The Critical Role of Gasket Materials in Mining Industry30 November 2020
Gasket materials in underground mines are those that minimize dangerous site ignitability hazards. The products described below only serve to prove one hard fact: There can be no gambling, no wagering with what are essentially high-risk work conditions here, not when lives and limbs are at stake. Fire Resistant and Anti-Static FRAS products, therefore, exist to prevent flame propagation events, to basically fireproof mines and to minimize the electrical build-ups down there that could cause an explosion.
Reviewing FRAS Issues in Underground Mines
Let’s use a coal mine to highlight the hazards found down here, although any mining installation could trigger a fire threat. If anthracite and bitumen are exposed in a mine chamber, it’ll likely produce a fine black mist. Of some concern, this is a solid fuel. It’s not as combustible as some gaseous fuels, but it will ignite if the conditions are right. Besides, coal mines can also release pockets of methane. In fact, any mining facility can unlock a chamber full of methane. Bad enough, this “Firedamp,” this potentially explosive mixture is floating around, but it’s also contained, trapped in an underground mine’s many subterranean chambers, where workers are going about their business. By adding static to the already highly volatile mix, the whole installation begins to resemble a closed-in tinder box.
Anti-Static and Anti-Flame Propagation Solutions
FRAS products are essentially made from large rubber sheets, although they’re also sometimes die-cut into smaller, thinner strips as well. The rubber acts as a sheath for exposed metal surfaces, pipes, equipment frames, and all manner of underground mine apparatus. The goal is to insulate and isolate conductive parts, to prevent static build-up and to fireproof flammable materials. If a situation occurs where a spark could be generated, fire-retarding FRAS rubber minimizes the accumulation of static electricity. Moving onto FRAS-rated gear, composite pulley linings and conveyor skirts can be used to illustrate another example of a FRAS safe equipment build. This time, instead of layers of rubber sheeting blanketing a pipe or vent duct, special rubber composites are fabricated as integral equipment components.
There are also FRAS rated screening decks and belt scrapers. Steel-reinforced crushers and vibratory pans use FRAS materials as well. Of some benefit here, the anti-static materials also function fairly well as impact dampening surfaces, so they protect underlying steel surfaces from high-velocity aggregate loads. Up higher, above the equipment lines, anti-static and flame resistant plastic meshes function as mine ceiling guards. They line ceilings and walls. Indeed, high-functioning FRAS mechanisms line every conceivable underground mine assembly, including the ventilation ducts that work tirelessly to extract that ignitable coal dust.
In an underground mine, a vent tube is beneficial in dealing with the high concentration of gas emitted from the drilling site and borehole. Vent band, also known as vent tube rubber is used for wrapping around the ventilation tube, to seal the joint thus maintaining air pressure. Further, the vent band can be used to repair damage to the vent tube.
Given that the operation of underground coal mines poses a high number of risks of fire and explosion, materials used as vent band are required to be certified fire retardant and anti-static (FRAS). That means, they need to be able to control ignitability and flame propagation. Further, they also require the capability to reduce static electricity, which could lead to possible sparking.
To comply with the requirement, some manufacturers produce polyurethane systems with the ability to self-extinguish in the case of fire and also provides excellent antistatic protection. These materials have been documented to possess a highly durable, longer lasting, wear and abrasion resistance characteristic; and most importantly, they comply with all relevant Australian FRAS standards.