Background
A Coal India Limited subsidiary operating an underground longwall coal mine in Jharkhand, India was replacing the main gate conveyor belt on its primary production panel. The conveyor was 650 meters long, 1,000mm wide, carrying 1,200 tonnes per hour of run-of-mine coal in an underground environment classified as gassy (seam gas present).
The mine's safety officer needed to confirm the FRAS belt specification before procurement.
Regulatory Requirements
Underground coal mines in India with gas classifications require conveyor belts to comply with DGMS (Directorate General of Mines Safety) circular requirements. The applicable requirements for this mine included:
- Belt must pass drum friction test (resistance to propagating fire from frictional heating)
- Electrical surface resistance: maximum 3 Γ 10βΈ ohms (antistatic requirement)
- Test certificates from an approved laboratory
The mine's previous belt had been a standard EP belt β a compliance issue that the incoming mine manager identified and sought to correct.
Specification Process
The mine's requirement was: - EP315 rating (adequate for the conveyor length and load) - 1,000mm width - FRAS compound covers - Top cover 8mm, bottom cover 4mm - Test certification for drum friction and electrical resistance
We supplied material test reports covering: - Drum friction test result: self-extinguishing within 0.5 seconds of flame removal, burn length 85mm (well within DGMS limits) - Surface electrical resistance: 2.1 Γ 10β· ohms (within the 3 Γ 10βΈ ohm requirement) - Tensile strength: 19.2 MPa (exceeds minimum) - Elongation at break: 430%
The mine's safety officer reviewed the certificates and confirmed they met the DGMS requirements for this specific mine's classification.
Installation Notes
The underground belt installation was performed during a planned panel maintenance stop. The FRAS belt was handled with the same equipment and procedures as a standard belt β no special handling was required. The splice was a vulcanized step splice as required for underground coal applications (mechanical fasteners are not acceptable for underground coal in India).
Operational Result
The belt ran for 14 months before the first unplanned stop β at that point a roller bearing failure (not belt-related) required attention. The belt itself showed normal even wear with no compliance-related issues. The mine's next planned maintenance assessment found the belt at approximately 55% of estimated life remaining.
Key Points
Compliance requires confirmed certification, not assumption. The previous standard belt had presumably been in use for years without incident β but it was a compliance violation. FRAS requirements exist because belt fires in gassy underground coal mines are a real and serious risk.
FRAS does not mean the belt cannot burn. FRAS specification ensures the belt self-extinguishes quickly when the flame source is removed. It does not make the belt fireproof. Fire detection and suppression systems remain essential in underground coal mines regardless of belt specification.
Test certificates must match the specific application's regulatory requirements. A drum friction certificate from a European standard test may or may not satisfy DGMS requirements β the mine safety officer needs to make this determination, not the belt supplier.
Elephant Rubber supplied the FRAS EP315 belt and test documentation for this project.