SN/T 2763.3-2012 PDF in English
SN/T 2763.3-2012 (SN/T2763.3-2012, SNT 2763.3-2012, SNT2763.3-2012)
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Chemical analysis of nickel laterite ore. Part 3: Determination of total iron content. Titanium (Ⅲ) chloride reduction methods
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Standards related to (historical): SN/T 2763.3-2012
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SN/T 2763.3-2012: PDF in English (SNT 2763.3-2012) SN/T 2763.3-2012
SN
ENTRY & EXIT INSPECTION & QUARANTINE STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
Chemical analysis of nickel laterite ore - Part 3:
Determination of total iron content - Titanium (III)
chloride reduction methods
ISSUED ON: MAY 07, 2012
IMPLEMENTED ON: NOVEMBER 16, 2012
Issued by: General Administration of Quality Supervision Inspection and
Quarantine of PRC
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Principles ... 4
4 Reagent ... 5
5 Instrument ... 6
6 Specimen ... 6
7 Analytical procedures ... 6
8 Calculation of analysis results ... 8
9 Repeatability and reproducibility ... 9
Appendix A (Normative) Determination of wet moisture content in nickel laterite
ore - Gravimetric method ... 10
Chemical analysis of nickel laterite ore - Part 3:
Determination of total iron content - Titanium (III)
chloride reduction methods
1 Scope
This part of SN/T 2763 specifies a method for the determination of total iron
content in nickel laterite ore by the titanium (III) chloride reduction method.
This section applies to the determination of total iron content in nickel laterite
ore. Measuring range (mass fraction) is: 9% ~ 50%.
2 Normative references
The following documents are essential to the application of this document. For
the dated documents, only the versions with the dates indicated are applicable
to this document; for the undated documents, only the latest version (including
all the amendments) are applicable to this standard.
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 (ISO 5725-2)
GB/T 6682 Water for analytical laboratory use - Specification and test
methods
GB/T 12805 Laboratory glassware - Burettes
GB/T 12806 Laboratory glassware - One-mark volumetric flasks
GB/T 12808 Laboratory glassware - One-mark pipettes
3 Principles
The specimen is melted with sodium peroxide at 800 °C and leached with
hydrochloric acid. After the stannous chloride is reduced, sodium tungstate is
used as an indicator and titanium trichloride is used to reduce the remaining
high-valent iron to a low price to produce "tungsten blue"; then potassium
dichromate is used to oxidize until the blue disappears; sulfur and phosphorus
At the same time, weigh the sample and determine the wet moisture content in
accordance with Appendix A.
7.3 Determination
7.3.1 Decomposition of sample
Place the sample (7.2) in a 30 mL corundum crucible. Add 4 g of sodium
peroxide (4.1). Mix it uniformly. Cover it. Bake it on an electric stove until the
sodium peroxide turns black. Then place it in a high-temperature furnace at
800 °C to melt for 15 minutes. Take it out to cool it. Place it in a 400 mL beaker.
Add 40 mL of warm water to soak the crucible. Add 30 mL of hydrochloric acid
(4.3). Boil it slightly for about 5 minutes to drive off the hydrogen peroxide. Cool
it down. Heat at low temperature to dissolve the sample. Use hot water to wash
out the crucible. Adjust the volume of the solution to 150 mL. Add stannous
chloride (4.8) dropwise to light yellow. Remove it. Use running water to cool it
to room temperature.
7.3.2 Titration
Add 15 drops of sodium tungstate (4.9). Use titanium trichloride (4.11) to titrate
it until it turns blue. Then add potassium dichromate standard solution (4.14)
until colorless. Immediately add 10 mL of sulfur phosphorus mixed acid (4.10),
3 drops of sodium diphenylamine sulfonate solution (4.12). When the content
is 9% ~ 30%, use potassium dichromate standard solution (4.14) to titrate to a
stable purple. When the content is 30% ~ 50%, use potassium dichromate
standard solution (4.15) to titrate to a stable purple.
Since the specimen contains a certain amount of chromium, the tungsten blue
will fade and show a light green background. When adjusting the tungsten blue,
it shall carefully observe the fading situation of the tungsten blue; pay attention
to distinguish the background color from the fading of tungsten blue.
7.4 Blank test
Use the same amount of reagent (no sample added) to decompose the blank
test in accordance with 7.3.1. The titration is carried out according to 7.3.2.
Before adding the sulfur-phosphorus mixed acid, add 10 mL of ferrous
ammonium sulfate solution (4.13). After the titration, record the consumption of
potassium dichromate solution in milliliters (A); then add 10 mL of ammonium
ferrous sulfate solution (4.13). After titration, record the consumption of
potassium dichromate solution in milliliters (B), then V0 = A - B is the blank value.
The concentration of the potassium dichromate standard solution shall be
consistent with the concentration of the standard solution used in the
determination of samples according to 7.3.2.
Appendix A
(Normative)
Determination of wet moisture content in nickel laterite ore - Gravimetric
method
A.1 Scope
This Appendix specifies the gravimetric method for the determination of wet
moisture content in analytical samples of nickel laterite ore.
This Appendix is applicable to the determination of moisture content of
analytical samples of nickel laterite ore.
A.2 Principles
The sample that has been air-dried under laboratory conditions is dried to a
constant weight in a drying oven at 105 °C ~ 110 °C. The mass change before
and after drying is the mass of the wet moisture.
A.3 Instrument
A.3.1 Weighing bottle, the diameter is not less than 5 cm; it is equipped with a
tightly sealed ground cap.
A.3.2 Drying box, which can maintain the temperature in the range of 105 °C ~
110 °C.
A.4 Analytical procedures
A.4.1 Sample
Pre-dry the weighing bottle (A.3.1) in a drying oven (A.3.2) at 105 °C ~ 110 °C.
Weigh it. Weigh 1 g of the sample that has been pre-dried in the air into the
weighing bottle, accurate to 0.0002 g. Spread it flat in the weighing bottle.
A.4.2 Determination
Place the open weighing bottle containing the sample (A.4.1) and bottle cap in
a drying oven (A.3.2) that has been stabilized at 105 °C ~ 110 °C. Dry it for 1
hour. Take it out. Immediately cover the ground cap. Put it in a desiccator to
cool for 20 min ~ 30 min. Take out the weighing bottle from the desiccator.
Gently open the ground cap. Then quickly close it. Weigh it.
Repeat the drying (30 min each time), cooling and weighing operations, until
the difference between two consecutive weighing does not exceed 0.005 g. If
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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