Dec 9 (Reuters) - Perpetua Resources PPTA.O said on Monday its Idaho unit has signed a non-binding agreement with private firm Sunshine Silver Mining & Refining to explore the processing of antimony, amid a brewing trade war between the U.S. and China over critical minerals.

Shares of Perpetua rose 7.4% in premarket trade.

Under the agreement, the companies will assess the technical potential for processing and refining antimony from Perpetua's Pentagon-backed Stibnite antimony and gold project at the Sunshine Mine Complex in Idaho.

Last week, China banned the export of antimony — a crucial element in defense, clean energy and semiconductor applications — and other minerals such as germanium and gallium to the U.S., after Washington's latest crackdown on China's chip sector.

"Stibnite Gold Project is the only identified domestic reserve of antimony, and with final federal decisions expected in a matter of weeks, Perpetua is ready to work with U.S. companies to help secure domestic production of antimony," Perpetua CEO Jon Cherry said.

Perpetua said it and Sunshine Silver expect to cater to 40% of U.S. domestic antimony demand.

The company expects to receive the permit for the Stibnite project, also backed by hedge fund manager John Paulson, by year-end.

(Reporting by Pooja Menon in Bengaluru; Editing by Sahal Muhammed)

((Pooja.Menon@thomsonreuters.com;))