Mining operators have the difficult task of maintaining high productivity while keeping their crews safe in difficult working conditions. Large mining vehicles are at the center of these dual concerns.
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Loaders, haul trucks, and other large mining vehicles are built to move hundreds of tons of rocks and minerals. The weight and power of these machines make them effective, but also dangerous, and tires are an integral part of these vehicles.
The Importance of Tire Safety
The tires on large mining vehicles are designed to provide stability and necessary traction to move materials and prevent accidents. They are constantly under pressure and continuously flexing. When mining vehicles move, the resulting friction generates heat and slowly breaks down the tires. When one of these large tires ruptures or breaks down, it can cause many problems. When tires are filled with oxygen-containing air, a sudden rupture or a lightning strike could spark a lethal explosion.
In recent years, there has been a trend toward filling the tires of passenger cars with nitrogen, and this trend is starting to catch on for vehicles in the mining industry. Nitrogen has been shown to help maintain tire pressure and increase fuel efficiency in passenger vehicles. While those same benefits can translate to mining vehicles, there is the added bonus of increased safety. Any risk of explosion is far, far less when tires are filled with nitrogen.
Nitrogen vs. Air
Currently, mining vehicle tires are typically inflated and pressurized with air from the surrounding atmosphere. The air around us is typically made up of about 78% nitrogen, 21% oxygen, and a small amount of water vapor. Filling a tire with nitrogen usually means inflating it with a gas mixture containing at least 95% nitrogen.
Using this gas mixture translates to several direct benefits, including slower loss of pressure and less corrosion of metallic tire components caused by water vapor. As a result, workers and mining operators can work with greater safety.
Improved Tire Life
When tires are deflated, they wear out faster. Both oxygen and nitrogen are capable of permeating through the wall of a tire, but nitrogen does it four times slower than oxygen and more than 100 times slower than water vapor. Under extreme physical conditions, deflation occurs at a faster rate and nitrogen helps to maintain an acceptable level of pressure for longer. By some estimates, using nitrogen can extend the life of a tire by 10 percent.
Reduced Tire Failures
In addition to being a safety concern, tire failures can lead to work stoppages and potentially significant downtime. Tire failure is often the result of overheating caused by vehicles transporting heavy loads across rough ground. Tires are even more prone to heating in dry, hot conditions. Nitrogen helps to keep tires optimally inflated, reducing flex and friction.
Enhanced Fuel Efficiency
Because a tire loses nitrogen at a much slower rate, it helps to maintain optimal fuel efficiency. According to the United States Environmental Protection Agency, gas mileage decreases 0.3% for every one psi, decreasing the entire pressure for all four tires. One study performed with a Canadian trucking company found a 3.8% boost in fuel efficiency attributed to nitrogen tire inflation of long-haul truck tires.
Safer Work Environments
The size, mass, and magnitude of tire pressure make the large tires on mining vehicles a safety hazard. These tires are even more hazardous when filled with oxygen and used around combustible materials. Tire fires are dangerous in normal situations, but even more so in an underground mine. Filling tires with nitrogen significantly reduces the risk of underground tire fires.
In certain operations involving combustible materials, mining crews must ensure that lightning strikes do not cause an explosion. Inflating tires with nitrogen significantly reduces this risk of explosion.
Cost Savings
When a tire is filled with air, oxygen and water vapor from the air permeate the tire wall and cause the tire rims to rust. Rusted tire rims do not fit tires as well as clean rims and this poor fit can lead to greater pressure loss, increasing the risk of tires operating under low pressure and wearing out faster.
Implementation Challenges
While nitrogen tires are capable of making mine safer and more efficient, there are challenges to implementing a nitrogen inflation system. First and foremost, transporting nitrogen over large distances can be expensive and emission-heavy, and mining operations are often located in remote areas. Ideally, nitrogen would be generated at the mining site and some companies are looking into this possibility.
There would be an added benefit to generating nitrogen at sun mining sites, as the gas is often used and the extraction or processing of raw materials. For example, it is often used at a coal face to suppress methane and decrease the chance of spontaneous combustion. Nitrogen could be generated at the coalface because it gives operators the ability to transport the generator along with other axillary equipment, decreasing the need to run pipelines underground.
Case Studies
Although the use of nitrogen tires is not widespread in the mining industry, it is beginning to take hold as there are several operations currently using them. In fact, the use of nitrogen tires has become quite popular in South Africa, with most large mining operations using them as the industry standard.
According to NitraLife, which supplies nitrogen generators to mining operations, the initial South African standard was 95% nitrogen purity, but now, the standard is closer to 98%.
According to Mining Weekly, NitraLife has also supplied nitrogen generators to operations in Zambia, the Democratic Republic of Congo, Asia, and the Americas. While the company does offer to have its technicians install and maintain nitrogen generators, NitraLife says its technology is very user-friendly and easy to install.
Conclusion
Clearly, there are many benefits to using nitrogen tires in mining operations, particularly when it comes to making them safer. In fact, many mining operations are already using the technology and reaping its benefits. Although there are implementation challenges to consider, installing nitrogen generators deep into underground mines offers additional benefits.
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References and Further Reading
Tunnicliffe, A. (2023, June 8). On a roll: how nitrogen is fast becoming the tyre-filler of choice. Mining technology. https://www.mining-technology.com/features/how-nitrogen-is-fast-becoming-the-tyre-filler-of-choice/
Mining Weekly. (2017, November 24). Mining the most out of OTR tyres with Nitralife's nitrogen filling: Improved safety, better inflation and less hot air. Mining Weekly. Retrieved from https://www.miningweekly.com/article/mining-the-most-out-of-otr-tyres-with-nitralifes-nitrogen-filling-improved-safety-better-inflation-and-less-hot-air-2017-11-24
Geng, H-J, et al. The Application of Nitrogen Curtain Technology to Longwall Goaf to Prevent the Spontaneous Combustion of Coal: A Case Study in Shajihai Coalmine, China. Journal of Open Innovation: Technology, Market, and Complexity. https://www.mdpi.com/2484950
Tire Review. (2023, September 8). The Benefits of Nitrogen in Tires. Tire Review. https://www.tirereview.com/benefits-nitrogen/
Majkrzak, S. (2011, November 3). Nitrogen tire inflation. OEM Off-Highway. https://www.oemoffhighway.com/drivetrains/article/10447183/nitrogen-tire-inflation
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