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Volume 269 • Number 2 March-April 2021
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Volume 269 • Number 2 • March-April 2021
CONTENTS
4 News, Plant and Equipment
Features
12 Gas monitoring – is continual monitoring
the answer?
22 Evaluating a new method when
considering IPCC
30 Automated conveyor belt cleaner
tensioner reduces maintenance and
guesswork
32 Longwall innovations – challenging times
in Russia
36 Software playing a crucial role
44 It’s sheer madness to import the coal
essential for our steel industry when we
can produce it ourselves
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NEWS, PLANT AND EQUIPMENT
New cost-competitive, large-scale filter press delivers 93%
availability and 95% water recovery
The newly released a combination of fast and
AFP2525 Automatic Filter safe maintenance, lower
Press from FLSmidth costs and a minimised
delivers high availability and environmental footprint,
efficiency, with the lowest the AFP2525 immediately
cost possible – in fact, becomes the leading
the lowest cost per ton of solution in its area. It meets
production in the industry. growing customer demand
To keep mines operating for fast and efficient water
at its highest levels, all recovery and illustrates our
components of the AFP2525 determination to meet our
Automatic Filter Press are MissionZero ambition and
designed for quick and easy help mining move towards significant amount of water maximises water recovery
maintenance. zero water waste by 2030,” in their operations, reducing and is suitable for large-
We know that when comments Mikko Keto, the need for fresh water scale mines.
treating tailings at high Mining President at intake. This cuts both water- Additionally, fast filtration
volumes, even the smallest FLSmidth. sourcing and wet tailings rates and short mechanical
process disruptions add up. As well as the lowest management costs for times minimise the filter
That’s why we focussed cost per ton of production, the mine site, while also cycle time; this combination
heavily on ease and speed the AFP2525 also delivers reducing environmental of speed and reliability
of maintenance – for the lowest cake moistures footprint. result in the lowest cost per
instance, the AFP2525 and the highest production Why does the AFP2525 ton in the industry. With the
provides fast plate-pack rates – 300 tph from a provide a step change AFP2525 Automatic Filter
removal, while cloth change single filter; 7,200 tpd. The in this area? Firstly, Press, miners can expect an
and plate maintenance AFP2525 is also highly the AFP2525 has the average of 93% availability
happen outside of the durable and long-lasting due highest availability in the and up to 95% recovery of
filter, ensuring maximum to a maintenance-friendly, industry – the filter is process water.
efficiency and safety while robust design so it is built to easy to maintain, which The AFP2525 Automatic
the filter is operating. last for the life of the mine means costly downtime Filter Press is a key solution
“We are delighted to and beyond. is minimised. Secondly, in FLSmidth’s MissionZero
launch this large-scale, Ultra-efficient water the filter is exceptionally ambition to enable mines to
cost-competitive filter press reclamation allows miners efficient and operates eliminate water waste and
to the mining industry. With to recycle and reuse a at high capacity – i.e., it emissions by 2030.
Profits fall along with prices
The falling coal prices in the achieved in the previous production during the debt against the backdrop
first half of the 2021 financial corresponding period. six months under review of the improving price
year have seen ASX-listed “The impacts of subdued increased by 28%, to environment,” said Flynn.
Whitehaven Coal swing to a pricing on seaborne coal 7.7-million tonnes, while “With future savings
loss in the six months under markets were a key feature saleable coal production targets identified and coal
review. of the first-half results was up 10% on the previous markets rebalancing in
Whitehaven reported a as Covid-19 impacts on corresponding period, to response to demand signals,
net loss after tax of A$94.5- economic and industrial 7.1-million tonnes. we are optimistic about
million for the six months to activity continued to be felt,” Total coal sales for achieving stronger outcomes
December, compared with a said Whitehaven MD and the period under review through the second half.”
net profit after tax of A$27.4- CEO Paul Flynn. increased by 3%, to Whitehaven’s RoM
million for the previous “The business responded 8.7-million tonnes, while production targets have
corresponding period. strongly to these challenging revenues declined by 21%, remained unchanged at
Earnings before interest, market conditions, including to A$699.3-million. Unit costs between 21-million and
taxes, depreciation and through improvement per tonne for the period were 22.5-million tonnes for the
amortization declined by measures that delivered also down by 8%, to A$70/t. full 2021 financial year,
79% over the same period, meaningful cost reductions “We have closed out the while its managed coal sales
to A$37.2-million, reflecting and greater operational first half of 2021 with strong targets have also remained
the lower average achieved efficiency, offsetting price levels of liquidity, strong unchanged at between
coal price of A$80/t, headwinds to some extent.” banking support and we 19-million and 20-million
compared with the A$108/t Run-of-mine (RoM) are focused on retaining tonnes.
4 Coal International • March-April 2021
NEWS, PLANT AND EQUIPMENT
environment with China
will continue to impact
near-term export volume,”
Harding said.
“We expect continued
coal growth export of 1%
per year over the next
decade, supported by steel-
intensive growth in India
and a relatively young fleet
of coal-generation power
plants in Asia.”
India was Australia’s
largest metallurgical coal
export market during the
second half of last year,
with an export volume of 27
Aurizon anticipates export growth million tonnes, followed by
Japan at 16 million tonnes
Aurizon Holdings is Aurizon also experienced December. and China at 12 million
confident of the long-term interruptions to its export This caused Aurizon’s tonnes.
demand for Australian coal contracts with Australian coal revenue to drop by Japan topped Australia’s
from international markets coal miners due to COVID- 8%, or $73.2 million, to thermal coal export market
despite a 10% drop in 19-related disruptions to $644.5 million. with an export volume of 37
exports during the second steelmaking, particularly in Aurizon managing million tonnes during the
half of last year. China. director and chief executive same period, with South
Australia exported The company was Andrew Harding reiterated Korea coming in second
183 million tonnes of unable to retain its 3.2 that the company remained at 16 million tonnes and
coal during the period, million tonne a year export confident for long-term Taiwan at 10 million tonnes.
comprising 86 million contract with Stanwell demand for Australia’s Aurizon’s iron ore
tonnes of metallurgical coal Corporation, which ended high-quality coal. transport increased by 2.4
and 97 million tonnes of in December 2020, and is “Steel production has million tonnes, thanks to
thermal coal, down 6 and also saying goodbye to a now resumed to pre- commencing new contracts
12%, respectively, on the 5.2 million tonne per annum COVID levels, though with Rio Tinto and Mineral
prior year. contact for New Acland this the challenging trade Resources during 2020.
Domination of India’s energy generation until 2040
Coal is forecast to hold its India will be the country The World Coal that policies are in place to
top position as India’s largest with the highest increase Association (WCA) support the deployment of
single source of electricity in energy demand in the expressed its support for all clean technologies,” the
in 2040, despite the rising world by 2040, driven by the IEA’s call to support WCA stated.
use of renewable energy, an expanding economy, India in building a reliable “Our success as a global
according to International population, urbanisation and and affordable energy mix community in meeting our
Energy Agency (IEA). industrialisation. to meet the needs of its environmental goals will rely
In a report titled India “As India recovers from growing population. on a realistic and leveled
Energy Outlook 2021, IEA a COVID-induced slump “A pragmatic and approach.”
noted that India’s energy in 2020, it is re-entering a collaborative focus from Coal currently powers
use had doubled since 2000, very dynamic period in its international governments, 70% of India’s electricity
with coal, along with oil and energy development. Over industry, and investors generation, with solar
solid biomass, meeting 80% the coming years, millions is now needed to ensure accounting for less than 4%.
of this demand. of Indian households are
Despite the Indian set to buy new appliances,
Government’s plan to air conditioning units and
increase renewable energy vehicles,” IEA stated.
sources, especially solar, from “India is set to become
52 gigawatts in 2017 to 175 the world’s most populous
gigawatts by 2021-22 and country, adding the
275 gigawatts by 2026-27, it equivalent of a city the size
will still fall short of meeting of Los Angeles to its urban
India’s energy needs. population each year.
Coal International • March-April 2021 5
NEWS, PLANT AND EQUIPMENT
Czech mining regions confronted with ‘hidden’ Mining
energy poverty innovation lab
About 14 % of households
launched in
in the Ústecký region face Shanxi
problems paying their heating
bills, according to research. An intelligent mining
While Czech coal mining innovation lab was
regions supply heat and established in north
electricity to the whole China’s coal-rich Shanxi
country, local people are Province to facilitate the
often unable to afford heating digital transformation of the
their own homes, researchers country’s coal industry.
say. More broadly, Czechia The lab in Taiyuan, the
is struggling to meet its EU provincial capital, was
reporting obligations on Czechs eyes coal phase-out by 2038 jointly built by the Shanxi
energy poverty, an issue provincial government,
common to other countries in to preventing energy poverty. skilled workers and those Huawei Technologies
Central and Eastern Europe. Officially at least, that’s aged above 60. Co., Ltd., and two local
About 14% of households what the statistics show. However, the Czech enterprises.
in the Ústecký region – In 2018, 2.7% of the government does not Huawei CEO Ren
one of Czechia’s three Czechs were reportedly acknowledge the issue, Zhengfei said that Huawei
coal mining regions – face unable to keep their home according to Climate hopes to combine ICT with
problems paying their heating adequately warm while the Action Network Europe, an coal mining technologies
bills, according to research European average is 7.3%, environmental NGO. to support the digital and
by the Prague University of according to the EU Energy “In the Czech National intelligent transformation
Economics and Businesses Poverty Observatory. And Energy and Climate Plan, in the coal industry, realize
(VŠE). only 2.1% of the Czech energy poverty is discussed a production model that
The second most affected population cannot pay their in a rather theoretical way,” features “fewer workers,
region is Moravskoslezský energy bills on time due to CAN Europe said in a briefing greater safety, and higher
kraj, another Czech coal- financial difficulties, while the published in December. efficiency,” and enable coal
mining region.“Energy EU average is 6.6%. The country has currently mine workers to “wear suits
poverty is caused mainly However, these numbers no clear definition of energy and ties” at work.
by ineffective buildings and do not reflect regional poverty, which complicates The lab will be staffed
appliances, low incomes of disparities across the country, any attempt to monitor the with 220 ICT and coal
households, high costs of and may be underestimated, phenomenon. mining experts. Huawei
energy and special needs of critics say. The Czech coal plans to use the innovation
its consumers,” said Radek Energy poverty affects commission recommended lab as a place to continue
Tahal from VŠE. less developed regions to phase out coal by 2038. innovating with partners
At European level though, – especially coal mining Environmental groups, and making breakthroughs
the Czech Republic is areas – as well as the most who fought for 2033, were in technologies that can
considered to be among the vulnerable in Czech society: outvoted and walked out of be used in mining pits,
best in class when it comes unemployed people, low- the commission in protest. including self-cleaning
cameras, low-frequency
wireless transmission, and
risk prediction technologies.
The lab ultimately aims to
help Shanxi’s mines reduce
their numbers of workers
by 60% in fully mechanized
and intelligent mining
scenarios, and reduce
their numbers of workers
entering mining pits each
shift by 10 to 20%, it said.
“It’s like Microsoft
providing services for
aircraft engines,” said Ren.
“Huawei provides services
for mines, airports and
docks.”
6 Coal International • March-April 2021
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Progress
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NEWS, PLANT AND EQUIPMENT
Is coal really pulling out of South Africa?
South Africa’s formerly will never enter the
thriving coal sector has atmosphere; and 720,000
had a noticeable decline cubic metres of precious
in net investments over water per annum, for 30
recent years with statistics years, have been saved
from the Minerals Council – a crucial win in a highly
of South Africa reporting a water-scarce region of
R2-billion drop from 2010 a water-scarce country
to 2018. forecast to be particularly
As the future of the hard hit as the climate
South African coal industry crisis intensifies,” said
remains bleak and Nicole Loser, attorney
divestment from coal mining and programme head
continues around the world, for pollution and climate
some of South Africa’s giant change at the Centre for Mpumalanga’s coal fields: ‘The result of major producers
coal miners have sold or Environmental Rights selling their coal assets is that the enormous environmental
are in the process of selling (CER). damage of the mines is left to smaller, less-resourced
their operations. “Significant air pollution companies after much of the profitable reserve has been pulled
Challenges facing the that would have harmed the out.’ Photo © Daylin Paul/courtesy Life After Coal.
coal industry include an lives and health of residents
altered customer base of Lephalale and surrounds managing the balance In response to questions
for the country’s coal – already affected by between the current on what the future holds for
exports as developed Eskom’s Medupi and environment and the Eskom’s coal-fired power
countries are moving Matimba power plants – has communities we operate stations, the company’s
towards renewable energy been avoided.” in,” said Mgojo, as quoted media desk replied that
resources. There is a Speaking at the 2021 in Mining Weekly. “coal requirements are
hostile funding environment virtual Investing in African underpinned by the
for coal projects as financial Mining Indaba earlier Energy mix anticipated demand and
institutions nationally and in February, the chief Even with the declining Integrated Resource Plan
internationally are no longer executive of one of the coal sector, the government (IRP) assumptions into the
investing in coal projects country’s top five coal remains intent on keeping future”.
due to the pressure from producers announced that coal as a major part of the The IRP is a long-term
environmental lobbying – a his company would no country’s energy mix, and electricity capacity plan
challenge too for newer coal longer be investing in its well into the future. which provides the country
miners with less financial thermal coal assets. According to Eskom, with a “living plan” of its
muscle compared to major Exxaro Resources’ move one of the core pillars of its envisaged energy mix up to
coal producers. from thermal coal forms coal strategy is to procure 2030.
Litigation against some part of its transition to coal for the life of Eskom’s In response to questions
major coal developments is becoming carbon neutral by power stations, or the life of about the transition towards
also setting a precedent for 2050, said Mxolisi Mgojo. the coal-mining reserves. a clean and sustainable
the future of investments in The company will
coal projects. In November continue to supply
2020 the High Court in thermal coal to
Pretoria set aside the Eskom’s Medupi
environmental approval and Matimba power
for the proposed 1200MW stations in line with
Thabametsi coal-fired existing supply
power plant outside contracts.
Lephalale in Limpopo “We understand
because the minister of that we are a fossil
environmental affairs had fuel company and
failed to take into account we are migrating
the climate change impacts to a whole new
of the proposed coal-fired sustainable
power station. development
“The shelving of goal where we
Thabametsi means that intend to drive the
136,1-million tonnes of renewable part of Duvha power station near Emalahleni: Eskom’s strategy is to procure
carbon dioxide equivalent the future, [while coal for the life of its power stations, or the life of coal-mining reserves.
greenhouse gas emissions simultaneously] Photo © Mujahid Safodien/courtesy Life After Coal.
8 Coal International • March-April 2021
NEWS, PLANT AND EQUIPMENT
2020. Reasons for the
rejection included that “the
activity will conflict with the
general objectives of the
Integrated Environmental
Management laid down in
Chapter 5 of the National
Environmental Management
Act and that any potential
detrimental environmental
impacts resulting from
the activities cannot be
mitigated to acceptable
levels”.
Speaking to MineAlert
about this application
in September 2020,
the attorney for the
communities objecting to
the application, Richard
Spoor, said there was a
growing trend of DMRE
New order: Among the 82 new coal projects in exploration, feasibility study and/or construction awarding prospecting rights
phase in Mpumalanga are several in and around the Chrissiesmeer Protected Area. Map and mining permits to small
courtesy AmaranthCX. entrepreneurs, especially
around the Mpumalanga
energy supply, Eskom One of Mgojo’s concerns on basic environmental region.
responded: “Eskom is about the disposal of coal impact assessments and Attorney and programme
embarking on a just energy assets by the major coal consultation processes head of mining at CER,
transition plan which seeks producers is that they with interested and affected Catherine Horsfield,
to map out a pathway to could land in the hands of parties. cautions that “when one
decarbonising the grid, companies that may not An example of this has regard to the fact that
shifting to cleaner energy comply with environmental, was the application coal assets are rapidly
solutions and ensuring social and governance by Manzolwandle becoming stranded assets,
concomitant increase in (ESG) requirements. Investments to mine coal one cannot avoid the
sustainable jobs. We are “A big concern [when] near the southern border inference that selling these
in the process of detailing disposing of one’s coal of the Kruger National assets is more akin to
this plan with the respect assets [is that] they may Park. Despite backlash dumping them, and buyers
to technology options, land in the hands of parties from the surrounding should beware”.
financing options and socio- who may not want to act communities, the small According to Horsfield,
economic development responsibly in terms of how company was confident the result of major coal
options. they treat the environment about its application being producers selling their
“From a coal perspective, and other aspects of ESG,” successful. coal assets is that the
improving the quality of Mgojo was quoted saying Manzolwandle initially enormous environmental
coal procured to acceptable on the Argus website. failed to follow proper damage of the coal mines
levels could potentially Paul Miller, director of consultation processes and is left to these smaller,
assist with current mining supply consultancy failed to notify all interested less-resourced companies
emissions regulations as we AmaranthCX, echoes and affected parties about after much of the profitable
transition towards a cleaner Mgojo’s concerns: “This some public meetings reserve has been pulled
and more sustainable is yet another blow to held to discuss their out.
energy supply,” said the transparency within the proposed mining project. Its In response to questions
entity’s media desk. sector as listed companies environmental consultants on how they would ensure
had stricter environmental, landed in hot water when compliance, the DMRE
Smaller coal operations social and governance it was discovered their responded: “When a
Divestment by the larger reporting and disclosure background information company sells its mining
companies has resulted requirements,” he said. document had been copied rights or changes a
in coal mines being taken According to Miller, the and pasted from other control in a listed entity,
over by smaller operators lack of proper follow-ups similar documents. the cessionary (buyer)
and some big companies on the smaller operators The application was must demonstrate the
that are not listed on opens up the possibility rejected by the Department technical and financial
the Johannesburg Stock for them to get away with of Mineral Resources and ability that they will be
Exchange. not doing due diligence Energy (DMRE) in October able to carry through the
Coal International • March-April 2021 9
NEWS, PLANT AND EQUIPMENT
to discouraging the
development of new
coal-fired power stations
and mines; reduce
emissions from existing
coal infrastructure and
encourage a coal phase-
out; and enable a just
transition to sustainable
energy systems has had
some notable successes
towards these objectives.
Some milestones in
the past year include the
criminal prosecution of
Eskom for violating permit
limits and filing misleading
information to authorities
at its Kendal coal power
station; and the proposed
Thabametsi coal plant
being set aside (following
successful litigation by
Pollution hotspot: Recent research found that in South Africa 9.3% of deaths can be the campaign), with the
attributed to air pollution from fossil fuels – about 45,134 people each year. proposed Khanyisa coal
plant in Mpumalanga likely
mining operations and Africa, an additional prospecting applications to follow.
comply with the compliance four mines undergoing and new coal projects “These victories have
requirements of the existing expansions, and one owned by small operators resulted in tangible
mining right.” being recommissioned publicly available. None of benefits for health, climate,
Horsfield remarked that after a period of care and the new coal projects which the economy and the
it is crucial “the financial maintenance. are in their exploration environment,” said Loser.
provision needed for “If all of these projects and studies phase A new study published
environmental rehabilitation were to go into operation that he mapped out for this week by scientists
is accurately assessed as planned, they would AmaranthCX appear on the at Harvard University,
and properly collected by add 128-million tonnes to DMRE ‘Operating Mines University College London
the DMRE. That financial South Africa’s output, a Directory and because of and other universities found
provision needs to be set 51% increase in current the login issues with the that air pollution from fossil
aside and ring-fenced production,” said GEM SAMRAD system these fuel use is responsible
before profits are paid out energy analyst Ryan could not be verified on it. for one in five deaths
to shareholders.” Driskell Tate. “It has become apparent worldwide. This research
The DMRE hosts an that there are deep found that in South Africa,
Coal data online directory of operating systematic issues with the 9.3% of deaths can be
Miller’s company recently mines that shares brief SAMRAD system,” said attributed to air pollution
mapped out 271 coal details such as the mine Miller. “There is no one- from fossil fuels – about
mines and prospecting code, owner, name and stop-shop for information, 45,134 people each year.
operations across South commodity type. The and that is a general issue “Coal is not on the way
Africa. His data shows there site also hosts the South of [lack of] transparency.” out, but we have certainly
are currently 112 new coal African Mineral Resources In response to questions seen positive indications
projects in exploration, Administration System from MineAlert about the of a declining coal sector
feasibility study and/or (SAMRAD), the official inaccessibility of SAMRAD, in South Africa,” Loser
construction phase. Of administration system of the DMRE’s media desk said. “Examples include
these new projects, 82 are mining applications and responded that the system the withdrawing by
in Mpumalanga province, permits. However, recent is available during working investors and financiers
which is already heavily attempts to access the hours and is updated from proposed coal power
polluted due to mining and portal proved fruitless, and quarterly. projects, the adoption of
coal power stations. calls to the number provided policies by commercial
According to the for the SAMRAD help desk Life after coal lenders to restrict funding
Global Energy Monitor rang unanswered. Life After Coal/Impilo of coal projects, and
(GEM), there are 23 new Miller said the DMRE Ngaphandle Kwamalahle, diminishing allocations in
mines currently under portals do not make a joint campaign of civil South Africa’s electricity mix
development in South information on new organisations committed to coal power.”
10 Coal International • March-April 2021GAS MONITORING
Gas monitoring – is
continual monitoring the
answer?
ithout delving into the past of early some of elements of the mine designed with consideration of
W
methods of gas detection in mines when emergency situations, having some emergency equipment
the warm-blooded birds like canaries onsite and a comprehensive training programme in place.
were commonly used , the industry is
now implementing new technology in It is a well-known fact that gas monitoring on its own will
gas detection methods that may even never prevent a mine fire or put it out if it starts. What it
see the return of the canary albeit a does offer is a means of identifying a problem early and
modern version that is highly unlikely to fall off its perch, this subsequently an opportunity to take appropriate controlling
new technology to remotely detect toxic gases in underground actions. The earlier a problem is identified the better the
mines is being trialled in Western Australia. chance of successfully dealing with the problem. The
best chance of getting an early warning is by continual
Sophisticated monitoring equipment and wireless sensor monitoring. The successful application of mine monitoring
networks are now at the forefront of detecting gas and systems requires the setting of appropriate alarms
hopefully will save many unnecessary deaths. Many that trigger effective remedial actions. The mine must
companies have now started producing automatic detectors also implement effective maintenance and calibration
which tells the exact concentration of the gases present procedures to ensure reliable ongoing operation of the
in the mine environment, these devices are able to detect mine gas monitoring systems if they rely on them for this
even a very small amount of gas percentage. early warning or in fact use results to assess any control
measures they might implement during an event.
The key issue of research on wireless sensor networks is
to balance the energy costs across the whole network and Coal mines around the globe all implement different gas
to enhance the robustness in order to extend the survival monitoring measures, however Queensland in Australia’s
time of the whole sensor network. Zigbee technology is underground operations, as a whole, has arguably the
given preference over others such as Wi-Fi for establishing best gas monitoring systems in the world. Each mine
a wireless network because it provides a large range of utilises real time, tube bundle and onsite ultra-fast gas
coverage and less fluctuation in the signals chromatograph systems. Queensland’s mining legislation
has specific requirements for mine gas monitoring but
When a high potential incident occurs in a coal mine, the there is no requirement for all three techniques. Industry
situation can quickly spiral downward to cause multiple loss has however identified the need for all three and adopted
of life, loss of equipment, loss of coal assets and major this as a standard, resulting in over sixty thousand gas
damage to a company’s reputation. Without wanting to results collected each day. Automated monitoring systems
state the obvious, a fire in a coal mine is very difficult to are programmed to alarm for gas concentrations, gas ratios
control as the fuel (coal) is abundant and changing the and explosibility. These alarms are then used to initiate
ventilation may endanger the underground mine workers. predetermined actions to take control of the situation and
prevent the compromise of safety to workers and the loss
Such incidents in underground coal mine are an ever- of resources. Dedicated software packages have been
present risk in the industry. However, the mine can be better developed to assist in the interpretation of the large volume
prepared to take control of the situation earlier by having of results generated. The real time systems are used for
12 Coal International • March-April 2021GAS MONITORING
real time warning, essential for incidents such as belt fires. sequentially using infrared and paramagnetic techniques.
Tube bundle systems suit long term trending used for Gases measured are carbon monoxide, carbon dioxide,
identification of the onset of spontaneous combustion or for methane and oxygen. Because the analysers are on the
the determination of explosibility during the routine sealing surface, tube can be located in the goaf as once positioned
of worked areas. Gas chromatograph analysis is used there is no requirement to access the end sampling point
to provide a complete analysis and provides results for (although sample filters and water traps located out bye
hydrogen and ethylene, key gases used in the assessment will require maintenance). Tube bundle systems are suited
of spontaneous combustion. It is also crucial during to long term trending (provided the system is suitably
significant spontaneous combustion events and coal fires maintained). Very good analytical equipment is available
to use gas chromatography to determine the explosibility and can be housed in dedicated air-conditioned rooms on
status of the underground atmosphere otherwise the the surface with the samples dried and passed through
severity of the situation is likely to be underestimated. particulate filters prior to entering the analyser.
This paper outlines the need for all three techniques for
assessing the underground status and outlines advantages Generally, systems are set up to measure oxygen, carbon
and disadvantages of each. monoxide, carbon dioxide and methane. Given their
ability to measure carbon monoxide down to 1 ppm, the
REAL TIME MONITORING long-term stability of these analysers and the frequent
Real time sensor systems (telemetric systems) are ideal sampling, this technique is best for long term trending of
for telling us what is happening now. The sensors must carbon monoxide, and carbon monoxide make, to identify a
be located where the gas needs to be measured, and the spontaneous combustion event. With respect to measuring
measurement signal is sent to the surface. This means range, it is normally only carbon monoxide that presents
having multiple sensors underground, and that these sensors problems, with most systems capable of measuring to only
are exposed to the harsh underground environment which is 1000 ppm. Because methane and oxygen concentrations
not ideal for precise analytical measurements. This is not can be measured over all expected concentrations ranges,
really a major problem as these systems are used to detect this technique is the best for automated monitoring of
step changes, such as the onset of a fire, a sudden increase explosibility of an area so long as a fire or heating doesn’t
in a seam gas in the general body or reduction in oxygen. exist. This technique is best for monitoring explosibility
They offer real time warning and are the best system for during a routine sealing operation and for the early onset of
identifying a sudden event such as a belt fire. The situation any spontaneous combustion event.
is reported when it happens. Generally, sensors included are
methane, carbon monoxide, carbon dioxide, and oxygen. To get this improved stability and analytical capability,
These types of sensors employed underground tend to the immediate availability of the results is sacrificed. The
have limited measuring ranges: carbon monoxide is often samples need to be drawn to the surface prior to being
only capable of being measured up to 50 ppm, methane to analysed, meaning the data being generated can be from
5 % and carbon dioxide to several percent. This range is samples collected from over an hour before. There is only
fine while no problems exist, and indeed to alert the onset one bank of analysers, so only one sample is analysed at a
of a problem. But if a fire or other major incident involving time. Depending on the number of tubes in the system and
generated gases occurs, these sensors may quickly reach the programmed sampling sequence, each point may only
full scale and be unable to return a true indication of the be sampled once every thirty to sixty minutes. Add this to the
concentrations. Due to the environment these sensors are time taken to draw the sample from underground, which may
in and their characteristics, they are not as useful for long be as long as an hour and it is obvious this technique is not
term trending as the other techniques. Most of these sensors suitable for the instantaneous detection of an incident such
require the presence of oxygen to work and are therefore as a fire. To minimise delay time in sample analysis, even
unsuitable for monitoring areas of low oxygen concentration when a sampling location isn’t been analysed it is being
such as sealed or non-ventilated goafs. As each individual drawn to the surface by purging pumps that just vent the
sensor needs to be calibrated regularly (at least monthly) sampled gas to atmosphere. As multiple points are drawn
they are not suited to being located for long term monitoring through these purging pumps it is important to balance the
in inaccessible areas. Some of these sensors also suffer flows of each of the tubes to ensure that each of the tubes is
from cross sensitivities, as the reactions they rely on to being purged and not just the tube with the least resistance.
give a response can be common to other gases found
underground, such as carbon monoxide sensors being cross Because the analysers in these systems rely on infrared
sensitive to hydrogen sulphide and hydrogen. absorbance and paramagnetic attraction the gas matrix
is not important, making this technique suitable for the
In the case of an explosion, it is likely that the real time analysis of gases from oxygen depleted areas such as the
monitoring system will be rendered inoperable, requiring goaf. What must be remembered is that the measurement
other techniques for the determination of the status of the of oxygen using paramagnetic analysers is flow rate
underground environment dependent and the flow from each tube must be balanced
to be the same, including any calibration gases used.
TUBE BUNDLE Otherwise, it is possible that two locations could in fact
Tube bundle systems draw gas samples from designated have the same oxygen concentration, but because of
sampling locations underground to the surface through more resistance in one of the tubes, the flow through the
plastic tubes using vacuum pumps and analysed analyser is at a lower flow rate and as such results in a
Coal International • March-April 2021 13GAS MONITORING
lower reading than a location with the same concentration The GC is not the best analytical technique for low
but flowing through the instrument at a faster rate. concentrations of carbon monoxide; therefore, this technique
is not the preferred method for determination of carbon
Too often the maintenance of the tubes is overlooked, monoxide makes nor low general body concentrations.
and the monthly leak testing identified in Australian However, during a significant spontaneous combustion
Standard “AS2290.3 Electrical equipment for coal mines event, fire or following an explosion, it is the only technique
– Maintenance and overhaul Part 3: Maintenance of gas that will allow us to make an accurate determination of the
detecting and monitoring equipment.” is not performed or explosibility of the underground environment. Like the tube
not done as stated by the standard. If maintenance follows bundle system, the gas matrix of the sample does not affect
the method outlined in the standard, it is not only possible GC analysis. So long as appropriate calibration gases are
to confirm that no leaks exist but also determine an available, this technique is capable of measuring gases at
approximate time taken for a sample to reach the surface. any concentration above their detection limit. This eliminates
The knowledge of the draw times of each tube is critical to the problems seen with the other techniques, particularly for
adequately assess what is happening and how long ago it carbon monoxide concentrations greater than 1000 ppm.
actually happened in an emergency situation.
The ultrafast gas chromatographs in use in Queensland
In the event of a mine explosion the tube bundle monitoring mines allow the analysis of most the components expected
system may still appear to be functional but the location underground in approximately 2 minutes. Since their
from which tubes are sampling may not be the same, due introduction the number of routine samples analysed
to damage to the tubes. A good tube bundle system will has increased significantly allowing the mine to build
include monitoring of the vacuum pressure in each of the comprehensive background knowledge of the normal
tubes, so following an explosion this data can be used to background composition of particular areas underground.
determine whether a tube has been compromised or not. This increased sampling and analysis regime has also
It is also useful during routine operation for identifying increased the chances of identifying and deviation from
increased restriction or sudden leakage in a tube, both of what is normal and allows the early intervention to deal with
which can compromise the operation of the system. any problems identified.
If the tubes are damaged and not providing any valuable This increased speed of analysis is invaluable during
information, it may be possible to make use of boreholes emergency situations, particularly when assessing the
and connect new tubes to locations of interest as the safety of the underground atmosphere for re-entry or
surface equipment will still be operational (flame arrestors during re-entry by mines rescue teams. In these cases
are installed at each end of the sampling tubes). Another what makes this assessment more effective is that GC is
major advantage of the tube bundle system is that it draws onsite and can be operated by mine personnel. There is no
the sample to the surface and any locations requiring delay in determining the status underground while waiting
further analysis such as GC don’t require any additional for external providers to arrive or transporting samples
trips underground to collect samples. This is particularly away from site for laboratory analysis.
advantageous in emergency situations when personnel
may have been withdrawn from the mine and re-entry is COMPARISON OF TECHNIQUES
prohibited. Comparison of results obtained at the same monitoring
location using the different techniques are shown in Figures
GAS CHROMATOGRAPHY 1-7. It can be seen In Figure 1, that oxygen measurements
Gas chromatography, with regard to gas analysis, involves collected over 1 day showed much less variation in
the separation of all sample components followed by measurements made using the tube bundle than for the
their measurement on relatively non-specific detectors. real time sensor which regularly varied by more than 0.3 %
Specificity is obtained by virtue of the separation process
rather than detection. The use of a GC expands analytical
capabilities to include gases crucial in the interpretation
of spontaneous combustion events, particularly ethylene
and hydrogen. The GC provides a complete analysis
of the gases expected underground and is the only one
of the three techniques capable of measuring hydrogen,
nitrogen, ethylene and ethane. Determination of nitrogen is
particularly important for determining oxygen deficiency in
some spontaneous combustion indicating ratios. Similar to
the tube bundle, problems exist with bringing the samples
to the GC. The significance of time delays in getting results
is dependent on what the results are being used for. GC is
not going to be suitable for detection of a belt fire because
of the time delay between collection of the sample and
analysis, but the delay is acceptable for confirmation of
other results or for evidence and trending of spontaneous
combustion indicators. Figure 1: Real time vs tube bundle oxygen measurements.
14 Coal International • March-April 2021GAS MONITORING
Figure 2: Real time vs tube bundle methane Measurements. Figure 5: Tube bundle vs GC oxygen measurements.
Figure 3: Real time vs tube bundle carbon monoxide Figure 6: Tube bundle vs GC methane measurements.
measurements.
Figure 4: Tube bundle vs GC carbon dioxide measurements. Figures 7: Tube bundle vs GC carbon monoxide
measurements.
(absolute) between measurements. These variations make one-month period, reflecting increasing and decreasing
calculation of oxygen deficiencies used in ratios used for trends. The difference in absolute concentration seen in
indicating /assessing spontaneous combustion, unreliable. Figure 7 could be a result of a difference in calibration
gases used to set the instruments response.
The methane results collected over 1 week in Figure
2 show good correlation in the magnitude of methane When differences exist in the concentrations measured
and reasonable agreement with trends between the two using the different techniques it can complicate the
techniques. Although the absolute carbon monoxide application of pre-set trigger levels. It also means that data
concentrations measured over 1 day in Figure 3 were for trends should only be generated by one technique and
different, the trend over the 24 hours was the same for the not an accumulation of results. When trends from different
two techniques. This difference may be as a result of a techniques are viewed, they should indicate the same
difference in calibration between the two techniques or as pattern. Often these measurement differences are related
a result of sensor drift (most likely the real time). to the techniques themselves but some of the issues can
be removed if calibration gases used for each technique are
Slight differences in absolute concentrations are evident compared prior to being used to set instrument response.
and the difference in the amount of data collected by the
techniques is significant, however the tube bundle data and Another strong point of real time sensors and tube bundle
GC data (Figures 4-7) show very good agreement over a monitoring is that the monitoring points are at fixed locations,
Coal International • March-April 2021 15GAS MONITORING
Figure 8: Sample 1 as measured by tube bundle. Figure 9: Sample 1 as measured by GC.
Figure 10: Sample 2 as measured by tube bundle. Figure 11: Sample 2 as measured by GC.
Figure 12: Sample 3 as measured by tube bundle. Figure 13: Sample 3 as measured by GC.
resulting in consistent automated sampling/measurement. or fuel rich, due to the generation of percent levels of carbon
When samples are collected underground for subsequent monoxide and hydrogen during mine fires. The presence of
GC analysis, variations in results and trends can often be percent levels of these gases not only adds to the percentage
attributed to not collecting samples from exactly the same of combustible gases present but also has a major influence
locations, or poor sampling techniques. in the lowering of the oxygen nose point (the lowest oxygen
concentration at which an explosion can occur). Figures 8-13
Gas chromatography is the only one of the techniques that are examples of explosibility diagrams generated by GC
actually measures nitrogen. As mentioned, nitrogen is included analysis and tube bundle analysis of the same gas mix
in some ratios used to indicate spontaneous combustion. coming from heatings and mine fires. The composition of
These ratios are still calculated from measurements made these samples is listed in Table 1. Because the tube bundle
from the other techniques but when nitrogen values are analysis does not include the hydrogen, and only includes up
required, the nitrogen concentration is assumed to be the to 1000 ppm carbon monoxide, the percentage of combustible
balance remaining and calculated by summing the measured gas is underestimated, and the calculation of the combustible
components and subtracting from 100. This presents obvious (explosive) zone is incorrect. In a fire or heating situation,
problems with the reliability of such calculations and in critical without the GC analysis an assessment of the flammability
situations, calculation of these ratios should be done using GC of the atmosphere underground is likely to be unreliable and
results . It is usual practice to confirm any abnormal results can indicate that the atmosphere is inert when in reality it is
with one of the other techniques so prior to the need for any explosive. Figures 8 and 10 represent explosibility diagrams
such comparison knowledge of how the mine’s own individual generated using results from tube bundle analysis during
systems compare is required. advanced spontaneous combustion events. If tube bundle
results were used in isolation without consideration to the
ASSESSMENT OF FLAMMABILITY presence of hydrogen or concentrations greater than 1000
The need to perform a complete analysis by GC of ppm of carbon monoxide, then the atmosphere could be
atmospheres generated during coal fires or heating’s is assessed as being inert and rescue/firefighting teams sent into
not only critical but the only option to obtain an accurate the mine to deal with the situation. GC analysis of the same
assessment of the flammability status of the underground samples shows the atmosphere to be explosive (Figures
environment. Failure to do so can lead to wrongly assessing 9 and 11) and considering the intensity of the spontaneous
the atmosphere to be inert, when in fact it could be explosive combustion an ignition source is likely to be present.
16 Coal International • March-April 2021GAS MONITORING
Table 1: Mine fire samples.
Gas Sample 1 Sample 2 Sample 3
Hydrogen (%) 1.26 2.90 6.48
Oxygen (%) 10.45 7.51 6.48
Nitrogen (%) 78.85 78.45 73.17
Methane (%) 3.93 1.38 1.99
Carbon monoxide (%) 1.82 2.02 2.33
Carbon dioxide (%) 3.66 6.67 15.07
Ethylene (%) 0.013 0.048 0.1152
Ethane (%) 0.0179 0.108 0.0774
Figures 12 and 13 represent a sample collected from an indicative of the affected area and not just at the point of
advanced mine fire. In this case the explosibility diagram entry of the inertisation gas, otherwise assessment of the
from the tube bundle data shows the atmosphere to be situation may not be indicative of the true state.
non-combustible. This would mean that from this data only
and with no consideration to the presence of hydrogen CONCLUSION
or carbon monoxide concentrations greater than 1000 As beneficial as they are, it must be remembered that
ppm it would appear that it was safe to re-ventilate the monitoring systems on their own are not going to provide a
area as there was not enough fuel for an explosion. The successful solution to gas monitoring. Success depends on
explosibility diagram generated by the GC data shows that systems, processes and training built around the hardware
the atmosphere is actually fuel rich, and the addition of and the way these systems are used.
oxygen to the area could push the atmosphere through the
explosive zone, again with a likely ignition source present. • An effective gas monitoring system includes real time
sensors, a tube bundle system and a gas chromatograph.
These examples highlight the necessity to determine the • Each technique is addressing different hazards.
explosibility of the underground atmosphere using gas • Each technique has strengths and weaknesses which
chromatography. must be known by those both operating them and using
the generated results for interpretation.
TRIGGER ACTION RESPONSE PLANS (TARPS) • Effective maintenance and calibration procedures are
Mines determine gas levels that they think should not be
required to ensure reliable ongoing operation of mine
exceeded. Often these numbers are based on historical data
monitoring systems.
collected from the monitoring systems. To handle the large
• Interpretation of data is best done looking at trends
volumes of measurements made gas monitoring software
rather than one off samples. Even if the situation is
has been developed that will automatically trigger a visual
being underestimated, any increase in intensity should
and audible alarm if one of the pre-set levels is exceeded.
result in an increase in the trend although the rate of
Alarm set points can be different for every sample point.
change may not match the increase in intensity.
These alarms activate what are known as Trigger Action
• Trends should only be based on data collected from the
Response Plans (TARPS) that have predetermined actions
same technique.
to follow. These actions have been formulated to ensure
that appropriate actions are taken to ensure the safety of • There are likely to be differences between in absolute
workers and maintain control of the mine. measurements made using different techniques.
• A true indication of the flammability of the mine
Alarms can be generated from absolute concentrations, atmosphere during a mine fire, heating or post explosion
gas ratios or explosibility. They are most useful as an early can only be determined by gas chromatograph analysis
warning, not as an alert to an emergency or a need to due to the high concentrations of carbon monoxide and
evacuate the mine. When alerted early enough the mine hydrogen possible.
will have time to take remedial action to rectify the problem.
Having continual automated gas monitoring provides the REFERENCES
best chance for early detection. Australian Standard (1990) AS2290.3 Electrical equipment for
coal mines -Maintenance and overhaul Part 3: Maintenance of
The frequency and scope of monitoring is often included gas detecting and monitoring equipment.
in the TARPS to ensure that the situation is not escalating The Coal Mining Safety and Health Regulation 2001 Reprint No.
or that the control measures are being effective. It must 2C, 2007 the Office of the (Queensland Parliamentary Counsel).
be noted that if inertisation is one of the control measures
called for in the TARPS, any monitoring to determine the ACKNOWLEDGEMENT
effectiveness of the control must be done from a location Darren Brady Department of Mines and Energy, Queensland
Coal International • March-April 2021 17NEWS, PLANT AND EQUIPMENT
Bonfiglioli acquires SampingranaggI
Bonfiglioli S.p.A. won Bonfiglioli S.P.A. had signed
the auction at the Court a “Bonfiglioli/Sampingranaggi
of Bologna, 12 March integration agreement”
2021, for the acquisition with the Emilia-Romagna
of Sampingranaggi from Region, Metropolitan City
Bentivoglio (BO), for € of Bologna and FIOM-CGIL
7,158,000. Emilia Romagna. FIOM-
This acquisition confirms CGIL Bologna and the
the interest Bonfiglioli S.p.A. Sampingranaggi joint trade
had already expressed in union representatives (RSU),
Sampingranaggi, generated a pact that the Group has The Chairwoman Sonia the human hand, machines
by the total synergy of declared complementary Bonfiglioli commented: are merely stationary atoms.
Sampingranaggi’s know- and functional to its own bid, “I like to think that, if Their skills, knowledge and
how with the Group’s design with a view to safeguarding Sampingranaggi had not experience are the great
and production strategies the production continuity of already been there in the heritage of Sampingranaggi,
. The move preserves Sampingranaggi and the post-war period, today and today become part of the
and consolidates the people who work there, Bonfiglioli would not exist. great Bonfiglioli family. My
Sampingranaggi strategic currently about 80 employees. Because it all began there, in warmest welcome goes to
supply chain, strengthening A priority will in fact be the 1948, when a young technical them.”
their role as a technological appropriate enhancement graduate started out on a “For Bonfiglioli, SAMP
pivot for the Bologna regional of the workforce, also valuable journey of work and represents a great
and metropolitan area. through the provision of experience that, three years opportunity,” underlined
The acquisition includes the Bonfiglioli Academy’s later, led him to set up his first Fausto Carboni, CEO
the assets of the Italian and continuous training programs, business. of the Group, “in many
Chinese Sampingranaggi now available also to the So beyond this aspects. From an industrial
companies (Bentivoglio – Sampingranaggi staff, with “sentimental” reunion, which point of view, it offers us
BO, Funo di Argelato-BO a view to a synergic and makes me very happy, and the possibility to integrate
and Shanghai-China), their transversal use of their the full complementarity some strategic component
respective warehouses, respective skills. of Sampingranaggi and productions, including bevel
the Sampingranaggi brand, With this acquisition, Bonfiglioli products, my first gears, while in terms of
patents, designs and products Bonfiglioli S.p.A. will be able thought, however, goes to business development it
for robotics, as well as all their to increase its production the women and men of this allows us to enter the robotic
staff. Sampingranaggi’s 2020 verticalization both in Italy company who now become gearbox market, where there
turnover was €21 million, of and China, accessing the an important part of Bonfiglioli. is ample room for growth
which €15 million in Italy and robotics market also through Many times we could have in future, both in Italy and
€6 million in China. the development of other bought plants to produce in China through their local
Precisely with this in extremely precise and efficient bevel gears (that are the heart company, which that is part of
mind, on 3 March 2021 products. of gearboxes), but without the acquisition.”
Weekly reports yet to be experienced. TFR coal and EU carbon prices
has struggled with railings are once again dampening
It would appear that China significant strength in both to RBCT since the start of European dark spreads
was South Africa’s largest basins, whilst many Chinese 2021, with unavailability of after the recent surge of
export market in February, buyers are immune to the locos, heavy rain and Covid coal purchases, whilst
followed closely by Pakistan, freight market, either owning related issues causing warmer weather in SE Asia
beating India into 3rd place their own vessels or having problems. Which probably has seen Korean demand
as Indian buyers struggled long-term fixed rate capesize all goes to explaining why slow down too.
with firmer freight rates. time charters. physical RB1 is trading at a Eskom is apparently
Panamax rates have seen It seems that Chinese $3 premium to paper. going ahead with a revised
buyers don’t Japan’s J-Power 10-year Duvha contract
have issues with has meanwhile started for around R600/ton,
SA coal’s trace producing liquified hydrogen which is terrible timing for
elements after from Australian brown coal, it considering coal prices
all, although the as Australia pushes to are making recent highs.
first cases of become a major hydrogen Locking in prices for 10
cargoes stuck exporting nation. CO2 years is also an incredibly
in dispute with released from the process brave move, which will likely
China’s CIQ is planned to be buried off either result in hero or villain
agency have the coast of Victoria. High status in the future.
18 Coal International • March-April 2021You can also read
