With NSW committed to net zero emissions by 2050, questions are being raised during the election campaign as to how this will be achievable with continued expansion of the region's coal mines.

An additional 52-million tonnes of run-of-mine coal will be extracted over approximately eight years, with operations to cease at the site in December 2030 - a 13-month extension to the company's existing development consent.

Approved in 2007 when its was known as the Anvil Hill Coal Project the mine began operations in 2010 and currently employs 400 people.

In its submission to the IPC Glencore said if the extension was refused the mine would most likely cease production in 2025 although it has approval to operate until 2029.

At such time it would then be rehabilitated. However early closure would result in the potential loss of $408 million of economic benefit to NSW.

In their meeting with the IPC the Muswelbrook Council's representatives said 'enough is enough' in opposing the extension.

Speaking on council's behalf barrister Craig Leggatt SC detailed a litany of serious problems with the mine's impacts on flora and fauna, water contamination, the social and economic future of the Shire, and Glencore's "uncharacteristically poor" provision of information about the project.

He said, "Muswellbrook Shire Council has a history of working collaboratively with coal mines in its local government area, and it's done that to achieve community outcomes that are beneficial to the community; however, the time has been reached, in the opinion of the council, with the Continued Operations Project that enough is enough."

"What I mean by that is council does not want the Continued Operations Project to proceed. Council wants the IPC as the consent authority to refuse to grant consent to the Continued Operations Project."

In its Statement of Reasons for Decision, the Commission noted the Project "represents a reasonable 'brownfield' extension of the existing Mangoola Coal Mine that would enable the economic and beneficial reuse of existing infrastructure and an orderly and economic use of land."

"Notwithstanding the concerns raised ... the Commission finds that on balance and when weighed against the impacts under the current policy and regulatory framework, the Project would generate net positive social and economic benefits for the local area, Hunter region and to NSW" it added.

The Project - anticipated to create 145 construction and 80 operational jobs, and provide ongoing employment for 400 workers - will use existing infrastructure including the Mangoola Mine Coal Handling and Processing Plant, rail loop and mining fleet and involve the development of a new haul road overpass which would also traverse Wybong Road and Big Flat Creek, to connect the Northern Extension Area with the Mangoola Mine.

Up to $129-million in mining royalties will be generated by the Project, the IPC stated.

The decision to approve the extension has been welcomed by Glencore who said they were pleased the project has successfully met every step of the NSW environmental assessment requirements and will enable mining to continue for a further five years to 2030.

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We look forward to a timely execution of Federal Government and Muswellbrook Shire Council approvals, a Glencore spokesperson said.

Also pleased with outcome were the CFMEU.

"This news comes as a great relief to the 400 directly employed mineworkers at Mangoola mine," said CFMEU Northern Mining and NSW Energy District President Peter Jordan.

"The extension will also create 200 additional jobs. While there are conditions to work through, the Commission has found the Mangoola extension to be in the public interest. It's a terrific outcome for workers and the community."