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GB 475-2008: [GB/T 475-2008] Method for manual sampling of commercial coal
GB 475-2008 (GB/T 475-2008)
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 73.040
D 21
GB 475-2008
Replacing GB 475-1996
Method for Manual Sampling of Commercial Coal
(ISO 18283:2006, Hard Coal and Coke - Manual Sampling, MOD)
Converted to recommended standard in accordance with 2017 No.7
Announcement by the Standardization Administration
ISSUED ON: DECEMBER 4, 2008
IMPLEMENTED ON: MAY 1, 2009
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative References ... 5 
3 Terms and Definitions ... 5 
4 General Principles and Precision of Sampling ... 9 
5 Sampling Scheme ... 12 
6 Sampling Method - Primary Increment Sampling Method ... 24 
7 Intermittent Sampling Method ... 32 
8 Various Coal Sample Taking ... 32 
9 Manual Sampling Instruments ... 33 
10 Packaging and Marking of Coal Sample ... 39 
11 Report of Sampling ... 39 
Appendix A (informative) Comparison Checklist of Chapter No. in this Standard
and ISO 18283:2006 (E) ... 41 
Appendix B (informative) Technical Differences and Causes between this
Standard and ISO 18283:2006 (E) ... 43 
Appendix C (normative) Sampling Precision Verification and Bias Test ... 46 
Appendix D (informative) Examples of Calculation of Increment Mass,
Sampling Unit Number and Sampling Unit Increment Number ... 51 
Appendix E (informative) Handling Method for Large Block of Materials with
Particle Size of over 150 mm or Other Particle Sizes ... 55 
Method for Manual Sampling of Commercial Coal
1 Scope
This Standard stipulates the terms and definitions of manual sampling method of
commercial coal; general principles and precision of sampling; establishment of
sampling schemes; sampling methods; manual sampling instruments; packaging and
marking of coal sample; sampling report.
This Standard is applicable to lignite, bituminous coal and anthracite.
2 Normative References
Through the reference in this Standard, clauses of the following documents become
clauses of this Standard. In terms of references with a specific date, all the subsequent
modification sheets (excluding the corrected content) or the revised editions are not
applicable to this Standard. However, all parties that reach an agreement in
accordance with this Standard are encouraged to explore the possibility of adopting
the latest version of these documents. In terms of references without a specific date,
the latest version is applicable to this Standard.
GB/T 19494.3 Mechanical Sampling of Coal - Part 3: Determination of Precision and
Bias Test (GB/T 19494.3-2004, ISO 13909-7:2001, ISO 13909-8:2001, NEQ)
3 Terms and Definitions
The following terms and definitions are applicable to this Standard.
3.1 Coal Sample
Coal sample refers to a representative portion of coal taken from coal to determine
certain characteristics.
3.2 Sample of Commercial Coal
Sample of commercial coal refers to coal sample that represents average properties
of commercial coal.
3.3 Test Sample of Coal
Test sample of coal refers to coal sample that is prepared to satisfy a certain specific
test requirement.
3.4 Common Sample of Coal
Common sample of coal refers to coal sample that is taken for multiple tests.
3.5 Moisture Sample of Coal
Moisture sample of coal refers to coal sample that is specifically taken for the
determination of total moisture.
3.6 General Sample of Coal
General sample of coal sample that is specifically taken for the preparation of general-
analysis test sample of coal.
3.7 General-analysis Test Sample of Coal
General-analysis test sample of coal refers to coal sample that is crushed to a particle
size of less than 0.2 mm and reaches an air-dried state, which is used for the
determination of most physical and chemical properties.
3.8 Size Analysis Sample of Coal
Size analysis sample of coal refers to coal sample that is specifically taken for particle
size analysis.
3.9 Increment
Increment refers to a sample taken by one-time operation of the sampling device, or,
interception of a full cross section of a coal stream.
3.10 Sub-sample
Sub-sample refers to coal sample that is constituted of several primary increments that
are uniformly distributed throughout the sampling unit.
3.11 Gross Sample
Gross sample refers to coal sample merged from all increments taken from a sampling
unit.
3.12 Primary Increment
Primary increment refers to increment taken in the first stage of sampling, before any
crushing and division.
3.13 Divided Sample
Divided sample refers to a retained portion after division for the purpose of reducing
sample mass.
3.14 Sampling
Sampling refers to the process of taking a representative portion of coal from a large
amount of coal.
3.15 Continuous Sampling
Continuous sampling refers to the process of taking a gross sample from each
sampling unit; during the sample, increment points are distributed at a uniform interval.
3.16 Intermittent Sampling
Intermittent sampling refers to the process of taking samples from only several
sampling units.
3.17 Lot
Lot refers to an independent coal quantity that requires the determination of global
property.
3.18 Sampling Unit
Sampling unit refers to coal quantity of a gross sample taken from a lot of coal. A lot of
coal may be one or multiple sampling units.
NOTE: equivalent to sub-lot (part of a lot for which a test result is required) in ISO 18283.
3.19 Nominal Top Size
Nominal top size refers to corresponding sieve size of sieve that is closest to (but not
greater than) 5% of the accumulative mass fraction of articles on the sieve.
3.20 Precision
Precision refers to the degree of consistency between independent test result obtained
under specified conditions.
NOTE 1: it is also expressed in an index of precision, for example, two standard deviations.
NOTE 2: the precision of coal sampling is the limit value of the difference (under 95%
probability) between the determination result of a single sampling and the
average value of the determination results of countless samplings of the same
coal (same source, same property).
3.21 Systematic Sampling
Systematic sampling refers to the process of taking increments in accordance with the
same time, space or mass interval, but the first increment is randomly taken within the
first interval, while the remaining increments are taken at a selected interval.
3.22 Random Sampling
3.30 Random Error
Random error refers to an error which is statistically independent of the previous errors.
NOTE: this signifies that in a series of random errors, any two errors are uncorrelated, and
it is impossible to predict any individual errors. Errors are divided into system
errors (bias) and random errors. In an observation series, as the number of
observations increases, the average value of random errors tends to be zero.
3.31 Bias
Bias refers to system error. As a result of this, the average of a series of results is
always higher than or lower than the value obtained through reference method.
3.32 Relevant Bias
Relevant bias refers to permissive bias of actual importance or consent from all parties
of a contract.
4 General Principles and Precision of Sampling
4.1 General Principles of Sampling
The objective of coal sampling and sample preparation is to obtain a test coal sample
whose test results are representative of the entire lot of coal being sampled.
The basic process of sampling and sample preparation is: firstly, from many points that
are distributed throughout the entire lot of coal, collect a significant amount of coal,
namely, primary increment; then, directly incorporate the various primary increments
into a gross sample, or, incorporate them after division; finally, through a series of
sample preparation procedure, prepare the gross sample into test coal samples of the
requested number and type.
The basic requirement of sampling is that all particles of the lot of coal being sampled
may enter the sampling equipment; each particle has an equal probability of being
taken into the sample.
In order to make sure that the precision of the test results of the obtained sample
satisfies the requirements, take the following factors into consideration during the
sample:
a) Variability of coal (generally, measured through the variance of primary
increment);
b) The number of gross samples taken from this lot of coal;
c) The number of increments of each gross sample;
When sampling is directly conducted from stationary coal, full-depth sample or different
depths (up, middle, down, or up and down) of sample shall be taken. When it can be
guaranteed that the quality of coal in the carrier is uniform, and stratified loading of
coal with different qualities does not exist, sampling from the top of the carrier is also
allowed.
No matter which mode is adopted for sampling, it shall all pass bias test to prove that
it has no substantial bias.
Under the circumstance of sampling from the top of train, truck and barge, immediately
take samples after the loading. When sampling is conducted after transportation, dig
a pit to 0.4 m ~ 0.5 m, then, take samples. Before the sampling, thoroughly eliminate
coal briquettes and gangues that fall to the bottom of the pit. Increments shall be
uniformly distributed on the sampling surface. Pay attention to large accumulations (for
example, accumulations in the corner or near the wall of the carrier) caused by isolation
during the handling process (for example, loading and unloading).
The opening of probe/drill or shovel used for manual sampling shall at least be 3 times
of the nominal top size of coal, and not less than 30 mm (see 9.1). The capacity of the
sampling apparatus shall be sufficiently large. The mass of the increments being taken
shall reach the requirements in 5.2.4.2. During the sampling, increments shall not fill
up the sampling apparatus, or, be overflowed from the sampling apparatus. In addition,
increments shall be taken at a time; do not throw the excessive part, or, make up the
deficient part.
While taking increments, the probe/drill or shovel shall be vertically (or, in a certain
inclination) inserted from the sampling surface. While taking increments, large-size
materials (for example, coal or gangue) shall not be intentionally pushed aside.
The number of sampling units, the number of increments, the minimum mass of
increments, and the minimum mass of gross sample are shown in 5.2.3 (or 5.3.2.4)
and 5.2.4.
6.2.2 Distribution of increments
6.2.2.1 Increment distribution method
6.2.2.1.1 Systematic sampling method
Divide the surface of the sampled compartment/barge into several small blocks with
an equal area; number them. Then, successively take one increment from the middle
part of each small block of each compartment/barge. The first increment shall be
randomly taken from the small blocks of the first compartment/barge; the remaining
increments shall be successively taken from the subsequent compartment/barge.
6.2.2.1.2 Random sampling method
blocks with an equal area (small blocks at the bottom of the coal stack shall
be at a distance of 0.5 m from the ground). Then, adopt the method of
systematic sampling or random sampling to determine the location of
sampling zone and the location of sampling points (small blocks) in each
zone. From each small block, take one full-depth, or, deep or top coal sample
from each small block. Under the circumstance when it is not new working
surface, firstly, eliminate 0.2 m of surface layer during the sampling;
b) When sampling is conducted on coal unloaded from bucket loader, unload
coal sample onto a clean surface. Then, in accordance with Method a), take
increments.
7 Intermittent Sampling Method
When sampling is often conducted on large lot of coal coming from the same coal
source and with stable quality (for example, incoming coal from port), the method of
intermittent sampling may be adopted. When intermittent sampling method is adopted,
obtain prior consent from relevant parties.
Intermittent sampling scheme shall be designed in accordance with 5.3.2.4.1 b).
8 Various Coal Sample Taking
Generally speaking, coal sample for coal analysis includes: general analysis sample
(sample used for the determination of general physical and chemical characteristics of
coal); total moisture sample (sample exclusive for the determination of total moisture);
common sample (sample used for multiple purposes, such as: the determination of full
moisture, and the determination of general physical and chemical characteristics);
physical sample (sample used for the analysis of special physical properties, for
example, physical strength index or particle size).
Samples used for the determination of total moisture may be independently taken, or,
be taken from common samples. Under the circumstance of extracting total moisture
samples from common samples, the number of primary increments being taken shall
be the greater number between the number of increments needed for ash content and
moisture determination. If after extracting moisture samples, the remaining samples
are insufficient for the required mass of the remaining tests, then, increase the number
of increments, till the mass of gross sample satisfies the requirement.
If necessary (for example, coal is extremely wet), moisture samples may be
independently taken. When moisture samples are independently taken, the following
points shall be considered:
a) Coal gradually loses moisture, due to drainage during the storage;
Probe and drill shall receive bias test in accordance with the stipulations in GB/T
19494.3. After they pass the bias test, they may be put into use.
9.2.1 Sampling bucket
Sampling bucket (see Figure a)) is made of materials that do not easily stick to coal
(for example, stainless steel). It is applicable...