Mining giant Glencore has announced the Mount Isa Mines Copper Smelter and the Townsville Copper Refinery can stay open until 2022.
The facilities were due to close in 2016 and 2017 respectively.
The announcement follows an agreement between the Swiss miner and the Queensland Government over new environmental licensing conditions.
North Queensland copper assets chief operating officer Mike Westerman said improved environmental practices were behind the decision.
"Back in 2011 when we made the decision to close the smelter, that was in conjunction with the State Government at the time, and we had a temporary environmental plan in place that gradually reduced our environmental emissions up until 2016," Mr Westerman said.
"During that five-year period we've been able to significantly improve our environmental performance to the [point] where the State Government is extremely happy with our environmental performance.
"The community of Mount Isa is happy with our performance and Glencore, as a global organisation, is also confident of our environmental performance, so all of those things aligned to allow us to operate post the 2016 closure date."
The facilities support 250 jobs in Mount Isa and another 180 to 200 in Townsville, as well as more than 800 indirect jobs which flow on from those operations.
Mr Westerman said Glencore would operate the two facilities as long as they were economically viable.
"For the employees there and for the company, that means we have to concentrate on the things that we control, which is our cost performance, our efficiency, our environmental performance," he said.
"If we can get those things right we can operate until 2022. The decision today gives us every opportunity to do that."
Mr Westerman added that Glencore would invest $60-70 million in the smelter for maintenance over the next seven years.
SMD Price at posting:
0.9¢ Sentiment: Hold Disclosure: Held
PHOTO: The Mount Isa Mines Copper Smelter was due to close in 2016, but can now stay open until 2022 thanks to new environmental licensing conditions.(ABC North West Queensland: Emily Bissland)