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GB/T 16659-2024: Determination of mercury of coal
GB/T 16659-2024
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 73.040
CCS D 21
Replacing GB/T 16659-2008
Determination of Mercury of Coal
(ISO 15237.2016, Solid Mineral Fuels – Determination of Total Mercury
Content of Coal)
ISSUED ON. APRIL 25, 2024
IMPLEMENTED ON. NOVEMBER 1, 2024
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 Terms and Definitions... 4
4 Reagents and Materials... 4
5 Apparatus... 6
6 Test Conditions... 7
7 Samples... 7
8 Cold Atomic Absorption Spectrophotometry... 8
9 Atomic Fluorescence Spectrometry... 10
10 Mercury Detector Method... 12
11 Solid Sampling Direct Mercury Detector Method... 12
12 Precision... 14
13 Test Report... 15
Appendix A (Informative) Instrument Reference Working Conditions... 16
Determination of Mercury of Coal
1 Scope
This Document specifies the reagents and materials, instruments and equipment, test conditions,
samples, test procedures, test data processing, precision and test reports for the determination
of mercury in coal by cold atomic absorption spectrophotometry, atomic fluorescence
spectrometry, mercury detector method and solid sampling direct mercury detector method.
This Document is applicable to the determination of mercury content in lignite, bituminous coal,
anthracite and coal gangue.
2 Normative References
The provisions in following documents become the essential provisions of this Document
through reference in 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) is applicable to this Document.
GB/T 213 Determination of calorific value of coal
GB/T 474 Preparation of coal sample
GB/T 483 General rules for analytical and testing methods of coal
GB/T 6682 Water for analytical laboratory use - Specification and test methods
GB/T 19494.2 Mechanical sampling of coal - Part 2.Method for sample preparaion
3 Terms and Definitions
For the purposes of this Document, there are no terms and definitions apply.
4 Reagents and Materials
Unless otherwise specified, only reagents confirmed as analytically pure are used in the analysis;
and the used water is Class-II water or water of equivalent purity as specified in GB/T 6682.
4.17 Potassium borohydride solution or sodium borohydride solution. 5.0g/L.
Weigh 5.0g of potassium borohydride (guarantee reagent) or sodium borohydride (guarantee
reagent) and dissolve it in 1L of potassium hydroxide solution (4.16); prepare it before use.
4.18 Mercury standard stock solution. 100μg/mL.
Accurately weigh 0.1354g (accurate to 0.0002g) of guaranteed reagent of mercury chloride that
has been fully dried in a desiccator into a 100mL beaker; dissolve it with the fixed solution
(4.13); transfer it to a 1L volumetric flask. And then dilute it to the scale with the fixed solution
(4.13) and make constant volume. Or use a commercially available certified standard solution.
4.19 Mercury standard intermediate solution. 1.0μg/mL.
Accurately pipette 5.00 mL of mercury standard stock solution (4.18) into a 500 mL volumetric
flask; dilute to the scale with the fixed solution (4.13); and make constant volume.
4.20 Mercury standard working solution. 0.1 μg/mL.
Accurately pipette 10.00 mL of mercury standard intermediate solution (4.19) into a 100 mL
volumetric flask; dilute to the scale with the fixed solution (4.13); and make constant volume.
5 Apparatus
5.1 Analytical balance. graduation value 0.1mg.
5.2 Atomic absorption spectrophotometer. equipped with a mercury hollow cathode lamp with
a wavelength of 253.7nm.
5.3 Atomic fluorescence spectrometer. equipped with a mercury hollow cathode lamp with a
wavelength of 253.7nm.
5.4 Mercury detector. cold atomic absorption mercury detector or cold atomic fluorescence
mercury detector.
5.5 Solid sampling direct mercury detector.
5.6 Electric heating plate. controllable in the range of 50℃~200℃.
5.7 Microwave digestion system. including microwave digestion instrument, digestion tank,
etc.
5.8 Mercury vapor generation bottle. a conical bottle with a scale of 50mL and a tightly fitting
plug, with inlet and outlet pipes on the plug and the end of the inlet pipe 5mm~10mm away
from the bottom of the bottle.
5.9 Sample boat. made of quartz or nickel, with a volume of no less than 150μL; suitable for
measurement of solid sampling direct mercury detector.
6 Test Conditions
6.1 The test shall be carried out in a room with a temperature above 10°C.
6.2 All glassware used in the test must be soaked in nitric acid solution (4.10) for at least 24 h
before use, and then washed by water for later use.
7 Samples
7.1 Specimens
The coal samples for the general analysis test shall be prepared according to GB/T 474 or GB/T
19494.2.
7.2 Preparation of sample solution
7.2.1 Wet digestion
Weigh about 0.1g (accurate to 0.0002g) of the coal sample for general analysis test into a
mercury vapor generator bottle. Add 50mg of vanadium pentoxide (4.6) and a few drops of
anhydrous ethanol (4.8) to moisten the specimen; then add 10mL of nitric acid (4.3);
immediately cover the mercury vapor generator bottle with a porcelain cover; leave it overnight.
Add 4mL of sulfuric acid (4.4) and place it on a electric hot plate; first heat at (120±10) ℃ for
about 1.5h; then gradually increase the temperature to (160±10) ℃; and continue heating until
sulfur trioxide smoke just emerges. If black particles are found, it means that the specimen has
not been completely decomposed; and add 3mL~5mL of nitric acid (4.3); and then continue
heating until sulfur trioxide smoke just emerges. Remove the mercury vapor generator bottle
and cool it. Add 20mL of water and 2mL of hydrogen peroxide (4.7); stand for 5 min; place it
on a electric hot plate and slowly heat it to boil and prevent the solution from splashing. At this
time, the solution shall be blue. If the solution is brown-red, add an appropriate amount of
hydrogen peroxide (4.7) and boil it again. Remove the mercury vapor generator bottle; cool it;
transfer the solution to a 50mL volumetric flask; dilute it to the scale with water; and make
constant volume.
7.2.2 Oxygen bomb combustion
According to the provisions of GB/T 213, weigh about 0.99g~1.01g (accurate to 0.0002g) of
coal sample for general analytical test in a dry combustion dish and ignite it for combustion.
After the combustion is completed, wait for the oxygen bomb to cool down, and then slowly
and evenly release the gas. The entire release process lasts for no less than 2 min. Transfer the
Draw the working curve with the absorbance of the standard solution as the ordinate and the
corresponding mass of mercury (μg) as the abscissa.
8.2.1.2 Drawing the working curve of oxygen bomb combustion method
8.2.1.2.1 Accurately pipette 0.00mL, 1.00mL, 2.00mL, 5.00mL, and 10.00mL of mercury
standard working solution (4.20) to five 50mL volumetric flasks respectively. Add 5mL of nitric
acid solution (4.9) and 0.5mL of potassium permanganate solution (4.14); shake well. And
slowly titrate hydroxylamine hydrochloride solution (4.15) while shaking the volumetric flask
until the color of potassium permanganate just fades; dilute to the scale with water; and make
constant volume.
8.2.1.2.2 Transfer the standard solution to the mercury vapor generating bottle; and perform the
rest of the operation as in 8.2.1.1.2.
8.2.1.3 Drawing the working curve of microwave digestion method
8.2.1.3.1 Accurately pipette 0.00mL, 0.25mL, 0.50mL, 1.00mL, and 1.50mL of the mercury
standard working solution (4.20) into five 50mL volumetric flasks respectively; add 5mL of
nitric acid solution (4.3); dilute to the scale with water; and make constant volume.
8.2.1.3.2 Transfer the standard solution into the mercury vapor generating bottle; and perform
the rest of the operation as in 8.2.1.1.2.
8.2.2 Determination of sample
Transfer the specimen solution (7.2.1 or 7.2.3) or accurately pipette 50mL of the specimen
solution (7.2.2) into the mercury vapor generating bottle; add 1mL of stannous chloride solution
(4.11) and immediately cover the bottle with the stopper; and shake well. After standing for a
while, connect the mercury vapor generating bottle to the atomic absorption spectrophotometer
for determination and record the maximum absorbance; and obtain the mercury content in the
specimen solution from the working curve.
8.2.3 Blank test
For each batch of coal samples, prepare two blank solutions (without adding coal samples)
according to 7.2; and determine the mercury content in the blank solutions according to 8.2.2;
and take the average value as the blank value.
8.3 Test data processing
8.3.1 Calculation of result
8.3.1.1 When wet digestion or microwave digestion is used to prepare the specimen solution;
the mercury content in the coal sample for general analytical test is calculated according to
Formula (1).
Where.
w (Hgad) - the content of mercury in the coal sample for general analysis test, in μg/g;
m1 - the mass of mercury in the specimen solution obtained from the working curve, in μg;
m2 - the mass of mercury in the blank solution obtained from the working curve, in μg;
m - the mass of the coal sample for general analysis test, in g.
8.3.1.2 When the specimen solution is prepared by oxygen bomb combustion, the content of
mercury in the coal sample for general analysis test is calculated according to Formula (2).
Where.
w (Hgad) - the content of mercury in the coal sample for general analysis test, in μg/g;
m1 - the mass of mercury in the specimen solution obtained from the working curve, in μg;
m2 - the mass of mercury in the blank solution obtained from the working curve, in μg;
2 – decantation multiple;
m - the mass of the coal sample for general analysis test, in g.
8.3.2 Expression of result
The result is the arithmetic mean of repeated measurements, rounded off to three digits after
the decimal point according to GB/T 483.
9 Atomic Fluorescence Spectrometry
9.1 Method summary
The sample is treated into a solution. In an acidic medium, potassium borohydride is used as a
reducing agent to reduce the mercury in the test solution to mercury vapor. Argon is used as a
carrier gas to introduce it into the atomizer and measured by atomic fluorescence spectrometer.
9.2 Test procedures
m – the mass of coal sample for general analysis test, in g.
9.3.2 Expression of result
The same as 8.3.2.
10 Mercury Detector Method
10.1 Method summary
Treat the sample into a solution to convert mercury into divalent mercuric ions. Under acidic
conditions, use stannous chloride as a reducing agent to reduce the mercury ions to mercury
atomic vapor; and measure with a mercury detector.
10.2 Test procedures
10.2.1 Drawing the working curve
Prepare standard series solutions according to the requirements of 8.2.1.Connect the mercury
vapor generating bottle to the mercury detector; measure and record the maximum absorbance
or fluorescence intensity at a wavelength of 253.7nm. Draw a working curve with the
absorbance or fluorescence intensity of the standard solution as the ordinate and the
corresponding mass of mercury (μg) as the abscissa.
10.2.2 Determination of sample
Except for not adding mercury standard solution, transfer the specimen solution (7.2.1 or 7.2.3)
or accurately pipette 50mL of the specimen solution (7.2.2) into the mercury vapor generating
bottle; add 1mL of stannous chloride solution (4.11) and immediately cover the bottle with a
stopper; and shake well. The rest of the operation is the same as 10.2.1; and the mercury content
in the specimen solution is obtained from the working curve.
10.2.3 Blank test
The same as 8.2.3.
10.3 Test data processing
The same as 8.3.
11 Solid Sampling Direct Mercury Detector Method
11.1 Method summary
The sample is directly sent to the mercury detector; and the sample is dried, heated and
decomposed in the oxygen flow. The oxides of halogen, nitrogen and sulfur in the
decomposition product are adsorbed; and the mercury is catalytically reduced and amalgamated
in the amalgamation tube to be enriched. After the system is purged with oxygen, the
amalgamation tube is quickly heated to release mercury vapor, which is loaded into the
absorption cell for determination through oxygen.
11.2 Test procedures
11.2.1 Purification of sample boat
Before use, remove the residual sample from the nickel sample boat; rinse it with water; and
then put it in a high-temperature furnace; burn it at 650℃ for 10min; and cool it. Before use,
soak the quartz sample boat in nitric acid solution (4.10) for 30min; rinse it with water; and dry
it.
11.2.2 Drawing the working curve
11.2.2.1 Working curve of low mercury content absorption cell
11.2.2.1.1 Accurately pipette 0.00mL, 2.00mL, 5.00mL, 10.00mL, 15.00mL, and 20.00mL of
mercury standard intermediate solution (4.19) into six 100mL volumetric flasks respectively;
dilute to scale with nitric acid solution (4.10); and make constant volume.
11.2.2.1.2 Respectively pipette 100μL of series of mercury standard solutions (11.2.2.1.1) and
add them to the sample boat for determination. Repeat the determination for 2 times for each
standard solution; take the average value. Draw the working curve of low mercury content
absorption cell with the corresponding mercury mass (ng) as the abscissa and the absorbance
as the ordinate.
11.2.2.2 Working curve of high mercury content absorption cell
11.2.2.2.1 Accurately pipette 0.00mL, 0.20mL, 0.50mL, 1.00mL, 2.00mL, and 5.00mL of
mercury standard stock solution (4.18) into six 100mL volumetric flasks respectively; dilute to
scale with nitric acid solution (4.10); and make constant volume.
11.2.2.2.2 Respectively pipette 100μL of mercury series standard solutions (11.2.2.2.1) into the
sample...