Rio Tinto looks set to be granted more time to complete the largest rehabilitation exercise in the history of Australian mining.
Proposed laws introduced to federal parliament on Thursday allow the clean up of the Ranger uranium mine to breach the current 2026 deadline.
Minister for Resources Madeleine King said the bill is the first step to extend the miner's authority to keep working on the rehabilitation until the work is complete.
In the heart of Kakadu, the open cut mine run by Rio's subsidiary Energy Resources Australia began producing uranium oxide via acid leach extraction in 1981.
Operations ceased more than 30 years later but oxide continues to be sold on the world market, partly funding rehabilitation.
Uranium oxide from the mine has powered the world's nuclear power plants, under the Atomic Energy Act that gave ownership of the resource to the Commonwealth.
But remediation costs have doubled to $2.2 billion - more than twice earlier estimates - and work would need to run until the end of 2028, ERA warned earlier this year.
Ranger's pit, where backfilling began more than 25 years ago, was once 170 metres deep.
Tree planting has begun on what is now a large and flat surface area of almost 40 hectares.
The minister said the mine site must be restored to a condition similar to the surrounding Kakadu National Park.
"For such an environmentally, culturally and historically important region, only the highest standard of rehabilitation will do," Ms King said.
Failure would further harm Rio's reputation after it detonated Western Australia's 46,000-year-old Juukan Gorge rock shelters two years ago, devastating traditional owners and shocking many Australians.
The bill provides for some areas of the mine site to be handed back to the Mirarr Traditional Owners as soon as it is safe to do so.
Minister for Indigenous Australians Linda Burney said the proposed laws have the support of the Northern Land Council and Gundjeihmi Aboriginal Corporation which represent the Mirarr.
Although a full handover is still some years away, this legislation will give both ERA and the Mirarr a line of sight for the land's eventual rehabilitation and return, she said.
"Once this bill is passed, I will be able to start negotiations on a new land access agreement with the Mirarr Traditional Owners."
A new Rehabilitation Authority would also be established.
