In an open pit mine setting, there will be much use of ultra-class trucks that employ off-the-road tyres. A tyre fire is a very serious emergency situation. Pyrolysis of tyres is when the rubber material is heated and converted into flammable gases from high temperatures or internal friction, typically in absence of a flame. The handling of these explosive incidents calls for very stringent procedures.
It is important to know about the nature of pyrolysis as a danger in such scenarios. Pyrolysis is the chemical process where the solid rubber parts of the tyre get converted into very pressurised hydrocarbons (Januszewicz et al., 2020). When the tyre bursts due to over-pressure or the gases ignite in the presence of air, an explosion takes place with rubber parts flying far out due to sheer force of the explosion.
Once a tyre fire has been detected, the necessary operating procedure must be carried out immediately. The driver will move the truck to a secluded place, keeping it away from all other people and structures. Once he activates the fire suppressing system within the truck, the driver must quickly leave the truck and inform the emergency dispatch center.
Pre-incident planning by emergency response teams is essential for managing vehicle fires in mining facilities (Hansen, 2021). The first safety measure that must be implemented once a fire breaks out is setting up an exclusion zone. Mining companies have strict requirements where there should be a 300-meter radial barrier surrounding the truck to protect all mining facility personnel from the explosive fire zone.
The management of such an incident does not allow using water or foam directly on the burning pyrolyzing tyre since cooling the tyre leads to contraction or cracking of the metal rim, resulting in the explosion almost immediately. It is important to let the tyre cool down by itself. For this purpose, the zone of exclusion remains for no less than 24 hours until all signs of heat and smoke disappear. To check the temperature in the tyre remotely, thermal imaging cameras are used.
Safety protocols must be strictly followed to manage a fire incident involving a haul truck tyre. With knowledge of the danger presented by the pyrolysis, timely vehicle isolation, expansion of the exclusion zone, and natural cooling, it is possible for open-pit mines to deal effectively with these explosive situations.
References
Hansen, R. (2021). Pre-incident planning of fires in underground hard rock mines: old and new risks. Australian Journal of Emergency Management, 68–74. https://doi.org/10.47389/36.4.68
Januszewicz, K., Kazimierski, P., Kosakowski, W., & Lewandowski, W. M. (2020). Waste Tyres Pyrolysis for Obtaining Limonene. Materials, 13(6), 1359. https://doi.org/10.3390/ma13061359
