On-belt analysis of coal assists efficient production, reduces operating costs
On-belt analysis of coal has been found to assist efficient
production and reduce operating costs of mining operations.
For example, a coal mine in Australia had out of specification
shipments penalized by A$ 2,000,000 in one month due to high
moisture in the coal. Since installing analyzers two years ago and
some process control, there have been no further penalties as
shipments have been within acceptable moisture limits.
On-belt analyzers are widely used to monitor and control
coal quality, from coal face to shipment and final use. The key to
on-line analysis is that results are presented in real-time. In
some cases, results are provided within seconds of the coal
passing the analyzer. Scantech has more
than 850 installations in over 50 countries,
and thus the on-belt analyzers have general
industry acceptance.
Analyzers may be installed at the mine
to ensure the coal has the quality
anticipated on the basis of borehole
analyses. Washery operations can be
controlled with reference to on-line
analyzer results. A very common use is for
by-pass control, that is, if the ash of the raw
coal is already sufficiently low, then the coal
may bypass the washery and be fed directly
to the product belt.
Whilst Scantech employs mature
technologies for on-line ash analysis, there
have recently been significant developments
of these technologies. For example, an
explosion-proof natural gamma ray ash
analyzer, known as the COALSCAN 1500,
has been developed for a novel
underground installation. This technology is
regularly used close to the mine, to check
that the coal contains an acceptable
amount of inter-seam material.
Dual Energy Transmission (DUET) is the most commonly
used on-line ash measurement technique. The COALSCAN
2100 makes use of this technology. New developments in the
DUET ash measurement technology permit coal depths up to
400mm in some cases to be measured. These analyzers are
often found in coal washery bypass applications.
On conveyor belt elemental analyzers, known as the
COALSCAN 9500X, are now available to analyze the entire
stream, avoiding not only the operating and capital costs of
sampling, but also the sensitivity of older technologies to
variation in ash mineralogy.
This technology is no longer sensitive to variations in bed
depth. As well as measuring ash, this technology measures the
ash oxides and many other parameters useful for efficient plant
control. There have been four generations of this analyzer, with
the latest model requiring minimal maintenance, has very low
levels of external radiation and drift free analysis. The application
of these analyzers is widespread throughout the power industry,
where coals from multiple sources is blended and burnt. The ash,
sulphur and calorific value of the blended coal are monitored so
that i) there are no unnecessary environmental emissions and ii)
to optimize the power station performance. These technologies
can all be combined with the microwave moisture monitor, so
that a complete analysis of the coal is available in real time.
Scantech also produces stand-alone moisture monitors.
The TBM 210 was developed about 20 years ago. It is
installed at many sites to assist, for example, monitoring
moisture levels in of coal shipments, optimizing washery
performance and maintaining appropriate levels of dust
The TBM 230 has recently been introduced. This new
moisture monitor penetrates coal bed depths up to about
600mm. The results from on-line analysis are updated every
one, two or five minutes as compared with the laboratory
analyses of samples, which may be available hours or even days
after the coal has been processed. It must always be recognized
that, as well as the problem with the long delay in obtaining the
results, no matter how accurate the laboratory
analysis is, the results are always based on a few
grams of sample. There will always be errors
involved with sampling, dividing, crushing and then
preparing a few grams of sample to represent
many thousands of tonnes of coal.
On-line analysis allows more efficient use of the
resource, more effective process control and more
cost-effective methods of mining, processing and
burning of coal. On-line analysis should be viewed
not simply as an alternative to laboratory analysis.
The most beneficial on-line analyzer installations
are generally those where the user has realized
the advantages that real time analysis can bring to
their process. At ports, for example, where coal is
being loaded and unloaded, rapid and accurate
monitoring is required to make certain that
shipments have the correct coal quality.
Sampling based on modern sampling theory
Alex Stewart International employs more than 1,200 people in
over 45 countries and operates 17 laboratories, write Mr.
Graham Stewart and Mr. Kozo Matsumoto, Alex Stewart International
Corporation. Alex Stewart International provides its customers
with independent verification of the quantity and quality of bulk
commodity shipments, as well as geochemical analysis of mining
samples for exploration projects. Core business services are for
large international commodity trading
companies within the agriculture, metals
and mineral and oils and petroleum
As a service company, one of Alex Stewart International’s core business areas
is the supervision of weighing and sampling
of base-metal concentrates, where we consider it most important to rely on
modern sampling theory, not on rule-of thumb.
Total sampling variance is defined as:
  Primary variance of primary increments divided by the
number of primary increments;
  + sample preparation variance + analytical variance divided by
the number of replicate analyses.
In order to design any sampling scheme, first it is important
to decide the target value of the total sampling variance.
Then a decision must be made on: primary variance of
primary increments; sample preparation variance; and analysis
Here, in fact in modern theory, there are two schools of
  P. Gy’s theory using the concept of variogram; and
  traditional theory stemmed from some of JIS standards.
Traditional sampling theory is based on the assumptions that
each sampling point is statistically independent of all others and
that analysis results at each point are subject to a normal
standard distribution.
If this is not deemed to be the case, then it is better to follow Gy’s theory.
Following Gy’s theory, the required number of sample increments for each lot
tends to be much less than the one established by traditional theory. However, at
Alex Stewart International, it is believed that the truth lies is between both theories and
that considerable experience in actual shipments is vital.
Also, in actual shipments, correct determination of moisture
content of any bulk cargo is extremely important. This point
would seem self-evident, but in reality, contrary to expectation, it
is rarely carried out at the loading point. Alex Stewart has
considerable experience in this throughout the world.
Lastly, it should be emphasized that normally taking many
samples will not resolve any sampling issues. Too many samples
can create other serious difficulties in sample reduction. This
issue will also have to be resolved based on theory and
SGS services for the iron ore industry
SGS Minerals Services provide support to clients in the minerals
sector both as a strategic partner and as a technical advisor.
Through a global network of offices and laboratories, it delivers
a broad spectrum of independent services for:
  •   coal and coke;
  •   base and precious metals;
  •   steel and steelmaking raw materials;
  •   solid biomass;
  •   fertilizers;
  •   cement;
  •   industrial minerals; and
  •   diamonds.
SGS’s wide range of services includes geochemical analysis,
exploration services, mineralogy, metallurgy, environmental
sustainability, advanced systems, trade services and risk mitigation.
SGS provides a comprehensive range of services for the iron ore
industry, from the initial mineral exploration stage, to feasibility,
production, trade and industrial use, and mine site closure and
reclamation. SGS can provide the following services:
  •   umpire and settlement analysis;
  •   proficiency testing;
  •   collateral management;
  •   commercial inspection services;
  •   mechanical sampling systems (MSS); and
  •   E-Reports and e-Certificates.
SGS has the industry expertise to provide services on a
global platform for all levels of operation, including the
production, selling, buying and transporting of iron ore materials.
SGS’s laboratories employ uniform analytical and operational
methodologies, follow industry-leading quality assurance and
quality control practices, and use standardized templates for the
presentation of their results. SGS’s professional staff share best
practices and expertise, ensuring that all remain on the leading
edge of quality assurance/quality control practices, including
internal round robin programmes. Having specialized
laboratories strategically located around the world allows SGS
to provide the rapid turnaround necessary to facilitate
international trade in high-value materials.
SGS’ Laboratory Quality Services International (LQSi)
programme provides a quality-monitoring tool for SGS’s global
network of analytical laboratories, as well as for numerous
independent laboratories. LQSi’s proprietary statistical software
may be used to evaluate data from proficiency tests where
sample preparation, distribution and data compilation is
conducted by organizations other than LQSi. LQSi offers the
following laboratory quality services:
  proficiency (round robin) testing;
  proficiency test reporting services; and
  quality control samples.
SGS provides collateral management solutions to reduce
operational risk and improve profitability by ensuring that the
quantity and/or quality of goods being stored or shipped comply
with contractual requirements. In addition, SGS guarantees that
its services meet the specific requirements of credit institutions
and it has trusted stock-monitoring services to reduce shipping
and storage risks.
Collateral Management Agreements (CMA) allow SGS clients to
secure a loan using physical commodities as collateral. It is a
three-party agreement among the product owner/borrowing
party, SGS (the collateral manager) and the given credit
institution. Under a CMA, SGS acts as the custodian of
commodities until requirements of the financial institution are
met by continuous possession and responsibility for the iron ore
cargo while it is in storage. SGS guarantees the cargo’s weight
upon delivery, eliminating risk of shrinkage and/or financial loss.
SGS’ CMA provides financial advantages by:
  facilitating access to structured trade finance;
  making trade finance more economical; and
  allowing longer-term revolving financing.
To ensure that risks to the physical control and availability of the
iron ore cargo are minimized, SGS maintains and protects cargo
following strict internal SGS standards. It secures legal control
of the storage facilities by leasing the premises from the owner
and it provides non-negotiable bankable receipts stating that the
goods specified will be delivered as per the agreement. A
bankable SGS CMA will guarantee the weight and/or quantity of
iron ore cargo and ensure that the CMA meets local regulatory
SGS delivers a broad spectrum of independent evaluation
services to ports and terminals worldwide, aimed at reducing
operational risks and maximizing profits. All SGS port work is
done in accordance with internationally accepted standards such
as ASTM, EPA, ISO and JIS. Whether buying, selling or
transporting iron ore material, SGS experts can minimize commercial and
contractual risk by ensuring that the quality and quantity of material is the
same during loading, shipping and receiving. The company’s commercial
inspection services include hold inspections, loading master, on-line
analysis, mechanical sampling systems, on- and off-hires, bunker and
conditional surveys, weight and quantity verification, draught surveys
and sea-going barges and vessels.
Sampling can be carried out either manually or mechanically, the
latter being preferable with respect to operator safety and
accuracy. SGS engineers are at the forefront of mechanical
sampling design and installation. They have the operating
experience and knowledge needed to ensure that the system
design meets ASTM and ISO standards and that they are
consistently reliable, unbiased and accessible for maintenance.
The advantages of an SGS mechanical sampling system include:
  •   elimination of human error;
  •   representative, unbiased samples;
  •   assurance of consistent operation;
  •   time and cost savings;
  •   improved product stream sampling;
  •   maintenance of constant and repeated cutter velocity; and
  •   maintenance of sample integrity.
SGS’s e-Certificate platform dramatically improves the issuance
of documents. SGS certificates are generated through SGS’s
onSITE system and are sent by e-mail for instant verification by
any party involved. SGS will validate
the certificate on-line to ensure
increased security. The SGS onSITE
website contains:
  • e-Certificate — sent by e-mail and authenticated by using the onSITE authentication page; and
  • e-Report — personal online account to access repository of SGS e-Reports.
  • SGS e-Certificates fully comply with the Uniform Customs and
  • Practice for Documentary Credits for Electronic Presentation.
SGS strives to provide value added solutions to all operational
aspects of the iron ore industry, from early stage exploration
through to transportation and the end-user. SGS can help
minimize operational and financial risk through industrial
expertise and improve operational efficiencies with experienced
technical leadership. SGS is an innovator in inspection,
verification, testing and certification services. Founded in 1878,
SGS is recognized as the global benchmark in quality and
integrity. With over 59,000 employees, SGS operates a network
of over 1,000 offices and laboratories around the world.