The "overall partnership agreement" means the Somair mine in northern Niger could carry on working until 2040, 11 years beyond its currently expected closure, Mining Minister Hadiza Ousseini said.
Discussions focused on licensing arrangements and cost reduction in particular, she said.
Orano is the restructured successor to the state-owned Areva, which began uranium mining in the former French colony around 50 years ago, extracting raw material intended mainly for France's nuclear industry.
One of the company's mines, Cominak (for the Akokan Mining Company) closed in 2021.
The deal concerning Somair, whose name is derived from the Air Mining Company, includes a pledge by Orano to inject 26 billion CFA francs ($44 million) into education and other "priority" sectors in Niger, the company's CEO, Nicolas Maes, said.
However, the two sides agreed to postpone the start of mining at the northern site of Imouraren, which has estimated deposits of 200,000 tons of uranium -among the biggest in the world.
Operations should have started there in 2015 but were put on hold after the world price for uranium collapsed following the 2011 Fukushima disaster in Japan.
Ousseini said the partners were looking roughly at "a horizon of 10 years" for determining the feasibility of starting up mining at the site.
Niger Keeps Uranium Mine Open
FILE: Uranium ore is heap leached with sulfuric acid at Areva's Somair mine in Arlit. Taken Sept. 25, 2013.
NIAMEY - The government of Niger and French nuclear firm Orano on Thursday signed a deal to extend the operational life of the country's sole uranium mine.