ISO 14180:2023

Coal — Guidance on the sampling of coal seams

This document provides guidance on methods for taking samples from coal seams in the ground, whether from exploration areas or tenements, or from operating underground or open-cut mines. The following methods are described: a) sampling of small- or large-diameter holes; b) drill cuttings sampling; c) open-cut slot sampling; d) adit, drift or shaft sampling; e) pillar sampling; f) channel sampling; g) strip sampling. This document does not apply to sampling from moving streams in production or any other source of coal that is not in situ. Recommendations are made for selection and preparation of the sampling site, and methods are described for taking both small and bulk samples and for preparing the samples for transport. NOTE Annex A gives an example of a channel sample record form that can be used to record sampling and other relevant data, and ISO 13909 and ISO 18283 describe how to determine the mass of a representative sample at various nominal top sizes.

Charbon — Recommandations pour l'échantillonnage des veines de charbon

General Information

• Status: Published
• Publication Date: 06-Nov-2023
• ICS: 73.040 - Coals
• Technical Committee: ISO/TC 27/SC 4 - Sampling
• Drafting Committee: ISO/TC 27/SC 4 - Sampling
• Current Stage: 6060 - International Standard published
• Start Date: 07-Nov-2023
• Due Date: 01-Jun-2024
• Completion Date: 07-Nov-2023

Relations

• Revises: ISO 14180:2017 - Solid mineral fuels — Guidance on the sampling of coal seams
• Effective Date: 03-Dec-2022

ISO 14180:2023 - Coal - Guidance on the sampling of coal seams (Overview)

ISO 14180:2023 provides guidance for taking representative samples directly from coal seams in situ. Intended for exploration areas, tenements and operating underground or open-cut mines, the third edition (2023) describes safe, traceable methods to collect both small and bulk samples and to prepare them for transport and laboratory analysis. This standard is focused on in‑place coal seam sampling and explicitly excludes sampling from moving production streams or other non‑in situ sources.

Key topics and technical requirements

• Sampling methods covered - Detailed guidance for:

  • Core sampling (small- and large-diameter cores; common diameters noted as 50 mm–200 mm)
  • Drill cuttings (chip) sampling
  • Open‑cut slot sampling
  • Adit, drift or shaft sampling
  • Pillar sampling and block recovery
  • Channel sampling (vertical channels through the seam)
  • Strip sampling (smaller cross-section channel-like samples)

• Site selection and preparation - Guidance on choosing representative sampling locations, obtaining permissions from mine managers or tenement owners, and coordinating multidisciplinary teams (geologists, mining engineers, safety officers, lab staff).

• Sample handling and documentation - Procedures for core recovery, handling, identification, bagging and boxing, labelling, and transport. Annex A provides an example channel sample record form to standardize data capture.

• Quality and representativity - Emphasis on collecting representative samples to characterize lateral and vertical variation of seam lithotypes, plies and inorganic layers; recommendations for multiple samples where seams are heterogeneous.

• Safety and governance - Strong recommendation for a pre‑sampling risk analysis and compliance with site safety procedures.

• Related technical notes - References to sample mass determination methods (ISO 13909 and ISO 18283) and vocabulary (ISO 1213-2).

Practical applications and users

ISO 14180:2023 is essential for professionals involved in coal resource evaluation and quality assessment, including:

• Exploration geologists and field samplers
• Mining and geotechnical engineers
• Mine operators and environmental/safety officers
• Coal quality laboratories and sample preparation facilities
• Regulators and consultants preparing mine feasibility, reserve and compliance reports

Use cases include resource definition drilling programs, seam characterization for mine planning, pilot wash and combustion test sample collection, and baseline environmental or regulatory sampling.

Related standards

• ISO 13909 - Determination of representative sample mass at nominal top sizes
• ISO 18283 - Sampling methods for similar sample mass guidance
• ISO 1213-2 - Vocabulary for sampling, testing and analysis (terms used in ISO 14180)

ISO 14180:2023 helps ensure coal seam sampling is safe, repeatable and traceable, improving the reliability of downstream testing, resource estimation and operational decision‑making.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 14180
Third edition
2023-11
Coal — Guidance on the sampling of
coal seams
Charbon — Recommandations pour l'échantillonnage des veines de
charbon
Reference number
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative reference .1
3 Terms and definitions . 1
4 Selection of sampling site .3
4.1 Initial considerations . 3
4.2 Sampling procedures . 3
4.3 Core sampling . 4
4.3.1 Purpose of coal sampling . 4
4.3.2 Core drilling and sampling procedures . 4
4.3.3 Core recovery . 5
4.3.4 Core handling and identification . 6
4.3.5 Procedure for placing samples in bags . 6
4.3.6 Procedure for storing and despatching samples . 6
4.3.7 Boxing of core . 7
4.3.8 Transporting core. 8
4.4 Cuttings or “chip” sampling . 8
4.4.1 Purpose of cuttings sampling . 8
4.4.2 Method of cuttings sampling . 8
4.4.3 Cuttings samples identification and labelling . 9
4.4.4 Additional information on drilling and sampling of cores . 9
4.5 Open-cut slot sampling . 9
4.5.1 Purpose of open-cut slot sampling . 9
4.5.2 Method of open-cut slot sampling . 10
4.6 Adit, drift or shaft sampling .12
4.7 Pillar sampling . 13
4.7.1 Purpose of pillar sampling . 13
4.7.2 Marking of sampling site . 13
4.7.3 Method of pillar sampling . 13
4.8 Channel sampling . 15
4.8.1 Purpose of channel sampling . 15
4.8.2 Manual sampling in underground situations. 16
4.8.3 Continuous miner sampling . 17
4.9 Strip sampling . 18
4.9.1 Purpose of strip sampling . 18
4.9.2 Method of strip sampling . 18
4.10 Total moisture samples . 18
4.11 Labelling . 18
5 Recording of sampling location and geological data .19
5.1 Sampling location . 19
5.2 Geological and sampling data. 19
6 Transportation of samples.20
6.1 Pillar samples . 20
6.2 Channel and strip including sub-sectional (ply) samples . 20
Annex A (informative) Example of a standard form for recording channel sampling data .21
Bibliography .23
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 27, Coal and coke, Subcommittee SC 4,
Sampling.
This third edition cancels and replaces the second edition (ISO 14180:2017), of which it constitutes a
minor revision. The changes are as follows:
— 3.7 revised, with note to entry added;
— notes in 4.1 and 4.4.2 changed to body text;
— new subclause 4.4.4 added;
— editorial changes in accordance with the latest version of the ISO/IEC Directives Part 2.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
Coal is one of the most challenging materials to sample due to its characteristic heterogeneity. A coal
seam can consist of a single stratum of one lithotype of relatively uniform maceral constitution or,
more commonly, a number of layers of different coal lithotypes varying in thickness and lateral extent.
The seam can also contain discrete layers of inorganic sediments or carbonaceous shales of varying
thickness. Veins of concordant or discordant secondary mineral rock can also be present. The lithotype
layers can vary considerably in hardness, texture and structure according to the nature of the coal and
inorganic sediments. The inorganic layers can also thicken laterally, splitting the seam into two or more
separate units, which can require multiple samples.
It is strongly recommended that a collaborative team, including geologists, mining engineers, safety,
land and laboratory professionals, reviews each proposed sampling programme to help ensure optimal
effectiveness and efficiency are obtained.
The purpose of sampling coal for any resource evaluation is to predict the expected quality of the
produced coal from a given locale. Therefore, the fundamental goal of each sampling effort is the
collection of representative samples of the seam(s) at each sampling location. A properly executed
sampling programme needs to accurately define both the lateral variation in coal quality and the
average quality for a specified area.
After inspection of any seam, the sampler designs a sampling programme with sufficient representative
samples to define the range of expected coal quality. In variable seams it is necessary to take a number
of samples to improve the representativity of sampling.
In operating mines, the manager needs to be consulted and approval needs to be obtained before
sampling sites are selected and sampling proceeds. Where there is no operating mine, the area or
tenement owner and/or operator is consulted.
In all sampling situations, experienced and qualified personnel will be required for supervision and
to ensure that accurate records are made of location, thickness and lithotype descriptions and that all
safety precautions have been addressed.
Methods of sampling for physical, chemical, petrographic or utilization properties are described for the
following:
a) sampling from small and large diameter drill cores;
b) sampling from exposed seam faces;
c) sampling from trial open-cut excavations;
d) sampling from underground workings.
v
INTERNATIONAL STANDARD ISO 14180:2023(E)
Coal — Guidance on the sampling of coal seams
SAFETY PRECAUTIONS — It is strongly recommended that a risk analysis of the sampling
exercise be undertaken by an experienced safety officer before work begins.
1 Scope
This document provides guidance on methods for taking samples from coal seams in the ground,
whether from exploration areas or tenements, or from operating underground or open-cut mines. The
following methods are described:
a) sampling of small- or large-diameter holes;
b) drill cuttings sampling;
c) open-cut slot sampling;
d) adit, drift or shaft sampling;
e) pillar sampling;
f) channel sampling;
g) strip sampling.
This document does not apply to sampling from moving streams in production or any other source of
coal that is not in situ.
Recommendations are made for selection and preparation of the sampling site, and methods are
described for taking both small and bulk samples and for preparing the samples for transport.
NOTE Annex A gives an example of a channel sample record form that can be used to record sampling and
other relevant data, and ISO 13909 and ISO 18283 describe how to determine the mass of a representative sample
at various nominal top sizes.
2 Normative reference
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 1213-2, Solid mineral fuels — Vocabulary — Part 2: Terms relating to sampling, testing and analysis
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1213-2 and the following
apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
bulk sample
sample of large mass, taken in a particular operation for a specific reason, such as for pilot washing,
coal preparation or combustion tests
Note 1 to entry: It is not possible to define the minimum size of a bulk sample.
3.2
channel sample
sample of the coal and associated inorganic material taken by removing a vertical channel of even
cross-section from the seam
Note 1 to entry: Where the full section of the seam is not accessible or not required, this term can refer to a
sample taken either from a specifically defined portion of the seam or from the floor to roof as mined or exposed.
3.3
coal seam
stratum or sequence of strata composed of coal as a significant component and significantly different in
lithology to the strata above and below it
Note 1 to entry: It is laterally persistent over a significant area and it will be of sufficient thickness and persistence
to warrant mapping or description as an individual unit.
3.4
core sample
cylindrical sample of the whole or part of a coal seam obtained by drilling using a coring barrel
Note 1 to entry: The diameter of the core can vary from 50 mm to 2 000 mm depending on the reason for which
the sample is required. However, 50 mm to 200 mm is the most common core diameter range.
3.5
cuttings sample
sample of coal chips produced from the rotary drilling of a coal seam using a non-coring bit, such as a
blade bit or roller bit
3.6
pillar sample
section of a seam taken in the form of a block, or series of blocks, of coal with associated inorganic rock
which, when arranged in correct vertical sequence, represent a true section of the seam
Note 1 to entry: Where the full section of the seam is not accessible or not required, this term can refer to a
sample taken either from a specifically defined portion of the seam or from the floor to roof as mined or exposed.
3.7
ply
layer of coal seam normally differing in properties from adjacent layers
Note 1 to entry: Any distinctive layer can be regarded as a ply.
3.8
ply sample
sample taken from an individual ply or leaf or from a series of plies or leaves of a coal seam
3.9
strip sample
sample like a channel sample but smaller in cross-section
Note 1 to entry: A single strip sample can often be regarded as being too small to guarantee that all horizons of the
seam are adequately represented. However, several such samples can be taken to achieve better representativity
in a variable seam.
4 Selection of sampling site
4.1 Initial considerations
Sampling sites, where possible, are chosen at random when no other information regarding the
tenement or exploration site is available. The site for sampling apart from drill holes should be chosen,
as far as possible, to avoid cracks and breaks, random lenses of rock or mineral matter, or other
abnormalities or irregularities in the face to be sampled. However, on occasion, the purpose can be to
sample a particular mode of development of the seam section, in which case the sample should be taken
at the best available site exhibiting this feature. The location of the sampling point should be recorded
accurately (see Clause 5).
Core sampling is usually employed for sampling coal seams that are not exposed in outcrop or by
mining. It is especially useful in areas which are not readily accessible as drill rigs are small enough
to be located by helicopter. Sometimes, however, this method is used even though exposed faces are
available. This is because it is often faster, less labour-intensive, safer and more representative than
pillar or strip sampling, especially if a suitable drilling rig is readily available. For example, many open-
cut mines take cores of the seam to be uncovered in the next mining strip to obtain coal quality data for
mine planning purposes. Coring of the uncovered coal seam by a drilling rig sitting directly on top of
the coal is also common practice where detailed coal quality parameters need to be known for blending
purposes or for specific cargoes where the customer is particularly sensitive to certain coal properties
or inorganic impurities.
Cores can be obtained routinely in diameters ranging from 50 mm to 200 mm, depending on the amount
of material required for testing. It is generally advisable that, for routine sampling operations, 100 mm
cores be taken, as this size provides a good compromise between representativity and cost.
There are risks in comparing data from different core sizes of the same coal. The determined yield
values and analysis for washing coals can vary significantly. When this occurs, it is recommended that
the results be confirmed by very large cores as described previously.
4.2 Sampling procedures
No two projects are exactly be the same and may have different requirements regarding sampling, such
as when and what should be sampled, how the sampling should be done, and the details of how the
samples should be numbered or identified, wrapped, recorded, stored and treated.
There are several rules related to sampling that should be noted:
a) Prepare well. Even if there is little expectation of finding anything of commercial significance, the
sampler should always be prepared and in a position to take samples if the opportunity presents.
Always have a selection of sample bags, bottles or other containers on hand, in case they are needed.
b) Ask questions. Before embarking on a new project, the sampler should discuss the sampling
requirements with the exploration geologist and/or manager, so it is clear exactly what is required.
c) If in doubt, take samples. Samples that are excess or surplus to requirements can always be
disposed of later, but if samples are not taken when the opportunity is available, then the chance
to do so may be lost completely. Take more samples than you may think are needed and divide if
uncertain about coal ply boundaries. These can always be recombined in the laboratory following
geophysical reconciliation.
d) Do not put off until tomorrow what you can do today. For example, if it is late in the day but
the project requires that 1 m increment soil samples should be collected from the first 10 m of the
cuttings of an exploration chip borehole, do not leave the cuttings overnight with the intention of
collecting the samples the next morning. Do not take the risk that samples are lost, contaminated
or have their integrity compromised.
e) Care should also be taken to prevent contamination by out-of-seam materials or other sources,
such as drilling fluid. In all cases, but particularly for lower rank coals, it is imperative that the
sample be promptly packed in its container to minimize loss of moisture and be transported to the
laboratory as soon as practicable.
f) Before sampling an exposed face, the section to be sampled should, as far as practicable, be
uniformly dressed and squared up, and any loose, overhanging or protruding pieces of coal or rock
should be removed. Where a face is weathered, the immediate surface material should be removed
to a depth sufficient to eliminate weathering effects. In the case of underground face sampling,
contamination by stone dust is to be avoided, as this will influence the analysis.
g) The coal sample after logging and identification should be kept in a sealed bag or container.
h) If the laboratory cannot begin analysis immediately, arrangements should be made to keep the
sample in cold or cool storage to prevent oxidation of the coal. Any coal not being analysed should
be returned to cold or cool storage until it is required.
i) It is critical that sample information is recorded carefully, thoroughly and accurately. There is no
value in having a sample that cannot be identified or being unable to determine where a sample
came from or why it was sampled.
j) It is essential that all samples are analysed using rigid quality assurance and quality control
procedures. Examples such as duplicate samples, round robins between laboratories, standard
samples and laboratory certification to ISO/IEC 17025 are recommended in this document.
1)
4.3 Core sampling
4.3.1 Purpose of coal sampling
Core drilling is used to obtain representative samples for geotechnical, coal quality and gas content
and other testing to provide as much information from a borehole as possible. A well-drilled and
recovered core enables precise detail to be recorded on the thickness and brightness of coal bands and
the presence of any inter-bedded rock types, such as mudstone, siltstone or tuffaceous material, within
a coal seam. It also enables the weathered state of the coal to be identified. The combination of detailed
lithology logs with coal quality determinations and other test results supports the determination of
working sections and mining methods, coal handing procedures and products.
4.3.2 Core drilling and sampling procedures
The drilling and sampling of core is an expensive and time-consuming process. The information
available from logging and testing of core contributes significantly to critical decisions about the
quantity and quality of the resource and the potential mining conditions. Cores should be highly valued
and treated with appropriate care. Tasks when coring include the following:
a) Communicate with the driller about the length of the core run, the depth of the borehole and the
condition of the core.
b) Carefully transfer core from driller’s splits to PVC splits for logging.
c) Clean drilling mud and cuttings from core surface with as little water and disturbance as possible.
d) Photograph and log all cores as soon as possible after extraction to minimize disturbance to core.
e) Sample coal and partings separately before transferring any material to core boxes, unless the
material is significantly different to the expected interval or the core is required for another
purpose. In some countries, the term used when handling partings and high ash zones is “When in
doubt break it out”, meaning these zones can be separately sub-sampled, analysed and combined
mathematically later. Alternatively, the core may be boxed first, logged and sampled later with the
aid of the geophysical logs.
1) Much of 4.3 is taken from Reference [7], used with permission.
f) Any coal core retained should be stored in core sock (plastic tubing) or similar protective covering
to minimize moisture loss and further disturbance.
g) Minimize evaporation of moisture from coal samples by not leaving exposed for an extended
period, sealing samples into plastic bags and keeping sample bags out of direct sunlight.
4.3.3 Core recovery
There are a number of aspects for good core recovery that should be considered as follows:
a) The mechanical state of the rock, the driller and the drilling methods utilized, and the condition
and operation of the coring equipment. It is possible to obtain 100 % core recovery if these factors
are all favourable, but this is not usual in many situations.
b) The difference between what is cored and what is recovered needs to be reconciled. The first
step in the core logging process is to measure the length of core recovered.
c) The rig geologist should accurately determine the borehole depth before the core is pumped
out of the barrel and be responsible for the measurement of the drilled core run intervals. The rig
geologist should ask the driller for the length of the drilled run before the core run is extracted
from the core barrel. Once the core is pumped out of the barrel, the length drilled can then be
compared with the recovered length. Significant differences between the drilled length and the
recovered length may be due to measurement or calculation error of the amount drilled, or due to
core loss. Therefore, all measurements should be rechecked and frequent checks of the driller’s
depth should be made.
d) Once the core is on the logging table, the rig geologist should make the best attempt possible to
close up any gaps, crushed zones and irregularities (e.g. rotate the defect or break for a best fit),
or zones of apparent core expansion due to swelling clays or bulking due to discing or mechanical
disturbance. The rig geologist should also try to identify the top of the run. The core should not be
manipulated to fit the drilling interval.
e) The core should then be measured by both the driller and the rig geologist to obtain the measured
recovered length of core which should then be recorded on the drilling sheet with the driller
to depth and the geologist to depth. The difference between the length drilled and the recovered
length is the ‘core loss’ or ‘core gain’.
f) The apparent expansion of core can of course occur in combination with real core loss. It then
becomes difficult to know how much real core loss to assign to versus reducing core length for the
cumulative effects of core expansion. Also, although core lost from one core run may be recovered
later, each subsequent core run can also be subject to discrete core loss, and this should be allocated
accordingly.
g) The core run information is best recorded as a comment on the lithology sheet or separate
recovery sheet and should contain the run number, the start of run (SOR) depth, end of run (EOR)
depth, drilled core length and recovered core length. For example: “Run 1: 18,00 m to 22,50 m,
drilled 4,50 m, rec 4,32 m”. A record can also be calculated and recorded of the loss or gain for each
core run and the cumulative loss or gain (from values collected on the drilling sheet).
h) Where it is difficult to identify where the loss or gain has occurred, a continuous record of the
core depths or thicknesses can be made. Any indications of where core loss has occurred should be
recorded and depths adjusted later.
i) Some countries for their geotechnical use also calculate rock quality determinations (RQD) at the
same time as core recovery.
j) Some countries also carry out full scale geophysical logging of cores to provide an accurate seam
thickness to confirm core recovery and provide information regarding variation in ash in the seam.
The data obtained can also assist in the final sampling of the core.
4.3.4 Core handling and identification
Before samples are sent to the laboratory, the following procedures should be followed to ensure the
highest possible standard and reliability of sample collection and analysis:
a) Ensure all samples are taken as soon as possible to minimize moisture loss, otherwise store coal in
core sock or with plastic cover.
b) Minimize inclusion of excess free moisture minimize damage to core when separating samples.
c) Recover all possible core with minimal contamination.
d) Use a brush to ensure all possible fines are retained.
e) It is recommended that each sample should also be given a unique number within a sequential
numbering system, preferably commencing with the first sample of the uppermost seam in the hole.
Record project name, borehole name and sample number with a waterproof pen on the outside of
each bag – sample depths may also be included.
f) Record bag number (as bag x of xx) if multiple bags used for sample interval.
4.3.5 Procedure for placing samples in bags
This procedure should include:
a) double bag all samples (in tough plastic bags, i.e. > 60 um);
b) include a sample tag with a sample number in the outer bag;
c) seal the bag as airtight as possible with tape or cable ties;
d) determine and record the mass of all bagged samples by weighing;
e) keep samples in a shady or cool area if possible;
f) transfer all samples to cold or cool storage at the end of the day if possible;
g) consider using a barcode system for identifying all samples.
4.3.6 Procedure for storing and despatching samples
This procedure should include the following:
a) Pack sample bags into larger poly sacks (<25 kg) or 200 l drums (see Figure 1).
b) Seal securely (cable ties, staples, tape or secured lid).
c) Label outside with project name, borehole name, sample numbers and bag or drum number with a
waterproof pen or paint.
d) Keep a physical or digital record of all sample bags or drums with contents.
e) Transfer all samples to cold or cool storage awaiting despatch if possible.
f) Samples should be dispatched to the laboratory as soon as reasonably possible (at least once per
week is recommended).
g) Prior to despatch, the laboratory should be informed in writing of the number, identification and
dispatch mass of all samples and numbers of drums and/or bags that are to be delivered; a copy of
the sample record sheets shall be provided to the laboratory.
h) Record the date of despatch.
i) Record when the laboratory receives the samples. The laboratory staff shall ensure that they
reconcile the samples received against the sample record sheets and weigh each sample. This
ensures that all samples are received and if any bag is ripped the sample loss can be determined.
Figure 1 — Typical polypropylene sacks
4.3.7 Boxing of core
If core is to be stored for later inspection and sampling it should be placed in appropriate core boxes or
trays. All core boxes should be labelled on the front and one end from left to right so they can be read in
racks, with the following:
a) project name;
b) borehole number;
c) box number;
d) from and to depths (of the core in the box).
Suitable markers (e.g. wood or polystyrene block) should be placed inside the box as follows:
— at the top left with the borehole number, box number and core start depth;
— at the end of each run with the letters ‘EOR’, run number and depth;
— at the start of a new run where not continuous from previous run with the letters ‘SOR’, run number
and depth;
— where a sample has been taken with sample number and to and from depths (marker does not need
to match size of sample);
— where core loss has been recorded;
— at the bottom right with the end of core (EOC) or total depth (TD)of the borehole.
Position the core in a box in a way that minimises manual handling and core damage. It is recommended
that additional blocks are placed into gaps in the core trays to stop the core moving during transport.
Broken or fragmented core may be rolled into an appropriate length of PVC split tubing to ensure
integrity in transfer to the core box, and during transport and storage. If the core has been sampled the
residual core should be stored and clearly identified as being sampled. Figure 2 shows an example of
the correct layout of core in a core box. This shows that details such as project name (removed from this
figure), borehole name (removed from this figure), box number and depths can also be written on the
edges of the box. Note that breaks have occurred in the core during boxing or transportation as they
are not marked.
4.3.8 Transporting core
While on site, core boxes should be located so they are easily accessed and securely stored where they
will not be affected by weather or other disturbance. Position the box in a manner that prevents any
chance of the core box falling or the core being uncovered.
Core boxes should be secured and transported to a core shed and stored appropriately as soon as
possible. Strap core boxes into a vehicle to avoid movement and reduce the safety hazard during transit.
SOURCE Green, D., ed. CoalLog Geology and Geotechnical Training Manual. In: ACARP Project C22017. Australia,
[8]
2015, reproduced with permission.
Figure 2 — Typical core box
4.4 Cuttings or “chip” sampling
4.4.1 Purpose of cuttings sampling
Cuttings or chip sampling is used where core sampling is not possible or not justified in terms of
cost. Cuttings samples shall not be considered as representative compared to core samples, although
technological advances have made both core and cuttings samples more reliable. They require a great
deal of experience on the part of the driller and sampler to obtain reasonable samples but should never
be accepted as being truly representative of the coal seam. An instance in which cuttings samples
can be adequate would be in the early stages of an exploration area or tenement evaluation where an
indication of coal quality is required as a precursor to more detailed core sampling.
4.4.2 Method of cuttings sampling
Open hole drilling can be accomplished utilizing two non-coring techniques, rotary air blast drilling
(RAB) and reverse circulation drilling (RC). RAB drilling utilizes a single wall drill pipe, with a variety
of cutting bits at the downhole end and acts by injecting either air or drilling fluid down through the
drill pipe, and recovering drill cuttings as they are flushed out at the top of the hole, having travelled
up the hole in the annulus between the drill pipe and the wall of the hole. RC drilling utilizes a double
walled drill pipe, creating a “pipe within a pipe”, and acts by injecting either air or drilling fluid down
the outside pipe, and returning the drill cuttings to the surface through the inner pipe. RC drilling is
preferable to RAB drilling as the drill cuttings are not mixed and contaminated by the wall rock as they
travel up the hole as is the case with RAB, with RC samples therefore being more representative of the
strata the drill bit has penetrated.
The size of the cuttings can be very variable but generally ranges from a few millimetres to a few
centimetres. As the drill bit advances through the seam, the circulating medium (air, water or drilling
mud) transports the cuttings from the bit to the surface and they are collected in a purpose-made
container or cyclone or on a shovel held near the hole. Generally, the driller alerts the sampler when a
coal seam is intersected and stops drilling while still circulating the drilling fluid to clear the hole as
much as practical of out-of-seam contamination. When satisfied that the hole is clear, the driller then
drills a previously agreed distance, usually one metre, while the sample is collected, and then cleans
out the hole again. This procedure is continued through the seam until the seam floor is encountered.
A qualified and well-trained sampler or geologist should log all chip samples after washing by sieving
in a bucket of water to remove dust or drilling fluid, except for some intervals of weathered or clayey
material, as they may not remain in the sieve after being immersed in water. Washing will help to reveal
colour variations, grain size, the presence of minerals and possibly defects such as joint surfaces. This
also assists with determining percentages of multiple rock types. Log all chips in the same state to
provide consistency of colour descriptions, which will appear different if wet or dry. This is likely to be
a wet condition if they are logged immediately after washing them; however, if some dry out then they
should be made wet again. This should also be recorded.
Be observant and record any contaminant present within the chip samples. Rubber, for instance, is an
indication that the interior of the high-pressure bull hose has started to disintegrate. Drilling is to be
terminated immediately and the bull hose replaced before drilling can recommence.
NOTE Small cutting samples are less representative than full core samples.
The sampler is responsible for labelling each bag of material collected with a drill hole number and
depth at which the material was extracted. A variation on conventional cuttings retrieval is the
technique of reverse-circulation drilling. In this drilling method, the normal circulation of the drilling
medium (down the centre of the drilling rods and back up the annulus between the rods and wall of the
hole) is reversed and the drilling fluid is pumped down the annulus, entrains the cuttings and returns
up the centre of the rods, from which the cuttings are recovered and sampled.
Foundation drilling rigs can be used to collect very large cuttings samples, generally on a whole-seam
basis, where a large quantity of coal is required for utilization testing or any other purpose. Again, the
sample is placed directly in a truck, or on a prepared surface for loading later onto a truck with a front-
end loader or similar machine. Sizing of coal obtained in this way can be finer than the anticipated run-
of-mine coal sizing, but techniques such as reaming may be used to increase the average size if this is
important.
Another type of cuttings sampling is known as “keyhole sampling”. This method involves the fracturing
of the coal by blasting in the hole, or reaming followed by the recovery of the broken coal by circulating
the drilling medium using hydraulic mobilization and lifting. This method is best suited to sampling
deep coal seams that are targeted for underground mining, as an alternative to taking a number of
conventional large-diameter cores.
4.4.3 Cuttings samples identification and labelling
Identification and labelling for cuttings samples is similar to the method described for core samples in
4.3.4. If the samples are of small mass, then a number of cuttings samples held in small plastic bags and
suitably tagged can be placed in larger plastic bags or drums for ease of transport.
4.4.4 Additional information on drilling and sampling of cores
ASTM D5192 and Reference [6] provide further information regarding drilling equipment, geophysical
logging, description of coal and rocks and sampling of coal cores.
4.5 Open-cut slot sampling
4.5.1 Purpose of open-cut slot sampling
Slot sampling is a form of bulk sampling used to acquire a large quantity of coal that would be
representative of run-of-mine coal from undeveloped deposits amenable to open-cut mining, or
undeveloped areas or seams of an existing open-cut mine. Normally before this form of sampling is
undertaken core or cores would be taken to determine coal quality and the depth of coal oxidation
Often the purpose is to confirm coal quality, sizing, washability and utilization behaviour on a pilot or
in a trial in a coal preparation plant, or in a commercial trial to predict quality for investment purposes.
Results from these tests are more reliable than those obtained from core or channel samples and
contribute substantially to a development decision and planning.
It is imperative to realize that this type of sampling is subject to relevant legislated acts and regulations
and normally can be carried out only with all appropriate authorizations in place and under the
direction of suitably qualified mining personnel.
It is necessary that all safety issues and environmental concerns shall have been adequately considered
and resolved before sampling commences.
4.5.2 Method of open-cut slot sampling
Slot sampling requires a full mine design produced by qualified and experien
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