Adani, which has battled opposition from green groups since work on the project began five years ago, will now need to resolve its financing, with banks under increased pressure not to provide loans for coal in particular.
Environmental campaigners say they hope two outstanding court cases can still stop India's Adani Enterprises Ltd from developing a A$10 billion ($7.6 billion) coal project, even after it received a key state government approval.
The granting of a mining lease by the state government marked another step in Adani's long-running bid for approval to mine and ship an estimated 11 million tonnes of coal reserves, building roads, power lines and pipelines to do so.
But activists - some 200 of which protested outside the Queensland parliament on Monday - say the ongoing federal court challenges could still throw Adani's plans into doubt.
Benedict Coyne, a lawyer for the Wangan and Jagalingou people, who have rejected a land use agreement with Adani, said he was surprised a decision had come while the cases were still in process.
"If it is found that the decision was not made lawfully, then any (further) decisions are called into question," he said.
Adani said in a statement on Sunday that it had a "clear and positive" commitment from the government and welcomed the approval as an important milestone.
The group said it expected appeals to be resolved in 2016, allowing construction to begin in 2017.
Adani, which has battled opposition from green groups since work on the project began five years ago, will now need to resolve its financing, with banks under increased pressure not to provide loans for coal in particular.
Several international banks have said they will not provide financing for coal mining in the Galilee Basin, while Standard Chartered and Commonwealth Bank of Australia pulled out of the project in August.
Adani has said tough market conditions should not put pressure on the project because most of its coal is already earmarked for Adani-owned power plants in India, rather than for sale on the open market.
