Belt conveyor systems are used extensively in the mining industry – they provide an ideal solution to transport bulk material. However, a key protection area that has to be considered is how to best handle the issue of conveyor belt system fires.
“Any large fire may damage or cause the collapse of the conveyor structural elements with resultant interruption to operations and high replacement costs. The principal fire load includes the material being conveyed, the electromechanical components of the system, and the belt itself.”
There is a misconception that conveyors are not easily ignitable, which can often prevent mines from taking the necessary precautions to ensure that there is sufficient fire protection in place: “Once a moving conveyor fire starts, it will grow rapidly, and become very difficult to control in a very short period of time. 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 the control of which, incredibly difficult.”
In June this year 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 $13-million in 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.
“As such, the essential ethos behind any quality conveyor belt fire protection needs to revolve around the preservation of the conveyor belt system itself. Hence, the need for early detection and the quick and successful extinguishing of any fire, while simultaneously cooling the effected structure, remains key.”
Early detection, fast-acting fire prevention solutions are key
“It is important to note that every conveyor belt system is unique, and as such, an individual assessment has to be made for each system in order to adequately and accurately determine where the fire risks lie for that particular system design”.
To ensure early fire detection in conveyor belt environments, ASP Fire recommends the installation of Technoswitch Fire Detection technologies in conjunction with suitable Fire Control and Extinguishant panels, which are specially suited to long-distance and moving environments – these include:
• Ember Detectors, which detect a smoldering ember on a moving conveyor belt before it bursts into flames.
• Linear heat detection cable is used for very long distances, which are prevalent on conveyor belts, and responds to a rise in heat that is above the alarm threshold.
• The IR3 Flame Detectors uses three different Infrared light wavelengths to detect an open flame within the conveyor system.
Rapid Fire Suppression eliminates equipment damage and downtime
To complete the fire protection system, ASP Fire recommends the iCat Fire Solution’s industry-leading technology to provide a cost-effective and efficient solution for conveyor belt fire-suppression: “The iCat Rotor Technology water mist fire suppression system can automatically detect fire and effectively suppress a fire in a matter of seconds before it becomes a problem.”
The iCat T-Rotor Technology systems are a prime example of innovative New Age technology – providing localised protection, hand-held extinguishers, fast response back-packs and vehicle protection systems. They comprise extinguishers that use a combination of water and/or foam in a mist form, as opposed to traditional fire extinguishers that use either dry foam or chemical powders.
“The misting technology of the T-Rotor Technology atomises water and charges it with kinetic energy, creating a fine atomised mist with a size of between 50μ and 60μ. Using water as the main agent, and nitrogen as a propellant – it can extinguish all types of fire, including rubber and plastic fires, kitchen cooking oil fires, diesel and petrol fires and electrical fires rated up to 245kV”.
The system can also be designed to create cooling zones on conveyor belts to detect and cool hot material without adding to the moisture content of the product, to reduce any potential fire risks.
The Water Mist extinguisher range is FM and SABS-approved: “Using water and nitrogen is safe, effective and saves on maintenance and service costs. Each litre of water in a water mists system amounts to 120 square metres of coverage capability, and the small quantity of water that is used has the added benefit of ensuring little to no redundancy, damage or environmental contamination.”