Safety & Health in the Stone Crushing Industry - Occupational ...

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Noise is mostly produced by either impact or vibration. This happens at the following locations in a
stone crushing unit:
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The crushers themselves(Primary and Secondary) when boulders are crushed and
transported along conveyors
The boulder loading point when boulders are fed into receiving pit
The sieves when the gravel is sorted
Noise can have the following effects on the health of workers and owners:
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Distortion of sounds (hearing something, but not understanding)
Temporary or permanent hearing loss
A continual ringing in the ears for which there is no cure ("tinnitus" in medical terms)
Quickened pulse rate, increased blood
pressure and a narrowing of the blood vessels
Abnormal secretions of hormones, muscle
tensing, nervousness, sleeplessness, fatigue
Solutions to protect health
Conduct regular maintenance: replace all
unbalanced or loose parts of machines
Lubricate turning machine parts regularly
Replace metal parts with quieter plastic parts if
possible, for instance rollers, washers
Machines which vibrate should be mounted on
heavy, rigid bases to prevent vibration
Consider putting heavy rubber or plastic mats on
places where impact or machine parts or boulders
cause noise
Enclose especially noisy machine parts with punctured metal plates, best in several layers so
the sound gets "trapped"
Position workers away from noise sources as much as possible
Provide hearing protection for workers, such as earplugs and earmuffs, train workers on the
purpose, proper fitting, and care of hearing protectors and provide continuous monitoring of
employee noise-exposure levels if possible. However, in that case collaboration with experts
in occupational health is needed for advice
Always use properly shaped and sharpened cutting tools so you need less force to cut things.
We show here a noise map of a typical stone crushing unit. The areas in the centre, in red (dark grey in
the black & white print) indicate areas with more that 90 decibel of noise (measure in decibel on scale
A, adapted to the capacities of the human ear, abbreviated dB (A)) where hearing protection needs to
be worn. It is the area around the crushers and the sieve. The next area around it, in pink (gray) has
noise levels over 85 dB(A) where hearing protection should be provided. Noise levels above 85 dB(A),
and definitely above 90 db(A), are dangerous and will lead to noise-induced hearing loss after a short
time. They are also a risk factor to develop high blood pressure, nervousness, and irritation, all of
which can increase the risk to have heart diseases such as heart attack, or stroke.