GB/T 214-2007 English PDF (GBT214-2007)

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GB/T 214-2007: Determination of total sulfur in coal
GB/T 214-2007
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 75.160.10
D 21
Replacing GB/T 214-1996, GB/T 18856.8-2002
Determination of Total Sulfur in Coal
(ISO 334:1992, Solid Mineral Fuels - Determination of Total Sulfur - Eschka
Method, NEQ; ISO 351:1996, Solid Mineral Fuels – Determination
of Total Sulfur – High Temperature Combustion Method, NEQ)
ISSUED ON: NOVEMBER 01, 2007
IMPLEMENTED ON: JUNE 01, 2008
Issued by: General Administration of Quality Supervision, Inspection
and Quarantine;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 5
3 Eschka Method ... 5
4 Coulometric Titration Method ... 8
5 High Temperature Combustion Neutralization Method ... 12
6 Test Report ... 18
Determination of Total Sulfur in Coal
1 Scope
This Standard specifies the method principle, reagents and materials, apparatus, test
procedures, results calculation and precision, etc. of the Eschka method, coulometric
titration, high temperature combustion neutralization method for the determination of
sulfur in coal. For the arbitration analysis, the Eschka method shall be taken.
This Standard is applicable to the lignite, bituminous coal, anthracite, and coke; it is
also applicable to the dry coal samples of the water-coal-slurry.
2 Normative References
The provisions in following documents become the provisions of this Standard through
reference in this Standard. For dated references, the subsequent amendments
(excluding corrigendum) or revisions do not apply to this Standard, however, parties
who reach an agreement based on this Standard are encouraged to study if the latest
versions of these documents are applicable. For undated references, the latest edition
of the referenced document applies.
GB/T 212 Proximate Analysis of Coal (GB/T 212-2001, eqv ISO 11722:1999; eqv
ISO 1171:1997; eqv ISO 562:1998)
GB/T 483 General Rules for Analytical and Testing Methods of Coal
3 Eschka Method
3.1 Principle
The coal sample was mixed with the Eschka reagent and burned. The sulfur in the coal
was converted into sulfate; and then the sulfate ion generated the barium sulfate
precipitate. The total sulfur content in the coal shall be calculated based on the mass
of the barium sulfate.
3.2 Reagents and Materials
3.2.1 Eschka reagent (hereinafter referred to as Drinox): evenly mix the 2 pieces of the
mass of chemically pure light magnesium oxide (GB/T 9857) and 1 piece of mass of
chemically pure anhydrous sodium carbonate (GB/T 639); and grind them to the
substance with the particle size of less than 0.2mm; then store in a sealed container.
4.3.2 Electrolytic cell and electromagnetic stirrer
The electrolytic cell has a height of (120~180) mm, a capacity of no less than 400mL;
equipped with platinum electrolytic electrode pair with an area of about 150mm2, and
platinum indicator electrode pair with an area of about 15mm2. The response time of
the indicator electrode shall be less than 1s; the speed of the electromagnetic stirrer is
about 500r/min, which can be adjusted continuously.
4.3.3 Coulomb integrator
The integral linear error in the range of electrolytic current (0~350) mA shall be less
than 0.1%; equipped with (4~6) digital display or printer.
4.3.4 Sample-delivery program controller
It can move forward and backward flexibly according to the prescribed programs.
4.3.5 Air supply and purification device
It consists of the electromagnetic pump and purification tube. The air supply volume is
about 1500mL/min; and the air extraction volume is about 1000mL/min. The
purification tube contains sodium hydroxide and color-changing silica gel.
4.4 Test procedures
4.4.1 Test preparation
4.4.1.1 Raise the temperature of tubular high temperature furnace to 1150°C; use
another set of platinum rhodium-platinum thermocouple pyrometer to determine the
position ad length of high temperature zone, and the position at 500°C.
4.4.1.2 Adjust the sample-delivery program controller, so that the pre-decomposition
and pyrolysis of the coal samples are at the positions of 500°C and 1150°C,
respectively.
4.4.1.3 Fill the outlet of the combustion tube with cleaned and dried glass fiber cotton.
Fill the aluminum silicate cotton with a thickness of about 3 mm at a distance of (80 ~
100) mm from the outlet end.
4.4.1.4 Assemble the following devices together, such as program controller, tubular
high temperature furnace, Coulomb integrator, electrolytic cell, electromagnetic stirrer,
and air supply and purification device. The connection among the combustion tube,
piston and the electrolytic cell shall be close to each other, and sealed with a silicone
rubber tube.
4.4.1.5 Start the air extraction and air supply pumps; adjust the air extraction flow to
1000mL/min. Then close the piston between the electrolytic cell and combustion tube.
4.4.3.2 Start the air supply pump and the air extraction pump; and adjust the air
extraction flow to 1000mL/min. Under air extraction condition, add the electrolyte to
the electrolytic cell and start the electromagnetic stirrer.
4.4.3.3 Put a small amount of non-measured coal sample into the porcelain boat;
perform the endpoint potential adjustment test as described in 4.4.3.4. If the display
value of the Coulomb integrator is 0 after the test, the measurement shall be repeated
until the display value is no longer to be 0.
4.4.3.4 Take (0.05±0.005) g (accurate to 0.0002g) of air-dry coal sample in a porcelain
boat with a particle size of less than 0.2mm; and cover the coal sample with a thin layer
of tungsten trioxide. Place the porcelain boat on the quartz tray for sample delivery,
start the sample-delivery program controller, and the coal sample shall be
automatically sent into the furnace, and the coulometric titration shall begin
immediately. After the test, the Coulomb integrator displays the milligrams or mass
fraction of sulfur, or printed by a printer.
4.4.4 Calibration inspection
During the measurement of the instrument, coal reference materials or other control
samples should be used regularly (after every 10 ~ 15 measurements are
recommended) to verify the stability and validity of the sulfur analyzer. If the
measurement value of the coal reference material or other control samples exceed the
uncertainty range (control limit) of the standard value; the instrument shall be re-
calibrated according to the above procedures; and re-measure the samples since the
previous inspection.
4.5 Result calculation
If the Coulomb integrator finally displays the milligrams of sulfur, the total sulfur mass
fraction shall be calculated as per Formula (2):
Where:
St,ad – total sulfur mass fraction in the coal samples for general analysis, in %;
m1 – display value of Coulomb integrator, in mg;
m – mass of coal sample, in mg.
4.6 Precision of method
The repeatability and reproducibility for the determination of total sulfur by Coulometric
titration method can refer to the provisions of Table 2.
5.2.9 Sodium hydroxide standard solution: c (NaOH) = 0.03mol/L.
5.2.9.1 Preparation of sodium hydroxide standard solution
Take 6.0g of guarantee reagent of sodium hydroxide (GB/T 629); dissolve it in 5000mL
of distilled water that has been boiled and cooled; mix well; put it in the bottle; and plug
it with a rubber stopper.
5.2.9.2 Calibration of the concentration of sodium hydroxide standard solution
Take (0.2~0.3) g (accura...