Rio Tinto Alcan's Yarwun operation experienced a minor nitric acid spill yesterday.
A small spill of about one litre of acid occurred at the site, according to the Gladstone Observer.
No workers were affected by the incident, which was soon rectified by emergency services.
This is not the first spill at the Yarwun facility.
In 2011 the refinery reportedly experienced a spill of 25 000 litres of sulphuric acid.
The acid spill occurred during heavy rain, with most of it washed into the on-site storm water catchment system and into Boat Creek.
The QLD Department of Environment and Resources Management (DERM) found no evidence of environmental damage caused by the spill.
Rain and high tides apparently diluted the acid.
According to Rio Tinto’s early investigation, only 3000 litres of acid was spilled into the process area.
“The vast majority of this was contained on site and only a small amount of sulphuric acid and sea water mix was released into the creek,” a Rio Tinto spokesperson said.
A faulty drain valve believed to be the cause of the spill was immediately removed.