A mine operator’s failure to conduct adequate workplace examinations resulted in the death of a 21-year-old miner who was engulfed in a coal stockpile, according to a federal investigation.
U.S. Mine Safety and Health Administration investigators found that the mine operator didn’t conduct a workplace examination before miners began working which led to dangerous conditions around the stockpile going unnoticed.
Assigned to work in coal shed
Thomas Mitchell was a 21-year-old production utility miner at the CEMEX Construction Materials Knoxville Cement Plant mine in Knox County, Tennessee.
The mine’s plant uses a coal-fired kiln to process cement. Coal is brought to the plant via haul truck and is dumped in a coal shed. Miners use a front-end loader to dump coal onto the grizzly, located in the floor of the coal shed.
The grizzly is a metal grate designed to slow the flow of coal and prevent large chunks of coal or foreign objects from entering the hopper below. Coal is fed from the hopper onto a belt conveyor and transported to coal silos.
On Nov. 5, 2022, Mitchell was assigned to load rock into a hopper at the rock reclaim area and dump coal onto the grizzly in the coal shed.
At 1:54 a.m. Mitchell used a front-end loader to begin loading coal onto the grizzly. By 2:31 a.m., the coal silo was full, which activated the high-level alarm and automatically stopped the belt conveyor.
One of Mitchell’s co-workers restarted the belt conveyor to replenish the silo at 3:05 a.m. This caused a void to form as more coal built up over the grizzly.
Walking on stockpile caused coal to collapse and engulf him
Once he was finished loading coal onto the grizzly, Mitchell traveled to the rock reclaim area to begin loading rock, which he told co-workers he planned to do for about 45 minutes. A co-worker reminded him when his 45 minutes was up. Mitchell then drove the front-end loader to the coal shed, at 4:05 a.m.
Based on interviews and information gathered during the investigation, MSHA determined that Mitchell parked and exited the front-end loader at 4:10 a.m. and walked on the coal stockpile over the grizzly. Mitchell’s weight caused the bridged coal above the grizzly to collapse and engulf him.
There were no eyewitnesses to the incident.
Body found hours later
By 5:17 a.m., Mitchell’s co-workers went to look for him. Eventually, the front-end loader was found with its engine running, the cab door open and the bucket slightly raised over the coal stockpile. The search continued until the end of the shift and through the early part of the day shift.
At 7:20 a.m., Mitchell’s body was discovered when a miner used a front-end loader to remove coal over the grizzly. A supervisor called 9-1-1 minutes later. Emergency responders pronounced Mitchell dead at 8:15 a.m.
No workplace exams for more than a month
MSHA investigators found that the mine operator hadn’t conducted a workplace examination for more than a month before the incident occurred.
Coal was stockpiled 14 feet high along both sides of the narrow travel-way and above the grizzly with no separation to the back of the coal shed. These over-steepened and connected stockpiles were vulnerable to sloughing and the grizzly’s exact location couldn’t be determined.
The light above the grizzly wasn’t functioning, and there were no other signs indicating the location of the grizzly.
An adequate workplace examination would have identified these hazards.
Mine operator developed new procedures to address hazard
MSHA determined that the root causes for the incident were the mine operator’s failure to conduct workplace examinations as well as its failure to have procedures preventing miners from standing over drawholes without platforms or safety lines.
To avoid a similar incident from occurring, the mine operator has since:
- developed a procedure requiring a supervisor to conduct a minimum of two workplace examinations each shift, and
- trained miners on new procedures for working in the coal shed, including how to properly load coal on the grizzly and what to do if the miner has to exit the front-end loader.