Eight young people aged from 13 to 17 - many of whom met during School Strike 4 Climate - argue that federal environment minister Sussan Ley should not allow the mine to proceed because she had a common law duty of care for young people and prevent climate change.

One of the eight students, Izzy Raj-Seppings, 13, said approval of the mine would make climate change worse and harm her generation in the future.

"We're trying to get the federal environment minister to prevent the Vickery coal mine going ahead because we believe she has a duty of care for young Australians and young people all over the world," Raj-Seppings reportedly told the ABC.

"I definitely have hope because if you look around, you can see all the incredible climate activists, young and old, all these people fighting for what's right.

"And we are making change."

Whitehaven Coal received NSW Independent Planning Commission approval to develop its proposed $607 million Vickery extension project near Gunnedah last month.

The primary approval follows a lengthy technical evaluation process for the project and a comprehensive program of community consultation and outreach, including a Multi-stage Public Hearing administered by the IPC during February 2019 and July 2020.

Whitehaven lodged a state significant development application in 2018 seeking to increase total coal extraction to 168 million tonnes or by 24.4%; increasing the peak annual extraction rate from 4.5 million tonnes to 10Mt; and increasing the disturbance area by 776 hectares.

It has also sought to build a coal handling and preparation plant at the project site, which would connect to the main Werris Creek-to-Mungindi railway line via a rail spur across the Namoi River flood plain.

A research note for the University of New South Wales' Climate Justice Project states that the Vickery coal mine extension, by itself, will produce about 390 million tonnes of carbon dioxide-equivalent greenhouse gas emissions over its lifetime.

Whitehaven declined to comment.