Millertown, NF — On Jan. 4, 2008, 18 workers at a Newfoundland copper and zinc mine were exposed to sulphur dioxide (SO2) gas as a result of a faulty gas monitoring sensor.
Employees at Teck Cominco’s Duck Pond Mine near Millertown, Nfld., were working about 250 metres underground when the smell of gas was detected. The workers evacuated the mine and were taken to a local health centre to be examined. However, no noticeable effects of exposure to the sulphide gas were detected.
The sulphur dioxide leak occurred after a routine development blast at the mine. When sulphide ore is blasted, dust from the blast can ignite and explode, producing sulphide gas. In this case, signals from a fixed underground gas detection unit were not reaching an above-ground monitoring system. On investigation, it was discovered a cable had been squashed by a piece of equipment, so no signal could be transmitted.
As well, the investigation showed that two other monitors were not working; as a result, these CO and NO2 sensors were sent back to the manufacturer. The company noted that they had just been installed in late December, 2007.
As a result of the incident, the company is planning to install an alarm system on the monitoring system which will sound an alarm if a reading is not received from any of the three sensors.