A federal appeals court threw out a lower court injunction that kept Mosaic Co. from operating a Florida phosphate mine, the fertilizer producer said.

Last summer the Sierra Club environmental group sued to stop Mosaic from mining phosphate rock at its mine in South Fort Meade, Florida. The groups claims the surface mining process damages the Florida watershed.

The U.S. Army Corps of Engineers previously approved Mosaic's permit to operate the mine. Mosaic rival CF Industries  operates a similar mine nearby but has not been sued by environmental groups.

Last year the U.S. District Court for the Middle District of Florida put on hold Mosaic's ability to use its Corps of Engineers permit, effectively stopping production at the mine. In the latest ruling from the U.S. Court of Appeals for the 11th Circuit, judges lifted the injunction that kept Mosaic from using the permit. The judges also ordered the lower court to study whether the Corps "came to a rational permit decision," Mosaic said.

The injunction will not be fully lifted for 90 days in order to give the lower court time to study the case. "Obviously, we would have preferred that they affirm the (lower court) ruling," said Eric Huber, an attorney arguing the case for the Sierra Club. "But it was a procedural ruling and they said nothing about the merits of the opinion" that the permit should not have been issued.