples at 105 °C±2 °C; COOL to room temperature in a desiccator for
later use.
7 Analytical procedures
7.1 Number of determinations
The same predried sample shall be determined at least twice independently.
7.2 Test portion size
According to Table 1, weigh the test portion, accurate to 0.0001 g.
7.3 Blank test
DO a blank test along with the test portion. The reagents used must be taken
from the same reagent bottle.
7.4 Verification test
Analyze the same type of standard sample along with the test portion.
7.5 Determination
7.5.1 Determination of general test portion
PLACE the test portion (see 7.2) in a 300 mL conical flask; ADD about 0.5 g of
Iron (II) content (mass fraction) Test portion size
7.5.2 Determination of test portion containing metallic iron
The test portion contains metallic iron. ADD 30 mL of ferric trichloride solution
(see 4.8); PUT a non-magnetic metallic iron core stir bar (see 5.1) in; COVER
the porcelain crucible lid. STIR on a magnetic stirrer (see 5.2) at a speed of 200
r/min for 20 min; WASH out the stir bar; ADD about 0.5 g of sodium fluoride
(see 4.1), 30 mL of hydrochloric acid (see 4.3); then, follow the same steps as
7.5.1.
7.5.3 Determination of test portion containing high-valent manganese and
no metallic iron
7.5.4 Determination of blank value
ADD 6.00 mL of ammonium ferrous sulfate solution (see 4.10) and 25 mL of
mixture of sulfuric phosphoric acid (see 4.7) to the blank solution; ADD water to
a volume of about 100 mL. ADD 5 drops of sodium diphenylamine sulfonate
indicator solution (see 4.11); USE potassium dichromate standard titration
solution (see 4.9) to titrate to a stable purple; RECORD the volume V1 of the
potassium dichromate standard titration solution consumed.
8 Analysis results and their representation
8.1 Calculation of iron (II) content
According to formula (1), calculate the iron (II) content ωFe(II) in the sample and
express it as mass fraction (%).
8.2 General treatment of results
8.2.1 Repeatability and reproducibility
The precision of this Part is determined from the joint tests on samples with 5
levels of iron (II) content by 9 laboratories from 2014 to 2015.Each laboratory
determines the iron (II) content of each level 3 times under the repetitive
conditions specified in GB/T 6379.1.
8.3 Calculation of ferrous oxide content
According to formula (3), calculate the content ωFeO of ferrous oxide in the
sample, expressed as mass fraction (%).
9 Test report
The test report shall include the following information.
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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