North Carolina regulators have granted Piedmont Lithium's request for more time to provide information needed to complete the state's long-running review of the company's mine permit application.

The proposed mine, if built, would become one of North America's largest sources of lithium for electric vehicle batteries, but it has faced extensive opposition from neighbors worried about water, noise pollution and other potential problems.

Piedmont had been expected to provide North Carolina officials with information on 10 areas by the end of November. Company officials, though, asked in a letter dated November 16 for the deadline to be extended by 180 days to May 24, 2024.

Piedmont said it needed the additional time to study the use of a synthetic liner, rather than a clay liner, for a waste rock pit that would touch heights of roughly 152 m. North Carolina regulators, who approved Piedmont's request on November 21, have in recent years asked mining applicants to consider use of synthetic liners.

A Piedmont spokesperson said the company expects to provide the additional information well before May and it does not believe it will need more time to provide other information.

Piedmont first applied for the permit in August 2021. The state asked for additional information in October 2021 and in January 2022. The company's deadline to respond to the January 2022 request was extended twice. In May 2023, state regulators asked for more information within 180 days; that deadline has now been extended through next May.

Piedmont's failure to detail plans for residents of Gaston County, just west of Charlotte, prompted local officials to delay needed zoning changes.

During the North Carolina delay, Piedmont invested in Quebec-focused Sayona Mining and Ghana-focused Atlantic Lithium, deals that give it access to lithium from both companies.