Vice president and general manager Denis Horgan told the Delta Optimist that the small fire, which occurred at about 12.30pm, originated on a conveyor belt on a loader of one of its two berths.
The flames were extinguished about 30 minutes later and no one was injured.
Horgan said repair work had begun and the berth would be idle until Wednesday.
It is the same berth that suffered damage on December 7 from a vessel crash.
About 100m of the causeway structure and conveyor belt infrastructure was repaired over several weeks before it reopened in February.
The same month, Westshore confirmed it would spend $C210 million ($US201 million) for a capital expenditure project to replace its three oldest stacker-reclaimers and make other improvements.
The phased project is projected to take four to five years.
Westshore is the largest coal export facility in North America.