Simandou has faced delays due to legal disputes, political changes, and the challenges of building a 600 km rail and port infrastructure.
The American Exploration & Mining Association was joined by a coalition in filing a challenge last Friday in the Wyoming district court.
The world’s largest producer of uranium is increasing its mining tax on the nuclear fuel by at least 50% next year.
Portugal already has the largest copper mine in the European Union, operated by Lundin Mining.