According to the NSW Resources Regulator, the vacuum truck was being used to remove explosives from two blast holes that had collapsed after heavy rain.
When the job was finished the shotfirer checked the truck then took it to the wash down bay for a clean.
Two days later the truck was at a different mine.
After it was used a worker took it to that site's wash down bay for cleaning, where he found an explosives GL booster and detonator in the sump.
The parts were confirmed to have come from the previous mine.
In the wake of the potentially explosive incident the regulator warned mine operators to always check lines and tanks in trucks working with explosives to make sure there were no explosive precursors from blast holes stuck inside.