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GB/T 30732-2014 (GB/T30732-2014, GBT 30732-2014, GBT30732-2014)
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GB/T 30732-2014: PDF in English (GBT 30732-2014)

GB/T 30732-2014
GB
NATIONAL STANDARD OF THE
PEOPLE'S REPUBLIC OF CHINA
ICS 73.040
D 21
Proximate analysis of coal - Instrumental method
ISSUED ON: JUNE 9, 2014
IMPLEMENTED ON: OCTOBER 1, 2014
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of PRC;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Method summary ... 4
4 Reagents and materials ... 5
5 Instruments and Equipment ... 5
6 Measurement procedures ... 7
7 Result calculation ... 8
8 Method precision ... 10
9 Test report ... 11
Appendix A (Informative) Structural schematic diagram of several automatic industrial
analyzers ... 12
Appendix B (Informative) Correction for buoyancy effects ... 16
Proximate analysis of coal - Instrumental method
1 Scope
This standard specifies the method summary, reagents and materials, instruments and
equipment, measurement procedures, calculation of results, precision for determining
the moisture, ash content and volatiles of coal by automatic industrial analyzers, as well
as calculation of fixed carbon.
This standard applies to lignite, bituminous coal, and anthracite.
2 Normative references
The following documents are essential for the application of this document. For dated
references, only the dated version applies to this document. For undated referenced
documents, the latest version (including all amendments) applies to this document.
GB/T 212 Proximate analysis of coal
GB/T 483 General rules for analytical and testing methods of coal
3 Method summary
3.1 Moisture determination
A certain amount of general analysis test coal sample is taken and dried in a heating
furnace in air or nitrogen flow at 105 °C to 110 °C until the mass is constant; the
moisture mass fraction of the coal sample is calculated based on the mass loss of the
coal sample.
3.2 Determination of ash content
A certain amount of general analysis test coal sample is taken and heated to (815±10) ℃
in a heating furnace according to the specified procedure; during this process, it is ashed
and burned in air or oxygen flow until the mass is constant. The ash content mass
fraction of the coal sample is calculated according to the mass of the residue.
3.3 Determination of volatile matter
A certain amount of general analysis test coal sample is taken and heated in a heating
furnace for 7 minutes at (900±10) °C without air; the moisture mass fraction of the coal
sample is subtracted from the mass fraction of the decrease mass in the mass of the coal
sample, the remaining is taken as the volatile mass fraction of the coal sample.
4 Reagents and materials
4.1 Nitrogen: with a purity of 99.9%.
4.2 Oxygen: 99.9%, no hydrogen.
4.3 Anhydrous calcium chloride: chemically pure, granular.
4.4 Color-changing silica gel: industrial supplies.
4.5 Crucible: It is used for measuring moisture and ash content, made of porcelain or
quartz, with sufficient bottom area to ensure that the mass of the coal sample per square
centimeter does not exceed 0.15 g after the coal sample is spread out.
4.6 Volatile matter crucible: It is made of porcelain or quartz, and equipped with a tight
cover, the shape and size comply with the requirements of GB/T 212.
4.7 Certified coal reference materials: national first-class coal physical property and
chemical composition analysis reference materials.
5 Instruments and Equipment
5.1 Automatic industrial analyzer
5.1.1 General
The automatic industrial analyzer shall include a high-temperature furnace, a built-in
balance, a sample receiving and conveying device, a temperature measurement and
control and display system, a furnace atmosphere control system, a result display and
printing device, etc. Appendix A gives the structural schematic diagrams of several
automatic industrial analyzers. The automatic industrial analyzer shall record and
provide detailed information such as empty crucible mass, coal sample mass, hot
crucible mass, and buoyancy effect correction value in each test by printing or other
means.
5.1.2 High-temperature furnace
5.1.2.1 Moisture determination furnace: It can control the temperature between 105 °C
and 110 °C, has a sufficient constant temperature zone, a small free space in the furnace,
and ventilation and exhaust ports. The constant temperature zone is measured at least
once a year.
6 Measurement procedures
6.1 General
6.1.1 Moisture and ash content can be measured continuously with the same sample in
the same heating furnace, or two samples can be measured separately; volatile matter
shall be weighed and measured separately.
6.1.2 Each measurement shall use one or more empty crucibles at the same time to
correct the buoyancy effect of the thermal mass of the crucible.
NOTE: See Appendix B for buoyancy effect correction calculation.
6.1.3 All weighings during the test shall be accurate to 0.0002 g.
6.1.4 The instrument shall be operated according to the instrument instruction manual.
6.1.5 The instrument shall be inspected from time to time by using certified coal
reference materials based on actual usage conditions.
6.2 Moisture determination
6.2.1 In the measuring instrument, accurately weigh the crucible that has been pre-dried
to a constant mass, add (1±0.1) g general analysis test coal sample to the crucible, flatten
it, and weigh it accurately.
6.2.2 According to the provisions of 5.1.4, air or nitrogen must be introduced into the
heating furnace in advance (nitrogen must be introduced for lignite samples). The
furnace temperature slowly rises to 105 ℃~110 ℃ and remains constant. The
instrument automatically weighs according to the set time interval until the mass is
constant (the mass decrease does not exceed 0.0005 g at a 10-minute interval) or the
mass increases. In the latter case, the mass before the mass increase is used as the basis
for calculation.
6.3 Ash content determination
6.3.1 Individual determination by a slow ashing method
6.3.1.1 Accurately weigh the crucible that has been pre-dried to a constant mass in an
environment close to room temperature, add (1±0.1) g of general analysis test coal
sample to the crucible, flatten it, and weigh it accurately.
6.3.1.2 According to the provisions of 5.1.4, introduce air or oxygen into the furnace,
slowly increase the furnace temperature to 500 ℃ in no less than 30 minutes, and
maintain it at this temperature for 30 minutes. Continue to raise the temperature to
(815±10) ℃, and burn the sample until the mass is constant at this temperature. The
calculation is based on the mass of the residue after the last ignition. During the burning
process, the instrument automatically weighs according to the set time interval until the
mass change does not exceed 0.0005 g at 10-minute intervals.
6.3.2 Continuous determination by a slow ashing method
After the moisture measurement is completed (see 6.2), measure the ash content
according to steps 6.3.1.2.
6.3.3 Rapid determination
Rapidly heat the furnace to (815±10) ℃ at a speed that will prevent deflagration of the
coal sample (heating time shall not be less than 30 minutes). Otherwise, the rest is the
same as 6.3.1.1 and 6.3.1.2. Airflow shall be increased if necessary.
6.4 Determination of volatile matter
6.4.1 In the weighing chamber of the measuring instrument, accurately weigh the
crucible that has been pre-dried to a constant mass, add (1±0.01) g general analysis test
coal sample into the crucible, flatten it, and weigh it accurately. Lignite and long-flame
coal samples shall be pressed into cakes first, and then cut into small pieces with a
particle size of about 3 mm.
6.4.2 Preheat the high-temperature furnace to 900 ℃~920 ℃ (if necessary, nitrogen can
be introduced to maintain an inert atmosphere in the furnace according to 5.1.4). The
sample receiving and conveying device will send the covered crucible into the constant
temperature zone of the high-temperature furnace. Heat it accurately for 7 minutes
before returning it to the weighing room, and weigh it again after cooling to the set
temperature.
6.4.3 After the volatile matter crucible is placed in the high-temperature furnace, the
furnace temperature shall return to (900±10) ℃ within 3 minutes, and then remain at
(900±10) ℃; otherwise, the test will be invalid. Heating time includes temperature
recovery time.
7 Result calculation
7.1 Moisture calculation
Calculate the moisture content of the general analysis test coal sample according to
formula (1).
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.