Page 53 - Vol 28 Issue 29 2019

safety mining

• Moving cranes are equipped with transducers (LDT). These are installed that can cause the mounting of
brakes and, much like a car, these on the machine to help automate the non-IECEx approved products,
brakes need to be changed. This process and guide the operator, and or even non-grounded products
needs to happen on a routine basis thereby minimize the risk compared such as lights, drills or pumps.
before the brakes stop functioning. to the process where manual handling For some areas, using a simple
Brakes for cranes are electrically alone is used. Some machines use the grounding reel can be enough to
released and spring set for safety. LDT to measure the deflection of the avoid explosions. Rugged grounding
On magnetic industrial brakes the shovel boom to eliminate the risk of reels using static grounding cords and
electrical mechanism consists of lifting a shovel that is too heavy. Lifting clamps can secure the grounding,
one or two DC coils. As power is a shovel that is too heavy can not only and thereby the work safety,
introduced to the coils, it creates an break the machinery but also increase in accordance to the individual
electromagnetic field that releases the danger when an excavator tip over. hazardous zone classification.
the brake. Cutting power to the coils Retrofit type solutions can increase
allows the spring to extend back to its product and personnel safety • When storing or moving materials, it is
original position and sets the brake. significantly at a reasonably cost important to be able to continuously
• Hydraulic hoses, and power or signal on out dated but still well running measure the stream or amount of
material to avoid accidents due
cables are usually an unforeseen machinery. An LDT is typically to overload. Non-contact position
danger. A broken hydraulic fluid mounted inside the cylinder to provide sensing solutions, such as radar
hose may cause a burst of 100°C the best protection of the electronics, level transmitters, have been proven
fluid spraying out at over 300bar. but on older hydraulic cylinders, the performers in the mining industry for
The consequences for the colleague inside mounting may be too difficult. many years. Quick response times and
standing nearby could be crucial! Focus As a result, some LDT’s can be state-of-the-art electronics make this
on safety and efficiently conveying mounted on the side of the cylinder technology an excellent choice for fast
power by protecting the cables and providing virtually the same accuracy. moving material. Overfill prevention
hoses is pivotal in the mining industry. It is not crucial whether or not the and ensuring clearances on large
The cables and hoses deliver power, LDT is mounted inside or outside the and heavy materials is paramount in
air, or hydraulic (or a combination of hydraulic cylinder. What is crucial keeping the work environment safe.
these) to mining equipment in motion. though is to make sure that it is a
This is critical to the operation of most high quality LDT that is installed, so Installing these instruments on heavy
equipment and the best protection it is able to withstand the constant machinery may enhance the longevity
secures the hoses and wiring vibration and shock that is very as well as lower the number of
from abrasion, wear and twisting. breakdowns. But at the end of the day
common on these machines. whether one is mining for coal, gold
• The hydraulic cylinder controls the • Dusty environments are extremely or anything else, safety should at any
extremely heavy equipment used in hazardous. The combustion level given time be first in line. As the study
mining. It also controls where the of dust, and especially of coal dust, from China clearly states, humans
drilled ore will fall from the excavator. can create an explosive atmosphere, make mistakes. It is the responsibility
Knowing the position of these cylinders where the slightest spark will create of any company to minimize the risk
at all times is important to avoid a potential disaster. Using IEC 60079- of human errors, and to do so by
shovels or drills from getting out of 11 certified products has been the educating the personnel as well as
balance. Position monitoring is often safety standard in South Africa since using simple technical instruments.
performed by linear displacement 2005. Make sure to avoid mistakes

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AFRICAN POWER Mining & Oil Review Vol 28, Issue 29, 2019 | 53
MDA Ad.indd 1 2019/11/28 09:50