Modern Mining December 2015

MATERIALS HANDLING

Fire protection essential for conveyor belt systems

T his is the view of Michael van Niekerk from ASP Fire, who goes on to add: “Conveyor belt sys- tems and supporting structures are normally of non-combustible construction; however, any large fire may damage or cause the collapse of the structural elements. The principal fire load includes the material being conveyed, the mechanical com- ponents of the system, and the belt itself.” He says there is a misconception that con- veyors are not easily ignitable, which can often prevent mines from taking the necessary pre- cautions to ensure that there is sufficient fire protection in place: “Once a conveyor fire starts, it will grow rapidly and become very dif- ficult to control in a very short period of time.” He points out that belts contain polymeric materials, which present a serious risk in terms of rapid fire spread and the generation of toxic, corrosive smoke – making these fires lethal and incredibly difficult to control. In June 2015, for example, a fire that burned a multi-story conveyor belt at a Lake Elsinore aggregate mining and crushing business in the USA caused an estimated US$13 million in Belt conveyor systems are used exten- sively in the mining industry – they provide an ideal solution to transport manageable sized material from one processing point to another. Using such a system reduces the reliance on manpower and reliability is maxi- mised. However, a key protection area that has to be considered is how to best handle the issue of conveyor belt system fires.

damage and took firefighters more than two hours to contain. “When you consider the overall loss caused by a conveyor belt fire, you can’t just think about the possible loss of lives, injured staff and the loss of expensive equipment, but you also have to consider the excessive loss of revenue that will be incurred by the downtime required to fix or rebuild the conveyor belt,” says van Niekerk. “As such, the essential ethos behind any quality conveyor belt fire protection needs to revolve around the preservation of the con- veyor belt system itself. Hence, the need for early detection and the quick and successful extinguishing of any fire, while simultaneously cooling the affected structure, remains key. “It is important to note that every conveyor belt system is unique and, as such, an individ- ual assessment has to be made for each system in order to adequately and accurately deter- mine where the fire risks lie for that particular system design.” He notes that – in his experience – the most common causes of conveyor belt fires are static heat build-up from friction caused by belt movement, moving fire on the belt itself,

An underground conveyor tail pulley fire with water mist system in action.The water mist fire suppression systems available from ASP Fire force water through micro nozzles at a very high pressure to create a water vapour mist. Fire extin- guishing occurs due to a combination of the cooling effect of the water mist and the displacement of oxygen caused by the expansion of the water mist as it is vaporised.

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December 2015  MODERN MINING  29