Open cut mining operations are a constant movement of heavy plant equipment and all miners are well aware of the risk that this equipment can catch fire. It is an inherent risk of operating heavy equipment fitted with high powered diesel engines, heat generating turbo chargers, high pressure hydraulic systems and large rubber tyres.
Common causes of plant fires are well documented and mining operations are continuously improving their maintenance strategies and work tasks to reduce the risk of component failure or work error leading to a plant fire.
Unfortunately, even with all the maintenance strategies and controls in place, plant fires are still an occurrence in our mining operations, when they occur the best opportunity to take control of a fire is with the help of the first responder: the mining water truck.
Distributed across the mining operation, water trucks spend their days managing dust and maintaining haul roads, but their place in the pit makes them the perfect candidate to respond to afire emergency. Their large water tank and pumping system are one of the key ingredients to combat fires quickly before they become uncontrolled and the loss of plant equipment, resulting in lost production, downtime and a rigorous investigation.
Mining emergency response teams (ERT) are ultimately responsible for responding to emergency incidents on site, but depending on the size of the mining operation, the travelling distance to the site of the incident can mean precious time is lost. In the event of a fire, a quick responding water truck can take control whilst the ERT are in transit.
In their standard form, a mining water truck may not be well equipped to combat equipment fires, it takes more than a big water pump. Mining operations need to consider all aspects of the water truck including the water pump motor drive circuit, the water pump flow specifications and ensuring the hydraulic motor matches the truck specifications, the water pump specifications and the water delivery equipment such as water cannons and sprays. Don’t forget to look for restrictions in the water pump inlet and outlet piping and make sure the rock screen filter is empty.
Most mining water trucks are fitted with a water cannon to the front of the tank, it is an effective way of adding fire-fighting capabilities. Adding a foam induction nozzle to the water cannon further improves this capability as it can then deliver fire suppression fluids to a fire. But being capable may not mean effective, and just like “Oils ain’t oils”, fitting the right water cannon can require increased water output and a substantially higher water delivery pressure for greater water throw distance(reach). Water pipe diameter and its routing from the water pump to the water cannon can be a major cause of restriction. So when selecting a water cannon nozzle it is imperative that the water delivery system can actually achieve the water cannon’s flow and pressure performance specifications. Also review your sites operating procedures to ensure that fighting fires with water cannons is an accepted method on your site.
ADE has designed and manufactured a water cannon specifically for mining that feature a stainless-steel body, integrated water on/off valve and nozzle options offering up to 3000 litres per minute water output.
Depending on your mining procedures however, the use of a front water cannon for fire fighting duties may not be appropriate especially when combating tyre fires. When the water cannon is not available, water truck operators can reverse up to a fire and utilise the rear mounted spray head valves, but this method has limitations as the spray heads normally used for haul road dust suppression may be fitted low or angled downwards reducing effectiveness.
Some mining operations have tried to remedy this issue by fitting one or two high mounted spray head valves specifically for combating tyre fires. The spray head valves typically have a water flow rate of up to 1500 litres per minute and a reach of approx. 10 meters. The setup is not ideal considering most water trucks on a mine site are several classes smaller than the haul fleet, the reality being that the fire sprays hardly reach half the height of the tyre of the truck that could be on fire.
Through consultation with a mining operation near the town of Blackwater, QLD, ADE has designed and manufactured a rear fire spray solution that utilises adjustable nozzles rather than spray head valves. The nozzles are remotely adjustable from a fog to a jet stream with a total water output of up to 6000 litres per minute. Water reach has increased to over 50 meters and there is an option to induct fire fighting foam directly into the nozzles.
Your current fleet of water trucks might be capable of fighting a fire, but may not be overly effective, flow losses through piping, or a slow turning hydraulic motor can dramatically reduce the overall water output through a fire nozzle. Just like you wouldn’t want to fight a house fire with a garden hose, the size of large mining equipment demands high water output when stricken by fire.
ADE can review your water truck fleet and provides solutions to transform your water trucks into an effective first responder
Read More: www.amsj.com.au
Australasian Mine Safety Journal: Winter 2021 Edition