The activists involved in Brisbane's peak-hour anti-Adani protest say the road closures and public transport chaos on Friday will seem like "a minor inconvenience" compared to what they say will happen if the central Queensland mine goes ahead as planned.

The march closed George, Adelaide, Edward and Charlotte streets and was organised by Uni Students for Climate Justice and Movement Against Destruction, the same groups behind a similar protest on June 21 that occupied the Victoria Bridge.

Rally organiser Catherine Robertson said some activists wore hazmat suits to display the "crime scene" that would unfold in the Galilee Basin and Great Barrier Reef if the mine was not stopped.

"It was angry, it was loud and we occupied major intersections for quite some time," she said.