The $22-billion Carmichael coal and rail project has secured approval for a permanent rail line and a temporary construction camp as hundreds protested against the mine in Melbourne.

Queensland's Coordinator-General has given "the latest, and final, secondary approval" for about 31.5 kilometres of permanent track, as well as the 300-bed camp.

The rail section approved will form part of the 389 kilometre heavy haul railway line from the mine in the Galilee Basin to the Abbot Point port.

The Carmichael mine, which will be Australia's largest coal mine, still needs a water licence approved and hopes to secure a Federal Government loan.

State Development Minister Dr Anthony Lynham said the approval was another milestone for the project.

"Adani has confirmed it will start construction next year," Dr Lynham said.

"North Queensland is about to see a new horizon, because these big projects will be a huge economic stimulus for the north."

The coordinator-general has given "the latest, and final" approval for Adani's Carmichael mine. ( Supplied: adanimining.com )

The Indian mining giant is expected to announce Townsville, about 200 kilometres from the Abbot Point port in north Queensland, as the project's headquarters.

Adani Group chairman Gautam Adani and Premier Annastacia Palaszczuk will meet in the city on Tuesday.

Townsville Mayor Jenny Hill said it would be a huge win for the region.

"We've got one of the highest unemployment rates in Australia," she said.

"These are the sort of projects that can support 2,000 to 3,000 jobs, not to mention the other jobs that come from the fact that so many people are employed."

The mine will consist of six open-cut pits and up to five underground mines, and will supply Indian power plants with enough coal to generate electricity for up to 100 million people.

The controversial project involves dredging 1.1 million cubic metres of spoil near the Great Barrier Reef Marine Park, which will then be disposed of on land.

Hundreds protest against mine in Melbourne

News of the mine's approval sparked protests in Melbourne on Monday.

More than 250 gathered at the rally, ahead of a meeting between Prime Minister Malcolm Turnbull and Mr Adani in the city later today.

The Australian Conservation Foundation's Paul Sinclair said the project could still be stopped.

"Every day that we stop Adani digging that coal is a day this planet is free from its pollution," he said.

"Every day that we stop Adani digging that coal, renewable energy grows stronger in this country."