Conveyors in mines and quarries for heavy material handling are the most important logistics management asset on the site, delivering the raw or product material from the mine excavation right through to shipping.
They are also one of the highest maintenance costs for the site with frequent (e.g. shift) inspections of drive bearings, idler rollers, conveyor belt condition and tracking, chute blockages, spillage and so on.
The conveyor belts can span from 1 up to 4 metres in width and travel up to speeds of 5-6 m/s, and can cost in the vicinity of $1M to replace for a 1-2 km conveyor length.
A fire (e.g. 09-21-2015-Swanton fire ) on a conveyor system can start from multiple sources, including the material being transported itself, right through to overheated components such as drive or idler bearings, or smouldering dusts leading to spontaneous combustion situations.
Traditional fire detection on and around mine and process plant conveyors has been difficult to achieve using conventional point heat detectors and aspirating CO gas detectors. This is mainly due to the conveyors’ long length and variable physical orientation (e.g. slopes, corners, enclosed or open structure), high speed of the belt dispersing any gases, harsh operating environment, and prohibitive costs for the supply, installation, and maintenance of effective conventional fire detection systems on this scale. The result has been inadequately performing conveyor fire detection systems, and in most cases no fire detection at all.
This overheated bearing can damage the conveyor belt via gouging and become a fire ignition hazard.
In fact, it has reached a temperature of over 180°C, which is well above the ignition temperatures of many dusts including coal.
A fire detection system that can address these conveyor operating conditions would greatly increase fire safety for the protection of people, fixed assets, and minimise disruptions to plant production.
Distributed Temperature Sensing (DTS) technology using a resettable linear heat detector on a single fibre optic core has been successfully tested and deployed on underground and surface conveyor systems.
The DTS system’s capabilities have been proven to exceed conventional point or linear (copper wire based) heat detectors, or aspirating CO gas detectors. The ruggedized fibre optic based system has the capacity to detect fires quickly and localise the source to within 0.5 metres. This precision is unaffected by wind and other environmental effects, because not only convective, but also conductive and radiant (infrared) heat is measured by the system.
Our fibre optic cable distributed temperature system (DTS) provides the following key features for the heavy materials handling conveyor system:
- Accredited for fire detection use (flame resistance 750°C for 2 hours, IEC 60331)
- Doesn’t propagate the flame along the cable (IEC60332-3).
- 24×7 remote temperature monitoring of the entire length, for total coverage.
- Provides the actual location of the fire, to remote monitoring control rooms.
- It provides early warning of heat before a flame occurs.
- Can be installed in harsh environments (stainless steel cable sheath with high crush resistance).
- Is immune to EMI (electromagnetic interference).
- Requires no maintenance, after it is installed.
- The fibre cable is the sensor, no other cabling or field interface devices required.