Opponents of a northwest NSW coal mine have vowed to continue protesting, after human barricades stopped tree-clearing bulldozers entering the site.

Among them was first-time protester Raymond McLaren, who was fined $420 after spending most of Monday chained to an old car blocking a road at Whitehaven Coal's Maules Creek project, near Boggabri.

Police eventually cut the 75-year-old free at about 8pm (AEDT).

Mr McLaren opposes the mine despite the fact his Tamworth engineering firm builds equipment for the mining sector.

He says the open-cut mine will see the Leard State Forest completely destroyed.

"I spent the day pretty uncomfortable," he told AAP on Tuesday.

"But it's beautiful forest, it's a fantastic place for camping, probably one of the best in Australia."

Mr McLaren described his brush with the law as "a bit terrifying" but worthwhile if it raised awareness of the precious forest.

"It was a very meaningful thing we did there," he said.

"This environment is just so valuable."

Julie Macken of Greenpeace, one of the groups behind the protest, says there were six arrests at the blockade, with three of the protesters charged, and two fined.

Police confirmed the three have been charged with hindering with mining equipment were a man, 50, and two woman aged 21 and 22.

All three were granted conditional bail to appear in Narrabri Local Court on January 28.

Greenpeace will next target the ANZ AGM in Brisbane on Wednesday, over the bank’s involvement in the Maules Creek project.

In the most high-profile protest against Whitehaven to date, activist Jonathan Moylan will stand trial next year accused of issuing a hoax media release that wiped hundreds of millions off the company's value.

A Whitehaven spokesman on Monday said the Maules Creek project had passed a comprehensive, independent assessment process and protesters should respect the final judgment of authorities.

AAP