Methane is the second most important anthropogenic
greenhouse gas that influences troposphere ozone and water vapor. In small concentrations, methane is not
dangerous and poses no threat to human health and life. However, once there is
a buildup in methane concentrations, it can cause serious damage to humans and
the environment hence methane monitoring is crucial to reduce the risks of
accidents.
Minimizing the risks
of methane through monitoring
Methane is a colorless substance which is a principle component
of natural gas. Natural gas is considered by modern society as an ideal option
to fossil fuel because of its clean and safe combustion. While methane is not
considered toxic, it can cause suffocation when it displaces oxygen in the
environment and reduces the concentration of oxygen required for breathability.
Methane is also combustible and mixtures of approximately 5 to 15% in the air
are considered explosive. So unless methane monitoring is used in certain
situations, there is high risk for methane to cause asphyxiation and
explosions.
The importance of
methane monitoring for the mining industry
The use of machine mounted methane monitors is required by
the federal government so that miners will be warned of the presence of
dangerous concentrations of methane while mining coal. The methane monitoring
equipment must be permanently mounted on machines to provide continuous
readings of methane levels. Response time of methane monitors is very critical
because methane levels can fall or rise rapidly and the miners must be able to
respond accordingly to these changing conditions otherwise their life might be
at stake. Machine mounted methane monitors must provide warnings whenever
methane levels are 1% and higher and before it reaches face reach at 5%. One of
the most significant factors for the accuracy of methane monitoring is the
proper placement of the monitors on the mining machine.
Proper placement of
methane monitoring for quick response
Based on the Office of Mining Safety and Health Research
(OMSHR), the design of the protective dust cap over the methane monitor has the
greatest effect on its response time. All sensors used in the mining industry
have these dust caps that protects the sensor’s head from the harsh influences
of the mining environment. Although methane monitoring equipment with faster
response times provides the most accurate measurements, the sensors need to be
protected from the excessive amounts of dust and water.
The best possible location of methane sensors on a
continuous mining machine would be on the return side of the machine that
offers the most accurate assessment of face methane levels. However, locations
that are close to the face are bound to suffer from damage during mining
activities while if placed farthest from the face, sufficient accuracy of
measurements will not be achieved. The research of OMSHR is exploring the
benefits of placing a secondary methane monitoring device on a mining machine
to provide earlier warning should there be hazardous methane concentrations.
Further refinement in the design of the protective dust caps is also being
explored so as to reduce the potential for mining accidents due to methane
buildup.
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